Page 1 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

 

Follow-up Efforts on SEC-00192 

Rocky Flats Plant Tritium Issues

White Paper 

Rev. 1 

National Institute for Occupational 

Safety and Health 

May 30, 2014

J. S. Bogard, E. M. Brackett, Mutty Sharfi, and Dan Stempfley 

Oak Ridge Associated Universities Team

- 

Reviewed by Dr. James W. Neton and LaVon B. Rutherford, CHP 

Division of Compensation Analysis and Support
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 2 of 42 

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

 

 

INTRODUCTION

This is a summary of the initial and secondary tritium follow-up efforts performed by the 

National Institute for Occupational Safety and Health (NIOSH) Division of Compensation 

Analysis and Support (DCAS) and Oak Ridge Associated Universities Team (ORAUT) in 

support of the SEC-00192 Rocky Flats Plant (RFP) Special Exposure Cohort (SEC) Evaluation 

Report (ER) presented to the Advisory Board on Radiation and Worker Health (Advisory Board) 

in September 2012. 

As part of the initial follow-up, additional document data captures and personnel interviews were 

performed (classified and unclassified) to: (1) clarify the existence of tritium on site and 

associated personnel exposures; (2) expand the investigation on tritium bubbler sampling; (3) 

confirm the existence of shipping container tritium surveys; and (4) confirm the type and amount 

of sampling analysis performed in Building 123. These initial follow-up efforts were performed 

to validate the tritium bounding method for the SEC-00192 RFP ER (which uses information 

from the 1973 tritium incident as the maximum exposure scenario), and to provide more precise 

estimates of doses due to tritium.

NIOSH requested that ORAUT conduct a secondary follow-up effort and evaluate all available 

documentation/data in light of the additional information captured during the initial effort in 

order to: 

• analyze RFP occupational tritium exposures prior to 1973 (see Appendix 1 on 11) 

• determine the best approach for tritium dose assignments for 1973 and later (see Appendix 1) 

• provide an example tritium dose reconstruction using this approach (see Appendix 1) 

ORAUT was also asked to prepare responses to comments from the Advisory Board Work

Group and Sanford Cohen &Associates (SC&A) on the RFP Tritium White Paper (see 

Appendix 2 on page 35). 

INITIAL FOLLOW-UP

A review of all RFP-related Site Research Database (SRDB) documents was performed to 

determine if any documents existed in that dataset that could expand on any of the issues raised 

regarding tritium. The documents relating to tritium monitoring at RFP were identified, 

including some tritium bubbler results, and some indication of tritium contamination surveys. 

There are multiple documents regarding four significant incident-related tritium releases that 

occurred in 1968, 1973, 1974, and 1977 (SRDB Ref ID: 8265, 8790, 24164, 24165, 24167, 

110900, 110901, and 110903). There are also post-1977 documents that confirm continued 

monitoring of tritium releases and residual tritium as a result of these four earlier releases. 
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 3 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

There is also an SRDB document that provides information on post-1977 stack releases 

occurring in 1981 and 1986; both releases were considered small with no impact to site 

personnel or the immediate surrounding area (SRDB Ref ID: 110900). While some of the 

documents corroborated the classified interview issues addressed in the following sections of this 

white paper (i.e., bubblers and tritium contamination surveys), it does not appear that any of the 

new information supports the notion that there were any tritium levels that exceeded the 1973 

incident. Therefore, ORAUT finds no evidence disputing the use of the 1973 incident data as the 

bounding estimate for tritium at RFP, as presented in the SEC-00192 RFP ER.

As stated in the SEC-00192 ER, RFP operations that were related to, or had potential exposure 

impacts associated with tritium included neutron generator operations (i.e., the use of tritiated 

targets), and returned pit operations. Subsequent post-ER classified interviews identified 

shipping container handling as a potential exposure source. 

The following was learned:

• The follow-up effort corroborated in at least one interview (SRDB 122907) and in two 

documents (SRDB 118369; 117274) the point made in the SEC-00192 ER that the stainless 

steel reservoir operation was a construction operation before the introduction of tritium, 

which occurred at other sites. RFP was responsible constructing the reservoirs and shipping 

them to other locations where they were filled/used. 

• The follow-up effort corroborated that the neutron generator tritium target sources did not 

represent a source larger than the one represented in the 1973 tritium incident. 

• The tritium-contaminated pits and shipping containers are considered directly related because 

the shipping container tritium was a result of tritium from the pits loaded in the containers. 

Because of potential classification issues, the assessment of this issue will be addressed later 

in this document under the more general term Shipping Containers rather than the term Pits. 

• A follow-up effort was directed to determine if there are any other scenarios with the 

potential to exceed the SEC-00192 RFP ER bounding approach. These scenarios are being 

assessed as part of the pre-1973 tritium shipping container exposure evaluation (discussed 

later).

The indications found in the available documentation and provided by the majority of 

interviewees, was that RFP did not work with tritium as a normal or usual process, and therefore, 

did not expect it on site. The RFP radiological program did very little monitoring for tritium 

prior to the 1973 incident because they felt they had limited tritium exposure potential. Changes 

to the program related to tritium monitoring were implemented as a result of the 1973 incident. 

It has been corroborated that tritium bubbler monitoring did exist on site as part of the usual RFP 
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 4 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

air monitoring program before and after the 1973 tritium incident (SRDB 122907); however, the 

current information does not indicate how long before the 1973 incident bubblers existed on site. 

The available bubbler monitoring data is being evaluated for its applicability in dose 

reconstructions.

As indicated in the SEC-00192 ER, the site implemented a routine tritium bioassay program after 

the 1973 tritium incident, but discontinued the routine program in 1975 due to lack of positive 

bioassay results. The program was subsequently implemented on an as-needed or as-identified 

basis. This situation was corroborated in at least one personnel interview performed during this 

follow-up effort (SRDB 122907).

INITIAL FOLLOW-UP: TRITIUM BUBBLERS

Significant information on the bubbler monitors was discovered during the additional follow-up 

data capture efforts. There is some documentation in the SRDB that discusses the use of tritium 

bubblers. Based on the available data, including the most recent information (schematics and 

pictures of the tritium air sampling and monitoring equipment and processes [SRDB 122779 

through 122791]), there was a program that included the use of tritium bubblers to monitor 

enclosed and exhaust systems for tritium (SRDB 122466). As previously discussed, the exact 

start date for the use of bubblers has not been confirmed, but they did exist on site before the 

1973 incident (SRDB 122907). Most individuals interviewed were not well-informed on bubbler 

use or operation.

The SRDB contains some tritium bubbler results (SRDB 111095 and 122712) as well as detailed 

schematics and pictures of the units (SRDB Ref ID’s: 122691, 122692, 122693, 122787, 122788, 

122789, and 122790). Based on these results, information discovered during the follow-up 

research, and the interviews there is nothing to support the occurrence of a release event more 

significant than the 1973 incident. 

Table 1 beginning on the next page presents a summary of the Rocky Flats tritium bubbler 

information contained in the SRDB.

(continued)
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 5 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table 1: Rocky Flats Tritium Bubbler Information in the SRDB (on pages 5-7)

SRDB 

Ref ID

Year File Description Comments

Category: Tritium Monitoring Results, Procedures, and Occurrences

17824 1990-

1991 Occurrence reports

Contains two occurrence reports involving inoperable bubblers, 

and one report of a Triton tritium air monitor that was shut off. 

None of the occurrences involved tritium releases.

24164 1976-

1983

Tritium inventories and

effluents

Contains: an evaluation of tritium-release potential from a 

proposed neutron crate counter (1983); elevated tritium effluents 

from Bldg 776/777 (January 1981); estimated inventory of tritium 

as surface contamination in glove boxes, ducts, and exhaust 

plenums in Bldg 776/777 (1980); evaluation of ethylene glycol in 

place of water in tritium bubblers (1978); special study of tritium 

in ambient air (1976); a report, “Estimates of Maximum Tritium 

Releases to the Atmosphere from Operations at the Rocky Flats 

Plant” (1976); and a Call Report indicating that 0.058 μCi of 

tritium would probably be vented to the atmosphere for an 

experiment on May 20, 1974.

24307 1986

Procedure for effluent 

and room air tritium 

sampling

Operating procedure

111095 1977-

1981

Tritium bubbler 

sampling results

Log of analytical results for bubblers in operating areas, including 

room air and near downdraft tables. Most results are <100 pCi/m3, 

but results exceed 1,000 pCi/m3 on several occasions in Bldg 559

- Rm 102, and in Bldg 881- Rm 283. Highest result appears to be 

89,230 pCi/m3 in Bldg 771 for the period May 11-18, 1978.

122466 2013 Documented interview 

with [Name redacted]

Includes a discussion of the different laboratories at Rocky Flats 

for analyzing tritium and other radionuclides in samples.

122712 1998 Lab report - tritium 

activity in bubblers

Detailed analytical report from Thermo NUtech, including sample 

activity, counting uncertainty, detection limit, and total propagated 

uncertainty.

122907;

24167 2013

Documented interview 

with [Name redacted]; 

1973 incident report

Includes a discussion of the tritiated targets for laser fusion 

experiments and corroboration that bubblers were in use at several 

Rocky Flats locations prior to the 1973 tritium release incident.

Category: Tritium Sampler Photos and Design Documents

122691 1973 Photos – tritium 

operations at Dow

Relevance of photos to tritium monitoring or tritium operations is 

not apparent, except for one photo of a Triton tritium monitor.

