ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller & Associates I MJW Corporation

Page 1 of 60

Document Title:

Pantex Plant National Security Complex – 

Occupational External Dosimetry

Document Number: ORAUT-TKBS-0013-6 

Revision: 00

Effective Date: 07/27/2006

Type of Document: TBD

Supersedes: None

Subject Experts: Jack J. Fix, Jerome B. Martin, Daniel J. Strom, Richard J. Traub, 

and Paul S. Stansbury

Document Owner

Approval: Matthew H. Smith Signature on File for Approval Date: 05/24/2006

Jack J. Fix, TBD Team Leader

Approval: Signature on File Approval Date: 05/24/2006

John M. Byrne, Task 3 Manager

Concurrence: Keith A. McCartney Signature on File for Concurrence Date: 05/25/2006

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 05/25/2006

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 07/27/2006

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 2 of 61

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

07/27/2006 00 New Technical Basis Document for the Pantex Plant National 

Security Complex – Occupational External Dose. First approved 

issue. Training required: As determined by the Task Manager. 

Initiated by Jerome B. Martin.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 3 of 61

TABLE OF CONTENTS

SECTION TITLE

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

PAGE

7

6.1 Introduction ..............................................................................................................................9

6.1.1 Purpose.......................................................................................................................10

6.1.2 Scope..........................................................................................................................10

6.2 External Dosimetry................................................................................................................. 10

6.3 Basis of Comparison..............................................................................................................11

6.4 External Radiation Exposure Records.................................................................................... 11

6.5 Dose Reconstruction Parameters........................................................................................... 13

6.5.1 Historical Administrative Practices...............................................................................14

6.5.2 Dosimetry Technology................................................................................................. 16

 6.5.2.1 Beta/Photon Dosimeters................................................................................ 16

 6.5.2.2 Neutron Dosimeters....................................................................................... 20

 6.5.2.3 Effects of Changing Early Dosimetry Services............................................... 21

6.5.3 Dosimeter Calibration Procedures...............................................................................22

 6.5.3.1 Beta/Photon Dosimeters................................................................................ 22

 6.5.3.2 Neutron Dosimeters....................................................................................... 23

6.5.4 Workplace Radiation Fields.........................................................................................24

6.5.4.1 Depleted Uranium......................................................................................... 25

6.5.4.2 Photon Radiation .......................................................................................... 25

6.5.4.3 Neutron Radiation......................................................................................... 26

6.5.5 Dosimeter Response to Radiation Fields.....................................................................29

6.5.5.1 Beta/Photon Film Dosimeter Response ........................................................ 29

6.5.5.2 Beta/Photon TLD Dosimeter Response ........................................................ 30

6.5.5.3 Neutron Dosimeter Response....................................................................... 31

6.5.5.4 Neutron-to-Photon Dose Ratios .................................................................... 32

6.5.5.5 Neutron Dose Weighting Factor.................................................................... 35

6.5.5.6 Use of Lead Aprons ...................................................................................... 36

6.6 Analysis of Claims Filed by Pantex Workers .......................................................................... 37

6.6.1 Years with a Claim ......................................................................................................39

6.6.2 Collective Dose by Job Title ........................................................................................39

6.6.3 Analysis of Recorded Doses .......................................................................................40

6.7 Recommendations for Pantex Worker External Dose Reconstruction .................................... 42

6.7.1 Unmonitored External Dose ........................................................................................42

6.7.2 Adjustment for Protective Lead Aprons .......................................................................42

6.7.3 Missed External Dose for Monitored Workers..............................................................43

6.7.4 Photon and Neutron Dose Adjustments.......................................................................46

6.7.5 Skin Dose....................................................................................................................49

6.7.6 Extremity Dose............................................................................................................49

6.7.7 Radiation Dose Fraction..............................................................................................50

6.7.8 Organ Dose.................................................................................................................50
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6.7.9 Claim Analysis Methods ..............................................................................................50

6.7.9.1 Minimizing Assumptions ............................................................................... 50

6.7.9.2 Maximizing Assumptions .............................................................................. 50

6.7.9.3 Best Estimate Assumptions .......................................................................... 50

6.7.9.4 Summary of Correction and Adjustment Factors........................................... 51

6.8 Uncertainty in Photon and Neutron Doses ............................................................................. 51

References ........................................................................................................................................52

Glossary ............................................................................................................................................58
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LIST OF TABLES

TABLE TITLE

6-1 Annual external radiation doses, 1952–2004..........................................................................

PAGE

12

6-2 Dosimeter type, period of use, exchange frequency, MRD, and MDL .................................... 15

6-3 UD-802 dosimeter characteristics .......................................................................................... 18

6-4 UD-812/UD-809 dosimeter characteristics ............................................................................. 19

6-5 IARC study results for U.S. beta/photon dosimeters............................................................... 20

6-6 Ratio of neutron-to-photon cumulative dose........................................................................... 22

6-7 Common sources of laboratory bias in calibration parameters for 

beta/photon dosimeters.......................................................................................................... 23

6-8 Common sources of laboratory bias in calibration parameters for neutron 

dosimeters .............................................................................................................................24

6-9 Beta, photon, and neutron radiation energies and percentages for Pantex 

facilities ..................................................................................................................................30

6-10 Typical workplace beta/gamma dosimeter Hp(10) performance............................................. 31

6-11 Typical workplace neutron dosimeter performance ................................................................ 32

6-12 Neutron quality factor or weighting factor ............................................................................... 36

6-13 Neutron dose energies, percentages and associated ICRP (1990) 

correction factors ................................................................................................................... 36

6-14 Percent reduction in measured photon dose provided by lead aprons ................................... 37

6-15 Cancer sites protected or unprotected by apron..................................................................... 38

6-16 General categories of job titles for Pantex claimants and recorded doses.............................. 40

6-17 Pantex worker photon dose statistics ..................................................................................... 47

6-18 Potential missed dose for Pantex workers.............................................................................. 48

6-19 Summary of recommended correction and adjustment factors............................................... 51
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LIST OF FIGURES

FIGURE TITLE

6-1 Number of workers monitored as a function of time and number of 

workers with zero recorded annual dose................................................................................

PAGE

13

6-2 Comparison of Hp(10) for photons with energy responses for sensitive 

DuPont 502 emulsion in MED two-element film badge and sensitive 

DuPont 555 emulsion in Oak Ridge National Laboratory multielement film 

badge.....................................................................................................................................17

6-3 Six-element TLD holder ......................................................................................................... 18

6-4 Comparison of Hp(10) from normally incident neutrons to energy 

responses of NTA film and neutron albedo dosimeter containing neutron 

TLD chip made of 6

LiF and shielded by cadmium................................................................... 21

6-5 Cumulative plot of annual photon and neutron recorded dose................................................ 22

6-6 MCNP-calculated photon spectra emitted from 238U as excited by 234mPa 

beta in 238U spheres ............................................................................................................... 27

6-7 Bremsstrahlung component of calculated spectrum from 238U spheres on 

linear vertical axis ..................................................................................................................27

6-8 Characteristic X-ray component of calculated spectrum from 238U spheres 

on linear vertical axis.............................................................................................................. 28

6-9 Unmoderated neutron spectra calculated by SOURCES-4A .................................................. 29

6-10 Log-probability plot of grouped neutron-to-photon dose ratios................................................ 33

6-11 Comparison of neutron quality factors.................................................................................... 35

6-12 Body areas covered by lead apron......................................................................................... 37

6-13 Frequency distribution of claims that encompass the respective years................................... 39

6-14 Distribution of annual photon and neutron dose for Pantex claims ......................................... 41

6-15 Dose reconstruction flowchart for cancer site not protected by a lead 

apron......................................................................................................................................44

6-16 Dose reconstruction flowchart for cancer site protected by a lead apron................................ 45

6-17 Lognormal probability plot of Pantex recorded annual photon and neutron 

doses .....................................................................................................................................46
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ACRONYMS AND ABBREVIATIONS

AEC U.S. Atomic Energy Commission

AP anterior-posterior 

Ci curie

cm centimeter

DOE U.S. Department of Energy

DOELAP DOE Laboratory Accreditation Program

DOL U.S. Department of Labor

DU depleted uranium

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

eV electron-volt

HE high explosives

HERS Historical Exposure Records System

HEU highly enriched uranium

Hp(d) personal dose equivalent at depth d (deep dose at 10 mm; shallow at 0.07 mm) 

hr hour

IAAP Iowa Army Ammunition Plant

IARC International Agency for Research on Cancer

ICD International Classification of Diseases

ICRP International Commission on Radiological Protection

ICRU International Commission on Radiation Units and Measurements

IREP Interactive RadioEpidemiological Program

ISO isotropic

keV kiloelectron-volt, 1,000 electron-volts

MCNP Monte Carlo N-Particle

MDL minimum detectable level

MED Manhattan Engineers District

MeV megaelectron-volt, 1 million electron-volts

mg milligram

mm millimeter

mR milliroentgen

mrad millirad

MRD minimum recordable dose

mrem millirem

n neutron

NCRP National Council on Radiation Protection and Measurements

NIOSH National Institute for Occupational Safety and Health

NTA nuclear track emulsion, type A 

PNL Pacific Northwest Laboratory

PC probability of causation

PPD Pantex Personnel Dosimeter
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ROT rotational

RPG radiation protection guideline

TBD technical basis document

TLD thermoluminescent dosimeter

TLD-100 LiF with natural abundance of 6

Li and 7Li

TLD-600 LiF enriched with 6

Li

TLD-700 LiF enriched with 7

Li

TLND thermoluminescent neutron dosimeter

U.S.C. United States Code

yr year

Z atomic number

α alpha particle

β beta particle

γ gamma ray

μgm microgram
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6.1 INTRODUCTION

Technical basis documents and site profile documents are not official determinations made by the 

National Institute of Occupational Safety and Health (NIOSH) but are rather general working 

documents that provide historic background information and guidance to assist in the preparation of 

dose reconstructions at particular sites or categories of sites. They will be revised in the event 

additional relevant information is obtained about the affected site(s). These documents may be used 

to assist the NIOSH staff in the completion of the individual work required for each dose 

reconstruction.

In this document the word “facility” is used as a general term for an area, building, or group of 

buildings that served a specific purpose at a site. It does not necessarily connote an “atomic weapons 

employer facility” or a “Department of Energy [DOE] facility” as defined in the Energy Employees 

Occupational Illness Compensation Program Act [EEOICPA; 42 U.S.C. § 7384l(5) and (12)]. 

EEOICPA defines a DOE facility as “any building, structure, or premise, including the grounds upon 

which such building, structure, or premise is located ... in which operations are, or have been, 

conducted by, or on behalf of, the Department of Energy (except for buildings, structures, premises, 

grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program)” [42 U.S.C. § 

7384l(12)]. Accordingly, except for the exclusion for the Naval Nuclear Propulsion Program noted 

above, any facility that performs or performed DOE operations of any nature whatsoever is a DOE 

facility encompassed by EEOICPA.

For employees of DOE or its contractors with cancer, the DOE facility definition only determines 

eligibility for a dose reconstruction, which is a prerequisite to a compensation decision (except for 

members of the Special Exposure Cohort). The compensation decision for cancer claimants is based 

on a section of the statute entitled “Exposure in the Performance of Duty.” That provision [42 U.S.C. § 

7384n(b)] says that an individual with cancer “shall be determined to have sustained that cancer in the 

performance of duty for purposes of the compensation program if, and only if, the cancer ... was at 

least as likely as not related to employment at the facility [where the employee worked], as 

determined in accordance with the [probability of causation1

As noted above, the statute includes a definition of a DOE facility that excludes “buildings, structures, 

premises, grounds, or operations covered by Executive Order No. 12344, dated February 1, 1982 

(42 U.S.C. 7158 note), pertaining to the Naval Nuclear Propulsion Program” [42 U.S.C. § 7384l(12)]. 

While this definition contains an exclusion with respect to the Naval Nuclear Propulsion Program, the 

section of EEOICPA that deals with the compensation decision for covered employees with cancer 

[i.e., 42 U.S.C. § 7384n(b), entitled “Exposure in the Performance of Duty”] does not contain such an 

exclusion. Therefore, the statute requires NIOSH to include all occupationally-derived radiation

exposures at covered facilities in its dose reconstructions for employees at DOE facilities, including 

radiation exposures related to the Naval Nuclear Propulsion Program. As a result, all internal and 

external dosimetry results are considered valid for use in dose reconstruction. No efforts are made to 

determine the eligibility of any fraction of total measured exposure for inclusion in dose 

reconstruction. NIOSH, however, does not consider the following exposures to be occupationallyderived:

] guidelines established under subsection 

(c) ...” [42 U.S.C. § 7384n(b)]. Neither the statute nor the probability of causation guidelines (nor the 

dose reconstruction regulation) define “performance of duty” for DOE employees with a covered 

cancer or restrict the “duty” to nuclear weapons work.

 

1 The U.S. Department of Labor is ultimately responsible under the EEOICPA for determining the probability of 

causation (POC). 
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• Radiation from naturally occurring radon present in conventional structures; 

• Radiation from diagnostic X-rays received in the treatment of work-related injuries. 

6.1.1

Pantex Plant was one of the last plants built during World War II to load, assemble, and pack high 

explosive (HE) ordnance. The plant began operations in September 1942 only 9 months after 

groundbreaking and operations stopped the week after the War ended on August 14, 1945 (Mitchell 

2003). The purpose of this TBD is to describe the external dosimetry systems and practices at 

Pantex beginning in December 1951 when U.S. Atomic Energy Commission (AEC) operations began. 

This document discusses historical and current practices in relation to the evaluation of external 

radiation exposure of monitored and unmonitored workers. 

Purpose

6.1.2

Pantex Operations play an important role in the U.S. nuclear weapons program. Historically, Pantex 

has provided several roles associated with the assembly, disassembly, retrofit, and modification of 

nuclear weapon systems (Mitchell 2003). Today, Pantex continues to fabricate high explosives and 

assemble nuclear weapons. The principal operations at this site, however, are the dismantling of 

retired nuclear weapons and the maintenance of the nation's nuclear weapons stockpile. Pantex, 

which is operated by DOE's Office of Defense Programs, is the only facility in the United States that 

performs these operations.

Scope

The methods and concepts of measuring occupational external doses to workers have evolved since 

the beginning of Pantex operations. An objective of this document is to provide a technical basis to 

evaluate external radiation exposure to workers that can reasonably be associated with Pantex 

operations under EEOICPA legislation. Consistent with NIOSH guidelines, this document identifies 

options to adjust historical recorded occupational external dose to account for current scientific 

methods and protection factors. In particular, this document presents the methods to prepare worker 

dose information for input to the NIOSH Interactive RadioEpidemiological Program (IREP). 

6.2 EXTERNAL DOSIMETRY 

Information on the history of Pantex Plant nuclear weapons assembly activities involves classified

information, so a complete description of events is not publicly available. The U.S. Atomic Energy

Commission (AEC) built two nuclear weapons assembly plants to supplement assembly activities at 

Sandia National Laboratories that began in about 1945 (DOE 1997). One of these was at the Iowa 

Army Ammunition Plant (IAAP) in 1947; the second was the Pantex Plant in 1951. Pantex was 

originally a conventional munitions factory loading high explosives into bombs and artillery shells 

(DOE 1997); it was converted to nuclear weapons work in 1951–1952. In 1975, IAAP nuclear 

weapons assembly work transferred to the Pantex Plant. The Pantex Plant remains operational as 

the sole DOE facility for nuclear weapons assembly, modification, and dismantling (DOE 1997). This 

TBD summarizes information obtained from the Pantex Plant and other sources related to radiation 

doses received by Plant workers from external sources.

Details of Pantex workers handling sources of radiation, such as depleted uranium (DU), plutonium, 

and other nuclear weapon materials, involves classified information. Work activities undoubtedly 

varied over time. Analysis of historical information showed that assembly activities at Pantex began in 

1952, which corresponds with the first record of personnel monitoring (Carr 1992). The nature of the 

radiation fields a Pantex worker could have encountered depends on the type of facility in which the 

work occurred. Nuclear weapons components emit alpha, beta, X-, and gamma rays, and neutrons; 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 11 of 61

however, doses to workers depend strongly on the configuration (i.e., material and shielding) of the 

source of radiation and the work performed (OXLEY 2001). In addition, industrial radiography 

operations had the potential to expose some workers to X-ray or gamma radiation. Workers were 

potentially exposed to various radiation fields from DU. This TBD addresses the significance of these 

radiation fields.

