Defense Threat Reduction Agency 

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Fort Belvoir, VA 22060-6201 

DTRA-TR-17-003(R1) 

Prepared by: 

Leidos, Inc. 

For: 

Defense Threat Reduction Agency 

Radiation Dose Assessment for Military 

Personnel of the Enewetak Atoll Cleanup 

Project (1977–1980)

Revision 1

DISTRIBUTION A. Approved for public release; distribution is unlimited. 

April 2020 
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4. TITLE AND SUBTITLE

Radiation Dose Assessment for Military Personnel of the Enewetak 

Atoll Cleanup Project (1977–1980), Revision 1 

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

McKenzie-Carter, Michael A.1; Case, David R.1; Chehata, Mondher1; 

Falo, Gerald A.2; Fong, Show-Hwa1; Schaeffer, Dennis M1; Ronald L. 

Weitz1; Alleman, Lee A.3 

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

1. Leidos Inc., Reston, VA 

2. U.S. Army Public Health Center, Aberdeen Proving Ground, MD 

3. Defense Threat Reduction Agency, Fort Belvoir, VA 

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REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

Nuclear Technologies Department, Attn: Dr. Paul Blake 

Defense Threat Reduction Agency 

8725 John J. Kingman Road, Mail Stop 6201 

Fort Belvoir, VA 22060-6201 

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AGENCY REPORT NUMBER

DTRA-TR-17-003(R1) 

12. DISTRIBUTION AVAILABILITY STATEMENT

DISTRIBUTION A. Approved for public release; distribution is unlimited. 

13. SUPPLEMENTARY NOTES

14. ABSTRACT

During 1977–1980, the U.S. Department of Defense (DoD) conducted a radiological cleanup of Enewetak Atoll. The 

Enewetak Atoll Cleanup Project (ECUP) was carried out by a Joint Task Group established by the Defense Nuclear 

Agency, and involved the cumulative participation of approximately 6,000 military service members. This report provides

a revision to the technical basis for performing individualized radiation dose assessments for these ECUP veterans. The

technical approach, survey and monitoring data, and radiation dose estimation methods are described. Example dose 

assessments for hypothetical, high-sided example exposure scenarios result in doses that are well below applicable 

regulatory limits. Guidelines are provided for performing individual ECUP radiation dose assessments, including a 

questionnaire to gather pertinent information from participants. As discussed in this report, ECUP veteran exposures 

resulted in doses that are less than doses associated with adverse health effects. 

15. SUBJECT TERMS

Enewetak Atoll, Environmental Cleanup, Veterans Affairs, Radiation Dose Assessment 

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF 

ABSTRACT 

 U

18. NUMBER 

OF PAGES 

316 Pages 

19a. NAME OF RESPONSIBLE PERSON 

 Dr. Paul K. Blake 

a. REPORT

 

b. ABSTRACT

 

 

c. THIS PAGE

 

 

19b. TELEPONE NUMBER (Include area code ) 

 (703) 767-3433
1 

UNIT CONVERSION TABLE

U.S. customary units to and from international units of measurement*

U.S. Customary Units 

Multiply by 

International Units 

 Divide by†

Length/Area/Volume 

inch (in) 2.54 × 10–2 meter (m) 

foot (ft) 3.048 × 10–1 meter (m) 

yard (yd) 9.144 × 10–1 meter (m) 

mile (mi, international) 1.609 344 × 103 meter (m) 

mile (nmi, nautical, U.S.) 1.852 × 103 meter (m) 

barn (b) 1 × 10–28 square meter (m2) 

gallon (gal, U.S. liquid) 3.785 412 × 10–3 cubic meter (m3) 

cubic foot (ft3) 2.831 685 × 10–2 cubic meter (m3) 

Mass/Density 

pound (lb) 4.535 924 × 10–1 kilogram (kg) 

unified atomic mass unit (amu) 1.660 539 × 10–27 kilogram (kg) 

pound-mass per cubic foot (lb ft–3) 1.601 846 × 101 kilogram per cubic meter (kg m–3) 

pound-force (lbf avoirdupois) 4.448 222 newton (N) 

Energy/Work/Power 

electron volt (eV) 1.602 177 × 10–19 joule (J) 

erg 1 × 10–7joule (J) 

kiloton (kt) (TNT equivalent) 4.184 × 1012 joule (J) 

British thermal unit (Btu) 

(thermochemical) 1.054 350 × 103

joule (J) 

foot-pound-force (ft lbf) 1.355 818 joule (J) 

calorie (cal) (thermochemical) 4.184 joule (J) 

Pressure 

atmosphere (atm) 1.013 250 × 105 pascal (Pa) 

pound force per square inch (psi) 6.984 757 × 103 pascal (Pa) 

Temperature 

degree Fahrenheit (oF) [T(oF) − 32]/1.8 degree Celsius (oC) 

degree Fahrenheit (oF) [T(oF) + 459.67]/1.8 kelvin (K) 

Radiation 

curie (Ci) [activity of 

radionuclides] 3.7 × 1010 per second (s–1) [becquerel (Bq)] 

roentgen (R) [air exposure] 2.579 760 × 10–4coulomb per kilogram (C kg–1) 

rad [absorbed dose] 1 × 10–2joule per kilogram (J kg–1) [gray (Gy)] 

rem [equivalent and effective dose] 1 × 10–2joule per kilogram (J kg–1) [sievert (Sv)] 

*

Specific details regarding the implementation of SI units may be viewed at http://www.bipm.org/en/si/. 

†Multiply the U.S. customary unit by the factor to get the international unit. Divide the international unit by the factor to get the 

U.S. customary unit. 
2 

Acknowledgments

This work was conducted through the cooperation of Enewetak Atoll cleanup veterans, 

the Dose Assessment and Recording Working Group (DARWG), the Department of Energy 

National Nuclear Security Administration (DOE/NNSA), and the Defense Threat Reduction 

Agency (DTRA)’s Nuclear Test Personnel Review (NTPR) Program Team. The authors 

gratefully acknowledge the support of the following individuals: 

DTRA NTPR Team 

Paul K. Blake, CAPT, MSC, USN (ret), DTRA 

James D. Franks, LCDR, MSC, USN, DTRA 

Lee A. Alleman, LCDR, MSC, USN, USSOCOM 

Daniel N. Mannis, LCDR, MSC, USN (ret), DTRA 

Bruce L. Murray, Engility (ret) 

Dea A. Hunt, DTRA (DTRIAC) 

Brian K. Malik, CACI 

Nancy F. Wolejsza, CACI 

Brian Morgan, CACI 

Jean Ponton, CACI 

Mike Harding, CACI 

Stephen D. Egbert, Leidos 

Enewetak Cleanup Veterans 

Robert N. Cherry, COL, USA (ret) 

Edward A. Tupin, CAPT, USPHS (ret) 

National Nuclear Security Agency, Nuclear Testing Archive 

Martha E. DeMarre, MSTS, LLC 

U.S. Army 

John P. Cuellar, USA, COL, MSC, U.S. Army Medical Command 

William S. Harris, U.S. Army Dosimetry Center 

DARWG 

R. Jeff Marro, CAPT, MSC, USN (ret) 
3 

Table of Contents

Acknowledgments........................................................................................................................... 2

Table of Contents ............................................................................................................................ 3

List of Figures ............................................................................................................................... 10

List of Tables ................................................................................................................................ 12

Section 1. Introduction .................................................................................................................. 21

1.1 Background ........................................................................................................... 22

1.2 Veterans’ Concerns ............................................................................................... 23

1.3 Purpose and Scope ................................................................................................ 24

1.4 Radiological Quantities ......................................................................................... 24

1.5 Technical Approach .............................................................................................. 24

Section 2. Enewetak Atoll and Cleanup Project ........................................................................... 27

2.1 Enewetak Atoll Setting ......................................................................................... 27

2.2 Use of Enewetak Atoll for Nuclear Testing .......................................................... 27

2.3 Enewetak Cleanup Project Summary.................................................................... 30

2.4 Cleanup Basis and Strategy .................................................................................. 32

2.5 Functional Organization of the Population of Interest .......................................... 36

Section 3. Radiological Aspects of the Enewetak Atoll Cleanup Project ..................................... 38

3.1 Radiological Condition of Enewetak Atoll Prior to Cleanup Activities ............... 38

3.2 Radiation Safety Program and Radiological Controls .......................................... 38

3.2.1. Radiation Safety Program ......................................................................... 39

3.2.2 Radiological Controls ............................................................................... 41

3.3 Identification and Resolution of Radiological Control Issues .............................. 46

3.3.1. Film Badge Issues ..................................................................................... 46

3.3.2. Inoperable Air Samplers ........................................................................... 46

3.3.3. Availability of Personal Protective Equipment ......................................... 46

3.3.4. High Air Sampler Readings from Natural Radon ..................................... 47

3.3.5. High Individual Film Badge Readings ..................................................... 48
4 

Section 4. Radiological Survey and Monitoring ........................................................................... 49

4.1 External Radiation ................................................................................................ 49

4.2 Soil Survey ............................................................................................................ 53

4.3 Debris Survey........................................................................................................ 53

4.4 Air Monitoring ...................................................................................................... 56

4.5 Lagoon and Ocean Water ...................................................................................... 57

4.6 Lagoon Sediments ................................................................................................. 59

4.7 Food and Drinking Water ..................................................................................... 60

4.7.1. Local Foods ............................................................................................... 60

4.7.2. Drinking Water ......................................................................................... 64

4.8 Personnel Dosimetry (Film Badge, TLD) ............................................................. 65

4.9 Bioassay ................................................................................................................ 66

4.9.1. Nasal Smears ............................................................................................. 66

4.9.2. Urine Bioassay .......................................................................................... 67

Section 5. Sources, Pathways and Scenarios of Radiation Exposure ........................................... 69

5.1 Potential Sources of Radiation Exposure .............................................................. 69

5.1.1. Contaminated Soil ..................................................................................... 69

5.1.2. Soil Slurry ................................................................................................. 70

5.1.3. Contaminated Debris ................................................................................ 71

5.1.4. Contaminated Concrete Structures ........................................................... 71

5.1.5. Lagoon Water and Sediment ..................................................................... 72

5.1.6. Other Sources ............................................................................................ 72

5.1.7. Drinking Water and Food ......................................................................... 73

5.2 Exposure Pathways for Dose Assessment ............................................................ 74

5.2.1. Exposure of the Whole Body to Radiation from External Sources .......... 74

5.2.2. Exposure of the Skin to Radiation from External Sources ....................... 75

5.2.3. Exposure of Organs and Tissues to Radiation from Internal Sources ...... 75

5.3 Participant Activities and Potential Exposure to Radiation .................................. 75

5.3.1. Soil Cleanup .............................................................................................. 77

5.3.2. Debris Cleanup.......................................................................................... 82

5.3.3. Radiological Support ................................................................................ 88

5.3.4. Southern Islands (except Enewetak) ......................................................... 93
5 

5.3.5. Project Support on Residence Islands – Enewetak ................................... 94

5.3.6. Project Support on Residence Island – Lojwa .......................................... 95

5.3.7. Intra-Atoll Transport ................................................................................. 95

5.3.8. Pre-cleanup Mobilization and Demobilization ......................................... 96

5.3.9. Unexploded Munitions Recovery and Disposal ....................................... 98

Section 6. External Radiation Dose Assessment Methods ......................................................... 100

6.1 Dosimetry Records.............................................................................................. 100

6.1.1. Sources of Dose Records ........................................................................ 100

6.1.2. DD Form 1141 ........................................................................................ 100

6.1.3. ECUP Dosimetry Data ............................................................................ 101

6.1.4. Administrative Doses .............................................................................. 101

6.2 External Dose Estimation Methods .................................................................... 103

6.2.1. Soil Cleanup ............................................................................................ 103

6.2.2. Debris Cleanup........................................................................................ 108

6.2.3. External Dose from Lagoon Water and Sediments ................................. 111

6.3 Skin Dose ............................................................................................................ 112

6.3.1. Skin Dose from Dermal Contamination ................................................. 112

6.3.2. Skin Dose from External Non-Contact Sources of Radiation ................ 116

6.3.3. Uncertainties and Upper-bound Skin Doses ........................................... 117

6.4 Uncertainties and Upper-bound External Doses ................................................. 119

6.4.1. Uncertainty in Reconstructed External Doses ........................................ 120

6.4.2. Total Bias and Uncertainty in Film Badge Doses ................................... 120

6.4.3. Uncertainty in TLD Doses ...................................................................... 123

6.4.4. Method for Calculating Total Doses and Total Upper Bound External 

Doses .................................................................................................. 124

Section 7. Internal Radiation Dose Assessment Methods .......................................................... 125

7.1 Inhalation of Suspended Soil .............................................................................. 125

7.2 Incidental Ingestion of Soil and Dust.................................................................. 130

7.3 Incidental Ingestion of Lagoon and Ocean Water .............................................. 132

7.4 Ingestion of Food and Drinking Water ............................................................... 133

7.4.1. Consumption of Local Food ................................................................... 133

7.4.2. Ingestion of Drinking Water ................................................................... 135
6 

7.5 Puncture Wounds and Cuts ................................................................................. 136

7.6 Uncertainties and Upper-bound Internal Doses .................................................. 136

Section 8. Example Radiation Dose Assessment Results and Discussion .................................. 137

8.1 Example Scenario #1: Soil Cleanup Personnel ................................................... 137

8.2 Example Scenario #2: Debris Cleanup ............................................................... 139

8.2.1. External Dose Assessment—Debris Cleanup Scenario .......................... 139

8.2.2. Internal Dose Assessment—Debris Cleanup Scenario ........................... 140

8.3 Example Scenario #3: Navy Boat Transportation Team .................................... 141

8.3.1. External Dose Assessment—Boat Transportation Team ........................ 142

8.3.2. Internal Dose Assessment—Boat Transportation Team ......................... 144

8.4 Example Scenario #4: Air Force Duty on Enewetak in 1965 ............................. 145

8.4.1. External Dose Assessment for Air Force Personnel in 1965 .................. 147

8.4.2. Internal Dose Assessment for Air Force Personnel in 1965 ................... 149

8.5 Example Calculation for Skin Dose from Dermal Contamination and External 

Exposure ............................................................................................................. 151

Section 9. Guidelines for Individualized Radiation Dose Assessments ..................................... 154

9.1 Collection of Veteran-Specific Information ....................................................... 154

9.2 Individualized Dose Assessment for ECUP Veterans ........................................ 154

Section 10. Summary and Conclusions ...................................................................................... 156

Section 11. References ................................................................................................................ 159

A P P E N D I C E S .............................................................................................................. 168

Appendix A. Operational Milestones and Major Activities of the Enewetak Cleanup Project .. 169

A-1. Enewetak Cleanup Project Milestones................................................................ 169

A-2. Major Enewetak Cleanup Activities ................................................................... 170

Appendix B. Radiation Monitoring Data .................................................................................... 183

B-1. Environmental TLD Results ............................................................................... 183

B-2. Average TRU Soil Activity Concentrations – Excised Soil Disposed in Cactus 

Crater and Dome ................................................................................................. 196

B-3. Example Weekly Air Sampling and TLD Data Summaries Extracted from a CJTG 

Situation Report (SITREP) ................................................................................. 198

Appendix C. Dose Calculation Methods .................................................................................... 200
7 

C-1. External Dose Calculations ................................................................................. 200

C-1.1. External Dose from Contaminated Soil .................................................. 200

C-1.2. External Dose from other Sources .......................................................... 201

C-1.3. External Dose on Residence Islands ....................................................... 201

C-1.4. External Dose from Seawater Immersion ............................................... 202

C-1.5. External Dose from Sediment ................................................................. 202

C-1.6. Total External Dose and Upper-bound Doses ........................................ 203

C-2. Internal Dose Calculations .................................................................................. 205

C-2.1. Inhalation of Suspended Soil .................................................................. 205

C-2.2. Incidental Ingestion of Soil and Dust...................................................... 207

C-2.3. Consumption of Local Food ................................................................... 207

C-2.4. Total Internal Dose and Upper-bound Doses.......................................... 207

C-3. Skin Dose Calculations ....................................................................................... 212

C-3.1. Skin Dose from Dermal Contamination ................................................. 212

C-3.2. Skin Dose from External Sources of Radiation ...................................... 213

C-3.3. Total Skin Dose and Upper-bound Doses ............................................... 214

Appendix D. Analysis of TLD Dose Uncertainties .................................................................... 215

D-1. Introduction ......................................................................................................... 215

D-2. Zero Offset .......................................................................................................... 215

D-3. Truncation of Display Digit ................................................................................ 215

D-4. Performance Testing Limits ................................................................................ 215

D-5. Combining Sources of Error ............................................................................... 216

D-6. TLD Dose Uncertainty ........................................................................................ 217

Appendix E. Resuspension of Soil Contaminants ...................................................................... 219

E-1. Resuspension Factor Method .............................................................................. 219

E-2. Mass Loading Method ........................................................................................ 219

E-3. Relationship between Mass Loading and Resuspension Factor ......................... 220

E-4. Resuspension Factors Estimated for ECUP Aggregate Hauling Activity .......... 222

Appendix F. Respiratory Protection Factors ............................................................................... 224

Appendix G. Soil Concentrations of TRU Radionuclides .......................................................... 230

G-1. Radionuclide Concentrations in Excised soil ..................................................... 230
8 

G-2. Radionuclide Concentrations in Undisturbed soil .............................................. 231

G-3. Recommended TRU:Am-241 Ratios for Undisturbed Soil ................................ 234

G-4. Use of TRU:Am-241 Ratios ............................................................................... 234

Appendix H. List of Standing Operating Procedures and Enewetak Atoll Instructions for 

Radiological Operations at ECUP ......................................................................... 236

Appendix I. Questionnaire for Radiation Dose Assessment for Veterans of the Enewetak 

Cleanup Project (1977–1980) ................................................................................ 238

Appendix J. Lagoon and Ocean Water Activity Concentrations ................................................ 253

Appendix K. Validation of the Methodology for Estimating External Doses Associated with 

Handling Contaminated Debris during the Enewetak Cleanup Project ................. 256

K-1. Introduction ......................................................................................................... 256

K-1.1. Background ............................................................................................. 256

K-1.2. Purpose .................................................................................................... 256

K-1.3. Scope and Objectives .............................................................................. 256

K-2. Methodology for Estimating and Comparing Debris Exposure Rates................ 257

K-2.1. Debris Exposure Rate Data ..................................................................... 257

K-2.2. Representative Exposure Distances and Debris Pile Size....................... 257

K-2.3. Estimation of Mean Debris Exposure Rates ........................................... 257

K-2.4. Comparison of Mean Debris and Island-Average Exposure Rates ........ 260

K-3. Results and Discussion ....................................................................................... 260

K-3.1. Mean Contaminated Debris Exposure Rates .......................................... 260

K-3.2. Comparison of Mean Debris Exposure Rates with Island-average 

Exposure Rates........................................................................................ 261

K-4. Conclusions and Recommendations ................................................................... 262

Appendix L. Development of Beta-Gamma Dose Ratios for Skin Dose Assessments for 

Participants in the Enewetak Cleanup Project ....................................................... 291

L-1. Introduction ......................................................................................................... 291

L-1.1. Background ............................................................................................. 291

L-1.2. Purpose and Objectives ........................................................................... 291

L-2. Methodology ....................................................................................................... 291

L-2.1. Interim Beta-gamma Dose Ratio ............................................................ 291

L-2.2. Additional Beta-gamma Dose Ratios...................................................... 295

L-3. Results and Discussion ....................................................................................... 297
9 

L-3.1. Interim Beta-gamma Dose Ratio ............................................................ 297

L-3.2. Additional Beta-gamma Dose ratios for ECUP ...................................... 297

L-4. Conclusions ......................................................................................................... 299

Appendix M. Assessment of Internal Doses from Local Food Consumption by Participants in the 

Enewetak Cleanup Project ..................................................................................... 301

M-1. Introduction ......................................................................................................... 301

M-1.1. Background ............................................................................................. 301

M-1.2. Purpose and Objectives ........................................................................... 301

M-2. Methodology ....................................................................................................... 301

M-2.1. Dose Calculation Method ....................................................................... 301

M-2.2. Activity Concentrations in Edible Parts of Local Foods ........................ 302

M-2.3. Parameter Values and Assumptions........................................................ 304

M-2.4. Uncertainty .............................................................................................. 305

M-3. Results and Discussion ....................................................................................... 305

M-4. Conclusions ......................................................................................................... 307

Abbreviations, Acronyms and Symbols ..................................................................................... 311
10 

List of Figures

Figure 1. Radiation dose assessment development and implementation process ........................ 26

Figure 2. Enewetak Atoll islands and nuclear detonation sites (DNA, 1981) ............................. 28

Figure 3. Joint Task Group organization (DNA, 1981) ............................................................... 33

Figure 4. Lagoon disposal sites .................................................................................................... 35

Figure 5. Controlled Island Access Form – Sample for Runit, July 1979, with personally 

identifiable information redacted ............................................................................... 42

Figure 6. Example of urine bioassay report (some information redacted) .................................. 68

Figure 7. Example of partial DD Form 1141, with personally identifiable information redacted

 ................................................................................................................................. 102

Figure B-1. Example weekly summaries of air sampling and TLD results extracted from CJTG 

Enewetak Cleanup SITREP No 66, week ending August 20, 1978 ........................ 199

Figure F-1. Protection factors for respirators (USNRC, 1976) .................................................. 226

Figure G-1. Estimated soil activity concentration of Am-241 as a function of assumed 

TRU:Am-241 ratio (Pu-239+240 = 8.7 pCi g−1) ..................................................... 233

Figure G-2. Effect of TRU:Am-241 ratio on organ inhalation doses ........................................ 233

Figure J-1. Location, identification, and sampling depth of 55-liter water samples (AEC 1973a, 

Figure 79) ................................................................................................................. 253

Figure K-1. Exposure rate as a function of distance from radiation sources ............................. 259

Figure I-1. Measured radiation exposure rates on Ruby ...................................................... 264

Figure I-2. Measured radiation exposure rates on Sally No. 1 ............................................ 265

Figure I-3. Measured radiation exposure rates on Sally No 2 ............................................. 266

Figure I-4. Measured radiation exposure rates on Pearl No. 1 ............................................ 267

Figure I-5. Measured radiation exposure rates on Pearl No. 2 ............................................ 268

Figure I-6. Measured radiation exposure rates on Yvonne No. 1 ........................................ 269

Figure I-7. Measured radiation exposure rates on Yvonne No. 2 ........................................ 270

Figure I-8. Measured radiation exposure rates on Yvonne No. 3 ........................................ 271

Figure I-9. Measured radiation exposure rates on Yvonne No. 4 ........................................ 272

Figure I-10. Measured radiation exposure rates on Yvonne No. 5 ...................................... 273

Figure I-11. Measured radiation exposure rates on Janet No. 1 .......................................... 274

Figure I-12. Measured radiation exposure rates on Janet No. 2 .......................................... 275

Figure I-13. Measured radiation exposure rates on Janet No. 3 .......................................... 276

Figure I-14. Measured radiation exposure rates on Janet No. 4 .......................................... 277
11 

Figure I-15. Measured radiation exposure rates on Janet No. 5 .......................................... 278

Figure I-16. Measured radiation exposure rates on Janet No. 6 .......................................... 279

Figure I-17. Measured radiation exposure rates on Janet No. 7 .......................................... 280

Figure L-1. Values of RRβ/γ(t,h) for the time-extended and weathered beta-gamma dose ratios as 

a function of time ..................................................................................................... 296

Figure L-2. Calculated ECUP beta-gamma dose ratios ............................................................. 298
12 

List of Tables

Table 1. Compendium of island names and corresponding site names ....................................... 29

Table 2. Military Service component and DNA/JTG staffing of the Enewetak cleanup 

population of interest.................................................................................................... 37

Table 3. Personnel radiation protection levels ............................................................................. 43

Table 4. Summary of exposure rates at 1 meter above the surface .............................................. 50

Table 5. Net average exposure rates by location and monitoring period derived from 

environmental TLDs posted on selected islands ....................................................... 51

Table 6. Soil concentration data, surface to 15 cm depth soil samples, from the 1972 radiological 

survey ......................................................................................................................... 54

Table 7. Exposure rates measured at contact on islands with contaminated debris .................... 56

Table 8. Summary of air sampling data for Enjebi (Norton, 1980) ............................................. 57

Table 9. Summary of air sampling data collected throughout the Enewetak Cleanup Project .... 57

Table 10. Radionuclide activity concentrations in lagoon water samples ................................... 58

Table 11. Radionuclide activity concentrations in ocean water samples near Enewetak Atoll ... 58

Table 12. Mean activity concentrations of Cs-137 and Pu-239 in surface water samples collected 

from the four quadrants of the lagoon ....................................................................... 59

Table 13. Mean radionuclide activity concentrations in Enewetak Lagoon sediments ............... 59

Table 14. Activity concentration of radionuclides in coconut meat at Enewetak Atoll .............. 61

Table 15. Activity concentrations of radionuclides in coconut milk at Enewetak Atoll .............. 62

Table 16. Activity concentrations of radionuclides in coconut crab at Enewetak Atoll .............. 62

Table 17. Activity concentrations of radionuclides in clams at Enewetak Atoll ......................... 63

Table 18. Average activity concentrations of radionuclides in the edible part of local foods at 

Enewetak Atoll that were potentially consumed by cleanup participants ................. 64

Table 19. Activity concentrations in drinking water from Enewetak and Enjebi Islands ........... 65

Table 20. Summary of personnel dosimetry (DNA, 1981) .......................................................... 66

Table 21. Results of nasal smears ................................................................................................ 66

Table 22. Summary of urine bioassay results .............................................................................. 67

Table 23. Tasks, activities and sources of exposure – Soil Cleanup Project Component ........... 78

Table 24. Tasks, activities and sources of exposure – Debris Cleanup Project Component ....... 84

Table 25. Tasks, activities and sources of exposure – Radiological Support Project Component

 ................................................................................................................................... 89

Table 26. Tasks, activities and exposure pathways – Southern Islands Project Component....... 93
13 

Table 27. Parameter values and assumptions for estimating external doses from contaminated 

soil ............................................................................................................................ 105

Table 28. Averaging methods to determine exposure rates or soil activity concentrations for 

scenarios where ECUP veterans worked on multiple islands .................................. 106

Table 29. Time spent outdoors and indoors on residence islands.............................................. 107

Table 30. Comparison of mean contaminated debris exposure rates and island-average exposure 

rates .......................................................................................................................... 109

Table 31. ECUP participant debris cleanup volumes at Enewetak Atoll .................................. 110

Table 32. Parameter values and assumptions for skin dose from dermal contamination .......... 113

Table 33. Recommended dermal contamination dose coefficients for Co-60, Sr/Y-90, and Cs137 (for beta dose) ................................................................................................... 114

Table 34. Recommended values for beta SDMF ....................................................................... 114

Table 35. Recommended dermal contamination dose coefficients for Pu-239/240 and Am241(for alpha dose) .................................................................................................. 115

Table 36. Recommended values for the interception and retention fraction ............................. 116

Table 37. Parameter values and assumptions for skin dose from external non-contact radiation

 ................................................................................................................................. 117

Table 38. Beta-to-gamma dose ratio for external non-contact radiation sources for all islands at 

Enewetak Atoll ........................................................................................................ 117

Table 39. Average film badge laboratory uncertainty factors for various dose ranges ............. 121

Table 40. Bias and uncertainty factors for various sources of error for film badge dosimetry . 122

Table 41. Lowest reliable film badge doses............................................................................... 122

Table 42. Upper-bound uncertainty factor as a function of participant TLD reading ............... 124

Table 43. Parameter values and assumptions for estimating internal doses from inhalation of 

suspended soil .......................................................................................................... 126

Table 44. Estimated average activity concentration of contaminated soil excised and moved to 

Cactus Crater and dome ........................................................................................... 127

Table 45. ECUP personnel protection levels and respiratory protection factors ....................... 127

Table 46. Parameter values and assumptions for estimating internal doses from the incidental 

ingestion of contaminated soil and dust................................................................... 131

Table 47. Parameter values for estimating ingestion doses from eating local foods ................. 134

Table 48. Estimated dose per serving from the consumption of local foods ............................. 134

Table 49. Upper-bound doses per serving from the consumption of local foods ....................... 135

Table 50. Task durations assumed for a maximized exposure scenario for a soil cleanup worker

 ................................................................................................................................. 138
14 

Table 51. Exposure parameter values and assumptions for estimating external dose in the debrishandling example scenario ...................................................................................... 140

Table 52. Exposure parameter values and assumptions for estimating internal dose in the debrishandling example scenario ...................................................................................... 142

Table 53. Dosimetry record for the Navy Boat Transportation example scenario .................... 143

Table 54. Key external exposure parameter values and assumptions for the Boat Transportation 

Team example scenario ........................................................................................... 144

Table 55. Key internal exposure parameter values and assumptions for the Boat Transportation 

Team example scenario ........................................................................................... 146

Table 56. External dose parameter values and assumptions for the 1965 example scenario .... 148

Table 57. Internal dose parameter values and assumptions for the 1965 example scenario ..... 150

Table 58. Parameter values used for the example skin dose calculation ................................... 151

Table 59. Example dermal activity concentrations at Kirunu (Clara) for skin dose calculations

 ................................................................................................................................. 152

Table 60. Example skin doses for one 12-hour exposure .......................................................... 152

Table A-1. Major ECUP cleanup activities for debris, soil, and equipment/facility ................. 171

Table B-1. Environmental radiation exposure and exposure rates measured with TLDs on islands 

of Enewetak Atoll .................................................................................................... 184

Table B-2. Estimated average TRU activity of excised soil disposed in Cactus Crater and dome

 ................................................................................................................................. 196

Table B-3. Estimated TRU activity of excised soil disposed in Cactus Crater ......................... 197

Table B-4. Estimated TRU activity of excised soil disposed in Cactus dome .......................... 197

Table C-1. Dose coefficients for estimating external exposure to contaminated sediment ....... 203

Table C-2. Inhalation dose coefficients ..................................................................................... 209

Table C-3. Ingestion dose coefficients....................................................................................... 210

Table D-1. Upper-bound uncertainty factor as a function of TLD reading ............................... 217

Table E-1. Mass loading values and resuspension factors for representative types of ECUP soil 

disturbances ............................................................................................................. 221

Table E-2. Air concentrations, resuspension factors, and mass loading values associated with 

aggregate hauling ..................................................................................................... 223

Table F-1. Personnel protection levels and respiratory protection for ECUP ........................... 225

Table F-2. Assigned protection factors for respirators (USNRC, 2017) ................................... 228

Table G-1. Comparison of inhalation doses (bone surface) using two different assumptions for 

TRU and other radionuclide soil content ................................................................. 232

Table G-2. Am-241 soil concentrations in undisturbed soil for all islands calculated using 

TRU:Am-241 ratios ................................................................................................. 235
15 

Table H-1. Standing Operating Procedures and Enewetak Atoll Instructions ........................... 236

Table J-1. Sample characteristics and activity concentrations of Enewetak Atoll lagoon, crater, 

and ocean water samples ......................................................................................... 254

Table K-1. Contaminated debris exposure rates measured at contact and calculated at 10 ft ... 261

Table K-2. Comparison of mean calculated exposure rates from contaminated debris data and 

island-average exposure rates from 1972 aerial survey ........................................... 261

Table II-1. Radiation exposure rates on Ruby ..................................................................... 282

Table II-2. Radiation exposure rates on Sally ...................................................................... 282

Table II-3. Radiation exposure rates on Pearl ...................................................................... 283

Table II-4. Radiation exposure rates on Yvonne ................................................................. 283

Table II-5. Radiation exposure rates on Janet ...................................................................... 286

Table III-1. Estimated average sizes of contaminated debris piles ...................................... 290

Table III- 2. Comparison of calculated debris average and island-average exposure rates . 290

Table L-1. Time-extended NTPR beta-gamma dose ratios ....................................................... 293

Table L-2. Weathering reduction factors ................................................................................... 295

Table L-3. Time-extended and weathered beta-gamma dose ratios .......................................... 295

Table L-4. Values of RRβ/γ(30,h) for the time-extended and weathered beta-gamma dose ratios

 ................................................................................................................................. 297

Table L-5. Beta-gamma dose ratios calculated for ECUP skin dose assessments ..................... 298

Table L-6 Reference heights of body locations from surface .................................................... 299

Table M-1. Average activity concentration of key radionuclides in the edible part of local foods 

at Enewetak Atoll .................................................................................................... 303

Table M-2. Parameter values for estimating ingestion doses from eating local foods .............. 304

Table M-3. Estimated doses per serving from the consumption of local foods ........................ 306

Table M-4. Upper-bound doses per serving from the consumption of local foods ................... 307

Table I-1. Total internal organ doses from potential local food consumption by ECUP 

participants ......................................................................................................... 309

Table I-2. Total upper-bound internal organ doses from potential local food consumption by 

ECUP participants ............................................................................................. 310
16 

Revision Notes

This revision updates and expands technical information and guidance in the original 

version of DTRA Technical Report DTRA-TR-17-003, dated April 13, 2018. Many of the 

revisions are driven by responses to questionnaires from veterans of the Enewetak Cleanup 

Project (ECUP), and information and data recently compiled from project documentation. 

The revision extends the original report to include three new appendices that address 

three technical issues: (1) validating the method for estimating doses from handling 

contaminated debris; (2) assessing internal doses from the possible consumption of local foods 

by ECUP participants; and (3) calculating height-specific beta skin doses for non-contact 

exposure to contaminated soil using newly estimated beta-to-gamma dose ratios for ECUP dose 

assessments. The information in these new appendices is summarized in the body of the report in 

Sections 6 and 7. Additions and minor revisions of dose assessment parameter values are made 

in the text and tables in Sections 6, 7, and 8, and other appendices of the original technical report. 

The example radiation dose assessments included in Section 8 are revised by applying updated 

default parameter values and assumptions discussed in Section 6 and 7. Other relevant changes 

are made in Sections 2, 3, and 4. 

The dose assessment equations and text of Appendix C are revised to incorporate updated 

information and revised equations. Specific improvements in dose reconstruction methods in this 

revision include: revised analysis of activity concentrations in lagoon and ocean water to assess 

exposure from swimming (Sections 6.2.3 and 7.3, and new Appendix J); estimation of 

consumption of local foods (Section 7.4 and new Appendix M); inclusion of additional 

radionuclides in soil for dose assessments for individuals exposed in the 1960s timeframe 

(Sections 3.1 and 8.4); guidance on the use of Controlled Island Access forms for determining 

respiratory protection levels; and guidance for consideration of dermal soil loading when 

estimating skin doses from dermal contamination (Section 6.3.1). Uncertainties in doses that are 

based on TLD readings are revised and further discussed in Section 6.4.3 with details provided in 

revised Appendix D. The entries in Table A-1 are rearranged to follow a chronological order by 

the start date of each project activity. 

In addition, numerous editorial changes are made, and tables, figures, and references are 

updated as appropriate. Text is clarified where needed and sub-sections are added to improve the 

report organization. 

The conclusions reached in this revision are unchanged from those in the original version 

of the report. This Technical Report, DTRA-TR-17-003(R1), supersedes the original version 

dated April 13, 2018. 
17 

Executive Summary

This report documents the technical basis for performing individualized radiation dose 

assessments (RDA) for veterans who participated in the cleanup of Enewetak1 Atoll from 1977 

to 1980. The report is a revision of the technical report published in April 2018 by the Defense 

Threat Reduction Agency (DTRA). A summary of revisions and updates is given in the 

“Revision Notes” included in this report. 

Approximately 6,000 military service members of the United States Department of 

Defense (DoD) participated in the Enewetak Atoll Cleanup Project (ECUP) as part of the 

radiological cleanup, rehabilitation, and resettlement of Enewetak Atoll in the Marshall Islands. 

To implement this effort, DoD established a Joint Task Group (JTG) within the Defense Nuclear 

Agency (DNA) and initiated the cleanup project, as authorized by Congress (Congress, 1977). 

Enewetak Atoll was one of two primary locations in the Pacific Ocean where the United 

States conducted atmospheric tests of nuclear devices from 1946 to 1958 (DNA, 1981). 

Radioactive contamination from the nuclear detonations remained at Enewetak Atoll after testing 

ended. During the early 1970s, previous residents of the atoll, who had been relocated prior to 

the start of testing, expressed interest in returning to their homeland as they were promised. 

From 1948 to 1958, the United States conducted 43 nuclear tests on the Enewetak 

Proving Ground at Enewetak Atoll (DNA, 1981). The tests were conducted primarily on the 

northern islands to minimize contamination of the base camp islands located in the southeast 

islands of the atoll. The tests resulted in measurable residual radiation from fallout that deposited 

primarily on the northern islands of the atoll. The major radioactive contaminants remaining in 

the 1970s included the transuranic (TRU) radionuclides plutonium-239 (Pu-239), plutonium-240, 

(Pu-240), and americium-241 (Am-241), as well as the fission and activation products 

cesium-137 (Cs-137), strontium-90 (Sr-90), and cobalt-60 (Co-60). These radionuclides formed 

the primary potential sources of exposure to radiation through external exposure as well as 

through inhalation of airborne contaminants in suspended soil, and ingestion of soil, water, and 

dust. Small amounts of other fission products and TRU nuclides were present but were 

determined not to be important in ECUP dose assessments. Media that could be the source of 

radiation exposure included principally soil and dust, but also potentially contaminated debris, 

equipment, lagoon water and sediments, locally harvested food, and drinking water. 

Planning for the cleanup of Enewetak Atoll began in the early 1970s following the U.S. 

government’s decision to return the atoll to the Trust Territory of the Pacific Islands. This 

required collecting information about the nature and extent of the radioactive contamination 

through the approximately 40 islands of the atoll. The Atomic Energy Commission (AEC) and 

DoD conducted radiological surveys and completed several studies during the early to mid1970s. These efforts led to the conclusion that the islands of Enjebi, Lujor, Aomon, Boken, and 

Runit had radioactive soil contamination above satisfactory levels that would require cleanup 

(DNA, 1981). The principal investigations conducted by AEC, DoD, and their contractors 

include: 

 

1

 In 1974, the U.S. government changed its spelling of the name of the atoll from Eniwetok to Enewetak to more 

closely represent the way it was pronounced by the Marshallese people. 
18 

 A preliminary radiological survey and initial reconnaissance conducted in May 1972 by 

representatives from AEC, DNA, the U.S. Environmental Protection Agency (USEPA) and 

the University of Washington (AEC, 1972; DNA, 1972; Stevens, 1972; TTPI, 1972) 

 An engineering study under DNA contract to Holmes & Narver, Inc. (H&N) of the atoll to 

include recommendations and cost estimates for cleanup of the atoll (H&N, 1973) 

 A radiological field survey conducted in late 1972 to develop sufficient data to characterize 

the radiological environment of Enewetak Atoll (AEC, 1973a) 

 An environmental impact statement evaluating the cleanup, rehabilitation and resettlement of 

the Enewetak Atoll (DNA, 1975). 

The cleanup was conducted under a comprehensive radiation safety and monitoring 

program, appropriate for occupationally exposed individuals, to provide extensive oversight of 

all project activities and preserve robust monitoring and personnel exposure records. Decades 

after the cleanup was completed, ECUP veterans developed adverse medical conditions and 

expressed concerns that their exposures during ECUP were the cause of their ills. Discussions of 

the ECUP veterans in the news and through contact with congressional representatives led to 

proposed legislation in several Congresses to include ECUP participants in veterans’ 

compensation programs for radiation exposed individuals. In the fall of 2016, DTRA directed its 

radiation dose assessment support team to develop a technical basis document to assist the 

agency in responding to VA requests for dose information for ECUP veterans’ claims. 

The overall approach to develop the technical basis for assessing radiation doses for 

ECUP veterans was organized into five parts: 

1) Identification of major cleanup project components 

2) Development of the dose estimation methodology 

3) Preparation of guidelines for veteran claim implementation 

4) Development of dose calculation tools 

5) Preparation of the original technical basis document and this revision. 

Beginning in late 2016, a team of historians, health physicists, other scientists and 

engineers, and support personnel reviewed a large collection of documents and records 

pertaining to ECUP, covering periods from the early 1970s to the early 1980s. The goal was to 

evaluate and compile information relevant to the potential exposure to radiation of DoD 

personnel who participated in the cleanup project during 1977–1980. Extensive repositories of 

records at the Defense Threat Reduction Information Analysis Center (DTRIAC) at Kirtland Air 

Force Base (AFB), NM, and the Nuclear Testing Archive at Las Vegas, NV, were searched for 

pertinent documents. Transfer of the DTRIAC collection to DTRA and scanning to digital form 

improved the efficiency of searches and formed the basis for a searchable repository for future 

veteran radiation dose assessments. 

Records of radiation dosimetry obtained from film badges and thermoluminescent 

dosimeters (TLDs), which were assigned throughout the duration of the ECUP, provide an 
19 

overall impression of the external exposures of ECUP participants. However, as observed during 

atomic testing, the hot, humid, and sometimes wet atoll environments affected the performance 

of film dosimeters with the result that many of these devices could not be properly evaluated for 

dose, especially during the initial months of the ECUP. Supplementing film dosimeters with 

TLDs improved dose monitoring significantly. Nevertheless, administrative procedures were 

required to estimate the doses for individuals whose film badge dosimeters could not be 

evaluated. (DNA, 1981) 

Review of ECUP bioassay records in the form of nasal smears and urinalysis testing 

results indicate that internal deposition of plutonium nuclides was not observed except in 

samples from a few individuals. Results from a second sample from each of these individuals 

showed no detectable radioactivity from plutonium in all such samples. (DNA, 1981) 

To characterize the scenarios of exposure of ECUP personnel, specific coherent project 

tasks were identified and categorized into nine major project components including soil cleanup, 

debris cleanup, radiological support, and six others. Methods to estimate radiation doses for 

various exposure pathways are based mainly on the standard methods developed by DTRA for 

the Nuclear Test Personnel Review Program (DTRA, 2017). All necessary equations to estimate 

external, internal and skin doses for ECUP personnel, as well as upper-bound doses at least at the 

95th percentile confidence level, are provided. 

For external exposures, it is concluded that measurements of radiation exposure rates 

based on the 1972 aerial radiological surveys conducted by the AEC would tend to overestimate 

the conditions that prevailed during the cleanup project during 1977–1980. These exposure rates 

are recommended as default values to be used to estimate high-sided external whole-body 

gamma doses. 

For internal exposures, it is estimated that over 99 percent of the calculated internal dose 

from inhalation of suspended soil and dust for most internal organs would result from the three 

TRU radionuclides Pu-239, Pu-240, and Am-241. With respect to the airborne activity 

concentrations of suspended soil and dust from undisturbed ground, it is recommended to use 

island-average soil activity concentrations from the 1972 AEC soil-sampling program (AEC, 

1973a). For estimating internal doses from exposures to contaminated soil that was excised from 

the islands of Boken, Enjebi, Lujor, Aomon, and Runit, then transported, mixed and contained in 

the Cactus Crater and dome on Runit, it is recommended that the air activity concentrations 

should be based on the TRU concentrations of the soil removed from each island. These 

concentrations are derived from the total estimated activity removed from each island as reported 

in DNA (1981). Using the total TRU activity and the total volume of soil removed from each of 

the five islands, an average soil concentration for each island and overall weighted averages are 

estimated. In addition, air sampling results are available in the form of weekly statistical 

summaries, including the weekly maximum concentrations. 

Based on the information described in this report and summarized above, the study team 

was able to build a collection of pertinent radiation data and combine them with conservative 

assumptions and sound calculations to produce credible, high-sided dose estimates in favor of 

ECUP veterans. Using these data and assumptions, several examples of dose estimation for 

ECUP exposure scenarios are described. They include sample assessments for personnel who 

were involved in soil cleanup, debris cleanup, and boat transport of contaminated soil. In 

addition, an example dose assessment for Air Force personnel who were assigned temporary 
20 

duty at Enewetak in 1965 is included. This latter example was developed to serve as a basis to 

estimate doses in support of specific VA claims from veterans who performed duties on 

Enewetak in the 1960s before the start of the ECUP. 

Finally, guidelines are presented that supported the development of a standard operating 

procedure (SOP) to be used to perform individual radiation dose assessments for ECUP veterans 

in response to VA requests. For such individualized dose assessments, it is important to collect 

veteran-specific information and data that can be used to adjust or complement the scenarios of 

exposures and assumptions identified in this report. For this purpose, an ECUP-specific 

questionnaire was developed and has been used to collect veteran-specific information from 

claimants. If additional sources of exposures and pathways are identified in the questionnaire, 

supplemental doses are estimated using standard dose reconstruction techniques. Since the 

publication of the original version of this technical report, a standard operating procedure, 

“Radiation Dose Assessment for Participants in the Enewetak Cleanup Project”, was developed 

and published by DTRA (DTRA, 2019). Section 9 of this report describing the guidelines for 

SOP development is maintained in this revision for completeness. 

Based on discussions in this report, it is confirmed that ECUP participants conducted all 

cleanup work within a structured and effective radiation protection program as reported in DNA 

(1981) and elsewhere, which served to minimize radiation doses. The highest of the estimated 

upper-bound total effective radiation doses for any of the included sample assessments is 

0.22 rem (2.2 mSv) above natural background. This dose is similar to the average individual 

effective dose of 0.31 rem (3.1 mSv) to the U.S. population from ubiquitous background 

radiation including radon (NCRP, 2009a). It is also substantially lower than the whole body 

occupational dose limit of 5 rem (50 mSv) per year that was in place for personnel during ECUP. 

As a result of the ECUP radiation protection program, the generally low levels of contamination 

encountered, and as confirmed by example dose assessments, it is concluded that ECUP 

participants’ exposures resulted in whole-body and organ doses much lower than doses 

associated with adverse health effects. This conclusion is supported by the following statement 

from the Health Physics Society’s position statement regarding radiation health risks: 

“Substantial and convincing scientific data show evidence of health effects 

following high-dose exposures (many multiples of natural background). 

However, below levels of about 100 mSv [10 rem] above background from all 

sources combined, the observed radiation effects in people are not statistically 

different from zero.” (HPS, 2019) 
21 

Section 1. 

Introduction 

This report serves as the technical basis document for performing individualized radiation 

dose assessments (RDA) for veterans who participated in the cleanup of Enewetak2 Atoll from 

1977 to 1980. Approximately 6,000 military service members of the United States Department of 

Defense (DoD) participated in the cleanup project. The DoD established a Joint Task Group 

(JTG) within the Defense Nuclear Agency (DNA) to conduct the cleanup, as authorized by 

Congress in Public Law 95-134 (Congress, 1977), in an operation named the Enewetak Atoll 

Cleanup Project (ECUP). Enewetak Atoll was one of two primary locations in the Pacific Ocean 

where the United States conducted atmospheric tests of nuclear devices during the mid-1940s 

through 1962 (DNA, 1981). Radioactive contamination from nuclear detonations remained after 

testing ended. During the early 1970s, previous residents of the atoll, who had been relocated 

prior to the start of testing, expressed interest in returning to their homeland as they were 

promised. 

The JTG performed the cleanup using personnel from the U.S. military services assisted 

by DoD civilian employees and contractors, the U.S. Atomic Energy Commission (AEC)3 and 

other agencies (DNA, 1981). The cleanup was conducted under a comprehensive radiation safety 

and monitoring program, appropriate for occupationally exposed individuals, to provide 

extensive oversight of all project activities and preserve robust monitoring and personnel 

exposure records. Major cleanup activities included: 

 Clearance of vegetation and removal of contaminated soil and debris 

 Demolition and removal of uncontaminated buildings and debris 

 Transportation of contaminated soil and debris to disposal sites at the lagoon or Cactus Crater 

on Runit Island 

 Preparation of the atoll for resettlement. 

During the past few years, veterans have filed claims with the Department of Veterans 

Affairs (VA) asserting that adverse medical conditions they have developed were associated with 

their radiation exposures during ECUP. The VA’s decisions have not satisfied the affected 

veterans who have pursued other forms of redress. In reaction, legislators have introduced bills in 

the U.S. House of Representatives and the U.S. Senate that would include participation in ECUP 

as a radiation-risk activity (Congress, 2008, 2009) or to establish presumptive service connection 

for ECUP participants in a manner similar to that established for atomic test veterans (Congress, 

2017a, b). In addition, bills in the House of Representatives (Congress, 2017c) and Senate 

 

2

 In 1974, the U.S. government changed its spelling of the name of the atoll from Eniwetok to Enewetak to more 

closely represent the way it was pronounced by the Marshallese people. 

3

 A portion of AEC was reorganized into the Energy Research and Development Administration (ERDA) in January 

1975, which was subsumed into the Department of Energy (DOE) at its creation in August 1977. 
22 

(Congress, 2017d) proposed amendments to the Radiation Exposure Compensation Act (RECA) 

to include radiation exposure during cleanup of Enewetak Atoll. 

In 2016, the Defense Threat Reduction Agency (DTRA)—successor to DNA and DoD’s 

lead agent for providing dose assessments for atomic veterans—initiated the effort to identify, 

compile, and review available ECUP records and to prepare this technical report to serve as a 

comprehensive technical basis document to support ECUP veterans RDAs. Extensive 

repositories of records at the Defense Threat Reduction Information Analysis Center (DTRIAC) 

at Kirtland Air Force Base (AFB), NM and the Nuclear Testing Archive at Las Vegas, NV were 

identified and searched for pertinent documents. More than 150 boxes of relevant documentation 

were moved from the DTRIAC collection to DTRA and were digitally scanned to form a 

searchable repository of information about ECUP operations, reports, memos, letters, monitoring 

data, etc. A team of historians, health physicists, other scientists and engineers, and support 

personnel evaluated this information, including radiation monitoring results such as personnel 

dosimetry, air sampling results, exposure rates from external radiation, and bioassay results. The 

review of the documentation indicated that the ECUP radiation safety program was effective, and 

that the highest recorded whole body dose was 0.07 rem, which is about 70 times lower than the 

annual occupational dose limit of 5 rem in effect at the time (DNA, 1981; USNRC, 1975). 

DTRA then tasked its Nuclear Test Personnel Review (NTPR) Program support 

contractor to prepare this report with support from DoD’s Dose Assessment and Recording 

Working Group (DARWG) and professional health physics experts of the military services who 

are ECUP veterans. This team accomplished the aforementioned document review, the data 

analyses, the development of dose assessment methods, and performed the calculations of 

example dose estimates discussed in this report. This document presents the relevant historical 

information, exposure analyses and dose estimates for example ECUP participation scenarios. 

1.1 Background 

Enewetak Atoll is a small ring of islands approximately 2,500 miles west of Hawaii and 

is the only surface feature of one of the three island chains known as the Marshall Islands Group 

(DNA, 1981, Figure 1-3). The atoll contains some 40 named islands, two coral heads large 

enough to have been named by the Enewetak people, a number of small, unnamed islets, and 

long stretches of submerged reefs. Section 2.1 provides additional discussions of the atoll’s 

characteristics. 

From 1948 to 1958 the United States conducted 43 nuclear tests on the Enewetak Proving 

Ground at Enewetak Atoll (DNA, 1981). Prior to the start of testing, the Enewetak people were 

relocated to Ujelang Atoll, about 124 miles southwest of Enewetak. The tests were conducted 

primarily on the northern islands to minimize contamination of the base camp islands located in 

the atoll’s southeast. The tests resulted in small, but observable, residual radiation environments, 

primarily on the northern islands of the atoll. The major radioactive contaminants remaining in 

the 1970s included transuranic (TRU) radionuclides Pu-239, Pu-240, and Am-241, as well as the 

fission and activation products Cs-137, Sr-90, and Co-60. Small amounts of other fission 

products and TRU nuclides were present but would not be important in dose assessments. 

Section 2.2 provides additional discussions of the atoll’s use for nuclear testing. 

During the 1971 review required by the agreement between the United States and the 

Trust Territory of the Pacific Islands (TTPI), it was determined that Enewetak Atoll was no 
23 

longer needed for nuclear testing and should be returned to the TTPI (Johnston and Williams, 

1972). Efforts to return the Enewetak people identified the need for detailed assessments of the 

conditions on the various islands of the atoll and development and implementation of plans and 

programs to restore the atoll to acceptable conditions for habitation. The AEC and DoD 

conducted radiological surveys and completed several studies during the early to mid-1970s, 

which identified that the islands of Lujor, Aomon, Boken and Runit had radioactive 

contamination above acceptable levels that would require cleanup (DNA, 1981). At the same 

time, restoration actions on non-contaminated islands and test facilities were recommended. The 

principal studies conducted by AEC, DoD, and their contractors include: 

 A preliminary radiological survey and initial reconnaissance conducted in May 1972 by 

representatives from AEC, DNA, the U.S. Environmental Protection Agency (USEPA) and 

the University of Washington (Stevens, 1972; DNA, 1972; TTPI, 1972; AEC, 1972) 

 An engineering survey under DNA contract to Holmes & Narver, Inc. (H&N) of the atoll to 

include recommendations and cost estimates for cleanup of the atoll (H&N, 1973) 

 A radiological field survey to develop sufficient data on the total radiological environment of 

Enewetak Atoll (AEC, 1973a) 

 An environmental impact statement on the cleanup, rehabilitation and resettlement of the 

Enewetak Atoll (DNA, 1975). 

The assembled studies provided the input needed for planning cleanup efforts and 

assessments of the expected conditions after cleanup was complete. These plans led to the 

implementation of ECUP within the period of 1977 to 1980. Significant milestones during the 

first year included mobilization efforts starting March 15, 1977 and ECUP’s D-Day on June 15 

(DNA, 1981). Appendix A includes a list of ECUP milestones. Summary discussions of the 

history of ECUP are presented in Section 2. The radiological conditions prior to the cleanup, the 

radiological safety program, and other related aspects are detailed in Section 3. 

1.2 Veterans’ Concerns 

Many veterans who participated in ECUP continue to express concerns about whether 

their radiation exposures have contributed to various medical conditions they are experiencing. 

Many of them have joined organized groups to share information and concerns about their health 

and perceived problems with the radiation controls used during the project. Some groups have 

been very active and have raised interest in the media, for example in a recent New York Times 

article (Philipps, 2017) and in Congress. Bills in both the 114th and 115th Congresses were 

introduced to “provide for treatment of veterans who participated in the cleanup of Enewetak 

Atoll as radiation exposed veterans for the purposes of the presumption of service-connection of 

certain disabilities by the Secretary of Veterans Affairs” (Congress, 2015, 2016, 2017a, b) and 

for consideration under the Radiation Exposure Compensation Act (RECA) by the Department 

of Justice (Congress 2017c, Congress 2017d). 

Specific veterans’ concerns about inadequate radiological controls included reduced 

levels of personal protective equipment such as anticontamination suits and lack of respirators, 

allegations of falsified radiation monitoring and dosimetry records, and defective air sampling 
24 

and radiation dosimetry equipment. Concerns about radiological controls, challenges and 

significance are discussed in Section 3.2.2. 

1.3 Purpose and Scope 

The purpose of this report is to serve as the technical basis document for performing 

RDAs for ECUP participants and to discuss the approach, methods, and examples of dose results 

of a study to estimate upper-bound radiation doses that may be assigned to individuals in the 

Population of Interest (POI). The POI consists of about 6,000 military service members who 

participated in ECUP within the period 1977 to 1980.4 The POI is described in Section 2 and 

includes members of the three military service components of the JTG (Army Element, Navy 

Element and Air Force Element) as well as those in the DNA/JTG itself. 

1.4 Radiological Quantities 

This report discusses methods for the calculation of two radiation dose quantities, i.e., the 

effective dose and equivalent dose. These quantities apply to both exposures from sources 

outside the body and sources inside the body. The absorbed dose is a measure of the energy 

deposited in an organ or tissue. The equivalent dose to a tissue or organ from radiation is the 

absorbed dose multiplied by a radiation weighting factor. The radiation weighting factor is 

unitless and relates absorbed dose to the probability of a stochastic radiation effect, such as 

cancer or changes in hereditary characteristics. For example, alpha particles are known to be 10 

to 20 times more effective than beta particles or gamma rays. The effective dose is the sum of the 

organ weighted equivalent doses to all tissues and organs in the human body. Effective dose is 

commonly used to determine compliance with regulatory limits. Doses and other radiological 

quantities in this report are stated in conventional units (rad, rem, Ci, R, etc.) because those units 

were used prior to and during the cleanup period. When useful for comparison, more recent 

doses reported in SI units5 (Gy, Sv, Bq, etc.,) are stated in conventional units with SI units in 

parentheses. All doses reported in this report are assumed to be in addition to background. 

Internal doses in organs and tissues result from radiation emitted from radioactive 

materials in the body. Doses are accrued over the entire time that the radioactive materials 

remain in the body. In some cases, the radioactive materials remain for very short periods such as 

a few weeks, or months while in other cases, such as for Pu, the radioactive material is retained 

for many years. A convenient way to compare the potential radiation effects from these varied 

conditions, committed doses are calculated. A committed dose is the total dose to an organ or 

tissue over a specified time period, such as 50 years for an occupationally exposed individual or 

over 70 years, 80 years or some other number of years for members of the public. Committed 

equivalent doses or committed effective doses can be calculated. In this report, internal doses are 

estimated using the 50-year committed effective dose to the whole body and the 50-year 

committed equivalent dose to specified organs or tissues. 

1.5 Technical Approach 

The characterization of exposure to radiation described in this report is designed to 

provide the technical basis for radiation dose assessments in response to future VA requests for 

 

4

 The inclusive dates January 1, 1977 through December 31, 1980 are the period of participation for the ECUP 

proposed in recent legislation. (Congress, 2017a, b) 

5

 SI means Système International d'Unités (International System of Units). 
25 

dose information that are needed in the processing of veteran claims. The report discusses 

pertinent historical and technical information combined with relevant technical methods used in 

radiation dose assessments. It includes a compilation of information and data that can be used by 

a radiation dose assessment (RDA) analyst to assign or estimate conservative external and 

internal radiation doses and corresponding upper-bound doses that could have been accrued by a 

veteran who participated in the ECUP between 1977 and 1980. 

Potential radiation exposures are categorized at the project activity level to estimate 

conservative upper-bound doses based on a veteran’s account of his or her participation 

information. High-sided conservative parameter values are selected to reflect the higher end of 

the range of plausible values. The upper-bound dose is estimated to be at least as high as the 95th

percentile dose based on comparisons of similar assessments using a probabilistic analysis that 

accounts for uncertainties in the determination of dose distributions. To carefully compile all 

project activities performed by ECUP participants that are relevant to this technical basis study, a 

three-level structure, described in detail in Section 5, is devised where ECUP-relevant operations 

are subdivided into nine project components, which are subdivided into a number of major tasks 

and specific project activities. 

Project activities and related sources of radiation and exposure pathways are discussed in 

Section 5. Section 6 discusses external dose estimation methods, use of dosimetry records, and 

the method to estimate external dose uncertainties. Section 7 includes methods and assumptions 

for selecting dose parameters values for estimating internal doses, as well as uncertainties in 

internal doses. The methods presented in Section 6 and Section 7 and the radiation monitoring 

data compiled in Section 4 constitute the basis for performing future individual radiation dose 

assessments for ECUP participants. In Section 8, examples of scenarios of participation and 

radiation exposure are presented showing how doses can be estimated by an RDA analyst in the 

case of future veteran claims and VA requests for dose information. 

Standard dose reconstruction techniques used in RDAs are based on standard procedures 

and methods developed for other veterans’ RDA programs such as the DTRA NTPR Program 

(DTRA, 2017). As shown in Figure 1, the overall approach to develop the technical basis for 

assessing radiation doses for ECUP veterans organized the effort into five parts: identification of 

major project components, development of the dose estimation methodology, preparation of 

guidelines for veteran claim implementation, development of dose calculation tools, and 

preparation of this technical basis document. The following steps were adopted as part of the 

approach to develop the technical basis for estimating upper-bound doses for veterans who 

participated in ECUP: 

1) Review historical information and data related to ECUP to include planning, data collection, 

project implementation components, tasks and activities, and related personnel records of 

exposure to radiation 

2) Collect additional information from veterans and military services with emphasis on 

radiation measurements, radiation exposure potential, and implemented radiation safety 

procedures 

3) Compile and evaluate available dosimetry records of ECUP military personnel 
26 

4) Use all collected historical information to develop activity-based exposure scenarios and 

pathways of exposure for individuals who participated in specific project activities and tasks 

(project activities and tasks are discussed in detail in Section 5) 

5) Estimate conservative, also referred to in this report as high-sided, external and internal doses 

and corresponding upper-bound doses for example exposure scenarios using standard dose 

reconstruction methods and techniques 

6) Propose guidelines and procedures for individualized RDAs that DTRA or military services 

can use for VA claims 

7) Develop an ECUP veteran questionnaire with questions that would help collect individual 

information that can be used as veteran-specific dose input data. 

An RDA implementation process is shown in Figure 1. This process shows the dose 

development phase covered by this report combined with the implementation aspects for 

individualized veteran dose assessments. 

Figure 1. Radiation dose assessment development and implementation process 
27 

Section 2. 

Enewetak Atoll and Cleanup Project 

This section describes the geographic layout of Enewetak Atoll and the naming 

convention of the islands, including the designations of the Enewetak people. It also lists the 

atmospheric nuclear tests conducted in the atoll from 1948 to 1958 and their locations. A broad 

overview of the actions to cleanup Enewetak Atoll starting in 1972, along with the basis and 

strategy for conducting the cleanup, and considerations for returning the islands to the 

Marshallese population are detailed. 

2.1 Enewetak Atoll Setting 

Enewetak Atoll, shown in Figure 2 is approximately 23 by 17 statute miles with the long 

axis running northwest to southeast. The land surface area totals 1,761 acres or 2.75 square 

miles. The lagoon has an area of approximately 388 square miles. Its depth averages 160 feet 

with a maximum of approximately 200 feet. There are three entrances to the lagoon: the east 

channel or Deep Entrance, 180 feet deep, lying between Medren and Japtan; the Wide Passage in 

the south, 6 miles in width; and a 24-foot deep channel called the Southwest Passage. The atoll 

contains some 40 named islands, two coral heads large enough to have been named by the 

Enewetak people, and a number of small, unnamed islets and long stretches of submerged reefs. 

Table 1 provides the names used by the people of Enewetak and U.S. government-assigned 

names and codes for the islands.6 (DNA, 1981) 

As can be seen from Figure 2, the atoll is divided into 22 northern islands Bokoluo to 

Runit and 18 southern islands Inderal to Biken. The northern islands, listed in Table 1, were 

assigned female code names in alphabetical order (Alice to Yvonne) in a clockwise direction. 

The southern islands, also listed in Table 1, were assigned male code names continuing 

clockwise (Alvin to Leroy). Smaller islands and other features were named later, disrupting the 

original alphabetical order of assignment. Data indicate that elevated levels of external radiation 

and contamination were found in the northern islands, while low levels less than 4 μR h−1 were 

characteristic of the southern islands (AEC, 1973a). 

2.2 Use of Enewetak Atoll for Nuclear Testing 

The U.S. government decided in 1947 to develop the atoll for use as an atmospheric 

nuclear testing site in the Pacific. The decision involved much negotiation by organizational 

elements of the U.S. government, primarily AEC, DoD, and DOI, representatives of the TTPI (of 

which the Marshallese people of Enewetak Atoll were part), and the President as the final 

decision maker. Use of the atoll as a nuclear testing site required moving and relocating the 

Enewetak Atoll inhabitants to Ujelang Atoll, another neighboring atoll a few hundred miles 

away. Enewetak Atoll was developed into a logistics support base and proving ground for 

nuclear testing. Enewetak Atoll was part of the Pacific Proving Ground in the Marshall Islands, 

which included another nuclear test site, Bikini Atoll. (DNA, 1981) 

 

6

 In this report, “Island Name” means the name used by the people of Enewetak, and “Site Name” means the name 

assigned by the U.S. government, mainly for use during the atomic testing program. 
28 

Figure 2. Enewetak Atoll islands and nuclear detonation sites (DNA, 1981) 
29 

Table 1. Compendium of island names and corresponding site names 

Island 

Code* Site Name Island Name†

Island Name Site Name

Northern Islands Aej Olive 

FA Alice Bokoluo Alembel Vera 

FB Belle Bokombako Ananij Bruce 

FC Clara Kirunu Aomon Sally 

FD Daisy Louj Bijile Tilda 

FE Edna Bocinwotme Biken Leroy 

FH Helen Bokaidrik Billae Wilma 

FI Irene Boken Bocinwotme Edna 

FJ Janet Enjebi Bokaidrik Helen

FK Kate Mijikadrek Bokandretok Walt 

FL Lucy Kidrinen Boken Irene 

MP Percy Taiwel Boken Irwin 

FM Mary Bokenelab Bokenelab Mary 

FN Nancy Elle Boko Sam 

FO Olive Aej Bokoluo Alice 

FP Pearl Lujor Bokombako Belle 

FR Ruby Eleleron Drekatimon Oscar (coral head) 

FS Sally Aomon Eleleron Ruby 

FT Tilda Bijile‡ Elle Nancy 

FU Ursula Lojwa Enewetak Fred 

FV Vera Alembel Enjebi Janet 

FW Wilma Billae Ikuren Glenn 

FY Yvonne Runit Inedral Uriah 

Southern Islands Japtan David 

MS Sam Boko Jedrol Rex 

MT Tom Munjor Jinedrol Alvin 

MU Uriah Inedral Jinimi Clyde 

MV Van ―§ Kidrenen Keith 

MA Alvin Jinedrol Kidrinen Lucy 

MB Bruce Ananij Kirunu Clara 

MC Clyde Jinimi Lojwa Ursula 

MC David Japtan Louj Daisy 

MR Rex Jedrol Lujor Pearl 

ME Elmer Medren (aka Parry) Medren (aka Parry) Elmer 

MW Walt Bokandretok Mijikadrek Kate 

MF Fred Enewetak Munjor Tom 

MG Glenn Ikuren Mut Henry 

MH Henry Mut Ribewon James 

MI Irwin Boken Runit Yvonne 

MJ James Ribewon Taiwel Percy 

MK Keith Kidrenen Unibor Mack (coral head) 

ML Leroy Biken ―§ Van 

MO Oscar (coral head) Drekatimon 

MM Mack (coral head) Unibor 

*

 Island code was assigned by JTG. 

†

 As confirmed by the Enewetak people during the Ujelang field trip of July 1973 (or from Dr. Jack A. 

Tobin). 

‡

 Shown as Bijire in DNA (1981). 

§

 The Enewetak people had no name for this island. 
30 

The United States conducted 43 nuclear tests on Enewetak Atoll from 1948 to 1958. The 

tests ranged in yield from a few kilotons (kt) to megatons (Mt). Figure 2 also provides the 

locations within the atoll where the individual nuclear tests were conducted. The tests were 

primarily conducted in the atoll’s northwestern and northeastern quadrants to minimize 

radioactive contamination to base camps on the southern islands. Each test caused measurable 

effects to some portions of the atoll’s islands. Some produced major changes to the topography 

of some islands. Other changes noted were construction of buildings to house equipment and 

labs for measuring and recording nuclear effects (DNA, 1981). The visible effects of these 

changes include: 

 Elugelab and Lidilbut islands and most of Bokaidrikdrik and Eleleron were obliterated. 

 Large craters were formed on the reefs on the north end of Runit. 

 Surface profiles of ground zero points were changed. 

 Coconut palms and other vegetation were destroyed in many areas. 

 Causeways, landfills, and the areas excavated for test preparations changed the topography of 

some islands, for example a constructed causeway stopped the water flow between Aomon 

and Eleleron. 

 Large structures and bunkers for test measurements and observations remained after the 

testing. 

 Semi-permanent buildings were left standing mostly in the southeastern islands. 

 Tons of concrete rubble and metal debris were left in place after the tests. 

Conditions not readily visible included contaminated soil and debris on many islands and 

contaminated waters in the surrounding lagoon and ocean, including contaminated sediments. 

Many miles of cable were laid in the lagoon and between some islands for instrumentation, 

communications, and the activation of nuclear devices. Radionuclides were also distributed in 

the form of radioactive debris, soil and water. Debris and soil were mostly on the surfaces of 

many islands and in the surrounding waters, and to a lesser extent in burial sites (crypts) and 

bunkers on certain islands. All of these effects had a significant influence on formulating plans 

and actual execution of cleanup operations. 

Atmospheric nuclear testing ceased in 1962 in advance of the signing of the Limited Test 

Ban Treaty by the United States, UK, and USSR in 1963. In the early 1970s, the U.S. 

government decided that control of Enewetak Atoll should be returned to the TTPI (Johnston and 

Williams, 1972) and felt a moral and potentially legal obligation to remediate the atoll due to 

debris, unexploded ordnance, abandoned buildings, and atoll-wide radiological contamination 

and to resettle the Enewetak people with a supporting agricultural, housing, and community 

infrastructure. (DNA, 1981) 

2.3 Enewetak Cleanup Project Summary 

In 1972, representatives of the Office of Micronesian Status Negotiations (MSN), DoD, 

DOI and AEC discussed plans for the radiological cleanup, rehabilitation, and resettlement of 

Enewetak Atoll in the Marshall Islands resulting in a decision to conduct the ECUP project 
31 

(DNA, 1981). From 1972 to 1976, AEC, DNA, EPA, University of Washington, U.S. Air Force 

(USAF), TTPI, and the Enewetak people were involved in determining the on-going scope of 

work necessary to conduct the cleanup (DNA, 1981). From mid-1977 through March 1980, the 

cleanup was executed by DoD and involved Army, Navy, and Air Force units and personnel. 

During that time, the Department of Energy (DOE) performed radiological characterizations and 

certifications, and the DOI conducted the rehabilitation and resettlement project. 

The primary purpose of the radiological debris and soil cleanup was to reduce the TRU 

elements (plutonium and americium) to levels that would not pose long-term hazards to the 

returning people of Enewetak. While removing TRU-contaminated debris and soil, other 

radionuclides present were also removed. The cleanup consisted of three separate efforts: 

 Transfer and disposal of uncontaminated (“green”), contaminated (“yellow”) debris, and 

structures into the lagoon, see Section 3.2.2 for definition of green and yellow debris 

 Crater-entombment of radiologically contaminated debris and structures transported from the 

islands 

 Crater-entombment of radiologically contaminated soil excised on the islands and then 

transported from the islands. 

The crater formed by the Cactus event on Runit Island was established as a permanent 

disposal location for ECUP in 1977. The crater was used for entombment of contaminated soil 

and “red” debris; see Section 3 for debris classification. Contaminated soil was mixed with 

cement, attapulgite clay, and salt water to form a slurry that was placed in the crater using tremie 

equipment mounted on a floating barge. Contaminated debris requiring crater disposal, i.e., 

classified as “red”, was placed in the crater with cranes, bulldozers, or dump trucks and 

encapsulated within soil-cement slurry. A concrete dome cap was used to seal the crater after it 

was filled with the radiologically contaminated soil-cement mix and debris. (DNA, 1981) 

The atoll islands were classified based on intended use by the resettled Enewetak people 

as determined by an acceptable soil contamination level to which a given island would be 

remediated. Radiological soil survey results identified which islands required remediation. They 

formed the basis for the development of the remediation and radiological safety plans. Soil 

plutonium concentration levels determined the necessity and extent of soil remediation. Three 

levels of residual plutonium were used to guide decontamination activities: 

 Level 1: Plutonium concentration greater than 400 pCi g−1—soil removal by scraping 

 Level 2: Plutonium concentration from 40 to 400 pCi g−1—individual case consideration 

 Level 3: Plutonium concentration less than 40 pCi g−1—no cleanup required. 

The soil survey results originally identified 12 islands with concentrations above the 

40 pCi g−1limit. However, not all of the 12 islands required remediation because they were not 

intended for residential use. The final island survey (DOE, 1982a) identified 30 islands below 

Level 3 criteria and they were classified for residential use. Seven islands with concentrations 

between 40 and 160 pCi g−1 were designated for agricultural use. Two islands with 
32 

concentrations over 160 pCi g−1 were designated for food gathering. One island, Runit, the site of 

the Cactus Crater, was quarantined permanently (DNA, 1981). 

The concentration range of 160 to 400 pCi g−1 was set as the criterion for islands from 

which food could be harvested, but planting for agricultural use was restricted. Islands with 

concentration ranges from 40 to 160 pCi g−1 were acceptable for harvesting and planting. Islands 

with concentrations below 40 pCi g−1 were suitable for habitation. The decision to quarantine 

Runit (concentration above 400 pCi g−1) was based on reestablishing priorities against available 

resources. During the course of the cleanup operation, the decision was made not to cleanup 

Runit (DNA, 1981). 

In 1986, the U.S. government returned Enewetak Atoll to the Republic of the Marshall 

Islands, formerly TTPI. Today, all of the islands, except Runit, and the lagoon are accessible. 

Runit remains quarantined due to residual sub-surface soil contamination and the presence of the 

Cactus Crater dome. 

2.4 Cleanup Basis and Strategy 

Initial plans and approaches started well before the U.S. government decision to conduct 

the actual cleanup. In the early 1970s, the AEC embarked on an island-by-island aerial 

radiological survey of Enewetak Atoll (AEC, 1973a) to derive ground-level radiation exposure 

rates associated with the beta and gamma-emitting radionuclides described later in Section 3. 

DNA commissioned an engineering survey and study of the various terrains and environments 

that would be encountered on the atoll (H&N, 1973) and prepared an Environmental Impact 

Statement (EIS) (DNA, 1975), taking into account the sensitivities of restoring the islands for 

safe re-habitation by the Enewetak people and for their self-sustainment. The EIS provided an 

exhaustive development of alternative cleanup plans and presented a best alternative choice for 

decision makers (DNA, 1975). 

