ORAU TEAM

Dose Reconstruction

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller I MJW Technical Services

Page 1 of 42

DOE Review Release 01/14/2014

Document Title:

Pantex Plant – Occupational Environmental 

Dose

Document Number: ORAUT-TKBS-0013-4

Revision: 02

Effective Date: 01/03/2014

Type of Document: TBD

Supersedes: Revision 01

Subject Expert(s): Dale D. Thomas III

Approval: Signature on File Approval Date: 12/20/2013

Dale D. Thomas III, Document Owner

Concurrence: Richard E. Merrill Signature on File for Concurrence Date: 12/20/2013

John M. Byrne, Objective 1 Manager

Concurrence: Signature on File Concurrence Date: 12/20/2013

Edward F. Maher, Objective 3 Manager

Concurrence: Vickie S. Short Signature on File for Concurrence Date: 12/20/2013

Kate Kimpan, Project Director

Approval: Signature on File Approval Date: 01/03/2014

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-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 2 of 42

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

08/24/2004 00 New technical basis document for the Pantex Plant – Occupational 

Environmental Dose. Incorporates internal review and NIOSH 

comments. Incorporates additional internal review and NIOSH 

comments. First approved issue. Initiated by Dillard B. Shipler.

06/22/2007 01 Revised to include Attributions and Annotations. Constitutes a total 

rewrite of the document. Incorporates formal internal review 

comments. No changes were needed as a result of formal NIOSH

review. This revision results in no change to the assigned dose and 

no PER is required. Initiated by John J. Fix.

01/03/2014 02 Revision initiated to clarify dose assignments. Updated Section 4.1. 

Added paragraphs to Attachment A for clarification of dose 

assignments. Updated format; includes editorial changes. Added 

Tables A-3 and A-4 to simplify on-site ambient dose assignment. 

Figure 4-4 was deleted. 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.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 3 of 42

TABLE OF CONTENTS

SECTION TITLE PAGE

Acronyms and Abbreviations ............................................................................................................... 5

4.1 Introduction .............................................................................................................................. 7

4.1.1 Purpose........................................................................................................................ 8

4.1.2 Scope........................................................................................................................... 8

4.1.3 Special Exposure Cohort Information ........................................................................... 8

4.1.3.1 January 1, 1958, through December 31, 1983 ............................................... 8

4.1.3.2 January 1, 1984, through December 31, 1991 ............................................... 9

4.2 Internal Dose from Onsite Atmospheric Radionuclide Concentrations...................................... 9

4.2.1 Onsite Releases to Air................................................................................................ 11

4.2.1.1 Tritium.......................................................................................................... 14

4.2.1.2 Uranium ....................................................................................................... 15

4.2.1.3 Plutonium..................................................................................................... 15

4.2.1.4 Thorium........................................................................................................ 15

4.2.2 Rationale for Showing that Organ Doses Due to Intakes of Environmental 

Levels of Radionuclides at Pantex Are Negligible....................................................... 16

4.2.2.1 Negligible Individual Dose Level................................................................... 16

4.2.2.2 Evidence that Onsite Airborne Uranium and Thorium Levels Are 

Mostly of Natural Origin................................................................................ 16

4.2.2.3 Upper 95% Confidence of the Mean Net Concentration ............................... 17

4.2.2.4 Dose Coefficients......................................................................................... 18

4.2.2.5 Criteria for Determining that Maximum Credible Intakes Lead to Doses 

Less than 10 Microsievert to Most Highly Dosed Tissue or Organ................ 19

4.2.3 Annual Intakes from Resuspension ............................................................................ 21

4.3 External Dose ........................................................................................................................ 23

4.3.1 Ambient Radiation ...................................................................................................... 23

4.4 Uncertainty............................................................................................................................. 26

4.5 Attributions and Annotations .................................................................................................. 27

References ........................................................................................................................................ 32

Glossary ............................................................................................................................................ 37

ATTACHMENT A, RADIONUCLIDE INTAKE AND OCCUPATIONAL EXPOSURE........................... 40
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LIST OF TABLES

TABLE TITLE PAGE

4-1 Annual releases to atmosphere.............................................................................................. 13

4-2 Maximum values of 95% upper confidence intervals of means or net means ......................... 18

4-3 Dose conversion coefficients and air concentrations leading to 10 μSv for 3

H, 232Th, 

234U, and 239Pu .......................................................................................................................19

4-4 Climatological data for 2000 by month ................................................................................... 23

4-5 Calculated difference between onsite and offsite annual doses for the Pantex Plant.............. 26

A-1 References for maximum air concentrations for tritium (oxidized), thorium, uranium, 

and plutonium used in Section 4.2.2 dose analyses............................................................... 41

A-2 Upwind “control” (location OA-AR-13) average annual air concentration................................ 41

A-3 Maximizing onsite ambient doses........................................................................................... 41

A-4 Best-estimate onsite ambient doses....................................................................................... 42

LIST OF FIGURES

FIGURE TITLE PAGE

4-1 Pantex Plant site ....................................................................................................................10

4-2 Isotopic contributions to offsite dose from Pantex operations in 2000 .................................... 11

4-3 Air monitoring stations in 2000 ............................................................................................... 12

4-4 Pantex 238U and thorium mean environmental air monitoring data for 2000 at seven 

locations.................................................................................................................................17

4-5 Pantex 238 U and thorium mean environmental air monitoring data (historic) at seven 

locations.................................................................................................................................17

4-6 IMBA equivalent dose to four tissues or organs per unit intake during each year for 

1-μm AMAD type W 232Th inhalation ...................................................................................... 20

4-7 IMBA equivalent dose and average equivalent dose to bone surfaces per unit intake 

during each year for 1-μm AMAD type W 232Th inhalation ...................................................... 21

4-8 IMBA annual equivalent dose to bone surfaces for 10-, 20-, 30-, 40-, and 50-year 

inhalation intakes of 1 Bq/yr of 1-μm AMAD type W 232Th ...................................................... 21

4-9 Wind rose for 2000................................................................................................................. 22

4-10 Locations of thermoluminescent dosimeters in 2000.............................................................. 24

4-11 Ambient dose rates for Pantex Plant ...................................................................................... 25
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 5 of 42

ACRONYMS AND ABBREVIATIONS

AMAD activity median aerodynamic diameter

ASER annual site environmental report

Bq becquerel

Ci curie

CED committed equivalent dose

CEDE committed effective dose equivalent

CFR Code of Federal Regulations

CY calendar year

DHHS U.S. Department of Health and Human Services

DOE U.S. Department of Energy

DOL U.S. Department of Labor

DU depleted uranium

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000

EMR environmental monitoring report

F fast absorption type

g gram

HE high explosive

hr hour

ICRP International Commission on Radiological Protection

IMBA Integrated Modules for Bioassay Analysis

in. inch

m meter

M moderate absorption type

mm millimeter

mrem millirem

mph miles per hour

mSv millisievert

NCRP National Council on Radiation Protection and Measurements

NIOSH National Institute for Occupational Safety and Health

ORAU Oak Ridge Associated Universities

POC probability of causation

s second

S slow absorption type

SRDB Ref ID Site Research Database Reference Identification (number)

Sv sievert

TBD technical basis document

TBq terabecquerel

TLD thermoluminescent dosimeter
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 6 of 42

U.S.C. United States Code

yr year

μBq microbecquerel

μCi microcurie

μm micrometer

μSv microsievert

§ section or sections
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 7 of 42

4.1 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 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 NIOSH staff in the completion of the individual work required for each dose reconstruction.

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

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

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

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

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

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

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

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

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

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

facility encompassed by EEOICPA.

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

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

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

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

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

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

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

determined in accordance with the POC [probability of causation1

] 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, 42 C.F.R. Pt. 82) restrict the “performance of duty” 

referred to in 42 U.S.C. § 7384n(b) to nuclear weapons work (NIOSH 2010).

The statute also 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 excludes Naval Nuclear Propulsion Facilities from being covered under the Act, 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 occupational radiation exposures are considered valid for inclusion in a 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 

occupationally derived (NIOSH 2010):

• 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

 1 The U.S. Department of Labor (DOL) is ultimately responsible under the EEOICPA for determining the POC.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 8 of 42

4.1.1 Purpose

The purpose of this technical basis document (TBD) is to describe the Pantex Plant occupational 

environmental doses. The Oak Ridge Associated Universities (ORAU) Team will use this information 

as needed to evaluate environmental doses for EEOICPA claims.

4.1.2 Scope

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

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

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

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

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

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

performs these operations.

The occupational environmental dose is the dose received by workers on the site but outside facilities. 