External Dose Reconstruction Implementation Guidelines (NIOSH 2002) determined that external 

personnel dosimetry results are the highest quality record for assessing historical doses from external 

sources to individuals and their organs. The DOE Laboratory Accreditation Program (DOELAP) 

accredited the current Pantex dosimetry system in 1993. Before 1993, several dosimetry systems 

measured radiation doses to workers from external sources. Early dosimetry practices were based on 

experience gained during several decades of radium and X-ray use in medical diagnostic and 

therapeutic applications. These methods were generally well advanced at the start of the Manhattan 

Engineers District (MED) project to develop nuclear weapons in the 1940s (Morgan 1961; Taylor 

1971). The primary difficulties encountered in MED efforts to measure worker doses to external 

radiation were (1) the potential for large quantities of high-level radioactivity that had not been 

encountered previously and (2) mixed radiation fields involving beta particles, photons (X- and gamma 

rays), and (3) neutrons with a broad spectrum of energies. This TBD summarizes what is known 

about dosimetry systems used at Pantex and their technical performance in measuring dose to 

workers.

6.3 BASIS OF COMPARISON

Since the initiation of the MED project in the early 1940s, various concepts and quantities have been 

used to measure and record occupational radiation dose at MED/AEC/DOE facilities. A common 

basis of comparison has been selected to assess the consistency of the available recorded dose at 

Pantex operations in comparison to current dosimetry performance and field-tested capabilities. The 

dates of change in the Pantex dosimetry systems are known; comparisons of recorded doses before 

and after these changes provide the ability to assess consistency. Similar radiation beams have been 

used historically to calibrate and conduct performance testing of dosimetry systems (AEC 1955; 

Unruh et al. 1967; McDonald et al. 1983). This basis, to be used in dose evaluation or reconstruction, 

is the personal dose equivalent, Hp(d), where d identifies the depth in millimeters and represents the 

point of reference for dose in tissue. For weakly penetrating radiation of significance to skin dose, d = 

0.07 mm; the personal dose equivalent is noted as Hp(0.07). For penetrating radiation of significance 

to whole-body dose, d = 10 mm; the personal dose equivalent is noted as Hp(10). Both Hp(0.07) and

Hp(10) are recommended for use as operational quantities to be recorded for radiological protection 

by the International Commission on Radiological Units and Measurements (ICRU 1993). DOE has 

used these radiation quantities in the DOELAP since the 1980s to accredit personnel dosimetry 

systems in the Complex (DOE 1986).

6.4 EXTERNAL RADIATION EXPOSURE RECORDS

Pantex maintains a database containing monthly, annual, and career dose information for workers 

from 1952 to the present. Annual dose data include the whole-body dose equivalent from photons 

and neutrons, individually and collectively. Table 6-1 summarizes the average recorded worker dose 

for each year along with the total collective dose and its neutron and gamma components. At first, 

Pantex issued dosimeters only to workers likely to receive a radiation dose. From 1952 through 1957, 

this included only radiographers. From 1958 through 1988, only radiation workers were monitored. 

The variations in numbers of radiation workers reflect changes in weapon production rates. From 

1989 to the present, all Pantex workers have been monitored for external radiation exposure (Griffis 

1988). Figure 6-1 shows the number of workers monitored and the number who had recorded annual 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 12 of 61

Table 6-1. Annual external radiation doses, 1952–2004 (Prather 2004).

Year

Total 

collective dose 

(person-rem)

Number of 

workers 

monitored

Average 

total dose 

(rem)

Collective 

neutron dose 

(person-rem)

Collective 

gamma dose 

(person-rem)

1952 0.00 1 0.00 0.00 0.00

1953 0.00 1 0.00 0.00 0.00

1954 0.00 2 0.00 0.00 0.00

1955 0.00 1 0.00 0.00 0.00

1956 0.00 1 0.00 0.00 0.00

1957 0.02 3 0.01 0.00 0.02

1958 0.09 19 0.01 0.00 0.09

1959 0.35 22 0.02 0.00 0.35

1960 10.35 69 0.15 9.20 1.15

1961 8.74 71 0.12 6.23 2.51

1962 5.27 64 0.08 1.53 3.74

1963 18.20 218 0.08 5.75 12.45

1964 79.91 253 0.32 7.80 72.11

1965 47.41 416 0.11 2.53 44.88

1966 70.46 581 0.12 4.39 66.07

1967 78.33 563 0.14 1.51 76.82

1968 29.64 423 0.07 0.55 29.09

1969 30.84 432 0.07 0.17 30.67

1970 85.46 468 0.18 0.43 85.03

1971 101.42 495 0.21 1.08 100.34

1972 70.84 467 0.15 0.50 70.34

1973 86.35 441 0.20 0.17 86.18

1974 75.61 500 0.15 0.95 74.66

1975 61.89 493 0.13 17.13 44.76

1976 45.77 463 0.10 12.76 33.01

1977 58.08 465 0.13 10.14 47.94

1978 50.46 518 0.10 13.12 37.34

1979 178.91 714 0.25 62.85 116.06

1980 147.52 819 0.18 30.40 117.12

1981 201.19 915 0.22 28.78 172.41

1982 110.76 1,002 0.11 23.31 87.45

1983 103.18 1,027 0.11 24.60 78.58

1984 141.71 1,113 0.13 21.54 120.17

1985 133.56 1,172 0.11 27.87 105.69

1986 85.59 1,129 0.08 20.49 65.10

1987 34.85 1,160 0.03 4.05 30.80

1988 24.98 1,121 0.02 2.74 22.24

1989 33.56 1,438 0.02 3.22 30.34

1990 23.46 2,090 0.01 1.92 21.54

1991 22.31 2,126 0.01 0.23 22.08

1992 50.59 2,317 0.02 15.41 35.18

1993 44.83 2,624 0.02 12.78 32.05

1994 28.82 2,978 0.01 6.55 22.27

1995 36.62 3,107 0.01 10.24 26.39

1996 27.62 3,209 0.01 5.79 21.83

1997 10.99 3,120 0.00 2.46 8.54

1998 14.84 2,800 0.01 2.99 11.84

1999 25.59 2,686 0.01 4.39 21.20

2000 34.18 2,766 0.01 6.55 27.63

2001 42.82 2,770 0.02 7.70 35.11

2002 46.87 2,947 0.02 8.93 37.94

2003 35.28 2,996 0.01 5.14 30.15

2004 23.62 3,168 0.01 4.77 18.85
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1

10

100

1,000

10,000

1940 1950 1960 1970 1980 1990 2000 2010

Number

Monitored

Number

with Zero

Dose

Figure 6-1. Number of workers monitored as a function of time and 

number of workers with zero recorded annual dose (Martin 2003a).

doses of zero from external sources. For most of this period, very few workers received significant 

external doses. From 1965 to 1980, however, a larger fraction of the workers received non-zero 

external doses. The increase is probably a result of increased production and increased handling of 

nuclear components.

From 1989 to 1991, Pantex implemented the Historical Exposure Records System (HERS) to capture 

past radiation dose records and ensure complete documentation (Rawlston 1991). Exposure records 

were retrieved from the archives, reviewed, and summarized. Individual workers were interviewed 

and their records were checked for accuracy. Missing records or anomalies were analyzed, with 

worker assistance, and appropriate notes were entered in the record. The HERS project produced 

the best possible set of radiation exposure records attainable in 1991.

6.5 DOSE RECONSTRUCTION PARAMETERS

Examinations of the beta, photon (X- and gamma ray), and neutron radiation types, energies, and 

workplace exposure geometries, and the characteristics of Pantex Plant dosimeter responses, are 

crucial for the assessment of bias and uncertainty of the original penetrating dose of record in relation 

to the radiation quantity Hp(10). The bias and uncertainty for current dosimetry systems are typically 

well documented for Hp(10). The performance of current dosimeters can often be compared to 

performance characteristics of historical dosimetry systems in the same, or highly similar, facilities or 

workplaces. In addition, current performance testing techniques can be applied to earlier dosimetry 

systems to achieve a consistent evaluation of all dosimetry systems.
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Overall, the accuracy and precision of original individual worker doses of record and their 

comparability to be considered in using NIOSH (2002) guidelines depend on:

• Administrative practices adopted by facilities to calculate and record personnel dose based 

on technical, administrative, and statutory compliance considerations

• Dosimetry technology used, including the physical capabilities of the dosimetry system, such 

as response to radiation type and energy, especially in mixed radiation fields

• Calibration methods used for monitoring systems and the similarity of the methods of 

calibration to sources of exposure in the workplace

• Workplace radiation fields that can include mixed types of radiation, variations in exposure 

geometries, and environmental conditions

An evaluation of the original doses of record based on these parameters is likely to provide the best 

estimate of Hp(0.07), as necessary, and Hp(10) for individual workers with the least relative overall 

uncertainty.

6.5.1

Pantex started monitoring workers for radiation exposure in 1952. Dosimeters used at that time to 

measure worker radiation doses were contracted from a commercial service. Table 6-2 summarizes 

the monitoring technique and exchange frequency. The minimum recordable dose (MRD) for 

nonpenetrating skin and penetrating whole-body dose, as reported by the film badge processor, were

initially 30 and 10 mrem, respectively (Tracerlab 1963). Actual minimum detectable levels (MDLs) are 

typically higher because of additional uncertainty in field use and the use of dose recording 

thresholds. Table 6-2 lists reasonable MDLs for most applications for film dosimeters based on 

Wilson (1960, 1987), NIOSH (1993), NRC (1989), and Wilson et al. (1990) and for thermoluminescent 

dosimeters (TLDs) based on Fix et al. (1982) and Rathbone (2002). MRDs varied with time and 

processor, as listed in Table 6-2.

Historical Administrative Practices

Pantex Plant administrative practices important to dose reconstruction include historical policies for:

• Assigning dosimeters to workers 

• Exchanging dosimeters

• Recording notional dose (i.e., a dose that was added to a record when the dosimeter for a 

monitoring period was lost or damaged) (Reissland 1982)

• Investigating missed dose (i.e., a dose that was added to a record when the dosimeter for a 

monitoring period was lost or damaged) (Watson et al. 1994)

• Replacing destroyed or missing records

• Evaluating and recording doses for incidents or accidents

• Obtaining and recording occupational dose to workers for other exposures
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Table 6-2. Dosimeter type, period of use, exchange frequency, MRD, and MDL (Martin 2003b).

Dosimeter type/

provider Period

Exchange 

frequencya

MRD (mrem) MDL (mrem)

Skin β/γ deep Neutron Skin Deep Neutron

βγ film/Tracerlab 1/1952–12/1959 Weekly 30b 10b 40c 40c

βγ film and NTA film/ 

Tracerlab

1/1960–3/1961 Weekly 30b 10b 15b 40c 40c (d)

4/1961–5/1963 Monthly 30b 10b 15b 40c 40c (d)

βγ film and NTA film/

Eberline

6/1963–9/1964 Monthly 10b 10b 10b 40c 40c (d)

βγ film and NTA film/

Landauer

10/1964-12/1968 2/month 40b 10b 10b,e 40c 40c (d)

1/1969–12/1972 Monthly 20b,f

TLD 2-element/in-house 

and NTA film/Landauerg

1973–1976 Monthly 10 4 10b,e 30 30 (d)

TLD 6-element/in-house 1977–1980 Monthly 10 4 50 30 30 50

Panasonic 802/in-house 1980–1991h Monthly 20 20 50 30 30 50

Panasonic 802/in-house 1992–2000h Monthly 15 10 70 30 30 50

Quarterly 20 15 85 30 30 50

Panasonic 809/812/inhousei 1994–present Monthly 10 10 5j 30 30 50

25k

Quarterly 15 15 10j 30 30 50

65k

a. Exchange frequencies were established from dosimetry reports. The initial weekly exchange frequency was changed to 

monthly in March 1961 (Tracerlab 1963). A monthly exchange frequency continued with Eberline (Ashton 2003). An 

exchange frequency of twice per month for both beta/gamma and neutron films was established with Landauer in 

October 1964; this frequency changed, for both beta/gamma and neutron films, to monthly in January 1969 (Adams 

2003). Nuclear track emulsion, type A (NTA) film provided by Landauer was used with the two-element TLD and 

exchanged monthly (Adams 2003). 

b. Based on minimum doses recorded on dosimetry reports (Tracerlab 1963, Ashton 2003, Adams 2003). 

c. Estimated MDL typical of film dosimeter capabilities (Wilson 1960, 1987; NIOSH 1993; NRC 1989; Wilson et al. 1990).

d. For years of NTA film use, before 1977, the reconstructed neutron dose is calculated using the adjusted photon dose 

and a neutron-to-photon dose ratio.

e. MRD for thermal neutrons (Adams 2003). 

f. MRD for fast neutrons (greater than 1 MeV) (Adams 2003). 

g. The Pantex in-house two-element TLD was implemented in 1973 for monitoring only beta-gamma radiation exposures. 

Use of NTA film continued for monitoring neutron exposures until the implementation of the six-element TLD system in 

1977.

h. In 1992, the algorithms were changed for the Panasonic 802 to the Stanford algorithms (Pantex 2002). The dosimeter 

exchange frequency for non-radiation workers was changed from monthly to quarterly in 1992. 

i. Beginning in January 1994, the Panasonic 809/812 dosimeter was provided to radiation workers and exchanged 

monthly. The Panasonic 802 dosimeter was provided to all other Pantex workers and exchanged quarterly. Between 

1994 and 2000, Panasonic 802 dosimeters were gradually phased out and replaced by Panasonic 809/812 dosimeters 

for all workers.

j. DOELAP performance testing with moderated 252Cf neutrons.

k. DOELAP performance testing with unmoderated 252Cf neutrons.

At a minimum, Pantex routine practices appear to have required assigning dosimeters to personnel 

designated as radiation workers who could receive an external radiation dose greater than 10% of the

Radiation Protection Guideline (RPG) of 5 rem/year. Dosimeters were exchanged on a routine 

schedule. Beginning in 1980, if dosimeters were lost or damaged, investigations were conducted and 

doses were recorded reflecting the results of the investigation. Before 1980, there appear to be 

missing dose components for some workers based on such designations as “not available” or 

“damaged film” in worker records. These missing components can be reconstructed from other 

recorded dosimeter data using methods described by Watson et al. (1994) and based on examination 

of continuity in worker job activities, or by using recommended methods described in later sections of 

this TBD.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 16 of 61

6.5.2

Pantex Plant dosimetry methods evolved with the development of improved technology and a better 

understanding of the complex radiation fields encountered in the workplace. The adequacy of 

dosimetry methods to measure radiation dose accurately, as discussed in later sections, depends on 

radiation type, energy, exposure geometry, etc. (OXLEY 2001). Dosimeter exchange frequency 

gradually lengthened and corresponded to downward reductions in RPGs (Morgan 1961; Taylor 

1971). During the early stages of the program to monitor individual Pantex workers, a weekly dose 

control of 0.3 rem was in effect. Table 6-2 summarizes major changes in Pantex external dosimetry 

systems and routine dosimeter assignment periods for workers.

Dosimetry Technology

The first dosimeter used at Pantex was a two-element film badge supplied by Tracerlab for measuring 

beta, X-ray, and gamma exposures (Tracerlab 1963). Beginning in 1960, Pantex used a multielement 

film badge that incorporated NTA film to measure beta, X-ray, gamma, and fast neutrons (AEC 1955; 

Tracerlab 1963). From 1972 to 1976, a two-element, in-house TLD system was used to measure 

beta, X-ray, and gamma exposures, while NTA film was retained to measure fast neutrons 

(Alexander, Hess, and Canada 1973). From 1977 to 1980, Pantex used a six-element, in-house TLD 

system that included personal nuclear accident dosimeter elements (DOE 1980). Beginning in 1980, 

Panasonic TLD systems with automatic readers were used; the UD-802 TLD was used from 1980 to 

1993. The UD-809/ UD-812 TLD system was DOELAP-accredited and used for radiation workers

beginning in 1994 (Pantex 2002). The UD-802 was used for all other workers until it was phased out 

in 2000. All Pantex workers have been monitored with the UD-809/UD-812 TLD since 2000. 

A few documents or results of studies describe earlier dosimetry systems (AEC 1955; Roberson et al. 

1983; McDonald et al. 1983). For the current TLDs, MRDs are precisely defined in Pantex Plant 

Technical Basis Manual for External Dosimetry (Pantex 2002). The MRDs are not necessarily 

equivalent to the MDL or lower limit of detection (LD) described in NIOSH (2002) or in the DOELAP 

Standard (DOE 1986). Dosimeter readings indicating a dose less than these MDLs were judged to 

have high uncertainty. For earlier dosimetry systems, there were similar quantities below which doses 

were not recorded. Others might have been MRDs based on expert judgment. In either case, 

dosimetry results less than the MRD were recorded as zero. Table 6-2 lists MRDs of dosimeters used 

at the Pantex Plant to monitor for beta/gamma skin and deep doses, and neutron deep doses.

