ORAU TEAM

Dose Reconstruction

Project for NIOSH

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

Page 1 of 9 

Document Title:

External Coworker Dosimetry Data for the 

Savannah River Site 

Document Number: ORAUT-OTIB-0032

Revision: 00

Effective Date: 05/31/2005

Type of Document: OTIB

Supersedes: None

Subject Expert: Steven E. Merwin

Document Owner

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

Judson L. Kenoyer, Task 3 Manager

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

Richard E. Toohey, Project Director

Approval: Signature on File Approval Date: 05/31/2005

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-0032 Revision No. 00 Effective Date: 05/31/2005 Page 2 of 9

PUBLICATION RECORD

EFFECTIVE 

DATE

REVISION

NUMBER DESCRIPTION

04/04/2005 00-A New technical information bulletin to provide information to allow 

ORAU Team dose reconstructors to assign doses to Savannah River 

Site workers who have no or limited monitoring data, based on site 

coworker data. Initiated by Steven E. Merwin.

04/11/2005 00-B Incorporates internal review comments. Initiated by Steven E. 

Merwin.

05/12/2005 00-C Incorporates OCAS comments. Initiated by Steven E. Merwin.

05/31/2005 00 First approved issue. No training required. Initiated by Steven E. 

Merwin.
Document No. ORAUT-OTIB-0032 Revision No. 00 Effective Date: 05/31/2005 Page 3 of 9

TABLE OF CONTENTS

Section

1.0 Purpose ......................................................................................................................................

Page

4

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

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

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

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

6.0 SRS Coworker Data Development..............................................................................................6

7.0 SRS Coworker Annual Dose Summaries ....................................................................................7

8.0 SRS Coworker Annual Dose Distributions................................................................................... 8

LIST OF TABLES

Table

1 Missed external doses based on SRS TBD and ORAUT-OTIB-0017 .......................................

Page

7

2 Annual SRS external coworker doses modified to account for missed 

dose (rem) ...............................................................................................................................9
Document No. ORAUT-OTIB-0032 Revision No. 00 Effective Date: 05/31/2005 Page 4 of 9

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 TIB is to provide information to allow ORAU Team dose reconstructors to assign 

doses to Savannah River Site (SRS) 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 SRS TBD,2

 operations at the site began in 1952, and the site initially used 

dosimeter and processing technical support provided by the Oak Ridge National Laboratory (ORNL). 

SRS routine practices appear to have required assigning dosimeters to all workers who entered a 

controlled radiation area. There does not appear to be any significant administrative practice that 

would jeopardize the integrity of the recorded dose of record; however, the “adjustment to reported 

dose” recommended by the TBD (e.g., 1.119 for the reported deep photon dose prior to 1986) is

appropriate for the coworker doses established in this TIB, since the doses are based on the SRS 

dosimetry data.
Document No. ORAUT-OTIB-0032 Revision No. 00 Effective Date: 05/31/2005 Page 5 of 9

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 SRS 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 actually been received, or for 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 SRS 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 SRS dosimetry data presented in this TIB do not extend beyond 

1999 because at the time this TIB was drafted, sufficient data beyond that year were not available. 

However, the absence of these data (and the subsequent development of dose distributions) 

should not interfere with the processing of most SRS cases having a lack of external dosimetry 

data, since well before 1999 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 1999 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 or low-energy photon radiation. Neutron data are not presented. 

The site TBD2 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. Prior to 1980, external on-site ambient doses should be included in addition to the coworker doses 

assigned in accordance with this TIB because prior to that year it is possible that such doses 

would not have been included in the dosimetry results reported by the site.

5

 

5.0 REFERENCES

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

Assignment, Rev 00, December 29, 2004. 

2. ORAU Team, ORAUT-TKBS-0003, Technical Basis Document for the Savannah River Site to be 

Used for EEOICPA Dose Reconstructions, Rev 02, October 29, 2004.
Document No. ORAUT-OTIB-0032 Revision No. 00 Effective Date: 05/31/2005 Page 6 of 9

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-OTIB-0017, Interpretation of Dosimetry Data for Assignment of Shallow 

Dose, Rev 00, January 19, 2005.

5. ORAU Team, ORAUT-OTIB-0007, Technical Information Bulletin: Occupational Dose from 

Elevated Ambient Levels of External Radiation, Rev 00, November 12, 2003.

6.0 SRS COWORKER DATA DEVELOPMENT

Dosimetry data for monitored SRS workers available from the HPAREH database were evaluated. In 

all cases, the reported data corresponded to annual deep doses (i.e., penetrating gamma radiation) 

and annual shallow doses (i.e., penetrating plus non-penetrating radiation). 

The annual data reported in HPAREH 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 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 HPAREH summary data submitted by the site as part of the EEOICPA Subtitle B program

and comparing it to the data described above. A review of data for two claimants with complex and 

extensive dosimetry records covering the years 1953 through 1999 indicated good agreement 

between the two data sets. Importantly, when the data did not match exactly, there was no apparent 

bias toward an under or overestimation of dose for either data set, suggesting that relying on the 

HPAREH annual data for coworker dose reconstruction would not result in a negative bias against the 

claimants.

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; 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.

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

prior to October 1957 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-0017.4 

Special Considerations

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

considered in the analysis of the site data. These include:
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Table 1. Missed external doses based on SRS TBD and ORAUT-OTIB-0017. 

