Draft

ADVISORY BOARD ON

RADIATION AND WORKER HEALTH

National Institute for Occupational Safety and Health

WHITE PAPER: SUPPLEMENTAL INFORMATION AND 

RESPONSE TO FINDING 434.1-C.1.1 FOR A WESTINGHOUSE 

NUCLEAR FUELS DIVISION DOSE RECONSTRUCTION

Contract No. 211-2014-58081 

SCA-TR-DR2017-WP001, Revision 0 

Prepared by

U.H. Behling, PhD, MPH

SC&A, Inc.

2200 Wilson Boulevard, Suite 300 

Arlington, Virginia, 22201 

May 2017 

DISCLAIMER

This is a working document provided by the Centers for Disease Control and Prevention (CDC) technical 

support contractor, SC&A for use in discussions with the National Institute for Occupational Safety and 

Health (NIOSH) and the Advisory Board on Radiation and Worker Health (ABRWH), including its 

Working Groups or Subcommittees. Documents produced by SC&A, such as memorandum, white paper, 

draft or working documents are not final NIOSH or ABRWH products or positions, unless specifically 

marked as such. This document prepared by SC&A represents its preliminary evaluation on technical 

issues.

NOTICE: This report has been reviewed to identify and redact any information that is protected by the 

Privacy Act 5 U.S.C. § 552a and has been cleared for distribution.
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SC&A, INC.: Technical Support for the Advisory Board on Radiation and Worker 

Health Review of NIOSH Dose Reconstruction Program

DOCUMENT TITLE: 

White Paper: Supplemental Information and Response to Finding

434.1-C.1.1 for a Westinghouse Nuclear Fuels Division Dose 

Reconstruction

DOCUMENT NUMBER/

DESCRIPTION:

SCA-TR-DR2017-WP001

REVISION NO.: 0 (Draft)

SUPERSEDES: N/A

EFFECTIVE DATE: May 25, 2017

TASK MANAGER: Rose Gogliotti [signature on file]

PROJECT MANAGER: John Stiver, MS, CHP [signature on file]

DOCUMENT 

REVIEWER(S):

Rose Gogliotti [signature on file]

John Stiver, MS, CHP [signature on file]

Record of Revisions

Revision 

Number

Effective 

Date Description of Revision

0 (Draft) 5/25/2017 Initial issue
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TABLE OF CONTENTS

Abbreviations and Acronyms ......................................................................................................... 4

1.0 Statement of Purpose .......................................................................................................... 5

2.0 Relevant Background Information and Timeline of Events ............................................... 5

3.0 Evaluation of Data Used by NIOSH to Derive External Doses During the WNFD 

Residual Period ................................................................................................................... 6

3.1 Guidance in the WNFD Template .......................................................................... 6

3.2 Evaluation of Spreadsheet Data Provided to SC&A on March 31, 2017 ............... 7

3.1.1 Figure 1: External Exposure Doses to Natural Thorium ............................. 7

3.1.2 Figure 2: Isotopic Components Representing Natural Thorium ................. 9

4.0 Remaining Concerns and Uncertainties ............................................................................ 12

4.1 Undocumented Surface Activity ........................................................................... 12

4.2 Inappropriate Value for Resuspension Factor....................................................... 12

4.3 Inconsistency of Resuspension-Factor-Derived Air Concentration ..................... 13

4.4 Undocumented Air Concentration for Internal Dose Assessment ........................ 13

4.5 Inconsistent Assignment of Isotopic Activity Fractions ....................................... 13

5.0 Recommendations for the Resolution of Finding 434.1-C.1.1 ......................................... 14

6.0 References ......................................................................................................................... 15

Appendix A: Reproduction of the WNFD Dose Methodology Template ................................ 16

Appendix B: Table 1 from Regulatory Guide 1.86 .................................................................. 22
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ABBREVIATIONS AND ACRONYMS

ABRWH Advisory Board on Radiation and Worker Health 

AEC U.S. Atomic Energy Commission

AWE Atomic Weapons Employer 

BZ breathing zone 

DCF dose conversion factor

DOE U.S. Department of Energy 

dpm disintegrations per minute

DR dose reconstruction 

EE energy employee

EEOICPA Energy Employees Occupational Illness Compensation Program Act 

EPA U.S. Environmental Protection Agency 

EU enriched uranium 

FEMP Fernald Environmental Management Project 

ICRP International Commission on Radiological Protection

keV kiloelectron volt 

LMFBR Liquid Metal Fast Breeder Reactor

MDA minimum detectable activity

MeV mega-electron volt 

mrem millirem

NERVA Nuclear Engine for Rocket Vehicle Application

NIOSH National Institute for Occupational Safety and Health

NU natural uranium 

ORAUT Oak Ridge Associated Universities Team

OTIB ORAUT technical information bulletin

Pu plutonium 

Ra radium 

SCDRR Subcommittee for Dose Reconstruction Reviews 

SRDB Site Research Database

Th thorium 

WNFD Westinghouse Nuclear Fuels Division 
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1.0 STATEMENT OF PURPOSE

This report provides SC&A’s analysis of information submitted by the National Institute for 

Occupational Safety and Health (NIOSH) on March 31, 2017, pertaining to Finding 434.1-C.1.1 

for a dose reconstruction (DR) review of an energy employee (EE) who worked at the 

Westinghouse Nuclear Fuels Division (WNFD). 

