Page 1 of 69

DOE Review Release 12/05/2016

Pantex Plant – Occupational External Dose

ORAUT-TKBS-0013-6 Rev. 03

Effective Date: 11/29/2016

Supersedes: Revision 02

Subject Expert(s): Dale D. Thomas III

Document Owner 

Approval: Signature on File

Dale D. Thomas III, Document Owner

Approval Date: 11/22/2016

Concurrence: Signature on File

John M. Byrne, Objective 1 Manager

Concurrence Date: 11/18/2016

Concurrence: Signature on File

Edward F. Maher, Objective 3 Manager

Concurrence Date: 11/18/2016

Concurrence: Vickie S. Short Signature on File for

Kate Kimpan, Project Director

Concurrence Date: 11/21/2016

Approval: Signature on File

James W. Neton, Associate Director for Science

Approval Date: 11/29/2016

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

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.

New Total Rewrite Revision Page Change
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 2 of 69

 

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.

06/22/2007 01 Approved revision initiated to incorporate Attributions and 

Annotations section. Constitutes a total rewrite of the document. 

Added references and made editorial changes. Modified Table 6-1 

average total dose for 1958, 1977, 1983, and 1997. Modified Table 

6-9 to add Radiography NDE. No further changes occurred as a 

result of formal internal review. Incorporates formal NIOSH review 

comments. This revision results in no change to the assigned dose 

and no PER is required. Training required: As determined by the 

Task Manager. Initiated by Jack J. Fix.

11/24/2015 02 Revision initiated to add section detailing the Special Exposure 

Cohort classes for the Pantex Plant. Includes editorial changes. 

Incorporates formal internal and NIOSH review comments. 

Constitutes a total rewrite of the document. Training required: As 

determined by the Objective Manager. Initiated by Dale D. 

Thomas III. 

11/29/2016 03 The revision was initiated due to the determination that NTA Film 

neutron dosimetry ended in 1973 as opposed to 1976 as previously 

understood. Revisions were made to Sections 6.5.2, 6.5.2.2, 6.5.5.3, 

6.7.2, 6.7.3, and 6.8. References were updated. Incorporates formal 

internal and NIOSH review comments. Training required: As 

determined by the Objective Manager. Initiated by Dale D. 

Thomas III.
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 3 of 69

TABLE OF CONTENTS

SECTION TITLE PAGE

Acronyms and Abbreviations ............................................................................................................... 6

6.1 Introduction .............................................................................................................................. 8

6.1.1 Purpose........................................................................................................................ 9

6.1.2 Scope........................................................................................................................... 9

6.1.3 Special Exposure Cohort.............................................................................................. 9

6.1.3.1 January 1, 1958, through December 31, 1983 ............................................... 9

6.1.3.2 January 1, 1984, through December 31, 1991 ............................................. 10

6.1.4 Pantex Workers at Other AEC/DOE Facilities............................................................. 10

6.2 External Dosimetry................................................................................................................. 11

6.2.1 Potential for Workplace Exposures Based on Job Categories .................................... 11

6.3 Basis Of Comparison ............................................................................................................. 13

6.4 External Radiation Exposure Records.................................................................................... 13

6.5 Dose Reconstruction Parameters........................................................................................... 14

6.5.1 Historical Administrative Practices.............................................................................. 15

6.5.2 Dosimetry Technology................................................................................................ 15

6.5.2.1 Beta/Photon Dosimeters .............................................................................. 17

6.5.2.2 Neutron Dosimeters ..................................................................................... 21

6.5.2.3 Effects of Changing Early Dosimetry Services ............................................. 22

6.5.3 Dosimeter Calibration Procedures .............................................................................. 23

6.5.3.1 Beta/Photon Dosimeters .............................................................................. 23

6.5.3.2 Neutron Dosimeters ..................................................................................... 24

6.5.4 Workplace Radiation Fields ........................................................................................ 25

6.5.4.1 Depleted Uranium ........................................................................................ 26

6.5.4.2 Photon Radiation.......................................................................................... 26

6.5.4.3 Neutron Radiation ........................................................................................ 29

6.5.5 Dosimeter Response to Radiation Fields.................................................................... 30

6.5.5.1 Beta/Photon Film Dosimeter Response........................................................ 30

6.5.5.2 Beta/Photon TLD Dosimeter Response........................................................ 31

6.5.5.3 Neutron Dosimeter Response ...................................................................... 33

6.5.5.4 Neutron Dose Weighting Factor ................................................................... 34

6.5.5.5 Use of Lead Aprons ..................................................................................... 35

6.6 Analysis of Claims Filed by Pantex Workers .......................................................................... 38

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

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

6.6.3 Analysis of Recorded Doses....................................................................................... 39

6.7 Recommendations for Pantex Worker External Dose Reconstruction .................................... 41

6.7.1 Unmonitored External Dose........................................................................................ 41

6.7.2 Adjustment for Protective Lead Aprons....................................................................... 41

6.7.3 Photon and Neutron Dose Adjustments...................................................................... 42

6.7.4 Skin Dose................................................................................................................... 42

6.7.5 Extremity Dose ........................................................................................................... 43

6.7.6 Radiation Dose Fraction ............................................................................................. 43
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6.7.7 Organ Dose................................................................................................................ 44

6.8 Uncertainty in Photon and Neutron Doses ............................................................................. 44

6.9 Attributions and Annotations .................................................................................................. 44

References ........................................................................................................................................ 54

Glossary ............................................................................................................................................ 60

ATTACHMENT A UNMONITORED EXTERNAL DOSE TABLES................................................ 65

LIST OF TABLES

TABLE TITLE PAGE

6-1 Job titles and descriptions of work with possibility for occupational exposures ....................... 12

6-2 Dosimeter type, period of use, exchange frequency............................................................... 16

6-3 Dosimeter limits of detection for dose reconstruction by period.............................................. 16

6-4 UD-802 dosimeter characteristics .......................................................................................... 19

6-5 UD-812/UD-809 dosimeter characteristics ............................................................................. 20

6-6 IARC study results for U.S. beta/photon dosimeters............................................................... 21

6-7 Ratio of neutron-to-photon cumulative dose........................................................................... 23

6-8 Common sources of laboratory bias in calibration parameters for beta/photon dosimeters .... 24

6-9 Common sources of laboratory bias in calibration parameters for neutron dosimeters ........... 25

6-10 Beta, photon, and neutron radiation energies and percentages for Pantex facilities ............... 31

6-11 Typical workplace beta/gamma dosimeter Hp(10) performance............................................. 32

6-12 Typical workplace neutron dosimeter performance ................................................................ 33

6-13 Neutron quality factor or weighting factor ............................................................................... 35

6-14 Neutron dose energies, percentages and associated correction factors for nuclear 

weapons component assembly and disassembly................................................................... 35

6-15 Percent reduction in measured photon dose provided by lead aprons ................................... 37

6-16 Cancer sites protected or unprotected by apron..................................................................... 37

6-17 General categories of job titles for Pantex workers and recorded collective doses................. 40

A-1 Annual Pantex external photon doses.................................................................................... 67

A-2 Annual Pantex external neutron doses................................................................................... 68

A-3 Annual Pantex external skin doses ........................................................................................ 69

LIST OF FIGURES

FIGURE TITLE PAGE

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

recorded annual dose ............................................................................................................ 14

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 ............................................................... 18

6-3 Six-element TLD holder ......................................................................................................... 19
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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 ................................................................................................................................22

6-5 Cumulative plot of annual photon and neutron recorded dose................................................ 23

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 ........................................................................................................................................28

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 .................................................. 30

6-10 Comparison of neutron quality factors used in PNNL neutron spectrum measurements 

(Soldat et al. 1990) 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 workers.............................................................................................. 34

6-11 Body areas covered by lead apron......................................................................................... 36

6-12 Frequency distribution of claims that encompass the respective years................................... 39

6-13 Distribution of annual photon and neutron dose for Pantex claims ......................................... 40
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ACRONYMS AND ABBREVIATIONS

AEC U.S. Atomic Energy Commission

AP anterior-posterior

AWE Atomic Weapons Employer

CFR Code of Federal Regulations

Ci curie

cm centimeter

DHHS U.S. Department of Health and Human Services

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 explosive

HERS Historical Exposure Records System

HEU highly enriched uranium

Hp(0.07) personal dose equivalent at 0.07 millimeters depth in tissue

Hp(10) personal dose equivalent at 10 mm depth in tissue

Hp(d) personal dose equivalent at depth d

Hp,slab(10) personal dose equivalent (slab phantom) at 10-mm depth in tissue

IARC International Agency for Research on Cancer

ICD International Classification of Diseases

ICRP International Commission on Radiological Protection

IREP Interactive RadioEpidemiological Program

ISO isotropic

keV kiloelectron-volt, 1,000 electron-volts

MCNP Monte Carlo N-Particle

MDL minimum detectable level

MED Manhattan Engineer District

MeV megaelectron-volt, 1 million electron-volts

mg milligram

mm millimeter

mrad millirad

MRD minimum recordable dose

mrem millirem

n neutron

NCRP National Council on Radiation Protection and Measurements

NDE nondestructive evaluations

NIOSH National Institute for Occupational Safety and Health

NTA nuclear track emulsion, type A

ORAU Oak Ridge Associated Universities
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PNNL Pacific Northwest National Laboratory

PPD Pantex Personnel Dosimeter

ROT rotational

RPG radiation protection guideline

RST Radiation Safety Technician

SD standard deviation

SEC Special Exposure Cohort

SRDB Ref ID Site Research Database Reference Identification (number)

TBD technical basis document

TLD thermoluminescent dosimeter

TLD-600 LiF TLD with enriched 6

Li

TLD-700 LiF TLD with enriched 7

Li

TLND thermoluminescent neutron dosimeter

U.S.C. United States Code

μg microgram

Z atomic number

α alpha particle

β beta particle

γ gamma ray

§ section or sections
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6.1 INTRODUCTION

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

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

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

dose reconstructions at particular Department of Energy (DOE) or Atomic Weapons Employer (AWE) 

facilities or categories of DOE or AWE facilities. They will be revised in the event additional relevant 

information is obtained about the affected DOE or AWE facility(ies). These documents may be used 

to assist NIOSH staff in the evaluation of Special Exposure Cohort (SEC) petitions and the completion 

of the individual work required for each dose reconstruction.

In this document the word “facility” is used to refer to an area, building, or group of buildings that 

served a specific purpose at a DOE or AWE facility. It does not mean nor should it be equated to an 

“AWE facility” or a “DOE facility.” The terms AWE and DOE facility are defined in sections 7384l(5) 

and (12) of the Energy Employees Occupational Illness Compensation Program Act of 2000 

(EEOICPA), respectively. An AWE facility means “a facility, owned by an atomic weapons employer, 

that is or was used to process or produce, for use by the United States, material that emitted radiation 

and was used in the production of an atomic weapon, excluding uranium mining or milling.” 42 U.S.C. 

§ 7384l(5). On the other hand, a DOE facility is defined 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 [DOE] (except for buildings, 

structures, premises, grounds, or operations ... pertaining to the Naval Nuclear Propulsion Program);” 

and with regard to which DOE has or had a proprietary interest, or “entered into a contract with an 

entity to provide management and operation, management and integration, environmental 

remediation services, construction, or maintenance services.” 42 U.S.C. § 7384l(12). The Department 

of Energy (DOE) determines whether a site meets the statutory definition of an AWE facility and the 

Department of Labor (DOL) determines if a site is a DOE facility and, if it is, designates it as such.

Accordingly, a Part B claim for benefits must be based on an energy employee’s eligible employment 

and occupational radiation exposure at a DOE or AWE facility during the facility’s designated time 

period and location (i.e., covered employee). After DOL determines that a claim meets the eligibility 

requirements under EEOICPA, DOL transmits the claim to NIOSH for a dose reconstruction. 

EEOICPA provides, among other things, guidance on eligible employment and the types of radiation 

exposure to be included in an individual dose reconstruction. Under EEOICPA, eligible employment 

at a DOE facility includes individuals who are or were employed by DOE and its predecessor 

agencies, as well as their contractors and subcontractors at the facility. Unlike the abovementioned 

statutory provisions on DOE facility definitions that contain specific descriptions or exclusions on 

facility designation, the statutory provision governing types of exposure to be included in dose 

reconstructions for DOE covered employees only requires that such exposures be incurred in the 

performance of duty. As such, NIOSH broadly construes radiation exposures incurred in the 

performance of duty to include all radiation exposures received as a condition of employment at 

covered DOE facilities in its dose reconstructions for covered employees. For covered employees at 

DOE facilities, individual dose reconstructions may also include radiation exposures related to the 

Naval Nuclear Propulsion Program at DOE facilities, if applicable. No efforts are made to determine 

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

NIOSH does not consider the following types of exposure as those incurred in the performance of 

duty as a condition of employment at a DOE facility. Therefore these exposures are not included in 

dose reconstructions for covered employees (NIOSH 2010a):

• Background radiation, including radiation from naturally occurring radon present in 

conventional structures

• Radiation from X-rays received in the diagnosis of injuries or illnesses or for therapeutic 

reasons
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6.1.1 Purpose

Pantex Plant was one of the last plants built during World War II to load, assemble, and pack highexplosive (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 technical basis document (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.

