ORAU TEAM 

Dose Reconstruction 

Project for NIOSH

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

Page 1 of 17

Document Title: 

External Coworker Dosimetry Data 

for the Rocky Flats Plant 

Document Number: ORAUT-OTIB-0058 

Revision: 01 

Effective Date: 01/08/2007 

Type of Document: OTIB 

Supersedes: Revision 00 

Subject Expert: Matthew H. Smith 

 

Approval: Signature on File Approval Date: 01/08/2007 

John M. Byrne, Document Owner 

Concurrence: Signature on File Concurrence Date: 01/08/2007 

Edward F. Maher, Task 5 Manager 

Concurrence: Signature on File Concurrence Date: 01/08/2007 

James P. Griffin, Deputy Project Director 

Approval: Brant A. Ulsh Signature on File for Approval Date: 01/08/2007 

James W. Neton, Associate Director for Science 

 New Total Rewrite Revision Page Change 

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

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION. 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 2 of 17 

PUBLICATION RECORD 

EFFECTIVE 

DATE 

REVISION 

NUMBER DESCRIPTION 

05/12/2006 00 New technical information bulletin to provide information to allow 

ORAU Team dose reconstructors to assign doses at the Rocky Flats 

Plant to certain workers who have no or limited monitoring data, 

based on site coworker data. First approved issue. Training 

required: As determined by the Task Manager. Initiated by Matthew 

H. Smith. 

01/08/2007 01 Approved Revision 01 due to the release of ORAUT-OTIB-0052 Rev 

00 and comments received from NIOSH. Constitutes a total rewrite 

of the document. Incorporates internal formal review comments. 

Incorporates NIOSH formal review comments and additional 

information found regarding neutron to photon ratios for the period 

1970-1976. Added Table 6-2. This revision results in an increase in 

assigned dose and a PER is required. Training required: As 

determined by the Task Manager. Initiated by Matthew H. Smith. 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 3 of 17 

TABLE OF CONTENTS 

SECTION TITLE PAGE

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

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

2.0 Purpose.......................................................................................................................................5

3.0 Background.................................................................................................................................5

4.0 General Approach.......................................................................................................................6

5.0 Applications and Limitations .......................................................................................................6

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

6.1 Adjustment for Missed Dose .......................................................................................... 7

6.2 Special Considerations .................................................................................................. 8

7.0 Coworker Annual Dose Summaries............................................................................................9

8.0 Supplemental Information about RFP Neutron-to-Photon Ratio Assumptions .........................16

8.1 Justification for Extrapolation of Neutron-to-Gamma Ratios from 

1959 to the 1952 to 1958 Period.................................................................................. 16

References ...........................................................................................................................................17

LIST OF TABLES 

TABLE TITLE PAGE

6-1 Missed external doses based on ORAUT-TKBS-0011-6............................................................7

6-2 RFP lognormal neutron-to-photon ratio values, 1970 to 1976 ....................................................8

7-1 Annual RFP external coworker doses (including NDRP data) modified to 

account for missed dose...........................................................................................................11

7-2 Annual RFP external coworker doses (including NDRP data and missed 

dose) modified to separate penetrating dose components.......................................................12

7-3 Annual RFP external coworker doses (excluding NDRP data) modified to 

account for missed dose...........................................................................................................13

7-4 Annual RFP external coworker doses (including NDRP data and missed 

dose) modified in accordance with ORAUT-OTIB-0052 ...........................................................13

7-5 Annual RFP external photon and neutron coworker doses (including 

NDRP data and missed dose) modified in accordance with ORAUT-OTIB0052..........................................................................................................................................14

7-6 Annual RFP external coworker doses (excluding NDRP data) modified in 

accordance with ORAUT-OTIB-0052........................................................................................15
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 4 of 17 

ACRONYMS AND ABBREVIATIONS 

DOE U.S. Department of Energy 

EEOICPA Energy Employees Occupational Illness Compensation Program Act of 2000 

GM geometric mean 

GSD geometric standard deviation 

HIS20 Health Information System 

IREP Interactive RadioEpidemiological Program 

keV kiloelectron-volt, 1,000 electron-volts 

LOD limit of detection 

mo month 

NDRP Neutron Dose Reconstruction Project 

NIOSH National Institute for Occupational Safety and Health 

NOCTS NIOSH-OCAS Claims Tracking System 

OCAS Office of Compensation Analysis and Support 

ORAU Oak Ridge Associated Universities 

ORNL Oak Ridge National Laboratory 

RFP Rocky Flats Plant 

TIB technical information bulletin 

TLD thermoluminescent dosimeter 

U.S.C. United States Code 

yr year 

§ section or sections 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 5 of 17 

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 

historic 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 [EEOICPA; 42 U.S.C. § 7384l(5) and (12)]. 

2.0 PURPOSE

The purpose of this TIB is to provide information to allow dose reconstructors to assign doses based 

on site coworker data to Rocky Flats Plant (RFP) 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. The 

data are to be used in conjunction with ORAUT-OTIB-0020, Use of Coworker Dosimetry Data for 

External Dose Assignment (ORAUT 2005a). 

3.0 BACKGROUND

The Oak Ridge Associated Universities (ORAU) Team is conducting 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 (ORAUT 2005a), some cases without complete monitoring data 

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

As described in ORAUT-TKBS-0011-6, Technical Basis Document for the Rocky Flats Plant – 

Occupational External Dosimetry (ORAUT 2004), operations at the site began in 1951. The RFP 

used a variety of film dosimeters between 1951 and 1969. In 1964, the dosimetry package was 

incorporated into the security badge, which better ensured that each worker wore a dosimeter 

(ORAUT 2004). A combination film and thermoluminescent dosimeter (TLD) was used starting in 

1970 until a TLD for both gamma and neutrons was implemented in 1971. Use of dosimetry at the 

RFP expanded as production operations increased. Exchange frequencies varied from quarterly to 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 6 of 17 

weekly depending on job duties. There does not appear to have been any significant administrative 

practice that would have jeopardized the integrity of the dose of record. 

