Rocky Flats Plant

Special Exposure Cohort Petit

Evaluation Report Rev. 1

LaVon B. Rutherford, CHP

National Institute for Occupational Safety and Health

Division of Compensation Analysis and Support

October 2013

Westminster, CO
Background

 September 5, 2012 ‐ SEC‐00192 Evaluation R

(ER) Rev. 0 for Rocky Flats Plant (RFP) issued

 September 18, 2012 ‐ NIOSH presented ER a

Advisory Board meeting in Denver, CO

• NIOSH’s recommendation was not to add a class

• Advisory Board concluded follow‐up required, in

classified interviews and classified document rev
Background–cont.

 Since the ER presentation, NIOSH conducted a v

follow‐up efforts that identified additional issu

 Three work group meetings held in 2013 to disc

these issues (Feb. 20, July 8, and Sept. 12)

 NIOSH revised the ER to incorporate the new fin

 September 30, 2013 ‐ DCAS sent the revised ER 

Advisory Board

 October, 4, 2013 ER cleared Authorized Derivat

Classifier (ADC ) review, sent revised ER to petit
Follow‐up Efforts

 Additional Data Captures (classified and

unclassified) – Los Alamos National Laborato

Office of Scientific and Technical Informatio

Environmental Management Consolidated BCenter, and Department of Energy (DOE)‐Leg

Management

 Secure Discussions

 Secure Interviews and other interviews (19)

 Additional dose reconstruction modeling
Post Evaluation Issues

 Follow‐up efforts on RFP Tritium Issues

 Evaluation of petitioner concerns about data

falsification and/or data Invalidation

 U‐233/Thorium Strikes

 Neptunium Other Thorium Activities – evaluation includ
Issues that Resulted in Evaluat

Report Revision

 U‐233/Thorium Strikes

• Classified interviews indicated the number of st

were greater than previously evaluated in SEC‐0

• Hanford infeasibility associated with U‐233

 Neptunium

• Not clearly evaluated under SEC 0030

• Hanford infeasibility associated with Neptunium

 Other Thorium Activities

• Classified review indicated there may have been

additional work with thorium not previously eva
Tritium

 Follow‐up Efforts on SEC‐00192 RFP Tritium Issu

• Issued whitepaper on June 25, 2013

– Concluded tritium dose reconstruction feasible

• Provided to the work group on June 26, 2013 and the

petitioners on July 3, 2013 (after ADC review)

• Presented to the work group and petitioners on July 

during the RFP work group meeting

– Preliminary follow‐up questions identified by the wor

Sanford Cohen and Associates (SC&A)

• Work Group and SC&A discussed paper during the w

meeting on September 12, 2013
Tritium–cont.

 Tritium Related Operations

• Tritium contaminated materials from returned u

• Neutron Generator Targets

– Sealed units– Maintenance performed by factory authorized reps

 Potential for the production of tritium from vari

radioactive materials present onsite

• Determined not to be a significant source or contribut

exposure
Tritium–cont.

 Additional Data Captures and Interviews:

• Identified and confirmed potential for tritium ex

from contaminated shipping containers

• Supported our previous finding that all known in

involving a tritium release were below the relea

from 1973 incident

• Did not identify any other sources of tritium exp

beyond previously evaluated other than from thshipping containers
Tritium–cont.

 Tritium exposure time periods evaluated:

• From 1959 through 1972• During 1973

• Post 1973
Tritium Exposure 1959 ‐ 197

 Based on interviews and document review, 

believes the most likely chronic exposure scfrom opening and working with shipping cothat contained units returned from other sit

 Exposure scenario developed from August 3

incident where 1.5 curies of tritium released 

shipping container
Tritium Exposure 1959 – 1972

 Basis for using 1974 incident:

• Background levels prior to the incident were bei

measured and were dosimetrically insignificant 

the release

• Quantity released was probably more typical of 

from a shipping container

• Tritium was released to the workplace environm

not in a glovebox
Tritium Exposure 1959 – 1972

 Basis for using 1974 incident:

