Rocky Flats Plant

Special Exposure Cohort

Petition Evaluation Report

Stuart Hinnefeld

Director

National Institute for Occupational Safety and Health

Division of Compensation Analysis and Support

September 2012

Denver, CO
Petition Overview

 August 23, 2011: NIOSH received an 83.13

petition for period of April 1952 to Decem

2005 (for tritium exposures)

 February 9 2012: Petition qualified for

evaluation

 September 5, 2012: Evaluation Report app

 SEC class recommended: None
Background

 Rocky Flats Plant (RFP)

• Located in Golden, Colorado

• 384‐acre site, surrounded by ~6000 acre buffer zon

• Approximately 6000 people maximum workforce (

• Located in Golden, Colorado

 RFP primarily produced plutonium triggers fo

recovered plutonium from, nuclear weapons

• SEC00030 evaluation did not adequately address t

• Work with some pits and special return material e

some tritium potential
Proposed and Evaluated SEC C

 Petitioner‐Proposed class:

All workers employed at Rocky Flats from April 1

to December 31, 2005

 Class Evaluated by NIOSH:

All employees of the Department of Energy, its

predecessor agencies, and their contractors and

subcontractors with the potential for tritium expwhile working at the Rocky Flats Plant in Golden

Colorado, during the period from April 1, 1952 t

December 31, 2005.
Petition Basis and Concerns

 Unmonitored workers

• Petitioner provided information and affidavit stat

in support of the petitioner’s position that there w

times when the petitioner was not monitored, speas it related to tritium.

• NIOSH determined that it has access to personnel 

monitoring data for Rocky Flats workers, specifica

applicable to tritium at the time of the 1973 incid

• NIOSH determined that a review of tritium record

data for all time periods was appropriate, and suf

support qualifying SEC00192 for further evaluatio
Sources of Available Informat

 Rocky Flats Plant TBDs (ORAU‐TKBS‐0011‐

through ORAU‐TKBS‐0011‐6)

 NIOSH Site Research Database documents

 DCAS and ORAUT technical bulletins Case files in NIOSH OCAS Claims Tracking S
Additional Information Obtain

During SEC Petition Evaluatio

 Interviews with former RFP workers Worker Outreach meetings Classified records reviews
Previous Dose Reconstructio

NIOSH OCAS Claims Tracking System

Information available as of January, 2012

Totals include claims that are in the earlier SEC classes

 RFP claims submitted to NIOSH 16 Dose reconstructions completed,

or claim otherwise dispositioned, for energy

employees in the evaluated class

16

 Claims containing internal dosimetry 14 Claims containing tritium bioassay 12
Potential Tritium Exposures

 Tritium containers

• First two designs (pure fission weapons) phased out 

1957

• Later design (thermonuclear) had tritium but it was c

at other sites

 Neutron generators

• Used tritium targets (total inventory in all machines 

• Located in five locations on‐site

 Radiation interactions

• Interactions between transuranics and B, Be, and N c

produce tritium
Potential Tritium Exposures—

 Contaminated Returns

• The years when contaminated returns could ha

existed in the MED/AEC complex is not certain; possible they were not at RFP until late 1960s

• Conservative assumption would be that release

from contaminated returns could have occurre

any time since RFP plutonium operations comm

in 1953
Source Term for Exposure

 Neutron generators and radiation interacti

deemed significant

• Tritium (a total of 241 Ci over the operational 

through 1973) in neutron generator targets spacross the site in five different areas

• Estimates of total tritium generated from radia

interactions range from 0.2 – 3.2 Ci/yr

 Contaminated returns deemed a significan

exposure risk
Source Term for Exposure—co

 1973 incident involving contaminated return prod

the highest recorded tritium contamination levels

 RFP receipt records from 1970‐1974 indicated alm

shipments. Four from LLNL were considered likely 

have been contaminated with tritium

• April 1969 ~60 Ci• March 1971 ~50 Ci

• December 1971 ~30 Ci

• March 1973 500‐2000 Ci
Source Term for Exposure—co

 In the 1979‐1980 time period an evaluatio

1700 LANL ‘site return’ pits, retrieved from

stockpile, showed very little tritium (from – 468 mCi/m3)

 In 1984 radiography of pits (to determine

structural integrity) was a routine aspect o

testing, and was sufficient to determine lik

tritium contamination in a pit received fro

LANL (returned to LANL for disassembly)
Incidents

 Normal site returns were processed by aci

dissolution

 Special returns were ‘hydrided’ and the of

was burned and filtered before release to 

atmosphere – this would result in HTO rath

than elemental tritium
Incidents—cont.