4.0 GENERAL APPROACH

As described in ORAUT-OTIB-0020 (ORAUT 2005a), the general approach to the development of 

coworker data for cases without external monitoring data is to assign either 50th- or 95th-percentile 

doses with the intent that the assigned doses represent, but do not underestimate, the doses that 

would have been assigned had the worker been monitored. 

5.0 APPLICATIONS AND LIMITATIONS

Some RFP 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 TIBs for external 

coworker dosimetry data for all relevant sites. 

The data in this TIB address penetrating radiation from gamma and neutron radiation and 

nonpenetrating radiation from electron and/or low-energy photon radiation. Neutron data are not 

presented separately; methods for determining neutron dose are discussed in Section 7.0. ORAUTTKBS-0011-6 (ORAUT 2004) and the following two documents should be used as the basis for 

assigning neutron doses, when relevant: 

• ORAUT-OTIB-0050, Use of Rocky Flats Neutron Dose Reconstruction Project Data in Dose 

Reconstructions (ORAUT 2005b).

• ORISE 05-0199, Technical Basis Document for the Neutron Dose Reconstruction Project (Falk 

et al. 2005). 

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

6.0 COWORKER DATA DEVELOPMENT

Dosimetry data for monitored RFP workers in the Health Information System (HIS20) were selected 

for this evaluation. HIS20 was the last system used at the RFP for the retention of occupational 

radiation exposure data. The information in this system contains data that have been transferred from 

previous electronic systems and hard-copy health physics files. In addition, HIS20 contains the 

results of the Neutron Dose Reconstruction Project (NDRP) (Falk et al. 2005). 

The annual data for each worker reported between 1952 and 2005 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 6.2 for further discussion of special considerations). The data were 

prorated so coworker doses that represent 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 that were used for coworker dose development was confirmed by selecting a 

sampling of beta-gamma film badge worksheets (handwritten records) and comparing them to data for 

penetrating radiation listed in the HIS20 database. 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 7 of 17 

Each beta-gamma worksheet contains film badge results for numerous workers for a given building 

and quarter. For each worker-year, four sheets of quarterly data are combined to comprise the 

annual beta-gamma dose record. Thirty such worker-years were examined and compared to data for 

the same worker-year. 

Of the 30 worker-years compiled (which represent data for 30 individuals), 22 (73%) were complete in 

that all quarterly data were found and the total annual dose was in agreement. For 5 worker-years 

(17%), one-quarter of the beta-gamma worksheet data were not found, but the annual total calculated 

without that missing quarter agreed with the HIS20 database. For 3 worker-years (10%), some 

quarterly beta-gamma worksheet data were not found or were blank and the annual totals did not 

agree with the HIS20 database. In all three of those instances, the HIS20 database annual values 

were higher than the data from the beta-gamma worksheets. 

6.1 ADJUSTMENT FOR MISSED DOSE 

According to OCAS-IG-001, External Dose Reconstruction Implementation Guideline (NIOSH 2006), 

missed doses are assigned for reported zero readings for each monitoring cycle to account for the 

possibility that doses were received but either not recorded by the dosimeter or not reported by the 

site. In addition, reported dose values less than one-half the applicable minimum detection limits are 

assigned as missed dose. Annual maximum potential missed doses are calculated by multiplying the 

number of zero or unrecorded 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 to 

calculate the probability of causation, which is determined by the U.S. Department of Labor. Thus, in 

the Interactive RadioEpidemiological Program (IREP), Parameter 1 input is equal to the calculated 

maximum annual missed doses multiplied by 0.5, and the Parameter 2 input is equal to 1.52. These 

values represent the geometric mean (GM) and geometric standard deviation (GSD), respectively, for 

each year of analysis. 

The assignment of maximum potential missed doses for monitored workers is particularly significant 

for RFP workers from 1954 to 1962, when they could have been monitored weekly. Table 6-1 lists the 

maximum annual missed dose by monitoring period based on information in ORAUT-TKBS-0011-6 

(ORAUT 2004). 

Table 6-1. Missed external doses (rem) based on ORAUT-TKBS-0011-6 (ORAUT 2004). 

Monitoring 

period 

Penetrating 

LOD 

Nonpenetrating 

LODa Exchange 

frequency 

Maximum potential 

annual missed 

penetrating dose 

Maximum potential 

annual missed 

nonpenetrating dose

1952–1953 0.04 0.05 Semimonthlyb 0.960 1.200 

1954–1962 0.04 0.05 Weeklyb 2.080 2.600 

1963–1964 0.04 0.05 Semimonthlyb 0.960 1.200 

1965–1966 0.04 0.05 Monthlyb 0.480 0.600 

1967–1968 0.04 0.05 Semimonthlyb 0.960 1.200 

1969–1976 0.02 0.03 Semimonthlyb 0.480 0.720 

1977–1992 0.02 0.03 Monthlyc 0.240 0.360 

1993–2005 0.01 0.02 Monthlyc 0.120 0.240 

a. Based on analysis of nonpenetrating LODs for other DOE sites in ORAUT-OTIB-0017 (ORAUT 2005c). Specific RFP 

data for nonpenetrating LOD are not available at this time. 

b. Based on maximum potential exchange frequency in ORAUT-TKBS-0011-6 (ORAUT 2004). 

c. The exchange frequency was not defined in ORAUT-TKBS-0011-6 (ORAUT 2004). It is based on a review of claim data 

evaluated under the EEOICPA Subtitle B program. 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 8 of 17 

6.2 SPECIAL CONSIDERATIONS 

Certain aspects of the external dosimetry practices at the RFP that are documented in ORAUT-TKBS0011-6 (ORAUT 2004) were considered in the analysis of the site data. These include: 

• Conservatively determined default dosimeter exchange frequencies were used. Not all RFP 

employees would have had dosimetry exchanged at these upper-bound frequencies. 