122692 1977 Photos - tritium 

monitoring

Good photos of sampling fixture for sealed cans and drums, Triton 

Model 955B tritium monitor, and bubblers mounted outside a 

glove box for sampling glove box air.
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 6 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table 1: Rocky Flats Tritium Bubbler Information in the SRDB (on pages 5-7)

SRDB 

Ref ID

Year File Description Comments

122693 1983 Photos – tritium air 

sampling station

Labeled tritium sampling assembly showing building number, air 

flow rates, and water volume.

122779 1974

Drawing 1 of 8 - Tritium 

and iodine sampler 

assembly

Engineering drawing

122780 1974

Drawing 2 of 8 - Tritium 

and iodine sampler 

assembly

Engineering drawing

122781 1974

Drawing - Environmental

tritium and radioiodine 

sampler details

Engineering drawing

122782 1974

Drawing - Environmental

tritium and radioiodine 

sampler wiring diagram

Engineering drawing

122783 1974

Drawing - Environmental 

tritium and radioiodine 

sampler mounting detail

Engineering drawing

122784 1974

Drawing - Environmental 

tritium and radioiodine 

sampler onsite electrical 

hookup

Engineering drawing

122785 1974

Drawing - Environmental

tritium and radioiodine 

sampler offsite electrical 

hookup

Engineering drawing

122786 1974

Drawing - Environmental

tritium and radioiodine 

sampler onsite and 

offsite electrical hookup

Engineering drawing

122787 1978 Drawing – Tritium 

detector assembly Engineering drawing

122788 1978 Drawing – Tritium 

detector details (1) Engineering drawing

122789 1978 Drawing – Tritium 

detector details (2) Engineering drawing
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 7 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table 1: Rocky Flats Tritium Bubbler Information in the SRDB (on pages 5-7)

SRDB 

Ref ID

Year File Description Comments

122790 1978 Drawing – Tritium 

detector details (3) Engineering drawing

122791 1978 Drawing - Tritium 

detector flow diagram Engineering drawing

INITIAL FOLLOW-UP: SHIPPING CONTAINER TRITIUM SURVEYS

As part of the follow-up, additional research was performed regarding the issue of tritium 

contamination in shipping containers. This issue arose from one of the classified interviews 

(SRDB 122516). Tritium contamination in shipping containers was corroborated in an SRDB 

document (SRDB Ref ID: 111301); however, no actual contamination surveys have been found. 

The follow-up survey requirements and processes were corroborated in a follow-up interview in 

which the interviewee discussed implementing the shipping container tritium survey program in 

response to the 1973 incident (SRDB 122907). During that interview, the interviewee said that 

no tritium contamination was ever found. Other classified interviewees indicated that they had 

heard about shipping-container contamination, but they had no direct experience of it. A worstcase situation analysis of potential shipping-container contamination levels has been performed 

for comparison with the SEC-00192 ER bounding analysis in order to validate the ER’s 

bounding exposure scenario and to provide a more precise estimate for tritium dose prior to 

1973. This analysis is provided in Appendix 1.

INITIAL FOLLOW-UP: SAMPLE ANALYSIS IN BUILDING 123

Analytical capability existed in both the production areas and in Building 123 (SRDB 122625), 

which housed the laboratories supporting worker health and safety (Industrial Hygiene and 

Health Physics) as well as the environmental programs (SRDB 122627). Samples collected in 

the production areas may have been analyzed either in the production laboratories or in Building 

123, depending on the anticipated level of analytes and the potential for contamination with 

plutonium or uranium, for which strong contamination-control practices were in place. Tritium 

samples from stack exhausts, which were filtered several times before sampling and release to 

the environment, were typically analyzed in Building 123. Samples collected in the work areas 

were analyzed in a production area laboratory to eliminate the possibility of introducing 

plutonium contamination into the Building 123 lab (SRDB 122627). Samples with a high 

likelihood of elevated tritium content might also be analyzed in a production lab to prevent 

tritium contamination in the low-level Building 123 laboratories (SRDB 122624). 
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 8 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Some effort was made prior to 1973 to use commercially-available tritium monitoring equipment 

(e.g., the vibrating reed spectrometer and tritium sniffers) (SRDB 110885; 122623; 122670; 

122671) or to develop an in-house capability (through development of specialized ion chambers 

or tritium concentration techniques, such as silica gel traps [SRDB 24648; 24680]). Liquid 

scintillation counting was reportedly used for quantitative analysis of a variety of radioactive 

materials in the production areas; it quickly became the technique of choice for tritium sample 

analysis after the 1973 environmental tritium release. Tritium sniffers continued to be used to 

indicate elevated tritium in the workplace, but they did not provide quantitative data of record.

No results for tritium samples analyzed in the production areas have been captured, and only 

limited data are available from the Building 123 laboratories. ORAUT’s understanding of the 

criteria for determining where tritium samples were analyzed comes solely from interviews with 

former Rocky Flats Plant employees.

INITIAL FOLLOW-UP: CONCLUSION

The additional documents and interviews obtained during the post-ER follow-up efforts provide 

additional evidence of the potential for tritium exposures. However, the information also 

supports the case that estimates of potential tritium exposure that could have occurred prior to 

1973 are bounded by the exposure estimate for the 1973 event, and that more precise estimates 

are feasible.

Table 2 on the next page lists the follow-up actions performed in support of SEC-00192. 

Table 3 on page 10 lists the follow-up interviews performed in support of SEC-00192.

SECONDARY FOLLOW-UP: APPENDICES 1 AND 2

In light of the additional information and data gathered during the follow-up effort, NIOSH 

requested that ORAUT evaluate the available documentation and data to: (1) analyze RFP 

tritium exposures for 1959-1973; (2) determine the best approach for dose assignment for 1973 

and later; and then (3) produce an example tritium dose reconstruction employing the best 

approach determined in the analysis. The results of this assessment are provided in Appendix 1. 

NIOSH also asked ORAUT to prepare responses to comments from the Board Working Group 

and SC&A on the RFP Tritium White Paper. These responses are provided in Appendix 2.

(continued)
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 9 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table 2: Initial and Secondary Follow-up Actions Performed in Support of SEC-00192

Date Activity Locationa

Initial Follow-Up Actions

10/03/2012 Secure Discussions NIOSH (Cincinnati OH)

10/28/2012 Data Capture LANL (Los Alamos NM)

11/06/2012 

through 

11/07/2012

Eleven secure interviews with former RFP employees

(see Table 3) DOE-EMCBC (Denver CO)

01/15/2013 

through 

01/31/2013

Eight follow-up telephone interviews with former RFP 

employees (see Table 3) Employee homes via telephone

02/03/2013 Data Capture DOE-LM (Westminster CO)

EMCBC (Denver CO)

02/22/2013 Data Capture OSTI (Oak Ridge)

02/25/2013 Secure Discussions NIOSH (Cincinnati OH)

Secondary Follow-Up Actions

05/30/2013 Reconstructing Rocky Flats Tritium Doses Pre- and Post1973 (see Appendix 1) ORAUT (Cincinnati OH)

03/06/2014 Response to WG/SC&A Comments on the RFP Tritium 

White Paper (see Appendix 2)

NIOSH (Cincinnati OH); prepared 

by ORAUT (Cincinnati OH)

a

DOE-EMCBC (Denver), LANL (Los Alamos), and OSTI (Oak Ridge) are sites where reviews of classified material were 

performed. Secure interviews were conducted at DOE-EMCBC.

(continued)
White Paper Follow-up Efforts on SEC-00192 Rocky Flats Plant Tritium Issues (Rev. 1) May 30, 2014

Page 10 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table 3: Follow-up Interviews Performed in Support of SEC-00192

Site Interview Topic Interview Date SRDB Ref ID

Rocky Flats, SEC-00192 Tritium (DFC)* 11/6/2012 122515

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122553

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122666

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122667

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122668

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122551

Rocky Flats, SEC-00192 Tritium (DFC) 11/6/2012 122550

Rocky Flats, SEC-00192 Tritium (DFC) 11/7/2012 122517

Rocky Flats, SEC-00192 Tritium (DFC) 11/7/2012 122516

Rocky Flats, SEC-00192 Tritium (DFC) 11/7/2012 122669

Rocky Flats, SEC-00192 Tritium Building 123 1/15/2013 122627

Rocky Flats, SEC-00192 Tritium Building 123 1/15/2013 122628

Rocky Flats, SEC-00192 Tritium Building 123 1/16/2013 122624

Rocky Flats, SEC-00192 Tritium Building 123 1/18/2013 122625

Rocky Flats, SEC-00192 Tritium Building 123 1/22/2013 122629

Rocky Flats, SEC-00192 Tritium Building 123 1/22/2013 122623

Rocky Flats, SEC-00192 Tritium Building 123 1/23/2013 122626

Rocky Flats, SEC-00192 Tritium Building 123 1/31/2013 122670

Rocky Flats, SEC-00192 Tritium Building 123 1/31/2013 122671

* DFC = Denver Federal Center where secure interviews regarding tritium were conducted.
Page 11 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Appendix 1: Reconstructing Rocky Flats 

Tritium Doses Pre- and Post-1973

J. S. Bogard, E. M. Brackett, and Mutty Sharfi, ORAUT

Introduction

The potential for tritium exposure to Rocky Flats personnel was not considered significant until 

an unexpected release occurred in April 1973. Because tritium monitoring was not rigorous 

before this event, NIOSH requested that ORAUT perform a follow-up effort to validate the 

tritium bounding method for the SEC-00192 RFP ER, which uses information from the 1973 

tritium incident as the maximum exposure scenario. ORAUT conducted additional document 

data captures and personnel interviews regarding the existence of tritium on site and associated 

personnel exposures as well as follow-up on tritium bubbler sampling, shipping container tritium 

surveys, and sampling analysis performed in Building 123.