This dose can be internal and external depending on the characteristics of the individual 

radionuclides. Radionuclides at the Pantex Plant have included tritium, uranium, plutonium, and 

thorium. Pantex neither uses or releases noble gases (BWXT Pantex 2001). While most inhaled 

radionuclides would give a dose to particular organs in the body, tritium gas would give a dose to the 

whole body. Sections 4.2 and 4.3 discuss internal and external dose, respectively, from these 

radionuclides at Pantex. Section 4.4 discusses uncertainty. Attributions and annotations, indicated 

by bracketed callouts and used to identify the source, justification, or clarification of the associated 

information, are presented in Section 4.5.

4.1.3 Special Exposure Cohort Information

4.1.3.1 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 Special Exposure Cohort (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 (DHHS 2011), DHHS finds that it lacks sufficient personnel or area monitoring data, source 

term data, and operational information to support reconstructing internal dose from intakes of uranium 

with sufficient accuracy from January 1, 1958 through December 31, 1983 at the Pantex Plant in 

Amarillo, Texas. Reconstruction of thorium intakes with sufficient accuracy is not feasible for all 

workers during the same period since the proposed method for estimating those intakes depend on 

the reconstruction of uranium intakes. However, reconstruction of doses from radon is feasible based 

on workplace measurements. Plutonium and thorium intakes can be reconstructed for individuals 

who have specific monitoring results for those radionuclides. Tritium doses can be reconstructed 

based on tritium bioassay results from monitored workers. Although DHHS found that it is not 

possible to completely reconstruct internal radiation doses for the proposed class, NIOSH can use 

any internal monitoring data that might become available for an individual claim (and that can be 

interpreted using existing NIOSH dose reconstruction processes or procedures). Therefore, dose 
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 9 of 42

reconstructions for individuals employed at 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 a partial dose reconstruction.

4.1.3.2 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 (DHHS 2013), DHHS found it lacks sufficient information to reconstruct internal radiation 

doses adequately for all Pantex Plant employees from intakes of uranium and thorium with sufficient 

accuracy from January 1, 1984, through December 31, 1991, at the Pantex Plant in Amarillo, Texas. 

Specifically, DHHS found that the available monitoring data, as well as available process and source 

term information for the Pantex Plant was inadequate to estimate with sufficient accuracy the internal 

doses from potential exposures to uranium during the period from 1984 through 1990, and to thorium 

from January 1, 1984, through December 31, 1991. However, tritium internal doses can be 

reconstructed for the period based on the available tritium bioassay data. Although DHHS found that 

it is not possible to completely reconstruct internal radiation doses for the proposed class, NIOSH can 

use any internal monitoring data that might become available for an individual claim (and that can be 

interpreted using existing NIOSH dose reconstruction processes or procedures). Therefore, dose 

reconstructions 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 a partial dose reconstruction.

4.2 INTERNAL DOSE FROM ONSITE ATMOSPHERIC RADIONUCLIDE 

CONCENTRATIONS

The internal dose to workers outside facilities is determined from air concentrations that resulted from 

individual facility releases, ground-level releases (e.g., burning activities), and the resuspension of 

radioactive materials in soil. Unmonitored workers could have received internal or external 

occupational doses (or both) from any or all of these sources. Figure 4-1 shows the major areas of 

the Pantex Plant site.

To determine the offsite effective dose equivalent from airborne releases, Pantex used the U.S. 

Environmental Protection Agency-approved CAP88-PC computer program to evaluate the radiological 

dose that a member of the public could receive during the year (BWXT Pantex 2001, pp. 72–73). 

Figure 4-2 shows the percent contributions to dose that resulted (BWXT Pantex 2001). The results 

indicate the importance to dose of the various radionuclides involved in Pantex operations.

The analysis encompassed all potential environmental pathways for radioactive material released to 

the air. The source terms for releases to air result from process knowledge, the number of operations 

during the year, and other modifying factors. The source terms represent the maximum possible 

releases from a point (stack or vent), an area, or both. Actual releases to the air were much less than 

the maximum estimates, which are essentially the minimum limits of monitoring or detection 

equipment. The total estimated releases and monitoring data from the site were available, but not 

specific source terms [1].
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 10 of 42

Figure 4-1. Pantex Plant site (BWXT Pantex 2001).
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 11 of 42

Figure 4-2. Isotopic contributions to offsite dose from Pantex operations in 2000 (BWXT Pantex 

2001).

4.2.1 Onsite Releases to Air

Information on releases of radionuclides from Pantex facilities during the Plant’s operating period from 

1952 through 2000 was obtained from environmental monitoring reports (EMRs) and annual site 

environmental reports (ASERs) (Alexander 1974, 1975, 1976, 1977; Alexander, Cornelius, and Horton 

1978; Alexander and Cornelius 1979, 1980; Alexander and Laseter 1981; Laseter 1982, 1983, 1984, 

1985, 1986, 1987; Laseter and Langston 1988, 1989; MHSMC 1990, 1991; Battelle and MHMSC 

1992, 1993, 1994, 1995; DOE 1996, 1997; Battelle and MHC 1998; DOE 1999, 2000; BWXT Pantex 

2001, 2002a, 2003), annual summaries of radiological doses and releases reported to DOE (DOE 

1982, 1984, 1992, 1994; BMI 1985, 1988, 1990a, 1990b; PNL 1993; PNNL 1997a, 1997b), radiation 

safety department incident records (MHSMC 1986), and radiation safety department technical basis 

manuals (BWXT Pantex 2002b). EMRs and ASERs contain air release and soil monitoring data, and 

thermoluminescent dosimeter (TLD) monitoring data from on and off the site. Table 4-1 summarizes 

releases to the atmosphere from plant vents. Figure 4-3 shows air sampler locations.

A review of the references determined that the monitoring data are representative for assessing dose. 

The analysis considered the release and monitoring data, coupled with understanding of historical 

meteorology (Snyder 1993), to be adequate estimates of radionuclide-specific airborne concentrations 

for 3

H, 238Pu, 239/240Pu, 233/234U, and 238U. The uranium used in weapons at Pantex is depleted uranium 

(DU) that consists primarily of 238U and small amounts of 234U, 235U, and 236U, all of which are alpha 

particle emitters with long half-lives (Battelle 1992, Chapter 5). The 235U is about 1% of the total 

activity in DU [2]. Because 233U and 234U cannot readily be chemically separated, they are measured 

and reported together. In reality, there is no 233U on the Pantex Plant [3]. Though small quantities of 

232Th were released from Pantex facilities, “monitoring of 232Th was not consistent because the 

releases were small and contributed little to dose, as well as that 232Th is a naturally occurring form of 

the element” (BWXT Pantex 2001).
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Figure 4-3. Air monitoring stations in 2000 (BWXT Pantex 2001).
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 13 of 42

Table 4-1. Annual releases (curies) to atmosphere. 

Year Tritium

Total 

uranium

Total 

plutoniuma All others Reference

1981 9.5E-02 1.0E-05 -- -- DOE 1982

1983 5.0E-02 1.0E-05 -- -- DOE 1984

1984 1.2E-04 -- -- -- BMI 1989

1985 -- -- --

1986 1.3E-01 1.0E-05 -- -- BMI 1988

1987 9.6E-02 -- -- -- BMI 1990b

1988 1.2E-01 -- -- -- BMI 1990a

1989 4.0E+04 2.1E-05 -- -- PNL 1993

1990 2.55E+03 -- MHSMC 1991

1991 1.7E-01 -- -- -- DOE 1992

1992 1.3E-01 -- -- 3.5E-07 DOE 1994

1993 3.0E-01 -- -- -- Battelle and MHSMC 1994

1994 4.46E-01 -- -- -- Battelle and MHSMC 1995

1995 1.0E-01 -- -- -- DOE 1996

1996 1.3E-01 1.46E-04 -- 1.67E-17 232Th DOE 1997

1997 1.17E-01 1.32E-04 1.27E-09 232Th Battelle and MHC 1998

1998 5.34E-02 1.78E-04 -- 1.59E-08 232Th DOE 1999

1999 1.58E+00 6.97E-05 -- 7.14E-07 232Th DOE 2000

2000 2.71E+00 6.73E-07 -- 2.76E-07 232Th, 

3.28E-06 All other 

radionuclides

BWXT 2001

a. = no releases.

It was assumed that monitoring data, and particularly air monitoring data, is appropriate for dose 

reconstruction and account for resuspension of radionuclides in soil. Particularly, monitoring data 

account for the accumulation of long-lived radionuclides in soil during the life of the Plant. In addition, 

the occurrence of radioactive materials on site changed over time, as follows:

• In 1956, tritium began arriving in sealed containers (ORAUT 2004).

• In 1958, plutonium began arriving in sealed metal forms (ORAUT 2004).

• Thorium began arriving at the plant as new, bare metal forms in the 1960s (ORAUT 2004).

In addition, operations changed over the years:

• From 1952 to 1958, the only operation at Pantex was weapons assembly (ORAUT 2004).

– No tritium containers were manipulated, so no tritium was released [4].

– No metal oxides formed or burned, so no metal oxides were released [5].