• During the process of prorating HIS20 dose to account for partial years of employment, it was 

discovered that artificially short or long wear periods had been entered in the HIS20 database. 

These artificial periods were entered because only one date (usually the end date) was 

available in the electronic data from previous database systems. To avoid skewing the overall 

dataset with artificially high or low prorated dose, data with a wear period less than or equal to 

0.1 yr or greater than 1.25 yr were excluded from the analysis described in Section 7.0. 

• Inclusion of NDRP data in the HIS20 database led to the development of tables of data for 

penetrating and nonpenetrating dose that include and exclude the NDRP values. To 

determine neutron dose for the period from 1952 to 1969, neutron-to-photon ratios defined in 

the NDRP study (Falk et al. 2005) were used. Neutron-to-photon ratios for the period from 

1970 to 1976 are defined in this document (see Table 6-2). For 1977 to 2005, values from 

ORAUT-OTIB-0050 were used (ORAUT 2005b). 

Table 6-2. RFP lognormal neutron-to-photon ratio values, 1970 to 1976. 

Year 

Neutron-to-photon 

ratio GM 

(semimonthly 

exchange) GSD 

95th 

percentile 

Neutron-to-photon 

ratio GM (monthly 

exchange) GSD 

95th 

percentile

1970 1.61a 3.45 12.4 NA NA NA 

1971 1.61 3.45 12.4 NA NA NA 

1972 1.32 2.15 4.64 0.8 2.63 3.94 

1973 1.32b 2.15 4.64 NA NA NA 

1974 0.68 3.01 4.16 NA NA NA 

1975 0.67 3.31 4.82 NA NA NA 

1976 0.95 3.59 7.81 0.78 4.29 8.55 

a. Data for 1970 were not available. This value is the greater of the ratios for 1969 and 1971. The 

high neutron-to-gamma ratio in 1971 for Building 771 is reasonable from a process aspect, and 

extrapolating that ratio back to 1970 also is reasonable. In the aftermath of the 1969 plutonium fire 

in Buildings 776 and 777, the salvaged plutonium oxide had to be converted back to plutonium 

metal, a process done in Building 771. Building 771 had a huge backlog for relatively pure 

plutonium (little americium, low gamma) to be reprocessed, which was staged in the 776 to 771 

tunnel and any other possible staging area in the vicinity. In addition, PuF4 (a high-neutron source) 

seemed to be generated faster in Building 771 than it could be reduced to metal, which also caused 

a staging problem in or near the process areas in Building 771 until the backlog could be reduced. 

b. Data for 1973 were not available. This value is the greater of the ratios for 1972 and 1974.

• ORAUT-OTIB-0027 should be used to choose the proper method for processing penetrating 

and nonpenetrating data to determine low-energy (less-than-30-keV) photon dose or electron 

(greater-than-15-keV) dose components as needed (ORAUT 2005d). 

Neutron-to-photon ratio values for 1970 to 1976 were developed by analyzing records that contain 

dosimetry reports to supervisors. Data were available for workers on a semimonthly dosimeter 

exchange cycle for 1971, 1972, 1974, 1975, and 1976. Data for workers on a monthly exchange 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 9 of 17 

cycle were available for 1972 and 1976. Neutron-to-photon ratio values for the semimonthly 

exchange cycle were used in this document because: 

• A semimonthly exchange cycle was assumed for applying missed external dose for this period 

(see Table 6-1). 

• The neutron-to-photon ratio values for semimonthly exchange were equal to or greater than 

the monthly exchange values. 

Table 6-2 lists the neutron-to-photon ratios for this period. The individual ratios for available data 

were analyzed, and they fit lognormal distributions. 

As described in Section 7.0, an approach favorable to the claimant was adopted in the development 

of coworker dose summaries; this approach was intended to account for any underestimate of doses 

to radiological workers at the RFP based on these considerations. 

7.0 COWORKER ANNUAL DOSE SUMMARIES 

Based on the described information and approaches, RFP coworker annual external dosimetry 

summaries were developed for use in the evaluation of external penetrating and nonpenetrating dose 

for certain workers who were potentially exposed to workplace radiation, but for whom there is no or 

limited monitoring data from DOE. These summaries were developed using the following steps: 

Step 1. As described in Section 6.0, for data between 1952 and 2005, the reported penetrating dose, 

which represented annual summary data, was modified for each worker to account for partial 

years of employment. This adjustment was made by analyzing the dosimetry wear dates in 

the HIS20 database. For example, if the average employment period for all RFP employees 

in the NIOSH-Office of Compensation Analysis and Support (OCAS) Claims Tracking 

System (NOCTS) was 11 mo in a particular calendar year, the reported annual doses were 

multiplied by 12/11 (1.09). This permits the dose reconstructor to assign an appropriate 

prorated dose to account for partial years of employment or potential exposure. 