6.1.2 Scope

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

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

weapon systems (Mitchell 2003). Today, Pantex continues to fabricate HE 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, operated by the 

DOE Office of Defense Programs, is the only facility in the United States that performs these 

operations.

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. 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).

Attributions and annotations, indicated by bracketed callouts and used to identify the source, 

justification, or clarification of the associated information, are presented in Section 6.9.

6.1.3 Special Exposure Cohort

6.1.3.1 January 1, 1958, through December 31, 1983

On December 21, 2011, the Secretary of the U.S. Department of Health and Human Services (DHHS) 

designated the following class of employees as an addition to the SEC (DHHS 2011):

All employees of the Department of Energy, its predecessor agencies, and their 

contractors and subcontractors who worked at the Pantex Plant in Amarillo, Texas, 

during the period from January 1, 1958 through December 31, 1983, for a number of 

work days aggregating at least 250 work days, occurring either solely under this 

employment or in combination with work days within the parameters established for one 

or more other classes of employees included in the SEC.

As stated in DHHS (2011), DHHS found that it lacks sufficient personnel or area monitoring data, 

source term data, and operational information to support completely reconstructing internal dose with 

sufficient accuracy at the Pantex Plant from January 1, 1958, through December 31, 1983. However, 

the letter indicates that the principal sources of external radiation doses for members of the evaluated 

class were plutonium, uranium, and thorium components in weapons systems, radiation-producing 

machines used in non-destructive examination of components, and medical X-ray examinations. The 

letter further indicates that the Board and NIOSH determined that these external doses can be 

reconstructed with sufficient accuracy based on dosimeter measurements, workplace measurements 
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in order to estimate early neutron doses, and complex-wide approaches for reconstructing medical 

X-ray exposures. Although DHHS found it is not possible to completely reconstruct internal radiation 

doses for the proposed class, NIOSH can use any reliable internal and external monitoring data that 

may be available for an individual claim during this period (and that can be interpreted using existing 

NIOSH dose reconstruction processes or procedures). Therefore, dose reconstruction for individuals 

employed at the Pantex Plant during the period from January 1, 1958, through December 31, 1983, 

but who do not qualify for inclusion in the SEC, can be performed using these data as appropriate to 

support partial dose reconstructions.

6.1.3.2 January 1, 1984, through December 31, 1991

On September 30, 2013, the Secretary of DHHS designated the following class of employees as an 

addition to the SEC (DHHS 2013):

All employees of the Department of Energy, its predecessor agencies, and their 

contractors and subcontractors who worked at the Pantex Plant in Amarillo, Texas, 

during the period from January 1, 1984 through December 31, 1991, for a number of 

work days aggregating at least 250 work days, occurring either solely under this 

employment or in combination with work days within the parameters established for one 

or more other classes of employees included in the SEC. 

As stated in DHHS (2013), DHHS found that it lacks specific biological monitoring data, air monitoring 

data, process and radiological source information, and surrogate data from similar operations at other 

sites to support completely reconstructing internal dose with sufficient accuracy at the Pantex Plant 

from January 1, 1984, through December 31, 1991. However, the letter indicates that the principal 

sources of external radiation doses for members of the proposed class were plutonium pits and 

depleted uranium and thorium components. Secondary sources of external exposure included other 

radioactive materials present in smaller quantities (typically microcurie levels) as calibration sources 

or in larger quantities (up to curie levels) as radiography sources (ORAUT 2015). DHHS (2013)

further indicates that NIOSH concluded that it is feasible, using methods in existing NIOSH 

procedures, to reconstruct external radiation doses, including the X-ray dose (when appropriate), for 

all Pantex workers from January 1, 1984, through December 31, 1991. Based on this information, 

DHHS and NIOSH concluded that the external doses could be reconstructed for all years using the 

available external monitoring data for Pantex workers, adjusted during some periods to account for 

the performance of the monitoring devices. Although DHHS found it is not possible to completely 

reconstruct internal radiation doses for the proposed class, NIOSH can use any reliable internal 

monitoring data that may be available for an individual claim during this period (and that can be 

interpreted using existing NIOSH dose reconstruction processes or procedures) and external 

monitoring data as described above. Therefore, dose reconstruction for individuals employed at 

Pantex Plant during the period from January 1, 1984, through December 31, 1991, but who do not 

qualify for inclusion in the SEC, can be performed using these data as appropriate to support partial 

dose reconstructions.

6.1.4 Pantex Workers at Other AEC/DOE Facilities

Due to the nature of the work at Pantex, workers were sometimes temporarily required to perform 

their duties at other AEC/DOE facilities [e.g., the Nevada Test Site (which is now the Nevada National 

Security Site), modification centers, national laboratories, etc.] and might have been monitored for 

occupational radiation exposures by Pantex, the temporary work location, or concurrently by both 

facilities. In such cases, all available monitoring records should be used to assign worker doses.
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6.2 EXTERNAL DOSIMETRY

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

information, so a complete description of events is not publicly available. The 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 Ordnance Plant in 1947; the second 

was the Pantex Plant in 1951. Pantex was originally a conventional munitions factory, loading HE into 

bombs and artillery shells (DOE 1997); it was converted to nuclear weapons work in 1951 and 1952. 

In 1975, Iowa Ordnance Plant 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 from the Pantex Plant 

and other sources about radiation doses Pantex workers received 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 ca. 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-ray, gamma, and neutron 

radiation; however, doses to workers depend strongly on the configuration (i.e., material and 

shielding) of the source of radiation and the work that was performed (BWXT Pantex 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.

OCAS-IG-001, the External Dose Reconstruction Implementation Guideline (NIOSH 2007), 

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 

(ORAUT 2003a). Early dosimetry practices were based on experience from 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 Engineer 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, (2) mixed radiation fields 

involving beta particles, photons (gamma and X-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.

6.2.1 Potential for Workplace Exposures Based on Job Categories

Knowing the job title and a brief description of duties for that title can be helpful in determining the 

correct information to use for assessing dose. Production technicians (also called assembly 

operators) and radiation safety technicians (RSTs) typically had the highest potential for occupational 

external doses. Other workers could have received external dose, but the probability of receiving 

external exposure was smaller. Claimant interview files might not list the same job title because the 

interviewee could have described the type of job rather than the job title and because job titles have 

changed over the years. Table 6-1 summarizes job titles, descriptions, and relative potential for 

receiving occupational external exposures.
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Table 6-1. Job titles and descriptions of work with possibility for occupational exposures.

Job title Description of work

Possibility for exposure

(1 highest)a

Production Technician, Assembler, 

Assembly Operator, Assembly 

Fabrication

Assembles, disassembles, reassembles, and 

inspects components.

1

Quality Assurance Technician I Conducts nondestructive evaluations (NDEs) with 

linear accelerators, X-ray machines, etc.; conducts 

telemetry testing; performs confirmatory 

measurements on components, assemblies, 

containers, etc.

1

Quality Assurance Technician II Performs NDEs, electronic, destructive, telemetry, 

and radiation measurement testing.

1

RST (entry) Performs monitoring and sampling, collects 

samples, assists RST in monitoring personnel.

1a

RST Performs monitoring and sampling, collects 

samples, performs radiation and contamination 

surveys, conducts surveillance work.

1

RST (Senior) Responds to contamination or radiation alarms; 

performs surveillance, monitors radiation conditions 

in workplace.

1

Firing Site Technician Includes hydroshot operators, drivers, anyone 

involved with cleanup of hydroshot contamination.

2

Not known, possibly drivers or 

teamsters

Includes burning of HE and cleanup of ash at 

burning ground.

2

Material Handler (pits and cans) Operates material handling/moving equipment,

transports material, loads and unloads materials 

and containers.

2

Operations Manager, Production 

Supervisor 

Supervises personnel engaged in manufacturing, 

assembly, packaging, material control, etc.

2

Quality Control Inspectors/ 

Auditors

Conducts special audits, different from Quality 

Assurance Technicians.

2

Security, protective force, guard Performs per job title. 2b

Engineer, engineering Performs variety of tasks associated with design, 

testing, and procedure development.

2c

Machinist Machining on components. 2a

Metrology laboratory staff Performs nonradiological metrology calibrations. Onsite ambient only

Fireman Performs per job title. Onsite ambient only

Computer Programmer, Electronic 

Data Processing Analyst 

Performs computer programming and maintenance. Onsite ambient only

Secretary, Administrator, 

Technical Writer, Nonoperations 

management, Planner

Performs per job title. Onsite ambient only

Tool and die maker Performs per job title. Onsite ambient only

Food service Performs tasks associated with operation of 

cafeteria.

Onsite ambient only

Stores Stockman, Clerk, 

Supervisor

Performs tasks associated with general stores. Onsite ambient only

a. Based on actual contact with components.

b. In general, security personnel had lesser risks of occupational external exposures. However, some potential for 

exposures can be inferred from working inside the cells, pit vaults, igloos, and gravel gerties. The default assumption is 

to place security personnel in Category 2; however, based on other information in the file, dose reconstructors may 

assign onsite ambient dose only if they believe the worker’s tasks did not involve entry into cells, pit vaults, gravel 

gerties, igloos, or locations within the material access areas.

c. Engineering tasks cover a wide range and most have little or no potential for occupational external exposures. 

However, some tasks might have involved observations during assembly or disassembly work. If the engineer did not 

have a dosimeter or never had recordable dose, only assign environmental dose unless there is information in the file to 

indicate otherwise.
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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 in comparison to current dosimetry performance and field-tested capabilities. The dates of 

change in the Pantex dosimetry systems are known (ORAUT 2003a); comparisons of recorded doses 

before and after these changes provide the ability to assess consistency. Similar radiation sources 

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 and the personal dose equivalent is noted as Hp(0.07). For penetrating 

radiation of significance to whole-body dose, d = 10 mm and 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 that contains 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 (ORAUT 2004). In 2015, a detailed evaluation of this data 

was performed that resulted in the development of an external coworker model (ORAUT 2016). The 

results of this evaluation are summarized in Attachment A. At first, Pantex issued dosimeters only to 

workers likely to receive a radiation dose. From 1952 through 1957, this included only radiographers 

(ORAUT 2003b). From 1958 through 1988, only radiation workers were monitored (ORAUT 2003b). 

The variations in numbers of radiation workers reflect changes in weapon production rates (Carr ca. 

1992). Since 1989, all Pantex workers who enter a radiologically controlled area have been 

monitored for external radiation exposure (Griffis 1988). Figure 6-1 shows the number of monitored 

workers and the number who had recorded annual doses of zero from external sources. For most of 

this period, very few workers received significant external doses. From 1960 to 1980, however, a 

larger fraction of the workers received nonzero external doses [1]. The increase was 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 checked for accuracy. Missing records or anomalies were analyzed, with worker 

assistance, and appropriate notes were entered in the record (Rawlston 1991). The HERS project 

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

In late 1992, the algorithm Pantex used to calculate doses was changed to resolve performance 

issues during the 1989 DOELAP performance testing. This algorithm, called the “Stanford Algorithm,” 

was used to successfully pass DOELAP performance testing during 1993. The recalculated doses 

have been linked to individual claimant files and are typically present in the worker’s records in 

addition to the original site-reported doses. These records should be compared, and the result most 

favorable to the claimant should be used for each dose reconstruction.
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 14 of 69

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 (ORAUT 2003b).

6.5 DOSE RECONSTRUCTION PARAMETERS

Examinations of the beta, photon (X- and gamma and X-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) (BWXT Pantex 2002). 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 

(BWXT Pantex 2002).

Overall, the accuracy and precision of original individual worker doses of record and their 

comparability to be considered in using NIOSH (2007) guidelines depend on:

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

based on technical, administrative, and statutory compliance considerations;

• Dosimetry technology that was used, including the physical capabilities of the dosimetry

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

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

calibration to sources of exposure in the workplace; and
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 15 of 69

 

• 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 Historical Administrative Practices

Pantex started monitoring workers for radiation exposure in 1952 (ORAUT 2003a, 2003b). 

Dosimeters that were 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. 

Table 6-3 lists reasonable minimum detectable levels (MDLs) for most applications for film and 

thermoluminescent dosimeters (TLDs) based on era of use and processor (Wilson 1960, 1987; 

NIOSH 1993; NRC 1989; Wilson et al. 1990).

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

• Assigning dosimeters to workers (Rawlston 1991),

• Exchanging dosimeters (Rawlston 1991),

• 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 (Rawlston 1991),

• Evaluating and recording doses for incidents or accidents (Rawlston 1991), and

• Obtaining and recording occupational dose to workers for other exposures (Rawlston 1991).

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 [2]. Dosimeters were exchanged on a routine 

schedule [3]. Beginning in 1980, if dosimeters were lost or damaged, investigations were conducted 

and doses were recorded that reflected the results of the investigation (ORAUT 2003b). 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 in Watson et al. (1994) and based on examination 

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

TBD.