2.0 RELEVANT BACKGROUND INFORMATION AND TIMELINE 

OF EVENTS

• In February 2013, NIOSH completed its DR for the WNFD EE.

• In February 2014, SC&A issued its draft review of the WNFD DR along with five findings 

(SC&A 2014). 

Finding 434.1-C.1 stated that NIOSH employed an “unsupported method for determining 

photon dose during the residual period.” More specifically, this finding cited the absence 

of information needed for SC&A to duplicate doses derived by NIOSH. Duplication and

verification of values used by NIOSH for reconstruction of assigned radiation doses is 

essential to SC&A’s DR review.

• On September 13, 2015, and November 16, 2015, findings for the WNFD DR were 

discussed with the Subcommittee for Dose Reconstruction Reviews (SCDRR). In its

September 13, 2015, response to SC&A’s Finding 434.1-C.1.1, NIOSH stated: “NIOSH 

agrees that though these calculations were described in the DR report, they were not

directly included in the claim file or detailed in the DR report” (emphasis added) 

(BRS 2015). 

• On January 30, 2017, Finding 434.1-C.1.1 was again discussed during another SCDRR 

teleconference. For resolution of the finding, NIOSH agreed to provide the necessary 

information that would allow SC&A to verify and validate external doses during the 

residual period. 

• On March 31, 2017, NIOSH provided SC&A with the following documents: 

– The WNFD Template, titled Dose Reconstruction Methodology for Westinghouse 

Nuclear Fuels Division, Cheswick, PA, issued February 8, 2013. This document is 

reproduced herein as Appendix A.

– The WNFD spreadsheet developed by NIOSH for deriving external deep and shallow 

doses during the WNFD residual period. 

• On April 13, 2017, the SCDRR conducted its most recent teleconference to discuss select 

DRs and their findings, which included Finding 434.1-C.1.1. Due to time constraints, 

SC&A had not been able to provide the SCDRR with a written analysis of the recently

furnished data prior to the teleconference. As a result, the SCDRR asked SC&A to 
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supplement its oral presentation of these two documents in a formal report. Presented 

below are summary evaluations that provide the following information: 

– An evaluation of forwarded data used by NIOSH for the derivation of external doses 

during the WNFD residual period 

– Remaining concerns and uncertainties pertaining to Finding 434.l1-C.1.1 

– Recommendations for the resolution of Finding 434.1-C.1.1 

3.0 EVALUATION OF DATA USED BY NIOSH TO DERIVE EXTERNAL

DOSES DURING THE WNFD RESIDUAL PERIOD 

3.1 GUIDANCE IN THE WNFD TEMPLATE 

For the derivation of external dose during the residual period, the WNFD Template (see 

Appendix A) provides the following guidance that is limited to the statements quoted below: 

Residual External Dose 

Though a monitoring program existed at WNFD during the residual period, 

continuing operations that are not covered under the EEOICPA also occurred. 

Therefore, external dosimetry should only be used to limit residual exposures. 

Residual exposures are calculated based on the contamination levels calculated 

below and applying the dose conversion factors from EPA Federal Guidance 

Report 12 for contaminated surfaces and submersion. These doses are provided in 

the table below. [emphasis added]

Year 

OTIB-0070 

Adjustment Factor Photon (rem) Electron (rem)

1973 1.000 0.032 0.171

1974 0.783 0.025 0.134

1975 0.613 0.020 0.105

1976 0.480 0.016 0.082

1977 0.376 0.012 0.064

1978 0.294 0.010 0.050

1979 0.231 0.007 0.040

In behalf of the “derived” photon dose of 0.032 rem/yr and electron dose of 0.171 rem/yr given in 

the table, NIOSH’s explanation for these numbers is confined to (1) unspecified “contamination 

levels” and (2) the application of the U.S. Environmental Protection Agency’s (EPA’s_ dose 

conversion factors (DCFs) for contaminated surfaces and contaminated air submersion cited in 

Federal Guidance Report 12 (EPA 1993). 
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SC&A’s inability to reproduce and validate the aforementioned photon and electron doses that 

prompted Finding 434.1-C.1.1 must, therefore, be viewed in context with the limited information 

provided in the WFND Template.

3.2 EVALUATION OF SPREADSHEET DATA PROVIDED TO SC&A ON MARCH 31,

2017 

Reproduced as Figures 1 and 2 are two spreadsheets that in combination provide numerical data 

that trace the conversion of the specified surface contamination level of 2.83×106

 dpm/m2 in 1973 

to a deep dose rate of 0.032 rem/yr and a shallow dose rate of 0.171 rem/yr for natural thorium 

(Nat-Th). (Note: Data are also provided for three other potential source terms: plutonium (Pu) mix 

12% 10 year, recycled natural uranium [NU], and recycled 2% enriched uranium [EU].) 