Step 2. One-half of the maximum potential annual missed doses listed in Table 6-1 were added to 

the reported annual doses from Step 1 (with the exception of reported positive doses, in 

which case the maximum missed dose was reduced by the dose that corresponded to one 

badge exchange because it is not possible that all individual badge results were zero if a 

positive annual dose was reported). 

Step 3. The 50th- and 95th-percentile annual coworker gamma doses were derived from the doses 

from Step 2 by ranking the data into cumulative probability curves and extracting the 50thand 95th-percentile doses for each year. 

Tables 7-1 and 7-2 list the results of the coworker analysis that include and exclude NDRP 

data, respectively. These percentile doses should be used for RFP workers with no or 

limited monitoring data through the use of the methodologies outlined in Section 7.0 of 

ORAUT-OTIB-0020 (ORAUT 2005a). In general, the 50th-percentile dose can be used as a 

best estimate of a worker’s dose when professional judgment indicates that the worker was 

probably exposed to intermittent low levels of external radiation. The 50th-percentile dose 

should generally not be used for workers who were routinely exposed. For routinely 

exposed workers (i.e., workers who were expected to have been monitored and routinely 

exposed), the 95th-percentile dose should be applied. However, other options are available 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 10 of 17 

through the guidance in ORAUT-OTIB-0020. For instance, for cases in which routine 

monitoring data exist and coworker dose is used to supplement missing quarters or years, 

the percentile dose should be the one that is consistent with the recorded doses unless there 

is reason to believe that the worker’s job or location differs significantly from that held during 

the years dose was recorded. For workers who are unlikely to have been exposed, external 

onsite ambient dose should be used rather than coworker doses. 

Step 4. Workers exposed to neutrons from work in plutonium facilities from 1952 to 1969 were, in 

general, included in the NDRP study. Therefore, the neutron and photon dose components 

for 1952 to 1969 were calculated by applying the neutron-to-gamma ratios (for “all other” 

facilities) from Table 11.1 of the NDRP report (Falk et al. 2005) to the penetrating dose 

values from HIS20. Neutron and gamma dose component values are listed in Table 7-3. 

The results for penetrating dose in Table 7-2 represent the gamma component of 

penetrating dose for 1952 to 1969 for workers who were not part of the NDRP study and did 

not work in RFP plutonium facilities (i.e., probably uranium workers). Neutron and gamma 

components of the penetrating dose for 1970 to 1976 were separated using the neutron-tophoton ratio values in Section 6.2 of this document. Neutron and gamma components of the 

penetrating dose for 1977 to 2005 were separated using the neutron-to-photon ratio values 

in ORAUT-OTIB-0050 (ORAUT 2005b). The NDRP data include an estimate of missed 

neutron dose (addressed as notional dose by the NDRP project); therefore, no adjustments 

are needed for missed neutron dose for 1952 to 1969. Similarly, for 1970 to 2005, missed 

neutron dose is accounted for when the applicable neutron-to-photon ratio is applied to the 

data in Table 7-1. Photon dose in Table 7-3 should be used for uranium workers from 1970 

to 2005. 

Step 5. In instances where nonpenetrating dose is considered for 1952 to 1969, Table 7-1 values 

should be used for workers at plutonium facilities (i.e., nonpenetrating dose is due to lowenergy photons). For workers at nonplutonium facilities (i.e., nonpenetrating dose is due to 

electrons), the nonpenetrating values in Table 7-2 should be used. 

Step 6. Tables 7-4, 7-5, and 7-6 list penetrating dose values (as described in the steps above) that 

have been adjusted using the guidance in Section 8.0 of ORAUT-OTIB-0052, Parameters to 

Consider When Processing Claims for Construction Trade Workers (ORAUT 2006b). This 

guidance is applicable for construction trade workers who meet the criteria in Section 3.0 of 

ORAUT (2006b). Because ORAUT-OTIB-0052 does not provide an adjustment factor for 

nonpenetrating dose, the guidance in Step 6 should be used to derive the nonpenetrating 

dose component for construction trade workers. 

Step 7. Tables 7-4, 7-5, and 7-6 list penetrating dose values (as described in the steps above) that 

have been adjusted using the guidance in Section 8.0 of ORAUT-OTIB-0052, Parameters to 

Consider When Processing Claims for Construction Trade Workers (ORAUT 2006b). This 

guidance is applicable for construction trade workers who meet the criteria in Section 3.0 of 

ORAUT (2006b). Because ORAUT-OTIB-0052 does not provide an adjustment factor for 

nonpenetrating dose, the guidance in Step 6 should be used to derive the nonpenetrating 

dose component for construction trade workers. 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 11 of 17 

Table 7-1. Annual RFP external coworker doses (including NDRP data) modified to 

account for missed dose (rem). 

