Page 1 of 24

DOE Review Release 11/16/2016

Pantex External Coworker Model

ORAUT-OTIB-0086 Rev. 01

Effective Date: 11/04/2016

Supersedes: Revision 00

Subject Expert(s): Matthew H. Smith, Thomas R. LaBone, and Nancy Chalmers

Document Owner 

Approval:

Mark Fishburn Signature on File for

Matthew H. Smith

Matthew H. Smith, Document Owner

Approval Date: 10/26/2016

Concurrence: Signature on File

John M. Byrne, Objective 1 Manager

Concurrence Date: 11/03/2016

Concurrence: Signature on File

Edward F. Maher, Objective 3 Manager

Concurrence Date: 11/03/2016

Concurrence: Signature on File

Kate Kimpan, Project Director

Concurrence Date: 10/27/2016

Approval: Signature on File

James W. Neton, Associate Director for Science

Approval Date: 11/04/2016

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

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION. 

New Total Rewrite Revision Page Change
Document No. ORAUT-OTIB-0086 Revision No. 01 Effective Date: 11/04/2016 Page 2 of 24

 

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION 

NUMBER DESCRIPTION

08/07/2015 00 Converted white paper to technical information bulletin. Incorporates 

formal internal and NIOSH review comments. Training required: As 

determined by the Objective Manager. Initiated by Matthew H. 

Smith.

11/04/2016 01 Revision initiated to update document and instructions (Section 5.1, 

Table 7-2, and Attachment A) to reflect that the use of nuclear track 

emulsion, Type A film for personnel neutron dosimetry ceased at the 

end of 1973. Incorporates formal internal review comments and 

updated coworker data in Tables 7-1, 7-2, and 7-3 based on updated 

instructions in Attachment A. Incorporates formal NIOSH review 

comments regarding data in Tables 7-1, 7-2, and 7-3 for the era 

1960-1962. Tables 7-1 through 7-3 have been updated and 

footnoted. In addition, explanatory language was added to Section 

5.0. Constitutes a total rewrite of the document. Training required: 

As determined by the Objective Manager. Initiated by Matthew H. 

Smith. 
Document No. ORAUT-OTIB-0086 Revision No. 01 Effective Date: 11/04/2016 Page 3 of 24

 

TABLE OF CONTENTS

SECTION TITLE PAGE

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

1.0 Introduction .............................................................................................................................. 5

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

1.2 Scope........................................................................................................................... 5

2.0 Background.............................................................................................................................. 6

3.0 General Approach.................................................................................................................... 6

4.0 Applications and Limitations..................................................................................................... 7

5.0 Coworker Data Development ................................................................................................... 7

5.1 NTA Era, 1960 to 1973................................................................................................. 7

5.2 Pre-Stanford Era 1974 to 1979..................................................................................... 7

5.3 STANFORD ERA 1980 to 1993.................................................................................... 7

5.4 Recent Era, 1994 to 2010............................................................................................. 8

6.0 Statistical Analysis ................................................................................................................... 8

7.0 Coworker Annual Dose Summaries ......................................................................................... 8

8.0 Attributions and Annotations .................................................................................................... 9

References ........................................................................................................................................ 13

ATTACHMENT A EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 TO 

2010) ..............................................................................................................16

ATTACHMENT B NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED 

WORKERS ..................................................................................................... 20

LIST OF TABLES

TABLE TITLE PAGE

7-1 Annual external photon doses................................................................................................ 10

7-2 Annual external neutron doses............................................................................................... 11

7-3 Annual external skin doses .................................................................................................... 12

A-1 Sources of dose information................................................................................................... 19

LIST OF FIGURES

FIGURE TITLE PAGE

B-1 Latent image fading of neutron film plotted as a function of time ............................................ 23
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ACRONYMS AND ABBREVIATIONS 

AEC U.S. Atomic Energy Commission

AP anterior-posterior

cm centimeter

DOE U.S. Department of Energy

DOELAP DOE Laboratory Accreditation Program

GM geometric mean

GSD geometric standard deviation

ICRP International Commission on Radiation Protection

in. inches

LOD limit of detection

keV kiloelectron-volt, 1,000 electron-volts

MCNP Monte Carlo n-particle

MDL minimum detectable level

MeV megaelectron-volt, 1 million electron-volts

MRD minimum recordable dose

mrem millirem

NIOSH National Institute for Occupational Safety and Health

NTA nuclear track emulsion, Type A

ORAU Oak Ridge Associated Universities

RDX Research Department Formula X

SC&A S. Cohen & Associates

SRDB Ref ID Site Research Database Reference Identification (number)

SSN Social Security Number

TBD technical basis document

TIB technical information bulletin

TLD thermoluminescent dosimeter

U.S.C. United States Code

WB whole body

β beta particle

λ gamma ray

§ section or sections
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1.0 INTRODUCTION

Technical information bulletins (TIBs) 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). TIBs may be used to assist NIOSH staff in the completion of 

individual dose reconstructions.

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 of 2000 [42 U.S.C. § 7384l(5) and (12)].

1.1 PURPOSE

This TIB provides information that allows dose reconstructors to base external doses on known site 

coworker data for Pantex Plant workers who have no or limited monitoring data. In addition, the data 

in this TIB should be used to assign dose for gaps in the dosimetry record. Please note that if the 

unmonitored period is short and the EE was monitored before and after the gap with no apparent 

change in work assignments, the gap may be filled with the average of the surrounding measurements 

(see OCAS-IG-001). 