Management of the entire cleanup operation was assigned to a JTG reporting directly to 

the Commander, Field Command DNA (FCDNA). The JTG (Figure 3) was responsible for all 

aspects of the operation on Enewetak, including a comprehensive radiation safety program. After 

substantial planning, the personnel mobilization effort began in March 1977. Work on preparing 

for construction of the Lojwa base camp began in April 1977 and the first transportation units, 

including Navy landing craft and an Air Force Airfield Team arrived in May 1977. Also, an 

advanced party of the JTG arrived during the spring of 1977 to begin organizing the group. 

D-day occurred June 15, 1977 and efforts to organize the JTG and establish policies continued. 

Mobilization continued until November 1977. In practice, mobilization and cleanup efforts 

overlapped by several months. Some cleanup operations began long before November 17, 1977 

and some mobilization efforts were not completed until much later (DNA, 1981). 

Two islands, Enewetak and Lojwa were selected for development as base camps or 

residence islands, because levels of radiation were found to be at background levels comparable 

to those of the United States and their strategic locations enhanced cleanup operations. They 

required no radiological cleanup. Enewetak Island was the main base for operational 

administration, supply management, air transportation, and central communications. It was large 

enough to accommodate various buildings and support structures and support an air field long 

enough for handling large cargo aircraft, such as the USAF C-5A. Lojwa was the base camp to 

support the bulk of daily cleanup operations on the mostly contaminated northern islands. It 
33 

Figure 3. Joint Task Group organization (DNA, 1981) 
34 

facilitated daily travel to and from work sites to housing facilities by eliminating large distance 

time-consuming travel from housing facilities on Enewetak Island (DNA, 1981). Preparation for 

actual cleanup involved detailed radiological surveys to describe accurately any redistribution of 

the residual radioactive contaminants on the islands since the initial 1972 survey (AEC, 1973a). 

These began in July 1977 with surveys on Enjebi Island. Enjebi was chosen because of its ease 

of access and conduciveness regarding efforts to test out new procedures, including methods for 

brush clearing. Also, a tracked vehicle, configured for the in situ measurement of plutonium 

(IMP) was deployed to assess ground-level concentrations of TRU by the measurement of 

Am-241 activity. These initial surveys aided in working out the details of IMP operations, brush 

clearing, and soil sampling as well as implementing procedures for determining plutonium 

surface soil concentrations from IMP measurements. 

By late August 1977, the techniques for the three separate efforts had been worked out, 

but concerns about the allocation of resources to complete the cleanup of items required by the 

EIS (DNA, 1975) caused priorities for the effort to change. Items requiring attention included 

removal of plutonium from the Aomon burial sites (crypts), removal of plutonium-contaminated 

soil from Boken, Lujor, and Runit, and removal of residual large building debris from Enjebi. 

There was a decision to establish three designated debris disposal sites in the Enewetak lagoon 

for the cleanup operations as shown in Figure 4 (DNA, 1981). Only contaminated debris meeting 

the radiological conditions to be considered as “yellow” debris were disposed of at these lagoon 

sites, see Section 3.2. 

Other preparations including clearing of channels to the primary islands, and location and 

disposition of unexploded ordnance by Service explosive ordnance disposal (EOD) personnel 

were completed by the end of October 1977. Cleanup on Lujor officially began on November 1, 

1977. Operations continued but experienced two tropical storms—Typhoon Mary in December 

1977 and Typhoon Nadine in January 1978 that interrupted operations. Upon resumption of 

cleanup activities, the established DNA cleanup priorities were to:

 Continue cleanup of Aomon for agricultural use, with an option to cleanup to residential 

levels 

 Begin soil cleanup on Enjebi beginning with the areas of highest contamination; and after 

considering available resources for Boken and Lujor 

 Cease work on Enjebi 

 Concentrate on soil removal on Boken and Lujor. 

In addition, cleanup on Runit was again considered and decisions made to cleanup small and 

large areas, with plutonium concentrations over 160 pCi g−1, as resources were available, but not 

use any special resources (DNA, 1981). 

Soil cleanup presented several management and technical problems that required 

reassessments of some of the original plans, introduced delays in completion of certain tasks, and 

required confirmation of cleanup levels and disposal plans. Nevertheless, cleanup was carried out 

using an orderly process of assessment, planning, and testing of procedures before full-scale 

implementation. The testing involved balancing considerations for radiation safety, and other 

safety issues, with the efficiency, practicality, and effectiveness of the proposed procedures. 
35 

Figure 4. Lagoon disposal sites 

Pilot testing of alternative soil removal processes began in March 1978 and considered 

the following basic steps: 

 Identify the site and scope of work 

 Implement radiation safety and control procedures 

 Survey and stake the boundaries of soil excision areas 

 Remove excess brush 

 Excise (scrape surface with bulldozer blade) the area and windrow (bulldoze into long line 

piles) excised soil to prepare for movement to landing craft 

 Resurvey the excised area using the IMP and/or soil samples 

 Repeat previous steps until residual soil concentrations were reduced to desired levels 

 Transport soil from windrows to beach stockpiles 

 Transport soil from beach stockpiles to stockpiles on Runit. 
36 

Each of the basic steps was fully tested and evaluated to satisfy safety and efficiency criteria. All 

of the operations were conducted with the oversight of the Field Radiation Support Team (FRST) 

radiological control personnel under the direction of J-2 health physicists. Ultimately, surface 

soil removal was accomplished using bulldozers for scraping 6-inch deep cuts and windrowing. 

(DNA, 1981) 

Transport from cleanup sites to contaminated island beaches used a variety of trucks 

depending on the ability to negotiate the sand surface, beach, etc. Soil transport from the beach 

to Runit was conducted with bulk haul of the soil in modified landing craft, using fully tested 

procedures. Sampling for airborne activity concentrations during transport confirmed the 

operations could be conducted without respiratory protection while in transit. 

A second cleanup of Lujor was completed during June and July 1979 after a resurvey 

identified areas with levels above the 160 pCi g−1 limit. Also, cleanup of the Aomon burial sites 

(crypts) required unique efforts because of their unknown construction and contents. Following 

several additional studies and excavations beginning in July 1978, initial excavations began in 

January 1979 and the entire operation including restoration was completed by the end of May 

1979. Cleanup of Runit remained the only outstanding effort (DNA, 1981). 

The Runit cleanup involved contaminated small areas (hotspots) and plutonium-coated, 

metallic fragments, as well as contaminated debris. The cleanup proceeded in parallel with 

completion of the tremie operations to fill the crater and to place the concrete cap. While 

conducting a survey of Runit, cleanup teams were faced with discovery of additional high (red 

level) survey readings greater than 100 μR h−1 at one foot on debris requiring crater disposal. 

Discoveries of additional red-level debris on Runit in November 1979 and a few other islands in 

October 1978 continued until completion in February 1980. Afterwards, the final concrete 

capping of the Runit crater was accomplished by March 31, 1980. Following additional 

restoration activities on Enewetak Island and demobilization activities, the project proceeded to 

completion. On May 13, 1980, the demobilization forces departed Enewetak Atoll, 3 years after 

the initial elements arrived on Enewetak Atoll to initiate ECUP (DNA, 1981). 

2.5 Functional Organization of the Population of Interest 

As described in Section 2.4, management of the cleanup operation was assigned to a JTG 

that was responsible for all aspects of the operation on Enewetak. The JTG was staffed by 

individuals from the Army, Navy and Air Force in five divisions that reported to the 

Commander, JTG (CJTG). The CJTG was also given supervisory authority for direction and 

control over the Military Service Components of the JTG. The total number of participants and 

units composing the military service elements and the FCDNA JTG that make up the ECUP 

Population of Interest (POI) are shown in Table 2. 
37 

Table 2. Military Service component and DNA/JTG staffing of the Enewetak cleanup 

population of interest 

U.S. Army Element U.S. Navy Element U.S. Air Force 

Element FCDNA/JTG

2,670 2,207 740 246 

• Engineer Units 

• Helicopter Team 

• LARCs and 

amphibious vehicle 

operations 

• Chaplain Team 

• Finance Team 

• General Laundry 

Team 

• Decontamination 

Laundry 

• Harbor Clearance 

Units and WaterBeach Cleanup 

Teams 

• Intra-atoll 

Transportation 

• Radiological and 

laboratory 

technicians 

• Field Radiation 

Support Team 

• Medical team 

• Radiological and 

lab technicians 

• Communicationselectronics team 

• Petroleum-oillubricants team 

• Airfield team 

• Postal team 

• Commander, JTG 

• Administration 

• Engineering 

• Radiological 

Control 

• Logistics 

• Security 
38 

Section 3. 

Radiological Aspects of the Enewetak Atoll Cleanup Project 

3.1 Radiological Condition of Enewetak Atoll Prior to Cleanup Activities 

The radiological surveys performed in the years leading to the cleanup project served as 

the basis for identifying the radionuclides of concern, from a dose perspective, as Cs-137, Sr-90, 

Co-60, Pu-239, Pu-240 and Am-241. These radionuclides were produced from the nuclear test 

detonations and were deposited throughout the islands on vegetation, ground surfaces, lagoon 

sediment and water, as well as the remaining buildings, building rubble, and equipment used 

during the atmospheric test era. Cesium-137 (half-life 30.0 years) and Sr-90 (half-life 29.12 

years) were direct by-products originating from the fission of the nuclear fuel. Cobalt-60 (halflife 5.27 years) originated from the neutron activation of elemental cobalt contained in iron and 

steel or scrap metal and building materials during the nuclear detonation. Plutonium-239 (halflife 24,065 years), and Pu-240 (half-life 6,537 years) that were not consumed by the nuclear 

detonations remained at the atoll, and Am-241 (half-life 432.2 years) was produced as a decay 

product of Pu-241 (half-life 14 years), which would have been present as a small fraction of the 

total plutonium, typically less than 1 percent by mass (DOE, 1982a). 

Small quantities of the TRU radionuclides Pu-238 and Pu-241, and fission products, such 

as antimony isotope Sb-125 and europium isotope Eu-155, also remained at Enewetak Atoll, but 

they were not significant in ECUP dose assessments. Although analysis results for Pu-241 from 

the 1972 Enewetak radiological survey were not located, analyses for Pu-238 in soil were 

conducted but it was often not detected. When positive Pu-238 concentrations were measured, 

they were typically much less than Pu-239 (AEC, 1973a). In addition, soil activities of other 

fission products, primarily Sb-125 and Eu-155, were measured in trace amounts, but calculations 

indicated that these radionuclides contributed at most an additional 3 to 5 percent of the total 

1972 exposure rates (AEC, 1973a). Because the primary additional fission products have smaller 

radioactive half-lives than those of the radionuclides of concern listed above, they would 

contribute even less to the total exposure rates during ECUP than the 3 to 5 percent estimated for 

1972. Therefore, because of their low concentrations and/or radiological decay characteristics, these 

additional radionuclides are not included in ECUP radiological dose assessments. However, these 

shorter-lived fission products are included in the dose estimates of personnel who visited 

Enewetak Atoll prior to the ECUP in the mid-1960s as discussed in Section 8.4. 

DNA and AEC jointly conducted an extensive island-by-island radiological survey of the 

atoll in 1972. Prepared plans and results for the effort are available in AEC (1973a, b) and DOE 

(1982b). Section 4 presents an extracted summary of the survey results showing island-by-island 

measurements of external exposure rates and soil concentrations in 1972. These measurements 

provided the baseline for the planning and conduct of the cleanup operations. 

3.2 Radiation Safety Program and Radiological Controls 

The foremost goal of the cleanup operation was to maintain radiation exposures to 

personnel according to the “ALARA” principle, i.e., “as low as reasonably achievable” (DNA, 

1981). High-level governmental interest kept intense focus on this goal. In fact, according to 
39 

DNA, “No other aspect of the Enewetak radiological cleanup operation received the attention, 

priority, and detail that the radiation safety (RADSAFE) program received” (DNA, 1981). The 

program discussed below describes the cleanup policies and guidance and the radiological 

control practices implemented to minimize radiation exposure. 

Potential internal exposure from all of the residual radionuclides (see Section 2.2) 

presented the most significant risk especially from the alpha particles emitted by Pu-239/240 and 

Am-241 and, to a lesser extent, from the beta particles emitted by Co-60 and Sr-90. Almost all 

Co-60 was entrained in steel and Sr-90 was highly mobile in the environment. In addition, x-rays 

and gamma rays emitted by Co-60 and Am-241 contribute to the internal exposure. The 

radiations emitted by these radionuclides present minimal exposure risk when outside the body, 

but upon entry to the body via inhalation, ingestion, or wounds, bodily tissues and organs could 

be irradiated. Inhalation of radioactive contaminants suspended in the air was the primary route 

of entry. Intake of the isotopes of plutonium and americium was of most concern because they 

emit alpha particles, were present in substantial quantities at Enewetak, and tend to be retained in 

the body for periods significantly longer than the other radionuclides. 

3.2.1. Radiation Safety Program 

Three levels of on-site administration consisting of the Radiation Protection Officer 

(RPO), the Radiation Control Committee (RCC), and the FRST managed the radiation protection 

program. The duties of the RPO, defined in AR 40-14 (USA, 1975) as “the individual designated 

by the commander to provide consultation and advice on the degree of hazards associated with 

ionizing radiation and the effectiveness of measures to control these hazards,” were fulfilled by 

the J-2 officer on the JTG staff (Figure 3), designated as the RPO for Enewetak Atoll. A staff of 

radiation specialists within the J-2 organization engaged in day-to-day operational activities for 

the RPO, with alternate RPOs providing field oversight of the FRST activities. 

Radiation safety strategy considered that personnel engaged in cleanup operations 

involved digging, construction, and soil hauling, which could result in significant resuspension 

of radioactive contamination. To this end, a continuous assessment and careful management of 

all potential exposure pathways were maintained. To assure that radiation doses were minimized, 

radiation protection program guidance adhered to federal guidelines and regulations which 

required radiation exposures be kept ALARA—a philosophy still in use today. 

The regulations contained in Title 10, Code of Federal Regulations (CFR), Part 20 

(USNRC, 1975) were adopted for personnel radiation dose limits during ECUP. Army 

Regulation (AR) 40-14, “Control and Recording Procedures for Occupational Exposures to 

Ionizing Radiation” (USA, 1975) implemented the Federal radiation dose limits contained in 

these regulations which were in effect at the time in the United States for radiation workers. The 

dose limits are summarized below: 

1) The accumulated dose equivalent of radiation to the whole-body, head and trunk, active 

blood-forming organs, gonads, or lens of the eye will not exceed: 

– 1.25 rem in any calendar quarter, nor 

– 5 rem in any calendar year. 

2) The accumulated dose equivalent of radiation to the skin of the whole-body (other than hands 

and forearms), cornea of the eye, and bone will not exceed: 
40 

– 7.50 rem in any calendar quarter, nor 

– 30 rem in any calendar year. 

3) The accumulated dose equivalent of radiation to the hands and wrists or the feet and ankles 

will not exceed: 

– 18.75 rem in any calendar quarter, nor 

– 75 rem in any calendar year. 

4) The accumulated dose equivalent of radiation to the forearms will not exceed: 

– 10 rem any calendar quarter, nor 

– 30 rem in any calendar year. 

5) The accumulated dose equivalent of radiation to the thyroid, other organs, tissues, and organ 

system will not exceed: 

– 5 rem in any calendar quarter, nor 

– 15 rem in any calendar year. 

6) Individuals under 18 years of age, females known to be pregnant, and occasionally exposed 

individuals will not be exposed to a whole-body dose equivalent of more than: 

– 2 millirem in any one hour, nor 

– 100 millirem in any 7 consecutive days, nor 

– 500 millirem in any calendar year, nor 

– 10 percent of the values in 2., 3., 4., and 5. above for other parts of the body. 

7) Individuals over 18 years of age, but who have not yet reached their 19th birthday, will not be 

occupationally exposed to ionizing radiation exceeding: 

– 1.25 rem dose equivalent to the whole body in any calendar quarter, nor 

– 3 rem in the 12 consecutive months prior to their 19th birthday. 

The RCC reviewed procedures involved in the handling of radioactive materials. It made 

recommendations concerning protective measures required in radiologically controlled areas, and 

monitored the implementation of the Enewetak Atoll radiological protection program. The 

committee, chaired by the JTG Deputy Commander/Chief of Staff, met at least once a calendar 

quarter. Other committee members included the J-2, the Engineering Management Officer (J-3), 

the Assistant J-3 (Atoll Safety Officer), Service Element Commanders, the Staff Surgeon, the 

Enewetak Radiation Support Project (ERSP) manager, and the FRST Non-commissioned Officer 

in Charge (NCOIC). The FRST implemented the atoll radiation protection program at each 

worksite. 

The J-2 tailored the general guidance to the situations existing at Enewetak by developing 

18 Standing Operating Procedures (SOPs) and 12 Enewetak Atoll Instructions (EAIs) (DNA, 

1981) (see Appendix H. for a topical listing of SOPs and EAIs). After RCC and CJTG approval, 

these documents informed workers of what to do and how to carry out radiation safety 

procedures designed to keep personnel exposures ALARA. Personnel protection equipment 

(PPE) was a means to isolate personnel from potential internal sources of exposure and surface 

contamination on the body. Enewetak Atoll Instruction No. 5707.1, Personnel Protection Levels, 

established the basic policies and procedures and established four basic levels of personnel 

protection (I through IV) including two sublevels within levels II and III (Table 3). The levels 

allowed for a full range of protective outerwear from normal work clothing to complete 

encapsulation of the individual within protective clothing and mask. The level required was that 
41 

most appropriate for the potential hazard, and was evaluated continuously at each work site on 

each island by the FRST personnel. 

The action levels were indicators of the radiological status of a given island’s situation 

and provided points at which specific activities should occur, thus the term action level. The first 

action level was set at one-tenth of the levels noted in Table 3, and the second at one-half of the 

levels. If an action level was reached, the FRST members performed the actions specified and 

alerted the RPO to the potential hazard development. As a matter of basic policy, eating, 

drinking, and smoking were strictly regulated to minimize contamination that could enter the 

body by these routes (EAI 5605 referenced in Appendix H). Likewise, careful attention was paid 

to immediately identify any cut, wound, or break in the skin to minimize the probability for 

intake into the body (EAI 5710 referenced in Appendix H). 

3.2.2 Radiological Controls 

3.2.2.1 Radiation Controlled Areas – Equipment and Personnel 

The FRST strictly managed access to controlled islands by the implementation of 

procedures that restricted and controlled personnel movements. Controlled Island Access forms 

provided a daily log of an individuals’ presence on these islands and the use and type of 

protective clothing and equipment employed. A sample of the form is shown in Figure 5 and 

these logs became part of the official ECUP record. The degree of radiological protection 

provided by clothing and respiratory protection equipment was specified by the criteria shown in 

Table 3. The program included the radiological monitoring of personnel, vehicles, and 

equipment. Personnel exiting a radiation-controlled area were monitored for contamination. 

Measurements determined the level of contamination and the extent of personnel 

decontamination required, if any, before release from the controlled area. In addition, monitoring 

was used to document whether the equipment was cleared for release for unrestricted use. 

Two sets of criteria were applied for contamination control: one for personnel leaving a 

radiation area through a hot line, and the other for vehicles and equipment being moved to a 

radiologically clean area (DNA, 1981). 

For personnel, the following criteria were used: 

 Alpha skin contamination limit - Must not exceed 200 dpm per 100 cm2

 at contact 

 Beta skin contamination limit - Must not exceed 400 dpm per 15 cm2

 at 1 inch 

For vehicles and equipment, the following criteria were used: 

 Alpha radiation surface 

contamination limit 

- Must not exceed 1,000 dpm per 100 cm2 fixed on, or 

20 dpm per 100 cm2 removable from the surface 

 Beta radiation surface 

contamination limit 

- Must not exceed 5,000 dpm per 100 cm2 fixed on, or 

200 dpm per 100 cm2 removable from the surface 

 Gamma radiation limit - Must not exceed 15 μR h−1

at 1 foot from the surface 
42 

Figure 5. Controlled Island Access Form – Sample for Runit, July 1979, with personally identifiable 

information redacted 
43 

Table 3. Personnel radiation protection levels 

Level* Protective Clothing 

Personnel 

Monitoring 

Areas 

Action Levels 

Personnel Air Ground 

I None 

Boots 

Hands 

Hair 

Alp

h

a

<

6

0

c

p

m

B

eta

<

2

0

0

c

p

m

G

a

m

m

a

< 15



R

h

−1

Alp

h

a

<

5

5

c

p

m

h

−1

B

eta

<

3,2

5

0

c

p

m

h

−1

Alp

h

a

<

3

0

0

c

p

m

B

eta

<

5

4

0

c

p

m

G

a

m

m

a

<

2,0

0

0



R

h

−1

II 

A. Rubber boots 

B. Rubber boots and 

surgical masks 

As above plus 

arms and legs 

Alp

h

a

<

3,0

0

0

c

p

m

B

eta

<

7,2

0

0

c

p

m

G

a

m

m

a

<

2,0

0

0



R

h

−1

III 

A. Rubber boots, gloves 

(as appropriate), fullface or half face 

positive pressure 

respirator 

B. Same as IIIA plus 

anticontamination 

clothing 

Whole Body 

Alp

h

a

<

5,5

0

0

c

p

m

h

−1

B

eta

<

3,2

5

0

c

p

m

h

−1

IV 

Same as IIIB except 

gloves are now 

required, a full-face 

mask is required, and all 

openings in clothing are 

taped shut 

Whole body 

Alp

h

a

<

3

0

0,0

0

0

c

p

m

B

eta

<

7,2

0

0

c

p

m

G

a

m

m

a

<

2,0

0

0



R

h

−1

Alp

h

a

<

3

0

0,0

0

0

c

p

m

B

eta

<

7,2

0

0

c

p

m

G

a

m

m

a

<

2,0

0

0



R

h

−1

*

 Table from DNA (1981)

3.2.2.2 Contaminated Soil and Debris 

Radiological criteria were established for the disposal of contaminated soil and debris. 

All contaminated soil was transported to Runit for disposal in the Cactus Crater. Contaminated 
44 

debris was disposed of either in the Cactus Crater or at designated locations within the Enewetak 

Atoll lagoon shown in Figure 4, in accordance with the following criteria: 

 Red (C – Crater) - Gamma radiation level taken within 1 foot of object ≥100μR h

−1

 Yellow (L – Lagoon) - Gamma radiation level taken within 1 foot of surface >15 μR h−1

, 

but <100 μR h−1

- Beta radiation level >5,000 dpm per 100 cm2 at contact 

- Alpha radiation level >1,000 dpm per 100 cm2 at contact 

 Green (R – Release) - Below all “Yellow” limits. 

3.2.2.3 Personnel Dosimetry 

All personnel entering any controlled island were required to wear a dosimetric device; 

e.g., a film badge, a self-reading pocket dosimeter, and/or a thermoluminescent dosimeter (TLD). 

Personnel dosimetry provided the means by which an individual’s external beta/gamma dose 

could be measured and documented. The primary dosimetric device was the film badge—as 

prescribed by AR 40-14 (USA, 1975). The U.S. Army Lexington-Blue Grass Depot Activity 

(LBDA) provided film badge dosimeters to the ECUP. They were issued on-site and returned to 

LBDA for evaluation per AR 40-14 (USA, 1975). The dosimetry results were returned to 

Enewetak and recorded on DD Forms 1141. Dosimetry results were sent to the medical facility at 

the individual’s base of permanent assignment at first. Retroactively, they were sent directly to 

the applicable Service Dosimetry Center. In response to a Radiation Safety Audit and Inspection 

Team (RSAIT) audit recommendation, the JTG were able to effect changes to policies and 

procedures that were identified as redundant and unnecessary. Whenever film badges were 

damaged or lost, and when supplemental dosimetry was not used, JTG assigned administrative 

doses, computed according to methods approved by the Surgeon General of the Army (LBDA, 

1978). Later, the methods were amended by FCDNA to supersede the initial administrative doses 

with recalculated administrative doses (FCDNA, 1978). 

3.2.2.4 Air Sampling, Nasal Smears, and Urine Bioassays 

An air sampling program was an important part of the radiological controls for internal 

exposures. It provided a basis for the FRST to establish respiratory protection levels and to 

document airborne radionuclide levels in work and living environments. Extensive air sampling 

was conducted in these areas to monitor air concentrations for comparison with Maximum 

Permissible Concentrations (MPCs) based on the exposure guidelines shown in Table 3. The 

MPCs in air established by the U.S. Nuclear Regulatory Commission (USNRC) (USNRC, 1975) 

were used to set limits for these environments. The MPC for insoluble plutonium in air, which is 

40 pCi m−3, was based on 40 hours per week occupancy for a workweek. Since the ECUP 

workweek was typically 60 hours, the MPC was adjusted to 27 pCi m−3. In living environments, 

such as Lojwa base camp, the general population MPC was adjusted based on a 168-hour week 

(24 hours a day for 1 week). 

Airborne action levels were set at 10 and 50 percent of the MPCs (DNA, 1981). The 

10-percent MPC action level required nasal smears to be taken from all personnel in the area not 
45 

wearing respiratory protection, according to the procedures in FCRR SOP 609-04.01 (FCRR, 

1978a). The 50-percent MPC action level also required that respiratory protection be worn if 

work was to continue per SOP 608-05 (FCRR, 1977a). When these action levels were detected, 

all contaminated smear(s) and air filter(s) were expeditiously transferred to the Radiological 

Laboratory for analysis (DNA, 1981).

In addition to the 10-percent action level, nasal smears were obtained whenever deemed 

appropriate based on conditions such as air sampling results or concern for radioactivity levels in 

a given work area, to assess the potential for uptake into the body (FCRR, 1978a). While the 

nasal smears gave an immediate but only rough indication of a potential intake by measuring 

radioactive particles trapped in the nose, they did not indicate whether an intake actually 

occurred or how much radioactive material may have been inhaled (DNA, 1981). 

Nasal smears were supplemented by urine bioassays whenever applicable action levels 

were exceeded. In the event of an intake, urinalysis would provide the best way to determine 

internal dose based on the circumstances. In addition, all individuals who spent more than 30 

days on radiologically controlled islands were required to submit a urine sample at the end of 

their assignment before departure from the atoll. All samples consisted of an individual’s urine 

output for a 24-hour period. Samples were shipped for analysis to the USAF Occupational and 

Environmental Health Laboratory (USAF OEHL) at Brooks AFB, Texas (DNA, 1981). Details 

of the urine bioassay procedures can be found in (FCRR, 1978a). 

3.2.2.5 Independent Radiation Safety Audits and Inspections 

DNA Director commissioned 10 RSAITs to provide independent inspections of the 

radiological protection program and evaluate its efficacy. The team was given the widest 

authority to review all aspects of the RADSAFE program. The Director, Armed Forces 

Radiobiology Research Institute (AFRRI) headed the team, which included members, generally 

health physicists, from each of the Services and ERDA/DOE. The RSAIT performed 

broad-range inspections of radiation safety as well as environmental and occupational safety on 

the atoll. They reviewed all established procedures to ensure that radiation safety was achieved. 

They then visited selected islands and inspected the actual practices to ensure that the procedures 

were adequately implemented. 

The RSAIT made ten inspection visits to the atoll. Visits were scheduled as frequently as 

would be useful, initially quarterly and eventually about three per year. The duration of each 

inspection visit was scheduled to allow thorough observation of working conditions at the site of 

RADSAFE operation on RSAIT-selected islands of the cleanup project. Formal written reports 

were provided to Director, DNA; Commander, Field Command; and each of the Services upon 

conclusion of each trip. During the visits, the team identified and documented issues and 

recommended actions to improve cleanup operations. 

The RSAIT provided an independent assessment mechanism to demonstrate compliance 

and identify operational difficulties with established policies and procedures. In particular, 

RSAIT reports confirmed that day-to-day practices, together with recommended improvements, 

were effective in controlling radiation exposures to ECUP personnel to the limits of federally 

established radiation standards. 
46 

3.3 Identification and Resolution of Radiological Control Issues 

3.3.1. Film Badge Issues 

The high heat and humidity conditions at Enewetak damaged 90 to 100 percent of the 

film badges during the initial months of the cleanup. Typically, this damage was such that, if the 

wearers had received low doses, they would have been obscured by damage, which 

compromised the film badge image used to quantify exposure. Administrative doses were 

calculated (LBDA, 1978; FCDNA, 1978) for the period of exposures of damaged film badges. 

The first remedial action was to segregate badges visually found to be compromised by 

moisture from those that were dry when making shipments to LBDA. Previously, badges were 

aggregated together during shipment and wet badges comingled with dry badges in shipping 

boxes. This action reduced the number of damaged film badge to a level as low as 50 percent, 

still an undesirable result. An assistance visit to Enewetak by LBDA representatives led to the 

suggestion of sealing the film badges inside two plastic bags, with a small packet of desiccant in 

the inner bag. This method reduced film badge damage to as low as 11 percent in one issue 

period and as high as 20 percent in one other period, but did not eliminate the problem. 

Another solution was the addition of U.S. Navy-provided CaF2:Mn TLDs (DT-526/PD) 

to be worn as supplemental dosimeters. The TLDs were hermetically sealed devices, intended for 

underwater use by Navy divers, and were unaffected by heat and humidity such as at Enewetak. 

Additionally, they were read on site at the atoll and their readings recorded. Beginning in May 

1978, workers on radiologically controlled islands were issued and wore TLDs and film badges 

together based on the availability of TLDs. This practice was not fully implemented until March 

1979. (RSAIT, 1979a) TLDs also replaced self-reading pocket dosimeters as the dosimetry 

device for visitors. 

3.3.2. Inoperable Air Samplers 

Anecdotal ECUP veteran information indicated that the number of air samplers failing in 

use was high, especially the ones positioned on controlled access islands, and compromised the 

ability of the FRST team to adequately measure the airborne activity. Continuous air sampling 

was found to tax the performance of the equipment and frequent outages were experienced at the 

outset of the cleanup operation. The Precision Measurements Equipment Laboratory (PMEL) at 

Lojwa, a radiation instrument repair and calibration lab, maintained a staff and large number of 

replacement parts. The PMEL technicians were able to keep pace with outages by repairing 

samplers in the field or bringing them back to the lab for more complex maintenance while 

leaving behind an operable sampler (DNA, 1981). The repaired sampler was then made available 

to an exchange pool of equipment for other emerging repair/maintenance requirements. New 

samplers were ordered and kept in supply to replace those that were beyond restoration. The 

RSAIT did not report any findings that air sampler down time contributed to reduced capability 

to produce periodic assessments of airborne activity concentrations (RSAIT, 1977a, b; 1978a, b, 

c, d; 1979a, b). 

3.3.3. Availability of Personal Protective Equipment 

Initially in the cleanup operations, workers on controlled access islands wore full-face 

mask respirators. Later in the operation, forced air supply, high filtration masks replaced them. 

These masks were worn as a precaution to protect against airborne activity concentrations. The 
47 

personal protective equipment (PPE) was bulky, physically confining and taxing, and a 

significant hindrance to the task of handling and removing contaminated debris and soil. During 

this initial period, air sample measurements were taken to assess radioactive air concentrations, 

but not enough samples were taken to establish when, where, and how often, the PPE should be 

worn. During this stage, based on limited data, practices to protect workers from airborne 

radioactivity were necessarily conservative. 

As air concentration data were amassed on a larger number of controlled islands, the 

practice of wearing the bulky PPE was reevaluated and found to be unnecessary for adequate 

airborne source protection in most cases. Respiratory PPE was necessary whenever contaminated 

soil moving operations were performed (RSAIT, 1978c). Paper masks were found to be 

protective only for keeping hands, cigarettes, and other substances from entering workers’ 

mouths (Cherry, 2018a) and for occupational health protection, such as in high dust conditions. 

The RSAIT became concerned that full-face respirators being worn for extended periods 

presented an occupational health hazard to workers and reduced efficiency for accomplishing 

work tasks (RSAIT, 1978a). The RSAIT strongly recommended that PPE requirements be based 

on air sample activity concentration measurements taken on specific controlled islands while 

work was being conducted, or by specific local, island-based decisions. The actions implemented 

from the RSAIT recommendation reduced the need for confining respirators in many cases to 

only using protective clothing and paper masks. This was the case for all controlled-access 

islands, except for Runit where it was common to find increased activity concentration levels 

requiring PPE that was more protective than paper masks. 

ECUP veterans’ perception was that the lack of availability of certain types of PPE, such 

as respirators, was the reason for using masks. The need to decrease worker PPE protection was 

actually based on review and sound technical analysis of air sampling data (RSAIT, 1978a and 

1978c). 

3.3.4. High Air Sampler Readings from Natural Radon 

There were several situations of field air sample concentrations measuring higher than 

10 percent of the MPC limit for alpha activity established by federal regulations (USNRC, 1975). 

However, in each of these cases, subsequent laboratory sample analysis showed the second 

readings were within the limit of 10 percent of the MPC. Dr. John Auxier, a senior health 

physicist who was on-site with the RSAIT, suggested during a discussion with an alternate RPO 

that the samples with high readings were counted right after their removal from the filter holders 

without sufficient time for decay of naturally occurring short-lived, alpha-emitting radionuclides 

such as radon progeny (Cherry, 1978). The senior health physicist indicated that scientifically 

accepted radiological practices called for letting samples remain unmeasured for at least two 

hours to allow for decay of radon progeny collected on the filters. 

The Enewetak Rad Lab conducted a test by taking a controlled air sample to verify the 

presence, nature, and short half-lives of the radionuclides measured. An investigation determined 

that sample results that exceeded the action level of 10 percent of MPC were as a result of 

making alpha activity measurements before the two-hour waiting period had elapsed (Cherry, 

1978). Following the test, the FRST field procedures were changed for any filter showing values 

at or above the 0.1 MPC action level on the initial measurement in the field to take a second 

reading at one-half hour after the initial reading (RSAIT, 1979a). No subsequent measurements 
48 

above 10 percent of MPC limit were observed after the procedural change was implemented, 

confirming the new wait-time procedure was appropriate and effective. 

3.3.5. High Individual Film Badge Readings 

During a period of several days of surveying contaminated debris on a controlled island, 

four FRST technicians were given permission to bivouac on the island overnight for one night. 

The film badges of two of the technicians recorded doses of 0.400 rem and 0.430 rem, whereas 

the dosimeters of the other two technicians had zero readings. The high doses were about two 

orders of magnitude greater than expected based on average exposure rates on that island. An 

investigation was conducted that involved an assessment of the validity of the high film badge 

doses based on worker activities and known radiation exposure rates on the island. Although 

there appeared to be no known circumstances that could account for the recorded doses, it was 

possible to inadvertently expose the film badges if they had not been stored in a low background 

area when not in use. To test this possibility, a TLD dosimeter was placed in close contact with a 

radiological instrument check source. This TLD reading indicated an exposure rate of 5 mR h−1, 

which was not consistent with the readings of the two technicians’ film badges. 

As a further test, TLD dosimeters were placed on a pile of contaminated steel debris on 

the island that was known to contain the activation product Co-60. The TLDs were exposed for 

24 hours after being placed on the debris pile, with resulting readings of 0.519 and 0.465 rem. 

Reasonable agreement was observed between the technicians’ film badge readings and the TLD 

readings resulting from exposure on the debris pile. The investigation concluded that it was 

likely that the two technicians did not receive the radiation doses measured by their film badges. 

(Bauchspies, 1978) 
49 

Section 4. 

Radiological Survey and Monitoring 

4.1 External Radiation 

The Enewetak Radiological Survey performed by AEC in 1972 provided a database and 

general concepts for radiological cleanup. The predominant radioactive contaminants were 

identified as Sr-90, Cs-137, Co-60, Pu-239/240, and Am-241. An aerial survey for gamma 

radiation levels for all land areas was also conducted as part of the survey. Table 4 presents the 

average exposure rates at 1 meter above the surface derived from the aerial survey data for each 

island. The ranges shown are from measurements made with a Baird-Atomic, Inc. NaI 

scintillation instrument. Exposure rates determined in aerial surveys represent radiations emitted 

by soil, debris, and other contaminated material. (AEC, 1973a) 

It is evident that the northern half of the atoll had higher exposure rates than the southern 

islands in 1972. However, one of the southern islands, Biken, had slightly elevated activities as 

compared to other southern islands. Biken is situated within the fallout patterns from several 

shots that took place on the eastern and northern sides of the atoll. In addition, the island’s dense 

vegetation slowed down the migration of fallout particles through the soil by environmental 

processes (AEC, 1973a). 

Starting in June 1978 and ending in October 1979, Navy TLDs were posted to monitor 

environmental radiation levels on a number of northern islands for extended periods of about 30 

to 60 days. Actual monitoring sites on the islands were not noted in the hand-written logs found 

in the ECUP records, except for Enjebi (Janet), Boken (Irene), Aomon (Sally), Runit (Yvonne), 

Bijire (Tilda), and Lojwa (Ursula) where multiple sites of posted TLDs were specified. No 

records of the policy, procedures, and specific placement for the environmental TLDs have been 

found in the ECUP record collection at the time of this report’s publication. Table 5 presents the 

net exposure rates derived from the environmental TLD data by island and locations, where 

given, during various monitoring periods. Appendix B-1 contains the complete environmental 

TLD data transcribed from the logs. 

Lojwa Island was established as the location of a temporary base camp in the northeast 

sector of the atoll to support cleanup efforts in the northern islands, after it was removed from the 

list of controlled access islands in May 1977 (DNA, 1981; CJTG, 1977a). The environmental 

radiation levels on Lojwa were closely monitored and reported weekly on Enewetak Cleanup 

SITREP reports (hereinafter SITREP), numbered 5–124 in CJTG (1977b), during the period 

from June 26, 1977 to September 30, 1979.1 This was to ensure that the external radiation levels 

continued to be within radiological limits allowed for ECUP residents on the island. The reported 

average exposure rates taken with a micro-R meter on Lojwa ranged from approximately 2 to 

5 μR h−1 (CJTG, 1977b). 

 

1

 CJTG prepared and submitted weekly Enewetak Cleanup Situation Reports (SITREPs) from May 24, 1977 

(SITREP No. 1) through May 14, 1980 (SITREP No. 155). This collection of SITREPs is cited as CJTG (1977b). 
50 

Table 4. Summary of exposure rates at 1 meter above the surface 

Island Name Site Name Average Exposure Rate 

(μR h−1 at 1 meter)* 

Range of Exposure Rates 

(μR h−1 at 1 meter)† 

Bokombako Belle 115 5–200 

Bokoluo Alice 81 4–170 

Boken Irene 80 3–560 

Lujor Pearl 70 1–400 

Kirunu Clara 42 5–100 

Enjebi Janet 40 2–150 

Runit Yvonne 33 1–750 

Louj Daisy 21.3 5–140 

Mijikadrek Kate 19 3–22 

Kidrinen Lucy 14 1–20 

Eleleron Ruby 14 1–42 

Elle Nancy 12 1–50 

Aej Olive 11 1–15 

Bokenelab Mary 10 2–12 

Biken Leroy 7.6 3–8 

Aomon Sally 7 3–110 

Bocinwotme Edna 6 5–8 

Bijire Tilda 6 2–11 

Taiwel Percy 5 2–11 

Lojwa Ursula 5 1–7 

Alembel Vera 5 1–6 

Ribewon James 3 0–5 

Billae Wilma 2 1–3 

Ananij Bruce 1.2 0–1 

Boko Sam‡ 0.31 0–1 

Munjor Tom‡ 0.31 0–1 

Inedral Uriah‡ 0.49 0–1 

- Van‡ 0.33 0–1

Jinedrol Alvin‡ 0.31 0–1 

Jinimi Clyde‡ 0.15 0–1 

Japtan David‡ 0.31 0–5 

Jedrol Rex‡ 0.53 0–1 

Medren aka Parry Elmer‡ 0.31 0–2 

Bokandretok Walt‡ 0.18 0–1 

Enewetak Fred‡ 0.26 0–1 

Ikuren Glenn‡ 0.53 0–1 

Mut Henry‡ 0.34 0–1 

Boken Irwin‡ 0.54 0–2 

Kidrenen Keith‡ 0.64 0–2 

*

 Converted from 1972 aerial survey results for each island AEC (1973a). 

† Ranges are from measurements made at each soil sampling location on each island using a Baird-Atomic 

survey instrument (AEC, 1973a). 

‡ Activity levels on these islands are lower than the limit of sensitivity of the aerial survey equipment; for 

these, exposure rates are derived from soil sample activity concentration data (AEC, 1973a). 
51 

Table 5. Net average exposure rates by location and monitoring period derived from 

environmental TLDs posted on selected islands 

Island

Exposure Rate (μR h−1)

Ju

n - Jul 78 

Jul - A

ug 78

S

e

p - O

ct 78

O

ct - Nov 78

Nov - D

e

c 78

D

e

c 78 - Jan 79

Jan - F

e

b 79

F

e

b - Mar 79

Mar - A

p

r 79

A

p

r - May 79

May - Ju

n 79

Ju

n - Jul 79

Jul - A

ug 79 

A

ug - O

ct 79

Bokoluo (Alice) - - 23 24 18 4 31 21 25 23 - 15 13 15 

Bokombako (Belle) 8

*

8 55 36 40 7 68 49 50 50 - 33 23 18 

Bokenelab (Mary) - - - 6 3 2 4 5 8 5 5 - 7 5 

Edna's Daughter - - - - 6 5 11 6 8 7 11 5 11 8 

Olive - - 1 5 1 1 4 3 2 2 2 2 2 3 

Pearl (Park Bench) - - - - - - - - 23 12 12 - - - 

Lujor (Pearl) 7

*

3 11 0 1 2 0 - - - - - - - 

Pearl (Beach) - - - - - - - 3 2 3 1 0 5 - 

Mary's Daughter - - - 16 11 15 18 21 21 12 15 - 10 12 

Janet (FRST Shack) 7

*

- - - - - - - 4 - - - - - 

Janet (Farm) 43*36 3 9 5 4 8 8 6 9 6 6 9 4 

Janet (Farm Shack) 13*8 - 7 4 - 4 8 7 9 6 - - - 

Janet (North Point) 33*- 18 14 16 7 14 9 10 11 10 - 8 7 

Janet (Trailer) 10*8 - 5 0 2 8 5 3 4 3 9 3 2 

Percy - - - - 4 3 7 8 13 7 7 7 3 2 

Ruby - - 8 11 2 - 9 10 0 10 9 0 b 8 

Nancy - - - 16 9 10 13 12 13 12 10 - - 7 

Pearl's Daughter - - - - 9 27 11 13 14 8 13 8 26 5 

Kate - - 3 6 4 5 7 7 8 7 6 7 4 0 

Edna - - - 9 2 10 7 6 7 5 7 - 1 10 

Daisy - - 5 6 5 3 9 6 8 6 8 5 11 4 

Clare - - 5 3 4 5 9 6 7 9 4 9 9 2 
52 

Table 5. Net average exposure rates by location and monitoring period derived from 

environmental TLDs posted on selected islands (cont.) 

Island

Exposure Rate (μR h−1) 

Ju

n - Jul 78

Jul - A

ug 78

S

e

p - O

ct 78

O

ct - Nov 78

Nov - D

e

c 78

D

e

c 78 - Jan 79

Jan - F

e

b 79

F

e

b - Mar 79

Mar - A

p

r 79

A

p

r - May 79

May - Ju

n 79

Ju

n - Jul 79

Jul - A

ug 79

A

ug - O

ct 79

Irene (Set 1) 17*19 - 35 68 81 90 76 99 98†9

†

74†97†63†

Irene (Set 2) - - 0 13 9 7 11 9 10 6

‡

12‡10‡11‡7

‡

Vera 8

*

- 2 2 9 1 2 3 4 4 5 5 6 2 

Sally (Hotline) 8

*

4 - 3 1 §8 3 3 3 0 - - - 

Sally (Crypt) - - 3 7 5 6 10 7 9 11 - - - - 

Wilma 7 20 - 2 2 2 0 3 3 1 1 2 3 1 

Lucy - - 0 6 3 6 7 5 8 6 5 7 3 2 

Runit (N. Boat Ramp) 10*- 13 2 4 - - 0 7 6 - 5 - 1 

Runit (S. Quarry) 6 0 2 13 4 - - 3 7 - 1 3 1 - 

Runit (Cactus Crater) 31*- 24 25 16 - 23 20 - 29 24 22 25 13 

Runit (Hotline) 21 - 0 2 0 1 4 3 4 0 1 5 0 1 

Runit (Debris Pile) - - 2500 - - - - - - - - - - - 

Runit (FRST Shack) - - - - - 2 4 4 4 3 2 2 1 2 

Lojwa (FRST) - 3 2 2 0 0 4 1 2 3 2 1 1 0 

Lojwa (PMEL) - - - 2 0 0 2 1 2 0 2 1 0 1 

Lojwa (Mess Hall) - - - 2 0 1 2 1 1 0 1 - - 2 

Tilda (FRST Bunker) 7

*

3 2 - 0 1 0 3 3 2 - 1 0 0 

Tilda (EOD Small Bunker) - - - 5 1 2 4 3 2 2 3 3 2 - 

*

 This cell contains the gross reading from the TLD instrument and the corresponding exposure rate is based on the uncorrected reading. 

†

 Located at pit on Irene 

‡

 Located at bunker on Irene 

“-” indicates blank cell, which means that TLD data are not available to calculate an exposure rate. 
53 

In Table 5, Irene (Set 1) and Irene (Set 2) represent two entries in each environmental 

TLD log with no further identification as to what areas of the island the two distinct 

measurements were made. However, from a comparison of exposure rates to those reported in 

AEC (1973b) from the 1972 survey of Irene, it appears that TLD Set 1 is from the main island of 

Irene where the crater from Shot Seminole at Operation Redwing was formed, and TLD Set 2 is 

from the western islet or what remained of Helen. 

4.2 Soil Survey 

The AEC conducted soil sampling on each island as part of the Enewetak Radiological 

Survey in 1972. The principal radionuclides present in the samples were the same as reported in 

Section 4.1. The samples were collected manually and analyzed in the laboratory. The mean 

values for soil activity concentrations in the top 15 cm of soil, shown in Table 6, were compiled 

and reported in DOE (1982a) for Pu-239/240, Cs-137 and Sr-90, and in AEC (1973a) and DOE 

(1982b) for Co-60. The mean concentrations of Am-241 are estimated from the mean 

concentrations of Pu-239/240 as discussed in Appendix G. 

4.3 Debris Survey 

Measurements of exposure rates from contaminated debris made during the cleanup 

period were not located for inclusion in this report. All debris was surveyed in accordance with 

FCRR SOP 608-02.02. The surveys were conducted primarily to classify debris into three 

disposal categories. The radiological criteria used to classify debris are described in Section 3. A 

large majority of debris collected was not contaminated. Only about 2.5 percent of the total 

volume of debris that was collected during ECUP was contaminated with radioactive material 

(DNA, 1981). 

During the 1972 radiological survey of Enewetak Atoll’s islands, measured contact 

exposure rates greater than the local ambient levels were reported for undisturbed scrap debris on 

Enjebi, Runit, Lujor, Eleleron, Aomon, and Bokoluo (AEC, 1973a). The exposure rate 

measurements are reproduced in Appendix K, except for Bokoluo. Bokoluo island was not 

included because it had no contaminated debris, except for the wreckage of a beached LCM, 

which had a recorded exposure rate of 8 mR h−1(AEC, 1973a; DNA, 1981). 

The contact exposure rate data for contaminated debris on the five islands were analyzed 

in detail using the maps and location data from Engineering Study reports prepared by Holmes 

and Narver (H&N) (H&N, 1973). The number of exposure rate measurements and the minimum, 

maximum and geometric mean are shown in Table 7. The geometric mean of each of the five 

datasets is not significantly different from the median and therefore is considered representative 

of the average debris exposure rate on each of the five islands. 

Debris contact exposure rates were measured at 276 debris locations on these islands, 

with measurements at 250 locations or 90 percent of measurements ranging from 0.001 to 

0.40 mR h−1. At 25 debris locations, exposure rate measurements ranged from 0.50 to 8.5 mR h−1

in several isolated areas. In one isolated area on Runit, a maximum exposure rate of 60 mR h−1

was measured. In that area, a pile of concrete rubble and metal debris, estimated to be a volume 

of 222 yd3, was located on the reef north of the runway and near the Shot Erie ground zero. 

Aside from the one isolated area on Runit, measurements at six debris locations ranged from 1 to 

3 mR h−1 in areas confined to the central and northern areas of Runit. 
54

Table 6. Soil concentration data, surface to 15 cm depth soil samples, from the 1972 radiological survey 

Island Island-average Soil Concentrations in Top 15 cm (pCi g−1

)

Sr-90* Cs-137* Pu-239/240* Co-60† Am-241‡

Island Name Site Name Min Mean Max Min Mean Max Min Mean Max Min Mean Max Mean 

Bokoluo Alice 14 107.9 430 0.7 44.1 141 3.9 15.6 68 1.4 5.9 33 10.4 

Bokombako Belle 9.8 148.9 670 0.4 47.5 170 4.2 27.1 100 3.1 10 30 18.1 

Kirunu Clara 13 99.2 310 0.8 35.4 110 3.5 31.6 88 0.91 6.4 20 21.1 

Louj Daisy 3.4 107.7 380 0.9 10.5 33 3.8 31.6 98 6.4 11 26 21.1 

Bocinwotme Edna 30 68.6 220 2.7 4.7 6.4 13 19.4 24 0.33 0.43 0.63 12.9 

Boken Irene 8.4 52.8 570 0.2 7.3 41 2.4 26.2 280 0.12 5.4 520 5.2 

Enjebi Janet 1.6 72.9 630 0.6 27.0 180 0.1 16.2 175 0.02 1.9 33 3.2 

Mijikadrek Kate 1.6 43.5 200 0.1 13.1 37 0.2 11.3 50 1.6 2.7 5.8 7.5 

Kidrinen Lucy 4.4 30.1 83 0.1 10.3 25 1.5 7.7 23 0.26 1.5 3.8 5.1 

Taiwel Percy 3.6 34.6 73 0.1 7.3 17 1.5 9.0 23 0.08 0.47 2.9 6.0 

Bokenelab Mary 1.2 34.8 140 0.03 8.4 26 0.9 10.1 35 0.74 1.5 4.8 6.7 

Elle Nancy 3.6 39.3 110 0.01 11.6 28 1.3 10.1 28 0.56 1.6 5.3 6.7 

Aej Olive 2.0 21.5 70 0.1 7.7 28 1.9 8.4 30 0.65 1.5 4.1 5.6 

Lujor Pearl 2.3 28.3 140 0.2 12.4 55 0.3 38.3 530 3.6 12 70 7.7 

Eleleron Ruby 7.1 24.3 63 0.7 3.2 7.2 3.0 14.5 24 0.29 0.93 16 9.7 

Aomon Sally 0.9 16 140 0.1 5.7 30 0.2 11.0 130 0.05 0.54 69 2.2 

Bijire Tilda 2.2 19.1 54 0.04 4.2 20 1.1 6.5 34 0.61 1.2 1.9 4.3 

Lojwa Ursula 0.9 8.2 19 0.1 2.6 7.8 0.2 1.8 4.2 0.05 0.31 1.7 1.2 

Alembel Vera 1.1 12.5 68 0.03 4.4 12 0.6 4.3 25 0.02 0.3 2.2 2.9 

Billae Wilma 0.3 6.0 19 0.3 2.0 7.2 0.1 1.8 5.3 0.01 0.12 0.7 1.2 

Runit Yvonne 1.2 3.3 30 0.02 1.00 3.6 0.02 8.7 50 0.01 0.64 20 1.7 

Boko Sam 0.5 0.72 0.8 0.02 0.38 0.5 0.03 0.09 0.2 - 0.04 - 0.06 

Munjor Tom 0.18 0.72 1.2 0.07 0.32 0.56 0.01 0.08 0.13 - 0.04 - 0.05 

Inedral Uriah 0.05 0.45 1.0 0.02 0.11 0.23 0.02 0.08 0.12 - 0.15 - 0.05 

n/a Van 0.1 0.41 0.81 0.05 0.14 0.20 0.04 0.08 0.11 - 0.09 - 0.05 

Jinedrol Alvin 0.21 0.44 0.74 0.03 0.11 0.29 0.02 0.06 0.11 - 0.68 - 0.04 

Ananij Bruce 0.03 0.59 1.8 0.02 0.40 1.1 0.02 0.09 0.22 - 0.12 0.74 0.06 
55

Table 6. Soil concentration data, surface to 15 cm depth soil samples, from the 1972 radiological survey (cont.) 

Island Island-average Soil Concentrations in Top 15 cm (pCi g−1

)

Sr-90* Cs-137* Pu-239/240* Co-60† Am-241‡

Island Name Site Name Min Mean Max Min Mean Max Min Mean Max Min Mean Max Mean 

Jinimi Clyde 0.12 0.23 0.36 0.02 0.06 0.13 0.04 0.06 0.11 - 0.04 - 0.04 

Japtan David 0.08 0.55 2.6 0.03 0.40 1.0 0.004 0.05 0.23 0.009 0.03 0.14 0.03 

Jedrol Rex 0.03 0.51 1.6 0.02 0.51 1.2 0.02 0.04 0.06 - 0.09 0.36 0.03 

Medren (Parry) Elmer 0.02 0.76 5.1 0.02 0.32 1.2 0.01 0.21 5.5 0.01 0.06 0.88 0.14 

Bokandretok Walt 0.25 0.41 0.6 0.04 0.15 0.3 0.02 0.04 0.06 - 0.04 0.05 0.03 

Enewetak Fred 0.16 0.61 1.5 0.02 0.25 0.48 0.02 0.08 0.4 0.02 0.04 0.15 0.05 

Ikuren Glenn 0.09 1.37 3.9 0.01 0.60 1.8 0.005 0.11 0.3 - 0.21 0.25 0.07 

Mut Henry 0.13 0.75 2.2 0.004 0.25 0.7 0.07 0.14 0.23 - 4.3 63 0.09 

Boken Irwin 0.14 0.69 1.6 0.008 0.13 0.47 0.01 0.13 0.22 - 0.62 6.5 0.09 

Ribewon James 0.13 0.69 2.2 0.02 0.08 0.22 0.02 0.08 0.16 - 6.5 46 0.05 

Kidrenen Keith 0.03 0.88 1.8 0.01 0.28 0.81 0.01 0.11 0.17 - 0.17 0.83 0.07 

Biken Leroy 0.42 16.8 34 0.5 5.06 10 0.02 1.15 2.3 0.04 0.58 5.0 0.77 

*

 Data from DOE (1982a, Tables 7-1 to 7-3). 

†

 For the northern islands and Leroy, the mean is the geometric mean reported in AEC (1973a); an arithmetic mean was not reported. For the southern islands 

except Leroy, the mean values are reported in DOE (1982b). 

‡

 Only mean values are reported for Am-241. These values are calculated based on the mean Pu-239/240 concentrations in this table and estimated TRU to 

Am-241 ratios. A detailed discussion is included in Appendix G. 

"-" Indicates “no data”
56

Table 7. Exposure rates measured at contact on islands with contaminated debris 

Island Number of 

Measurements

Debris Contact Measurement (μR h−1)

Island Name Site Name Mean Median Min Max 

Enjebi Janet 160 27 19 3 8,500 

Runit Yvonne 85 29 30 1 60,000 

Lujor Pearl 15 147 250 3 5,000 

Eleleron Ruby 6 19 18 6 120 

Aomon Sally 10 35 19 8 3,000 

In addition, on Enjebi, there were 12 debris locations island-wide with exposure rates that 

ranged from 0.5 to 8.5 mR h−1. On Lujor, six debris locations with exposure rates from 0.8 to 

5 mR h−1 were found confined to the surface of the ground zero area of Shot Inca. On Aomon, 

the highest exposure rate of 3 mR h−1 was found at one debris location outside of a bunker. 

It is important to note that the measured contact exposure rates described above do not 

represent the general exposure conditions for ECUP participants in debris-handling scenarios. 

Debris exposure rates to cleanup operators are expected to have been lower than the measured 

contact exposure rates by at least an order of magnitude. About 80 percent of the contact 

exposure rates measured at debris locations in 1972 were less than 0.1 mR h−1, which was the 

threshold to mark debris in the red category that would be removed for disposal in the Cactus 

Crater; see Section 3. Applicable exposure rates for participants in debris-handling scenarios are 

discussed in Section 6 and Appendix K. 

4.4 Air Monitoring 

Airborne activity concentrations were monitored during the cleanup of Enewetak Atoll. 

One to five air samplers were positioned downwind of all earthmoving operations. Filters were 

monitored every two hours and changed every day (DNA, 1981). 

Throughout the cleanup project, approximately 900,000 m3 of air were sampled, of which 

760,000 m3 of air were sampled on the controlled islands. The radiation laboratory on Enewetak 

Island analyzed about 5,200 air filter samples. No significant airborne radioactive material of any 

type was detected. (DNA, 1981) 

The Radiological Safety Plans officer periodically reported summaries of air sampling 

data collected on controlled islands throughout the cleanup project. Examples of summaries for 

Enjebi are shown in Table 8. In addition, weekly summaries of air sampling results for various 

locations were reported in weekly SITREPs. The sampling locations included areas on the 

controlled access islands, on residence islands, as well as watercrafts that transported excavated 

contaminated soil. Similar statistics as those shown in Table 8 were used to summarize the data 

collected for the weekly SITREP at these locations. Data summary Types A to F defined in 

Table 9 correspond to Columns AAA to FFF in the weekly SITREPs. A sample SITREP 

containing air-sampling results is provided in Appendix B-3
57

In addition, environmental air samples were routinely collected on Lojwa to verify that 

this resident island for ECUP participants remained within the established radiological limits. 

The total volume of air sampled and the findings were reported on weekly SITREP reports, 

numbered 5-124 of CJTG (1977b), during the period from June 9, 1977 to September 30 1979. 

The results consistently showed that there was no detectable or no significant activity found on 

the air filters. 

Table 8. Summary of air sampling data for Enjebi (Norton, 1980) 

Type Data Summaries Apr–Sept†

1977

Jan–Dec 

1978

Jan–mid May†

1979

A Volume of air sampled (m3) 35,398 51,516 17,289 

B Number of filters analyzed 115 359 108 

C Zero readings 58 211 27 

D < 0.27 pCi m−3(≤ 1% MPC

*

) 55 148 81 

E 0.27 to < 2.7 pCi m−32 0 0 

F ≥ 2.7 pCi m−3(≥ 10% MPC) 0 0 0 

G Highest reading (pCi m−3) 0.39 0.18 0.15 

H Average reading (pCi m−3) 0.08 0.03 0.03 

*

 The MPC was established at 27 pCi m−3 for insoluble airborne Pu-239, which is based on a 60-hour workweek 

for personnel entering controlled access islands; details are included in Section 3.2.2 (USNRC, 1975). 

† The reference does not report results for Oct–Dec 1977, nor results after mid May 1979. 

The overall statistics of the air sampling data collected during the cleanup can be found in 

Appendix B of DNA (1981). 

Table 9. Summary of air sampling data collected throughout 

the Enewetak Cleanup Project 

Type Data Summaries Enewetak Cleanup Project

A Volume of air sampled (m3) 866,227 

B Number of filters analyzed 5,204 

C Zero readings 2,667 (51.2%) 

D < 0.27 pCi m−3(≤ 1% MPC

*

) 2,336 (44.9%) 

E 0.27 to < 2.7 pCi m−3201 (3.9%) 

F ≥ 2.7 pCi m−3(≥ 10% MPC) 0 

*

 The MPC was established at 27 pCi m−3 for insoluble airborne Pu-239, which is based on a 60-hour workweek 

for personnel entering controlled access islands; details are included in Section 3.2. (USNRC, 1975) 

4.5 Lagoon and Ocean Water 

Activity concentrations of fission and activation products, and TRU radionuclides were 

measured in samples of lagoon and ocean water during the 1972 AEC radiological survey (AEC, 

1973a). Fifty-four lagoon, crater, and ocean water samples were collected at 38 locations shown 
58

in Figure J-1. Forty samples were collected from the lagoon, twelve from craters, and two 

samples were collected from the ocean near the Deep Entrance of the atoll, east of Medren and 

Japtan Islands. Cesium and plutonium were detected in all samples. Fifteen lagoon samples, 

primarily from the northern half of the lagoon, contained detectable amounts of Co-60, Eu-155, 

Bi-207, or Am-241; these radionuclides were not found in any other water samples. Results for 

several other radionuclides (Rh-102m, Ru-106, Sb-125, Eu-152, and U-235) were below 

detection limits in all samples. Table 10 provides a summary of the means and ranges of activity 

concentrations for Cs-137, Pu-239/240, and Pu-238 in 32 shallow and 8 deep lagoon water 

samples. Results for these three radionuclides in the two ocean water samples are provided in 

Table 11. Sampling locations and analysis results for all fifty-four water samples are shown in 

Table J-1. 

Table 10. Radionuclide activity concentrations in lagoon water samples 

Sample Depth 

(ft) 

Water activity concentrations (fCi kg−1)

*

Cs-137 Pu-239/240 Pu-238 

Mean Range Mean Range Mean Range 

3 325 59–766 29 0.38–96.1 4 0.03–14.9 

90–195 341 190–497 506 2.8–3780 164 0.14–1280 

*

 See Table J-1 for sample results and locations.

Table 11. Radionuclide activity concentrations in ocean water samples 

near Enewetak Atoll

Water activity concentrations (fCi kg−1) 

Sample Location and 

Depth* Cs-137 Pu-239/240 Pu-238 

East of Medren (3 ft) 32 0.43 0.01 

East of Japtan (3 ft) 146 0.21 0

* Ocean samples were taken from two locations near the Deep Entrance to the lagoon. See Figure J-1 for sample 

locations.

Table 12 provides the mean activity concentrations of Cs-137 and Pu-239 in surface 

water in four quadrants of the lagoon (AEC, 1973a). As expected, the data show that the 

northwestern and northeastern quadrants exhibit the highest concentrations because most of the 

Enewetak tests were conducted on and near the islands in these quadrants, and the islands in 

these quadrants had the highest measured soil contamination levels in the atoll (see Section 4.2). 

The southwestern quadrant concentration levels were somewhat elevated, likely because the 

islands in this quadrant received fallout from atmospheric nuclear tests that took place on the 

islands in the northeastern quadrant of the atoll (AEC, 1973a). 
59

Table 12. Mean activity concentrations of Cs-137 and Pu-239 in surface water samples 

collected from the four quadrants of the lagoon 

Sample Location 

in Enewetak Lagoon

Activity Concentration (fCi L−1)

*, †

Cs-137 Pu-239

Southeastern quadrant 226 9.1 

Northeastern quadrant 334 42.6 

Northwestern quadrant 579 33.4 

Southwestern quadrant 332 21.6 

Ocean, east of Enewetak Atoll 89 0.3 

*

 From Table 56 of AEC (1973a). 

†

 The units fCi L−1 and fCi kg−1 are considered equivalent in AEC (1973a). 

4.6 Lagoon Sediments 

Radionuclides were distributed non-uniformly in lagoon sediments of Enewetak Atoll. 

The sediment layer was generally thin, and most sampling conducted in 1972 was limited to no 

more than a few centimeters due to the nature of the sedimentary deposits. The highest activity 

concentrations were generally in the northwestern portion of the lagoon, and the southern portion 

of the lagoon was generally uncontaminated (AEC, 1973a). Table 13 provides the mean activity 

concentrations of radionuclides found in lagoon sediments averaged over the entire lagoon. 

Radionuclide activity concentrations in lagoon sediments for all areas of the lagoon are presented 

in Figures 52–64 and Tables 45–47 of AEC (1973a). 

Table 13. Mean radionuclide activity concentrations 

in Enewetak Lagoon sediments 

Radionuclide Activity per Unit Area 

(mCi km−2)

*

Sr-90 586 

Pu-239/240 463 

Eu-155 369 

Am-241 172 

Bi-207 163 

Cs-137 78

Co-60 73 

Sb-125 22 

Rh-102m 8.4 

Eu-152 2.5 

Rh-101 1.2 

* From Table 47 of AEC (1973a)
60

4.7 Food and Drinking Water 

4.7.1. Local Foods 

Local terrestrial and marine foods were collected during the Enewetak Radiological 

Survey from October 1972 to February 1973 (AEC, 1973a). The survey goals were to provide 

the data needed for rating the relative importance of radionuclides and pathways leading to doses 

to future residents of Enewetak Atoll. The data also helped guide cleanup decision-making 

affecting the future use of the islands and provided a basis for radiological levels encountered by 

ECUP workers that may have consumed local foods. 

Because of their relatively long half-lives, activity concentrations in foods, and potential 

contribution to internal doses, Co-60, Sr-90, Cs-137, and Pu-239/240 are considered key 

radionuclides for all local foods included in this analysis. In addition, Am-241 is included for 

one local food (fish). 

There were limited terrestrial foods available for sampling during the 1972–1973 survey 

(DNA, 1981). Coconuts and coconut crabs were sampled and are included in this analysis. 

Coconuts were a staple food of the Enewetak people, but very few coconut trees were growing 

on the atoll after the nuclear testing ended in 1958. Multiple samples of coconut meat and milk 

from various islands were analyzed and the results are shown in Table 14 and Table 15. Coconut 

crabs were part of the diet for the native Enewetak population and ECUP participants might have 

eaten them according to some anecdotal accounts (Cherry, 2018b; Fitzgerald, 2017). Table 16

presents the activity concentrations of the key radionuclides found in coconut crabs from various 

islands at Enewetak Atoll (AEC, 1973a). Analysis results for less consumed foods such as 

pandanus, breadfruit, and arrowroot are not included here because no accounts suggesting that 

ECUP participants consumed these foods were found. 
61

Table 14. Activity concentration of radionuclides in coconut meat at Enewetak Atoll 

Island 

Concentration (pCi g−1 dry weight)*

Co-60 Sr-90 Cs-137 Pu-239/240 

Louj Daisy < 0.059 0.200 7.17 No data 

Boken Irene 

< 0.067 0.067 1.77 0.0362 

< 1.7 1.61 5.11 < 0.034 

Enjebi Janet < 0.069 0.207 84.7 No data 

Bokenelab Mary 

< 0.055 0.136 14.3 0.0005 

< 0.017 14.1 5.58 < 0.43 

Elle Nancy < 0.054 0.167 18.8 < 0.0006 

Alembel Vera < 0.053 0.134 9.30 0.00013 

Runit Yvonne 

0.077 0.011 3.96 No data 

< 0.066 < 0.054 1.99 < 0.0020 

Ananij Bruce < 0.014 No data 0.582 No data 

Japtan David 

< 0.060 0.014 2.59 0.0027 

< 0.012 0.026 0.399 0.0034 

Medren Elmer 

< 0.028 < 0.075 3.45 < 0.0052 

< 0.068 0.032 2.14 0.00044 

Enewetak Fred 

< 0.020 0.030 2.39 No data 

< 0.021 0.367 0.530 < 0.0058 

Ikuren Glenn 

< 0.053 < 0.049 1.30 < 0.0013 

< 0.029 0.02 1.01 < 0.0025 

Mut Henry < 0.007 <0.028 0.565 < 0.001 

Boken Irwin 0.074 <0.086 0.29† < 0.0027 

Kidrenen Keith < 0.064 <0.056 0.952 < 0.0009 

Biken Leroy < 0.015 0.189 3.9 0.00073 

*

 Data were extracted from Table 164 in AEC (1973a). 

†

 The number "0.29" is presumed to be the value athough"0.2~9" is shown in Table 164 in AEC (1973a). 
62

Table 15. Activity concentrations of radionuclides in coconut milk at Enewetak Atoll 

Island 

Concentration (pCi (g, wet)−1)

*

Co-60 Sr-90 Cs-137 Pu-239/240 

Louj Daisy < 0.051 0.068 0.084 < 0.0016 

Boken Irene < 0.15 < 0.077 No data < 0.0086 

Enjebi Janet < 0.03 0.084 11.2 < 0.0005 

Bokenelab Mary < 0.016 0.042 4.52 < 0.0046 

Elle Nancy < 0.06 0.051 6.65 < 0.0010 

Japtan David < 0.012 < 0.023 1.09 < 0.0015 

*

 Data were extracted from Table 165 in AEC (1973a). 

Table 16. Activity concentrations of radionuclides in coconut crab at Enewetak Atoll 

Island 

Concentration in Muscle (pCi (g, dry)−1)

*

Co-60 Sr-90 Cs-137 Pu-239/240 

Ananij Bruce 0.198 0.185 1.98 0.0012 

Ikuren Glenn 0.247 Not Reported 1.88 0.0013 

Ribewon James 1.05 0.079 1.25 0.00076 

Kidrenen Keith 0.42 1.19 1.92 0.0014

Biken Leroy 1.23 1.58 12.6 0.0031 

* Data were extracted from Table 169 in AEC (1973a).

The marine sampling program was focused on fish since they are commonly eaten by the 

Marshallese and might have been consumed by ECUP workers during recreational activities 

(Cherry, 2018b; Fitzgerald, 2017). The sampling included reef and bottom (lagoon) feeders as 

well as pelagic species. The concentrations of key radionuclides averaged over all fish from the 

entire atoll are summarized in AEC (1973a). In addition to fish, marine invertebrates that were 

reportedly consumed were also sampled, including lobsters and clams. Enewetak cleanup 

veterans have indicated that local lobsters were eaten (Fitzgerald, 2017). One ECUP veteran 

suggested that ECUP participants might have also eaten the large "killer" clams, Tridacna gigas, 

during the deployment. The giant clam and the smaller clam, Tridacna crocea, were the two 

species collected during the 1972–1973 survey. The differences in the activity concentrations 

between the larger and smaller clams were not significant (AEC, 1973a). Because of the claim 

suggesting consumption of the giant clam, only the consumption of mantle and muscle of giant 

clams is considered here, assuming that the viscera and kidney were not consumed. Activity 

concentrations of radionuclides in clams from various islands at Enewetak Atoll are shown in 

Table 17. Average concentrations of key radionuclides in the edible parts of all local foods 

considered here as potentially consumed by ECUP participants are shown in Table 18. 
63

Table 17. Activity concentrations of radionuclides in clams at Enewetak Atoll 

Island 

Concentration in Mantle and Muscle (pCi (g, dry)−1)

*,†,‡

Co-60 Sr-90 Pu-239/240 

Bokoluo Alice 3.9 0.10 0.05 

Bokombako Belle§18 0.5 0.24 

Enjebi Janet 20 0.02 0.094 

Mijikadrek Kate 0.5 0.01 0.50 

Bijile Tilda 1.3 0.009 0.49

Jedrol Rex 22 0.013 0.015 

Bokandretok Walt§2.5 0.018 0.06 

Ikuren Glenn§7.6 0.21 0.016 

Mut Henry 13 0.02 0.90 

Biken Leroy§4.5 0.01 0.014 

* Data were extracted from Table 39 in AEC (1973a). 

† Only the activity concentrations for “mantle and muscle” of the clams were used for consumption of giant 

clams. 

‡ Cs-137 and Am-241 were not detected in the vast majority of the analyzed clam samples so they were not 

included. 

§ Sr-90 was not detected in the samples collected from these islands. To high side the average activity 

concentrations, their respective detection limits for Sr-90 were used.
64

Table 18. Average activity concentrations of radionuclides in the edible part of local foods 

at Enewetak Atoll that were potentially consumed by cleanup participants 

Food

Activity Concentration (pCi g−1, dry weight)*,†,‡

Co-60 Sr-90 Cs-137 Pu-239/240 Am-241 

Fish 2.00 0.075 0.39 0.248 0.114 

Spiny Lobster 0.29 0.020 0.018§0.0060 – 

Coconut Meat 0.12 0.80 7.5 0.030 – 

Coconut Milk 0.053 0.058 4.71 0.0030 – 

Coconut Crab 0.629 0.759 3.93 0.0016 – 

Clam (giant)** 9.33 0.091 – 0.24 – 

*

 Averages based on data reported in AEC (1973a) except as noted otherwise: for coconut meat, see Table 164; for 

coconut milk, see Table 165; for coconut crab, see Table 169; for fish, average concentrations are reported in 

Table 158 except for Sr-90 the average concentration is for muscle only and is taken from Table 159; and for lobster, 

average concentrations are reported in Table 41 except for Cs-137 (see note below). (AEC, 1973a) 

†

 The concentrations are in pCi g−1 dry weight except pCi g−1 wet weight in coconut milk. 

‡

 The averages are calculated with non-detect sample concentrations set equal to the detection limits. 

§

 Concentrations of Cs-137 in spiny lobster muscle were not reported in AEC (1973a). The value shown is the highest 

value in samples collected in 1978–1979 reported in Table 6 of Ebert and Ford (1986). 

** Concentrations are from Table 39 (AEC, 1973a). In addition to Am-241, Cs-137 was not detected in the vast 

majority of the analyzed clam samples. So they were not considered as key radionuclides for clams.

“–” indicates not detected in any sample or not considered as a key radionuclide (AEC, 1973a).

4.7.2. Drinking Water 

One drinking water sample was taken for radiological analysis from the distillation plant 

on Enewetak Island during the 1972 AEC radiological survey (AEC, 1973a). No radiological 

contamination was found in the water. However, Sr-90 and Pu-239 were detected in two sludge 

samples from the plant. The highest Pu-239 concentration in the sludge was 56 pCi g−1(DNA, 

1981). 

Three tap water samples from Enewetak Island and one from a water truck on Enjebi 

were collected in March 1978. The tap water was distilled from seawater. The activity 

concentrations of Cs-137, Pu-239/240, and Pu-238 were measured in these samples. The results 

of the analysis are shown in Table 19 as reported in Noshkin et al. (1981). 

Additional drinking water samples were taken in December 1979 from campsite 

facilities, the community center, dining hall, Dorm Building 462, recreational center, and clinic. 