Year 

Penetrating 

95th percentile 

Penetrating 

50th percentile 

Nonpenetrating 

95th percentile 

Nonpenetrating 

50th percentile 

Number of 

monitored workers

1952 5.018 2.505 5.133 2.620 42 

1953 4.190 0.751 4.553 0.892 319 

1954 3.233 1.095 3.600 1.361 353 

1955 4.411 1.165 5.266 1.431 529 

1956 4.461 1.135 5.617 1.415 781 

1957 5.136 1.177 6.004 1.454 918 

1958 6.015 1.253 7.553 1.584 1,062 

1959 7.186 1.581 8.002 1.908 1,063 

1960 7.121 1.293 7.728 1.645 1,284 

1961 7.850 1.527 8.201 1.923 1,638 

1962 6.523 1.542 7.062 1.828 2,003 

1963 5.955 0.940 6.232 1.104 2,176 

1964 4.875 0.648 5.012 0.799 2,834 

1965 3.533 0.511 3.663 0.598 2,826 

1966 4.767 0.592 4.976 0.679 2,888 

1967 4.379 0.627 4.735 0.761 2,902 

1968 3.276 0.578 3.591 0.714 3,101 

1969 2.702 0.327 2.919 0.450 3,471 

1970 2.301 0.307 2.460 0.423 3,308 

1971 1.938 0.384 2.096 0.500 3,398 

1972 1.853 0.377 1.995 0.494 3,282 

1973 1.697 0.380 1.848 0.497 3,020 

1974 1.881 0.497 2.047 0.612 2,687 

1975 1.329 0.401 1.525 0.516 2,489 

1976 0.826 0.248 1.030 0.364 2,424 

1977 0.589 0.122 0.699 0.177 3,740 

1978 0.698 0.120 0.830 0.180 4,176 

1979 0.906 0.122 1.074 0.180 3,893 

1980 0.743 0.120 0.889 0.168 3,752 

1981 0.853 0.110 1.008 0.180 4,060 

1982 0.990 0.121 1.174 0.166 4,851 

1983 1.212 0.134 1.440 0.193 5,360 

1984 1.204 0.141 1.551 0.200 5,673 

1985 1.302 0.142 1.584 0.203 6,140 

1986 1.365 0.183 1.860 0.301 4,942 

1987 1.510 0.259 2.265 0.457 2,583 

1988 1.236 0.199 1.614 0.373 2,778 

1989 0.550 0.115 0.733 0.180 5,296 

1990 0.288 0.130 0.435 0.201 3,369 

1991 0.337 0.154 0.471 0.228 5,641 

1992 0.267 0.150 0.421 0.235 5,831 

1993 0.207 0.080 0.296 0.150 5,313 

1994 0.179 0.084 0.242 0.142 4,839 

1995 0.200 0.080 0.275 0.137 4,130 

1996 0.274 0.105 0.357 0.168 3,454 

1997 0.352 0.085 0.420 0.145 3,718 

1998 0.275 0.073 0.337 0.130 3,470 

1999 0.192 0.072 0.256 0.127 3,655 

2000 0.164 0.060 0.224 0.120 3,576 

2001 0.160 0.060 0.223 0.120 3,443 

2002 0.157 0.060 0.215 0.120 3,502 

2003 0.127 0.060 0.194 0.120 3,373 

2004 0.097 0.060 0.164 0.120 2,758 

2005 0.175 0.071 0.234 0.129 955 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 12 of 17 

Table 7-2. Annual RFP external coworker doses (including NDRP data and missed 

dose) modified to separate penetrating dose components (rem). 

Year 

Photon 

95th percentile 

Photon 

50th percentile 

Neutron 

95th percentile 

Neutron 

50th percentile 

Number of 

monitored workers 

1952 2.532 1.390 2.486 1.115 42 

1953 2.155 0.592 2.034 0.159 319 

1954 2.026 1.054 1.207 0.041 353 

1955 2.561 1.086 1.850 0.079 529 

1956 2.584 1.072 1.877 0.063 781 

1957 2.891 1.091 2.245 0.086 918 

1958 3.290 1.126 2.724 0.127 1,062 

1959 3.823 1.275 3.363 0.306 1,063 

1960 3.199 1.117 3.922 0.175 1,284 

1961 3.459 1.201 4.391 0.326 1,638 

1962 2.687 1.178 3.835 0.364 2,003 

1963 2.125 0.606 3.830 0.335 2,176 

1964 1.564 0.507 3.312 0.141 2,834 

1965 1.964 0.373 1.569 0.138 2,826 

1966 3.251 0.468 1.516 0.124 2,888 

1967 2.909 0.565 1.470 0.063 2,902 

1968 1.740 0.514 1.536 0.064 3,101 

1969 1.219 0.269 1.483 0.058 3,471 

1970 0.882 0.118 1.420 0.190 3,308 

1971 0.743 0.147 1.196 0.237 3,398 

1972 0.799 0.163 1.054 0.215 3,282 

1973 0.731 0.164 0.966 0.216 3,020 

1974 1.119 0.296 0.761 0.201 2,687 

1975 0.796 0.240 0.533 0.161 2,489 

1976 0.424 0.127 0.402 0.121 2,424 

1977 0.415 0.086 0.174 0.036 3,740 

1978 0.492 0.085 0.207 0.035 4,176 

1979 0.638 0.086 0.268 0.036 3,893 

1980 0.523 0.085 0.220 0.035 3,752 

1981 0.600 0.077 0.252 0.033 4,060 

1982 0.697 0.085 0.293 0.036 4,851 

1983 0.854 0.094 0.359 0.040 5,360 

1984 0.848 0.100 0.356 0.042 5,673 

1985 0.917 0.100 0.385 0.042 6,140 

1986 0.961 0.129 0.404 0.054 4,942 

1987 1.063 0.182 0.447 0.077 2,583 

1988 0.870 0.140 0.366 0.059 2,778 

1989 0.388 0.081 0.163 0.034 5,296 

1990 0.203 0.091 0.085 0.038 3,369 

1991 0.237 0.108 0.100 0.045 5,641 

1992 0.188 0.105 0.079 0.044 5,831 

1993 0.146 0.056 0.061 0.024 5,313 

1994 0.126 0.059 0.053 0.025 4,839 

1995 0.141 0.056 0.059 0.024 4,130 

1996 0.193 0.074 0.081 0.031 3,454 

1997 0.248 0.060 0.104 0.025 3,718 

1998 0.193 0.051 0.081 0.022 3,470 

1999 0.136 0.050 0.057 0.021 3,655 

2000 0.115 0.042 0.048 0.018 3,576 

2001 0.112 0.042 0.047 0.018 3,443 

2002 0.110 0.042 0.046 0.018 3,502 

2003 0.089 0.042 0.038 0.018 3,373 

2004 0.068 0.042 0.029 0.018 2,758 

2005 0.123 0.050 0.052 0.021 955 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 13 of 17 

Table 7-3. Annual RFP external coworker doses (excluding NDRP data) modified to account for 

missed dose (rem). 