6.5.2 Dosimetry Technology

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

understanding of the complex radiation fields 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. (BWXT Pantex 2001).
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 16 of 69

Table 6-2. Dosimeter type, period of use, and exchange frequency (ORAUT 

2003a).

Dosimeter type/ provider Period and exchange frequencya

βγ film/Tracerlab 01/1952–12/1959, weekly

βγ film and nuclear track emulsion, type A (NTA) 

film/Tracerlab

01/1960–03/1961, weekly

04/1961–05/1963, monthly

βγ film and NTA film/Eberline 06/1963–09/1964, monthly

βγ film and NTA film/Landauer 10/1964–12/1968, twice per month

βγ film and NTA film/Landauer 01/1969–12/1972, monthly

TLD 2-element/in-house and NTA film/Landauerb 01/1973–12/1973, monthly

Pantex in-house TLD 1974–1979, monthly

Panasonic UD-802/in-house 1980–1991c, monthly

Panasonic UD-802/in-house 1992–2000c, monthly

Panasonic UD-802/in-house 1992–2000b, quarterly

Panasonic UD-809/UD-812/in-housed 1994–present, monthly

Panasonic UD-809/UD-812/in-housed 1994–present, quarterly

a. Exchange frequencies were established from dosimetry reports. The initial weekly exchange 

frequency was changed to monthly in March 1961 (Tracerlab 1962–1963). 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 to monthly in January 1969 for both beta/gamma and neutron 

films (Adams 2003). NTA film provided by Landauer was used with the two-element TLD and 

exchanged monthly (Adams 2003).

b. The Pantex in-house two-element TLD was implemented in 1973 for monitoring only 

beta/gamma radiation exposures. Thermoluminescent neutron dosimeters (TLNDs) for 

monitoring neutron exposures were implemented in 1974.

c. In 1992, the algorithms were changed from the Panasonic 802 to the Stanford algorithms 

(BWXT Pantex 2002). The dosimeter exchange frequency for nonradiation workers was 

changed from monthly to quarterly in 1992.

d. Beginning in January 1994, the Panasonic UD-809/UD-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 UD-809/UD-812 

dosimeters for all workers.

Table 6-3a. Dosimeter limits of detection for dose reconstruction by period.

Years Gamma, mrem Skin, mrem Neutron, mrem

1952–1959 10 30 Not applicableb

1960–1963 10 30 15

1964–1972 10 40 20

1973 4 10 10

1974–1979 4 10 50

1980–1991 20 20 50

1992–1993 15 20 85

1994–2010 15 15 10

a. Estimated MDL typical of dosimeter capabilities (Wilson 1960, 1987; NIOSH 1993; NRC 

1989; Wilson et al. 1990).

b. Neutron dosimetry was not performed prior to 1960 (ORAUT 2003a).

Dosimeter exchange frequency gradually lengthened and corresponded to downward reductions in 

RPGs (Morgan 1961). During the early stages of the program to monitor individual Pantex workers, a 

weekly dose control of 0.3 rem was in effect (NBS 1951). Table 6-2 summarizes major changes in 

Pantex external dosimetry systems and routine dosimeter assignment periods for workers.

The first dosimeter used at Pantex was a two-element film badge from Tracerlab for measuring beta, 

X-ray, and gamma exposures (Tracerlab 1962–1963). Beginning in 1960, Pantex used a 

multielement film badge that incorporated NTA film to measure beta, X-ray, gamma, and fast neutrons 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 17 of 69

 

(Tracerlab 1962–1963). 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 

through 1973 (Adams 2003; Alexander, Hess, and Canada 1973). Beginning in 1974, neutron 

exposure monitoring was accomplished using TLDs. From 1977 to 1980, Pantex used a six-element 

in-house TLD system that included personal nuclear accident dosimeter elements (DOE 1980; 

ORAUT 2003a). 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 DOELAPaccredited and used for radiation workers beginning in 1994 (BWXT Pantex 2002). The UD-802 was 

used for all other workers until it was phased out in 2001. All Pantex workers who entered 

radiologically controlled areas have been monitored with the UD-809/UD-812 TLD since 2001 

(ORAUT 2003b).

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

1983; McDonald et al. 1983). For current TLDs, minimum recordable doses (MRDs) are precisely 

defined in the Pantex Plant Technical Basis Manual for External Dosimetry (BWXT Pantex 2002). 

The MRDs are not necessarily equivalent to the MDL or lower limit of detection described in NIOSH 

(2007) or in the DOELAP standard (DOE 1986). Dosimeter readings that indicated a dose less than 

these MDLs were judged to have high uncertainty. For earlier dosimetry systems, similar quantities 

existed 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 [4]. Table 6-3 

lists the MRDs of dosimeters that were used at the Pantex Plant to monitor for neutron deep doses 

and beta/gamma skin and 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 2006a) and 

thermoluminescent (ORAUT 2006b) 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 TLDs are 40 and 30 mrem, respectively. A 

typical MDL (missed dose) per exchange cycle for neutrons is 50 mrem for both NTA film (ORAUT 

2006c) and TLND (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, 

due primarily to relatively (in comparison to tissue) high atomic numbers (Z) [silver (Z = 47) and 

bromine (Z = 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 near unity. The 

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

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 Z of the lithium (Z = 3) and fluorine (Z = 9) in the chips (Horowitz 

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

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

film over an open window and a 290-mg/cm2 aluminum filter for beta/photon discrimination (ORAUT 

2003a; Alexander, Hess, and Canada 1973). The six-element TLD badges that were adopted for use 

in 1977 were patterned after a Sandia design (DOE 1980; ORAUT 2003a). Figure 6-3 shows the TLD 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 18 of 69

 

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).

holder, chips, and filters. The open window for measuring skin dose was covered by a 7-mg/cm2

polyester tape over the TLD-700 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, which was implemented at Pantex in 1980, was the multielement 

Panasonic Model UD-802 (BWXT Pantex 2002). The UD-802 TLD is capable of measuring beta, 

photon, and thermal and albedo neutron radiations. Table 6-4 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 300 mg/cm2 of 

plastic, which provides 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 it 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, which reduces the over-response because it is 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 19 of 69

 

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

Table 6-4. UD-802 dosimeter characteristics (BWXT Pantex 2002).

Characteristic E1 E2 E3 E4

Phosphor 6Li2B4O7 6Li2B4O7 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

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 

tested radiation categories, including neutrons and mixtures of radiations. However, neutron doses 

can be overestimated by as much as 8 times because the fixed unmoderated 252Cf correction factor is 

used for neutron responses (BWXT Pantex 2002).

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

2002; ORAUT 2003b). This system was DOELAP-accredited in all beta, photon, and neutron 

radiation testing categories in 1993 [5]. 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 6Li 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 6-5 lists 

phosphor and filtration data for the UD-812 TLD and holder used at Pantex. The response of the UD812 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 (BWXT Pantex 2002). It uses four 

lithium-borate phosphors under different filters of approximately the same density thickness. 

Table 6-5 lists phosphor and filtration data for the UD-809/UD-812 and holder used at Pantex. The 

first position, E5, is 7

Li2

11B4O7 depleted of the neutron-sensitive 6

Li and 10B. This element is used to 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 20 of 69

Table 6-5. UD-812/UD-809 dosimeter characteristics (BWXT Pantex 2002).

Element Phosphor

Filtration 

(front/back)

Filter thickness 

(mg/cm2) Sensitivity

Primary 

use

E1 (812) 7Li211B4O7 Plastic 17 Beta/gamma Beta

E2 (812 7Li211B4O7 Plastic 150 Beta/gamma Beta

E3 (812) CaSO4 Plastic 300 Beta/gamma Gamma

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

E5 (809) 7Li211B4O7 Cd/Cd 900 Gamma Gamma

E6 (809) 6Li210B4O7 Sn/Cd 900 Gamma/thermal neutron Neutron

E7 (809) 6Li210B4O7 Cd/Cd 900 Gamma/neutron Neutron

E8 (809) 6Li210B4O7 Cd/Sn 900 Gamma/albedo neutron Neutron

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 [6].

Analyses of dosimeter performance data and workplace collective dose patterns in Tables 6-2 and 6-3 

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 UD802 TLD used at the DOE Savannah River Site (US-22) and at Pantex from 1980 to 2001. 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 water-filled 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 6-6 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 twoelement film badge (ORAUT 2003b).

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 only AP irradiations. Although there are differences 

in films and filters 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. 03 Effective Date: 11/29/2016 Page 21 of 69

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

US-2 (Two-element film dosimeter)

Geometry Phantom

118 keV meana and 

SD/meanb

208 keV meana and 

SD/meanb

662 keV meana and 

SD/meanb

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)

Geometry Phantom

118 keV meana and 

SD/meanb

208 keV meana and 

SD/meanb

662 keV meana and 

SD/meanb

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)

Geometry Phantom

118 keV meana and 

SD/meanb

208 keV meana and 

SD/meanb

662 keV meana and 

SD/meanb

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 that were used at the Pantex Plant differ significantly in 

their response to neutrons of different energies (Figure 6-4) (IAEA 1990). NTA film was included in 

the holder for the Pantex beta/gamma dosimeter from 1960 through 1973 (ORAUT 2003a). 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 TLND (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 (Thompson 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 (BWXT 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 et al. 1994). 
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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).

However, neutron doses derived from this version of the algorithm could be overestimated by as 

much as 8 times because the fixed unmoderated 252Cf correction factor is used for neutron responses 

(BWXT Pantex 2002).

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 have been only limited and incomplete Pantex studies 

that compared 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 that were 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 photon energies (i.e., 40 and 70 keV). 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 6-7 

[7]. 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 [8]. Figure 6-5 shows a plot in cumulative Pantex worker photon and neutron doses from 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 23 of 69

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 

Table 6-7. Ratio of neutron-to-photon cumulative dose.

Dosimeter technology

Neutron

cumulative dose 

(person-rem)

Photon

cumulative dose 

(person-rem) Ratioa 

Film + NTA, 1952–1972 41.67 595.66 0.070

TLD + NTA, 1972 1973, 

TLND, 1974–1976

31.01 238.61 0.130

TLND, 1977–1993 303.45 1,142.09 0.266

UD-809/UD-812 TLND, 1994–2004 65.51 261.75 0.250

a. Rounded to three significant figures.

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

(ORAUT 2003b, 2004).

comparatively smooth during the transition from film to TLDs in the mid-1970s. The trend in the 

neutron dose fraction (in comparison with the photon dose) implies a significantly increased neutron 

dose fraction when TLDs were used. However, the ratio between neutron and photon doses is 

significantly variable, particularly before the mid-1980s [9]. 

6.5.3 Dosimeter Calibration Procedures

Potential error in doses of record depends on the dosimeter calibration methods and the extent of the 

similarity between the radiation fields for calibration and those 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.

6.5.3.1 Beta/Photon Dosimeters

Pantex Plant film badges and TLDs were originally calibrated with 60Co and 137Cs sources and

Victoreen R chambers to measure the exposure (MHSMC 1972). Deliberately irradiated film badges 

were sent periodically to R. S. Landauer, Jr., and Company beginning in 1970, and reported doses 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 24 of 69

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

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

and 1980 (see Tables 6-2 and 6-3). Table 6-8 lists sources of bias in the calibration parameters for 

beta/photon dosimeters.

Table 6-8. Common sources of laboratory bias in calibration parameters for beta/photon dosimeters.

a

Parameter Description Anticipated laboratory biasb

Free-in-air 

calibration

In the 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, 226Ra 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 is equivalent 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. 

Mid-cycle calibration minimizes overall 

uncertainty. 

a. Judgment based on Pantex dosimeter response characteristics (BWXT 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 (DOE 1980). A 2-μg 

252Cf source was used to calibrate TLD-600 chips for measuring fast neutron dose (DOE 1980). 

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 (DOE 1980). Calibration methods 

were similar to those used at Sandia. In the mid-1980s, a 0.5-Ci 137Cs source in the 12-10 Building 

was used to calibrate Panasonic UD-802 dosimeters [10]. Element correction factors were 

determined for each chip in each dosimeter, which were used for improved photon dosimetry (BWXT 

Pantex 2002).

Calibrations for the Panasonic UD-802 and UD-809/UD-812 TLD systems occurred in the Pantex 

Radiation Safety Department Calibration Facility. This facility, first used in 1996, has 5- and 0.5-Ci 

137Cs sources, a 120-μg 252Cf source, a dosimetry-type X-ray machine, and two 90Sr and one 204Tl 

sources, which are used for DOELAP calibration and quality control (BWXT Pantex 2001).

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 (DOE 1980). 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 (ORAUT 2003a). Similar calibration procedures were used with the development 

and operation of the 6-element in-house TLD system between 1977 and 1980 (DOE 1980). Table 6-9 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 25 of 69

lists common sources of expected laboratory bias for personnel neutron dosimeters based on 

comparison of the dose of record with Hp(10). 

Table 6-9. 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 (BWXT Pantex 2002).