3.1.1 Figure 1: External Exposure Doses to Natural Thorium 

Shown below the deep dose in Figure 1 is the derivation of the shallow dose of 0.171 rem/yr, 

which parallels that of the deep dose with the exception of DCF values taken from EPA’s Federal 

Guidance Report 12 that correspond to skin as the target tissue for the shallow dose. For simplicity 

and convenience to the reader, salient elements in Columns 1 through 10 of Figure 1 are 

sequentially identified in numbered list items 1 through 10 below the figure. 
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Figure 1: Spreadsheet Data Obtained from NIOSH Pertaining to External Exposure Doses to Natural Thorium 

Surface Activity (dpm/m2) 2.83E+06

Column #1 Column #2 Column #3 Column #4 Column #5 Column #6 Column #7 Column #8 Column #9 Column #10

Radionuclide Surface Activity (dpm/m2)

Resuspension 

(m-1)

Air Concentration 

(dpm/m3)

Effective Contaminated 

DCF (rem/dpm hr m-2)

Effective Submersion DCF 

(rem/dpm hr m-3)

Effective Contaminated 

Dose Rate (rem / hr)

Effective Submersion Dose 

Rate (rem / hr) Workhours / Year

Effective WB Dose 

(rem/yr)

Nat-Th 2.83E+06 1.00E-06 2.83 5.73E-12 2.99E-10 1.62E-05 8.47E-10 2000 0.032

Pu Mix 12% 10 yr 2.83E+06 1.00E-06 2.83 4.98E-14 1.45E-12 1.41E-07 4.10E-12 2000 0.000

Recycled NU 2.83E+06 1.00E-06 2.83 1.16E-13 5.22E-12 3.30E-07 1.48E-11 2000 0.001

Recycled 2% EU 2.83E+06 1.00E-06 2.83 7.00E-14 3.08E-12 1.98E-07 8.72E-12 2000 0.000

Radionuclide Surface Activity (dpm/m2)

Resuspension 

(m-1)

Air Concentration 

(dpm/m3)

Skin Contaminated DCF 

(rem/dpm hr m-2)

Skin Submersion DCF 

(rem/dpm hr m-3)

Skin Contaminated Dose 

Rate (rem / hr)

Skin Submersion Dose 

Rate (rem / hr) Workhours / Year

Skin Dose 

(rem/yr)

Nat-Th 2.83E+06 1.00E-06 2.83 3.03E-11 5.00E-10 8.57E-05 1.42E-09 2000 0.171

Pu Mix 12% 10 yr 2.83E+06 1.00E-06 2.83 1.65E-13 2.33E-12 4.67E-07 6.59E-12 2000 0.001

Recycled NU 2.83E+06 1.00E-06 2.83 2.77E-11 1.72E-10 7.84E-05 4.87E-10 2000 0.157

Recycled 2% EU 2.83E+06 1.00E-06 2.83 1.16E-11 7.68E-11 3.29E-05 2.18E-10 2000 0.066

Photon (rem) Electron (rem)

1973 1.000 0.032 0.171

1974 0.783 0.025 0.134

1975 0.613 0.020 0.105

1976 0.480 0.016 0.082

1977 0.376 0.012 0.064

1978 0.294 0.010 0.050

1979 0.231 0.007 0.040

Deep Dose

Shallow Dose

Year OTIB-070

95th Pecentile
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1) NIOSH identified four different potential source terms that could result in external 

exposure. (Natural thorium, however, resulted in the highest deep dose and shallow dose 

among the four potential source terms and is highlighted in yellow.) 

2) Identifies the assigned surface contamination level of 2.83×106 dpm/m2 for year 1973.

3) A resuspension value of 1×10-6 m-1 was selected to derive the air contamination level.

4) By means of the assumed resuspension value of 1×10-6 m-1 times the 2.83×106 dpm/m2, 

NIOSH calculated the air concentration of 2.83 dpm/m3

. 

5) Corresponds to the combined effective DCF for the three isotopes representing natural 

thorium, as derived in Figure 2, from surface contamination. 

6) Corresponds to the combined effective DCF for the three isotopes representing natural 

thorium, as derived in Figure 2, from Federal Guidance Report 12 for submersion 

exposure. 

7) Represents the effective external dose rate that results from contaminated surface. For 

example, the derived “effective contaminated” dose rate of 1.62E-05 rem/hr is the 

product of columns 2 and 5: (2.83×106

 dpm/m2) × (5.73×10-12) = 1.62E-05 rem/hr. 

8) Represents the effective external dose rate that results from submersion in contaminated 

air.

9) Work-hours per year during which external exposure is assumed. 

10) The effective annual dose of 0.032 rem/yr is the combined effective external dose from 

surface contamination and submersion in contaminated air.