In light of the additional information and data gathered during the follow-up effort, NIOSH 

requested that ORAUT evaluate the available documentation and data to: (1) analyze RFP 

tritium exposures for 1959-1973; (2) determine the best approach for dose assignment for 1973 

and later; and then (3) produce an example tritium dose reconstruction employing the best 

approach determined in this analysis. This white paper presents the results of these three efforts:

• PART I: Analysis of Rocky Flats Tritium Exposures for 1959-1973 by J. S. Bogard

• PART II: Rocky Flats Tritium Dose Assignment for 1973 and Later by E. M. Brackett

- Attachment A: Rocky Flats 1973 H-3 Dose Assignment by E. M. Brackett

• PART III: Example RFP Tritium Dose Reconstruction by Mutty Sharfi
Page 12 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

PART I: Analysis of Rocky Flats Plant 

Tritium Exposures for 1959-1973

J. S. Bogard, ORAUT

Tritium Monitoring Data Prior to 1973

Although tritium was used as a boost gas in weapons and as target material in neutron 

generators, it was not processed or handled in any significant quantities at Rocky Flats. Tritium 

was monitored in the environment around the site for a time, but that monitoring ceased and was 

left to the State of Colorado for a brief period preceding an environmental release that occurred 

in April 1973. No analytical records have been captured by NIOSH that might help establish the 

Rocky Flats workplace tritium environment prior to that time.

The management of Rocky Flats woke abruptly to the potential for tritium workplace and 

environmental contamination with the release in April 1973 of 500 Ci - 2,000 Ci of tritium, 

primarily from Building 779A, and its eventual detection in waters draining into a reservoir

serving as a municipal drinking water supply (SRDB Ref ID: 110941; 111269; 111284). The 

release also resulted in tritium exposure to a small number of Rocky Flats personnel. Subsequent 

workplace monitoring and personnel bioassay was implemented, in part to establish the baseline 

tritium environment against which future incidents could be evaluated. A smaller and lessimpactful tritium release occurred in September 1974 from Building 777; the subsequent

investigation report (SRDB Ref ID: 8790) includes release details along with summaries of 

tritium workplace monitoring results prior to the incident for comparison. These data provide 

the basis for a model for bounding chronic tritium exposures to workers and of smaller, lessnotable tritium releases that might have occurred prior to 1973.

Several factors single out the 1973 tritium release as bounding for the entire history of Rocky 

Flats operations. These factors include the large quantity of tritium involved, the chemical form 

of the released tritium, and the meteorological conditions at the time of the release. Other 

documented releases involved smaller quantities of elemental tritium, having a much smaller 

dose conversion factor than the tritium oxide released in 1973. Bounds for personnel tritium 

exposures after the 1973 release can be developed based on measurement results, since personnel 

bioassay, air sampling, and workplace contamination monitoring for tritium became more 

common after that release. There are only very limited tritium measurement results prior to 1973

because tritium was not perceived as a radionuclide of occupational or environmental interest at 

Rocky Flats. Bounding tritium exposures for the pre-1973 period are more difficult to develop 

as a result of this lack of measurement data.
Page 13 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

According to the ChemRisk report (SRDB 8017), there was no environmental monitoring for 

tritium prior to 1970, and little in the way of workplace monitoring until after the 1973 tritium 

release; therefore, evidence of tritium releases prior to 1973 is primarily anecdotal. A 600-Ci 

release of elemental tritium (from a different source than the 1973 release) occurred in 1968. 

The ChemRisk report said the following with regard to possible releases from tritiated Pu 

shipments (SRDB 8017, pdf p. 285):

The 1973 findings associated with the tritiated plutonium initiated an investigation of other 

possible similar shipments and processing of tritiated plutonium. The investigation 

discovered three other shipments with maximum estimated tritium releases of 57 Ci (April 

1969), 40 Ci (March 1971), and 29 Ci (November 1971).

The reported investigation and the documented 1968 release of elemental tritium are the only 

sources of information about other possible releases. The 1968 release was elemental tritium

with no significant environmental or personnel exposure. None of the three identified potential 

releases from tritiated Pu was near the magnitude of the 1973 release. There is no evidence of a 

tritium release comparable to the magnitude and impact of the 1973 release prior to that year.

Source of Data for the pre-1973 Period

Despite the lack of measurement data, it is possible to develop pre-1973 tritium exposure bounds 

based on measurement results provided in a Rocky Flats Area Office (RFAO) report issued 

subsequent to a tritium release in one of the Rocky Flats production buildings on August 30, 

1974 (SRDB Ref ID: 8790). The information contained in this report includes measurement data 

(i.e., results from air samples, surface contamination surveys, and bioassay) from the production 

area where the release occurred as well as comparison data from other areas prior to, during, and 

after the release. Several factors support the use of these data as surrogates for bounding the 

tritium environment at Rocky Flats prior to 1973:

1. Background tritium levels immediately prior to the incident described in the RFAO report, 

although undoubtedly elevated since the more significant 1973 release, were well below 

dosimetrically-significant values and can be considered as fairly representative of typical

background levels for this analysis. The background tritium levels monitored in the months 

prior to the 1974 incident are consistent with internal radiation doses from tritium of well 

under 1 mrem annually. They are dosimetrically insignificant in this sense.

2. The quantity of tritium released (1.5 Ci) was significantly less than that released in 1973, and 

is probably more typical of potential undocumented releases in work areas – particularly 

those resulting from opening contaminated shipping containers.

The 1974 1.5-Ci tritium release is the only documented release from a shipping container in 

the Rocky Flats workplace. It is taken to be typical since there are no other such documented 
Page 14 of 42

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

releases to use in forming the model. There is documented concern about tritium releases, as 

shown in the following quote from the ChemRisk report (SDRB 8017, pdf p. 38):

As early as 1962, Rocky Flats maintained instruments for detection of tritium gas in 

particular work areas of the plant because operations have sometimes resulted in the 

storage of tritium containers.

The instruments available to Rocky Flats at that time were only semi-quantitative for 

indicating the presence of tritium; NIOSH has captured no records of these results.

Because NIOSH has only identified six documented releases from 1968-1974 (an average of 

1 per year), the application of a daily release would be a significant/bounding overestimate of 

the number of RFP tritium releases.

3. Tritium was released to the workplace environment, and not in a glovebox.

4. The release involved elemental tritium (HT, T2), and not tritium oxide (HTO)1

.

5. The tritium was released from a contaminated shipping container which was procured by 

Rocky Flats in 1970 and can be taken as representative of shipping containers in use prior to 

1973.

As stated in the response to Item 2, the 1974 1.5-Ci tritium release is the only documented

release from a shipping container in the Rocky Flats workplace. It is taken to be typical since 

there are no other such documented releases to use in forming the model. There is 

documented concern about such releases, as shown in the following quote from the 

ChemRisk report (SDRB 8017, pdf p. 38):

As early as 1962, Rocky Flats maintained instruments for detection of tritium gas in 

particular work areas of the plant because operations have sometimes resulted in the 

storage of tritium containers.

The instruments available to Rocky Flats at that time were only semi-quantitative for 

indicating the presence of tritium; NIOSH has captured no records of these results.

Because NIOSH has only identified six documented releases from 1968-1974 (an average of 

1 per year), the application of a daily release would be a significant/bounding overestimate of 

the number of RFP tritium releases.

 1 The impact of the 1973 tritium release was largely due both to the quantity (500 Ci – 2,000 Ci) and the chemical form (HTO) of 

the material. The presence of tritium oxide in the 1973 release resulted from peculiarities of the plutonium recovery operation 

from which it was generated. There is no indication that any other tritium release at Rocky Flats involved the oxide. Tritium in its 

elemental form (HT, T2) is far more likely to have been a contaminant at Rocky Flats because of the nature of its possible source 

terms – tritiated accelerator targets (neutron generators), plutonium hydride in recovery operations, and boost gas in returned 

reservoirs or pits.
Page 15 of 42

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

6. The incident occurred close enough in time to the 1973 tritium release that work practices 

and controls were likely more similar to those prior to 1973 than to those even a year or two 

later, as procedures and controls evolved with greater sensitivity to the potential for tritium 

contamination.

The RFAO report provides the best source of monitoring data for use in bounding both chronic 

and accidental tritium exposures to Rocky Flats personnel prior to the unique circumstances of 

the 1973 release. The RFAO report states that elevated tritium concentrations were detected in

air samples from Room 452 (Special Assembly Area) in Building 777 and from the Building 205 

exhaust plenum servicing Building 776/777 over the period of August 29 – September 4, 1974 

(SRDB Ref ID: 8790, pdf p. 9). Subsequent sampling and investigation of the elevated sample 

results concluded that about 1.5 Ci of tritium was released from the exhaust system of Room 

452, Building 777, when a shipping container (referred to as a “pressure cooker”) received in 

July 1974 from Battelle Pacific Northwest Laboratory (BNW) was opened on a downdraft table 

in Room 452 on August 30 (SRDB Ref ID: 8790, pdf pp. 36-39). No elevated environmental 

tritium levels were detected as a result of the incident, but workplace tritium levels seven times 

the applicable Radiological Control Guide were detected in air samples collected on August 30 

in Room 452 adjacent to the downdraft table, with average concentrations for the work week 

about 1.5 times the guidelines. Table A-1 below shows the reported values.

