ORAU Team

NIOSH Dose Reconstruction Project

Technical Basis Document for the Pantex Plant – Site Description

Document Number:

ORAUT-TKBS-0013-2 

Effective Date: 03/30/2004

Revision No.: 00

Controlled Copy No.: ______

Page 1 of 17

Subject Expert: Jerome B. Martin 

Document Owner

Approval: Signature on File Date:03/29/2004

Jerome B. Martin, TBD Team Leader

Approval: Signature on File Date:03/30/2004 Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File Date: 03/29/2004 Richard E. Toohey, Project Director

Approval: Signature on File Date: 03/30/2004 James W. Neton, OCAS Health Science Administrator

Supersedes:

None

TABLE OF CONTENTS

Record of Issue/Revisions ...................................................................................................................3

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

2.0 Site Description...........................................................................................................................5

2.1 Site Activities ..............................................................................................................................6

2.1.1 Early Pantex Plant Operations............................................................................................6

2.1.2 Weapon Assembly and Disassembly Processes ................................................................ 7

2.2 Site Facilities...............................................................................................................................7

2.2.1 Bays...................................................................................................................................9

2.2.2 Cells................................................................................................................................. 11

2.2.3 Special-Purpose Facilities ................................................................................................ 12

2.2.4 Nuclear Staging Facilities ................................................................................................. 13

2.3 Pantex radiation protection program ......................................................................................... 13

2.4 General Radiation Exposure Characteristics............................................................................. 15

References ........................................................................................................................................16

Glossary ............................................................................................................................................17
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LIST OF FIGURES

2-1 Map of Pantex Plant....................................................................................................................5

2-2 Pantex nuclear weapon assembly process .................................................................................8

2-3 Weapons dismantlement and pit storage at Pantex Plant ........................................................... 8

2-4 Generic representation of a nuclear explosive bay...................................................................... 9

2-5 Generic representation of a nuclear explosive cell .................................................................... 11

2-6 Evolution of external dosimetry at Pantex ................................................................................. 14
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RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 11/26/03 00-A New Technical Basis Document for the Pantex 

Plant – Site Description. Initiated by Jerome B. 

Martin.

Draft 12/29/2003 00-B Incorporates internal review comments. Initiated 

by Jerome B. Martin.

Draft 03/24/3004 00-C Incorporates additional NIOSH and internal review 

comments. Initiated by Jerome B. Martin.

03/30/2004 03/30/2004 00 First approved issue. Initiated by Jerome B. 

Martin.
Effective Date: 03/30/2004 Revision No. 00 Document No. ORAUT-TKBS-0013-2 Page 4 of 17

ACRONYMS AND ABBREVIATIONS

AEC U.S. Atomic Energy Commission

ALARA as low as reasonably achievable

BXWT Babcock & Wilcox Technologies, Inc.

CAM continuous air monitor

DOD U.S. Department of Defense

DOE U.S. Department of Energy

DU depleted uranium

FM farm-to-market

HE high explosives

hr hour

IFI in-flight insertable

IHE insensitive high explosives

lb pound 

Linac linear accelerator

MeV megavolt-electron, 1 million electron volts

NEOP nuclear explosive operating procedures

NDE Non-Destructive Examination

NIOSH National Institute for Occupational Safety and Health

ORAU Oak Ridge Associated Universities

RAMS Radiation Alarm Monitoring System

SNM special nuclear material

TBD technical basis document

TLD thermoluminescent dosimeter

U.S.C. United States Code
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2.0

The Pantex Plant is approximately 17 miles northeast of Amarillo in Carson County (in the Texas 

panhandle; see Figure 2-1). The Plant site is bounded on the north by Texas Farm-to-Market (FM) 

Road 293, on the east by FM 2373, and on the west by FM 683. To the south, U.S. Department of 

Energy (DOE)-owned property extends to within 1 mile of U.S. Highway 60. 

SITE DESCRIPTION

Figure 2-1. Map of Pantex Plant. 