• The release involved elemental tritium and not t

oxide

• The incident occurred close enough to the 1973 

that work place controls were likely similar to pr

1973

– SC&A questions the basis for believing this is a reason

bounding scenario
Tritium Exposure 1959 ‐ 1972–

 Monitoring Data from 1974 incident:

• Air samples from June through September 1973

– Average concentration prior to Aug. 30, 1974 were 534

4518 pCi/m3

– Concentration Aug. 30 was 37, 676, 609 pCi/m3

• Bioassay samples taken indicated a high result o

pCi/L

• Work Areas Smears were taken (>200)
Tritium Exposure 1959 – 1972

 Dose Assessment from 1974 incident:

• The largest reported urine sample was 32, 320 p

a start date of August 30, 1974

• Using IMBA, the resulting dose was < 1 mrem (0

mrem)

• Assuming 1 incident per day for 250 per year res

37.5 mrem/year

 Therefore, all unmonitored workers for tritiu

be assigned 37.5 mrem for all years prior to 
Tritium Exposure 1973

 Annual Dose Assigned based 1973 incident:

• The incident occurred April 9 through April 25, 1

a shipment of scrap plutonium from LLNL was pr

at RFP in bldg. 779A

• The incident was not immediately identified so i

monitoring did not begin until September 1973

• Approximately 250 people were bioassayed for t

– Initially 19 people were identified with elevated tritiu

– Upon recheck only 5 were above 10,000 pCi/L action l
Tritium Exposure 1973–cont.

 The five cases (Case A, B, C, D, and H) exceed

10,000 pCi/L were reviewed from the final inreport:

• All cases were modeled to determine the best fi

urine data which then would give the most likely 

• Case H best fit exposure scenario resulted in the 

dose of 84 mrem

– Limited information therefore assumed acute intake f

event

 Tritium doses will be assigned to all unmoni

workers
Tritium Exposure post 1973

 Co‐worker analysis was performed using 1974 a

tritium bioassay data

• 38 individuals with tritium data 1974• 37 individuals with tritium data 1975

 Because tritium was only present as a potentia

contaminant, groups of individuals were not pla

routine bioassay for tritium

 One‐tenth of the urine samples collected for pl

were analyzed for tritium

 Also, samples were required when there was a 
Tritium Exposure post 1973–c

 Dose Assessment for 1974 and 1975:

• It was assumed each worker had potential for ex

throughout the year

• The 95th percentile was used because only one‐t

the population was sampled

 The co‐worker study for 1974‐1975 period y

doses of 0 mrem for everyone

 For post 1974 the same dose will be assigne

unmonitored workers based on the limited 

data being consistent with the 1974 and 197
Thorium

 In SEC‐0030 evaluation the NIOSH position was 

documents supported that Thorium quantities 

at Rocky Flats were not in high enough quantiticontribute significantly to internal dose potenti

 As stated in NIOSH’s original SEC‐0030 evaluatio

beginning in 1952, Thorium was used on site inquantities small enough that effluents were no

routinely analyzed for Th. Thorium quantities v

from as little as none to as much as 238 kilograin a given month
Thorium–cont.

 Thorium was used in a variety of processes incl

• Fabrication of metal parts from natural thorium or th

alloys

• Use of oxide (“thoria”) as a mold‐coating compound

• Numerous analytical procedures and research and

development

• As a substitute for U or Pu components in research a

development

• Removal of Th‐228 from U‐233

• Mg‐Th alloy work (This is still being evaluated)
Thorium–cont.

 Most of the work associated with Thorium d

the SEC‐0030 evaluation was focused on speactivities that occurred in the 1960s

 Based on interviews and document review, 

decided to re‐evaluate the Thorium issue
Thorium–cont.

