ORAU Team

NIOSH Dose Reconstruction Project

Technical Basis Document for the Pantex Plant

– Occupational Environmental Dose

Document Number:

ORAUT-TKBS-0013-4 

Effective Date: 08/24/2004

Revision No.: 00

Controlled Copy No.: ________

Page 1 of 36

Subject Experts: Dillard B. Shipler and Daniel J. Strom

Document Owner

Approval: Signature on File Date: 08/18/2004

Dillard B. Shipler, TBD Team Leader

Approval: Signature on File Date: 08/19/2004

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File Date: 08/19/2004

Richard E. Toohey, Project Director

Approval: Signature on File Date: 08/24/2004

James W. Neton, OCAS Health Science Administrator

Supersedes:

None

TABLE OF CONTENTS

Section

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

Page

3

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

4.1 Introduction................................................................................................................................6

4.2 Internal Dose from OnSite Atmospheric Radionuclide Concentrations....................................... 6

4.2.1 Onsite Releases to Air.........................................................................................................6

4.2.1.1 Tritium .....................................................................................................................12

4.2.1.2 Uranium...................................................................................................................13

4.2.1.3 Plutonium ................................................................................................................ 13

4.2.1.4 Thorium ...................................................................................................................13

4.2.2 Rationale for Showing that Organ Doses Due to Intakes of 

Environmental Levels of Radionuclides at Pantex Are Negligible....................................... 13

4.2.2.1 Negligible Individual Dose Level .............................................................................. 13

4.2.2.2 Evidence that Onsite Airborne Uranium and Thorium Levels Are 

Mostly of Natural Origin ........................................................................................... 14

4.2.2.3 Upper 95 % Confidence of the Mean Net Concentration.......................................... 15

4.2.2.4 Dose Coefficients .................................................................................................... 16

4.2.2.5 Criteria for Determining that Maximum Credible Intakes Lead to 

Doses Less than 10 μSv to Most Highly Dosed Tissue or Organ............................. 16

4.2.3 Annual Intakes from Resuspension ................................................................................... 19

4.3 External Dose..........................................................................................................................21

4.3.1 Ambient Radiation ............................................................................................................. 21

4.4 Uncertainty ..............................................................................................................................24
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References ........................................................................................................................................25

Glossary ............................................................................................................................................30

Attachment A Radionuclide Intake and Occupational Exposure.................................................. 34

4A.1 Radionuclide Intake.................................................................................................................34

4A.2 External Exposure ...................................................................................................................34

LIST OF TABLES

Table

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

Page

9

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

means ................................................................................................................................. 15

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

for 3

H, 232Th, 234U, and 239Pu................................................................................................ 16

4-5 Climatological data for 2000 by month ................................................................................ 20

4A-1 References for maximum air concentrations for tritium (oxidized), 

thorium, uranium, and plutonium used in Section 4.2.2 dose analyses................................ 34

4A-2 Upwind “control” (location OA-AR-13) average annual air concentrations ........................... 36

LIST OF FIGURES

Figure

4-1 Pantex Plant site

Page

8

4-2 Isotopic contributions to offsite dose from Pantex operations in 2000.................................... 9

4-3 Air monitoring stations in 2000 ............................................................................................ 10

4-4 Employment history............................................................................................................. 11

4-5 Pantex 238U and thorium mean environmental air monitoring data for 

2000 at seven locations....................................................................................................... 14

4-6 Pantex 238 U and thorium mean environmental air monitoring data 

(historic) at seven locations................................................................................................. 14

4-7 IMBA equivalent dose to four tissues or organs per unit intake (Sv/Bq) 

during each year for 1-μm AMAD Type W 232Th inhalation.................................................. 18

4-8 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.............................................................................................................................19

4-9 MBA annual equivalent dose (Sv) to bone surfaces for 10, 20, 30, 40, 

and 50-year inhalation intakes of 1 Bq per year of 1 μm Type W 232Th................................ 19

4-11 Locations of thermoluminescent dosimeters in 2000 ........................................................... 23
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RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 11/17/2003 00-A New technical basis document for for the Pantex 

Plant– Occupational Environmental Dose. 

Initiated by Jerome B. Martin.

Draft 02/09/2004 00-B Incorporates internal review and NIOSH 

comments. Initiated by Jerome B. Martin.