However, the samples were analyzed for bacteriological and chemical contents only (USAF 

Clinic/SGV, 1980). 
65

Table 19. Activity concentrations in drinking water from Enewetak and Enjebi Islands 

Sample type Island 

sampled

Date 

collected

Concentration (fCi L−1)

*

Cs-137 Pu-239/240 Pu-238 

Distilled seawater Enewetak 3/18/78 18 (8)†0.6 (40) < 0.1 

Distilled seawater Enewetak 3/18/78 20 (8) 0.4 (50) < 0.1 

Distilled seawater Enewetak 3/18/78 22 (8) 0.3 (70) < 0.1 

Water truck Enjebi 3/21/78 10 (14) 5.4 (22) 0.2 (40) 

*

 Data taken from Noshkin et al. (1981). 

†

 Values in parentheses are the percent standard deviation of the counting error. 

4.8 Personnel Dosimetry (Film Badge, TLD) 

This section provides a summary of personnel dosimetry records compiled during the 

ECUP operations. As mentioned in Section 3.2, the U.S. Army LBDA administered the film 

badge personnel monitoring program for ECUP-monitored workers per AR 40-14 (USA, 1975). 

Beginning in May 1977, film badges were issued to all ECUP workers assigned to controlled 

access islands. In May 1978, the program was supplemented by Navy-supplied TLDs to reduce 

the need to administratively assign doses because many film badges were damaged by high 

ambient temperatures and humidity on the atoll. The JTG policy (DNA, 1981) was to issue TLDs 

together with film badges to the extent that these were available (RSAIT, 1979a). In March 1979, 

TLDs and film badges were issued together to all controlled island access workers. Generally, 

workers wore dosimeters for four to five weeks and were reissued new dosimeters as long as 

they continued duty on controlled access islands. 

The LBDA evaluated the film badges received from Enewetak and entered the dosimetry 

readings in a database now maintained by U.S. Army Dosimetry Center (ADC) at Redstone 

Arsenal in Huntsville, AL. The Navy-supplied TLDs were read on-site and readings were sent to 

the LBDA to be stored in the ADC database. Cumulative dosimetry readings for controlled 

island access workers were sent from the JTG via DD Form 1141 to the dosimetry center of the 

individual’s respective military service. The military personnel film badge dose records are 

summarized in Table 20. 

The highest, valid dosimeter reading for an individual participant was 0.070 rem, which 

is less than 1.4 percent of the 5.0 rem yearly limit established for the project. Two single film 

badge readings of 0.400 and 0.430 rem were recorded. In-depth investigations revealed that these 

did not represent valid doses to individuals but that they may have resulted from film badges 

having been left on or near contaminated debris or a calibration check source overnight 

(Bauchspies, 1978). 

Administrative dose assignments were required per AR 40-14 (USA, 1975) and were 

designed to use conservative assumptions so the dose estimates were biased high. 

Administratively assigned doses ranged from 0 to 0.020 rem for any one-month issue period 

according to the ADC database for ECUP dosimetry. Finally, over 7,500 TLD readings were 

recorded starting in May 1978. Dose records for TLDs are summarized in Table 20. 
66

Table 20. Summary of personnel dosimetry 

(DNA, 1981) 

Film Badge Dosimetry

Doses Reported 12,248

Zero Readings* 8,361 (68.3%) 

1–10 mrem 3,712 (30.3%) 

11–20 mrem 157 (1.3%) 

> 20 mrem 18 (0.1%) 

TLD 

Doses Reported 7,519 

Zero Readings* 2,763 (36.7%) 

1–10 mrem 4,735 (63.0%) 

11–20 mrem 12 (0.2%) 

> 20 mrem 9 (0.1%) 

* Readings with reported values of zero were obtained from 

dosimeters with doses of less than 1 mrem. 

4.9 Bioassay 

A bioassay program was used to assess and document internal deposition of radioactive 

material, which might have occurred through inhalation, ingestion, or skin penetration (i.e., 

wounds). The two principal bioassay techniques used were the nasal smear (nose swipe) and 

urinalysis. 

4.9.1. Nasal Smears 

Nasal smears were used at the hotlines for plutonium-contaminated areas as the primary 

method of checking the adequacy of respiratory protection (DNA, 1981). During the project, 

over 1,100 nasal smears were obtained and analyzed. Results listed in Table 21 indicate that 

about 65 percent of the samples showed no detectable activity, i.e., zero or less than the 

minimum detectable activity (MDA). Of those smears that did show activity, the highest was 

3.64 dpm (1.64 pCi of plutonium), which is much lower than the maximum allowable level for 

plutonium of 500 dpm (DNA, 1981). 

Table 21. Results of nasal smears 

Parameter Value*

Total Nasal Smears Taken 1,145 

Range of activity 0–1.64 pCi of Pu 

Activity = 0 317 (27.7%) 

Activity < MDA 439 (38.3%) 

Activity  MDA 389 (34.0%) 

*

 Data from DNA (1981) 
67

4.9.2. Urine Bioassay 

As part of the ECUP Bioassay Program (FCRR, 1978a), over 2,000 24-hour urine 

samples were analyzed for activity concentrations, primarily for total or gross beta radiation 

(GB), Pu-239, and K-40. On a random basis, some samples were also analyzed specifically for 

Cs-137, Co-60, or Co-57. Summary results are listed in Table 22. 

Table 22. Summary of urine bioassay results 

Parameter Value*

Total Urine Samples Taken 2,338 

Potassium-40 (K-40) ‒ Range: < 50 to 4,100 pCi L−1

‒ 2,313 readings (98.9%) ≤ 2500 pCi L

−1

Gross Beta (GB) ‒ Range: < 300 to 4,200 pCi L−1

‒ 2,315 readings (99.0%) ≤ 2500 pCi L

−1

Ratio of GB to K-40 ‒ Range: 0.27 to 3.05 

‒ 2,305 readings (98.6%) ≤ 2.00

Plutonium-239 (Pu-239) ‒ Range: < MDA to 0.12 pCi d−1

‒ 2,332 readings (99.7%) < MDA 

* Data from DNA (1981)

The naturally occurring radionuclide K-40 accounts for a very small fraction of about 

0.012 percent of natural potassium (NNDC, 2019), and enters the body through a normal diet. 

An adult person normally excretes 25 to 125 millimoles of potassium per day (Anderson, 2003), 

which would include about 820 to 4,100 pCi of K-40. Assuming that the average daily excretion 

volume of urine is 1.5 L, the normal range of K-40 concentration in urine is about 550 to 

2,700 pCi L−1. Figure 6 shows an example report of a urine sample analysis, which shows almost 

equal values of GB and K-40 activity concentrations. Because K-40 is a beta-emitter, it accounts 

for essentially the entire GB measured in this sample, with insignificant amounts of other betaemitting radionuclides present. 

In addition to K-40, the GB count was indicative of any beta-emitting radionuclides such 

as Cs-137, Sr-90, and Co-60, which might have been taken up at Enewetak. If any bioassay 

results had indicated possible uptake of these beta-emitters, specific measurements for Sr-90 or 

Cs-137 would have been made. “Significant uptake” was defined using a threshold GB value on 

the order of 5,000 pCi L−1 and a GB to K-40 ratio threshold value of 3. No bioassay results 

exceeded the GB threshold. The highest GB to K-40 ratio was 3.05, and in that sample the GB 

value was well below the GB threshold value. These results indicate there was no significant 

uptake of beta-emitting radionuclides by ECUP participants. (DNA, 1981) 
68

Figure 6. Example of urine bioassay report (some information redacted)8

Plutonium activity concentration results were based on an individual’s total daily 

(24-hour) urine output, and were reported as pCi of Pu-239 in the sample9 (see Figure 6). At the 

time ECUP was underway, a trigger level was established based on the proposal of the American 

Health Physics Society Plutonium Bioassay Committee that, if the plutonium concentration 

exceeded 0.20 pCi per 24-hour sample, a second sample should be taken for verification. No 

ECUP samples exceeded this trigger level. Results for all but 6 of over 2,000 samples were 

below the MDA. The six samples that exceeded the MDA included one measurement at 0.05, 

two at 0.06, two at 0.08, and one at 0.12 pCi. In each case where the MDA was exceeded, dose 

estimates were made. The estimates indicated that no significant doses were received. Moreover, 

a second sample was obtained from each individual where the initial measurement exceeded the 

MDA and, in each case, the second sample result was less than the MDA. (DNA, 1981) 

 

8

 This report was generated by the USAF Radiological Health Laboratory, which at the time was in the process of 

being relocated to Brooks AFB, TX and reorganized under the USAF OEHL. 

9

 Pu-239 activity value includes contributions from Pu-240. 
69

Section 5. 

Sources, Pathways and Scenarios of Radiation Exposure 

Participants in the ECUP were potentially exposed to external gamma and beta radiation 

and internal radiation from the intake of radioactive materials by inhalation and ingestion, or 

through wounds. As discussed in Section 3, the radionuclides of concern are Sr-90, Cs-137, 

Co-60, Pu-239/240, and Am-241. In this section, contaminated media encountered by ECUP 

participants during the cleanup are discussed in Section 5.1, and relevant external, internal, and 

skin exposure pathways are identified in Section 5.2. Participants’ potential exposures to 

contaminated materials are categorized based on a set of project components, tasks, and specific 

project activities that are presented in Section 5.3. 

5.1 Potential Sources of Radiation Exposure 

Potential sources of radiation exposure for ECUP participants include contaminated soil, 

(by itself and mixed into slurry), debris, concrete structures, lagoon water and sediment, food and 

drinking water. These sources are discussed in the following sub-sections. 

5.1.1. Contaminated Soil 

Contaminated soil was a source of potential radiation exposures to several categories of 

ECUP personnel who performed activities associated with soil cleanup operations or other 

project tasks. Contaminated soil consisted of undisturbed and disturbed ground surface soil; soil 

excised and placed into windrows, piles, dump trucks, and landing craft; and soil mixed with 

cement in the Cactus dome. 

Ground surface soil on Enewetak Atoll islands was potentially contaminated with 

radioactive material. External exposure rates from soil, and activity concentrations in soil are 

shown in Table 4 and Table 6, respectively. This source might have been encountered during 

brush removal, soil and debris cleanup operations, as well as during other activities such as 

radiological sampling and monitoring, and construction activities. Personnel who worked on the 

southern islands and residence islands may have been exposed to isolated spots of contaminated 

surface soil (DNA, 1981). However, in general, the soil on the southern islands was not 

contaminated and the average external exposure rates were less than the cosmic radiation 

background range of 3.9 to 4.7 μR h

−1

. This background range is based on TLD readings of 10 to 

12 mR accumulated over a three-and-one-half month exposure period (AEC, 1973a). 

Windrows and piles of excised contaminated soil represented another potential source of 

radiation exposure. These sources were located on the islands of Boken, Enjebi, Lujor, Aomon, 

and Runit, where contaminated soil was removed and eventually contained in the Cactus Crater 

and dome (DNA, 1981). Soil windrows and piles are treated as a different source category from 

undisturbed surface soil because they have different source geometries than contaminated ground 

such as size and shape, they had a greater likelihood for soil suspension, and they may have had 

higher contaminant concentrations than the surrounding ground. Soil activity concentrations of 

excised soil that was placed into windrows or piles are discussed in Section 7. This soil was a 
70

potential source of exposure for individuals who were involved in soil removal and transport, as 

well as those who performed radiological control and survey activities. 

Contaminated soil transported to Runit was off-loaded and moved to stockpiles for use 

during the tremie disposal operations. Stockpiled soil was loaded onto trucks and transported to 

the batch plant for incorporation with cement, water and other aggregates to produce the slurry 

that was disposed of in the Cactus Crater to form hardened concrete. Soil activity concentrations 

of transported and stockpiled soil are discussed in Section 7. A discussion of the soil slurry as a 

source of potential exposure to radiation is given in Subsection 5.1.2. 

Exposure to contaminated soil excised from the five islands mentioned above was 

possible during transport by dump trucks, landing craft, and floating platforms. Other individuals 

who may have been exposed to contaminated soil were those who worked at the batch plant 

including the screening plant. In addition, personnel who provided close support to tremie 

operations in and around contaminated soil had the potential to be exposed to this source of 

radiation. 

Exposure to contaminated soil during transport by dump trucks, landing craft, and 

floating platforms was also possible for the limited quantity of soil removed from Medren. 

Medren is not included as one of the soil-removal islands above because the soil removed from 

Medren did not contain any TRU contamination (DNA, 1981). It is mentioned here because 

about 110 yd3 of soil contaminated with Co-60 that was identified in a limited area on the island 

was removed and transported to Runit over a four-day period in February 1978. The 

contaminated soil on Medren was excavated by backhoe, loaded directly into dump trucks that 

were driven to the boat ramp and transported by LCUs to Runit (DNA, 1981). Personnel 

potentially exposed to this source include operators of heavy equipment, e.g., dump trucks, 

loaders, and water transport personnel. 

Another potential source of radiation exposure was the contaminated soil that was mixed 

with cement and water to form the dome over the Cactus Crater on Runit. The soil-cement dome 

was constructed over the hardened concrete slurry and debris that filled the crater during the 

tremie operations. The operators of heavy equipment and other personnel involved in this 

activity, such as surveyors, ground spotters/guides, radiological monitors, etc., could have been 

exposed to this source of radiation. 

5.1.2. Soil Slurry 

Contaminated soil slurry was produced for containment in the Cactus Crater on Runit 

during the tremie operations. The contaminated soil that was removed from islands other than 

Runit was stockpiled on Runit. The soil was mixed with cement, attapulgite clay, and water at 

the batch plant on Runit, and then loaded onto transit-mix trucks. The components were mixed to 

form slurry in the transit-mix trucks as they were enroute to the tremie pump positioned at the 

rim of the crater. The slurry was then pumped through a small feeder pipe to a floating barge 

where it flowed down through a tremie pipe to the bottom of the crater. In some areas of the 

crater, the transit-mix trucks dumped the slurry directly into the crater at its rim. In addition, 

contaminated debris stockpiled on Runit from other islands was placed in the crater. Slurry was 

used to choke this debris and encase it into the concrete mass. The tremie operations started on 

June 15, 1978 and were completed on February 10, 1979 (DNA, 1981). 
71

Because of the inclusion of contaminated soil, slurry was a potential source of exposure 

to individuals involved in the mixing, transporting, and pumping operations. Soil activity 

concentrations of excised soil before mixing into slurry are discussed in Section 7. Slurry that 

was rejected from pumping due to unsatisfactory consistency and homogeneity was dumped 

from the transit-mix trucks into trenches and was allowed to harden. Once hardened, blocks of 

the dried material were loaded into dump trucks, transported to and dumped directly into the 

crater. This “processed tremie” method was used only when necessary and disposal was limited 

to eight loads per day unless approved by CJTG (DNA, 1981). 

5.1.3. Contaminated Debris 

Contaminated debris was collected from the islands of Enjebi, Lujor, Eleleron, Aomon, 

and Runit, and transported for disposal at lagoon disposal sites and the Cactus Crater. Most of 

the contaminated debris was removed from Runit and Aomon, with Runit debris accounting for 

over 50 percent of the total volume (DNA, 1981; DOE, 1982a). The debris cleanup activities 

consisted of offshore collection by divers, winch operators, and EOD personnel; onshore 

collection from beach and inland areas; consolidation and handling by heavy equipment, e.g., 

bulldozers, cranes, etc.; loading, off-loading, and transport using dump trucks, landing craft, 

barges and floating platforms; and disposal in the lagoon or in the Cactus Crater on Runit. The 

divers, operators of heavy equipment on-land and offshore, personnel involved in water transport 

and disposal of debris, as well as those who performed radiological control and survey activities, 

could have been exposed to this source of radiation. 

Another type of contaminated debris consisted of small plutonium-contaminated 

fragments that were located and removed from the Fig-Quince ground zero (GZ) area on Runit 

and the Kickapoo GZ area on Aomon. These fragments were located and removed primarily by 

members of the FRST during November and December 1977 for the Fig-Quince area (DNA, 

1981), and October 1978 for the Kickapoo area (DNA, 1981). 

In addition to being a potential source of external exposure, there was a potential for 

dermal contamination and internal exposure from soil suspended during handling contaminated 

debris. 

5.1.4. Contaminated Concrete Structures 

Concrete debris consisting primarily of non-contaminated slabs, blocks, pads, walls, and 

rubble was found on several islands (DNA, 1981; H&N, 1973). Concrete structures including 

bunkers and buildings were also located on several islands. In many cases, bunkers were not 

radiologically contaminated and were made safe by covering or sealing with concrete or by 

removing doors and protruding hazards and leaving them otherwise intact for subsequent use 

(e.g., as typhoon shelters) (DNA, 1981; H&N, 1973). Contaminated concrete structures were 

present on several islands, primarily the islands of Enjebi, Boken, Aomon, and Bijire. Much of 

the contamination that caused these structures to be classified as yellow debris was surface beta 

radiation (DNA, 1981). Several techniques such as sandblasting and chipping were used to clear 

away the surface contamination and leave the structures intact and in place (DNA, 1981). 

Covering a concrete vault on Enjebi with 6 inches of concrete was also used to render a 

contaminated concrete vault safe (DNA, 1981). However, the two concrete crypts located near 

the Yuma and Kickapoo GZs had some plutonium surface contamination and were broken up by 

explosive demolition and then disposed in the lagoon (DNA, 1981). The “Enjebi Hilton,” a 
72

multi-level building 52 ft wide, 196 ft long, and 36 ft high, had extensive beta contamination on 

the roof. This building was demolished by a wrecking ball and explosives after the contaminated 

portions had been chipped loose and transported to Runit for containment (DNA, 1981). 

Personnel who conducted sandblasting and chipping work may have been exposed to the dust 

generated by the abrasive engineering tools. Internal exposure from the inhalation of suspended 

contaminated dust generated by the engineering equipment was also possible. 

5.1.5. Lagoon Water and Sediment 

Water and sediments in the lagoon and to a lesser extent nearby ocean water were 

contaminated with fission products and TRU radionuclides as shown in Table 10 to Table 13. 

Lagoon water and sediments were potential sources of exposure to members of the Water Beach 

Cleanup Team (WBCT), the Underwater Demolition Team (UDT), and EOD personnel. In 

addition, ECUP personnel engaging in water-based recreational activities, such as swimming and 

sailing, were potentially exposed to these sources. The WBCT personnel could have been 

exposed to contaminated lagoon water and sediments as they worked at depths up to 

approximately 15 feet to retrieve debris by hand and winches attached to bulldozers or LCMs. 

They also participated in offshore cleanup of debris collected by boats and floating platforms 

(DNA, 1981). Members of the UDT were potentially exposed to these sources of exposure when 

they set charges to open or clear channels for boat navigation. 

Personnel water-based activities, such as boating conducted on the surface of lagoon 

water presented a potential for external exposure to radiation from gamma emitters from 

contaminants distributed in the water. Potential for significant internal exposure to alpha, beta, 

and gamma emitters by ingestion was possible only if personnel left the boat and came into 

contact with lagoon water. Divers and recreational swimmers also had the potential for skin 

exposure and whole body external exposures from immersion in the water. If individuals 

disturbed the sediment of the lagoon or ocean floor, the water activity concentration levels in the 

immediate vicinity could temporarily increase if the sediments contained radioactive 

contaminants. 

5.1.6. Other Sources 

Other potential sources of radiation exposure include contaminated equipment and PPE 

laundry, as described below. 

5.1.6.1 Contaminated Equipment 

Equipment considered worthy of retention was monitored for both fixed and removable 

contamination before being released for reuse in uncontrolled areas. Decontamination was 

performed if contamination was detected and levels exceeded the release limits set forth in 

Enclosure 1 of FCRR SOP 608-03.1, “Decontamination of Facilities and Equipment.” Personnel 

who surveyed equipment to evaluate whether or not it was contaminated, and those who actually 

performed decontamination, could have been exposed to external and internal radiation as a 

result of inhalation of resuspended contaminated soil and dust from the surface of the equipment. 

When contaminated equipment was found, dry removal procedures were in general 

attempted before wet procedures. In addition, wet techniques were selected only when the spread 

of contamination could be controlled (FCRR SOP 608-03.1). Procedures available at Enewetak 

to manage contaminated items included: 
73

 Brushing or scraping 

 Vacuuming 

 Filing and grinding 

 Damp wiping down 

 Ultrasonic cleaning, if applicable 

 Hosing down with available water and detergents 

 Steam cleaning 

 Sealing for fixation, e.g., painting 

 Disposing as contaminated debris. 

5.1.6.2 Decontamination Laundry Facility on Lojwa 

Personnel clothing decontamination was performed at the Decontamination Laundry 

Facility (DLF) on Lojwa. FRST contamination control areas or hot line operations personnel 

separated all items being sent to the DLF into three categories: (1) clothing, (2) plastic ware, e.g., 

gloves, boots, booties, etc., and (3) respiratory protection masks (respirators) (FCRR 

SOP 608-10) (FCRR, 1978b). Clothing found to have hot spots in excess of 2,000 dpm was 

disposed of as radioactive waste, rather than sent to the DLF (FCRR SOP 608-03.1)(FCRR, 

1977b). All contaminated items returned to Lojwa were double-bagged with each bag 

individually sealed by a knot or tape. FRST personnel made two copies of a list of all 

contaminated items describing: (1) the spot where activity was found on each item, (2) the 

typical readings and the type of probe used, (3) the date packaged, (4) the island location, and (5) 

the name of the FRST member filling out the list. A copy of this list was placed inside the outer 

bag (FCRR SOP 608-10) (FCRR, 1978b). 

The DLF was considered a radiologically controlled area. FRST had supervisory control 

for radiation safety and maintained, at a minimum, Access Rosters, Team Chief Reports, and Air 

Sampler Data Logs for the DLF. 

The DLF personnel who operated the facility could receive external radiation exposure 

and internal exposure as a result of inhalation of resuspended contaminated soil and dust from 

the personnel protective clothing and respirators. 

5.1.7. Drinking Water and Food 

When the Enewetak base camp was being prepared for the cleanup forces starting in June 

1974 and until the March 1980 demobilization, water distillation units installed on Enewetak and 

Lojwa Islands were used to provide potable drinking water to cleanup participants. Records show 

that ocean water was the source and distilled water was supplied throughout the cleanup project 

(1977–1980) for all drinking, cooking, bathing, and cleaning needs. (DNA, 1981) 

As discussed in Section 4.7.1, samples of produced water were collected in 1978 from 

Enewetak and Enjebi Islands and analyzed for Cs-137, Pu-239/240, and Pu-238. Trace levels of 

Cs-137 and plutonium isotopes in the samples were about 3–5 orders of magnitude below the 

current maximum contaminant levels for drinking water in the United States (USEPA, 2017b). 
74

The food consumed by cleanup participants was supplied by the food service using 

ingredients supplied through the military logistics system. As a result, prepared food and 

drinking water were not potential direct sources of exposure to radiation. Although the 

consumption of local terrestrial and marine food by cleanup personnel was plausible, the 

availability and access to such foods was limited. Very few coconut trees were growing at 

Enewetak Atoll. Other edible food such as pandanus, breadfruit, and arrowroot were even less 

available (DNA 1981). Some veterans may have caught and consumed lobsters or fish (Cherry, 

2018b). Other local foods may have included coconut crab and coconut milk and meat, as well as 

giant clams. However, given the scope of the cleanup project and potential contamination of 

local food, it is expected that in general, personnel refrained from eating such foods. In cases 

where local foods were consumed, the specifics of such consumption can be used to assess 

exposure on a case-by-case basis. Therefore, the potential consumption of local foods is included 

in the ECUP Questionnaire to participants and is assessed in Section 7.4 and Appendix M. 

Incidental ingestion of contaminated soil and dust through food and beverage 

consumption is considered a potential source of exposure to radiation for participants while on 

contaminated islands and is discussed in Section 7.2. In addition, an evaluation of potential 

exposure from the consumption of drinking water is discussed in Section 7.4.2. 

5.2 Exposure Pathways for Dose Assessment 

In general, an exposure pathway is the route followed by radiation or contaminants from 

a source via air, soil, water, or food to a human receptor. In the context of the ECUP and 

potential exposure to radiation, pathways involve exposure of the whole body to gamma 

radiation from external sources, exposure of internal organs and tissues to radiation emissions 

from internally deposited radioactive materials, and exposure of the skin to external sources of 

gamma and beta radiation. 

5.2.1. Exposure of the Whole Body to Radiation from External Sources 

Direct exposure to the radiation emitted by radioactive contamination is the primary 

pathway relevant to ECUP personnel. Sources of radiation that may have resulted in direct 

exposure to radiation of ECUP participants include: 

 Fallout mixed in the top layer of soil of contaminated islands 

 Stockpiles of contaminated soil and debris 

 Contaminated soils and debris, during transport by trucks and boats 

 Contaminated concrete slabs and building debris 

 Slurry of mixed contaminated soil and cement, during preparation, transport and disposal in 

the Cactus Crater 

 Soil-cement mix produced and contained in the Cactus dome 

 Lagoon and ocean waters, while retrieving debris and during recreational diving or 

swimming 

 Contaminated equipment and decontamination laundry. 
75

Direct exposure from contaminated ground surfaces was the most likely potential 

external radiation exposure pathway for ECUP participants. This exposure pathway applies to 

participants who were working or residing on islands with radiation levels above background, 

whether involved in cleanup activities or not. Direct exposure to soil that was excised, 

windrowed, stockpiled, and transported for ultimate containment in Cactus Crater on Runit 

represents a similar pathway for those individuals who were involved in soil cleanup activities. 

5.2.2. Exposure of the Skin to Radiation from External Sources 

Exposure of the skin to external sources of gamma and beta radiation could have 

occurred from the same sources listed for whole body exposure in the preceding subsection. In 

addition, exposure could have occurred if contaminated material was deposited directly on the 

skin or clothing. 

5.2.3. Exposure of Organs and Tissues to Radiation from Internal Sources 

Exposure of internal organs and tissues could have occurred from the intake and 

deposition of radioactive materials inside the body. Potentially contaminated media and routes of 

entry relevant to ECUP participants include: 

 Inhalation of soil suspended in air during brush removal and soil excision 

 Inhalation of airborne soil during loading, off-loading and uncovered transport on trucks, 

boats and barges 

 Inhalation of suspended soil during soil-cement mix operation in the Cactus dome 

 Inhalation of dust, e.g., from breaking down solidified slurry or from sandblasting during 

decontamination of concrete surfaces 

 Ingestion of food, including locally obtained food and water 

 Inadvertent ingestion of lagoon or ocean water while extracting offshore debris or swimming 

 Incidental ingestion of soil and dust 

 Absorption of material into the blood stream through open wounds. 

Suspension of contaminated soil during soil removal, handling, and transport was the 

most likely internal radiation exposure pathway for ECUP participants. This exposure pathway 

applies to participants who were working or residing on islands with radiation levels above the 

background level. 

5.3 Participant Activities and Potential Exposure to Radiation 

The ECUP POI can be considered to consist of groups of individuals with similar 

exposure scenarios. These groups are based on conducting similar project activities that involved 

the same or similar sources of radiation and potential exposure pathways. Each of the functional 

service organization and JTG units was assigned various responsibilities and tasks. Some of 

these tasks involved potential exposures to the radiation sources described above in Section 5.2. 

To evaluate the scenarios of exposure for ECUP personnel, specific activities within coherent 

project tasks were identified and categorized into the following top-level project components: 
76

 Soil cleanup 

 Debris cleanup 

 Radiological support 

 Southern islands (except Enewetak) 

 Project support on the residence island of Enewetak 

 Project support on the residence island of Lojwa 

 Intra-atoll transport 

 Pre-cleanup and demobilization 

 Recovery and disposal of unexploded ordnance by EOD teams. 

Within each of the top-level ECUP project component listed above, second-level tasks 

and third-level specific project activities were identified to best characterize personnel 

involvement in the cleanup effort and associated potential sources of radiation exposures. The 

tasks and activities related to each project component are discussed in subsequent subsections. 

Participants in some of the project teams conducted consistent and similar activities. 

However, members of other teams performed varying activities at different times and at different 

locations. For example, personnel in some of the general support units, such as the Finance Team 

and Airfield Team, conducted activities that were relatively consistent within the unit and were 

limited in both scope and location. The radiation dose assessment for participants in these types 

of units can be characterized by evaluating the scenarios of exposure for one of the two Project 

Support components for the residence islands of Enewetak or Lojwa; see list of project 

components above. 

Personnel in other units, such as the U.S. Army Engineer units and the FRST, were 

responsible for conducting a wide range of activities. These participants performed tasks at 

locations on multiple islands, and at different phases of the cleanup project. For these 

participants, a single unit-level radiation dose assessment cannot be performed. Rather, exposure 

scenarios associated with participation in project tasks on various islands or water transport 

vessels would be identified. These activity-based exposures to sources of radiation would 

constitute the basis for performing individualized dose assessment in response to future VA 

requests for dose information. 

Project personnel may have participated in multiple project components and tasks, and 

consequently, were the subject of distinct scenarios of exposure to radiation. In these cases, the 

scenarios of exposure should be assessed for an individual based on all activities performed 

under all project components. External and internal doses are estimated for all project component 

activities according to the methods discussed in Section 6 and Section 7. 

Project tasks within each project component and associated potential sources and 

pathways of radiation exposure are described in the following sub-sections. Participant groups 

that performed similar activities or operated in similar radiation environments are also identified. 
77

5.3.1. Soil Cleanup 

5.3.1.1 Tasks, Activities and Exposure Pathways 

The soil cleanup project component comprises five distinct tasks, each with several 

inherent activities. These activities were conducted primarily by personnel in the U.S. Army 

Element (Engineer units, LARC unit), U.S. Navy Element (Intra-atoll transportation teams, 

Harbor Clearance units, WBC teams), and DNA/JTG Element (Engineering team). Radiological 

support personnel were also involved in soil cleanup activities as discussed for the Radiological 

Support Project Component. Under the soil cleanup project component (Table 23), the following 

are the main tasks that personnel performed: 

 Brush removal 

 Soil removal (except Runit) and transport to Runit 

 Tremie disposal of contaminated soil slurry in the Cactus Crater 

 Runit soil cleanup 

 Direct disposal by soil-cement mixing into Cactus dome. 

Each of the above tasks involved specific activities that were potentially associated with 

exposure to radiation. Soil cleanup activities involved excision of soil contaminated with 

radioactive materials from five islands, transport of the soil to Runit Island, and disposal in the 

Cactus Crater and dome. The five islands are Boken, Enjebi, Lujor, Aomon, and Runit (DNA, 

1981). In addition, a small quantity, about 110 yd3, of soil contaminated with Co-60 was 

removed from a limited area on Medren and was disposed in the Cactus Crater. 

Activities under each task are listed with specific sources of exposure in Table 23. These 

activities generally took place over the period from mid-1978 to mid-1979. Brush removal 

activities, which generally preceded soil removal, are included in the soil cleanup project 

component. As shown in Table 23, external sources of exposure for this project component 

consist of direct exposure to soil surfaces, soil piles, and soil-cement mixtures. Sources of 

internal exposure pathways consist of inhalation of suspended soil or soil mixtures. In addition, 

exposure from incidental ingestion of contaminated soil and dust applies to all participants; this 

pathway is generic in nature and is applicable to all project components. Therefore, it is not 

specifically shown in Table 23. 
78

Table 23. Tasks, activities and sources of exposure – Soil Cleanup Project Component 

Tasks and 

Activities

Sources of External Exposure Sources of Internal Exposure

S

oil S

urfaces

S

oil Piles

Piles d

urin

g

B

ulk

Tra

nsport

S

oil-cement Mixture

Slurry

d

urin

g

P

u

m

pin

g

Rejected

Slurry

S

oil S

uspen

ded fro

m

S

urface d

urin

g

S

oil

Disturb

a

nce

S

oil S

uspen

ded

w

hile

Han

dling (e.g.,

loadin

g, u

nlo

a

din

g)

S

oil S

uspen

ded

d

urin

g

Tra

nsp

ort

S

oil-cement

S

uspen

ded

d

urin

g

Mixin

g or

S

preadin

g

Brush removal task

Uproot bushes and 

vegetation   

Burn uprooted 

vegetation 

Transport ashes to 

Runit 

Soil removal (except Runit) and transport to Runit task 

Remove and 

windrow   

Load soil on dump 

trucks  

Transport soil to 

stockpiles  

Load soil on LCMs 

or LCUs   

Transport to Runit  

Transport to 

stockpile  

Tremie disposal in Cactus Crater task

Load soil onto 

dump trucks  

Transport soil to 

batch plant  

Mix soil into slurry  

Transport slurry to 

pump 



Pump slurry 

through pipes 

Discharge slurry 

into trenches 

Place hardened, 

rejected slurry into 

crater 


79

Tasks and 

Activities

Sources of External Exposure Sources of Internal Exposure

S

oil S

urfaces

S

oil Piles

Piles d

urin

g

B

ulk

Tra

nsp

ort

S

oil-cement Mixture

Slurry

d

urin

g

P

u

m

pin

g

Rejected

Slurry

S

oil S

uspen

ded fro

m

S

urface d

urin

g

S

oil

Disturb

a

nce

S

oil S

uspen

ded

w

hile

H

a

n

dlin

g (e.g.,

lo

a

din

g, u

nlo

a

din

g)

S

oil S

uspen

ded

d

urin

g

Tra

nsp

ort

S

oil-cement

S

uspen

ded

d

urin

g

Mixin

g

or S

preadin

g

Runit soil removal and transport to Cactus dome task

Remove and 

windrow soil   

Load soil on dump 

trucks  

Transport soil to 

Cactus dome  

Place soil over FigQuince soil   

Direct disposal by soil-cement mixing into Cactus dome task

Load soil onto 

dump trucks  

Transport soil on 

trucks to crater  

Spread and mix soil 

with cement  

Construct key wall  

Construct 

containment cap    

5.3.1.2 Soil Cleanup – Potential Exposure Scenarios 

To characterize the type of activities performed by project personnel, several 

consolidated cleanup operations under the soil cleanup project component were identified. The 

following subsections describe these project operations and the type of personnel that were 

involved in conducting them. 

5.3.1.2.1 Soil Removal and Transport 

The scenario of exposure for individuals in this participant group includes activities 

involving disrupting and handling contaminated soil on four soil removal islands and Runit. 

Specifically, activities in this exposure scenario are those that may have resulted in suspension of 

contaminated soil during removal, transport, and disposal such as: 

 Uprooting, pushing/moving and windrowing vegetation 

 Excision, windrowing and piling contaminated soil 

 Loading and unloading bulk contaminated soil as follows: 
80

– At soil removal sites 

– At beach stockpiles 

– On and off boats 

– At boat ramp on Runit 

– At soil stockpiles on Runit 

– At batch plant on Runit 

 Transporting soil by trucks 

 Transporting soil by boats 

 Burning windrowed brush 

 Loading and unloading contaminated ash-soil mix from burned vegetation 

 Transporting contaminated ash-soil mix for disposal on Runit 

 Placing a 12-inch layer of relatively clean soil over the Fig-Quince area. 

Personnel involved in the above activities can be generally categorized in the following 

subgroups: 

 Operators of earthmoving machinery, e.g., bulldozers, backhoes, front loaders, bucket 

loaders, etc. 

 Truck drivers 

 Boat crew members 

 Batch plant personnel 

 Support personnel, such as surveyors, ground spotters and guides. 

Other groups of personnel, such as FRST members, were associated with soil removal 

and transport activities. However, their activities are described under the “Radiological Support” 

project component. 

5.3.1.2.2 Tremie Operations 

Personnel who were involved in tremie operations in the Cactus Crater on Runit 

performed activities that can be described as follows (DNA 1981): 

 Loading contaminated soil from stockpiles onto dump trucks 

 Driving dump trucks from contaminated soil stockpiles to concrete batch plant 

 Mixing contaminated soil with cement and water at the batch plant 

 Depositing tremie mix into transit-mix trucks at the batch plant 

 Driving transit-mix trucks from batch plant to concrete pump next to the crater 
81

 Pumping contaminated soil-cement slurry in tremie piping 

 Operating the tremie crane and barge on the crater water surface. 

In addition, as presented in Section 5.1.2, rejected slurry was handled by the “processed 

tremie” method. The activities involved in this method are described as follows: 

 Discharging rejected slurry from the transit-mix trucks into excavated trenches to let it 

harden 

 Breaking large hardened slurry blocks into smaller pieces 

 Loading hardened slurry chunks into dump trucks 

 Driving dump trucks and offloading the hardened slurry chunks into the crater. 

The groups of individuals listed below participated in the activities for tremie operations, 

which include the “processed tremie” method for rejected slurry: 

 Transit-mix truck drivers transporting slurry to crater rim 

 Operators of slurry disposal equipment, e.g., tremie pumps, barge, crane, etc. 

 Excavators of trenches for rejected slurry 

 Operators of equipment for preparation, transport and disposal of rejected, hardened slurry. 

Other groups of personnel may have been associated with tremie operations. However, 

their activities are described under separate project components. 

5.3.1.2.3 Soil-Cement Operations 

The remaining group of personnel that conducted activities under the Soil Cleanup 

component, that are not discussed under other project components, are those individuals who 

were involved in the soil-cement operations on Runit. The purpose of this operation was to 

construct the dome over the hardened slurry that filled the Cactus Crater. The following activities 

were conducted (DNA, 1981): 

 Loading, transporting and dumping contaminated soil at the crater containment site by truck 

 Spreading the soil in approximately 6-inch layers using a grader 

 Dumping bags of cement onto soil at the ratio of two bags per cubic yard of soil 

 Mixing dry cement with the soil using a disc harrow towed by a bulldozer 

 Watering down the dry mixture and compacting the wetted mixture with a vibratory roller 

compactor. 

Construction of the key wall and containment cap are also included in the soil-cement 

grouping of activities. Key wall construction did not involve handling contaminated soil but it 
82

was constructed at the perimeter of the dome at least partially during the period of soil-cement 

activities. Construction of the containment cap took place directly on top of the compacted soilcement mixture. Also, partial cap construction was started before all of the soil-cement activities 

were complete (DNA, 1981). 

Personnel conducting soil-cement, key wall and containment cap construction activities 

included the following: 

 Dump truck and water truck drivers 

 Operators of graders, bulldozers, and roller compactors 

 General construction engineers and personnel 

 Support personnel, such as surveyors, ground spotters and guides. 

5.3.2. Debris Cleanup 

5.3.2.1 Tasks, Activities and Sources of Exposure 

The Debris Cleanup Project Component comprised eight tasks shown in Table 24, each 

with a number of specific activities. These activities were conducted primarily by personnel in 

Army Engineer Units, Army LARCs and Amphibious Vehicle operations, Navy Harbor 

Clearance Units, EOD teams, WBC teams, and DNA/JTG Engineering (DNA, 1981). Personnel 

associated with the Radiological Support Project Component (see Section 5.3.3 below) were also 

involved in these debris cleanup activities. The following are the main tasks that personnel 

performed (see detailed activities and relevant sources of radiation exposure in Table 24): 

 Onshore debris removal and transport to beach stockpile area at islands other than Runit 

 Offshore debris removal and transport for islands other than Runit 

 Transport and disposal at lagoon dump sites of “yellow” debris from beach stockpiles loaded 

on trucks from islands other than Runit 

 Transport and lagoon disposal of bulk “yellow” debris from islands other than Runit 

 Transport and offloading of “red” debris to Runit stockpiles for islands other than Runit 

 Disposal of “red” debris from islands other than Runit in the Cactus Crater 

 Collection and disposal of Runit debris in donut hole in Cactus dome 

 Disposal of “red” debris collected during Cactus dome and antechamber dome extension 

constructions. 

Personnel removed, transported, and disposed of approximately 1,800 yd3 of 

contaminated debris from the islands of Enjebi, Lujor, Eleleron, and Aomon. Contaminated 

debris from these islands was disposed of at three designated sites in deep areas of the lagoon 

shown in Figure 4 or into the Cactus Crater and dome on Runit. In addition, about 4,000 yd3 of 

contaminated debris was collected onshore and offshore of Runit and disposed of in the Cactus 

dome and two antechamber extensions. Non-contaminated debris was removed from 34 islands 
83

with the largest quantities removed from Enewetak and Medren Islands (DNA, 1981). The soil of 

several of these islands had some level of contamination with radioactive materials. Table 6

(Section 4.2) provides island-by island mean soil activity concentrations. 

The lagoon was chosen for the disposal of debris that was radiologically classified as 

“yellow” or “green.” The Cactus Crater and dome were chosen for disposal of debris classified 

as “red.” Definitions for the radiological classifications are given in Section 3.2.2. All debris 

stockpiled on Runit, regardless of source, was moved locally for disposal in Cactus Crater and 

dome with heavy equipment, such as cranes with clamshells, front loaders, dump trucks and 

bulldozers. 

Each of the tasks listed above involved several activities that could have been associated 

with exposure to radiation while handling both contaminated and non-contaminated debris, such 

as inoperable equipment, abandoned vehicles, orphaned laboratory sources, and building 

materials containing source contamination. Activities under each task are listed along with 

potential sources of exposure in Table 24. The debris cleanup and disposal took place during 

three periods. From mid-1977 to May 1979, contaminated debris from the four islands listed 

above was collected and disposed of. All cleanups were completed by late 1978, except for 

Enjebi, which was completed in May 1979. Following the first phase and up to late 1979, debris 

on Runit was collected and disposed of in the Cactus dome. During this same timeframe, 

resurveys of the four islands indicated additional “red” debris removal was necessary. That 

debris was collected and transported to Runit for disposal during February to May 1979 (DNA, 

1981). 

As shown in Table 24, sources of external exposure to radiation for the debris cleanup 

project component consisted of direct exposure to contaminated debris during retrieval, 

stockpiling, transport, movements over contaminated ground, and disposal. Additionally, 

contaminated soil in the ground was a source of exposure applicable to personnel involved in the 

removal of non-contaminated debris from all the remaining soil-contaminated northern islands. 

Internal exposure pathways consisted of inhalation of suspended soil created by movement of 

debris and disposal activities in contaminated environments. In addition, exposure from 

incidental ingestion of contaminated soil and dust applies to all participants involved in debris 

cleanup who worked on contaminated islands. This pathway is common in nature and is 

applicable to all project components. Therefore, it is not specifically shown in Table 24, but it is 

discussed in Section 7.2. 

5.3.2.2 Debris Cleanup: Potential Exposure Scenarios 

The activities by personnel associated with the debris cleanup tasks listed in Table 24 are 

generally similar but differ with respect to the sources of the debris, timeframe of disposal 

actions, and the location of disposal sites. There were three phases of disposal activities on Runit. 

“Red” debris from the four islands other than Runit with contaminated debris was continuously 

being transported to Runit for disposal in the crater. Runit debris cleanup and disposal activities 

were postponed until cleanup of the other four islands was complete. The following subsections 

describe potential scenarios of exposure that are relevant to specific debris cleanup tasks and 

participant groups that performed them. 
84

Table 24. Tasks, activities and sources of exposure – Debris Cleanup Project Component 

Tasks and Activities

Sources of External Exposure Sources of 

Internal Exposure

Gro

u

n

d

S

urface

Debris o

n

Beach

a

n

d

U

n

derw

ater (S

m

all/L

arge)

Debris Piles d

urin

g

C

ollectio

n

a

n

d

Tra

nsp

ort

to

Beach

Areas (Y/R)

*

Piles o

n

Beach (Y/R)

Piles d

urin

g

Transp

ort b

y

B

o

at or B

arge (Y/R)

Debris Piles o

n

R

u

nit (R)

Debris Disp

osed in

Crater

a

n

d

D

o

n

ut (R)

S

oil S

uspen

ded fro

m

Gro

u

n

d

w

hile H

a

n

dlin

g

Debris (e.g., C

ollectin

g,

L

o

a

din

g, U

nloadin

g)

S

oil S

uspen

ded

d

urin

g

Tra

nsport to

a

n

d fro

m

Stock

piles

Onshore debris removal and transport to beach stockpile area at islands other than Runit 

Disassemble/break up 

oversized debris      

Remove debris by 

hand; move to piles    

Remove debris by 

engineering equip 

(bulldozers) 

    

Load debris on trucks 

with loaders and 

cranes

   

Transport debris by 

truck to beach 

stockpiles 

    

Offshore debris removal and transport for islands other than Runit 

Manually remove 

small debris    

Retrieve large u/w 

debris by divers using 

winches 

    

Transport offshore 

debris to stockpile or 

lagoon dump sites 

      

Transport and disposal at lagoon dump sites of “yellow” debris from beach stockpiles loaded on 

trucks from islands other than Runit 

Load trucks w/ beach 

stockpile debris w/ 

loaders and cranes 

    

Drive loaded trucks 

onto landing craft   

Transport “yellow” 

debris for lagoon 

disposal 

 

Offload yellow debris 

from trucks on boats 

by cranes on a barge 

 
85

Tasks and Activities

Sources of External Exposure Sources of 

Internal Exposure

Gro

u

n

d

S

urface

Debris o

n

Beach

a

n

d

U

n

derw

ater (S

m

all/L

arge)

Debris Piles d

urin

g

C

ollectio

n an

d

Tra

nsp

ort

to

Beach

Areas (Y/R)

*

Piles on

Beach (Y/R)

Piles d

urin

g

Tra

nsp

ort b

y

B

oat or

B

arge (Y/R)

Debris Piles o

n

R

u

nit (R)

Debris Disp

osed in

Crater

a

n

d

D

o

n

ut (R)

S

oil S

uspen

ded fro

m

Gro

u

n

d

w

hile H

a

n

dlin

g

Debris (e.g., C

ollectin

g,

L

oadin

g, U

nlo

a

din

g)

S

oil S

uspen

ded

d

urin

g

Tra

nsp

ort to 

a

n

d fro

m

Stoc

k

piles

Transport and disposal of bulk “yellow” debris from islands other than Runit 

Load bulk “yellow” 

debris onto landing 

craft 

  

Transport “yellow” 

debris for lagoon 

disposal 

 

Offload yellow debris 

with loaders/cranes at 

lagoon dump sites 

 

Transport and offloading of “red” debris for other than Runit 

Transport red debris 

to Runit collection 

point 

    

Offload red debris to 

Runit stockpile w 

loaders/cranes 

   

Cactus Crater disposal of “red” debris from islands other than Runit 

Dispose of debris in 

crater 

     

Dispose of bags of 

soil with Pu 

fragments 

    

Bulldoze oversized 

debris to edge of 

crater 

    

Runit debris collection and disposal in a donut hole in the Cactus dome 

Collect debris from 

South Runit (1977)      

Collect metal debris 

from reef near 

runway and 

Blackfoot areas 

     

Manually remove 

small debris from 

beach/underwater 

areas 

     
86

Tasks and Activities

Sources of External Exposure Sources of 

Internal Exposure

Gro

u

n

d

S

urface

Debris o

n

Beach

a

n

d

U

n

derw

ater (S

m

all/L

arge)

Debris Piles d

urin

g

C

ollectio

n an

d

Tra

nsp

ort

to

Beach

Areas (Y/R)

*

Piles on

Beach (Y/R)

Piles d

urin

g

Tra

nsp

ort b

y

B

oat or

B

arge (Y/R)

Debris Piles o

n

R

u

nit (R)

Debris Disp

osed in

Crater

a

n

d

D

o

n

ut (R)

S

oil S

uspen

ded fro

m

Gro

u

n

d

w

hile H

a

n

dlin

g

Debris (e.g., C

ollectin

g,

L

oadin

g, U

nlo

a

din

g)

S

oil S

uspen

ded

d

urin

g

Tra

nsp

ort to 

a

n

d fro

m

Stoc

k

piles

Retrieve large 

underwater by divers 

using winches 

     

Transport offshore 

debris to beach 

stockpile area 

    

Truck RUNIT debris 

beach stockpile to 

Donut Hole in dome 

     

Dispose debris in 

Donut Hole using a 

bulldozer 

   

Dispose of soil bags 

with Pu-contaminated 

fragments (FigQuince) 

    

Disposal of “red” Runit debris collected during Cactus dome and antechamber constructions 

Dispose debris from 

Lacrosse crater in 

depressions in Cactus 

mound surface 

    

Dispose metallic 

debris inside dome 

cap sections 

    

Construct two dome 

extensions after dome 

capping for “red” 

debris 

 

Choke “red” debris 

with clean concrete 

slurry 

  

*

 Debris classified as “yellow (Y) and red (R)” 
87

5.3.2.2.1 Debris Removal, Transport, and Disposal for Islands other than Runit 

The scenario of exposure for individuals who participated in debris removal, transport, 

and disposal involved handling of both contaminated and non-contaminated debris on over 

30 islands. Preparations for and actual transport and unloading at the disposal sites in this 

scenario resulted in external exposures. They resulted from directly handling debris, piles at a 

distance, ground shine from contaminated soil on the ground surface, and offshore debris 

collection. Specific activities associated with debris removal, transport, and disposal are: 

 Disassembling, breaking up, and removing debris 

 Retrieving large underwater debris by divers using winches 

 Transporting debris by truck to beach stockpile, lagoon dump sites or Runit 

 Loading trucks with loaders and cranes with clamshells and driving them onto landing craft 

 Transporting and offloading “yellow” debris for lagoon disposal by bulldozers, crane and 

clamshell 

 Transporting and offloading “red” debris to Runit collection areas by bulldozers, crane and 

clamshell 

 Transporting “red” debris from Runit collection areas and disposing in Cactus Crater and 

dome. 

Personnel involved in the above activities can be generally categorized into the following 

subgroups: 

 Heavy machinery operators, e.g., bulldozers, backhoes, front end loaders, bucket loaders, 

cranes with clamshells, and winches 

 Truck drivers 

 Boat crew members 

 EOD personnel 

 Divers. 

Other groups of personnel, such as brush removal teams, are not included under debris 

cleanup, but are discussed under the Soil Cleanup Project Component. 

5.3.2.2.2 Debris Collection and Disposal on Runit 

The scenario of exposure for individuals who participated in debris cleanup on Runit 

involved the collection and disposal of “red” debris brought in from four debris-removal islands 

other than Runit, or removed from South Runit, Blackfoot ground zero (GZ), Lacrosse crater, 

and within the Cactus Crater areas. The scenario also includes in-water debris collection as well 

as activities involving soil and debris being prepared for disposal and the actual disposal. 

Another scenario, unique to Runit, was the disposal of “red” debris consisting of plutonium 

embedded in rock-like materials, collected from Aomon and Runit. External exposures resulted 
88

from directly handling the debris, piles at a distance, and ground shine from contaminated soil on 

the ground surface. Specific activities associated with debris collection and disposal on Runit 

include: 

 Collecting and transporting offshore debris to beach stockpile area 

 Collecting and moving debris from South Runit, nearby reefs, old runway, and Blackfoot GZ 

areas 

 Manually removing and retrieving small and large underwater debris from beach and 

underwater areas and trucking and disposing debris in Donut Hole in Cactus dome 

 Disposing of debris in Cactus Crater 

 Disposing of bags of soil with plutonium fragments 

 Bulldozing oversized debris to edge of Cactus Crater 

 Disposing of metallic debris inside dome cap sections 

 Disposing of debris from Lacrosse crater in depressions in Cactus mound surface 

 Constructing two dome extension antechambers after dome became full 

 Choking “red” debris with clean concrete slurry in crater antechambers. 

Personnel involved in the above activities can be generally subdivided into the following 

groups: 

 Heavy machinery operators, e.g., bulldozers, backhoes, front-end loaders, bucket loaders, 

cranes with clamshells, and winches 

 Truck drivers 

 Boat crew members 

 EOD personnel 

 Divers 

 Surveyors and construction workers involved in the dome extension and capping. 

Other groups of personnel, such as brush removal teams, are not considered under debris 

cleanup, but are described under the Soil Cleanup Project Component in Section 5.3.1. 

5.3.3. Radiological Support 

5.3.3.1 Tasks, Activities and Sources of Exposure 

The Radiation Control Division (J-2) staff developed detailed procedures for specific 

operations that provided the workers what to do and how to do it in the field of radiation safety 

so that personnel exposures were kept as low as reasonably achievable (DNA 1981). The FRST, 

under J-2 staff (alternate RPO) supervision, oversaw on-site radiological safety and conducted 

field sampling of soil and debris. The Navy and Air Force also furnished technicians to work 
89

with the radiological support contractors, thus reducing the cost of radiological survey and 

laboratory operations (DNA 1981). In addition, the “Radiation Safety Audit and Inspection 

Team” (RSAIT) was chartered by the DNA Director to independently assess the radiological 

protection program. The team comprised members from each of the Services and 

ERDA/Department of Energy (DOE) (DNA 1981). The radiological support component includes 

the following five major tasks: 

 Provide operational radiological control 

 Perform radiological surveys and sample collection 

 Provide radiological laboratory support 

 Oversee radiation control at Army-operated decontamination laundry 

 Conduct radiation safety audit and inspections. 

The activities associated with each of the tasks above entailed possible exposures to 

radiation. The potential exposure pathways are identified in Table 25 for each of the activities. 

Table 25. Tasks, activities and sources of exposure 

– Radiological Support Project Component 

Task and 

Activities 

Sources of External Exposure Sources of Internal 

Exposure 

Gro

u

n

d

S

urface or

S

u

bsurface

S

oil Pile

Debris PileC

o

nta

min

ated

P

P

E

C

o

nta

min

ated

E

q

uip

ment

C

o

nta

min

ated

S

a

m

ples

C

heck so

urces for

C

alibratio

n

S

oil suspensio

n

w

hile S

u

pervisin

g

O

n site

S

oil Resuspensio

n

fro

m

P

P

E

S

oil Resuspensio

n

fro

m

E

q

uip

ment

Radiological control 

Operate hot line 

monitoring 

stations 

    

Collect and deliver 

contaminated PPE 

to laundry at 

Lojwa 



Decontaminate 

personnel and 

equipment 

  

Radiological surveys and sample collection 

Survey radiation 

levels and collect 

samples 

    

Take nasal swabs    
90

Task and 

Activities 

Sources of External Exposure Sources of Internal 

Exposure 

Gro

u

n

d

S

urface or

S

u

bsurface

S

oil Pile

Debris PileC

o

nta

min

ated

P

P

E

C

o

nta

min

ated

E

q

uip

ment

C

o

nta

min

ated

S

a

m

ples

C

heck so

urces for

C

alibratio

n

S

oil suspensio

n

w

hile S

u

pervising 

O

n site

S

oil Resuspensio

n

fro

m

P

P

E

S

oil Resuspensio

n

fro

m

E

q

uip

ment

Radiological laboratory support 

Decontaminate 

radiological 

instrumentation 



Calibrate 

radiological 

instrumentation 



Perform 

radiological 

sample analyses 



Army-operated decontamination laundry

Launder 

contaminated PPE  

Monitor washers 

and dryers for 

residual 

contamination 

 

Sample laundry 

effluents 

Radiation Safety Audit and Inspection

Evaluate 

radiological 

protection 

practices on-site 

   

5.3.3.2 Radiological Support: Potential Exposure Scenarios 

The following subsections describe potential scenarios of exposure that are relevant to 

radiological support tasks and participant groups who performed them. 

5.3.3.2.1 Radiological Control and Surveys 

The individuals in this potentially exposed group are FRST members who operated the 

atoll radiation protection program. Specific assignments included the following (DNA, 1981): 

 Controlling hot lines 

 Operating air samplers 

 Issuing, collecting, and reading supplementary personnel dosimetry devices 
91

 Performing radsafe procedures at each work site, e.g., soil and debris cleanup sites 

 Monitoring personnel, facilities, and equipment 

 Overseeing decontamination of personnel, facilities, and equipment as required. 

 Collecting and delivering contaminated PPE to laundry at Lojwa 

 Taking nasal swabs. 

Personnel involved in the above activities can be generally categorized into the following 

subgroups: 

 Health physicists 

 Health physics, radiological control, bioenvironmental engineering and safety technicians 

 Other military specialties as assigned. 

5.3.3.2.2 Radiological Laboratory Support 

The technicians provided by Navy and Air Force worked with contractors, such as 

Holmes & Narver Pacific Test Division to furnish radiological support. They conducted the 

following activities necessary to establish cleanup requirements, to evaluate the effectiveness of 

cleanup work, to maintain functional and accurate radiation probes, and to certify the results of 

radiological cleanup (DNA 1981): 

 Performing radiological sample analyses 

 Performing soil and debris surveys 

 Decontaminating radiological instrumentation 

 Calibrating radiological instrumentation. 

Personnel involved in the above activities can be generally categorized into the following 

subgroups: 

 Health physicists 

 Radio-analytical chemists 

 Radiation specialists 

 Health physics, radiation control or bioenvironmental engineering technicians 

 Precision measurement equipment laboratory (PMEL) technicians. 

5.3.3.2.3 Decontamination Laundry 

The Army Laundry Team from 613th Field Service Company began providing laundry 

service on June 17, 1977. They operated a general laundry at Enewetak Camp and a 
92

decontamination laundry at Lojwa Camp for cleaning washable personal protective equipment. 

The Lojwa laundry was operated under supervision of the FRST. The FCRR SOP 608-10, 

“Decontamination Laundry Procedures” (FCRR, 1978b), provided detailed guidance on the 

operation and monitoring of the facility (DNA, 1981). The Laundry team performed the 

following activities: 

 Laundering contaminated PPE 

 Monitoring washers and dryers for residual contamination 

 Sampling laundry effluents. 

Personnel involved in the above activities can be generally categorized into the following 

subgroups: 

 Laundry technicians 

 Health physics, radiological control, bioenvironmental engineering and safety technicians. 

5.3.3.2.4 Radiation Safety Audit and Inspection 

The RSAIT was given the broadest range of authority to scrutinize all aspects of the 

radsafe program. The RSAIT comprised a multi-disciplinary group of radiation safety, 

occupational safety and health, and medical specialties, many of whom were health physicists (or 

equivalent military specialty). The group was headed by the Director of AFRRI (Armed Forces 

Radiobiology Research Institute) (DNA 1981). 

The RSAIT visits were scheduled as frequently as would be useful; they started at 

quarterly intervals, but eventually were reduced to about three times per year. Their work 

involved the following (DNA, 1981): 

 Reviewing all procedures established for radiation, environmental, and occupational safety 

 Visiting the various islands and observing the practices actually in use to ensure that the 

procedures were appropriately performed. 

The RSAIT visited the atoll ten times during the cleanup. The duration of each visit 

depended on the time required for thorough inspection of actual working conditions at the site of 

each radsafe operation on the atoll. 

Personnel involved in the above activities can be generally categorized into the following 

subgroups: 

 Health physicists 

 Health physics, radiological control, bioenvironmental engineering and safety technicians 

 Medical specialists 

 Other military specialists as assigned. 
93

5.3.4. Southern Islands (except Enewetak) 

This project component contains three distinct tasks. Only one of the tasks involved 

exposure to radiation sources. The cleanup tasks performed in the southern islands other than 

Enewetak include the following: 

 Remove contaminated soil from Medren 

 Remove non-contaminated debris from southern islands 

 Retrieve unexploded ordnance by EOD teams. 

The first task above involved a small quantity of Co-60 contaminated soil from limited 

areas on Medren that was removed and contained in the Cactus Crater. Activities under the task 

are listed with specific potential exposure pathways in Table 26. These activities took place 

during February 7–10, 1978 (DNA 1981). As shown in Table 26, external exposure pathways for 

this project component consist of direct exposure to soil surfaces and soil piles. Internal exposure 

pathways consist of inhalation of suspended soil. In addition, exposure from incidental ingestion 

of contaminated soil and dust applies to all participants; this pathway is not shown in Table 26. 

Table 26. Tasks, activities and exposure pathways – Southern Islands Project Component 

Tasks and 

Activities

Sources of External Exposure Sources of Internal Exposure

S

oil S

urfaces

S

oil Piles

Piles d

uring 

B

ulk

Tra

nsp

ort

S

oil S

uspen

ded

fro

m

S

urface

d

urin

g

S

oil

DisturbanceS

oil S

uspen

ded

w

hile H

a

n

dlin

g

(e.g., L

o

a

din

g,

U

nlo

a

din

g)

S

oil S

uspen

ded

d

urin

g

Tra

nsp

ort

Soil removal from Medren and transport to Runit task 

Remove soil with 

backhoes  

Load soil on dump 

trucks  

Transport trucks by 

LCU to Runit  

Offload soil from 

trucks to stockpile   

Personnel involved in the above activities on Medren can be generally categorized into 

the following subgroups: 
94

 Operators of earth moving machinery, e.g., backhoes, front loaders 

 Truck drivers 

 Boat crew members 

 Support personnel, such as surveyors, ground spotters and guides. 

The participants conducting the second and the third tasks of this project component did 

not handle radioactive materials and were not near contaminated soil (DNA, 1981). These 

participants had no sources of exposure to radiation. Therefore, these tasks are not listed in 

Table 26. 

5.3.5. Project Support on Residence Islands – Enewetak 

Enewetak Island was the primary residence and support base for ECUP. The results of 

the Enewetak Radiological Survey indicated that Enewetak Island had levels of contamination 

comparable to or lower than those due to worldwide fallout in the United States (AEC, 1973a). 

The tasks listed below were conducted on Enewetak, to support the cleanup project: 

 Construct and maintain facilities and structures 

 Provide medical and dental care 

 Install and maintain telecommunication equipment and stations 

 Maintain petroleum, oil, and lubrication stores and resupply forward areas 

 Operate and maintain postal service 

 Operate food services 

 Provide welfare and recreation services 

 Operate airfield and offload/load cargo 

 Participate as crewmembers on supply ships or aircraft. 

Personnel involved in the above activities can be generally categorized into the following 

subgroups: 

 Civil engineers, construction workers 

 Medical doctors and dentists, nurses, medical assistants 

 Electrical engineers, communication electronics technicians, radiomen 

 Post servicemen 

 Chefs and cooks 

 Pilots, airmen, aircraft fuel technicians 

 Crewmen 

 Other military specialists as assigned. 
95

The participants conducting the tasks above on Enewetak Island did not handle 

radioactive materials and were not near contaminated soil and debris. Therefore, these personnel 

had no potential sources of exposure. 

5.3.6. Project Support on Residence Island – Lojwa 

Based on the data collected and analyzed, Lojwa Island was cleared from the controlled 

access island list on May 27, 1977 because it was found to be radiologically safe (CJTG, 1977a). 

Lojwa was then established as the location of a temporary base camp in the northern islands to 

support cleanup in that area and to reduce transportation time and requirements (DNA, 1981). 

The tasks performed on Lojwa to support the cleanup project are listed below: 

 Construct and maintain facilities and structures 

 Provide medical and dental care 

 Install and maintain telecommunication equipment and stations 

 Maintain petroleum, oil, and lubrication stores and resupply forward areas 

 Operate and maintain postal service 

 Operate food services 

 Provide welfare and recreation services. 

Personnel involved in the above activities can be generally categorized into the following 

subgroups: 

 Civil engineers, construction workers 

 Medical doctors and dentists, nurses, medical assistants 

 Electrical engineers, communication electronics technicians, radiomen 

 Post servicemen 

 Chefs and cooks 

 Other military specialists as assigned. 

The participants conducting the tasks above on Lojwa did not handle radioactive 

materials and were not near contaminated soil or debris that required cleanup. The island-average 

external exposure rate on Lojwa is shown in Table 4. 

5.3.7. Intra-Atoll Transport 

Transportation of people, equipment, supplies, and materials from island to island during 

the ECUP project depended heavily on boat transportation. In addition, air transportation by 

helicopter supported the primary missions of MEDEVAC and Search and Rescue (SAR), as well 

as other support on an as-needed basis. 
96

Intra-atoll boat transportation was assigned to the Navy, primarily its Boat Transportation 

Team, with one exception. The Army provided amphibious lighters (Lighter Amphibious 

Resupply, Cargo LARCs), which were able to cross several hundred yards of the shallow reefs 

that surrounded many of the islands and prevented access by Navy landing craft. 

The following activities were performed by intra-atoll air transportation personnel: 

 Transport personnel and materials during MEDEVAC and SAR missions 

 Transport personnel and equipment during command, control, and logistical missions 

 Transport ERDA personnel and equipment during gross radiological surveys of islands. 

Personnel who performed intra-atoll transportation can be categorized into the following 

subgroups: 

 Boat crewmembers including Boatswain's Mates, Enginemen, Hull Technicians, Electrician 

Mates, and other Navy specialties 

 Army heavy equipment operators 

 Army aviation personnel including pilots, flight engineers, and other aircrew. 

Intra-atoll transportation personnel were expected to perform their functions 6 days per 

week, 10 hours per day, but may have exceeded those levels to accomplish their missions. 

The service members who performed the first three tasks listed for boat transportation 

and all tasks for air transportation above did not handle radioactive materials directly and were 

not near contaminated soil or debris. Therefore, there are no sources of potential exposure for 

these individuals. During transportation of contaminated soil or debris, service members in this 

project component did not handle radioactive materials directly, but were present near the 

contaminated soil or debris, usually at a distance and not in direct contact. Nevertheless, service 

members performing the latter two activities are included in the Soil Cleanup or Debris Cleanup 

project components. 

5.3.8. Pre-cleanup Mobilization and Demobilization 

The ECUP effort was characterized by major cleanup functions represented by soil 

cleanup, debris cleanup, and radiological safety that involved possible radiation exposures. In 

addition, other major efforts removed and disposed of uncontaminated materials in order to 

prepare the atoll for resettlement of the Enewetak people. These activities starting in the summer 

of 1977 and extending into the fall of 1979 account for most of the total project timeframe. 

The success of ECUP operations depended on effective planning and preliminary 

preparation efforts during a mobilization period and on similarly effective ramp-down efforts to 

finalize the departure of project military service members and units, DOE, and contractor 

personnel during a demobilization period from March 26, 1979 until May 13, 1980. Mobilization 

and demobilization activities overlapped with cleanup activities in some cases. Activities during 

both phases could have involved radiation sources on islands before and after cleanup. 
97

5.3.8.1 Mobilization 

The activities during mobilization that may need evaluation to assess radiation exposure 

include: 

 A visit by a Navy survey team, assisted by FCDNA, to thoroughly investigate Enewetak 

Atoll water and beaches from November 30 through December 15, 1976 for harbor 

clearance, beach access, and traffic ability 

 A December, 1976 visit to the atoll by Pacific Air Forces Surgeon’s Office in preparation for 

establishing a Medical Clinic at Enewetak Camp and a Medical Aid Station at Lojwa Camp 

 An OPLAN development conference at Enewetak Atoll during February 21 through 

March 9, 1977 

 The installation of radio communications equipment by an Air Force installation team 

starting on March 16, 1977 

 The arrival of an initial party of the CJTG’s staff including the Logistics Officer, an Engineer 

Construction NCO and radiation safety officer on April 5, 1977, presumably on Enewetak 

Island 

 A joint Army-Navy effort of the project from April 8 to May 9, 1977 to remove aggregate 

from a stockpile on Enjebi (Janet) Island to Lojwa (Ursula) Island to make concrete for use in 

constructing the forward base camp 

 The arrival on May 3, 1977 of six enlisted Navy personnel to receive and put into service the 

first increment of landing craft 

 Arrival of an advance party of the Commander, JTG, base construction forces and support 

teams on May 17, 1977 

 Site preparation, surveying, and construction of concrete slabs for buildings on Lojwa 

starting May 17, 1977 by Army engineering troops billeting temporarily in tents there 

 Arrival of the first contingent of the FRST on June 28, 1977 

 Construction of facilities on South Runit under personnel protection requirements until 

July 15, 1977 

 Arrival of a detachment of the Underwater Demolition Team Eleven on September 13, 1977 

to begin channel clearance and underwater demolition work at islands throughout the atoll 

requiring access by boats 

 Arrival and setup of the Navy Water-Beach Cleanup Team on October 15, 1977. 

These listed activities were performed primarily on uncontrolled islands such as 

Enewetak and Lojwa. It seems reasonable to conclude that any doses received during these 

activities would be less than similar activities on the same islands for full, six-month durations. 

A few exceptions to the above include aggregate handling on Enjebi to establish a 

stockpile on Runit, and construction activities on south Runit, which both involved somewhat 
98

elevated concentrations of radioactive contaminants. In these cases, dose assessments that 

consider the specific circumstances of the exposures would be a reasonable approach. 

5.3.8.2 Demobilization 

Demobilization primarily involved logistics oriented activities, i.e., razing base camp 

facilities; disposing of excess materiel; and shipping personnel, equipment, and supplies to other 

locations. Most of the effort involved uncontaminated equipment, debris, and other items. These 

activities started well before cleanup was completed. The first demobilization event involved the 

retrograde of equipment by ship in March 1979. Stringent procedures were followed to assure 

that only items that met established radiation clearance limits left the atoll. During the entire 

process, only one piece of equipment was found to be contaminated. Although below release 

limits, it was sent from Enewetak Island to Runit for decontamination. (DNA, 1981) 

Contaminated equipment was handled through a separate process whereby all equipment 

that had ever been on a controlled island was moved through Runit for assessment. A primary 

concern of radiological control was to assure that contaminated equipment was not removed 

from a radiologically controlled island to an uncontrolled island within the atoll. Before 

equipment was removed from a controlled island, it was monitored by the FRST and, if 

necessary, decontaminated before being released. (DNA, 1981) 

These monitoring and decontamination efforts were accomplished on Runit by members 

of the FRST assisted by members of the equipment user organizations. FRST members 

performed the monitoring tasks, advised, and assisted in decontamination, and performed 

reassessment and certification that equipment met release limits. 

With respect to radiation exposure assessment, the radiological control activities during 

demobilization were essentially the same as the FRST duties during soil and debris cleanup. 

Assessment of doses was included in the Radiological Support Project Component. Personnel 

monitoring with film and TLD badges continued throughout the demobilization phase. 

Exposures to support group members during demobilization were similar to their 

activities during soil and debris cleanup, including truck and equipment driving, maintenance, 

etc. Therefore, exposures for these individuals are included in the Soil Cleanup and Debris 

Cleanup Project Components. 

5.3.9. Unexploded Munitions Recovery and Disposal 

Unexploded munitions existed on land, and in water areas adjacent to islands, reefs and 

other landmasses of Enewetak Atoll. When the presence of these objects caused safety concerns 

for cleanup personnel, EOD personnel were employed to locate, identify, recover and dispose of 

the items. 

Early in the mobilization phase, EOD specialists assigned to the FRST were primarily 

responsible for recovery and disposal of all unexploded munitions found on land. By early 

October 1977, FRST EOD personnel had collected over 300 rounds of munitions on the 

southwest beach of Enjebi (Janet). These were destroyed by multiple detonations in midOctober. Later in the cleanup, the FRST EOD specialists were released and the U.S. Navy EOD 

Detachment assumed the entire EOD function (DNA, 1981). 
99

The Navy EOD Detachment worked to deal with unexploded munitions in offshore areas, 

primarily around the island of Medren. As for the munitions found on land, the munitions were 

either collected for disposal later, or detonated in place if considered dangerous. 

It can be reasonably concluded that since the munitions were remnants of earlier combat 

actions, they were not contaminated with radioactivity and presented no exposure potential. In 

some cases, particularly when EOD specialists may have accompanied FRST personnel into 

controlled areas, an exposure potential may have existed. For these situations, dose assessments 

for EOD personnel would be similar to those of the FRST personnel they accompanied.
100

Section 6. 

External Radiation Dose Assessment Methods 

The ECUP personnel were exposed to radiation from external sources while evaluating 

radiological conditions on the islands, cleaning up and disposing of contaminated soil and debris 

and performing other ancillary and support activities. Estimates of radiation doses resulting from 

external sources follow the principles of DTRA’s dose reconstruction methods for the NTPR 

Program (DTRA, 2017). 

This section discusses the use of personnel dosimetry records consisting of film badge 

and TLD readings for estimating external doses to ECUP personnel. Discussions are included on 

the application of dose reconstruction methods using results from radiation survey data presented 

in Section 4 when dosimetry records are not usable or available. The dose reconstruction 

methods that would be used for ECUP veterans’ assessments are discussed in Section 6.2. 

The methods discussed provide estimates of dose to the whole body and internal organs 

primarily from gamma-ray radiation. The possible exposure of the skin to beta-particle radiation 

is not normally measured with whole-body dosimeters. Consequently, methods developed for 

skin dose assessments are discussed in Section 6.3 and can be used to estimate skin doses. 

Finally, all doses either from recorded dosimetry or from dose reconstruction estimates 

have associated uncertainties that must be taken into account for a complete report of the doses 

for ECUP personnel. Section 6.4 discusses methods for estimating and reporting dose 

uncertainties and upper-bound doses. 

6.1 Dosimetry Records 

6.1.1. Sources of Dose Records 

The availability, completeness, and considerations for using the dosimetry records are 

discussed in terms of the sources and difficulties with some of the results, such as those from 

damaged film badges. The following five sources of dosimetry records have been identified 

during research for this project: 

 DD Form 1141 “Record of Occupational Exposure to Ionizing Radiation” 

 ADC (formerly called LBDA) database 

 Department of Army (DA) Form 3484 “Photodosimetry Report” 

 Thermoluminescent Dosimetry Report 

 TLD Control Card. 

6.1.2. DD Form 1141 

DD Form 1141 is the official document used by the Military Services to record radiation 

doses to personnel engaged in radiation work. These forms were prepared by FCDNA Enewetak 
101

and sent to the dosimetry center of the individual’s Military Service. Although this policy was in 

effect during ECUP operations (DNA, 1981), not all Centers received these records, recorded the 

results, or preserved the ECUP-specific DD Forms 1141. 

A sample DD Form 1141 is shown in Figure 7, with the following information: 

 Blocks 1 through 5 at the top of the form contain the individual’s personal identification 

information. 

 Columns 6 through 12 contain dose data. 

The “from” and “to” entries, columns 7 and 8, capture the period of exposure for the 

corresponding dose entry in column 12. In column 6, entries without an asterisk are considered 

as resulting from valid film badge doses, i.e., from undamaged film badge. Entries in column 6 

with one asterisk denote the corresponding entry in column 12 is an administratively assigned 

dose. Entries with two asterisks in column 6 denote the corresponding entry in column 12 is a 

TLD dose. 