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

6.5.4 Workplace Radiation Fields

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

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

progeny of those elements, and 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 [11]. Other workplace radiation fields involve industrial radiation-generating equipment 

(X-ray machines and electron accelerators) and isotopic gamma-ray and neutron sources for 

radiography and testing purposes (60Co and 252Cf) [12]. The nuclides in the sealed nuclear weapon 

component pits emit beta, X-ray, gamma, and neutron radiation. From an external dosimetry 

perspective, the radiations of concern are beta particles, photons (gamma and X-rays), and neutrons. 

Radiation exposure to workers depends significantly on the processes in the preparation, design, and 

construction of the weapons [13].

As a good practice to comply with the DOELAP accreditation process for the Panasonic UD-809/

UD-812 TLD system, field measurements were made to characterize radiation fields in the Pantex 

workplace and to document the performance of the dosimetry system (BWXT Pantex 2002). 

Radiation fields were measured with TLDs on a polymethylmethacrylate phantom that were exposed 

under controlled conditions. The radiation fields were also characterized with several instruments to 

measure the photon, neutron, and beta dose rates. Each characterized weapon program was 

measured in each of four configurations: full weapon, physics package, bare pit, and pit in storage 

container (BWXT Pantex 2002). The data derived from these measurements are 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 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 26 of 69

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) (BWXT Pantex 2002). The 

appropriate correction factors were chosen based on gamma spectroscopy measurements during the 

field measurements. Beta dose rates were measured with a Victoreen 450BE instrument with an 

open window (BWXT Pantex 2002). Neutron dose rates were measured with tissue-equivalent 

proportional counters and multisphere measurements were analyzed to characterize the neutron 

spectra (BWXT Pantex 2002).

The predominant source of radiation dose at Pantex is photons from 241Am, with the 60 keV photon 

being the most significant (BWXT Pantex 2002). 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 [14]. 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 sources of beta radiation are DU and thorium (BWXT Pantex 

2002). Total dose rates in the workplace are generally low (less than 10 mrem/hour) unless very 

close work is being performed (BWXT 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 favorable to 

claimants.

6.5.4.1 Depleted Uranium

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

and during and after testing. An important progeny 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, Slaback, and Birky 1998; ICRP 1983). An additional source of exposure in the 

Pantex workplace is from bremsstrahlung that high-Z materials produce during interactions with 

higher energy beta particles. Beta particles emitted by 234mPa excite both bremsstrahlung and 

characteristic X-rays in DU or 238U (Shleien, Slaback, and Birky 1998).

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

taken to protect against exposure. Protective clothing and gloves provide a protection factor of 2 or 

more depending on the thickness (DOE 2001). A bare slab source of DU contributes an Hp(0.07)

dose of approximately 230 mrad/hour at the surface (BRH 1970) in comparison with an Hp(10) dose 

of approximately 2 mrad/hour (NIOSH 2010b). However, based on a review of shallow and deep 

dosimetry data, significant beta exposures to Pantex workers were rarely detected by film badges or 

TLDs [15].

6.5.4.2 Photon Radiation

Photon radiations at Pantex have had widely varying energies that have ranged from about 30 keV to 

a few MeV [16]. Sources of photon radiation have included weapon components, analytical devices 

that use X-rays from radiation-generating devices, and low-activity radioactive sources such as those 

used to check or calibrate radiation detectors [17]. These sources could have included alpha, beta, 

photon, and neutron emitters and were of the types and source strengths typical of mainstream 

industrial or process-related users [18]. Doses from the proper and widespread use of small check 

sources are negligible.
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 27 of 69

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 

is purified [19]. However, 241Am starts growing in immediately as its parent radionuclide 241Pu decays 

with a half-life of 14.4 years. The 241Am, which emits 60 keV photons, reaches a maximum activity 

after about 80 years, but it reaches about 85% of this maximum in 40 years [20]. Therefore, for 

nuclear weapons activities, this is increasingly significant with weapons disassembly, which often 

occurs many years after assembly [21].

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 1988, p. 237). The governing 

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

228Th is 1.9 years 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 years, and rise to nearly 

complete equilibrium after 20 years (Stannard 1988). 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, Slaback, 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 (Booth et al. 2005). 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 on a logarithmic vertical axis. Note the smooth 

bremsstrahlung spectrum, the uranium characteristic K X-rays at 90 to 109 keV, and the L X-rays in 

the range of 13 to 19 keV. The vertical axes in Figures 6-6 through 6-8 represents the energy of the 

photon emission (i.e., MeV per photon emission). 

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 (calculations made using Booth et al. 2005).

The linear vertical axes in Figures 6-7 and 6-8 show the bremsstrahlung and characteristic X-ray 

components, respectively, of the calculated spectrum in Figure 6-6. The average energy of the 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 28 of 69

photon spectrum is 0.41 MeV. The spectrum below 30 keV is insignificant [22]. The characteristic 

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

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 (calculations made using Booth et al. 2005).

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

linear vertical axis (calculations made using Booth et al. 2005).

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 [23]. Assembled weapon 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 29 of 69

 

components were encased in a metallic cladding that significantly attenuated photon radiation 

(particularly at lower energies) (Shleien and Terpilak 1984). Measured photon energy spectra in 

Pantex workplaces have confirmed that a major fraction of the photon dose rate near weapons is from 

the 60 keV photons from 241Am (BWXT Pantex 2002).

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

concrete. Most elements that constitute ordinary concrete have a low Z. The elemental composition 

of concrete is 50% oxygen (Z = 8) and 32% silicon (Z = 14) (Shleien, Slaback, and Birky 1998). 

Higher energy photons scatter within such a facility lose energy in each collision and result in photons 

of lower energy. Gamma radiation of 2.2 MeV results from 1

H (n,γ) 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, Slaback, 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 range of 30 to 250 keV [24]. An assumption that all photons are in 

this range is a simplifying conservative assumption that is generally favorable to claimants.

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 (BWXT Pantex 2001). The specific workplace neutron fields for selected types of 

nuclear weapon components are classified. Unclassified information on neutron spectra from fission 

and sealed plutonium sources is available.

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

sealed or encapsulated (Carr 2004). Assembly and disassembly operations that occur in cells 

comprise the only times workers have been exposed to neutrons from bare pits [25]. 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 

energies. In the workplace, these spectra are significantly changed through scattering in nuclear 

weapon components, equipment, and building materials [26]. The UD-809/UD-812 dosimeter system 

was designed and calibrated for neutrons in the Pantex workplaces (BWXT Pantex 2002).

Maximum radiation dose rates occur when workers handle bare pits [27]. The operations often 

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

approximately 30 cm [28]. Lead aprons or other shielding has been used to reduce photon dose 

rates. In other assembly or disassembly operations, where HE or other materials surround the pit, 

photon and neutron dose rates decrease significantly, although photon dose rates decrease more 

rapidly with increased shielding [29].

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 favorable to claimants. Although 

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

causation for deeper organs (such as the liver) is much larger from the higher neutron fluence in the 

0.1 to 2 MeV range than in any other energy group (NIOSH 2007). Radiation fields characteristic of 

Pantex facilities (beta/photon and neutron) can be generally defined based on historical information 

on processes, locations, operating periods, and radioactive materials in each, as listed in Table 6-10.
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 30 of 69

 

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 Dosimeter Response to Radiation Fields

6.5.5.1 Beta/Photon Film Dosimeter Response

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 [35]. 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 (AEC 1955). The open window enabled 

measurement of beta particles and lower energy photons. The plastic filter enabled measurement of 

intermediate-energy photons, and the metal filter enabled measurement of higher energy photons 

(1 cm depth) (AEC 1955).

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

keV X-rays, 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 over-response 

(in the 100 to 200 keV region) tended to yield conservatively high results. This testing, in combination 

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

dosimetry systems, leads to the conclusion that film-badge measured photon doses at Pantex 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 over-response to photons in the 

100 to 200 keV energy region [36].
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Table 6-10. 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

Bays, cells Assembly/ 

disassembly of 

nuclear weapons

1958–2005 Tritium Beta <15 keV 100c

Bays, cells Assembly/ 

disassembly of 

nuclear weapons

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

Neutrons 0.1–2 MeV 100d

Bays, cells Assembly/ 

disassembly of 

nuclear weapons

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, 

nondestructive 

examination

Radiography 1952–2005 Weapon 

components

Photons 30–250 keV 100b

Neutrons 0.1–2 MeV 100d

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

Warehouse, 

production stores

Packaging 

components

1958–2005 Tritium Beta <15 keV 100c

a. Workplace beta radiation has energy greater than 15 keV [30].

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 favorable to claimants [31].

c. Beta particles from tritium are classified in the “less-than-15 keV” category [32].

d. The energy of neutrons in the workplace is predominately in one of two ranges: 0.1 to 2 MeV or 2 to 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 favorable to 

claimants [33].

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 

its progeny 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 [34].

Table 6-11 summarizes typical beta/photon personnel dosimeter parameters important to Hp(10)

performance in the workplace.

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 Harshaw Model 2000 TL analyzer system (DOE 1980). 

The first PPDs had open windows for beta and lower energy photons (7 mg/cm2

) and a window of 
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 32 of 69

Table 6-11. Typical workplace beta/gamma dosimeter Hp(10) performance.

a

Parameter Description Potential workplace biasb [37]

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 dosimeter response characteristics and workplace radiation fields (BWXT Pantex 2002).

b. Dose of record in comparison with Hp(10).

290 mg/cm2 Al (DOE 1980). 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 measurement of the whole-body (deep) dose, Hp(10) (see Figure 6-3).

The Panasonic UD-802 system 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, 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 [38].

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, during the entire period from 1952 to the present 

at Pantex, film badges and TLDs responded adequately to the 60 keV photons from 241Am, and the 

film badges probably over-responded to photons between 100 and 200 keV [39]. Based on this 

information, the photon dose of record is likely to be favorable to claimants, assuming the dose of 

record is adjusted upward for missed dose (i.e., recorded zero dose when less than MDL) [40].

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

are normally worn on the front of the torso [41]. An assumption that exposure orientations are 

100% AP is a simplifying and conservative assumption that is generally favorable to claimants. 

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 benchtop) 

then a correction factor should be applied in accordance with the guidance of OCAS-TIB-0010, Best 

Estimate Dose Reconstruction for Glovebox Workers (NIOSH 2011).
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6.5.5.3 Neutron Dosimeter Response

Tracerlab provided NTA film dosimetry service from 1958 through April 1963 (ORAUT 2003b). 

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 1973, Landauer provided similar services (Adams 2003). 

MRDs were 20 and 10 mrem, respectively, for fast and thermal neutrons.

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 6-12. Testing of NTA 

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

neutron doses were probably underestimated (ORAUT 2006c). Based on this, correction factors are 

applied to the recorded NTA film results to account for threshold response (1.4), angular dependence 

(1.33), and uncorrected fading (1.56). Combining these factors, the total correction factor of 2.9 is 

applied to the NTA film results in addition to the International Commission on Radiological Protection

(ICRP) correction factor (1.91) (ORAUT 2016).

Table 6-12. Typical workplace neutron dosimeter performance (BWXT Pantex 2002).

a

Parameter Description Potential workplace biasb [42]

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 

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 dosimeter response characteristics [43].

b. Dose of record in comparison with Hp(10).

The in-house TLD system used at Pantex from 1974 to 1980 responded well to thermal neutrons but 

under-responded to neutrons with energies above about 10 keV (Thompson 1977). Therefore, 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 bare and moderated 252Cf sources. These measurements showed that 

the UD-802 significantly under-responded to fast neutrons; therefore, UD-802-measured neutron 

doses between 1980 and 1993 are likely to be underestimated. DOELAP accredited the Panasonic 

UD-809/UD-812 TLD system in 1993 for all neutron categories applicable at Pantex. Measured 

neutron doses at Pantex since 1994 are reliable and dose reconstructors should use the dose of 

record [44]. In addition, the Pantex site retrospectively reanalyzed all neutron dosimeter results from 

1974 through 1993 using the dosimeter algorithm that was accredited by DOELAP. These results 

have been linked to individual worker records and should be used for dose reconstruction [45].
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6.5.5.4 Neutron Dose Weighting Factor

An adjustment to the neutron dose is necessary to account for the change in neutron quality factors 

between historical and current scientific guidance, as discussed in NIOSH (2007). At Pantex, TLNDs 

were calibrated with measurements based on fluence-to-dose conversion factors and quality factors 

similar to those from ICRP Publication 21 (ICRP 1973) and National Council on Radiological 

Protection and Measurements (NCRP) 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 6-10 compares NCRP (1971) 

quality factors to those used in Pacific Northwest National Laboratory (PNNL) measurements at the 

Y-12 National Security Complex (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 6-10, for each 

neutron energy group used to define the radiation weighting factors in ICRP (1991).

Figure 6-10. Comparison of neutron quality factors used in PNNL 

neutron spectrum measurements (Soldat et al. 1990) 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 workers. 

Table 6-13 summarizes the group-averaged NCRP (1971) quality factors that were 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).