Period

Penetrating 

LOD (rem)

Non-penetrating 

LOD (rem)

Exchange 

frequency

Maximum annual missed dose (rem)

Penetrating Non-penetrating

1951–9/1957 0.04 0.05 Weekly 2.080 2.600

10/1957–1964 0.04 0.05 Biweekly 1.040 1.300

1965 0.04 0.05 4-week 0.520 0.200

1966–1970 0.04 0.05 Monthly 0.480 0.600

1971–1983 0.015 0.025 Monthly 0.180 0.300

1984–Present 0.005 0.020 Monthly 0.060 0.240

• Although the majority of the annual doses reported were positive, many of the underlying 

individual badge readings were zero, and thus the reported annual doses tend to 

underestimate the actual doses received because of missed doses below the dosimeter LODs 

(see Table 1 above). 

• In some cases, values less than the dosimeter LODs were reported by the site. For example, 

values as low as a few millirem (mrem) were reported even though the penetrating LOD was 

as high as 40 mrem (depending on the era).

• As discussed previously, 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 should account for any underestimate of doses to 

radiological workers at the SRS based on the above considerations.

7.0 SRS COWORKER ANNUAL DOSE SUMMARIES

Based on the information and approaches described above, SRS 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, 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 SRS 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 SRS employees in NOCTS was 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. The 50th, 95th, and 99th percentile annual penetrating and shallow doses were derived for two 

scenarios: excluding and including reported zeroes.

3. For each year and percentile evaluated, the higher of the following two values was selected: 1) the 

percentile dose with zero results included plus one-half of the maximum annual missed dose as 

listed in Table 1, and 2) the percentile dose with zero results excluded. 
Document No. ORAUT-OTIB-0032 Revision No. 00 Effective Date: 05/31/2005 Page 8 of 9

4. 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. 

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

SRS 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, they should not be applied for cases with estimated POCs >50% without first 

subtracting missed dose based on the information in Table 1 and Step 3 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

8.0 SRS COWORKER ANNUAL DOSE DISTRIBUTIONS

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 SRS,

2 and non-penetrating 

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

or other applicable considerations (or as <30 keV photons, if appropriate).

4

 

Reserved
Document No. ORAUT-OTIB-0032 Revision No. 00 Effective Date: 05/31/2005 Page 9 of 9

Table 2. Annual SRS 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%

1952 1.672 1.599 1.117 1.233 0.368 0.365

1953 1.774 1.354 1.082 2.391 1.239 0.284

1954 1.506 1.192 1.062 1.753 0.905 0.288

1955 2.994 1.885 1.087 2.609 1.716 0.297

1956 3.229 2.188 1.138 1.942 1.536 0.291

1957 3.469 2.548 1.085 1.407 0.995 0.261

1958 2.421 1.704 0.658 1.248 0.611 0.176

1959 2.727 1.836 0.689 2.321 1.665 0.314

1960 3.300 2.724 0.781 3.697 2.397 0.335

1961 2.665 2.101 0.654 6.347 3.271 0.290

1962 2.722 1.943 0.654 6.449 3.209 0.294

1963 2.937 2.168 0.637 7.283 3.091 0.283

1964 3.273 2.769 0.711 9.578 4.902 0.362

1965 2.846 2.277 0.413 8.617 4.568 0.289

1966 2.831 2.168 0.412 6.834 4.109 0.222

1967 2.897 2.443 0.429 6.285 3.191 0.264

1968 2.833 2.337 0.409 8.944 4.394 0.305

1969 2.776 2.350 0.463 7.659 4.341 0.288

1970 2.798 2.306 0.427 6.845 3.008 0.186

1971 2.609 1.925 0.411 5.483 2.152 0.183

1972 2.453 1.615 0.213 5.392 1.952 0.135

1973 2.413 1.504 0.182 5.254 1.810 0.106

1974 2.318 1.378 0.151 4.786 1.636 0.091

1975 1.775 1.093 0.137 3.236 1.255 0.096

1976 1.678 0.955 0.136 3.490 1.219 0.091

1977 1.719 0.940 0.137 3.149 1.140 0.091

1978 1.607 0.913 0.132 3.131 1.150 0.086

1979 1.601 0.905 0.122 3.271 0.889 0.092

1980 1.471 0.838 0.127 2.512 0.890 0.086

1981 1.391 0.800 0.127 2.987 1.159 0.092

1982 1.286 0.791 0.132 2.341 0.798 0.070

1983 1.239 0.739 0.128 2.531 0.845 0.082

1984 1.050 0.623 0.068 2.184 0.660 0.106

1985 1.001 0.559 0.062 1.634 0.577 0.101

1986 0.795 0.440 0.051 1.065 0.308 0.111

1987 0.780 0.425 0.047 0.994 0.285 0.123

1988 0.829 0.431 0.041 0.664 0.186 0.128

1989 0.702 0.354 0.050 0.713 0.220 0.117

1990 0.641 0.304 0.053 0.384 0.210 0.101

1991 0.397 0.193 0.030 0.265 0.092 0.090

1992 0.383 0.191 0.030 0.170 0.069 0.090

1993 0.328 0.193 0.030 0.102 0.039 0.090

1994 0.437 0.187 0.030 0.083 0.060 0.090

1995 0.491 0.260 0.030 0.130 0.062 0.090

1996 0.441 0.196 0.030 0.096 0.056 0.090

1997 0.419 0.206 0.030 0.223 0.097 0.090

1998 0.406 0.227 0.030 0.209 0.093 0.090

1999 0.276 0.161 0.030 0.243 0.115 0.090