6.1.3. ECUP Dosimetry Data 

The ECUP personnel dose records have been maintained in the ADC database. External 

doses for cleanup personnel are accounted for by three sources of information in the database: 

film badge dosimetry, TLD dosimetry, and administratively assigned doses. 

FCDNA implemented the use of TLDs in tandem with film badges starting in May 1978 

(DNA, 1981) with full implementation in Mar 1979 (RSAIT, 1979a). The TLDs were a means of 

overcoming environmental problems that caused damage to film badges because TLDs were 

sealed and protected from the environment. Thus, TLD dose data are considered a valid source 

for dose records. 

DA Form 3484, provided by LBDA to FCDNA, contained a record of the film badge 

processing data by batch for all film badges turned in to LBDA from ECUP operations. That 

form was provided as a record to FCDNA indicating the disposition of the dosimeters, i.e., valid 

or damaged. Doses were assigned based on the readings of valid dosimeters. Administrative 

doses were assigned when film badges were damaged. The form served as a worksheet for 

populating dose data in the LBDA (now ADC) database. 

Other forms such as the TLD Reports and TLD Control Cards, both filled out on a 

recurring basis, provided a local record of TLD dose data. The TLDs were read out on site at the 

Enewetak Operation by radiological control technicians. These forms provided a means for 

transmitting TLD data to LBDA to include in its database. 

6.1.4. Administrative Doses 

Administrative doses were assigned using procedures developed by FCDNA to replace 

damaged film badge results (FCDNA, 1978). Amended DD Forms 1141 were prepared for these 

individuals to record these administratively estimated doses. The administrative doses are highsided estimates of ECUP worker doses. For this reason, the recommendation is to use 

reconstructed doses in place of administrative doses. Further discussion about external dose 

estimation methods is included in Section 6.2. 
102

Figure 7. Example of partial DD Form 1141, with personally identifiable 

information redacted 
103

6.2 External Dose Estimation Methods 

To augment personal dosimetry measurements, radiation doses for exposures from 

external sources can be estimated using dose reconstruction methods developed by DoD dose 

assessment programs, such as DTRA’s NTPR Program (DTRA, 2017). This is necessary 

sometimes to supplement incomplete, lost, or unreliable dosimetry records. The methods 

employed in dose assessments include the use of high-sided estimates of parameter values in the 

calculation of doses to personnel for all applicable exposure pathways. Sources and pathways of 

exposure to radiation for ECUP participants are described in Section 5. When necessary, external 

doses from exposure to contaminated soil, contaminated debris, or other contaminated material, 

e.g., equipment or laundry, are estimated based on the measured or estimated exposure rates and 

the type and duration of each activity. Estimated external doses are combined with an uncertainty 

factor to estimate upper-bound doses that are expected to exceed the 95th percentile dose if 

determined from a distribution of doses of individuals exposed to the same or similar sources and 

levels of radiation and monitored with personal dosimeters. 

This section describes the assumptions and parameter values that are used to estimate 

doses from exposure to radiation external to the body. The equations used for the external dose 

estimation are presented in Appendix C. Exposure scenarios and results of example radiation 

dose calculations for ECUP personnel are presented and discussed in Section 8. For veteran 

claims, dose estimates prepared in response to VA requests should consider all sources of 

radiation and pathways that are applicable to the individual. Finally, a veteran radiation dose 

assessment should be performed following the recommended guidelines discussed in Section 9. 

6.2.1. Soil Cleanup 

The most common potential external radiation exposure source for ECUP participants 

was undisturbed contaminated soil, for which island-specific exposure rates have been 

determined and were used to estimate the island-average exposure rates shown in Table 4. These 

island-specific exposure rates are based on measurements made during the 1972 radiological 

survey (AEC, 1973a), and the island-average values are used as conservative estimates for the 

ECUP radiation dose assessments for exposures during the cleanup project period of 1977–1980. 

The 1972 exposure rates are considered overestimates of the actual average exposure rates that 

prevailed during ECUP because they were not adjusted to reflect radioactive decay or weathering 

of the radioactive soil contaminants from 1972 to 1977. Furthermore, they are considered 

overestimates for dose calculations because they are assumed constant values that did not 

decrease as cleanup of contaminated soil and debris progressed throughout the duration of the 

project. 

Direct measurements have not been located for exposures to excised soil in other 

configurations, such as in piles, during transport, and when mixed in slurry or cement. For these 

situations, the island-average exposure rates can be used to estimate external exposure rates for 

individuals. For example, the exposure rate from a pile of soil, e.g., as stockpiled on a beach or 

as bulk-hauled in a truck or boat, can be estimated using the undisturbed soil/ground exposure 

rate together with a distance modifier such as the ratio of measurement distance to receptor 

distance from the source. Exposure rates for contaminated soil in mixtures, e.g., mixed with 

cement, can be bounded by using the undisturbed soil/ground exposure rates. These should be 

conservative estimates because of 1) the finite and small sizes of slurry pipes, transit-mix trucks, 
104

and dome sections as compared to the infinite plane geometry of the surveyed islands, and 2) the 

dilution of the soil with cement, attapulgite, and water. 

External doses and upper-bound doses for ECUP participants who were involved in soil 

cleanup or other on-shore activities are estimated using the equations presented in 

Appendix C-1. Parameter values and assumptions for estimating external doses for these 

exposure scenarios are shown in Table 27 to Table 29, and brief discussions of these parameters 

and assumptions follow. 

 Island-average exposure rate: The island-average exposure rates shown in Table 4, which 

are based on the 1972 radiological survey, are used as default values for scenarios involving 

exposures to contaminated soil for a veteran who performed activities on specified islands as 

reported on Controlled Island Access Logs or other references. 

In some exposure scenarios, the veteran may have conducted work on multiple 

islands. In these scenarios, averages of the individual island-average exposure rates may be 

appropriate to use to estimate external doses. For example, a simple average of exposure 

rates for all northern islands for cases where a veteran spent time on several of the northern 

islands, but the islands are not known. In other scenarios, such as soil removal work on 

several known islands, a weighted average of the relevant island exposure rates can be used, 

weighted by the time spent on each island, if known, or by the fraction of the total volume of 

soil removed from each island. The rationale for weighting the individual exposure rates by 

volume of soil removed is based on the assumption that the amount of soil removed is 

proportional to the amount of time a worker involved in soil removal activities would have 

spent on each island. This is the approach used in the example scenario described in Section 

8.2.1. Guidance on averaging methods for estimating external exposure rates for scenarios 

involving work on multiple islands is shown in Table 28 for four categories of worker 

participation. 
105

Table 27. Parameter values and assumptions for estimating external doses from 

contaminated soil 

Parameter Value Rationale/Reference/Comment

External exposure 

rate 

Island-specific or 

multi-island average 

The 1972 island-average 

exposure rates shown in Table 4

are conservatively used for 1977-

1980. See Table 28 for guidance 

on averaging when multiple 

islands are involved. 

Duration of duty tour Variable 

(default = 6 months [26 wk]) 

Based on individual’s arrival and 

departure records, if available 

Work schedule 10 h d−1 for 6 d wk−1 This is the default assumption for 

all participants (DNA, 1981). 

Time spent outdoors 

and indoors on 

residence island 

See Table 29

Protection factor Tent: 1.5 

Building: 2.0 (DTRA, 2017, SM ED02) 

Film badge 

conversion factor 

(for 3 orientations 

relative to a source) 

Facing source: 1.0 rem R−1

Standing upright: 0.7 rem R−1

Facing away: 0.5 rem R−1

(DTRA, 2017, SM ED02) 

Fraction of time 

exposed to source 

0.1 to 1 

(default = 1) 

Fraction of a workday or of work 

duration that a worker is exposed 

to a source 
106

Table 28. Averaging methods to determine exposure rates or soil activity concentrations 

for scenarios where ECUP veterans worked on multiple islands 

Type of Work

If work islands are known

If work islands are 

not known Durations on specific 

islands are known 

Durations on specific 

islands are not 

known 

Work involving or 

supporting soilremoval activities*

TWA† using values 

for known soilremoval islands 

VWA‡ using values 

for known soilremoval islands 

VWA using values for 

all soil-removal 

islands 

General work only 

on northern 

islands§,**

TWA using values for 

known northern 

islands 

SA†† using values for 

known northern 

islands 

SA using values for all 

northern islands 

General work only 

on southern 

islands§,**

TWA using values for 

known southern 

islands 

SA using values for 

known southern 

islands 

SA using values for all 

southern islands 

General work on 

northern and 

southern islands 

TWA using values for 

known northern and 

southern islands 

SA using values for 

known northern and 

southern islands 

SA using values for all 

northern islands‡‡

*

 Soil-removal islands and the volume of soil removed from each of the five soil-removal islands are shown in 

Table 37. 

† TWA = Time-weighted average of values, e.g., exposure rates or soil activity concentrations. Time-weighted 

averages are based on the amount of time spent on each island. 

‡ VWA = Volume-weighted average of values, e.g., exposure rates or soil activity concentrations. Volumeweighted averages are based on the volume of soil or debris removed from each island. 

§

 Northern and southern islands are identified in Table 1. 

** “General work” can be any work other than participation in direct soil-removal or debris-removal work, such as 

sampling, monitoring, and surveying. 

†† SA = Simple average (arithmetic mean) of values. 

‡‡ Using SA for all northern islands for this scenario will likely result in a high-sided average exposure rate or soil 

activity concentration. 
107

Table 29. Time spent outdoors and indoors on residence islands 

Work Location, Day of 

Week, and Worker 

Category

Daily Duration (h d−1)

Rationale/Reference/Comment Outdoor Indoor*

Enewetak and Lojwa Support Workers†

Workdays (6 d wk−1): 

Outdoor Workers 15 9 

Outdoor time is working and 

recreation; indoor time is sleeping 

and eating 

Indoor Workers 5 19 Outdoor time is recreation; indoor 

time is sleeping, eating, and working 

Non-Workdays (1 d wk−1): 

Outdoor and Indoor 

Workers 15 9 Outdoor time is recreation; indoor time is sleeping and eating 

Northern Island Workers (Lojwa Island)‡ 

and Southern Island Workers (Enewetak Island)§

Workdays (6 d wk−1) 5 9 Outdoor time is recreation; indoor 

time is sleeping and eating 

Non-Workdays (1 d wk−1) 15 9 Outdoor time is recreation; indoor 

time is sleeping and eating 

*

 On all days, sleeping and eating are assumed to take 8 h and 1 h, respectively. 

†

 Participants normally assigned to work locations on Enewetak Island or Lojwa Island with billeting on the same 

island. 

‡

 Northern-Island Workers are those participants who were billeted on Lojwa Island but were normally assigned 

to work locations on other northern islands. These workers may have also occasionally conducted work on Lojwa 

Island. 

§

 Southern Island Workers are those participants who were billeted on Enewetak Island but were normally 

assigned to work locations on other southern islands. These workers may have also occasionally conducted work 

on Enewetak Island. 

 Duration of duty tour: Enewetak Atoll arrival and departure cards, FCDNA Forms 288 and 

289, respectively, are available for individuals who visited or worked at Enewetak Atoll 

during the cleanup project. The dates on these cards determine the value for this parameter. If 

these cards are not located, and reliable dates are not available elsewhere, the default duration 

of duty can be assumed to be 6 months based on the typical ECUP assignment of 4–6 months 

(DNA, 1981). 

 Work schedule: The default work schedule for all participants is 10 h d−1, 6 d wk−1, and 

ECUP workers typically did not work on Sundays (DNA, 1981). For northern island workers, 

it is assumed that the 10 h d−1 work schedule includes an average travel time of 1 hour each 

way between Lojwa and the work site. This is a reasonable average value based on transit 
108

times derived from LCU boat logs and FRST Operational Reports10, which included transit 

times between Lojwa and Enjebi, and Lojwa and Runit. 

 Time spent indoors on a residence island: For all participants, the default daily schedule is 

8 h d−1 of sleeping and 1 h d−1 eating meals, which are assumed spent indoors on one of the 

residence islands. In addition to the daily 9 h d−1 for sleeping and eating, an additional 

10 h d−1 is assumed spent indoors on workdays if a participant’s normal work location was 

indoors on a residence island. 

 Time spent outdoors on a residence island: All non-work time other than sleeping and 

eating is assumed recreational time spent outdoors on the residence island. For all 

participants, this amounts to 5 h d−1 on workdays and 15 h d−1 on non-workdays. This is a 

high-siding assumption because less time would be spent outdoors if, for example, some 

recreation was spent indoors, or if additional time was spent sleeping or resting indoors on 

non-workdays. If a participant’s normal work location was indoors on the residence island or 

on a northern island, the only outdoor time on the residence island is assumed daily 

recreational time of 5 h d−1. In addition to 5 h d−1 spent outdoors for daily recreation by all 

participants, an additional 10 h d−1 is assumed spent outdoors on the residence island on 

workdays for participants whose normal work location was outdoors on the residence island. 

 Protection factor: This parameter accounts for the degree of protection from radiation 

afforded by the walls and floor of a tent or building where an individual was located while 

indoors. The value used is dependent upon the type of structure where most of a participant’s 

indoor time was spent. 

 Film badge conversion factor: The film badge conversion factor is the ratio of dose 

recorded on a properly worn film badge to free-in-air integrated exposure, and is used to 

convert an exposure to a dose. The factor accounts for body shielding of the film badge to 

gamma radiation, and is assigned the values of 0.7 for the standing position on a planar 

surface, 1.0 for facing the source of radiation, and 0.5 for facing away from a source (DTRA, 

2017, SM ED02). 

 Fraction of time exposed to source: This factor is intended to account for the fraction of 

time that an ECUP worker is actually exposed to a specific external source of radiation. 

Examples of scenario characteristics that could be accounted for include fraction of a 

workday that an individual is on a specific island, or is near a specific distinct source (e.g., 

debris piles). Because of the difficulty in determining an appropriate value, and to simplify 

veteran dose assessments, the recommended default value for this parameter is 1.0. 

6.2.2. Debris Cleanup 

Contaminated debris measurements made just before and during the cleanup project were 

not located in project documents or other sources. However, exposure rate measurements of 

contaminated debris were made during the 1972 radiological survey conducted by AEC (AEC, 

1973a). These measurements were conducted in support of the engineering study of the cleanup 

 

10 FRST Operational Reports are the daily reports prepared by a FRST Team Chief on JTG Form 16 for a specific 

Controlled Access Area. The forms contain serial numbers of survey meters used, and a Narrative section that may 

contain times, activities conducted, use of PPE, and other items relevant to radiological control. 
109

project developed for DNA (H&N, 1973). These debris exposure rate data were compiled from 

AEC (1973a) and are reported in Appendix K. 

The available debris exposure rate measurements are not directly applicable to veteran 

dose assessments. This is primarily because they are contact measurements that are not 

representative of exposure rates at distances from the debris items or piles at which personnel 

were typically located. In addition, the measurements were made on individual pieces of debris, 

whereas personnel who were involved in debris-handling activities would likely have been 

tasked with removing, transporting, and disposing of debris items and piles with a large range of 

radioactivity and sizes. Therefore, actual debris exposure environments are difficult to 

characterize for estimating doses. 

As described in Section 4.3, contaminated debris was removed from five northern 

islands: Enjebi, Runit, Lujor, Eleleron, and Aomon. The island-average exposure rates on these 

islands, which would have included contributions from the contaminated debris on each island, 

are recommended for use in dose assessments for contaminated debris cleanup activities. This 

recommendation is supported by an analysis of the 1972 debris survey data that showed that for 

each of the five islands of interest, island-average exposure rates are much larger than the 

respective mean exposure rates at average handling distances from the debris. A summary of the 

results of this analysis is shown in Table 30, which contains a comparison of the estimated mean 

exposure rates from debris in debris-cleanup scenarios with the respective island-average 

exposure rates. Additional details of the analysis are included in Appendix K. 

Table 30. Comparison of mean contaminated debris exposure rates 

and island-average exposure rates 

Island with Contaminated 

Debris 

Mean Contaminated Debris 

Exposure Rate at 10 ft* 

(μR h−1) 

Island-Average 

Exposure Rate 

(μR h−1)

† Island Name Site Name 

Enjebi Janet 1.3 40 

Runit Yvonne 1.4 33 

Lujor Pearl 7.1 70 

Eleleron Ruby 0.93 14 

Aomon Sally 1.7 7 

*

 Exposure rates are estimated for a 10-ft diameter disk source assuming contact measurements are taken at an 

average distance of 0.5 ft. In addition, operators of contaminated debris-handling equipment were typically 

positioned an average of 10 ft away from debris piles, see Appendix K. 

†

 See Table 4. 

The comparison in Table 30 shows that the island-average exposure rates are 

considerably higher than the mean contaminated debris exposure rates for all five islands at a 

representative exposure distance of 10 ft. Thus, island-average exposure rates are adequate to be 

used as the basis for estimating veterans’ external doses in general debris-cleanup scenarios. 

However, there were several debris sites on the five islands with debris exhibiting relatively high 

contact exposure rates that could possibly expose individuals to radiation levels higher than the 
110

corresponding island-average exposure rates. For these sites, an external dose can be calculated 

using the debris contact exposure rate adjusted for the individual’s distance from the specified 

debris and duration of exposure stated by the veteran. This external dose would be based on a 

single or combination of debris exposure rate measurements that are selected based on the 

veteran’s statements and responses in their ECUP Questionnaire. Contact exposure rate 

measurements for all debris surveyed in 1972 were reported in AEC (1973a) and are compiled in 

Appendix K. 

Parameter values and assumptions for estimating external doses for ECUP participants, 

who were involved in soil-removal activities, also apply to debris cleanup activities, which are 

shown in Table 27 to Table 29. For these exposure scenarios, external doses and upper-bound 

doses are estimated using the equations presented in Appendix C-1. In cases where a veteran 

performed debris cleanup activities on multiple islands, parameter values are estimated using 

simple or weighted averages across relevant islands as indicated for soil-removal activities in 

Table 28. Weighted averages for debris-cleanup activities can be calculated using the debris 

volumes shown in Table 31 and extracted from Figure 5-34 of DNA (1981). 

Table 31. ECUP participant debris cleanup volumes at Enewetak Atoll 

Island Name * Site Name Total volume of 

debris†,‡,§ (yd3) 

Northern Islands 

Bokoluo Alice 1,575 

Bokombako Belle 28 

Kirunu Clara 505 

Louj Daisy 5 

Bokaidrikdrik Helen 15 

Boken Irene 1,890 

Enjebi Janet 16,477**

Mijikadrek Kate 1,073 

Kidrinen Lucy 257 

Taiwel Percy 2 

Bokenelab Mary 158 

Elle Nancy <1 

Aej Olive 1 

Lujor Pearl 271**

Eleleron Ruby 251**

Aomon Sally 2,914**

Bijire Tilda 720 

Lojwa Ursula 2,115 

Alembel Vera <1 

Billae Wilma 64

Runit Yvonne 15,602**
111

Table 31. ECUP participant debris cleanup volumes at Enewetak Atoll (cont.) 

Island Name * Site Name Total volume of 

debris†,‡,§ (yd3) 

Southern Islands

Ananij Bruce 95 

Japtan David 790††

Jedrol Rex 28 

Medren (aka Parry) Elmer 41,028††

Enewetak Fred 110,780††

Ikuren Glenn 908 

Mut Henry 215 

Boken Irwin 270 

Ribewon James 254 

Kidrenen Keith 140 

Biken Leroy 197 

n/a Van 10 

Bokandretok Walt 10 

Total 198,650 

*

 Nine islands that had no debris removed are not included in this table 

†

 Debris volumes are from DNA, 1981, Figure 5-34. 

‡

 The debris volumes in this table include debris used as shore protection. 

§

 Volumes in this table are volumes of uncontaminated debris unless indicated otherwise. 

** The total volumes for these five islands include the following volumes of contaminated 

debris: Enjebi (530 yd3), Lujor (255 yd3), Eleleron (250 yd3), Aomon (728 yd3), 

Runit (4,120 yd3). 

†† A total of 55,000 yd3

 of debris were removed from these three islands by a scrap contractor 

(DNA, 1981, Figure 5-34). The volumes removed by the scrap contractor are excluded from the 

values in this table. 

6.2.3. External Dose from Lagoon Water and Sediments 

ECUP participants may have accrued an external dose while swimming in potentially 

contaminated lagoon or ocean water. A simplified seawater immersion dose methodology is 

documented for use in DoD’s NTPR program (Weitz, 2012). Applying this methodology and 

using the highest mean Cs-137 surface water activity concentration of 579 fCi L−1 (Table 12) 

results in a dose rate from immersion in water lower than 0.001 μrem h

−1

 to the whole body. A 

similar dose rate can also be estimated using EPA dose coefficients for water immersion 

(USEPA, 1993). Furthermore, using the highest mean near-surface water activity concentrations 

in Table 10–Table 12, and assuming swimming in the lagoon for 1 hour every day of a 6-month 

assignment, the resulting external effective whole body or organ dose (including skin) would be 

less than 0.001 mrem. Based on these results, swimming in the lagoon or ocean water was not a 

significant source of external exposure for ECUP participants and any related dose would be 

subsumed within applied upper-bound dose uncertainties. 

The sediments of the Enewetak lagoon also presented a potential source of external 

exposure to ECUP participants while swimming, walking, or working in the shallow waters of 
112

the lagoon. Using the mean activity concentrations of all significant radionuclides in Enewetak 

lagoon sediments shown in Table 13, together with the dose coefficients from USEPA (1993), 

the dose rate 1 m above Enewetak sediments was calculated to be approximately 0.01 mrem h−1

to any internal organ, and approximately 0.1 mrem h−1 to skin. Note that the mean lagoon 

sediment activity concentrations reported in Table 13 greatly overestimate the concentrations 

near the southern islands of the atoll, and it is not suitable to use these concentrations for dose 

estimates near any southern island, including residence islands. Furthermore, these estimates do 

not account for the shielding that would be provided by intervening lagoon water, which would 

reduce the dose rate by about a factor of 2 for every foot of water between the sediment and an 

exposed individual (Voss, 2001). Because of these considerations, residual radioactivity in the 

Enewetak lagoon sediments was not a significant source of exposure for ECUP participants and 

any related external dose would be subsumed within applied upper-bound dose uncertainties. 

6.3 Skin Dose 

Assessing the dose to the skin requires investigating the two major pathways of exposure: 

skin contamination and external non-contact sources of radiation. The methods discussed in 

Sections 6.1 and 6.2 can be used to estimate the gamma radiation dose to the skin from external 

sources. The skin doses from these two routes of exposure were not measured, i.e., there are 

neither dosimeter results for the skin nor measurements of contamination on the skin of the 

workers. Therefore, the doses are estimated by adapting methods developed for the DoD dose 

assessment and other U.S. government radiation assessment programs (Apostoaei and Kocher, 

2010; DTRA, 2010a; DTRA, 2010b; USEPA, 2002) discussed in Section 6.2. Potential doses 

from hot particles on the skin are not considered here; however, if hot particles are of concern the 

user should consult the scientific literature for guidance (e.g., USNRC, 2013 or NCRP, 1999). 

Chapter 4 of NCRP Report No. 130 (NCRP, 1999) presents a detailed review of the 

biology of the skin and its response to radiation. For radiation protection, it is assumed that the 

basal layer (at a nominal depth of 70 micrometers (μm)) of the epidermis contains the cells of

concern for skin cancer (DTRA, 2010a). The assumption that the basal layer contains the cells of 

concern is based on the continuous division of cells occurring there. The location of the cells of 

interest should be taken in to account when estimating the radiation dose to the skin regardless of 

the source. 

6.3.1. Skin Dose from Dermal Contamination 

Apostoaei and Kocher (2010) present a detailed process for calculating skin doses from 

fallout radionuclides deposited on the skin. In their report, they discuss models for skin 

contamination from descending fallout, suspension, and other sources and pathways. They also 

discuss the effects of showering and the radiation dose from alpha emitters. The methods of 

Apostoaei and Kocher (2010) and DTRA (2010b) are adapted for this report; the user should 

refer to these documents for a detailed analysis of skin dose from dermal contamination. The 

focus here is on radionuclides that were resuspended from the ground. Other sources, such as 

potentially contaminated lagoon water adhering to the skin after swimming, are not significant 

sources of skin dose. Moreover, to simplify the assessment, some factors that decrease the skin 

doses, such as clothing, self-attenuation of alpha particles, and shielding of alpha radiation by 

water, perspiration, or soil, are not included here. These factors can be difficult to accurately 

estimate, and omitting them helps to ensure that the assessment is high-sided. In addition, no 
113

accounting is made for incomplete removal of soil from the skin following a workday, e.g., 

inefficient or no showering. The methods of Apostoaei and Kocher (2010) can be used to 

account for these conditions, if necessary. However, the dose consequences of deviations from 

complete removal of contaminants from the skin following every workday are countered by the 

use of high-sided parameter values and application of upper-bound uncertainties. 

A high-sided skin dose from dermal contamination is estimated over a total time of 

12 hours. This is based on the assumption that the total amount of contaminated soil that could 

have gradually accumulated on bare skin over an 8 to 10-hour workday was deposited at the 

beginning of the workday and remained on the skin until completely removed by showering 

2 to 4 hours after the workday ended. The recommended parameter values shown or referenced 

in Table 32 are used in conjunction with the equations shown in Appendix C for deterministic 

estimates of the skin dose from dermal contamination. Brief discussions of several of these 

parameters that are not discussed elsewhere in this report follow Table 32. 

Table 32. Parameter values and assumptions for skin dose from dermal contamination 

Parameter Value Rationale/Reference/Comment

Work schedule 8–10 h d−1

for 6 d wk−1 DNA (1981) 

Daily exposure to 

dermal 

contamination 

12 h d−1

Value is the daily work hours plus an additional 

2–4 hours at which time complete removal of 

contaminated soil is assumed 

Dose coefficient See Table 33 and 

Table 35 (Cross et al., 1992; NCRP, 2009b) 

Skin dose 

modification factor See Table 34 Used with beta dose coefficients (Apostoaei and Kocher, 2010, Table 4-2) 

Resuspension factor 10−9–10−7 m−1(Bramlitt, 1977); see Appendix E 

Deposition velocity 3600 m h−1(Apostoaei and Kocher, 2010, Table 4-2) 

Interception and 

retention fraction See Table 36 (Apostoaei and Kocher, 2010, Table 4-1) 

Duration of duty 

tour 

Variable 

(default = 6 months) 

Based on individual’s arrival and departure 

records 

Fraction of workday 

exposed 

0.1 to 1 

(default = 1 

for full time) 

Fraction of a workday (not the total duration of 

exposure) that an ECUP worker is exposed to 

suspended soil, based on combination of task 

durations and analyst judgment 

Resuspension depth 1 cm Assumed reasonable value, see Section 7.1

Soil density 1.5 g cm−3

(AEC, 1973a; DOE, 1982a); see Section 7.1

Activity 

concentrations of 

undisturbed soil 

Island-specific 

mean values See Table 6

Activity 

concentrations of 

excised soil 

Island-specific 

weighted-average 

values shown in 

Table 43

Weighted average calculated from estimated 

total TRU activities and total volumes of soil 

removed from soil-removal islands (DNA, 

1981) 
114

The total dermal contamination skin dose is the sum of the doses from exposure to all the 

radionuclides present. If it is important for the risk assessment, then the dose from each type of 

radiation must be calculated and reported separately. Recommended dose coefficients for beta 

radiation emitted from Co-60, Sr/Y-90, and Cs-137 were selected from Table 5 of Cross et al. 

(1992) for a depth of 70 μm and are shown in Table 33. Because the recommended dose 

coefficients for beta radiation are applicable to a depth of 70 μm (7 mg cm−2), Apostoaei and 

Kocher (2010) developed the Skin Dose Modification Factor (SDMF) to account for different 

depths of the skin cells of interest at different skin sites. The SDMF is used in conjunction with 

the beta dermal contamination dose coefficients. The recommended values for the beta SDMF 

from Apostoaei and Kocher (2010) are shown in Table 34. 

Table 33. Recommended dermal contamination dose 

coefficients for Co-60, Sr/Y-90, and Cs-137 (for beta dose) 

Radionuclide Dose Coefficient 

(rem cm2 pCi−1 h−1)

Co-60 3.830 × 10-6

Sr-90 / Y-90 1.204 × 10-5

Cs-137 5.687 × 10-6

Table 34. Recommended values for beta SDMF 

Skin Site SDMF

Face, behind ears*, forehead, neck, 

shoulders, chest*, torso, under belt*, and 

upper legs 

1.3 

Back of neck*, forearms, lower legs, and 

under boot edge* 0.9 

Scalp*, palms of hands, backs of hands*, 

and soles of feet 0.3 

* SDMF values for these skin sites are not available in Apostoaei and Kocher 

(2010). The indicated values are recommended based on similar skin thickness or 

proximity to other sites on the body. 

The recommended dose coefficients for alpha emitters of concern (NCRP, 2009b) are 

shown in Table 35. The dose coefficients for alpha radiation vary with skin sites because the 

depth of the skin cells of interest was taken into account when the dose coefficients were 

developed. Dermal contamination alpha dose coefficients are also available in Apostoaei and 

Kocher (2010). The dose coefficients from NCRP (2009b), and Apostoaei and Kocher (2010), 

agree to within 2.5 percent. 
115

Table 35. Recommended dermal contamination 

dose coefficients for Pu-239/240 and Am-241(for alpha dose) 

Skin Site 

Dose Coefficient 

(rem cm2 pCi−1 h−1) 

Pu-239/240 Am-241 

- Forearms 

- Upper and lower legs 

- Under boot edges 

7.4 × 10-4 1.3 × 10-3

- Chest 

- Under the belt 6.7 × 10-3 8.2 × 10-3

- Face 

- Shoulders 

- Back and sides of torso 

- Scalp 

- Neck and behind ears 

- Back of neck*

- Forehead 

6.4 × 10-3 7.4 × 10-3

- Palms of hands 

- Backs of hands 

- Soles of feet 

0 0 

*

 Alpha dose coefficients for this skin site are not available in NCRP (2009b) or 

Apostoaei and Kocher (2010). The indicated values for this site are recommended 

based on its proximity to “neck and behind ears”. 

The deposition velocity describes the rate of deposition of suspended airborne soil 

particles onto the skin. This parameter is dependent on several conditions, especially particle 

sizes, the amount of movement of an individual within the suspended dust cloud, and the 

strength of the wind. The default deposition velocity of 3600 m h−1 (1 m s−1) was selected based 

on the range of deposition velocities recommended in Apostoaei and Kocher (2010) for 

individuals in motion in a dust cloud. That range has minimum, mode, and maximum values of 

0.3, 1.0, and 3.0 m s−1, respectively. Higher deposition velocities are possible in conditions of 

strong winds such as are typical at Enewetak Atoll. However, situations of high wind-driven skin 

deposition of contaminated soil were minimized during ECUP because of the requirement to 

wear protective clothing when it was necessary to conduct work downwind of soil-moving 

operations (EAI No. 5707.1). 

The interception and retention fraction quantifies the fraction of airborne soil moving by 

an individual that is deposited and retained on the skin. The value of this parameter varies with 

different areas of the body due to factors such as the presence or absence of hair or clothing. The 

value is normally less than 1.0 for most skin sites, but values greater than 1.0 are possible for 

areas of the body such as under a collar that can accumulate deposited soil. Recommended 

interception and retention fractions are taken from Apostoaei and Kocher (2010) and are shown 

in Table 36. 
116

Table 36. Recommended values for the interception and retention fraction 

Skin Site Interception and 

Retention Fraction

Face, neck*, shoulders, back and sides of torso, 

forehead, palms of hands, and soles of feet* 0.015 

Chest (unspecified amount of hair) 0.03 

Forearms, backs of hands*, upper legs, and lower 

legs (above boot edge) 0.06 

Scalp 0.23 

Back of neck under collar, under belt, under boot 

edge, and behind ears 1.5 

*

 Interception and retention fractions for these skin sites are not available in Apostoaei and 

Kocher (2010). The indicated values are recommended based on similarity to or proximity to 

other sites. 

The dose analyst should be aware of a reasonable upper bound of soil loading on the skin 

when using Equation C-14. When concentrations of soil on the skin exceed about 2 mg cm−2, the 

soil becomes visible and ad hoc cleaning is likely (Apostoaei and Kocher, 2010). Using the 

ranges of relevant parameter values shown in Table 32 and Table 36 in Equation C-14, the 

calculated soil loading on various skin sites ranges from approximately 0.0008 to 8 mg cm−2. 

These calculated soil-loading values will exceed 2 mg cm−2 only in high-retention areas of the 

body where the interception and retention fraction is 1.5, and for these sites, only in situations of 

sustained soil suspension greater than 1 × 10-8 m−1. For these situations, the dermal soil loading 

parameter in Equation C-14 should be limited to a value no higher than 2 mg cm−2. 

6.3.2. Skin Dose from External Non-Contact Sources of Radiation 

The equation for estimating the dose to skin from non-contact sources of radiation at a 

specific height or distance from external sources of radiation can be found in Appendix C. This 

equation is used with the parameter values and scenario assumptions listed in Table 37 and 

Table 38. 

The beta-to-gamma dose ratios for exposure to radionuclides in soil estimated from the 

1976 studies of Crase et al. (1982) at Enewetak Atoll have been determined to be reasonable for 

use in ECUP skin dose assessments. Using the median beta-to-gamma dose ratio of 0.29 

calculated for a height of 100 cm, which is based on the information reported in Crase et 

al. (1982), additional ratios for a range of heights from 1 to 200 cm were estimated and are 

shown in Table 38. The method used to estimate the beta-to-gamma dose ratios for various 

heights above the ground is described in Appendix L. 
117

Table 37. Parameter values and assumptions for skin dose from external 

non-contact radiation 

Parameter Value Rationale/Reference/Comment

Exposure duration Variable Calculated using values for “Work schedule” 

and “Duration of duty tour” below 

Work schedule 6 d wk−1

8–10 h d−1

(DNA, 1981) 

Duration of duty tour 

Variable 

(default = 6 mo 

= 26 wk) 

Based on individual’s arrival and departure 

records 

Fraction of workday 

exposed 

0.1 to 1 

(default = 1) 

Fraction of a workday that an ECUP worker 

is exposed to contaminated soil or other 

source of external non-contact radiation 

Exposure rate from 

soil Island-specific 

Island-specific exposure rates are shown in 

Table 4. See Section 6.2 for additional 

guidance on this parameter. 

Ratio of the beta dose 

to the gamma dose See Table 38 Rationale and additional guidance is provided in Appendix L

Modification Factor 0 to 1 

(default = 1) 

Default value assumes bare skin and no other 

modifications. 

Table 38. Beta-to-gamma dose ratio for external non-contact radiation sources for all 

islands at Enewetak Atoll 

Skin Height above Contaminated Ground Surface* (cm)

1 20 40 80 100 120 160 200 

Beta-to-gamma Dose 

Ratio 1.2 0.72 0.45 0.34 0.29 0.25 0.18 0.14 

*

 See Appendix L for guidance on determining beta-to-gamma ratios for heights not shown in this table and 

for estimating heights of various body locations. 

As an aid in estimating the height of a veteran’s skin site, reference heights from the 

ground for 11 anatomical locations and 3 postures, including standing, sitting in a chair and 

sitting on the ground, are provided in Appendix L. If the height above ground of a required skin 

site is not one of the heights given in Table 38, an equation is provided in Appendix L that can 

be used to estimate the beta-to-gamma ratio for the specific height, i.e., for any skin site for an 

ECUP veteran. Alternatively, interpolation techniques can be used to estimate ratios between the 

values listed in Table 38. 

6.3.3. Uncertainties and Upper-bound Skin Doses 

The dose estimation methods described above that use high-sided default values result in 

conservative estimates of skin doses for ECUP participants. However, parameter values 

applicable to an individual veteran could be much different from the default assumptions, 

resulting in large uncertainties in the calculated skin doses. For example, scenario or veteran 
118

circumstances that could result in a veteran’s skin dose that is higher than the dose estimated 

using default parameter values include the following: 

 A higher soil suspension than the recommended value for a given scenario 

 A skin thickness less than what is incorporated into the dermal dose coefficients and SDMF 

values 

 An amount of water or sweat on a veteran’s body that may result in retention at a specific 

skin site greater than what is assigned 

 Incomplete removal of all accumulated dermal contamination at the end of each day. 

On the other hand, factors that could result in a veteran’s skin dose that is lower than the 

dose estimated using default parameter values include the following: 

 Self-absorption of alpha emissions by contaminated soil particles deposited on the skin 

 Attenuation of alpha and beta emissions from dermal contamination by accumulated soil on 

the skin 

 The presence of clothing versus the default assumption of bare skin 

 Lower soil concentrations or soil suspension than the recommended default values 

 Less time spent near contaminated soil than the default assumption. 

If taken into consideration, some of the above factors would reduce or possibly eliminate 

a dominant skin dose exposure pathway, i.e., dermal contamination with alpha-emitters. The 

uncertainty in skin dose introduced by one of these factors, i.e., self-absorption of alpha particles, 

is due to characteristics such as unknown and variable shapes of soil particles and locations of 

alpha-emitting radionuclides in or on soil particles. Characteristics of soil particles contaminated 

with alpha-emitting radionuclides are hard to accurately quantify, and if quantified would carry 

large uncertainties. Therefore, self-absorption of alpha particles is not included in the ECUP skin 

dose estimation to simplify and high side the analysis. This approach is reasonable because 

estimated doses that do not include consideration of self-absorption of alpha particles are always 

higher than doses that include self-absorption. Similar over-estimation bias results from the 

assumption that contaminated soil was deposited on bare skin rather than on clothing. Deposition 

of contaminated soil on clothing would not result in a skin dose from deposited alpha-emitters 

because of full attenuation by the clothing. 

In addition to the pathway and scenario-related uncertainties discussed above, skin dose 

estimates involve other potential sources of uncertainty including measurement, data recording 

and processing errors, and spatial variability in environmental concentrations of contaminants. 

These aspects are discussed in Section 6.4. 

To help ensure that ECUP skin doses are not underestimated, upper-bound uncertainty 

factors, as defined in Section 6.4, are described here for use with the skin dose estimates 

calculated using the methods detailed above. The use of an uncertainty factor with high-sided 

skin dose estimates to arrive at estimates of upper-bound skin doses is consistent with the use of 
119

uncertainty factors with the high-sided external and internal dose estimates for ECUP veterans 

described in this report. 

Based on the standard methods developed for DTRA’s NTPR program an uncertainty 

factor of 3 is recommended for doses due to external non-contact skin exposures for ECUP 

veterans. This is based on the use of this factor for non-contact skin doses in the NTPR standard 

methods (DTRA, 2017). For the more complex exposure pathway of dermal contamination, 

uncertainty factors ranged from approximately 3 to 14 based on historical skin dose assessments 

performed for the NTPR program (DTRA, 2017). Because of the use of high-sided assumptions 

and parameter values described above, an uncertainty factor of 10 is considered adequate for use 

with the calculated ECUP skin doses due to dermal contamination. 

Finally, for both skin dose exposure pathways, i.e., dermal contamination and exposure to 

non-contact sources, the uncertainties are assumed correlated. Therefore, the upper bounds of 

each component of the skin dose for a specific skin location are summed to estimate the total 

upper-bound skin dose. Treating all pathway dose components as correlated is a highly 

conservative approach that results in overestimates of upper-bound doses. 

6.4 Uncertainties and Upper-bound External Doses 

Sources of uncertainty in estimating external doses for ECUP veterans are similar to 

those identified in other radiation dose assessments developed by DTRA (DTRA, 2017; 

Dunavant et al., 2017). These are generally attributed to, among others, imperfection in 

measuring instruments, spatial and temporal distributions, procedural errors, and data recording 

and processing errors. The following is a non-exhaustive list of potential sources of uncertainties 

in external dose estimation: 

 Instrument precision 

 Operator measurement and recording errors 

 Uncertainties due to data acquisition and data processing tools, such as data mapping 

 Spatial variability when only average values are reported or a few measurements are taken 

 Variability in the exposure times 

 Uncertainties in the isotopic mix of radioactive materials and method of estimating exposure 

rates 

 Imperfect knowledge of individual’s scenario of participation and radiation exposure, such as 

location and time, as well as shielding. 

The following subsections discuss the uncertainties in reconstructed, film badge, and 

TLD doses. Upper bound uncertainty factors are discussed. The method for applying uncertainty 

factors to individual dosimeter readings and for summing doses and deriving upper bound doses 

to an individual who wore multiple dosimeters, with or without reconstructed dose, are given in 

Appendix C. 
120

6.4.1. Uncertainty in Reconstructed External Doses 

Following the procedures an standard methods (SM) used for NTPR dose calculations, an 

uncertainty factor of 3 can be assigned to each external dose component calculated for the ECUP 

personnel (Schaeffer, 2015; Kocher, 2009; DTRA, 2017, SM UA01). In addition, it is generally 

appropriate to assume that the components of the external dose are uncorrelated, i.e., they vary 

independent of each other. Therefore, to determine an upper-bound external dose, the 

uncertainties of the external dose components are combined in quadrature (DTRA, 2017, 

SM UA01) as described in Appendix C. Using this uncertainty approach, the upper-bound dose 

is considered to exceed the 95th percentile dose determined from a hypothetical distribution of 

film badge doses for individuals exposed to the same sources of radiation. In addition, the 

uncertainty factor accounts for relatively small doses not explicitly estimated that are less than a 

few percent of the overall external dose, e.g., dose from swimming. 

6.4.2. Total Bias and Uncertainty in Film Badge Doses 

This section discusses the three principal sources of uncertainty in film badge dosimetry, 

namely laboratory, radiological (calibration), and environmental (NAS-NRC, 1989). It includes 

estimates for the bias and uncertainty factors for each source. A summary of the overall bias and 

laboratory, radiological and environmental uncertainty is provided. A method for applying the 

factors to film badge readings is described in Section 6.4.4. 

6.4.2.1 Laboratory Bias and Uncertainty 

Variations in laboratory techniques for processing film badges are important contributors 

to film badge dose uncertainty (Daniels and Schubauer-Berigan, 2005). Factors that come into 

play are consistency in dark room technique and control of the temperature while developing the 

film. Assuring that chemicals used in the film development do not become contaminated or 

depleted over time and tightly controlling the variation of laboratory room and chemical bath 

temperatures, result in technique consistency. The selection of the reference temperatures is 

important, as well as is tightly controlling the durations that films are kept in each of the multiple 

chemical process baths. These factors all can affect the relationship between film optical density 

and the known exposure intensity, a relationship that establishes the dose reported for a film 

badge of a given optical density (NCRP, 2007). Bias is 1.0 and the uncertainty for the laboratory 

source of error at the upper bound of a 95 percent confidence interval (CI) (97.5 percentile) is 1.3 

(NAS-NRC, 1989; NCRP, 2007; Daniels and Schubauer-Berigan, 2005). A summary of 

laboratory uncertainty factors derived from a study of film badge dosimetry (comparable to that 

used at ECUP), used at four National Laboratories and one Naval Shipyard (Daniels and 

Schubauer-Berigan, 2005, Figure 3) were used to estimate the values in Table 39. This table 

shows the uncertainty factors corresponding to various dose levels for laboratory uncertainty. 

The uncertainty factor increases as the dose decreases to the film badge’s limit of detection of 

20 mR (NAS-NRC, 1986). From the limit of detection to 70 mR, the uncertainty factor reaches 

an asymptotic value of 1.3. 
121

Table 39. Average film badge laboratory uncertainty factors 

for various dose ranges 

Dose Range (mrem)* Average Uncertainty Factor†

21–30 1.8

31–40 1.65 

41–50 1.45 

51–60 1.4 

61–70 1.3 

> 70 1.3 

*

 For a film badge dose at or below the MDL of 20 mrem including 0 mrem, the 

dose should be estimated by reconstruction; see Section 6.4.2.5 for further 

information. 

†Derived from Daniels and Schubauer-Berigan (2005, Figure 3) 

 

6.4.2.2 Radiological Bias and Uncertainty 

The overall accuracy and precision of film badge are optimum for high energy 

(>100 keV) gamma radiations (NCRP, 2007 pg. 155). The high-energy gamma radiation sources 

detected at ECUP were Cs-137 and Co-60. Matching the energy of the calibration source’s 

gamma radiation to the energies of the radiation in the field is a method for minimizing bias and 

uncertainty (NCRP, 2007). The degree of traceability of the calibration source to national 

standards can also contribute to bias and uncertainty and likewise for the design and wearing 

configuration of the film badge (NAS-NRC, 1989). The overall bias is 1.1 and the associated 

uncertainty for radiological sources of error at the upper bound of a 95 percent CI 

(97.5 percentile) is 1.1 (NAS-NRC, 1989; NCRP, 2007; Daniels and Schubauer-Berigan, 2005). 

6.4.2.3 Environmental Bias and Uncertainty 

Film badge calibrations and processing are done under tightly controlled environmental 

conditions in the laboratory while the environment for ECUP personnel wearing the badge can 

dramatically vary. The same can be said for control films that are kept on site nearby the ECUP 

person’s actual work location. These control film badges are maintained to measure background 

environmental radiation levels and are stored indoors under somewhat more controlled 

conditions than the work sites. In addition, wearing intervals and the amount of transit time to 

and from the processing laboratory can affect latent image fading on the badge creating a loss of 

signal when the film is processed. Additionally, the background fog level (natural darkening) can 

raise the signal. The effects of these factors have been found to be self-cancelling as regards bias 

and uncertainty (Daniels and Schubauer-Berigan, 2005). The overall bias is 1.0 and the 

associated uncertainty for environmental sources of error at the upper bound of a 95 percent CI 

(97.5 percentile) is 1.1 (NAS-NRC, 1989; NCRP, 2007; Daniels and Schubauer-Berigan, 2005). 

6.4.2.4 Summary of Bias and Uncertainty Factors and Application to Film Badge 

Readings 

Table 40 contains a summary of the bias and uncertainty factors discussed in the previous 

three subsections. Using the NAS analysis methods (NAS-NRC, 1989), the bias factors are 
122

combined multiplicatively and the uncertainties are combined in quadrature. The results of these 

computations are shown in Table 40 as the total bias and uncertainty factors. 

Table 40. Bias and uncertainty factors for various sources of 

error for film badge dosimetry 

Sources of Bias and 

Uncertainty Bias Factor Uncertainty Factor

Laboratory 1.0 1.3 – 1.8 

Radiological 1.1 1.1 

Environmental 1.0 1.1 

Total 1.1 1.3 – 1.8 

6.4.2.5 Lowest Reliable Film Badge Doses 

The minimum detectable level (MDL) is the minimum exposure that can be statistically 

distinguished from zero in the laboratory. The MDL is usually established at the point where the 

laboratory uncertainty is ± 100 percent at the 95 percent confidence interval (NAS-NRC, 1989). 

In an information bulletin furnished in LBDA (1973), the lowest reliable film badge dose is 

discussed. The methods and procedures described there are applicable for ECUP film badge 

doses because they were used for the cleanup project (Peters and Bramlitt, 1979). It was stated 

that films that show 0.00 optical density units are reported as a 0.0 dose. However, films may 

receive small amounts of radiation that are not reflected on the film due to the limitations of the 

film sensitivity. In addition, small doses may be shown on films known not to have been exposed 

to radiation. This is caused by inherent inaccuracies in films and densitometer uncertainty for 

low exposures. Because of these uncertainties, doses below the limits shown in Table 41 are 

considered highly uncertain. In addition, at these lower limits, the inaccuracies may be very large 

(LBDA, 1973). For the most important radiations potentially encountered by ECUP participants, 

i.e., energy greater than 200 keV, the lowest reliable film badge dose is 20 mrem. 

Table 41. Lowest reliable film badge doses 

Gamma or X-Ray Energy

(keV)

Lowest Reliable Dose*

(mrem)

< 100 2 

100–200 10 

> 200 20 

Beta Radiation 40 

*

 LBDA (1973) 

A preliminary evaluation of the ADC dose data for ECUP participants showed that over 

5,700 doses from undamaged film badges out of more than 11,000 film badge doses are less than 

or equal to the MDL of 20 mrem. In addition, in a 1986 report by NAS-NRC that reviewed the 

U.S. Army radiation dosimetry system, it was stated that one of the characteristics of the Army 
123

film badge, which was used at the ECUP, is that readings below about 20 mrem are so inaccurate 

that the results cannot be reported with any confidence (NAS-NRC, 1986). 

For the reasons stated above, for a film badge dose at or below the MDL of 20 mrem, 

including 0 mrem, the dose and upper-bound should be estimated by reconstruction. The 

methods used to estimate external gamma doses using environmental data are discussed in 

Sections 6.2 and 6.4.1. 

6.4.3. Uncertainty in TLD Doses 

An assigned ECUP participant TLD dose consists of the net TLD reading of the TLD 

worn by a participant. The net TLD reading is determined by subtracting the background 

exposure (see below) from the TLD reading of the participant’s TLD. The uncertainty in the 

assigned TLD dose is composed of the uncertainty in these two components, i.e., the 

participant’s TLD reading and the uncertainty in the background exposure. These uncertainties 

and their use in determining the overall uncertainty in a participant’s TLD dose are described in 

detail in Appendix D and are summarized in the following subsections. 

6.4.3.1 Uncertainties in TLD Readings 

The uncertainty in an ECUP participant’s TLD reading results from the following three 

sources (USN, 1975; USN, 1988): 

 Zero offset for the TLD reader zero reference level 

 Truncation of the digit on the display corresponding to tenths of a milliroentgen (mR) 

 The maximum allowable limit for system accuracy during performance testing. 

The uncertainties contributed by these three sources are estimated and combined in 

quadrature as described in detail in Appendix D, to result in uncertainties at least at the 

95th percentile confidence level. The resulting uncertainties and uncertainty factors for ECUP 

participants’ TLD readings are shown in Table 42. 
124

Table 42. Upper-bound uncertainty factor as a function of participant TLD reading 

TLD Reading (mR) Upper-bound Uncertainty Upper-bound Uncertainty 

Factor

1 0.60 1.60

2 0.80 1.40 

3 1.04 1.35 

4 1.31 1.33 

5 1.59 1.32 

6 1.87 1.31 

7 2.16 1.31 

8 2.46 1.31 

9 2.75 1.31 

10 3.05 1.30 

 10* Use Equation D-1 1.30 

*

 Upper-bound uncertainty at 95% confidence level is approximately 30% of the reading for TLD readings greater 

than 10 mR.

6.4.3.2 Background and Net TLD Dose Uncertainties 

To determine the participant’s net TLD reading, an averaged total background exposure 

may be available on a TLD Report listing the details of the participant’s TLD badge reading. If a 

TLD Report is not available, a background exposure is estimated using ECUP control TLD 

readings or corrected readings. These consist of 15 sets of 10 background exposure results from 

control TLDs that were exposed during 10 separate periods from July 1978 to February 1980. 

The control TLD readings were obtained from the ECUP radiation safety program records. A 

mean background exposure rate of 0.116 mR d−1 is calculated from the 150 control TLD 

readings, including corrected readings. If a TLD Report is not available, the background 

exposure is determined by multiplying the mean background exposure rate by the number of 

days in the TLD wearing period. As described in Appendix D, statistical analysis was used to 

determine a 95th percentile background exposure rate of 0.125 mR d−1 for the 150 control TLD 

readings. The resulting uncertainty factor for the background exposure rate is therefore 1.08 

(0.125/0.116), that can be rounded up to 1.1. Therefore, the uncertainty associated with the total 

background exposure is 0.10  total background exposure, or 10 percent. The uncertainty in the 

background exposure thus calculated is combined in quadrature with the uncertainty in the 

participant’s TLD reading, from Table 42, to estimate the total uncertainty in a participant’s 

assigned TLD dose. 

6.4.4. Method for Calculating Total Doses and Total Upper Bound External Doses 

The total bias and uncertainties associated with each category of external dose identified 

in the previous sub-sections (reconstructed doses, valid film badge doses, and TLD doses) should 

be calculated for all dose periods for an ECUP participant. Total uncertainties for each dose 

category should be combined as described in Appendix C. The total external dose and the total 

upper-bound external dose should then be calculated as described in Appendix C. 
125

Section 7. 

Internal Radiation Dose Assessment Methods 

Bioassays can provide a basis for estimating radionuclide intakes and internal doses. As 

described in Section 4.8.2, bioassay results for the majority of individuals consisted of a single 

urine sample submitted at the end of their assignment. Results for all individuals who submitted 

a sample indicated that Pu-239 activity concentrations were less than the MDA. Because internal 

doses determined from a single bioassay result, especially for a result less than MDA, may not 

provide a credible estimate of total radiation exposure of internal organs and tissues (Boecker et 

al., 1991), these bioassay results are not recommended for use in ECUP internal dose 

assessments. 

Radiation doses to organs and tissues due to exposures from internally deposited 

radioactive material can be estimated using well-established dose reconstruction methods 

developed by DoD dose assessment programs, such as DTRA’s NTPR Program (DTRA, 2017). 

The methods employed in dose assessments for compensation programs rely on high-sided 

estimates of parameter values used in the calculation of doses to personnel for all applicable 

exposure pathways. Sources and pathways of exposure to radiation for ECUP participants are 

described in Section 5. Estimated internal doses are combined with uncertainty factors to 

calculate upper-bound doses that are expected to exceed the 95th percentile of dose distributions 

if determined using probabilistic analysis. 

This section describes the assumptions and parameter values that are used to estimate 

doses for ECUP participants from internal radiation exposures of organs and tissues. The 

equations used for dose estimation are presented in Appendix C. Examples of exposure scenarios 

and results of radiation dose calculations for ECUP personnel are presented and discussed in 

Section 8. For veteran dose estimates that would be prepared in response to VA requests, all 

sources of radiation and intake pathways that are applicable to the individual should be 

considered; a veteran’s RDA would be performed following the recommended guidelines 

discussed in Section 9. 

7.1 Inhalation of Suspended Soil 

Internal doses from inhalation of suspended contaminated soil are estimated based on the 

types of jobs performed by ECUP participants, durations of exposures, and soil activity 

concentrations, which in turn depend on the location where the job was conducted or from where 

the soil was removed. The parameter values and exposure scenario assumptions shown in 

Table 43 are used to estimate internal doses from the inhalation of airborne radioactive materials 

using the methods presented in Appendix C. Activity concentrations of undisturbed soil are 

extracted from radiological survey data compiled in Section 4. Estimated activity concentrations 

in excised soil are based on total estimated TRU activity and total volume of soil removed from 

each contaminated island as reported in DNA (1981). The estimated concentrations and the 

volume of soil removed from each island are shown in Table 44 with a more detailed analysis 

given in Appendix B-2. The respiratory protection factors are shown in Table 45 and are 

discussed in Appendix F. 
126

Table 43. Parameter values and assumptions for estimating internal doses 

from inhalation of suspended soil 

Parameter Value Rationale/Reference/Comment 

Activity concentrations 

of undisturbed soil 

Island-specific or 

multi-island average 

Mean island-specific values are shown 

in Table 6. See Table 28 in Section 

6.2.1 for guidance on averaging when 

multiple islands are involved. 

Activity concentrations 

of excised soil 

Island-specific 

(See Table 44) 

Calculated from estimated total TRU 

activity and total volume of soil 

removed from each contaminated 

islands (DNA, 1981) 

Work schedule 10 h d−1 for 6 d wk−1(DNA, 1981) 

Average daily time spent 

outdoors 

 Outdoor workers: 

 Indoor workers 

 Workdays: 

 Non-workdays: 

15 h d−1 for 7 d wk−1

5 h d−1 for 6 d wk−1

15 h d−1 for 1 d wk−1

The times listed here are total time 

outdoors (residence + work islands). 

All non-work time other than sleeping 

and eating is assumed recreational 

time spent outdoors on the residence 

island (see Table 29 in Section 6.2.1). 

Duration of duty tour Variable 

(default = 6 months) 

Based on individual’s arrival and 

departure records 

Resuspension factor 10−9 to 10−7 m−1

(AEC, 1973a; Bramlitt, 1977); see 

data analysis in Appendix E 

Depth of soil available 

for suspension 1 cm (DTRA, 2017, SM ID01; AEC, 1973a)

Soil density 1.5 g cm−3(AEC, 1973a; DOE, 1982a) 

Mass loading 40–600 g m−3

(Oztunali et al., 1981; AEC, 1973a; 

Yu et al., 2015); see Appendix E

Enhancement factor < 1 to 6.5 

(Default = 3) See Appendix E

Breathing rate 1.2 m3 h−1

Applicable to an adult male during 

light activity/exercise (DTRA, 2017, 

SM ID01) 

Respiratory protection 

factor See Table 45 See Appendix F

Inhalation dose 

coefficients 

Organ- and radionuclidespecific; AMAD = 1 μm,

(rem pCi−1) 

Worker dose coefficients, extracted 

from ICRP Publication 68 (ICRP, 

2011) 

Fraction of time exposed 

to source 

0.1 to 1 

(default = 1) 

Fraction of a workday that an ECUP 

worker is exposed to suspended soil, 

based on questionnaire responses and 

task durations 
127

Table 44. Estimated average activity concentration of contaminated soil excised and 

moved to Cactus Crater and dome 

Island with

Contaminated Soil 

Removed

Total TRU 

Activity 

(Ci)*

Soil Volume Removed (yd3)

* Average TRU 

Activity 

Concentration

(pCi g−1)

†

Disposed 

in Crater

Disposed 

in Dome Total

Medren 0 110 0 110 0

‡

Aomon 1.29 10,603 0 10,603 106

Aomon Crypt 0.93 448 9,328 9,776 83

Boken 1.01 421 4,516 4,937 178

Enjebi 2.57 43,023 9,984 53,007 42

Lujor 1.70 0 14,929 14,929 99

Runit 7.22 0 10,735 10,735 587

Overall totals 

(Runit not included) 7.50 54,605 38,757 93,362 70§

Overall Totals 

(Runit included) 14.72 54,605 49,492 104,097 123§

*

 Total TRU activity values and soil volumes are from Figure 8-34 of DNA (1981). 

†

 Soil activity concentrations are based on an average bulk soil density of 1.5 g cm−3 (AEC, 1973a; DOE, 

1982a). 

‡

 The 110 cubic yards of soil removed from Medren was contaminated only with Co-60, with hotspots ranging 

between 20–2000 pCi g−1. Based on soil volumes removed and their maximum concentrations, the average 

Co-60 activity concentration in this soil is estimated to be less than 170 pCi g−1. (DNA, 1981) 

§

 These average TRU soil activity concentrations are weighted averages calculated using total soil volume 

removed from each island. 

Table 45. ECUP personnel protection levels and respiratory protection factors 

ECUP Personnel 

Protection Level ECUP Respiratory Protection* Respiratory Protection Factor†

I or IIA None 1 

IIB Surgical mask (dust mask) 1 

IIIA or IIIB 

Full-face negative pressure respirator 50 

Half-face positive pressure respirator 50 

Full-face positive pressure respirator 1,000 

IV Full-face positive pressure respirator 1,000 

*

 Half-face, negative pressure respirators (protection factor of 10 [USNRC, 1976]) are mentioned in some ECUP 

documentation (e.g., FCRR SOP 608-10 “Decontamination Laundry Procedures”). However, this respirator type 

is not listed in the ECUP Personnel Protection Level documentation (EAI No. 5707.1; DNA, 1981). 

†

 For use in ECUP dose assessments, the respiratory protection factor for work in Controlled Access areas can 

normally be determined from the Personnel Protection Level specified in relevant Controlled Island Access 

forms. When Level IIIA or IIIB is indicated in the Controlled Island Access form, a respiratory protection factor 

of 50 should be used unless it is known that a full-face, positive pressure respirator was worn. 
128

Discussions of the parameter values and assumptions for exposure scenarios involving 

inhalation of suspended soil are included below. 

 Soil activity concentrations: Activity concentrations for both undisturbed and excised soil 

are required, but their use depends on a specific individual’s participation and exposure 

scenario. Both of these sets of values are island-specific as shown in Table 6 and Table 44. 

Scenarios involving general work on an island would likely involve only undisturbed soil. 

Island-average activity concentrations for undisturbed soil on each island are shown in 

Table 6 and are recommended for use in these scenarios. These mean values are primarily 

arithmetic means and generally high side the central estimates of the soil activity 

concentration distributions. 

The average TRU activity concentration calculated for soil removed from each of the five 

soil-removal islands is shown in Table 44. These soil activity concentrations calculated for 

excised soil would be appropriate for use in scenarios involving exposure to suspended soil 

during soil removal disturbances such as bulldozing, loading, and unloading activities. In 

addition, these soil activity concentrations are significantly higher than the island-average 

TRU activity concentrations in the top 15 cm of undisturbed soil for all soil-removal islands. 

To simplify internal dose calculations, all radioactivity in excised soil can be assumed 

Pu-239 as long as total TRU activity concentrations from Table 44 are used to estimate 

airborne activity concentrations of suspended soil or soil that is incidentally ingested. The 

basis for this assumption is discussed in Appendix G. If measured airborne activity 

concentrations in suspended excised soil are used for dose estimates, all radionuclides of 

concern should be included. However, such measurements are generally not available for use 

in inhalation dose estimates over extended periods. 

In cases where a veteran worked on multiple islands, the estimated soil activity concentration 

to which he was exposed depends on the nature of work and the amount of time he worked 

on each island. For example, if the veteran participated in soil-excavation work and the 

number of days on each island is known based on the Controlled Island Access forms (see 

Figure 5), a time-weighted average of the soil activity concentrations for excised soil from 

each relevant island may be used. However, if the amounts of time spent on the islands are 

not certain, a volume-weighted average of the individual island excised soil activity 

concentrations can be used. This method is based on the assumption that the amount of time 

spent on an island by a worker involved in soil-removal activities is proportional to the 

amount of soil removed from the island. This is the approach used in the example scenario 

described in Section 8.2 for debris-cleanup work, and it can be applied to excised soil as 

shown by the weighted average concentrations presented in Table 44. Guidance on averaging 

methods for estimating soil activity concentrations for scenarios involving work on multiple 

islands is shown in Table 28 for four categories of worker participation. The overall volumeweighted average TRU soil activity concentrations in Table 44 can be used for excised soil 

that was stockpiled on Runit. 

 Work schedule: The work schedule for individuals involved in handling excised soil or near 

suspended soil depended on several factors. The default values shown in Table 43 are based 

on a 10-hour workday for 6 days each week. For northern island workers, it is assumed that 

there was a total of two hours spent traveling between Lojwa and the work island each 

workday. This is a reasonable average value based on travel times derived from LCU boat 
129

logs and FRST Operational Reports11 of about one hour each way between Lojwa and 

Enjebi, and between Lojwa and Runit. The assumed workweek is 6 days because ECUP 

workers typically did not work on Sundays. 

 Duration of duty tour: Arrival and departure cards are available for each individual who 

visited or worked at Enewetak Atoll during the cleanup project. If such records are found to 

be missing, the default duration of duty is assumed 6 months based on the typical ECUP 

assignment of 4–6 months (DNA, 1981). 

 Resuspension factor and mass loading factor: Resuspension factors and mass loading 

factors used for estimating airborne activity from the suspension of soil are discussed in 

Appendix E. The lower value of 10−9 m−1 of the recommended range is an appropriate value 

for individuals upwind of soil disturbances, and the upper value of 10−7 m−1 is a more 

appropriate value for locations downwind of on-going soil disturbances. As indicated in 

contemporaneous reports and as required by ECUP SOPs, personnel were located upwind of 

soil disturbances and were rarely downwind during cleanup activities involving airborne 

contaminated soil and dust. Based on the discussion in Appendix E, the proposed generic 

value of 100 μg m−3 for mass loading is considered a conservative value that can be used as a 

representative average applicable to the entire duration for personnel not performing 

activities involving removal or handling of contaminated soil. Further guidance for the use of 

these values is given in Appendix E. 

 Depth of soil available for suspension: This value is variable and is not well characterized. 

However, a value of 1 cm is a typical assumption used in dose assessment studies (AEC, 

1973a; DTRA, 2017, SM ID01). 

 Soil density: Based on 364 soil density measurements for the top 5 cm obtained in December 

1979, a mean wet soil density of 1.53 g cm−3 with a standard deviation of 0.14 g cm−3 was 

estimated (DOE, 1982a). The value of 1.5 g cm−3 was used in DOE radiation dose 

assessments for future Enewetak inhabitants (AEC, 1973a) and several other relevant 

publications. Therefore, the value of 1.5 g cm−3 is recommended for ECUP dose assessments. 

 Enhancement factor: This factor is used with the mass loading values to account for the 

potentially higher airborne activity concentration of suspended soil compared to the source 

soil. Values for plutonium enhancement factors typically range from less than 1.0 to 6.5, and 

a reasonably conservative value of 3.0 is used in this report for all radionuclides. This factor 

is also discussed in Appendix E. 

 Breathing rate: The default breathing rate of 1.2 m3 hr−1 is based on an adult male 

performing light activities, comparable to walking at a rate of 3 mph on a flat firm surface 

(DTRA, 2017, SM ID01). This rate is used as an average, constant breathing rate for all 

periods and activities where inhalation exposure is applied. 

 Respiratory protection factor: This factor represents the degree of protection afforded by a 

respirator, and it is equal to the ratio of the concentration of contaminants outside the 

respirator to the concentration inhaled. Therefore, the inhaled concentration equals the 

 

11 FRST Operational Reports are the daily reports prepared by a FRST Team Chief on JTG Form 16 for a specific 

Controlled Access Area. The forms contain serial numbers of survey meters used, and a Narrative section that may 

contain times, activities conducted, use of PPE, and other items relevant to radiological control. 
130

ambient concentration divided by the respiratory protection factor. The respiratory protection 

factors shown in Table 45 are taken from contemporaneous and current USNRC guidance 

(USNRC, 1976; USNRC, 2017) and are discussed in Appendix F. The numerical protection 

factor used in dose assessments for ECUP participants can be based on the respiratory 

protection worn or the Personnel Protection Level specified for a given activity. For work in 

controlled-access areas, the protection factor is determined from the Personnel Protection 

Level specified in the relevant Controlled Island Access form (see Figure 5). When Level 

IIIA or IIIB is indicated in the Controlled Island Access form, a respiratory protection factor 

of 50 should be assumed, unless it is known that a full-face, positive pressure respirator was 

worn, in which case a respiratory protection factor of 1,000 is applicable. 

 Inhalation dose coefficients: To high side the dose estimates, it was assumed that all 

suspended soil particles were respirable with an average activity median aerodynamic 

diameter (AMAD) of 1 μm. This conservative assumption results in dose coefficients that are

higher than those of AMADs in the 3–10 μm range by factors of up to about 4 for most

organs. In addition to particle size, the chemical form of a radionuclide also affects the dose 

delivered to internal organs. Chemical forms of the radionuclides of concern at Enewetak are 

not well known. Therefore, when a choice was available in determining the dose coefficients 

for Sr-90, Sb-125, Pu-239, and Co-60, “unspecified compounds” was assumed. This results 

in higher dose coefficients by factors of up to 20 for Sr-90 and Pu-239 for most organs. For 

Co-60, Type M dose coefficients for “unspecified compounds” are generally lower than 

Type S dose coefficients by a factor of up to 4. For the most important radionuclides of 

concern with regard to internal dose, e.g., Pu-239, these assumptions high side the organ 

doses by at least a factor of 8. (ICRP, 2011) 

 Fraction of time exposed to source: This factor is intended to account for the fraction of a 

workday that an ECUP worker is actually exposed to suspended soil. Examples of scenario 

characteristics that could be accounted for include fraction of a workday that soil handling is 

occurring, and the locations of personnel with respect to the prevailing wind. Because of the 

difficulty in determining an appropriate value, and to simplify future assessments, the 

recommended default value for this parameter is 1.0. 

7.2 Incidental Ingestion of Soil and Dust 

Internal doses from incidental ingestion of contaminated soil and dust may have resulted 

from inadvertent intake by the mouth of small quantities of soil and dust particles that adhered to 

food, beverages, cigarettes, or hands. Any ECUP veteran who visited an island with 

contaminated soil had the potential for incidental ingestion of contaminated soil and dust in the 

course of their assigned activities. However, use of a dust mask or respiratory protection would 

preclude this exposure pathway. The dose from this pathway is calculated as a chronic type of 

exposure that involved non-specific intakes of relatively small quantities of soil and dust. The 

parameter values and exposure scenario assumptions shown in Table 46 are used to estimate 

internal doses from this pathway using the methods presented in Appendix C. Activity 

concentrations in undisturbed soil are extracted from radiological soil survey data compiled in 

Table 6. Estimated activity concentrations in excised soil are based on total estimated TRU 

curies and total volume of removed soil from each contaminated island reported in DNA (1981). 
131

These estimated concentrations and the volumes of soil removed from each island are shown in 

Table 44. 

Table 46. Parameter values and assumptions for estimating internal doses from 

the incidental ingestion of contaminated soil and dust 

Parameter Value Rationale/Reference/Comment 

Incidental soil and 

dust ingestion rate 0.05 g d−1 Central tendency value for adults in rural setting (USEPA, 2017a) 

Activity 

concentrations of 

undisturbed soil 

Island-specific; 

values shown in Table 6

Mean values are used for most 

radionuclides as high-sided central 

estimates. This pathway should 

typically be assessed for one of the 

residence islands. 

Work schedule 6 d wk−1 DNA, 1981 

Time on residence 

island 7 d wk−1 Full-time occupancy on residence island is assumed. 

Duration of duty tour Variable 

(default = 6 months) 

Based on individual’s arrival and 

departure records 

Fraction of workday 

exposed 0–1.0 

Accounts for time in controlled 

areas when respiratory protection 

prevents ingestion 

Ingestion dose 

coefficients 

Organ- and radionuclide-specific 

(rem pCi−1) 

Worker dose coefficients taken 

from ICRP Publication 68 (ICRP, 

2011) 

Brief discussions of the parameter values and assumptions for exposure scenarios 

involving incidental ingestion of soil and dust are included below. 

 Incidental soil and dust ingestion rate: The default rate of 0.05 g d−1 is recommended in 

the USEPA Exposure Factors Handbook as the mean value for daily adult incidental 

ingestion of soil and dust in rural settings (USEPA, 2017a). This mean value is judged a 

reasonable value to assess this ingestion pathway for ECUP participants. 

 Soil activity concentrations: Activity concentrations for undisturbed or excised soil may be 

required, and their use depends on the specific individual’s participation and exposure 

scenario. Both of these sets of values are island-specific. The default ECUP assumption is the 

use of island-average mean soil concentrations for undisturbed soil, as this is more 

appropriate for this chronic, long-term exposure pathway. 

 Work duration: See discussion for this parameter in Section 7.1. 

 Duration of duty tour: See discussion for this parameter in Section 7.1. 

 Fraction of workday exposed: This factor accounts for the fraction of a day that incidental 

ingestion of soil and dust is a potential exposure pathway for an ECUP worker. The factors 

affecting the specific value used within the range shown in Table 46 are the amount of time 

spent on a controlled island or near contaminated soil, and the fraction of that time that the 
132

individual is not wearing any respiratory protection that covers the mouth. The latter 

assumption is valid because this exposure pathway involves contamination on items such as 

food and cigarettes, or on the hands, to be placed in or near an individual’s mouth. 

 Ingestion dose coefficients: Similar to the inhalation dose coefficients discussed above, 

when a choice was available in determining the dose coefficients (for Sr-90, Pu-239, and 

Co-60), “Unspecified compounds” was assumed. For all organs, this assumption results in 

the use of very similar or higher dose coefficients than those for alternative choices by 

factors of up to 30 for Sr-90 and up to 50 for Pu-239. Ingestion dose coefficients for Co-60 

do not vary much for different chemical forms (ICRP, 2011). 

7.3 Incidental Ingestion of Lagoon and Ocean Water 

Internal doses from incidental ingestion of potentially contaminated lagoon or ocean 

water may have resulted from the inadvertent ingestion of small quantities of water during diving 

duties or recreational water-based activities. Among many waterfront activities, ECUP 

participants spent time swimming, snorkeling, spearfishing, scuba diving, and sailing in lagoon 

or ocean waters. It is most likely that these recreational activities took place near the residence 

islands of Enewetak or Lojwa during off-duty time, i.e., at the end of a workday and on 

weekends. On the other hand, U.S. Navy divers were involved in underwater inspection, survey, 

and debris recovery and retrieval among other duties. They used SCUBA gear with or without 

helmets, or with an ordinary diving mask. 

For recreational activities, the estimate of internal doses from the incidental ingestion of 

potentially contaminated lagoon or ocean water considers the type of the water-based activity, 

length of exposures, and radionuclide concentrations in the water where the activity took place. 

Table 10 to Table 12 of Section 4.5 present the sampling results of activity concentrations of 

Cs-137 and Pu-239/240 for lagoon and ocean water. Other radionuclides were detected in a very 

small number of samples at concentrations significantly lower than these two radionuclides, at 

levels that would not affect the dose results. Using the highest mean 3-foot deep sample activity 

concentrations from Table 10 to Table 12, a water ingestion rate of 36 mL h−1 for adult men 

swimming in seawater12 (USEPA, 2019), and assuming recreational swimming in the lagoon for 

1 h d−1 every day of a 6-month assignment, maximum doses were estimated. This scenario is 

considered bounding for all water-based recreational activities for this pathway. The estimated 

upper-bound committed effective dose equivalent is 0.007 mrem. The highest organ upper-bound 

committed dose equivalent is approximately 0.2 mrem for bone surface. 