Table 6-13 lists average quality factors for the four energy groups for inputting dose to IREP, 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 (ORAUT 2006d):

( ) (6-1) ( )

( ) ( ) R n

f n f n

avg n

w E C E D E

Q E

= ×
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Table 6-13. 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 Not applicable Not applicable Not applicable

10 keV–100 keV 10 5.38 10 1.86

100 keV–2 MeV 10 10.49 20 1.91

2 MeV–14 MeV 10 7.56 10 1.32

14 MeV–60 MeV 10 Not applicable 5 Not applicable

a. First Tripartite Conference in 1949 (Warren et al. 1949; Fix, Gilbert, and Baumgartner 1994).

b. ORAUT (2009).

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. 

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 6-10 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 before 1994 using the ICRP (1991) correction factor from Table 6-14. 

Beginning on January 1, 2010, Pantex incorporated the ICRP correction factor into the reported 

neutron doses. Therefore, the correction factor is not applied for any reported doses after 2009.

Table 6-14. Neutron dose energies, percentages, and associated correction factors for nuclear 

weapons component assembly and disassembly. 

Process

Neutron energy

(MeV)

Default dose 

fractiona (%)

Correction factor 

from Table 6-13

Nuclear weapons component assembly 0.1–2 MeV 100 1.91

a. The assumption (see Table 6-10) that all neutron energies are between 0.1 and 2 MeV typically results in a higher 

organ dose assignment and is therefore favorable to claimants.

6.5.5.5 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 [46]. Monitored 

radiation doses for radiographers in the early years were usually zero [47]. In the late 1950s when 

work with pits began, there were higher measured photon radiation doses and workers began wearing 

lead aprons [48]. However, the use of lead aprons was not included in procedures until the mid1980s [49]. Workers wearing aprons were instructed 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” 

(BWXT Pantex 2002). However, there was no enforcement to ensure that dosimeters were worn 

under the apron [50].

Three types of lead aprons have been worn by Pantex workers over the years (Passmore 1995a,

1995b, 1995c). Some covered only the front of a worker’s body. Some covered the front and back 

but not the sides. In 1995, the use of aprons that wrap entirely around the body began, but use of the 

other two types continued. Figure 6-11 shows the areas of the body a lead apron typically covers 

(Memmler and Rada 1970).
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Figure 6-11. Body areas covered by lead apron 

(skeletal figure from Memmler and Rada 1970).

In 1995, a series of studies were performed at Pantex on the effects of apron use on dosimeter 

readings (Passmore 1995a, 1995b, 1995c). The studies placed a dosimeter on the front of a phantom 

in an aisle 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 included the 2.2 MeV photons 

that are generated when a thermal neutron is captured by hydrogen [51]. This exposure scenario was 

chosen to represent the radiation fields where lead aprons were least effective in reducing photon 

dose [52]. Dose measurements were made with no apron and with the dosimeter under and over 

each type of apron. The results summarized in Table 6-15 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.
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Table 6-15. Percent reduction in measured photon dose provided by lead aprons

(Passmore 1995a, 1995b, 1995c).

Apron type

Apron thickness

(mm lead equivalent)

Dosimeter locationa

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.

Production technicians, material handlers, radiography technicians, and quality control technicians 

routinely wore aprons during work in the 1980s and 1990s, and perhaps earlier [53]. More recently, 

the use of lead aprons has been required by procedure and enforced by management. Production 

technicians and material handlers in facilities that contained plutonium generally wore aprons [54]

while workers in other job classifications did not.

An adjustment factor was derived from the largest relevant dose reduction data in Table 6-15 and 

applied to the location of cancer sites listed in Table 6-16 [55]. 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 [56]. If a worker received dose while not wearing an apron, applying this factor of 1 

to the measured dose is still favorable to claimants. If the cancer site is in an area not protected by a 

lead apron, an adjustment factor of 1.5 should be applied regardless of the location of the dosimeter 

[57].

Table 6-16. 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
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ICD-9 code Cancer description Cancer sitea

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

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.

6.6 ANALYSIS OF CLAIMS FILED BY PANTEX WORKERS

An analysis of job titles, worker classifications, and external dose parameters from Pantex claims was 

performed to better determine dose reconstruction recommendations. There are three primary 

sources of information in each claim that provide information of interest to reconstruction of external 

dose: (1) DOL claim documentation; (2) DOE medical X-ray, dosimetry, and incident archive records; 

and (3) records of interviews with claimants and coworkers, as available. This information is used to 

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 

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 [58].
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6.6.1 Years with a Claim

A sample of 316 claims that were filed with the U.S. Department of Labor (DOL) by Pantex workers 

was analyzed to examine trends in the data. These claims were assembled into a dataset with one 

line of data for each year of employment for each worker. Information for workers that had more than 

one job title in a given year was entered into additional lines. Overall, a total of 6,396 lines of data 

was assembled for the 316 claims. Claimants reported a total of 692 different job titles or job codes. 

The average period of employment for workers was 20.2 years [59]. The records (with and without a 

recorded radiation dose) were examined for each year for the respective claims. Figure 6-12 

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.

Active Claims

0

50

100

150

200

250

1940 1950 1960 1970 1980 1990 2000 2010

Year

Frequency

Active Claims

Figure 6-12. Frequency distribution of claims that encompass the respective years [61]. 

6.6.2 Collective Dose by Job Title

Analysis of the available claim documentation showed a wide spectrum of job titles and job 

descriptions for the workers. 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 workers during the years of employment [60]. Similar job titles were 

grouped into the assigned job titles listed in Table 6-17, and collective photon and neutron doses were 

tabulated to examine the dose distribution in relation to job titles [62]. This analysis confirmed that 

most of the collective dose was received by assembly, inspection, and warehouse operators, who 

were generally designated as radiation workers. Another interesting feature of these data is the 

nearly equal collective photon and neutron doses that were 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 [63].

6.6.3 Analysis of Recorded Doses

Radiation doses were examined for these workers for years before March 1989, when monitoring 

began for all employees. A total of 1,754 lines of data showed recorded doses (including zeros) for 

monitored workers and accounted for about 27% of the data. A total of 3,577 lines of data had no 

recorded doses (blank), which represented unmonitored workers and accounted for about 56% of the 
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Table 6-17. General categories of job titles for Pantex workers and recorded collective 

doses (person-mrem) [64].

Category of job title

Collective photon dose Collective neutron dose

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 Not applicable 38,414 Not applicable

data. The remaining 1,065 lines of data represent workers who were monitored after March 1989 and 

accounted for about 17% of the database. Overall, about 44% of the records contained results 

(including zeroes) of dose monitoring (i.e., 2,819 lines, the sum of 1,754 and 1,065 lines from before 

and after March 1989, respectively). Further analysis of monitored worker data (2,819 lines) showed 

that about 48% had nonzero recorded doses. The recorded photon and neutron collective dose for 

the Pantex claims is presented in Figure 6-13. 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 a few workers [65]. 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.

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 6-13. Distribution of annual photon and neutron dose for Pantex claims. 
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An attempt was made to associate group job titles with specific worker job activities that were 

expected to involve radiation exposure. However, meaningful analysis was not feasible with the data 

available because worker job titles changed significantly over the years and many workers held 

several titles during their employment at Pantex. It is evident that the respective workers represent a 

broad spectrum of work functions at Pantex.

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 

[66]:

• Dose to unmonitored workers with potential for occupational external exposures 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), and

• Unmeasured neutron dose to monitored and unmonitored workers.

6.7.1 Unmonitored External Dose

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 [67]. A detailed statistical analysis of the available external monitoring results for the 

Pantex Plant was published in ORAUT (2016). The analysis for ORAUT-OTIB-0086, Pantex External 

Coworker Model, resulted in the development of unmonitored photon, electron, and neutron doses 

which are listed in Attachment A. It is recommended that dose reconstructors assign a dose to an 

unmonitored worker, who would otherwise be monitored by today’s standards, equal to the geometric 

mean or 95th-percentile coworker doses for each year of unmonitored employment [68] for the 

operational years through 1988 (i.e., 1952 through 1988). This is favorable to claimants because 

unmonitored workers are expected to have lower exposure because Pantex practice was to monitor 

all radiation workers before March 1989. For years before 1960 when no measured gamma dose 

equal to or greater than 40 mrem was measured, dose reconstructors should use the median dose for 

1960 for each year of employment [69]. In presumptively noncompensable cases, unmonitored doses 

can be applied for periods after 1988 if deemed warranted by the dose reconstructor.

6.7.2 Adjustment for Protective Lead Aprons

Adjustment to dose for use of protective lead aprons depends on the location of the cancer site as 

determined from Figure 6-11 [70]. The aprons covered the body from the shoulders to below the 

knee, but not the arms. 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 dosimetermeasured dose might be too low, the recommended adjustment factor is 1.5, as described in 

Section 6.5.5.6. This factor is applied to all measured and missed dose components. The adjustment 

is not applied to unmonitored external doses listed in Tables A-1 through A-3. In the absence of 

extremity monitoring information, dose reconstructors should apply the higher of the recorded shallow 

dose or the 95th-percentile external shallow dose for the skin of the hands and forearms.
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6.7.3 Photon and Neutron Dose Adjustments

Pantex worker neutron dose measurements made with the Panasonic UD-809/UD-812-accredited 

and workplace performance-validated TLND implemented in 1994 are considered accurate [71]. NTA 

film neutron dose results are adjusted by the factor of 2.9 as discussed in Section 6.5.5.3 from 1958 

through 1976. For 1977 through 1993, the doses recalculated using the Stanford algorithm are 

considered accurate and are used for reconstructing worker doses.

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 as outlined 

in Section 6.8. 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.

2. Details in the claim file and/or interview should be used to determine if unique work activities 

and exposure geometries should be a consideration, particularly for non-uniform fields 

generally associated with bench-top operations. For example, information in some worker’s 

files indicated that they performed pit maintenance operations with the pit on their lap in a 

sitting position. This could result in a low bias to the organs of the lower torso. In these cases, 

the 95th-percentile glovebox correction factor listed in NIOSH (2011) are recommended to 

ensure an analysis favorable to the claimant. This type of activity was generally limited to a 

relatively small fraction of time during the average workday. Because of this, a scaling factor 

should be applied to the 95th-percentile glovebox correction. For example, the actual pit 

handling activity probably took no more than one to two hours per day. Assuming that the 

claimant actually performed pit handling maintenance operations for one hour per day, five 

days per week, the appropriate correction to apply would equate to the 95th-percentile 

correction multiplied by 0.125 (5 hours per day divided by the 40 hour work week). If the 

worker’s dosimetry records indicate that they were monitored for extremity doses, the 

extremity dosimetry records may represent a more accurate indication of the actual dose to 

the lower torso organs than the whole body dosimeter worn underneath a lead apron worn at 

the chest or collar level. In such cases, the uncorrected extremity dose applied to the lower 

torso organ shall be compared to the lower torso organ dose determined using the whole-body 

dosimeter result obtained using the scaled 95th-percentile correction factor. The highest dose 

to the lower torso organ should be assigned for the dose reconstruction. In either case, the 

correction should be applied using a constant distribution for measured dose and a lognormal 

distribution with a geometric standard deviation of 1.520 for missed dose.

3. From 1974 through 2009, no adjustment in measured neutron dose is needed other than 

standard adjustments for dosimeter response uncertainty and the ICRP Publication 60/NCRP 

Report 38 neutron weighting factors adjustments from Table 6-14 (ICRP 1991; NCRP 1971). 

For 2010 and later years, the site incorporated the ICRP weighting factor into the reported 

dose. Therefore, additional weighting factors are not required after 2009.

6.7.4 Skin Dose

For years before 1981, the skin dose records included only beta doses [72]. For 1981 and 

subsequent years, the skin dose has been calculated as the sum of the beta, gamma, and neutron 

doses. In cases where no nonpenetrating dose was recorded, the skin dose is assumed to be equal 

to the whole-body penetrating dose [73]. Based on this, recorded deep doses for 1981 and earlier 

should not be subtracted from the reported shallow dose. For 1981 and subsequent years of 

employment, electron doses are the difference between the reported shallow and deep doses and 

should be applied with an energy range of 100% >15 keV. Additional guidance on determining skin 
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dose can be obtained from ORAUT-OTIB-0017, Interpretation of Dosimetry Data for Assignment of 

Shallow Dose (ORAUT 2005).

6.7.5 Extremity Dose

Wrist-type extremity dosimeters have been assigned to radiation workers who directly handled 

nuclear weapon components, such as pits (BWXT Pantex 2002). Since 1980, a Panasonic UD-802 

dosimeter with a wristband has been used for extremity dose monitoring [74]. Between 1972 and 

1980, a wrist-type TLD badge was used; before 1972, a wrist-type film badge was used [75]. More 

recently (since 1991), two UD-802 wrist dosimeters (labeled right and left) have been assigned to 

radiation workers for use when working “hands on” with pits, uranium, or thorium components (BWXT 

Pantex 2002).

The actual use of extremity dosimeters at Pantex has not always been rigorously managed, and there 

were times when workers did not wear the assigned extremity dosimeters [76]. If an extremity 

dosimeter was worn and the measured dose was less than the skin dose measured by the wholebody dosimeter, the assumption was made that the extremity dosimeter was not worn at least part of 

the time; therefore, 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 (BWXT Pantex 2002).