Year 

Penetrating 

95th percentile 

Penetrating 

50th percentile 

Nonpenetrating 

95th percentile 

Nonpenetrating 

50th percentile 

Number of 

monitored workers

1952 1.004 0.853 1.119 0.968 2 

1953 1.829 0.690 2.151 0.818 295 

1954 1.858 1.075 2.747 1.340 343 

1955 2.572 1.145 3.203 1.411 507 

1956 2.551 1.095 3.334 1.370 696 

1957 2.956 1.135 3.879 1.405 872 

1958 3.907 1.155 5.314 1.445 1,011 

1959 4.757 1.256 5.684 1.573 1,029 

1960 3.877 1.108 4.586 1.415 1,242 

1961 4.204 1.250 4.760 1.581 1,593 

1962 4.264 1.248 4.864 1.538 1,942 

1963 3.558 0.646 3.941 0.798 2,097 

1964 2.337 0.545 2.520 0.675 2,775 

1965 2.548 0.416 2.717 0.498 2,781 

1966 4.362 0.541 4.565 0.620 2,846 

1967 4.231 0.571 4.565 0.702 2,871 

1968 2.674 0.536 3.026 0.660 3,063 

1969 1.787 0.278 2.113 0.395 3,390 

Table 7-4. Annual RFP external coworker doses (including NDRP data and missed dose) 

modified in accordance with ORAUT-OTIB-0052 (rem) (ORAUT 2006b). 

Year 

Penetrating 

95th percentile 

Penetrating 

50th percentile 

Nonpenetrating 

95th percentile 

Nonpenetrating 

50th percentile 

Number of monitored 

workers 

1952 6.842 3.323 5.133 2.620 42 

1953 5.681 0.867 4.553 0.892 319 

1954 4.118 1.125 3.600 1.361 353 

1955 5.768 1.224 5.266 1.431 529 

1956 5.838 1.181 5.617 1.415 781 

1957 6.782 1.240 6.004 1.454 918 

1958 8.012 1.346 7.553 1.584 1,062 

1959 9.653 1.805 8.002 1.908 1,063 

1960 9.561 1.402 7.728 1.645 1,284 

1961 10.583 1.730 8.201 1.923 1,638 

1962 8.724 1.751 7.062 1.828 2,003 

1963 8.153 1.132 6.232 1.104 2,176 

1964 6.641 0.723 5.012 0.799 2,834 

1965 4.858 0.627 3.663 0.598 2,826 

1966 6.585 0.740 4.976 0.679 2,888 

1967 5.947 0.694 4.735 0.761 2,902 

1968 4.402 0.625 3.591 0.714 3,101 

1969 3.691 0.366 2.919 0.450 3,471 

1970 3.130 0.338 2.460 0.423 3,308 

1971 2.622 0.446 2.096 0.500 3,398 

1972 2.503 0.436 1.995 0.494 3,282 

1973 2.284 0.441 1.848 0.497 3,020 

1974 2.541 0.603 2.047 0.612 2,687 

1975 1.769 0.470 1.525 0.516 2,489 

1976 1.064 0.255 1.030 0.364 2,424 

1977 0.781 0.127 0.699 0.177 3,740 

1978 0.934 0.120 0.830 0.180 4,176 

1979 1.224 0.127 1.074 0.180 3,893 

1980 0.996 0.120 0.889 0.168 3,752 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 14 of 17 

Year 

Penetrating 

95th percentile 

Penetrating 

50th percentile 

Nonpenetrating 

95th percentile 

Nonpenetrating 

50th percentile 

Number of monitored 

workers 

1981 1.150 0.110 1.008 0.180 4,060 

1982 1.343 0.122 1.174 0.166 4,851 

1983 1.653 0.143 1.440 0.193 5,360 

1984 1.642 0.154 1.551 0.200 5,673 

1985 1.779 0.154 1.584 0.203 6,140 

1986 1.867 0.212 1.860 0.301 4,942 

1987 2.070 0.319 2.265 0.457 2,583 

1988 1.686 0.234 1.614 0.373 2,778 

1989 0.727 0.117 0.733 0.180 5,296 

1990 0.360 0.137 0.435 0.201 3,369 

1991 0.427 0.171 0.471 0.228 5,641 

1992 0.330 0.165 0.421 0.235 5,831 

1993 0.267 0.090 0.296 0.150 5,313 

1994 0.229 0.095 0.242 0.142 4,839 

1995 0.258 0.090 0.275 0.137 4,130 

1996 0.362 0.124 0.357 0.168 3,454 

1997 0.471 0.098 0.420 0.145 3,718 

1998 0.363 0.080 0.337 0.130 3,470 

1999 0.247 0.078 0.256 0.127 3,655 

2000 0.207 0.060 0.224 0.120 3,576 

2001 0.202 0.060 0.223 0.120 3,443 

2002 0.197 0.060 0.215 0.120 3,502 

2003 0.156 0.060 0.194 0.120 3,373 

2004 0.114 0.060 0.164 0.120 2,758 

2005 0.223 0.077 0.234 0.129 955 

Table 7-5. Annual RFP external photon and neutron coworker doses (including NDRP data and 

missed dose) modified in accordance with ORAUT-OTIB-0052 (rem)(ORAUT 2006b). 