Because of the divers’ more frequent and extended contact with lagoon and ocean water, 

they were more likely to receive a higher radiation dose from this exposure pathway than 

personnel who were only involved in recreational swimming and sailing. Divers usually wear 

SCUBA gear with a full-face mask, a diving helmet, or an ordinary diving mask. In a survey 

among professional divers, it was strongly indicated that they ingested much less water when 

wearing a full-face mask instead of an ordinary diving mask and even less when wearing a 

diving helmet. These occupational divers are estimated to swallow about 10 mL of marine water 

per dive, which is an average over wearing all types of diving masks or helmets (Schijven and de 

Roda Husman, 2006). 

 

12 This value is based on an average value of ingesting 27 mL in a 45 min swim (USEPA, 2019). 
133

The duration of a dive for an occupational diver is reported to be typically 60 

to 95 minutes (Schijven and de Roda Husman, 2006). Assuming 60-minute dives, a maximum of 

8 dives per workday and 6 workdays per week, an ECUP diver could have conducted as many as 

1,248 dives over a 6-month period of deployment. Maximized doses were estimated using this 

number of dives together with the highest concentrations of Cs-137 and Pu-239/240 in Enewetak 

near-surface water from Table 10 to Table 12, and an ingestion rate of 10 mL per dive. The 

resulting upper-bound committed effective dose equivalent is approximately 0.01 mrem and the 

highest organ upper-bound committed dose equivalent is approximately 0.3 mrem for bone 

surface. 

Near-surface water activity concentrations were used in the assessment above. This is 

because divers were responsible for collecting and surveying debris located offshore from the 

high tide line out to a depth of 15 feet in the water at low tide (DNA, 1981). Therefore, the 

activity concentrations measured in the deep-water range of 46–195 feet in craters, shown in 

Table 10, do not represent the radionuclide concentrations to which the divers may have been 

exposed to in lagoon water. 

Based on the above assessment results, the potential doses to ECUP personnel from 

incidental ingestion of lagoon or ocean water during recreational swimming or occupational 

diving are less than 0.001 rem for any organ or effective dose. Therefore, this pathway is not 

considered a significant exposure pathway for ECUP personnel. Any internal dose related to this 

type of exposure would be largely subsumed within the upper-bound internal dose uncertainties; 

hence, there is no need to estimate these doses separately.

7.4 Ingestion of Food and Drinking Water 

7.4.1. Consumption of Local Food 

As discussed in Section 5, the food consumed by ECUP personnel was prepared using 

ingredients supplied through the military logistics system and as such, it was not a source of 

radiation exposure. However, regarding foods obtained from Enewetak Atoll, anecdotes of 

ECUP veterans indicate that some participants consumed locally gathered marine and terrestrial 

foods while off-duty (Cherry, 2018b; Fitzgerald, 2017; Tupin, 2018). To evaluate the 

significance of this potential exposure pathway, an assessment of organ doses from consuming 

local foods was conducted and is described in detail in Appendix M. Key parameter values are 

based on the data reported in Section 4 and a summary of the highest organ doses are described 

below.

Consumption of six local foods are assessed in this report. The most likely local foods 

that might have been consumed by ECUP participants are fish and spiny lobster from the ocean 

and lagoon, and coconut meat and coconut milk from the land. Coconut crabs are also included 

because veterans might have eaten them according to some anecdotal accounts (Fitzgerald, 

2017). In addition, giant clams were consumed according to one veteran’s statement in a 

questionnaire submitted in connection to his radiation dose assessment. Other foods can be 

assessed on a case-by-case basis if consumption of such foods is claimed by a veteran in their 

ECUP questionnaire. 

Average activity concentrations of key radionuclides that were measured in each of the 

edible parts of the selected local foods from all samples collected on the atoll are given in 

Table 18. The wet-to-dry weight ratios and the food consumption rates are listed in Table 47. 
134

The rationale for each assumed consumption rate for ECUP personnel is given in Appendix M. 

Using these assumptions, committed equivalent doses per serving were calculated using 

Equation M-1 presented in Appendix M. The highest estimated organ ingestion doses per serving 

based on these concentrations and parameter values are shown in Table 48. Doses for all organs 

and foods are given in Appendix M. 

Table 47. Parameter values for estimating ingestion doses from eating local foods 

Edible Part of Local Food Wet-to-Dry Ratio* Consumption Rate 

(g per serving)

Fish muscle 3.5 300 

Spiny Lobster muscle 4.32 500 

Coconut Meat 2 400 

Coconut Milk 20 300 

Coconut Crab muscle 4.1 500 

Clams (Giant) 6.4 500 

*

 Values are taken from AEC (1973a), except that the ratio for muscle of the common shore crab is used for 

coconut crab muscle (Bjerregaard and Depledge, 2002). 

Table 48. Estimated dose per serving from the consumption of local foods 

Local Food

Estimated Dose (rem per serving)

Highest Organ Dose 

(Organ) Committed Effective Dose 

Fish 9.8 × 10−4

(Bone surface) 3.1 × 10−5

Spiny Lobster 2.5 × 10−5

(Bone surface) 1.4 × 10−6

Coconut Meat 5.0 × 10−4

(Bone surface) 9.5 × 10−5

Coconut Milk 1.3 × 10−4

(Bone surface) 7.1 × 10−5

Coconut Crab 1.7 × 10−4

(Bone surface) 3.4 × 10−5

Clams (Giant) 5.8 × 10−4

(Bone surface) 2.7 × 10−5

The default assumption for ECUP dose assessments is that local food was not consumed. 

The pathway should be included only if a veteran mentions that local food was consumed. If 

applicable, the exposure should be assessed using the estimated per-serving doses together with 

consumption information supplied by the veteran. If a veteran recalls that he ate local foods but 

doesn’t specify the type and amount, then the default assumption is one serving of fish once a 
135

month. Fish is the default food because its consumption produces the highest per-serving dose to 

the bone surface. The default frequency of one serving per month is based on the recollection of 

an ECUP veteran that the eating of locally gathered fish only took place sporadically (Tupin, 

2018). 

Based on the upper-bound doses summarized in Table 49, the total internal dose accrued 

by an ECUP participant who may have potentially consumed local foods can be estimated. Using 

the default assumption as an example, a veteran who was deployed for 6 months is assumed to 

have consumed one serving of locally caught fish per month for a total of 6 servings. Using these 

assumptions, the estimated total upper-bound doses to various internal organs range from less 

than 0.001 to 0.06 rem, the lowest dose being to the breast and the highest to bone surface. The 

estimated upper-bound committed effective dose is 0.002 rem. Additional details and results of 

estimating doses from consuming local foods are given in Appendix M. 

Table 49. Upper-bound doses per serving from the consumption of local foods 

Local Food

Upper-Bound Dose (rem per serving)

Organ Dose Range Committed Effective Dose

Fish 3.8 × 10−5– 9.8 × 10−33.1 × 10−4

Lobster 2.9 × 10−6– 2.5 × 10−41.4 × 10−5

Coconut Meat 6.2 × 10−4– 5.0 × 10−39.5 × 10−4

Coconut Milk 5.8 × 10−4– 1.3 × 10−37.1 × 10−4

Coconut Crab 2.0 × 10−4– 1.7 × 10−33.4 × 10−4

Clams (Giant) 4.5 × 10−5– 5.8 × 10−32.7 × 10−4

7.4.2. Ingestion of Drinking Water 

All water used by ECUP participants for drinking, cooking, and bathing was produced by 

distilling ocean water (DOE, 1982a). Production volumes of the distillation plants at Enewetak 

and Lojwa Islands were monitored and reported regularly. An adequate supply of distilled water 

was achieved throughout the project as reported in the weekly SITREPs. The ocean water mean 

activity concentrations shown in Table 11 are 0.43 fCi kg−1 and 0.21 fCi L

−1

 for Pu-239/240, and 

32 fCi kg−1 and 146 fCi L−1 for Cs-137. These concentrations are comparable to concentrations 

measured in the western Pacific and north Atlantic Oceans (Aoyama and Hirose, 1995; Morgan 

and Arkell, 1963; AEC, 1973a). In addition, in the distillation process, water is boiled and steam 

is condensed to remove salts, metals, minerals, and particulates (USEPA, 2005). This is borne 

out by available distilled water concentration measurements shown in Table 19. The maximum 

measured concentration of Cs-137 in distilled water reported in Table 19 is 22 fCi L

−1

, which is 

lower than ocean water activity concentrations, and would result in a maximum dose of 

110−8rem to any organ, based on a full year of ingestion of 2 L d

−1

. This dose is much lower 

than the dose criterion in the National Primary Drinking Water Standards for beta and photon 

emitters of 4 mrem y

−1

(USEPA, 2017b). Likewise, the Pu-239/240 activity concentrations in 

both ocean water and distilled water are well below the Maximum Contaminant Level of 
136

15 pCi L

−1

 (15,000 fCi L

−1

) for alpha particle radiation (USEPA, 2017b). Therefore, ingestion of 

drinking water is not considered to be a significant pathway for ECUP participants and any 

related internal dose would be subsumed within applied upper-bound dose uncertainties. 

7.5 Puncture Wounds and Cuts 

No reports of this potential internal exposure pathway have been located for any ECUP 

participants. Therefore, assessment of this potential pathway in the future should be handled on a 

case-by-case basis, using relevant guidance and recommendations (e.g., NCRP, 2006). 

7.6 Uncertainties and Upper-bound Internal Doses 

Sources of uncertainty in estimating internal doses to veterans who participated in ECUP 

are similar to those identified in other radiation dose assessments developed by DTRA (DTRA, 

2017; Dunavant et al., 2017). Similar to uncertainties in external doses discussed in Section 6.4, 

sources of uncertainties in internal doses are generally attributed to, among others, imperfection 

in measuring instruments, spatial and temporal distributions, procedural errors, and data 

recording and processing errors. Additional sources of uncertainties in internal doses include 

human physiological characteristics reflected in internal dose estimation parameters such as 

breathing rates, composition of radioactive material, and radionuclide dose coefficients. 

Following the procedures used for the NTPR Program dose assessments, an uncertainty 

factor of 10 can be assigned to each internal dose calculated for ECUP participants. The 

uncertainties of the internal dose are assumed to be correlated, i.e., the upper bounds of each 

component of the internal dose are summed to estimate the total upper-bound internal dose for 

either the committed effective dose or the organ dose as described in Appendix C. Given an 

uncertainty factor of 10 and a systematically high-sided calculated dose, the upper-bound internal 

dose is considered to exceed the 95th percentile dose if determined from a distribution of doses 

for individuals estimated from internal monitoring measurements (Weitz et al., 2009; NAS-NRC, 

2003). In addition, the uncertainty factor applied to high side internal dose estimates should 

account for relatively small doses that are less than a few percent of the overall internal dose, 

e.g., doses from potential occasional consumption of locally caught fish or local food, and 

incidental ingestion of water while swimming or diving. (DTRA, 2017, SM UA01) 
137

Section 8. 

Example Radiation Dose Assessment 

Results and Discussion 

This section describes example ECUP radiation exposure scenarios and presents 

estimated dose results. Dose parameter values and assumptions are provided in the example 

exposure scenarios to assist veterans in understanding how an individualized dose assessment 

might be conducted, in the event that personal radiation dosimetry monitoring data are not 

available or useable. As described in previous sections, the results are high-sided estimates of 

radiation doses for representative members of participant groups that performed similar tasks and 

activities during the cleanup project. The exposure scenarios are based on historical ECUP 

information, monitoring data described in other sections of this report, and other ECUP 

documentation. Default parameter values were selected to result in high-sided dose estimates. 

Estimated organ committed equivalent doses and whole-body committed effective doses 

are discussed for three example ECUP scenarios in this section (Sections 8.1, 8.2, and 8.3). The 

dose estimates for these example ECUP scenarios result in upper-bound estimates of the total 

organ dose for the highest exposed organ (bone surface) from 0.12 to 1.4 rem. These total organ 

doses are the sums of the external and internal committed organ equivalent doses (Section 1.4). 

The upper-bound estimates of the total effective doses range from 0.03 to 0.22 rem. These total 

effective doses are the sums of the external and internal committed effective doses. These doses 

should be considered bounding doses for ECUP participants who performed similar generic 

activities for each scenario. The highest of the example upper-bound total effective doses is less 

than the average (mean) dose to the U.S. population of 0.31 rem from ubiquitous background 

radiation, including radon (NCRP, 2009a), and is a factor of 10 lower than the occupational dose 

limits that were in place for ECUP workers, as discussed in Section 3 (USA, 1975). 

Dose estimates for an example scenario involving Air Force personnel assigned 

temporary duty on Enewetak Island in 1965 are described in Section 8.4. This non-ECUP 

scenario is included to demonstrate the use of the data in this report for scenarios occurring prior 

to the start of ECUP. A final example scenario (Section 0) describes calculated skin doses for a 

hypothetical ECUP participant working on two contaminated islands. 

8.1 Example Scenario #1: Soil Cleanup Personnel 

Soil cleanup tasks were judged the most significant ECUP activities with regard to 

potential doses because of the constant exposure to contaminated soil and the disruption, 

suspension, and possible inhalation of contaminated soil and dust. This example of a soil cleanup 

scenario involves an operator of heavy earthmoving equipment, e.g., bulldozers or front-end 

loaders, who participated in brush removal and soil removal activities. The heavy-equipment 

operator is assumed to have excised and loaded soil from Boken and Runit, per the schedule 

shown in Table 50, and is assumed to have worked on Runit during the entire two-month period 

of soil removal from that island during June–July, 1979 (DOE, 1982a). In addition, the operator 

is assumed to have cleared vegetation, and excised and loaded soil, from Boken, which is the 

island with the highest average soil concentration of TRU other than Runit, for a total of 
138

4 months. This means that the scenario involves heavy equipment operation all day for every 

working day of an entire 6-month ECUP assignment. This hypothetical work schedule 

maximizes the estimated doses because reviews of controlled island access logs show that ECUP 

workers did not go to contaminated islands every workday and most worked on both 

contaminated and uncontaminated islands. 

Specific activities were selected from the listing of Tasks and Activities shown in 

Table 23. The activities included in this example scenario, including the islands where they were 

conducted and their durations, are shown in Table 50. 

Table 50. Task durations assumed for a maximized exposure scenario 

for a soil cleanup worker 

Scenario Tasks and 

Activities Island

Duration of Task

Hours per 

Day 

Days per 

Week Months 

Brush Removal 

Uproot bushes and vegetation Boken 8 1 4 

Soil removal and transport to Runit 

Remove and windrow soil Boken 4 5 4 

Load soil on dump trucks Boken 4 5 4 

Runit soil removal and transport to Cactus dome 

Remove and windrow soil Runit 4 6 2 

Load soil on dump trucks Runit 4 6 2 

External and internal doses were estimated using the exposure pathways indicated in 

Table 23 and the equations in Appendix C. The island-average exposure rates of 80 μR h

−1

 and 

33 μR h

−1

 were used for Boken and Runit, respectively. A value of 1.0 was assumed for the 

fraction of time exposed to the source for external and internal dose estimates for this example 

scenario. This factor accounts for the fraction of time during a workday that an ECUP worker 

was actually near the exposure sources. Data were not available to estimate the fraction of time 

exposed, and there is no feedback from a veteran for this hypothetical scenario. So in such a 

case, the conservative default value of 1.0 was used. 

Based on the above parameter values used for this example scenario, the external dose 

calculated for personnel who performed the duty activities described above is 0.056 rem. The 

high-sidedness of this estimated dose can be confirmed by comparing it to the dosimetry results 

shown in Table 20. An external dose estimate for assumed residence on Lojwa is also included 

for this example scenario. Based on an average exposure rate of 5 μR h

−1

, and 9 h d−1 spent 

inside a tent that is assumed to provide a protection factor of 1.5, the external dose from 

exposure to Lojwa ground soil for 6 months is estimated to be 0.008 rem. Therefore, the total 

external dose for this example scenario is 0.064 rem. Applying an uncertainty factor of 3 as 

described in Section 6.4 results in an upper-bound external dose of 0.2 rem. 

For the inhalation exposure pathway, the calculated airborne contaminated soil 

concentrations are based on mass loading values of 560 μg m−3 for soil removal, windrowing, 

and loading/unloading activities, and 300 μg m−3 for brush removal (Oztunali, 1981). These mass 
139

loading values correspond to measured or calculated values found in the literature for close 

proximity to bulldozing and agricultural tillage, respectively. An enhancement factor of 3, as 

described in Section 7.1 and Appendix E, was also assumed (Shinn et al., 1994). The use of these 

mass loading values and the enhancement factor resulted in calculated average air concentrations 

of approximately 1 percent of the ECUP MPC value of 27 pCi m−3 for Pu-239/240 for the 

example work on Boken, and approximately 4 percent of the MPC value for the example work 

on Runit. This suggests that the calculated hypothetical air concentrations are high-sided because 

in reality only 4 percent of the more than 5,000 air filters analyzed during ECUP showed air 

concentrations greater than 1 percent of the MPC (DNA, 1981). 

Assumptions for respiratory protection factors are based on documented ECUP 

procedures such as EAI 5707 “Personnel Protection Levels.” A value of 50 for a half facepiece, 

positive pressure respirator was assumed in this example scenario for all activities on Boken and 

Runit assuming personnel protection levels of Level IIIA or IIIB. Based on the controlled island 

access logs, workers were actually often required to wear Level III protective clothing when 

conducting cleanup work on Boken and Runit. Respiratory protection factors for the respirators 

used during ECUP are as high as 1,000 for full-face positive pressure respirators prescribed for 

protection Level III and Level IV (Appendix F). Therefore, the value of 50 is conservative 

because it results in high-sided doses (DNA, 1981). 

Using the parameter values in Table 43, the highest estimated internal organ dose from 

inhalation of airborne contaminated soil on these islands is 0.083 rem for bone surface. Other 

calculated inhalation organ doses resulting from soil handling are less than 0.02 rem. The 

estimated effective dose from inhalation on the two contaminated islands is approximately 

0.003 rem. Doses due to inhalation of suspended soil and incidental ingestion of soil and dust 

were calculated for the residence time on Lojwa. A mass loading value of 100 μg m−3 was 

assumed for Lojwa. The internal dose to bone surface from residing on Lojwa is 0.008 rem. The 

total internal dose for this scenario for the highest organ dose (bone surface) is therefore 

0.091 rem. The effective dose due to intakes via inhalation and incidental ingestion during soilhandling work and while on Lojwa is 0.003 rem. Applying an uncertainty factor of 10 to the 

internal doses, as described in Section 7.6, results in an upper-bound internal bone surface dose 

of 0.91 rem and an upper-bound internal effective dose of 0.029 rem. 

8.2 Example Scenario #2: Debris Cleanup 

Debris cleanup tasks during ECUP presented the potential for external and internal 

exposures. This example scenario involves a generic debris cleanup worker, for example an 

operator of heavy equipment such as a crane with clamshell and winches, who participated in 

debris collection and loading on trucks and other transport vehicles. 

8.2.1. External Dose Assessment—Debris Cleanup Scenario 

The primary source of external radiation exposure during debris cleanup was exposure to 

undisturbed contaminated soil during onshore collection, removal, and transport of noncontaminated and contaminated debris. Most debris cleanup activities involved noncontaminated debris, because approximately 98 percent of the volume of debris cleaned up was 

not contaminated (DNA, 1981). Exposure to “red” and “yellow” debris also was a source of 

potential external exposure. The primary source of internal radiation exposure during debris 

cleanup was due to suspended contaminated soil. 
140

Doses for individuals conducting debris cleanup activities were generically estimated 

using high-sided assumptions as shown in Table 51. For external doses, exposure rates are based 

on the island-average exposure rates as described in Section 6.2.2. An average exposure rate 

from contaminated soil and debris was estimated by averaging the exposure rates for the 

21 northern islands from which any debris was removed (DNA, 1981). This was derived by 

weighting the exposure rates by the fractional volume of total debris removed from each of the 

northern debris-removal islands, with the assumption that the amount of debris removed is 

proportional to time spent on the island. Assuming that the maximum time of 8 h d−1 and 

6 d wk−1 was spent on these islands for a 6-month period resulted in an external dose of 

0.031 rem. Adding the external dose of 0.008 rem for 6-months residence on Lojwa, discussed in 

the first example scenario (Section 8.1), resulted in a total external dose of 0.039 rem and an 

upper-bound external dose of 0.12 rem. 

Table 51. Exposure parameter values and assumptions for estimating external dose 

in the debris-handling example scenario 

Parameter Value Rationale/Reference/Comment

Exposure rate from 

undisturbed soil on 

debris-removal islands 

35 μR h

−1

Weighted average for 21 

northern islands that had debris 

removed 

Work schedule 

26 wk 

6 d wk−1

8 h d−1

(DNA, 1981) 

Fraction of time 

exposed to source 

‒ 1.0 (external dose) 

‒ 0.25 (internal dose) 

‒ Default 

‒ Analyst judgment 

Time spent outdoors 

on Lojwa 

5 h d−1 for 6 d wk−1

15 h d−1 for 1 d wk−1 See Section 6 

Time spent in a tent on 

Lojwa 9 h d−1

 for 7 d wk−1

Default schedule is 8 h sleeping 

and 1 h eating meals indoors 

every day 

Protection factor for a 

tent 

1.5 

High-sided assumption that 

resulted in a higher dose than 

assuming a metal building 

(DTRA, 2017, SM ED02) 

Film badge conversion 

factor 0.7 (standing upright on ground) (DTRA, 2017, SM ED02) 

8.2.2. Internal Dose Assessment—Debris Cleanup Scenario 

A high-sided internal dose was estimated using weighted average soil concentrations of 

all radionuclides of concern, derived by weighting the individual island-average soil activity 

concentrations by the fractional volume of total debris removed from each of the northern debrisremoval islands as was done for the external exposure rate estimate above. Suspension of 

contaminated soil due to debris removal and handling, e.g., removing buried debris and dragging 

across ground surfaces, was high sided by using a soil mass loading of 300 μg m−3 corresponding 
141

to agricultural tilling (Oztunali et al., 1981), with an enhancement factor of 3 (Shinn et al., 1994). 

No respirator other than a dust mask was assumed (protection factor = 1). A fraction of time of 

exposure of 0.25 was assumed for the fraction of time the veteran was exposed to the airborne 

source, based on the assumption that soil was suspended by dragging or digging up debris for 

25 percent of each workday. The remainder of each workday is assumed to have been spent 

loading debris onto trucks or other activities that did not generate airborne soil. The parameters 

discussed above are listed in Table 52. These assumptions resulted in a maximum internal organ 

dose of 0.122 rem to bone surface due to inhalation of suspended soil during debris collection 

and handling. The internal dose to bone surface from inhalation of suspended soil and incidental 

ingestion of soil and dust while residing on Lojwa is 0.008 rem, and thus the total internal dose 

for bone surface for this example scenario is 0.130 rem. The upper bound internal dose to bone 

surface is 1.3 rem. The upper bound internal dose to all other organs is less than 0.3 rem. The 

internal effective dose due to intakes from inhalation during debris-handling work and inhalation 

and incidental ingestion on Lojwa is 0.004 rem, and the upper-bound total internal effective dose 

is 0.039 rem for this example scenario. 

8.3 Example Scenario #3: Navy Boat Transportation Team 

As compared to the other example scenarios that use default assumptions, this scenario is 

a much closer representation of the actual scenario for an ECUP participant. It involves a 

hypothetical Navy veteran serving at Enewetak during the period May–November, 1978, as a 

crewmember of one of the boats of the Boat Transportation Team. It is assumed that the veteran 

was assigned to one of the landing craft utility (LCU) boats that was modified to transport bulk 

soil to Runit. The LCU was this individual’s assigned duty station. The residence location in this 

scenario is assumed the forward camp on Lojwa. 

Based on available records, it is assumed that during May and June, 1978, the LCU and 

its assigned crew were used for general inter-island transport of passengers, Army vehicles and 

troops, supplies, and equipment between Enewetak, other southern islands, Runit and Lojwa. 

Starting on July 10, the LCU was used for transporting bulk-contaminated soil to Runit. During 

the period from July 10 until the end of this example scenario on November 19, 1978, the boat 

hauled bulk soil primarily from Enjebi to Runit. 

There are personal monitoring data used for this example, therefore the dose assessment 

is more detailed than that for other example scenarios. Descriptions of the external and internal 

dose estimates are provided in the following subsections. 
142

Table 52. Exposure parameter values and assumptions for estimating internal dose 

in the debris-handling example scenario 

Parameter Value Rationale/Reference/Comment

Mass loading factor for 

debris handling 300 μg m−3

This value corresponds to 

agricultural tilling (Oztunali et 

al., 1981); see Appendix E

Enhancement factor 3 See Appendix E

Resuspension factor on 

Lojwa 2  10−8

 m−1 Default value 

Lojwa soil density 1.5 g cm−3 Default value 

Depth of soil available 

for suspension 1 cm Default value 

Breathing rate 1.2 m3 h−1(DTRA, 2017, SM ID01) 

Respiratory protection 

factor 1.0 No respiratory protection is assumed 

Fraction of time 

exposed to source 0.25 Analyst judgment 

Soil concentrations in 

undisturbed soil on 

northern islands 

Radionuclide 

Activity 

Concentration Debris was removed from 21 

northern islands (DNA, 1981); 

these soil concentrations are 

weighted averages for the 21 

islands. 

Sr-90 39.4 pCi g−1

Cs-137 13.9 pCi g−1

Pu-239 12.8 pCi g−1

Am-241 3.28 pCi g−1

Co-60 1.70 pCi g−1

Soil concentrations in 

undisturbed soil on 

Lojwa 

Radionuclide 

Activity 

Concentration 

Table 6

Sr-90 8.20 pCi g−1

Cs-137 2.60 pCi g−1

Pu-239 1.80 pCi g−1

Am-241 1.20 pCi g−1

Co-60 0.31 pCi g−1

8.3.1. External Dose Assessment—Boat Transportation Team 

It is assumed that individual dosimetry is available for this dose assessment from a 

DD Form 1141, DA Form 3484, and records in the ADC database. It is assumed that for the 

6-month period from May 22 to November 19, 1978, the dosimetry record consisted of three 

administrative doses of 0 rem each, and three film badge doses of 0.0, 0.001, and 0.005 rem as 

shown in Table 53. 

Using the external dose methodology guidance outlined in Section 6.1 and DTRA (2019), 

the administrative doses and the three sub-MDL film badge readings are replaced with 

reconstructed doses as described below. Major assumptions are listed in Table 54, and additional 

details are provided below. 
143

Table 53. Dosimetry record for the Navy Boat Transportation example scenario 

Period of Exposure 

(1978) Type of Record Dose 

(rem) Comment 

From To 

May 22 June 18 Film Badge 0.005 

Dose is less than MDL. No 

work with contaminated 

soil during the period. 

June 18 July 15 Administrative 

Dose 0.000 Bulk soil haul starting July 10 

July16 August 20 Film Badge 0.000 

Dose is less than MDL. 

Bulk soil haul during 

period 

August 21 September 18 Film Badge 0.001 

Dose is less than MDL. 

Bulk soil haul during 

period 

September 18 October 15 Administrative 

Dose 0.000 Bulk soil haul during period 

October 15 November 19 Administrative 

Dose 0.000 Bulk soil haul during period 

Based on available records, the LCU crewmembers did not enter any controlled access 

areas prior to July 10, 1978. Starting on July 10, the LCU was used for transporting bulkcontaminated soil from Enjebi and Aomon to Runit. Bulk soil on the LCU during transport was 

the only source of external exposure to crewmembers during the workday. 

An LCU transporting contaminated soil was a Controlled Access area. FRST Operational 

Reports and Controlled Access log sheets that detailed the activities of the LCU were available 

for review. Based on these records, it is determined that the example LCU transported bulk soil 

to Runit on 79 days over the period July 10–November 19, 1978, with an average transit time of 

1.74 h. The log sheets showed that on some of these days, two trips were accomplished. Given 

this operational scenario, an estimated external dose of approximately 0.003 rem is obtained, 

based on a total of approximately 213 hours of over-water transport during the period. 

To estimate the hypothetical external dose from residing on Lojwa, the island-average 

external exposure rate of 5 μR h

−1

 was used, in addition to the outdoor and indoor times, and 

other applicable parameter values in Table 54. As a result, an external dose of 0.008 rem is 

estimated for exposure to Lojwa soil. The total reconstructed external dose for this scenario for 

time on the LCU and on Lojwa is 0.011 rem. Using an upper-bound uncertainty factor of 3 and 

the method described in Appendix C results in an upper-bound external dose of 0.028 rem. 
144

Table 54. Key external exposure parameter values and assumptions for the Boat 

Transportation Team example scenario 

Parameter Value Rationale/Reference/Comment

Exposure rate from 

undisturbed soil on 

Lojwa 

5 μR h

−1 Table 4

Exposure rate on 

LCU from bulk soil 

excised from Enjebi 

13 μR h

−1

Estimated using exposure rate of 

40 μR h

−1

 for undisturbed Enjebi 

soil, and average distance of 3 m 

from bulk soil 

Work schedule 

10 h d−1

6 d wk−1

 (for 26 wk) 

(DNA, 1981) 

Average transit time 

from Enjebi to 

Runit 

1.74 h trip−1 Based on review of applicable 

FRST Operational Reports 

Weekly average 

frequency of trips 

transporting bulk 

soil 

6.5 trips wk−1

(for 19 wk) 

Based on review of applicable 

FRST Operational Reports 

Fraction of time 

exposed to source 1.0 

Veteran is exposed to bulk soil 

on LCU during all transit time 

between Enjebi and Runit 

Time spent outdoors 

on Lojwa 

5 h d−1 for 6 d wk−1

15 h d−1 for 1 d wk−1 Default schedule 

Time spent in a tent 

on Lojwa 9 h d−1

 for 7 d wk−1

Default schedule is 8 h d−1 of 

sleeping and 1 h d−1 for meals 

indoors every day 

Protection factor for 

a tent 1.5 

High-sided assumption that 

resulted in a higher dose than 

assuming a metal building 

(DTRA, 2017, SM ED02) 

Film badge 

conversion factor 

1.0 (facing bulk soil on LCU) 

0.7 (standing upright on the ground 

on Lojwa) 

(DTRA, 2017, SM ED02) 

8.3.2. Internal Dose Assessment—Boat Transportation Team 

The veteran may have been exposed to airborne TRU and other radionuclides during soil 

loading and unloading operations on his LCU. Because the soil was wetted down and/or covered 

with a tarp during actual transit operations (FRST Operational Reports; EAI No. 5708.1), 

inhalation of suspended soil was possible only during the periods of soil loading and unloading. 

Based on a review of applicable Controlled Access log sheets and FRST Operational Reports for 

the LCU, the time for loading and unloading soil totaled approximately 210 h over the 79 days of 

bulk soil haul by the LCU. The FRST Operational Reports confirm that Level IIIA respiratory 
145

protection was used by the LCU crewmembers during loading and unloading operations. Based 

on measured air concentrations from air samplers on the LCU as documented in SITREPs, and 

the other parameter values and assumptions shown in Table 55, the maximum internal organ 

dose from inhalation of suspended soil during soil loading and unloading operations is 0.001 rem 

for bone surface. 

A dose from inhalation of suspended soil on Lojwa was also estimated for 182 days of 

residence on the island for this scenario. Based on conservative assumptions shown in Table 55, 

the calculated effective dose from inhalation is less than 0.001 rem, and the highest estimated 

organ dose from inhalation is 0.007 rem for bone surface. The next highest estimated organ dose 

is 0.001 rem for liver. 

An internal dose from incidental ingestion of soil and dust on Lojwa was also estimated 

for the entire duration of the example scenario. Based on the parameter values and assumptions 

in Table 55, the effective dose and all organ doses from this exposure pathway are less than 

0.001 rem. 

The total internal organ doses for this scenario range from less than 0.001 rem for most 

organs, up to 0.010 rem for bone surface. The next highest estimated total organ dose is 

0.002 rem for liver. The total effective dose for this scenario is less than 0.001 rem. Applying an 

uncertainty factor of 10 to the total internal doses results in upper-bound internal organ doses 

ranging from less than 0.001 rem for many organs, up to 0.10 rem for bone surface, and an 

upper-bound effective dose of 0.003 rem. 

8.4 Example Scenario #4: Air Force Duty on Enewetak in 1965 

This example scenario addresses Air Force personnel that were assigned Temporary Duty 

at Enewetak in 1965. Although these individuals are not ECUP participants, this example 

demonstrates that some of the data collected in the 1972 survey and used for assessment of 

ECUP dose estimates can also be used to assess potential doses to the personnel working at the 

atoll in the period after nuclear testing had ended and before the start of ECUP (1963–1977). 

During this period, the majority of U.S. military activities at the atoll were limited to the 

main atoll airfield and a Long-Range Navigation (LORAN) station, both located on Enewetak 

Island. In addition, personnel on transient ships and transport aircraft spent short periods of time 

at the atoll during ECUP to deliver supplies and equipment, perform maintenance and repairs, 

pick up retrograde cargo, etc. This example scenario involves aircraft maintenance personnel 

assigned short-term assignments at Enewetak Island in 1965 to support Air Force aircraft 

operations. These individuals included, for example, aircraft maintenance technicians and 

aircraft mechanics. These job assignments were limited to work conducted on Enewetak Island, 

and did not require access or travel to any other islands in the atoll. 
146

Table 55. Key internal exposure parameter values and assumptions 

for the Boat Transportation Team example scenario 

Parameter Value Rationale/Reference/Comment 

Breathing rate 1.2 m3 h−1(DTRA 2017, SM ID01) 

Average air 

concentration of 

Pu-239/240 on 

LCU during 

loading and 

unloading 

0.001–0.065 pCi m−3

Wtd ave. = 0.032 pCi m−3

Based on the detection of alpha radiation on 

53 out of a total of 252 filters during the 

bulk-hauling period. The averages are based 

on the maximum measured air 

concentration measured each week, 

averaged over each weekly period 

(SITREPs). 

Average time of 

LCU loading and 

unloading 

operations 

1.7 h trip−1 Based on review of FRST Operational 

Reports for LCU during bulk soil hauling 

Weekly average 

frequency of trips 

transporting bulk 

soil 

6.5 trips wk−1

(for 19 wk) 

Based on review of applicable FRST 

Operational Reports 

Respiratory 

Protection factor on 

LCU during 

loading and 

unloading 

50 

Use of Level IIIA PPE (full-face or halfface positive pressure respirator) during soil 

loading/unloading operations (EAI 5708.1; 

FCRR SOP 608.05; FRST Operational 

Reports; and Controlled Access logs). A 

value of 50 is conservatively assumed. 

Fraction of time 

exposed to source 1.0 Veteran is exposed to suspended soil on LCU during all loading and unloading time 

Airborne mass 

loading of Lojwa 

soil 

100 g m−3 See Section 7 and Appendix E

Enhancement factor 3 See Appendix E

Incidental soil and 

dust ingestion rate 0.05 g d−1 Central tendency value for adults in rural setting (USEPA, 2017a) 

Number of days of 

participation 

182 d 

(26 wk) 

Based on assumed arrival and departure 

dates 

Dose coefficients Radionuclide-, organ-, and 

pathway-specific 

Worker dose coefficients for inhalation and 

ingestion from ICRP (2011); see 

Appendix C

Soil concentrations 

in undisturbed soil 

on Lojwa 

Radionuclide Activity 

Concentration 

Table 6

Sr-90 8.2 pCi g−1

Cs-137 2.6 pCi g−1

Pu-239 1.8 pCi g−1

Am-241 1.2 pCi g−1

Co-60 0.31pCi g−1
147

Very low levels of contaminants were detected in the soil at Enewetak Island in 1972. 

There was no radiologically contaminated debris, and there was no detectable airborne 

radioactive material (DNA, 1981; DOE, 1982b). In order to estimate potential exposures in 1965, 

this assessment uses the 1972 soil survey results, adjusted for radioactive decay during the time 

between the survey and the exposure scenario, which provide the basis for external and internal 

doses for personnel temporarily at the island in 1965. The potential exposure pathways are direct 

external exposure to contaminants in the soil, inhalation of airborne radionuclides in suspended 

soil, and incidental ingestion of soil and dust. External and internal exposures to lagoon and 

ocean water and sediments have been shown to be insignificant in Sections 6 and 7, and any 

small doses would be subsumed within applied upper-bound dose uncertainty factors. 

8.4.1. External Dose Assessment for Air Force Personnel in 1965 

The main potential external exposure pathway for this scenario is direct external exposure 

to gamma-emitting radionuclides in the soil. The 1972 island-average external exposure rate on 

Enewetak Island was primarily due to two radionuclides: 0.14 μR h

−1

 from Cs-137 and 

0.12 μR h

−1

 from Co-60 (AEC, 1973a). The 1965 external exposure rate would have been higher 

than in 1972 because 1965 is closer to the times of testing and deposition of atmospheric testing 

fallout. This means there was less time for infiltration of fallout into soil and runoff into the 

lagoon or ocean (i.e., environmental weathering), and less time for radioactive decay of shorterlived fission products, and consequently higher soil activity concentrations. 

The effects of incorporating environmental weathering into the calculated 1965 exposure 

rates are estimated to result in soil exposure rates that are approximately 5 percent higher than 

exposure rates that do not include weathering effects (Till and Meyer, 1983). Although this 

minimal impact environmental weathering is not included for this 1965 example, the small 

increase in estimated dose is accounted for by the use of the upper-bound uncertainty factor (see 

below). 

As discussed in Section 3.1, fission products such as Sb-125 and Eu-155 are not included 

in ECUP radiological dose assessments for the southern islands of Enewetak Atoll because of 

their minimal contributions to total doses. However, the fractional contributions of Sb-125 and 

Eu-155 to the total soil exposure rate would have been higher in 1965 than in 1972 due to their 

relatively short half-lives, and thus they are included in this example. Measurements of 1972 

survey soil exposure rates for Sb-125 and Eu-155 were not located. The contributions of these 

radionuclides to the 1972 exposure rate on Enewetak Island were estimated by first determining 

approximate soil concentrations using ratios to the Cs-137 soil concentration (AEC, 1973a). 

Exposure rates from these soil concentrations were then estimated using dose coefficients for soil 

contaminated to a depth of 15 cm (USEPA, 1993). Using these calculated values and the 

exposure rates for Cs-137 and Co-60 above, the calculated 1972 exposure rate on Enewetak 

Island is 0.27 μR h

−1

. Using the individual radionuclide exposure rates and radioactive decay 

constants shown in Table 56, an estimated total 1965 exposure rate on Enewetak Island was 

calculated using radioactive decay principles as shown in Equation 8-1. 

 = , × 







(8-1)
148

where 

E65Tot = Total 1965 island-average exposure rate on Enewetak Island (μR h

−1

) 

E72,i = 1972 island-average exposure rate on Enewetak Island of radionuclide i

(μR h

−1

) 

λi = Radioactive decay constant for radionuclide i (y−1) 

t = Time from the 1965 veteran arrival date to 1972 survey date (y) 

Table 56. External dose parameter values and assumptions for 

the 1965 example scenario 

Parameter Value Rationale/Reference/Comment 

Radioactive decay 

constants 

Radionuclide 

Decay 

Constant 

(y−1) Decay constants were calculated as 

ln(2) / half life 

Half-lives obtained from NNDC 

(2019) 

Sr-90 0.0240 

Cs-137 0.0230 

Pu-239 0.000029

Am-241 0.00160 

Co-60 0.132 

Sb-125 0.251 

Eu-155 0.146 

Average exposure rates 

on Enewetak Island 

Nov 8, 1972: 0.27 μR h

−1

Jul 1, 1965: 0.53 μR h

−1

The 1965 exposure rate was 

calculated from the 1972 rate as 

described in the text. 

Duration of temporary 

duty on Enewetak Island 6 months 

This is a high-sided assumption 

because duty assignments were likely 

3–6 months. 

Length of workday 10 h d−1 There are 6 workdays each week. 

Average daily time 

spent outdoors on 

Enewetak Island 

Outdoor worker 

Indoor worker 

15 h d−1

6.4 h d−1 

All non-work time other than sleeping 

and eating is assumed outdoors. 

Daily time spent in a 

tent on Enewetak Island 

(sleeping and eating) 

9 h d−1 Default schedule is 8 h d−1

 of sleeping 

and 1 h d−1 eating indoors every day. 

Protection factor for a 

tent 1.5 (DTRA, 2017, SM ED02) 

Film badge conversion 

factor 

0.7 (standing upright on 

ground) (DTRA, 2017, SM ED02) 

Using Equation 8-1 and the four radionuclides discussed above, the total 1965 islandaverage exposure rate on Enewetak Island is calculated to be 0.53 μR h

−1

, based on a radiological 

survey date of November 8, 1972 (AEC, 1973a) and a veteran arrival date of July 1, 1965 (t = 
149

7.4 y). This arrival date was chosen because it is the mid-point of 1965. The calculated 1965 

exposure rate is approximately 10 percent higher than what would be calculated without Sb-125 

and Eu-155. Using the methods described in Appendix C with this exposure rate and the other 

parameter values in Table 56 results in an external dose of approximately 0.0015 rem for this 

scenario. Applying an uncertainty factor of 3 (Section 6.4) results in an upper-bound external 

dose of 0.005 rem. 

8.4.2. Internal Dose Assessment for Air Force Personnel in 1965 

The only potential internal exposure pathways for this scenario are inhalation of airborne 

radionuclides in suspended soil, and incidental ingestion of soil and dust. Mean soil 

concentrations of Sr-90, Cs-137, Pu-239/240, Am-241, and Co-60 in 1972 are shown in Table 6. 

The 1972 soil activity concentrations of Sb-125 and Eu-155 have been estimated, based on 

median activity ratios to the Cs-137 soil concentration on the northern islands (AEC, 1973a). The 

resulting soil activity concentrations on Enewetak Island are 0.018 pCi g−1 and 0.050 pCi g−1 for 

Sb-125 and Eu-155, respectively. Similar to the adjustment to external exposure rate above, the 

soil activity concentrations for 1965 were estimated from the 1972 soil concentrations using 

radioactive decay principles as shown in Equation 8-2. 

 = × 



(8-2)

where 

 = 1965 island-average soil activity concentration of radionuclide i on Enewetak 

Island (pCi g−1) 

 = 1972 island-average soil activity concentration of radionuclide i on Enewetak 

Island (pCi g−1) 

 = Radioactive decay constant for radionuclide i (y−1

) 

t = Time from the 1965 veteran arrival date to 1972 survey date (y) 

Using the above equation for each radionuclide, the calculated 1965 island-average soil 

activity concentrations on Enewetak Island were estimated and are shown in Table 57. Other 

parameter values and assumptions for the 1965 example scenario are also shown in Table 57. 

The resuspension factor used is the geometric mean of the calculated downwind values shown in 

Appendix E, and is equivalent to a mass loading value of 100 μg m−3. 

Using the methods described in Appendix C and the values in Table 57, inhalation and 

incidental ingestion doses were calculated resulting in a total committed effective dose of less 

than 0.001 rem for this scenario. A maximum internal organ dose of approximately 0.0008 rem 

was calculated for bone surface. Applying an uncertainty factor of 10 to the total internal doses 

(Section 7.6) results in a maximum internal upper-bound organ dose of 0.008 rem for bone 

surface and an upper-bound committed effective dose of less than 0.001 rem. Upper-bound 

internal doses for other organs ranged from much less than 0.001 rem calculated for several 

organs to 0.002 rem for liver. 
150

Table 57. Internal dose parameter values and assumptions for the 1965 example scenario 

Parameter Value Rationale/Reference/Comment 

Duration of temporary 

duty on Enewetak 

Island 

6 months 

This is a high-sided default 

assumption because duty assignments 

were likely 3–6 months. 

Breathing rate 1.2 m3 h−1 Default value (DTRA, 2017, 

SM ID01) 

Resuspension factor 2  10−8 m−1

All suspended particles are assumed 

to be respirable. See text and 

Appendix E for discussion. 

Depth of soil 

available for 

suspension 

1 cm (DTRA, 2017, SM ID01; 

AEC, 1973a) 

Soil density 1.5 g cm−3(AEC, 1973a; DOE, 1982a) 

Respiratory protection 

factor 1.0 No respiratory protection was used. 

Incidental soil and 

dust ingestion rate 0.050 g d−1 Central tendency value for adults in rural setting (USEPA, 2017a) 

Average daily time 

spent outdoors on 

Enewetak Island 

Outdoor worker

Indoor worker

15 h d−1

6.4 h d−1

All non-work time other than 

sleeping (8 h d−1) and eating (1 h d−1) 

is spent outdoors. 

Fraction of outdoor 

time exposed to 

source 

1.0 Fraction of a workday that an 

individual is exposed to the source 

Dose coefficients Radionuclide-, organ-, and 

pathway-specific 

Inhalation and ingestion worker dose 

coefficients from ICRP (2011); see 

Appendix C

1965 soil activity 

concentrations on 

Enewetak Island 

Radionuclide

Activity 

Concentration

(pCi g−1) 

Calculated values for Enewetak 

Island are based on 1972 mean values 

in Table 6, except for Sb-125 and 

Eu-155, which are calculated as 

described in the text (Section 8.4.2). 

Sr-90 0.73 

Cs-137 0.30 

Pu-239/240 0.08 

Am-241 0.05 

Co-60 0.11 

Sb-125 0.11 

Eu-155 0.15 
151

8.5 Example Calculation for Skin Dose from Dermal Contamination and External 

Exposure 

This example involves a worker who is assumed to have spent seven weeks working 

eight hours per day on Kirunu (Clara). The dose assessment is for a skin cancer behind the left 

ear of the veteran. The example calculation presented below is based on the method described in 

Section 6.3.1. 

To estimate a high-sided skin dose from dermal contamination for this scenario, it is 

assumed that the total amount of radioactive material accumulated over 8 hours was deposited 

and distributed uniformly in its entirety at the beginning of the workday and remained constant 

until completely removed by showering four hours after the workday ended. This results in a 

fixed skin dose rate for 12 hours over which the radiation dose is calculated. Parameter values 

used for the dose assessment are shown in Table 58. 

Table 58. Parameter values used for the example skin dose calculation 

Parameter Value Rationale/Reference/Comment

Duration of assignment 49 d Assumed for this example 

Duration of workday 8 h Default value for time on work island 

(Table 32) 

Work schedule 6 d wk-1 (DNA, 1981) 

Duration of exposure to dermal 

contamination 12 h Default value (Table 32) 

Activity concentrations of 

undisturbed soil 

Radionuclidespecific Table 6

Soil density 1.5 g cm−3 Default value (Table 32) 

Depth of soil available for 

suspension 1 cm Default value (Table 32) 

Resuspension factor 2  10−8 m−1 Default value (Appendix E) 

Deposition velocity 3600 m h−1 Default value (Table 32) 

Interception and retention 

fraction 1.5 Table 36

Fraction of workday exposed 

to suspended soil 1 Default value 

Skin depth modification factor 

(SDMF) for beta-emitters 1.3 Table 34 (SDMF for face and neck) 

Dose coefficients for dermal 

contamination 

Radionuclidespecific Table 33 and Table 35

Beta-gamma dose ratio 0.18 Appendix L

Other modifying factors 1.0 No modifying factors 

To calculate the dermal contamination dose to the skin behind the ear, the soil loading of 

the skin and dermal activity concentrations are first determined using Equations C-14a and 

C-14b in Appendix C. Using the values specified above, the calculated soil loading is 
152

1.3 mg cm−2 at the end of an 8-hr workday. The calculated dermal activity concentrations are 

shown in Table 59. The values in Table 59 are the areal concentrations of dermal contamination 

that would be accumulated over an eight-hour workday with no accounting for removal. 

The high-sided daily dose for a 12-hour exposure from the dermal contamination from 

each radionuclide listed in Table 59 is shown in Table 60 (See Equation C-15 in Appendix C). 

Note that a SDMF of 1.3 was applied to the beta dose coefficients (see Table 58), and the alpha 

dose coefficients for the face were assumed to apply to the ear. Other modifying factors were 

assumed equal to 1.0. 

Table 59. Example dermal activity concentrations 

at Kirunu (Clara) for skin dose calculations 

Radionuclide Dermal Concentration 

(pCi cm−2) 

Co-60 8.29 × 10−3

Sr-90 1.29 × 10−1

Cs-137 4.59 × 10−2

Pu-239/240 4.10 × 10−2

Am-241 2.73 × 10−2

Table 60. Example skin doses for one 

12-hour exposure 

Radionuclide Skin Dose (rem) 

Co-60 4.96 × 10−7

Sr-90 2.41 × 10−5

Cs-137 4.07 × 10−6

Pu-239/240 3.15 × 10−3

Am-241 2.43 × 10−3

The total, high-sided skin dose from dermal contamination for one day of work, 12-hour 

exposure is 0.006 rem to the skin site behind the ear. Alpha emitters contribute the majority of 

this dose, and the doses from the beta emitters are insignificant. This worker spent seven weeks, 

six days per week, working under these conditions, and the total skin dose from dermal 

contamination accumulated on Kirunu for a skin site behind the ear is 0.235 rem. 

For estimating the skin dose from non-contact sources, the mean external gamma 

exposure rate on Kirunu was 42 μR h−1 at 1 meter above the ground. Note that the exposure time 

is eight hours because it is assumed that the external exposure stopped at the end of the workday. 
153

The total skin dose from external non-contact sources of radiation on Kirunu is estimated from 

Equation C-16 in Appendix C as 0.012 rem. 

The radiation doses to the skin calculated above for working for seven weeks on Kirunu 

are high-sided estimates, which means that they are biased high but are not upper-bound 

radiation doses. To ensure that these calculated doses are likely to exceed the 95th percentile, 

uncertainty factors (UF) are applied as discussed in Section 6.3.3. For the skin dose from dermal 

contamination, a UF of 10 is recommended, and the resulting upper-bound dermal contamination 

dose is 2.35 rem. For the non-contact skin dose, a UF of three is recommended, and the 

calculated upper-bound dose is 0.035 rem. The total estimated skin dose is 0.247 rem, and the 

total upper-bound skin dose for this example is the sum of the upper-bound doses from each 

exposure pathway, rounded to 2.4 rem. 

For an actual veteran dose assessment, an additional skin dose would be calculated and 

included for the veteran’s time spent on his residence island, presumably Lojwa. Because of the 

much lower soil activity concentrations and the external exposure rate on Lojwa as compared to 

Kirunu, the dose for his time on Lojwa would not add significantly to the total skin dose 

estimated above for Kirunu. 
154

Section 9. 

Guidelines for Individualized Radiation Dose Assessments 

This section includes guidelines that should be used to create detailed procedures for 

performing individualized radiation dose assessment for ECUP veterans. Such procedures should 

be consistent with standard operating procedures and methods employed in other DoD radiation 

dose assessment programs such as DTRA’s NTPR Program for non-presumptive cancers.13 

Veterans of the military services who participated in ECUP during the period 1977–1980 

constitute the target population for this technical basis document report. The various groups of 

the POI are described in Section 2.5. During project planning and implementation, individuals 

may have performed a multitude of activities while assigned duty at Enewetak Atoll. The 

potential sources of radiation and exposure pathways, described in Section 5, should constitute 

the basis for estimating doses to individuals who participated in identified project activities. In 

addition, for individualized dose assessments, it is important to collect veteran-specific 

information and data that can be used to adjust or complement the scenarios of exposures and 

assumptions identified in this report. Additional doses should be calculated for pathways that 

were not identified in this report, where needed. 

9.1 Collection of Veteran-Specific Information 

To perform an individualized dose assessment, it is necessary to determine the veteran’s 

participation in various project activities at various locations on the Enewetak Atoll. An ECUPspecific questionnaire should be used to collect veteran-provided input about his or her activities 

and scenarios of radiation exposure. A draft of the recommended questionnaire is included as 

Appendix I. 

Furthermore, all information related to the veteran that is available in the DTRA ECUP 

document collections and historical records should be obtained and added to the dose assessment 

case file as it is done in other DoD veteran radiation dose assessment programs. The veteran’s 

personnel and medical records from the National Personnel Records Center, St Louis, MO, 

should be obtained, reviewed, and added to the assessment file if not already included. In 

addition, the questionnaire should provide many opportunities for the veteran to add comments 

within the questionnaire or in enclosures and attachments. The veteran should also be invited to 

submit any documentation in his or her possession that contains information about their time at 

Enewetak Atoll during the ECUP period. 

9.2 Individualized Dose Assessment for ECUP Veterans 

Based on the veteran’s recollections and statements, and an analysis of relevant data and 

historical records, the veteran’s activities during ECUP and all possible sources of exposure to 

radiation and pathways should be identified. In as much as possible, the evaluation of exposure 

to radiation should be related to the pathways identified in this report. For each pathway 

 

13 Since the publication of the original version of this technical report, a standard operating procedure for ECUP 

participant dose assessments was developed and published by DTRA (DTRA, 2019). This section of this report 

describing the guidelines for SOP development is maintained in this revision for completeness. 
155

associated with documented or claimed activities, the supporting data presented in Section 4, 

Section 6 and Section 7 of this report should be used to estimate all relevant external, internal, 

and skin doses. In addition, information given by a claimant, whether in the questionnaire or in 

separate communications, should be taken into account to assume benefit of the doubt to the 

veteran and to assure consistency with VA (2017) requirements. 

Members of ECUP teams who were assigned to radiologically controlled areas were 

monitored for radiation exposure using film badges, pocket dosimeters, TLDs, bioassays, and 

possibly other radiation measuring devices. Therefore, as specified in Section 6, doses for some 

of the exposure pathways would be based on an individual’s dosimetry records. Doses for 

periods not reflected in the individual’s dosimetry records would be estimated using the dose 

assessment methods described in this report. 

Exposure pathways other than those identified in this report might need to be added for 

some ECUP participants. If such additional sources of exposure and relevant pathways are 

identified, the corresponding doses should be calculated using standard dose reconstruction 

techniques such as those used in the NTPR Program (DTRA, 2017) or equivalent approved 

standard procedures and methods. The doses from the additional exposure pathways should then 

be incorporated in the calculation of the upper-bound total external and total internal doses using 

the methods described in Appendix C. 
156

Section 10. 

Summary and Conclusions 

This technical report has been prepared to assemble and characterize information on 

prevailing radiological conditions of the Enewetak Atoll in the late 1970s that is most relevant 

and useful in conducting radiation dose assessments for veterans who participated in the ECUP. 

It also lays out most pertinent dose estimation techniques that are based on accepted methods and 

procedures, which can be used to perform such assessments. 

Beginning in late 2016, DTRA directed a team of historians, health physicists, scientists, 

and other support personnel to develop a technical basis document to support radiation dose 

assessments and VA claim processing for ECUP veterans. The team reviewed a large collection 

of documents and records pertaining to ECUP covering periods from the early 1970s to early 

1980s. The goal was to evaluate and compile information relevant to the potential exposure to 

radiation of DoD personnel who participated in the cleanup project during 1977–1980. The 

majority of the historical records were maintained in a storage facility at DTRIAC in 

Albuquerque, New Mexico. Over 150 boxes of documentation were moved from storage at 

DTRIAC to Northern Virginia where the contents were digitized by DTRA. This ECUP 

document collection can be accessed and electronically searched to retrieve information about 

ECUP operations, reports, memos, letters, monitoring data, etc., to respond to requests for 

information from a variety of public and private sources. In addition, this digital repository can 

be used to retrieve veteran-specific information to support DTRA radiation dose assessments for 

VA claim processing. 

Planning for the cleanup of Enewetak Atoll began in the early 1970s when the U.S. 

government decided to return the atoll to the Trust Territory of the Pacific Islands. In order for 

the Enewetak people to safely return to and live at Enewetak Atoll, it was necessary to 

characterize and clean up residual radiation from the atmospheric nuclear testing that was 

conducted during the 1940s and 1950s in the Pacific Proving Grounds. The majority of the 

islands contaminated with radioactive material remaining from the testing era were in the 

northern part of the atoll as can be seen in the radiological survey results reported in Section 4.

The southern islands contained non-contaminated debris and abandoned facilities, and radiation 

levels on these islands were generally below detection limits. To ensure worker safety, extensive 

radiation protection and control measures were instituted and access to contaminated islands was 

restricted. Access of each individual entering a contaminated area was logged on a daily basis. 

This was the case for small boats and other watercrafts used to transport contaminated soil and 

debris. Prior to entering a controlled area, individuals were provided with personal protection 

equipment at the level necessary for the safe conduct of all required work at each location where 

they worked. Individuals who worked on the contaminated islands were issued radiation 

dosimeters on a monthly basis. 

Participants in the ECUP were potentially exposed to external radiation from the 

surrounding environment and to internal radiation from the intake of radioactive materials by 

inhalation and ingestion, or through wounds. Environmental media potentially contaminated with 

radioactive material that could be the source of radiation exposure included principally soil and 
157

dust, but also debris, equipment, lagoon water, sediments, food, and drinking water. To 

characterize the scenarios of potential exposure of ECUP personnel, specific coherent project 

tasks have been identified and categorized into nine major project components described in 

Section 5. Methods to estimate radiation doses for various exposure pathways are discussed in 

Section 6 and Section 7, and are mainly based on the standard methods developed by DTRA for 

the NTPR Program. Appendix C contains all necessary equations to estimate external, internal 

and skin doses, as well as upper-bound doses, for ECUP personnel. 

For the external gamma exposure rates, it is concluded that the aerial measurements from 

the 1972 radiological surveys conducted by the AEC would tend to overestimate the conditions 

that prevailed during the cleanup project. These exposure rates, shown in Table 4, are 

recommended as default values to be used to estimate high-sided external whole-body gamma 

doses. Furthermore, personal dosimetry records were evaluated and are discussed in Section 4. It 

is reported that of the 12,248 film badge records, about 99.9 percent of doses are lower than the 

MDL of 20 mrem. Based on an assessment of uncertainties in film badge results, doses lower 

than the MDL should be replaced with calculated doses based on environmental data when 

reconstructing external doses of ECUP participants. In addition, over 7,500 TLDs were issued 

and 99.7 percent of the doses are less than 0.010 rem. It is important to mention that when 

required, each film badge or TLD was worn for a limited period during a participant’s 

assignment to the atoll. In most cases, an individual who was assigned to restricted access islands 

was issued several sequential dosimeters. Therefore, a single dosimeter result may not represent 

an individual’s total external dose record. 

As for the radionuclides of concern and resultant doses, it is estimated that over 

99 percent of the internal dose from inhalation of suspended soil and dust for most internal 

organs would result from three main TRU radionuclides, namely Pu-239/240 and Am-241. The 

TRU radionuclides and other radionuclides of concern also contributed to calculated internal 

doses from incidental ingestion of soil and dust, although these doses were significantly lower 

than inhalation doses. With respect to the activity concentration of airborne suspended soil and 

dust from undisturbed ground, it is recommended to base them on island-average soil 

concentrations from the 1972 AEC soil sampling program, which are reported in Table 6. For 

exposures to contaminated soil that was excised from the islands of Boken, Enjebi, Lujor, 

Aomon, and Runit, then transported, mixed and contained in the Cactus Crater and dome on 

Runit, it is recommended that the air activity concentrations should be based on the TRU 

concentrations of the soil removed from each island. These concentrations are derived from the 

total estimated activity removed for each island as reported in DNA (1981). Using the total TRU 

activity in curies and the total volume of soil removed from each of the five islands, an average 

soil concentration for each island and overall weighted averages are estimated in Section B-2. In 

addition, air sampling results are available in the form of weekly statistical summaries as shown 

in Section B-3. Because only the weekly maximum concentrations are reported, these data can be 

used to estimate extremely conservative internal inhalation doses, as is the case in the example 

scenario assessment for boat crewmembers discussed in Section 8. 

Based on the above information, the study team was able to build a collection of pertinent 

radiation data and combine them with reasonable assumptions and sound calculations to produce 

conservative and credible dose estimates. Using the data and information compiled in this report, 

several examples of dose estimation for ECUP exposure scenarios are presented in Section 8. 

They include sample assessments of hypothetical participation scenarios for personnel who were 
158

involved in soil cleanup such as earthmoving equipment operators, debris cleanup personnel 

such as crane operators, and crewmembers of boats that were used to transport contaminated soil. 

In addition, an example dose assessment for Air Force personnel that were assigned temporary 

duty at Enewetak in 1965 is included. The latter example is developed to serve as a basis to 

estimate doses in support of specific VA claims from veterans that performed duties on 

Enewetak in 1965. 

Finally, guidelines are presented in Section 9 to support the development of a standard 

operating procedure to be used to perform individual radiation dose assessments for ECUP 

veterans in response to VA requests. For such individualized dose assessments, it is important to 

collect veteran-specific information and data that can be used to adjust or complement the 

scenarios of exposures and assumptions identified in this report. For this purpose, an ECUPspecific questionnaire, included as Appendix I was developed and is being used to collect 

veteran-specific information. If additional sources of exposures and pathways are identified in 

the questionnaire, supplemental doses should be estimated using standard dose reconstruction 

techniques. 

Based on discussions in this report, it is confirmed that ECUP participants conducted all 

cleanup work within a structured and effective radiation protection program that served to 

minimize radiation doses as reported in DNA (1981). The highest of the estimated upper-bound 

total effective radiation doses for any of the included sample assessments is 0.22 rem (2.2 mSv). 

This dose is similar to the average individual effective dose of 0.31 rem (3.1 mSv) to the U.S. 

population from ubiquitous background radiation including radon (NCRP, 2009a). It is also 

substantially lower than the whole body occupational dose limit of 5 rem (50 mSv) per year that 

was in place for personnel during the ECUP. As a result of the ECUP radiation protection 

program, the generally low levels of contamination encountered, and as confirmed by example 

dose assessments, it is concluded that ECUP participants’ exposures resulted in whole-body and 

organ doses much lower than doses that would result in observable health effects. This 

conclusion is supported by the Health Physics Society official position statement regarding 

radiation health risks: 

“Substantial and convincing scientific data show evidence of health effects 

following high dose exposures (many multiples of natural background). However, 

below levels of about 100 mSv [10 rem] above background from all sources 

combined, the observed radiation effects in people are not statistically different 

from zero.” (HPS, 2019) 
159

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168

A P P E N D I C E S 
169 

Appendix A. 

Operational Milestones and Major Activities of the 

Enewetak Cleanup Project 

A-1. Enewetak Cleanup Project Milestones 

From 1972 to 1976, planning for the radiological cleanup, rehabilitation, and resettlement 

of Enewetak Atoll in the Marshall Islands resulted in a decision to conduct a three-year cleanup 

project. From early 1977 through mid-1980 the Enewetak Cleanup Project proceeded, and was 

executed by the DoD involving U.S. Army, U.S. Navy, and U.S. Air Force personnel. During 

that time, the AEC performed radiological characterization and certification, and the DOI 

conducted the rehabilitation and resettlement project. The following are significant planning and 

administrative milestones of the cleanup project (DNA, 1981): 

 March 15, 1977, mobilization begins 

 March 16, 1977, Air Force communications team arrive 

 April 5, 1977, first Army-Navy team arrives through May 17, 1977 

 April 14, 1977, first Navy sealift 

 May 3–16, 1977, Transportation units arrive 

 May 17, 1977, advance party arrives 

 May–November 1977, Lojwa Camp construction 

 June 15, 1977, D-Day 

 June 1977, Joint Task Group organized 

 June 28, 1977, FRST deployment 

 July–November 1977, mobilization continues 

 November 1977, Operation Switch I: rotation/replacement of personnel 

 November 15, 1977–February 1980, cleanup implementation (See Appendix A-2 for details) 

 March 26, 1979, demobilization begins 

 September 3–4, 1979, sealift of retrograde cargo 

 End of September, 1979, DOE-ERSP demobilization complete 

 October 13–14, 1979, all Lojwa Camp personnel move to Enewetak Camp 

 October 1979–January 1980, final cleanup and other actions completed 

 March 1, 1980, rollup begins 

 May 13, 1980, final 45 personnel depart Enewetak Atoll. 
170 

A-2. Major Enewetak Cleanup Activities 

Table A-1 lists the major activities associated with the debris cleanup, entries D-1 to 

D-41), soil cleanup, entries S-1 to S-27), and equipment/facility decontamination, entries E-1 and 

E-2) in the ECUP operation. The entries in Table A-1 are generally arranged to follow a 

chronological order by the start date of each activity. 
171

Table A-1. Major ECUP cleanup activities for debris, soil, and equipment/facility 

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

D-1 FRST completed 

survey of 

contaminated debris 

on Runit, with 

assistance by WBCT

FRST members, 

WBCT 

Survey 

instruments for 

α, β, and γ,

check sources, 

and spray 

painters 

Runit March 1977 November 1977 (DNA, 1981) 

D-2 Debris surveys at 

Enjebi 

USAE or FRST 

members 

Radiation survey 

instruments, 

check sources, 

and spray 

painters 

The 

contaminated 

sites include one 

runway parking 

area and three 

concrete 

structures 

unusually 

difficult to 

decontaminate 

First survey, July 

1977; second 

survey, early 1978 

First survey, early 

1978; second 

survey, sometime 

in 1978 

(DNA, 1981) 

D-3 Manual removal of 

small debris from 

offshore areas 

WBCT divers No special 

equipment 

All islands 

including Runit 

Beginning of 

Cleanup Phase 

September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 

D-4 Large debris 

retrieval from water 

-- Diver manually 

connected winch 

cable with large 

debris 

WBCT divers D8 bulldozers 

and landing 

crafts with 

winches 

All islands 

including Runit 

Beginning of 

Cleanup Phase 

September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 

D-5 Large debris under 

water hoisted to 

beach stockpiles or 

aboard the landing 

crafts 

Truck drivers and 

crane operators 

Dump trucks, 

landing crafts, 

and floating 

platforms 

All islands 

including Runit 

Beginning of 

Cleanup Phase 

September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 
172

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

D-6 Yellow debris on 

loading for lagoon 

dumping 

Engineering 

equipment 

operators, crew 

members 

Bucket loaders, 

12.5 ton cranes 

w/clamshells, 

landing crafts, 

and floating 

platforms 

All islands 

including Runit 

Beginning of 

Cleanup Phase 

September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 

D-7 Yellow debris 

transport to lagoon 

dump sites 

Crew members Landing crafts 

and floating 

platforms 

Routing from an 

island including 

Runit to 

designated 

lagoon dump 

sites 

Beginning of 

Cleanup Phase 

September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 

D-8 Yellow debris 

offloading at lagoon 

dump sites 

Engineering 

equipment 

operators, crew 

members 

Bucket loaders, 

12.5 ton cranes 

w/ clamshells, 

landing crafts, 

and floating 

platforms 

Designated 

lagoon dump 

sites 

Beginning of 

Cleanup Phase 

September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 

D-9 Disassembling and 

breaking up 

oversized debris for 

collection and 

transport 

USAE members Engineering 

tools for 

demolitions 

All islands 

including Runit 

Beginning of 

Cleanup Phase 

September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 

D-10 Survey of 

contaminated debris 

FRST members 

and truck driver 

Exposure rate 

meters, survey 

instruments for 

α, β, and γ,

check sources, 

cameras, and 

spray painters 

All islands 

including Runit 

Beginning of 

Cleanup Phase 

September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 

D-11 Hand tools used to 

clear brush from the 

entire Fig-Quince 

area 

USAE members Hand tools Fig-Quince area 

at Runit 

November 1, 1977, 

at the earliest 

November 28, 

1977, at the latest 

(DNA, 1981) 
173

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

D-12 Debris cleanup at 

Lujor 

USAE members Equipment not 

specified 

Lujor November 15, 1977 February 22, 1978 (DNA, 1981) 

D-13 FRST surveyed FigQuince area for Pu 

fragments 

FRST members Portable 

FIDLER probes, 

shovels, and 

plastic bags 

Fig-Quince area 

at Runit 

November 28, 1977 December 23, 1977 (DNA, 1981) 

D-14 General survey of 

contaminated debris 

at Aomon 

USAE or FRST 

members, truck 

drivers 

Radiation survey 

instruments, 

check sources, 

cameras, spray 

painters, 

shovels, and 

plastic bags 

Aomon December 8, 1977 January 16, 1978 (DNA, 1981) 

D-15 Debris cleanup at 

Boken 

USAE and FRST 

members 

Equipment not 

specified 

Boken January 4, 1978 July 12, 1978 (DNA, 1981) 

D-16 Demolition of 

"Enjebi Hilton" 

USAE members Air chisels Enjebi Hilton on 

Enjebi 

January 26, 1978 March 4, 1978 (DNA, 1981) 

D-17 Transporting 

contaminated debris 

from Enjebi to Runit 

Navy Boat 

Transportation 

Team, USAE 

members 

Landing crafts 

or floating 

platforms 

Enjebi Hilton, a 

large bunker, 

and a small 

concrete vault 

on Enjebi 

January 26, 1978 May 15, 1979 (DNA, 1981) 

D-18 Removal of bunker 

surface 

contamination by 

sandblasting at 

Enjebi 

USAE members Sandblasters, 

hammer drills, 

and grinders 

A large bunker 

on the east side 

of Enjebi 

March 1978 March 1978 (DNA, 1981) 

D-19 Removal by 

chipping of surface 

beta contamination 

of a vault at Enjebi 

USAE members Chipping 

hammers and 

drills 

A small heavily 

reinforced, 

concrete 

instrument vault 

at Enjebi 

March 1978 May 15, 1979 (DNA, 1981) 
174

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

D-20 Re-survey of 

contaminated 

concrete structures 

FRST members 

and truck driver 

Survey 

instruments for 

α, β, and γ,

check sources, 

and spray 

painters 

Enjebi, Boken, 

Aomon, and 

Bijire 

March 1978 March 1978 (DNA, 1981) 

D-21 Removal of concrete 

surface 

contamination by 

sandblasting and 

chipping 

USAE members Sandblasters, 

hammer drills, 

grinders, acid, 

and detergent 

washers 

Enjebi, Boken, 

Aomon, and 

Bijire 

March–April 1978 

time frame 

March–April 1978 

time frame 

(DNA, 1981) 

D-22 Debris survey at 

bunkers on Boken 

USAE and FRST 

members 

Radiation survey 

instruments for 

betas, check 

sources, and 

spray painters 

Boken April 1978 June 1978 (DNA, 1981) 

D-23 Debris cleanup at 

Eleleron 

USAE members Equipment not 

specified 

The peninsula of 

Eleleron 

June 1, 1978 July 10, 1978 (DNA, 1981) 

D-24 Cleanup at Bijire USAE members Equipment not 

specified 

A concrete 

photographic 

bunker 

(Greenhouse 

Station 100) on 

Bijire 

June 8, 1978 July 23, 1978 (DNA, 1981) 

D-25 Contaminated debris 

stockpiled from 

other islands was 

placed in the crater 

during the tremie 

operation. 

Equipment 

operators, USAE 

members 

Trucks and 

bulldozers 

Runit June 15, 1978 February 10, 1979 (DNA, 1981) 
175

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

D-26 Disposed of 

contaminated 

"oversized material" 

(too large for the 

tremie pump) by 

bulldozing it off the 

edge of the Cactus 

Crater 

Equipment 

operators, USAE 

members 

Bulldozers and 

graders 

Near Cactus 

Crater at Runit 

After June 15, 

1978, the beginning 

of the tremie 

operation 

February 10, 1979, 

end of tremie 

operation 

(DNA, 1981) 

D-27 Explosive 

demolition for two 

Pu-contaminated 

concrete blocks at 

Aomon 

Army EOD 

Specialists 

Explosives Aomon -- One 

block near 

Yuma GZ and 

the other near 

Kickapoo GZ 

August 1978 October 1978 (DNA, 1981) 

D-28 Cleanup of debris 

from two 

demolished Pu 

concrete blocks at 

Aomon 

Equipment 

operators, USAE 

members 

Trucks and 

bulldozers 

Aomon -- One 

block near 

Yuma GZ and 

the other near 

Kickapoo GZ 

August 1978 October 1978 (DNA, 1981) 

D-29 FRST conducted two 

surveys to estimate 

debris volume on 

Runit 

FRST members Equipment not 

specified 

Runit September 1978 November 1978 (DNA, 1981) 

D-30 Special survey for 

rusty-colored Pu 

fragments near 

Kickapoo GZ at 

Aomon 

J-2, DOE, FRST 

members 

Survey 

instruments for 

gammas from 

Am-241 and 

check sources 

Aomon -- near 

Kickapoo GZ 

October 1978 October 1978 (DNA, 1981) 

D-31 Two cleanups of Pu 

fragments near 

Kickapoo GZ at 

Aomon 

FRST and JTG J-2 

members 

Shovels and 

hand tools 

Aomon -- near 

Kickapoo GZ 

October 1978 December 1978 (DNA, 1981; 

FCDNA, 1979) 
176

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

D-32 Cleanup of a twisted 

metal debris pile on 

the reef just north 

the old runway 

USAE members Equipment not 

specified 

North of the old 

runway on Runit

October 1978, at 

the earliest 

December 1978 (DNA, 1981; 

FCDNA, 1979) 

D-33 Cleanup metal debris 

in the area of the 

Blackfoot GZ 

USAE members Equipment not 

specified 

Blackfoot GZ 

on Runit 

October 1978, at 

the earliest 

December 1978 (DNA, 1981; 

FCDNA, 1979) 

D-34 Bulldozed a large 

quantity of 

contaminated debris 

found unexpectedly 

in the crater banks 

into crater (in 

February, 1979) 

Equipment 

operators, USAE 

members 

Bulldozers Banks of Cactus 

Crater at Runit 

February 1, 1979 February 2, 1979 (DNA, 1981) 

D-35 Delayed 

contaminated debris 

from Aomon crypt 

and Runit placed in 

the "Donut Hole". 

Equipment 

operators, USAE 

members 

Trucks and 

bulldozers 

Runit February 1979 Mid-July 1979 (DNA, 1981) 

D-36 Survey and resurvey of 

contaminated debris 

pulled out from the 

ocean reef of Runit 

FRST members 

and truck driver 

Exposure rate 

meters, survey 

instruments for 

α, β, and γ,

check sources, 

cameras, and 

spray painters. 