 During NIOSH’s review documents supported that:

• Activities involving thorium occurred as far back as 1952

• A concern with exposure or the need to monitor personne

back as 1954

 Changing Inventories in these early years supported 

work with Thorium was occurring during this period

• Activities and processes involving Thorium were not well

documented in the early years nor was the throughput

 Based on NIOSH’s review of the NMMS database, n

significant inventories of Thorium existed at Rocky 

1971

• Documents do indicate that thorium solutions (thorium n

existed up through 1974
Thorium–cont.

Personnel and Area Monitoring Data RFP developing personnel monitoring approach for 

through the 1950s into the 1960s

 No routine monitoring for thorium existed at RFP

• Personnel and area air samples from 1960, but no activity 

• Two bioassay samples in 1966• Some Thorium Specific Personnel and Area monitoring da
Thorium–cont.

Surrogate Data During review of SEC‐00030 NIOSH used surrogate d

samples for the thorium ingot operation in 1960

• This was vetted in 2007 before surrogate data criteria (IG‐

established in 2008

• Data was from a study conducted at the Albany Research 

This was a one‐time operation conducted under experime

laboratory conditions
Thorium–cont.

Feasibility Determination Activities involving thorium in the 1950s and early 1

were not well defined

 Lack sufficient personnel and area monitoring

 Surrogate data used does not meet the criteria for u

surrogate data established in IG‐004
Thorium–cont.

Feasibility Determination‐cont. Therefore, NIOSH finds it’s not feasible to reconstru

thorium exposure from 1952 through 1966

 NIOSH intends to use any relevant internal monitor

that may become available for individual claims
U‐233/Thorium Strikes

 Exposure during U‐233/Thorium strikes was origina

evaluated under the SEC ‐0030 evaluation

• Re‐opened under SEC‐0192 after indications this may have 

more than the two times (1965 and 1967) previously iden

 U‐233 was being evaluated for its use in the weapo

program

 Problems with U‐233 was a contaminant U‐232

• U‐232 progeny pose a significant external hazard

 A chemical process called a “Thorium strike” was us

remove the Th‐228 and its progeny
U‐233/Thorium Strikes–cont.

 SEC‐0030 assumed U‐233 exposure covered 

uranium bioassay

 During the deliberation of SEC‐0030 the bou

Thorium dose was based on air sampling takduring the strike in 1965

• This strike was considered bounding because it h

highest concentration of U‐232 of the two strike

• No credit was taken for ventilation, hoods or tim
U‐233/Thorium Strikes–cont.

 Interviews and documents indicated additional 

occurred other than the two previously evaluat

• Were the potential exposures from other strikes bou

the 1965 exposure analysis?

 Other questions came up based on recent addit

class at Hanford based on inability to reconstru

to U‐233

• Were the activities similar?• Were the material quantities similar?• How much monitoring data do we have in compariso
U‐233/Thorium Strikes–cont.

Reasons to believe 1965 Strike is still bounding Thorium Most documents indicate the U‐233 was to be proc

shipped off site prior to the 90 day period to preven

hazard from the ingrowth and therefore a strike wo

be required

 Documents indicate the concentration of U‐232 did 

exceed 8 ppm after 1965

 Although NIOSH determined the 1965 exposure wa

bounding, it’s not clear how this would be applied i

additional strikes are assumed
U‐233/Thorium Strikes–cont.

Determining U‐233 exposures The quantity of U‐233 on site at RFP varied from 19

end of U‐233 operations in 1983

 Estimates from available documents indicate quant

could have been from 1 kg up to 150 kg from 1965 

1983

• Highest quantities from 1965 through 1968

 Bioassay data for uranium exists and a uranium co‐

model exists for the period of concern
U‐233/Thorium Strikes–cont.

Determining U‐233 exposures Initial idea was to give a corrected uranium dose to a

with uranium bioassay

• Assumption based on all workers who worked on U‐233 act

have uranium bioassay

 A review was conducted to determine if any of the O

(46) listed in logbook for U‐233 operations were existclaimants in NOCTS

• There were 18 of the 46 who are claimants

• Of the 18 claimants, 17 had uranium bioassay; no clear reas

claimant did not have bioassay
U‐233/Thorium Strikes–cont.