The following discussions briefly describe Pantex Plant processes (Section 2.1) and facilities (Section 

2.2) and illustrate the origins of the associated source terms. Section 2.3 summarizes the general 

characteristics of radiation exposure at Pantex. Dose reconstructors would use these data only if 

monitoring data were unavailable and other methods were not appropriate for dose reconstruction.

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.
Effective Date: 03/30/2004 Revision No. 00 Document No. ORAUT-TKBS-0013-2 Page 6 of 17

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 facility” as defined in the Energy Employee 

Occupational Illness Compensation Program Act of 2000 (42 U.S.C. § 7384l (5) and (12)).” 

2.1 SITE ACTIVITIES

2.1.1

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

ordnance. The plant began operations in September 1942, only 9 months after groundbreaking. By 

the end of the War, Pantex had three loading lines running full time, which produced 500-lb bombs, 

105-mm howitzer shells, and 23-lb fragmentation bombs. Operations at Pantex stopped the week 

after the War ended on August 14, 1945 (Gaither 1995). In 1951, when the U.S. Atomic Energy 

Commission (AEC) was looking for a new high explosives (HE) fabrication plant, the unused 6-yr-old 

HE loading line at Pantex was attractive. AEC contracted Silas Mason Company for the construction 

of 10 new buildings and modification of 3 others, and construction began on April 13, 1951 (Mitchell 

2001). Pantex completed its first HE operations in December 1951 (AEC 1952). By mid-1952, 

Pantex was at full production, responsible for HE fabrication, assembly of non-nuclear components, 

retrofits, modifications, and disassembly for retirements. The 10 facilities included six Gravel Gertie

cells and related explosives-manufacturing facilities that did not process special nuclear material 

(SNM).

Early Pantex Plant Operations

Beginning in 1948, the in-flight insertable (IFI) design was used. In this design, nuclear and nonnuclear components were kept separate until the time of use. The nuclear capsule did not require 

additional assembly, so military technicians could complete the final weapon assembly en route to the 

target by inserting the nuclear capsule into the mechanical assembly (Mitchell 2001). 

Between 1952 and 1954, the primary mission at Pantex was to precision-machine HE castings and 

send them to Sandia National Laboratory in Albuquerque, New Mexico, for assembly. From 1956 to 

1958, with the 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 (Martin 

2003a). Because these DU components were new at the time of assembly, this analysis assumed 

that removable depleted uranium oxide contamination on the components was minimal. In similar 

fashion, the potential for significant removable tritium contamination was minimal because the tritium 

reservoirs had to meet rigorous shipping requirements. The only other sources of radiation exposure 

at Pantex during this period were industrial radiography and medical X-rays.

In the late 1950s the sealed-pit design replaced the IFI design and delivery of sealed plutonium pits to 

Pantex became routine in1958 (Mitchell 2001). New facilities were required for the sealed-pit design, 

which involved encapsulated SNM; six Gravel Gertie cells were completed in 1958. 

By 1966, all the older IFI weapons were dismantled, with most of the SNM recycled into the new 

sealed-pit weapons. In 1964, the weapon surveillance and repair mission was assigned to Pantex, 

while both Pantex and Burlington shared the retrofits and modifications mission. Pantex renovated 

facilities for HE development in the early 1960s, and completed the new separated-bay designed 

weapon assembly facility in 1970. Since 1975, Pantex has been the only DOE weapon assembly, 

disassembly, retrofit, and modification center (Mitchell 2001). 
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2.1.2

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

were followed to ensure product quality and uniformity. Classified records documented every step of 

assembly and disassembly of every weapon, including the badge number or inspection stamp of the 

person completing the step (Martin 2003b). With the advent of the sealed-pit design in 1958, all 

assembly and disassembly work was on complete, sealed-pit weapons (Mitchell 2001).

Weapon Assembly and Disassembly Processes

Most parts for nuclear weapons assembly were manufactured within the nuclear weapons complex of 

government-owned/contractor-operated facilities. Pantex received those parts as completed major 

components (DOE 1997). These components supported one of three major processes: 

HE subassembly, physics package assembly, or mechanical assembly. A process called palletizing

involved pulling the required parts for one weapon from warehouse stock into one or two large 

baskets or pallets, which were delivered at the appropriate time to the bay or cell where assembly 

would take place (BWXT 2001).