Draft 06/18/2004 00-C Incorporates additional internal review and NIOSH 

comments. Initiated by Dillard B. Shipler.

Draft 07/12/2004 00-D Incorporates an additional NIOSH review 

comment. Initiated by Dillard B. Shipler.

Draft 07/20/2004 00-E Incorporates an additional NIOSH review 

comment. Initiated by Dillard B. Shipler.

Draft 07/28/2004 00-F Incorporates an additional internal review 

comment. Initiated by Dillard B. Shipler.

08/24/2004 08/24/2004 00 First approved issue. Initiated by Dillard B. 

Shipler.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 4 of 36

ACRONYMS AND ABBREVIATIONS

AMAD activity median aerodynamic diameter

ASER Annual Site Environmental Report

Bq Becquerel

Ci curie

CDC Centers for Disease Control and Prevention

CEDE committed effective dose equivalent

CY calendar year

DOE U.S. Department of Energy

DU depleted uranium

EH environment, safety, and health (DOE)

EDE effective dose equivalent

EPA U.S. Environmental Protection Agency

FD fenceline dosimeter

FL fenceline

FS firing site

GM Geiger-Mueller

h hour

3

H tritium

HE high explosive

ICRP International Commission on Radiological Protection

IMBA Integrated Modules for Bioassay Analysis (program)

m meter

mrem millirem

mL milliliter

mph miles per hour

NCRP National Council on Radiation Protection and Measurements

OCAS Office of Compensation and Support

OD onsite dosimeter

OS off-site

PD onsite dosimeter

RBM red blood marrow

rem unit of radiation dose

Sv sievert

TBD to be determined

TLD thermoluminescent dosimeter
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 5 of 36

y year

μ micro, 10-6
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 6 of 36

4.1 INTRODUCTION

Technical Basis Documents (TBDs) and Site Profile Documents (SPDs) are general working 

documents that provide guidance concerning the preparation of dose reconstructions at particular 

sites or categories of sites. They will be revised in the event additional relevant information is 

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

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

dose reconstruction.

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

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

employer facility” or a “Department of Energy facility” as defined in the Energy Employee 

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

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 present at the Pantex Plant include tritium, uranium, plutonium, and 

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

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

whole body. The following sections discuss radionuclides present at Pantex. 

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 (EPA)-approved CAP88-PC computer model to evaluate the 

radiological dose that a member of the public could receive during the year. Figure 4-2 shows the 

percent contributions to dose that resulted (DOE 2001a). 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 

release 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.

4.2.1

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

1952 through 2000 was obtained from several sources, including Environmental Monitoring Reports 

(EMRs), Annual Site Environmental Reports (ASERs)(DOE/AL 1993, 1994, 1995, 1996, 1997, 1998, 

1999, 2001, 2002)(DOE 2001a)(MHSMC 1973, 1974, 1975, 1976, 1977, 1978, 1979,1980, 1981, 

1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992), annual summaries of 

Onsite Releases to Air
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 7 of 36

radiological doses and releases reported to DOE (DOE 1982, 1984, 1992, 1994)(PNL 1985, 1988, 

1990, 1990a, 1993, 1997, 1997a), radiation safety department incident records (Mason 1986), and 

radiation safety department technical basis manuals (Pantex 2002). Table 4-1 summarizes releases 

to the atmosphere from plant vents. EMRs and ASERs contain air release and soil monitoring data, 

and thermoluminescent dosimeter (TLD) monitoring data from on and off the site. 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 234

U, 235U, and 236U, all of which are alpha 

particle emitters with long half-lives. A very small amount of 235U does not contribute to dose. 

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. Though small quantities of 232Th were 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 8 of 36

Figure 4-1. Pantex Plant Site. 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 9 of 36

Figure 4-2. Isotopic contributions to offsite dose from Pantex operations in 2000 (DOE 2001a). 

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

Summaries-see reference list). 