3.1.2 Figure 2: Isotopic Components Representing Natural Thorium

Figure 2 segregates the source term described in Figure 1 as natural thorium into its isotopic 

components of thorium-232 (Th-232), Th-228, and radium-228 (Ra-228) and provides the 

contribution of effective contaminated dose rate and effective submersion dose rate for each 

radionuclide. Incorporated into isotopic-specific dose rates, however, are the isotopic activity 

fractions (shown in the upper left-hand side of Figure 2 for natural thorium) of 0.084 for Th-228, 

0.0145 for Th-232, and 0.9015 for Ra-228. 

However, the assigned isotopic activity fractions of 8.4% for Th-228, 1.45% for Th-232, and 

90.15% for Ra-228 appear to represent activity fractions for thorium tailings. For unprocessed 

natural thorium, Th-232, Th-228, and Ra-228 must reasonably be assumed to exist in secular 

equilibrium where each of the three radionuclides contribute the identical activity fraction of 

0.333. 

Therefore, NIOSH’s inappropriate assignment of activity fractions for natural thorium for 

deriving external dose assessment conflicts with the correct natural thorium activity fractions 
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of 0.333 used by NIOSH for deriving internal dose, as shown in the “Internal Dose” section of 

the WNFD Template (see Appendix A). 
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Figure 2: Spreadsheet Data Obtained from NIOSH Pertaining to the Isotopic Components Representing Natural Thorium

Natural Thorium

Radionuclide Activity Faction

Th228 0.084

Th232 0.0145

Ra228 0.9015

Radionuclide Activity Faction

Effective Contaminated 

DCF (rem/dpm hr m-2)

Effective Submersion DCF 

(rem/dpm hr m-3)

Effective Contaminated 

Dose Rate (rem / hr)

Effective Submersion 

Dose Rate (rem / hr)

DU Contaminated Dose 

Rate (rem / hr)

DU Submersion Dose 

Rate (rem / hr)

Th228 8.40E-02 8.43E-12 4.82E-10 7.08E-13 4.05E-11

Th232 1.45E-02 3.31E-15 5.23E-14 4.79E-17 7.59E-16

Ra228 9.02E-01 5.57E-12 2.87E-10 5.02E-12 2.59E-10

Radionuclide Activity Faction

Skin Contaminated DCF 

(rem/dpm hr m-2)

Skin Submersion DCF 

(rem/dpm hr m-3)

Skin Contaminated Dose 

Rate (rem / hr)

Skin Submersion Dose 

Rate (rem / hr)

DU Skin Contaminated 

Dose Rate (rem / hr)

DU Skin Submersion 

Dose Rate (rem / hr)

Th228 8.40E-02 5.44E-11 8.83E-10 4.57E-12 7.42E-11

Th232 1.45E-02 4.12E-14 2.06E-13 5.97E-16 2.99E-15

Ra228 9.02E-01 2.85E-11 4.73E-10 2.57E-11 4.26E-10

Activity Faction

3.03E-11 5.00E-10

5.73E-12 2.99E-10
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4.0 REMAINING CONCERNS AND UNCERTAINTIES

While data in Figures 1 and 2 allowed SC&A to duplicate NIOSH’s derived external deep dose 

of 0.032 rem/yr and shallow dose of 0.171 rem/yr of the residual period, it does not imply their 

validation. Imbedded in the derivation of external doses are three unexplained or undocumented 

assumptions and two inconsistencies that require further clarification, as explained below. 

4.1 UNDOCUMENTED SURFACE ACTIVITY

Figures 1 and 2 identify the starting surface contamination of 2.83×106 dpm/m2, which 

quantitatively directly affects the derivation of external doses. However, no information is 

provided by NIOSH that explains and validates the origin and derivation of the 2.83×106

 dpm/m2

contamination level.

4.2 INAPPROPRIATE VALUE FOR RESUSPENSION FACTOR

For the derivation of external submersion doses, NIOSH assigned the resuspension factor of 

1.00E-06 m-1. NIOSH’s assigned resuspension value of 1.00E-06 m-1 is not only inappropriate 

but also produces a resulting air concentration that is incompatible with air concentrations 

assumed by NIOSH for the derivation of internal/inhalation uptake values, as explained below.

In the “Residual External Dose” section of the WNFD Template (see Appendix A), NIOSH 

states the following: 

Though a monitoring program existed at WNFD during the residual period, 

continuing operations that are not covered under the EEOICPA also occurred. 

[emphasis added] 

This statement implies that (1) there was no decontamination at the WNFD facility after 

completion of Atomic Weapons Employer (AWE) activities in 1972, and (2) some radiological 

activities continued that were not covered under the Energy Employees Occupational Illness 

Compensation Program Act (EEOICPA). 

A resuspension factor as low as 1.00E-06 m-1 is generally only used to validate a thorough and 

documented decontamination effort for a facility that complies with standards specified in the 

U.S. Atomic Energy Commission’s (AEC’s) Regulatory Guide 1.86, Termination of Operating 

Licenses for Nuclear Reactors (AEC 1974), and meets the standard for unrestricted use given in 

Table 1 of the regulatory guide. Acceptable surface contamination levels for natural thorium as 

well as other nuclides given in Regulatory Guide 1.86, Table 1 are reproduced in Appendix B.