The physics package operation involved the mating of the HE subassembly with the nuclear 

components. Once assembled into a single unit, the physics package was sent to the 

Non-Destructive Examination (NDE) section for radiography, then to Mechanical Assembly, where the 

weapon was built around the physics package. The completed weapon was checked for leaks, which 

involved filling the weapon with a tracer gas such as helium or argon, placing the weapon in a vacuum 

chamber, and applying a vacuum in the chamber to detect any tracer gas leaking from the weapon. 

Once the vacuum leak check was successfully completed, the interior of the weapon was purged and 

backfilled with an inert gas, usually nitrogen. 

The completed nuclear weapons, or warheads, were sent to the paint bay for touch-up painting. 

Warheads were sent to Mass Properties for spin balancing and to test moments, products of inertia, 

and center of gravity. Once the mass properties procedures were complete, warheads were sent 

back to NDE for radiography. Bombs from the paint bay and warheads from radiography were both 

processed for ultimate user packaging, which included final checks on stenciling, serial numbers, and 

other program-specific documentation. Completed and packaged weapons were staged for shipment 

to the U.S. Department of Defense (DOD). 

Figure 2-2 is a schematic illustration of the weapon assembly process at Pantex. The shaded steps 

are those with the highest potential for radiation exposure. The following sections characterize the 

radiation source(s), the geometry of exposure situations, and the typical duration of exposures 

associated with these steps.

Figure 2-3 shows how the dismantlement of nuclear weapons at Pantex is basically the reverse of the 

assembly process. 

From 1951 through 1987, weapons were shipped between Pantex and 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 (Mitchell 2001).

2.2 SITE FACILITIES

Figure 2-1 shows the location of the major Pantex Plant activities in Zone 4 and Zone 12. Major 

operations with radioactive materials included staging of SNM in Zone 4 and assembly and 

disassembly of nuclear weapons in Zone 12 South [Babcock & Wilcox Technologies (BWXT) 2001]. 
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Figure 2-2. Pantex nuclear weapon assembly process. 

Figure 2-3. Weapons dismantlement and pit storage at Pantex Plant. 

Source:

Mitchell (2001).

Weapon Assembly Process

Completed HE 

Subassembly from 

Machining Process

Warehouse Received 

Parts & Components 

from Vendors

Palletized for:

• HE Subassembly

• Physics Package 

Assembly, or

• Mechanical 

Assembly

HE Subassembly, Pit, 

Secondary, & Palletized 

Parts Mated to Form 

Physics Package

Radiography

Physics Package 

to Mechanical 

Assembly Bay

Completed Weapon to 

Vacuum Leak Check

• Weapon Filled with 

Tracer Gas

• Weapon Placed in 

Vacuum Chamber

• Vacuum Pulled in 

Chamber

Weapon to Purge 

& Backfill

Warheads go to Mass 

Properties

• Spin Balance

• Moments & Products 

of Inertia

• Center of Gravity

Staging in

Zone 4

Back for New 

Material or 

Disassembly 

& Inspection

Shipped to DOD by Transportation 

Safeguards Division

Vacuum Leak 

Check or 

Weight Check

Pits & Components

Received from 

Nuclear Weapons 

Complex

Bombs go To 

Paint Bay

Ultimate User 

Packaging

Warheads to 

Radiography
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The moderate-hazard facilities at Pantex are primarily those for assembly and disassembly and the 

special-purpose and nuclear staging facilities that have handled complete nuclear weapons (nuclear 

explosives) and components. The following sections describe the bays, cells, special-purpose 

facilities, and nuclear staging facilities at Pantex.