In cases where the monitoring records list a recorded “0,” that entry is assumed to mean that the 

dosimeter was issued and processed, and that no exposure or dose was detected in excess of the 

dosimeter limit of detection (LOD). In cases in which the records show that the worker was monitored 

for occupational external exposures and one or more dosimeter exchange cycles are blank (or listed 

as a dash, slash, or hash mark), then the absence of an entry is assumed to indicate that the worker:

1. Was not issued a dosimeter in that exchange cycle, or

2. That a dosimeter might have been issued but was not processed due to loss or damage, or

3. That the results of processing were incomplete or suspect and no dose was assigned because 

of the absence of processing or an errant result.

In such cases for years before 1988, NIOSH intends to apply (after consideration of the worker’s job 

title and the totality of the monitoring record), either (1) unmonitored dose based on external coworker 

data, (2) missed dose, or (3) ambient dose. In 1988 and later years, all personnel who entered the 

operational areas of the plant were required to wear a dosimeter as a condition for entry. The absence 

of a listed result, or the presence of a dash, slash, or hash mark for a given dosimeter exchange cycle 

in 1988 and later years, should be interpreted to mean that the worker was not monitored because he 

or she was not present in the operational areas. Therefore, ambient dose should be assigned for 

those exchange cycles.

1.2 SCOPE

Attributions and annotations, indicated by bracketed callouts and used to identify the source, 

justification, or clarification of the associated information, are presented in Section 8.0.
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2.0 BACKGROUND

The Oak Ridge Associated Universities (ORAU) Team has prepared a series of coworker data studies 

to permit dose reconstructors to complete certain cases for which external or internal monitoring data 

are unavailable or incomplete. Cases that do not have complete monitoring data could fall into one of 

several categories:

• The worker was unmonitored and, even by today’s standards, did not need to be monitored 

(e.g., a nonradiological worker).

• The worker was unmonitored but, by today’s standards, would have been monitored.

• The worker might have been monitored, but the data are not available to the dose 

reconstructor.

• Partial information is available, but it is insufficient to facilitate a dose reconstruction.

As described in ORAUT-OTIB-0020, Use of Coworker Dosimetry Data for External Dose Assignment, 

some cases without complete monitoring data can be processed based on assumptions and 

methodologies that do not involve coworker data (ORAUT 2011). For example, many cases in the first 

category can be processed by the assignment of ambient external and internal doses based on 

information in the relevant site technical basis documents (TBDs).

Pantex used a variety of film and thermoluminescent dosimeter (TLD) dosimetry systems, as 

described in the latest revision of ORAUT-TKBS-0013-6, Pantex Plant – Occupational External Dose

(ORAUT 2015a). In this TIB, see Attachment A, External Dose Coworker Study Instructions (1960 to 

2010), for a description of these systems.

3.0 GENERAL APPROACH

External dose is measured with a dosimeter that indicates the dose that is received by an individual 

over a given length of time (e.g., a month or quarter). Multiple measurements over a year are summed 

to give the annual dose for the individual. Dosimeter readings below a given censoring level are 

reported as less than that level (usually referred to as the LOD). For example, the dose for a given 

month might be reported as <0.050 rem. These censored data are problematic for the development of 

coworker models. The previous approach to handling censored dosimeter readings (ORAUT 2011) 

was to substitute one-half of the censoring level for the censored results and then calculate the 

empirical 50th and 95th percentiles of the dataset. In statistics, this substitution is referred to as an 

imputation. In general, the imputation of a constant value like LOD/2 is not recommended (Helsel 

2012) because it biases parameter estimates high. ORAUT-RPRT-0071, External Dose Coworker 

Methodology (ORAUT 2015b), outlines an alternative approach to analyzing the censored data that:

• Uses a lognormal probability model to generate a distribution of values to use for imputation 

rather than a constant one-half of the censoring level,

• Uses survival analysis techniques like those currently used for internal dose coworker modeling 

to estimate the parameters of a lognormal fit [i.e., the geometric mean (GM) and geometric 

standard deviation (GSD)] to the data rather than using the empirical 50th and 95th percentile, 

and

• Uses multiple imputation to account for the uncertainty introduced into the parameter estimates 

by the imputation process.
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4.0 APPLICATIONS AND LIMITATIONS

Some Pantex workers could have worked at one or more other major sites in the DOE complex during 

their employment histories. Therefore, the data in this TIB must be used with caution to ensure that, 

for likely noncompensable cases, unmonitored external doses from multiple site employments have 

been overestimated. This typically requires the availability of the recorded doses or TBDs or TIBs that 

cover external coworker dosimetry data for all relevant sites. In situations where a best estimate of 

dose is needed, the appropriate distributions for factors such as dose conversion factors, geometric 

correction factors, and other applicable factors as defined by TBDs or TIBs should be applied.

The data in this document address penetrating gamma radiation, nonpenetrating dose, and neutron 

dose.

External onsite ambient dose should be applied as specified in the latest revision of ORAUT-PROC0060, Occupational Onsite Ambient Dose Reconstruction for DOE Sites (ORAUT 2006). 

5.0 COWORKER DATA DEVELOPMENT

Information for coworker analysis was found in two data sources provided by Pantex Plant staff (BWXT 

Pantex 2011, 2013). The former contains unadjusted Pantex dosimetry data for the period 1960 to 

2010, and the latter contains Pantex dosimetry data that were adjusted using an improved algorithm 

for the Panasonic 802 dosimetry system that was first introduced in 1980.