SC&A concludes that conditions during the residual period at WNFD do not meet these 

criteria. NIOSH’s use of a 1.00E-06 m-1 resuspension factor for deriving external 

submersion doses is, therefore, inappropriate.
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4.3 INCONSISTENCY OF RESUSPENSION-FACTOR-DERIVED AIR 

CONCENTRATION

The resuspension factor of 1.00E-06 m-1 and its derived submersion air concentration of 

2.83 dpm/m3 of air (i.e., (2.83×106 dpm/m2) × (1×10-6) = 2.83 dpm/m3) is incompatible with the 

corresponding value of 100 dpm/m3 air concentration used by NIOSH for estimating the daily 

inhalation of 965.121 dpm (see the “Internal Dose” section of Appendix A).

Based on 1971 and 1972 air sampling data (given in Site Research Database [SRDB] Ref. IDs 

65275, 65285, 65298, 65299, 65387, 65388, 65391, 65393, 65394, 65396, 65398, 65399, 65401, 

65402, and 65404), NIOSH derived inhalation and ingestion intakes during the residual period at 

the 95th percentiles for three separate job categories (see the “Internal Dose” section of the 

WNFD Template in Appendix A). For the highest exposed group, the derived 95th percentile 

inhalation intake for operators/general laborers corresponds to 965.121 dpm per day during year 

1973. (Note: The 15 SRDB Ref. IDs identified by NIOSH are not referenced in the template. The 

template does not contain a reference list.)

Incorporated in the inhalation intake of 965.121 dpm/day is the assumed breathing rate of 1.2 m3

of air per hour and an 8-hour workday. 

The inhalation of 965.121 dpm/day, therefore, assumes an air concentration of 100 dpm 

alpha activity per cubic meter of air at the beginning of the WNFD residual period of 1973. 

In summary, the concurrent exposure to two air concentrations that differ by a factor of ~35 must 

clearly be regarded as incompatible, inasmuch as a person cannot be exposed to an air 

submersion dose defined by 2.83 dpm/m3 of air while at the same time inhaling air containing 

100 dpm/m3. 

4.4 UNDOCUMENTED AIR CONCENTRATION FOR INTERNAL DOSE 

ASSESSMENT

With regard to NIOSH’s assumption of an air concentration of 100 dpm/m3 for the assignment of 

inhalation intakes, it must also be noted that no explanation is given for its derivation. A 

reasonable assumption is that this value reflects air sampling data in the 15 SRDBs cited in the 

“Internal Dose” section of the WNFD Template (see Appendix A). 

4.5 INCONSISTENT ASSIGNMENT OF ISOTOPIC ACTIVITY FRACTIONS

The activity fractions assigned to natural thorium in the derivation of external doses correspond 

to values that do not represent secular equilibrium but more likely represent thorium tailings.

However, for the assessment of internal doses from inhalation and ingestion of natural thorium, 

NIOSH assigned activity fractions that represent secular equilibrium among decay-chain 

members.

Because internal and external exposures to natural thorium are likely concurrent, activity 

fractions assumed for deriving external and internal dose must, therefore, be the same. 
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5.0 RECOMMENDATIONS FOR THE RESOLUTION OF 

FINDING 434.1-C.1.1 

Whenever a dose reconstruction is based on a facility-specific template that has not been 

previously evaluated, SC&A’s charter is to include the template in its review of the DR. 

On behalf of Finding 434.1-C.1.1, SC&A recommends the following changes for resolution: 

1) Provide information/data that validate the surface contamination of 2.83×106

 dpm/m2 used 

to derive external dose.

2) For the derivation of external doses, revise activity fractions for natural thorium that 

represent a state of secular equilibrium, as was assumed by NIOSH in the derivation of 

internal exposures. 

3) For external submersion dose, replace the resuspension factor of 1.00E-06 m-1 with a 

resuspension factor that realistically reflects an AWE facility that had not been 

decontaminated and decommissioned but actively continued operations that were not 

covered under EEOICPA. 

A review of Figure 3-1, Table 3-1, and Figure 3-2 in Revision 01 to ORAUT-OTIB-0070 

(NIOSH 2012) suggest more realistic resuspension factors in the range of 5E-05 m-1 to 

1E-03 m-1. 

Justification for a more realistic resuspension factor is also prompted by the need to 

establish parity between the air concentration assumed for external submersion dose and 

the air concentration assumed for internal/inhalation exposure. Thus, if NIOSH had

selected the resuspension factor of 3.5E-05 m-1, the resultant air concentration of 

99.0 dpm/m3 (i.e., 99.0 dpm/m3 = (3.83×106 dpm/m2) × 3.5 E-05 m-1) used to derive 

external air submersion dose would perfectly match NIOSH’s assumed air concentration of 

100 dpm/m3 for assessing inhalation dose. 