2.2.1

Figure 2-4 shows a generic bay situated off a ramp or hall for transport of a weapon or weapon 

component into the bay. The bay is accessed through a pair of interlocked blast-proof doors, which 

prevent the outer door from opening unless the inner door is closed (and vice-versa). A pair of double 

doors (also with an interlocking system) is used to bring equipment into the bay. A special work stand 

occupies the middle of the floor space for weapons work. Appropriate electrical, pneumatic, and 

safety alarm systems are permanently installed in the bay. In addition, an elaborate communication 

system is in place for monitoring the Nuclear Explosive Operating Procedures (NEOPs) and tracking 

the SNM. Redundant and diverse fire protection systems are in place, and strict control of 

combustible material is enforced. Certain operations require that the process technicians are 

electrically grounded to the weapon to avoid static discharge. In addition, operations are discontinued 

during lightning warnings (BWXT 2001).

Bays

Figure 2-4. Generic representation of a nuclear explosive bay. 

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 (BWXT 2001). 

The major operations in these bays are the partial assembly or disassembly of nuclear weapons 

containing HE and the complete assembly and disassembly of nuclear weapons containing insensitive 

high explosives (IHE). 
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Physics package assembly and disassembly, where bare pit and HE operations occur, take place in 

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

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

for HE weapons begins in a bay and concludes in a cell. Disassembly of weapons with IHE occurs 

only in a bay.

Alpha and beta continuous air monitors connected to the Pantex Radiation Alarm Monitoring System 

(RAMS) are used to detect airborne radiological contamination in the bays and cells (BWXT 2001). 

The radiation safety system in the radiography bays provides interlocking safety devices to protect 

workers from accidental exposures. Additional safety measures include interlocks between the 

operating controls; gamma radiation detectors; panic switches; warning lights, chimes, and horns; 

passageway door switches; RAMS alarms; and fire alarms.

Nuclear explosives, nuclear components, radioisotopic thermoelectric generators, HE, and IHE are 

transferred to and from the bays using electric forklifts or manually operated transfer carts (BWXT 

2001). Only weapons containing IHE main charges can be completely assembled or disassembled in 

the bays. For pit-HE-IHE disassembly, employees wear lead-lined aprons, safety glasses, and vinyl

gloves to handle bare pits. In addition, a safety net is used during pit-HE-IHE disassembly for some 

operations. All assembly and disassembly operations are performed in the designated bay according 

to the written NEOPs and the Operations and Instructions Standards specific to a weapons program.

Radiographic inspection and certification of nuclear explosive assemblies and subassemblies are 

performed in the radiography bays, which currently house an 8-million-electron-volt (MeV) linear 

accelerator (Linac) and a 9-MeV Linac (BWXT 2001). Each Linac has the capability to examine 

completed nuclear explosives in addition to nuclear explosive components and subassemblies. The 

radiography bays contain manipulator systems, turntables, alignment lasers, and closed-circuit 

television systems. The control room areas for the two radiography bays include a process/service 

room that provides development and processing of film from Linac operations, film storage, and film 

viewing and interpretation. In addition to the large fixed Linac units, a portable X-ray machine can be 

used in the bays to radiograph pits. 

Process flow is similar in the two radiography bays (BWXT 2001). Assemblies are brought to the 

radiography bay in fixtures that allow radiography, or they are removed and placed in suitable fixtures. 

The operator positions the film behind the unit, perpendicular to the beam with respect to the Linac 

and the unit. During operation of the Linac, the operator moves to the control room to make the 

radiographic exposure. All personnel remain in the control room during the exposure. There are 

numerous emergency stop switches on the walls inside the radiography bays, which disable or 

prevent the operation of the radiography equipment in the event personnel are accidentally trapped in

the bay. The control room is isolated from the Linac room such that exposure rates to personnel 

follow as low as reasonably achievable (ALARA) principles and do not exceed 0.25 millirem/hr. 

During operation of the portable unit, the operator would occupy the vestibule portion of the bay where 

exposure rates to personnel do not exceed 0.25 millirem/hr. The portable X-ray machine is operated 

via a control console connected to it by cables. The operator, after making the radiographic exposure, 

develops the film in the process/service room. The operator views the film, makes the appropriate 

verifications of internal structure, and completes the necessary forms to release the unit for work by

other departments.

