ORAU Team

NIOSH Dose Reconstruction Project

Technical Basis Document for the Pantex Plant – Introduction

Document Number:

ORAUT-TKBS-0013-1

Effective Date: 02/18/2004

Revision No.: 00

Controlled Copy No.: ______

Page 1 of 7

Subject Expert: Jerome B. Martin

Document Owner

Approval: _Signature on File________ Date: 02/23/2004

Jerome B. Martin TBD Team Leader

Approval: _Signature on File____________ Date: 02/25/2004

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File________ Date: 02/25/2004

Richard E. Toohey, Project Director

Approval: _Signature on File____________ Date: 02/25/2004

James W. Neton, OCAS Health Science Administrator

Supersedes:

None

TABLE OF CONTENTS

Section

Record of Issue/Revisions ...................................................................................................................

Page

2

Acronyms and Abbreviations ...............................................................................................................3

1.0 Executive Summary ....................................................................................................................4

Attachment D Radionuclide Intake and Occupational Exposure

Attachment F Occupational External Dose for Monitored Workers
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RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 11/26/2003 00-A New technical basis document for the Pantex 

Plant – Site Profile. Initiated by Jerome B. Martin

Draft 01/12/2004 00-B Incorporates NIOSH comments. Initiated by 

Jerome B. Martin.

02/18/2004 02/18/2004 00 First approved issue. Initiated by Jerome B. 

Martin.
Effective Date: 02/18/2004 Revision No. 00 Document No. ORAUT-TKBS-0013-1 Page 3 of 7

ACRONYMS AND ABBREVIATIONS

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

DoD Department of Defense

DOE Department of Energy

DU depleted uranium

IFI in-flight insertable

IMBA Integrated Modules for Bioassay Analysis

IREP Interactive RadioEpidemiological Program

NIOSH National Institute for Occupational Safety and Health

ORAU Oak Ridge Associated Universities

TBD technical basis document
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1.0

In enacting the Energy Employees Occupational Illness Compensation Program Act of 2000 

(EEOICPA), the U.S. Congress officially recognized the hazardous nature of producing and testing 

nuclear weapons. Under the Act, workers who have developed selected types of cancer (or their 

survivors) may be entitled to compensation and medical benefits. This program is administered by 

the U.S. Department of Labor, Office of Worker Compensation. The National Institute for 

Occupational Safety and Health (NIOSH), a part of the U.S. Department of Health and Human 

Services, is responsible for determining the individual worker’s dose. Oak Ridge Associated 

Universities (ORAU) leads a team to support NIOSH in conducting this major program. 

EXECUTIVE SUMMARY

The Act requires the estimation of radiological doses from ionizing radiation received by workers in 

the nuclear weapons production programs of the U.S. Department of Energy (DOE) and its 

predecessor agencies. Methods for implementing provisions of the Act have been promulgated in

Title 42 of the Code of Federal Regulations, Part 82, “Methods for Radiation Dose Reconstruction 

Under the Energy Employees Occupational Illness Compensation Program Act of 2000.”

This technical basis document (TBD) is a specific support mechanism to the ORAU Team concerning 

documentation of historical practices at the Pantex Plant. Dose reconstructors should use the 

information in this TBD to evaluate both internal and external dosimetry data for unmonitored and 

monitored workers. In addition, the document serves as a supplement to, or a substitute for, 

individual monitoring data. This document provides a site profile of the Pantex Plant that contains 

technical basis information for the ORAU Team to use to evaluate the total occupational radiation 

dose for EEOICPA claimants. 

In addition, this document provides supporting technical data to evaluate, with claimant-favorable 

assumptions, the total Pantex Plant occupational radiation dose that can reasonably be associated 

with worker exposures. This dose results from exposure to external and internal radiation sources in 

Pantex facilities; to Pantex occupationally-required diagnostic x-ray examinations, and to on-site 

environmental releases. The discussion includes the doses that workers could have incurred while 

not monitored or that could have been missed. 

Over the years new and more reliable radiation protection measures, as well as improved techniques 

and equipment for radiation detection and measurement, have been developed. The methods 

needed to account for these changes are also identified in this document. 

The doses are to be evaluated using the NIOSH Interactive RadioEpidemiological Program (IREP)

and the Integrated Modules for Bioassay Analysis (IMBA) computer programs. Information on 

measurement uncertainties is an integral component of the NIOSH approach. This document 

describes how the uncertainty for Pantex exposures and dose records is to be evaluated.

The document comprises six sections: this introduction, Site Description, Occupational Medical Dose, 

Occupational Environmental Dose, Occupational Internal Dose, and Occupational External Dosimetry. 

Some sections are accompanied by an attachment that provides the critical data for the specialists 

reconstructing the doses. 

Section 2, Site Description, briefly describes the facilities and processes that have been used in the 

assembly and disassembly of nuclear weapons since operations began at Pantex in December 1951. 