– No testing involving radioactive material was performed [6].

– Small amounts of tritium were released when weapons were disassembled [7].

– There are no specific data to substantiate specific releases of tritium prior to 1972 [8].

– Some DU was released at the burning grounds with the burning of high-explosive (HE) 

components (ORAUT 2007a).

– Some DU was released at the firing sites when HE firings involved DU components 

(ORAUT 2007a).
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– Starting in 1958, all assembly and disassembly operations were on complete sealed-pit 

weapons (Mitchell 2003).

• From 1958 to 1979, the primary operation at Pantex was weapons assembly (Mitchell 2003). 

Some component testing was performed. A small number of weapons were disassembled for 

testing and quality control.

• From 1980 to 1990, disassembly of weapons was performed more often than assembly 

(DOE 2001a).

• From 1990 to the present, the primary operation at the plant has been large-scale disassembly 

of weapons (DOE 2001a).

Although 238Pu has been part of the monitoring program in recent years, the monitoring was to 

establish background concentrations in anticipation of a program that would have involved 238Pu. 

However, that program never started and unencapsulated 238Pu was never on the Pantex Plant 

(Griffis 2004).

With the exception of hydrodynamic testing, it is evident from this information that operations that 

could lead to releases of radioactive materials were limited until about 1980 [9]. Table 4-1 lists site 

release data from 1981. Although operations have increased with time and employment, releases 

from operations have been relatively stable and remain small. As a result, atmospheric dispersion 

modeling was deemed unnecessary [10]. This selection was based on the maturity of the monitoring 

program, the technical level of analytical techniques, and the application of quality programs [11]. In 

other words, these are the best available data.

Considering time-related operations, time-related presence of radioactive materials on the site, and 

the small concentrations of radioactive materials in the air and soil when releases of radioactive 

materials could have occurred after 1980, initial analyses of potential intakes and resulting doses 

indicated that potential doses from intakes would be negligible [12]. Additional guidance for 

evaluation of potential intake based on the type of worker and location is provided in the latest 

revision of ORAUT-TKBS-0013-5, Pantex Plant – Occupational Internal Dose (ORAUT 2007a).

4.2.1.1 Tritium

Tritium is one of the principal nuclear materials used at the Pantex Plant. It is the heaviest and only 

radioactive isotope of hydrogen, with a physical half-life of 12.35 years. Nuclear operations involving 

tritium have occurred at Pantex since 1956.

Tritium comes to Pantex in sealed containers that are placed into nuclear assemblies without being 

opened. Therefore, no tritium releases occur during normal assembly operations. Small amounts of 

tritium (a few microcuries per unit) are routinely released during disassembly operations [13].

A major unplanned accident that resulted in a tritium release occurred at Pantex on May 17, 1989, 

when a conservatively estimated 40,000 Ci were released in a Gravel Gertie cell (ORAUT 2007b). It 

was assumed that all the tritium leaked from the cell and the building within 12 days; doses were 

estimated for that period. The estimated potential individual whole body-dose was 1.43 mrem at the 

closest downwind fenceline (MHSMC 1990). The estimated maximum individual onsite dose in the 

downwind direction (north-northeast) was about 10 times the fenceline dose (MHSMC 1990). 

Therefore, dose reconstructors should assign a 15-mrem dose to the whole body for a worker in the 

area during that period [14].
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At the beginning of 1990, an estimated 2,550 Ci of residual tritium remained trapped in the walls and 

gravel overburden of the cell in which the 1989 release occurred (MHSMC 1991). The analysis 

conservatively assumed that this entire amount was released to the atmosphere during 1990. The 

estimated maximum individual onsite dose in the downwind direction (north-northeast) was 1.0 mrem. 

Therefore, dose reconstructors should also assign a 1-mrem dose to the whole body for a worker in 

the area during that period [15].

4.2.1.2 Uranium

Uranium arrives at Pantex as a metal (DU, primarily 238U), uncoated and unsealed (ORAUT 2004). 

Uranium oxidizes fairly readily in air. When aged weapons are dismantled for inspection, 

refurbishment, or disassembly, significant amounts of uranium oxide powder can be associated with 

the parts with which it has come in contact [16]. One type of these parts is the HE, which is generally 

destroyed by burning. During the burning, associated powdered uranium is released to the 

atmosphere (ORAUT 2007a).

The alpha-emitting radionuclides of this uranium represent a potential radiological risk if inhaled. 

Isotopes known to be present through measurement include 233/234U and 238U. Dose reconstructors

should assume that 234U, the isotope that results in the maximum organ dose, is present at 100%. 

This assumption results in a small overestimation of the actual dose that is favorable to the claimant 

(BWXT Pantex 2001).

The only unplanned release of uranium occurred on January 10, 1986, when exhaust fans were 

inadvertently turned on and off several times after a test detonation at Firing Site 23. This action 

resulted in the release of particulate material containing DU (BWXT Pantex 2004). All personnel in 

the area were upwind (northeast at that time) of the release point. The release lasted a short time 

(1 to 2 minutes) (BWXT Pantex 2004). The curie activity of this release was not monitored, and soil 

samples could not determine event deposition because previous uncontained test shots had 

contaminated the area around the Firing Site (MHSMC 1986).

4.2.1.3 Plutonium

Plutonium concentrations are very low (e.g., around 0.01 to 0.02 μBq/m3

); they can probably be

accounted for by fallout from atmospheric testing because plutonium arrives at Pantex as sealed pits, 

which preclude oxidation or other means of dispersal (BWXT Pantex 2001). Even when aged 

weapons are dismantled for inspection or refurbishment, plutonium is not available in a form for 

release [17].

4.2.1.4 Thorium

Thorium releases to the atmosphere have not been routinely monitored as have uranium, plutonium, 

and tritium (BWXT Pantex 2001), although monitoring for thorium has been a component of the 

environmental monitoring program (at least in air and soil since about 1998). Although thorium arrives 

at the Plant as an uncoated and unsealed metal, it does not oxidize readily. Even when aged 

weapons are dismantled for inspection or refurbishment, little or no thorium is available in a form for 

release. Any thorium released would likely be ThO2 and International Commission on Radiological 

Protection (ICRP) absorption type S (ICRP 1996) [18].
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 16 of 42

4.2.2 Rationale for Showing that Organ Doses Due to Intakes of Environmental Levels of 

Radionuclides at Pantex Are Negligible

4.2.2.1 Negligible Individual Dose Level

The National Council on Radiation Protection and Measurements (NCRP) has defined a negligible 

individual effective dose as 10 μSv (1 mrem) per year (NCRP 1993). It follows that an annual dose to 

an organ or tissue that is 10 μSv (1 mrem) or less is also negligible. Furthermore, a committed dose 

of 10 μSv (1 mrem) or less to an organ or tissue from intakes during a year is also negligible. If it can 

be shown that measured airborne concentrations of radionuclides in the Pantex environment are 

negligible in the sense that they produce negligible doses using these criteria, then no effort need be 

expended to assess them [19].

4.2.2.2 Evidence that Onsite Airborne Uranium and Thorium Levels Are Mostly of Natural 

Origin

Of the four principal measured radionuclides in the air at Pantex, 232Th and uranium occur naturally, 

while 3

H and plutonium do not occur in significant quantities in nature (BWXT Pantex 2001). A 

concentration from which a background or control value has been subtracted is called a “net 

concentration.” Because nonzero concentrations of 232Th and uranium are observed off the site due 

to natural sources that are not related to Pantex operations, it is logical to subtract such “control” 

values from observations at the Plant. Thorium and uranium emissions from Pantex operations are 

unlikely to have temporal correlation with each other because they arise from different campaigns. 

The observation that uranium air concentrations at a given sampler location correlate strongly with

thorium air concentrations at that location supports the hypothesis that much of the uranium and 

thorium is due to uranium and thorium in local dust, not to uranium and thorium releases from Pantex 

operations. These correlation coefficients (r

2

) are 0.854 for the 2000 means and 0.895 for the historic 

means, with seven data pairs contributing to each, as shown in Figures 4-4 and 4-5, respectively.

A further argument that all or virtually all of the uranium in Pantex air samples is of natural origin is the 

isotope ratio of 233/234U to 238U. For 2000, this ratio is 1.007 ±0.037 (1 standard deviation), and for the 

historical data it is 0.981 ±0.086 (1 standard deviation). If the uranium were DU from the vast majority 

of Pantex uranium operations, the ratio would be 0.127 (DOE 2001b). The expected value of this 

ratio is 1.000 for natural uranium, in which 234U is in secular equilibrium with 238U and their activities 

are equal.