Only a small portion of the worker population (approximately 60 out of 220) were monitored each year 

during the era 1960-1962. It is likely that this small population represented workers who had the 

highest potential for exposure. Due to the statistically small number of data points, and the likelihood 

of a biased population, the data for 1963 were used as a surrogate for the era 1960-1962. The 

monitored population in 1963 is larger and numerically similar to the data in subsequent years. 

Therefore, the 1963 data are a better representation of the entire exposed worker population for the 

years in the earlier era - which is more appropriate to meet the coworker modeling needs outlined in 

Section 2.0. 

In relation to neutron dosimetry data, the following sections outline four general eras that were 

considered during the analysis. 

5.1 NTA ERA, 1960 TO 1973

During most of this period (1960 to 1973), nuclear track emulsion, type A (NTA) film was used for 

neutron dosimetry. To address NTA film energy threshold under-response, angular dependence, and 

fading, a correction factor of 2.9 was applied to neutron data from BWXT Pantex (2011) (see 

Attachment B, NTA Film Issues and Dose Assignments for Monitored and Unmonitored Workers). No 

adjustments to photon or skin dose were needed.

5.2 PRE-STANFORD ERA 1974 TO 1979

Information from Landauer indicated that the use of NTA film for personnel neutron dosimetry ceased 

at the end of 1973 (NIOSH 2016). Therefore, for the period 1974 - 1979, dosimetry data for neutrons, 

photons, and skin from BWXT Pantex (2011) were used with no corrections or adjustments.

5.3 STANFORD ERA 1980 TO 1993

Starting in 1980, Pantex monitored personnel for external photon and neutron doses with the fourelement Panasonic 802 TLD dosimeter. In late 1992, the algorithm Pantex used to calculate doses 
Document No. ORAUT-OTIB-0086 Revision No. 01 Effective Date: 11/04/2016 Page 8 of 24

 

was changed to resolve performance issues encountered during the 1989 Department of Energy 

Laboratory Accreditation Program (DOELAP) performance testing. This algorithm, called the “Stanford 

Algorithm,” was used to successfully pass DOELAP performance testing during 1993. The data that 

were recalculated using the Stanford Algorithm are contained in BWXT Pantex (2013). They are used 

in conjunction with the data in BWXT Pantex (2011) for the analyses during this period in this 

document. Specifically, due to data deficiencies noted by Pantex personnel (TLD data could only be 

recalculated for persons for whom the actual TLD element readings were available), the following data 

were discarded from each workbook (Prather 2015):

• Data that were present in BWXT Pantex (2011), but not present in BWXT Pantex (2013), and 

likewise,

• Data that were present in BWXT Pantex (2013), but not present in BWXT Pantex (2011).

In addition, for a given year and month for an individual, the highest whole-body (WB) skin dose, WB 

gamma dose, and WB neutron dose values were used, respectively, when comparing data (filtered as 

described above) in BWXT Pantex (2011, 2013). Finally, it should be noted that the neutron results 

using this improved algorithm are likely biased high because an unmoderated 252Cf source was used 

for calibration rather than a moderated 252Cf source that would have been more similar to Pantex 

workplace neutron spectra (Prather 2004).

5.4 RECENT ERA, 1994 TO 2010

In 1993, Pantex switched to the Panasonic 809/812 dosimetry system. This system passed DOELAP 

accreditation tests at that time, and no adjustments to dose are needed for the data in BWXT Pantex 

(2011) for this period.

See Attachment A for additional information and assumptions about the development of these 

coworker datasets.

6.0 STATISTICAL ANALYSIS

The data from BWXT Pantex (2011, 2013) were analyzed in accordance with the instructions in 

Attachment A and ORAUT-RPRT-0071 (ORAUT 2015b). The imputation model plots, fit with 

lognormal regression on order statistics, are included in ORAUT (2015c). Censored monthly badge 

readings were imputed from these lognormal imputation distributions, monthly doses were summed to 

compute annual doses, and yearly lognormal fits were made. After multiple imputations (K = 30), the 

parameters were averaged, resulting in the plots in ORAUT (2015d).

7.0 COWORKER ANNUAL DOSE SUMMARIES

The results of the analysis method described above are shown in Tables 7-1 to 7-3 for photon, 

neutron, and skin (nonpenetrating) dose, respectively. The tables also include the 95th percentile of 

the specified lognormal distribution and the number of workers in each year (N). These data should be 

used in the same manner as described in ORAUT-OTIB-0020 in relation to using either the GM (50th 

percentile) or the 95th-percentile value as a constant depending on the energy employee’s work 

history (ORAUT 2011). These doses should be assigned with energy ranges – and any applicable 

correction factors – as described in ORAUT-TKBS-0013-6, Pantex Plant – Occupational External Dose

(ORAUT 2015b). Note that there were an insufficient number of monitored workers for neutron and 

skin dose in the early years, so doses from 1960 to 1963 were combined to form multiyear coworker 

models.
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8.0 ATTRIBUTIONS AND ANNOTATIONS

All information requiring identification was addressed via references integrated into the reference 

section of this document.
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Table 7-1. Annual external photon doses (rem).

