ORAU TEAM

Dose Reconstruction

Project for NIOSH

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

Page 1 of 11

Document Title:

External Coworker Dosimetry Data for the 

Paducah Gaseous Diffusion Plant 

Document Number: ORAUT-OTIB-0031

Revision: 00

Effective Date: 05/19/2005

Type of Document: OTIB

Supersedes: None

Subject Expert: Steven E. Merwin

Document Owner

Approval: Signature on File Approval Date: 05/12/2005

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File Concurrence Date: 05/13/2005

Richard E. Toohey, Project Director

Approval: Signature on File Approval Date: 05/19/2005

James W. Neton, Associate Director for Science

 New Total Rewrite Revision Page Change

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

PLEASE DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION.
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 2 of 11

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION

NUMBER DESCRIPTION

03/09/2005 00-A New technical information bulletin to provide information to allow 

ORAU Team dose reconstructors to assign doses at the Paducah 

Gaseous Diffusion Plant to certain workers who have no or limited 

monitoring data, based on site coworker data. Initiated by Steven E. 

Merwin.

03/28/2005 00-B Incorporates internal review comments. Initiated by Steven E. 

Merwin.

04/27/2005 00-C Incorporates NIOSH review comments. Initiated by Steven E. 

Merwin.

05/19/2005 00 First approved issue. No training required. Initiated by Steven E. 

Merwin.
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 3 of 11

TABLE OF CONTENTS

Section

Publication Record ..............................................................................................................................

Page

2

1.0 Purpose ......................................................................................................................................4

2.0 Background................................................................................................................................. 4

3.0 General Approach.......................................................................................................................5

4.0 Applications and Limitations........................................................................................................5

5.0 References ................................................................................................................................. 5

6.0 PGDP Coworker Data Development ...........................................................................................6

7.0 PGDP Coworker Annual Dose Summaries .................................................................................7

8.0 PGDP Coworker Annual Dose Distributions................................................................................9

Attachment A PGDP External Dosimetry Data Review .....................................................................11

LIST OF TABLES

Table

1 Missed external doses based on PGDP Occupational External 

Dosimetry TBD2 and ORAUT-OTIB-0017..............................................................................

Page

7

2 Annual PGDP external coworker doses modified to account for missed 

dose (rem) ..........................................................................................................................10
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 4 of 11

1.0 PURPOSE

Technical Information Bulletins (TIBs) 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. TIBs may be used to assist the 

National Institute for Occupational Safety and Health 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 facility” as defined in the Energy Employees 

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

The purpose of this Technical Information Bulletin (TIB) is to provide information to allow ORAU Team 

dose reconstructors to assign doses to Paducah Gaseous Diffusion Plant (PGDP) workers who have 

no or limited monitoring data, based on site coworker data. The data in this TIB are to be used in 

conjunction with ORAUT-OTIB-0020, “Use of Coworker Dosimetry Data for External Dose 

Assignment.”1 

2.0 BACKGROUND

The ORAU Team is conducting a series of coworker data studies to permit dose reconstructors to 

complete certain cases for which external and/or internal monitoring data are unavailable or 

incomplete. Cases not having complete monitoring data may fall into one of several categories, 

including:

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

(e.g., a non-radiological worker).

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

• The worker may 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-0020,1 some cases not having complete monitoring data can be 

processed based on assumptions and methodologies that do not involve coworker data. For 

example, many cases falling in the first category above can be processed by assigning ambient 

external and internal doses based on information in the relevant site Technical Basis Documents 

(TBDs).

As described in the PGDP External Dosimetry TBD,2

 operations at the site began in 1952, and in 

1953 the site began using dosimeter and processing technical support provided by the Oak Ridge 

National Laboratory (ORNL). Until July 1960, dosimeters were issued to a limited number of 

individuals, i.e., those with the highest potential for exposure, and the badges were exchanged 

weekly. After that time, dosimeters were assigned to all workers who entered a controlled area, and 

the badges were exchanged and processed on a monthly or quarterly schedule. There does not 

appear to be any significant administrative practice that would jeopardize the integrity of the recorded 

dose of record.
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 5 of 11

3.0 GENERAL APPROACH

As described in ORAUT-OTIB-0020,1 the general approach to developing coworker data for cases 

without external monitoring data involves two phases. The first (Phase I) permits cases to be 

processed when a “best and final” estimate of dose is not required for claim determination. The 

second (Phase II) facilitates the assignment of “best and final estimates” of dose, when necessary. 