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. Wrist doses measured 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 10 between whole-body and 

extremity exposures (Battelle 2006, p. 5). That is, if the measured contact dose rate is 10 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 10 and the result assigned as a conservative extremity dose.

Examination of the worker data revealed that, of 316 claims, only 42 had recorded extremity dose 

data greater than 100 mrem in a given year [77]. 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 10 can be 

used, if necessary.

6.7.6 Radiation Dose Fraction

Table 6-10 summarizes the recommended fractions for Pantex dose according to facility, worker 

occupational classification, and IREP-required energy categories. Because of the uncertainty in 

actual workplace fields, the energy fractions for worker dose estimation in Table 6-10 are 

recommended:

• 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 estimates of organ dose that are favorable to claimants.
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6.7.7 Organ Dose

Once the adjusted doses have been calculated for each year, the values are used to calculate organ 

doses of interest using NIOSH (2007). Consistent with NIOSH direction, it is recommended that the 

100% AP (front-to-back) geometry should be assumed for the irradiation geometry and for conversion 

to organ dose. Exceptions to this include the red bone marrow, esophagus, lung, and bone surface. 

To determine the organ dose conversion factor most favorable to the claimant, a comparison must be 

made between the AP and ROT exposure geometries. For photon doses, the exposure to organ dose 

conversion factor should be applied through 1972 and the personal dose equivalent [Hp(10)] should 

be applied for 1973 and all subsequent years [78]. The deep dose equivalent Hp,slab(10) dose 

conversion factor should be used for neutron doses for all years.

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 2006a). The estimated uncertainty in TLD-recorded 

doses is ±20% before 1994 (ORAUT 2006b) and ±10% for 1994 and after (BWXT Pantex 2002).

The correction factor of 2.9 accounts for uncertainties in neutron doses during the NTA film period 

(i.e., through 1973). Therefore, no uncertainty corrections should be applied to NTA film neutron dose 

results. For all other years, the neutron dosimeter results are accurate to ±30% based on DOELAP 

performance testing (ANSI 1993). Therefore, an uncertainty correction of ±30% should be applied to 

the recorded neutron dose results for the years of 1974 through the present.

6.9 ATTRIBUTIONS AND ANNOTATIONS

Where appropriate in this document, bracketed callouts have been inserted to indicate information, 

conclusions, and recommendations provided to assist in the process of worker dose reconstruction. 

These callouts are listed here in the Attributions and Annotations section, with information to identify 

the source and justification for each associated item. Conventional References, which are provided in 

the next section of this document, link data, quotations, and other information to documents available 

for review on the Project’s Site Research Database (SRDB).

Jerry Martin served as the initial Document Owner of this TBD. Mr. Martin was previously employed 

at Pantex and his work involved management, direction, and implementation of radiation protection 

and/or health physics program policies, procedures, or practices in relation to atomic weapons 

activities at the site. This revision has been overseen by a new Document Owner, who is fully 

responsible for the content of this document, including all findings and conclusions.

[1] Martin, Jerome B. Oak Ridge Associated Universities (ORAU) Team. Senior Health Physicist. 

August 2006.

A larger fraction of the workers received nonzero external doses between 1960 and 1980, 

which was determined by inspection of Figure 6-1.

[2] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

AEC Manual Chapter 0524 (e.g., AEC 1958) required personal external dosimetry for radiation 

workers with the potential to exceed 10% of the RPG of 5 rem/year. A comparison of the data 

in Table 6-2, Table 6-3, and Figure 6-1 for monitored workers to the total plant population 

generally indicated that radiation workers with a potential to exceed 500 mrem/year were 

monitored while other workers were not.
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[3] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The dosimeter exchange frequency was determined from dosimetry reports (Tracerlab 1962–

1963; Ashton 2003; Adams 2003).

[4] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Examination of external dosimetry reports (Tracerlab 1962–1963; Ashton 2003; Adams 2003; 

ORAUT 2003b) revealed that results less than the MRD were recorded as zero. Any results 

equal to or greater than the MRD were reported as nonzero results.

[5] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Pantex received its DOELAP certificate indicating successful completion of testing of the 

UD-809/UD-812 TLD system in all beta, photon, and neutron radiation testing categories on 

September 1, 1993 (personal knowledge).

[6] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The discussion of UD-809 TLD elements is from BWXT Pantex (2002); however, the element 

numbers E5 through E8 are used here instead of E1 through E4 to distinguish between the 

similar element numbers in the UD-812 TLD.

[7] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

An examination of the collective neutron and collective gamma doses in Table 6-17 and their 

ratios indicates trends in the ratios as stated in the text. The improved TLD and TLND used 

between 1974 and 1993 (see Table 6-7) gave an overall ratio of 0.266, which is similar to the 

0.25 ratio obtained with the DOELAP-accredited UD-809/UD-812 TLND system currently 

used.

[8] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The ratios in Table 6-7 have increased with improvements in the dosimetry systems.

[9] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

A calculation of neutron-to-photon dose ratios for the data in Figure 6-5 shows that the ratios 

after about 1985 are fairly constant, while the ratios before 1985 are quite variable.

[10] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

A 0.5-Ci 137Cs source in the 12-10 Building was used to calibrate the UD-802 dosimeters from 

the mid-1980s to 1996, when the Radiation Safety Department Calibration Facility was 

commissioned (ORAUT 2003a).

[11] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The highest dose rates are encountered when handling bare pits. In all other configurations 

(full weapons, physics packages, or pits in storage containers), some shielding is provided that 

reduces the dose rates to workers.

[12] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Information on other radiation fields at Pantex is based on personal knowledge of radiationgenerating machines and the radioactive materials inventory.

[13] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Radiation dose rates vary considerably with the different weapon designs. Dose rates also 

vary during assembly and disassembly as components that provide shielding are added or 

removed (personal knowledge).
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[14] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Radiation dose rates decrease during assembly as components that provide shielding are 

added (personal knowledge).

[15] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The statement about beta exposures being rarely detected by film badges or TLDs is based on 

personal knowledge of routine annual analyses of exposure data relative to worker 

assignments to ensure proper assignment of radiation worker status and the type of dosimeter 

to provide.

[16] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Of the various photon radiation sources at Pantex, the lowest energy (about 30 keV) is 

produced by X-ray diffraction machines and the highest energy (2.6 MeV) is produced by the 

thorium decay product 208Tl.

[17] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Information on sources of photon radiation at Pantex is based on personal knowledge of 

radiation-generating machines and the radioactive materials inventory.

[18] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Information on radiation sources at Pantex is based on personal knowledge of the radioactive 

materials inventory.

[19] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

When plutonium metal is purified, its decay products and other radionuclides are removed. 

However, weapons-grade plutonium contains several isotopes of plutonium, including varying 

amounts of 238Pu, 239Pu, 240Pu, 241Pu, and 242Pu. With a half-life of 14.4 years, 241Pu 

immediately begins to decay to 241Am.

[20] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

With a half-life for 241Pu of 14.4 years, 241Am will reach equilibrium in about 80 years, but it will 

reach about 80% of this maximum in 40 years.

[21] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Disassembly of nuclear weapons often occurs 20 or more years after assembly. The longer 

the interval between assembly and disassembly, the more significant the exposure from 241Am 

photons.

[22] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

As can be seen in Figure 6-8, there are very few photons with energies less than 0.05 MeV 

(50 keV).

[23] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Disassembly of nuclear weapons often occurs 20 or more years after assembly. The longer 

the interval between assembly and disassembly, the more significant the exposure from 241Am 

photons.

[24] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Of the various photon radiation sources at Pantex, the lowest energy (about 30 keV) is 

produced by X-ray diffraction machines and the highest energy (2.6 MeV) is produced by the 

thorium decay product 208Tl. The predominant source of radiation dose at Pantex is photons 

from 241Am, with the 60 keV photon being the most significant. Although there are photons 

with energies greater than 250 keV in the Pantex workplace, the dose workers received from 
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higher energy photons is insignificant in comparison with the dose from 60 keV photons. An 

assumption that all photons are in the 30 to 250 keV range is a simplifying assumption that is 

generally favorable to claimants.

[25] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Bare pits are only handled in cells. Pits are surrounded by other weapon components or 

storage containers in all other Pantex facilities.

[26] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The spectra shown in Figure 6-9 are unmoderated neutrons. In the workplace, with 

moderation caused by nuclear weapons components, equipment, and building materials, the 

moderated spectra are shifted to lower energies.

[27] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Radiation dose rate surveys are routinely conducted in Pantex workplaces where radioactive 

materials are handled or radiation-generating machines are operated. The highest radiation 

dose rates to workers usually occur when workers handle bare pits. In all other workplace 

scenarios, bare pits are covered by some shielding material, which reduces the dose rate to 

workers.

[28] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Workplace measurements have been made to simulate typical worker exposure scenarios. 

The nominal distance from the surface of a pit to the worker’s dosimeter location is 30 cm 

during hands-on operations.

[29] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

When any shielding or moderating material is added to a bare pit, both the photon and neutron 

dose rates are decreased, but the lower energy photon dose rates are reduced the most.

[30] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Although there are some beta particles emitted by DU and its progeny that have energies less 

than 15 keV, these lower energy beta particles cannot penetrate the dead layer of the skin and 

do not contribute to external dose.

[31] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Table footnote b is the explanation for the recommended simplifying assumption.

[32] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The maximum energy of beta particles from tritium is 18 keV and the average energy is 6 keV. 

Most of the beta particles from tritium are less than 15 keV. In any case, beta particles from 

tritium do not contribute to external dose.

[33] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Although there are neutrons with higher energies (which are more penetrating) at Pantex, the 

probability of causation for deeper organs (such as the liver) is much larger from the higher 

neutron fluence in the 0.1 to 2 MeV range than in any other energy group (NIOSH 2007).

[34] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

This conclusion was reached by review of AEC (1955) and inspection of Figure 6-2 that shows 

an over-response to photons with energies greater than 30 keV for the multielement film 

dosimeter that was used at Pantex from 1958 to 1976. The two-element film dosimeter, which 

was used at Pantex between 1952 and 1958, shows a slight under-response at 60 keV but an 

over-response to photons between 70 and 200 keV.
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[35] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The three companies that provided film badge service to Pantex between 1952 and 1976 were 

Tracerlab, Eberline, and Landauer. A review of the radiation dosimetry reports from all three 

suppliers and the explanatory notes on the back of each page of the reports indicated the 

frequency of exchange, film type, absorbers, MRDs, energy response, units of exposure, and 

other factors that demonstrated the similarities between the services.

[36] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Table footnote e is the explanation for the recommended simplifying assumption.

[37] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The statements about potential workplace dosimeter bias are based on Tables 8.1, 8.2, and 

8.3 in Wilson et al. (1990). Professional judgment was used to evaluate dosimeter response in 

Hanford facilities and predict the potential workplace dosimeter bias. The same method was 

used to evaluate dosimeter response to Pantex workplace radiation fields and to predict 

potential workplace dosimeter bias.

[38] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

On September 1, 1993, Pantex received its DOELAP certificate indicating successful 

completion of testing of the UD-802 TLD system in all beta and photon radiation testing 

categories, and of the UD-809/UD-812 TLD system in all beta, photon, and neutron radiation 

testing categories (personal knowledge).

[39] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

This conclusion was reached by review of AEC (1955) and inspection of Figure 6-2 that shows 

an over-response to photons with energies greater than 30 keV for the multielement film 

dosimeter that was used at Pantex from 1958 to 1976. The two-element film dosimeter, which 

was used between 1952 and 1958, shows a slight under-response at 60 keV but an overresponse to photons between 70 and 200 keV.

[40] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The photon dose of record is considered to be reliable. If additions to the dose of record are 

made to account for missed dose, the adjusted dose is likely to be favorable to claimants.

[41] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

In most Pantex workplace scenarios where workers handle radioactive materials, they do so 

while facing the source in an AP orientation and they routinely wear the dosimeter on the front 

of the torso. An assumption that the exposure orientations are 100% AP is a simplifying and 

conservative assumption that is generally favorable to claimants.

[42] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The statements about potential workplace dosimeter bias are based on Tables 8.1 through 8.3 

in Wilson et al. (1990). Professional judgment was used to evaluate dosimeter response in 

Hanford facilities and predict the potential workplace dosimeter bias. The same method was 

used to evaluate dosimeter response to Pantex workplace radiation fields and to predict 

potential workplace dosimeter bias.

[43] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The statements about potential workplace dosimeter bias are based on Tables 8.1 through 8.3 

in Wilson et al (1990). Professional judgment was used to evaluate dosimeter response in 

Hanford facilities and predict the potential workplace dosimeter bias. The same method was 

used to evaluate dosimeter response to Pantex workplace radiation fields and to predict 

potential workplace dosimeter bias.
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[44] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

On September 1, 1993, the UD-809/UD-812 dosimeter used by Pantex was accredited by 

DOELAP in all neutron categories tested. Neutron doses measured and recorded at Pante

since 1994 are reliable, and the dose of record should be used in dose reconstructions.

x 

[45] Thomas, Dale D. III. ORAU Team. Senior Health Physicist. December 2013.