Year GM GSD 95th percentile N

1960a 0.010 7.95 0.302 217

1961a 0.010 7.95 0.302 217

1962a 0.010 7.95 0.302 217

1963 0.010 7.95 0.302 217

1964 0.101 4.05 1.007 253

1965 0.029 5.27 0.440 416

1966 0.042 4.21 0.442 581

1967 0.045 4.33 0.505 562

1968 0.035 3.41 0.264 423

1969 0.032 3.82 0.293 432

1970 0.065 4.20 0.688 467

1971 0.057 4.92 0.778 495

1972 0.055 4.09 0.557 467

1973 0.124 2.44 0.539 441

1974 0.067 3.48 0.519 500

1975 0.037 3.24 0.255 493

1976 0.044 2.79 0.241 463

1977 0.080 2.15 0.281 465

1978 0.032 3.99 0.316 518

1979 0.086 2.85 0.481 714

1980 0.012 5.71 0.204 772

1981 0.066 4.86 0.889 908

1982 0.039 4.09 0.397 1,002

1983b 0.042 4.03 0.419 Not applicable

1984 0.046 3.97 0.441 1,093

1985 0.039 4.10 0.395 1,172

1986 0.036 3.13 0.235 1,128

1987 0.023 2.80 0.123 1,160

1988 0.028 2.57 0.130 1,121

1989 0.020 3.10 0.127 1,437

1990 0.021 2.56 0.100 2,090

1991 0.023 2.35 0.095 2,126

1992 0.028 2.56 0.130 2,316

1993 0.009 3.36 0.064 2,633

1994 0.008 3.16 0.050 2,978

1995 0.008 3.08 0.048 3,107

1996 0.007 3.14 0.048 3,162

1997 0.006 2.91 0.037 3,000

1998 0.007 2.95 0.040 2,786

1999 0.007 2.90 0.041 2,686

2000 0.007 2.90 0.038 2,642

2001 0.007 2.85 0.037 2,770

2002 0.007 2.95 0.039 2,947

2003 0.007 2.75 0.035 2,996

2004 0.006 2.72 0.033 3,168

2005 0.003 2.94 0.018 3,210

2006 0.003 3.02 0.018 3,237

2007 0.003 3.35 0.019 3,183

2008 0.003 3.94 0.027 2,159

2009 0.003 3.84 0.029 2,110

2010 0.002 3.98 0.024 2,067

a. Values from 1963 are used as surrogate data for 1960 to 1962 based on the discussion in Section 5.0 Coworker Data 

Development. 

b. Per the instructions in Attachment A, the data for 1983 have been interpolated between the 1982 and 1984 values.
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Table 7-2. Annual external neutron doses (rem).

Year GM GSD 95th percentile N

1960a 0.007 12.30 0.482 209

1961a 0.007 12.30 0.482 209

1962a 0.007 12.30 0.482 209

1963 0.007 12.30 0.482 209

1964 0.043 5.21 0.645 249

1965 0.015 4.27 0.168 415

1966 0.022 3.13 0.147 581

1967 0.020 2.55 0.094 563

1968 0.021 2.27 0.080 423

1969 0.003 7.06 0.084 66

1970 0.017 2.49 0.075 465

1971 0.019 2.23 0.071 494

1972 0.021 2.13 0.072 464

1973 0.022 2.51 0.101 59

1974 0.019 3.71 0.164 29

1975 0.213 2.60 1.028 54

1976 0.001 12.88 0.042 463

1977 0.001 14.04 0.052 465

1978 0.001 14.27 0.052 518

1979 0.005 7.68 0.146 714

1980 0.003 5.71 0.058 772

1981 0.023 3.46 0.180 908

1982 0.024 3.39 0.180 1,002

1983b 0.022 3.39 0.165 Not applicable

1984 0.020 3.39 0.150 1,093

1985 0.025 4.00 0.240 1,172

1986 0.027 3.47 0.213 1,128

1987 0.019 2.81 0.103 1,160

1988 0.019 2.72 0.101 1,121

1989 0.016 3.11 0.102 1,437

1990 0.017 2.71 0.089 2,090

1991 0.019 2.49 0.084 2,126

1992 0.007 5.08 0.100 2,316

1993 0.004 2.98 0.024 2,633

1994 0.004 2.99 0.026 2,978

1995 0.004 2.98 0.027 3,107

1996 0.004 2.99 0.026 3,162

1997 0.004 2.85 0.021 3,000

1998 0.004 2.73 0.020 2,786

1999 0.004 2.65 0.020 2,686

2000 0.004 2.74 0.020 2,642

2001 0.004 2.73 0.020 2,770

2002 0.004 2.77 0.020 2,947

2003 0.004 2.62 0.019 2,996

2004 0.004 2.65 0.018 3,168

2005 0.004 2.59 0.018 3,210

2006 0.004 2.63 0.018 3,237

2007 0.003 2.85 0.018 3,183

2008 0.004 2.96 0.021 2,159

2009 0.004 2.76 0.019 2,110

2010 0.003 3.06 0.018 2,067

a. Values from 1963 are used as surrogate data for 1960 to 1962 based on the discussion in 

Section 5.0 Coworker Data Development

b. Per the instructions in Attachment A, the data for 1983 have been interpolated between the 

1982 and 1984 values.
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Table 7-3. Annual external skin doses (rem).