4) Provide information/data that validate the air concentration of 100 dpm/m3 and, therefore, 

the inhalation of 965.121 dpm/day. 
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6.0 REFERENCES

AEC 1974. Termination of Operating Licenses for Nuclear Reactors, Regulatory Guide 1.86, 

U.S. Atomic Energy Commission. June 1974. 

BRS 2015. Subcommittee for Dose Reconstruction Reviews, Board Review System, Set 14-18 

Other DCAS Cases, WNFD 434.1-C.1.1. NIOSH finding response added September 13, 2015. 

EPA 1993. External Exposure to Radionuclides in Air, Water, and Soil, Federal Guidance 

Report No. 12, EPA-402-R-93-081, Office of Radiation and Indoor Air, U.S. Environmental 

Protection Agency, Washington, DC. September 1993.

NIOSH 2012. Dose Reconstruction during Residual Radioactivity Periods at Atomic Weapons 

Employer Facilities, ORAUT-OTIB-0070, Revision 01, National Institute for Occupational 

Safety and Health, Cincinnati, Ohio. March 5, 2012. 

SC&A 2014. Audit of the 18th Set of 12 Dose Reconstruction Cases, Contract No. 200-2009-

28555, SC&A, Inc., Vienna, Virginia. February 3, 2014. 
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APPENDIX A: REPRODUCTION OF THE WNFD DOSE

METHODOLOGY TEMPLATE

Dose Reconstruction Methodology for 

Westinghouse Nuclear Fuels Division, Cheswick, PA

February 8, 2013 

Facility Description

The Westinghouse Nuclear Fuels Division received shipments of nuclear materials from the 

AEC nuclear weapons complex in 1971 and 1972. The Cheswick site received a shipment of 

enriched uranium from the AEC’s Fernald plant in 1971. It also received a shipment of 

plutonium in 1972 from the West Valley facility. This plutonium originated out of Hanford. 

Although the Westinghouse facility in Cheswick, PA, conducted substantial work with 

radioactive materials in other years, this work is not covered under EEOICPA because it was not 

related to nuclear weapons production. This includes the fabrication of nuclear fuels and reactor 

subsystems for naval, space, and civilian applications. Among the projects to which the 

Cheswick facility contributed were the Naval Nuclear Propulsion Program, the Nuclear Engine 

for Rocket Vehicle Application (NERVA) program, and the Liquid Metal Fast Breeder Reactor 

(LMFBR) program.

External Dose 

Photon Dose 

The limit of detection for photons is 0.04 rem for photons, as found in the Technical Information 

Bulletin: A Standard Complex-Wide Methodology for Overestimating External Doses Measured 

with Film Badge Dosimeters, (SRDB RefID 29953). 

The evaluation of cases under the guidance found in the Technical Information Bulletin: 

Interpretation of Dosimetry Data for Assignment of Shallow Dose, (SRDB RefID 19434), will 

require a 0.05 rem limit of detection for photons. 

All photon doses will be assigned as acute dose, in the 30-250 keV photon energy range. 

The monitoring program at the Cheswick facility was comprehensive. Dosimetry records exist 

for the operational period of 1971 to 1972, and are sufficient to perform dose reconstructions, 

with the adjustment for potential neutron dose discussed below. 

Shallow Dose 

The limit of detection for electrons is 0.05 rem for electrons, as found in the Technical 

Information Bulletin: A Standard Complex-Wide Methodology for Overestimating External 

Doses Measured with Film Badge Dosimeters, (SRDB RefID 29953). 
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Shallow doses were included in the dosimetry records. Measured shallow doses will be assigned 

as acute dose, in the <30 keV photon energy range. Blanks in the records will be treated as zeros.

Neutron Dose

As the records indicate that the plutonium originated at the Hanford site, neutron energies were 

assigned as 90% 0.1 – 2 MeV and 10% 2 – 20 MeV neutrons, with ICRP-60 weighting factors of 

1.71 and 0.13, respectively, based on information regarding non-reactor plutonium facilities from 

the Technical Basis Document for the Hanford Site – Occupational External Dose (SRDB RefID 

32074). 

Neutron missed doses are assigned based on a monthly exchange frequency and a claimantfavorable limit of detection of 100 mrem. The limit of detection is based on the known neutron 

detection limits for the relevant era major DOE sites, such as the Savannah River Site, as found 

in the Technical Basis Document for the Savannah River Site (SRDB RefID 20176). 

On-Site Ambient Dose

The dosimetry records include reports for several control dosimeters (SRDB RefID 59671), all of 

which were less than 0.040 rem per badge, below the limit of detection for photons described 

above. When adjusted to reflect a 2,500 hour work-year, per guidance in Occupational On-Site 

Ambient Dose Reconstruction for DOE Sites (SRDB RefID 29986), this results in an annual 

dose of 0.137 rem/year, and should be assigned to all unmonitored workers during operational 

years (1971-1972). The calculated annual dose should be multiplied by the appropriate exposure 

(R)-to-organ DCF documented in OCAS-IG-001 for an isotropic exposure geometry (SRDB 

RefID 29986). An assumption of a normal distribution and 30% standard deviation should be 

applied. 