 Special project incident in 1968 released ~

of tritium (no detectable environmental im

due to chemical form of tritium – element

tritium release versus tritiated water)

 1973 incident was a special return, and the 

gas was burned resulting in production of 

and the release of 500‐2000 Ci

 1974 incident – tritium release from a

contaminated shipping container amounte

an estimated 1.5 Ci
Monitoring

 Prior to 1973 incident, RFP did not routine

collect bioassay for tritium (as it was not anticipated as a component of their missio

• Handful of tritium samples in SRDB prior to 19

(~30)

• Special sampling due to 1973 incident well‐ documented, 148 workers monitored, 5 deem

have ‘potentially significant exposures’

• Routine sampling program put in place after 1

incident, abandoned for job‐specific sampling because the results showed zero positive samp
Monitoring—cont.

 A review of HP, IH, and EM reports for all y

indicates limited tritium results

• Tritium sniffers• Triton portable and fixed air monitors

• Swipe and smear surveys
Monitoring—cont.

 Post‐1973, procedures were implemented 

sample workers working a job involving m

than 1 mCi tritium

• One document lists 16 names of personnel 

sampled; tritium sampling data for 13 of th

were found in the SRDB
Approach to Dose Reconstruct

 Although there were several incidents rela

tritium at RFP, only the one in 1973 resultesignificant personnel exposure. Involvedpersonnel were carefully monitored, result

numerous, and are available in the SRDB

 Because of the size and chemical composit

this 1973 release (HTO versus elemental tr

NIOSH considers this to be a bounding sce
Approach to Dose Reconstruct

 Rocky Flats started processing the contaminated r

in April 1973, not knowing that they were contam

 In June 1973, the state of Colorado detected tritiu

surrounding surface waters and notified Rocky FlaRocky Flats maintained that it could not have bee

source

 In September 1973, Rocky Flats started investigat

found tritium in multiple unexpected locations in 

workplace
Approach to Dose Reconstruct

 Bioassay samples were collected from 148 emplo

who were judged to have been potentially expose

tritium

 Dose estimates were prepared for employees wit

highest bioassay results, using “worst case” and “

fit” approaches. The “worst case” result of 753mrem/year will be adopted as the internal tritium 

for all workers from the beginning of Pu operationthrough 1973 to account for potential doses from

unidentified, but presumably smaller, earlier occuof contaminated returns
Approach to Dose Reconstruct

 Because of the extent of time over which t

exposures likely occurred (from receipt in A

until investigation in September), tritium

exposures from this incident were more ch

in nature, rather than single acute exposur

This chronic exposure experience is analogwhat would have occurred if there were ot

unidentified receipts of contaminated retu
Evaluation Process

 Two‐prong test established by EEOICPA an

incorporated into 42 C.F.R. § 83.13 (c)(1) a

C.F.R. § 83.13 (c)(3):

1. Is it feasible to estimate the level of radiation 

of individual members of the class with sufficiaccuracy?

2. Is there a reasonable likelihood that such radi

dose may have endangered the health of mem

the class?
Feasibility of Dose Reconstruct

The process and incident information, along administrative controls and environmental, 

and personnel sampling, provide sufficientinformation to estimate doses associated w

tritium work at the Rocky Flats Plant
Summary

Feasibility Findings for Titanium Alloys Manufacturing Pet

January 1955 – December 1956

Source of Exposure Reconstruction

Feasible

Reconstru

NOT Fea

Internal X

‐ Tritium X

External N/A