The credible upper bound concentrations to which workers could have been exposed in a year are 

equal to the upper 95% confidence of the mean net concentration [20]: 

,95 . . C C mzx cred = net [21] (4-1)

A worker performing light work breathes 1.2 m3 of air per hour. Assuming a 2,000-hour work year, the 

worker takes in the radioactive material in 2,400 m3 during a year. The credible upper bound intake is 

therefore:

3 ,95 I mC mzx cred . . = × 2,400 net (4-2)
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 17 of 42

Figure 4-4. Pantex 238U and thorium mean 

environmental air monitoring data for 2000 at 

seven locations (BWXT Pantex 2001).

Figure 4-5. Pantex 238 U and thorium mean 

environmental air monitoring data (historic) at 

seven locations (BWXT Pantex 2001).

4.2.2.3 Upper 95% Confidence of the Mean Net Concentration

Environmental data for Pantex (Attachment A, Table A-1) was used to calculate the values in 

Equation 4-1. The standard error S.E. of a value C is related to the standard deviation S.D. by the 

reciprocal of the square root of the number n of measurements:

. .( ) . .( ) SD C SE C

n = (4-3)

The upper 95% confidence level of the mean C95 is the mean increased by adding the standard 

normal deviate for 0.95; that is, 1.645 times the standard error of the mean, so that:

C C SE C 95 =+ × 1.645 . .( ) (4-4)

The upper 95% confidence level of the mean net concentration C95,net (assuming the same number of 

measurements was made of each) is:

95,net background background

2 2 background background

( ) 1.645 . .( )

( ) 1.645 { . .( )} { . .( )}

C CC SE C C

C C SE C SE C

=− + × −

=− + × +

(4-5)

The maximum values for thorium and uranium, the two elements for which net concentrations are 

needed, are listed in Table A-1, as are the references for the maximum value for plutonium and 3

H.

The observed 95% upper confidence intervals of the net means were calculated for Pantex for 

calendar year (CY) 2000 and for historical means. For the latter, it was necessary to estimate the 

standard error of the means because the standard deviations for the historic data are not given. The 

standard deviation of the population of means was assumed to be a reasonable estimate of the 

standard error of the mean of an individual measurement. Table 4-2 lists the greatest onsite (that is, 

“onsite” or “fenceline” but not “offsite”) values [22].

Pantex Environmental Air Monitoring Data 

for CY 2000; r^2 = 0.854

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3

Th Mean (Bq/m3)

U Mean (Bq/m3) .

U Mean

y=x

Fit

 

 

 

 

 

 

 

Pantex Environmental Air Monitoring Data 

Historical Means; r^2 = 0.895

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3

Th Historical Mean (Bq/m3)

U Historical Mean (Bq/m3) 

U Hist Mean

y=x

Fit
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 18 of 42

Table 4-2. Maximum values of 95% upper confidence intervals of means or net means (BWXT 

Pantex 2001).

Nuclide Location

Historical mean 

or CY 2000

Maximum value of upper 95% 

confidence interval (μBq/m3) Type

H-3 Onsite PA-AR-06 Historical mean 819,663 Mean

Th-232 Fenceline FL-AR-10 CY 2000 2.21 Net mean

U-233/234 + U-238 Fenceline FL-AR-10 Historical mean 4.97 Net mean

Pu-239/240 Fenceline FL-AR-10 Historical mean 0.137 Mean

4.2.2.4 Dose Coefficients

The ICRP has published, and the Integrated Modules for Bioassay Analysis (IMBA) computer 

program calculates, dose coefficients in units of sievert per becquerel. These coefficients are the 

committed equivalent dose (CED)2 HT(τ) in organ or tissue T per unit intake hT(τ), where τ is the 

integration time in years after the intake. The integration time τ is 50 years for the reference worker. 

Dose coefficients depend on radionuclide, intake route (e.g., inhalation or ingestion), particle size 

(e.g., 1 or 5 μm), absorption type (e.g., S, M, F), and the selection of biokinetic models. The 

assumptions most favorable to claimants about dose coefficients are those that result in the highest 

dose per unit intake.

The intake that leads to a dose D or HT for various dose coefficients is:

( ) ( ) ( )

T

T

D H τ I D

dosecoefficient h τ = = (4-6)

The concentration that leads to a dose D or HT for various dose coefficients is:

3 3 3

( ) ( ) ( ) 2,400 m (2,400 m )( ) (2,400 m )( ( ))

T

T

I D D H τ C D

dosecoefficient h τ = = = (4-7)

Substituting 10 μSv for HT in the above equation gives:

3

10 μSv (10 μSv) (2,400 m )( ( )) T

C

h τ = (4-8)

Selecting the greatest value of hT(τ) for the intake from each element (for example, thorium, uranium, 

or plutonium) results in specifying values of particle size, absorption type, and radionuclide for each 

element that give worst-case (i.e., favorable to claimant) results. That is, the lowest concentration of a 

radionuclide that results in 10 μSv CED to an organ or tissue after a year breathing that concentration 

in air.

If the observed C95,net is less than the concentration calculated from the previous equation, 

environmental doses from that radionuclide are negligible and need not be calculated.

If the observed C95,net is greater than the concentration calculated in the previous equation, annual 

equivalent doses should be examined to determine if these, when combined over the individual’s 

exposure history, result in more than 10 μSv to the tissue in any one year.

 2

NIOSH does not use CED in its dose reconstructions for POC calculations. This quantity is introduced here as a simple 

bounding value to establish that airborne concentrations are too small to result in significant annual dose to a tissue or 

organ. If a committed dose value is not exceeded, an annual dose value will never be exceeded.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 19 of 42

4.2.2.5 Criteria for Determining that Maximum Credible Intakes Lead to Doses Less than 

10 Microsievert to Most Highly Dosed Tissue or Organ

Table 4-3 lists dose conversion coefficients and air concentrations leading to 10 μSv CED for 3

H, 

232Th, 234U, and 239Pu, as calculated with IMBA. The table lists the tissues or organs receiving the 

highest HT(τ). These values are from ICRP Publication 71 for 232Th (ICRP 1996). If the 95th 

percentile concentrations are below these values, the resultant doses would be below 10 μSv 

(1 mrem), and there is no need to reconstruct doses due to inhalation of environmental radionuclides. 

The resultant doses from the 95th percentile concentrations are below 1 mrem for all but type M 232Th. 

A discussion on why Pantex 232Th is not type M follows [23].

Table 4-3. Dose conversion coefficients and air concentrations leading to 10 μSv for 3

H, 232Th, 234U, 

and 239Pu (ICRP 1996). 

Nuclide Details

Organ with 

highest HT(τ)

Air concentration breathed 

for 2,000 hours leading to 

10-μSv CED (μBq/m3)

Dose from 

breathing 

95th-percentile 

concentration

(mrem)

Tritium Water vapor Small intestine 185,000,000 0.0044

Th-232 Type M, 1 μm, f1 = 5E-4 Bone surface 1.89 1.17

Th-232 Type S, 1 μm, f1 = 5E-4 Bone surface 14.4 0.15

U-234 Type S, 1 μm, f1 = .002 Lung 59.0 0.084

Pu-239/240 Type M, 1 μm, f1 = 5E-4 Bone surface 2.85 0.048

For type M thorium the largest upper 95% confidence level of net mean air concentration is

2.21 μBq/m3

, which indicates that a CED of 117 μSv (1.17 mrem) to bone surfaces would accumulate 

for each year of exposure. However, for thorium type S, the only plausible environmental form of 

232Th at Pantex, the largest upper 95% confidence level of net mean air concentration is 14.4 μBq/m3

, 

which indicates that a CED of 1.5 μSv (0.15 mrem) to bone surfaces would accumulate for each year 

of exposure. For thorium intakes, CED to the red bone marrow is always far below 10 μSv [24].

Because simultaneous exposure to the observed 95% upper confidence intervals of the means or net 

means of all environmental radionuclides at Pantex never leads to a CED to the most highly dosed 

tissue or organ that equals or exceeds 10 μSv, there is no need to reconstruct doses due to 

environmental exposures to airborne radioactive materials at Pantex.

The quantity of interest is the dose to the tissue or organ during each year, which would have 

contributions from intakes in each previous year. Figure 4-6 shows IMBA equivalent dose to four 

tissues or organs unit intake (Sv/Bq) during each year for 1-μm AMAD type W 232Th inhalation. 

Figure 4-7 shows the annual contribution to equivalent dose to bone surfaces per unit intake for 

inhalation of a 1-μm activity median aerodynamic diameter (AMAD) type M 232Th aerosol. The 

greatest value occurs in year 22 after the intake, and the peak value is 2.41% of the average. 

Figure 4-8 shows the equivalent dose rate to bone surfaces for 10, 20, 30, 40, and 50 years of intakes 

of 1 Bq/yr of the same aerosol. Figure 4-7 is derived from the results in Figure 4-6 by summing 

contributions to annual equivalent dose in a given year over the various years of intake. Figure 4-7

shows that the annual equivalent dose rate peaks at differing intervals (28, 35, 43, 49, and 50 years, 

respectively) after intake begins for different intake durations and for differing intervals (18, 15, 13, 9, 

and 0 years, respectively) after intake ends for the different intake durations.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 20 of 42

Figure 4-6. IMBA equivalent dose to four tissues or organs per unit 

intake (Sv/Bq) during each year for 1-μm AMAD type W 232Th 

inhalation.