Between 1952 and 1954, the primary mission at Pantex was to precision-machine high explosive 

castings and send them to Sandia National Laboratory in Albuquerque, New Mexico for assembly. 

Between 1954 and 1958 with the in-flight insertable (IFI) design, the only nuclear components 

handled at Pantex were depleted uranium (DU) cases and tritium reservoirs; during this time there 
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was no processing of nuclear material. In 1958, the sealed-pit design replaced the IFI design and 

sealed plutonium pits were delivered to Pantex for assembly. 

The nuclear weapon assembly process was highly standardized and consistent. Rigorous procedures 

were followed to ensure product quality and uniformity. Most of the parts for nuclear weapons were 

manufactured with the nuclear weapons complex of government-owned or contracted vendors. 

Pantex received those parts as completed major components. These components supported one of 

three major processes: high explosives assembly, physics package assembly, or mechanical 

assembly. The physics package operation involved the mating of the high explosives with the nuclear 

components. Completed and packaged weapons were staged for shipment to the U.S. Department of 

Defense (DoD).

From 1951 through 1987, weapons were shipped between Pantex and the DoD sites primarily by rail 

in specially designed and built railcars, escorted by DOE couriers. From 1977 to the present, 

weapons have moved between Pantex and DoD sites in specially designed and built tractor trailers, 

also escorted by DOE couriers.

The facilities at Pantex are primarily those for assembly and disassembly of weapons and the special 

purpose and nuclear staging facilities that have handled complete nuclear weapons and components. 

Bays and “Gravel Gertie” cells are the facilities used for assembly and disassembly. The principal 

function of the bays is the assembly and disassembly of nuclear explosives, particularly the 

mechanical portion, which includes the electrical components and tritium reservoirs.

Physics package assembly and disassembly, where bare pit and high explosive operations occur, 

take place in the cells. During the process of assembly of a nuclear explosive, operations begin in an 

assembly cell then move to an assembly bay for completion. The reverse is true for disassembly. 

Disassembly of weapons with insensitive high explosives occurs only in bays.

“Gravel Gertie” cells are round structures with a gravel and earth cover supported by a cable system. 

The design is based on experiments that showed that the mounded gravel roof over the round room 

would lift and vent the gas pressures produced in an accidental explosion. Plutonium would be 

filtered from the vented gases by the gravel and releases to the environment would be minimized. 

Special purpose facilities at Pantex include the Paint Facility, the Separation Testing Facility, the 

Mass Properties Facility, the Weapons Aging Facility, and the Weapons Transfer Station. Nuclear 

staging facilities include the Zone 4 igloos for staging or interim storage of weapons, weapon 

components, and other process-related materials. Zone 12 staging facilities include pit vaults, 

warehouses, and staging facilities for special nuclear material components.

Section 3, Occupational Medical Dose, provides information about the dose that individual workers 

received from x-rays that were required as a condition of employment. These x-rays included 

pre-employment chest and lumbar spine x-rays and annual chest x-rays during physical exams. 

Pantex required pre-employment and annual physical examinations as part of its occupational health 

and safety program. These medical examinations typically included annual diagnostic PA (posterioranterior) chest x-rays from the beginning of Atomic Energy Commission operations in 1952, with a 

change in frequency to every 5 years beginning in 1982. Additionally, Pantex required a single set of 

pre-employment lumbar spine radiographs, both AP (anterior-posterior) and lateral views, for men (but 

not for women) from 1952 through 1982. Using documented Pantex x-ray techniques (machine 

settings), entrance skin exposures could have been as high as 14 R (about 14 rems) for the lumbar 

spine x-rays.
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Both the x-ray equipment and the techniques used for taking x-rays have changed over the years 

covered by this TBD. These factors have been taken into account in determining the dose that a 

worker would have received from an x-ray. When there was a doubt about the technique used, the 

most claimant-favorable assumptions have been made to ensure that the dose is not underestimated. 

The investigated parameters include the tube current and voltage, exposure time, filtration, source to 

skin distance, the view (posterior-anterior or lateral), and any other factor that could affect the dose 

received by the worker.

The organ doses resulting from the x-rays have been calculated. The calculated dose takes into 

account the uncertainty associated with each of the parameters mentioned above. Tables present the 

doses received by the various organs for convenient reference by the dose reconstructors. 

Section 4, Occupational Environmental Dose, applies to workers who were not routinely monitored for 

external or internal radiation exposure. The environmental dose is the dose unmonitored workers 

could receive when working outside the buildings on the site from inhalation of radioactive materials in 

the air, direct radiation from plumes, contact with particles on the skin, and from direct exposure to 

radionuclides in the soil.

Exposure to these sources can result in an internal dose to the whole body or body organs from 

inhaling the radioactive materials and in a whole- or partial-body external dose from deposited 

radionuclides or submersion in a cloud of radioactive material. 