The ocean reef 

of Runit near 

Lacrosse Crater 

Around 

August 1979 

Around 

August 1979 

(DNA, 1981) 

D-37 Containment in the 

cap of reclassified 

"yellow" to "red" 

debris found in the 

ocean reef of Runit 

Equipment 

operators, USAE 

members 

Trucks and 

bulldozers with 

winches 

Near Lacrosse 

crater and 

Cactus Crater at 

Runit 

August 1979 September 6, 1979, 

when dome 

capping ended 

(DNA, 1981) 
177

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

D-38 Survey of 

contaminated debris 

revealed following 

seasonal recession of 

beaches in 

September, 1979 

FRST members 

and truck driver 

Exposure-rate 

meters, survey 

instruments for 

α, β, and γ,

check sources, 

cameras, and 

spray painters 

Runit beaches September 1979 September 1979 (DNA, 1981) 

D-39 First extension 

container for the 

"red" debris revealed 

following seasonal 

recession of beaches 

in September, 1979 

Equipment 

operators, USAE 

members 

Trucks and 

bulldozers 

The first 

extension added 

on the island 

side of Cactus 

Crater 

September 19, 1979 End of September 

1979 

(DNA, 1981) 

D-40 Survey of additional 

contaminated beach 

debris exposed in 

November, 1979 

FRST members 

and truck driver 

Exposure rate 

meters, survey 

instruments for 

α, β, and γ,

check sources, 

cameras, and 

spray painters 

Runit beaches November 1979 November 1979 (DNA, 1981) 

D-41 Second extension 

container for "red" 

beach debris 

discovered in 

November, 1979 

Equipment 

operators, USAE 

members 

Trucks and 

bulldozers 

The second 

extension added 

on the lagoon 

side of Cactus 

Crater 

Mid-February 1980 The end of 

February 1980 

(DNA, 1981) 

S-1 Erie site 

investigation 

AARDC, USAE, 

and FRST 

members 

SPA-2 micro-R 

meters, soil 

probes, drilling 

equipment, and 

backhoes 

Erie GZ on 

Runit 

June 30, 1977 July 11, 1977 (DNA, 1981) 

S-2 Devegetation - 

extensive 

Equipment 

operators, USAE 

members 

Hand tools, 

bulldozers, 

chains, and 

trucks 

Enjebi July 1, 1977 July 31, 1977 (DOE, 1982a; 

DNA, 1981) 
178

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

S-3 Devegetation - 

moderate 

Equipment 

operators, USAE 

members 

Hand tools, 

bulldozers, and 

trucks 

Boken, Alembel September 1977 October 1977 (DOE, 1982a; 

DNA, 1981) 

S-4 Devegetation - 

extensive 

Equipment 

operators, USAE 

members 

Hand tools, 

bulldozers, and 

trucks 

Bokombako, 

Lujor, 

Aej, Aomon, 

Bijire 

October 1, 1977 March 15, 1978 (DOE, 1982a; 

DNA, 1981) 

S-5 Assisting FRST 

digging trenches to 

collect subsurface 

soil samples 

USAE members Digging tools 

and equipment 

Runit November 28, 1977 December 23, 1977 (DNA, 1981) 

S-6 Devegetation - 

extensive 

Equipment 

operators, USAE 

members 

Hand tools, 

bulldozers, and 

trucks 

Runit January 1978 January 1979 (DOE, 1982a; 

DNA, 1981) 

S-7 Devegetation - 

moderate 

Equipment 

operators, USAE 

members 

Hand tools, 

bulldozers, and 

trucks 

Bokoluo, 

Kirunu, Louj, 

Mijikadrek, 

Kidrinen, 

Eleleron, Elle, 

Bokenelab, 

Billae 

January 1, 1978 March 1, 1978 (DOE, 1982a; 

DNA, 1981) 

S-8 Cleanup of Co-60 

contaminated soil at 

Medren 

USAE equipment 

operators, JTG/J2, and FRST 

members 

Survey 

instruments, soil 

sampling tools, 

dump trucks, 

bucket, backhoe 

loaders, water 

tank trucks, 

scrape blades, 

and LCUs 

Two 

contaminated 

areas, "Crate", 

and "Blue Star", 

which were 

about 150 feet 

apart, 300 yards 

south of the old 

runway 

February 7, 1978 February 10, 1978 (DNA, 1981) 
179

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

S-9 Soil 

excision/removal at 

Aomon

Equipment 

operators, USAE 

members

Survey 

instruments, soil 

sampling tools, 

IMPs - in situ 

survey van, 

dump trucks, 

bulldozers 

Aomon March 8, 1978 August 1978 (DNA, 1981) 

S-10 Plowing experiment 

on Enjebi 

USAE members D8 bulldozers 

w/single-plow 

blades 

Enjebi 

(Area X-1) 

June 1978 June 1978 (DNA, 1981) 

S-11 Tremie operation 

Step 1- loading 

contaminated soil 

from stockpiles to 

dump trucks 

Equipment 

operators, USAE 

members 

Loader buckets 

and trucks 

Soil stockpiles 

on Runit 

June 15, 1978 February 10, 1979 (DNA, 1981) 

S-12 Tremie operation 

Step 2 - driving 

dump trucks from 

contaminated soil 

stockpiles to 

concrete batch plant 

Truck drivers Trucks Soil stockpiles 

and concrete 

batch plant on 

Runit 

June 15, 1978 February 10, 1979 (DNA, 1981) 

S-13 Tremie operation 

Step 3 - 

contaminated soil 

mixed with cement 

at batch plant 

Plant operators Batch plant and 

screen plant 

equipment 

Batch plant and 

screen plant on 

Runit 

June 15, 1978 February 10, 1979 (DNA, 1981) 

S-14 Tremie operation 

Step 4 - driving 

transit-mix trucks 

from batch plant to 

concrete pump next 

to the crater 

Truck drivers Transit-mix 

trucks 

Batch plant and 

concrete pump 

on Runit 

June 15, 1978 February 10, 1979 (DNA, 1981) 
180

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

S-15 Tremie operation 

Step 5 - pumping 

contaminated slurry 

into pipes 

USAE members Concrete pump 

and tremie pipes

Concrete pump 

next to Cactus 

Crater on Runit 

June 15, 1978 February 10, 1979 (DNA, 1981) 

S-16 "Processed Tremie" 

method: pouring 

rejected slurry into 

excavated trenches 

and placing the 

hardened slurry into 

the crater. 

Equipment 

operators, USAE 

members 

Transit-mix 

trucks and dump 

trucks 

Cactus Crater 

area at Runit 

June 15, 1978 February 10, 1979 (DNA, 1981) 

S-17 Soil excision/ 

removal at Enjebi 

(Surface) 

USAE members Bulldozers and 

trucks 

Enjebi 

July 6, 1978 March 23, 1979 

(DNA, 1981) 

S-18 Soil excision/ 

removal at Enjebi 

(Subsurface) 

USAE members Bulldozers and 

trucks 

Enjebi 

December 6, 1978 April 18, 1979 

(DNA, 1981) 

S-19 Soil excision/ 

removal at Boken 

(Subsurface) – 1st 

operation 

Company B, 

USAE members 

Bulldozers, 

bucket loaders, 

trucks, LCM-8, 

LARC-LX 

Soil transported 

from Boken to 

Enjebi, then to 

Runit 

Mid-January 1979 April 23, 1979 (DNA, 1981) 

S-20 Devegetation – 

moderate on Lojwa 

Equipment 

operators, USAE 

members 

Hand tools, 

bulldozers, and 

trucks 

Lojwa February 1, 1979 March 1, 1979 (DOE, 1982a; 

DNA, 1981) 

S-21 Soil-cement mixture 

operation 

Equipment 

operators, USAE 

members 

Graders, 

bulldozers with 

disc harrows and 

roller 

compactors, and 

sprinkler trucks 

Cactus Crater on 

Runit 

February 18, 1979 July 26, 1979 (DNA, 1981) 
181

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

S-22 Soil excision/ 

removal at FigQuince on Runit - 

1st phase 

Equipment 

operators, USAE 

members 

Bulldozers with 

clamshells, 

graders, and 

dump trucks 

Fig-Quince area 

on Runit 

March 13, 1979 March 24, 1979 (DNA, 1981) 

S-23 Soil excision/ 

removal at Enjebi 

(Plow-X) 

USAE members Bulldozers and 

trucks 

Enjebi April 1, 1979 May 9, 1979 (DNA, 1981) 

S-24 Soil excision and 

removal at Lujor 

USAE, USNE, 

and FRST 

members 

Bulldozers and 

bucket loader 

Lujor 

(eastern half of 

island) 

April 7, 1979 July 8, 1979 (DNA, 1981) 

S-25 Soil excision/ 

removal at FigQuince on Runit - 

2nd phase 

Equipment 

operators, USAE 

members 

Bulldozers with 

clamshells and 

graders, and 

dump trucks 

Fig-Quince area 

on Runit 

June 1, 1979 July 26, 1979 (DNA, 1981) 

S-26 Soil excision/ 

removal at Boken 

(Subsurface) –2nd 

operation 

Company B, 

USAE members 

Bulldozers, 

bucket loaders, 

5-ton dump 

trucks, LCM-8, 

LARC-LX, 

LCU-causewayLARC 

combination 

Soil transported 

from Boken to 

Runit 

June 11, 1979 July 7, 1979 (DNA, 1981) 

S-27 Placing 12-inch 

blanket of relatively 

clean soil (<160 

pCi/g) over the FigQuince area 

Equipment 

operators, USAE 

members 

Bulldozers and 

graders 

Runit July 1979 August 1979 (DNA, 1981) 

E-1 Laundry facility for 

cleaning washable 

personnel protective 

equipment 

USAE members Washers and 

dryers 

Lojwa Beginning of 

Cleanup Phase 

End of ECUP (DNA, 1981) 
182

Activity 

Index* Cleanup Activity Personnel Equipment Activity Location Start Date† End Date References 

E-2 Decontamination of 

batch plant to 

produce clean 

concrete to build the 

keywall 

Plant operators, 

USAE members 

Batch plant 

equipment 

Batch plant on 

Runit 

Beginning of 

Cleanup Phase 

End of ECUP (DNA, 1981) 

*

 Key: D for Debris cleanup and decontamination, S for Soil cleanup and E for Equipment/facility decontamination. 

†

 Activities with a Start Date listed as “Beginning of Cleanup Phase” began on or shortly after the official start date of the ECUP cleanup phase of November 15, 1977 

(DNA, 1981). 
183

Appendix B. 

Radiation Monitoring Data 

Results and information pertinent to ECUP radiological conditions and radiation 

monitoring are provided in this appendix for environmental TLD results, TRU soil activity 

concentrations in excised soil, and an example weekly summary of air sampling and TLD data. 

B-1. Environmental TLD Results 

The results of measurements of environmental radiation exposure and exposure rates 

made during ECUP are listed in Table B-1. These results are the basis of the summary results in 

Table 5 of the main report. 

Table B-1 was developed by manually entering information pertaining to environmental 

TLDs contained on hand-written data sheets found in the ECUP records to an Excel workbook 

collection. The environmental TLDs covered a period roughly from June 1978 to October 1979. 

One monthly report corresponding to an approximate period of August to September 1978 was 

not found among the records researched. Subsequent searches of the ECUP records collection 

did not find this monthly report. 

The value in column Net Reading for each record was derived from the gross TLD 

reading, which was not reported in Table B-1. The gross reading was corrected by the 

application of the dosimeter calibration factor. Background was subtracted from the corrected 

result, which is then shown as the net reading. The gross reading is greater in value than the 

corresponding net reading listed in this table. One net exposure rate for Runit debris pile in the 

table for the period 9/25 to 10/18/78 is the highest reading observed and is about two orders of 

magnitude higher than most readings. 

There are two sets of IRENE readings labeled IRENE (TLD Set #1) and IRENE (TLD 

Set #2). It appears that TLD Set #1 is from the main island, where Shot Seminole crater is 

located, and TLD Set #2 is from the western islet, or what remained of the island of Helen. 
184

Table B-1. Environmental radiation exposure and exposure rates measured with TLDs on 

islands of Enewetak Atoll 

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

ALICE 9/25/1978 10/30/1978 35 19 23 

ALICE 10/30/1978 11/13/1978 14 8 24 

ALICE 11/13/1978 12/16/1978 33 14 18 

ALICE 12/16/1978 1/24/1979 39 4 4 

ALICE 1/24/1979 2/12/1979 19 14 31 

ALICE 2/12/1979 3/12/1979 28 14 21 

ALICE 3/12/1979 4/11/1979 30 18 25 

ALICE 4/11/1979 5/15/1979 34 19 23 

ALICE TLD apparently lost; a blank is shown in the TLD Report 

ALICE 6/14/1979 7/30/1979 46 17 15 

ALICE 7/19/1979 8/21/1979 33 10 13 

ALICE 8/21/1979 10/10/1979 50 18 15 

BELLE 6/21/1978 7/22/1978 31 6‡ 8‡

BELLE 7/22/1978 8/22/1978 31 6 8 

BELLE 9/25/1978 10/30/1978 35 46 55 

BELLE 10/30/1978 11/21/1978 14 18 54 

BELLE 11/21/1978 12/16/1978 25 24 40 

BELLE 12/16/1978 1/24/1979 39 7 7 

BELLE 1/24/1979 2/12/1979 19 31 68 

BELLE 2/12/1979 3/12/1979 28 33 49 

BELLE 3/12/1979 4/11/1979 30 36 50 

BELLE 4/11/1979 5/15/1979 34 41 50 

BELLE TLD apparently lost; a blank is shown in the TLD Report 

BELLE 6/14/1979 7/30/1979 46 36 33 

BELLE 7/30/1979 8/21/1979 22 12 23 

BELLE 8/21/1979 10/10/1979 50 22 18 

MARY 10/23/1978 11/20/1978 28 4 6 

MARY 11/20/1978 12/19/1978 29 2 3 

MARY 12/19/1978 1/24/1979 36 2 2 

MARY 1/24/1979 2/12/1979 19 2 4 

MARY 2/12/1979 3/16/1979 32 4 5 

MARY 3/16/1979 4/11/1979 26 5 8 

MARY 4/11/1979 5/19/1979 38 5 5 

MARY 5/19/1979 6/19/1979 31 4 5 

MARY No TLD data for June/July 1979 

MARY 7/17/1979 8/30/1979 44 7 7 

MARY 8/30/1979 10/10/1979 42 5 5 

EDNA'S Daughter 11/24/1978 12/16/1978 22 3 6 
185

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

EDNA'S Daughter 12/16/1978 1/24/1979 39 5 5 

EDNA'S Daughter 1/24/1979 2/12/1979 19 5 11 

EDNA'S Daughter 2/12/1979 3/12/1979 28 4 6 

EDNA'S Daughter 3/12/1979 4/11/1979 30 6 8 

EDNA'S Daughter 4/11/1979 5/15/1979 34 6 7 

EDNA'S Daughter 5/15/1979 6/15/1979 31 8 11 

EDNA'S Daughter 6/15/1979 7/30/1979 45 5 5 

EDNA'S Daughter 7/30/1979 8/21/1979 22 6 11 

EDNA'S Daughter 8/21/1979 10/10/1979 50 9 8 

OLIVE 9/25/1978 10/28/1978 33 1 1 

OLIVE 10/28/1978 11/20/1978 23 3 5 

OLIVE 11/20/1978 12/21/1978 31 1 1 

OLIVE 12/21/1978 1/24/1979 34 1 1 

OLIVE 1/24/1979 2/12/1979 10 1 4 

OLIVE 2/12/1979 3/16/1979 32 2 3 

OLIVE 3/16/1979 4/11/1979 26 1 2 

OLIVE 4/11/1979 5/16/1979 35 2 2 

OLIVE 5/16/1979 6/19/1979 34 2 2 

OLIVE TLD missing 

OLIVE 6/19/1979 8/31/1979 73 3 2 

OLIVE 8/31/1979 10/10/1979 41 3 3 

PEARL 6/22/1978 7/22/1978 30 5‡ 7‡

PEARL 7/22/1978 8/22/1978 31 2 3 

PEARL 9/25/1978 10/28/1978 33 9 11 

PEARL 10/28/1978 11/20/1978 23 0 0 

PEARL 11/20/1978 12/21/1978 31 1 1 

PEARL 12/21/1978 1/24/1979 39 2 2 

PEARL 1/24/1979 2/12/1979 19 0 0 

PEARL (Beach) 2/13/1979 3/10/1979 25 2 3 

PEARL (Beach) 3/10/1979 4/17/1979 38 2 2 

PEARL (Beach) 4/17/1979 5/19/1979 32 2 3 

PEARL (Beach) 5/19/1979 6/18/1979 30 1 1 

PEARL (Beach) 6/20/1979 7/23/1979 33 0 0 

PEARL (Beach) 8/4/1979 8/31/1979 27 3 5 

PEARL (Beach) TLD lost 

MARY's Daughter 10/23/1978 11/20/1978 28 11 16 

MARY's Daughter 11/20/1978 12/19/1978 29 8 11 

MARY's Daughter 12/19/1978 1/24/1979 36 13 15 

MARY's Daughter 1/24/1979 2/12/1979 19 8 18 

MARY's Daughter 2/12/1979 3/16/1979 32 16 21 
186

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

MARY's Daughter 3/16/1979 4/11/1979 26 13 21 

MARY's Daughter 4/11/1979 5/16/1979 35 10 12 

MARY's Daughter 5/16/1979 6/19/1979 34 12 15 

MARY's Daughter TLD missing 

MARY's Daughter 7/17/1979 8/30/1979 44 11 10 

MARY's Daughter 8/30/1979 10/10/1979 42 12 12 

JANET (FRST Shack) 6/21/1978 7/21/1978 30 5

‡ 7‡

JANET (FRST Shack) 3/16/1979 4/17/1979 32 3 4 

JANET (Farm) 6/21/1978 7/21/1978 30 31‡ 43‡

JANET (Farm) 7/22/1978 8/22/1978 31 26.6 36 

JANET (Farm) 9/25/1978 10/23/1978 28 2 3 

JANET (Farm) 10/23/1978 11/16/1978 24 5 9 

JANET (Farm) 11/16/1978 12/20/1978 34 4 5 

JANET (Farm) 12/20/1978 1/23/1979 34 3 4 

JANET (Farm) 1/23/1979 2/13/1979 21 4 8 

JANET (Farm) 2/13/1979 3/12/1979 27 5 8 

JANET (Farm) 3/12/1979 4/17/1979 36 5 6 

JANET (Farm) 4/17/1979 5/16/1979 29 6 9 

JANET (Farm) 5/16/1979 6/18/1979 33 5 6 

JANET (Farm) 6/18/1979 7/21/1979 33 5 6 

JANET (Farm) 7/21/1979 8/21/1979 31 7 9 

JANET (Farm) 8/31/1979 10/10/1979 41 4 4 

JANET (Farm Shack) 6/21/1978 7/21/1978 30 9‡ 13‡

JANET (Farm Shack) 7/22/1978 8/22/1978 31 5.6 8 

JANET (Farm Shack) No TLD data for Sept/Oct 1978 

JANET (Farm Shack) 10/23/1978 11/16/1978 24 4 7 

JANET (Farm Shack) 11/16/1978 12/20/1978 34 3 4 

JANET (Farm Shack) TLD lost in storm 

JANET (Farm Shack) 1/23/1979 2/12/1979 20 2 4 

JANET (Farm Shack) 2/13/1979 3/12/1979 27 5 8 

JANET (Farm Shack) 3/12/1979 4/17/1979 36 6 7 

JANET (Farm Shack) 4/17/1979 5/16/1979 29 6 9 

JANET (Farm Shack) 5/16/1979 6/18/1979 33 5 6 

JANET (North Point) 6/21/1978 7/21/1978 30 24‡ 33‡

JANET (North Point) TLD lost 

JANET (North Point) 9/25/1978 10/23/1978 28 12 18 

JANET (North Point) 10/23/1978 11/16/1978 24 8 14 

JANET (North Point) 11/16/1978 12/20/1978 34 13 16 

JANET (North Point) 12/20/1978 1/23/1979 34 6 7 

JANET (North Point) 1/23/1979 2/13/1979 21 7 14 
187

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

JANET (North Point) 2/13/1979 3/12/1979 27 6 9 

JANET (North Point) 3/12/1979 4/17/1979 36 9 10 

JANET (North Point) 4/17/1979 5/16/1979 29 8 11 

JANET (North Point) 5/16/1979 6/18/1979 33 8 10 

JANET (North Point) TLD missing 

JANET (North Point) 7/21/1979 8/21/1979 31 6 8 

JANET (North Point) 8/21/1979 10/10/1979 50 8 7 

JANET (Trailer) 6/21/1978 7/21/1978 30 7

‡ 10‡

JANET (Trailer) 7/22/1978 8/22/1978 31 5.6 8 

JANET (Trailer) No TLD data for Sept/Oct 1978 

JANET (Trailer) 10/23/1978 11/16/1978 24 3 5 

JANET (Trailer) 11/16/1978 12/20/1978 34 0 0 

JANET (Trailer) 12/20/1978 1/23/1979 34 2 2 

JANET (Trailer) 1/23/1979 2/13/1979 21 4 8 

JANET (Trailer) 2/13/1979 3/12/1979 27 3 5 

JANET (Trailer) 3/12/1979 4/17/1979 36 3 3 

JANET (Trailer) 4/17/1979 5/16/1979 29 3 4 

JANET (Trailer) 5/16/1979 6/18/1979 33 2 3 

JANET (Trailer) 6/18/1979 7/21/1979 33 7 9 

JANET (Trailer) 7/21/1979 8/21/1979 31 2 3 

JANET (Trailer) 8/21/1979 10/10/1979 50 2 2 

PERCY 11/20/1978 12/19/1978 29 3 4 

PERCY 12/19/1978 1/24/1979 36 3 3 

PERCY 1/24/1979 2/12/1979 19 3 7 

PERCY 2/12/1979 3/16/1979 32 6 8 

PERCY 3/16/1979 4/11/1979 26 8 13 

PERCY 4/11/1979 5/16/1979 35 6 7 

PERCY 5/16/1979 6/19/1979 34 6 7 

PERCY 6/19/1979 7/17/1979 36 6 7 

PERCY 7/17/1979 8/30/1979 44 3 3 

PERCY 8/30/1979 10/10/1979 42 2 2 

RUBY 9/25/1978 10/28/1978 33 6 8 

RUBY 10/28/1978 11/20/1978 23 6 11 

RUBY 11/20/1978 12/15/1978 25 1 2 

RUBY 12/15/1978 1/24/1979 40 

RUBY 1/24/1979 2/12/1979 19 4 9 

RUBY 2/12/1979 3/16/1979 32 8 10 

RUBY 3/16/1979 4/20/1979 35 0 0 

RUBY 4/20/1979 5/15/1979 25 6 10 

RUBY 5/15/1979 6/18/1979 34 7 9 
188

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

RUBY 6/18/1979 8/6/1979 49 0 0 

RUBY TLD Lost 

RUBY 8/31/1979 10/10/1979 41 8 8 

NANCY 10/28/1978 11/20/1978 23 9 16 

NANCY 11/20/1978 12/21/1978 31 7 9 

NANCY 12/21/1978 1/24/1979 39 9 10 

NANCY 1/24/1979 2/12/1979 19 6 13 

NANCY 2/12/1979 3/16/1979 32 9 12 

NANCY 3/16/1979 4/11/1979 26 8 13 

NANCY 4/11/1979 5/16/1979 35 10 12 

NANCY 5/16/1979 6/19/1979 34 8 10 

NANCY TLD missing 

NANCY TLD lost 

NANCY 8/31/1979 10/10/1979 41 7 7 

PEARL'S Daughter 11/20/1978 12/21/1978 31 7 9 

PEARL'S Daughter 12/19/1978 1/24/1979 36 23 27 

PEARL'S Daughter 1/24/1979 2/12/1979 19 5 11 

PEARL'S Daughter 2/12/1979 3/16/1979 32 10 13 

PEARL'S Daughter 3/16/1979 4/20/1979 35 12 14 

PEARL'S Daughter 4/20/1979 5/15/1979 25 5 8 

PEARL'S Daughter 5/15/1979 6/18/1979 34 11 13 

PEARL'S Daughter 6/18/1979 7/23/1979 35 7 8 

PEARL'S Daughter 7/17/1979 8/31/1979 45 28 26 

PEARL'S Daughter 8/31/1979 10/10/1979 41 5 5 

KATE 9/25/1978 10/23/1978 28 2 3 

KATE 10/23/1978 11/20/1978 28 4 6 

KATE 11/20/1978 12/19/1978 29 3 4 

KATE 12/19/1978 1/24/1979 36 4 5 

KATE 1/24/1979 2/12/1979 19 3 7 

KATE 2/12/1979 3/16/1979 32 5 7 

KATE 3/16/1979 4/11/1979 26 5 8 

KATE 4/11/1979 5/16/1979 35 6 7 

KATE 5/16/1979 6/19/1979 34 5 6 

KATE 6/19/1979 7/21/1979 32 5 7 

KATE 7/21/1979 8/30/1979 40 4 4 

KATE 8/30/1979 10/10/1979 41 0 0 

EDNA 10/23/1978 11/24/1978 32 7 9 

EDNA 11/24/1978 12/16/1978 22 1 2 

EDNA 12/16/1978 1/24/1979 39 9 10 

EDNA 1/24/1979 2/12/1979 19 3 7 
189

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

EDNA 2/12/1979 3/12/1979 28 4 6 

EDNA 3/12/1979 4/11/1979 30 5 7 

EDNA 4/11/1979 5/15/1979 34 4 5 

EDNA 5/15/1979 6/15/1979 31 5 7 

EDNA TLD missing 

EDNA 7/17/1979 8/21/1979 35 1 1 

EDNA 8/21/1979 10/10/1979 50 12 10 

DAISY 9/25/1978 10/30/1978 35 4 5 

DAISY 10/30/1978 11/20/1978 21 3 6 

DAISY 11/20/1978 12/16/1978 36 4 5 

DAISY 12/16/1978 1/24/1979 39 3 3 

DAISY 1/24/1979 2/12/1979 19 4 9 

DAISY 2/12/1979 3/12/1979 28 4 6 

DAISY 3/12/1979 4/11/1979 30 6 8 

DAISY 4/11/1979 5/15/1979 34 5 6 

DAISY 5/15/1979 6/15/1979 31 6 8 

DAISY 6/15/1979 7/30/1979 45 5 5 

DAISY 7/30/1979 8/21/1979 22 6 11 

DAISY 8/21/1979 10/10/1979 50 5 4 

CLARA 9/25/1978 10/30/1978 35 4 5 

CLARA 10/30/1978 11/13/1978 14 1 3 

CLARA 11/13/1978 12/16/1978 33 3 4 

CLARA 12/16/1978 1/24/1979 39 5 5 

CLARA 1/24/1979 2/12/1979 19 4 9 

CLARA 2/12/1979 3/12/1979 28 4 6 

CLARA 3/12/1979 4/11/1979 30 5 7 

CLARA 4/11/1979 5/15/1979 34 7 9 

CLARA 5/15/1979 6/15/1979 31 3 4 

CLARA 6/15/1979 7/30/1979 45 10 9 

CLARA 7/30/1979 8/22/1979 23 5 9 

CLARA 8/21/1979 10/10/1979 50 2 2 

IRENE (TLD SET #1)§ 6/21/1978 7/21/1978 30 12‡ 17‡

IRENE (TLD SET #1)§ 7/22/1978 8/22/1978 31 14 19 

IRENE (TLD SET #1)§ No TLD data for Sept/Oct 1978 

IRENE (TLD SET #1)§ 10/23/1978 11/24/1978 32 27 35 

IRENE (TLD SET #1)§ 11/24/1978 12/21/1978 27 44 68 

IRENE (TLD SET #1)§ 12/21/1978 1/25/1979 35 68 81 

IRENE (TLD SET #1)§ 1/25/1979 2/13/1979 19 41 90 

IRENE (TLD SET #1)§ 2/12/1979 3/16/1979 32 58 76 

IRENE (TLD SET #1)§ 3/16/1979 4/17/1979 32 76 99 
190

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

IRENE (Pit) (TLD SET #1)§ 4/17/1979 5/15/1979 28 66 98 

IRENE (Pit) (TLD SET #1)§ 5/15/1979 6/15/1979 31 7 9 

IRENE (Pit) (TLD SET #1)§ 6/15/1979 7/21/1979 37 66 74 

IRENE (Pit) (TLD SET #1)§ 7/21/1979 8/21/1979 31 72 97 

IRENE (Pit) (TLD SET #1)§ 8/21/1979 10/10/1979 50 75 63 

IRENE (TLD SET #2)§ 9/25/1978 10/23/1978 28 0 0 

IRENE (TLD SET #2)§ 10/23/1978 11/24/1978 32 10 13 

IRENE (TLD SET #2)§ 11/24/1978 12/21/1978 27 6 9 

IRENE (TLD SET #2)§ 12/21/1978 1/25/1979 35 6 7 

IRENE (TLD SET #2)§ 1/25/1979 2/13/1979 19 5 11 

IRENE (TLD SET #2)§ 2/12/1979 3/16/1979 32 7 9 

IRENE (TLD SET #2)§ 3/16/1979 4/17/1979 32 8 10 

IRENE (Bunker) (TLD SET #2)§ 4/17/1979 5/15/1979 28 4 6 

IRENE (Bunker) (TLD SET #2)§ 5/15/1979 6/20/1979 36 10 12 

IRENE (Bunker) (TLD SET #2)§ 6/15/1979 7/21/1979 37 9 10 

IRENE (Bunker) (TLD SET #2)§ 7/21/1979 8/21/1979 31 8 11 

IRENE (Bunker) (TLD SET #2)§ 8/21/1979 10/10/1979 50 8 7 

VERA 6/22/1978 7/22/1978 30 6‡ 8‡

VERA TLD lost 

VERA 9/25/1978 10/30/1978 35 2 2 

VERA 10/30/1978 11/21/1978 22 1 2 

VERA 11/21/1978 12/15/1978 24 5 9 

VERA 12/15/1978 1/25/1979 41 1 1 

VERA 1/25/1979 2/12/1979 18 1 2 

VERA 2/12/1979 3/16/1979 32 2 3 

VERA 3/16/1979 4/17/1979 32 3 4 

VERA 4/11/1979 5/15/1979 34 3 4 

VERA 5/15/1979 6/21/1979 37 4 5 

VERA 6/21/1979 8/6/1979 46 5 5 

VERA 8/4/1979 8/31/1979 26 4 6 

VERA 8/31/1979 10/10/1979 40 2 2 

SALLY (Hotline) 6/21/1978 7/21/1978 30 6‡ 8‡

SALLY (Hotline) 7/22/1978 8/22/1978 31 3 4 

SALLY (Hotline) No TLD data for Sept/Oct 1978 

SALLY (Hotline) 10/23/1978 11/16/1978 24 2 3 

SALLY (Hotline) 11/16/1978 12/19/1978 33 1 1 

SALLY (Hotline) TLD lost in storm 

SALLY (Hotline) 1/23/1979 2/12/1979 20 4 8 

SALLY (Hotline) 2/12/1979 3/13/1979 29 2 3 

SALLY (Hotline) 3/13/1979 4/18/1979 36 3 3 
191

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

SALLY (Hotline) 4/18/1979 5/15/1979 27 2 3 

SALLY (Hotline) 5/15/1979 6/20/1979 36 0 0 

SALLY (Hotline) TLD missing 

SALLY (Crypt) 9/26/1978 10/23/1978 27 2 3 

SALLY (Crypt) 10/23/1978 11/16/1978 24 4 7 

SALLY (Crypt) 11/16/1978 12/19/1978 33 4 5 

SALLY (Crypt) 12/19/1978 1/23/1979 35 5 6 

SALLY (Crypt) 1/23/1979 2/12/1979 20 5 10 

SALLY (Crypt) 2/12/1979 3/13/1979 29 5 7 

SALLY (Crypt) 3/13/1979 4/18/1979 36 8 9 

SALLY (Crypt) 4/18/1979 5/15/1979 27 7 11 

SALLY (Crypt) TLD lost 

WILMA 6/21/1978 7/21/1978 30 5 7 

WILMA 7/22/1978 8/22/1978 31 15 20 

WILMA No TLD data for Sept/Oct 1978 

WILMA 10/30/1978 11/20/1978 21 1 2 

WILMA 11/22/1978 12/15/1978 23 1 2 

WILMA 12/19/1978 1/25/1979 37 2 2 

WILMA 1/25/1979 2/12/1979 18 0 0 

WILMA 2/12/1979 3/16/1979 32 2 3 

WILMA 3/16/1979 4/11/1979 26 2 3 

WILMA 4/11/1979 5/15/1979 34 1 1 

WILMA 5/15/1979 6/21/1979 37 1 1 

WILMA 6/21/1979 8/6/1979 46 2 2 

WILMA 8/6/1979 8/30/1979 24 2 3 

WILMA 8/30/1979 10/10/1979 41 1 1 

LUCY 9/25/1978 10/23/1978 28 0 0 

LUCY 10/23/1978 11/20/1978 28 4 6 

LUCY 11/20/1978 12/19/1978 29 2 3 

LUCY 12/19/1978 1/24/1979 36 5 6 

LUCY 1/24/1979 2/12/1979 19 3 7 

LUCY 2/12/1979 3/16/1979 32 4 5 

LUCY 3/16/1979 4/11/1979 26 5 8 

LUCY 4/11/1979 5/16/1979 35 5 6 

LUCY 5/16/1979 6/19/1979 34 4 5 

LUCY 6/19/1978 7/21/1978 32 5 7 

LUCY 7/21/1978 8/30/1979 40 3 3 

LUCY 8/30/1979 10/10/1979 41 2 2 

RUNIT (N. Boat Ramp) 6/21/1978 7/21/1978 30 7‡ 10‡

RUNIT (N. Boat Ramp) TLD lost 
192

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

RUNIT (N. Boat Ramp) 9/25/1978 10/17/1978 22 7 13 

RUNIT (N. Boat Ramp) 10/23/1978 11/17/1978 25 1 2 

RUNIT (N. Boat Ramp) 11/17/1978 12/19/1978 32 3 4 

RUNIT (N. Boat Ramp) TLD lost in storm 

RUNIT (N. Boat Ramp) 2/13/1979 3/16/1979 31 0 0 

RUNIT (N. Boat Ramp) 3/16/1979 4/17/1979 32 5 7 

RUNIT (N. Boat Ramp) 4/17/1979 5/16/1979 29 4 6 

RUNIT (N. Boat Ramp) TLD lost 

RUNIT (N. Boat Ramp) 6/22/1979 7/17/1979 25 3 5 

RUNIT (N. Boat Ramp) TLD lost 

RUNIT (N. Boat Ramp) 8/22/1979 10/10/1979 49 1 1 

RUNIT (S. Quarry) 6/21/1978 7/21/1978 30 4 6 

RUNIT (S. Quarry) 7/22/1978 8/22/1978 31 0 0 

RUNIT (S. Quarry) 9/25/1978 10/18/1978 23 1 2 

RUNIT (S. Quarry) 10/23/1978 11/17/1978 25 8 13 

RUNIT (S. Quarry) 11/17/1978 12/19/1978 32 3 4 

RUNIT (S. Quarry) TLD lost in storm 

RUNIT (S. Quarry) 2/13/1979 3/16/1979 31 2 3 

RUNIT (S. Quarry) 3/16/1979 4/17/1979 32 5 7 

RUNIT (S. Quarry) TLD lost 

RUNIT (S. Quarry) 5/16/1979 6/22/1979 37 1 1 

RUNIT (S. Quarry) 6/22/1979 7/17/1979 25 2 3 

RUNIT (S. Quarry) 7/27/1979 8/24/1979 28 1 1 

RUNIT (Cactus Crater) 6/21/1978 7/21/1978 30 22‡ 31‡

RUNIT (Cactus Crater) TLD lost 

RUNIT (Cactus Crater) 9/25/1978 10/18/1978 23 13 24 

RUNIT (Cactus Crater) 10/23/1978 11/17/1978 25 15 25 

RUNIT (Cactus Crater) 11/17/1978 12/19/1978 32 12 16 

RUNIT (Cactus Crater) TLD lost in storm 

RUNIT (Cactus Crater) 1/24/1979 2/13/1979 20 11 23 

RUNIT (Cactus Crater) 2/13/1979 3/16/1979 31 15 20 

RUNIT (Cactus Crater) TLD lost 

RUNIT (Cactus Crater) 4/17/1979 5/16/1979 29 20 29 

RUNIT (Cactus Crater) 5/16/1979 6/22/1979 37 21 24 

RUNIT (Cactus Crater) 6/22/1979 7/17/1979 25 13 22 

RUNIT (Cactus Crater) 7/27/1979 8/24/1979 28 17 25 

RUNIT (Cactus Crater) 8/22/1979 10/10/1979 49 15 13 

RUNIT (Hotline) 6/21/1978 7/21/1978 30 15 21 

RUNIT (Hotline) TLD lost 

RUNIT (Hotline) 9/25/1978 10/18/1978 23 0 0 
193

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

RUNIT (Hotline) 10/23/1978 11/17/1978 25 1 2 

RUNIT (Hotline) 11/17/1978 12/19/1978 32 0 0 

RUNIT (Hotline) 12/19/1978 1/20/1979 32 1 1 

RUNIT (Hotline) 1/24/1979 2/13/1979 20 2 4 

RUNIT (Hotline) 2/13/1979 3/16/1979 31 2 3 

RUNIT (Hotline) 3/16/1979 4/17/1979 32 3 4 

RUNIT (Hotline) 4/17/1979 5/16/1979 29 0 0 

RUNIT (Hotline) 5/16/1979 6/22/1979 37 1 1 

RUNIT (Hotline) 6/22/1979 7/17/1979 25 3 5 

RUNIT (Hotline) 7/27/1979 8/24/1979 28 0 0 

RUNIT (Hotline) 8/22/1979 10/10/1979 49 1 1 

RUNIT (Debris Pile) 6/21/1978 7/21/1978 30 Reading malfunction 

RUNIT (Debris Pile) TLD lost 

RUNIT (Debris Pile) 9/25/1978 10/18/1978 23 1380 2500 

RUNIT (FRST Shack) 12/19/1978 1/24/1979 36 2 2 

RUNIT (FRST Shack) 1/24/1979 2/13/1979 20 2 4 

RUNIT (FRST Shack) 2/13/1979 3/16/1979 31 3 4 

RUNIT (FRST Shack) 3/16/1979 4/17/1979 32 3 4 

RUNIT (FRST Shack) 4/17/1979 5/16/1979 29 2 3 

RUNIT (FRST Shack) 5/16/1979 6/22/1979 37 2 2 

RUNIT (FRST Shack) 6/22/1979 7/17/1979 25 1 2 

RUNIT (FRST Shack) 7/27/1979 8/24/1979 28 1 1 

RUNIT (FRST Shack) 8/22/1979 10/10/1979 49 2 2 

LOJWA (FRST) 7/22/1978 8/22/1978 31 2 3 

LOJWA (FRST) 9/25/1978 10/21/1978 26 1 2 

LOJWA (FRST) 10/21/1978 11/16/1978 26 1 2 

LOJWA (FRST) 11/16/1978 12/19/1978 33 0 0 

LOJWA (FRST) 12/19/1978 1/23/1979 35 0 0 

LOJWA (FRST) 1/23/1979 2/13/1979 20 2 4 

LOJWA (FRST) 2/13/1979 3/13/1979 28 1 1 

LOJWA (FRST) 3/13/1979 4/18/1979 36 2 2 

LOJWA (FRST) 4/18/1979 5/15/1979 27 2 3 

LOJWA (FRST) 5/15/1979 6/20/1979 36 2 2 

LOJWA (FRST) 5/15/1979 6/23/1979 39 1 1 

LOJWA (FRST) 7/18/1979 8/24/1979 37 1 1 

LOJWA (FRST) 8/22/1979 10/10/1979 45 0 0 

LOJWA (PMEL) 10/21/1978 11/16/1978 26 1 2 

LOJWA (PMEL) 11/16/1978 12/19/1978 33 0 0 

LOJWA (PMEL) 12/19/1978 1/23/1979 35 0 0 

LOJWA (PMEL) 1/23/1979 2/13/1979 20 1 2 
194

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

LOJWA (PMEL) 2/13/1979 3/13/1979 28 1 1 

LOJWA (PMEL) 3/13/1979 4/18/1979 36 2 2 

LOJWA (PMEL) 4/18/1979 5/15/1979 27 0 0 

LOJWA (PMEL) 5/15/1979 6/20/1979 36 2 2 

LOJWA (PMEL) 6/20/1979 7/18/1979 28 1 1 

LOJWA (PMEL) 7/18/1979 8/24/1979 37 0 0 

LOJWA (PMEL) 8/22/1979 10/10/1979 45 1 1 

LOJWA (Mess Hall) 10/21/1978 11/16/1978 26 1 2 

LOJWA (Mess Hall) 11/16/1978 12/19/1978 33 0 0 

LOJWA (Mess Hall) 12/19/1978 1/23/1979 35 1 1 

LOJWA (Mess Hall) 1/23/1979 2/13/1979 20 1 2 

LOJWA (Mess Hall) 2/13/1979 3/13/1979 28 1 1 

LOJWA (Mess Hall) 3/13/1979 4/18/1979 36 1 1 

LOJWA (Mess Hall) 4/18/1979 5/15/1979 27 0 0 

LOJWA (Mess Hall) 5/15/1979 6/20/1979 36 1 1 

LOJWA (Mess Hall) TLD missing 

LOJWA (Mess Hall) TLD missing 

LOJWA (Mess Hall) 8/24/1979 10/10/1979 47 2 2 

TILDA (FRST Bunker) 6/21/1978 7/22/1978 31 5‡ 7‡

TILDA (FRST Bunker) 7/22/1978 8/22/1978 31 2 3 

TILDA (FRST Bunker) 9/25/1978 10/21/1978 26 1 2 

TILDA (FRST Bunker) No TLD data for Oct/Nov 1978 

TILDA (FRST Bunker) 11/16/1978 12/19/1978 33 0 0 

TILDA (FRST Bunker) 12/19/1978 1/23/1979 35 1 1 

TILDA (FRST Bunker) 1/23/1979 2/13/1979 20 0 0 

TILDA (FRST Bunker) 2/12/1979 3/13/1979 29 2 3 

TILDA (FRST Bunker) 3/13/1979 4/18/1979 36 3 3 

TILDA (FRST Bunker) 4/18/1979 5/15/1979 27 1 2 

TILDA (FRST Bunker) TLD lost 

TILDA (FRST Bunker) 6/20/1979 7/18/1979 28 1 1 

TILDA (FRST Bunker) 7/18/1979 8/24/1979 37 0 0 

TILDA (FRST Bunker) 8/24/1979 10/10/1979 47 0 0 

TILDA (EOD Small Bunker) 10/23/1978 11/16/1978 24 3 5 

TILDA (EOD Small Bunker) 11/16/1978 12/19/1978 33 1 1 

TILDA (EOD Small Bunker) 12/19/1978 1/23/1979 35 2 2 

TILDA (EOD Small Bunker) 1/23/1979 2/13/1979 20 2 4 

TILDA (EOD Small Bunker) 2/12/1979 3/13/1979 29 2 3 

TILDA (EOD Small Bunker) 3/13/1979 4/18/1979 36 2 2 

TILDA (EOD Small Bunker) 4/18/1979 5/15/1979 27 1 2 

TILDA (EOD Small Bunker) 5/15/1979 6/20/1979 36 3 3 
195

Island DOI* DOR† Days Net Reading 

(mR) 

Net Exposure 

Rate 

(μR h−1) 

TILDA (EOD Small Bunker) 6/20/1979 7/18/1979 28 2 3 

TILDA (EOD Small Bunker) 7/18/1979 8/24/1979 37 2 2 

TILDA (EOD Small Bunker) No TLD data for Aug/Oct 1979 

*

 DOI means date of issue 

†

 DOR means date of return 

‡

 This cell contains the gross reading from the TLD instrument and the corresponding exposure rate is based on 

the uncorrected reading. 

§

 IRENE (TLD SET #2) and IRENE (TLD SET #1) are designated in AEC (1973b) as Irene A and Irene B. 
196

B-2. Average TRU Soil Activity Concentrations – Excised Soil Disposed in Cactus Crater 

and Dome 

Estimated activity concentrations in excised soil are based on total estimated TRU 

activity and the total volume of soil removed from each contaminated island as reported in DNA 

(1981). The estimated concentrations and the volume of soil removed from each island are 

presented in Table B-2. The estimated concentrations of TRU for each island shown in Table B-2

include the total amount of contaminated soil that was disposed of in Cactus Crater and dome. 

For Aomon crypt, Boken and Enjebi, removed contaminated soil was disposed of in the 

Cactus Crater during tremie operations and Cactus dome during soil-cement mix operations. For 

Aomon and Medren, disposal occurred only in the Cactus Crater and for Lujor and Runit, 

disposal occurred only in the Cactus dome. Estimates of the TRU activity of the soil removed 

from Aomon crypt, Boken, and Enjebi, which was contained in the Cactus Crater or in the 

Cactus dome, are given in Table B-3 and Table B-4, respectively. 

Table B-2. Estimated average TRU activity of excised soil disposed 

in Cactus Crater and dome 

Island 

 Total 

Island TRU 

(Ci)*

Soil Volume (yd3)

*

Average TRU 

Activity 

(Crater + Dome) 

Crater Dome Total 

Volume (pCi cm−3

) (pCi g−1

)

†

Medren 0 110 0 110 0 0 

Aomon 1.29 10,603 0 10,603 159 106 

Aomon Crypt 0.93 448 9,328 9,776 124 83 

Boken 1.01 421 4,516 4,937 268 178 

Enjebi 2.57 43,023 9,984 53,007 64 42 

Lujor 1.7 0 14,929 14,929 149 99 

Runit 7.22 0 10,735 10,735 880 587 

Weighted 

Average 

(without Runit)

7.5‡54,605‡38,757‡93,362‡105§70§

Weighted 

Average 

 (with Runit)

14.72‡54,605‡49,492‡104,097‡185§123§

*

 Total TRU activity and soil volume data are from table shown in Figure 8-34 "Contaminated Material 

Cleanup/Containment" (DNA, 1981). 

† To estimate values in this table column, the soil bulk density = 1.50 g cm−3

. 

‡

 These values are totals. 

§

 The weighted average TRU soil activity concentration is estimated as the total activity divided by total soil 

volume.
197

Table B-3. Estimated TRU activity of excised soil disposed in Cactus Crater 

Island

Total 

Island 

TRU (Ci)

Soil 

Volume

(yd3)

Average 

TRU Activity

(Ci yd−3)

*

TRU in 

Crater

(Ci)*

Average TRU Activity

(Crater)

(pCi cm−3) (pCi g−1) 

Medren 0 110 0.0 0 0 

Aomon 1.29 10,603 0.000122 1.29 159 106 

Aomon Crypt 0.93 448 0.000095 0.04 125 83 

Boken 1.01 421 0.000205 0.09 268 178 

Enjebi 2.57 43,023 0.000048 2.09 64 42 

Lujor 1.7 0 0.000114 0.0 

Runit 7.22 0 0.000673 0.0 

Total Soil Volume 

and Weighted

Average Activity 

Concentration 

(Crater)

54,605 0.000064 3.50 56 

*

 Island-based TRU activity concentration (Ci yd−3) derived from Table B-2 (crater + dome) is used to estimate 

TRU activity for each island soil going to Cactus Crater from Aomon crypt, Boken and Enjebi. 

Table B-4. Estimated TRU activity of excised soil disposed in Cactus dome 

Island 

Total 

Island 

TRU (Ci)*

Soil 

Volume

(yd3) 

Average 

TRU Activity

(Ci yd−3)

*

TRU in

Dome 

(Ci)*

Average TRU Activity 

(Dome) 

(pCi cm−3) (pCi g−1) 

Medren 0 0 0.0 

Aomon 0 0 0.000122 0.0 

Aomon Crypt 0.93 9,328 0.000095 0.89 124.43 83.0 

Boken 1.01 4,516 0.000205 0.92 267.59 178.4 

Enjebi 2.57 9,984 0.000048 0.48 63.42 42.3 

Lujor 1.7 14,929 0.000114 1.70 148.95 99.3 

Runit 7.22 10,735 0.000673 7.22 879.72 586.5 

Total Soil Volume 

and Weighted

Average Activity 

Concentration 

(Dome)

49,492 0.000227 11.22 197.6 

*

 Island-based activity per cubic yard of soil derived from Table B-2 (Crater + Dome) is used to estimate TRU 

activity for each island soil going to Cactus dome from Aomon crypt, Boken and Enjebi. 
198

B-3. Example Weekly Air Sampling and TLD Data Summaries Extracted from a CJTG 

Situation Report (SITREP) 

The JTG prepared and submitted weekly SITREPs on various topics of interest to DNA 

and DoD. Included in SITREPs are weekly summaries of air sampling and TLD results as shown 

in Figure B-1. Air sample results are summarized in columns labeled AAA through GGG and 

have the following meanings: 

AAA = Volume of air sampled during time period in cubic meters 

BBB = Number of air filters counted during time period 

CCC = Number of filters which yield no detectable activity 

DDD = Number of filters showing values less than 0.01 MPC (0.27 pCi m−3) 

EEE = Number of filters showing average activity equal to or greater than 0.01 MPC, 

but less than 0.1 MPC (0.27 to 2.7 pCi m−3) 

FFF = Number of filters showing average activity equal to or greater than 0.1 MPC 

(2.7 pCi m−3) 

GGG = Maximum value read from any one filter during period (in pCi m−3). 
199

Figure B-1. Example weekly summaries of air sampling and TLD results extracted from 

CJTG Enewetak Cleanup SITREP No 66, week ending August 20, 1978 
200

Appendix C. 

Dose Calculation Methods 

This appendix contains equations for calculating external and internal doses for ECUP 

participants. Propagation of uncertainties associated with combining external doses from 

different dose categories, such as reconstructed, film badge, TLD, and doses from different 

scenarios, for both external and internal doses, are addressed. Upper-bound dose calculations are 

described as well. 

C-1. External Dose Calculations 

External doses described in this section for ECUP participants are the external doses that 

would be recorded on a properly worn dosimeter. In DTRA’s NTPR program, these doses are 

referred to as “film badge doses” (DTRA, 2017, SM ED01). 

C-1.1. External Dose from Contaminated Soil 

The dose from exposure to a contaminated soil surface is estimated using Equation C-1 

(DTRA, 2017, SM ED02): 

 = ̇

 ×  ×  × 

(C-1)

where 

Dext = Dose due to working on or visiting an island (rem) 

̇

 = Exposure rate for island (R h−1

) 

Tact = Time duration of work activities or visits to the island (h) 

 = Film badge conversion factor (rem R−1) 

FExt = Exposure factor for external exposure (unitless) 

The dose from exposure to soil piles, windrows, or other bulk soil is estimated using 

Equation C-2a: 

 = ̇

 ×  ×  × 

(C-2a)

where 

Dpile = Dose due to working near bulk soil (rem) 

̇

 = Exposure rate of bulk soil (R h−1

) 
201

The dose from exposure to a bulk soil pile like the one transported on an LCU described 

in the example scenario in Section 8, the exposure rate from the bulk soil in the LCU can be 

estimated using Equation C-2b: 

̇

 = ̇ ×





(C-2b)

where 

dmeas = Distance from the soil surface at which the island exposure rate was measured (m)

dLCUsoil = Average distance of a veteran from bulk soil during transport in an LCU (m) 

Exposure rates from contaminated soil on each island are shown in Section 4 and their 

use is discussed in Section 6, including for scenarios involving multiple islands. The film badge 

conversion factor (FB) in Equations C-1 and C-2 is the ratio of the dose recorded on a properly 

worn film badge to the free-in-air integrated exposure. This factor accounts for body shielding of 

a film badge worn on the front of the body from gamma radiation emanating from a 

contaminated source behind an individual. The film badge conversion factor is assigned a value 

of 0.7 for the standing position on a planar field, when the contaminated surface is below and 

partially behind the individual. It is assigned a value of 1.0 for an individual facing the source of 

radiation, e.g., a pile of contaminated soil, where there is no body shielding between the source 

and the film badge) (DTRA, 2017, SM ED02). The exposure factor (FExt) accounts for the 

fraction of time that an individual is near the source of radiation during a workday. 

C-1.2. External Dose from other Sources 

For external doses from sources other than soil (e.g., contaminated debris), the term for 

exposure rate for an island or from bulk soil in the equations above should be replaced by the 

estimated or measured exposure rate from the specific source. In addition, applicable values for 

the film badge conversion factor and the exposure factor must be used. Exposure rates applicable 

to debris-handling scenarios are discussed in Appendix K. 

C-1.3. External Dose on Residence Islands 

For external dose estimates while on a residence island, one of the two following 

equations, C-3a or C-3b, should be used: 

 = ̇

 ×  ×  ×  +

(1 − )



 (C-3a)

where 

Dext = External dose (rem) 

FB = Film badge conversion factor (rem R−1) 

̇



= Exposure rate for island (R h−1) 

TDur = Total duration of exposure (h) 

FO = Average fraction of time the participant spent outside 

PF = Protection factor for land-based structures 
202

 = ̇

 ×  ×  ×  +





 (C-3b)

where 

Tdays = Number of days living on the residence island (d) 

Tod = Average daily time outdoors (h d−1) 

Tid = Average daily time indoors (h d−1) 

C-1.4. External Dose from Seawater Immersion 

The following equation shows the calculation of the external dose rate from immersion in 

seawater. Since Cs-137 is the only key radionuclide of concern for external exposure in seawater 

(Section 4.5), it is specified in the equation below. The Cs-137+Ba-137m dose coefficient for 

effective dose for this exposure pathway is 6.2610−17 Sv s−1 per Bq m−3. Organ dose 

coefficients are similar to this value, and are available in USEPA (1993). 

̇

 =  × . ×   (C-4)

where 

̇



= Dose rate from immersion in seawater (rem h−1) 

Csw = Concentration of Cs-137 in seawater (fCi L−l) 

DCwater.imm = Dose coefficient for immersion in water (organ or effective dose) 

for Cs-137 (Sv s−1 per Bq m−3) 

and 

  = (3.7 × 10 Bq fCi

) × (10

 L m-3) × (3600 s h

) × (100  



)

C-1.5. External Dose from Sediment 

The external dose rate from standing above exposed sediment at Enewetak Atoll is 

calculated using Equation C-5. Applicable dose coefficients are shown in Table C-1. The 

shielding provided by the water that is likely to be on top of sediment is ignored to high side the 

dose rate. 

̇

 = , × , ×  





(C-5)

where 

̇



= Dose rate from standing above sediment (rem h−1) 

Csed,i = Concentration of each radionuclide i in sediment (mCi km−2) 

DCsurf,i = Dose coefficient for exposure to surface of contaminated lagoon sediment for 

each radionuclide i in sediment (organ or effective dose) (Sv s−1 per Bq m−2) 
203

and 

 

= (10  ) × (3.70 × 10  



) × (3600  h



) × (100  



)

Table C-1. Dose coefficients for estimating external exposure to 

contaminated sediment 

Radionuclide Dose Coefficient*

(Sv s−1 per Bq m−2) 

Co-60 2.35  10−15

Sr-90+Y-90 5.60  10−18

Rh-101 2.55  10−16

Rh-102m 4.76  10−16

Sb-125 4.25  10−16

Cs-137+Ba-137m 5.86  10−16

Eu-152 1.10  10−15

Eu-155 5.90  10−17

Bi-207 1.48  10−15

Pu-239 3.67  10−19

Am-241 2.75  10−17

*

 Dose coefficients are for effective dose, for exposure to contaminated 

ground surface (USEPA, 1993, Table III.3).

C-1.6. Total External Dose and Upper-bound Doses 

The total external dose for an individual is the sum of all reconstructed doses, valid film 

badge readings, and valid TLD readings. For n reconstructed doses, valid film badge readings, or 

valid TLD readings, the total external dose is calculated using the following equation: 

 = , + , + ,













(C-6)

where 

Dγ = Total whole body external dose (rem) 

Dγ,i = The i

th component of the total reconstructed dose (rem) 

DFB,i = The i

th component of the total film badge dose (rem) 

DTLD,i = The i

th component of the total TLD dose (rem) 
204

The total upper-bound external dose is calculated by estimating the upper-bound 

uncertainties from each category of external dose (reconstructed, film badge, and TLD), and then 

combining and adding them to the sum of external doses (DTRA, 2017, SM UA01). Note that if 

film badges are part of the upper-bound calculation, the sum of the bias-corrected film badge 

readings is used with its associated uncertainty. Recommended uncertainty factors are discussed 

in Section 6.4. The uncertainty associated with each category of external dose is calculated as 

follows: 

, = , × ( − 1)

, = 

,



× , − 1

, = 



+ 



(C-7)

The uncertainty components for TLD doses in Equation C-7 ( and ) are defined 

in Appendix D, including the method used to calculate them. 

The uncertainties are then combined in quadrature, and the total upper-bound external gamma 

dose is calculated as follows: 

 =  + ,









+ ,









+ ,









(C-8)

where 

uγ,i = Uncertainty associated with the i

th component of the total reconstructed dose 

(rem) 

uFB,i = Uncertainty associated with the i

th component of the total mean film badge dose 

(rem) 

uTLD,i = The uncertainty associated with the i

th component of the total TLD dose (rem) 

UFext = Uncertainty factor for reconstructed whole body external gamma doses 

UFFB,i = Uncertainty factor for each valid film badge reading i

BFi = Bias factor to convert each valid film badge reading i to a mean dose 

UBγ = Total upper-bound whole body external dose (rem) 
205

C-2. Internal Dose Calculations 

C-2.1. Inhalation of Suspended Soil 

The dose from inhalation of suspended contaminated soil during soil disturbance 

activities when air sampling data are not available is estimated with Equation C-9a using a 

resuspension factor, or with Equation C-9b using a mass loading value. The resuspension factor 

is used with the calculated surface activity density (pCi cm−2), which is estimated assuming a 

nominal soil thickness that is available for resuspension. The mass loading value estimates the 

airborne soil loading, and is used with an enhancement factor to account for higher 

concentrations of contaminants in suspended soil as compared to undisturbed soil. These 

equations can be used with excised (removed) soil or undisturbed soil. When used with excised 

soil and the total TRU activity (total curies) is accounted for, the calculation can be limited to 

Pu-239 activity as described in Appendix G. 

. = 

 × , ×  × h ×  × , ×  × 







×   (C-9a)

where 

Dsoil.inh = Inhalation dose from suspended contaminated soil (rem) 

BR = Breathing rate (m3 h−1) 

Csoil,i = Soil activity concentration of radionuclide i (pCi g−1) 

ρ = Soil density (g cm−3) 

Thsoil = Soil layer thickness available for resuspension (cm) 

Ksusp = Resuspension factor (m−1) 

DCinh,i = Inhalation dose coefficient for radionuclide i (rem pCi−1) 

Tsoil = Time spent in contaminated area (h) 

Finh = Exposure factor for inhalation (unitless) 

RPF = Respiratory protection factor (unitless) 

And Units conversion = 104 cm2 m−2

. = 

 × , ×  ×  × , ×  × 







(C-9b)

where 

ML = Mass loading of airborne soil (g m−3) 

EF = Enhancement factor (unitless) 

For the airborne soil inhalation pathway, activity concentrations in soil are either island 

averages (Section 4) or calculated average values (e.g., for excised soil) (Section 7). These 

activity concentrations could be for one island or for multiple islands as described in Section 6. 

ICRP worker inhalation dose coefficients are used, assuming an AMAD of 1.0 μm and

absorption type corresponding to unspecified compounds (ICRP, 2011). These assumptions were 
206

made in order to produce high-sided estimates of inhalation doses to internal organs. Plutonium 

and other contaminants at Enewetak may exist in multiple chemical forms (e.g., Robison and 

Noshkin, 1998). The assumption of “unspecified compounds” is high-siding because it results in 

the use of inhalation dose coefficients that are generally higher than those associated with other 

compounds such as insoluble oxides by factors of about 9–20 for Sr-90 and Pu-239 (the lungs are 

an exception to this generalization) (ICRP, 2011). The higher dose coefficients are due to the 

higher degree of absorption from the lungs; absorption types associated with unspecified 

compounds are Type F (Sr-90, Cs-137) and Type M (Co-60, Sb-125, Eu-155, Pu-239, Am-241). 

The inhalation dose coefficients recommended for use in ECUP dose assessments are shown in 

Table C-2. 

Respiratory protection factors are discussed in Appendix F. The exposure factor for 

inhalation (Finh) accounts for the fractional time in a workday that an ECUP worker is actually 

exposed to suspended airborne soil; values of 0.1 to 1.0 can be used. 

When representative air sampling data are available, the dose from inhalation of 

suspended contaminated soil can be estimated with Equation C-10. 

. = 

 ×  ×  × ,







(C-10)

where 

ACi = Measured air concentration of radionuclide i (pCi m−3) 

Use of equation C-10 will usually be based on measured air concentrations of 

Pu-239/240, and estimation of the concentrations of other radionuclides based on their relative 

concentrations in the soil that is the source of the suspended radionuclides measured. When 

measured air concentrations of Pu-239/240 are used, estimation of other radionuclide 

concentrations in air is required for exposures involving either excised or undisturbed soil. The 

air concentrations used in Equation C-10 (ACi) should be representative of the average 

concentrations over the entire period of exposure (Tsoil). This may require averaging multiple air 

concentration measurements taken over the period of exposure or taken at other times or 

locations with similar conditions of exposure. 
207

C-2.2. Incidental Ingestion of Soil and Dust 

The dose from incidental ingestion of contaminated soil and dust is estimated as follows: 

. =   ×  × , × ,





(C-11)

where 

Dinc.ing = Dose from incidental ingestion of contaminated soil and dust (rem) 

qsoil = Incidental soil and dust ingestion rate (g d−1) 

Tsoil = Time spent in contaminated area (d) 

Csoil,i = Soil activity concentration of radionuclide i (pCi g−1) 

DCing,i = Ingestion dose coefficient for radionuclide i (rem pCi−1) 

This equation can be applied for exposures involving excised or undisturbed soil. For 

most incidental ingestion scenarios (e.g., incidental ingestion of undisturbed soil on a residence 

island), average island-specific activity concentrations for all radionuclides and the applicable 

radionuclide dose coefficients would be used. The ICRP 68 ingestion dose coefficients 

recommended are based on f1 absorption fractions of 0.3 (Sr-90), 0.1 (Co-60, Sb-125), 

1.0 (Cs-137), and 0.0005 (Eu-155, Pu-239, Am-241) (ICRP, 2011). The ingestion dose 

coefficients recommended for use in ECUP dose assessments are shown in Table C-3. 

C-2.3. Consumption of Local Food 

Internal doses have been estimated for the potential consumption of locally gathered food 

by ECUP participants. The unit doses and a description of the assessment of these potential 

organ doses is described in detail in Appendix M. 

C-2.4. Total Internal Dose and Upper-bound Doses 

In most cases, internal doses for ECUP participants will be estimated using 

environmental data, exposure scenario assumptions, and appropriate dose coefficients as 

described above. The total internal dose for an individual is simply the sum of internal doses 

from all sources. Using guidance from DTRA’s NTPR program, internal dose uncertainties may 

be combined assuming that all internal component doses are fully correlated (DTRA, 2017, 

SM UA01). This means that the total upper-bound dose to any organ is calculated by applying 

the applicable uncertainty factor to each dose component and summing, as shown below. 

 = ,





(C-12)

 = ( × ,)





(C-13)

where 

Dint = Total internal dose to a specific organ (or effective dose) from all sources of 

intake (rem) 
208

Dint,i = The i

th component of internal dose to a specific organ (or effective dose) (rem) 

UBint = Upper-bound total internal dose to a specific organ (or effective dose) (rem) 

UFint = Uncertainty factor for internal reconstructed doses 

An uncertainty factor (UFint) of 10 is used for reconstructed internal doses as discussed in 

Section 7 (DTRA, 2017, SM UA01). 
209

Table C-2. Inhalation dose coefficients 

Organ/Tissue† 

ICRP 68 Inhalation Dose Coefficients* (rem pCi−1) 

Co-60 Sr-90 Sb-125 Cs-137 Eu-155 Pu-239 Am-241 

Adrenals 2.4110−82.2210−94.0710−91.8110−86.6610−99.2510−69.9910−6

Bladder Wall 8.8810−94.8110−91.1510−91.8510−87.0310−109.2510−69.9910−6

Bone Surface 1.3710−81.3710−63.0310−81.7810−84.0710−75.5510−35.9210−3

Brain 7.0310−92.2210−99.9910−101.5210−89.9910−109.2510−69.9910−6

Breast 2.1510−82.2210−93.5510−91.4410−81.4810−99.2510−69.9910−6

Esophagus 2.5210−82.2210−94.0710−91.6710−81.7410−99.2510−69.9910−6

St Wall 1.5910−82.2910−92.4110−91.7010−82.2610−99.2510−69.9910−6

SI Wall 1.2210−82.4110−91.9210−91.8110−82.4410−99.2510−69.9910−6

ULI Wall 1.4410−87.0310−93.6610−91.8510−84.0710−99.2510−69.9910−6

LLI Wall 1.8110−81.9210−87.4010−92.1510−84.8110−99.2510−69.9910−6

Colon 1.5910−81.2210−85.1810−91.9610−84.4410−99.2510−69.9910−6

Kidneys 1.4110−82.2210−91.9210−91.7410−84.8110−92.1810−53.0010−5

Liver 3.0010−82.2210−94.8110−91.7410−81.3010−71.1110−33.5910−4

Muscle 1.3310−82.2210−92.0710−91.6310−81.7010−99.2510−69.9910−6

Ovaries 1.1510−82.2210−91.6710−91.8510−81.7010−97.0310−51.1510−4

Pancreas 2.0010−82.2210−93.0710−91.8510−85.1810−99.2510−69.9910−6

Red Marrow 1.5210−85.9210−75.9210−91.6710−83.6310−82.5910−42.0410−4

ET Airways 6.2910−86.6610−92.3310−82.8910−81.2210−83.5210−53.6610−5

Lungs 1.8110−72.2910−91.1110−71.6310−86.2910−81.1110−41.2610−4

Skin 8.5110−92.2210−91.2210−91.3710−88.1410−109.2510−69.9910−6

Spleen 1.8510−82.2210−92.8110−91.7410−81.5910−99.2510−69.9910−6
210

Testes 7.0310−92.2210−97.4010−101.6310−82.9610−107.0310−51.1510−4

Thymus 2.5210−82.2210−94.0710−91.6710−81.7410−99.2510−69.9910−6

Thyroid 1.3310−82.2210−91.8910−91.6710−89.2510−109.2510−69.9910−6

Uterus 9.9910−92.2210−91.2610−91.8510−81.1810−99.2510−69.9910−6

Effective dose 3.5510−88.8810−81.6710−81.7810−82.4110−81.7410−41.4410−4

*

ICRP 68 dose coefficients for a particle size of 1 μm were obtained from ICRP (2011).

†

 Abbreviations used in this table: SI Wall = Small Intestine Wall; ULI Wall = Upper Large Intestine Wall; LLI Wall = Lower Large Intestine Wall; 

ET Airways = Extra-thoracic Airways. 

Table C-3. Ingestion dose coefficients 

Organ/Tissue†

ICRP 68 Ingestion Dose Coefficients* (rem pCi−1) 

Co-60 Sr-90 Sb-125 Cs-137 Eu-155 Pu-239 Am-241 

Adrenals 9.2510−92.4410−91.5510−95.1810−84.8110−115.1810−85.5510−8

Bladder Wall 9.6210−95.5510−9 1.5910−95.1810−81.1110−105.1810−85.5510−8

Bone Surface 7.4010−91.5210−6 3.3310−85.1810−82.4410−93.0310−53.3310−5

Brain 5.1810−92.4410−9 9.6210−10 4.4410−85.5510−125.1810−85.5510−8

Breast 4.8110−92.4410−9 7.7710−10 4.0710−87.0310−125.1810−85.5510−8

Esophagus 6.2910−92.4410−9 9.2510−10 4.8110−87.4010−125.1810−85.5510−8

St Wall 9.2510−93.3310−9 1.8110−94.8110−83.6610−105.5510−85.9210−8

SI Wall 1.5510−84.0710−9 3.5910−95.1810−89.9910−106.2910−86.6610−8

ULI Wall 2.4110−82.1510−8 9.2510−95.1810−84.4410−91.1810−71.3010−7

LLI Wall 4.4410−88.1410−8 2.2910−86.2910−81.3010−82.4810−72.7410−7

Colon 3.2210−84.8110−8 1.5210−85.5510−88.1410−91.7410−71.9210−7

Kidneys 8.8810−92.4410−9 1.4110−94.8110−86.2910−111.2210−71.7010−7

Liver 1.6310−82.4410−9 2.8910−94.8110−87.7710−106.2910−62.0010−6
211

Muscle 7.0310−92.4410−9 1.1510−94.4410−84.4410−115.1810−85.5510−8

Ovaries 1.5910−82.4410−9 2.9210−95.1810−83.5210−104.0710−76.2910−7

Pancreas 9.6210−92.4410−9 1.4110−95.1810−86.2910−115.1810−85.5510−8

Red Marrow 7.7710−96.6610−7 5.5510−94.8110−82.5910−101.4410−61.1510−6

ET Airways 6.2910−92.4410−9 9.6210−10 4.8110−84.4410−125.1810−85.5510−8

Lungs 6.6610−92.4410−9 1.0710−94.8110−82.0410−115.1810−85.5510−8

Skin 4.8110−92.4410−9 7.7710−10 4.0710−81.3010−115.1810−85.5510−8

Spleen 7.7710−92.4410−9 1.1110−94.8110−83.4010−115.1810−85.5510−8

Testes 6.6610−92.4410−9 9.2510−10 4.4410−82.5510−114.0710−76.2910−7

Thymus 6.2910−92.4410−9 9.2510−10 4.8110−87.4010−125.1810−85.5510−8

Thyroid 6.2910−92.4410−9 9.6210−10 4.8110−84.4410−125.1810−85.5510−8

Uterus 1.1110−82.4410−9 1.8110−95.1810−81.5910−105.1810−85.5510−8

Effective dose 1.2610−81.0410−7 4.0710−94.8110−81.1810−99.2510−77.4010−7

*

 ICRP 68 ingestion dose coefficients were obtained from ICRP (2011). 

†

 Abbreviations used in this table: SI Wall = Small Intestine Wall; ULI Wall = Upper Large Intestine Wall; LLI Wall = Lower Large Intestine Wall; 

ET Airways = Extra-thoracic Airways.
212

C-3. Skin Dose Calculations 

C-3.1. Skin Dose from Dermal Contamination 

To calculate the skin dose from dermal contamination, the level of dermal concentration 

is first calculated as shown in Equation C-14a and C-14b: 

,, = , × ,,

,, =  × h ×  ×  ×  ×  × 

(C-14a) 

(C-14b)

where 

Cskin,i,j = Dermal (areal) concentration of radionuclide i at skin site j at the end of a 

workday (pCi cm−2) 

Csoil,i = Soil activity concentration of radionuclide i (pCi g−1) 

SLskin,i,j = Soil loading on skin of radionuclide i at skin site j at the end of a workday 

(g cm−2) 

ρ = Soil density (g cm−3) 

Thsoil = Soil layer thickness available for resuspension (cm) 

Ksusp = Resuspension factor (m−1) 

Vd = Deposition velocity of suspended soil particles (m h−1) 

rj = Interception and retention fraction for skin site j (unitless) 

Fskin = Fraction of workday a worker is exposed to suspended soil (unitless) 

Tworkday = Duration of the workday (h) 

A high-sided daily skin dose from dermal contamination is then estimated using 

Equation C-15: 

,,

 = , ×  × ,, ×  × [h ] (C-15) 

where 

,,

 = Daily skin dose from dermal contamination from radionuclide i at skin 

site j (rem) 

DCi,j = Dermal contamination dose coefficient for radionuclide i at skin site j at a 

depth of 0.07 mm (e.g., rem cm2 pCi−1 h−1) 

SDMFj = Skin depth modification factor for beta radiation only at skin site j

(unitless) 
213

Tdose = Duration of exposure to dermal contamination, equal to the sum of the 

workday hours and 2–4 h beyond the workday for a total of 12 h at which 

time complete removal of dermal contamination is assumed (h) 

Other 

Factors 

= Placeholder for other modifying factors such as presence of clothing 

(unitless) 

The recommended skin depth modification factors for beta radiation are shown in 

Table 34, Section 6.3.1. The parameter SDMF is not used for alpha radiation because the depth 

of the skin cells of interest is taken into account in the alpha dose coefficients. 

C-3.2. Skin Dose from External Sources of Radiation 

By appropriately choosing parameter values, a high-sided dose to skin at any height from 

external non-contact sources of radiation is estimated using Equation C-16: 





(h) = ̇

 ×  ×  × 1 + :

(h) ×  + ̇

 ×  ×  ×

1



 (C-16)

where 





(h) = External beta+gamma dose to skin at height h (rem) 

̇



= External gamma exposure rate (R h–1) 

FB = Film badge conversion factor (rem R−1) 

Texp-out = Duration of exposure to external radiation while outdoors (h) 

Texp- in = Duration of exposure to external radiation while indoors (h) 

Rβ:γ (h) = Beta-gamma dose ratio at height h (unitless) 

M = Any modifying factors, such as accounting for clothing, exposure factor, 

etc. (unitless, M = 1 for bare, dry skin) 

PF = Protection factor for land based structures (unitless) 

As an alternative to the formulation of Equation C-16, the beta radiation and gamma 

radiation portions of Equation C-16 can be calculated separately as follows: 





(h) = ̇

 ×  ×  × :(h) × 



 = ̇

 ×  ×  + ̇ ×  ×  ×

1



(C-17a) 

(C-17b)

Beta-gamma dose ratios and reference heights of body locations for use in ECUP skin 

dose assessments are provided in Appendix L. A discussion of the development of the ECUP 

beta-gamma dose ratios is also included in Appendix L. 
214

C-3.3. Total Skin Dose and Upper-bound Doses 

The total skin doses for the dermal and non-contact pathways for each skin site are the 

sums of the skin doses from each pathway. For upper-bound dose estimates, skin dose 

uncertainties for each pathway may be combined assuming that all component doses are fully 

correlated (DTRA, 2017, SM UA01). This means that the total upper-bound skin dose for each 

pathway for each site is calculated by applying the applicable uncertainty factor to each dose 

component and summing, as shown below, first for dermal contamination (Equations C-18a and 

C-18b) and then for external non-contact sources (Equation C-19). 