Year Tritium Total uranium Total plutonium a All others

1981 9.5E-02 1.0E-05 -- --

1983 5.0E-02 1.0E-05 -- --

1984 1.2E-04 -- -- --

1985 -- 1.0E-05 -- --

1986 1.3E-01 1.0E-05 -- --

1987 9.6E-02 -- -- --

1988 1.2E-01 -- -- --

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

1990 2.55E+03 --

1991 1.7E-01 -- -- --

1992 1.3E-01 -- -- 3.5E-07

1993 3.0E-01 -- -- --

1994 4.46E-01 -- -- --

1995 1.0E-01 -- -- --

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

1997 1.17E-01 1.32E-04 1.27E-09 232Th

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

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

2000 2.71E+00 6.73E-07 -- 2.76E-07 232Th, 3.28E-06

a. = no releases.

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” 

(DOE 2001a). Total employment on the site is shown in Figure 4-4. Many employees in early years 

were not badged indicating the need for assessing missed or unmonitored dose.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 10 of 36

Figure 4-3. Air monitoring stations in 2000 (DOE 2001a)
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Figure 4-4. Employment history. 

It was assumed that monitoring data, particularly air monitoring data would be appropriate for dose 

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

would 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 was time-related, as follows:

From 1958 to 1979, the primary operation at Pantex was weapons assembly. Some component 

testing was performed. A small number of weapons were disassembled for testing and quality 

control. 

Radioactive materials began arriving at Pantex 1951. (Martin 2004) 

− In 1951, DU began arriving as new, bare metal forms.

− In 1956, tritium began arriving in sealed containers.

− In 1958, plutonium began arriving in sealed metal forms (Mitchell 2001). 

− Thorium began arriving at the plant as new, bare metal forms in the1960s. (Martin 2003a)

• From 1952-1958, the only operation at Pantex was weapons assembly.

− No tritium containers were manipulated, so no tritium was released.

− No metal oxides formed or burned, so no metal oxides were released. 

− No testing involving radioactive material was performed.

− Small amounts of tritium were released when weapons were disassembled.

− There are no specific data to substantiate specific releases of tritium prior to 1972. 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 12 of 36

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

components.

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

− Starting in 1958, all assembly and disassembly operations were on complete sealed-pit 

weapons (Mitchell 2001).

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

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

of weapons.

• Though 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 238Pu was never on the Pantex Plant (Griffis

2004).

It is evident from this information that operations that could lead to releases of radioactive materials 

did not start until about 1980. 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. This selection 

was based on the maturity of the monitoring program, the technical level of analytical techniques, and 

the application of quality programs. In other words, these are the best available data.

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. 

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. 

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. 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. The estimated maximum individual onsite dose in the downwind direction, NNE, was about 

10 times the fenceline dose. Therefore, use a 15-mrem dose to the whole body for a worker in the 

area during that period.

At the beginning of 1990, an estimated 2,550 Ci of tritium residual remained trapped in the walls and 

gravel overburden of the cell in which the 1989 release occurred. The analysis conservatively 

assumed that this entire amount was released to the atmosphere during 1990. The estimated 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 13 of 36

maximum individual onsite dose in the downwind direction (NNE) was 1.0 mrem. Use this value for a 

worker in the area during that period.

4.2.1.2 Uranium

Uranium arrives at Pantex as a metal (DU, primarily 238U), uncoated and unsealed. 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. One of type of part is HE that generally is destroyed by burning. During 

the burning, associated powdered uranium is released to the atmosphere. 

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

Isotopes measured to be present include 233/234U and 238U. For dose reconstruction, assume that 234U,

the isotope that results in the maximum organ dose, is present at 100%. This assumption would 

result in a small, but claimant-favorable, overestimation of the actual dose.

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

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

resulted in the release of particulate material containing depleted uranium. All personnel in the area 

were upwind (NE at that time) of the release point. The release lasted a short time (1 to 2 minutes). 

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.

4.2.1.3 Plutonium

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

) and 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 (DOE 2001a). Even when aged weapons are 

dismantled for inspection or refurbishment, plutonium is not available in a form for release.

4.2.1.4 Thorium

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

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

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) clearance Type S (ICRP 1995).

4.2.2

4.2.2.1 Negligible Individual Dose Level

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

Radionuclides at Pantex Are Negligible

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 airborne concentrations of radionuclides measured in the Pantex environment are 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 14 of 36

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

expended to assess them.

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

Origin

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

while 3

H and plutonium do not occur in significant quantities in nature. 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 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 are strongly correlated 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 released by 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 4-5 and 4-6, respectively. 