The concentration that, if breathed for the duration of a worker’s employment at Pantex, would yield a 

peak annual equivalent dose of 10 μSv to bone surfaces can be deduced from the data in Figure 4-7. 

They are 6.62, 3.36, 2.30, 1.78, and 1.58 μBq/m3

, respectively, for intakes lasting 10, 20, 30, 40, or 50 

years. Therefore, a worker would have to breathe the 95% upper confidence level concentration at 

location FL-AR-10 for 33 years to reach a peak annual dose rate of 10 μSv in a year, and for 34 or 

more years to exceed 10 μSv in a year to bone surfaces. It is noted that lung clearance classification 

W is from the ICRP 30 dosimetric models. Dose coefficients for the ICRP 66 internal dosimetry model 

lung absorption type M 232Th material yield comparable results.

As a further measure of how this calculation tends to overestimate the dose, it is implausible that 

released thorium from Pantex operations could be type M, because thorium was not machined or cut, 

only assembled or disassembled. Therefore, the only plausible means for thorium to become 

airborne would be for oxidation products to become airborne [25]. The dose factor for type S thorium 

is 2.5 × 10-5

/4.5 × 10-5 or 55% of the dose factor for type M thorium. If the thorium is type S, then 

even a 50-year continuous exposure to the maximum credible concentration does not lead to an 

annual equivalent dose to bone surfaces in excess of 10 μSv, as shown above.

For all other organs and tissues, combining maximum credible intakes to all combined radionuclides 

never exceeds 10 μSv in any calendar year, even for 50 years continuous exposure.

Inhalation of 1 um Type W Th-232

1E-7

1E-6

1E-5

1E-4

1E-3

0 10 20 30 40 50

Years Since Intake

Annual Equivalent Dose per Unit Intake (Sv/Bq) 

Bone Surfaces

Lung

Red Bone Marrow

Liver
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 21 of 42

Figure 4-7. IMBA equivalent dose and average equivalent dose to bone 

surfaces per unit intake (Sv/Bq) during each year for 1-μm AMAD type 

W 232Th inhalation.

Figure 4-8. IMBA annual equivalent dose (Sv) to bone surfaces for 10-, 20-, 

30-, 40-, and 50-year inhalation intakes of 1 Bq/yr of 1-μm AMAD type W 

232Th.

4.2.3 Annual Intakes from Resuspension

Soil sampling and analysis were routinely performed at the Pantex Plant (BWXT Pantex 2001). In 

addition, several special surveys were performed, but methods for soil sampling and analysis were 

not standardized throughout the DOE weapons complex until the early 1970s. In 1973, DOE 

dedicated a laboratory to soils analysis and purchased or fabricated the necessary field and 

laboratory equipment.

1 um Type W Th-232 Inhalation

0

0.0001

0.0002

0.0003

0.0004

0 10 20 30 40 50

Year Following Intake

Equivalent Dose to Bone Surfaces p 

Unit Intake during Year (Sv/Bq) 

Annual Sv/Bq

50-year Average (Sv/Bq)

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0 10 20 30 40 50 60 70 80 90 100 110

Time (Years since first intake)

Annual Equivalent Dose (Sv) 

 to Bone Surfaces .

50 y

40 y

30 y

20 y

10 y
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 22 of 42

As stated in Section 4.2.1, concentrations of radionuclides in soil were not used to determine 

resuspension as part of the concentration of radionuclides available for inhalation. This analysis 

assumed that monitored air concentrations included a real-time resuspension fraction. This 

assumption is reasonable because:

• The topography of the site and the region is very flat and dry (BWXT Pantex 2001).

• The meteorology of the site and the region is very consistent and relatively invariable (Snyder 

1993).

• Wind speed and direction are relatively consistent and constant, respectively (see Figure 4-9

and Table 4-4) (BWXT Pantex 2001).

 Figure 4-9. Wind rose for 2000 (BWXT Pantex 2001).
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 23 of 42

Table 4-4. Climatological data for 2000 by month (BWXT Pantex 2001).

Month

Temperature,

°Celsius

(°Fahrenheit) Mean relative 

humidity (%)

Precipitationa,

mm

(in.)

Wind speed,

m/s 

(mph)

Maximum Minimum Mean monthly Mean Maximum

January 22.4 -11.3 3.8 46 3.05 4.8 15.3

(72.3) (11.7) (38.8) (0.12) (10.7) (34.0)

February 25.0 -8.5 7.7 41 0.00 5.6 15.7

(77.0) (16.7) (45.9) (0.00) (12.5) (34.9)

March 26.2 -4.7 8.4 63 105.66 5.8 16.8

(79.2) (23.5) (47.2) (4.16) (12.8) (37.4)

April 32.8 -1.7 13.9 52 7.37 6.2 15.1

(91.0) (28.9) (57.0) (0.29) (13.8) (33.6)

May 38.7 3.8 20.7 46 21.59 6.4 17.0

(101.7) (38.8) (69.3) (0.85) (14.1) (37.8)

June 34.6 11.7 25.3 75 176.02 5.9 17.5

(94.3) (53.1) (70.1) (6.39) (13.2) (38.9)

July 38.3 16.1 26.1 55 0.00 5.3 15.5

(100.9) (61.0) (79.0) (0.00) (11.8) (34.4)

August 36.6 15.9 27.5 38 0.00 5.1 12.3

(97.9) (60.6) (81.5) (0.00) (11.3) (27.3)

September 37.8 -0.1 22.7 38 0.00 5.5 14.1

(100.0) (31.8) (72.9) (0.00) (12.2) (31.3)

October 35.7 -0.1 14.7 71 134.62 5.1 14.2

(96.3) (31.8) (58.5) (5.30) (11.3) (32.7)

November 20.8 -8.5 3.5 71 0.00 4.9 13.4

(69.4) (16.7) (38.3) (0.00) (10.8) (29.7)

December 17.9 -13.6 -0.8 70 0.00 4.6 15.8

(64.2) (7.5) (30.6) (0.00) (10.3) (35.1)

Annualb 14.5 56 443.31 5.4

(57.4) (17.65) (12.1)

a. Includes water equivalent of snowfall.

b. Annual mean of parameter (when indicated) except for precipitation. Total precipitation is indicated. Annual maximum and/or minimum 

temperatures and/or annual maximum wind speed may be obtained by reviewing the data in the appropriate column.

For reconstructing potential unmonitored dose, annual concentrations at all site locations are less 

than the maximums in the calculations in Section 4.2.2 [26]. These concentrations result in negligible 

doses. Therefore, no dose should be assigned resuspension of radionuclides.

4.3 EXTERNAL DOSE

Before 1989, only radiation workers were monitored for radiation exposure. These personnel worked 

primarily in facilities in Zones 4 and 12 [27]. Radiation workers accounted for about half of the 

workers on the site [28]. Therefore, employees working in other areas or zones were not monitored. 

Estimated occupational environmental dose would have to be added for those employees who were 

not monitored.

Pantex workers have received external doses from ambient radiation levels on the site. Ambient 

radiation levels were not reported until 1986 [29].

4.3.1 Ambient Radiation

The environmental radiological profile for the Pantex Plant is for dose reconstruction when personal 

dosimetry or bioassay program participation was not required or was not available. ASERs were 

reviewed for data that would be useful in reconstructing ambient radiation levels. Data in these 

historical documents (see the References section) included ambient TLD radiation measurements. 

An ambient radiation level program was initiated and reported beginning in 1986. Figure 4-10 shows 

the locations of the monitors and TLD dosimeters in 2000 (Laseter 1987).
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 24 of 42

Figure 4-10. Locations of thermoluminescent dosimeters in 2000 (BWXT Pantex 2001). 

FD = fenceline dosimeter; OD = onsite dosimeter; OS = offsite dosimeter; PD = onsite 

dosimeter.

The dosimetry results from the ambient environmental monitoring program for the Pantex facility were 

analyzed to determine whether there was a difference in the dose rates on and off the site.

No environmental dose rates were recorded before 1986 [30]. Before this time, the environmental 

data consisted of radionuclide concentrations in air, water, soil, vegetation, and jackrabbits [31]. 

Therefore, the analysis is most appropriate for 1986 to 2002, but extrapolations to previous years can 

be made.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 25 of 42

The dose rate data the analysis used were from TLD readings except for the offsite dose rates for 

1990. In 1990 there were apparent problems with the TLD system because, for most dosimeter 

locations, there was only one non-zero quarterly value (MHSMC 1991). Because the TLD data 

appeared to be in error, for 1990 only, the offsite dose rate data were obtained from bulb dosimeters 

at the same sampling locations [32].