,

 = ,





(C-18a)



, =  × ,



(C-18b)

where 

,

 = Total dose to a specific skin site from all radionuclides in dermal 

contamination (rem) 

,

 = Skin dose from dermal contamination from radionuclide i at a specific skin 

site (rem) 



, = Upper-bound dermal contamination dose to a specific skin site (rem) 

 = Uncertainty factor for dermal contamination skin doses 



, =  × 



(h) (C-19)

where 



, = Upper-bound external beta+gamma dose to a specific skin site at height 

h (rem) 

 = Uncertainty factor for external (non-contact) skin doses 





(h) = External beta+gamma dose to skin site at height h (rem) 

An uncertainty factor of 10 is used for dermal contamination skin doses and an 

uncertainty factor of 3 for external (non-contact) doses. To calculate the total upper-bound dose 

for each skin site, the upper-bound doses for dermal contamination and non-contact sources are 

simply combined as shown below. (McKenzie-Carter, 2014) 



, = , + ,

(C-20)

where 



, = Total upper-bound dose to a specific skin site from all sources (rem) 
215

Appendix D. 

Analysis of TLD Dose Uncertainties 

D-1. Introduction 

In 1978, the Navy shipped several CP-1112/PD thermoluminescent dosimeter (TLD) 

readers and a number of DT-526/PD TLD dosimeters to Enewetak Atoll to supplement film 

badge dosimeters. Film badges were subject to a significant rate of environmental damage. The 

TLDs provided back-up readings to damaged film badges as the basis for determining the dose 

of record. The TLD reader and TLD dosimeters used together composed a dosimetry system. 

Three sources of error contribute to the overall system uncertainty for computation of an upperbound value for a given TLD reading (USN 1975; USN 1988). The three sources are: 

 Zero offset for the TLD reader zero reference level 

 Truncation of the digit on the display corresponding to tenths of a milliroentgen (mR) 

 The maximum allowable limit for system accuracy during performance testing. 

The remainder of this appendix through Section D-5 discusses the above sources of error 

in TLD readings and contains estimates of TLD reading uncertainties and uncertainty factors. 

Use of the TLD reading uncertainty factors to estimate uncertainty factors of assigned doses 

based on TLD readings is discussed in Section D-6. 

D-2. Zero Offset 

The CP-1112/PD technical manual (TM) (USN, 1975), section 3-3, “Operating 

Procedures,” gives the procedure for checking and resetting the zero reference level. The limit 

stated in the procedure for this setting is“000 to 003” (no units). This is a source of error 

corresponding to a range from 0.0 to 0.3 mR. 

D-3. Truncation of Display Digit 

The CP-1112/PD TM (USN, 1975), Section 3-3, Table 3-2 and paragraphs d(1) and (2) 

describe the six digital display ranges and reading interpretation. Table 3-2 indicates the lowest 

decade range of the TLD reader displays in two digits while the other five ranges display in three 

digits. The TLD reader display shows “XX.M” on the first range corresponding to dosimeter 

readings from 0 to 99 mR. Because the 10th of the mR digit is not displayed, the actual value 

could range from XX.0 mR to XX.9 mR if the digit after the decimal point were displayed by the 

reader. The display will show “XX.M” for nine signal levels in the previously stated range. This 

truncation introduces a potential error ranging from 0.0 to almost 1 mR. 

D-4. Performance Testing Limits 

Performance testing data can be used to assess overall dosimetry system uncertainty 

(NCRP, 2007) versus accounting separately for sources of laboratory, radiological, and 

environmental error as described for example in NAS-NRC (1989). The U.S. Navy introduced a 
216

performance testing program in the early 1980s to test several hundreds of dosimeter processors 

once a year to specific test limits (USN, 1988). The performance test consisted of testing readers 

with dosimeters pre-exposed to a National Institute of Standards and Technology radiation 

standard and evaluating samples of dosimeters drawn from every processing organization’s 

inventory. The maximum allowable uncertainty for the test of each dosimeter processing 

organization was ±30 percent at least at the 95th percentile confidence level (USN, 1988). This 

uncertainty corresponds to an uncertainty factor of 0.7 to 1.3 at least at the 95th percentile level. 

D-5. Combining Sources of Error 

The zero offset error and digit display truncation error are considered independent 

sources of error since they are caused by completely independent processes. The zero offset error 

can randomly take values from 0.0 to 0.3 mR with a mid-point value of 0.15 mR, assuming a 

symmetrical distribution. The truncation error ranges from 0.0 mR to almost 1 mR with a central 

value of 0.5 mR, also assuming a symmetrical distribution. Because the zero offset and 

truncation errors are independent, they can be combined using quadrature (NCRP, 2007). 

The upper-bound uncertainty for the performance test, a factor of 1.3 at least at the 95th

percentile confidence level, is from sources reported in NAS-NRC (1989) that are independent 

from the zero offset and truncation errors. The performance test uncertainty is equal to 0.3 times 

the TLD reading. 

The average offset error, the average truncation error, and the TLD system performance 

test uncertainty are combined in quadrature as recommended in NCRP (2007). As a result, for 

any given TLD reading, denoted by TLDrdg, the upper-bound uncertainty attributable to that 

reading, , is given by Equation D-1: 

 = (0.15)

 + (0.5) + (0.3 × ) (D-1) 

The upper-bound uncertainty factor for a TLD reading, , is defined as the ratio 

of the 95th percentile upper-bound value to the TLD reading, given by Equation D-2: 

 =  +  (D-2) 

Table D-1 provides estimates of  and . At a reading of about 10 mR, the 

 values asymptotically approach a value of 1.3, where the source of error for TLD 

system performance test predominates over the zero offset and truncation errors. 
217

Table D-1. Upper-bound uncertainty factor as a function of TLD reading 

TLD Reading (mR) Upper Bound Uncertainty Upper Bound Uncertainty 

Factor 

1 0.60 1.60

2 0.80 1.40 

3 1.04 1.35 

4 1.31 1.33 

5 1.59 1.32 

6 1.87 1.31 

7 2.16 1.31 

8 2.46 1.31 

9 2.75 1.31 

10 3.05 1.30 

>10* Use Equation D-1 1.30 

*

 Upper bound uncertainty at 95% confidence level is approximately 30% of the reading for TLD readings greater 

than 10 mR. 

D-6. TLD Dose Uncertainty 

The external dose assigned to an ECUP participant during a period or periods that a TLD 

was worn is the net reading of each TLD worn. The assigned dose (net reading) was calculated 

according to Equation D-3. 

 =  −  (D-3)

where 

 = Assigned TLD dose (mR or mrem) 

 = TLD reading (mR) 

 = Background radiation exposure for TLD wearing period (mR) 

The objective is to estimate the uncertainty associated with the assigned TLD dose(s) for 

use in calculating a total upper-bound external dose. To that end, the TLD reading associated 

with the assigned TLD dose, the uncertainties in the TLD reading, a background exposure, and 

the uncertainty in the background exposure must all be estimated. 

Rearranging Equation D-3 gives Equation D-4 below. 

 =  +  (D-4)

Equation D-4 is used together with the assigned TLD dose and an estimate of the 

background exposure to estimate the TLD reading associated with the assigned TLD dose. The 

uncertainties in the TLD reading(s) are then estimated using the values in Table D-1, which 

presents the uncertainties for single TLD readings. 
218

To estimate a background exposure for a given participant TLD reading, 15 sets of 

readings and corrected readings from control TLDs that were exposed during 10 separate periods 

from July 1978 to February 1980 were obtained from the ECUP records. Each set contains 10 

individual TLD readings, so there are 150 control TLD readings in total. Documentation of the 

specific placement of the control TLDs was not located, but it is assumed that they reflect 

primarily cosmic background and other natural radiation (AEC, 1973a). The control TLD 

readings were converted to daily exposure rates, and a mean of 0.116 mR d−1 was calculated. 

This value is assumed to be representative background exposure rate for all ECUP TLD wearing 

periods. If a TLD Report that lists an individual’s background exposure is not available, the Bkg

value for a given TLD dose is obtained by multiplying this mean exposure rate by the number of 

days in a participant’s wearing period. 

An estimate of the upper-bound uncertainty associated with the background exposure can 

be obtained statistically from the 15 sets of control TLD readings. Assuming a t-distribution in 

the control TLD readings, a 95th percentile value of 0.125 mR d−1 was calculated. Using the 

mean and 95th percentile values, an uncertainty factor of 1.08 (0.125/0.116) was calculated, 

which can be rounded up to 1.1. Therefore, the uncertainty associated with the total background 

exposure is about 10 percent of the background value. The uncertainty factor is used to calculate 

the upper-bound uncertainty for the background exposure for a specific TLD wearing period 

(), as shown in Equation D-5. 

 =  × (1.1 − 1)

=  × 0.1

(D-5)

Because the uncertainty in a TLD reading from Table D-1 is estimated differently than 

the uncertainty in the background TLD readings as described above, these uncertainties are 

assumed independent of each other and hence are uncorrelated. Therefore, they are combined in 

quadrature, as shown in Equation D-6 below, to estimate the total uncertainty in a TLD dose 

denoted . 

 = 



+ 



(D-6)

The total uncertainty in TLD dose (uTLD) is combined in quadrature with the uncertainties 

in reconstructed and film badge doses to estimate the total external upper-bound dose as 

described in Appendix C. 
219

Appendix E. 

Resuspension of Soil Contaminants 

When measured concentrations of airborne contaminants are not available, two common 

methods can be used to estimate the air concentration of resuspended soil contaminants: the 

resuspension factor method and the mass loading method. 

E-1. Resuspension Factor Method 

The resuspension factor, which is the ratio of airborne activity concentration to surface 

activity concentration, has been calculated or measured for many types of soil disturbances, and 

ranges over many orders of magnitude. Typical values range from 10−7 to 10−5 m−1, and a value 

of 10−6 m−1 is often used as a generic value for planning purposes. However, these values apply 

to periods shortly after depositions of contaminated material when the freshly deposited material 

is more likely to be suspended than the underlying soil (Anspaugh et al., 2002; AEC, 1973a). 

Therefore, these values are not applicable to most situations involving the aged deposits of 

plutonium and other radionuclides at Enewetak during ECUP. For wind-driven resuspension 

from aged deposits, a more applicable resuspension factor has been estimated to be in the range 

of 10−10 to 10−8 m−1 (AEC, 1973a; Till and Grogan, 2008). In addition, use of a time-dependent 

model for the resuspension factor is sometimes recommended for periods long after deposition 

(Anspaugh et al., 2002; DTRA, 2017; Till and Meyer, 1983). However, methods based on timedependent models generally do not account for different types of soil disturbances because they 

incorporate a fixed initial value (K(0) = 10−5 m−1). 

E-2. Mass Loading Method 

The second approach for estimating air concentrations of resuspended contaminants 

discussed in this report uses the mass loading method. This method estimates an airborne 

concentration of soil particulates that have been suspended from the ground surface, as mass per 

unit volume of air. The concentration of a contaminant in the suspended soil is then related to the 

activity concentration of contaminants in the surface soil to estimate the airborne activity 

concentration of contaminants. An inherent assumption in this approach is that the contaminants 

in the soil are reasonably well-mixed within the top layer of soil. Although, the mass loading 

method is commonly used for non-radioactive particulate matter, e.g., dust, dirt, smoke, it is also 

appropriate for radioactive soil contaminants as stated in Anspaugh et al. (2002). Environmental 

standards have been developed for mass loading levels of non-contaminated particulates 

(USEPA, 2017c). Mass loadings of contaminated soil have been measured for many types of soil 

disturbances, including in environments similar to Enewetak Atoll. Values of particulate mass 

loading resulting from various soil disturbances that are relevant to ECUP generally range from 

40 to 600 μg m−3 (AEC, 1973a; Oztunali et al., 1981; Shinn et al., 1994, 1996, 1997). 

Even though plutonium in aged deposits may be well-mixed in the soil, it can be 

preferentially associated with the smaller particle sizes that are more likely to become airborne 

(Anspaugh et al., 2002). To account for a potentially different airborne activity concentration 

compared to the source soil, an “enhancement” or “enrichment” factor is used with the mass 

loading values. Values for plutonium enhancement factors range from less than 1.0 to 6.5 (Shinn 
220

et al., 1980, 1994, 1997). Although this factor may vary depending upon the type of disturbance, 

a reasonably conservative value of 3 is used in this report (Shinn et al., 1994). This value is also 

recommended as the default value to be used for all resuspended radionuclides in ECUP 

radiation dose assessments. 

E-3. Relationship between Mass Loading and Resuspension Factor 

To simplify the use of information on contaminant resuspension by future analysts, an 

equivalency between mass loading and resuspension factor was derived. The derivation starts by 

setting air concentrations calculated by the two methods equal to each other as shown in 

Equation E-1, and then solving for the resuspension factor K. Assuming an enhancement factor 

of 3, an average soil density of 1.5 g cm−3, and a soil thickness available for suspension of 1 cm, 

the relationship between mass loading and resuspension factor is given by Equation E-2. Note 

that the soil activity concentration, Csoil, is unimportant in this derivation because it is the same 

for both methods and cancels out as can be seen in Equation E-1; 

 ×  ×  × h =  ×  ×  (E-1)

where 

K = Contaminant resuspension factor (m−1) 

Csoil = Soil activity concentration (pCi g−1) 

 = Soil bulk density (g m−3

) 

Thsoil = Depth of soil available for resuspension (m) 

ML = Mass loading of suspended soil in air (μg m−3) 

Ef = Enhancement factor (unitless) 

If r = 1.5 Õ 10  , 

h = 0.01 , 

and 

 = 3

then, Equation E-1 becomes: 

 = 2 × 10 ×  (E-2)

Based on the above relationship, the equivalency of various pairs of mass loading and 

resuspension factors is shown in Table E-1 for selected soil disturbance activities. 
221

Table E-1. Mass loading values and resuspension factors for 

representative types of ECUP soil disturbances 

ECUP Activity or 

other Relevant Item 

Mass Loading 

(μg m−3) 

Resuspension 

factor (m−1)

* Comment 

Ambient level on the 

islands of Enewetak 40 8  10−9

Ambient dust loading under quiet 

atmospheric conditions (AEC, 

1973a) 

Generic default value 100†2  10−8

Default mass loading value is 

from several sources (e.g., 

Anspaugh et al., 1975; AEC, 

1973a; Yu et al., 2015) 

Truck traffic 100 2  10−8

Resuspension factor is the 

geometric mean (GM) of 

downwind values calculated from 

measurements in Bramlitt (1977) 

Regulatory limit 

(maximum PM10 24-h 

average concentration) 

150 3  10−8

Mass loading value is the National 

Primary and Secondary AAQS 

(40CFR50.6) 

Work involving soil 

piles 250 5  10−8

Mass loading value is calculated 

as the GM of values measured 

near Johnston Island Pu-soil piles: 

79 and 178 μg m−3 (Shinn et al., 

1994), 256 and 1017 μg m−3

(Shinn et al., 1996) 

Clearing vegetation 300 6  10−8

Mass loading value is for 

agricultural tillage (Oztunali et al., 

1981) 

Soil excision and 

windrowing 600 1.2  10−7

Mass loading value is for close 

proximity to operating bulldozer; 

basement excavation (Oztunali et 

al., 1981) 

*

 These resuspension factors were calculated using Equation E-2. 

† This value is a conservative value for general activities at Enewetak Atoll and may be used for dose estimation 

purposes if no other specific value is applicable.

The range of resuspension factors in Table E-1 is approximately 10−8 to 10−7m−1, and it 

includes values that are larger than the range given earlier for aged deposits. The estimates are 

calculated using assumed values for the soil density, the enhancement factor, and the depth of 

soil available for resuspension. If, for example, the soil depth is larger than the assumed value of 

0.01 m, or if the enhancement factor is smaller than the assumed value of 3, the calculated 

resuspension factors would be lower than shown. For example, enhancement factors of less than 

1.0 have been reported for Pacific island environments such as Enewetak (Shinn et al., 1980). 

Using an assumed enhancement factor of 1.0 in Equation E-1, with all other parameter values 

unchanged, would result in calculated resuspension factors of 2.7  10−9m−1 to 4  10−8m−1 in 

Table E-1. 
222

E-4. Resuspension Factors Estimated for ECUP Aggregate Hauling Activity 

During April and May 1977, aggregate was bulk-hauled from a stockpile on Enjebi to 

Lojwa for use in construction of the forward base camp (DNA, 1981). This was accomplished 

using scoop loaders, dump trucks, and landing craft mechanized (LCM-8) to move the aggregate. 

Air samplers were operated upwind and downwind of the aggregate loading and unloading 

operations, and resuspension factors were estimated using downwind concentrations of 

Pu-239/240 (Bramlitt, 1977). The resuspension of Pu-239/240 in soil was due to the operation of 

the heavy mechanized equipment. 

The air sampling concentration data and calculated resuspension factors shown in 

Table E-2 duplicate the calculation of resuspension factors in Bramlitt (1977). In the 1977 

memorandum, resuspension factors were estimated only for downwind sampler locations; so 

upwind estimates are added in Table E-2. Several errors in the original 1977 calculations have 

been corrected here, although they do not significantly affect the results. Except for those with 

errors, the resuspension factors for downwind locations in Bramlitt (1977) match the values in 

Table E-2. 

The resuspension factors shown in Table E-2 are calculated using the following equation: 

 =





(E-3)

where 

K = Resuspension factor (m−1) 

ACPu = Air concentration of Pu-239/240 (pCi m−3) 

CaPu = Ground surface activity density of Pu-239/240 (pCi m−2) 

(= Csoil,Pu    Thsoil) 

Csoil,Pu = Soil activity concentration of Pu-239/240 (pCi g−1) 

 = Soil bulk density (g m−3

) 

Thsoil = Depth of soil available for resuspension (m) 

As pointed out in Bramlitt (1977), the exact location of the samplers with respect to the 

equipment operations was not available. In addition, several other factors that could affect soil 

suspension were not documented. However, the calculated resuspension factors are comparable 

to values reported in the literature and are consistent with estimates from other measurements 

included in Table E-1. 

Mass loading values calculated using Equation E-2 are also shown in Table E-2. The data 

and results presented in Table E-2 show that at the aggregate pile on Lojwa, the activity 

concentration was 22 fCi m−3 on April 20, 1977 and only 2 fCi m−3 the next day on April 21, 

1977. Except for that sample and another sample collected on Enjebi where the activity 

concentration was 11 fCi m−3, all downwind concentrations were lower than 3 fCi m−3 with an 

average of 1.3 fCi m−3. Furthermore, for all measurements, the average mass loading for upwind 

locations is 18 μg m−3, and in most cases the estimated upwind mass loading values were less 

than 20 μg m−3. These values are a factor of 5 lower than the proposed generic value of 

100 μg m−3 (Table E-1). For the downwind locations, excluding the outlier value corresponding 
223

to the activity concentration of 22 fCi m−3 mentioned above, the average calculated mass loading 

is less than 120 μg m−3. 

Table E-2. Air concentrations, resuspension factors, and mass loading values 

associated with aggregate hauling 

Location 

Sample 

Dates 

(1977) 

Measured 

Pu-239/240 Air 

Concentration*

(fCi m−3) 

Calculated 

Resuspension Factors†

(m−1) 

Calculated Mass 

Loading Values‡

(μg m−3) 

DW§ UW** DW UW DW UW

Aggregate 

Pile at Lojwa 

Apr 20 22 0.41 6.710−71.210−83333 62 

Apr 21 2.0 < 0.7 6.110−82.110−8303 106 

Enjebi Apr 22 2.9 0.05 1.310−82.210−1063 1 

Apr 26 1.6 < 0.08 6.910−93.510−1035 2 

Apr 28 2.3 0.09 1.010−83.910−1050 2 

Apr 29 1.9 0.03 8.210−9 1.310−10 41 1 

Apr 30 1.7 0.02 7.410−

9

8.710−1137 0.4 

Enjebi Beach Apr 21 11 < 0.4 4.810−81.710−9238 9 

May 5 1.2 < 0.11 5.210−94.810−1026 2 

May 6 0.44 ND†† 1.910−9- 10 - 

May 7 0.62 ND 2.710−9- 13 - 

May 8 0.31 ND 1.310−9- 7 - 

Lojwa Apr 22 0.67 < 0.06 2.010−81.810−9102 9 

Apr 26 1.7 0.11 5.210−83.310−9258 17 

Apr 28 0.77 0.05 2.310−81.510−9117 8 

Apr 29 0.68 0.11 2.110−83.310−9103 17 

Apr 30 0.71 < 0.06 2.210−81.810−9108 9 

May 5 1.2 < 0.3 3.610−89.110−9182 45

May 6 2.4 < 0.04 7.310−81.210−9364 6 

May 7 0.96 0.045 2.910−81.410−9145 7 

Minimum 0.31 0.04 1.310−98.710−11

Maximum 22 0.7 6.710−72.110−8

*

 Taken from Enclosure 1 of Bramlitt (1977). 

†

 Calculated using Equation E-3, with Csoil,Pu = 2.2 pCi g−1 (Lojwa); Csoil,Pu = 15.4 pCi g−1 (Enjebi);  = 1.5  106

g m−3; and Thsoil = 0.01 m. 

‡

 Calculated using the Calculated Resuspension Factors in this table and Equation E-2. 

§

 DW = Downwind location relative to soil disturbance. 

** UW = Upwind location relative to soil disturbance. Where air concentration values are listed as “<” (less than), 

the value shown is used. 

†† ND = No Data available for upwind locations on these dates.
224

Appendix F. 

Respiratory Protection Factors 

A respiratory protection factor represents the degree of protection afforded by a respirator 

against airborne contaminants. Numerically it is equal to the ratio of the concentration of 

contaminants outside the respirator to the concentration inhaled (i.e., inhaled concentration = 

outside concentration/protection factor). Protection factors for various respirators have been 

established by the U.S. Nuclear Regulatory Commission. The USNRC guidance on protection 

factors available in 1976 was published in NUREG-0041, “Manual of Respiratory Protection 

Against Airborne Radioactive Materials” (USNRC, 1976). Subsequent to ECUP, protection 

factors were first published in the Code of Federal Regulations in 1983 as Appendix A to Title 

10, Part 20 (USNRC, 2017). 

Air-purifying respirators were used at ECUP. These included half-face and full-face 

respirators. Some of the half-face and full-face respirators were equipped with a battery-operated 

blower unit, i.e., for positive pressure. FRST members were responsible for determining the 

appropriate respirator to use in a work environment, ensuring that a proper fit was made, and that 

respirators were used properly at each work site. Guidance and requirements for respiratory 

protective equipment at ECUP, including selection, usage, testing and fitting, were provided in 

the ECUP Standing Operating Procedure FCRR SOP 608-05 “Respiratory Protection” and EAI 

5707.1 “Personnel Protection Levels.” 

The USNRC protection factors available for ECUP in NUREG-0041 and current 

regulations differ somewhat. The primary difference relevant to respirators in use during ECUP 

is the protection factor specified for half-face, positive pressure respirator. As shown in 

Figure F-1, which is a reproduction of Table 6-1 of USNRC (1976), this respirator was assigned 

a protection factor of 1,000 at the time of ECUP, but is currently assigned a protection factor of 

50 as shown in Appendix A of 10 CFR 20, reproduced here as Table F-2, USNRC (2017). Also, 

the full-face, negative pressure respirator was assigned a protection factor of 50 at the time of 

ECUP, but is currently assigned a protection factor of 100. These are shown below in Table F-1

for each ECUP Personnel Protection Level as specified in EAI No. 5707.1 “Personnel Protection 

Levels.” Based on the two sets of protection factors for air-purifying respirators, the more 

conservative protection factor for each respirator type is recommended for use in ECUP dose 

assessments as recommended in Section 7 of this report. 
225

Table F-1. Personnel protection levels and respiratory protection for ECUP 

ECUP Personnel 

Protection Level ECUP Respiratory Protection*

Respiratory Protection 

Factor†

NUREG-0041‡ 10CFR20§

I or IIA None 1 1 

IIB Surgical mask (dust mask) 1 1 

IIIA or IIIB 

Full-face negative pressure respirator 50 100 

Half-face positive pressure respirator 1000 50 

Full-face positive pressure respirator 1000 1000 

IV Full-face positive pressure respirator 1000 1000 

*

 Half-face, negative pressure respirators (protection factor of 10 [USNRC, 1976]) are mentioned in some ECUP 

documentation (e.g., FCRR SOP 608-10 “Decontamination Laundry Procedures.” However, this respirator type is 

not listed in the ECUP Personnel Protection Level documentation (EAI No. 5707.1; DNA, 1981). 

†

 The lower protection factor for each respirator type is recommended for use in ECUP dose assessments. 

‡

 USNRC (1976, Table 6-1). 

§

 USNRC (2017, Appendix A to Part 20). 
226

Figure F-1. Protection factors for respirators (USNRC, 1976) 
227

Figure F-1. Protection factors for respirators (USNRC, 1976) (cont.) 
228

Table F-2. Assigned protection factors for respirators (USNRC, 2017) 

Appendix A to Part 20 – Assigned Protection Factors for Respiratorsa

Operating mode 

Assigned 

Protection 

Factors 

I. Air Purifying Respirators [Particulateb only]c: 

Filtering facepiece disposabled Negative Pressure (

d

) 

Facepiece, halfe Negative Pressure 10 

Facepiece, full Negative Pressure 100

Facepiece, half Powered air-purifying respirators 50 

Facepiece, full Powered air-purifying respirators 1000

Helmet/hood Powered air-purifying respirators 1000 

Facepiece, loose-fitting Powered air-purifying respirators 25 

II. Atmosphere supplying respirators [particulate, 

gases and vaporsf]: 

1. Air-line respirator: 

Facepiece, half Demand 10 

Facepiece, half Continuous Flow 50 

Facepiece, half Pressure Demand 50

Facepiece, full Demand 100

Facepiece, full Continuous Flow 1000 

Facepiece, full Pressure Demand 1000 

Helmet/hood Continuous Flow 1000

Facepiece, loose-fitting Continuous Flow 25 

Suit Continuous Flow (

g

) 

2. Self-contained Breathing Apparatus (SCBA):

Facepiece, full Demand 100h 

Facepiece, full Pressure Demand 10,000i 

Facepiece, full Demand, Recirculating 100h

Facepiece, full Positive Pressure Recirculating 10,000i 

III. Combination Respirators: 

Any combination of air-purifying and 

atmosphere-supplying respirators 

Assigned protection factor for type and mode of 

operation as listed above. 

a These assigned protection factors apply only in a respiratory protection program that meets the requirements of 

this Part. They are applicable only to airborne radiological hazards and may not be appropriate to circumstances 

when chemical or other respiratory hazards exist instead of, or in addition to, radioactive hazards. Selection and use 

of respirators for such circumstances must also comply with Department of Labor regulations. 

Radioactive contaminants for which the concentration values in Table 1, Column 3 of Appendix B to Part 20 are 

based on internal dose due to inhalation may, in addition, present external exposure hazards at higher concentrations. 

Under these circumstances, limitations on occupancy may have to be governed by external dose limits. 

bAir purifying respirators with APF <100 must be equipped with particulate filters that are at least 95 percent 

efficient. Air purifying respirators with APF = 100 must be equipped with particulate filters that are at least 99 

percent efficient. Air purifying respirators with APFs >100 must be equipped with particulate filters that are at least 

99.97 percent efficient. 

cThe licensee may apply to the Commission for the use of an APF greater than 1 for sorbent cartridges as protection 

against airborne radioactive gases and vapors (e.g., radioiodine). 
229

Table F-2. Assigned protection factors for respirators (USNRC, 2017) (cont.) 

dLicensees may permit individuals to use this type of respirator who have not been medically screened or fit tested 

on the device provided that no credit be taken for their use in estimating intake or dose. It is also recognized that it is 

difficult to perform an effective positive or negative pressure pre-use user seal check on this type of device. All 

other respiratory protection program requirements listed in §20.1703 apply. An assigned protection factor has not 

been assigned for these devices. However, an APF equal to 10 may be used if the licensee can demonstrate a fit 

factor of at least 100 by use of a validated or evaluated, qualitative or quantitative fit t e s t . 

eUnder-chin type only. No distinction is made in this Appendix between elastomeric half-masks with replaceable 

cartridges and those designed with the filter medium as an integral part of the facepiece (e.g., disposable or reusable 

disposable). Both types are acceptable so long as the seal area of the latter contains some substantial type of sealenhancing material such as rubber or plastic, the two or more suspension straps are adjustable, the filter medium is at 

least 95 percent efficient and all other requirements of this Part are met. 

fThe assigned protection factors for gases and vapors are not applicable to radioactive contaminants that present an 

absorption or submersion hazard. For tritium oxide vapor, approximately one-third of the intake occurs by 

absorption through the skin so that an overall protection factor of 3 is appropriate when atmosphere-supplying 

respirators are used to protect against tritium oxide. Exposure to radioactive noble gases is not considered a 

significant respiratory hazard, and protective actions for these contaminants should be based on external 

(submersion) dose considerations. 

gNo NIOSH approval schedule is currently available for atmosphere supplying suits. This equipment may be used in 

an acceptable respiratory protection program as long as all the other minimum program requirements, with the 

exception of fit testing, are met (i.e., §20.1703). 

hThe licensee should implement institutional controls to assure that these devices are not used in areas immediately 

dangerous to life or health (IDLH). 

iThis type of respirator may be used as an emergency device in unknown concentrations for protection against 

inhalation hazards. External radiation hazards and other limitations to permitted exposure such as skin absorption 

shall be taken into account in these circumstances. This device may not be used by any individual who experiences 

perceptible outward leakage of breathing gas while wearing the device. 

[64 FR 54558, Oct. 7, 1999; 64 FR 55524, Oct. 13, 1999] 
230

Appendix G. 

Soil Concentrations of TRU Radionuclides 

The major radioactive contaminants at Enewetak during ECUP that may have resulted in 

external or internal doses to ECUP participants were the TRU radionuclides Pu-239, Pu-240 and 

Am-241, and the fission and activation products Cs-137, Sr-90, and Co-60 (DNA, 1981; DOE, 

1982a). Small quantities of other TRU radionuclides were also present (e.g., Pu-238 and Pu-241) 

as well as other fission products (e.g., Sb-125 and Eu-155). However, because of their low 

concentrations and/or radiological decay characteristics, these additional radionuclides are not 

important from an ECUP radiological dose perspective. (DNA, 1981; DOE, 1982a; AEC, 

1973a). 

Contaminated soil represents the most likely source of potential exposure to these 

radionuclides for ECUP participants. Soil radionuclide concentrations used in the dose 

calculations in this report are based on values measured during the radiological field survey 

conducted in 1972 and documented in NVO-140 (AEC, 1973a). The 1972 soil concentrations are 

not modified to account for radiological or environmental processes that would have changed the 

soil concentrations from the time of the measurements to the start of ECUP in 1977. The most 

significant of these processes is the radioactive decay of Co-60, which has a radioactive half-life 

of approximately 5.3 years (NNDC, 2019). Based on the measured exposure rates in NVO-140 

(AEC, 1973a), Co-60 accounted for an average of about one-half of the average external 

exposure rates from undisturbed soil on the islands. Therefore, the island external exposure rates 

at the beginning of ECUP would have been about 75 percent of the 1972 measured rates due to 

the radiological decay of Co-60. Additional decay of Co-60 that occurred over the 3-year period 

of ECUP is also ignored in this report for simplicity. 

Several simplifications and other assumptions regarding soil concentrations of certain 

radionuclides are made in this report for excised soil and undisturbed soil as described below. 

G-1. Radionuclide Concentrations in Excised Soil 

Radioactive contaminants in excised soil are estimated during ECUP only for the TRU 

component. To simplify the internal dose estimates for certain scenarios and not understate 

potential doses, all TRU radioactivity in excised soil is assumed to be Pu-239, and non-TRU 

radionuclides are not included. This assumption may be used when the total TRU content of the 

excised soil is included, i.e., for scenarios using the soil activity concentrations of Table 44 in 

Section 7.1. This is a reasonable assumption for the purposes of the ECUP dose assessments for 

the following reasons: 

 Radioactive content of excised soil was reported simply as total curies (e.g., DNA, 1981, 

Figure 8-34) or total TRU curies (DOE, 1982a), without identifying individual radionuclides. 

 Pu-239 was the predominant TRU radionuclide in Enewetak soil (AEC, 1973a; DOE, 

1982a). 
231

 The combined Pu-239+Pu-240 activity was reported in 1972 and during ECUP because the 

alpha particle energies of these isotopes are almost identical and they cannot be resolved 

using ordinary pulse-height analysis. 

 Pu-238 was present at Enewetak but existed in small quantities and was not routinely 

measured. When it was measured, it generally accounted for less than 5 percent of the total 

TRU activity (DNA, 1981; AEC, 1973a). 

 The inhalation dose coefficients for TRU radionuclides other than Pu-239 are generally less 

than or similar to those of Pu-239. The few TRU dose coefficients that are higher than those 

for Pu-239 are typically only 10–20 percent larger (ICRP, 2011). 

 Calculated inhalation doses from Pu-239 are an order of magnitude, or more, larger than 

internal doses from Sr-90, Cs-137, and Co-60. 

The validity of this assumption is demonstrated in Table G-1, where unit-concentration 

inhalation “doses” for bone surface calculated using two methods are shown. The calculated 

doses (rem g−1) are not representative of a specific scenario, but are simply relative values that 

allow comparison of the contribution of each radionuclide to an actual estimated inhalation dose. 

Both methods shown in Table G-1 are based on a TRU soil concentration of 1 pCi g−1. In 

Method #1, the 1 pCi g−1 of TRU activity is assumed to be Pu-239, and no other radionuclides 

are included. In Method #2 the 1 pCi g−1 of TRU activity is distributed among the four ECUP 

TRU radionuclides, and dose contributions from other radionuclides representative of Enewetak 

soil are included. The total dose calculated using Method #1 (5.55  10−3 rem g−1) is within 

1 percent of the dose calculated using Method #2 (5.58  10−3 rem g−1). This confirms that the 

simplified approach of Method #1 is acceptable for the ECUP dose assessments where the total 

TRU content of the soil is accounted for. For other scenarios, e.g., those involving suspension of 

soil from roadways and general, non-excision, areas on an island, or where measured air 

concentrations of Pu-239 are used, all radionuclides of concern should be included as described 

in Appendix C. 

G-2. Radionuclide Concentrations in Undisturbed Soil 

Undisturbed soil radioactivity concentrations for five of the six radionuclides of concern 

for all islands are documented in AEC (1973a). Soil concentrations of Am-241 were not 

typically reported and are therefore estimated for use in the dose estimates of this report. This 

was done using documented activity ratios of TRU:Am-241 that were developed during ECUP to 

support the IMP measurement results (DOE, 1982a). 

The ratio TRU:Am-241 was found to vary over the range of about 2.5 to 10 at Enewetak 

islands (DOE, 1982a). There are exceptions to this range, for example the ratio of 14.42 for the 

Fig-Quince area on Runit. The assumed value for the TRU:Am-241 ratio directly affects the 

estimated Am-241 soil concentrations. Assuming that Pu-239+240 and Am-241 make up 

essentially all of the TRU activity, the Am-241 soil concentration varies by a factor of 6 over the 

range of 2.5–10 assumed for the ratio TRU:Am-241 (Figure G-1). 
232

Table G-1. Comparison of inhalation doses (bone surface) using two different assumptions 

for TRU and other radionuclide soil content 

Radionuclide Soil Concentration 

(pCi g−1) 

Dose Coefficient 

(rem pCi−1) 

Dose 

(rem g−1) 

Method #1 (used in this report to account for all TRU radioactivity in excised soil): 

TRU*: Pu-239 1.0 5.55  10−35.55  10−3

Method #1 Total: 5.55  10−3

Method #2:

TRU*: 

Pu-238†0.04 4.81  10−31.92  10−4

Pu-239‡0.40 5.55  10−32.22  10−3

Pu-240‡0.40 5.55  10−32.22  10−3

Am-241§0.16 5.92  10−39.47  10−4

Sr-90** 2.30 1.37  10−6 3.15  10−6

Cs-137** 0.58 1.78  10−81.02  10−8

Co-60** 0.11 1.37  10−81.48  10−9

Method #2 Total: 5.58  10−3

*

 TRU concentrations for each method are highlighted with a bold-line cell border. Both methods are based on a 

total TRU concentration of 1 pCi g−1. 

†

 The Pu-238 concentration is based on the Pu-238:Pu-239 ratios in Table 14 of NVO-140 (AEC, 1973a). 

‡

 Pu-239 and Pu-240 concentrations are assumed equal (DOE, 1982a, Table 6-3). Because the Pu-239 and Pu-240 

dose coefficients for bone surface are equal, this assumption does not affect the comparison shown in this table. 

§

 The Am-241 concentration is based on the average Am-241:Pu-239 ratio of approximately 0.4 in Table 14 of 

NVO-140 (AEC, 1973a). 

** Concentrations of Sr-90, Cs-137, and Co-60 are based on 1 pCi g−1

 of TRU, using the geometric means of soil 

concentration ratios for all islands that debris-removal activities were conducted (DOE, 1982a; AEC, 1973a). 

Because Am-241 contributes different fractions of the total inhalation dose for different 

organs, the impact of the TRU:Am-241 ratio on organ dose from inhalation of suspended 

contaminated soil varies depending on the organ of interest. The relative change in inhalation 

dose for a range of TRU:Am-241 ratios is shown for the representative organs liver, bone 

surface, lungs, and testes in Figure G-2. 
233

Figure G-1. Estimated soil activity concentration of Am-241 as a function of assumed 

TRU:Am-241 ratio (Pu-239+240 = 8.7 pCi g−1) 

Figure G-2. Effect of TRU:Am-241 ratio on organ inhalation doses 

0

1

2

3

4

5

6

7

2 3 4 5 6 7 8 9 10 11

A

m-2

41 S

oil Activity

C

oncentr

ation

(p

Ci g

-1

)

TRU:Am-241 Ratio

0.5

0.6

0.7

0.8

0.9

1.0

1.1

2 4 6 8 10 12

R

elativ

e

D

ose

TRU:Am-241 Ratio

Liver

Bone Surface

Lungs

Testes
234

G-3. Recommended TRU:Am-241 Ratios for Undisturbed Soil 

The TRU:Am-241 ratios for the five soil removal islands are documented in DOE 

(1982a), and range from 3.2 to 11.3 (ignoring the high value for the Fig-Quince area). The 

recommended TRU:Am-241 value for estimating Am-241 soil concentrations for these islands is 

6.0, which is the geometric mean of this range (the arithmetic mean is 6.5). The TRU:Am-241 

ratios for other islands are not always documented in DOE (1982a). The ratio for other islands, 

especially the southern islands where no detonations took place, would be expected to be in the 

range 2.5–4 (DOE, 1982a). Because a lower ratio generally results in higher organ doses 

(Figure G-2), a ratio of 2.5 is recommended as a conservative value for estimating the Am-241 

soil concentrations on all islands other than the five soil-removal islands. 

G-4. Use of TRU:Am-241 Ratios 

The TRU:Am-241 ratio is used to estimate Am-241 soil activity concentrations in 

undisturbed soil. As described earlier in this Appendix, TRU radionuclides in Enewetak soil 

were primarily Pu-238, Pu-239, Pu-240, and Am-241, with Pu-239 being the predominant TRU 

radionuclide. Because Pu-238 is generally a small fraction of the total TRU activity, the sum of 

the Pu-239/240 and Am-241 soil concentrations is assumed to be the total TRU soil 

concentration. That is, TRU activity = (Pu-239/240 + Am-241) activity. Based on this 

assumption, Am-241 soil concentrations using the TRU:Am-241 Ratio and the Pu-239/240 soil 

concentrations are estimated using the following equation: 

 =



( − 1)

(G-1) 

where: 

CAm241 = Soil activity concentration of Am-241 in undisturbed soil (pCi g−1

) 

CPu239240 = Soil activity concentration of Pu-239/240 in undisturbed soil (pCi g−1

) 

Ratio = Value of ratio of TRU soil activity concentration to Am-241 soil activity 

concentration in undisturbed soil (2.5 or 6, depending on island) 

Application of the two recommended ratios and the resulting estimated island-average 

Am-241 soil activity concentrations for all islands are shown in Table G-2. 
235

Table G-2. Am-241 soil concentrations in undisturbed soil for all islands calculated using 

TRU:Am-241 ratios 

Island Name Site Name 

Mean Pu-239/240 

Soil Concentration*

(pCi g−1) 

TRU:Am-241 

Ratio†

Calculated Am-241 

Soil Concentration 

(pCi g−1) 

Bokoluo Alice 15.6 2.5 10.4

Bokombako Belle 27.1 2.5 18.1

Kirunu Clara 31.6 2.5 21.1

Louj Daisy 31.6 2.5 21.1

Bocinwotme Edna 19.4 2.5 12.9

Boken Irene 26.2 6 5.2

Enjebi Janet 16.2 6 3.2

Mijikadrek Kate 11.3 2.5 7.5

Kidrinen Lucy 7.7 2.5 5.1

Taiwel Percy 9 2.5 6.0

Bokenelab Mary 10.1 2.5 6.7

Elle Nancy 10.1 2.5 6.7

Aej Olive 8.4 2.5 5.6

Lujor Pearl 38.3 6 7.7

Eleleron Ruby 14.5 2.5 9.7

Aomon Sally 11 6 2.2

Bijire Tilda 6.5 2.5 4.3

Lojwa Ursula 1.8 2.5 1.2

Alembel Vera 4.3 2.5 2.9

Billae Wilma 1.8 2.5 1.2

Runit Yvonne 8.7 6 1.7

Boko Sam 0.09 2.5 0.06

Munjor Tom 0.08 2.5 0.05

Inedral Uriah 0.08 2.5 0.05

n/a Van 0.08 2.5 0.05

Jinedrol Alvin 0.06 2.5 0.04

Ananij Bruce 0.09 2.5 0.06

Jinimi Clyde 0.06 2.5 0.04

Japtan David 0.05 2.5 0.03

Jedrol Rex 0.04 2.5 0.03

Medren (Parry) Elmer 0.21 2.5 0.14

Bokandretok Walt 0.04 2.5 0.03

Enewetak Fred 0.08 2.5 0.05

Ikuren Glenn 0.11 2.5 0.07

Mut Henry 0.14 2.5 0.09

Boken Irwin 0.13 2.5 0.09

Ribewon James 0.08 2.5 0.05

Kidrenen Keith 0.11 2.5 0.07

Biken Leroy 1.15 2.5 0.77

*

 Mean Pu-239/240 soil concentrations from NVO-213 (DOE, 1982a). 

†

 TRU:Am-241 ratio is 6 for the five soil-removal islands and 2.5 for all other islands. 
236

Appendix H. 

List of Standing Operating Procedures and Enewetak Atoll Instructions 

for Radiological Operations at ECUP 

Table H-1 presents the identifying document numbers, titles, and dates of the Standing 

Operating Procedures (SOPs) and Enewetak Atoll Instructions (EAIs) for topics dealing with 

radiological operations at ECUP available in the ECUP records. There are 18 SOPs and 12 EAIs 

referenced in the Radiological Cleanup of Enewetak (DNA, 1981), but no consolidated listing by 

topical subject. 

Table H-1. Standing Operating Procedures and Enewetak Atoll Instructions 

Document 

Number Title Revisions and Changes Date 

SOP 608-01 Air Particulate Sampling Procedures Original July 21, 1977 

SOP 608-02 Debris Survey Procedures Original 

608-02.1 

608-02.02 

608-02.02 CT1†

608-02.02 CT2 

n/a*

December 3, 1977 

May 3, 1978 

July 2, 1978 

July 15, 1978 

SOP 608-03 Decontamination of Facilities and 

Equipment 

Original 

608-03.1 

608-03.01 CT1 

October 18, 1977 

December 12, 1977 

August 18, 1978 

SOP 608-04 Hotline Procedures Original 

608-04.1 

July 5, 1977 

March 17, 1979 

SOP 608-05 Respiratory Protection Original July 5, 1977 

SOP 608-06 Radioactive Source Test Procedures Original October 12, 1977 

SOP 608-07 Source Accountability and Control 

Procedures 

Original October 12, 1977 

SOP 608-08 Radiological Guidelines for Ground 

Zero Operations 

Original November 9, 1977 

SOP 608-09 Runit Contamination Control Area 

Procedures 

Original 

608-09.1 

June 2, 1978 

January 25, 1980 

SOP 608-10 Decontamination Laundry Procedures Original July 2, 1978 

SOP 608-11 Disposal of Laboratory Generated 

Radioactive Waste 

Original July 17, 1978 

SOP 608-12 Air Sampler Maintenance for the 

M-102 Air Sampler 

Original August 15, 1978 

SOP 608-13 Microwave Oven Survey Program Original November 27, 1978 

SOP 608-14 Radiological Certification of 

Enewetak Atoll Retrograde 

Equipment 

Original March 18, 1979 
237

Table H-1. Standing Operating Procedures and Enewetak Atoll Instructions (cont.) 

SOP 609-01 Sample Data Records Original July 17, 1978 

SOP 609-02 Radiation Dosimetry Records Original 

609-02.1 

July 21, 1977 

November 17, 1978

SOP 609-03 Radiation Control Sample 

Identification Procedures 

Original 

609-03.1 

July 17, 1978 

March 5, 1979 

SOP 609-04 Bioassay Procedures Original 

609-04.01 

609-04.01 CT1 

July 20, 1977 

May 4, 1978 

December 18,1978 

EAI 5101 Radiation Control Committee Original 

5101.1 

5101.2 

n/a 

November 17, 1978 

January 25, 1980 

EAI 5701 Radiological Briefing for Arriving 

Persons, Enewetak 

Original August 15, 1977 

EAI 5702 Access to Radiologically Controlled 

Islands 

Original 

5702 CT1 

August 15, 1977 

March 17, 1979 

EAI 5703 Radiation Monitoring of Blasting 

Operations 

Original October 18, 1977 

EAI 5704 Radioactive Source Test Procedures Original October 29, 1977 

EAI 5705 FRST Training Original February 1, 1978 

EAI 5706 Administration of Personnel 

Dosimetry Program 

Original 

5706.01 

5706.02 

n/a 

March 3, 1979 

January 24, 1980 

EAI 5707 Personnel Protection Levels Original 

5707.1 

April 3, 1978 

November 17, 1978

EAI 5708 Bulk Soil Haul Monitoring Procedures 

Renamed as: 

Overwater Transportation of 

Contaminated Soil 

Original 

5708 CT1 

5708 CT2 

5708.1 

5708.1 CT1 

June 7, 1978 

July 15, 1978 

August 22, 1978 

November 18, 1978 

March 17, 1979 

EAI 5709 Island Debris Removal Completion 

Procedures 

Original June 7, 1978 

EAI 5710 Radiological Control of Personnel 

Injured in Controlled Areas 

Original July 1, 1978 

EAI 5711 Tour Extension Eligibility – 

Radiological Considerations 

Original 

5711 CT1 

August 19, 1978 

September 21, 

1978 

*

 “n/a” indicates that the date was not available. 

†

 “CT” indicates “Change Transmittal” 
238

Appendix I. 

Questionnaire for Radiation Dose Assessment for Veterans of the 

Enewetak Cleanup Project (1977–1980) 

This appendix contains the questionnaire that is sent to an ECUP veteran upon receipt of 

a valid claim or inquiry by the DTRA NTPR Program. The questionnaire is used to collect 

veteran-specific information that can be used to adjust or complement the scenarios of exposures 

and assumptions identified in this report in order to produce an individualized radiation dose 

assessment. 
239

DEFENSE THREAT REDUCTION AGENCY

QUESTIONNAIRE FOR RADIATION DOSE ASSESSMENT FOR 

VETERANS OF THE ENEWETAK CLEANUP PROJECT (1977–1980) 

AGENCY DISCLOSURE NOTICE 

The public reporting burden for this collection of information is estimated to average 60 minutes per response, including 

the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and 

completing and reviewing the collection of information. Send comments regarding this burden estimate or any other 

aspect of this collection of information, including suggestions for reducing the burden, to the Department of Defense, 

Washington Headquarters Services, Executive Services Directorate, Information Management Division, 4800 Mark 

Center Drive, East Tower, Suite 02G09, Alexandria, VA 22350-3100 (0704-0447). Respondents should be aware that 

notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a 

collection of information if it does not display a currently valid OMB control number. 

Indicate Assignment Category

(A list and a map of the Enewetak Atoll islands are enclosed for 

reference)

Complete these Sections of 

the Questionnaire

 (a) You were assigned duties on Enewetak Island and/or Lojwa Island 

with no work duties on other islands, OR 

(b) you were in transit through Enewetak Atoll and did not participate 

in cleanup activities 

I, II, III, IV and VII 

 You were assigned duties only on the southern islands of Enewetak 

Atoll other than residence islands 

I, II, III, V and VII 

 You were assigned duties on the northern islands of Enewetak Atoll, 

with or without duties on the southern islands 

I, II, III, VI and VII 

SECTION I: PARTICIPANT CONTACT INFORMATION 

Name of Veteran: (Last, First, Middle Initial) Service Number: Social Security Number: 

Mailing Address: 

Telephone: Cell Phone: Email: 

If this questionnaire is completed by someone other than the participant, please provide the following: 

Name: (Last, First, Middle Initial)

Mailing Address: 

Telephone: Cell Phone: Email: 

OMB No. 0704-0447 
240

Relationship to veteran: 

SECTION II: ASSIGNMENT SUMMARY (DURING ENEWETAK CLEANUP PROJECT) 

Military Service Unit of Assignment during Enewetak Cleanup 

Project 

Dates of Assignment at 

Enewetak Atoll Rate/Rank 

Person(s) who Served with You 

Arrival Date Departure Date Job Occupation

SECTION III: SKIN CANCER CLAIMS ONLY 

If you are filing for a VA disability claim due to, or partly due to, skin cancer or melanoma, provide the 

following information: 

Height: feet inches 

Physical location(s) of skin cancer or melanoma on the body: 

 
241

SECTION IV: SUPPORT PERSONNEL WITH DUTIES ON 

ENEWETAK ISLAND OR LOJWA ISLAND 

The questions in this section are intended to assess your potential for radiation exposure as a military support 

person who was assigned duties on Enewetak Island and/or Lojwa Island with no work duties on other 

islands, or were in transit through Enewetak Atoll during the Enewetak Cleanup Project for any time 

period from January 1, 1977 to December 31, 1980. Please provide detailed answers to the best of your 

recollection. Qualify as “approximate” where necessary. If you are unable to answer a question, state 

“unknown”. If more space is needed for any question, use additional sheets and include reference to section 

and question numbers. 

1. List all specific duties and related job descriptions that you performed while on Enewetak Island 

(Letter “E”) or Lojwa Island (Letter “L”): 

Duty Island

(Write E or L) Duty and Job Description 

2. Did you handle, transport, work in close proximity or come into contact with objects or materials 

contaminated with radioactive material? 

Yes ___ No ___ 

If “No”, go to the next numbered question. If “Yes”, answer the following questions: 

a. Describe your activities and circumstances for handling, transporting or working near objects or 

materials with radioactive contamination: 

b. Approximately how many times were you exposed to radioactive contamination? 

c. On average, how much time did each event take? 
242

3. Did you visit islands other than Enewetak or Lojwa Islands? 

Yes ___ No ___ 

If “No”, go to the next numbered question. If “Yes”, answer the following question: 

a. List the name of the islands you visited, how long the visits lasted, and describe the purpose of 

each visit (see enclosed list and map of islands for reference; list name or two-letter code in the 

left-hand column below): 

Island Visited Duration Purpose of Visit 

4. Are there any other duties, actions or locations that you think may have caused you to be exposed to 

radiation during your participation in the Enewetak Cleanup Project? 

5. On which island were you billeted and what was the type of your living quarters (for example, tent, 

building, etc.)? 

6. Where did you eat your meals while on Enewetak or Lojwa Islands? 

7. Were you instructed NOT to consume locally gathered foods? Yes ___ No ___ 
243

8. If you consumed locally gathered food, what foods did you consume; include approximate quantity 

and how often? 

9. Were you issued personal dosimeters during your assignment at Enewetak Atoll (film badges, TLDs 

or pocket dosimeters)? 

Yes ___ No ___ 

If “No”, go to question 11. If “Yes”, answer the following question: 

a. Provide details, such as what kind of dosimeter(s) you were provided, when did you wear them, in 

what areas, etc.: 

10. Were you advised of the results of the dose readings from your personal dosimeters? 

Yes ___ No ___ 

If “No”, go to next numbered question. If “Yes”, answer the following question: 

a. Provide any details about the doses from your dosimeters: 

11. Additional Comments: Please add any information related to your potential exposure to radiation that 

you believe was not covered under the questions in this section: 
244

SECTION V: PERSONNEL WITH DUTIES ON THE SOUTHERN ISLANDS 

OF ENEWETAK ATOLL (REFER TO THE ENCLOSED LIST AND MAP) 

The questions in this section are intended to assess your potential for radiation exposure as a military service 

member who was assigned duties on non-residence southern islands of Enewetak Atoll (refer to the 

enclosed list of islands and map) during the Enewetak Cleanup Project for any time period from January 1, 

1977 to December 31, 1980. Please provide detailed answers to the best of your recollection. Qualify as 

“approximate” where necessary. If you are unable to answer a question, state “unknown”. If more space is 

needed for any question, use additional sheets and include reference to section and question numbers. 

1. To the best of your recollection, list specific duties and related job descriptions that you performed on 

the southern islands of Enewetak Atoll. (If more space is needed, use additional sheets and include 

reference to section and question numbers): 

Duty Island Duty and Job Description 

2. Did you handle, transport, work in close proximity or come into contact with objects or materials 

contaminated with radioactive material? 

Yes ___ No ___ 

If “No”, go to the next numbered question. If “Yes”, answer the following questions: 

a. Describe your activities and circumstances for handling, transporting or working near objects or 

materials with radioactive contamination: 

b. Approximately how many times were you exposed to radioactive contamination? 

c. On average, how much time did each event take? 
245

3. Did you visit any of the northern islands of Enewetak Atoll? 

Yes ___ No ___ 

If “No”, go to the next numbered question. If “Yes”, answer the following question: 

a. Describe the purpose of your visits, the name of the islands you visited, and how long the visits 

lasted: 

Island Visited Duration Purpose of Visit 

4. Are there any other duties, actions or locations that you think may have caused you to be exposed to 

radiation during your participation in the Enewetak Cleanup Project? 

5. On which island were you billeted and what was the type of your living quarters (for example, tent, 

building, etc.)? 

6. Where did you eat your meals: 

a. While at work on southern islands? 

b. On your residence island while off-duty? 

7. Were you instructed NOT to consume locally gathered foods? Yes ___ No ___ 
246

8. If you consumed locally gathered food, what foods did you consume; include approximate quantity 

and how often? 

9. Were you issued personal dosimeters during your assignment at Enewetak Atoll (film badges, TLDs, 

and pocket dosimeters) 

Yes ___ No ___ 

If “No”, go to question 11. If “Yes”, answer the following question: 

a. Provide details, such as what kind of dosimeter(s) you were provided, when did you wear them, in 

what areas, etc.: 

10. Were you advised of the results of the dose readings from your personal dosimeters? 

Yes ___ No ___ 

If “No”, go to next numbered question. If “Yes”, answer the following question: 

a. Provide any details you remember about the doses from your dosimeters: 

11. Additional Comments: Please add any information related to your potential exposure to radiation that 

you believe was not covered under the questions in this section: 
247

SECTION VI: PERSONNEL WITH DUTIES ON THE NORTHERN ISLANDS 

OF ENEWETAK ATOLL (REFER TO THE ENCLOSED LIST AND MAP) 

The questions in this section are intended to assess your potential for radiation exposure as a military service 

member who was assigned duties on the northern islands of Enewetak Atoll (refer to the enclosed list of 

islands) during the Enewetak Cleanup Project for any time period from January 1, 1977 to December 31, 1980. 

You may have been assigned duties on the southern islands in addition to the northern islands. Please provide 

detailed answers to the best of your recollection. Qualify as “approximate” where necessary. If you are unable 

to answer a question, state “unknown”. If more space is needed for any question, use additional sheets and 

include reference to section and question numbers. 

IMPORTANT NOTE: The Defense Threat Reduction Agency, formerly the Defense Nuclear Agency who was 

the lead agency of the Enewetak Cleanup Project, generally has a complete record of personnel who visited the 

restricted access northern islands of the Enewetak Atoll by individual’s name, island name and date. This 

information will be combined with your responses to the questions below, which should include details about 

your specific job activities, the environmental and site conditions where you worked and radiological protection 

afforded to you when deemed necessary. 

1. Check all cleanup project tasks that you were involved in. List your job occupation and include any 

relevant comments in the right-hand column below. To assist in your dose assessment, include 

quantitative information, such as average number of hours per work day engaged in listed tasks, 

number of times per day, work environment (for example dusty, or soil wetted down, etc.): 

Tasks Performed 

(check all that apply) 

What was your job occupation 

(include island names and any other comments) 

Contaminated soil cleanup

□ Brush clearing/removal 

□ Soil removal 

□ Soil loading 

□ Soil trucking 

□ Transport by boat 

□ Concrete/Slurry mixing plant 

□ Tremie operations (specify your role) 

Debris cleanup (contaminated) 

□ Collection onshore 

□ Collection offshore 

□ Loading 

□ Offloading at disposal sites 

□ Transport by boat 
248

□ Transport by barge 

□ Transport by floating platform 

□ Crater disposal in (specify your role) 

Debris cleanup (non-contaminated) 

□ Collection 

□ Transport 

□ Disposal 

Radiological support 

□ Radiological control 

□ Radiological survey and monitoring 

□ Sample collection 

□ Radiological laboratory support 

□ Radiation control at Army-operated 

decontamination laundry 

□ Radiation safety audit and inspections 

Inter-island transport / logistics 

□ Water-based □ Air-based 

□ Transport of personnel and equipment 

□ Transport of cargo (construction 

materials, water, food, etc.) 

□ Boat maintenance 

□ Aircraft maintenance 

Other activities not listed above 

□ 

□ 

□ 
249

2. What was your typical work schedule? 

a. How many work days per week: __________ 

b. Average hours on northern island(s) per work day: ___________ 

3. If you were involved in contaminated soil removal, transport or disposal, please answer the following 

questions: 

a. Was the soil wetted down before removal? .................................................. Yes ___ No ___ 

b. Was the soil wetted down after it was loaded for transport by trucks? ......... Yes ___ No ___ 

c. Was the soil covered with a tarp during transport by truck? ......................... Yes ___ No ___ 

d. Was the soil wetted and covered with tarp during transport by boats? ......... Yes ___ No ___ 

4. Please answer the following questions about personnel protection equipment (PPE): 

a. What type of respiratory protection or other personnel protection equipment (PPE) were you 

provided while working with contaminated soil or other duties at locations where contaminated 

soil was handled (check all that applies)? 

□ Full-face mask respirator □ Half-face mask 

respirator 

□ Dust mask □ Anti-contamination clothing (Anti-C) 

□ Rubber boots □ Gloves □ None 

□ Other, describe: 

b. If you used a respirator, what type of respirator did you wear? 

□ Supplied/forced air □ Filter cartridge □ Did not use a respirator 

c. If you wore a full-face or half-face mask respirator, were you given a fit test? 

Yes ___ No ___ 

d. Provide detailed description of your work in areas where contaminated soil was disturbed and 

your use of respiratory protection and other personnel protection equipment: 
250

5. Did you handle, transport, work in close proximity or come into contact with objects or materials 

contaminated with radioactive material? 

Yes ___ No ___ 

If “No”, go to the next numbered question. If “Yes”, answer the following questions: 

a. Describe your activities and circumstances for handling, transporting or working near objects or 

materials with radioactive contamination: 

b. Approximately how many times were you exposed to radioactive contamination? 

c. On average, how much time did each event take? 

6. Are there any other duties, actions or locations that you think may have caused you to be exposed to 

radiation during your participation in the Enewetak Cleanup Project? 

7. On which island were you billeted and what was the type of your living quarters (for example, tent, 

building, etc.)? 

8. Where did you eat your meals: 

a. While at work on northern islands? 

b. On your residence island while off-duty? 

9. Were you instructed NOT to consume locally gathered foods? Yes ___ No ___ 
251

10. If you consumed locally gathered food, what foods did you consume; include approximate quantity 

and how often? 

11. Were you issued personal dosimeters during your assignment at Enewetak Atoll (film badges, TLDs, 

and pocket dosimeters) 

Yes ___ No ___ 

If “No”, go to question 13. If “Yes”, answer the following question: 

a. Provide details, such as what kind of dosimeter(s) you were provided, when did you wear them, in 

what areas, etc.: 

12. Were you advised of the results of the dose readings from your personal dosimeters? 

Yes ___ No ___ 

If “No”, go to next numbered question. If “Yes”, answer the following question: 

a. Provide any details you remember about the doses from your dosimeters: 

13. Additional Comments: Please add any information related to your potential exposure that you believe 

was not covered under the questions in this section: 
252

SECTION VII: SIGNATURE 

I certify under penalty of perjury under the laws of the United States of America that the information provided on this 

form is true and correct. 

Print Name: 

Signature: Date: 

SECTION VIII: PRIVACY ACT STATEMENT 

AUTHORITY: 42 U.S.C. 2013 (AEC), 38 U.S.C. 1154 and 1112 (Veterans Benefits), 42 U.S.C. 2210 (DOJ 

compensation program), Pub. L. 108-183 section 601 (Veterans Benefits Act of 2003), Pub. L. 94-367, Pub. L. 100-426 

(Radiation Exposure Compensation Act) amended by Pub. L. 100-510, and E.O. 9397 (SSN). 

PURPOSE(S): For use by agency officials and employees, or authorized contractors, and other DoD components to 

provide data or documentation relevant to the processing of administrative claims or litigation; to conduct scientific 

studies or medical follow-up programs; and in the preparation of the histories of nuclear test programs. 

ROUTINE USES: Disclosure of records permitted outside DoD under 5 U.S.C. 552a(b) (Privacy Act) to the Department 

of Veterans Affairs, Department of Justice, and Department of Labor for identifying and processing claims by individuals 

who allege job-related disabilities as a result of participation in nuclear test programs and for litigation actions, Veterans 

Advisory Board on Dose Reconstruction for the purpose of reviewing and overseeing the DoD Radiation Dose 

Reconstruction Program audits of dose reconstructions and to the Department of Health and Human Services, National 

Council on Radiation Protection & Measurements, and Vanderbilt University for the purpose of conducting 

epidemiological studies on the effects of ionizing radiation on participants of nuclear test programs. The DoD 'Blanket 

Routine Uses' also apply. 

DISCLOSURE: Voluntary. However, failure to provide the requested information and authorization may delay or 

preclude DTRA from providing or releasing information. 
253

Appendix J. 

Lagoon and Ocean Water Activity Concentrations 

Sampling locations and activity concentrations of radionuclides detected in water samples from 

the Enewetak Lagoon, craters on several islands of the atoll, and the ocean near the atoll are presented 

in this Appendix. The information is taken from various figures and tables in (AEC, 1973a) as 

indicated below. 

Fifty-four results from water samples obtained during the 1972 radiological survey are 

available in AEC (1973a). The sampling locations of these 54 lagoon, crater, and ocean water samples 

are shown in Figure J-1 (AEC 1973a, Figure 79). Sample identification numbers are given in 

Figure J-1 next to each sampling location, followed by the sampling depth in feet. Water activity 

concentrations measured in these samples are shown in Table J-1. 

Figure J-1. Location, identification, and sampling depth of 55-liter water samples 

(AEC 1973a, Figure 79) 
254

Table J-1. Sample characteristics and activity concentrations of Enewetak Atoll lagoon, crater, and ocean water samples 

Sample 

ID # 

Sampling 

Location*

Sampling 

Depth (ft) 

Water sample activity concentration (fCi L−1)

†, ‡

Cs-137 Pu-239/240 Pu-238 Co-60 Eu-155 Bi-207 Am-241 

79 Lagoon 3 296 6.0 1.1 -

§

- - - 

80 Lagoon 3 471 32.5 2.7 - - - - 

81 Mike crater 93 3200 54.6 1.9 - - - - 

82 Mike crater 3 730 23.4 2.0 - - - - 

103 Lagoon 3 486 43.6 6.8 116 - < 224 - 

104 Lagoon 3 241 13.1 1.9 - - - - 

105 Lagoon 150 300 17.4 2.5 - - - - 

106 Lagoon 3 342 22.4 2.2 - - - - 

107 Lagoon 95 190 9.6 0.9 - - - - 

108 Lagoon entrance 3 229 10.2 1.1 - - - - 

109 Lagoon entrance 3 228 9.6 1.0 - - - - 

110 Lagoon 3 377 28.9 3.8 - - - - 

111 Lagoon 3 258 11.6 1.4 - - - - 

112 Lagoon 3 163 15.4 1.9 146 - < 53 - 

113 Lagoon 3 170 4.8 0.6 - - - - 

114 Lagoon 3 462 51.9 7.1 518 - - - 

116 Ocean 3 32 0.43 0.01 - - - - 

117 Lagoon 3 107 11.8 1.7 - - - - 

118 Koa crater 50 1100 26.4 3.2 - - - - 

119 Lagoon 3 290 18.0 2.3 - - - - 

120 Lagoon 3 228 7.4 1.1 - - - - 

121 Lagoon entrance 90 251 2.8 0.14 - - - - 

123 Koa crater 108 8910 1510 236 354 1433 420 346 

124 Lagoon 3 579 71.2 10 < 68 - 734 - 

125 Lagoon 3 59 6.8 1.6 - - - - 

126 Lagoon 3 322 30.4 3.9 < 67 - 261 - 

127 Koa crater 3 1170 19 1.7 - - - - 

128 Lagoon 3 532 33.1 3 - - - - 

129 Lagoon 3 538 44.4 4.4 < 40 - 570 - 
255

Sample 

ID # 

Sampling 

Location*

Sampling 

Depth (ft) 

Water sample activity concentration (fCi L−1)

†, ‡

Cs-137 Pu-239/240 Pu-238 Co-60 Eu-155 Bi-207 Am-241 

365 Lagoon 195 427 3780 1280 842 940 1266 314 

366 Lagoon 3 499 77.0 13.3 121 - 258 - 

367 Lagoon 3 482 66.2 7.9 - - - - 

368 Lagoon 3 410 96.1 14.9 138 - 204 - 

371 Lagoon 111 305 75.2 11.2 - - - - 

373 Mike crater 46 4220 71.9 7.0 136 - < 88 - 

374 Lagoon 175 462 63.2 9.0 118 - < 242 - 

375 Lagoon 3 305 29.0 3.7 - - - - 

376 Lagoon 3 250 18.6 2.6 - - - - 

377 Lagoon 3 364 62.9 9.7 < 51 - 413 - 

378 Lagoon 167** 497 43.1 7.1 - - - - 

379 Lagoon 3 246 14.5 2.1 - - - - 

381 Lagoon 3 176 6.8 0.7 - - - - 

382 Lagoon 3 766 54.3 4.0 - - - - 

383 Lagoon 182 295 53.3 4.6 < 50 67 683 36 

384 Ocean 3 146 0.21 0 - - - - 

385 Lagoon entrance 3 130 1.6 0.5 - - - - 

386 Lagoon 3 291 13.9 2.0 < 61 - 154 - 

387 Lagoon 3 109 0.38 0.03 - - - - 

611 Seminole Crater 3 970 1330 411 - - - - 

612 Seminole Crater 3 212 302 65 - - - - 

613 Lacrosse Crater 3 118 57 26 - - - - 

614 Cactus Crater 3 935 185 98 - - - - 

615 Lacrosse Crater 3 108 46 24 - - - - 

616 Cactus Crater 3 302 105 52 - - - - 

*

 See Figure J-1 for sampling locations. Crater locations are identified in Table 58 of AEC (1973a); Sample 612 is incorrectly omitted from Table 58. 

†

 Values for Cs-137, Pu-239/240, and Pu-238 are from Table 55 of AEC (1973a). Values for Co-60, Eu-155, Bi-207, and Am-241 are from Table 54 of 

AEC (1973a). Values are shown as reported in these tables. Results for several other radionuclides (Rh-102m, Ru-106, Sb-125, Eu-152, and U-235) were 

below detection limits in all samples (AEC, 1973a). 

‡

 The unit “fCi L−1” is the same as “fCi kg−1” in AEC (1973a). 

§

 "-" indicates no result reported. 

** The depth shown for Sample 378 in Figure J-1 extracted from AEC (1973a, Figure 79) is assumed incorrect. The correct value is reported here and in 

Table 55 in AEC (1973a).
256 

Appendix K. 

Validation of the Methodology for Estimating External Doses Associated with 

Handling Contaminated Debris during the Enewetak Cleanup Project 

K-1. Introduction 

Exposure rate measurements of contaminated debris were made in a 1972 radiological 

survey performed by teams of the Atomic Energy Commission (AEC) at Enewetak Atoll (AEC, 

1973a). The islands from which contaminated debris was removed during ECUP were Janet 

(Enjebi), Pearl (Lujor), Ruby (Eleleron), Sally (Aomon), and Yvonne (Runit) (DNA, 1981). In 

this appendix, debris exposure rate data are analyzed and compared with the island-average 

exposure rates estimated from the 1972 aerial surveys performed by the AEC. Such a 

comparison allows the validation of the methodology recommended for using island-average 

exposure rates to assess external doses for ECUP participants who were involved in the cleanup 

and handling of contaminated debris as discussed in Section 6 of this technical report. 

K-1.1. Background 

During the preparation of the original version of this technical report in 2018, 

contaminated debris external exposure rate data collected during ECUP 1977–1980 were not 

available. Later, debris exposure rate measurements made during the 1972 radiological survey 

and reported in AEC (1973a) were located, compiled, and analyzed. 

K-1.2. Purpose 

The analysis in this appendix is provided to validate the hypothesis that island-average 

exposure rates constitute high-sided values when compared to exposure rates associated with 

contaminated debris. 

K-1.3. Scope and Objectives 

The analysis in this appendix applies to individuals who handled contaminated debris 

during ECUP using heavy equipment such as front loaders, cranes with clamshells, and trucks. 

These workers moved contaminated debris within a given island and consolidated it into piles on 

the island shorelines in preparation for transport and disposal offshore. The analysis does not 

apply to personnel who performed activities related to boat transport of contaminated debris, 

beach cleanup teams, or those who were involved in handling red debris destined for disposal in 

the Cactus Crater on Yvonne (Runit) island. 

The objectives of the validation analysis are to: 

 Develop a methodology for comparing island-average exposure rates from the 1972 

aerial surveys with debris exposure rate data collected from direct measurements 

performed by AEC in the 1972 radiological survey 

 Determine exposure rates at distances representative for ECUP workers who performed 

debris cleanup activities described above 
257 

 Compare debris exposure rate data with island-average exposure rates and develop 

appropriate recommendations. 

K-2. Methodology for Estimating and Comparing Debris Exposure Rates 

K-2.1. Debris Exposure Rate Data 

According to DNA (1981), contaminated debris was removed from five islands: Janet 

(Enjebi), Pearl (Lujor), Ruby (Eleleron), Sally (Aomon), and Yvonne (Runit). Contemporaneous 

debris exposure rate data were not available. However, contact exposure rate data and location of 

contaminated debris from radiological surveys performed in 1972 by AEC were reported in a 

series of maps for the five islands of interest in AEC (1973a). Descriptions and map locations of 

such debris are indexed and catalogued in the report of the Engineering Study for a Cleanup Plan 

of the Enewetak Atoll (H&N, 1973). 

Attachment I of this appendix contains the 17 map sheets applicable to the five islands of 

interest, and exposure rate data are presented in Attachment II of this appendix. Each data point 

is numbered sequentially on each map sheet to establish a cross-reference between Attachment I

and Attachment II by island name, sheet number, and location number. 

K-2.2. Representative Exposure Distances and Debris Pile Size 

Typical ECUP scenarios depicted in DNA (1981) are for ECUP workers operating a front 

loader or a crane with a clamshell loading debris into dump trucks or offloading debris in the 

lagoon. Another relevant scenario is that of truck drivers transporting loads of debris from its 

original location to stockpiles near the beach for later transport to disposal areas. The estimated 

distance a person was positioned from debris in loading and transport scenarios is about 10 ft or 

more, and over 20 ft for crane/clamshell movement of debris. Situations where debris cleanup 

workers walked close to piles of contaminated debris are possible. However, operators of debris 

moving machinery and dump trucks rarely would have been located in close proximity of debris 

piles, as they may only have walked close-by to check on mechanical equipment problems or 

physical obstacles over short durations, i.e., minutes. For this reason, exposures at distances 

closer than 10 ft are not considered, and when relevant, these scenarios can be assessed on a 

case-by-case basis using the methodology described in Section K-2.3. 

