Draft 

ADVISORY BOARD ON 

RADIATION AND WORKER HEALTH 

National Institute for Occupational Safety and Health 

 SC&A RESPONSE TO NIOSH WHITE PAPER: 

“FOLLOW-UP EFFORTS ON SEC-00192 

ROCKY FLATS PLANT TRITIUM ISSUES,” 

DATED MAY 30, 2014

Contract No. 211-2014-58081

Prepared by 

John Mauro 

Joyce Lipsztein 

Joseph Fitzgerald 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, VA 22182 

September 2014 

Disclaimer 

This document is made available in accordance with the unanimous desire of the Advisory Board 

on Radiation and Worker Health (ABRWH) to maintain all possible openness in its 

deliberations. However, the ABRWH and its contractor, SC&A, caution the reader that at the 

time of its release, this report is pre-decisional and has not been reviewed by the Board for 

factual accuracy or applicability within the requirements of 42 CFR 82. This implies that once 

reviewed by the ABRWH, the Board’s position may differ from the report’s conclusions. Thus, 

the reader should be cautioned that this report is for information only and that premature 

interpretations regarding its conclusions are unwarranted.
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S. COHEN & ASSOCIATES:

Technical Support for the Advisory Board on

Radiation & Worker Health Review of

NIOSH Dose Reconstruction Program

Document No. 

Response to NIOSH White Paper

Effective Date:

Draft – September 18, 2014

SC&A Response to NIOSH White Paper: 

“Follow-up Efforts on SEC-00192 Rocky Flats 

Plant Tritium Issues,” dated May 30, 2014

Page 2 of 37

Task Manager:

________________________________________

Joseph Fitzgerald, MS, MPH Date

Supersedes: 

N/A

Project Manager:

________________________________________

John Stiver, MS, CHP Date

Reviewers:

 A. Makhijani, PhD

 J. Stiver

Record of Revisions

Revision 

Number

Effective 

Date Description of Revision

0 (Draft) 09/18/2014 Initial issue
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TABLE OF CONTENTS 

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

Executive Summary .........................................................................................................................6

1.0 Introduction ..........................................................................................................................8

2.0 Commentary on the NIOSH White Paper Addressing Tritium Issues Dated May 30, 

2014....................................................................................................................................11

2.1 The 1973 Incident and Associated Exposures (Appendix 1, Part II) .....................11

2.1.1 Overview ....................................................................................................11

2.1.2 SC&A Response to Specific NIOSH Comments.......................................14

2.2 Post-1973 Exposures ..............................................................................................20

2.2.1 Observations and Conclusions Regarding Post-1973 Exposures 

based on Review of the SRDB Folders......................................................28

2.3 Pre-1973 Exposures (Appendix 1, Part I) ..............................................................29

References ......................................................................................................................................36
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ABBREVIATIONS AND ACRONYMS 

ABRWH, Board or 

Advisory Board Advisory Board on Radiation and Worker Health 

AEC Atomic Energy Commission 

BNWL Battelle Northwest Laboratory 

Bq Becquerel 

Ci curie

d day 

dis/sec disintegrations per second 

DOE (U.S.) Department of Energy 

dpm disintegrations per minute 

EEOICPA Energy Employees Occupational Illness Compensation Act of 2000 

g gram 

GI gastro-intestinal 

h or hr hour 

HTO tritium oxide 

ICRP International Commission on Radiation Protection 

IMBA Integrated Modules for Bioassay Analysis 

keV kilo electron volt, 1,000 electronvolts 

kg kilogram 

L or l liter 

LANL Los Alamos National Laboratory 

LLL Lawrence Livermore Laboratory 

LLNL Lawrence Livermore National Laboratory 

LSD Liquid Scintillation Detector 

m3cubic meter 

MDL minimum detectable limit 

MeV million electron volt 

ml milliliter 

mrad millirad 

mrem millirem 

μCi microcurie 
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NIOSH National Institute for Occupational Safety and Health 

NOCTS NIOSH/OCAS Claims Tracking System 

OBT organically bound tritium 

ORAUT Oak Ridge Associated Universities Team 

pCi picocuries 

PER Petition Evaluation Report 

QC quality control 

rad radiation absorbed dose 

RFAO Rocky Flats Area Office 

RFP Rocky Flats Plant 

SRS Savannah River Site 

SS “Source and Special” [nuclear material] 

SC&A S. Cohen and Associates (SC&A, Inc.) 

SEC Special Exposure Cohort 

SRDB Site Research Database 

Sv Sievert

y or yr year
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EXECUTIVE SUMMARY 

This SC&A white paper is being provided to the Advisory Board on Radiation and Worker 

Health (ABRWH or Advisory Board) and the National Institute for Occupational Safety and 

Health (NIOSH) in response to NIOSH’s May 30, 2014, white paper titled, Response: Rocky 

Flats Plant Surveillance Document Review (Bogard et al. 2014). NIOSH’s white paper 

represents the latest exchange of white papers and discussions performed under the direction of 

the RFP Work Group designed to resolve issues associated with the reconstruction of tritium 

doses to RFP workers. NIOSH sought to revisit its 2013 assessment (Bogard et al. 2013) based 

on additional document data captures and personnel interviews that were performed 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. NIOSH’s

additional investigations did not lead to any changes in its conclusions regarding the validity of 

the tritium bounding method for the SEC-00192 evaluation report for RFP. 

The tritium exposures of primary concern are those to workers who opened containers received 

by RFP that, at times, may have been contaminated with tritium. Reviews of the various white 

papers that were prepared by NIOSH and SC&A, discussions of tritium issues at various work 

group meetings, worker interviews, and the review of documents captured during site visits and 

placed in the Site Research Database (SRDB) reveal that prior to an incident that occurred in 

April 1973, it was the general belief that material shipped to RFP for processing did not contain 

tritium, because the tritium was monitored and removed prior to shipment. As a result, RFP’s 

radiological controls before 1973 included very little in-plant tritium air monitoring and no 

routine tritium bioassay monitoring of workers. The incident was discovered as part of a routine 

environmental surveillance program being performed by the State of Colorado. 

Subsequent to the April 1973 incident, actions were taken by the Department of Energy (DOE) 

and its contractors to determine the cause of the incident, the impacts of the incident, and take 

corrective actions to avoid such incidents in the future. In addition, as more was learned about 

the incident, DOE and its contractors began to put in place and expand upon certain tritium 

monitoring programs, which included air samplers using bubblers and scintillation counters, 

tritium swipe samples, effluent and environmental monitoring, and bioassay programs. 

The data and process knowledge that NIOSH proposes to use to reconstruct the tritium doses to 

workers associated with the April 1973 tritium incident are described in the various white papers. 

In addition, research related to the 1973 incident uncovered information associated with other 

incidents of lesser impact than the 1973 incident that expanded NIOSH’s investigations into 

tritium exposures. Investigations into tritium exposures were, therefore, divided into three time 

categories; the 1973 incident, exposures post-1973, and exposures pre-1973. NIOSH’s 

investigations concluded that (1) the highest tritium dose associated with the 1973 incident was 

84 mrem; (2) the coworker model for post-1973 exposures is assumed to be zero mrem/yr, 

except for known exposures to workers specifically exposed in the 1974 incident; and (3) pre1973 exposures to tritium are assumed to be 37.5 mrem/yr, assuming one incident per day at 

0.15 mrem (largest reported bioassay result from the 1974 release) for 250 work days per year. 
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SC&A’s investigation into these matters found that a plausible upper bound for the exposures 

associated with the 1973 incident may be as high as 6,000 mrem. The reasons for the differences 

between the NIOSH and SC&A estimates of the tritium dose are that SC&A assumed a different 

date when the acute intakes occurred for some workers and also used a tritium retention model 

that is being developed by the International Commission on Radiation Protection (ICRP) that is 

applicable to circumstances where urine samples are first collected more than 100 days following 

an acute exposure. SC&A used this model, because the current ICRP model is only applicable to 

reconstructing acute doses that occurred less than 100 days before the first urine sample is 

collected. SC&A, while acknowledging NIOSH’s response that it is not, as a matter of internal 

policy, able to use pending ICRP methods, points out that NIOSH did not use the current 

recommended ICRP intake-excretion function for deriving the bounding intakes for tritium, but 

an Integrated Modules for Bioassay Analysis (IMBA) modification of the model, which was not 

approved by the ICRP. 

With respect to NIOSH’s conclusions regarding post-1973 exposures, SC&A concludes that 

post-1973 data cannot be used with confidence to reconstruct post-1973 exposures. In our 

judgment, based on the original 1974 investigation, there is considerable uncertainty regarding 

the locations of the bubblers in relation to the locations where workers might have been exposed 

during and following the 1974 incident, and perhaps other unidentified incidents. As a result, 

SC&A questions data adequacy with respect to reconstructing post-1973 exposures. In addition, 

the post-1973 urine sampling data were collected too infrequently to be used with confidence for 

the purpose of building a coworker model. 