Medical Dose

No specific information can be found regarding occupational X-ray dose. In the absence of 

specific information, X-ray doses will be assigned in accordance with the Technical Information 

Bulletin: Dose Reconstruction from Occupationally Related Diagnostic X-Ray Procedures 

(SRDB RefID 20220). Assuming a pre-employment, annual, and post-employment X-ray will 

result in one view for each operational year (1971 – 1972). Medical exposure does not apply to 

the residual period. 

Residual External Dose

Though a monitoring program existed at WNFD during the residual period, continuing 

operations that are not covered under the EEOICPA also occurred. Therefore, external dosimetry 

should only be used to limit residual exposures. Residual exposures are calculated based on the 

contamination levels calculated below and applying the dose conversion factors from EPA 

Federal Guidance Report 12 for contaminated surfaces and submersion. These doses are 

provided in the table below. 
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Year OTIB-0070 

Adjustment Factor Photon (rem) Electron (rem)

1973 1.000 0.032 0.171

1974 0.783 0.025 0.134

1975 0.613 0.020 0.105

1976 0.480 0.016 0.082

1977 0.376 0.012 0.064

1978 0.294 0.010 0.050

1979 0.231 0.007 0.040

Internal Dose

Bioassay records are available for most individuals involved with fuel production, involving 

work directly with powder and/or fuel pellets. Records indicate that thorium and plutonium were 

used on the Westinghouse site. The plutonium originated at the Hanford site and arrived at 

Cheswick via the West Valley site. Both nuclides were used to experimentation in the 

laboratories onsite and in the manufacture of mixed oxide fuels, though the thorium found in the 

fuel appears to have been regarded as more of an impurity. Bulk containers of thorium were 

stored in a vault in Building 7 on the site and were used primarily for experimentation. 

Additionally, a shipment of enriched uranium was received at the site from Fernald. Potential 

constituents of recycled uranium must be evaluated and will be performed in accordance with the 

guidance found in the Technical Basis Document for the Fernald Environmental Management 

Project (FEMP) – Occupational Internal Dose, (SRDB RefID 19485), with an assumption of 2% 

enrichment. 

Radionuclide 2% Enriched Recycled Uranium Ratios

U-234:Alpha 1.000

Pu-239:U-234 0.00246

Np-237:U-234 0.00182

Tc-99:U-234 0.379

Th-228:U-234 2.73E-06

Th-232:U-234 2.73E-06

The plutonium mixture will be evaluated using the guidance found in the Technical Basis 

Document for the Hanford Site – Occupational Internal Dose, (SRDB RefID 32522), assuming 

12%, 10-year-old fuel grade plutonium. 
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Radionuclide 12%, 10-year-old Fuel Grade Plutonium Ratios

Pu-238:Alpha 0.117

Pu-239:Alpha 0.593

Pu-241:Alpha 14.201

Am-241:Alpha 0.289

Bioassay and air monitoring records are available. The bioassay records indicate monitoring for 

uranium (natural and enriched) and plutonium. There is no indication of any monitoring for 

thorium. An addendum to the site health physics manual, dated June 1, 1961, states: “The 

properties of uranium and thorium are not sufficiently dissimilar to warrant their separate 

treatment. As far as potential hazard is concerned, both natural uranium and thorium have 

substantially the same specific activity. Therefore, the handling procedures and techniques for 

thorium are the same as those used for uranium” (SRDB RefID 40618). 

Radionuclide Natural Thorium Ratios

Th-228:Alpha 0.333

Th-232:Alpha 0.333

Ac-228:Alpha 0.333

Ra-228:Alpha 0.333

Ra-224:Alpha 0.333

No minimum detectable activities (MDAs) were given in the records. In assigning missed 

internal dose, the reporting value or three times the uncertainty (if the reported value is zero) 

should be assumed to be the MDA. 

Air monitoring results are reported in both units of microCuries/milliliter of air and in dpm/cubic 

meter. In most cases, the dpm/cubic meter results were more legible in the records. These results 

are largely from stationary air samples, collected on a daily or weekly basis, at strategic locations 

around the process areas and the stack. These are considered general area air samples. These 

results are reported as gross total alpha activity. A daily weighted average was established based 

on a breathing rate of 9.6 cubic meters per day (SRDB RefID 22735), for 250 working days per 

year. There are several breathing zone (BZ) air sampling records, listed by the individual. These 

are included within the individual DOE response files and may be used to calculate intakes in the 

unexpected absence of bioassay information. 