Year GM GSD 95th percentile N

1960a 0.012 3.86 0.112 215

1961a 0.012 3.86 0.112 215

1962a 0.012 3.86 0.112 215

1963 0.012 3.86 0.112 215

1964 0.056 1.82 0.148 249

1965 0.036 2.67 0.180 414

1966 0.051 2.01 0.160 579

1967 0.053 1.99 0.165 559

1968 0.060 1.96 0.182 421

1969 0.057 1.82 0.154 393

1970 0.116 2.66 0.582 119

1971 0.139 3.20 0.944 97

1972 0.198 2.96 1.183 83

1973 0.021 4.81 0.284 409

1974 0.015 8.90 0.543 423

1975 0.008 4.46 0.093 483

1976 0.003 11.97 0.189 463

1977 0.006 9.28 0.217 466

1978 0.004 11.22 0.235 519

1979 0.015 5.65 0.254 714

1980 0.018 8.35 0.583 772

1981 0.097 6.34 2.017 908

1982 0.055 6.16 1.099 1,002

1983b 0.068 5.60 1.124 Not applicable

1984 0.080 5.04 1.150 1,093

1985 0.061 6.80 1.429 1,172

1986 0.068 5.65 1.165 1,128

1987 0.035 5.08 0.502 1,160

1988 0.037 4.43 0.428 1,121

1989 0.022 4.45 0.258 1,437

1990 0.021 3.10 0.134 2,090

1991 0.020 2.47 0.088 2,126

1992 0.018 4.03 0.178 2,316

1993 0.008 4.32 0.086 2,633

1994 0.007 3.74 0.061 2,978

1995 0.007 3.63 0.058 3,107

1996 0.007 3.76 0.060 3,162

1997 0.006 3.59 0.048 3,000

1998 0.006 3.61 0.053 2,786

1999 0.007 3.52 0.053 2,686

2000 0.006 3.54 0.051 2,642

2001 0.006 3.47 0.049 2,770

2002 0.006 3.52 0.048 2,947

2003 0.006 3.27 0.044 2,996

2004 0.006 3.25 0.041 3,168

2005 0.006 3.12 0.038 3,210

2006 0.012 2.36 0.051 3,237

2007 0.011 2.57 0.052 3,183

2008 0.012 2.92 0.071 2,159

2009 0.013 2.69 0.065 2,110

2010 0.010 2.89 0.059 2,067

a. Values from 1963 are used as surrogate data for 1960 to 1962 based on the discussion in 

Section 5.0 Coworker Data Development. 

b. Per the instructions in Attachment A, the data for 1983 have been interpolated between the 1982 and 

1984 values.
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Pantex Plant,” e-mail to Oak Ridge Associated Universities Team, Division of Compensation 

Analysis and Support, Cincinnati, Ohio, May 13. [SRDB Ref ID: 157214]
Document No. ORAUT-OTIB-0086 Revision No. 01 Effective Date: 11/04/2016 Page 14 of 24

 

ORAUT (Oak Ridge Associated Universities Team), 2006, Occupational Onsite Ambient Dose 

Reconstruction for DOE Sites, ORAUT-PROC-0060, Rev. 01, Oak Ridge, Tennessee, June 28.

ORAUT (Oak Ridge Associated Universities Team), 2011, Use of Coworker Dosimetry Data for 

External Dose Assignment, ORAUT-OTIB-0020, Rev. 03, Oak Ridge, Tennessee, 

November 14.

ORAUT (Oak Ridge Associated Universities Team), 2015a, Pantex Plant – Occupational External 

Dose, ORAUT-TKBS-0013-6, Rev. 02, Oak Ridge Associated Universities, Tennessee, 

November 24.

ORAUT (Oak Ridge Associated Universities Team), 2015b, External Dose Coworker Methodology, 

ORAUT-RPRT-0071, Rev. 00, Oak Ridge Associated Universities, Tennessee, July 2.

ORAUT (Oak Ridge Associated Universities Team), 2015c, Pantex Fit Plots, April 7. [SRDB Ref ID: 

142269]

ORAUT (Oak Ridge Associated Universities Team), 2015d, Pantex Imputation Plots, April 7. [SRDB 

Ref ID: 142270]

Prather, M. P., 2004, “Re: Another question,” e-mail to J. J. Fix (Battelle), Pantex Plant, Amarillo, 

Texas, June 24. [SRDB Ref ID: 13474]

Prather, M. P., 2015, “Re: Recalculated dosimetry data using the Stanford algorithm,” e-mail to M. R. 

Rolfes (National Institute for Occupational Safety and Health), Consolidated Nuclear Security, 

Amarillo, Texas, February 26. [SRDB Ref ID: 141791]

SC&A (S. Cohen & Associates) and Salient, 2010, Sensitivity of NTA Film to Neutron Sources at 

Mound Laboratory, Rev. 1, Vienna, Virginia, and Jefferson, Maryland, July 23. [SRDB Ref ID: 

132770] 

The R Core Team, 2013, R: A Language and Environment for Statistical Computing, R Foundation for 

Statistical Computing, Vienna, Austria, May 16.