Radionuclides present at the Pantex Plant include tritium, uranium (primarily 238U), plutonium, and 

thorium. There were no noble gases released at the Pantex site. The primary radionuclides of 

concern are tritium and DU. There have been no environmental releases of plutonium or thorium. A 

significant release of tritium occurred in May 1989, but environmental doses were minimal. Chronic 

low-level releases of DU have been monitored and are characterized in this section.

Section 5, Occupational Internal Dose, describes the internal dosimetry program at Pantex Plant. 

Internal dose at Pantex occurs primarily from intakes of radioactive material that may have occurred 

during assembly and disassembly of nuclear weapons and potentially during radioactive waste 

management activities. Since 1990, measures to contain materials that may become airborne have 

been fairly successful. Between 1980 and 1990 when there was a large, ongoing disassembly effort, 

but controls to limit airborne contamination were not fully implemented, there was a higher likelihood 

of radionuclide intakes. Prior to 1980, most work was assembly of new, clean components so the 

potential for intakes was lower. In addition to the radionuclides used at Pantex that may result in 

worker intakes, this section addresses occupational internal dose from radon in the workplace. This 

section also addresses potential missed internal dose.

There was no routine bioassay program at Pantex prior to 1972; bioassay was performed for specific 

events. There are only four radionuclides handled at Pantex that are of concern for occupational 

intakes – tritium, uranium, thorium, and plutonium.

There is no specific data to substantiate any specific releases of tritium or uptakes of tritium prior to 

1972. It is reasonable to assume that there were no significant intakes of tritium before 1980. Around 

1980, disassembly of nuclear weapons was performed more often than assembly and releases of 

tritium were more likely to occur. A method is described for assigning a small chronic intake of tritium 

to workers who handled tritium reservoirs from 1980 on. The only exception is for 1989, when a 

significant release of tritium occurred in one event. Only one individual received a significant dose 

during that event.
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Uranium contamination at Pantex is either uranium metal or air oxidized uranium. During 

disassembly, aged components may have uranium oxide and uranium metal in the form of “black 

dust” that is potentially present as airborne contamination that exhibits class S aerosol behavior. 

Bioassay data for a group of 305 workers collected in 1990 were analyzed to determine the potential 

magnitude of doses from occupational intakes of uranium, the probabilistic corrections for nonoccupational intakes of uranium, and use of isotope ratios to distinguish occupational intakes from 

environmental intakes. A method is presented to determine default intake values for workers who 

were exposed to uranium contamination during disassembly of nuclear weapons.

Thorium and plutonium are also handled at Pantex, but no machining or other processing is 

conducted. The potential for removable contamination and uptakes by workers is very low. A few 

small uptakes of thorium have been recorded since 1999. No intakes of plutonium have occurred 

except for claimants that may have been involved in the 1961 incident and its subsequent cleanup.

Occupational internal dose from elevated radon in the Pantex workplace was also assessed. A DOE 

complex-wide survey of radon levels was performed in 1990. There were 137 locations sampled at 

Pantex, with duplicate measurements made at 13 locations. There were eight buildings at Pantex 

with radon concentrations above 4 pCi/L (the Environmental Protection Agency’s reference point for 

considering remedial action for indoor radon). Recommendations are provided for potential radon 

exposures and assessment of effective dose to the lungs of claimants.

Section 6, Occupational External Dosimetry, discusses the Pantex program for measuring skin and 

whole-body doses to the workers. The methods for evaluating external doses to workers have also 

evolved over the years as new techniques and equipment have been developed. In addition, 

concepts in radiation protection have changed. The dose reconstruction parameters, Pantex 

practices and policies, and dosimeter types and technologies for measuring the dose from the 

different types of radiation are described. The evaluation of doses measured from exposure to beta, 

gamma, and neutron sources are addressed. Tables present results for various dosimeters exposed 

to different exposure geometries and radiation energies.

The primary sources of external radiation exposure at Pantex are plutonium pits and DU or thorium 

components. Plutonium pits emit x-rays, gamma rays, and neutrons that are the major source of 

exposure to Pantex radiation workers. Direct handling of pits can result in relatively high extremity 

dose rates. Workers wear lead aprons during pit-handling work, which substantially reduces the low 

energy photon doses to the torso. Dosimeters are usually worn under the lead apron, which captures 

the reduced torso dose but underestimates the dose to the head (thyroid, lens of eye). Neutron doses 

measured under the lead apron may also be underestimated. Beta and photon exposures occur 

during handling of DU or thorium components. Exposures to thorium include the penetrating 2.6-MeV 

photons from 208Tl.

Sources of bias, workplace radiation field characteristics, responses of the different beta/gamma and 

neutron dosimeters in the workplace fields, and the adjustments to the recorded dose measured by 

these dosimeters during specific years are discussed in detail.

There are sources of potential dose that could have been missed because of the limitations of 

dosimetry systems and the methods of reporting low doses. This missed dose is discussed as a 

function of facility location, dosimeter type, year, and energy range. Attachment F describes the use 

of the external dosimetry technical basis parameters to facilitate the efforts of the dose reconstructors.