The Pantex site retrospectively processed all neutron dosimeter results for 1977 through 199

using the revised dosimeter algorithm that was accredited by DOELAP. These revised result

have been linked to the individual worker records and should be used for external dose 

reconstruction.

2 

s 

[46] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Most radiography was done with radiography machines or sources inside shielded rooms, in 

which case the radiographers were outside the shielded room during radiation exposures and

lead aprons were not worn. In some limited situations, radiography was done with portable 

X-ray machines or sources where a shielded room was not available. In these cases, the 

radiographers were supposed to wear lead aprons, but it was not required by procedure or 

enforced.

[47] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

From 1952 to 1957, only radiographers were assigned dosimeters, and the recorded doses 

were mostly zeros.

[48] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

In 1958, Pantex began to assemble nuclear weapons with pits from the Rocky Flats Plant. 

Higher photon dose rates were measured by radiation surveys, and lead aprons were provided 

to radiation workers.

[49] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The Pantex as low as reasonably achievable program and increased awareness of radiation 

exposure in the mid-1980s led to the revision of Pantex procedures to require the use of lead 

aprons while handling bare pits.

[50] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

In 1994, with the introduction of the UD-809/UD-812 TLD system and increased concern about 

the accurate reading of neutron dose, the requirement to wear the dosimeter under lead 

aprons was explained and enforced (personal knowledge).

[51] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The photon spectrum from older pits includes a significant component of 60 keV photons from 

241Am. The steel pit storage cans effectively attenuate the lower energy photons from pits and 

“harden” the spectrum. Neutrons from pits interact with low-Z materials in the pit storage 

igloos and produce 2.2 MeV photons by the neutron moderation reaction.

[52] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

A lead apron is most effective for attenuating low-energy photons (Shleien, Slaback, and Birky 

1998). A lead apron is far less effective for attenuating the higher energy photons described in 

attribution 69.

[53] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Production Technicians, Material Handlers, Radiography Technicians, and Quality Control 

Technicians are the job titles most often designated as radiation workers at Pantex. Lead 

aprons were provided to radiation workers for pit handling during weapon disassembly in the 
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1980s and 1990s. Lead aprons were also available at earlier times, but records about their 

use were not found.

[54] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Lead aprons were most often used during the handling of plutonium pits, and this work was 

done by Production Technicians and Material Handlers. Workers who did not handle 

plutonium pits were not required to wear lead aprons.

[55] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The purpose of the conservative adjustment factor is to take into account various effects that 

occur with three different kinds of lead aprons and the dosimeter location (under or outside the 

apron). A dosimeter under a lead apron measures a lower dose than one outside an apron, 

and the lower dose varies depending on the thickness and type of apron. The data in 

Table 6-15 indicate a maximum reduction of 35% in the measured photon dose from use of a 

lead apron. This was rounded up to 50% (a factor of 1.5) to be favorable to claimants, and this 

factor was applied to the organs in Table 6-16 if the organ was outside the area protected by 

the lead apron.

[56] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

If the cancer site was in an organ that was protected by the lead apron and the dosimeter was 

worn under the lead apron, the photon dose measured by the dosimeter was assumed to be 

an accurate measure of the dose received by the organ (i.e., the adjustment factor was 1).

[57] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

If the cancer site was in an organ that was not protected by a lead apron, the adjustment factor 

of 1.5 was applied regardless of whether the worker wore a lead apron and regardless of 

whether the dosimeter was worn under or outside of the lead apron. Applying the adjustment 

factor of 1.5 for any of these circumstances is favorable to claimants.

[58] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Although “average” or “routine” activities apply to most radiation exposure scenarios, many 

workers were involved in one or more radiation incidents during their radiation worker careers. 

Many of these incidents involved radioactive contamination that was readily cleaned up with 

little or no dose consequence. However, some incidents involved higher than normal radiation 

exposures or an uptake of radioactive material and an internal dose. The records for each 

worker must be carefully reviewed for any evidence of such radiation incidents, and the 

incidents must be evaluated to produce an accurate dose reconstruction.

[59] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The total person-years of employment at Pantex were divided by 316 claims to give the 

average of 20.2 years of employment per person.

[60] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The claims associated with 316 workers reported nearly 700 different job titles. Many workers 

had more than one job title, and many job titles have changed since Pantex began operations 

in 1952 to reflect changes in job duties and union negotiations.

[61] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

For each worker, the period of employment begins and ends in a given year. The data points 

for each year in Figure 6-13 represent the number of workers that were employed during that 

year. The plot indicates that few workers were employed in the early 1950s and few were still 

employed after 2000.
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[62] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Although there were nearly 700 different job titles, many were similar so they could reasonably 

be grouped into the 15 job categories in Table 6-17. The photon and neutron doses for each 

worker were summed within the job categories to give the collective photon and neutron doses 

in Table 6-17. The purpose of this tabulation was to facilitate an analysis of dose distribution 

in relation to job categories.

[63] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The near equality of collective photon and neutron doses for warehouse operators was 

unusual, and they were examined in detail to try to determine the cause. A large fraction of 

the neutron dose was received by a small group (fewer than 10) warehouse operators. One of 

the job duties of some warehouse operators involved handling pit containers in the pit storage 

vaults where neutron dose rates were relatively high. It is possible that some extensive 

operations occurred in pit storage vaults, but records of this were not found.

[64] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Although there were nearly 700 different job titles, many were similar so they could reasonably 

be grouped into the 15 job categories in Table 6-17. The photon and neutron doses for each 

worker were summed within the job categories to give the collective photon and neutron doses 

in Table 6-17. The purpose of this tabulation was to facilitate an analysis of dose distribution 

in relation to job categories. The near equality of collective photon and neutron doses for 

warehouse operators was unusual, and they were examined in detail to try to determine the 

cause. A large fraction of the neutron dose was received by a small group (fewer than 10) of 

warehouse operators. One of the job duties of some warehouse operators involved handling 

pit containers in the pit storage vaults where neutron dose rates were relatively high. It is 

possible that some extensive operations occurred in pit storage vaults, but records of this were 

not found.

[65] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The relatively high collective neutron dose in Figure 6-13 in 1960 was examined in detail to try 

to determine the cause. Most of the collective neutron dose was recorded for just a few 

workers. It is possible that these workers were involved in some extensive operations and that 

the recorded neutron doses were accurate. It is also possible that there was an effort to 

correct for the known underestimation of neutron doses as measured by NTA films, but no 

records of such an adjustment were found.

[66] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

There are four primary situations where the recorded dose for Pantex workers might be 

underestimated: 

1. There were a number of workers who were unmonitored before 1989 and who could have 

been incidentally exposed to radiation. The median photon dose for monitored workers 

before 1989 should be added to the dose of record.

2. If a cancer site is in an area not protected by a lead apron, an adjustment factor of 1.5 

should be applied regardless of whether the worker wore a lead apron and regardless of

whether the dosimeter was worn under or outside the lead apron.

3. When a dosimeter reading was less than the MDL, the dose was recorded as a zero when 

it could have actually been some nonzero value less than the MDL. All such zero results 

should be adjusted by adding a value of MDL/2.
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4. Before 1994, the neutron dosimeters at Pantex could have underestimated the neutron 

dose; therefore, all recorded neutron doses from before 1994 are considered unreliable. 

For this period, neutron doses should be calculated by multiplying the reliable photon dose 

of record by a neutron-to-photon dose ratio of 1.7.

[67] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Between 1952 and 1957, only a few radiographers were monitored (see Table 6-1). In 1958 

and 1959, after sealed pits were introduced, the number of monitored radiation workers 

increased to just 19 and 22, respectively. Therefore, the collective measured dose for this 

small group of workers was low in comparison with later periods.

[68] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The recommendation is based on the assumption that unmonitored workers (who were not 

expected to receive measurable radiation dose) would not likely receive incidental dose in 

excess of the median measured dose for monitored workers.

[69] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

To apply the same recommendation to unmonitored workers for years before 1960, when 

there was no measured gamma dose equal to or greater than 40 mrem, the median gamma 

dose for 1960 should be used.

[70] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Figure 6-11 illustrates the areas of the body that would be protected by a lead apron. If a 

cancer site is outside the areas protected by a lead apron, the adjustment factor for a lead 

apron should be used.

[71] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

On September 1, 1993, Pantex received its DOELAP certificate indicating successful 

completion of testing of the UD-802 TLD system in all beta and photon radiation testing 

categories and successful completion of testing of the UD-809/UD-812 TLD system in all beta, 

photon, and neutron radiation testing categories (personal knowledge). Only DOELAPaccredited dosimeters have been used at Pantex since January 1994.

[72] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The method for recording beta and skin doses changed in 1981. Before 1981, dosimetry 

records included beta, X-ray or gamma, and neutron doses, and the skin dose was taken to be 

the beta dose only. In 1981 and after, the skin dose has been calculated as the sum of the 

beta, gamma, and neutron doses, and the whole-body tritium dose.

[73] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Radiation that results in a whole-body penetrating dose must also pass through the skin. 

Although the skin dose would probably be less than the whole-body penetrating dose, the 

assumption that it is equal is favorable to claimants.

[74] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

A Panasonic UD-802 TLD with a wrist band has been used for extremity dosimetry since 1980 

(BWXT Pantex 2002; ORAUT 2003a).

[75] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

A wrist-type TLD dosimeter was used for extremity dosimetry between 1972 and 1980; a wristtype film badge was used before 1972. The earliest evidence of a nonzero extremity dose 

result was from 1964 (ORAUT 2003a). There was no evidence that confirmed the use of 

extremity dosimeters before 1964.
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[76] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

There are numerous examples in the dosimetry records where a worker received a nonzero 

whole-body dose, but the assigned extremity dosimeters were zero. This scenario suggests 

the worker wore the whole-body dosimeter but did not take the extremity dosimeter(s) into the 

workplace. In other examples, a worker received a nonzero whole-body dose and a nearly 

equal extremity dose. This scenario suggests the worker had both the whole-body and 

extremity dosimeters in the workplace, but did not wear the extremity dosimeter(s) on the 

wrists. 

[77] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

The extremity dose data for 316 Pantex claims were examined, and only 42 claims had 

extremity doses that were greater than 100 mrem in a given year. The ratios of wrist/extremity 

dose to whole-body photon dose were calculated, and a lognormal distribution analysis of the 

ratios showed that the 95th-percentile value of this distribution was approximately 6. This 

value is consistent with the rule-of-thumb used in operational health physics that if the 

measured contact dose rate is 6 times (or more) than the measured dose rate at the location 

of the whole-body dosimeter, extremity dosimeters should be assigned for the work.

[78] Martin, Jerome B. ORAU Team. Senior Health Physicist. August 2006.

Radiation doses that were measured by film badges were generally reported in units of 

exposure. Doses measured by TLDs were generally reported in units of deep dose 

equivalent. NIOSH (2007) recommends the use of the conversion factor from exposure to 

organ dose for data from film badges. NIOSH (2007) recommends the use of the conversion 

factor from deep dose equivalent to organ dose for data from TLDs. Film badges were used at 

Pantex until 1972; TLDs have been used since 1973.
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GLOSSARY

beta dose

Designation (i.e., beta) on some records for external dose from beta and less-energetic X-ray 

and gamma radiation, often for shallow dose or dose to the lens of the eye.

beta particle (β)

See beta radiation.

beta radiation

Charged particle emitted from some radioactive elements with a mass equal to 1/1,837 that of 

a proton. A negatively charged beta particle is identical to an electron. A positively charged 

beta particle is a positron.

bremsstrahlung

Electromagnetic radiation released as a result of inelastic scattering of a moving charged 

particle within the nucleus of an atom. X-rays produced in a typical medical X-ray tube 

frequently originate from inelastic scattering of accelerated electrons in the anode material.

curie (Ci)

Traditional unit of radioactivity equal to 37 billion (3.7 × 1010) becquerels, which is 

approximately equal to the activity of 1 gram of pure 226Ra.

depleted uranium (DU)

Uranium with a percentage of 235U lower than the 0.7% found in natural uranium. As 

examples, spent (used) fuel elements, byproduct tails, residues from uranium isotope 

separation, and some weapons materials contain DU. DU can be blended with highly 

enriched uranium to make reactor fuel or used as a raw material to produce plutonium. 