The term MDL, which is widely used in NIOSH documents, can vary depending on many conditions 

including dosimeter type, processing equipment, calibration techniques, and procedures. Because of 

these variations, NIOSH has evaluated external beta/photon film (ORAUT 2004a) and 

thermoluminescent (ORAUT 2003a) dosimetry capabilities and has established standard MDLs for 

missed beta/photon dose and a correction factor for variability. The standard MDLs (missed dose) 

per exchange cycle for beta/photon dose for film and thermoluminescent dosimeters are 40 and 30 

mrem, respectively. A typical MDL (missed dose) per exchange cycle for neutrons is 50 mrem for 

both NTA film (ORAUT 2005a) and thermoluminescent neutron dosimeters (TLNDs; Wilson et al. 

1990).

6.5.2.1 Beta/Photon Dosimeters

Figure 6-2 shows the response of a film badge to photon radiation of different energies; it also shows 

the Hp(10) response. The figure shows two responses for film badges: one for a sensitive DuPont 

502 emulsion in a two-element badge (Pardue, Goldstein, and Wollan 1944), and one for a sensitive 

DuPont 555 emulsion in the multielement badge (Thornton, Davis, and Gupton 1961). The response 

of the sensitive Eastman Type 2 film in a multielement film badge is similar to that of the sensitive 

DuPont 555 emulsion. The film badges show an over-response at photon energies around 100 keV, 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 17 of 61

due primarily to relatively (compared to tissue) high atomic numbers (Z) [silver (47) and bromine (35)] 

in the film emulsions. The film badges under-respond to lower energy photons, but the relative 

response of the two-element film badge to 60-keV photons from 241Am is nearly unity. The 

multielement film badge typically over-responds to 60-keV photons.

10-2 10-1 10 |0

Photon Energy (MeV)

0.1

1

10 Relative Response

Hp(10)

Two-Element Film Badge

Multi-Element Film Badge

Figure 6-2. Comparison of Hp(10) for photons with 

energy responses for sensitive DuPont 502 emulsion in 

MED two-element film badge (Pardue, Goldstein, and 

Wollan 1944) and sensitive DuPont 555 emulsion in Oak 

Ridge National Laboratory multielement film badge

(Thornton, Davis, and Gupton 1961).

The response of newer TLD badges provides a better match to the Hp(10) response in the soft 

tissues of the body due to the lower atomic number (Z) of the lithium (3) and fluorine (9) in the chips 

(Horowitz 1984; Cameron, Sunthanalingham, and Kennedy 1968). The two-element TLD badges 

used at Pantex from 1973 to 1976 had LiF (TLD-700) chips covered by a 7-mg/cm2 plastic film over 

an open window and a 290-mg/cm2 aluminum filter for beta-photon discrimination (Alexander, Hess, 

and Canada 1973). The six-element TLD badges adopted for use in 1977 were patterned after a 

Sandia design (DOE 1980; Martin 2003b). Figure 6-3 shows the TLD holder, chips, and filters. The 

open window used for measuring skin dose was covered by a 7-mg/cm2 polyester tape over the TLD700 chip. The aluminum-backed TLD-700 chip was used to measure deep dose. One TLD-700 chip 

was covered by cadmium and the other was backed by cadmium to discriminate between photon 

exposures from the front and back. The two TLD-600 chips were similarly backed and covered by 

cadmium to discriminate between neutron exposures from the front and back. In addition, nickelsulfur, cadmium-gold, cadmium-indium-copper, and gold-rhodium foils were included to provide a 

personal nuclear accident dosimeter capability.

The first commercial TLD badge, implemented at Pantex in 1980, was the multielement Panasonic 

Model UD-802 (Pantex 2002). The UD-802 TLD is capable of measuring beta, photon, and thermal 

neutron radiations. Table 6-3 lists phosphor and filter data for the UD-802 TLD and its holder. In 

general terms, elements E1 through E4 are used as follows: E1 is used for beta response, E2 is used 

for photon dose and beta energy determination, and E3 and E4 are used for photon energy 

characterization. The thin phosphor layer and minimal filtration over E1 enable excellent sensitivity to 

beta radiation and good response to photons and thermal neutrons. E2 is under approximately 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 18 of 61

Figure 6-3. Six-element TLD holder (DOE 1980).

300 mg/cm2 of plastic, providing a reasonably tissue-equivalent response to photons and penetrating 

beta radiation and thermal neutrons. The CaSO4 in E3 demonstrates a sharp over-response to lower 

energy photons due to the high effective Z of the material in relation to tissue. This element is 

sensitive to suitably penetrating beta radiation, but has no response to neutrons. A lead filter in E4 

compensates for the over-response of CaSO4 to lower energy photons. This filter preferentially 

removes the lower energy photon component, reducing the over-response because it is insensitive to 

neutron radiation and is beyond the range of expected beta radiation. E4 is used for reporting 

environmental exposure. The UD-802 TLD system was DOELAP-accredited in 1993 for all radiation 

categories except those including neutrons.

Table 6-3. UD-802 dosimeter characteristics (Pantex 2002).

Characteristic E1 E2 E3 E4

Phosphor 6Li2B4O7

6

Li2B4O7 CaSO4 CaSO4

Filtration Plastic Plastic Plastic Plastic/lead

Filter thickness, mg/cm2 20 300 300 1,000

Primary sensitivity Beta, gamma, neutron Gamma, neutron Gamma Gamma

The Panasonic UD-809/UD-812 TLD system was fully implemented in January 1994 (Pantex 2002). 

This system was DOELAP-accredited in all beta, photon, and neutron radiation testing categories in 

1993. The UD-812 TLD is the same as the UD-802 in phosphor type and filtration. The notable 

exception is that the lithium-borate phosphor in this dosimeter is depleted of the neutron-sensitive 6

Li 

and 10B, so signals from E1 and E2 are due only to photon and beta radiation. This makes the final 

dose determination more straightforward and precise. Table 6-4 lists phosphor and filtration data for 

the UD-812 TLD and holder used at Pantex. The response of the UD-812 is essentially the same as 

that of the UD-802 with the exception of the neutron fields, for which the UD-812 has no response.

The UD-809 TLD was designed for determination of neutron dose (Pantex 2002). It uses four lithiumborate phosphors under different filters of approximately the same density thickness. Table 6-4 lists 

phosphor and filtration data for the UD-812/UD-809 and holder used at Pantex. The first position, E5, 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 19 of 61

Table 6-4. UD-812/UD-809 dosimeter characteristics (Pantex 2002).

Element Phosphor

Filtration 

(front/back)

Filter thickness

(mg/cm2) Sensitivity

Primary 

use

E1 (812) 7Li2

11B4O7 Plastic 17 Beta/gamma Beta

E2 (812 7Li2

11B4O7 Plastic 150 Beta/gamma Beta

E3 (812) CaSO4 Plastic 300 Beta/gamma Gamma

E4 (812) CaSO4 Plastic + lead 1,000 Gamma Gamma

E5 (809) 7Li2

11B4O7 Cd/Cd 900 Gamma Gamma

E6 (809) 6Li2

10B4O7 Sn/Cd 900 Gamma/thermal neutron Neutron

E7 (809) 6Li2

10B4O7 Cd/Cd 900 Gamma/neutron Neutron

E8 (809) 6Li2

10B4O7 Cd/Sn 900 Gamma/albedo neutron Neutron

is 7Li2

11B4O7 depleted of the neutron-sensitive 6

Li and 10B. This element is used to estimate the 

photon response on the remaining three elements. Because the effective measurement depths of E6, 

E7, and E8 are beyond the range of expected beta radiation, the nonphoton response is due solely to 

neutrons. E6, with the tin filter on the front side (facing away from the worker’s body), responds to 

incident thermal neutrons; however, with the cadmium filter on the back side, the response to albedo 

neutrons is minimized. E8 has the opposite filtration, so its response to incident thermal neutrons is 

minimized. E7, which is not currently used in Pantex dose algorithms, has cadmium on front and 

back, so its response indicates that neutrons pass through the cadmium and still create a signal. The 

general application of this dosimeter design is to use the ratio of the albedo neutron signal to the 

incident thermal neutron signal to characterize the neutron field.

Analyses of dosimeter performance data and workplace collective dose patterns in Table 6-1 enable

some judgments about consistency in historical measured radiation doses. The International Agency 

for Research on Cancer (IARC) conducted a comparison study of 10 commonly used dosimetry 

systems from around the world (Thierry-Chef et al. 2002). Three of the designs were from the United 

States: a two-element film dosimeter previously used at the DOE Hanford Site (identified as US-2), a 

multielement film dosimeter previously used at Hanford (US-8), and the Panasonic 802 TLD used at 

the DOE Savannah River Site (US-22) (and at Pantex from 1980 to 2000). The study concluded that 

exposure to workers could be characterized as a combination of anterior-posterior (AP), rotational 

(ROT), and isotropic (ISO) irradiation geometries. Dosimeter responses for these geometries were 

investigated using two phantoms to represent the torso of the body. The first phantom was a waterfilled slab phantom with polymethyl methacrylate walls, an overall width of 30 cm, an overall height of

30 cm, and an overall depth of 15 cm. This phantom is widely used for dosimeter calibration and 

performance testing by the International Standards Organization. The second phantom was an 

anthropomorphic Alderson Rando Phantom. This realistic man-type phantom has a natural human 

skeleton cast inside material that has a tissue-equivalent composition. Table 6-5 lists the results of 

this study for the U.S. dosimeters. The two-element film dosimeter significantly overestimated Hp(10)

at the lower photon energies of 118 keV and 208 keV. As noted above, the multielement film badge 

was used at Pantex in essentially the same manner as the two-element film badge.

To evaluate the dosimeter response to lower energy (i.e., less-than-100-keV) photons that are 

significant in plutonium operations, Hanford conducted intercomparison testing of all Hanford historical 

dosimeter film designs (Wilson et al. 1990) using AP irradiations only. Although there are differences 

in films and filters used in multielement dosimeters, good comparison in energy response for both 

Pantex and Hanford dosimeters is probably based on similar design characteristics. The results of 

this testing for energies greater than 100 keV are consistent with the IARC results, showing an

overestimate of Hp(10) for the two-element dosimeter used from 1944 to 1956. 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 20 of 61

Table 6-5. IARC study results for U.S. beta/photon dosimeters (Thierry-Chef et al. 2002).

Geometry Phantom

118 keV 208 keV 662 keV

Meana SD/Meanb Meana SD/Meanb Meana SD/Meanb

US-2 (Two-element film dosimeter)

AP Slab 3.0 2.1 1.3 1.0 1.0 0.8

AP Anthropomorphic 3.0 4.2 1.2 1.9 1.0 1.8

ROT Anthropomorphic 2.2 2.0 1.4 3.0 1.2 3.2

ISO Anthropomorphic 1.5 4.4 1.1 1.6 1.0 2.7

US-8 (Multielement film dosimeter)

AP Slab 1.0 1.5 1.0 0.8 0.8 1.7

AP Anthropomorphic 0.8 9.5 0.9 6.0 0.8 1.8

ROT Anthropomorphic 1.2 1.9 1.2 1.7 1.1 1.8

ISO Anthropomorphic 1.0 3.0 1.2 9.0 1.0 2.3

US-22 (Multichip TLD)

AP Slab 0.9 4.4 0.9 3.9 0.9 3.5

AP Anthropomorphic 0.8 3.1 0.9 2.1 0.9 3.9

ROT Anthropomorphic 1.1 3.1 1.2 1.5 1.0 4.1

ISO Anthropomorphic 0.9 0.3 1.0 2.5 0.9 1.6

a. Ratio of dose of record to Hp(10). 

b. Ratio of standard deviation (SD) to the mean. 

6.5.2.2 Neutron Dosimeters

The two general types of neutron dosimeters used at the Pantex Plant differ significantly in their 

response to neutrons of different energies, as shown in Figure 6-4 (IAEA 1990). NTA film was 

included in the holder used for the Pantex beta/gamma dosimeter from 1960 through 1976 (Martin 

2003b). In general, the response of the NTA film decreases with decreasing neutron energies greater 

than a minimum threshold energy for laboratory studies estimated to be about 500 keV (IAEA 1990), 

and the neutron TLD response increases with decreasing neutron energy, as shown in Figure 6-4 

(IAEA 1990). The minimum threshold energy for routine use in Pantex mixed photon and neutron 

radiation fields is probably about 1 MeV. Results reported at the first AEC Neutron Dosimetry 

Workshop indicated that laboratory dose measurements made with NTA film were about one-half to 

one-fourth of those measured with other methods, including the neutron TLD (Vallario, Hankins, and 

Unruh 1969). The response of both dosimeters is highly dependent on the neutron energy spectra, 

and both dosimeter types require the matching of laboratory calibration neutron spectra to workplace 

neutron spectra for reliable results.

The neutron response of the six-element, in-house TLD system was similar to the response of the 

Sandia TLD system (PNL 1977). The dosimeter responded well to thermal neutrons, but underresponded to neutron energies above 10 keV.

Roberson et al. (1983) measured the Panasonic UD-802 dosimeter response to thermal and fast 

neutron beams. Neutron doses measured by the UD-802 between 1980 and 1992 are likely to be 

underestimated (Pantex 2002). The performance of the UD-802 for measuring neutron doses was 

improved in 1992 and 1993 when the Stanford algorithm was applied (Stanford 1993).

Neutron doses measured with the Panasonic UD-809/UD-812 dosimeter system were much 

improved. Neutron doses determined by means of the Stanford algorithm (Stanford 1993) are likely to 

be accurate based on DOELAP performance testing results and workplace validation studies (Pantex 

2002). 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 21 of 61

Figure 6-4. Comparison of Hp(10) from normally incident neutrons 

to energy responses of NTA film and neutron albedo dosimeter 

containing neutron TLD chip made of 6

LiF and shielded by 

cadmium (IAEA 1990).

6.5.2.3 Effects of Changing Early Dosimetry Services

Pantex has historically used different dosimetry technology, different film-based commercial dosimetry 

services, and in-house TLD capabilities. There are only limited and incomplete Pantex studies 

comparing the performance of the early dosimetry systems or services. However, in 1954 the AEC 

conducted performance testing of several commercial (including Tracerlab) and in-house film 

dosimeter services with exposures provided by the National Bureau of Standards (AEC 1955); this 

document includes specific dosimeter design specifications. The testing included 40-, 70-, and 

210-keV narrow spectral beam X-ray techniques, 60Co gamma radiation, and selected mixtures of 

these beams. The report provides measured response data for each of the dosimeter open-window 

and filtered regions of the film. This information exhibits the significant over-response of the openwindow and lightly filtered regions of the film at lower (i.e., 40 and 70 keV) photon energies. The data 

certainly illustrate the ability, in spite of many differences in organizations, emulsion types, and 

dosimeter designs, to reasonably detect and measure photon radiation levels and energies Pantex 

workers could have received.

Examination of the Pantex cumulative dose records for the periods of use suggests that changes in 

the ratio between neutron and photon doses did occur. Without precise knowledge of the workplace 

radiation fields, the exact cause or effect is uncertain. However, a reasonable explanation is 

improved photon dosimetry with the TLD system that has nearly a tissue-equivalent response and 

significantly improved neutron dosimetry with the implementation of the TLND, as noted in Table 6-6. 

The ratio of the measured neutron-to-photon dose has increased during the periods of improving 

dosimetry capabilities from film beta/photon and NTA neutron dosimeters to sophisticated TLD 

systems. Figure 6-5 shows a plot in cumulative Pantex worker photon and neutron doses from 1952 

through 2000 and the years of implementation of new dosimetry methods. It is apparent that little 

neutron dose was measured before about 1963. The trend in the recorded photon dose is 

comparatively smooth during the transition from film to TLDs in 1977. The trend in the neutron dose 

10 0

10 1

10 2

10 3

10 4

10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 101

Neutron Energy (MeV)

Hp(10)

NTA Film

6

Relative Response

LiF with Cd Shield
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 22 of 61

fraction (compared to the photon dose) implies a significantly increased neutron dose fraction after 

1977 when TLDs were used. However, the ratio between neutron and photon doses is significantly 

variable, particularly before the mid-1980s.

Table 6-6. Ratio of neutron-to-photon cumulative dose.a

Dosimeter technology

Cumulative dose (person-rem)

Neutron Photon Ratio

Film + NTA, 1952 - 1972 41.67 595.66 0.070

TLD + NTA, 1973 - 1976 31.01 238.61 0.130

TLND, 1977 – 1993 303.45 1,142.09 0.266

809/812 TLND, 1994 - 2004 65.51 261.75 0.250

a. Data from Table 6-1.