With respect to pre-1973 exposures, SC&A finds that radiological control protocols for tritium 

contamination changed substantially following the 1973 incident, and that both the operations 

and the circumstances of tritium releases associated with routine pit returns and the 1974 

pressure cooker container release, respectively, were sufficiently different to make the 1974 

releases not representative of these earlier ones. Therefore, the retrospective application of this 

source term would not be supportable.
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1.0 INTRODUCTION 

Under the direction of the Rocky Flats Plant (RFP) Work Group, NIOSH and its contractors 

[Oak Ridge Associated Universities Team (ORAUT)] and the Advisory Board and its contractor 

(SC&A) have been investigating strategies for reconstructing tritium doses to workers at RFP. 

The investigations began with Special Exposure Cohort (SEC) Petition Evaluation Report (PER) 

for Petition SEC-00192 dated September 30, 2013 (NIOSH 2013). Revision 0 of the SEC-00192 

(NIOSH 2012) petition evaluation report addressed: 

All employees of the Department of Energy, its predecessor agencies, and their 

contractors and subcontractors with the potential for tritium exposures while 

working at the Rocky Flats Plant in Golden, Colorado, during the period from 

April 1, 1952 through December 31, 2005. 

In addition, Revision 1 of the report (NIOSH 2013) was expanded to evaluate: 

All employees of the Department of Energy, its predecessor agencies, and their 

contractors and subcontractors with the potential for tritium, thorium, 

uranium-233 and associated progeny, and/or neptunium-237 exposures while 

working at the Rocky Flats Plant in Golden, Colorado, during the period from 

April 1, 1952 through December 31, 2005. 

In Revision 1 of its petition evaluation report, dated September 30, 2013, NIOSH concluded that: 

...it has access to sufficient information to: (1) estimate the maximum radiation 

dose, for every type of cancer for which radiation doses are reconstructed, that 

could have been incurred in plausible circumstances by any member of the class; 

or (2) estimate radiation doses more precisely than an estimate of maximum dose. 

Information available from the site profile and additional resources is sufficient 

to document or estimate the maximum internal and external potential exposure to 

members of the evaluated class under plausible circumstances during the 

specified period (January 1, 1984 through December 31, 2005).

Revision 1 of the SEC PER provided the technical basis for concluding that tritium exposures 

could be reconstructed with sufficient accuracy. 

Prior to and following the issuance of Revision 1 to SEC Petition Evaluation Report for SEC00192, white papers were issued to discuss NIOSH’s conclusions provided in Revision 1 of the 

SEC PER that: 

...the potential for tritium exposures existed from the beginning to the end of RFP 

operations, and was associated with, and the result of, the receipt and 

reprocessing of tritium-contaminated weapons components returned to the site. 

Based on the assessment presented in this evaluation, NIOSH concludes that there 

are sufficient data and knowledge of processes and operations to support 
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bounding the associated tritium dose using the methods and information 

presented in this evaluation. 

On June 25, 2013, a white paper was issued by J.S. Bogard, E.M. Brackett, Mutty Shafi, and Dan 

Stempfley titled, White Paper: Follow-up Efforts on SEC-00192 Tritium Issues (Bogard et al. 

2013), which expands upon the technical basis for concluding that tritium doses at RFP could be 

reconstructed with sufficient accuracy. Noteworthy are Appendix 1, Parts 1 and 2, and 

Attachment A to the white paper that provide extensive information, data, and analyses that 

establish the technical underpinning for the conclusion that tritium exposures for pre-1973, 1973, 

and post-1973 time periods can be reconstructed with sufficient accuracy. The reconstruction of 

tritium exposures at RFP were divided into these three time periods because of the nature of 

tritium monitoring and discrete tritium “events” that took place at RFP, especially in 1973. 

In response to the June 25, 2013, white paper, SC&A delivered two white papers to NIOSH and 

the Board, one on September 10, 2013, and a second one on December 11, 2013, as follows: 

 Draft White Paper, Focused Review of “White Paper: Followup Efforts on SEC-00192 

RFP Tritium Issues,” Contract Number 200-2009-28555, Prepared by John Mauro, PhD, 

CHP, and Joseph Fitzgerald. September 2013. (SC&A 2013a) 

 Draft SC&A Review of Part II, Rocky Flats Tritium Dose Assignment for 1973, 

Attachment A, Contract No. 200-2009-28555, Revision 0, Prepared by Joyce Lipsztein, 

December 2013. (SC&A 2013b).

These SC&A white papers raised a number of concerns regarding the technical information, 

analyses, and conclusions regarding tritium dose reconstruction as provided in NIOSH’s June 25, 

2013, white paper. In response to the SC&A white papers, NIOSH issued a report dated May 30, 

2014 titled: 

 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, by 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. (Bogard et al. 2014). 

This SC&A white paper is provided in response to this May 30, 2014, white paper prepared by 

NIOSH and its contractors. As a preface to this white paper, SC&A would like to point out a 

number of overarching issues that might be useful to the Advisory Board in its deliberations with 

respect to this matter, as follows: 

Under SEC-00030, SEC status was granted for eligible RFP workers for April 1, 1952, through 

December 31, 1966. Under Petition 00192, SEC status was expanded through December 31, 

1983. Accordingly, the tritium issues addressed in this report are eclipsed to a certain degree by 

the SECs that have been granted, because the covered period encompasses the time periods when 

the tritium issues are of concern. The implications of these SECs are that, should the tritium 

issues be resolved in accordance with NIOSH’s position on these matters, tritium doses would be 
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reconstructed as part of partial dose reconstructions for workers not covered by the SEC. Should 

it be determined that tritium doses cannot be reconstructed with sufficient accuracy, partial dose 

reconstructions, to the extent that they can be performed, would not include reconstructed tritium 

doses. It is also noteworthy that, notwithstanding how this issue is resolved, we believe that the 

tritium exposures are quite small (i.e., in the mrem/yr range). However, judgments made 

regarding the ability to reconstruct doses with sufficient accuracy that emerge from these 

deliberations will help to advance ongoing inquiries by the Board with respect to what 

constitutes “sufficient accuracy.”
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2.0 COMMENTARY ON THE NIOSH WHITE PAPER ADDRESSING 

TRITIUM ISSUES DATED MAY 30, 2014 

The introduction to the NIOSH May 30, 2014, white paper explains that, in response to concerns 

expressed by the RFP Work Group and questions raised by the SC&A white papers dated 

September 2013 and December 2013, NIOSH revisited its existing records and initiated a 

number of follow-on investigations that included additional worker interviews and focused 

records retrieval. 

Our concerns are with respect to interpreting the relevant data and their dosimetric implications. 

As discussed at great depth in the previous white papers, issues related to reconstructing tritium 

exposures can be conveniently divided between pre-1973, 1973, and post-1973 exposures. The 

year 1973 is a watershed year because of the tritium incident that occurred in April 1973, which 

alerted all concerned that tritium exposures could have been occurring prior to 1973, a time when 

it was generally believed that the potential for tritium exposures was minimal. As a result of the 

1973 incident, considerable attention was given to the potential for chronic and possibly 

additional acute exposures to tritium associated with the receipt and processing of material from 

other weapons complex facilities after the 1973 incident. 

Because the 1973 incident is central to understanding all issues related to tritium exposures at 

RFP, we begin by first discussing the May 30th NIOSH white paper with respect to this incident 

(addressed in Appendix 1, Part II), followed by a discussion of whether post-1973 tritium 

exposure data can be applied retrospectively to pre-1973 historic exposures.

2.1 THE 1973 INCIDENT AND ASSOCIATED EXPOSURES

(APPENDIX 1, PART II) 

2.1.1 Overview 

A review of the full set of white papers with respect to this issue reveals that our concerns are a 

mix of policy issues related to applying ICRP guidance as well as issues related to data 

interpretation by time of exposure. In its June 25, 2013, white paper and in the more recent May 

2014 white paper, NIOSH contends that the methods used to reconstruct plausible upper bound 

doses to workers due to the April 1973 tritium incident are scientifically sound, because they 

follow current ICRP guidance. In brief, NIOSH was able to obtain bioassay data from two

workers about 140–180 days after the incident, and then using IMBA, reconstructed the acute 

intakes and associated doses due to the April 1973 incident for the two workers. The outcome of 

the NIOSH analysis is that the upper bound exposure from the incident was 84 mrem from an 

intake equal to 1,240 μCi. In reality, the NIOSH bounding intake was not calculated using the 

current ICRP model.

The current ICRP model for tritium after intake of tritiated water is the one described in ICRP 

Publication 78 (1997), with a clarification published in ICRP 88 (2002). The model assumes that 

for bioassay, the concentration in urine is the same as in body water and recommends that, “the 

activity concentration in urine should be calculated by dividing the whole body activity by the 

volume of body water, 42 l [liters].” 
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SC&A contends that the biokinetic models recommended by ICRP are only applicable to 

reconstructing doses if the bioassay samples were collected up to about 50 to 60 days after an 

acute exposure to tritiated water. 

Based on SC&A’s review of the data, we believe that it is not plausible for NIOSH to place an 

upper bound on these exposures unless a model is employed that accommodates reconstruction 

of tritium intakes well beyond 100 days after intake, e.g., the most-recent ICRP model, which is 

pending. Using this approach, SC&A believes that a plausible upper bound for the tritium 

exposures associated with the April 1973 incident can be assigned by using this newer ICRP 

model or similar models. 

The following table taken from SC&A’s December 2013 white paper reiterates the differences in 

the bounding doses as derived using NIOSH’s approach (current ICRP model) and SC&A’s 

approach (pending ICRP model). 