Figure 4-11 shows the average of the onsite and offsite radiation doses. In 1986, the Chernobyl 

incident released sufficient radioactive materials so that a spike in environmental dose rates was 

observed in locations far removed from the Pantex site (e.g., Oklahoma City and Austin, Texas) (TDH 

1999). The dose rates in Figure 4-11 for 1986 could have been elevated solely due to the Chernobyl 

incident.

Figure 4-11. Ambient dose rates for Pantex Plant (based on continuous occupancy, 

8760 hours per year).

Linear regression, as depicted in Figure 4-11, was performed on the reported dose rates for 1986 

through 2000, and the trend lines for offsite and onsite doses were found to converge. According to 

the trend lines, convergence occurs between 1998 and 2000, depending on which data set is used. 

According to the trend lines, as time goes backward to 1955, the difference in onsite and offsite dose 

rates increases. Of course, this trend cannot go on forever in the past, but this analysis can well 

serve the purpose of estimating ambient doses on the Pantex Plant site that are favorable to 

claimants. The difference in the slopes of the trend lines were used to estimate onsite ambient 

environmental doses back to 1955 (Table 4-5).

Based on the data in Table 4-5 and to be favorable to claimants, it is suggested that onsite ambient 

occupational dose for 1955 through 1974 be added to a person’s dose record at the rate of 30

mrem/yr, and the onsite ambient occupational dose for 1975 through 2000 be added to a person’s 

dose record at the rate of 15 mrem/yr. These values are based on a 2500 hour work year. This 

would result in a maximum ambient dose of about 1,110 mrem for the 50-year period between 1955

and 2000 [33].

Ambient Dose Rates for Pantex Plant

0

20

40

60

80

100

120

140

1985 1990 1995 2000 2005

Year

Dose Rate (mrem/year)

"On-site"

"Off-site"

Linear ("On-site")

Linear ("Off-site")
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 26 of 42

Table 4-5. Calculated difference between onsite 

and offsite annual doses for the Pantex Plant [34]. 

Year

Difference between onsite and offsite 

radiation dose rates (mrem/yr)(adjusted to 

account for a 2500 hour work-year)

1955 28

1960 25

1965 22

1970 19

1975 15

1980 12

1985 9

1990 6

1995 2

2000 1

The Pantex historical personnel external dose monitoring program was reviewed and determined to 

have been properly managed in relation to storage of control badges and accounting for 

environmental exposures [35]. Therefore, doses of record properly include occupational 

environmental doses and no adjustments of recorded doses need be made for monitored workers 

[36].

4.4 UNCERTAINTY

As discussed in the previous sections, estimates of annual intakes were based on air monitoring data 

and their sampling and analytical uncertainties. Where needed, the analysis made conservative (i.e., 

favorable to claimant) assumptions. The estimated annual concentrations based on monitoring data 

precluded the use of calculated meteorological conditions that could introduce large, additional 

uncertainties.

In instances where more detailed information is known about a particular individual or job 

classification, dose reconstruction should account for other modifying factors. For example, if (for a 

particular job classification) there is reason to believe that the actual ventilation rate for the worker 

might vary markedly from the average of 2,400 m3

/yr of exposure, the dose reconstructor should use 

professional judgment to adjust the estimated intakes as necessary, according to whether the 

individual was engaged in light or heavy work. The respiration rate is 1.2 m3

/hr for light work and 

1.7 m3

/hr for heavy work (Shleien 1992). In these cases, dose reconstructors should estimate the 

annual intake by summing the products of the fractional annual period for each job-dependent level of 

work and the corresponding ventilation rate to determine the total ventilation volume for the year in 

cubic meters. The annual intake is the product of the annual ventilation volume and the annual 

average concentration for the location of interest.

Based on TLD measurements of ambient external dose, the annual mean external gross dose (not 

net dose) on the site was 0.910 mSv with a standard deviation of 0.140 mSv. However, additional 

bias and uncertainty has been identified in TLD dosimeters. Biases and uncertainties for typical TLD 

systems have been identified as described by Fix and Stewart (ORAUT 2006).

The factors to be applied to various dosimeters are:

• Based on the distribution of energy levels and geometry judged most likely, recorded dose 

divided by the table's bias value to calculate deep dose.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 27 of 42

• Range of overall bias factors based on alternative distributions of energy levels and geometry.

• Systematic uncertainty resulting from lack of knowledge of actual distributions of energy levels 

and geometry.

• Random uncertainty resulting from variation among workers in energy levels and geometry.

Overall, these biases and uncertainties in external personnel dosimeters could lead to an additional 

factor-of-2 increase in the recorded dose.

For this document, no attempt has been made to quantify other uncertainties.

4.5 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).

Dillard B. Shipler served as the initial Document Owner of this document. Mr. Shipler was previously 

employed at the Pantex site and his work involved management, direction or implementation of 

radiation protection and/or health physics program policies, procedures or practices related 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] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Detailed source terms for the Pantex Plant are classified and were not made available.

[2] Winslow, Robert C. ORAU Team. Senior Health Physicist. April 2007.

DU contains about 99.8% 238U, 0.2% 235U, and 0.001% 234U by mass. Application of the 

specific activities of 1.24 × 10-8 TBq/g for 238U, 8.00 × 10-8 TBq/g for 235U, and 2.31 × 10-4

TBq/g for 234U results in 1.24 × 10-6 TBq for 238U, 1.60 × 10-8 TBq for 235U, and 2.31 × 10-7 TBq 

for 234U and a total activity of 1.49 × 10-6 TBq.

[3] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Pantex internal dosimetry manuals do not address 233U at all.

[4] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Because few devices were disassembled before 1980, releasable uranium oxide was available 

only in old devices and releases of tritium occurred only during disassembly. Airborne 

radioactive materials were not deemed a potential concern until 1980.

[5] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Uranium oxide that was released when old devices were disassembled was known and 

dispersion was controlled within the cells. Only small amounts of tritium were released when 

the container was disconnected from its assembly.

[6] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Tritium reservoirs came as sealed containers and the seal was not broken during insertion.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 28 of 42

[7] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

From review of documents and interviews of personnel (see ORAUT 2004, ORAUT 2007b), 

metal came as formed items, so no activities were performed that would generate oxides.

[8] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

From review of documentation and interview of personnel (see ORAUT 2004, ORAUT 2007b), 

no materials containing metals were burned during this period, so no oxides were formed or 

released.

[9] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Once tritium reservoirs were in place (inserted), valves were opened. When the device was 

disassembled, the valve was closed and the reservoir was removed. A small amount of tritium 

was released from between the reservoir and the device. These amounts are summarized in 

Table 4-1.

[10] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Specific releases of radioactive materials from Pantex facilities are classified and not available. 

Summaries are provided in annual reports except for a few historical incidents.

[11] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

This is based on review of plant documents, interviews with plant personnel, and personal and 

professional judgment.

[12] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Considering time-related production, time-related availability of radioactive materials on the 

site, and the small concentrations of radioactive materials in the air and soil when releases of 

radioactive materials could have occurred after 1980, initial analyses of potential intakes and 

resulting doses led the authors to believe that potential doses from intakes would be 

negligible.

[13] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

The team reviewed a number of “General Radiation Survey Forms for Bays/Cells” related to

surveys of gland nut removals when disassembling tritium reservoirs. Most were 0 μCi, many 

were 10 μCi, and only a few were more than 10 μCi. The statement is a general statement of 

the reviews.

[14] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

The factor was derived based on review of many years of Pantex documentation, professional 

judgment, and favorability to claimants.

[15] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

The factor was derived based on review of Pantex documentation, professional judgment, and 

favorability to claimants.

[16] Shipler, Dillard B. ORAU Team. Principal Health Physicist. August 2006.

Uranium oxide that was released when old devices were disassembled was known and 

dispersion was controlled in the cells.

[17] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

Plutonium pits that were removed during disassembly are still sealed and, therefore, no 

releases of plutonium occur.
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[18] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

This is the form of thorium that was monitored when monitoring did occur for thorium.

[19] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

“Negligible doses” will not contribute to doses deemed necessary to produce cancers.

[20] Winslow, Robert C. ORAU Team. Senior Health Physicist. March 2007.

A distribution of the environmental air samples taken outside the facility would represent the 

entire facility. While working at a facility, workers, in general, will move around and therefore 

receive exposures to different concentrations. However, a worker might spend a longer period 

in higher concentrations; the distribution would be diluted by the lower concentration areas. 

Therefore, the 95% confidence of the mean is assumed to be bounding to account for a 

worker spending the majority of the time in the higher concentration.

[21] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

This equation is a mathematical expression of the statement preceding the equation and 

referenced above.

[22] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The Pantex Plant monitored concentrations of radionuclides in air at the site boundary and at 

selected offsite locations (outside the site boundary). However, concentrations of 

radionuclides were not monitored regularly at locations within the site boundary. Areas within 

the site boundary (outside facilities) were monitored on an as-needed basis depending on the 

activities.