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

Figure 4-5. Pantex 238U and thorium mean 

environmental air monitoring data for 2000 at 

seven locations. 

Figure 4-6. Pantex 238 U and thorium mean 

environmental air monitoring data (historic) at 

seven locations. 

A further argument that all or virtually all of the uranium on 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 maximum credible concentrations to which workers could have been exposed in a year are equal

to the upper 95% confidence of the mean net concentration: 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 15 of 36

,95. .. net mzx cred = CC (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 maximum credible intake is 

thus

,2 400 ,95. 3

.. net Imzx cred = ×Cm (2) 

4.2.2.3 Upper 95 % Confidence of the Mean Net Concentration

Environmental data for Pantex referenced in Attachment 4A, Table 4A-1, was used to calculate the 

values in Equation (1). The standard error of a value is related to the standard deviation by the 

reciprocal of the square root of the number of measurements:

. . .( ) . .( )

n

DS C CES = (3) 

The upper 95% confidence level of the mean 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 

95 CC .1 645 ×+= . .(CES ). (4) 

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

measurements was made of each) is

( .1) 645 .{ .( )} .{ .( )} .

( .1) 645 . .( )

2 2

95,

background background

net background background

CC CESCES

CCC CCES

−= ×+ +

−= −×+

(5) 

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

needed, are listed in Table 4A-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 2000 and for historical means. For the latter, it was necessary to estimate the standard 

error of the mean 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. 

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

Nuclide Location

Historical mean 

or CY 2000

Maximum value of 

upper 95% confidence 

interval (μBq/m3) Type 3

H-3 Onsite PA-AR-06 Historical mean 819,663 Mean 232Th-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
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4.2.2.4 Dose Coefficients

The ICRP has published, and the Integrated Modules for Bioassay Analysis (IMBA) OCAS-Edition 

computer program (OCAS 2003) calculates, “dose coefficients” in units of Sv/Bq. These coefficients 

are the committed equivalent dose1

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

, HT(τ), in organ or tissue T per unit intake hT(τ), where τ is the 

integration time in years following 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), transportability class (e.g., S, M, F), as well as the selection of biokinetic 

models. The most claimant-favorable assumptions about dose coefficients are those that result in the 

highest dose per unit intake. 

.

)(

)( )(

τ

τ

T

T

h

H

dose coefficient

D DI = = (6) 

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

. ))()(400,2(

)(

)(400,2(400,2 )

)( )( 3 3 3 τ

τ

T

T

hm

H

dosem coefficient

D

m

DI DC = = = (7) 

Substituting 10 μSv for HT in the above equation gives

. ))()(400,2(

10 )10( 3 τ

μ μ hm TSv SvC = (8) 

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

intakes results in specifying values of particle size, transportability class, and radionuclide for each 

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

radionuclide that results in 10 μSv committed equivalent dose to an organ or tissue following a year’s 

breathing of that concentration in air.

If the observed Cnet,95 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 Cnet,95 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.

4.2.2.5 Criteria for Determining that Maximum Credible Intakes Lead to Doses Less than 10 

μSv to Most Highly Dosed Tissue or Organ

Table 4-3. Dose conversion coefficients and air concentrations leading to 10 μSv for 3H, 232Th, 234U, 

and 239Pu. 

 

1

The National Institute for Occupational Safety and Health (NIOSH) does not use committed equivalent dose in its dose 

reconstructions for probability of causation 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.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 17 of 36

Nuclide Details

Organ with 

highest 

HT(τ)

Air concentration 

breathed for 2,000 

hours leading to 10-

μSv committed 

equivalent dose 

(μBq/m3)

Dose from breathing 

95%ile 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

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

H, 232Th, 234U, 

and 239Pu, lists the air concentrations that would lead to 10 μSv committed equivalent dose, as 

calculated with IMBA (OCAS 2003). The table lists the tissues or organs receiving the highest HT(τ). 

These values are from ICRP Publication 71 for 232Th (ICRP 1995). If the 95%ile concentrations are 

below these values, the resulting doses would be below 10 Sv (1 mrem), and there is no need to 

reconstruct doses due to inhalation of environmental radionuclides. The resultant doses from the 

95%ile concentrations are below 1 mrem for all but 232Th Type M. A discussion on why Pantex 232Th

is not Type M, follows.