Table 1. Summary of Intake and Dose Assessments for Five Workers that had 

the Highest H-3 Bioassay Results among the Samples Collected in September 

and October 1973 

(Highest possible intakes are displayed) 

Case NIOSH Intake Date

NIOSH 

Intake 

(μCi)

NIOSH 

Dose 

(mrem)

SC&A Intake 

Date

SC&A Intake 

(rounded)

(μCi)

SC&A Dose 

(rounded)

(mrem)

A 9/19/73 38.7 2.6 04/21/73 9.0E4 6000

B 7/1/73 thru 9/25/73 28.1 1.9 7/1/73 1.6E3 100

C 8/27/73 21.3 1.4 8/27/73 21 1.4

D 4/10/73–4/25/73 1070 72 4/10/73–4/25/73 5.0E3 300

H 4/6/73 1240 84 4/6/73 5.4E3 360

The differences between NIOSH and SC&A assessments of intake and doses are caused by: 

- For Cases A and B: Different dates were assigned for the intake and New Model for 

HTO was used by SC&A; 

- For cases D and H, the same dates were assigned but new model for HTO was used. 

For case C, the same dates and same intakes and doses were assigned, because the current 

ICRP 78 (ICRP 1997) model for HTO gives similar predictions for the H-3 excretion rates as the 

new one, for about 30 days after exposure. 

As explained in SC&A’s December 2013 paper, when a worker is exposed to HTO in several 

incidents, the HTO excretion rate will be dominated by the worker’s most recent exposure. 

Sampling just after the last incident will reflect mostly the most recent exposure, hiding the ones 

that occurred months before the sampling. This could have happened, for example, with the 

exposure from Worker A, for which three different scenarios were assumed in SC&A’s 2013 

paper: exposure in September, mixed exposure in April and September, and exposure in the 

April incident. All three scenarios could be reasonably fitted with the excretion results, but the 

differences in doses between the worst case scenario and lower dose scenario were above three 

orders of magnitude. 
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SC&A’s estimated bounding dose, assumed to be the highest possible dose, was 6,000 mrem, 

assigned based on an acute intake of tritium in April 2013. NIOSH’s estimate of the bounding 

dose is 84 mrem. Some of the differences in these respective estimates are due to differences in 

the assumed time of intake and some of the differences are due to SC&A’s use of the new tritium 

biokinetic model being developed by ICRP for these types of situations. Some of the large 

differences between these two dose estimates may be resolvable if we can reconcile the 

differences in the date of exposure for Case A. However, we are still left with significant 

differences in the doses for this case and other cases due to differences in the retention models 

applied by NIOSH and SC&A, given the assumed timing of the initial intakes.

With respect to retention models, we have been in a similar situation in the past when we were 

confronted with the issue of high-fired plutonium at RFP. At that time, ICRP had not yet 

developed clearance models for high-fired plutonium, and NIOSH employed the standard Type S 

clearance model for slowly cleared plutonium for the purpose of reconstructing doses. However, 

all participants involved in the analyses agreed that high-fired plutonium existed at RFP and was 

cleared from the lung more slowly than typical Type S plutonium, indicating that the lung doses, 

as reconstructed using urine analysis data and approved ICRP models, would substantially 

underestimate the lung doses. As a result, NIOSH developed a protocol that addresses this issue 

(i.e., ORAUT-OTIB-0049) to the satisfaction of all concerned. We have a similar situation here. 

We believe that NIOSH should adopt the new models currently under development by ICRP and 

apparently widely accepted by the scientific community or, alternatively, determine that these 

doses cannot be reconstructed with sufficient accuracy at this time. It is important to note that 

NIOSH did not use the current recommended ICRP intake excretion function for deriving the 

bounding intakes for tritium, but an IMBA modification of the model, which does not follow the 

currently approved ICRP model.

NIOSH states that the bounding dose is based on the bioassay results taken on September 1973, 

from intakes that were assumed to have occurred in April 1973: 

 ...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). 

 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.

 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.

In reality, only the activity excreted in urine by two workers were used by NIOSH to calculate 

bounding intakes and doses. One of the workers submitted samples on only 3 days, with large 
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uncertainties on those results. The second worker submitted six samples, but NIOSH used only 

two samples to calculate the bounding dose. The uncertainties on the results from this worker 

are large, because the results do not follow the expected pattern of decrease with time for both 

distilled and non-distilled results. 

In addition, NIOSH points out on page 41 of its white paper that they have reason to believe that 

the date of acute intake of tritium for Case A was September 19, 1973, as opposed to April 21, 

1973, as used by SC&A (see Table 1 above). NIOSH contends that this is the best estimate of 

the date of intake, because other cases where intakes were in April 1973 did not exhibit similar 

excretion rates. These intake dates are a matter of judgment that we were not able to verify. 

Case D, for example, worked with Case A, and NIOSH assumed in its intake assumptions that it 

occurred in April 1973. Hence, we are left with a situation where it is difficult to reconstruct 

intakes that might have occurred because of the April 1973 incident unless we can agree on 

intake dates and, for some of the cases, take advantage of the new biokinetic models being 

developed by ICRP. 

2.1.2 SC&A Response to Specific NIOSH Comments 

1

st NIOSH Issue: 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 policy governing this program explicitly requires the use of currently 

approved ICRP models for the purpose of assessments and use of 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 of the results provided by SC&A 

from its 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. 

SC&A Response: SC&A agrees with NIOSH that the draft model published on the ICRP web 

for public consultation was not released yet for official use.

Notwithstanding the standing policy, NIOSH has used a model for tritium that is not the current 

ICRP recommendation for bioassay analysis. NIOSH’s bounding intake was obtained using the 

concentration of tritium in urine for case H. The intake derived by NIOSH is different from the 

intake obtained when the current ICRP model is applied. 

The current ICRP model is the one described in ICRP Publication 78 (1997), with a clarification 

published in ICRP 88 (2002, pg. 517), as reproduced below: 

BIOKINETIC MODEL FOR TRITIUM—A CLARIFICATION 

It has become apparent that there is some lack of clarity in the description 

of the retention and excretion of tritium in the forms of tritiated water (HTO) and 
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organically bound tritium (OBT) in Publications 56, 67, and 78 (ICRP, 1990

1993, and 1997, respectively). The following paragraphs are intended to rectify 

the position. 

Ingested and inhaled HTO is assumed to be translocated directly and 

instantaneously from the site of intake to blood without consideration of nuclear 

transformations in either the respiratory or gastro-intestinal tracts. From the 

blood activity is taken to be transferred, with a biological half-time of 0.25 days, 

to two whole body compartments which have biological half-times of 10 days 

(97%) and 40 days (3%). For bioassay purposes the activity concentration in 

urine is calculated by dividing the whole body activity (the activity in blood and 

both whole body compartments) by the volume of body water, 42 l. For 

dosimetric purposes, however, the activity is taken to be distributed throughout 

the whole body (excluding the lumen of the GI tract) which has a mass of 68.8 kg 

(ICRP, 1993). [Emphasis added to highlight the bioassay model). 

Table 2, reproduced from SC&A’s December 2013 white paper, shows the predicted activities of 

tritium excreted per liter of urine for a unit activity intake of tritiated water (inhalation, injection 

or ingestion). It is important to note that the values in this table are the same as the ones 

published in the IAEA 1999 (only the first 100 days were published in the IAEA document). In 

addition, the values in Table 2 reproduce the ones published by C.A. Potter (2004).

Table 2. Predicted Values (Bq/L per Bq intake) for Ingestion, Injection and Inhalation of 

Tritiated Water, using Current ICRP Model for Tritiated Water 

Time after Intake Activity Concentration Time after Intake Activity 

Concentration

days in Urine (Bq/L)

1 2.3E-02 80 2.7E-04

2 2.1E-02 90 1.9E-04

3 2.0E-02 100 1.5E-04

4 1.9E-02 110 1.2E-04

5 1.7E-02 120 9.4E-05

6 1.6E-02 130 7.7E-05

7 1.5E-02 140 6.4E-05

8 1.4E-02 150 5.3E-05

9 1.3E-02 160 4.4E-05

10 1.2E-02 170 3.7E-05

20 6.4E-03 177 3.32E-5

30 3.4E-03 178 3.25E-5

40 1.8E-03 180 3.1E-05

50 1.0E-03 190 2.6E-05

60 6.2E-04 200 2.2E-05

70 3.9E-04
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The outcome of the NIOSH analysis is that the upper bound exposure from the incident was an 

intake of 1,240 μCi, calculated using the activities excreted by case H worker, 18,800 pCi/L on 

September 30, 1973, 177 days after the exposure date assumed by NIOSH, and 23,600 pCi/L on 

October 1st, 1973, 178 days after intake. Using Table 2 values above, the predicted activities 

excreted per liter at 177 days and 178 days after an intake of 1,240 μCi are, respectively,

41,200 pCi/L and 40,300 pCi/L. Those predicted values are much higher than the real activities 

excreted by the worker; i.e., 18,800 pCi/L and 23,600 pCi/L. 

In conclusion, NIOSH’s bounding intake calculations were not obtained using the current ICRPrecommended bioassay model for tritiated water. 

