ORAU TEAM

Dose Reconstruction

Project for NIOSH

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

Page 1 of 10

Document Title:

Pantex Plant – Introduction

Document Number: ORAUT-TKBS-0013-1

Revision: 01

Effective Date: 07/27/2006

Type of Document: TBD

Supersedes: Revision 00

Subject Expert: Jerome B. Martin

Document Owner

Approval: Signature on File Approval Date: 06/01/2006

Jack J. Fix, TBD Team Leader

Approval: Signature on File Approval Date: 06/02/2006

John M. Byrne, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 06/01/2006

Edward F. Maher, Task 5 Manager

Concurrence: Signature on File Concurrence Date: 06/06/2006

Kate Kimpan, Project Director

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

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

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

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 2 of 10

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION

NUMBER DESCRIPTION

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

07/27/2006 01 Constitutes a total rewrite of document. Revised as a result of the 

biennial document review. Incorporates NIOSH formal review 

comments. Approved issue of Revision 01. 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 Jerome 

B. Martin.
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 3 of 10

TABLE OF CONTENTS

SECTION TITLE 

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

PAGE

4

1.1 Purpose ......................................................................................................................................5

1.2 Scope .........................................................................................................................................6

1.3 Discussion ..................................................................................................................................6

REFERENCES..................................................................................................................................10
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 4 of 10

ACRONYMS AND ABBREVIATIONS

AP anterior–posterior

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

DoD U.S. Department of Defense

DOE U.S. Department of Energy

DU depleted uranium

IFI in-flight insertable

L liter

MeV megaelectron-volt, 1 million electron-volts

NIOSH National Institute for Occupational Safety and Health

ORAU Oak Ridge Associated Universities

PA posterior–anterior

pCi picocurie

TBD technical basis document

U.S.C. United States Code

§ section
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 5 of 10

1.1 PURPOSE

Technical basis documents (TBDs) and site profile documents are general working documents that 

provide guidance concerning the preparation of dose reconstructions at particular sites or categories 

of sites. They will be revised in the event additional relevant information is obtained about the 

affected site(s). These documents may be used to assist the National Institute for Occupational 

Safety and Health (NIOSH) in the completion of the individual work required for each dose 

reconstruction.

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

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

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

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

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

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

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

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

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

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

facility encompassed by EEOICPA.

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

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

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

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

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

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

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

determined in accordance with the [probability of causation1

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

premises, grounds, or operations covered by Executive Order No. 12344, dated February 1, 1982 (42 

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

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

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

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

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

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

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

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

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

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

] guidelines established under subsection 

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

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

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

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

causation (POC).
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 6 of 10

• radiation from naturally occurring radon present in conventional structures;

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

1.2 SCOPE

This site profile is a specific support mechanism to the Oak Ridge Associated Universities (ORAU)

Team about the documentation of historical practices in relation to dose reconstruction at the Pantex 

Plant. This document provides supporting technical data, with assumptions that include a 

scientifically reasonable benefit of the doubt to claimants, to evaluate the total occupational radiation 

dose that can reasonably be associated with Pantex Plant 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. 

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. 

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 identified in this document. 

The doses are to be evaluated using the NIOSH Interactive RadioEpidemiological Program and the 

Integrated Modules for Bioassay Analysis 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 site profile consists of the latest revisions of six sections: This Introduction, Site Description, 

Occupational Medical Dose, Occupational Environmental Dose, Occupational Internal Dose, and 

Occupational External Dosimetry. Some sections are accompanied by attachments that provide the 

critical data for the dose reconstructors. 

1.3 DISCUSSION

Section 2.0, Site Description (ORAUT 2004a), briefly describes the facilities and processes that have 

been used in the assembly and disassembly of nuclear weapons since U.S. Atomic Energy 

Commission operations began at Pantex in December 1951. Between 1952 and 1954, the primary 

mission at Pantex was to machine precision high-explosive castings and send them to Sandia 

National Laboratory in Albuquerque, New Mexico, for assembly. Between 1954 and 1958 during the 

use of 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 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 by the nuclear weapons complex of government-owned sites or by 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 
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 7 of 10

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 to 1987, weapons were shipped between Pantex and the DoD sites primarily by 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 has occurred in bays only when insensitive high explosives were present.

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 facilities for special nuclear material components.

Section 3.0, Occupational Medical Dose (ORAUT 2005a), provides information about the dose that 

individual workers received from X-rays that were required as a condition of employment. These 

X-rays included preemployment chest and lumbar spine X-rays and annual chest X-rays during 

physical examinations. 

Pantex required preemployment and annual physical examinations as part of its occupational health 

and safety program. These medical examinations typically included annual diagnostic posterior–

anterior (PA) chest X-rays from the beginning of operations in 1952, with a change in frequency to 

every 5 years beginning in 1982. In addition, Pantex required a single set of preemployment lumbar 

spine radiographs, both anterior–posterior (AP) and lateral views, for men (but not for women) from 

1952 to 1982. Using documented Pantex X-ray techniques (machine settings), entrance skin 

exposures could have been as high as 14 R (about 14 rem) for the lumbar spine X-rays.