Table A-1: Reported Tritium Air Concentrations (μCi/m3) from the August 30, 1974 Release

Sampling Reference Plenum 205, Bldg. 776/777a Room 452, Bldg. 777

Normal Concentrations <1×10-2 <1×10-2

August 29-30, 1974 0.148 37.7

September 3-4, 1974 2.51 1.1

Source: SRDB 8790, pdf pp. 93-96

a

The Special Assembly Glovebox Line in Room 452, Building 777, was normally served by Plenum 206, but exhaust air from this area was 

vented through Plenum 205 from February 11 – August 7, 1974, while a new Plenum 206 was constructed. A tritium air sampler for Plenum 206 

was installed on August 30, 1974, but showed no elevated results. However, both Plenums 205 and Plenum 206 showed elevated tritium 

removable contamination (SRDB 8790, pdf pp. 74-82).

An air sampler located near the downdraft table in Room 452 indicated a tritium air 

concentration of 4.9×10-3 μCi/m3 on August 29 and 37.7 μCi/m3 on August 30. The applicable 

Radioactive Concentration Guideline at the time was 5 μCi/m3

. Two “pressure cookers” were 

opened at the downdraft table, coincident with the elevated tritium-in-air measurements, and 

were smear-sampled for removable tritium contamination. One cooker showed smear levels of 
Page 16 of 42

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

1.16×10-2 μCi; the other showed 3.43×102 μCi and was presumed to be the source of the gaseous 

tritium release.

Air Sample Results

Results from air samples collected daily in Room 452, Building 777, are available from June 3 to 

September 11, 1974. The air sampler was located near the downdraft table entry to the Special 

Assembly Line where the tritium contaminated “pressure cooker” was opened and was the only 

tritium air sampler in Building 777 at the time. Room air samples were collected in a water 

bubbler during the day shift (approximately 6 or 8 hours sampling time) at an air flow rate of 

2 L/min. Individual results are shown in Table A-2 below (SRDB: 8790, pdf pp. 87-89).

Table A-2: Tritium Activity Concentrations in Room Air: Rm. 452 - Special Assembly-Bldg. 777

Analysis Date 

(1974)

[

3

H] 

(pCi/m3)

Analysis Date 

(1974)

[

3

H] 

(pCi/m3)

Analysis Date 

(1974) [

3

H] (pCi/m3)

3-Jun 9,428 8-Jul 3,872 8-Aug 628

5-Jun 12,121 5-Jul 3,030 12-Aug 1,256

4-Jun 20,370 3-Jul 4,655 13-Aug 1,301

7-Jan 5,892 10-Jul 2,602 16-Aug --

6-Jun 16,498 9-Jul 2,512 20-Aug 2,439

14-Jun 5,387 11-Jul 4,553 21-Aug 3,140

13-Jun 4,553 17-Jul 21,022 22-Aug 3,298

12-Jun 12,358 16-Jul 5,040 23-Aug --

11-Jun 13,972 15-Jul 6,742 26-Aug 2,927

11-Jun 10,894 19-Jul 5,041 27-Aug 3,089

21-Jun 4,348 18-Jul 4,209 28-Aug 4,874

20-Jun 4,553 24-Jul 1,010 29-Aug 3,986

19-Jun 4,414 23-Jul 4,866 30-Aug 37,676,609

18-Jun 5,781 22-Jul 4,866 3-Sep 1,098,901

17-Jun 6,829 29-Jul 2,512 4-Sep 8,477

26-Jun 4,519 26-Jul 2,118 5-Sep 5,108

25-Jun -- 25-Jul 3,089 6-Sep --

24-Jun -- 1-Aug 1,842 9-Sep 3,030

2-Jul 3,454 30-Jul 1,727 10-Sep 3,140

1-Jul 4,348 1-Aug 2,269 11-Sep 2,898

27-Jun 5,366 7-Aug 1,179

27-Jun 4,553 5-Aug 2,512

Source: SRDB: 8790, pdf pp. 87-89
Page 17 of 42

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

The average and standard deviation of daily air sample results prior to August 30, the day of the 

tritium release from the contaminated shipping container, are (5343 ± 4518) pCi/m3

. The result 

on August 30 is 37,676,609 pCi/m3, and the sample taken on September 3 indicated a tritium 

concentration in the room air of 1,098,901 pCi/m3. However, the September 3 result is suspect 

because the sample was collected in the same vessel that was used on August 30 and which had

not been cleaned. Smear surveys of Room 452 on September 3 failed to show significant tritium 

contamination (SRDB: 8790, pdf pp. 37-38). Tritium levels in Building 777 were known to be

somewhat elevated over normal background because of residual contamination present since the 

1973 tritium release. 

Bioassay Results

The practice of pulling a sample of air from within shipping containers through a tritium air 

monitor to check for contamination was implemented after the 1973 tritium release. This 

practice was discontinued after urinary tritium results in the range of 0.75 μCi/L – 1.3 μCi/L 

were detected in May 1974 for the [redacted for privacy] who performed the monitoring. The 

[redacted for privacy] urinary tritium dropped to less than 0.1 μCi/L beginning in early July 1974 

(SRDB 8790, pdf pp. 18-19). All employees who worked in Room 452, Building 777, submitted

urine samples after the August 30 tritium release, with a high result of 32,320 pCi/L. Table A-3

below shows individual results (SRDB 8790, pdf p. 90).

Table A-3: Tritium Urinalysis Results - Exposed Workers and Others, August 30, 1974

Worker ID Area Urinary Tritium 

(pCi/L) Uncertainty (pCi/L)

[redacted] 777 32320 ± 6170

[redacted] 777 25610 ± 6100

[redacted] 779 24000 ---

[redacted] 777 22370 ± 5800

[redacted] 777 21600 ± 5800

[redacted] 707 17000 ---

[redacted] 777 15740 ± 6100

[redacted] 777 15730 ± 5640

[redacted] 779 14000 ---

[redacted] 707 13700 ± 5370

[redacted] 123 630 ± 580

Non-Occupational (Denver) 470 ---

Source: SRDB 8790, pdf p. 90; Three hyphens (---) = Value not provided.
Page 18 of 42

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ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

The report indicates that both a Denver resident and a Dow employee who did not work in 

radioactive material-handling areas were sampled with results < 0.01 μCi/L (<10,000 pCi/L). 

The Denver resident is identified in Table 3, and Worker ID [redacted for privacy] is believed, 

by implication, to be the [redacted for privacy] non-radiological worker.

Work Area Smear Surveys

Over 200 smear results for tritium are tabulated in the RFAO report (SRDB 8790, pdf pp. 74-

82). Most appear to be surveys inside glove boxes, but there are also workplace area results that 

can be used as indicators of likely sources of internal contamination of workers following an 

event such as the one in August 1974. The workplace smear results are shown in Table A-4

below and continued on the next page.

Table A-4: Tritium Smear Surveys - Work Areas in Buildings 776-777 (pages 18-19)

Date Bldg/Room Location Maximum Smear (pCi)

9/6/74 776-205 205 Plenum - cold side < 100

9/6/74 776-206 206 Plenum - cold side < 100

9/6/74 777-452 206-532 - top of box < 100

9/6/74 777-430 E.S. Welder 353,000

9/6/74 777-437 Penthouse < 100

9/6/74 777-437 A-1 110,000

9/6/74 777-437 A-2 4,800

9/6/74 777-437 A-3 9,400

9/6/74 777-463 A-5 1,200

9/6/74 777-463 Conveyor Line 7,900

9/6/74 777-463 A-7 7,700

9/9/74 776-205 205 Plenum (hot side) 211,000

9/9/74 776-206 206 Plenum (hot side) 1,230,000

9/10/74 776 - Size Reduction Floor < 500

9/10/74 776-201 Floor 1,100

9/11/74 777-452 Floor at J-24 460

9/11/74 777-452 Floor at K-24 470

9/11/74 777-452 Floor at L-24 640

9/11/74 777-452 Floor at M-24 780

9/11/74 777-452 Floor at K-25 560
Page 19 of 42

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positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table A-4: Tritium Smear Surveys - Work Areas in Buildings 776-777 (pages 18-19)

Date Bldg/Room Location Maximum Smear (pCi)

9/11/74 777-452 Floor at J-25 950

9/11/74 776-250 Plenum Floor < 100

9/11/74 776-250 Plenum Fan < 100

9/11/74 776-252 Plenum Floor 465

9/11/74 776-252 Plenum Filter 1,636

9/11/74 776-S-8 Plenum Filter < 100

9/11/74 776-S-8 Plenum Deep Beds < 100

9/11/74 776-S-7 Plenum Filter < 100

9/11/74 776-S-7 Plenum Floor < 100

9/11/74 776-S-4 Plenum Filter < 100

9/11/74 776-251 Plenum Floor 3,625

9/11/74 776-251 Plenum Filter 3,603

9/11/74 776-440 Floor 1,000

9/11/74 776-432 Floor K-20 500

9/11/74 776-432 Floor H-19 1,460

9/11/74 776-432 Floor H-20 710

9/11/74 776-432 Floor K-19 520

9/11/74 776-201 #1 System Kathene 160,000

9/11/74 776-201 #4 System Kathene 400,000

9/11/74 776-201 #3/7 System Kathene 450,000

9/11/74 776-201 #8 System Kathene 140,000

9/11/74 776-201 GBDA System Kathene 400,000

Source: SRDB 8790, pdf pp. 74-82

The exhaust plenums and the Kathabar air driers (which use a lithium chloride solution called 

Kathene) appear to have collected the greatest amount of tritium after the release. Workers 

responsible for changing filters in the plenums or recharging the Kathabar systems would appear 

to be at greatest risk for tritium uptake after the initial release.