For thorium Type M (the largest upper 95% confidence level of net mean air concentration = 2.21

μBq/m3

), indicating that a committed equivalent dose 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 = 14.4 

μBq/m3

), indicating that a committed equivalent dose of 1.5 μSv (0.15 mrem) to bone surfaces would 

accumulate for each year of exposure. For thorium intakes, committed equivalent dose to the red 

bone marrow is always far below 10 μSv.

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 committed equivalent dose 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 prior year. Figure 4-8 shows the annual contribution to equivalent 

dose to bone surfaces per unit intake for inhalation of a 1-μm AMAD Type M 232Th aerosol. The 

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

Figure 4-9 shows the equivalent dose rate to bone surfaces for 10, 20, 30, 40, and 50 years of intakes 

of 1 Bq per year of the same aerosol. Figure 4-8 is derived from the results shown in Figure 4-7 by 

summing contributions to annual equivalent dose in a given year over the various years of intake. 

Figure 4-8 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 differing intervals (18, 15, 

13, 9, and 0 years, respectively) after intake ends for the different intake durations. 

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 shown in 

Figure 4-8. 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. Thus, 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.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 18 of 36

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

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

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

would be for oxidation products to become airborne. The dose factor for Type S thorium is 

2.5 × 10-5/4.5 × 10-5 = 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 radionuclides combined 

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

Figure 4-7. IMBA (OCAS 2003) equivalent dose to four tissues or 

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

Type W 232Th inhalation. 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 19 of 36

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)

Figure 4-8. IMBA (OCAS 2003) 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. 

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

Figure 4-9. IMBA (OCAS 2003) annual equivalent dose (Sv) to bone surfaces 

for 10, 20, 30, 40, and 50-year inhalation intakes of 1 Bq per year of 1 μm 

Type W 232Th. 

4.2.3

Soil sampling and analysis were routinely performed at the Pantex Plant (DOE 2001a). 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. 

Annual Intakes from Resuspension
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 20 of 36

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 air monitored 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.

• 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 4-10

and Table 4-5).

For reconstructing potential missed or unmonitored dose, annual concentrations at all site locations 

are less than the maximums considered in the calculations of Section 4.2.2. These concentrations 

Table 4-5. Climatological data for 2000 by month (DOE 2001a). 

Month

Temperature °C (°F) Mean relative 

humidity (%)

Precipitation

a millimeters 

(inches)

Wind speed 

meters per second 

(miles per hour)

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. 

result in negligible doses. Therefore, no dose should be assigned to missed or unmonitored dose 

from resuspension of radionuclides.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 21 of 36

4.3 EXTERNAL DOSE

Before 1989, radiation workers were the only employees monitored for radiation exposure. These 

personnel worked primarily in facilities in Zones 4 and 12. Radiation workers accounted for about half 

of the workers on the site. 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 are subjected to external doses from ambient radiation levels on the site. Ambient 

radiation levels were not reported until 1986. 

4.3.1

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 reference section for citations by year) included ambient TLD radiation 

measurements. An ambient radiation level program was initiated and reported beginning in 1986. 

Figure 4-11 shows the locations of the monitors and TLD dosimeters in 2000.

Ambient Radiation

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 the plant site and off site.

No environmental dose rates were recorded for the years prior to 1986. Prior to this time, the 

environmental data consisted of radionuclide concentrations in air, water, soil, vegetation, and 

jackrabbits. Thus, the analysis is most appropriate for the years 1986 to 2002 but extrapolations to 

prior years can be made.

The dose rate data used for the analysis was 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. Because the TLD data appeared to be in 

error, for 1990 only, the offsite dose rate data were obtained from bulb dosimeters located at the 

same sampling locations.

Figure 4-12 shows the average of the on-site and off site 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 TX). The 

dose rates shown in Figure 4-12 for 1986 may have been elevated solely due to the Chernobyl 

incident. 

Linear regression was performed on the dose rates 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 1950, 

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, claimant friendly wise, ambient 

missed dose on the Pantex Plant Site. The difference in the slopes of the trend lines were used to 

estimate onsite ambient environmental doses back to 1950. See table 4-6.