The recommendation that, “the activity concentration in urine is calculated by dividing the 

whole body activity (the activity in blood and both whole body compartments) by the 

volume of body water, 42 l [liters],” is only valid for the activity equilibrated with body water 

which is retained with a half-life of 10 days. As seen in Table A.1.9 from ICRP 78 (1997), the 

maximum recommended monitoring interval for exposures to tritium after intakes of tritiated 

water is 30 days. 

In addition to the recommendations on interpretation of bioassay urine activity results , the ICRP 

has issued a biokinetic model for tritiated water to calculate doses from occupational exposure, 

described in Publications 30 (1979), 54 (1989), 56 (1990) and 78 (1997), and a clarification in 

Publication 88 (2002). All those models are based on ICRP Publication 30 (1979). 

ICRP Publication 30 (1979) and ICRP Publication 54 (1989) recommend the use of the threecomponent exponential function to represent the whole body retention of tritium after intakes of 

tritiated water, with the half-life of the 3rd component in the range of 250–550 days. Both 

publications suggest the simplification to a single exponential function, with a half-life of 

10 days, and assuming the concentration in urine is the same as in total body water: 

Concentration in urine Cu(t) = 1/(4200 exp(-0.693t/10) 

ICRP 56 (1990) recommended that the whole body retention of tritium after intakes of tritiated 

water could be represented by a three-component exponential function: 

R(t)=Ae -0.693t/T1+ B e-0.693/T2+ C e-0.693/T3

where T1 closely approximates to the turnover of body water in component A with a half-life of 

about 10 days; and components B and C represent tritium incorporated into tissue. The latter 

two components contribute to about 10% of the dose. For calculating the dose from tritium that 

entered the body as tritiated water, the three-term equation was simplified to a two-component 

exponential function, and T1 was calculated from the daily water balance (10 d) and T2 was 

calculated from the daily carbon balance (40 d). 

The ICRP Publication 88 (2002) model for retention of tritium after intakes of tritiated water 

states that: 
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Ingested and inhaled HTO is assumed to be translocated directly and 

instantaneously from the site of intake to blood without consideration of nuclear 

transformations in either the respiratory or gastro-intestinal tracts. From the 

blood activity is taken to be transferred, with a biological half-time of 0.25 days, 

to two whole body compartments which have biological half-times of 10 days 

(97%) and 40 days (3%).

The model for tritiated water described in ORAUT-OTIB-0011 (ORAUT 2004) is very similar to 

the retention model from ICRP Publication 78 (1997)/88 (2002), complemented by the ICRP 78 

(1997) assumption that about 1⁄2 of the total body water is excreted via urine. It is important to 

notice that the ICRP does not recommend the use of this model to interpret excretion rates. 

SC&A calculated predicted 24h excretion rates of tritium as a function of time after intake of 

tritiated water using this model. The model predicts that at 177 days after intake, the 24h activity 

of tritium excreted in urine should be 1.21E-5 of the intake, and at 178 days after the intake, 

1.19 E-5 of the intake. NIOSH calculated an intake of 1,240 μCi, which corresponds to 24h 

excretion of 15,004 pCi at 177 days after intake and 14,756 pCi at 178 days after intake. The 

worker’s 24h excretion was 26,320 pCi (18,800 × 1.4) and 33,040 pCi (23,600 × 1.4),

respectively, assuming 1.4 L as the daily excretion of urine. Thus, NIOSH did not use the model 

described in ORAUT-OTIB-0011 (2004).

NIOSH has used a modification of the ICRP model for tritium by using the IMBA model for 

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

(DOE 2006). The IMBA model is a modification of the ICRP recommended model, and there is 

no citation in DOE (2006) of peer-reviewed papers, using human or animal results, attesting that 

it is correct.

On the other hand, the draft ICRP publication contains many published references that show how

well the model fits real data.

On several occasions, for example, in the derivation of doses for strongly retained plutonium in 

the lungs (high-fired plutonium) for RFP, when the ICRP model could not be applied, NIOSH 

has used alternative methods for estimating bounding doses (ORAUT 2010).

In addition to issues related to the long-term biokinetics of tritium, NIOSH calculated the 

bounding dose and intake using data from two workers. The tritium concentrations in urine from 

those two workers are not reliable for use as a reference for exposures to the tritium incident in 

April 1973, because of the high uncertainties on those results. The uncertainty in the results of 

one of the workers was recognized by NIOSH:

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;
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NIOSH based the bounding intake and dose on two non-distilled samples collected from worker 

H. The uncertainties in the results from this worker are large, because the results do not follow 

the expected pattern of decrease with time for both distilled and non-distilled results.

The current ICRP model cannot be used to derive doses based on urine bioassay samples taken in 

September related to intakes in April. There are only two alternatives:

1. It is not possible to calculate bounding doses based on the April 1973 incident, as NIOSH 

claims.

2. An alternative model needs to be provided to calculate those bounding doses, using peerreviewed literature. In addition, more reliable results from tritium activity excreted in 

urine are needed to calculate the bounding dose.

2

nd NIOSH Issue: 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 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.

SC&A Response: As NIOSH has stated before, Case A worked with Case D in April. NIOSH 

recognizes that the Case D worker was exposed in April, as NIOSH has calculated its intake 

based on the April exposure. Thus, as NIOSH stated before, the Case A worker was involved in 

the [redacted] from April 11, 1973, until April 25, 1973, along with Cases D and P. It follows 

that it is plausible that the Case A worker was exposed in the 1973 incident. The fact that 

workers exposed in the same room presented different excretion rates and had different intakes is 

not unusual. As NIOSH already pointed out, the Case P worker was in the same room and this 

worker’s excretion rate was below the action level.
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In Appendix II, page 23, it is stated:

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. ... The five most-exposed individuals were identified and details of their 

potential exposures, including bioassay results, are included in the investigation 

report.

On page 24, it is stated: 

The best estimates for the five cases reviewed in Attachment A are summarized in 

Table A-5 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-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

As seen in Table A-5, NIOSH calculated intake and doses for Case D, considering that Case D 

was exposed in the April accident, when working with Case A.

In addition, the uncertainties of the bioassay results from the Case D worker are high. NIOSH 

points out on page 33:

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.

Also, the following is stated on page 31: “...because there are few samples and the results 

follow no specific pattern, there is little difference between the fits.” In conclusion, Case D 
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excretion rate results carry high uncertainties and cannot be used as proof that Case A was not 

exposed in the April incident.

SC&A has calculated doses from three possible exposure scenarios for the Case A worker. The 

differences in the assigned doses to the worker are huge: 2.7 mrem, 670 mrem, and 6,000 mrem. 

The uncertainties are quite high. The reason for this large uncertainty is the large delay between 

sample collection and the possible involvement of the worker in the April accident. As stated 

before by SC&A, when a worker is exposed to HTO in several incidents, the HTO excretion rate 

will be dominated by the worker’s most-recent exposure. Thus, sampling just after the last 

incident will reflect mostly the most recent exposure, hiding the ones that occurred months 

before the sampling. This could have happened, for example, with the exposure from Case A 

worker. As shown by SC&A, the urine excretion rate from Case A worker fitted equally well an 

exposure scenario of contamination in the September bubbler accident and a scenario of high 

intake in the April 1973 accident, followed by additional contamination in the September 

incident. Other scenarios could equally fit the urinary excretion rates results. In conclusion,

SC&A does not agree to rule out the April exposure from Case A worker, especially when 

NIOSH’s proposal is to calculate bounding intakes.

SC&A reaffirms that it is not possible to rule out Case A worker’s exposure in the April 1973 

incident.

In view of the great uncertainties in the calculation of bounding doses, aggravated by the lack of 

a correct internationally accepted model for tritium workers, SC&A cannot accept that the 

bounding doses calculated by NIOSH are applicable to RFP tritium workers.

2.2 POST-1973 EXPOSURES

In its May 30, 2014, white paper, NIOSH contends that there is no evidence that there were any

acute releases larger than that which occurred in April 1973. NIOSH cites interviews and SRDB 

documents (by Ref ID: 8265, 8790, 24164, 24165, 24167, 110900, 110901, and 110903) as the 

basis for this conclusion. The following presents a summary of the material contained in these 

SRDB files, focusing on that material that we believe is directly pertinent to reconstructing doses 

to workers associated with tritium releases that might have occurred subsequent to the large 

release that occurred in April 1973. Issues related to tritium releases and associated doses prior 

to the April 1973 incident are addressed in a separate section of this report.

There are a large number of reports presenting the results of tritium swipes, bubbler air sampling,

and urine analyses, along with engineering design descriptions, that are analyzed here to the 

extent needed to evaluate NIOSH’s conclusions with respect to this matter and also to determine 

the availability of data that would allow the reconstruction of tritium doses associated with 

releases that might have occurred following the April 1973 incident. We summarize the material 

contained in each SRDB folder in the order that they are cited in the NIOSH white paper, but 

cross-referenced between SRDB reports as required to evaluate the material and conclusions 

provided in NIOSH’s May 30, 2014, white paper with respect to post-1973 tritium exposures. In 

addition, some of the material is also relevant to pre-1973 releases and the 1973 incident, and is 

included for completeness of our review of each SRDB document. Some of the SRDB reports 
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cited in NIOSH’s May 30, 2014, white paper are not summarized here, because they are not 

especially relevant to post-1973 exposures or they refer to material that has been designated as 

“controlled” and is not provided in the SRDB. Following the descriptions of the material 

provided in each SRDB folder, we present a set of itemized findings and concerns with respect to 

reconstructing post-1973 exposures in accordance with the recommendations provided in 

NIOSH’s May 30, 2014, white paper.