Pantex Cumulative Annual Doses

0

500

1000

1500

2000

2500

1950 1960 1970 1980 1990 2000

Year

Cumulative Dose, person-rem

Neutron

Photon

TLND

TLD

809/812

802

Film

NTA

Figure 6-5. Cumulative plot of annual photon and neutron recorded dose. 

6.5.3

Potential error in doses of record depends on the methods used to calibrate dosimeters and the 

extent of the similarity between the radiation fields used for calibration and those encountered in the 

workplace. The potential error is much greater for dosimeters with significant variations in response, 

such as film dosimeters for lower energy photon radiation and NTA and neutron TLDs for neutron 

radiation.

Dosimeter Calibration Procedures

6.5.3.1 Beta/Photon Dosimeters

Pantex Plant film badges and TLDs were originally calibrated with 226Ra and 137Cs sources, with 

exposure measured by Victoreen R chambers. Deliberately irradiated film badges were sent 

periodically to R. S. Landauer, Jr., and Company beginning in 1970, and reported doses were 

compared with measured doses for calibration (Adams 2003). Similar calibration procedures were 

used with the development and operation of the in-house film and TLD systems between 1973 and 

1980 (see Table 6-2). Table 6-7 lists sources of bias in the calibration parameters for beta/photon 

dosimeters.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 23 of 61

Table 6-7. Common sources of laboratory bias in calibration parameters for beta/photon dosimeters.

a

Parameter Description Anticipated laboratory biasb

Free-in-air 

calibration

In 1970s, Pantex began exposing 

calibration dosimeters on phantom to 

simulate worker body. There were no 

on-phantom calibrations before 1970.

Dose of record is too high; however, effect of 

backscattered radiation from worker body is 

highly dependent on dosimeter design and actual 

geometry of radiation fields in workplace.

Radiation 

quantity

Photon dose quantities used to calibrate 

Pantex beta/photon dosimeters have 

varied. 

Because of higher energy, Ra-226 gamma 

radiation used to calibrate dosimeters at Pantex 

caused only slight (about 3%) under-response in 

dose of record. 

Depth of tissue 

dose

Pantex used selected depth of 1 cm (i.e., 

depth of testes) to estimate deep dose.

No significant effect because Pantex dosimeter 

designs had filtration density thicknesses of 

about 1,000 mg/cm2 that would relate to 1-cm 

depth in tissue.

Angular 

response

Pantex dosimeters were calibrated using 

AP laboratory irradiation.

Dose of record is probably too low because 

dosimeter response is lower at non-AP angles. 

Effect is highly dependent on radiation type and 

energy.

Environmental 

stability

Pantex film and TLD dosimeters are 

subject to signal fade with time, heat, 

humidity, light, etc.

Dose of record is probably too low; however, this 

depends strongly on when calibration dosimeters 

were irradiated during dosimeter exchange cycle. 

Midcycle calibration minimizes overall 

uncertainty. 

a. Judgment based on Pantex dosimeter response characteristics (Pantex 2002).

b. Dose of record compared to Hp(10). 

In the 1970s, during the development of the two-element and six-element TLD systems, a 60-Ci 137Cs 

source in a well facility in the 12-2 Building was used to calibrate TLD-700 chips. A 2-μgm 252Cf 

source was used to calibrate TLD-600 chips for measuring fast neutron dose. Records indicated that 

photon calibrations occurred in March 1978 and neutron calibrations occurred in September 1978 

(DOE 1980). Additional neutron response testing with a Pu-Be neutron source and a thermal neutron 

source occurred in April and October 1980. Calibration methods were similar to those used at Sandia 

National Laboratories. In the mid-1980s, a 0.5-Ci 137Cs source in the 12-10 Building was used to 

calibrate Panasonic UD-802 dosimeters. Element correction factors were determined for each chip in 

each dosimeter, which were used for improved photon dosimetry (Martin 2003a).

Calibrations for the Panasonic 802 and 809/812 TLD systems have occurred in the Pantex Radiation 

Safety Department Calibration Facility. This facility, first used in 1993, has 5- and 0.5-Ci 137Cs 

sources, a 120-μgm 252Cf source, a dosimetry-type X-ray machine, and two 90Sr and two 204Tl 

sources, which are used for DOELAP calibration (Martin 2003a).

6.5.3.2 Neutron Dosimeters

A complete account of the historical aspects of the calibration of Pantex neutron dosimeters is not 

available. It is known, however, that NTA films and in-house TLDs were originally calibrated with 

239Pu:Be and 252Cf sources. Deliberately irradiated NTA quality control film badges were sent 

periodically to Landauer beginning in 1970, and reported doses were compared with measured doses 

for calibration (Landauer 1976). Similar calibration procedures were used with the development and 

operation of the 6-element, in-house TLD system between 1977 and 1980. Table 6-8 lists common 

sources of expected laboratory bias for personnel neutron dosimeters based on comparison of the 

dose of record with Hp(10). 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 24 of 61

Table 6-8. Common sources of laboratory bias in calibration parameters for neutron dosimeters.

a

Parameter Description Anticipated laboratory biasb

Source energy 

spectrum

In 1970, Pantex began using dosimeters 

calibrated on phantoms to simulate worker body 

and neutron spectra that represented workplace. 

239Pu:Be and 252Cf sources were used. There 

were no on-phantom calibrations before 1970.

Delivered dose was uncertain, as noted in 

Section 6.4.2.2. 

Radiation quantity Neutron dose quantities used to calibrate Pantex 

neutron dosimeters have varied historically. First 

collision dose for fast neutrons and quality factor

of 10 was used for many years.

Effects of neutron dose quantities used to 

calibrate Pantex dosimeters are uncertain. In 

particular, fluence-to-dose conversion factors 

have varied over time. Exact values used 

before 1980 are not known.

Angular response Pantex dosimeters are calibrated using AP 

laboratory irradiation.

Dose of record is probably too low because 

dosimeter response is lower at non-AP angles. 

Effect is highly dependent on neutron energy 

and actual geometry of radiation fields in 

workplace.

Environmental 

stability

Pantex NTA film and neutron TLD dosimeters are 

subject to signal fade with time, heat, humidity, 

light, etc.

Dose of record is probably too low; however, 

this depends strongly on when calibration 

dosimeters are irradiated during dosimeter 

exchange cycle. Midcycle calibration 

minimizes overall uncertainty.

a. Judgment based on Pantex Plant dosimeter response characteristics (Pantex 2002).

b. Dose of record compared to Hp(10). 

6.5.4

The main workplace radiation fields at Pantex arise from the handling of nuclear weapons 

components containing plutonium, thorium, and highly enriched uranium (HEU) and their radioactive 

progeny, as well as DU. The highest dose rates are encountered when handling bare pits. Dose 

rates are lower when handling full weapons, physics packages, and pits in storage containers. Other 

workplace radiation fields involve industrial radiation-generating equipment (X-rays and electron 

accelerators) and isotopic gamma-ray and neutron sources for radiography and testing purposes 

(

60Co and 252Cf). The nuclides in the sealed nuclear weapon component pits emit beta, X-, gamma, 

and neutron radiation. From an external dosimetry perspective, the radiations of concern are beta 

particles, photons (X- and gamma rays), and neutrons. Radiation exposure to workers depends 

significantly on processes used in the preparation, design, and construction of the weapons.

Workplace Radiation Fields

As part of the DOELAP accreditation process for the Panasonic 809/812 TLD system, field 

measurements were made to characterize radiation fields in the Pantex workplace and to document 

the performance of the dosimetry system (Pantex 2002). Radiation fields were measured with TLDs 

positioned on a polymethylmethacrylate phantom and exposed under controlled conditions. The 

radiation fields were also characterized with several instruments used to measure the photon, 

neutron, and beta dose rates. Each weapon program characterized was measured in each of four 

configurations: full weapon, physics package, bare pit, and pit in storage container. The data derived 

from these measurements is classified; however, some generalized unclassified conclusions can be 

stated.

The photon dose rates were measured with a Victoreen Model 530 electrometer in conjunction with 

the Victoreen Model 550-3 ion chamber. The ion chamber was calibrated by Victoreen and is 

traceable to the National Institute of Standards and Technology using four different X-ray techniques: 

M50 (22 keV), M100 (39 keV), M200 (90 keV), and M250 (180 keV). The appropriate correction

factors were chosen based on gamma spectroscopy measurements made during the field 

measurements. Beta dose rates were measured with a Victoreen 450BE instrument with an open 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 25 of 61

window. Neutron dose rates were measured with tissue-equivalent proportional counters and 

multisphere measurements were analyzed to characterize the neutron spectra (Pantex 2002).

The predominant source of radiation dose at Pantex is photons and the main source is 241Am, with the 

60-keV photon being the most significant energy. The photon dose rate is very dependent on the 

configuration of the weapon. The more material that is added to the component, or the more 

complete its assembly, the lower the photon dose rate. In general terms, the neutron component of 

the radiation field begins as a standard spontaneous fission spectrum and then is degraded and 

moderated as the assembly process adds more material to the weapon. Beta dose is not limiting in 

the Pantex workplace. The primary source of beta radiation is depleted uranium. Total dose rates in 

the workplace are generally low, less than 10 mrem/hr, unless very close work is being performed 

(Pantex 2002). 

With very few exceptions, the following sections show that, for external dose reconstruction purposes, 

all beta radiation fields are greater than 15 keV, all photon radiation fields are between 30 and 

250 keV, and all neutron fields are between 0.1 and 2 MeV. Assuming that 100% of the radiation 

fields are within these ranges is a simplifying conservative assumption that is generally claimantfavorable.

6.5.4.1 Depleted Uranium

Pantex workers handled DU (primarily 238U) during assembly and disassembly of weapon 

components, and during and following testing. An important progeny nuclide for potential worker 

exposure in the 238U decay is 234Th with a half-life of 24.1 days. In a matter of a few months after 

purification, DU components have 234mPa activities nearly equal to that of 238U. Protactinium-234m 

emits beta radiation 99.87% of the time when it decays to 234U with a maximum energy of 2.29 MeV 

and an average energy of 0.825 MeV (Shleien, Slayback, and Birky 1998; ICRP 1983). An additional 

source of exposure in the Pantex workplace is from bremsstrahlung produced in high-Z materials from 

interactions with higher energy beta particles. Beta particles emitted by 234mPa excite both 

bremsstrahlung and characteristic X-rays in DU or 238U.

Beta radiation from DU could contribute to extremity and skin dose to workers unless precautions 

were taken to protect workers from the radiation. Protective clothing and gloves provide a protection 

factor of 2 or more, depending on the thickness. A bare slab source of DU contributes an Hp(0.07)

dose of approximately 200 mrad/hr at the surface (BRH 1970) compared to an Hp(10) dose of 

approximately 2 mrad/hr (ORAUT 2003b). However, significant beta exposures to Pantex workers 

were rarely detected by film badges or TLDs, based on a review of shallow and deep dosimetry data.

6.5.4.2 Photon Radiation

Photon radiations encountered at Pantex have widely varying energies, ranging from about 30 keV to 

a few MeV. Sources of photon radiation have included weapon components, analytical devices 

employing X-rays produced by radiation-generating devices, and low-activity radioactive sources, 

such as those used to check or calibrate radiation detectors. These sources could have included 

alpha, beta, photon, and neutron emitters and were of the types and source strengths typically used 

by mainstream industrial or process-related users. Doses associated with the proper, and 

widespread, use of small check sources are negligible.

Weapons assembly at Pantex has been performed with nuclear components of purified metals. The 

purification process separates natural progeny radionuclides from their parent metals, which provides 

some insight into potential sources of radiation. Plutonium is purged of progeny radionuclides when it 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 26 of 61

is purified. However, 241Am starts growing in immediately as its parent radionuclide 241Pu decays with 

a half-life of 14.4 yr. The 241Am, which emits 60-keV photons, reaches a maximum activity after about 

80 yr, but it reaches about 85% of this maximum in 40 yr. Thus, for nuclear weapons activities, this is 

increasingly significant with weapons disassembly, which often occurs many years after assembly.

A sample of purified 232Th would initially contain an equal activity of 228Th and 232Th with no progeny 

radionuclides. The reappearance of the progeny is complex (Stannard and Baalman 1988, p. 237). 

The governing radionuclide in the 232Th-to228Th chain is 228Ra, which has a half-life of 5.75 yr. The 

half-life of 228Th is 1.9 yr, and none of its progeny has a longer half-life. The gross activity of an 

initially pure mixture of 232Th and 228Th would rise for about a month, decline for about 4 yr, and rise to 

nearly complete equilibrium after 20 yr. Thorium progeny emit many energetic beta particles (1 to 

2.25 MeV) and many energetic gamma rays, including the 2.61-MeV gamma emitted by 208Tl in 100% 

of its decays (Shleien, Slayback, and Birky 1998).

The Monte Carlo N-Particle (MCNP) program was used to model spectral characteristics of 

bremsstrahlung photons from 1- and 30-cm-diameter 238U spheres. The results were similar for both 

spheres. Figure 6-6 shows the MCNP-calculated photon spectrum emitted from 238U as excited by 

the 234mPa beta spectrum shown on a logarithmic vertical axis. Note the smooth bremsstrahlung

spectrum and the uranium characteristic K X-rays at 90 to 109 keV and the L X-rays in the range of 13 

to 19 keV.

A linear vertical axis in Figures 6-7 and 6-8 shows the bremsstrahlung and characteristic X-ray 

components, respectively, of the calculated spectrum in Figure 6-6. The average energy of the 

photon spectrum is 0.41 MeV. The spectrum below 30 keV is insignificant. The characteristic X-ray 

photons produce their own Compton scattered photons, which are visible as elevated fluences 

underlying the characteristic X-rays. For workers near the older plutonium pits, the 241Am 60-keV 

gamma photons are the most significant source of photon radiation. Assembled weapon components 

were encased in a metallic cladding that significantly attenuated photon (particularly lower energy) 

radiation. Measured photon energy spectra in Pantex workplaces have confirmed that a major 

fraction of the photon dose rate near weapons is attributed to the 60-keV photons from 241Am (Pantex 

2002). 

Much of the interior surfaces of the buildings in which nuclear components are handled or stored are 

concrete. Most elements consisting of ordinary concrete have a low Z. Concrete is 50% oxygen 

(Z = 8) and 32% silicon (Z = 14) by weight. Higher energy photons scatter within this facility, lose 

energy in each collision, and result in photons of lower energy. Gamma radiation of 2.2 MeV results 

from 1

H (neutron, gamma) 2H interactions caused by neutron radiation scattering (i.e., moderation) 

and absorption in the hydrogen-rich materials in the nuclear components and building materials 

(concrete) (Shleien, Slayback, and Birky 1998). This gamma field should be well-dispersed where 

pits are stored or handled and hydrogenous material is nearby.

Photon radiation in the workplace would have been readily measured at Pantex, with available 

dosimeter technology, during all years of operation. With few exceptions, photon energies in the 

Pantex workplace are all within the 30-250 keV range. An assumption that all photons are in this 

range is a simplifying conservative assumption that is generally claimant-favorable.

6.5.4.3 Neutron Radiation 

There have been three main types of facilities or activities at Pantex with potential for neutron 

exposure to workers: (1) bays and cells, (2) vaults and igloos (storage facilities), and 

(3) transportation. The specific workplace neutron fields for selected types of nuclear weapon 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 27 of 61

1E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0 0.5 1 1.5 2 2.5

Energy (MeV)

MeV/pe

Figure 6-6. MCNP-calculated photon spectra emitted from 238U as excited by 

234mPa beta in 238U spheres. 

238U Metal Bremsstrahlung Photon Energy Spectrum

0

0.000005

0.00001

0.000015

0.00002

0.000025

0.00003

0 0.5 1 1.5 2 2.5

Energy (MeV)

MeV/pe

Figure 6-7. Bremsstrahlung component of calculated spectrum from 238U 

spheres on linear vertical axis. 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 28 of 61

0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.0008

0.0009

0.001

0 0.05 0.1 0.15 0.2

MeV/pe

Energy (MeV)

MCNP Modeled 1-cm dia. 238U Metal Sphere

Bremsstrahlung & Characteristic X-Ray Photons

Figure 6-8. Characteristic X-ray component of calculated spectrum from 238U 

spheres on linear vertical axis. 

components are classified. Unclassified information on neutron spectra from fission and sealed 

plutonium sources is available. Because of differences in moderating materials, these facilities or 

activities generally have two different neutron spectra.