Tracerlab (Tracerlab/Keleket), 1962–1963, Twin-Film Service Radiation Dosage Reports, Richmond, 

California, January 18. [SRDB Ref ID: 14348]

Vallario, E. J., D. E. Hankins, and C. M. Unruh, 1969, AEC Workshop on Personnel Neutron 

Dosimetry, September 23–24, 1969, BNWL-1340, Battelle Pacific Northwest Laboratory, 

Richland, Washington. [SRDB Ref ID: 11096]

Wilson, R. H., 1960, Detection Level of the Film Badge System, HW-67697, General Electric 

Company, Hanford Atomic Products Operation, Richland, Washington, November 28. [SRDB 

Ref ID: 15403]

Wilson, R. H., 1987, Historical Review of Personnel Dosimetry Development and its Use in Radiation 

Protection Programs at Hanford, 1944 to the 1980s, PNL-6125, Battelle Memorial Institute, 

Pacific Northwest Laboratory, Richland, Washington, February. [SRDB Ref ID: 262]

Wilson, R. H., J. J. Fix, W. V. Baumgartner, and L. L. Nichols, 1990, Description and Evaluation of the 

Hanford Personnel Dosimeter Program from 1944 through 1989, PNL-7447, Battelle Memorial 

Institute, Pacific Northwest Laboratory, Richland, Washington, September. [SRDB Ref ID: 

4793]
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Xu, X. G., W. D. Reece, and J. W. Poston, Sr., 1995, “A Study of the Angular Dependence Problem in 

Effective Dose Assessment,” Health Physics, volume 68, number 2, pp. 214–224. [SRDB Ref 

ID: 154415]
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ATTACHMENT A 

EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 TO 2010)

TABLE OF CONTENTS

SECTION TITLE PAGE

A.1 Data Sources ......................................................................................................................... 17

A.2 General Comments................................................................................................................ 17

A.3 Instructions ............................................................................................................................ 18

LIST OF TABLES

TABLE TITLE PAGE

A-1 Sources of dose information................................................................................................... 19
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ATTACHMENT A

EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 TO 2010) (continued)

A.1 DATA SOURCES

BWXT Pantex 2011 (Unadjusted Pantex Data)

Doses worksheet: Columns to be used: 

SSN (Column B), 

Year (Column G), 

Month (Column H), 

WB Skin (Column K), 

WB Gamma (Column L), and

WB Neutron (Column M).

BWXT Pantex 2013

Sheet1 worksheet: Columns to be used: 

Badge number (Column C), 

Year (Column A), 

Month (Column B), 

WB Skin (Column E), 

WB Gamma (Column F), and

WB Neutron (Column G).

A.2 GENERAL COMMENTS

• A blank cell means an individual was not monitored.

• A missing month means an individual was not monitored that month.

• A cell containing zero means the individual was monitored, but the result was below the

censoring level. In this case, use the censoring level values discussed below. 

• There are four eras at Pantex: the NTA era from 1960 to 1973, the pre-Stanford era from 

1974 to 1979, the Stanford era from 1980 to mid-1993, and the more recent era from mid-1993 

to 2010: 

– During the NTA era (1960 – 1973), the adjustment factor for neutron dose is 2.9.

– For the period from 1974 to 1979, use the dosimetry data as they are recorded with no 

corrections or adjustments.

– For 1980 to 1983, use the Stanford algorithm data (BWXT Pantex 2013) and the 

unadjusted Pantex data (BWXT Pantex 2011) (see below).

– For 1994 to 2010, use BWXT Pantex (2011). 

– For 1983, which has no available Stanford algorithm data, omit this year from the 

analysis. Dose reconstructors should interpolate between the 1982 and 1984 values. 

(Note: The data for 1983 in Tables 7-1, 7-2, and 7-3 have been interpolated per these 

instructions).
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ATTACHMENT A

EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 TO 2010) (continued)

A.3 INSTRUCTIONS

The following four data fields are required:

• The year in which the dosimeter was worn.

• The month in which the dosimeter was worn.

• The identification (ID) number of the individual who wore the dosimeter. Social Security 

Number (SSN) is preferred over badge number. 

• The dose indicated by the dosimeter. NTA correction factor is 2.9 for 1960 to 1973.

Table A-1 provides the sources of these data fields by period.

Due to data deficiencies noted by Pantex personnel (TLD data could only be recalculated for persons 

for whom the actual TLD element readings were available), the following data rows should be 

discarded from each workbook (Prather 2015):

• Data that is present in BWXT Pantex (2011), but not present in BWXT Pantex (2013), and

• Data that is present in BWXT Pantex (2013), but not present in BWXT Pantex (2011).

For a given year and month for an individual, use the highest WB skin dose, WB gamma dose, and 

WB neutron dose values when comparing data (filtered as described above) in BWXT Pantex (2011, 

2013).

Imputation models should be calculated using the following CL values: 

• Gamma: CL = 10 mrem (1960-2004), CL = 5 mrem (2005-2010)

• Neutron: CL = 10 mrem (1960 – 1979), CL = 50 mrem (1980 – 1992), CL = 10 mrem (1993 – 

2010)

• Skin: CL = 40 mrem (1960-1972), CL = 10 mrem (1973-2005), CL = 15 mrem (2006-2010)

Due to insufficient data for neutron and skin badge readings, use 1963 annual doses as a surrogate

for 1960 to 1962 neutron, skin, and gamma badge readings. 
Document No. ORAUT-OTIB-0086 Revision No. 01 Effective Date: 11/04/2016 Page 19 of 24

ATTACHMENT A

EXTERNAL DOSE COWORKER STUDY INSTRUCTIONS (1960 TO 2010) (continued)

Table A-1. Sources of dose information.