Assessment of the 1974 Incident

The 1.5-Ci tritium release from a contaminated shipping container occurred on August 30, 1974. 

The RFAO report provides air survey, bioassay, and smear survey results (SRDB 8790). 

Specific urine sample collection dates were not included in the report but data were matched to 
Page 20 of 42

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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

two NOCTS claims, which reported a collection date of September 5, 1974. A dose assessment 

was performed using the Integrated Modules for Bioassay Analysis (IMBA) software. An intake 

date of August 30, 1974 was assumed, and the largest reported result collected after the incident, 

36,320 pCi/L, was used. There was a slight discrepancy (one digit) between the result included 

in the RFAO report and that in the NOCTS case file; the NOCTS value is assumed to be correct 

because it is the handwritten urinalysis record and is also the larger of the two values. The 

resulting dose is < 1 mrem (0.15 mrem). The Excel file RFP H-3 dose calculations – data.xlsx 

contains the information above as well as the data used for the analysis.

Conclusion

The RFAO report (SRDB 8790) of a 1.5-Ci tritium release on August 30, 1974 from a 

contaminated shipping container (“pressure cooker”) provides air survey, bioassay, and smear 

survey results that can be used to model similar releases. Such a model can be scaled to account 

for the source term and applied to incidents prior to the 1973 environmental tritium release when 

such tritium monitoring data are not available for Rocky Flats. The baseline information from 

these data can also be used to model the pre-1973 background tritium environment at Rocky 

Flats because the 1974 release described in the RFAO report occurred close enough in time to 

the seminal 1973 tritium event that many or most of the procedures and workplace practices had 

only begun to transition to account for the new sensitivity to tritium and its potential impact on 

Rocky Flats operations.

The number and nature of reported tritium release events, both before and after 1973, provide the 

basis for assumptions of pre-1973 workplace release frequencies, quantities and chemical forms.

The parameters of this model can then be used to estimate pre-1973 bounding doses to Rocky 

Flats workers from estimates of the tritium background environment and tritium release

incidents, particularly those involving contaminated shipping containers.

Part III presents an example tritium dose reconstruction that provides dose estimates for the pre1973, 1973, and post-1973 time periods as well as doses and probabilities of causation for four 

types of cancer. The results are summarized below.

• Pre-1973: Using the largest reported result collected after the August 30, 1974 incident, the 

resulting dose is < 1 mrem (0.15 mrem). Assuming one incident per day at 0.15 mrem for 

250 days results in a dose of 37.5 mrem/year for the pre-1973 time period.

• 1973: Using the bioassay samples collected after tritium incident associated with 

contaminated scrap in mid- to late-April 1973 resulted in a maximizing dose of 84 mrem and 

is applied as a bounding estimate of all unmonitored workers. This dose is more precise than 

the estimate in the evaluation report, but is still maximizing. 

• Post-1973: A co-worker study using data from NOCTS for 1974 and 1975 resulted in an 

annual dose of less than 1 mrem; therefore, no dose will be assigned for unmonitored tritium

after 1973.
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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

PART II: Rocky Flats Tritium Dose

Assignment for 1973 and Later

E. M. Brackett, ORAUT

Dose Assignment for 1973

The report, Investigation of the Tritium Release Occurrence at the Rocky Flats Plant (SRDB 

24165, pdf p. 16), describes a 1973 incident that prompted the site to sample a number of 

workers for tritium exposure. A shipment of scrap plutonium from LLNL was discovered to 

have been contaminated with tritium. This material was processed at the Rocky Flats Plant from 

April 9 to 25, 1973 in Building 779A. Because it was not immediately identified as being 

contaminated, monitoring of potentially-exposed individuals did not begin until late September 

1973.

Two hundred fifty people were sampled following the discovery; this included all employees 

who worked in areas in which the contaminated scrap was processed or who were involved in the 

processing of wastes from this scrap. Due to the large sample load, raw urine samples were first 

analyzed in many of the cases. It was noted that the counting efficiency was only about 3% for 

these analyses, and that the corrections made for spectral shift could lead to abnormally-high 

readings. Nineteen employees were initially identified as having elevated tritium levels in their 

urine. These samples were distilled and re-analyzed. Upon this recheck, fourteen of these 

employees were found to be below the 10,000 pCi/L action level established by the site. The 

five most-exposed individuals were identified and details of their potential exposures, including 

bioassay results, are included in the investigation report. One of these five individuals is in 

NOCTS. ORAUT reviewed the results of the five workers who exceeded the 10,000 pCi/L 

action level; this review is presented in Attachment A.

The best estimates for the five cases reviewed in Attachment A are summarized in Table A-5 on 

the next page. Tritium contamination was associated with plutonium scrap material; therefore, 

H-3 doses will be assigned to all individuals who were monitored for plutonium in 1973. 

Because monitoring began several months after the potential start of exposure, the largest 

assessed dose (84 mrem) will be assigned. 

(continued)
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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Table A-5: Summary of Intake Assessments for the RFP 1973 Incident

Case Intake Date Intake (μCi) Dose (mrem)

A 9/19/73 38.7 2.6

B 7/1 thru 9/25/73 28.1 1.9

C 8/27/73 21.3 1.4

D 4/10 thru 4/25/73 1070 72

H 4/6/73 1240 84

Dose Assignment for 1974-1975

ORAUT performed a co-worker study using data from NOCTS for 1974 and 1975. There are 38 

individuals with tritium data in 1974 and 37 in 1975. ORAUT-OTIB-0075, Use of Claimant

Datasets for Coworker Modeling, provides justification and guidance. 

When assessing tritium intakes for most sites, it is assumed that intake potential exists only while 

tritium bioassay monitoring is being performed because monitoring is cheap, easy, and requires 

only spot samples, thus presenting less of a burden than other forms of bioassay on both the 

employer and the employee. Because tritium was not of primary concern at RFP and was 

present only as a potential contaminant on equipment, a given individual was not placed on a 

routine sampling program. Instead, a program was established whereby one-tenth of the urine 

samples collected for plutonium analysis were also analyzed for tritium content (SRDB 111267, 

letter from RFP General Manager to RFAO AEC Manager) as well as the collection of samples 

when there was a particular concern. Samples available in NOCTS for these two years indicate 

that analyses were performed throughout the year, with most individuals sampled only once.

For the purpose of the co-worker study, it was assumed that each worker had the potential to be 

exposed at a constant level throughout the year in which the urine sample was collected. The 

95th percentile was used because one-tenth of the population was sampled. The co-worker study 

for 1974 -1975 yielded doses of 0 mrem for everyone. The file Tritium for 1974-1975 

coworker.xlsx contains the assumptions employed in the study. 

Dose Assignment after 1975

For later years, there are 11 or fewer individuals in NOCTS with tritium data; this is insufficient 

for performing a co-worker study. Results for these years are consistent with those from the 

previous years and show a general decreasing trend. The intake rate from the 1974-1975 

co-worker study (i.e., 0 mrem - see above) will apply to these years; therefore, no additional dose 

due to tritium, as it relates to the assessment performed in this analysis, will be assigned after 

1973.
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with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

Example Dose Reconstruction

Part III on page 33 presents an example tritium dose reconstruction that provides dose estimates 

for the pre-1973, 1973, and post-1973 time periods as well as doses and probabilities of 

causation for four types of cancer.

Attachment A - Rocky Flats 1973 H-3 Dose Assignment

E. M. Brackett, ORAUT

As discussed in Part II of this white paper, ORAUT reviewed the results of the five workers who 

exceeded the 10,000 pCi/L action level for tritium following a 1973 incident. This attachment 

provides the results of ORAUT’s review and proposes a method for the assignment of H-3 doses 

in 1973.

Background

Investigation of the Tritium Release Occurrence at the Rocky Flats Plant (SRDB 24165, pdf p. 

16) describes an incident in 1973 that prompted the site to sample a number of workers for 

potential H-3 exposure. The initial location of the contaminated scrap was identified as 

Building 779A, Room 154, in mid- to late-April. The waste stream from the processing of this 

material was also contaminated, providing opportunities for intake of H-3 at later dates. The 

collection of samples from a tritium-contaminated water bubbler on September 19 and 

September 25, 1973 were also identified as possible opportunities for intakes.

The contamination problem was not immediately identified; therefore, urinalysis began several 

months after the potential start of intakes. Samples were collected from about 250 employees. 

All employees who worked in areas in which the contaminated scrap was processed, or who 

were involved in the processing of wastes from this scrap were included in the urinalysis 

program. 

Exhibit 14 of the referenced report contains a section on Personnel Exposure Data. The 

following is an excerpt (SRDB 24165, pdf p. 122):

SAMPLING PROTOCOL

Dow began by sampling urines from all employees who were thought to have had the best 

chance of being exposed to tritium. As of October 15, 1973, about 250 employees have been 

tested. Dow is continuing to trace leads to other possible exposure and will sample them as 
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they are found. Dow intends to sample many employees who have had only a remote chance 

of coming in contact with tritium. Dow also tests the urine of any employee who requests this 

whether or not they are candidates for exposure.