Plutonium pits that are not associated with high explosives are referred to as “bare pits,” although all 

pits are sealed or encapsulated (Shipler 2004). Assembly and disassembly operations that occur in 

cells comprise the only times workers have been exposed to neutrons emanating from bare pits. The 

average energy is higher for unshielded plutonium and beryllium (α,n) interactions than for fission 

neutrons. Figure 6-9 shows examples of unshielded fission and Pu-Be spectra and the respective 

average energy. In the workplace, these spectra are significantly changed through scattering in 

nuclear weapon components, equipment, and building materials. The 809/812 dosimeter system was 

designed and calibrated for neutrons in the Pantex workplaces.

Maximum radiation dose rates occur when workers handle bare pits. The operations often involve 

direct hands-on manipulation where the distance from the surface of the pit to the dosimeter is 

approximately 30 cm. Lead aprons or other shielding has been used to reduce photon dose rates. In 

other assembly or disassembly operations, where high explosives (HE) or other materials surround 

the pit, photon and neutron dose rates decrease significantly, although photon dose rates decrease 

more rapidly with increased shielding.

Assuming that 100% of the neutron doses were delivered by neutrons in the 0.1- to 2-MeV energy 

range is a simplifying conservative assumption that is generally claimant-favorable. Although there 

are neutrons with higher energies (which are more penetrating) at Pantex, the probability of causation 

(PC) for deeper organs, such as the liver, is much larger in the 0.1- to 2-MeV range than in any other 

energy group, offsetting the higher dose at depth for the more energetic energy ranges. Radiation 

fields (beta/photon and neutron) characteristic of Pantex facilities can be generally defined based on 

historical information on processes, locations, operating periods, and radioactive materials in each, as 

listed in Table 6-9.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 29 of 61

Neutron Spectra from Examples in SOURCES-4A

0

0.5

1

1.5

2

2.5

3

3.5

4

0 1 2 3 4 5 6 7 8 9 10 11 12

Energy (MeV)

SF: n/(s cm3); PuBe: n/(s cm2) .

Spontaneous Fission

WG Pu-Be

E(avg)=1.934 MeV

E(avg)=4.66 MeV

Figure 6-9. Unmoderated neutron spectra calculated by SOURCES-4A

(Wilson et al. 1999).

6.5.5

6.5.5.1 Beta/Photon Film Dosimeter Response 

Dosimeter Response to Radiation Fields

The Pantex Plant used film for beta and photon dosimetry from 1952 to 1973 (see Table 6-2). Three 

companies provided dosimetry services during this period; the services and dosimeters were 

essentially the same. The dosimeters provided an open window with little filtration, a lower energy 

window for allowing beta particles and lower energy photons to enter a film area with a plastic filter, 

and a film area with a metal (usually aluminum) filter. The open window enabled measurement of 

beta particles and lower energy photons. The plastic filter enabled measurement of intermediateenergy photons, and the metal filter enabled measurement of higher energy photons (1-cm depth).

The AEC tested film badges provided by Tracerlab (AEC 1955) with exposures to 40-, 70-, and 210-

keV X-rays and 60Co gamma rays, and mixed-energy exposures of all four radiations. The film 

badges generally responded well “with a tendency to interpret most exposures too high.” The overresponse (in the 100- to 200-keV region) tended to yield conservatively high results. This testing, 

combined with the data from Figure 6-2 and the pattern in recorded doses with progressively more 

sophisticated dosimetry systems, leads to the conclusion that photon doses measured at Pantex by 

film badges were reliable. Moreover, photon exposures from 60-keV 241Am photons were not 

underestimated and the total photon dose was probably slightly overestimated because of the overresponse to photons in the 100- to 200-keV energy region.

Table 6-10 summarizes typical beta/photon personnel dosimeter parameters important to Hp(10)

performance in the workplace.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 30 of 61

Table 6-9. Beta, photon, and neutron radiation energies and percentages for Pantex facilities. 

Process/

buildings Description

Operations

Period

Radioactive

material

Radiation

type

Energy 

selection

Percent

(notes)

Bays

Cells

Assembly/

disassembly of 

nuclear weapons

1952-2005 DU Beta >15 keV 100a

Photons 30-250 keV 100b

1958-2005 Tritium Beta <15 keV 100c

1958-2005 Plutonium, HEU Photons 30-250 keV 100

Neutrons 0.1-2 MeV 100d

1958-2005 Thorium Beta >15 keV 100

Photons 30-250 keV 100e

Pit vaults

Igloos

Staging of 

plutonium pits

1958-2005 Plutonium, HEU Photons 30-250 keV 100

Neutrons 0.1-2 MeV 100d

Tritium vault Staging of tritium 

reservoirs

1958-2005 Tritium Beta <15 keV 100c

Transportation Movement of 

weapons

1952-2005 DU, HEU, thorium

Plutonium

Photons 30-250 keV 100b

Neutrons 0.1-2 MeV 100d

Radiography

NDE

Radiographyf 1952-2005 Weapon 

components

Photons 30-250 keV 100b

QA/QC

Cell 8

Pit testing 1958-2005 Plutonium, HEU Photons 30-250 keV 100e

Neutrons 0.1-2 MeV 100d

Warehouse–

Production 

Stores

Packaging 

components

1952-2005 Weapon 

components

Beta >15 keV 100a

Photons 30-250 keV 100b

Neutrons 0.1-2 MeV 100d

1958-2005 Tritium Beta <15 keV 100c

a. Workplace beta radiation has energy greater than 15 keV.

b. Most photons from DU have energies greater than 30 keV; some have energies greater than 250 keV. If shielding 

materials are present, fewer photons are in the categories less than 30 keV, or greater than 250 keV. The assumption 

that 100% of the photons from DU are between 30 and 250 keV is recommended as a simplifying conservative

assumption that is generally claimant-favorable. 

c. Beta particles from tritium are classified in the “less-than-15-keV” category.

d. The energy of neutrons in the workplace is predominately in one of two ranges: Between 0.1 and 2 MeV or between 2 

and 20 MeV. In some cases, with significant moderating materials, some neutrons are less than 0.1 MeV. However, 

assuming that 100% of the neutrons are between 0.1 and 2 MeV is a simplifying, conservative assumption that is 

generally claimant-favorable. 

e. Four weapons programs included thorium components assembled during the 1960s and disassembled during the 

1990s. Beginning in about 1960, there was handling of recently purified thorium that was not in secular equilibrium with 

progeny nuclides and had emission of predominantly lower energy photons. The assumption that 100% of these 

photons were between 30 and 250 keV is recommended. Although the thorium components were in secular equilibrium 

during the disassembly period and the 2.6-MeV photons from 208Tl are dominant, this represented a small fraction of the 

total worker photon dose. The assumption that the photon energy was between 30 and 250 keV is conservative. 

f. Radiography involved a low potential for significant neutron exposure.

6.5.5.2 Beta/Photon TLD Dosimeter Response

The Pantex external dosimetry program has used Panasonic TLD systems for personnel dosimetry, 

with the exception of the in-house period (1973 to 1980) when the Plant implemented the Pantex 

Personnel Dosimeter (PPD) based on the Victoreen 2800 system. The first PPDs had open windows 

for beta and lower energy photons (7 mg/cm2

) and a window of 290 mg/cm2 Al. In 1977, Pantex 

implemented an improved six-element TLD program, which had several filters up to a density 

thickness of about 1,000 mg/cm2 (i.e., nearly equivalent to 1-cm depth in tissue) for elements of the 

dosimeter used to measure the whole-body (deep) dose, Hp(10) (see Figure 6-3).

The Panasonic UD-802 system used at Pantex was tested by Roberson et al. (1983) and found to 

respond very well to 137Cs photons, to overestimate dose from 60-keV 241Am photons, and to 

underestimate the dose from fast neutrons. Adjustments were made to the calibrations and algorithm, 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 31 of 61

Table 6-10. Typical workplace beta/gamma dosimeter Hp(10) performance.

a

Parameter Description Potential workplace biasb

Exposure 

geometry

Pantex dosimeter system calibrated using 

AP laboratory irradiations.

Dose of record probably too low because 

dosimeter response is lower at angles other 

than AP. Effect is highly dependent on 

radiation type and energy.

Energy 

response

Pantex film deep dose response is too low 

for photon energies less than about 35 keV 

and too high for photon energies between 

35 and 200 keV (see Figure 6-2). 

Positive bias in dose of record is expected, 

because photon energy is typically > 35 keV in 

workplaces and performance testing shows 

positive bias.

Highly 

divergent 

fields

Dosimeter worn at collar could 

underestimate deep dose at waist.

Dose of record could be too low for workers 

performing waist-level uranium handling jobs.

Mixed fields Pantex dosimeters respond to beta and 

photon radiation.

Filtration of about 1,000 mg/cm2 over dosimeter 

region used to measure deep dose minimizes 

dosimeter response to beta radiation.

Missed dose Doses less than MDL recorded as zero 

dose.

Dose of record probably too low. Impact of 

missed dose would be greatest in earlier years 

because of dosimeter exchange frequency and 

film dosimeter with higher MDLs.

Environmental 

effects

Workplace environment (heat, humidity, 

etc.) fades dosimeter signal.

Dose of record is probably too low.

a. Judgment based on Pantex Plant dosimeter response characteristics and workplace radiation fields (Pantex 2002).

b. Dose of record compared to Hp(10). 

and the UD-802 system was accredited by DOELAP in 1993 for all beta and photon testing

categories. The Panasonic UD-809/UD-812 dosimeter system was accredited by DOELAP in 1993 

for all testing categories applicable to Pantex.

The dosimeter testing described in Section 6.4.5.1 (AEC 1955) and above (Roberson et al. 1983) and 

the DOELAP accreditations show widespread technical capabilities to measure photon doses reliably. 

The intercomparison studies provide evidence that film badges and TLDs responded adequately, 

during the entire 1952-to-present period at Pantex, to the 60-keV photons from 241Am and the film 

badges probably over-responded to photons between 100 and 200 keV. Based on this information, 

the photon dose of record is likely to be claimant-favorable, assuming the dose of record is adjusted 

upward for missed dose (i.e., recorded zero dose when less than MDL).

The exposure orientation of workers in the various Pantex facilities is primarily AP, and dosimeters 

are normally worn on the front of the torso. An assumption that exposure orientations are 100% AP is 

a simplifying and conservative assumption that is generally claimant-favorable. However, other 

exposure orientations (ROT and ISO) do occur for a limited number of workers in some work 

situations. If the claim file provides information to suggest a geometry for which the dosimeter would 

receive appreciably less dose than the region of interest, e.g. work at a bench top, then a correction 

factor should be applied in accordance with the guidance of OCAS-TIB-0010 (OCAS 2005).

6.5.5.3 Neutron Dosimeter Response

Tracerlab provided NTA film dosimetry service from 1952 through April 1963 (Tracerlab 1963). 

According to routine dose reports, the film was sensitive to neutrons with energies from 1 to 10 MeV. 

The stated MRD value of the film was 15 mrem for neutrons. Between April 1963 and September 

1964, Eberline provided similar film badge services (Ashton 2003); the stated MRD was 10 mrem. 

From October 1964 through 1976, Landauer provided similar services (Adams 2003). MRDs were 20 

and 10 mrem, respectively, for fast and thermal neutrons.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 32 of 61

Based on current knowledge of the general characteristics and response of NTA film, and the 

expected under-response in workplace conditions with significant scattering of neutrons, use of the 

film for personnel neutron dose monitoring can have the biases listed in Table 6-11. Testing of NTA 

film clearly showed that neutrons with energies below 500 keV were not measurable, and overall 

neutron doses were probably underestimated (ORAUT 2005a).

Table 6-11. Typical workplace neutron dosimeter performance (Pantex 2002).

a

Parameter Description Potential workplace biasb

Workplace neutron 

energy spectra

NTA dosimeter response decreases and 

TLND response increases with 

decreasing neutron energy. 

Depends on workplace neutron spectra. 

NTA dose of record probably too low 

because of high 500-keV energy 

threshold for detection of neutrons.

Exposure geometry NTA dosimeter response increases with 

increasing exposure angle and TLND 

response decreases with increasing 

exposure angle.

NTA dose of record probably too high 

because dosimeter response is higher at 

angles other than AP. TLD dose of 

record is lower at angles other than AP. 

Effect is highly dependent on neutron 

energy.

Missed dose Doses less than MDL recorded as zero 

dose.

Dose of record probably too low. Impact 

of missed dose is greatest in earlier 

years because of higher MDLs of neutron 

dosimeters. 

Environmental effects Workplace environment (heat, humidity, 

etc.) fades dosimeter signal.

Dose of record probably too low.

a. Judgment based on Pantex Plant dosimeter response characteristics.

b. Dose of record compared to Hp(10).

The six-element, in-house TLD system used from 1977 to 1980 responded well to thermal neutrons 

but under-responded to neutrons with energies above about 10 keV (PNL 1977). Thus, this system 

did not measure a significant fraction of the neutrons in the Pantex workplace.

The response of the Panasonic UD-802 TLD to thermal and fast neutron radiation was measured by 

Roberson et al. (1983) using a bare and a moderated 252Cf source. These measurements showed 

that the UD-802 significantly under-responded to fast neutrons. Therefore, neutron doses measured 

by the UD-802 between 1980 and 1993 are likely to be underestimated.

In summary, all neutron dosimeters used at Pantex prior to 1994 underestimated actual neutron 

doses. The neutron doses of record are unreliable and should not be used by dose reconstructors. 

DOELAP accredited the Panasonic UD-809/UD-812 TLD system in 1993 for all neutron categories 

applicable at Pantex. Neutron doses measured at Pantex since 1994 are reliable and dose 

reconstructors should use the dose of record.

6.5.5.4 Neutron-to-Photon Dose Ratios 

There have been many measurements of neutron and photon spectra and dose ratios for specific 

facilities, weapon components, and operations at the Pantex Plant. However, details of this 

information are classified other than the general statement that the instrument-measured dose ratios 

are less than the dosimeter-measured ratios. Assessments of neutron-to-photon dose ratios have 

been based on general information and measurements conducted at the Plant and at similar facilities 

and operations elsewhere in the DOE complex. Table 6-1 lists collective total, photon, and neutron 

doses as well as the average total dose to monitored workers for the entire period of operation. The 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 33 of 61

annual average percentages of the total dose due to neutrons for the periods of operation with 

positive recorded neutron dose from 1960 through 1993 and from 1994 through 2004 (with the 

809/812 accredited system) from Table 6-1 are 19% and 26%, respectively. However, these ratios 

are not directly applicable to claimants because they are derived from collective doses. They do not 

take into account the “diluting” effect of numerous workers who had photon doses only. 

Neutron-to-photon dose ratios were calculated from Pantex post-1993 dosimeter data. Data were

provided by Pantex (Prather 2004) on all photon and neutron recorded doses (measured by the 

809/812 TLDs) from 1993 to 2003. These data were analyzed by Strom (2004) and the neutron-tophoton dose ratios were determined where the neutron and photon doses were greater than 

50 mrem/yr. A log-probability plot of the grouped neutron-to-photon dose ratios is shown in Figure 

6-10. The median ratio is 0.7915 (rounded to 0.8) and the 95th-percentile ratio from this distribution is

1.603 (rounded to 1.6). These data represent radiation workers who were exposed to both photons 

and neutrons emitted from nuclear weapon components, primarily bare pits. During operations with 

bare pits, radiation workers routinely wear lead aprons that are very effective (greater than 99%) in

shielding the workers from lower energy photons, including 60-keV photons from 241Am (Shleiein and 

Terpilak 1984). Procedures in use during this period require the wearing of lead aprons, and their use 

has been enforced by management. Thus, the dosimeter data for 1993-2003 includes very little if any 

contribution from lower energy (i.e., 241Am) photons. 

1993-2003 Pantex Neutron and Gamma Doses (>/= 50 mrem)

0.1

1

10

-3 -2 -1 0 1 2 3

Standard Normal Deviate, z

Ratio (neutron/gamma)

Data

Finney

Uniform

Logs

Figure 6-10. Log-probability plot of grouped neutron-to-photon dose ratios. 

To reliably apply a 95th-percentile neutron-to-photon dose ratio of 1.6 to earlier periods, such as 

assembly operations in the 1960s, it must be shown that even higher ratios did not exist. Assembly 

operations in this period would have involved new pits with very little 241Am ingrowth (DOE 1998), and 

lead aprons probably were not routinely used. The neutron and photon fields around new pits would 

have been very similar to the fields experienced between 1993 and 2003 when radiation workers did 

wear lead aprons that attenuated essentially all lower energy photons. 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 34 of 61

During other periods when disassembly of aged weapons was conducted, the contribution of 241Am 

photons (Traub, Sherpelz, and Taulbee 2005) to the total photon dose would have been larger and 

lead aprons might not have been worn. Under these conditions, the photon doses would have been 

higher and the neutron-to-photon dose ratio would have been lower than that experienced with new 

pits. If lead aprons were worn, the ratio of neutron-to-photon dose would have been similar to those 

experienced during the 1993-2003 period. 