Period Year Month Individual IDa Dosimeter Dose

1960–1979 

and 

1994–2010

BWXT Pantex 2011, 

Column G

BWXT Pantex 2011, 

Column H

BWXT Pantex 2011, 

Column B

BWXT Pantex 2011, 

Column K, WB skin dose; 

Column L, WB gamma dose; 

and 

Column M, WB neutron doseb

1980–1993 BWXT Pantex 2013, 

Column A; 

and 

BWXT Pantex 2011, 

Column G

BWXT Pantex 2013, 

Column B; 

and 

BWXT Pantex 2011, 

Column H 

BWXT Pantex 2013, 

Column C; 

and 

BWXT Pantex 2011, 

Column A

BWXT Pantex 2013, 

Column E, WB skin dose; 

Column F, WB gamma dose; 

and 

Column G, WB neutron dose 

as well as 

BWXT Pantex 2011, 

Column K, WB skin dose; 

Column L, WB gamma dose; 

and 

Column M, WB neutron dose

a. SSN is preferred over badge number.

b. NTA correction factor is 2.9 for 1960 to 1973.
Document No. ORAUT-OTIB-0086 Revision No. 01 Effective Date: 11/04/2016 Page 20 of 24

 

ATTACHMENT B 

NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS

TABLE OF CONTENTS

SECTION TITLE PAGE

B.1 Introduction ............................................................................................................................ 21

B.2 Monitored Workers................................................................................................................. 21

B.3 Response to Thermal Neutrons.............................................................................................. 21

B.4 Angular Response of NTA Film.............................................................................................. 21

B.5 NTA Track Fading.................................................................................................................. 22

B.6 Conclusions ........................................................................................................................... 24

LIST OF FIGURES

FIGURES TITLE PAGE

B-1 Latent image fading of neutron film plotted as a function of time ............................................ 23
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ATTACHMENT B 

NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS (continued)

B.1 INTRODUCTION

This attachment summarizes the issues concerning NTA film in relation to the NIOSH proposal for 

evaluating neutron doses at Pantex. The effect of these issues on the proposed approach is 

discussed in detail sufficient to establish the appropriate method for interpreting neutron exposures for 

monitored personnel. The following issues are common to all sites that used NTA film:

• Dosimeter threshold response to thermal neutrons,

• Methods used to correct for fading,

• Energy dependence of fading characteristics,

• Calibration sources and protocol, and

• Exchange or wear periods and wear conditions (temperature and humidity conditions).

In addition, there are other uncertainty corrections.

B.2 MONITORED WORKERS

NIOSH recommends that measured doses for monitored workers be adjusted using a correction 

factor that includes corrections for the threshold energy of NTA film, the angular dependence of film, 

and for fading that occurs during the use of NTA film.

B.3 RESPONSE TO THERMAL NEUTRONS

NTA film has an effective threshold energy of about 500 keV. It is not sensitive to thermal neutrons 

and monitors only fast neutrons. The NIOSH recommendation recognizes this deficiency in NTA film 

and recommends a correction factor to adjust monitored doses. A Monte Carlo n-particle (MCNP) 

model was developed to determine the amount of dose that was missed due to a sensitivity threshold 

of 500 keV for the conditions likely to have been encountered by workers who received neutron doses 

at Pantex (LANL 2003). The model used Research Department Formula X (RDX) thicknesses of 0 to

4 in., which is an appropriate approximation of the possible exposure scenarios. The results indicated 

that NTA film would miss 16% of the dose equivalent at the operator position (distance of 60 cm), 

which is the position likely to receive the highest dose. The MCNP evaluation also indicated that the 

NTA film would miss 29% of the dose equivalent at the observer position (distance of 240 cm), which 

would experience much lower doses by a factor of 16. Greater distances could result in larger 

fractions of low-energy neutrons, but the corresponding dose rates would be much smaller due to the 

distance factor as well as the fact that low-energy neutrons are much less effective at delivering dose. 

The NIOSH recommendation selects the more conservative value from the observer position to be 

applied to all doses. The resulting correction factor is 1.4 versus a corresponding correction factor of 

1.2 for the operator position. This recommendation is favorable to claimants.

B.4 ANGULAR RESPONSE OF NTA FILM

NIOSH recommends a factor of 1.33 to account for the angular response of NTA film. This factor is 

based on a study conducted by Kathren, Prevo, and Block (1965). Calibrations are typically done by 

irradiating the dosimeter to be calibrated in an anterior-posterior (AP) configuration. The AP 

configuration is used because that is the anticipated exposure configuration when a worker is wearing 

the badge on the front portion of the body. The study was performed to determine the effect of 

irradiation at other angles by rotating the NTA film in front of a neutron source. This rotational 

movement resulted in AP, posterior-anterior, and lateral exposure; the results were the composite of 

exposure from all directions.
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ATTACHMENT B 

NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS (continued)

DOELAP requires the angular response of a dosimeter to be evaluated but does not require that an 

angular dependence correction be made to measured exposures. A study of angular dependence 

problems pointed out that exposures at some non-AP angles are less effective in delivering an 

effective dose equivalent because most of the important organs are in the anterior portion of the body

(Xu, Reece, and Poston 1995). An AP exposure position delivers the highest effective dose 

equivalent. As a result, it is possible for exposures from isotropic dosimeters to overestimate the 

actual effective dose equivalent.

The correction factor recommended by NIOSH (1.33) is soundly based and favorable to claimants in 

that the dosimeter can in fact provide a reasonably accurate effective dose equivalent from an angular 

perspective because the exposure to neutrons normally occurs while working with the source of 

neutrons in front of the body. NIOSH is recommending an additional one-third be added to the 

monitored exposure.