This initial revision of this TIB provides coworker external dosimetry summary statistics applicable to 

Phase I dose reconstructions; coworker dose distributions applicable to Phase II dose reconstructions 

will be made available in a subsequent revision. 

4.0 APPLICATIONS AND LIMITATIONS

1. Revision 00 of this document provides PGDP coworker data and information that may be used 

only for clearly non-compensable cases for which a higher external dose can be assigned than 

was likely to have been actually received, or compensable cases on a limited basis (see Section 

7.0). Revision 01 of this document will provide dose distributions and additional information based 

on the data presented herein to permit the processing of cases requiring a best estimate analysis.

2. Some PGDP workers may have worked at one or more other major sites within the DOE complex 

during their employment history. Thus, the data presented herein must be used with caution to 

ensure that for clearly non-compensable cases, unmonitored external doses from multiple site 

employment have been overestimated. This will typically require the availability of External 

Coworker Dosimetry Data TIBs for all relevant sites.

3. Summary statistics based on PGDP dosimetry data presented in this TIB do not extend beyond 

1995 because at the time this TIB was drafted, data beyond 1997 were not available, and the data 

for 1996 and 1997 included too few data points to be considered reliable. However, the absence 

of these data (and the subsequent development of dose distributions) should not interfere with the 

processing of most PGDP cases having a lack of external dosimetry data since well before 1995 

the monitoring and reporting practices at the site ensured that essentially all workers with a 

potential for external radiation exposure were monitored and the results are readily accessible. 

Should the need arise and sufficient data become available, coworker dosimetry data beyond the 

year 1995 will be presented in a subsequent revision to this TIB.

4. The data presented in this TIB address penetrating radiation from gamma radiation and nonpenetrating radiation from beta radiation. Neutron data are not presented. However, the potential 

for neutron exposures at the PGDP is limited to certain site areas and facilities, and the associated 

doses were low.

2

 Therefore, the TBD should be used as the basis for assigning neutron doses, 

when relevant, in addition to the photon and/or beta doses assigned in accordance with this TIB.

5. External on-site ambient doses should not be included in addition to the coworker doses assigned 

in accordance with this TIB, because any such doses would have been included in the dosimetry 

results reported by the site which were used as the basis for the coworker dose distributions 

presented below.

2,4

5.0 REFERENCES

1. ORAU Team, ORAUT-OTIB-0020, Use of Coworker Dosimetry Data for External Dose 

Assignment, Rev 00, December 29, 2004. 
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 6 of 11

2. ORAU Team, ORAUT-TKBS-0019-6, Technical Basis Document for the Paducah Gaseous 

Diffusion Plant – Occupational External Dose, Rev 00, August 24, 2004.

3. NIOSH (National Institute for Occupational Safety and Health), External Dose Reconstruction 

Implementation Guideline, Rev. 0, OCAS-IG-001, Office of Compensation Analysis and Support, 

Cincinnati, Ohio, 2002.

4. ORAU Team, ORAUT-PROC-0060, External On-Site Ambient Dose Reconstruction for DOE 

Sites, Rev 00, March 7, 2005. 

5. ORAU Team, ORAUT-OTIB-0017, Interpretation of Dosimetry Data for Assignment of Shallow 

Dose, Rev 00, January 19, 2005.

6.0 PGDP COWORKER DATA DEVELOPMENT

Dosimetry data for monitored PGDP workers from various sources were evaluated (see Attachment 

A). The data selected for development of coworker doses were 1) a “history tape” containing annual 

data between 1953 and 1975 and quarterly data between 1976 and 1988, and 2) a database titled 

“OHIS_External” containing mostly quarterly data between 1989 and 1997 (although the data for 1996 

and 1997 were excluded from consideration, as discussed previously). In all cases, the reported data 

corresponded to deep doses (i.e., penetrating gamma radiation) and shallow doses (i.e., penetrating 

plus non-penetrating radiation). 

The annual data reported between 1953 and 1975 were prorated to account for partial years of 

employment based on an analysis of the length of monitored employment associated with the data 

(see Section 7.0 for further discussion). The reported quarterly data between 1976 and 1988 were 

also prorated, but using a different approach (also described further in Section 7.0). The data 

between 1989 and 1995 included specific monitoring start and end dates, so the data were prorated 

based on 365 days/year. The data were prorated so that coworker doses representing a full year of 

monitored employment could be derived; this permits the dose reconstructor to assign appropriate 

doses based on specific employment dates and job descriptions. 