Although the annual neutron-to-photon dose ratios have varied over the decades, the pre-1993 

annual neutron-to-photon dose ratio should be bounded by the 95th-percentile value of 1.6 derived 

from the analysis of data from DOELAP-accredited dosimeters, with few exceptions. The neutron-tophoton dose ratio of 1.6 provides a claimant-favorable method for reconstructing neutron doses over a 

worker’s entire career at Pantex. For the years when the measured neutron and photon dose 

exceeds a ratio of 1.6, the higher measured dose ratios should be used. For comparison, neutron-tophoton dose ratios determined at Los Alamos National Laboratory (ORAUT 2005b) and Rocky Flats

(ORAUT 2004b) for similar exposure scenarios are 1.4 to 1.8 and 1.79, respectively.

The definition of the 95th-percentile value means that 5% of the data exceeds the 95th-percentile

value. In fact, an examination of the claimant data revealed that dosimetry records for four claimants 

included neutron-to-photon dose ratios greater than 1.6 in some years. In these few cases, the actual 

recorded neutron and photon doses (and higher neutron-to-photon dose ratios) should be used to 

calculate the neutron dose in the respective years. In all other years when the neutron-to-photon 

dose ratio is less than 1.6, a claimant-favorable neutron dose should be calculated by multiplying the 

photon dose by 1.6.

Neutron doses at Pantex have been monitored reliably with the Panasonic 809/812 dosimeter since

late 1993; however, neutron dosimeters used at Pantex prior to 809/812 TLDs generally 

underestimated neutron doses to some degree. The neutron doses of record measured prior to the 

809/812 TLDs are unreliable and should not be used by dose reconstructors, unless the neutron-tophoton dose ratio exceeds 1.6. All photon doses of record (with appropriate corrections for lead 

apron use and dosimeter response uncertainty) were reliably detected and can be used with a 

neutron-to-photon dose ratio to calculate claimant-favorable neutron doses for years prior to 1994.

Pantex radiation workers have accumulated photon doses from a variety of workplace radiation 

sources, including full weapon assemblies, partially shielded pits, and bare pits. Workplace 

measurements have shown that most neutron doses were received during the handling of bare pits. 

The application of a neutron-to-photon dose ratio of 1.6 to the photon dose of radiation workers 

assumes that all photon dose received was accompanied by a conservatively high estimate of the 

neutron dose associated with handling bare pits. 

Unmonitored workers at Pantex, who by today’s standards would be monitored, might have been 

exposed to low levels of photon and neutron doses. Photon doses to unmonitored workers can be 

estimated from the median photon doses for radiation workers listed in Table 6-17. A neutron dose 

can be derived from the median value of neutron-to-photon dose ratios determined by Strom (2004). 

This value of 0.8 applied to the median photon dose for radiation workers will provide a claimantfavorable estimate of the calculated neutron dose to unmonitored workers. The sum of the median 

photon dose and the calculated median neutron dose will provide a claimant-favorable total dose 

estimate for unmonitored workers.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 35 of 61

6.5.5.5 Neutron Dose Weighting Factor

An adjustment to the neutron dose is necessary to account for the change in neutron quality factors 

between historic and current scientific guidance, as discussed in NIOSH (2002). At Pantex, TLNDs 

were calibrated with measurements based on fluence-to-dose conversion factors and quality factors 

similar to those from International Commission on Radiological Protection Publication 21 (ICRP 1973) 

and National Council on Radiological Protection and Measurements Report 38 (NCRP 1971). These 

quality factors are point-wise data because they were calculated for a broad parallel beam of 

monoenergetic neutrons incident on a 30-cm-diameter cylindrical phantom representing the torso. 

Figure 6-11 compares NCRP (1971) quality factors to those used in Pacific Northwest Laboratory 

measurements at the Y-12 Plant (Soldat et al. 1990). To convert from NCRP (1971) quality factors to 

ICRP (1991) radiation weighting factors, a curve was fit that described the quality factors as a function 

of neutron energy. A group average quality factor was calculated, as shown in Figure 6-11, for each 

neutron energy group used to define the radiation weighting factors in ICRP (1991). Table 6-12 

summarizes the group-averaged NCRP (1971) quality factors used in the dose reconstruction. In

addition, this table compares these quality factors with dosimetry guidelines from the First Tripartite 

Conference in 1949 (Warren et al. 1949; Fix, Gilbert, and Baumgartner 1994).

Figure 6-11. Comparison of neutron quality factors used in PNL 

neutron spectrum measurements and neutron quality factors 

from NCRP (1971), shown as point-wise data and grouped 

averaged data over four neutron energy groups used in dose 

reconstruction for Y-12 Plant workers. 

Table 6-12 lists average quality factors for the four energy groups used to input dose to the Interactive 

RadioEpidemiological Program (IREP) computer code, which encompass potential neutron 

exposures. The neutron dose equivalent correction factor for each energy group, Cf(En), can be 

calculated by the use of the following equation:

( ) ( )

( ) ( ) nf

n

nR

nf ED

EQ

Ew EC = ×

avg

10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100 10+1

Neutron Energy (MeV)

0

5

10

15

Neutron Quality Factor 

PNL Measurements

NCRP 38: Point-wise data

NCRP 38: Group averaged data
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 36 of 61

where:

Df(En) = the dose fraction for the specific neutron energy group of interest

Qavg(En) = the group average NCRP (1971) neutron quality factor for that specific 

group

wR(En) = the ICRP (1991) neutron weighting factor for that specific group

Table 6-12. Neutron quality factor or weighting factor. 

Neutron energy

Historical 

dosimetry 

guidelinea

NCRP (1971) group 

averaged quality factor 

Qavg(En)

b 

ICRP (1991) neutron 

weighting factor

wR(En)

Correction factor

ICRP (1991)/NCRP (1971)

wR(En)/Qavg(En)

Thermal 5 2.35 5 2.13

0.5 eV–10 keV

10

10 keV–100 keV 5.38 10 1.86

100 keV–2 MeV 10.49 20 1.91

2 MeV–14 MeV 7.56 10 1.32

14 MeV–60 MeV Not applicable 5

a. First Tripartite Conference in 1949 (Warren et al. 1949).

b. ORAUT (2003c).

Using this method, the dose equivalent of record is a combination of all neutron energies. To 

calculate the neutron dose input to IREP, the neutron dose of record must be separated into neutron 

energy groups. Table 6-9 summarizes the dose fractions by neutron energy group for the neutron 

exposure areas at Pantex. Dose reconstructors should apply the correction to recorded, unmonitored, 

and missed neutron dose prior to 1994 using the ICRP (1991) correction factor from Table 6-13. 

Table 6-13. Neutron dose energies, percentages, and associated ICRP (1991) correction factors. 

Process

Description/

buildings

Neutron energy

(MeV)

Default dose 

fractiona (%)

ICRP (1991)/NCRP (1971)

correction factor

Nuclear weapons 

component assembly

Neutron exposure associated with weapons assembly and disassembly activities

0.1 – 2 MeV 100 1.91

a. From Table 6-9; assuming all neutron energies are between 0.1 and 2 MeV is claimant-favorable.

6.5.5.6 Use of Lead Aprons

Lead aprons were available to early radiography workers at Pantex. However, because radiography 

machines were inside shielded facilities, workers did not use the aprons routinely. Monitored radiation 

doses for radiographers in the early years were usually zero. In the late 1950s, when work with pits 

began, there were higher measured photon radiation doses and workers began wearing lead aprons. 

However, the use of lead aprons was not included in procedures until the mid-1980s. Present 

instructions for workers wearing aprons are to wear whole-body dosimeters “under the lead apron to 

make the best estimate of the delivered dose equivalent to the major portion of the body” (Pantex 

2002). However, there was no enforcement to ensure that dosimeters were worn under the apron.

Three types of lead aprons have been worn by Pantex workers over the years. Some covered only 

the front of a worker’s body. Some covered the front and back but not the worker’s sides. In 1995, 

the use of aprons that wrap entirely around the body began, but use of the other two types continued. 

Figure 6-12 shows the areas of the body typically covered by a lead apron. 

In 1995, a series of studies were performed at Pantex on the effects of apron use on dosimeter 

readings (Passmore 1995a,b,c). The studies were done by putting a dosimeter on the front of a

phantom positioned in an aisle way near the middle of an igloo in which plutonium pits were stored in 

cans. The photon spectrum in this isotropic field was “hardened” by the steel cans and it included the 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 37 of 61

2.2-MeV photons generated when a thermal neutron is 

captured by hydrogen. This exposure scenario was chosen to 

represent the radiation fields where lead aprons were least 

effective in reducing photon dose. Dose measurements were 

made with no apron and with the dosimeter under and over 

each type of apron. The results summarized in Table 6-14 are 

the percent reduction when wearing an apron in comparison 

with the measurement with no apron. A surprising result was 

that placing dosimeters outside the apron indicated a reduction

in the dosimeter readings. One possible explanation for this 

effect is that some radiation getting to the dosimeter on the 

phantom came through the back of the phantom and was 

reduced by the shielding in the apron that it encountered before 

it would have reached the dosimeter. 

Production Technicians, Material Handlers, Radiography 

Technicians, and Quality Control Technicians routinely wore 

aprons during work in the 1980s and 1990s, and perhaps 

earlier. More recently, the use of lead aprons has been 

required by procedure and enforced by management. 

Production Technicians and Material Handlers in facilities 

containing plutonium generally wore aprons. Workers in other 

job classifications generally did not wear aprons.

An adjustment factor was derived from the largest relevant 

dose reduction data in Table 6-14 and applied to the location of cancer sites listed in Table 6-15. If 

the cancer site is in an area protected by a lead apron, an adjustment factor of 1 applies to a worker 

who wore the dosimeter under the apron. 

Table 6-14. Percent reduction in measured photon dose provided by lead 

aprons. 

Apron type

Apron thickness

mm lead equivalent

Dosimeter location a

Deep dose Shallow dose

Under On top Under On top

Front only 0.50 30 13 29 12

Front and back 0.50 35 8 23 7

Wrap-around 0.25 27 7 19 8

a. In relation to dosimeter response with no apron.

If a worker received dose while not wearing an apron, applying this factor of 1 to the measured dose 

is still claimant-favorable. If the cancer site is in an area not protected by a lead apron, an adjustment 

factor of 1.5 is applied, regardless of the location of the dosimeter.

6.6 ANALYSIS OF CLAIMS FILED BY PANTEX WORKERS

An analysis of job titles, worker classifications, and external dose parameters reported in Pantex 

claims was done to better determine dose reconstruction recommendations. There are three primary 

sources of information in each claim that provide information of interest used to reconstruct external 

dose: (1) DOL claim documentation, (2) DOE medical X-ray, dosimetry, and incident archive records, 

and (3) records of interviews with claimant and coworkers, as available. This information is used to 

Figure 6-12. Body areas covered 

by lead apron (skeletal figure 

from Memmler and Rada 1970).
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 38 of 61

identify the employment period, job title and work activities, coworkers, supervisors, etc., for use in 

dose reconstruction. Analysis of the historical radiation monitoring and dose documentation for the 

Table 6-15. Cancer sites protected or unprotected by apron (42 CFR Part 81)

ICD-9 code Cancer description Cancer sitea

140 Malignant neoplasm of lip U

141 Malignant neoplasm of tongue U 

142 Malignant neoplasm of major salivary glands U

143 Malignant neoplasm of gum U

144 Malignant neoplasm of floor of mouth U

145 Malignant neoplasm of other and unspecified parts of mouth U

146 Malignant neoplasm of oropharynx U

147 Malignant neoplasm of nasopharynx U

148 Malignant neoplasm of hypopharynx U

149 Malignant neoplasm of other and ill-defined sites within lip, oral cavity, and pharynx U

150 Malignant neoplasm of esophagus U

151 Malignant neoplasm of stomach P 

152 Malignant neoplasm of small intestine, including duodenum P

153 Malignant neoplasm of colon P

154 Malignant neoplasm of rectum, rectosigmoid junction, and anus P 

155 Malignant neoplasm of liver and intrahepatic bile ducts P

156 Malignant neoplasm of gall bladder and extrahepatic bile ducts P

157 Malignant neoplasm of pancreas P

158 Malignant neoplasm of retroperitoneum and peritoneum P

159 Malignant neoplasm of other and ill-defined sites within digestive organs and peritoneum P

160 Malignant neoplasm of nasal cavities, middle ear, and accessory sinuses P

161 Malignant neoplasm of larynx P

162 Malignant neoplasm of trachea, bronchus, and lung P

163 Malignant neoplasm of pleura P

164 Malignant neoplasm of thymus, heart, and mediastinum P 

165 Malignant neoplasm of other and ill-defined sites within respiratory system and intrathoracic organs P

170 Malignant neoplasm of bone and articular cartilage F

171 Malignant neoplasm of connective and other soft tissue F

172 Malignant melanoma of skin F

173 Other malignant neoplasms of skin F

174 Malignant neoplasm of female breast P

175 Malignant neoplasm of male breast P 

179 Malignant neoplasm of uterus, part unspecified P

180 Malignant neoplasm of cervix uteri P

181 Malignant neoplasm of placenta P 

182 Malignant neoplasm of body of uterus P

183 Malignant neoplasm of ovary and other uterine adnexa P

184 Malignant neoplasm of other and unspecified female genital organs P

185 Malignant neoplasm of prostate P

186 Malignant neoplasm of testis P

187 Malignant neoplasm of penis and other male genital organs P

188 Malignant neoplasm of urinary bladder P 

189 Malignant neoplasm of kidney and other unspecified urinary organs P

190 Malignant neoplasm of eye U

191 Malignant neoplasm of brain U 

192 Malignant neoplasm of other and unspecified parts of nervous system F

193 Malignant neoplasm of thyroid gland U

194 Malignant neoplasm of other endocrine glands and related structures P 

195 Malignant neoplasm of other and ill-defined sites F

196 Secondary and unspecified malignant neoplasm of lymph nodes P

197 Secondary malignant neoplasm of respiratory and digestive organs P

198 Secondary malignant neoplasm of other tissue and organs F

199 Malignant neoplasm without specification of site U

200 Lymphosarcoma and reticulosarcoma U

201 Hodgkin’s disease U 

202 Other malignant neoplasms of lymphoid and histiocytic tissue U

203 Multiple myeloma and other immunoproliferative neoplasms U

204 Lymphoid leukemia U 

205 Myeloid leukemia U

206 Monocytic leukemia U
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 39 of 61

207 Other specified leukemia U

208 Leukemia of unspecified cell type U

a. F = Apron covered from shoulders to below the knee but not the arms; P = Protected by apron; U = Unprotected by apron. Dose 

reconstructors should use Figure 6-11 and knowledge of cancer site to determine U or P.

respective claims provides insight into Pantex dosimetry practices, such as assignment of dosimeters, 

exchange periods, and dose recording levels. 

For purposes of dose reconstruction, it is recognized that while “average” and “routine” activities are 

important and probably represent most exposure scenarios, there could be unusual circumstances in 

some claims that require special evaluation.

6.6.1

A sample of 316 claims filed with the U.S. Department of Labor (DOL) by Pantex workers was 

analyzed to examine trends in the data. These claims were assembled in a database with one line of 

data for each year of employment for each claimant. Information for claimants that had more than 

one job title in a given year is presented in extra lines. Overall, a total of 6,396 lines of data were 

assembled for the 316 claims. Claimants reported a total of 692 different job titles or job codes. The 

average period of employment for claimants was 20.2 years. The records (with and without a 

recorded radiation dose) were examined for each year for the respective claims. Figure 6-13 

illustrates the frequency of claims in each year. It is evident that the very early years have fewer 

claims. The peak in the number of claims for a year occurs in the late 1970s to early 1980s. 

Years with a Claim

Active Claims

0

50

100

150

200

250

1940 1950 1960 1970 1980 1990 2000 2010

Year

Frequency

Active Claims

Figure 6-13. Frequency distribution of claims that encompass the respective years. 

6.6.2

Analysis of the available claim documentation showed a wide spectrum of job titles and job 

descriptions for the claimants. Many descriptive occupational titles, including Pantex-specific 

numerical identifiers for positions, are found in the respective claim documentation. Nearly 700 

different job titles were identified for the 316 claimants during the years of employment. Similar job 

titles were grouped into the assigned job titles listed in Table 6-16, and collective photon and neutron 

doses were tabulated to examine the dose distribution with respect to job titles. This analysis 

confirmed that most of the collective dose was received by assembly, inspection, and warehouse 

Collective Dose by Job Title
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 40 of 61

operators, who were generally designated as radiation workers. Another interesting feature of these

data is the nearly equal collective photon and neutron doses recorded for warehouse operators, which 

is not evident for any other group of job titles. Detailed analysis of these data revealed that most of 

the collective neutron dose to warehouse operators was received by fewer than 10 workers in 1960 

and 1979. 