B.5 NTA TRACK FADING

The NTA film issues at Pantex are essentially identical to the issues that have been raised and 

addressed at the Mound site. The fading issue was a major area of discussion in documented Mound 

calibration and fading experimentation on NTA film. The fading information from Mound is similar to 

that observed at other U.S. Atomic Energy Commission (AEC) sites that used NTA film.

In the July 27, 2010, transcript of the Mound Work Group meeting, S. Cohen and Associates (SC&A) 

summarized the issues in relation to neutron fading. SC&A made the point that, in general, workers 

were exposed to moderated (shielded) neutron sources that lowered the average energy of the 

neutron spectrum in comparison with unshielded neutron sources. Lower-energy neutron tracks in 

NTA film fade faster than tracks from higher-energy neutrons, and even when the calibration source 

and exchange frequency were matched with the work conditions, the moderation might not have been 

well matched. As a result, SC&A suggested that the fading values used by NIOSH in the site profile 

(33% in the first week after exposure and 56% in the 2-week period) might not be favorable to the 

claimant. From the transcript it appears that all agreed that no worker at Mound would be exposed to 

a source that was exclusively composed of low-energy neutrons (below the NTA energy threshold), so 

there would always be some signal that could be registered by the NTA film (NIOSH 2010). 

On July 23, 2010, SC&A and Salient published a white paper, Sensitivity of NTA Film to Neutron 

Sources at Mound Laboratory (SC&A and Salient 2010), which noted that NTA track fading was 

studied by the Mound staff in 1967 and 1968 and a formal Mound report was issued July 1, 1968, 

reporting that 33% of the tracks faded after 1 week and 56% after 2 weeks. However, the purpose of 

that study was to establish the calibration and processing protocols that would appropriately 

compensate for the fading phenomena that was known to exist.

After the Work Group meeting, NIOSH found that the Mound experiments had also been published in 

the Health Physics journal (Kahle, Arnett, and Meyer 1969). The experimental description in this 

published peer-reviewed report provides detail that might not have been clear in the initial reports. 

Twenty NTA film badges were exposed to a PuF4 source with an average energy of 1.3 MeV, and 20 

badges were exposed to a moderated 238PuO2 source with an average energy of 0.9 MeV. Based on 

the unpublished Mound reports, NIOSH believes each badge contained four NTA films, which would 

be consistent with uncertainty data in the unpublished Mound reports. Each group of 20 badges was 

subdivided into two groups of 10. One group of 10 badges was exposed to the source each day for 

2 weeks, and one group was exposed on the day of development. The film badges were stored away 

from radiation before exposure, and during the interval from exposure to film development, at a 
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ATTACHMENT B 

NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS (continued)

constant temperature and constant relative humidity. Ordinary development and readout procedures 

were followed. Only those tracks that could be positively identified were counted. Kahle, Arnett, and 

Meyer (1969) reported:

Contrary to what was expected, the results indicated less fading of neutron tracks in films 

exposed to the lower average energy moderated 238PuO2 source. There was 33% fading 

of neutron tracks for film exposed to the PuF source for a seven day interval from 

exposure to film development and 56% fading for a fourteen day interval. There was 17% 

fading of neutron tracks for film exposed to the moderated 238Pu02 source for a seven 

day interval from exposure to film development and 30% fading for a fourteen day 

interval. These results are shown in [Figure B-1].

Since more fading is expected for lower energy neutrons, the combined results of the 

two experiments indicate that latent image fading cannot be accurately predicted on the 

basis of average energy alone. The entire neutron spectrum must be considered to 

predict latent image fading of tracks in neutron monitoring film.

Figure B-1. Latent image fading of neutron film plotted as a function of time (Kahle, Arnett, and 

Meyer 1969). 
Document No. ORAUT-OTIB-0086 Revision No. 01 Effective Date: 11/04/2016 Page 24 of 24

ATTACHMENT B

NTA FILM ISSUES AND DOSE ASSIGNMENTS FOR MONITORED WORKERS (continued)

NIOSH has recommended that a correction factor be applied to the neutron monitoring results to 

accommodate any fading that could have occurred during the wear period of the NTA film dosimeter. 

The correction factor is based on a value determined at Mound Laboratory of 9% per week for a 

4-week (1-month) period. Because fading corrections were incorporated into the processing protocol, 

the NIOSH recommendation to apply a fading correction of 1.56 is favorable to claimants.

B.6 CONCLUSIONS

For monitored workers, the NIOSH recommendation is to apply a correction factor of 1.4 to correct for 

the threshold energy response of NTA film, a correction factor of 1.33 for angular dependence, and a 

correction factor of 1.56 to account for uncorrected fading of the NTA film. These correction factors 

produce the overall NIOSH correction factor of 2.9. Further, the final dose is modified by the

International Commission on Radiation Protection (ICRP) Publication 60 correction factor of 1.91 

(ICRP 1991) (before January 1, 2010, when Publication 60 quality factors were implemented by 

Pantex dosimetry staff). In a paper by Vallario, Hankins, and Unruh (1969), the results of an 

intercomparison of AEC contractors and vendors were reported, with the observation that NTA film 

generally under-responded by 25% to 50%. This study was based on laboratory irradiations to known 

doses; no corrections were made for angular dependence. If the 50% under-response is corrected for 

angular response using the value above, the correction factor becomes 2.7, which is in reasonable 

agreement with the NIOSH recommendation. The NIOSH recommendation has a sound technical

basis and should be implemented for monitored workers.