The generic-use bays in these buildings can be configured for staging operations. Weapons and 

weapons components are held in staging bays in preparation for use in assembly, special testing, or 

transportation off the site. 
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2.2.2

The mounded earth and gravel cover over a cell is supported by a cable catenary system. The cables 

are suspended from the top of a cell's round room wall. The cell roof consists of the support cables, 

layers of wire mesh, gravel and earth coverings, and a Gunite or concrete cap. Figure 2-5 shows a 

generic cell design from Mitchell (2001).

Cells

Figure 2-5. Generic representation of a nuclear explosive cell. 

The design of the cells is based on Gravel Gertie experiments that show that the structure largely 

dissipates blast pressures (BWXT 2001). The mounded gravel roof over the round room is designed 

to lift and vent gas pressures produced in an explosion. Plutonium would be filtered from the vented 

gases by the gravel structure and release to the environment would be minimized. The equipment 

passageway doors are designed to remain intact in the event of accidental detonation, and the doors 

are interlocked so only one door can be open at a time. The two blast doors are also interlocked so 

only one door can be open.

The cell facilities consist of a round room, staging cubicles, a corridor area, and a unit 

equipment/mechanical room. All of these areas are inside the blast-resistant cell structure and 

provide protection from external events, including external explosions, winds, and tornados. The 

principal function of the assembly cells is the assembly and disassembly of nuclear explosives, 

particularly operations on the physics package of nuclear explosives that contain HE (BWXT 2001). 

Work on nuclear explosives that contain IHE can be in the bays. In the future, most of the operations 

in the cells are expected to involve the dismantlement of retired stockpile weapons.

The cells were designed as assembly/disassembly and inspection areas with the capability to process 

HE and nuclear explosives components that contain plutonium (BWXT 2001). The major operations 

conducted in cells are pit-HE assembly, pit-HE disassembly, and complete nuclear explosive 

assembly and disassembly. A number of specialized operations support quality assurance for these 

activities.

To comply with DOE and Pantex Plant requirements, plutonium-HE assembly and disassembly 

operations must be conducted in a cell-type structure where the design features of the facility afford 

an added margin of safety (DOE 2001). Partial assembly can be performed in a cell to the point 
Effective Date: 03/30/2004 Revision No. 00 Document No. ORAUT-TKBS-0013-2 Page 12 of 17

where the HE component is considered cased. In this configuration, completion of the assembly 

process is typically performed in the bay facilities.

Components for a particular program are sent to the operating cell performing the assembly (BWXT 

2001). Assembly operations are performed in designated cells according to NEOPs and other written 

procedures specific to a nuclear explosives program. Inspections and audits are performed to confirm 

that design specifications are met. Acceptance inspections are performed by DOE inspectors. During 

all phases of assembly, procedures specific to nuclear explosives are followed and checklists are 

initialed as each procedural step is completed. Once the nuclear explosive assembly is complete, it is 

sent to radiography (if required) to verify the presence of SNM and to confirm the position of the safing 

device. If required, the weapon is then sent to the vacuum chambers for final inspection and testing. 

During a limited (or partial) assembly, pits are transferred to the cells from the designated SNM 

staging facility at Pantex Plant. HE comes from an in-process staging facility for HE. Partial 

assembly in a cell typically results in a cased nuclear explosive assembly containing a pit mated with 

HE, which is then sent to an assembly bay facility for final assembly into a nuclear explosive.

Cells are also used extensively for the disassembly or partial disassembly of nuclear explosives that 

have been returned to DOE by DOD (BWXT 2001). Many of these nuclear explosives were designed 

and built without the added safety benefit of IHE. Therefore, disassembly operations must be 

completed in a cell after other component disassembly operations have been completed in other 

facilities.

Plutonium pit-HE assemblies are brought to the cells from other facilities in Zone 12 (BWXT 2001). 