Both the X-ray equipment and the techniques used for taking X-rays covered by this TBD have 

changed over the years. 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, 

assumptions that contain a scientifically reasonable benefit of the doubt to claimants 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 (PA or lateral), and any other 

factor that could affect the dose received by the worker.
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 8 of 10

The organ doses from the X-rays have been calculated. The calculated dose takes into account the 

uncertainty associated with each of the parameters mentioned above. Tables list the doses received 

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

Section 4.0, Occupational Environmental Dose (ORAUT 2004b), applies to workers who were not 

routinely monitored for external or internal radiation exposure. The environmental dose is the dose 

unmonitored workers could have received when working on the site but outside the buildings 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 

inhalation of the radioactive materials as well as a whole- or partial-body external dose from deposited 

radionuclides or submersion in a cloud of radioactive material. 

Radionuclides present at the Pantex Plant have included tritium, uranium (primarily 238U), plutonium, 

and thorium. The primary radionuclides of concern are tritium and DU. There were no noble gas 

releases at the Pantex site, and 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 5.0, Occupational Internal Dose (ORAUT 2005b), describes the internal dosimetry program at 

Pantex Plant. Internal dose at Pantex has occurred primarily from intakes of radioactive material that 

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

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

been fairly successful. Between 1980 and 1990 there was a large disassembly effort, but controls to 

limit airborne contamination were not fully implemented. During this period there was a higher 

likelihood of radionuclide intakes. Before 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 can 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 before 1972; bioassay was performed only 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 before 

1972. Tritium dose records assign doses to only a few workers out of over 2000 monitored between 

1971 and 1980. Default doses were assigned to exposed workers for the 1956 to 1971 period based 

on the few non-zero doses in 1972. Around 1980, disassembly of nuclear weapons was performed 

more often than assembly, and releases of tritium were more likely to occur. The TBD describes a 

method for assigning chronic intake of tritium to workers who have handled tritium reservoirs from 

1972 to the present based on the dose records. In addition the large accidental release of tritium in 

1989 is discussed. Four workers received intakes; one significantly, requiring medical treatment.

Uranium contamination at Pantex is either uranium metal or air-oxidized uranium. During 

disassembly, aged components can have uranium oxide and uranium metal in the form of black dust,

which is potentially present as airborne contamination that exhibits type S aerosol behavior. Bioassay 

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

of doses from occupational intakes of uranium, the probabilistic corrections for nonoccupational 

intakes of uranium, and the use of isotope ratios to distinguish occupational intakes from 
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 9 of 10

environmental intakes. The TBD describes a method to determine default intake values for workers 

exposed to uranium contamination during disassembly of nuclear weapons.

Thorium and plutonium have been handled at Pantex, but no machining or other processing has been 

conducted. The potential for removable contamination and uptakes by workers has been very low. A 

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

except for workers who could have been involved in a 1961 incident and its subsequent cleanup.

Occupational internal dose from elevated radon in the Pantex workplace was 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, which is the U.S. Environmental Protection Agency’s reference 

point for considering remedial action for indoor radon activity. The TBD provides recommendations 

for assessment of potential radon exposures and effective dose to workers.

Section 6.0, Occupational External Dosimetry (ORAUT 2006), discusses the Pantex program for 

measuring whole-body, skin, and extremity 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 TBD discusses the 

dose reconstruction parameters, Pantex practices and policies, and dosimeter types and technologies 

for measuring the dose from the different types of radiation. The evaluation of doses measured from 

exposure to beta, gamma, and neutron sources are addressed. Tables list results for various 

dosimeters exposed to different exposure geometries and radiation energies.

The primary sources of external radiation exposure at Pantex have been plutonium pits, DU, and

thorium components. Plutonium pits, which emit X-rays, gamma rays, and neutrons, have been 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 can also be underestimated. Beta and 

photon exposures have occurred during handling of DU or thorium components. Exposures to 

thorium have included 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.
Document No. ORAUT-TKBS-0013-1 Revision No. 01 Effective Date: 07/27/2006 Page 10 of 10

REFERENCES

ORAUT (Oak Ridge Associated Universities Team), 2004a, Technical Basis Document for the Pantex 

Plant – Site Description, Rev. 00, Oak Ridge, Tennessee, March 30.

ORAUT (Oak Ridge Associated Universities Team), 2005a, Technical Basis Document for the Pantex 

Plant – Occupational Medical Dose, Rev. 01, Oak Ridge, Tennessee, December 23.

ORAUT (Oak Ridge Associated Universities Team), 2004b, Technical Basis Document for the Pantex 

Plant – Occupational Environmental Dose, Rev. 01, Oak Ridge, Tennessee, August 24.

ORAUT (Oak Ridge Associated Universities Team), 2005b, Technical Basis Document for the Pantex 

Plant – Occupational Internal Dose, Rev. 00-F, Oak Ridge, Tennessee, September 20.

ORAUT (Oak Ridge Associated Universities Team), 2006, Technical Basis Document for the Pantex 

Plant – Occupational Environmental Dose, Rev. 00-G, Oak Ridge, Tennessee, March 24.