Year 

Photon 

95th percentile 

Photon 

50th percentile 

Neutron 

95th percentile 

Neutron 

50th percentile 

Number of 

monitored workers 

1952 3.361 1.761 3.481 1.562 42 

1953 2.833 0.645 2.848 0.222 319 

1954 2.428 1.068 1.690 0.057 353 

1955 3.178 1.113 2.590 0.111 529 

1956 3.210 1.093 2.628 0.088 781 

1957 3.639 1.120 3.143 0.120 918 

1958 4.198 1.168 3.814 0.178 1,062 

1959 4.944 1.377 4.709 0.428 1,063 

1960 4.070 1.156 5.491 0.245 1,284 

1961 4.435 1.273 6.147 0.456 1,638 

1962 3.354 1.242 5.369 0.510 2,003 

1963 2.791 0.664 5.362 0.469 2,176 

1964 2.005 0.526 4.636 0.197 2,834 

1965 2.661 0.434 2.197 0.193 2,826 

1966 4.464 0.567 2.122 0.173 2,888 

1967 3.889 0.607 2.058 0.088 2,902 

1968 2.252 0.535 2.150 0.090 3,101 

1969 1.614 0.284 2.077 0.082 3,471 

1970 1.199 0.130 1.931 0.209 3,308 

1971 1.004 0.171 1.617 0.275 3,398 

1972 1.079 0.188 1.424 0.248 3,282 

1973 0.984 0.190 1.299 0.251 3,020 

1974 1.512 0.359 1.028 0.244 2,687 

1975 1.059 0.281 0.710 0.189 2,489 

1976 0.546 0.131 0.519 0.124 2,424 

1977 0.550 0.089 0.231 0.037 3,740 

1978 0.658 0.085 0.276 0.035 4,176 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 15 of 17 

Year 

Photon 

95th percentile 

Photon 

50th percentile 

Neutron 

95th percentile 

Neutron 

50th percentile 

Number of 

monitored workers 

1979 0.862 0.089 0.362 0.037 3,893 

1980 0.702 0.085 0.295 0.035 3,752 

1981 0.810 0.077 0.340 0.033 4,060 

1982 0.945 0.086 0.397 0.036 4,851 

1983 1.164 0.101 0.489 0.042 5,360 

1984 1.156 0.108 0.486 0.046 5,673 

1985 1.253 0.109 0.526 0.046 6,140 

1986 1.315 0.149 0.552 0.063 4,942 

1987 1.458 0.225 0.612 0.094 2,583 

1988 1.187 0.165 0.499 0.069 2,778 

1989 0.512 0.082 0.215 0.035 5,296 

1990 0.253 0.097 0.106 0.041 3,369 

1991 0.301 0.121 0.126 0.051 5,641 

1992 0.232 0.116 0.098 0.049 5,831 

1993 0.188 0.063 0.079 0.027 5,313 

1994 0.161 0.067 0.068 0.028 4,839 

1995 0.182 0.063 0.076 0.027 4,130 

1996 0.255 0.088 0.107 0.037 3,454 

1997 0.332 0.069 0.139 0.029 3,718 

1998 0.255 0.057 0.107 0.024 3,470 

1999 0.174 0.055 0.073 0.023 3,655 

2000 0.146 0.042 0.061 0.018 3,576 

2001 0.142 0.042 0.060 0.018 3,443 

2002 0.139 0.042 0.058 0.018 3,502 

2003 0.110 0.042 0.046 0.018 3,373 

2004 0.080 0.042 0.034 0.018 2,758 

2005 0.157 0.054 0.066 0.023 955 

Table 7-6. Annual RFP external coworker doses (excluding NDRP data) modified in accordance 

with ORAUT-OTIB-0052 (rem) (ORAUT 2006b). Data include missed dose. 

Year 

Penetrating 

95th percentile 

Penetrating 

50th percentile 

Nonpenetrating

95th percentile 

Nonpenetrating 

50th percentile 

Number of 

monitored workers

1952 1.222 1.010 1.119 0.968 2 

1953 2.376 0.781 2.151 0.818 295 

1954 2.193 1.097 2.747 1.340 343 

1955 3.193 1.195 3.203 1.411 507 

1956 3.164 1.125 3.334 1.370 696 

1957 3.731 1.181 3.879 1.405 872 

1958 5.061 1.210 5.314 1.445 1,011 

1959 6.252 1.350 5.684 1.573 1,029 

1960 5.020 1.143 4.586 1.415 1,242 

1961 5.478 1.341 4.760 1.581 1,593 

1962 5.561 1.339 4.864 1.538 1,942 

1963 4.798 0.720 3.941 0.798 2,097 

1964 3.088 0.579 2.520 0.675 2,775 

1965 3.480 0.494 2.717 0.498 2,781 

1966 6.019 0.669 4.565 0.620 2,846 

1967 5.740 0.616 4.565 0.702 2,871 

1968 3.559 0.566 3.026 0.660 3,063 

1969 2.410 0.297 2.113 0.395 3,390 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 16 of 17 

8.0 SUPPLEMENTAL INFORMATION ABOUT RFP NEUTRON-TO-PHOTON RATIO 

ASSUMPTIONS

8.1 JUSTIFICATION FOR EXTRAPOLATION OF NEUTRON-TO-GAMMA RATIOS FROM 

1959 TO THE 1952 TO 1958 PERIOD 

As stated in the NDRP Protocol, “the values for 1959 were used without modification, since no other 

information was available to justify modifying the value” (Falk et al. 2005, Section 11.4). Factors that 

could be expected to modify this ratio include: 

1. Changes in source material: The early shipments of plutonium material came from the 

Hanford Site and Oak Ridge National Laboratory (ORNL) in the form of plutonium nitrate 

(Putzier 1982; Kazanjian and Navratil 1984). The first shipment from Hanford was received in 

May 1953 (Putzier 1982). The only changes in the source material (plutonium) known to have 

occurred at RFP during the involved years were increases in batch size rather than changes in 

isotopic composition. Therefore, this factor is not expected to have changed the neutron-togamma ratio between 1953 and 1959. 