Special tools and equipment are supplied from warehouse stocks. Some disassembly operations 

require a portable glove box or other specialized equipment. For plutonium pit-HE disassembly, 

personnel must use a safety net, safety latches, or SS-2l tooling and lead-shielded aprons, safety 

glasses, and approved gloves. Some operations require that portions of the round room floor be 

covered with a barrier paper taped to the floor. In the event of an accident or unanticipated 

contamination, this barrier paper can be peeled from the floor and disposed of as contaminated 

waste, which aids containment and cleanup. 

During disassembly, suspect components must be checked for radioactive contamination. If 

components are contaminated, decontamination procedures are performed before the components 

are transported.

2.2.3

The 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 (BWXT 

2001).

Special-Purpose Facilities

The Paint Facility is used to spray-paint weapons, components, and supporting container and 

transportation hardware. Radiation exposure rates to workers in the Paint Facility are comparable to 

those of transportation workers who move weapons containing nuclear materials, which are typically 

less than 100 mrem/yr. The Paint Facility is restricted to Nuclear Explosive Look-Alike assemblies. 

The coexistence of HE or IHE and SNM at the same time is not allowed in the paint bay.

Operations in the Separation Testing Facility involve functional separation tests of selected reentry 

body assemblies, which is a continuing requirement of the Weapons Surveillance Program. 

Separation tests are conducted remotely with authorized personnel in the control booth during the 
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entire test. Worker exposures to the weapons at the beginning and end of each test are brief, and 

cumulative radiation exposures are typically less than 100 mrem/yr. 

The Mass Properties Facility utilizes two bays and a remote control room. One of the bays has a 

spin-balancing machine that works much like a machine for balancing automobile tires. The weapon 

is placed in the machine and spun to measure any out-of-balance forces. The correct placing of 

balance weights on the weapon is determined from the results of the test. Another bay measures the 

center of gravity of the weapon and the moment and product of inertia of the weapon. Worker 

exposures to the weapons at the beginning and end of each test are brief, and cumulative radiation 

exposures are typically less than 100 mrem/yr.

The Weapons Aging Facility places the weapon or related weapon component in an enclave that 

controls the temperature of the atmosphere in the enclave such that the weapon components are 

aged artificially over an accelerated timeframe. As in the case of the Mass Properties and Separation 

Test Facilities, the operations are observed and controlled from a remote control room. Worker 

exposures to the weapons at the beginning and end of each test are brief, and cumulative radiation 

exposures are typically less than 100 mrem/yr. 

The Weapons Transfer Station is used for loading and unloading weapons, weapon components, or 

explosives. It is a completely enclosed high dock that accommodates over-the-road trailers and 

forklifts. 

2.2.4

Zone 4 facilities are used as a staging or interim storage area for weapons, weapon components, and 

other process-related materials (BWXT 2001). Periodic inspection of the pits is required; process 

technicians accompanied by radiation safety technicians perform this operation. Personnel are 

exposed isotropically to radiation sources during this work.

Nuclear Staging Facilities

Zone 12 staging facilities, including pit vaults, warehouses, and SNM component staging facilities, are 

where nuclear explosive components without HE are staged (BWXT 2001). Pits are encapsulated 

components packaged in specially designed containers for staging and transportation between 

facilities. Radioisotope thermal generators are small, self-contained, sealed 238Pu sources of 

thermally generated electricity. Tritium reservoirs are small metal bottles filled with tritium gas. 

2.3 PANTEX RADIATION PROTECTION PROGRAM

The radiation protection program at Pantex evolved gradually over time, with a major expansion after 

the tritium release incident in May 1989. A radiation dosimetry program was established at Pantex in 

1952 by the manager of the radiography group. The technology of the program has evolved over the 

past 50 years from simple film badges to sophisticated thermoluminescent dosimeter (TLD) systems. 

Steps in the evolution are shown in Figure 2-6. Each of these steps is described in detail in the 

Pantex Occupational External Dose technical basis document. The records of radiation doses to 

individual workers from personnel dosimeters represent the highest quality records for retrospective 

dose assessments. 