The validity of the data selected for coworker dose development was confirmed by selecting a

sampling of claimant dosimetry data submitted by the site as part of the EEOICPA Subtitle B program

and comparing it to the data selected as described above. A review of annual data for ten claimants 

covering over 150 worker-years of monitored employment at PGDP indicated excellent agreement 

between the two data sets. Specifically, a perfect match was found for more than 95% of the reported 

values. It is concluded that the data cited above are acceptable for the development of coworker 

doses for the PGDP. 

Adjustment for Missed Dose

According to the External Dose Reconstruction Implementation Guideline,3 missed doses are to be 

assigned for null dosimeter readings to account for the possibility that doses were received but not

recorded by the dosimeter or reported by the site. Annual missed doses are calculated by multiplying 

the number of null badge readings by the reported dosimeter limit of detection (LOD) and summing 

the results. These values are used as the 95th percentile of a lognormal distribution for the purpose 

of calculating probability of causation which is determined by the Department of Labor (DOL); thus, in 

IREP the calculated missed doses are multiplied by 0.5 and entered in Parameter 1, and a value of 

1.52 is entered in Parameter 2, to represent the geometric mean and geometric standard deviation, 

respectively.
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 7 of 11

The assignment of missed doses for monitored workers is particularly significant for PGDP claimants

prior to August 1960 when workers were monitored weekly. Table 1 lists the maximum annual missed

dose by era and type of radiation (penetrating gamma and non-penetrating) based on information 

presented in the site TBD2 and ORAUT-OTIB-0017.5 

Table 1. Missed external doses based on PGDP Occupational External Dosimetry TBD2 and ORAUTOTIB-0017.

5

Period

Penetrating 

LOD (rem)

Non-penetrating 

LOD (rem)a

Exchange 

frequency

Maximum annual missed dose (rem)

Penetrating Non-penetrating

1953–1959 0.04 0.05 Weekly 2.080 2.600

1960 0.04 0.05 Variedb 1.280 1.600

1961–1980 0.04 0.05 Variedc 0.160 0.200

1981–1988 0.02 0.03 Variedd 0.080 0.120

1989–Present 0.02 0.02 Quarterly 0.080 0.080

a. ORAUT-OTIB-0017, Attachment C provides an explanation for the non-penetrating LODs for the PGDP.

b. The exchange frequency was weekly through July 1960, then became less frequent (see note “c”).

c. The TBD indicates that either monthly, quarterly, or annual exchange frequencies were used during this period, 

depending on work locations and the potential for exposure. A review of the data indicates that quarterly exchanges 

were predominant; thus, quarterly exchanges have been assumed here to calculate the maximum annual missed dose. 

d. The TBD indicates that either quarterly or annual exchange frequencies were used during this period, depending on the 

potential for exposure. A review of the data indicates that quarterly exchanges were predominant; thus, quarterly 

exchanges have been assumed here to calculate the maximum annual missed dose.

Special Considerations

Certain aspects of the external dosimetry practices at the PGDP documented in the TBD2 were 

considered in the analysis of the site data. These include:

• In some cases, values less than the dosimeter LODs (listed in Table 1 above) were reported 

by the site. For example, values as low as a few millirem (mrem) were reported even though 

the penetrating LOD was considered to be 20 or 40 mrem (depending on the era). 

• As discussed previously, prior to 1976, the data available to analyze coworker doses represent 

annual dose summaries for individual workers. Because these data include partial work years, 

the average annual doses reported tend to underestimate the average annual doses received 

by employees who worked an entire year. 

As described in Section 7.0 below, a claimant-favorable approach was adopted in the development of 

coworker dose summaries, and this approach is intended to account for any underestimate of doses 

to radiological workers at the PGDP based on the considerations described above.

7.0 PGDP COWORKER ANNUAL DOSE SUMMARIES

Based on the information and approaches described above, PGDP coworker annual external 

dosimetry summaries were developed for use in the evaluation of external dose for certain claimants 

potentially exposed to workplace radiation, but with no or limited monitoring data provided by DOE. 

These summaries were developed using the following steps:

1. As described in Section 6.0 above, for data between 1953 and 1975, the reported deep and 

shallow doses, which represented annual summary data, were modified to account for partial 

years of employment. This adjustment was made by analyzing the NOCTS employment data for 

PGDP workers and adjusting the reported doses upward by an appropriate multiplier 

corresponding to the average fraction of a year an employee worked at the site. For example, if in 

a particular calendar year the average employment period for all PGDP employees in NOCTS was 
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 8 of 11

11 months, the reported annual doses were multiplied by 12/11, or 1.09. This permits the dose 

reconstructor to assign an appropriate prorated dose to account for partial years of employment or 

potential exposure. 