SRDB 8265

This SRDB folder contains handwritten notes related to the 1968 incident (which were

apparently captured during an interview) and a newspaper article from the Rocky Mountain 

News dated December 21, 1973. The article is critical of Dow Chemical Company for not 

reporting two tritium releases that occurred post-1968, making specific reference to an 

unreported tritium release at the plant effluent release point that occurred in the spring of 1973, 

which the article reported as between 500 and 2,000 curies. Other material in the SRDB folder 

cites information stating that a tritium release that had previously occurred in 1968 was about 

1/400th of the amount of tritium that is required to be reported when such releases occur.

The material in the folder also refers to a 1974 and a 1977 release of tritium, stating that the 1968 

release involved several hundred curies of tritium. Also, the material indicates that for the 1973 

release, it was estimated that 500 to 2,000 curies were involved, and that about 56 curies were 

released to liquid effluents, 100 to 500 curies were retained in tanks and ponds on the site, and 

the rest was released to the atmosphere via gaseous effluents.

SRDB 8790

This is an important folder with respect to pre- and post-1973 tritium releases and exposures,

because it contains a report titled, “Investigation of a Tritium Release Occurring in Building 777 

on September 3–4, 1974.” The report explains that elevated tritium concentrations were 

observed in Room 452 of Building 777 and in the plenum exhaust. Normal tritium 

concentrations were < 1E-8 μCi/ml of air, and values of 37.7 E-6 and 1.1E-6 μCi/ml (37.7 and 

1.1 μCi/m3) of air were observed on August 30, 1974, and September 3, 1974, respectively. The 

report describes follow-up investigations to determine the source of the elevated tritium levels, 

explaining that the investigations revealed that the release likely occurred at a downdraft table in 

Room 452 adjacent to a glovebox serviced by plenum 205 when a shipping container, referred to 

as a pressure cooker, containing tritium-contaminated plutonium was opened. The pressure 

cooker containing the contaminated plutonium was received at RFP on July 17, 1974, and 

opened on August 30, 1974. However, the report also acknowledges that the contamination 

might have been the result of more than one tritium-contaminated object and/or residual tritium 

contamination already within the glovebox system.

Exhibit 13 of the report presents tritium air sampling data collected from Room 452 beginning 

on June 3, 1974, and continuing on an almost daily basis until September 11, 1974 (these data 

are reproduced in Table A-2 of the NIOSH May 30, 2014, report). The pattern of tritium air 

concentrations in the room is very informative and useful for evaluating the nature of the 

incident. Specifically, the airborne tritium concentrations in the room are reported as about 
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5,000 to 20,000 pCi/m3up to August 29, 1973, and then on August 30, 1974, the tritium 

concentration in the room jumps to 37,676,609 pCi/m3and by September 4, 1974, is back down 

to the normal range. This is useful information because it can be used to estimate potential 

worker exposures prior to the event, as a result of the event, and after the event ended. For 

example, the effective dose commitment for the inhalation of tritiated water by adults is 

1.83E-11 Sv/Bq inhaled, and for elemental tritium, it is 1.83E-15 Sv/Bq [See Federal Guidance 

Report No. 13 (EPA 1999)]. Workers were clearly exposed to tritium, but it is not apparent how 

much of that tritium was tritiated water and how much was elemental tritium; the difference in 

the dose conversion factors between these two different forms of tritium is large (a 10,000-fold 

difference). The magnitude of the doses can be illustrated with the following simple hand 

calculations. Assuming chronic exposure to 10,000 pCi/m3of tritiated water (i.e., a typical 

higher end value before the August 1974 incident), the effective dose rate would be as follows:

10,000 pCi/m3 × 1.2 m3/hr × 2,000 hr/yr × 1.8E-11 Sv/Bq × 1E5 mrem/Sv × 0.037 Bq/pCi = 

1.6 mrem/yr

Using the bubbler data, and the assumption that workers were exposed to the observed peak 

tritium concentration for 2 days, the doses can be estimated as follows:

37,676,609 pCi/m3 × 1.2 m3/hr × 16 hr × 1.8E-11 Sv/Bq × 1E5 mrem/Sv × 0.037 Bq/pCi = 

48 mrem

In both cases, the actual exposures to workers from tritium could have been orders of magnitude 

smaller if most of the tritium was elemental.

Exhibit 14 in the report also presents the results of the routine bioassay program. As discussed 

below, in a memo dated September 12, 1974, titled “Tritium Monitoring,” a tritium bioassay 

program was initiated that required a screening program where 1/10th of randomly selected 

Pu/Am urine samples will be tested for tritium. We will refer to as the 1/10 program. A review 

of the data reveals that the concentration of tritium in the urine of workers was above the normal 

“background” levels in Denver, reported as 470 pCi/L. The reported values for workers under 

the 1/10 program were approximately 20,000 pCi/L (ranging from 13,700 to 32,320 pCi/L) for 

the 10 samples provided in Exhibit 14 of the report (these values are consistent with the bioassay 

results provided in Table A-3 of the NIOSH May 30, 2014, white paper). The doses associated 

with this chronic level of tritium in urine can be approximated as follows:

20,000 pCi/L × 0.037 dis/sec-pCi × 6 keV/dis × 0.01 rad-g/erg × 1.6E-6 erg/MeV × 

0.001 MeV/keV × 0.001 L/g × 1000 mrad/rad × 3.15E7 sec/yr = 2.2 mrad/yr 1

 

1 After the 1974 incident, a routine bioassay program was implemented where 10% of all workers sampled 

for Pu/Am were also analyzed for tritium. Table A-3 of the NIOSH white paper gives the results of that program 

and shows that random workers had tritium concentrations ranging from 13,700 to 32,320 pCi/L. It can be assumed 

that this is representative of all workers. Hence, it can be assumed that all workers experienced annual tritium doses 

of a few mrad/yr. As used here, we assume an mrad is equal to an mrem when dealing with internal exposure to 

tritium.
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The report explains that, following the 1973 incident, a number of steps were taken to avoid 

receipt of material from other facilities contaminated with unacceptably high levels of tritium. It 

had evidently become apparent that material from other facilities sent to RFP for processing 

often contained some tritium contamination, and criteria were established for checking the 

material for tritium contamination, establishing acceptance criteria, and performing bioassays on 

at least some workers.

The report provides considerable detail describing the measurements and other investigations 

taken to better understand the levels of contamination, the conditions under which the 

contamination occurred, and the exposures experienced by the workers.

The most important part of the report, as applicable to dose reconstruction, is a description of the 

air sampling and bioassay programs that were in place at the time of the incident and 

implemented after the incident was discovered. Daily air sampling records reveal that the 

concentration of tritium in Room 452 remained relatively low (the concentration guideline was 

5E-6 μCi/ml) and spiked for a short period of time on August 30, 1974 (37.7 μCi/m3, see above 

analysis), and on September 3, 1974 (1.1 μCi/m3). Urine samples were also collected from 

workers in Building 777 at the time, with the highest concentration being 0.3 μCi/L. The report 

also explains that 1 out of 10 urine samples collected from workers throughout the plant for 

plutonium analysis were analyzed for tritium (i.e., 1/10 screening program described above). 

The results of these analyses revealed that workers in other areas had tritium concentrations in 

urine of less than 0.01 μCi/L (i.e., 10,000 pCi/L, which corresponds to about 1.6 mrad/yr; see the 

above calculation).

2

The report also summarizes the results of routine exhaust air sampling, analyses of onsite and 

offsite water samples for tritium, and also outdoor air sampling for tritium using silica gel. One 

of the important findings is that the total release to the environment from the August 1974

incident was about 1.5 Ci.

The report concludes with a number of recommendations designed to detect the possible 

presence of tritium before packages are opened and expand tritium surveys.

 

Based on its review of this document, SC&A concurs with NIOSH’s conclusion that the August 

1974 incident was of substantially lesser radiological consequence than the April 1973 incident. 

Our investigations are also consistent with the data and analyses provided in the section of the 

NIOSH May 30, 2014, white paper describing the events and data characterizing worker 

exposures to tritium post-1973 at RFP. We also find that it is likely that incidents similar to the 

August 1974 incident could have occurred before and after the 1973 incident and gone 

unnoticed. However, we note that, if the recommendations provided in the report (i.e., 

“Investigation of a Tritium Release Occurring in Building 777 on September 3–4, 1974”) were

faithfully implemented, the frequency of future incidents of this nature would likely have been 

substantially reduced.

 

2 Note that these simple hand calculations are estimates of the doses to body water. The whole body doses 

would be closer to 1.0 mrem/yr if consideration is given to the fact that about 70% of the body is water, ranging 

from a low of 45% to a high of 75% (see Guyton 1991).
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Other documents also contained in this folder include the Atomic Energy Commission (AEC)

report on this incident and newspaper articles published at the time of the incident. An

additional document in the package that is noteworthy is titled, Procedure for Completing Form 

“Authorization to Ship SS Material.” That form establishes requirements, as of October 1973, 

that are to be used by facilities that ship non-routine source and special (SS) nuclear material to 

RFP. The form requires a thorough documentation of the source and composition of the 

material, including any impurities.