ACTION LEVELS

An "action level" of 10,000 pCi/l was tentatively chosen for resampling. This level was 

chosen for several reasons such as:

1. An article by Fitzsimmons indicated that people wearing tritiated watches could excrete 

levels of 10,000 pCi/l.

2. A calculation of worst possible circumstances indicate that an employee would have to 

exceed levels of 23,000 pCi/l before any permissible yearly levels of whole body radiation 

would be exceeded.

3. The sample load was such that Dow could handle resampling only a limited number of 

employees on a frequent basis. It turned out that a relatively small number were over 

10,000 pCi/l but a large fraction were in the 5,000 and 10,000 pCi/l range.

4. Without predistilling the urine samples the counting efficiency drops to about 3% and the 

corrections made for spectral shift can lead to abnormally high reading.

5. With a large sample load, counting time devoted to each sample must be restricted so 

that 10,000 pCi/l might be considered lowest detection limit available under the present 

circumstances.

All samples above 10,000 pCi/l are redone by counting the distillate of the original sample.

Five workers with H-3 urinalysis results exceeding the action level of 10,000 pCi/L were 

identified. Results from these five workers are reviewed here. Fourteen other workers initially 

exceeded the 10,000 pCi/L level but fell below this upon recount (as noted above, the distillates 

of the original samples were counted). 

Dose Assessment

Information about the five workers with the largest H-3 sample results (including H-3 urinalysis 

results and brief work histories) is included in the referenced SRDB document. This information 

was used to assess the doses to the affected workers and is displayed in italics in the sections 

below.
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All five cases had initial samples that were not distilled, with one to five later distilled samples. 

In general, the two sets of results were not consistent, with the distilled samples yielding lower 

values. This is to be expected given the site discussion above (see Item 4). The pre-distilled 

results were used in the development of this white paper because there were more results 

available and they yielded claimant-favorable doses.

The following assumptions were employed in this assessment:

• Equal weight to all samples (measurement error the same for all samples)

• Only pre-distilled samples used for fits (these are shown as blue dots in the figures; distilled 

samples appear in red and are not used in the analysis)

• H-3 in the form of tritiated water (HTO)

• IMBA model for inorganic H-3, as described in Guidance on Use of IMBA Software for DOE 

Safety Applications (DOE, 2006)

• Injection intake (for modeling with IMBA)

• Intake dates based on worker information and examination of fit to urine sample results

The five workers identified as having the largest H-3 urinalysis results are assessed below. Text 

in italics indicates an excerpt from the incident report.

Case A

Case A worked in Room [redacted for privacy] from [redacted for privacy], until [redacted 

for privacy].

He was involved in the [redacted for privacy] of the parts in question from [redacted for 

privacy], along with Cases [redacted for privacy]. He was not involved in any of the 

following special projects:

A. May 8, 1973, Window Change

B. June 16, 1973, TV Camera Installation

C. August 21, 1973, Rotary Blower Installation

He was involved in taking samples from a [redacted for privacy] on [redacted for privacy 

1973. On [redacted for privacy], this was done without a rubber glove.
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From this history, it would appear the most likely exposure occurred on [redacted for 

privacy]. If an exposure had occurred between [redacted for privacy], 1973, it is likely that 

both Cases [redacted for privacy] would have been exposed to the same source, and 

subsequently, excreted the same quantities of tritium.

The incident report also reads:

In Case A, a history of his work assignment and his urine results for the first two weeks 

indicate that he sustained a recent exposure. At the present time he is excreting tritium 

with an elimination half life of less than 10 days. According to Sanders and Snyder, this 

is the pattern of elimination from an exposure up to 90-days post exposure.

The statement that his intake appears to be recent agrees with current models for HTO intakes. If 

an intake is assumed from [redacted for privacy], a very poor fit to the data is obtained, as shown 

below in Figure A-1. 

Figure A-1: Case A Chronic Intake of HTO from [redacted for privacy], 1973

Based on the worker’s history and the bioassay result pattern, an acute intake was assumed to 

have occurred on [redacted for privacy], 1973. Using the results of samples collected from 

[redacted for privacy], and applying a uniform error to each of the samples, the intake is 38.7 

μCi. The corresponding dose is 2.6 mrem. These samples are presumed to be pre-distilled 

because later samples from [redacted for privacy], are labeled as “distilled.” This yields a very 

good fit to the pre-distilled results (see Figure A-2 on the next page). 

(continued)
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Figure A-2: Case A Acute Intake of HTO [redacted for privacy], 1973

Case B

He has worked in [redacted for privacy], since [redacted for privacy]. He was in the 

room when [redacted for privacy], that contained tritium.

Assumption of a chronic intake from [redacted for privacy], (date of first urine sample) yields an 

intake rate of 0.33 μCi/d (for a total intake of 28.1 μCi) and provides a reasonable fit to the 

results (see Figure A-3 below). The dose is 1.90 mrem.

Figure A-3: Case B Chronic Intake of HTO from [redacted for privacy], 1973

Assumption of an acute intake on [redacted for privacy], [redacted for privacy], yields an intake 

of 7.28 μCi. This fit (see Figure A-4 below) is almost identical to the first scenario. 
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Figure A-4: Case B Acute Intake of HTO on [redacted for privacy], 1973

A single acute intake on his [redacted for privacy] day in the area [redacted for privacy] yields an 

intake of 720 μCi and a dose of 49 mrem (see Figure A-5 below).

Figure A-5: Case B Acute Intake of HTO on [redacted for privacy], 1973

The single acute intake on [redacted for privacy] does not provide a good fit to the later predistilled results. The first two scenarios (chronic intake from [redacted for privacy], and acute 

intake on [redacted for privacy]) provide similar fits that reasonably follow the pattern of the predistilled samples. The chronic intake yields a larger intake so it is used for the best estimate. 
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Case C

He worked in [redacted for privacy] since [redacted for privacy]. He was not in the 

room when [redacted for privacy] containing tritium.

Given that the worker did not start in the area until [redacted for privacy], an acute intake was 

assumed on this date (see Figure A-6 below). Using only the pre-distilled sample results, his 

intake is 21.3 μCi with a dose of 1.4 mrem. 

Figure A-6: Case C Acute Intake of HTO on [redacted for privacy] 1973

If a chronic intake is assumed to have started on his [redacted for privacy] day of potential 

exposure ([redacted for privacy]) and continued until the date of his [redacted for privacy] 

([redacted for privacy]), the resulting intake is 0.24 μCi/d for a total intake of 7.08 μCi. This fit 

is shown in Figure A-7 below.

Figure A-7: Case C Chronic Intake of HTO from [redacted for privacy] 1973
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The two fits are very similar, so the acute intake is selected as the best fit as it results in a dose 

that is more favorable to the claimant.

Case D

He worked in [redacted for privacy], between [redacted for privacy], 1973. He has not 

been exposed to tritium since [redacted for privacy].

Case D submitted samples on only three days, although there are two results on two of those 

days. In one instance, one of the samples was distilled; on the other day, there is a note stating 

“repeated with sample channel ratio.” On the latter day, the results differ by a factor of almost 

two; the larger of these results is assumed to be the pre-distilled analysis and is used for the 

intake assessment. An assumed chronic intake from[redacted for privacy] (last date of incident) 

yields an intake of 71.2 μCi/d for a total intake of 1070 μCi (see Figure A-8 below). The 

resulting dose is 72 mrem.

Figure A-8: Case D Chronic Intake of HTO from [redacted for privacy] 1973

A chronic intake from [redacted for privacy] yields an intake rate of 8.84 μCi/d for a total intake 

of 581 μCi (39 mrem), as shown in Figure A-9 on the next page. 

(continued)
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Figure A-9: Case D Chronic Intake of HTO from [redacted for privacy] 1973

Because there are few samples and the results follow no specific pattern, there is little difference 

between the fits. Therefore, the acute intake is assigned because it yields the larger dose. 

Case H

He came in contact with the possible source of tritium on [redacted for privacy] 1973. 

No other information is included in the report. The conclusion in the report is: (It is expected 

that, as a result of a review of his work history and urinalysis data, a dose assignment of less 

than 3 rem will be made.) However, no follow-up information is available. Because the only 

available information indicates that an intake would have occurred on [redacted for privacy] , an 

acute intake was modeled (see Figure A-10 below). The resulting intake is 1240 μCi with a 

dose of 84 mrem. 

Figure A-10: Case H Acute Intake of HTO on [redacted for privacy] 1973
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Recommendation

The best estimates for each case are summarized in Table A-6 below. Tritium contamination 

was associated with plutonium scrap material; therefore, H-3 doses will be assigned to all 

individuals who were monitored for plutonium in 1973. Because monitoring began several 

months after the potential start of exposure, the largest assessed dose (84 mrem) will be assigned. 