The radiation protection program was focused on those most likely to be exposed to radiation: 

production technicians, material handlers, transportation workers, radiography technicians, quality 

control technicians, and warehouse-production workers. These workers and their exposure potential 

are described in the Pantex Occupational External Dose TBD. All other workers at Pantex had little 
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 Tracerlab β,γ film

 <---------------------> 

 + NTA film

 <--------> 

 Eberline β,γ,NTA film

 <--> 

 Landauer β,γ,NTA film

 <----------------------> 

 Pantex In-House TLD

 Two-element

<--> 

 Six-element

 <--------> 

 Panasonic 802

 <-------------------------//////////>

 Panasonic 809/812

 <------------------------

 1950 1960 1970 1980 1990 2000

Figure 2-6. Evolution of external dosimetry at Pantex

occasion to enter any radiological areas and their potential for radiation exposure or intakes of 

radioactive material is considerably less.

From 1951 to about 1980, nuclear weapon assembly operations were generally free of contamination. 

Occasional checks for removable contamination generally demonstrated negative results, so few 

precautions were taken in relation to personal protective equipment and clothing. There was no 

evidence of any intakes of radioactive materials by Pantex workers. The major emphasis was on 

monitoring external radiation exposure by the methods shown in Figure 2-6. 

In 1972, a modest bioassay program was begun for monitoring worker exposures to tritium; in 1976, 

the program was expanded for a 4-year period with generally negative results. In the early 1980s, 

with the increasing disassembly of weapons that had been in varying environments, DU 

contamination became a greater concern and additional radiation protection resources were applied 

to contamination control. In 1988, an extensive bioassay program for workers exposed to DU 

contamination was implemented. These bioassay programs are described in detail in the Pantex 

Occupational Internal Dose TBD. 

Airborne contamination is monitored with alpha continuous air monitors (CAMs) and tritium monitors. 

The air monitoring system was first installed in the early to mid-1970s. The alpha CAM system 

frequently responds to elevated radon concentrations, but has rarely detected airborne concentrations 

of uranium, thorium, or plutonium. The tritium monitors frequently respond to minor local releases of 

tritium gas. The few occasions when airborne contamination was detected are documented in 

incident reports, which are reviewed in the Pantex Occupational Internal Dose TBD.

Following the tritium release incident in May 1989, the radiation protection program expanded rapidly. 

In May 1989 there were only seven staff members in the Radiation Safety Department; by mid-1991 

the staff had expanded to 50 and new facilities and modern equipment were added. 
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2.4 GENERAL RADIATION EXPOSURE CHARACTERISTICS

The general radioactive source terms have been consistent throughout the history of Pantex, with few 

exceptions. From 1951 to the present, depleted uranium and tritium have been present at Pantex. 

During assembly, the DU was relatively clean and minimal removable contamination was 

encountered. The tritium was received in sealed reservoirs, and leakage was not a concern during 

assembly. Minor leakage occurred during disassembly. From 1958 though the present, sealed 

plutonium pits and enriched uranium components were received, handled, and stored at Pantex. With 

two minor exceptions, plutonium has always been contained by the pit cladding. In the 1960s, some 

thorium components were assembled into weapons, and during the 1990s these weapons were 

disassembled. These source terms are approximately the same for Zone 4 and Zone 12. There are, 

and have been, a few other radioactive materials present in small quantities as calibration sources or 

in larger quantities as radiography sources. These source terms are discussed in more detail in the 

Pantex Occupational External Dose TBD. 

Radiation exposures occur at Pantex when workers are involved in operations with radioactive 

materials, such as the assembly or disassembly of nuclear weapons. The primary sources of external 

radiation exposure are plutonium pits and DU or thorium components. The primary sources of 

radioactive contamination (which can lead to intake) are depleted uranium oxide and tritium.

Plutonium pits are sealed to prevent surface contamination problems. Enriched uranium components

are solid, hermetically sealed units. 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 

dose rates. Workers wear lead aprons during pit-handling work, which substantially reduce lowenergy 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 be underestimated. Beta and photon exposures occur during 

handling of DU or thorium components. The rule-of-thumb beta dose rate of approximately 200 

millirad/hr at the surface of a DU slab can be used to estimate worker exposures. Exposures to 

thorium include the penetrating 2.6-MeV photons from 208Tl. 