Another document in this SRDB folder worth noting is a memo to Mr. W.M. Lamb, Manager, 

Rocky Flats Area Office (RFAO), USAEC, from H.E. Bowman, General Manager, dated 

September 12, 1974, and titled “Tritium Monitoring” (Bowman 1974). The memo establishes 

requirements for tritium monitoring and action levels for follow-up investigations and 

decontamination. Among other requirements, this is the memo that resulted in the tritium 

screening program, where 1/10th of randomly selected Pu/Am urine samples will be tested for 

tritium.

SRDB 24164

This SRDB folder contains tritium effluent inventory reports for the 1980s. Since this 

information has limited applicability to worker dose reconstruction, the material was not 

evaluated in detail, except to note the concentration of tritium in the exhaust. For example, for a 

limited number of effluent samples collected in 1981, the concentrations ranged from less than 

the minimum detectable limit (MDL) of 50 pCi/m3to 216,670 pCi/m3. The implications are that 

the potential for tritium exposures of workers appears to be highly variable if one assumes that 

the concentrations of tritium in the exhaust lines are related to the concentrations of tritium in the 

air where workers are located. Judgments on the significance of these concentrations can be 

made by using the relationship described above, where chronic exposure to a tritiated water

airborne concentration of 10,000 pCi/m3is associated with a worker annual effective dose of 

about 1.6 mrem.

This SRDB folder also contains a 1976 report titled, Estimates of Maximum Tritium Releases to 

the Atmosphere from Operations at Rocky Flats (March 1976). The introduction of the report 

explains that routine effluent monitoring was triggered in part because of the large release of 

tritium (500 to 2,000 Ci) that occurred in 1973. The report explains that the total tritium released

in 1975 was 1.5 Ci. The report concludes that, with the controls implemented subsequent to the 

1973 incident, operations may be easily controlled to a release of less than 10 Ci/yr.

The March 1976 report certainly provides evidence that the 1973 release was an unusual one-ofa-kind release, at least subsequent to the 1973 release. In addition, it appears that considerable

data are available to place a plausible upper bound on the incident that occurred in August 1974, 

if the data are representative of the locations of workers that opened shipping containers. One 

could also argue that the programs implemented in accordance with the September 12, 1974,

memo likely reduced the intensity and frequency of tritium incidents, such as the one that 

occurred in August 1974.
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SRDB 24165

This SRDB folder contains material that is duplicative of the material provided in SRDB 24164.

SRDB 24167

This SRDB folder does not contain any material, but refers the reader to controlled documents.

SRDB 110900

This SRDB folder does not contain any material, but refers the reader to controlled documents.

SRDB 110901

This SRDB folder includes a report addressing the 1973 incident and provides no new 

information pertinent to either the incident or post-1973 exposures to tritium.

SRDB 110903

This SRDB folder contains a report investigating elevated tritium releases that occurred in Room 

154 in 1977. This is an interesting report, because it refers to a fire in a glovebox that was being 

used in hydride-oxidation runs. Reference is made to effluent tritium concentrations in exhaust 

air of 1,500 μCi/m3. For reasons discussed above, this concentration of elemental tritium or 

tritiated water is of little dosimetric significance. However, the fact that RFP was handling metal 

tritides is of interest, because the doses associated with the inhalation of metal tritides is much 

greater than for tritiated water.

SRDB 111095

This SRDB file contains, among other information, what we believe is tritium bubbler air sample 

data collected from 1977 to 1981 for different buildings. It is difficult to determine specifically 

where each sample was taken, but it also appears that through further research, we should be able 

to determine the sample locations. We believe that this could be an important issue, because we 

do need assurance that the airborne tritium concentrations, as determined using the bubbler data, 

are representative of the airborne tritium concentration in the breathing zone of workers, 

especially workers involved in opening packages at the downdraft tables.

The samples appear to be taken continuously over an approximate 3-day period before the water 

in the bubbler is analyzed for tritium. We suspect that the analytical method employed liquid 

scintillation detection. The tables are simply a series of columns as exemplified by the following 

first row on the first readily legible page of the file:

Date On Date off Sample # Volume m3 Water Analysis

527 5-30 201 203 8.74 125 L=10 pCi/m3

From the headings of the tables, this example is from a sample taken in 1977 and the standard 

procedure was to collect the samples on Monday, Wednesday, and Friday. It appears that a total 
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volume of air sampled over the approximate 2 or 3 day period was 8.74 m3, the total volume of 

water in the bubbler was 125 ml, and the result of this analysis was less than 10 pCi/m3of tritium 

in the air over the time period and at the location where the sample was taken.

Scanning through a large number of tables (there appear to be over 1,000 pages, with some pages 

containing about 70 data points and others with only 15 data points), 1,490 pCi/m3between 

February 6, 1978, and February 8, 1978, was the highest observed value (we did not look at 

every table), with most values below 100 pCi/m3. Again, the dosimetric significance of these 

concentrations is minimal, as exemplified by the above example calculations, as long as the data 

are representative of the concentrations of tritium in the breathing zone of workers.

SRDB 122466

There are handwritten notes in this folder from a February 5, 2013, interview with a worker (who 

first worked at RFP for [redacted] and then again [redacted]), indicating that tritium analysis 

was performed using liquid scintillation detection, because reference is made to a “scintillation 

cocktail” that was used to analyze for tritium in 1979 and later.

SRDB 122712

This SRDB folder contains a lab analysis report for 57 tritium bubbler samples analyzed for 

tritium in 1997 using liquid scintillation detection (LSD). The report presents a detailed 

description of the analytical methods and QC program. The results appear to indicate that all the 

samples were below or occasionally slightly above the detection limit of about 0.8 dpm/ml. We 

suspect that the 0.8 dpm/ml value refers to a ml of water in the bubbler. We are not sure how to 

convert this concentration in the bubbler water to airborne tritium concentration from the 

information provided in the file.

SRDB 111301 and SRDB 122907

These SRDB files contain similar information. Memos are provided dated October 21, 1974,

stating that swipe surveys of shipping containers revealed many containers with tritium 

contamination. On this basis, the memo in SRDB 111301 requires that additional requirements 

be established with respect to non-routine SS and non-SS material. The memo requires that the 

shipper not only verify the tritium level of the material sent, but must also check the tritium level 

of the shipping container, and a statement to that effect must be affixed to the shipping form. 

The memo also states that this protocol must be followed until RFP develops facilities for 

handling tritium-contaminated shipments, which is stated as expected to be available in 1975.

SRDB 122550

This SRDB folder presents a summary of an interview with a worker who worked at RFP from 

[redacted]. The worker had many jobs at RFP and was able to describe operations related to 

opening packages where tritium exposures could have occurred. The worker explained that 

packages arrived as two pits in a 10-gallon drum, and both were inside a 55-gallon drum. The 

worker explained that two large outer drums were opened per shift, i.e., six drums per day, and 
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that bubblers were used when the drums were opened. The worker also states that bubblers were 

used beginning in 1965 and no tritium measurements were made before 1965. Each 55-gallon 

drum was opened in a tent next to the room exhaust, and there was a bubbler positioned in front 

of the intake plenum of the exhaust system. The smaller drums were opened in another room,

and no bubblers were used when opening the smaller drums and removing the pits and placing 

them in a glovebox for processing. The interviewee explained that the opening of the inner box 

and its transfer to the glovebox was the time when unmonitored tritium exposures could have 

occurred. Also, the interviewee said that no urine analyses were performed. However, bubblers 

were used for monitoring tritium off-gas in Room 123 of Building 777. The worker mentioned 

that one or two times a year, elevated tritium was observed during off-gassing. This description 

is consistent with the information provided on page 36 of the NIOSH May 30, 2014, white paper.

SRDB 111267

This SRDB folder contains a memo dated September 12, 1974, to Mr. M.W. Lamb, Manager, 

RFAO, USAEC from H.E. Bowman, General Manager, titled “Tritium Monitoring.” This memo 

is described above under SRDB 8790.

SRDB 111288

This SRDB folder contains a memo dated September 16, 1974, from Dow Chemical personnel to 

R.D. Forest. The memo describes the people responsible for minimizing the potential for 

carrying tritium contamination from inside a line into a room. A separate memo in this SRDB 

folder dated September 12, 1974, presents specific action levels and protocols for handling 

tritium contaminated lines. These memos are only marginally applicable to the issues at hand,

because they address primarily the handling of contaminated lines after the contaminating event 

occurred. However, the second memo also provides instructions for additional tritium 

monitoring in areas where employees are working. Also, action levels were set at 50,000 pCi/m3

(5E-8 μCi/m3). The memo also provides instructions regarding the 1/10 bioassay program 

described above and action levels for tritium swipe samples. This is an important memo,

because it reveals that specific direction was given after the August 1974 incident to augment 

tritium sampling with the objective of monitoring workers, and not just assessing tritium that 

might have been released via effluent lines.