Table 6-16. General categories of job titles for Pantex claimants and recorded 

doses. 

Assigned job titles

Collective photon dose

person-mrem

Collective neutron dose 

person-mrem

Collective dose % of total Collective dose % of total

Assembly/Production 103,197 61.8 17,248 44.9

Clerk 2,460 1.5 2,390 6.2

Disability 330 0.2 0.0

Engineering 3,837 2.3 237 0.6

Explosives Handler 490 0.3 20 0.1

Inspection 19,567 11.7 3,431 8.9

Management 2,625 1.6 70 0.2

Material Hander 1,060 0.6 370 1.0

Metrology 3,971 2.4 405 1.1

Quality 9,430 5.6 2,150 5.6

Radiation Safety 345 0.2 0.0

Security 910 0.5 0.0

Support Services 2,260 1.4 50 0.1

Tradeworker 4,431 2.7 650 1.7

Warehouse Operator 12,205 7.3 11,393 29.7

Total 167,118 38,414

6.6.3

Radiation doses were examined for these claimants for years prior to March 1989, when monitoring 

began for all employees. A total of 1,754 lines of data showed recorded doses (including zeros) for 

monitored workers representing about 27% of the database. A total of 3,577 lines of data had no 

recorded doses (blank) representing unmonitored workers, which comprised about 56% of the 

database. The remaining 1,065 lines of data represent workers who were monitored after March 

1989 and account for about 17% of the database. Overall, about 44% of the records contained 

results (including zeroes) of dose monitoring (i.e., a total of 2,819 lines calculated as the sum of 1,754 

and 1,065 lines of data, respectively, from before and after March 1989). Further analysis of 

monitored claimant data (2,819 lines) showed that about 48% had non-zero recorded doses. The 

recorded photon and neutron collective dose for the Pantex claims is presented in Figure 6-14. 

Based on this information, the earliest recorded photon dose occurred in 1958 and the earliest 

neutron dose in 1960. The relatively high collective neutron dose in 1960 is interesting because it is 

higher than the recorded collective photon dose. The majority of the recorded neutron dose in 1960 

was recorded for just five workers (three identified as warehouse operators, one assembler, and one 

inspection foreman). One possible explanation is that there could have been an effort to correct for 

the known underestimation of neutron dose as measured by NTA films.

Analysis of Recorded Doses

An attempt was made to associate group job titles with job activities that were expected to involve 

radiation exposure. However, meaningful analysis was not feasible with the data available because 

claimant job titles changed significantly over the years and many claimants had several titles during 

their employment at Pantex. It is evident that the respective claimants represent a broad spectrum of 

work functions at Pantex. 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 41 of 61

An examination of the worker neutron and photon dose data revealed that the 95th-percentile value of 

the ratio was 1.3 and that only four workers received an annual photon and neutron dose for which 

Pantex Claim Dose Data

0

2000

4000

6000

8000

10000

12000

14000

16000

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Year

Collective Dose, person-mrem

Gamma

Neutron

Figure 6-14. Distribution of annual photon and neutron dose for Pantex claims. 

the neutron-to-photon dose ratio was greater than 1.6 (see Section 6.4.5.4). This higher ratio was 

typically associated with a relatively low (i.e., less than 100 mrem) annual photon dose, so there is 

greater uncertainty in the analysis. The workers were however associated with the Pantex job 

categories (i.e., inspector and warehouse operator) that typically showed the highest recorded doses. 

For these workers with higher neutron-to-photon dose ratios, consideration of potential unique 

workplace factors is recommended in cases of best-estimate dose reconstruction as follows:

• The higher recorded neutron dose should be used instead of the lower calculated neutron 

dose based on the 1.6 factor (the measured dose is used any time it is higher than a 

calculated value).

• Details of the claim file should be examined to determine if there are unique job activities or 

exposure geometries that could explain the higher measured neutron-to-photon dose ratio. 

• Consideration should be given in cases of potential nonuniformity in the workplace radiation 

field to follow the guidance of the latest revision of OCAS-TIB-0010 (NIOSH 2005) to assign a 

correction factor based on the benchtop operations typical of some work activities at Pantex. 

These considerations are similar to the considerations for glovebox workers. In these cases it 

is recommended that the correction factors provided in OCAS-TIB-0010 be used to 

compensate for the greater uncertainty associated with these claims.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 42 of 61

6.7 RECOMMENDATIONS FOR PANTEX WORKER EXTERNAL DOSE 

RECONSTRUCTION 

Dose reconstruction for Pantex workers is based on the foregoing information, which requires 

assessment of additional dose to be added to the dose of record from four primary causes as follows:

• Dose to unmonitored workers before the routine use of personnel dosimeters by all workers

• Adjustments to reported photon dose associated with the use of protective lead aprons

• Missed dose for monitored workers for low dose results [less than MDL of the personnel 

dosimeter]

• Unmeasured neutron dose to monitored and unmonitored workers

The application of the foregoing information and the following recommendations can be guided by the 

flowcharts in Figures 6-15 and 6-16. Dose reconstructors should consider the dose of record 

accurate for photon and neutron doses for all workers from January 1994 to the present.

6.7.1

Figure 6-5 implies there is comparatively little collective measured dose, particularly before about 

1960. This occurred because there was limited potential for exposure and few workers were 

monitored. Figure 6-17 shows a statistical analysis of the history of Pantex recorded gamma doses in 

a lognormal probability plot. Table 6-17 summarizes the respective lognormal probability statistical 

parameters for the period from 1952 to 2000 for Pantex annual dose results that are equal to or

exceed a gamma dose of 30 mrem. It is recommended that dose reconstructors assign a claimantfavorable dose to an unmonitored worker, who would otherwise be monitored by today’s standards,

equal to the median (i.e., geometric mean) dose measured for monitored workers for each year of 

employment. This is claimant-favorable because unmonitored workers are expected to be lower 

exposed workers since Pantex practice was to monitor all radiation workers prior to March 1989. For 

years before 1959, when no measured gamma dose equal to or greater than 30 mrem was measured, 

use the median dose for 1960 for each year of employment.

Unmonitored External Dose

There should not, typically, be a significant neutron exposure to unmonitored workers. However for 

an unmonitored worker with some evidence of potential neutron exposure, neutron doses can be 

conservatively estimated from the median photon doses for radiation workers listed in Table 6-17 by 

applying a median neutron-to-photon dose ratio determined by Strom (2004). This median value 

applied to the median photon dose for radiation workers will yield a claimant-favorable assigned 

neutron dose to unmonitored workers. 

6.7.2

Adjustment to dose for use of protective lead aprons depends on the location of the cancer site as 

determined from Figure 6-12. The aprons covered the body from the shoulders to below the knee, but 

not the arms. Figures 6-15 and 6-16 illustrate the logic for applying adjustments. If the cancer site is 

under the lead apron, there is no adjustment factor (or the adjustment factor is 1.0) because a 

dosimeter under the apron will reasonably measure a dose to the cancer site. If the cancer site is in 

an area not protected by an apron, and for which the dosimeter measured dose might be too low, the 

recommended adjustment factor is 1.5, as described in Section 6.3.5.6.

Adjustment for Protective Lead Aprons
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 43 of 61

6.7.3

Missed dose occurs when the dose of record is zero because the dosimeter response was less than 

the MDL or there is no dose of record for an assigned badge for a monitoring period. This kind of 

missed dose is most important for earlier years when MDLs were higher and dosimeter exchange was 

more frequent. Dose reconstructors should follow NIOSH (2002) guidance and use data in 

Missed External Dose for Monitored Workers
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 44 of 61

Figure 6-15. Dose reconstruction flowchart for cancer site not protected by a lead apron. 

Unmonitored Worker Monitored Worker

Tabulate median photon dose for each year 

prior to 1989 from Table 6-17. For years 

since 1989, follow the monitored worker flow 

chart steps.

Tabulate photon dose of record for each 

year. Tabulate neutron dose of record for 

each year since 1994.

Multiply by 1.5 (lead apron adjustment 

factor) and assign this as the claimantfavorable photon dose

Multiply photon doses by dosimeter 

response uncertainty correction factor Multiply photon doses by dosimeter a

response uncertainty correction factora 

As appropriate, assign neutron dose by 

multiplying claimant-favorable photon dose 

by 0.8b

. 

Add adjustments for missed and zero doses

Multiply by 1.5 (lead apron adjustment 

factor) and assign this as the claimantfavorable photon dose

Cancer Area NOT 

Protected by Apron

a. Uncertainties and correction factors are ±30% and 1.3 for film badges, ±20% and 1.2 for TLD prior to 

1994, and ±10% and 1.1 for TLDs after DOELAP accreditation, respectively.

b. Median neutron-to-photon dose ratio. 

c. ICRP 1990 neutron weighting factor adjustment for neutron energies 0.1- 2 MeV.

Note: Photon and neutron organ dose conversion factors are not included in this flow chart and must be 

applied separately.

Adjust neutron dose for ICRP-60 

weighting factor by multiplying by 

1.91c

As appropriate, assign neutron dose equal 

to photon dose multiplied by 1.6 for years 

prior to 1994. Use adjusted neutron dose of 

record for years since 1994. 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 45 of 61

Figure 6-16. Dose reconstruction flowchart for cancer site protected by a lead apron. 

Cancer Area 

Protected by Apron

Unmonitored Worker Monitored Worker

Tabulate median photon dose for each year 

prior to 1989 from Table 6-17. For years 

since 1989, follow the monitored worker flow 

chart steps.

Tabulate photon dose of record for each 

year. Tabulate neutron dose of record for 

each year since 1994.

Multiply recorded doses by dosimeter 

response uncertainty correction factor a

Multiply photon dose by dosimeter response 

uncertainty correction factor a

As appropriate, assign neutron dose by 

multiplying claimant-favorable photon dose 

by 0.8 b

. As appropriate, assign neutron dose equal 

to photon dose multiplied by 1.6 for years 

prior to 1994. Use adjusted neutron dose 

of record for years since 1994. 

Add adjustments for missed and zero 

doses

a. Uncertainties and correction factors are ±30% and 1.3 for film badges, ±20% and 1.2 for TLD prior to 

1994, and ±10% and 1.1 for TLDs after DOELAP accreditation, respectively.

b. Median neutron-to-photon dose ratio. 

c. ICRP 1990 neutron weighting factor adjustment for neutron energies 0.1- 2 MeV.

Note: Photon and neutron organ dose conversion factors are not included in this flow chart and must be 

applied separately.

Adjust neutron dose for ICRP-60 

weighting factor by multiplying by 1.91 c
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 46 of 61

-9 -8 -7 -6 -5 -4 -3 -2

0.01 

0.02 

0.05 

0.10 

0.25 

0.50 

0.75 

0.90 

0.95 

0.98 

0.99 

Ln (Annual Dose - Photon or Neutron)

Lognormal Probability Plot of Annual Neutron and Photon Doses

Neutron 

Doses 

Photon Doses 

Figure 6-17. Lognormal probability plot of Pantex recorded annual photon and 

neutron doses. 

Table 6-18 to calculate the missed photon dose. The method recommended for estimating missed 

photon dose is:

• Assign a missed photon dose based on the MDL/2 method and the number of exchange 

periods (NIOSH 2002) given in Table 6-18 for the respective dosimetry systems. 

6.7.4

Pantex worker neutron dose measurements with the 809/812-accredited and workplace performancevalidated TLND implemented in 1994 are considered accurate. Adjustments are necessary to earlier 

recorded neutron dose with the TLD systems used before 1994 (begun in 1977) and before 1977 with 

the NTA film dosimeter. The recorded neutron doses during these earlier periods are likely to be too 

Low and should not be used in dose reconstructions. The recommended approach, as illustrated in 

Figures 6-15 and 6-16, is to apply a neutron-to-photon dose ratio for the period of neutron dosimeter 

use before 1994, as described in the following:

Photon and Neutron Dose Adjustments

For monitored workers whose occupational activities involved handling nuclear weapons components 

(e.g., Production Technicians and Material Handlers), options to estimate the dose include:

1. Adjust the measured photon and neutron doses for dosimeter response uncertainty. If the 

cancer site is in an area not protected by an apron, apply the lead apron adjustment factor of 

1.5 to the adjusted photon dose.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 47 of 61

Table 6-17. Pantex worker photon dose statistics. 

Year

Recorded photon dose dataa Lognormal fit

No. of workers reported 

photon dose >30 mrem

Dose (mrem) Dose (mrem)

Mean Maximum Median 95% GSD

1952-58 (b)

1959 4 36.3 40 36.0 45 1.15

1960 8 69.4 170 58.0 160 1.86

1961 33 55.7 190 50.1 103 1.55

1962 58 55.5 210 50.1 101 1.53

1963 186 65.7 513 49.6 141 1.88

1964 581 120.0 1,820 74.9 306 2.35

1965 380 101.0 2,950 64.3 231 2.18

1966 708 80.0 1,300 59.2 183 1.98

1967 688 100.0 1,150 71.3 246 2.12

1968 268 90.2 1,090 63.1 220 2.14

1969 350 74.8 1,310 54.0 160 1.93

1970 815 94.2 1,120 63.0 238 2.24

1971 934 102.0 1,400 66.1 265 2.33

1972 765 79.2 540 60.0 188 2.00

1973 1,086 69.6 5,930 53.3 139 1.79

1974 706 91.2 4,990 63.1 200 2.02

1975 329 107.0 10,400 59.3 190 2.03

1976 369 85.6 990 67.1 192 1.90

1977 415 114.0 730 94.8 255 1.83

1978 323 110.0 1,000 77.1 271 2.15

1979 1,144 85.0 2,320 57.0 190 2.08

1980 1,228 86.4 820 60.3 208 2.12

1981 1,605 89.7 1,260 63.2 223 2.15

1982 886 86.5 680 66.5 204 1.98

1983 850 78.9 630 59.8 184 1.98

1984 1,330 63.6 1,100 50.2 136 1.84

1985 991 89.7 1,490 62.9 214 2.11

1986 725 74.1 730 57.9 166 1.90

1987 348 73.5 480 58.4 162 1.86

1988 291 59.8 340 50.7 121 1.70

1989 395 66.1 350 55.4 137 1.73

1990 285 56.6 240 49.5 110 1.63

1991 288 55.4 240 48.6 107 1.62

1992 386 60.3 299 52.6 117 1.63

1993 310 57.5 391 52.0 104 1.52

1994 235 53.6 162 49.5 93 1.47

1995 294 50.2 157 46.8 84 1.43

1996 230 50.5 138 47.3 84 1.42

1997 59 55.4 203 48.9 104 1.58

1998 120 43.4 104 41.6 66 1.32

1999 241 53.7 164 49.5 93 1.47

2000 312 53.1 179 48.8 93 1.48

a. Individual dosimeter records analyzed only if photon dose was equal to or greater than 30 

mrem.

b. All recorded doses less than 30 mrem.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 48 of 61

Table 6-18. Potential missed dose for Pantex workers. 

Dosimeter Period

Exchange

frequencya

MDL (mrem)

Missed annual 

mean dose (mrem)

Skin Deep Neutron Skin Deep Neutron

βγ film 1/1952–12/1959 Weekly 40b 40b I 1,040 1,040

βγ film and NTA film 1/1960–3/1961 Weekly 40 40 I 1,040 1,040 (d)

4/1961–9/1964 Monthly 40 40 I 240 240 (d)

10/1964-12/1968 2/month 40 40 I 520 520 (d)

1/1969–12/1972 Monthly 40 40 I 240 240 (d)

TLD two-element, inhouse and NTA film1973–1976 Monthly 40 40 I 240 240 (d)

TLD six-element in-house 1977–1980 Monthly 30 30 I 180 180 (d)

Panasonic 802 1980–1991 Monthly 30 30 I 180 180 (d)

1992–2000 Monthly 30 30 I 180 180 (d)

Quarterlye 30 30 I 60 60 (d)

Panasonic 809/812 1994–present Monthly 30 30 50 180 180 300

Quarterly 30 30 50 60 60 100

a. Exchange frequencies were established from dosimetry reports. The initial weekly exchange frequency was changed to 

monthly in March 1961 (Tracerlab 1963). A monthly exchange frequency continued with Eberline (Ashton 2003). An 

exchange frequency of twice per month for both beta/gamma and neutron films was established with Landauer in 

October 1964; this frequency changed, for both beta/gamma and neutron films to monthly in January 1969 (Adams 

2003). NTA film provided by Landauer was used with the two-element TLD and exchanged monthly (Adams 2003). 

b. Estimated MDL typical of film dosimeter capabilities (Wilson 1960, 1987; NIOSH 1993; NRC 1989; Wilson et al. 1990).

c. The MDL for neutron doses estimated for years prior to 1994 was unreliable.

d. For years prior to 1994, the reconstructed neutron dose is calculated using the adjusted photon dose and a neutron-tophoton dose ratio.

e. The dosimeter exchange frequency for non-radiation workers was changed from monthly to quarterly in 1992.