From a review of pictures in DNA (1981), debris piles were typically 10 to 20 ft in 

length. A more objective estimate of average pile sizes can be made using the total volume of 

contaminated debris removed from each island (DNA, 1981). Using these, total volumes, 

average pile volumes are estimated by assuming that each contact measurement greater than or 

equal to the criterion of 15 μR h

−1

 for yellow debris (DNA, 1981) represented a pile of 

contaminated debris moved by ECUP personnel. To calculate an average size pile for each 

island, the total volume of contaminated debris removed from the island is divided by the 

number of measurements greater than or equal to 15 μR h

−1

. The average pile volumes thus 

calculated are shown in Attachment III. 

K-2.3. Estimation of Mean Debris Exposure Rates 

Three commonly used radiation source models were considered to estimate external 

exposure rate as a function of distance from debris: point source, line source, and disk source. 

The point source model assumes that the size of the source is small compared to the distance to a 
258 

point of exposure. The other two models assume that concentrations of radionuclides are 

distributed uniformly along a line of a finite length or on the surface of a circular disk of a finite 

radius. Equations K-1, K-2, and K-3 below are adapted from Cember and Johnson (2008) and 

show the exposure rate as a function of distance d for a point, line, and disk source, respectively. 

() = () ×









(K-1)

where 

Ipt(d) = Exposure rate at distance d from a point source (μR h

−1

)

Ipt(d0) = Exposure rate at distance d0 from a point source (μR h

−1

) 

d0 = Distance from a radiation source with known exposure rate Ipt(d0) (ft) 

d = Distance from debris that ECUP exposure occurs (ft) 

() = () ×

() × 

 

(K-2)

where 

Iline(d) = Exposure rate at distance d from a line source, at the mid-point of the line source 

(μR h

−1

)

Iline(d0) = Exposure rate at distance d0 from a line source, at the mid-point of the line 

source (μR h

−1

) 

Θ(d) = Angle formed from a point at distance d and the ends of the line source (radians) 

Θ0 = Angle formed from a point at d0 and the ends of the line source (radians) 

() = () ×

ln 1 +











ln 1 +







(K-3)

where 

Idisk(d) = Exposure rate at distance d from a disk source, at the center-line of the disk 

source (μR h

−1

)

Idisk(d0) = Exposure rate at distance d0 from a disk source, at the center-line of the disk 

source (μR h

−1

) 

R = Radius of disk source (ft) 

Figure K-1 shows the graphical representation of the exposure rate as a function of 

distance for each of the three models described above and assuming uniformly distributed 

sources for the line and disk source with a known exposure rate of 1 μR h

−1

 at a distance d0 of 

0.5 ft. In this figure, a 5-foot-radius disk source and a 10-foot-long line source are used to 

estimate exposure rates at various distances from the source. 
259 

Figure K-1. Exposure rate as a function of distance from radiation sources 

The point source model in Figure K-1 shows considerably lower exposure rates at 

distances to over 20 ft as compared to the line or disk source models. However, the disk source is 

in general a better representation of the geometry of a debris pile than a point source or a onedimensional line source at the exposure distances under consideration in this evaluation. The disk 

source model also provides more conservative estimates of exposure rate as a function of 

distance than the line or point source models. Therefore, the disk model is selected for the 

remainder of the analysis to estimate exposure rates for personnel involved in moving, loading 

and transporting contaminated debris. The results are presented in Section K-3. 

To estimate debris exposure rates at the representative exposure distance of 10 ft, a disk 

with a radius of 5 ft is used for modeling a roughly 10-foot-wide debris pile. Calculations using a 

disk with a 10-foot radius are also made. These dimensions are consistent with the radii derived 

from the average-size piles for each island (see Section K-2.2 and Attachment III). These radii 

for the average debris pile for each island are derived by first representing the average pile 

volume as an idealized cube, and then calculating the facing area of one side of each cube. Then, 

the radius of a disk with the same facing area as the cube is calculated. The range of radii thus 

calculated for the five islands of interest is about 3–9 ft (see Attachment III). Mean exposure 

rates calculated using these radii and an exposure distance of 10 ft are also shown in 

Attachment III. 

To calculate the mean debris exposure rate for each of the five islands identified above 

that is applicable to personnel who handled contaminated debris, the 5-foot-radius disk source 

model is used to obtain the exposure rate at the representative distance of 10 ft using 

Equation (3). To determine the mean exposure rate for each island, 1) exposure rates are 

calculated at the 10-foot exposure distance for each reported measurement shown in 

Attachment II, assuming a representative measurement distance (d0) of 0.5 ft, and 2) the mean of 

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 2 4 6 8 10 12 14 16 18 20

N

orm

aliz

e

d

E

x

p

o

s

ure

R

ate (μ

R

h−1

)

Distance (ft)

Disk Source (R = 5 ft)

Line Source (L = 10 ft)

Point Source

Calculated exposure rates are 

normalized to an exposure rate of 

1 μR h

−1

 at 0.5 ft from the source. 
260 

all 10-foot exposure rates is calculated, which constitutes the mean debris exposure rate for each 

of the five islands. These island mean exposure rates are then compared to the island-average 

exposure rates as shown in Section K-3. 

K-2.4. Comparison of Mean Debris and Island-Average Exposure Rates 

In the original 2018 version of this technical report, an example dose assessment for 

debris cleanup personnel was included. As a preliminary approach, the island-average exposure 

rates were used to estimate the external dose. In doing so, it was assumed that the mean exposure 

rates of contaminated debris were lower than the island-average exposure rates. Therefore, the 

estimated external dose would be high-sided. The rationale was that the island-average exposure 

rates, which were derived from the 1972 aerial surveys and some field measurements, included 

contributions from both soil contamination and radiation emitted by localized sources that 

included piles of contaminated debris. 

To validate the above assumptions and rationale, a comparison is made between the 

island-average exposure rate and the estimated mean debris exposure rate for each of the five 

islands identified in Section K-2.1. For each of the five islands that contained contaminated 

debris, the mean of the debris exposure rates is calculated for a representative exposure distance 

of 10 ft. Because of the exponential nature of the exposure rate datasets (see Attachment II), they 

are positively skewed, suggesting lognormal distributions. In addition, most of the medians are 

not significantly different from the geometric means, again suggesting lognormal distributions. 

Therefore, the geometric mean is judged the most appropriate estimate of central tendency 

(NCRP, 2007). The geometric mean is considered most representative of the average debris 

exposure rate to which a debris cleanup worker would have been exposed on any of the five 

islands. 

K-3. Results and Discussion 

K-3.1. Mean Contaminated Debris Exposure Rates 

The mean of the debris contact exposure rate measurements as well as corresponding 

median, minimum, and maximum values for each island are shown in Table K-1. Contact 

exposure rate measurements were made as close to the debris material as possible, within a few 

inches. In this analysis, the assumption that the measurement distance was 0.5 ft is conservative, 

leading to higher estimated rates at the exposure distance of 10 ft. The debris contact exposure 

rate measurements are provided in Attachment I (maps) and Attachment II (Tables). Table K-1

also includes the number of measurements for each island. It provides the calculated mean 

exposure rates at the exposure distance of 10 ft estimated using a disk source with a 5-foot 

radius. 
261 

Table K-1. Contaminated debris exposure rates measured at contact 

and calculated at 10 ft 

Islands with 

Contaminated 

Debris

Number of 

Measurements

Contact Measurement (μR h−1)

* Calculated 

Mean‡ at 10 ft 

(μR h−1 Mean )

† Median Min Max 

Janet (Enjebi) 160 27 19 3 8,500 1.3 

Yvonne (Runit) 85 29 30 1 60,000 1.4 

Pearl (Lujor) 15 147 250 3 5,000 7.1 

Ruby (Eleleron) 6 19 18 6 120 0.93 

Sally (Aomon) 10 35 19 8 3,000 1.7 

*

 It is assumed that contact measurements were made within a few inches of the surface of the debris. To high 

side the calculated exposure rates in this table, measurements are assumed made at 0.5 ft. 

†

 Geometric mean. 

‡

 Calculated exposure rates are estimated for each debris contact measurement, from a disk source with a 5-foot 

radius at an exposure distance of 10 ft. This exposure distance is assumed the closest distance at which 

personnel would have typically handled contaminated debris using heavy equipment. 

K-3.2. Comparison of Mean Debris Exposure Rates with Island-average Exposure Rates 

The calculated exposure rates at the representative distance of 10 ft, shown in Table K-1, 

are compared with the island-average exposure rate as shown in Table K-2. The side-by-side 

comparison in Table K-2 shows that the island-average exposure rates derived from the 1972 

aerial surveys are factors of about 4 to 30 above the means of the debris exposure rates at 10 ft 

calculated using a 5-foot disk source. Similar exposure rates estimated using a 10-ft radius disk 

source result in such factors being 2 to 13. A 10-foot radius disk encompasses the calculated disk 

radii of the average contaminated debris piles on the five islands (see Attachment III, 

Table III-1). 

Table K-2. Comparison of mean calculated exposure rates from contaminated debris data 

and island-average exposure rates from 1972 aerial survey 

Island with Contaminated 

Debris 

Debris Mean 

Exposure Rate at 10 ft 

(μR h−1) 

Island-Average 

Exposure Rate 

(μR h−1)

* 

Janet (Enjebi) 1.3 40 

Yvonne (Runit) 1.4 33 

Pearl (Lujor) 7.1 70 

Ruby (Eleleron) 0.93 14 

Sally (Aomon) 1.7 7 

*

 From 1972 aerial survey, estimated at 1 meter from the ground (AEC, 1973a).
262 

In summary, despite the broadness of the debris exposure rate data, it is found that the 

island-average exposure rates are considerably higher than the mean of the debris exposure rates 

for all five islands at the representative distance of 10 ft. However, given the existence of debris 

at several locations on the five islands with rather high exposure rates as shown in Appendix K

and Attachment II, it is possible that an individual was exposed at levels higher than the 

island-average exposure rates. In such a case, dose estimates can be based on a single or a 

combination of debris exposure rate measurements that are selected based on a veteran’s 

statements and responses in the ECUP Questionnaire. The selected debris exposure rate 

measurements would be identifiable to specific geographic island locations. The exposure times 

should be commensurate with the time it would have taken to clean up the specified volume of 

debris as documented in H&N (1973). 

K-4. Conclusions and Recommendations 

The results of the validation confirm that island-average exposure rates derived from the 

1972 AEC aerial survey are consistently higher than the means of the debris exposure rates 

calculated at the representative exposure distance of 10 ft. The island-average exposure rates are 

a factor 4 to 30 higher than the mean debris exposure rates at the 10-foot reference distance and 

assuming a disk source with a radius of 5 ft. Similar results are obtained for a disk source with a 

radius of 10 ft at the representative distance of 10 ft. 

The primary recommendation is that for personnel who were involved in direct cleanup 

activities of contaminated debris on the five islands from which contaminated debris was 

removed, the island-average exposure rate should be used to estimate external doses. This 

recommendation does not apply to personnel who performed activities other than debris cleanup 

on the five islands, e.g., boat transport of contaminated debris. In addition, the recommendation 

does not apply to personnel who handled red debris destined for disposal in the Cactus Crater on 

Runit. 

Finally, in some cases where specific information is provided by a veteran relating to 

working on specified contaminated debris documented in H&N (1973), a single or a combination 

of debris exposure rates can be used to estimate external doses. It would be the dose assessment 

analyst’s decision whether to use this option. 
263 

Attachment I. 

Maps of the Islands where Contaminated Debris was Removed during ECUP 

Figure I-1 through Figure I-17 are maps of the islands of Ruby (Figure I-1), Sally 

(Figure I-2 and Figure I-3), Pearl (Figure I-4 and Figure I-5), Yvonne (Figure I-6 through 

Figure I-10), and Janet (Figure I-11 through Figure I-17). All figures were adapted from 

AEC (1973a). The figures show sequence numbers in red color and exposure rate measurements 

in black block font that correspond to the respective columns of the tables in Attachment II. The 

figures are for use in conjunction with the tables in Attachment II. 
264 

Figure I-1. Measured radiation exposure rates on Ruby 

Sheet 1 
265 

Figure I-2. Measured radiation exposure rates on Sally No. 1 

Sheet 2 
266 

Figure I-3. Measured radiation exposure rates on Sally No 2 

Sheet 3 
267 

Figure I-4. Measured radiation exposure rates on Pearl No. 1 

Sheet 1 
268 

Figure I-5. Measured radiation exposure rates on Pearl No. 2 

Sheet 2 
269 

Figure I-6. Measured radiation exposure rates on Yvonne No. 1 

Sheet 1 
270 

Figure I-7. Measured radiation exposure rates on Yvonne No. 2 

Sheet 2 
271 

Figure I-8. Measured radiation exposure rates on Yvonne No. 3 

Sheet 3
272 

Figure I-9. Measured radiation exposure rates on Yvonne No. 4 

Sheet 4 
273 

Figure I-10. Measured radiation exposure rates on Yvonne No. 5 

Sheet 5 
274 

Figure I-11. Measured radiation exposure rates on Janet No. 1 

Sheet 1 
275 

Figure I-12. Measured radiation exposure rates on Janet No. 2 

Sheet 2 
276 

Figure I-13. Measured radiation exposure rates on Janet No. 3 

Sheet 3 
277 

Figure I-14. Measured radiation exposure rates on Janet No. 4 

Sheet 4
278 

Figure I-15. Measured radiation exposure rates on Janet No. 5 

Sheet 5 

41 
279 

Figure I-16. Measured radiation exposure rates on Janet No. 6 

Sheet 6 
280 

Figure I-17. Measured radiation exposure rates on Janet No. 7 

Sheet 7 
281 

Attachment II. 

Exposure Rate Measurements on Islands where Contaminated Debris was 

Removed during ECUP 

Table II-1 to Table II-5 list the debris radiation exposure rate contact measurements and 

map locations for the islands of Ruby, Sally, Pearl, Yvonne, and Janet. The measurements were 

extracted from maps in AEC (1973a). The map sheet and sequence numbers in the tables in this 

attachment crosslink to the exposure rates shown on the maps in Attachment I. Additional debris 

description information is available in H&N (1973). 
282 

Table II-1. Radiation exposure rates on Ruby 

Map*

Sequence 

Number

(See Map)

Exposure Rate

(μR h−1)

Location Number/

Station Number

Island: Ruby 

Figure I-1 

(Sheet 1 of 

Ruby/Sally 

Map) 

1 6 8 

2 12 9 

3 20 9 

4 20 12 

5 120 1 

6 15 Greenhouse Station 

12 

* Maps and exposure rates from AEC (1973a) and Attachment I.

Table II-2. Radiation exposure rates on Sally 

Map *

Sequence 

Number

(See Map)

Exposure Rate

(μR h−1)

Location Number/

Station Number

Island: Sally 

Figure I-2 

(Sheet 2 of 

Ruby/Sally 

Map) 

1 200 Slightly north of road 

way

2 8 2 

3 60 3 

4 8 Redwing Stations 

2221.01/02/03 

5 8 

Loading Dock north 

of Redwing Station 

2211 

6 8 12 

7 8 13 

Figure I-3 

(Sheet 3 of 

Ruby/Sally 

Map) 

1 70 Redwing Stations 1 

and 3011 

2 30 5 (Concrete slab) 

3 3,000 6 

* Maps and exposure rates from AEC (1973a) and Attachment I.
283 

Table II-3. Radiation exposure rates on Pearl 

Map*

Sequence 

Number 

(See map)

Exposure Rate

(μR h−1)

Location Number/

Station Number

Island: Pearl 

Figure I-4 

(Sheet 1 of 

Pearl Map) 

1 1,000 3 

2 1,000 slightly south of 

location 3 

3 800 1 (central point on 

map) 

4 5,000 6 

5 80 1 (northernmost point 

on map) 

6 400 slightly NE of 

location 2 

7 2,000 2 

8 250 5 

9 3,000 1 (southernmost point 

on map) 

10 150 East of location 5 

Figure I-5 

(Sheet 2 of 

Pearl Map) 

1 11 8 

2 3 3 

3 7 4 

4 7 Castle Station 120.22 

5 7 7 

* Maps and exposure rates from AEC (1973a) and Attachment I.

Table II-4. Radiation exposure rates on Yvonne 

Map* Sequence Number (See Map) Exposure Rate (μR h−1)

Island: Yvonne

Figure I-6 

(Sheet 1 of 

Yvonne Map) 

1 2 

2 150 

3 200 

4 15 

5 200 

6 70 

7 400 

8 240 

Figure I-7 

(Sheet 2 of 

Yvonne Map) 

1 40 

2 50 

3 200 

4 80 
284 

Map* Sequence Number (See Map) Exposure Rate (μR h−1)

Island: Yvonne

5 60 

6 40 

7 40 

8 30 

9 60 

10 15 

11 25 

12 30 

13 170 

14 30 

15 60 

16 3 

17 100 

18 12 

19 80 

20 120 

21 1,400 

22 12 

23 3,000 

24 15 

25 10 

Figure I-8 

(Sheet 3 of 

Yvonne Map) 

1 3,000 

2 8 

3 30 

4 70 

5 15 

6 120 

7 110 

8 3 

9 70 

10 2 

11 3 

12 1 

13 2 

14 5 

15 2 

16 8 

17 10 

18 400 

19 1,000 
285 

Map* Sequence Number (See Map) Exposure Rate (μR h−1)

Island: Yvonne

Figure I-9 

(Sheet 4 of 

Yvonne Map) 

1 200 

2 80 

3 200 

4 1,000 

5 1 

6 3 

7 40 

8 130 

9 60,000 

10 250 

11 1,000 

12 15 

13 80 

14 5 

15 120 

16 220 

17 230 

18 300 

Figure I-10 

(Sheet 5 of 

Yvonne Map) 

1 2 

2 2 

3 2 

4 1 

5 3 

6 2 

7 2 

8 2 

9 3 

10 3 

11 2 

12 3 

13 2 

14 3 

15 1 

* Maps and exposure rates from AEC (1973a) and Attachment I.
286 

Table II-5. Radiation exposure rates on Janet 

Map* Sequence Number (See Map) Exposure Rate (μR h−1)

Island: Janet

Figure I-11 

(Sheet 1 of 

Janet Map)

1 4 

2 4 

3 4 

4 4 

5 1,500 

6 20 

7 20 

8 150 

9 190 

10 90 

11 750 

12 2,000 

13 8,500 

14 900 

15 2,300 

16 8,000 

17 15 

18 15

19 15 

20 20 

21 70 

22 130 

23 5 

24 12 

25 5 

26 60 

27 500 

28 50 

29 20 

Figure I-12

(Sheet 2 of 

Janet Map) 

1 120 

2 10 

3 25 

4 10 

5 6 

6 5 

7 10 

8 60 

9 30 

10 15 

11 13 
287 

Map* Sequence Number (See Map) Exposure Rate (μR h−1)

Island: Janet

12 10 

13 10

14 8 

15 5 

16 50 

17 15 

18 20 

19 20 

20 25 

21 15 

22 8 

23 3 

24 3 

25 5 

26 3 

27 8 

28 6 

Figure I-13 

(Sheet 3 of 

Janet Map) 

1 10 

2 6 

3 20 

4 18 

5 22 

6 17 

7 10 

8 10 

9 25 

10 45 

11 10 

12 5 

13 10 

14 14 

15 14 

16 12

17 8 

18 12 

19 13 

20 4 

21 12 

22 8 

Figure I-14 

(Sheet 4 of 

Janet Map) 

1 400 

2 60 

3 90 
288 

Map* Sequence Number (See Map) Exposure Rate (μR h−1)

Island: Janet

4 85 

5 80

Figure I-15 

(Sheet 5 of 

Janet Map) 

1 20 

2 20 

3 60 

4 40 

5 50 

6 150 

7 45 

8 30 

9 200 

10 30 

11 50 

12 20 

13 25 

14 10 

15 15 

16 15 

17 45 

18 45 

19 35 

20 25 

21 35 

22 30 

23 30 

24 40 

25 12 

26 18 

27 16 

28 18 

29 9 

30 12 

31 15

32 10 

33 13 

34 16 

35 13 

36 10 

37 15 

38 10 

39 15 

40 15 
289 

Map* Sequence Number (See Map) Exposure Rate (μR h−1)

Island: Janet

41 16 

42 8

43 10 

44 9 

45 8 

46 7 

47 16 

48 4 

Figure I-16 

(Sheet 6 of 

Janet Map) 

1 600 

2 80 

3 150 

4 120 

5 100 

6 50 

7 40 

8 50 

9 70 

10 80 

11 10 

12 85 

13 45 

14 40 

15 3 

16 40 

17 30 

18 30 

19 15 

Figure I-17 

(Sheet 7 of 

Janet Map) 

1 7,000 

2 700 

3 600 

4 70 

5 50 

6 15

7 20 

8 40 

9 15 

* Maps and exposure rates from AEC (1973a) and Attachment I.
290 

Attachment III. 

Estimated Sizes and Exposure Rates for Contaminated Debris Piles 

The estimated average size of contaminated debris piles on each of the islands from 

which contaminated debris was removed are shown in Table III-1. An explanation of the 

derivation of these values is given in Section K-2.2 and Section K-2.3. 

The calculated exposure rates at the representative distance of 10 ft from the average 

piles for each island, estimated using the equivalent disk radii shown in Table III-1, are 

compared with the island-average exposure rate in Table III- 2. The calculation of the mean 

exposure rates is described in Section K-2.3.

Table III-1. Estimated average sizes of contaminated debris piles 

Island 

Contaminated 

Debris 

Removed 

(yd3)

* 

Number of 

Contaminated 

Debris 

Locations†

Average 

Pile 

Volume 

(yd3) 

Length of 

Idealized 

Cube 

Side (ft)‡

Facing 

Area of 

Cube 

(ft2) 

Equivalent 

Disk 

Radius 

(ft)§

Janet (Enjebi) 530 103 5.1 5.2 26.8 2.9 

Yvonne (Runit) 4,120 52 79.2 12.9 166 7.3 

Pearl (Lujor) 255 10 25.5 8.8 78.0 5.0 

Ruby (Eleleron) 250 4 62.5 11.9 142 6.7 

Sally (Aomon) 728 5 146 15.8 249 8.9 

*

 From DNA (1981), Figure 5-34. 

†

 Locations with contaminated debris are those where the measured contact exposure rate is greater than or equal to 

15 μR h−1 as reported in AEC (1973a). 

‡

 This is the length of one side of a cube with a volume equal to the volume of the average pile. 

§

 Radius of a disk with an area equal to the facing area of the assumed cube geometry. 

Table III- 2. Comparison of calculated debris average and island-average exposure rates 

Island Mean Exposure Rate at 10-ft Distance 

(μR h−1)

* 

Island-Average Exposure Rate 

(μR h−1)

†

Janet (Enjebi) 0.6 40 

Yvonne (Runit) 2.3 33 

Pearl (Lujor) 7.1 70 

Ruby (Eleleron) 1.4 14 

Sally (Aomon) 3.5 7 

*

 Geometric mean of the exposure rates calculated using a disk source model with a radius as shown in 

Table III-1. See also Section K-2.3. 

†

 From the 1972 aerial survey, estimated at 1 meter from the ground (AEC, 1973a).
291 

Appendix L. 

Development of Beta-Gamma Dose Ratios for Skin Dose Assessments for 

Participants in the Enewetak Cleanup Project 

L-1. Introduction 

This appendix describes the development, applicability, and use of beta-gamma dose 

ratios for skin dose assessments for ECUP participants. 

L-1.1. Background 

Beta-gamma dose ratios are used to estimate beta skin doses from direct non-contact 

radiation when gamma doses are available. Estimates of ratios of beta and gamma doses at 

Enewetak Atoll based on measurements made in 1976 at Enewetak Atoll are available (Crase et 

al., 1982). The contributions of beta and low-energy gamma radiations to the total external doses 

from these presumably free-in-air measurements were determined for a height of 100 cm. From 

these measurements, minimum, median, and maximum “Crase ratios” of 0.19, 0.41, and 1.44, 

respectively, were calculated. The median value of these Crase ratios was recommended as an 

interim beta-gamma dose ratio in ECUP assessments for all skin sites in the original (2018) 

version of this technical report. Because beta-gamma dose ratios vary according to the distance 

of the skin site from the source, additional beta-gamma dose ratios are necessary to better 

estimate beta skin doses for sites at various heights. 

L-1.2. Purpose and Objectives 

The purpose of this appendix is to provide information and analyses to support and 

update the skin dose assessment methodology for ECUP participants. This purpose is 

accomplished via the two primary objectives described below: 

 Describe a method used to independently derive a beta-gamma dose ratio for comparison 

with the interim beta-gamma dose ratio previously recommended for ECUP skin dose 

assessments 

 Describe the development and results of additional beta-gamma dose ratios based on the 

interim ECUP beta-gamma dose ratio, for a range of heights above the ground. 

L-2. Methodology 

The methodologies for accomplishing the two primary objectives are discussed in the 

following subsections. Results of the described methodologies are contained in Section L-3. 

L-2.1. Interim Beta-gamma Dose Ratio 

An interim ECUP beta-gamma dose ratio was estimated using the measurements made in 

1976 on the islands of Enjebi (site Janet) and Bokombako (site Belle) (Crase et al., 1982), 

hereafter referred to as “Crase ratios.” The relevant measurements were made with LiF 
292 

thermoluminescent dosimeters (TLDs) placed on crossbars mounted 100 cm above the ground on 

wooden stakes. The relative contributions of beta and low-energy gamma radiations to the total 

measured external doses from these presumably free-in-air measurements were determined and 

documented (Crase et al., 1982). Using the measured relative contributions14, Crase ratios were 

estimated for the measurement height of 100 cm above the ground. The minimum and maximum 

derived Crase ratios are 0.19 and 1.44, with a median value of 0.41. The median Crase ratio was 

recommended as an interim beta-gamma dose ratio for use in ECUP assessments for all skin sites 

in the original version of this technical report. 

Several features of the measurements underlying the Crase ratios presented uncertainties 

and possible issues with regard to using them as beta-gamma dose ratios for ECUP. These items 

include the following: 

 Inclusion of low-energy gamma radiation in the Crase ratios 

 Measurements made at only one height above the ground surface 

 Unknown amounts of vegetation possibly affecting the measurements. 

Therefore, an effort was undertaken to derive beta-gamma dose ratios independently for 

comparison with the Crase ratios. To accomplish this, several approaches were explored to 

produce new ratios that could be used for comparison with the Crase ratios. The approach 

described in this appendix involves modification of the existing beta-gamma dose ratios 

developed for the NTPR Program (DTRA, 2017) to produce ratios for comparison. The NTPR 

ratios have previously been calculated for post-detonation times out to 2 y. Because fission 

product beta-gamma dose ratios vary with time after a detonation, the approach involved 

extending the NTPR ratios out to the post-detonation period appropriate for ECUP (20-30 y). In 

addition, the NTPR ratios were calculated for fallout deposition on an impenetrable surface. 

Therefore, the approach also required a method to incorporate weathering of deposited fallout 

(i.e., infiltration of fallout into the soil). 

L-2.1.1 Time-Extension of NTPR Beta-Gamma Dose Ratios 

The NTPR beta-gamma dose ratios are based on dose factors that describe the emission, 

transport, and absorption of radiation for radionuclides in soil. More specifically, they relate the 

concentrations of contaminants in soil to the free-field radiological conditions, at specific heights 

above the soil. Correlations have been observed between beta and gamma dose factors and their 

respective mean particle energies for times out to the 2-y post-detonation time limit of the NTPR 

beta-gamma dose ratios. These correlations are based on the emission rates of beta and gamma 

particles from mixed fission products, together with their respective mean energies, as obtained 

from Finn et al. (1979) over decay times out to 70 y post-detonation. It was observed that the 

gamma dose factors are directly proportional to mean gamma energies, whereas beta dose factors 

are proportional to a simple power-law scaling of mean beta energies over time. The exponent 

used for the power-law scaling of beta dose factors varied from 0.16 to 1.8 for heights from 1 cm 

to 200 cm, respectively. 

 

14 Crase et al. (1982) contains values of 16%, 29%, and 59% for the minimum, median, and maximum measured 

contribution, respectively, of beta or low-energy gamma radiation to the total external exposure rate. Crase ratios 

were derived from these contributions, assuming that they were due entirely to beta radiation. 
293 

Based on the observed correlations of beta and gamma dose factors and their respective 

mean particle energies for times out to 2 y post-detonation, it was assumed that the relationships 

would also exist for times greater than 2 y. Using these proportionalities, the NTPR beta-gamma 

dose factors were extended to various times out to 70 y post-detonation. The calculated timeextended values for times from 1 y to 70 y are shown in Table L-1. The power-law exponent (n), 

that resulted in the best fit for each height was determined and is shown for each height in 

Table L-1. 

Table L-1. Time-extended NTPR beta-gamma dose ratios 

Height h above a plane source (cm)

1 20 40 80 100 120 160 200 

Time (y) n=0.16* n=0.5 n=0.9 n=1.2 n=1.3 n=1.4 n=1.7 n=1.8 

1 176 78 48 32 27 24 18 14 

2 517 240 155 105 92 80 63 50 

3 436 195 120 79 68 59 45 35 

4 334 144 85 54 46 39 29 22 

5 270 113 64 40 33 28 20 16 

6 232 95 53 32 27 23 16 12 

10 180 74 41 25 21 18 13 10 

30 155 66 38 24 20 17 13 10 

70 147 63 36 23 19 16 12 9 

*

 For each height h, the power-law exponent n(h) used to calculate the set of beta-gamma dose ratios is given. 

L-2.1.2 Incorporating the Effects of Weathering 

To compare the Crase ratios derived from TLD measurements with the time-extended 

values developed from the NTPR program, environmental weathering – the infiltration of fallout 

into the ground – must be taken into account in the time-extended values. Weathering modifies 

the profiles of contaminants within the soil by moving them to greater depth where there is 

additional shielding. Assuming that beta-emitters and gamma-emitters move together with no 

vertical fractionation, weathering acts to decrease the beta-gamma dose ratio over time. 

The algorithm developed to model the effects of weathering involved the coupling of a 

weathering factor with a conventional fallout distribution model to estimate the vertical profile of 

radioactive contaminants in the soil as a function of time. Radiation transport methods were then 

used to calculate the aboveground beta dose contribution from this profile. This allowed for the 

calculation of a “weathering reduction factor” that quantifies the time-dependent effects of 

weathering on the beta-gamma dose ratios. 

Key aspects of the development of weathering reduction factors are described below. A 

full description of the development of the weathering reduction factors will be published at a 

later date. 

The weathering factor used here was developed by the U.S. Nuclear Regulatory 

Commission to estimate a weathered gamma dose rate. Specifically, it models the reduction of 

the gamma dose rate above a weathered deposition of mixed fission products compared to a 
294 

similar deposition on an impenetrable surface (i.e., a deposition with no weathering). This factor 

is expressed as the sum of two exponential terms, shown in Equation L-1 (Till and Meyer, 1983). 

() = 0.63 × 

. + 0.37 × .

(L-1)

where 

() = Weathering factor for gamma dose rate (unitless) 

t = Time after deposition (y) 

The vertical distribution of fallout assumed for contaminants in soil was taken from the 

work of Beck and de Planque (1968) and Beck (1980). As expressed in Equation L-2, the 

concentration of radionuclides (volumetric activity density) at time t after detonation is 

exponentially distributed with depth x: 

(,) =  × 

() (L-2)

where 

C(x, t) = Volumetric activity density at depth x and time t (Ci cm−3 or Ci g−1)

C0 = Volumetric activity density at the air-soil interface (Ci cm−3 or Ci g−1) 

α(t) = Depth profile parameter at time t (cm2 g−1) 

x = Depth in soil (g cm−2) 

Starting with the above equations, a lengthy series of equations and assumptions were 

used to describe time-dependent features such as the relationship of areal density of 

contaminants to the volumetric activity density, and to estimate depth profile parameters for beta 

and gamma radiation sources. The Sandia National Laboratory radiation transport code 

CEPXS/ONEDANT (Lorence et al., 1989) was used to calculate beta dose factors for a range of 

soil overlay thicknesses x and various times t after detonation. The results of these calculations 

were used to estimate beta-gamma dose ratio reduction factors for various post-detonation times 

and heights. The calculated weathering reduction factors for post-detonation times from 1 y to 

70 y are shown in Table L-2. 

Weathering reduction factors derived for various post-detonation times and heights were 

then applied to the time-extended beta-gamma dose ratios from Section L-2.1.1. Specifically, the 

time-extended beta-gamma dose ratios in Table L-1 were multiplied by the corresponding 

reduction factors in Table L-2 to produce the time-extended and weathered beta-gamma dose 

ratios shown in Table L-3. 
295 

Table L-2. Weathering reduction factors 

Time (y)

Weathering reduction factors at various heights above the surface (cm)

1 20 40 80 100 120 160 200 

1 0.098 0.131 0.156 0.172 0.175 0.178 0.180 0.180 

2 0.052 0.071 0.084 0.092 0.093 0.094 0.094 0.094 

5 0.042 0.057 0.062 0.074 0.075 0.076 0.076 0.076 

10 0.040 0.055 0.059 0.071 0.072 0.073 0.073 0.073 

30 0.036 0.048 0.053 0.063 0.064 0.065 0.064 0.064 

70 0.030 0.041 0.044 0.053 0.054 0.054 0.054 0.054 

Table L-3. Time-extended and weathered beta-gamma dose ratios 

Time (y) 

Beta-gamma dose ratios at various heights above the surface (cm) 

1 20 40 80 100 120 160 200 

1 16.3 10.6 7.8 5.5 4.9 4.6 3.6 2.7 

2 25.7 17.9 13.5 9.6 8.7 8.0 6.4 4.9 

5 11.3 6.4 4.0 2.9 2.5 2.1 1.5 1.2 

10 7.2 4.0 2.4 1.8 1.5 1.3 0.9 0.7 

30 5.5 3.2 2.0 1.5 1.3 1.1 0.8 0.6 

70 4.4 2.5 1.6 1.2 1.0 0.9 0.6 0.5 

L-2.1.3 Comparison with Crase Beta-gamma Dose Ratios 

To make a valid comparison of the Crase ratios with the 100-cm time-extended and 

weathered ratios described above, an adjustment was first made to the Crase ratios to convert 

them to Crase beta-gamma dose ratios. The adjustment accounts for the use of body selfshielding factors in the formulation of the NTPR ratios, from which the time-extended and 

weathered ratios were calculated. Self-shielding factors of 0.5 (beta) and 0.7 (gamma) are 

incorporated into the NTPR beta-gamma dose ratios. Therefore, the time-extended and 

weathered beta-gamma dose ratios incorporate these factors. Since the Crase ratios are 

presumably based on free-in-air measurements, self-shielding factors must be included in them 

in order to produce beta-gamma dose ratios for comparison. This is done by multiplying the 

Crase ratios by 0.5/0.7 = 0.71. Minimum, median, and maximum Crase beta-gamma dose ratios 

of 0.14, 0.29, and 1.03, respectively, were thus calculated. 

L-2.2. Additional Beta-gamma Dose Ratios 

The Crase beta-gamma dose ratios are based on measurements made at a height of 

100 cm. They can be extrapolated to other heights using ratios of the beta-gamma dose ratios at 

height h to the ratio at 100 cm, as shown in Equation L-3. 

/

(, h) =

⁄(, h)

⁄(, 100)

(L-3)

where 
296 

/

(, h) = Ratio of the beta-gamma dose ratios at time t and height h to the ratio at 

time t and h = 100 cm 

⁄

(, h) = Beta-gamma dose ratio at post-detonation time t and height h (unitless) 

⁄

(, 100) = Beta-gamma dose ratio at post-detonation time t and height 100 cm 

(unitless) 

The rationale for the use of /

(, h) values (“ratios of ratios”) to make height 

adjustments is based on the observation that when these ratios of ratios are plotted as a function 

of time, they tend to reach relatively constant values. This was observed for the NTPR ratios of 

ratios over the time period from about 0.5 y out to 2 y. The flattening of the NTPR ratios of 

ratios towards the end of the NTPR time period suggests that relatively constant values of these 

ratios may exist beyond 2 y. This was confirmed by examining the ratios of ratios for the timeextended and weathered dose ratios. The curves for most heights are relatively flat from about 

2 y to 70 y, as shown in Figure L-1. 

Figure L-1. Values of RRβ/γ(t,h) for the time-extended and weathered beta-gamma 

dose ratios as a function of time 

The values of the 30-y ratios of ratios (RRβ/γ(30,h)) for the time-extended and weathered 

beta-gamma dose ratios (RRβ/γ(30,h)) are shown in Table L-4.

15 The time of 30 y post-detonation 

was selected from the available times as appropriate because it is close to the post-shot time of 

the Crase measurements, which were made in 1976, 18 to 28 y after the period of the Enewetak 

Atoll detonations (1948–1958). 

 

15 The values in Table L-4 may differ slightly from those derived using the Rβ/γ values from Table L-3 due to 

rounding. 

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 10 20 30 40 50 60 70

R

Rβ/γ

(t,h)

Time after detonation (y)

h = 1 cm h = 20 cm

h = 40 cm h = 80 cm

h = 120 cm h = 160 cm

h = 200 cm
297 

Table L-4. Values of RRβ/γ(30,h) for the time-extended and weathered 

beta-gamma dose ratios 

Time after 

Detonation

Distance h from Source Plane (cm)

1 20 40 80 100 120 160 200

30 y 4.27 2.46 1.55 1.17 1.0 0.864 0.619 0.483 

The RRβ/γ(30,h) values in Table L-4 were then used with the minimum, median, and 

maximum beta-gamma dose ratios estimated from the Crase measurements to calculate betagamma dose ratios at seven heights from 1 cm to 200 cm using Equation L-4. 

⁄ 

(h) = ⁄  × ⁄(30, h) (L-4)

where 

⁄ 

(h) = ECUP beta-gamma dose ratio at height h (unitless) 

⁄  = Beta-gamma dose ratio calculated from Crase et al. (1982) (unitless) 

⁄ 

(30, h) = Ratio of the 30-y time-extended and weathered beta-gamma dose 

ratio at height h to the beta-gamma dose ratio at 100 cm (unitless) 

L-3. Results and Discussion 

The results of the methodologies described above are discussed in the following 

subsections. 

L-3.1. Interim Beta-gamma Dose Ratio 

The minimum, median, and maximum Crase beta-gamma dose ratios of 0.14, 0.29, and 

1.03, respectively (from Section L-2.1.3), were compared to the 30-y 100-cm beta-gamma dose 

ratio of 1.3 from Table L-3. The beta-gamma dose ratio of 1.3 exceeds the maximum Crase betagamma dose ratio by about 25 percent and exceeds the median by a factor of about 4.5. Given 

these comparisons, the Crase beta-gamma dose ratios are found to be in reasonable agreement 

with the time-extended and weathered beta-gamma dose ratio of 1.3. This conclusion includes 

acknowledgement of several differences between the two sets of beta-gamma dose ratios. Those 

differences include the omission of Co-60 from the time-extended and weathered beta-gamma 

dose ratios, and the inclusion of low-energy gamma radiation in the Crase ratios. Preliminary 

results from other approaches indicate that inclusion of Co-60 would yield beta-gamma dose 

ratios within the range of the Crase beta-gamma dose ratios. 

L-3.2. Additional Beta-gamma Dose ratios for ECUP 

The 30-y values of the ratios of ratios (RRβ/γ(30,h)) from Table L-4 were applied to the 

minimum, median and maximum Crase beta-gamma dose ratios to estimate height-dependent 

beta-gamma dose ratios for ECUP. The resulting beta-gamma dose ratios are shown in Table L-5

and the medians are plotted in Figure L-2. The beta-gamma dose ratios calculated based on the 

median 100-cm Crase beta-gamma dose ratio are proposed for use in radiation dose assessments 

for skin for ECUP participants. 
298 

Table L-5. Beta-gamma dose ratios calculated for ECUP skin dose assessments 

ECUP Beta-gamma Dose Ratios at Various Heights (cm)*

1 20 40 80 100 120 160 200 

Minimum 0.58 0.33 0.21 0.16 0.14 0.12 0.084 0.066 

Median 1.2 0.72 0.45 0.34 0.29 0.25 0.18 0.14 

Maximum 4.4 2.5 1.6 1.2 1.0 0.89 0.64 0.50 

*

 Values are rounded to 2 significant digits. 

Figure L-2. Calculated ECUP beta-gamma dose ratios 

The median ECUP beta-gamma dose ratios in Table L-5 can be used as reasonable 

estimates of beta-gamma dose ratios above contaminated soil for ECUP skin dose assessments. 

In using these values, it is assumed that on average, the conditions of exposure of ECUP 

participants in 1977–1980 were similar to the conditions under which the Crase TLD 

measurements were made. This is a necessary assumption because local conditions on Enewetak 

Atoll at the time of the Crase measurements (e.g., extent of vegetation, degree of soil moisture, 

nearby structures) would have affected the TLD measurements from which the beta contributions 

were determined. 

The median beta-gamma dose ratios from Table L-5 are plotted as a function of height in 

Figure L-2 together with a fitted logarithmic function. The fitted equation is shown in the figure 

and is reproduced in Equation L-5. 

y = -0.212  ln(x) + 1.2693

R2 = 0.9907

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

0 50 100 150 200

E

C

U

P

b

eta-g

a

m

m

a

d

o

s

e ratio (Rβ/γECUP

)

Height (cm)

Median ECUP

Log. (Median ECUP)
299 

⁄ 

(h) = −0.212 × (h) + 1.2693 (L-5)

where 

⁄ 

(h) = Calculated ECUP beta-gamma dose ratio at height h (unitless) 

h = Height above the surface (cm) 

If the height above ground of a required skin site dose is not one of the heights given in 

Table L-5, Equation L-5 can be used to estimate the beta-gamma dose ratio for the specific 

height, i.e., for any skin site on a veteran. Alternatively, interpolation techniques can be used to 

estimate ratios between the values listed in Table L-5 . To aid in estimating ratios for a specific 

skin site, reference heights from the ground for 11 anatomical locations and three configurations 

(standing, sitting in a chair, sitting on the ground) are provided in Table L-6. 

Table L-6 Reference heights of body locations from surface 

Anatomical Location 

Reference Heights for Three Positions*,† (cm) 

Standing Sitting 

(chair/bench) 

Sitting 

(ground/deck) 

Foot and ankle 1.0 1.0 5.1 

Shin 20.3 20.3 15.2 

Knee 40.6 40.6 15.2 

Mid-thigh 71.1 53.1 15.2 

Waist 99.1 56.4 14.0 

Forearms 99.1 56.4 20.3 

Stomach 119 76.7 34.3 

Mid-chest 140 97.0 54.6 

Neck 150 107 64.8 

Face and head/eyes 160 117 74.9 

Top of head 173 130 87.6 

*

 Reference heights are for a veteran stature of 173 cm (68 inches) (DTRA, 2017). 

†

 To estimate values for veteran heights other than 173 cm, multiply the appropriate reference height 

(except foot/ankle) by the ratio of veteran height to the reference height. For foot and ankle sites, the 

reference heights are used without modification for all veteran heights. 

L-4. Conclusions 

A beta-gamma dose ratio of 1.3 was estimated for a height of 100 cm at a post-detonation 

time of 30 y by modifying the NTPR beta-gamma dose ratios. The modified beta-gamma dose 

ratio was estimated using the flux and energy emission characteristics of decaying fission 

products over time to extend the NTPR beta-gamma dose ratios out to 70 y post-detonation, and 

incorporating environmental weathering reduction factors. The estimated value of 1.3 compares 

sufficiently well with the range of beta-gamma dose ratios of 0.14–1.03 calculated from the 

Crase TLD measurements. Preliminary results from other approaches produce beta-gamma dose 
300 

ratios in the range of Crase beta-gamma dose ratios. Therefore, it can be concluded that both 

methods and results for estimating beta-gamma dose ratios are credible. 

Additional beta-gamma dose ratios at various heights other than 100 cm were calculated 

using the time-extended and weathered 30-y beta-gamma dose ratio estimates to modify the 

minimum, median, and maximum 100-cm Crase et al. beta-gamma dose ratios. In the absence of 

specific measurements, the calculated beta-gamma dose ratios based on the median Crase betagamma dose ratios, shown in Table L-5, are recommended in skin dose assessments for ECUP 

participants and for all islands at Enewetak Atoll. A function was fitted to a plot of these ratios 

that can be used to estimate the beta-gamma dose ratio for the distance above the surface of any 

ECUP veteran skin site. Reference heights for specific anatomical skin sites are also provided, 

including a method for modifying these heights when necessary. 
301 

Appendix M. 

Assessment of Internal Doses from Local Food Consumption 

by Participants in the Enewetak Cleanup Project 

M-1. Introduction 

The most likely local foods that ECUP participants may have consumed during their 

participation are identified and a standardized dose assessment methodology is described in this 

appendix. A dose calculation tool based on the methodology is developed to estimate internal 

radiation doses from the potential consumption of local foods by ECUP participants. This 

appendix provides the details of the dose estimation from the consumption of local foods 

presented in Section 7. 

M-1.1. Background 

Given the possible contamination from previous nuclear testing in foods obtained from 

Enewetak Atoll, it is expected that personnel who cleaned up the islands during ECUP would 

refrain from eating local foods. However, anecdotes from ECUP veterans indicate that 

participants did consume both local marine and terrestrial foods. As the veterans recounted, 

cleanup personnel caught, prepared, and ate lobsters, fish, coconut crabs, or clams as recreational 

activities while off-duty (Cherry, 2018b; Fitzgerald, 2017; Tupin, 2018). Other local foods 

commonly eaten by the Marshallese people that might have been occasionally consumed by 

ECUP personnel are coconut meat and coconut milk. 

M-1.2. Purpose and Objectives 

The purpose of this appendix is to document the technical basis for estimating radiation 

doses from the potential consumption of local foods by ECUP participants. To achieve this goal, 

the following objectives are pursued: 

 Collect data and information to develop appropriate assumptions and select high-sided 

parameter values for calculating doses from the possible consumption of local food 

 Develop calculation tools based on a standardized local food dose assessment methodology 

to ensure timely and accurate calculations when handling veteran claims. 

M-2. Methodology 

This section presents the data, methods, assumptions, and parameter values used to 

estimate doses to internal organs and committed effective doses to the whole body that result 

from the potential consumption of local foods by ECUP personnel. 

M-2.1. Dose Calculation Method 

The internal radiation dose accrued from the ingestion of potentially contaminated foods 

is quantified as the committed equivalent dose per serving for organ exposures, or committed 

effective dose per serving for whole body exposures. In this appendix, the term “dose per 
302 

serving” is also used to describe these internal organ and effective doses from the ingestion of 

local foods. The organ dose per serving from eating local foods is calculated using Equation M-1 

as follows: 

 =   ×

,

/

× ,





(M-1)

where 

Dfood = Dose per serving from consumption of local food (rem per serving) 

qfood = Food consumption rate, i.e., amount consumed per serving (g, wet weight 

per serving) 

Cfood,i = Average activity concentration of radionuclide i in edible part of the food 

(pCi g−1, dry weight) 

Rw/d = Wet-to-dry weight ratio [(g, wet weight) (g, dry weight)−1] 

DCing,i = Ingestion dose coefficient for radionuclide i for the organ of interest 

(rem pCi−1) 

n = Total number of relevant radionuclides 

 

The average activity concentrations, Cfood,i, over the entire atoll for key radionuclides in 

the edible part of each local food are reported in Section M-2.2. The values for the wet-to-dry 

weight ratios, Rw/d, and the food consumption rates, qfood, along with the rationales, are presented 

and discussed in Section M-2.3. The ingestion dose coefficients, DCing,i, which convert activity 

intake to 50-year committed equivalent dose for 25 organs and 50-year committed effective dose 

to the whole body, are shown in Table C-3. The calculated results for organ and effective doses 

per serving and the corresponding upper-bound doses are presented in Attachment I of this 

appendix. 

M-2.2. Activity Concentrations in Edible Parts of Local Foods 

Local marine and terrestrial foods were collected during the radiological surveys 

conducted at Enewetak Atoll from October 1972 to February 1973 (DNA, 1981; AEC, 1973a). 

The averages of measured concentrations of radionuclides in the edible parts of local foods from 

samples collected over the entire atoll are calculated from data reported in AEC (1973a) and are 

listed in Table M-1. Activity concentration data from AEC (1973a) are presented in Section 4.7. 

Because of their relatively long half-lives, activity concentrations in foods, and potential 

contribution to internal doses, Co-60, Sr-90, Cs-137, and Pu-239/240 are considered the key 

radionuclides for the ingestion of local food. In addition, Am-241 was identified in fish so this 

additional radionuclide is included in the dose assessment for fish consumption (AEC, 1973a). 

Two data analysis methods are used in AEC (1973a) to develop high-sided radionuclide 

average concentrations in the edible parts of the foods, thus overestimating doses from 

consumption of local foods. First, the arithmetic means of measured concentrations in food tissue 

are used as the values to estimate internal doses. This assumption overstates the doses because, 

for example, the distributions of the measured concentrations of Sr-90, Cs-137, Co-60, and 

Pu-239/240 in the marine samples are quite skewed, and the medians are about 3 to 20 times 

lower than the arithmetic means (AEC, 1973a). Second, when calculating average 

concentrations, non-detectable concentrations of relevant radionuclides in the samples were set 
303 

to the respective detection limits. The average concentrations calculated using this data treatment 

produce high-sided dose contributions from some of these radionuclides because actual 

concentrations in the non-detect samples are frequently far below the analytical detection limits. 

This was verified, for example, in the case of Am-241, where the concentrations detected in a 

few fish samples using wet-chemistry analysis were found to be significantly lower than the 

detection limits previously established by gamma spectroscopy (AEC, 1973a). 

Furthermore, Am-241 was not detected in 372 out of 410 marine samples by gamma 

counting (AEC, 1973a). This indicates that Am-241 was undetectable in the majority of fish 

samples and the concentration shown in Table M-1 is an overestimate. As a result of setting 

concentrations of Am-241 to the detection limit for such a large number of non-detect samples, 

the average concentration of this radionuclide in fish is about two orders of magnitude higher 

than when concentrations in non-detects were set to 0 pCi g−1. Specifically, the reported average 

concentration is 0.00277 pCi g−1 with non-detect samples set to 0 pCi g−1, and 0.114 pCi g−1, 

shown in Table M-1, when the non-detects were set to the detection limit (AEC, 1973a). 

However, for the average concentrations in fish of the other four radionuclides listed in 

Table M-1, when non-detects are set to 0 pCi g−1 rather than the detection limit, the average 

concentrations are not significantly affected. 

Table M-1. Average activity concentration of key radionuclides in the edible part of 

local foods at Enewetak Atoll 

Food Average Activity Concentration (pCi g−1

, dry weight)*,†,‡

Co-60 Sr-90 Cs-137 Pu-239/240 Am-241 

Fish 2.00 0.075 0.39 0.248 0.114 

Lobster 0.29 0.020 0.018§0.0060 – 

Coconut Meat 0.12 0.80 7.5 0.030 – 

Coconut Milk 0.053 0.058 4.71 0.0030 – 

Coconut Crab 0.629 0.759 3.93 0.0016 – 

Clams (Giant)** 9.33 0.091 – 0.24 – 

*

 Averages are based on data reported in AEC (1973a), except as noted otherwise. For fish, average concentrations are 

reported in Table 158 except for Sr-90, the average concentration is for muscle only and is taken from Table 159; for 

lobster, average concentrations are reported in Table 41, except Cs-137 (see note below); for coconut meat, see 

Table 164; for coconut milk, see Table 165; for coconut crab, see Table 169; for clams, concentrations are from 

Table 39. (AEC, 1973a) 

†

 The concentrations are in pCi g−1 dry weight except they are pCi g−1 wet weight for coconut milk. 

‡

 The averages are calculated with non-detect sample concentrations set equal to the detection limits. 

§

 Concentrations of Cs-137 in spiny lobster muscle were not reported in AEC (1973a). The value shown is the highest 

value in samples collected in 1978–1979 reported in Table 6 of Ebert and Ford (1986). 

** Cs-137 and Am-241 were not detected in the vast majority of the analyzed clam samples, so these radionuclides are 

not included for clams.

“–” indicates not detected or not considered as a key radionuclide (AEC, 1973a).
304 

M-2.3. Parameter Values and Assumptions 

The wet-to-dry ratio is the ratio of the fresh tissue weight to the dried tissue weight 

obtained following a drying process described in AEC (1973a). The food consumption rate, qfood, 

is expressed as edible tissue (wet) weight consumed per serving. Values of the wet-to-dry ratio 

and the suggested consumption rates of local foods are presented in Table M-2. The rationale for 

each suggested consumption rate for ECUP participants is discussed in the following subsections. 

Table M-2. Parameter values for estimating ingestion doses from eating local foods 

Edible Part of Local Food Wet-to-Dry Ratio* Consumption Rate 

(g per serving)

Fish muscle 3.5 300 

Lobster muscle 4.3 500 

Coconut Meat 2 400 

Coconut Milk 20 300 

Coconut Crab muscle 4.1 500 

Clams (Giant) 6.4 500 

*

 Values are taken from AEC (1973a), except that the ratio for muscle of the common shore crab is used for 

coconut crab muscle (Bjerregaard and Depledge, 2002). 

M-2.3.1 Fish Consumption Rate 

A serving of fish can be based on the body weight of the person eating the fish. For 

example, 8 ounces (227 g) of uncooked fish muscle is one serving for a 150-pound person in the 

United States. To adjust the serving size for a person with a different weight, 1 ounce (28 g) of 

fish is added or subtracted for every 20 pounds of body weight over or under 150 pounds, 

respectively (MDH, 2020). Using the average weight of military personnel in the United States 

of about 180 pounds (USMC.net, 2018), a consumption rate of approximately 10 ounces 

(rounded up to 300 g) of fish per serving for ECUP participants is a reasonable assumption. 

M-2.3.2 Lobster Consumption Rate 

The tail is assumed to be the portion of the lobster potentially consumed by ECUP 

participants. The weights of the tails of a sub-set of lobsters sampled in 1978–1979 were 

approximately 135–195 g (Ebert and Ford, 1986). The average of the values in this range is 

approximately 160 g, which corresponds to a lobster with a total weight of 550 g according to 

Ebert and Ford (1986). Assuming that an ECUP participant ate three 160 g tails in one meal, and 

further assuming that the weight of the tail is entirely from muscle, this would result in 

approximately 500 g of muscle consumed in a serving. This serving size is considered a highsided estimate. 

M-2.3.3 Coconut Meat Consumption Rate 

The consumption of the meat from an entire coconut, which is about 400 g wet weight on 

average, is considered a high-sided assumption. This is because the consumption of the meat of 

an entire coconut all at once is considered unlikely. Nevertheless, the 400 g serving size from an 
305 

entire coconut is used in this analysis to estimate internal doses for ECUP veterans. However, 

this should be considered an infrequent occurrence. 

M-2.3.4 Coconut Milk Consumption Rate 

A drinking coconut is fully grown but still green. It contains about 250–350 ml of liquid 

(AEC, 1973a). It is reasonable that an ECUP veteran may have consumed all the liquid from a 

green coconut. Therefore, a serving size of all the milk from one coconut, 300 ml or 

approximately 300 g, is used as a conservative consumption rate for ECUP veterans. 

M-2.3.5 Coconut Crab Consumption Rate 

The edible part of a coconut crab is the fresh muscle of the legs. Due to the lack of data 

on the weights of the legs, a serving of the muscle of coconut crab legs is assumed to be 500 g, 

which is based on the estimated serving size for lobster (Section M-2.3.2). Because the number 

of coconut crabs at Enewetak Atoll was limited and this food is considered a delicacy (AEC, 

1973a), a 500 g serving size of coconut crab muscle is considered a high-sided estimate for 

ECUP personnel. 

M-2.3.6 Clams (Giant) Consumption Rate 

A typical amount of clams consumed as a main dish for a meal is about 1 pound of 

unshelled clams per person, which should yield around 125 g (4 oz) of actual meat per person 

(Cook’s Info, 2018). This estimate is for clams of common sizes served on, for example, dinner 

tables. Thus a consumption rate of 500 g per serving is assumed as a high-sided estimate for 

clams consumed by ECUP participants. 

M-2.4. Uncertainty 

As discussed in Section 7 and following the standard procedures and methods used in the 

NTPR Program radiation dose assessments, an uncertainty factor of 10 is applied to the internal 

dose calculated using Equation M-1 to obtain an upper-bound dose (DTRA, 2017, SM UA01). 

This uncertainty factor accounts for all uncertainties applicable to high sided parameter values 

used in internal dose calculations for the consumption of local foods. 

M-3. Results and Discussion 

The average radionuclide activity concentrations in six local foods potentially consumed 

by ECUP participants are given in Table M-1 and the consumption rates are given in Table M-2. 

Using these parameter values, the doses per serving of the six local foods are estimated using 

Equation M-1. The two highest estimated organ doses per serving along with the corresponding 

organs and the whole-body committed effective dose per serving are shown in Table M-3 for 

each local food potentially consumed by ECUP participants. Calculated doses for all organs 

resulting from consumption of the six local foods are tabulated in Table I-1 of this appendix. 
306 

Table M-3. Estimated doses per serving from the consumption of local foods 

Local 

Food

Estimated Dose (rem per serving)

Highest Organ Dose (Organ) 

(Radionuclide Contributing 

Largest Dose) 

Second Highest 

Organ Dose 

(Organ) 

Committed Effective 

Dose (Radionuclide 

Contributing Largest 

Dose) 

Fish 9.8 × 10−4

(Bone surface) (Pu-239/240) 

1.6 × 10−4

(Liver) 

3.1 × 10−5

(Pu-239/240) 

Lobster 2.5 × 10−5

(Bone surface) (Pu-239/240) 

5.0 × 10−6

(Liver) 

1.4 × 10−6

(Pu-239/240) 

Coconut 

Meat 

5.0 × 10−4

(Bone surface) (Sr-90) 

1.9 × 10−4

(Red marrow) 

9.5 × 10−5

(Cs-137) 

Coconut 

Milk 

1.3 × 10−4

(Bone surface) (Cs-137) 

9.1 × 10−5

(LLI wall) 

7.1 × 10−5

(Cs-137) 

Coconut 

Crab 

1.7 × 10−4

(Bone surface) (Sr-90) 

8.6 × 10−5

(Red marrow) 

3.4 × 10−5

(Cs-137) 

Clams 

(Giant) 

5.8 × 10−4

(Bone surface) (Pu-239/240) 

1.3 × 10−4

(Liver) 

2.7 × 10−5

(Pu-239/240) 

Based on the parameter values described above, the bone surface receives the highest 

dose from each of the selected local foods potentially consumed by ECUP participants. The 

estimated doses to the bone surface range from 2.5 × 10−5rem per serving of lobster to 

9.8 × 10−4rem per serving of fish. The much lower dose from consuming lobster than in fish is 

mainly due to the difference in concentrations of the highest contributor to dose in lobster and 

fish, Pu-239/240, being a factor of about 40. The estimated whole-body committed effective 

doses range from 1.4 × 10−6 to 9.5 × 10−5rem per serving, where coconut meat consumption 

results in the highest effective dose. This is mainly due to the relatively high concentrations of 

Sr-90 and Cs-137 found in coconut meat. Except for coconut meat and lobster, whole-body 

effective doses for the other foods are similar in magnitude. 

Furthermore, fish consumption produces the highest dose to the bone surface because the 

average Pu-239/240 concentration in fish was consistently higher than that in other foods as can 

be seen in Table M-1. In addition, Am-241 was detected only in fish, and the average 

concentration shown in Table M-1 was calculated by setting all non-detects equal to the 

detection limit. However, additional laboratory analyses showed that for non-detects, 

concentrations in fish samples were much lower than the detection limits. The dose to the bone 

surface from fish consumption drops to 6.7 × 10−4rem per serving, or about 30 percent lower, if 

the average concentration of 0.00277 pCi g−1 is used for Am-241, which is obtained by assigning 

a value of 0 pCi g−1 for all non-detects.

The ranges of upper-bound organ and upper-bound committed effective doses per serving 

from the consumption of the selected local foods are presented in Table M-4. Upper-bound doses 

for all organs included in the ICRP Database of Dose Coefficients (ICRP, 2011) are tabulated in 

Table I-2 of this appendix. The upper-bound doses are obtained by applying an uncertainty factor 

of 10 to the doses shown in Table M-3 and Table I-1. 
307 

Table M-4. Upper-bound doses per serving from the consumption of local foods 

Local Food 

Upper-Bound Dose (rem per serving) 

Organ Dose Range Committed Effective Dose 

Fish 3.8 × 10−5– 9.8 × 10−33.1 × 10−4

Lobster 2.9 × 10−6– 2.5 × 10−41.4 × 10−5

Coconut Meat 6.2 × 10−4– 5.0 × 10−39.5 × 10−4

Coconut Milk 5.8 × 10−4– 1.3 × 10−37.1 × 10−4

Coconut Crab 2.0 × 10−4– 1.7 × 10−33.4 × 10−4

Clams (Giant) 4.5 × 10−5– 5.8 × 10−32.7 × 10−4

Based on the upper-bound doses summarized above, the total internal dose accrued by an 

ECUP participant who consumed local foods can be estimated. Using fish as an example, a 

veteran who was deployed for six months may have consumed one serving of locally caught fish 

per month for a total of six servings. Given the limited opportunity to acquire and eat locally 

caught fish, this consumption rate is considered high-sided (Tupin, 2018). Using these 

assumptions, the estimated total upper-bound doses to internal organs range from less than 0.001 

to 0.06 rem, the lowest dose being to the breast and the highest to bone surface. The estimated 

upper-bound committed effective dose is 0.002 rem. If the concentrations of Am-241 in nondetect fish samples are set to 0 pCi g−1

, the upper-bound organ doses would be about 35 percent 

lower overall, ranging from less than 0.001 rem to 0.04 rem. 

M-4. Conclusions 

The results show that the internal dose per serving to bone surface resulting from the 

consumption of local fish is higher than the dose from the consumption of any other local foods 

investigated. This results primarily from the relatively high concentration of Pu-239/240 in fish, 

which produces the highest contribution to internal dose. 

For an ECUP participant that consumed local foods, the internal doses for some organs 

(e.g., bone surface and liver), may be the dominant overall dose components as compared to 

external doses or other internal doses due to inhalation and incidental ingestion of soil and dust 

discussed in Sections 6 and 7. However, estimated total internal doses from the ingestion of local 

foods depend on the assumed quantity consumed and how frequently local foods were 

consumed. The default values and assumptions presented in Section M-2 were carefully 

estimated and selected. They are default values that should be used in dose assessments for 

veterans who cannot recall the type, quantity, or frequency of the foods consumed. However, to 

perform individualized dose assessments for ECUP veterans, specific information on the 

consumption of local foods can be collected by means of a questionnaire. The veteran’s input 

should then be used instead of the default parameter values to estimate doses from the 

consumption of local foods. 
308 

Attachment I. 

Internal Organ and Effective Doses from Local Food Consumption 

Committed internal organ doses per serving from the consumption of five local foods 

were calculated using the methods and assumptions described in Section M-2. These doses are 

shown in Table I-1. Doses were estimated for all organs included in ICRP Database of Dose 

Coefficients (ICRP, 2011). Table I-2 presents corresponding upper-bound organ doses per 

serving obtained by applying an uncertainty factor of 10 to the doses shown in Table I-1. 
309 

Table I-1. Total internal organ doses from potential local food consumption 

by ECUP participants 

Organ/ 

Tissue 

Ingestion Doses (rem per serving) 

Fish Lobster Coconut 

Meat 

Coconut 

Milk 

Coconut 

Crab Clam 

Adrenals 4.9810−64.6010−77.8710−57.3410−52.5710−57.6710−6

Bladder Wall 5.0610−64.8010−77.9210−57.3510−52.6110−57.9610−6

Bone Surface 9.8310−42.4910−55.0010−41.2610−41.7110−45.7610−4

Brain 4.0310−6 3.0810−7 6.7510−5 6.2910−5 2.1910−5 4.7310−6

Breast 3.8410−62.8810−76.2010−55.7710−52.0110−54.4610−6

Esophagus 4.3510−63.5310−77.3110−56.8110−52.3710−55.5310−6

Stomach Wall 4.9710−64.5710−77.3310−56.8210−52.4110−57.7510−6

SI Wall*6.4110−66.8310−77.9210−57.3510−52.6410−51.2410−5

ULI Wall*9.7710−61.0510−68.2510−57.4010−52.8710−51.9810−5

LLI Wall*1.8210−51.9810−61.1010−49.1210−54.1110−53.7310−5

Colon 1.3310−51.4310−69.2910−57.9910−53.3510−52.6910−5

Kidneys 7.4010−64.8910−77.3610−56.8210−52.4010−58.7010−6

Liver 1.5810−45.0210−61.1010−47.3810−52.5710−51.2810−4

Muscle 4.3510−63.7010−76.7610−56.2910−52.2010−56.0710−6

Ovaries 1.9310−59.3010−78.1010−57.3810−52.6310−51.9110−5

Pancreas 5.0410−64.7210−77.8710−57.3410−52.5810−57.9410−6

Red Marrow 4.9110−52.9010−61.8810−48.0810−58.5510−53.7010−5

ET Airways* 4.3510−6 3.5310−7 7.3110−5 6.8110−5 2.3710−5 5.5310−6

Lungs 4.4110−63.6510−77.3110−56.8110−52.3810−55.8010−6

Skin 3.8410−62.8810−76.2010−55.7710−52.0110−54.4610−6

Spleen 4.6010−64.0310−77.3110−56.8210−52.3910−56.6010−6

Testes 1.7410−56.0410−76.9710−56.3210−52.2110−51.2410−5

Thymus 4.3510−63.5310−77.3110−56.8110−52.3710−55.5310−6

Thyroid 4.3510−63.5310−77.3110−56.8110−52.3710−55.5310−6

Uterus 5.2910−65.2210−77.8810−57.3410−52.5910−59.0110−6

Effective dose 3.1310−51.4010−69.4610−57.0810−53.3810−52.6910−5

*

 Abbreviations used in this table: SI Wall = Small Intestine Wall; ULI Wall = Upper Large Intestine Wall; 

LLI Wall = Lower Large Intestine Wall; ET Airways = Extra-thoracic Airways.
310 

Table I-2. Total upper-bound internal organ doses from potential local food consumption 

by ECUP participants 

Organ/ 

Tissue 

Upper-Bound Ingestion Doses (rem per serving) 

Fish Lobster Coconut 

Meat 

Coconut 

Milk 

Coconut 

Crab Clam 

Adrenals 4.9810−5

4.6010−67.8710−47.3410−42.5710−47.6710−5

Bladder Wall 5.0610−54.8010−67.9210−47.3510−42.6110−47.9610−5

Bone Surface 9.8310−32.4910−45.0010−31.2610−31.7110−35.7610−3

Brain 4.0310−53.0810−66.7510−46.2910−42.1910−44.7310−5

Breast 3.8410−52.8810−66.2010−45.7710−42.0110−44.4610−5

Esophagus 4.3510−53.5310−67.3110−46.8110−42.3710−45.5310−5

Stomach Wall 4.9710−54.5710−67.3310−46.8210−42.4110−47.7510−5

SI Wall*6.4110−56.8310−67.9210−47.3510−42.6410−41.2410−4

ULI Wall*9.7710−51.0510−58.2510−47.4010−42.8710−41.9810−4

LLI Wall*1.8210−41.9810−51.1010−39.1210−44.1110−43.7310−4

Colon 1.3310−41.4310−59.2910−47.9910−43.3510−42.6910−4

Kidneys 7.4010−54.8910−67.3610−46.8210−42.4010−48.7010−5

Liver 1.5810−35.0210−51.1010−37.3810−42.5710−41.2810−3

Muscle 4.3510−53.7010−66.7610−46.2910−42.2010−46.0710−5

Ovaries 1.9310−49.3010−68.1010−47.3810−42.6310−41.9110−4

Pancreas 5.0410−54.7210−67.8710−47.3410−42.5810−47.9410−5

Red Marrow 4.9110−4

2.9010−51.8810−38.0810−48.5510−43.7010−4

ET Airways*

4.3510−53.5310−67.3110−46.8110−42.3710−45.5310−5

Lungs 4.4110−53.6510−67.3110−46.8110−42.3810−45.8010−5

Skin 3.8410−52.8810−66.2010−45.7710−42.0110−44.4610−5

Spleen 4.6010−54.0310−67.3110−46.8210−42.3910−46.6010−5

Testes 1.7410−46.0410−66.9710−46.3210−42.2110−41.2410−4

Thymus 4.3510−53.5310−67.3110−46.8110−42.3710−45.5310−5

Thyroid 4.3510−53.5310−67.3110−46.8110−42.3710−45.5310−5

Uterus 5.2910−55.2210−67.8810−47.3410−42.5910−49.0110−5

Effective dose 3.1310−41.4010−59.4610−47.0810−43.3810−42.6910−4

*

 Abbreviations used in this table: SI Wall = Small Intestine Wall; ULI Wall = Upper Large Intestine Wall; 

LLI Wall = Lower Large Intestine Wall; ET Airways = Extra-thoracic Airways.
311

Abbreviations, Acronyms and Symbols

AAQS ambient air quality standards 

ADC Army Dosimetry Center 

AEC Atomic Energy Commission 

AFRRI Armed Forces Radiobiology Research Institute 

ALARA as low as reasonably achievable 

Am americium 

AMAD Activity Median Aerodynamic Diameter 

APF assigned protection factor

AR Army Regulation 

Ba barium 

Bi bismuth 

Bq becquerel 

CDR Commander 

CaF2:Mn calcium fluoride manganese doped 

CFR Code of Federal Regulations 

CJTG Commander, Joint Task Group 

CI confidence interval 

Ci curie 

cm centimeter 

Co cobalt 

COL Colonel (US Army) 

cpm counts per minute 

Cs cesium 

d day 

DA Department of Army 

DD Directives Division 

DARWG Dose Assessment and Recording Working Group

DLF decontamination laundry facility 

DNA Defense Nuclear Agency 

DOE Department of Energy 

DoD Department of Defense 

DOI Department of Interior, or Date of Issue 

DOR Date of return 

dpm disintegration per minute 

DTRA Defense Threat Reduction Agency 

EAI Enewetak Atoll Instruction 

ECUP Enewetak Cleanup Project 

ED external dose 

EIS Environmental Impact Statement 

EOD Explosive Ordnance Disposal 

ERDA Energy Research and Development Administration 

ERSP Enewetak Radiological Support Project 

Eu europium 

FB film badge conversion factor 
312

FCDNA Field Command, Defense Nuclear Agency 

fCi femtocurie 

FCRR Headquarters, Joint Task Group, Radiation Records 

FIDLER Field Instrument for Detecting Low Energy Radiation 

FRST Field Radiation Support Team 

g gram 

GB gross beta 

GM geometric mean 

Gy gray 

GZ Ground Zero 

H&N Holmes and Narver, Inc.

HPS Health Physics Society 

h hour 

ID internal dose 

IMP in situ measurement of plutonium 

ICRP International Commission on Radiological Protection 

JTG Joint Task Group 

K potassium 

keV kiloelectron volt 

kg kilogram 

km kilometer 

kt kiloton 

L or l liter 

LARC lighter, amphibious, resupply craft 

LBDA Lexington-Blue Grass Depot Activity 

LCM landing craft, mechanized 

LCDR Lieutenant Commander 

LCU landing craft, utility 

LTC Lieutenant Colonel (U.S. Army) 

m meter

mCi millicurie 

MDA minimum detectable activity 

MDL minimum detectable level 

min minute 

μCi microcurie 

μg microgram 

μR microroentgen 

ML mass loading 

mL milliliter 

μm micrometer 

μrem microrem 

MEDEVAC medical evacuation 

MPC maximum permissible concentration 

mR milliroentgen 

mrem millirem 

MSC Medical Service Corps 
313

MSTS Mission Support and Test Services 

Mt megaton 

N number of years of age 

n nano or number 

NaI sodium iodide 

nCi nanocurie 

NAS National Academy of Sciences 

NAS-NRC National Academy of Sciences-National Research Council 

NCO non-commissioned officer 

NCOIC non-commissioned officer in charge 

NCRP National Council on Radiation Protection and Measurements 

NDC Naval Dosimetry Center 

NIOSH National Institute of Occupational Safety and Health 

NTPR Nuclear Test Personnel Review 

NVO Nevada Operations Office 

OEHL Occupational and Environmental Health Laboratory 

OPLAN operations plan

oz ounce 

pCi picocurie 

PM10 particulate matter 10 micrometer or less in diameter 

PMEL Precision Measurement Equipment Laboratory 

POI population of interest 

PPE personal protective equipment 

Pu plutonium 

R roentgen 

RADSAFE radiation safety 

RCC Radiation Control Committee 

RDA radiation dose assessment 

RECA Radiation Exposure Compensation Act 

rem roentgen equivalent man 

RPO radiation protection officer 

RSAIT radiation safety audit and inspection team 

SAR search and rescue 

Sb antimony 

SCUBA self-contained underwater breathing apparatus 

SI Système International d'Unités (International System of Units)

SITREP situation report 

SM standard method 

SOP standing operating procedures 

SPARE Scenario of Participation and Exposure 

Sr strontium 

Sv sievert 

TLD thermoluminescent dosimeter 

TM technical manual 

TRU transuranic 

TTPI Trust Territory of the Pacific Islands 
314

UA uncertainty analysis 

UB upper-bound 

UDT underwater demolition team 

UF uncertainty factor 

UK United Kingdom 

USA United States Army 

USAF United States Air Force 

USEPA United States Environmental Protection Agency 

USN United States Navy 

USNRC United States Nuclear Regulatory Commission 

USUHS Uniformed Services University of the Health Sciences

USSR Union of Soviet Socialist Republics 

VA United States Department of Veterans Affairs 

WBC water beach cleanup 

WBCT water beach cleanup team 

wk week 

y year 

Y yttrium