[23] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The argument is presented in case the form of 232Th can be shown to be type M. The 

possibility is remote but the subject is covered.

[24] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The argument is presented to clarify the situation that involves bone surface cancer versus red 

bone marrow cancer where 232Th might be thought to be a contributor.

[25] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The statement means that pure thorium metal particulates could not be released to the air. 

Only particulates of thorium oxide could be released.

[26] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The authors compared the maximum concentrations at various locations, which were all less 

than the concentrations used to demonstrate negligible doses in Section 4.2.2.

[27] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The history of radiation monitoring of external dose to workers is covered in ORAUT-TKBS0013-6 (ORAUT 2007c), particularly in Table 6-15 and Figure 6-1.

[28] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The history of radiation monitoring of external dose to workers is covered in ORAUT-TKBS0013-6 (ORAUT 2007c), particularly in Table 6-15 and Figure 6-1.

[29] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

After reviewing annual environmental reports and their predecessor documents and talking 

with Plant personnel, it is evident that radioactive materials were sampled in environmental 

media but direct radiation was not monitored at all locations.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 30 of 42

[30] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

After reviewing annual environmental reports and their predecessor documents and talking 

with Plant personnel, it is evident that radioactive materials were sampled in environmental 

media but direct radiation was not monitored at all locations.

[31] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

After reviewing annual environmental reports and their predecessor documents and talking 

with Plant personnel, it is evident that radioactive materials were sampled in environmental 

media but direct radiation was not monitored at all locations.

[32] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

According to Pantex personnel and early site environmental and external monitoring data, bulb 

dosimeters were used before other dosimeters but were kept in the system as backup as new 

dosimetry was implemented.

[33] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The evaluation was based on the data in the spreadsheet and professional judgment in 

defining the factor and rounding it to a number that is favorable to the claimant and easy for 

the dose reconstructor to use.

[34] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The calculations were performed in a spreadsheet and the results of interest were included in 

the table and the figure to demonstrate the point.

[35] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

All Pantex external dosimetry program documents, including BWXT Pantex (2002a), were 

reviewed along with implementation reports and databases, and long-time employees were 

interviewed, as indicated in the several memoranda to file. The evidence seemed to justify the 

statements of credibility and reliance on the result of the programs as they grew and matured.

[36] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

All Pantex external dosimetry program documents, including BWXT Pantex (2002a), were 

reviewed along with implementation reports and databases, and long-time employees were 

interviewed, as indicated in the several memoranda to file. The evidence seemed to justify the 

statements of credibility and reliance on the result of the programs as they grew and matured.

[37] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

Section 4.2.2.5 discusses the potential for a small cumulative dose to bone surface because of 

dose factors and solubility factor selection.

[38] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

Because the lines converge noticeably to modern times and because the doses are relatively 

small, judgment concludes that single conservative values that are favorable to the claimant 

would be adequate rather than the imposition of a function for year-by-year doses.

[39] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

From the graph, the lines might be interpreted to converge in 2002. However, for 

conservatism and favorability to claimants, the convergence is not considered an end point

and the proposed doses should be applied to current years.

[40] Shipler, Dillard B. ORAU Team. Principal Health Physicist. September 2006.

The storage of control badges in places where environmental doses as well as work-related 

doses do not exist means that differences between badges worn by workers and control 
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 31 of 42

badges account for all exposures. Note in the paragraph above that unmonitored workers 

must have dose added to their total.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 32 of 42

REFERENCES

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Alexander, R. E., 1975, Environmental Monitoring Report for Pantex Plant Covering 1974, MHSMP75-8, Mason & Hanger-Silas Mason Company, Pantex Plant, Amarillo, Texas, May 1. [SRDB 

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Alexander, R. E., 1976, Environmental Monitoring Report for Pantex Plant Covering 1975, Mason & 

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Pantex Plant, DOE/AL/65030-9506, Amarillo, Texas, June. [SRDB Ref ID: 13709]
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BMI (Battelle Memorial Institute), 1985, Summary of the Annual Site Environmental Reports 

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Northwest Laboratory, Richland, Washington, March. [SRDB Ref ID: 11122]

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December 1987, Pacific Northwest Laboratory, Richland, Washington, February. [SRDB Ref 

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BWXT Pantex, 2001, 2000 Site Environmental Report for Pantex Plant, DOE/AL/65030-9904, Pantex 

Plant, Amarillo, Texas, May. [SRDB Ref ID: 8636]

BWXT Pantex, 2002a, 2001 Site Environmental Report for Pantex Plant, DOE/AL/66620-2002, 

Pantex Plant, Amarillo, Texas, December. [SRDB Ref ID: 13082]

BWXT Pantex, 2002b, Pantex Plant Technical Basis Manual for External Dosimetry, MNL-00051, 

Issue 4, Pantex Plant, Amarillo, Texas, January 3. [SRDB Ref ID: 11068]

BWXT Pantex, 2003, 2002 Site Environmental Report for Pantex Plant, DOE/AL/66620-2003, Pantex 

Plant, Amarillo, Texas, August. [SRDB Ref ID: 13080]

BWXT Pantex, 2004, Final Pantex Plant Radiological Investigation Report, AL-PX-SW-003788, 

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DHHS (U.S. Department of Health and Human Services), DHHS Designation of Additional Members 

of the Special Exposure Cohort under the Energy Employees Occupational Illness 

Compensation Program Act of 2000, Designating a Class of Employees from Pantex Plant, 

Amarillo, Texas, U.S. Department of Health and Human Services, Office of the Secretary, 

Washington, D.C., December 21, 2011. [SRDB Ref ID: 116796]

DHHS (U.S. Department of Health and Human Services), DHHS Designation of Additional Members 

of the Special Exposure Cohort under the Energy Employees Occupational Illness 

Compensation Program Act of 2000, Designating a Class of Employees from the Pantex Plant, 

Amarillo, Texas, U.S. Department of Health and Human Services, Office of the Secretary, 

Washington, D.C., September 30, 2013. [SRDB Ref ID: 128051]

DOE (U.S. Department of Energy), 1982, Summary of Annual Environmental Reports for CY 1981, 

Department of Energy Nuclear Sites, DOE/EP-0038/1, Office of Environment, Safety and 

Health, Washington, D.C., December.

DOE (U.S. Department of Energy), 1984, A Summary of Annual Site Environmental Reports, January 

through December 1983, DOE/EP-0049/1, Washington, D.C., January.
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DOE (U.S. Department of Energy), 1992, Summary of Radionuclide Air Emissions from Department of 

Energy Facilities for CY 1991, DOE/EH-0293T, Assistant Secretary for Environment, Safety 

and Health, Washington, D.C., December. [SRDB Ref ID: 13360]

DOE (U.S. Department of Energy), 1994, Summary of Radionuclide Air Emissions from Department of 

Energy Facilities for CY 1992, DOE/EH-0360, Assistant Secretary for Environment, Safety and 

Health, Washington, D.C., February. [SRDB Ref ID: 13361]

DOE (U.S. Department of Energy), 1996, 1995 Environmental Report for Pantex Plant, 

DOE/AL/65030-9602, Albuquerque Operations Office, Albuquerque, New Mexico, May. 

[SRDB Ref ID: 1291]

DOE (U.S. Department of Energy), 1997, 1996 Environmental Report for Pantex Plant, 

DOE/AL/65030-9704, Albuquerque Operations Office, Albuquerque, New Mexico, June. 

[SRDB Ref ID: 8621]

DOE (U.S. Department of Energy), 1999, 1998 Site Environmental Report, DOE/AL/65030-9904, 

Albuquerque Operations Office, Albuquerque, New Mexico. [SRDB Ref ID: 8622]

DOE (U.S. Department of Energy), 2000, 1999 Site Environmental Report for Pantex Plant, 

DOE/AL65030-9904, Albuquerque Operations Office, Albuquerque, New Mexico, May. [SRDB 

Ref ID: 8625]

DOE (U.S. Department of Energy), 2001a, Restricted Data Declassification Decisions, 1946 to the 

Present, RDD-7, Office of Declassification, Washington, D.C., January 1. [SRDB Ref ID: 

26132]

DOE (U.S. Department of Energy), 2001b, Guide of Good Practices for Occupational Radiological 

Protection in Uranium Facilities, DOE-STD-1136-2000, Change Notice No. 3, Washington, 

D.C., December. [SRDB Ref ID: 4617]

Griffis, D., 2004, “Re: FW: We need a Pantex Reviewer,” e-mail to ORAU Team, BWXT Pantex, 

Pantex Plant, Amarillo, Texas, February 2. [SRDB Ref ID: 13083]

ICRP (International Commission on Radiological Protection), 1996, Age-dependent Doses to 

Members of the Public from Intake of Radionuclides: Part 4 Inhalation Dose Coefficients, 

Publication 71, Pergamon Press, Oxford, England. [SRDB Ref ID: 22729]

Laseter, W. A., 1982, Environmental Monitoring Report for Pantex Plant Covering 1981, Mason & 

Hanger-Silas Mason Company, Pantex Plant, Amarillo, Texas. [SRDB Ref ID: 13716]

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1988, Mason & Hanger-Silas Mason Company, Pantex Plant, Amarillo, Texas, May. [SRDB 

Ref ID: 13436]

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Release at the FS-23 Interim Total Containment Test Fire Facility Occurring on January 10, 

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to file, Oak Ridge, Tennessee, May 27. [SRDB Ref ID: 14542]

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GLOSSARY

annual dose equivalent 

Dose equivalent received in a year in units of rem or sievert.

becquerel (Bq)

International System unit of radioactivity equal to 1 disintegration per second; 1 curie equals 

37 billion (3.7 × 1010) Bq.