2. For data between 1976 and 1988, the reported deep and shallow doses, which represented 

quarterly summary data, were modified to account for partial years of employment. Consistent 

with the guidelines in ORAUT-OTIB-0020,1 doses for individuals with less than four quarters of 

data for a particular year were converted to annual doses by extrapolation (i.e., one quarterly 

result was multiplied by 4; two quarterly results were multiplied by 2; and three quarterly results 

were multiplied by 1.333).

3. For data between 1989 and 1995, the reported deep and shallow doses, which represented 

primarily quarterly data, were modified to account for partial years of employment by multiplying 

the data by 365/X, where X corresponds to the number of days the employee was issued a 

dosimeter. This information was available for this period because the monitoring start and end 

dates were included with the data.

4. The 50th, 95th and 99th percentile annual penetrating and shallow doses were derived for two 

scenarios: excluding and including reported zeroes.

5. The 50th, 95th and 99th percentile doses based on the exclusion of zeroes were used as the 

basis for the coworker data set, since these are representative of radiological worker doses which 

are the principal focus of the coworker studies. However, to ensure claimant favorability, the 

percentile doses with zero results included were evaluated; and if the addition of one-half of the 

maximum annual missed doses (listed in Table 1) to these percentile doses resulted in values 

exceeding the percentile doses based on the exclusion of zeroes, the latter were replaced with the 

former.

6. Because the reported shallow doses include both penetrating and non-penetrating radiation, the 

percentile doses pertaining to penetrating radiation were subtracted from the percentile doses 

pertaining to the reported shallow doses to derive percentile doses pertaining to non-penetrating 

radiation. 

7. The results are presented in Table 2 below. These percentile doses should be used for selected 

PGDP workers with no or limited monitoring data using the methodologies outlined in Section 7.0 

of ORAUT-OTIB-0020.1

 Because the values include a claimant-favorable adjustment for potential 

missed dose, the 50th percentile values should not be applied for cases with POCs >50% without 

first subtracting missed dose based on the information in Table 1 and Step 5 above. Should these 

data prove insufficient for the completion of dose reconstructions, “best estimate” coworker dose 

distributions should be used as documented in Section 8.0 below and in accordance with Section 

8.0 of ORAUT-OTIB-0020.1

 

Doses to organs impacted only by penetrating radiation (e.g., organs other than the skin, breast and 

testes) are calculated based only on the “Gamma” columns in Table 2 combined with the appropriate 

organ dose conversion factors (DCFs).3

 Doses to the skin, breast and testes (and any other cancer 

location potentially impacted by non-penetrating radiation) are determined based on both the 

“Gamma” and “Non-penetrating” columns; gamma doses are assigned as photons with an energy 

range consistent with information in the external dosimetry TBD for the PGDP,

2 and non-penetrating 

doses are assigned as electrons >15 keV with corrections applied to account for clothing attenuation 

or other applicable considerations.5

 
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 9 of 11

A “zero” value in Table 2 for non-penetrating dose will not result in a dose of zero being assigned to 

an organ such as the skin. For example, the 50th percentile dose to the skin in 1987 would be 

assigned entirely as 0.170 rem of photons. This approach does not

With the methodology described above, null or negative values for non-penetrating dose can occur 

because of the subtraction of the reported penetrating doses from the reported shallow doses, and the 

claimant-favorable method described above to establish coworker doses based on an analysis of data 

both with and without zeroes included. In some cases, especially when few data points are involved, 

the shallow percentile doses were less than the penetrating percentile doses when reported zeroes 

were excluded, which resulted in a negative calculated non-penetrating dose. Also, in rare cases this 

approach resulted in a higher non-penetrating dose compared to the dose in a lower-percentile 

category for the same year. Such situations were adjusted in a claimant-favorable manner by 1) 

changing all calculated negative values to zero, and 2) as necessary, adjusting upward the doses in 

the 95th and/or 99th percentile categories to ensure they were not lower than the doses in the 

corresponding 50th percentile category. This situation occurred occasionally and only for the later 

years, when the data points were relatively few and the doses were relatively low.

result in an underestimation of

probability of causation which is determined by DOL because assigning beta dose as gamma dose in 

IREP has no negative effect, since the radiation effectiveness factors are the same for >15 keV 

electrons and >250 keV photons, and are higher for 30–250 keV photons. 