Table A-6: Summary of Intake Assessments for the RFP 1973 Incident

Case Intake Date Intake (μCi) Dose (mrem)

A 9/19/73 38.7 2.6

B 7/1 thru 9/25/73 28.1 1.9

C 8/27/73 21.3 1.4

D 4/10 thru 4/25/73 1070 72

H 4/6/73 1240 84

Reference

DOE, 2006, Guidance on Use of IMBA Software for DOE Safety Applications, DOE-HS-0002, 

U.S. DOE, Washington D.C.; December 2006 (SRDB 33212)
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PART III: Example RFP Tritium Dose Reconstruction

Mutty Sharfi, ORAUT

Employee Information

Cancer Description: Lung (ICD-9: 162); diagnosed 12/31/2000

Prostate (ICD-9: 185); diagnosed 12/31/2000

BCC (ICD-9: 173); diagnosed 12/31/2000

SCC (ICD-9: 173); diagnosed 12/31/2000

Year of birth: 1932

Gender: Male

Smoking: Never Smoked

Ethnicity: “White, non-Hispanic”

Employment Information

Start date: 01/01/1959

End date: 12/31/1975

Occupation: Unknown 

Dosimetry Data: None

Organ Dose Assessed

Table A-7: Organ Dose Assessed

Cancer External Organ Used Internal Organ Used

Lung Lung Lung

Prostate Urinary Bladder Heart Wall1

Skin Skin Skin

Source: ORAUT-OTIB-0005 1 Non-metabolic organ with the highest dose

External Dose

Not applicable for tritium exposures.

Internal Dose

• Pre-1973: The 1.5-Ci tritium release from a contaminated shipping container occurred on 

August 30, 1974. The largest reported bioassay result (SRDB 8790) collected after the 
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incident was used to assess the potential exposure from this release. The resulting dose is 

was about 0.15 mrem. Assuming this event occurred every workday of the year (250 times a 

year), the resulting annual dose would be about 38 mrem/year.

• 1973: A tritium incident associated with contaminated scrap occurred in Building 779A, 

Room 154, in mid- to late-April 1973. Because of this incident, the site sampled a number of 

workers for potential H-3 exposure (SRDB 24165). An analysis of these bioassay samples 

resulted in a maximizing dose of 84 mrem and is applied as a bounding estimate of all 

unmonitored workers. The assessment of the bioassay data for the 1973 incident includes all 

potential exposures for the year. The assumption of an acute intake bounds any potential 

underlying chronic exposure. 

• Post-1973: ORAUT performed a co-worker study using data from NOCTS for 1974 and 

1975 in accordance with ORAUT-OTIB-0075, Use of Claimant Datasets for Coworker 

Modeling. The 95th percentile annual dose was less than 1 mrem. Therefore, no dose will be 

assigned for unmonitored tritium after 1973.

Uncertainty 

All doses are applied as a constant distribution. 

Summary 

The assessment methods presented in this report define the methods by which a dose estimate 

can be determined for the evaluated worker class. These methods support NIOSH’s conclusion 

that the operationally-related internal dose for the evaluated worker class can be bounded. A 

summary of the doses and probability of causations are provided in Table A-8 below.

Table A-8: Example RFP Tritium DR - Summary of Doses and Probabilities of Causation

Cancer External (rem) Internal (rem) Total (rem) Probability of Causation

Lung 0.000 0.616 0.616 3.99%

Prostate 0.000 0.616 0.616 1.45%

Skin BCC 0.000 0.616 0.616 3.38%

Skin SCC 0.000 0.616 0.616 0.47%
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Appendix 2: Response to Work Group/SC&A Comments 

on the Rocky Flats Plant Tritium White Paper

TIMELINE

7/2013 – Board Working Group Meeting – developed issues that were responded to in the 

response to comments document.

9/2013 – Board Working Group Meeting – the tritium white paper was reviewed and the 

three periods assessed in the white paper were discussed:

- 1973 – Liz B. to send the WG and SC&A her IMBA files so that they may perform a 

comparative review of the proposed pre-1973 method.

- Post-1973 (1974-1975) – WG/SC&A not in agreement at the meeting about the dose 

being less than 1 mrem.

- Pre-1973 – discussions about the applicability of the 1974 incident data for the pre-1973 

period.

10/2013 – AB Meeting – although a SEC class is recommended that covers the time period in 

question related to the tritium exposure, additional confirmation/agreement to occur in regard 

to the partial DR method for tritium in the SEC period.

- Dr. Ziemer requested information on why the post-1973 coworker model came up with 0 

dose when there was dose associated with the 1974 incident – ensure that the bioassay 

samples from the 1974 incident in a co-worker model.

1/2014 – The SC&A report titled: SC&A Review of Part II, Rocky Flats Tritium Dose 

Assignment for 1973, Attachment A, was provided as an additional review response to the 

NIOSH Tritium white paper based on Working Group tasking. Included in the email 

response associated with this SC&A review was an indication that this tritium dose 

assignment review only focused on the 1973 period, and that SC&A was awaiting a response 

for the pre and post-1973 methodologies presented in the NIOSH white paper. 

COMMENT RESPONSES

1. If bubbler data exists and can be compared, compare pre-1973 data to 1974 data.
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RESPONSE: Only environmental and stack effluent tritium results have been captured 

for Rocky Flats prior to 1973; no tritium bubbler data for RFP work areas have been 

found for the pre-1974 period. However, additional SRDB searches identified workplace 

tritium results obtained in September-October 1973 using cold traps – part of the effort 

by Rocky Flats to identify the source of the 1973 environmental tritium release. These 

data may be useful for comparison with the 1974 bubbler data, but they still represent 

results from work areas potentially affected by the April 1973 release. (See information 

in Item 2 below.)

2. Look at baseline survey data from 1973 (SRDB 68351) to see if comparisons can be 

made. NOTE: Recognize that bubbler data may be suspect based on a classified 

interview noting that the bubbler was only present during opening of the secondary 

container and not present when opening the primary container.

RESPONSE: In response to the working group discussion of the documents referenced 

in the white paper:

• SRDB 111095 is a collection of hand-written records of survey and air sample logs, 

including bubbler sample results (1121 pages). The document contains information 

for the years from 1977-1982.

• SRDB 122712 is a collection of 1997 bubbler results analyzed and reported by 

Thermo NUtech (33 pages). There is no information in this source about other years 

at RFP.

• SRDB 122550 is the official transcript of the NIOSH-ORAUT interview of a former 

RFP employee. The former employee indicates that RFP started using tritium 

bubblers when opening outer containers (not when opening inner containers 

containing the pits). This occurred in 1965 in the B771 downdraft room; however, no 

bubbler results for the period prior to 1973 have been found. The interviewee also 

indicated that the bubblers were positioned in front of the intake plenums of the 

exhaust systems to serve as alarming devices, and not to record routine airborne 

concentrations in the area.

Based on additional research into the tritium release evaluation at RFP, ORAUT 

confirmed that smears, radioactive gas monitors, and cold traps were used in tracing the 

source of the April 1973 release; however, the only workplace air monitoring results 

reported were from cold trap samples. 
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Radioactive gas monitor results were all from glove box atmospheres. SRDB 111284, pdf p. 75, 

states (bold added for emphasis):

“A general survey using smear technique and subsequent radiochemical analysis at 

Building 123 was initiated in all buildings or specific areas of those buildings 

where the possibility of tritium was suspected. Smears were also taken inside 

glovebox lines in several areas. Most of the analysis for the latter group of smears has 

not been completed. In addition, air was monitored using Johnson Model 1055 or 

955 radioactive gas monitors and/or cold trap samplers in Buildings 774 and 779-

A. A bubbler sampler was installed to sample the Building 779-A exhaust air effluent 

and analysis for tritium was performed on water traps normally used as part of the 

stack sampler system for the Building 774 evaporator stack.”

Table 1 summarizes the cold trap sample data presented on pdf p. 79 in SRDB 111284.

Table 1: RFP Cold Trap Samples – Air 

Building Room Date H-3 

(pCi/m3)

Remarks

774 203 9-28-73 20.7 none

220 9-28-73 9.2 none

210 10-1-73 14 none

320 10-1-73 15 none

779-A 154, NE 9-26-73 1,580 none

154, NE 9-28-73 10,000 none

154, NE 10-1-73 1,068 none

154, NE 10-2-73 451 none

154, NE 10-4-73 302 none

154, SW 9-26-73 1,491 none

154, SW 10-1-73 400,750 none

154, SW 10-2-73 113 none

154, SW 10-4-73 5,540 none

001 10-4-73 3,700 Sampling from above liquid level in 

building process holding tanks

142 10-4-73 12,146

Boiler ventilation room. Filtered air passes 

through room and is recycled back to dryers 

and laboratories

(continued)
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NOTE: The average and standard deviation of the above results are:

• Building 774: (14.7 ± 4.7) pCi/m3

• Building 779-A, Rm 154 NE and SW: The documentation offers no explanation for 

the high result of 400,750 pCi/m3 on October 1, 1973.

- Calculation including the high value: (46,810 ± 132,766) pCi/m3

- Calculation excluding the high value: (2568 ± 3466) pCi/m3

Readings taken in Building 777, Rm 452 in the 31⁄2 months prior to the 1974 tritium 

contamination incident had average and standard deviation of (5343 ± 4518) pCi/m3. 

Building 779-A, Rm 154 housed the glove box hydriding reaction chamber where 

tritium-contaminated Pu from LLL was processed in April 1973, resulting in the 

highly-publicized environmental tritium release to public drinking water supply 

reservoirs. The resulting plutonium hydride was oxidized in other glove boxes in 779-A, 

Rm 154 before transfer to Bldg 771 for reduction to Pu metal. Bldg 771 process wastes 

were then transferred to Bldg 774 for further processing, or were sent either to the solar 

evaporation ponds or the sanitary sewer.