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.

committed effective dose equivalent (CEDE)

Sum of the effective dose equivalents to various tissues or organs in the body each multiplied 

by the appropriate tissue weighting factor and committed for a 50-year period following an 

acute intake or the onset of chronic intake. It does not include contributions from external 

dose.

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 (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.

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.

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.
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 38 of 42

effective dose equivalent (EDE)

Average of the dose equivalents weighted for the susceptibility of harm to different tissues or 

organs in units of rem or sievert.

exposure

(1) In general, the act of being exposed to ionizing radiation. See acute exposure and chronic 

exposure. (2) Measure of the ionization produced by X- and gamma-ray photons in air in units 

of roentgens.

gamma ray

Electromagnetic radiation (photons) originating in atomic nuclei and accompanying many 

nuclear reactions (e.g., fission, radioactive decay, and neutron capture). Physically, gamma 

rays are identical to X-rays but have higher energy; the only essential difference is that X-rays 

do not originate in the nucleus.

gray

International System unit of absorbed radiation dose, which is the amount of energy from any 

type of ionizing radiation deposited in any medium; 1 gray equals 1 joule per kilogram or 

100 rads.

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, 

high-speed electrons, high-speed protons, photoelectrons, Compton electrons, 

positron/negatron pairs from photon radiation, and scattered nuclei from fast neutrons.

radiation

Subatomic particles and electromagnetic rays (photons) with kinetic energy that interact with 

matter through various mechanisms that involve energy transfer. See ionizing radiation.

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.

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 
Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 39 of 42

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-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 40 of 42

TABLE OF CONTENTS

SECTION TITLE PAGE

A.1 Radionuclide Intake................................................................................................................ 40

A.2 External Exposure.................................................................................................................. 40

A.3 Onsite Ambient Dose Assignment.......................................................................................... 41

LIST OF TABLES

TABLE TITLE PAGE

A-1 References for maximum air concentrations for tritium (oxidized), thorium, uranium, 

and plutonium used in Section 4.2.2 dose analyses............................................................... 41

A-2 Upwind “control” (location OA-AR-13) average annual air concentrations .............................. 41

A-3 Maximizing onsite ambient doses........................................................................................... 41

A-4 Best-estimate onsite ambient doses....................................................................................... 42

A.1 RADIONUCLIDE INTAKE

Based on the information in Section 4.2.2 of this Technical Basis Document, all potential doses from 

occupational environmental intakes on the Pantex Plant are considered negligible and should be 

assigned zero dose. Some attention might be paid to claims based on bone surface cancers relative 

to the time the worker spent at the Pantex Plant [37]. As stated in Section 4.2.2, the committed dose 

from 232

Th conservatively might be 117 μSv (1.17 mrem). In addition, for individuals who were 

employed at the Pantex Plant in 1989 and 1990, an acute dose of 0.015 rem applied as <15-keV 

electrons should be assigned for 1989 and a chronic dose of 0.001 rem applied as <15-keV electrons 

should be assigned for 1990 based on Section 4.2.1.1.

A.2 EXTERNAL EXPOSURE

Ambient external doses on the Pantex site have been monitored by TLDs since 1986. Based on trend 

analysis of onsite and offsite TLD measurements, as described in Section 4.3.1, the extrapolated 

difference in offsite and onsite doses in 1955 could be as much as 100 mrem/yr for continuous 

occupancy on the site (8,760 hr/yr) [38]. The trend lines converge in about 2000 [39]. Therefore, to 

account for the dose that a worker would receive in a 50-hour work week (2,600 hr/yr), it is 

recommended that 30 mrem/yr be added to unmonitored workers for 1955 through 1974 and 

15 mrem/yr be added to unmonitored workers for 1975 through the present. 

The Pantex historical personnel external dose monitoring program was reviewed and determined to 

have been properly managed in regard to storage of control badges and accounting for environmental 

exposures (BWXT Pantex 2002). It is concluded that doses of record properly include occupational 

environmental doses and no adjustments of recorded doses need be made for monitored workers 

[40].

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Document No. ORAUT-TKBS-0013-4 Revision No. 02 Effective Date: 01/03/2014 Page 41 of 42

Tables A-1 and A-2 provide supporting data for the analyses described in this TBD.

Table A-1. References for maximum air concentrations for 

tritium (oxidized), thorium, uranium, and plutonium used in 

Section 4.2.2 dose analyses (BWXT Pantex 2001).

Radionuclides Tables in DOE (2001a)

Tritium (oxidized) Table 5.1, page 5-8, location PA-AR-06

Thorium-232 Table 5.3, page 5-11, location FL-AR-05

Uranium-234/234 & 238 Table 5.4, page 5-12, location FL-AR-05

Table 5.5, page 5-14, location FL-AR-05

Plutonium 239/240 Table 5.7, page 5-18, location FL-AR-08

Table A-2. Upwind “control” (location OA-AR-13) average annual air 

concentrations.

Isotopes/elements

Number of 

samples

Concentration (μBq/m3)

(mean ±standard deviation)

Previous 

3-yr mean

Tritium oxide - - -

Uranium 12 2.32 ±1.08 1.26

Plutonium - - -

Thorium 12 2.17 ±1.37 1.85

A.3 ONSITE AMBIENT DOSE ASSIGNMENT

For cases in which doses can be overestimated, onsite ambient doses should be assigned based on 

Table A-3 using a constant distribution.

Table A-3. Maximizing onsite ambient doses

Year Onsite ambient dose (rem)

1955–1974 0.030

1975–2015 0.015

For cases in which the dose cannot be overestimated, onsite ambient doses should be assigned 

based on Table A-4 using a normal distribution with the specified values for Parameters 1 and 2. 

Note that the primary mission at Pantex from 1952 through 1954 was to precision-machine HE 

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

(ORAUT, 2007b). Therefore, no on-site ambient doses are assigned for the years of 1951 through 

1954. 

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Table A-4. Best-estimate onsite ambient doses (rem).

Year Parameter 1 Parameter 2 Year Parameter 1 Parameter 2

1955 0.0280 0.0170 1985 0.0091 0.0055

1956 0.0273 0.0166 1986 0.0084 0.0051

1957 0.0267 0.0162 1987 0.0078 0.0047

1958 0.0261 0.0158 1988 0.0072 0.0044

1959 0.0254 0.0155 1989 0.0065 0.0040

1960 0.0248 0.0151 1990 0.0059 0.0036

1961 0.0242 0.0147 1991 0.0053 0.0032

1962 0.0235 0.0143 1992 0.0047 0.0028

1963 0.0229 0.0139 1993 0.0040 0.0024

1964 0.0223 0.0136 1994 0.0034 0.0021

1965 0.0217 0.0132 1995 0.0028 0.0017

1966 0.0210 0.0128 1996 0.0021 0.0013

1967 0.0204 0.0124 1997 0.0015 0.0009

1968 0.0198 0.0120 1998 0.0010 0.0005

1969 0.0191 0.0116 1999 0.0010 0.0001

1970 0.0185 0.0113 2000 0.0010 0.0001

1971 0.0179 0.0109 2001 0.0010 0.0001

1972 0.0172 0.0105 2002 0.0010 0.0001

1973 0.0166 0.0101 2003 0.0010 0.0001

1974 0.0160 0.0097 2004 0.0010 0.0001

1975 0.0154 0.0093 2005 0.0010 0.0001

1976 0.0147 0.0090 2006 0.0010 0.0001

1977 0.0141 0.0086 2007 0.0010 0.0001

1978 0.0135 0.0082 2008 0.0010 0.0001

1979 0.0128 0.0078 2009 0.0010 0.0001

1980 0.0122 0.0074 2010 0.0010 0.0001

1981 0.0116 0.0070 2011 0.0010 0.0001

1982 0.0109 0.0067 2012 0.0010 0.0001

1983 0.0103 0.0063 2013 0.0010 0.0001

1984 0.0097 0.0059

2014

forward 0.0010 0.0001

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