Based on the data in Table 4-6 and to be claimant favorable, it is suggested that unmonitored or 

missed onsite ambient occupational dose for the years from 1951 through 1974 be added to a 

persons dose record at the rate of 100 mrem/year, and the unmonitored or missed onsite ambient 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 22 of 36

occupational dose for the years from 1975 through 2000 be added to a persons dose record at the 

rate of 50 mrem/year. This would result in a maximum unmonitored or missed ambient dose of about 

3750 mrem for the 50 year period. 

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")

Figure 4-12 Ambient Dose Rates for Pantex Plant

Table 4-6 Calculated difference between onsite and offsite annual doses for the Pantex plant.

Year

Difference between onsite and offsite radiation 

dose rates (mrem/year)

1950 110

1955 98

1960 87

1965 76

1970 65

1975 53

1980 42

1985 31

1990 20

1995 8

2000 2 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 23 of 36

Figure 4-11. Locations of thermoluminescent dosimeters in 2000 (DOE 2001a).

a. Locations co-sampled with Texas Department of Health-Bureau of Radiation Control

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. It is concluded that doses of record properly 

include occupational environmental doses and no adjustments of recorded doses need be 

made for monitored workers.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 24 of 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., 

claimant-favorable) 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. In these cases, to estimate annual intake, sum 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 measurements, Table 4-9, 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. These biases and 

uncertainties have been identified and listed in Table 5-10 of MED/AEC//DOE External Dosimetry 

Technology Technical Basis Document (Fix et al. 2003). 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.

• 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. 
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 25 of 36

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DOE/AL, 1994, Environmental Report for Pantex Plant Covering 1994, Department of 

Energy/Albuquerque Operations Office P.O. Box 30020, Amarillo, TX, June, 1995.

DOE/AL, 1995, Environmental Report for Pantex Plant Covering 1995, Department of 

Energy/Albuquerque Operations Office P.O. Box 30020, Amarillo, TX, June, 1996.

DOE/AL, 1996, Environmental Report for Pantex Plant Covering 1996, Department of 

Energy/Albuquerque Operations Office P.O. Box 30020, Amarillo, TX, June, 1997.

DOE/AL, 1997, Environmental Report for Pantex Plant Covering 1997, Department of 

Energy/Albuquerque Operations Office P.O. Box 30020, Amarillo, TX, December, 1998

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Energy/Albuquerque Operations Office P.O. Box 30020, Amarillo, TX, June, 1999.

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Energy/Albuquerque Operations Office P.O. Box 30020, Amarillo, TX, June, 2000.

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DOE/AL, 2002, Site Environmental Report for Pantex Plant Covering 2002, Department of 

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MHSMC, 1975, Environmental Monitoring Report for Pantex Plant Covering 1975, Mason & HangerSilas Mason Co., Inc. P.O. Box 647, Amarillo, TX, May, 1976.

MHSMC, 1976, Environmental Monitoring Report for Pantex Plant Covering 1976, Mason & HangerSilas Mason Co., Inc. P.O. Box 647, Amarillo, TX, May, 1977.

MHSMC, 1977, Environmental Monitoring Report for Pantex Plant Covering 1977, Mason & HangerSilas Mason Co., Inc. P.O. Box 647, Amarillo, TX, May, 1978.

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MHSMC, 1980, Environmental Monitoring Report for Pantex Plant Covering 1980, Mason & HangerSilas Mason Co., Inc. P.O. Box 647, Amarillo, TX, May, 1981. 

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MHSMC, 1985, Environmental Monitoring Report for Pantex Plant Covering 1985, Mason & HangerSilas Mason Co., Inc. P.O. Box 647, Amarillo, TX, May, 1986. 

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june 2003
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 30 of 36

GLOSSARY

annual dose equivalent 

Dose equivalent received in a year, expressed in units of rem (sievert).