8.0 PGDP COWORKER ANNUAL DOSE DISTRIBUTIONS

Reserved
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 10 of 11

Table 2. Annual PGDP external coworker doses modified to account 

for missed dose (rem). 

Year

Gamma

99th%

Gamma

95th%

Gamma

50th%

Non-pen

99th%

Non-pen

95th%

Non-pen

50th%

1953 2.092 1.676 1.148 2.404 1.734 0.706

1954 2.488 2.238 1.203 5.880 4.391 0.975

1955 3.264 2.364 1.087 7.062 5.579 1.053

1956 4.182 2.732 1.093 6.587 4.834 1.053

1957 3.381 2.244 1.092 6.372 4.516 0.585

1958 3.047 2.039 1.040 6.439 4.026 0.491

1959 2.792 1.920 1.103 6.017 5.153 0.699

1960 2.231 1.564 0.692 4.906 3.145 0.457

1961 1.897 1.184 0.154 2.816 1.760 0.041

1962 1.956 1.306 0.150 3.137 1.582 0.075

1963 2.208 1.503 0.148 1.934 0.654 0.032

1964 1.239 0.809 0.085 0.939 0.589 0.032

1965 1.061 0.482 0.080 0.479 0.301 0.022

1966 1.200 0.435 0.080 0.310 0.378 0.020

1967 0.822 0.269 0.111 1.253 0.447 0.030

1968 1.058 0.665 0.093 3.353 0.843 0.114

1969 1.456 0.911 0.133 2.520 1.592 0.225

1970 0.597 0.449 0.084 1.682 1.047 0.126

1971 1.121 0.923 0.130 3.033 1.618 0.078

1972 1.361 0.888 0.144 3.796 1.561 0.072

1973 1.299 0.970 0.082 4.442 2.831 0.123

1974 0.883 0.627 0.080 2.791 1.276 0.067

1975 0.550 0.267 0.110 1.745 0.609 0.060

1976 0.760 0.334 0.082 2.234 0.494 0.055

1977 0.388 0.209 0.082 1.250 0.403 0.060

1978 0.304 0.213 0.109 0.401 0.155 0.036

1979 0.246 0.129 0.080 0.459 0.270 0.079

1980 0.318 0.220 0.080 0.290 0.140 0.020

1981 0.761 0.411 0.080 0.674 0.378 0.070

1982 1.267 1.044 0.275 2.408 1.002 0.085

1983 1.150 0.850 0.260 1.336 0.590 0.100

1984 1.222 0.818 0.180 1.997 0.662 0.100

1985 1.193 0.732 0.180 2.874 0.802 0.180

1986 1.506 0.800 0.240 2.967 1.456 0.040

1987 1.079 0.791 0.170 1.503 0.417 0.000

1988 2.328 0.902 0.280 0.622 0.258 0.080

1989 0.248 0.201 0.040 0.140 0.008 0.008

1990 0.249 0.192 0.040 0.080 0.006 0.006

1991 0.186 0.144 0.040 0.068 0.028 0.002

1992 0.298 0.218 0.043 0.011 0.002 0.002

1993 0.229 0.169 0.040 0.014 0.014 0.014

1994 0.333 0.241 0.040 0.010 0.010 0.010

1995 0.320 0.234 0.040 0.015 0.015 0.015
Document No. ORAUT-OTIB-0031 Revision No. 00 Effective Date: 05/19/2005 Page 11 of 11

ATTACHMENT A

PGDP EXTERNAL DOSIMETRY DATA REVIEW

There are many tables included in this database; they contain both internal and external dosimetry 

data. The external data listings are provided below, with their descriptions (from the document 

provided by PGDP).

PGDP_Dosimetry Data database

• DRS_89_THRU_96 – External dosimetry records from 1989 to 1996.

• DRS_97_THRU_98 – External dosimetry records from 1997 to 1998.

• OHIS_EXTERNAL_DOSE – External dosimetry records from 1981 to 1997.

• OHIS_EXTREMITY_DOSE – Extremity dosimetry records from 1990 to 1995.

• OHIS_HP_SCHEDULE – Dosimetry scheduling information from 1987 to 1998.

• OHIS_JOB_HISTORY – Personnel job history information from 1986 to 1998.

• HISTORY_TAPE – External dosimetry records from 1953 to 1988.

• HIS20_EDD_CALCULATED_EXPOSURE – Calculated external dosimetry exposure records 

from 1980 to 1998.

• HIS20_EDD_INACTIVE_IRD_EXPOSURE – External dosimetry records from 1953 to 1998.