2. Prior to 1994, assign a neutron dose for workers handling nuclear components by multiplying 

the adjusted photon dose and missed photon dose by a neutron-to-photon dose ratio of 1.6, 

unless the recorded neutron dose is greater (i.e., use the highest dose).

3. For some workers with best-estimate claims only, details in the claim file should be used to 

determine if unique work activities and exposure geometries could have been a consideration, 

particularly for nonuniform fields generally associated with benchtop operations. In these 

cases, the glovebox correction factors of OCAS-TIB-0010 (NIOSH 2005) are recommended to 

ensure a claimant-favorable analysis.

4. From 1994 to present, no adjustment in measured neutron dose is needed other than standard 

adjustments for dosimeter response uncertainty and ICRP Publication 60 neutron weighting 

factors adjustments (per step 5 below) (ICRP 1991). The missed neutron dose needs only the 

Publication 60 neutron weighting factor adjustment.

5. Multiply the assigned neutron dose by an ICRP (1991) neutron weighting factor adjustment of 

1.91 for neutron energies of 0.1 to 2 MeV.

For unmonitored Pantex workers, who by today’s standards would be monitored, but were not directly 

involved in handling nuclear components, options to estimate the dose include:

1. From 1989 to present, all Pantex workers have been monitored; use the dose of record.

2. Before 1989, if there is no recorded photon dose, use the median (with geometric standard 

deviation) photon dose for Radiation Workers for each year from Table 6-17. Adjust these 

doses for dosimeter response uncertainty. 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 49 of 61

3. Apply the neutron-to-photon dose ratio to the adjusted total photon dose (step 2 above). The 

recommended ratio is 0.8, which is the median neutron-to-photon dose ratio determined by 

Strom (2004). 

4. Multiply the assigned neutron dose by an ICRP (1991) neutron weighting factor adjustment of 

1.91 for neutron energies of 0.1-2 MeV.

6.7.5

In years before 1981, the beta and skin dose records included beta doses only; that is, only 

nonpenetrating beta dose is recorded. In 1981 and subsequent years, the beta and skin dose has 

been calculated as the sum of the whole-body penetrating dose, the nonpenetrating dose, the neutron 

dose, and the whole-body tritium dose. In cases where no nonpenetrating dose was recorded, the 

skin dose is assumed to be equal to the whole-body penetrating dose. Additional guidance on 

determining skin dose can be obtained from ORAUT-OTIB-0017, Interpretation of Dosimetry Data for 

Assignment of Shallow Dose (ORAUT 2005c).

Skin Dose

6.7.6

Wrist type extremity dosimeters have been assigned to radiation workers who directly handled nuclear 

weapon components, such as pits. Since 1980, a Panasonic UD-802 dosimeter with a wrist band has 

been used for extremity dose monitoring. Between 1972 and 1980, a wrist type TLD badge was used; 

before 1972, a wrist type film badge was used. More recently (since 1991), two 802 wrist dosimeters 

(labeled right and left) have been assigned to radiation workers (Pantex 2002).

Extremity Dose

The actual use of extremity dosimeters has not always been rigorously managed, and there were 

times when workers did not wear the assigned extremity dosimeters. If an extremity dosimeter was 

worn and the measured dose was less than the skin dose measured by the whole-body dosimeter, 

the assumption was made that the extremity dosimeter was not worn at least part of the time, and the 

skin dose was assigned as the wrist dose. If the extremity dosimeter did measure a dose greater than 

the whole-body dosimeter, the extremity dose was assigned to the wrist. If wrist dosimeter results 

were obtained for both wrists, the higher result was recorded as the extremity dose. 

Durham and Hickey (1994) established that the average ratio between finger and wrist doses was 2.5. 

Finger rings were exposed on a hand phantom to the surface of a bare pit. Beginning in 1994, wrist 

doses were multiplied by 2.5 to calculate the extremity dose of record. Measured wrist doses from 

before 1994 should be multiplied by 2.5 to calculate the maximum extremity dose, if necessary.

A standard practice in operational health physics is to use a factor of 6 between whole-body and 

extremity exposures. That is, if the measured contact dose rate is 6 times (or more) the measured 

dose rate at the location of the whole-body dosimeter, extremity dosimeters should be assigned for 

the work. In the case of missing extremity dose data, the whole-body dose can be multiplied by 6 and 

the result assigned as a conservative extremity dose. 

Examination of the claimant data revealed that of 316 claims, only 42 had extremity dose data greater 

than 100 mrem recorded in a given year. The 95th-percentile value of this distribution of 

wrist/extremity to whole-body photon dose ratios was approximately 6. If the cancer site involves the 

hands, forearms, feet, or legs below the knees, the extremity dose of record should be used. For any 

periods when the extremity dose of record is missing, the whole body dose multiplied by 6 can be 

used, if necessary.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 50 of 61

6.7.7

Table 6-9 summarizes the recommended fractions for Pantex dose according to facility, worker 

occupational classification, and energy categories required by IREP. Because of the uncertainty in 

actual workplace fields, the energy fractions for claimant dose estimation in Table 6-18 are 

recommended:

Radiation Dose Fraction

• 100% of the photon deep dose to the worker results from 30- to 250-keV photon radiation.

• 100% of the neutron dose to the worker results from 0.1- to 2-MeV neutrons.

These assumptions will generally result in claimant-favorable estimates of organ dose.

6.7.8

Once the adjusted doses have been calculated for each year, the values are used to calculate organ 

doses of interest using the external dose reconstruction implementation guidelines (NIOSH 2002). 

Consistent with OCAS/ORAUT agreements, it is recommended that the 100% AP (front-to-back) 

geometry should be assumed for the irradiation geometry and for conversion to organ dose. The 

calculated neutron doses should be multiplied by the conversion factors from deep dose equivalent to 

organ dose for AP irradiation from Appendix B of NIOSH 2002. For photons prior to 1973 (film badge 

era), the conversion factor from exposure to organ dose should be used. For 1973 to the present 

(TLD era), the conversion factor from deep dose equivalent to organ dose should be used.

Organ Dose

6.7.9

6.7.9.1 Minimizing Assumptions

Claim Analysis Methods

When a claim is categorized as likely compensable, minimizing assumptions are used to process the 

dose assessment quickly and simply. Assumptions such as assigning no neutron dose or no missed 

dose are typical minimizing assumptions that can expedite processing. If the estimated dose 

corresponds to a PC exceeding 50%, even with minimizing assumptions, the claim is probably 

compensable.

6.7.9.2 Maximizing Assumptions

When a claim is categorized as likely noncompensable, maximizing assumptions are used to expedite 

claim processing. Assigning the maximum neutron dose, maximum missed dose, and maximum 

adjustment for uncertainty are typical maximizing assumptions. If the estimated dose with maximizing 

assumptions corresponds to a PC that does not equal or exceed 50%, the claim is probably 

noncompensable.

6.7.9.3 Best Estimate Assumptions

The resolution of claims that require a more realistic assessment to determine compensability should 

consider that the conversion of photon and neutron doses of record to organ doses requires careful 

evaluation without simplifying assumptions. Best available data for the claimant should be used, 

including actual dosimeter results, actual number of x-rays, and actual uptakes. 
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 51 of 61

6.7.9.4 Summary of Correction and Adjustment Factors

The various recommended correction and adjustment factors defined above are summarized in 

Table 6-19 for application of minimizing assumptions, maximizing assumptions, and best estimate 

assumptions.

Table 6-19. Summary of recommended correction and adjustment factors. 

Parameters

Correction and adjustment factors

Minimizing 

assumptions

Maximizing 

assumptions

Best estimate 

assumptions

Photons:

Lead apron adjustmenta 1.0 1.5 1.5

Missed dose 0 N x MDL / 2 Monte Carlo analysis

Dosimeter response uncertainty:

Film badges 1.0 +30% ±30%b

TLDs 1.0 +20% ±20%b

TLDs after DOELAP 1.0 +10% ±10%b

Neutrons:

Prior to 1994: neutron/photon dose ratio 0 1.6 x photon dose Monte Carlo analysis

After 1994 0 Dose of record Dose of record

Dosimeter response uncertainty after 1994 0 +30% ±30%b

ICRP 60 neutron weighting factor 0 1.91 1.91

a. Apply the lead apron adjustment factor if the cancer is located in an area not protected by an apron.

b. Normal distribution. 

6.8 UNCERTAINTY IN PHOTON AND NEUTRON DOSES

For the usual analysis of measured film badge doses, MDLs in the literature range from about 30 to 

50 mrem for beta/photon irradiation (West 1993; Wilson et al. 1990). It is possible to read a photon 

dose of 100 mrem to within ±15 mrem if the exposure involved photons with energies between several 

keV and several MeV (Morgan 1961). The estimated standard error in recorded film badge doses 

from photons of any energy is ±30% (ORAUT 2004a). The estimated uncertainty in doses recorded 

by TLDs is ±20% prior to 1994 (ORAUT 2003a) and ±10% since 1994 (Pantex 2002).

The situation for neutrons was not as favorable as for photons. With NTA films used at Pantex before 

1977, the estimated standard error was larger and varied significantly with the energy of the neutrons. 

Therefore, measured neutron doses to workers were very likely underestimated. TLNDs used 

between 1977 and 1994 had some limitations. The recommended approach is to use neutron-tophoton dose ratios to estimate the neutron dose using the reliably measured photon doses. For 

TLNDs used at Pantex beginning in 1994, the estimated standard errors for a neutron dose of record 

reading of 100 mrem or more are approximately ±30% based on DOELAP performance testing.
Document No. ORAUT-TKBS-0013-6 Revision No. 00 Effective Date: 07/27/2006 Page 52 of 61

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GLOSSARY

Atomic Energy Commission (AEC)

Agency established for oversight of nuclear weapons and power production; a predecessor to 

the U.S. Department of Energy.

beta (β) dose

A designation (i.e., beta) on some Pantex external dose records referring to the dose from 

less-energetic beta, X-ray, or gamma radiation.

beta radiation

Radiation consisting of charged particles of very small mass (i.e., the electron or positron) 

emitted spontaneously from the nuclei of certain radioactive elements. Physically, the beta 

particle is identical to an electron or positron moving at high velocity.

bremsstrahlung

A German term that means secondary electromagnetic radiation (x-rays) produced by 

deceleration of charged particles passing through matter.

curie

A special unit of activity. One curie exactly equals 3.7 × 1010 nuclear disintegrations per 

second.

dose equivalent (H) 

The product of the absorbed dose (D), the quality factor (Q), and any other modifying factors. 

The special unit is the rem. When D is expressed in gray, H is in sieverts (1 sievert = 

100 rem).

dose of record

The dose files provided by DOE to NIOSH as part of the individual worker files. 

dosimeter

A device used to measure the quantity of radiation received. A holder with radiation-absorbing 

elements (filters) and an insert with radiation-sensitive elements packaged to provide a record 

of absorbed dose or dose equivalent received by an individual.

dosimetry

The science of assessing absorbed dose, dose equivalent, effective dose equivalent, etc., 

from external or internal sources of radiation.

dosimetry system

A system used to assess dose equivalent from external radiation to the whole body, skin, and 

extremities. This includes the fabrication, assignment, and processing of dosimeters as well 

as interpretation and documentation of the results.

depleted uranium (DU)

As used in components of nuclear weapons. Pantex listed isotopic activity fractions (NOTE: 

this is not the mass fraction) as:
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Isotope Activity fraction

U-234 0.0840

U-235 0.0145

U-238 0.9015

exchange period (frequency)

Period for routine exchange of dosimeters (weekly, biweekly, monthly, quarterly, etc.).

exposure

As used in the technical sense, a measure expressed in roentgen of the ionization produced 

by photons (i.e., gamma and X-rays) in air. 

extremity

That portion of the arm extending from and including the elbow through the fingertips, and that 

portion of the leg extending from and including the knee and patella through the tips of the 

toes.

film

In this context, a film packet that contains one or more pieces of film in a light-tight wrapping. 

When developed, the film has an image caused by radiation that can be measured using an 

optical densitometer.

film dosimeter

A small packet of film in a holder that attaches to a wearer.

gamma rays (γ)

Electromagnetic radiation (photons) originating in atomic nuclei and accompanying many 

nuclear reactions (e.g., fission, radioactive decay, and neutron capture). Physically, gamma 

rays are nearly identical to X-rays but with higher energy; the only essential difference is that 

X-rays do not originate in the nucleus.

gray

International System unit of absorbed dose (1 gray = 100 rad).

highly enriched uranium (HEU)

Uranium with activity fraction listed by Pantex as:

Isotope Activity fraction

U-234 0.9806

U-235 0.0194

U-238 0.0000

ionizing radiation

Electromagnetic or particulate radiation capable of producing charged particles through 

interactions with matter.

minimum detectable level (MDL)

A statistically determined minimum detectable level, lower limit of detection (LD), and related 

quantities.

minimum recordable dose (MRD)

The minimum dose recorded and reported; the MRD is normally based on site-specific policy.
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neutron

A basic particle that is electrically neutral weighing nearly the same as the hydrogen atom.

neutron, fast

A neutron with energy equal to or greater than 10 keV.

neutron, thermal

Strictly, a neutron in thermal equilibrium with surroundings. In general, a neutron with energy 

less than about 0.4 eV.

neutron film dosimeter

A film dosimeter that contains a nuclear track emulsion, type A, film packet.

nuclear emulsion

Often referred to as NTA film and used to measure personnel dose from neutron radiation.

nuclear track emulsion, type A (NTA)

A film that is sensitive to fast neutrons. The developed image has tracks caused by neutrons 

that can be seen by using an appropriate imaging capability such as oil immersion and a 1000-

power microscope or a projection capability.

open window

Designation on Pantex film dosimeter reports that implies the use of little (i.e., only security 

credential) shielding. It commonly is used to label the film response corresponding to the open 

window area.

personal dose equivalent Hp(d)

The dose equivalent in soft tissue below a specified point on the body at an appropriate depth 

d. The depths selected for personnel dosimetry are 0.07 mm and 10 mm for the skin and 

body, respectively. These are noted as Hp(0.07) and Hp(10), respectively. 

photon

A unit or particle of electromagnetic radiation consisting of X- or gamma rays. 

photon X-ray

Electromagnetic radiation of energies between 10 keV and 100 keV whose source can be an 

X-ray machine or radioisotope.

quality factor, Q

A modifying factor used to derive dose equivalent from absorbed dose.

radiation

Alpha, beta, neutron, and photon radiation.

radiation worker (or radiological worker)

Worker with a job assignment that requires work on, with, or in the proximity of radiationproducing machines or radioactive materials. A radiation worker has the potential of being 

exposed to more than 0.1 rem per year, which is the sum of the dose equivalent from external 

irradiation and the committed effective dose equivalent from internal radiation.
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radioactivity

The spontaneous emission of radiation, generally alpha or beta particles, gamma rays, and 

neutrons from unstable nuclei.

rem

A unit of dose equivalent equal to the product of the number of rad absorbed and the quality 

factor Q. 

roentgen (R)

A unit of exposure to gamma (or X-ray) radiation. A roentgen is defined precisely as the 

quantity of gamma (or X-) rays that will produce a total charge of 2.58 × 10-4 coulomb in 

1 kilogram of dry air. An exposure of 1 roentgen is approximately equivalent to an absorbed 

dose of 1 rad in soft tissue for higher energy photons (over 100 keV).

shielding

Any material or obstruction that absorbs (or attenuates) radiation and thus tends to protect 

personnel or materials from radiation. 

skin dose

Absorbed dose at a tissue depth (density thickness) of 7 mg/cm2

. 

thermoluminescent

Property of a material that causes it to emit light as a result of being excited by heat.

thermoluminescent dosimeter (TLD)

A holder containing solid chips of material that when heated release the stored energy as light. 

The measurement of this light provides a measurement of absorbed dose. 

whole-body dose

The absorbed dose at a tissue depth of 1.0 cm (density thickness of 1,000 mg/cm2

); however, 

this term is also used to refer to the recorded dose.

X-ray

Ionizing electromagnetic radiation that originates outside the nucleus of an atom.