Atomic Energy Commission 

Original agency established for nuclear weapons and power production; a predecessor to the 

U.S. Department of Energy.

becquerel

SI unit of radioactivity equal to one transformation per second.

beta (β) dose

Designation (i.e., beta) on some Pantex external dose records referring to the dose from lessenergetic beta, X-ray, and/or gamma radiation.

beta radiation

Radiation consisting of charged particles of very small mass (i.e., the electron) emitted 

spontaneously from the nuclei of certain radioactive elements. Physically, the beta particle is 

identical to an electron moving at high velocity.

committed dose equivalent (HT,50) 

Dose equivalent to organs or tissues received from an intake of radioactive material by an 

individual during the 50-year period following the intake.

committed effective dose equivalent (HE,50) 

Sum of the products of the weighting factors applicable to each organ or tissue that are 

irradiated and the committed dose equivalent. 

curie

A special unit of activity. One curie (1 Ci) exactly equals 3.7 x 1010 nuclear transitions per 

second.

deep absorbed dose (Dd) 

Absorbed dose at the depth of 1.0 cm in a material of specified geometry and composition.

deep dose equivalent (Hd) 

Dose equivalent at the respective depth of 1.0 cm in tissue.

depleted uranium (DU)

Used as components in nuclear weapons; isotopic activity fractions (NOTE: this is not the 

mass fraction) listed by Pantex as:

Isotope

234U

Activity fraction

0.0840

235U 0.0145

238U 0.9015

detection limit (lower)

Minimum quantifiable exposure or neutron flux that can be detected.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 31 of 36

depleted uranium analysis

Indicates that the chemical properties of uranium were used for analysis, not necessarily that 

the material in question was depleted uranium

dose equivalent (H)

Product of the absorbed dose (D), the quality factor (Q), and any other modifying factors. The 

special unit is the rem. When D is expressed in Gy, H is in sieverts (Sv). (1Sv = 100 rem).

dose of record

Dose files provided by DOE to NIOSH as part of the individual worker files. 

dosimeter

Device used to measure the quantity of radiation received. A holder with radiation-absorbing 

elements (filters) and an insert with radiation-sensitive elements packaged to provide a record 

of absorbed dose or dose equivalent received by an individual. (See film dosimeter, neutron 

film dosimeter, thermoluminescent dosimeter).

dosimetry

Science of assessing absorbed dose, dose equivalent, effective dose equivalent, etc., from 

external and/or internal sources of radiation. 

dosimetry system

System used to assess dose equivalent from external radiation to the whole body, skin, and/or 

extremities. This includes the fabrication, assignment, and processing of dosimeters as well 

as interpretation and documentation of the results.

effective dose equivalent

Sum of the products of dose equivalent to the organ or tissue (HT) and the weighting factor 

(WT) applicable to each organ or tissue.

exchange period (frequency)

Period (weekly, biweekly, monthly, quarterly, etc.) for routine exchange of dosimeters.

exposure

In the technical sense, a measure expressed in roentgens (R) of the ionization produced by 

photons (gamma and X-rays) in air. 

extremity

That portion of the arm extending from and including the elbow through the fingertips, and that 

portion of the leg extending from and including the knee and patella through the tips of the 

toes.

film

In general, a "film packet" that contains one or more pieces of film in a light-tight wrapping. 

The film when developed has an image caused by radiation that can be measured using an 

optical densitometer. (See nuclear track emulsion).

film dosimeter

Small packet of film within a holder that attaches to a wearer.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 32 of 36

flux (n/cm2-sec)

Measure of the intensity of neutron radiation in neutrons/cm2-sec. It is the number of neutrons 

passing through a sphere with a cross-sectional area of 1 cm2 of a given target in 1 second. 

Expressed as nv, where n = the number of neutrons per cubic centimeter and v = their velocity 

in cm/sec. In this sense, flux is the same as “fluence rate” as defined by the International 

Commission on Radiation Units and Measurements.

gamma ray (γ)

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

SI unit of absorbed dose. Unit symbol, Gy. 1 Gy = 100 rad.

ionizing radiation

Electromagnetic or particulate radiation capable of producing charged particles through 

interactions with matter.

neutron

Basic particle that is electrically neutral weighing nearly the same as the hydrogen atom.

neutron, fast

Neutron with energy equal or greater than 10 keV.

neutron, intermediate

Neutron with energy between 0.5 eV and 10 keV.

neutron, thermal

Strictly, neutrons in thermal equilibrium with surroundings; in general, neutrons with energy 

less than about 0.5 eV.

neutron film dosimeter

Film dosimeter that contains an Neutron Track Emulsion, type A, film packet.

nuclear track emulsion, type A (NTA)

Film that is sensitive to fast neutrons. The developed image has tracks caused by neutrons 

that can be seen by using an appropriate imaging capability such as oil immersion and a 

1000X power microscope or a projection capability.

personal dose equivalent Hp(d)

Dose equivalent in soft tissue below a specified point on the body at an appropriate depth d. 