Air sampling data (SRDB RefIDs 65275, 65285, 65298, 65299, 65387, 65388, 65391, 65393, 

65394, 65396, 65398, 65399, 65401, 65402, and 65404) were evaluated for the years 1971 and 

1972, the operational period for the site. From these data, inhalation and ingestion intakes at the 

95th percentiles were determined and are provided in the table below and should be assigned as a 

constant distribution. Airborne activities during the residual period were reduced in accordance 

with the Technical Information Bulletin: Dose Reconstruction during Residual Radioactivity 

Periods at Atomic Weapons Employer Facilities (SRDB RefID 108851). 
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Intakes for Unmonitored Operators and General Labor

Year OTIB-0070 

Adjustment Factor

Inhalation 

Intake (dpm/d)

Ingestion Intake 

(dpm/d)

1971 - 1972 1.000 965.121 19.302

1973 1.000 965.121 19.302

1974 0.783 755.690 15.113

1975 0.613 591.619 11.832

1976 0.480 463.258 9.265

1977 0.376 362.885 7.258

1978 0.294 283.746 5.675

1979 0.231 222.943 4.459

Intakes for Unmonitored Supervisors

Year OTIB-0070 

Adjustment Factor

Inhalation 

Intake (dpm/d)

Ingestion Intake 

(dpm/d)

1971 - 1972 1.000 482.561 9.651

1973 1.000 482.561 9.651

1974 0.783 377.845 7.557

1975 0.613 295.810 5.916

1976 0.480 231.629 4.632

1977 0.376 181.443 3.629

1978 0.294 141.873 2.837

1979 0.231 111.472 2.229

Intakes for Unmonitored “Other” Workers

Year OTIB-0070 

Adjustment Factor

Inhalation 

Intake (dpm/d)

Ingestion Intake 

(dpm/d)

1971 - 1972 1.000 48.256 0.965

1973 1.000 48.256 0.965

1974 0.783 37.784 0.756

1975 0.613 29.581 0.592

1976 0.480 23.163 0.463

1977 0.376 18.144 0.363

1978 0.294 14.187 0.284

1979 0.231 11.147 0.223

Intake ratios between the classifications of workers are based on the guidance found in the 

Technical Basis Document: Site Profiles for Atomic Weapons Employers That Worked Uranium 

Metals (SRDB RefID 101251). The intakes for operators and general labor are assumed to be the 

same. Supervisors are assumed to 50% of the operator/ general labor’s exposure and all other 

workers are assumed to be 10% of the supervisor’s.
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During the operational period (1971-1972), partially-monitored workers, those who have 

bioassays for uranium and/or plutonium, should be assigned unmonitored exposure in excess of 

any missed dose calculated from the bioassay data, i.e. subtracting missed intake activity from 

the 95th percentile intake activity described in the tables above, and assigning the remainder as 

either uranium, plutonium, or natural thorium (excluding the ones accounted for via bioassay), 

based on which nuclide provides the most claimant favorable result. 

For completely unmonitored workers, unmonitored exposures should be based on the geometric 

mean intake rate and assigned as either uranium, plutonium, or natural thorium, based on which 

nuclide provides the most claimant favorable result. 

During the residual period (1973-1979), intakes should be based on the tables above. These 

should be assessed as either uranium, plutonium, or natural thorium, based on which nuclide 

provides the most claimant favorable result. These intakes should be limited by the worker’s 

bioassay data if they would result in higher excretions then detected. 
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APPENDIX B: TABLE 1 FROM REGULATORY GUIDE 1.86

Table 1. Acceptable Surface Contamination Levels

NUCLIDE a AVERAGE b c MAXIMUM b d REMOVABLE b e

U-nat, U-235, U-238, and 

associated decay products

5,000 dpm α/100 cm2 15,000 dpm α/100 cm2 1,000 dpm α/100 cm2

Transuranics, Ra-226, Ra-228, 

Th-230, Th-228, PA-231, 

Ac-227, I-125, I-129

100 dpm/100 cm2 300 dpm/100 cm2 20 dpm/100 cm2

Th-nat, Th-232, Sr-90,

Ra-223, Ra-224, U-232, 

I-126, I-131, I-133

1000 dpm/100 cm2 3000 dpm/100 cm2 200 dpm/100 cm2

Beta-gamma emitters (nuclides 

with decay modes other than alpha 

emission or spontaneous fission) 

except Sr-90 and others noted above.

5000 dpm β-γ/100 cm2 15,000 dpm β-γ/100 cm2 1000 dpm β-γ/100 cm2

a Where surface contamination by both alpha- and beta-gamma-emitting nuclides exists, the limits established for alpha- and 

beta-gamma-emitting nuclides should apply independently. b As used in this table, dpm (disintegrations per minute) means the rate of emission by radioactive material as determined by correcting the counts 

per minute observed by an appropriate detector for background, efficiency, and geometric factors associated with the instrumentation. c Measurements of average contaminant should not be averaged over more than 1 square meter. For objects of less surface area, the average 

should be derived for each such object.

d The amount of removable radioactive material per 100 cm2 of surface area should be determined by wiping that area with dry filters or soft 

absorbent paper, applying moderate pressure, and assessing the amount of radioactive material on the wipe with an appropriate instrument of 

known efficiency. When removable contamination on objects of less surface area is determined, the pertinent levels should be reduced 

proportionally and the entire surface should be wiped.

Source: Reproduced from AEC 1974, page 1.86-5.