Pantex lists the isotope activity fractions for use in nuclear weapons components as: 

Isotope Activity fraction

234U 0.0840

235U 0.0145

238U 0.9015

dose equivalent (DE, H)

In units of rem or sievert, product of absorbed dose in tissue multiplied by a weighting factor 

and sometimes by other modifying factors to account for the potential for a biological effect 

from the absorbed dose.

dose of record

(1) Dose records that the U.S. Department of Energy provided to the National Institute for 

Occupational Safety and Health as part of each worker’s file. (2) Individual recorded dose 

such as that on a dosimetry card or in a dosimetry database.

dosimeter

Device that measures the quantity of received radiation, usually a holder with radiationabsorbing filters and radiation-sensitive inserts packaged to provide a record of absorbed dose 

received by an individual.

dosimetry

Measurement and calculation of internal and external radiation doses.
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dosimetry system

System for assessment of received radiation dose. This includes the fabrication, assignment, 

and processing of external dosimeters, and/or the collection and analysis of bioassay samples, 

and the interpretation and documentation of the results.

exchange period (frequency)

Period (weekly, biweekly, monthly, quarterly, etc.) for routine exchange of dosimeters.

exposure

(1) In general, the act of being exposed to ionizing radiation. (2) Measure of the ionization 

produced by X- and gamma-ray photons in air in units of roentgens.

extremities

Portion of the arm from and including the elbow through the fingertips and the portion of the 

leg from and including the knee and patella through the toes.

film

In the context of external dosimetry, radiation-sensitive photographic film in a light-tight 

wrapping. See film dosimeter.

film dosimeter

Package of film for measurement of ionizing radiation exposure for personnel monitoring 

purposes. A film dosimeter can contain two or three films of different sensitivities, and it can 

contain one or more filters that shield parts of the film from certain types of radiation. When 

developed, the film has an image caused by radiation measurable with an optical 

densitometer. Also called film badge.

gamma radiation

Electromagnetic radiation (photons) of short wavelength and high energy (10 kiloelectron-volts 

to 9 megaelectron-volts) that originates in atomic nuclei and accompanies many nuclear 

reactions (e.g., fission, radioactive decay, and neutron capture). Gamma photons are identical 

to X-ray photons of high energy; the difference is that X-rays do not originate in the nucleus.

gamma ray, particle, or photon (γ)

See gamma radiation.

gray (Gy)

International System unit of absorbed radiation dose, which is the amount of energy from any 

type of ionizing radiation deposited in any medium; 1 Gy equals 1 joule per kilogram or 

100 rads.

highly enriched uranium (HEU)

Uranium enriched to at least 20% 235U for use as fissile material in nuclear weapons 

components and some reactor fuels. Also called high-enriched uranium. Pantex lists the 

isotope activity fractions as:

Isotope Activity fraction

234U 0.9806

235U 0.0194

238U 0.0000
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ionizing radiation

Radiation of high enough energy to remove an electron from a struck atom and leave behind a 

positively charged ion. High enough doses of ionizing radiation can cause cellular damage. 

Ionizing particles include alpha particles, beta particles, gamma rays, X-rays, neutrons, highspeed electrons, high-speed protons, photoelectrons, Compton electrons, positron/negatron 

pairs from photon radiation, and scattered nuclei from fast neutrons. See beta radiation, 

gamma radiation, and X-ray radiation.

minimum detectable activity or amount (MDA)

Smallest amount (activity or mass) of an analyte in a sample that can be detected with a 

probability β of nondetection (Type II error) while accepting a probability α of erroneously 

deciding that a positive (nonzero) quantity of analyte is present in an appropriate blank sample 

(Type I error).

minimum detectable level (MDL)

See minimum detectable activity.

minimum recordable or recording dose (MRD)

See minimum reporting level.

minimum reporting level (MRL)

Level below which an analytical dose is not recorded in the worker’s dose record, usually 

based on a site-specific policy decision. The recording level is not necessarily the same as 

the minimum detectable amount or activity for that measurement. Also called less-than value, 

minimum reportable dose, minimum recordable or recording dose, recording level, and 

reporting level.

neutron (n)

Basic nucleic particle that is electrically neutral with mass slightly greater than that of a proton. 

There are neutrons in the nuclei of every atom heavier than normal hydrogen.

neutron, fast

Neutron with energy equal or greater than 10 keV.

neutron, thermal

Strictly, neutrons in thermal equilibrium with surroundings; in general, neutrons with energy 

less than about 0.5 eV.

neutron film dosimeter

Film dosimeter with a nuclear track emulsion, type A, film packet.

nuclear emulsion

Thick photographic coating in which the tracks of various fundamental particles show as black 

traces after development. The number of tracks in a given area is a measure of the dose from 

that radiation. See nuclear track emulsion, type A.

nuclear track emulsion, type A (NTA)

Film sensitive to fast neutrons made by the Eastman Kodak Company. The developed image 

has tracks caused by neutrons that become visible under oil immersion with about 

1,000-power magnification. The number of tracks in a given area is a measure of the dose 

from that radiation. Pantex apparently used NTA film at one time to measure alpha radiation

from radon progeny in air.
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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)]

Dose equivalent in units of rem or sievert in soft tissue below a specified point on the body at 

an appropriate depth d. The depths selected for personal dosimetry are 0.07 millimeters 

(7 milligrams per square centimeter) and 10 millimeters (1,000 milligrams per square 

centimeter), respectively, for the skin (shallow) and whole-body (deep) doses. These are 

noted as Hp(0.07) and Hp(10), respectively. The International Commission on Radiological 

Measurement and Units recommended Hp(d) in 1993 as dose quantity for radiological 

protection.

photon

Quantum of electromagnetic energy generally regarded as a discrete particle having zero rest 

mass, no electric charge, and an indefinitely long lifetime. The entire range of electromagnetic 

radiation that extends in frequency from 1023 cycles per second (hertz) to 0 hertz.

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, QF)

Principal modifying factor (which depends on the collision stopping power for charged 

particles) that is employed to derive dose equivalent from absorbed dose. The quality factor 

multiplied by the absorbed dose yields the dose equivalent.

radiation worker

Employee who works on, with, or in the proximity of radiation-producing machines or 

radioactive materials.

radioactivity

Property possessed by some elements (e.g., uranium) or isotopes (e.g., 14C) of spontaneously 

emitting energetic particles (electrons or alpha particles) by the disintegration of their atomic 

nuclei.

rem

Traditional unit of radiation dose equivalent that indicates the biological damage caused by 

radiation equivalent to that caused by 1 rad of high-penetration X-rays multiplied by a quality 

factor. The sievert is the International System unit; 1 rem equals 0.01 sievert. The word 

derives from roentgen equivalent in man; rem is also the plural.

roentgen (R, sometimes r)

Unit of photon (gamma or X-ray) exposure for which the resultant ionization liberates a positive 

or negative charge equal to 2.58 × 10-4 coulombs per kilogram (or 1 electrostatic unit of 

electricity per cubic centimeter) of dry air at 0 degrees Celsius and standard atmospheric 

pressure. An exposure of 1 R is approximately equivalent to an absorbed dose of 1 rad in soft 

tissue for higher energy photons (generally greater than 100 kiloelectron-volts).

shallow dose equivalent [SDE, Hs, Hp(0.07)]

Dose equivalent in units of rem or sievert at a depth of 0.07 millimeters (7 milligrams per 

square centimeter) in tissue equal to the sum of the penetrating and nonpenetrating doses.
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 64 of 69

shielding

Material or obstruction that absorbs ionizing radiation and tends to protect personnel or 

materials from its effects.

skin dose

See shallow dose equivalent.

thermoluminescence

Property that causes a material to emit light as a result of heat.

thermoluminescent dosimeter (TLD)

Device for measuring radiation dose that consists of 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.

U.S. Atomic Energy Commission (AEC)

Federal agency created in 1946 to assume the responsibilities of the Manhattan Engineer 

District (nuclear weapons) and to manage the development, use, and control of nuclear energy 

for military and civilian applications. The U.S. Energy Research and Development 

Administration and the U.S. Nuclear Regulatory Commission assumed separate duties from 

the AEC in 1974. The U.S. Department of Energy succeeded the U.S. Energy Research and 

Development Administration in 1979.

whole-body (WB) dose

Dose to the entire body excluding the contents of the gastrointestinal tract, urinary bladder, 

and gall bladder and commonly defined as the absorbed dose at a tissue depth of 

10 millimeters (1,000 milligrams per square centimeter). Also called penetrating dose.

X-ray radiation

Electromagnetic radiation (photons) produced by bombardment of atoms by accelerated 

particles. X-rays are produced by various mechanisms including bremsstrahlung and electron 

shell transitions within atoms (characteristic X-rays). Once formed, there is no difference 

between X-rays and gamma rays, but gamma photons originate inside the nucleus of an atom.
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 65 of 69

 

ATTACHMENT A 

UNMONITORED EXTERNAL DOSE TABLES

LIST OF TABLES

TABLE TITLE PAGE

A-1 Annual Pantex external photon doses.................................................................................... 67

A-2 Annual Pantex external neutron doses................................................................................... 68

A-3 Annual Pantex external skin doses ........................................................................................ 69
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 66 of 69

ATTACHMENT A

UNMONITORED EXTERNAL DOSE TABLES (continued)

The following tables were taken from ORAUT (2016) and modified for years for which no data was 

listed (i.e., years before 1960 and 1983).
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ATTACHMENT A

UNMONITORED EXTERNAL DOSE TABLES (continued)

Table A-1. Annual Pantex external photon doses (rem).

Year 50th percentile 95th percentile

1952–1963 0.010 0.302

1964 0.101 1.007

1965 0.029 0.440

1966 0.042 0.442

1967 0.045 0.505

1968 0.035 0.264

1969 0.032 0.293

1970 0.065 0.688

1971 0.057 0.778

1972 0.055 0.557

1973 0.124 0.539

1974 0.067 0.519

1975 0.037 0.255

1976 0.044 0.241

1977 0.080 0.281

1978 0.032 0.316

1979 0.086 0.481

1980 0.012 0.204

1981 0.066 0.889

1982 0.039 0.397

1983 0.042 0.419

1984 0.046 0.441

1985 0.039 0.395

1986 0.036 0.235

1987 0.023 0.123

1988 0.028 0.130

1989 0.020 0.127

1990 0.021 0.100

1991 0.023 0.095

1992 0.028 0.130

1993 0.009 0.064

1994 0.008 0.050

1995 0.008 0.048

1996 0.007 0.048

1997 0.006 0.037

1998 0.007 0.040

1999 0.007 0.041

2000 0.007 0.038

2001 0.007 0.037

2002 0.007 0.039

2003 0.007 0.035

2004 0.006 0.033

2005 0.003 0.018

2006 0.003 0.018

2007 0.003 0.019

2008 0.003 0.027

2009 0.003 0.029

2010 0.002 0.024
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 68 of 69

ATTACHMENT A

UNMONITORED EXTERNAL DOSE TABLES (continued)

Table A-2. Annual Pantex external neutron doses (rem).

Year 50th percentile 95th percentile

1960–1963 0.007 0.482

1964 0.043 0.645

1965 0.015 0.168

1966 0.022 0.147

1967 0.020 0.094

1968 0.021 0.080

1969 0.003 0.084

1970 0.017 0.075

1971 0.019 0.071

1972 0.021 0.072

1973 0.022 0.101

1974 0.019 0.164

1975 0.213 1.028

1976 0.001 0.042

1977 0.001 0.052

1978 0.001 0.052

1979 0.005 0.146

1980 0.003 0.058

1981 0.023 0.180

1982 0.024 0.180

1983 0.022 0.150

1984 0.020 0.150

1985 0.025 0.240

1986 0.027 0.213

1987 0.019 0.103

1988 0.019 0.101

1989 0.016 0.102

1990 0.017 0.089

1991 0.019 0.084

1992 0.007 0.100

1993 0.004 0.024

1994 0.004 0.026

1995 0.004 0.027

1996 0.004 0.026

1997 0.004 0.021

1998 0.004 0.020

1999 0.004 0.020

2000 0.004 0.020

2001 0.004 0.020

2002 0.004 0.020

2003 0.004 0.019

2004 0.004 0.018

2005 0.004 0.018

2006 0.004 0.018

2007 0.003 0.018

2008 0.004 0.021

2009 0.004 0.019

2010 0.003 0.018
Document No. ORAUT-TKBS-0013-6 Revision No. 03 Effective Date: 11/29/2016 Page 69 of 69

ATTACHMENT A

UNMONITORED EXTERNAL DOSE TABLES (continued)

Table A-3. Annual Pantex external skin doses (rem).

Year 50th percentile 95th percentile

1952–1963 0.012 0.112

1964 0.056 0.148

1965 0.036 0.180

1966 0.051 0.160

1967 0.053 0.165

1968 0.060 0.182

1969 0.057 0.154

1970 0.116 0.582

1971 0.139 0.944

1972 0.198 1.183

1973 0.021 0.284

1974 0.015 0.543

1975 0.008 0.093

1976 0.003 0.189

1977 0.006 0.217

1978 0.004 0.235

1979 0.015 0.254

1980 0.018 0.583

1981 0.097 2.017

1982 0.055 1.099

1983 0.068 1.124

1984 0.080 1.150

1985 0.061 1.429

1986 0.068 1.165

1987 0.035 0.502

1988 0.037 0.428

1989 0.022 0.258

1990 0.021 0.134

1991 0.020 0.088

1992 0.018 0.178

1993 0.008 0.086

1994 0.007 0.061

1995 0.007 0.058

1996 0.007 0.060

1997 0.006 0.048

1998 0.006 0.053

1999 0.007 0.053

2000 0.006 0.051

2001 0.006 0.049

2002 0.006 0.048

2003 0.006 0.044

2004 0.006 0.041

2005 0.006 0.038

2006 0.012 0.051

2007 0.011 0.052

2008 0.012 0.071

2009 0.013 0.065

2010 0.010 0.059