SRDB 8789

This SRDB folder contains a memo to William A. Lamb, Area Manager, RFAO, ERDA from 

R.O. Williams, Jr. Vice President and General Manager dated November 12, 1975 (75-RF-0818). 

The memo summarizes tritium surveillance, providing information on the quantity of tritium 

stored at the facility at various locations (Buildings 123, 559, 779, 881, and 991). The quantities 

ranged from 100 mCi to 7 Ci. The memo is indicative of the quantities of tritium at the facility 

at the time, which were relatively small.
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SRDB 111106

This SRDB folder contains a report dated December 16, 1974, describing a tritium monitoring 

plan, which consisted of swipe samples inside hoods and glovebox lines, different rooms and 

buildings, frequency of sampling, and action levels. It also provides instructions for effluent 

stack sampling.

2.2.1 Observations and Conclusions Regarding Post-1973 Exposures based on Review of

the SRDB Folders

1. Based on the review of the above SRDB folders, SC&A concurs that there do not appear 

to be any incidents post-1973 where the doses to workers could have been greater than 

the doses that might have been associated with the April 1973 incident. In addition, there 

are considerable air sampling data, and a limited amount of bioassay data post-1973, that 

indicate that a plausible upper bound could be placed on the tritium exposures that 

workers might have experienced after the 1973 incident. However, one of our concerns 

is whether the locations of the bubblers are representative of the airborne tritium 

concentrations at the locations of the potentially exposed workers. Also, one of the 

conclusions on page 20 of the May 30, 2014, white paper states that, “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.” This 

conclusion is not consistent with the material provided in SRDB 8790, where the 

potential doses involved in the August 1974 incident were certainly higher than 

1 mrem/yr, and it is unclear whether more than one of these incidents might have 

occurred. This observation also applies to the conclusion on page 22 of the NIOSH white 

paper that the bioassay data support a conclusion that the doses to workers from tritium 

for 1974 and 1975 were zero for everyone.

2. In a related matter, Table A-2 of the NIOSH May 30, 2014, report and its supporting 

SRDB 8790 document, provide detailed air sampling data for Room 452 related to the 

August 1974 release. Our question is, were there other rooms where containers were 

opened, and if so, are there any air sampling data, swipe data, or effluent data that

demonstrate that tritium releases did not occur at those locations? It appears that Item 2,

under the section titled “Comment Reponses” beginning on page 36 of the NIOSH May 

30, 2014, white paper provides information pertaining to this issue, but it is not clear that 

there is a high level of confidence that exposures to tritium associated with opening 

containers can be characterized and bounded.

3. The NIOSH conclusion regarding doses post-1973 being less than 1 mrem/yr is likely 

based on the 1/10 bioassay program, but it is not apparent that the workers included in the 

bioassay program were bioassayed at a frequency that would have detected an incident. 

In addition, there are questions regarding the locations of the bubblers with respect to the 

degree to which those data are representative of the airborne tritium concentrations where 

workers might have been exposed to tritium. There are a substantial number of smear 

samples, but it is not apparent that the results of smear samples could be used to validate 

the conclusions that exposures to workers post-1973 were less than 1 mrem/yr.
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4. Another concern we have regarding the post-1973 air sampling data is we did not find 

any reports that used two bubblers in series to confirm the efficiency of the bubbler for 

collecting tritium. We note that the efficiency of bubblers can be affected by humidity, 

the flow rate of air through the bubbler, and how long the bubbler is on line before 

analysis. Some discussion of bubbler efficiency is required.

5. Drawings of the bubbler are provided in SRDB 122779 and 122791, and handwritten 

notes from an interview that discusses the location of the bubblers is provided in SRDB 

122466. With respect to bubbler location, the notes in these SDBRs state that, “prior to 

1980, bubbler contents from exhaust plenums went to 123. ... In early 80’s (81 or 

thereabouts) they put a bubbling unit where components were disassembled.” The 

implications of these statements are that, prior to 1981, the bubblers may not have been 

placed in the optimum location for providing data useful for dose reconstruction. This 

matter requires further investigation and discussion.

6. We would also like to hear more about the handling of metal tritides at the facility and 

the exposures associated with incidents, such as the incident that occurred in 1977 in 

Room 154 where metal tritides might have been involved.

7. Table 1 of the NIOSH white paper presents a thorough summary of the reports addressing 

bubblers, but not bubbler efficiency. However, Table 1 of the white paper does confirm 

that a substantial amount of airborne tritium concentration data was collected following 

the 1973 incident that might be useful in reconstructing potential tritium exposures to 

workers post-1973 if they were located where workers might have been exposed to 

tritium. We would like to reiterate the need to address bubbler location.

8. Page 22 of the NIOSH white paper concludes that the doses after 1975 should be 

assigned as zero for the same reasons given for 1974. We are concerned with this 

conclusion for the same reason as given above regarding 1974 exposures.

9. Page 40 of the NIOSH May 30, 2014, white paper explains why zero dose is being used 

as a coworker tritium dose for workers in 1974 (provided in response to a question posed 

by Dr. Ziemer). For the reasons discussed previously, we believe the basis for assigning 

zero doses to workers in 1974 and also 1975 is not well founded because of uncertainties 

with respect to where the bubblers were located relative to the breathing zone of the 

workers, and also the very limited amount of bioassay data collected under the 1/10 

program.

2.3 PRE-1973 EXPOSURES (APPENDIX 1, PART I)

As observed in the NIOSH May 30, 2014, white paper (Part I) and in the preceding June 25, 

2013, paper, which it repeated: 

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 
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conditions at the time of 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. [Emphasis added]

Given the lack of useable tritium characterization and release data for the pre-1973 period, 

NIOSH has proposed to apply data from the only fully documented tritium release from a 

shipping container at RFP, a release that occurred on August 30, 1974, at one of the production 

facilities. The underlying assumption for retrospective use of this data is that the release is 

representative of such container releases throughout the pre-1973 RFP operating history, and can 

be considered bounding of all such releases in terms of source term and potential worker 

exposure. Based on air sampling and bioassay data collected at the time, NIOSH concludes that 

the resulting dose from the 1974 release would be less than 1 mrem (0.15 mrem), which 

translates into an annual occupational dose of 37.5 mrem/year, assuming one such incident per 

day for 250 days per year.

To support its use of the 1974 data in a retrospective application prior to 1973, NIOSH has 

highlighted six key supporting factors, which SC&A has already addressed in its 2013 white 

papers, and offers the following re-evaluation given the reissued June 2014 white paper.

1. NIOSH (excerpt): 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 [taken to be less than 

1 mrem per year based on background measurements made prior to the 1974 event].

SC&A Response: SC&A agrees that the background for tritium was very low at RFP, 

even after the 1973 event. However, it is not clear what the baseline background level 

would have been for tritium within the affected production facilities. For example, a 

contemporary assessment of the 1974 release by Boss and Hobbs (1974) notes that given 

that a “specific cause of the tritium release could not be absolutely determined...” it was 

possible that “tritium contamination residing in glovebox lines, exhaust and supply 

plenums from the previous major tritium incident in 1973 cannot be totally discounted as 

the cause or at least being contributory.” It is further noted that “elevated room air 

concentrations of tritium were detected in the special assembly area of Building 776/777, 

although these elevated concentrations could not be related specifically to the time period 

of the effluent air releases.” The authors go on to note that “cross-contaminated sampling 

apparatus, resulting in the loss of data, points to the extreme care that must be exercised 

to obtain valid sample results.” These findings are supported in the RFAO investigation 

report (RFAO 1974), which notes that:
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Exhaust from the Special Assembly Glovebox Line in room 452 [the one 

implicated in the release] is currently handled by plenum 206. However, 

during the period from February 11–August 7, 1974, exhaust air from 

[this line] temporarily was exhausted through plenum 205 because of the 

construction of new plenum 206. Therefore, exhaust air from [this line]

contributed to significant tritium contamination within both exhaust 

plenums 205 and 206.

Under the circumstances detailed in SRDB 24165 and SRDB 8790, with confirmed 

tritium contamination in the facility and significant cross contamination in exhaust lines, 

a valid determination of background workplace tritium levels for the 1974 event is 

difficult to establish, although the annual background dose involved would undoubtedly 

remain in the lower mrem range.

2. NIOSH (excerpt): 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. 

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.

SC&A Response: While the actual quantity of tritium released from the containers in 

question (versus from residual systems contamination) is seriously open to question (see 

SRDB 24165), the magnitude of the release is clearly less than that of the 1973 event. 

Whether it was “typical” of historic (pre-1973) handling of shipping containers is more 

conjectural, given the lack of pre-1973 radiological monitoring and controls, paucity of 

actual measurements and their reliability, and interview accounts of opening containers 

without the benefit of nearby tritium monitoring or active ventilation (see SRDB 

122550). It is also clear that RFP accepted both “SS” containers from Pantex and “nonSS” containers from elsewhere in the AEC complex, and that the containers themselves 

arrived contaminated. For example, the 1974 event involved non-SS shipped parts from 

Battelle Northwest Laboratory, in which one of the containers had contamination that 

actually exceeded the parts contained in it, suggesting that it remained in use 

contaminated.