The major radioactive contamination concern is DU oxide during disassembly operations. DU 

components tend to oxidize while in the field, and during disassembly this oxide is present as a readily 

dispersible powder. The TBD on Pantex Occupational Internal Dose discusses this contaminant. 

Contamination on thorium components is much less significant. In addition, tritium contamination is a 

concern; minor tritium intakes occur routinely but with very little whole-body dose. The one exception 

is the Cell 1 incident in 1989, which is discussed in detail in the Pantex Occupational Internal Dose

TBD. 
Effective Date: 03/30/2004 Revision No. 00 Document No. ORAUT-TKBS-0013-2 Page 16 of 17

REFERENCES

AEC (U.S. Atomic Energy Commission), 1952, Progress Report to the JCAE, June-Nov, 1951, 3, 

Semi-Annual Management Report, July 1, 1952 - December 31, 1952, (Pantex Plant), 9, 

Proctor and Gamble Defense Corporation, Pantex Ordnance Plant, Amarillo, Texas.

BWXT (Babcock & Wilcox Technologies, Inc.), 2001, Safety Information Document in Support of the 

National Environmental Policy Act Documents for Pantex Plant, BWXT Pantex, Amarillo, 

Texas.

DOE (U.S. Department of Energy), 1997, Linking Legacies: Connecting the Cold War Nuclear 

Weapons Production Processes to Their Environmental Consequences, DOE/EM-0319, Office 

of Environmental Management, Washington, D.C.

DOE (U.S. Department of Energy), 2001, Safety of Nuclear Explosives Operations, DOE Order 

452.2B, Washington, D.C.

Gaither, S., 1995, Ordnance Production in the Texas Panhandle: The Pantex Ordnance Plant, 

Amarillo, Texas 1942-1945, Miscellaneous Report of Investigations, Number 92, Geo-Marine, 

Inc.

Martin, J. B., 2003a, "Conversation with B. H. Carr, Pantex (retired), in relation to early history of 

Pantex operations, September 2003," memorandum to file, September 22, 2003, Pacific 

Northwest National Laboratory, Richland, Washington.

Martin, J. B., 2003b, "Conversation with E. E. Poore, Pantex Training Manager, in relation to training 

records of Pantex operations, September 2003," memorandum to file, September 24, 2003, 

Pacific Northwest National Laboratory, Richland, Washington.

Mitchell, K. C., 2001, Rhetoric to Reality: A Cold War Context Statement for the Pantex Plant, 

1951-1991, BWXT Pantex, Amarillo, Texas.
Effective Date: 03/30/2004 Revision No. 00 Document No. ORAUT-TKBS-0013-2 Page 17 of 17

GLOSSARY

depleted uranium

Uranium with a smaller percentage of the isotope 235U than the 0.7% found in natural uranium.

Gravel Gertie cell

Heavily bunkered facilities designed to minimize the blast effects and the release of hazardous 

materials from areas in which assembly and disassembly of nuclear devices occur; 

characterized by a cable-supported roof of wire mesh and a thick gravel overburden.

high explosive

A chemical compound or mechanical mixture that, when subjected to heat, impact, friction, 

shock, or other initiation stimulus, undergoes a rapid chemical change with the evolution of 

large volumes of highly heated gases that exert pressure in the surrounding medium.

insensitive high explosive

High explosive that is so insensitive that there is negligible probability of accidental initiation or 

transition from burning to detonation.

Nuclear Explosive Look-Alike (NELA) assemblies 

Non-nuclear assemblies that represent a nuclear explosive in its basic configuration, but do

not contain any fissile radioactive material.

pit

Fissile component designed to fit in the central cavity of an implosion system to create a 

nuclear explosive.

special nuclear material 

Plutonium, tritium, and uranium enriched in the isotopes 233 or 235, but not source material 

(natural uranium and thorium).

tritium reservoirs 

Gas-tight metal containers used to store tritium gas.