Glove boxes in Building 779-A, Rm 154 and in Buildings 771 and 774 were all found to 

be contaminated with tritium after the 1973 environmental release. It is interesting to 

note that, even though Bldg 774 glove boxes were tritium-contaminated, the Building 774 

work area cold trap samples showed extremely low tritium results. It appears that the 

glove boxes provided good containment.

ORAUT also reviewed the available NOCTS claims that had tritium bioassay data to 

determine the existence of a pre-1973 bioassay sampling program and to assess the 

sufficiency of the monitoring program for identifying potential tritium exposures and/or 

incidents. Five pre-1973 tritium bioassay samples for five different individuals were 

identified out 312 total sample results for 125 individuals (data ranging from 1966-1996). 

The five pre-1973 tritium sample results are: 

• Three urine samples, 1966: all background 

• One urine sample, January 1973: 5542 ± 846 (units not specified - assumption: pCi/L) 

• 1 urine sample, April 1973: background
Page 39 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

There do not appear to be any specific tritium incidents related to the collection of any of 

the pre-1973 bioassay samples. However, the fact that the samples do exist indicates that 

there was a capability for tritium urinalysis and a will to use it going back to 1966. The 

result from January 1973 is about 17% of the highest urine specimen from the 1974 

incident, which supports the use of the 1974 data to bound the pre-1973 tritium doses.

To date, no information has been identified to dispute the use of the 1974 data in the 

development of a pre-1973 bounding approach for tritium at RFP. NIOSH-ORAUT will 

continue to assess the data to confirm that this continues to be the case and will address 

issues with the bounding approach if and when they arise.

3. If the ChemRisk report is used for supporting dose reconstruction, look and see if the 

report was validated in any way.

RESPONSE: The ChemRisk report was referenced and used in the development of the 

RFP Environmental TBD; however, no additional validation of the report data has been 

performed by ORAUT. While this TBD may be used to support dose reconstructions, the 

associated exposure scenarios associated with the ChemRisk data are not considered to be 

representative of the most highly-exposed individuals (i.e., the data are more 

representative of radiological conditions outside of the work areas and plants). The 

available personnel monitoring/bioassay data contained in an individual’s personnel 

monitoring records are considered the most representative and bounding from a personnel 

exposure perspective.

4. Determine whether Pantex changed their shipping controls/survey criteria/shipping 

survey and contamination limits (did they change?) after the 1973 tritium release at 

Rocky Flats. If so, when did any changes occur?

RESPONSE: Based on the available documentation, it appears that the earliest changes 

made by Pantex that were related to tritium-contaminated shipments were made in the 

early 1980s. Below is a summary of the documentation review:

Pantex:

• Based on the available documentation, it is not apparent that changes in the Pantex 

program in response to the 1973 or 1974 incidents (i.e., shipping controls/survey 

criteria/shipping survey and contamination limits) occurred until 1981 

(SRDB 107801). Other Pantex documentation in the SRDB corroborates this 

conclusion (i.e., no available information is dated earlier than 1981) (SRDB 109244; 

109245; 109246; 109255).
Page 40 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

RFP:

• The 1974 incident occurred on September 3-4, 1974. Five RFP documents in the 

SRDB relate to the post-1974 incident follow-up: 

- SRDB 111267 (September 12, 1974)

- SRDB 111288 (September 12-16, 1974)

- SRDB 111301 (October 21, 1974)

- SRDB 8789 (November 12, 1975)

- SRDB 111106 (December 1974)

• All these documents are related to the RFP’s post-incident responses, including: (1) 

implementation of RFP action levels; (2) RFP performance of tritium surveys of 

suspect shipments; and (3) RFP requests that sites shipping related packages to RFP 

perform their own surveys. 

• A June 6, 1974 memorandum from Rocky Flats to the AEC indicates adoption of an 

upper limit of 10 mCi tritium per kilogram of plutonium shipped into Rocky Flats 

(SRDB 111268). Certification of an incoming material’s history was required of 

shippers in response to AEC recommendations issued after the 1973 tritium release 

led to the realization that trace amounts of tritium could be found in almost all 

materials, thus pointing to the need for an acceptance limit. Incoming shipments that 

could result in excessive tritium levels at RFP continued to be monitored for 

verification.

• ORAUT coordinated a request for information from RFP related to communication 

with Pantex regarding the implementation of control limits for shipments. RFP 

responded that no information was available (August 8, 2013 email from Rod 

Hoffman); since the time limit for retention of those records has expired, RFP 

believes that the documents may have been destroyed per the document 

retention/destruction schedule. 

ADDITIONAL COMMENT RESPONSE – DR. ZIEMER QUESTION

1. The question of why the coworker model came up with 0 dose when there was dose 

associated with the 1974 incident – was the bioassay samples from the 1974 incident 

included in the post-1973 RFP tritium co-worker model presented in the RFP tritium 

white paper.

RESPONSE: The coworker model was based on the analysis of the NOCTS claimant 

data. The assessed dose from the coworker was less than 1 mrem per year, which, in 
Page 41 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

terms of dose assignments for an individual DR under the EEOICPA program, results in 

a zero dose assignment for the purpose of calculating POC. All the NOCTS claimant 

data available for 1974 were used in the coworker study. While all the results from the 

1974 site incident report were not added in because details regarding the individuals were 

incomplete, the data/results that can be matched with NOCTS claimants (for two 

individuals) were used – data from the claimant’s NOCTS files; no data were added from 

the incident report. The results matched with NOCTS claimants included those for one 

individual identified as having the largest intake from the incident. It is noteworthy that 

the largest dose from the 1974 incident was only 0.15 mrem so inclusion of all of the 

results still wouldn’t yield a dose greater than 1 mrem.

ADDITIONAL COMMENT RESPONSE – SC&A REVIEW OF TRITIUM WHITE 

PAPER

1. SC&A reviewed the NIOSH tritium White Paper and provided comments and feedback 

on the tritium dose reconstruction method presented for the 1973 period at RFP in their 

paper titled: SC&A Review of Part II, Rocky Flats Tritium Dose Assignment for 1973, 

Attachment A.

RESPONSE: The primary NIOSH response to the SC&A review is that the SC&A 

analysis uses a draft model that is clearly identified as not for use at this time, which is 

acknowledged in the SC&A response. The Rule governing this program explicitly 

requires the use of currently approved ICRP models for the purpose of assessments and 

use of such unapproved models is outside of the scope of the NIOSH methodology. As 

such, NIOSH has not performed a detailed analysis of the model as it relates to 

EEOICPA dose reconstruction or the results provided by SC&A in their assessment. The 

general observation is that it should have very little impact on situations outside of the 

RFP because it only affects cases where urine samples are collected more than 100 days 

after intake, which should be a rare occurrence for tritium. It is noted that the SC&A 

paper matched the NIOSH White Paper values when the bioassay was collected 50 or 60 

days after the assumed intake. If the model is approved and issued by the ICRP, it will be 

reviewed for incorporation into the EEOICPA dose reconstruction program.

One of the focuses in the SC&A assessment of the NIOSH Tritium White Paper was the 

analysis of Case A (from the RFP evaluation of the five highest exposed individuals from 

the 1973 tritium release incident). It appears that the SC&A assessment results are 

approximately the same as the results presented in the NIOSH White Paper for Case A 

when the same intake assumptions are used. The similar results occur when assessing the 

exposures based on the ‘best fit’ of the data in the model – the best fit scenario is not 

disputed by SC&A; rather, the SC&A assessment offers other possible exposure 

situations that were not considered plausible based on NIOSH’s review. The earlier 
Page 42 of 42

This working document prepared by NIOSH’s Division of Compensation Analysis and Support (DCAS) or its contractor for use in discussions 

with the ABRWH or its Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This document represents preliminary 

positions taken on technical issues prepared by NIOSH or its contractor. NOTICE: This report has been reviewed to identify and redact any 

information that is protected by the Privacy Act 5 USC §552a and has been cleared for distribution.

intake date assumed by SC&A had been ruled out in the NIOSH analysis because Case A 

worked with Cases [redacted for privacy] in April and they did not exhibit similar 

excretion levels, and Case A’s elimination pattern exhibited a less-than-10-day half time, 

which is indicative of a relatively recent intake. In its review, the SC&A assessment 

concurs with the NIOSH assessment of Case D. However, as it relates to Case A, SC&A 

does not address that workers [redacted for privacy] worked together in April 1973 on the 

same project. When considered, there is no support for the use of the SC&A assumptions 

for Case A that results in the significantly higher dose totals. Further explained, the 

likelihood of [fewer than 9] receiving an intake of 92 mCi when co-located workers 

received no intake, is not plausible. NIOSH concludes that the nature of the exposure 

scenario does not support large differences in personnel exposure; rather, it supports the 

use of the NIOSH best fit analysis.

The other details discussed by SC&A regarding the use of un-distilled versus distilled 

samples support the basis that the NIOSH assessment presents a claimant-favorable 

approach for tritium dose reconstruction in the SEC period. In addition to the above 

thoughts regarding the assessment of the tritium exposures for 1973, it is important to 

remember that the entire period being assessed for tritium falls in the currently 

recommended SEC period (through 1983). Therefore, NIOSH feels that the assessment 

for 1973, as well as the pre and post-1973 periods, represent NIOSH’s best and final 

approaches for reconstructing tritium at RFP within the associated time periods.