While this may lead one to assume that 1.5 Ci could be an overestimate given this degree 

of uncertainty over source term, it also brings into question the validity of using the 1974 

release source term as “typical” or representative of all pre-1973 tritium contamination 

releases from SS and non-SS containers received at RFP from a range of weapons 

complex sites, including Savannah River Site (SRS), Hanford, Los Alamos National 

Laboratory (LANL), Lawrence Livermore National Laboratory (LLNL), Pantex, and 

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

SC&A Response: While it is true that in both cases (pre-1973 and 1974 events) tritium 

was released to the workplace environment, the exposure conditions were widely 

different. This is backed up by an interview with a knowledgeable operations worker 

who noted that they had followed a two-step procedure for opening pit containers at RFP 

(see SRDB 122550). The containers consisted of two pits apiece packed in 10-gallon 

cans, which were themselves packed inside of a 55-gallon drum. Two of the 55-gallon 

drums were opened per shift for a total of 6 drums for the 3 RFP operating shifts per day. 

The opening of these outer drums was apparently performed in a tent near a room tritium 

bubbler adjacent to an exhaust plenum. However, the inner containers were subsequently 

opened in another room without the benefit of an alarming bubbler with a clear exposure 

potential to any tritium contamination as the pits were manually moved from the inner 

cans to the glovebox entry port. This interviewee and other workers confirmed that no

one was monitored for tritium before 1973, with smearing limited to alpha smears of 

surfaces, alpha monitoring of any loose contamination, and gamma and neutron 

monitoring of the inner cans and pits (a handheld tritium “sniffer” was available for nonroutine use). It was confirmed in this and other interviews that tritium bubbler alarms 

occurred a few times a year, although actual breathing zone measurements or room 

contamination levels were never established.

As noted in SRDB 8790, the pressure cooker containers were opened over a downdraft 

table with workers following a formal bag out procedure requiring that the operators wear 

protective clothing, a full mask respirator, and several pairs of surgeons’ gloves, all of it 

monitored by scintillation-based air samplers located nearby. Prior to 1973, pit returns 

were handled without respiratory protection, without monitoring (during the second step), 

and without active local ventilation (second step).

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

SC&A Response: It is clear that tritium oxide (HTO) is of greater dosimetric concern,

and that the circumstances of the 1973 release (involving hydriding and flame oxidation) 

accentuated its formation. However, the presence of the hydriding operation at RFP (it 

was one of two process lines involved with site returns, with the other being an acid 

dissolution process, during which no hydrogen was generated, therefore, obviating the 

need for flame oxidation), the acceptance of both SS and non-SS containers of various 

weapons complex origins (and therefore, tritium in both forms cannot be ruled out), and 

the receipt of pits, parts, and other materials that had residual tritium contamination of 

unknown origins, raises doubt that all contamination at RFP before 1973 only involved 

elemental tritium. In fact, SRDB 24165 even suggests that the shutdown of the 

ventilation air dryer in the RFP production facilities the week before the 1974 release,

coupled with abnormally high humidity at RFP, may have contributed to the tritium 
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contamination in the process lines, suggesting the formation of HTO.3 It seems clear that 

the 1974 event involved an unknown mixture of elemental tritium gas and HTO.

One interviewee (SRDB 22629) noted that while RFP had, in the past, processed similar 

parts before from the Lawrence Livermore Laboratory (LLL) operation responsible for 

the 1973 release, the unique meteorological conditions at the time (heavy snow) may 

have been the difference in the environmental contamination experienced. The 

interviewee, a knowledgeable [redacted], offered that he believed that RFP might have 

had other such releases [that were not detected]. The use of the hydriding process with 

flame oxidation for parts contaminated with tritium would have led to the generation of 

HTO—it just would not have been easily detected in the environment without the 

meteorological inversion and participation experienced in 1973, and the offsite sampling 

that took place then.

5. NIOSH: The tritium was released from a contaminated shipping container, which was 

procured by RFP in 1970 and can be taken as representative of shipping containers in use 

prior to 1973.

SC&A Response: As noted earlier, while the container may have been an RFP 

prototype, it contained assorted parts from Battelle Northwest Laboratory (BNWL), and 

had residual contamination (in one container) that was higher than the parts inside, 

suggesting a prior contamination source. The two containers in question during the 1974 

release were of the “pressure cooker” variety, which were not typical of most of the 

containers in routine use at RFP before 1973. During that timeframe, most of the 

potentially contaminated materials consisted of returned pits from Pantex and Burlington, 

which were overpacked (as described above) in an outer 55-gallon drum and within an 

inner container, and were only smeared for alpha contamination prior to opening.

6. NIOSH: 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.

SC&A Response: The fact that the two “pressure cooker” shipping containers were 

opened on a downdraft table by workers in protective clothing with full-face respirators 

with nearby active tritium scintillation monitoring and readily available worker bioassay 

clearly separates the 1974 event from the RFP operating and monitoring practices of the 

pre-1973 era. As noted earlier, containers with returned Pantex pits (the vast majority of 

containers handled) were opened by hand, with limited ventilation, in a two-step process 

where only the first “opening” was covered by an alarming tritium bubbler located on an 

exhaust plenum [and this monitoring practice, itself, only began in the late 1960s, 

according to expert interviews (see SRDB 122515, 122625, 122550)], with the second 

 

3 As pointed in the RFAO investigation report (SRDB 8790), “moisture is one known means of releasing 

tritium from surfaces on which it is absorbed, as it readily exchanges with the hydrogen atoms associated with water 

molecules.”
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inner can opening conducted without any monitoring and negative exhausting, as the pit 

was moved by the handler into the glovebox port.

The new post-1973 approach for controlling tritium at RFP is evidenced in the October 5, 

1973, procedures (Putzier 1973) that were issued to “express the generalized philosophy 

and approach to be used by Health Physics Operations in making recommendations for 

tritium contaminated items.” These procedures provided action levels for contamination 

smear results, protective clothing requirements (including supplied air hood), and work 

planning.

As further noted in the RFAO investigation report (SRDB 8790):

Following the 1973 tritium incident, procedures were established to 

prevent the receipt of any tritium[-]contaminated SS material from being 

sent to Rocky Flats. The procedures apply to all non-routine shipments 

(excludes site returns from Pantex and Burlington) and requires the 

shipper to provide a material history and identification of any radioactive 

contamination.

Therefore, procedures were in place for the containers in question in 1974 that included 

shipment certification, respiratory protection, smearing, container “sniffing,”

4

air 

sampling, and event-driven bioassay, versus a single exhaust plenum bubbler for pre1973. SC&A finds these work practices and controls to be dissimilar between 1974 and 

pre-1973.

Conclusion: SC&A concludes that use of the 1974 tritium release to bound all pre-1973 

container releases is not valid for the following reasons, as previously discussed:

 The radical difference in the containers handled (“pressure cookers”), source term 

involved (BNWL parts), ventilation (“downdraft table”), air monitoring (room air 

samplers), and radiological controls (personnel monitoring, protective clothing, 

respiratory protection, work planning) makes the 1974 event not representative of the 

vast majority of pre-1973 container handling at RFP, which consisted of standard pit 

containers, Pantex returned pits, no local ventilation, an alarming tritium bubbler at a 

room exhaust plenum (only after late 1960s), and little personnel protection.

 

 The source and composition of the tritium released is also in doubt, given the detected 

presence of tritium, prior to the August 30, 1974, release in the facility glovebox lines, 

and exhaust and supply plenums, which pointed to cross-contamination from residual 

tritium sources related to the 1973 event, not solely the containers in question. Likewise, 

the presence of HTO outside of the 1973 event cannot be discounted, given the unusual 

environmental and operational conditions at the time of the 1974 release, nor can it be 

 

4

It is noteworthy that the pressure cooker containers involved in the 1974 event were to have been 

monitored by a tritium “sniffer” prior to handling, but were not because the contractor had suspended such 

monitoring due to increasing uptake of tritium by the radiological technician responsible for conducting it for all 

arriving containers. 
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discounted given the historic pre-1973 use of hydriding processes involving flame 

oxidation on previously received components.

While the 1973 release is undoubtedly the largest in RFP history, the 1974 event cannot be 

considered bounding of all pre-1973 container releases, given the inability to demonstrate that it 

is sufficiently representative of the conditions under which those releases took place. This is 

coupled with the source term issues and questionable sampling data that stemmed from the 

release, bearing on whether the parameters being used are sufficiently accurate for this critical 

application. The 1974 release offers a relatively substantial container release coupled with 

comprehensive tritium measurements and bioassay results stemming from upgrades made in the 

aftermath of the 1973 event. However, if it cannot be sufficiently normalized with the 15 years 

of prior operations involving returned pits, it becomes a “large” number for bounding purposes 

with insufficient relevancy to the historic operations involved.
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Health for factual accuracy or applicability within the requirements of 42 CFR 82.

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Health, June 25, 2013.

Bogard, J.S., E.M. Brackett, Mutty Sharfi, and Dan Stempfley, 2014. Follow-up Efforts on SEC00192 Rocky Flats Plant Tritium Issues, Rev. 1, National Institute for Occupational Safety and 

Health, May 30, 2014.

Boss, M.R. and F.D. Hobbs, 1974. Tritium Release – Circa 1974, ECR 317311-105, Rocky 

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5 The most recent and complete information contained in this report is available on a CD: FRG13_DB, 

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