The depths selected for personnel dosimetry are 0.07 mm and 10 mm for the skin and body, 

respectively. These are noted as Hp(0.07) and Hp(10), respectively. 

photon

Unit or "particle" of electromagnetic radiation consisting of X- and/or gamma rays. 
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photon - x-ray

Electromagnetic radiation of energies between 10 keV and 100 keV whose source can be an 

X-ray machine or radioisotope.

quality factor, Q

Modifying factor used to derive dose equivalent from absorbed dose.

radiation

Alpha, beta, neutron, and photon radiation. 

radioactivity

Spontaneous emission of radiation, generally alpha or beta particles, gamma rays, and 

neutrons from unstable nuclei.

rem

Unit of dose equivalent, which is equal to the product of the number of rad absorbed and the 

"quality factor."

roentgen (R)

Unit of exposure to gamma (or X-ray) radiation. It is defined precisely as the quantity of 

gamma (or X-) rays that will produce a total charge of 2.58 x 10-4 coulomb in 1 kg of dry air. 

An exposure of 1 R is approximately equivalent to an absorbed dose of 1 rad in soft tissue for 

higher (>100 keV) energy photons.

shallow absorbed dose (Ds) 

Absorbed dose at a depth of 0.007 cm in a material of specified geometry and composition.

shallow dose equivalent (Hs) 

Dose equivalent at a depth of 0.007 cm in tissue.

shielding

Material or obstruction that absorbs (or attenuates) radiation and thus tends to protect 

personnel or materials from radiation. 

skin dose

Absorbed dose at a tissue depth of 7 mg/cm2

. 

thermoluminescent

Property of a material that causes it to emit light as a result of being excited by heat.

thermoluminescent dosimeter (TLD)

Holder containing solid chips of material that when heated will release the stored energy as 

light. The measurement of this light provides a measurement of absorbed dose. 

whole-body dose

Absorbed dose at a tissue depth of 1.0 cm (1,000 mg/cm2

); also used to refer to the recorded 

dose.

X-ray

Ionizing electromagnetic radiation that originates external to the nucleus of an atom.
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 34 of 36

ATTACHMENT 4A

RADIONUCLIDE INTAKE AND OCCUPATIONAL EXPOSURE

TABLE OF CONTENTS

Section

4A.1 Radionuclide Intake.............................................................................................................

Page

34

4A.2 External Exposure............................................................................................................... 34

LIST OF TABLES

Table

4A-1 References for maximum air concentrations for tritium (oxidized), 

thorium, uranium, and plutonium used in Section 4.2.2 dose analyses................................

Page

34

4A-2 Upwind “control” (location OA-AR-13) average annual air concentrations ........................... 36

4A.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. As stated in Section 4.2.2, the committed dose from 

232Th conservatively might be 117 μSv (1.17 mrem).

4A.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 1951 could be as much as 100 mrem/year. The trend lines 

converge in about 2000. So it is recommended that 100 mrem/year be added to unmonitored workers 

for the years 1951 through 1975 and 50 mrem/year be added to unmonitored workers for the years 

1975 through 2000. This would result in a maximum unmonitored or missed ambient dose of about 

3750 mrem for the 50 year period. 

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. It is concluded that doses of record properly 

include occupational environmental doses and no adjustments of recorded doses need be 

made for monitored workers.

The following tables provide supporting data for the analyses described in the TBD:

Table 4A-1. References for maximum air concentrations for 

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

Section 4.2.2 dose analyses (DOE 2001a) 

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
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 35 of 36

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
Effective Date: 08/24/2004 Revision No.: 00 Document No. ORAUT-TKBS-0013-4 Page 36 of 36

Table 4A-2. Upwind “control” (location OA-AR-13) average annual air 

concentrations. 

Isotopes/elements

Number of 

samples

Concentration (μBq m−3) 

(mean ±standard deviation)

Previous 

3 y mean

Tritium oxide - - -

Uranium 12 2.32 ± 1.08 1.26

Plutonium - - -

Thorium 12 2.17 ± 1.37 1.85