2. Changes in shielding configuration: Building 771 was constructed in 1952 and 1953 and 

received RFP’s first shipment of plutonium from Hanford in May 1953 (Putzier 1982). The first 

significant modification of this building occurred with the work on the americium recovery line 

from 1957 to 1963 and the commencement of significant americium recovery operations in 

1963 and 1964. The expansion in the Plant’s plutonium facilities began in the mid-1950s and 

culminated with Buildings 776 and 777 coming on line in 1957 and 1958. The first significant 

machining of plutonium began in these buildings in 1958. About 1963, a fast-cycle process 

was implemented in Room 114 of Building 771, with enhanced neutron shielding around the 

continuous fluorinator. There were no further significant changes to these buildings until a 

project in 1967 and 1968 added photon and neutron shielding on gloveboxes in plutonium 

processing areas. Therefore, this factor is not expected to have changed the neutron-togamma ratio between 1953 and 1959. 

3. Ingrowth of americium-241: The plutonium processed at RFP throughout the 1950s came 

from Hanford and ORNL and contained very little 241Am (Putzier 1982). This material was 

processed as it arrived and shipped off the site. In 1959, researchers at RFP modified a 

thiocyanate ion exchange process to handle gram quantities of americium; this provided the 

design basis for an americium recovery system that began significant operations in 1963 

(Beach and Navratil 1984). Therefore, this factor is not expected to have changed the 

neutron-to-gamma ratio between 1953 and 1959. 
Document No. ORAUT-OTIB-0058 Revision No. 01 Effective Date: 01/08/2007 Page 17 of 17 

REFERENCES 

Beach, L. J., and J. D. Navratil, 1984, “Americium Recovery and Purification,” Chapter 13, Actinide 

Processing at Rocky Flats, J. D. Navratil and F. J. Miner, editors, Rockwell International, 

Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 24798, p. 264] 

Falk, R. B., J. M. Aldritch, J. Follmer, N. M. Daugherty, D. E. Hilmas, and P. L. Chapman, 2005, 

Technical Basis Document for the Neutron Dose Reconstruction Project, Neutron Dose 

Reconstruction Protocol, ORISE 05-0199, Oak Ridge Institute of Science and Education, Oak 

Ridge, Tennessee, February 7. [SRDB Ref ID: 17126] 

Kazanjian, A. R., and J. D. Navratil, 1984, “Old Plutonium Recovery Facility,” Chapter 1, Actinide 

Processing at Rocky Flats, J. D. Navratil and F. J. Miner, editors, Rockwell International, 

Rocky Flats Plant, Golden, Colorado. [SRDB Ref ID: 24798, p. 11] 

NIOSH (National Institute for Occupational Safety and Health), 2006, External Dose Reconstruction 

Implementation Guideline, OCAS-IG-001, Rev. 2, Office of Compensation Analysis and 

Support, Cincinnati, Ohio, August 25. 

ORAUT (Oak Ridge Associated Universities Team), 2004, Technical Basis Document for Rocky Flats 

Plant – Occupational External Dosimetry, ORAUT-TKBS-0011-6, Rev. 00, Oak Ridge, 

Tennessee, January 20. 

ORAUT (Oak Ridge Associated Universities Team), 2005a, Use of Coworker Dosimetry Data for 

External Dose Assignment, ORAUT-OTIB-0020, Rev. 01, Oak Ridge Tennessee, October 7. 

ORAUT (Oak Ridge Associated Universities Team), 2005b, Use of Rocky Flats Neutron Dose 

Reconstruction Project Data in Dose Reconstructions, ORAUT-OTIB-0050, Rev. 00, Oak 

Ridge, Tennessee, December 13. 

ORAUT (Oak Ridge Associated Universities Team), 2005c, Interpretation of Dosimetry Data for 

Assignment of Shallow Dose, ORAUT-OTIB-0017, Rev. 01, Oak Ridge, Tennessee, 

October 11. 

ORAUT (Oak Ridge Associated Universities Team), 2005d, Supplementary External Dose Information 

for Rocky Flats Plant, ORAUT-OTIB-0027, Rev. 00, Oak Ridge, Tennessee, May 19. 

ORAUT (Oak Ridge Associated Universities Team), 2006a, Occupational On-Site Ambient Dose 

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

June 28. 

ORAUT (Oak Ridge Associated Universities Team), 2006b, Parameters to Consider When 

Processing Claims for Construction Trade Workers, ORAUT-OTIB-0052, Rev. 00, Oak Ridge, 

Tennessee, August 31. 

Putzier, E. A., 1982, “The Past 30 Years at Rocky Flats. - A Summary of Experiences and 

Observations at Rocky Flats Plant Over the Past 30 Years with Emphasis on Health and 

Safety.” Health Sciences Division. Repository Document HS-371.