Determining U‐233 exposures NIOSH cannot assume all workers working on U‐233 o

necessarily had uranium bioassay

 NIOSH cannot identify all workers who worked with U

through the years of operations

 If NIOSH used the uranium co‐worker, NIOSH would h

assume all workers could have been exposed and a cofactor for exposures to U‐233/U‐232 and progeny app

• Factor could vary significantly depending on mass based ana

activity based

 U‐233 Specific Activity is approx. 140 times U‐235

• U‐233 operations would have been handled differently than 

uranium operations. Therefore, using the uranium co‐worke

necessarily have been indicative of U‐233 exposures.
U‐233/Thorium Strikes–cont.

Personnel and Area Monitoring Data No U‐233 specific bioassay data

 No Th‐228 specific bioassay data

 One set of U‐233 specific air samples in 1965 (Highe

39%)

 Uranium co‐worker cannot be used
U‐233/Thorium Strikes–cont.

Feasibility Determination NIOSH finds it’s not possible to completely reconstr

internal U‐233, U‐232, and Th‐228 radiation dose fo

period from 1964 through 1983

 NIOSH intends to use any related internal monitorin

that may become available for individual claims
Neptunium

 General conclusion under SEC‐0030 was Nep

was used in small quantities for research typ

and had limited exposure potential compareUranium and Thorium

 A determination was made to re‐explore thi

exposure situation based on interviews and 

determination associated with Neptunium a

Hanford
Neptunium

 Records indicate that Neptunium was proce

Rocky Flats as early as 1962 and inventories until 1988

 Neptunium was processed to produce pure

Neptunium oxide, metal, and metal alloys

 Processes employed included dissolution, an

exchange, precipitation, filtration, calcinatio

conversion to fluoride, and reduction to met
Neptunium–cont.

 Fabrication steps such as casting and rolling 

performed to produce metal shapes and foi

 Neptunium was also recovered from residua

materials including sand, slag, crucibles, cas

skulls, and alloys

• The residues were not only from Rocky Flats ope

but residues were sent from other sites

 Based on documents and inventories it appe

most work with Neptunium was completed 

end of 1983
Neptunium–cont.

 Annual on site inventories were typically

maintained around 1 kg

• Does not address throughput

 Batches involving Neptunium typically did n

exceed 300 grams

 Buildings having Neptunium inventories incl

371, 559, 707, 771, 776, 777, 779, 779A, and 
Neptunium–cont.

Neptunium Exposure Documents indicate some early work was conducte

hoods, but most work was performed in glove boxe

 Based on NIOSH’s review, Neptunium exposure pot

existed at every processing step, including extractiopurification, hydrofluorination, reduction to metal, 

casting, and rolling
Neptunium–cont.

Personal Monitoring Data There are only two bioassay samples for Neptunium They were both taken in 1966

• One “Below Significant Level” and the other 0.9 dpm/24h

 Gross Alpha bioassay samples existed up until 1970Workplace Monitoring Data NIOSH has found no workplace monitoring records 

sample, surface contamination samples) specific to

Neptunium
Neptunium–cont.

Feasibility Determination Can we use gross alpha samples as indicator for Ne

• NIOSH interviewed two former Rocky Flats Plant employe

with the Radiological Controls program and the Bioassay l

• Interviews indicated that it would be questionable based 

chemistry whether you would see the Neptunium in the s

• Interviews indicated that the intent of co‐precipitation pro

after 1961 for “Gross Alpha” analysis was to focus the ana

specific radionuclides typically Uranium and possibly plut
Neptunium–cont.

Feasibility Determination‐cont. Little to no personal or area monitoring data

 Gross Alpha bioassay samples not a viable means fo

estimating Neptunium exposures

 Too many different types of activities including wet 

processes to develop an exposure model

 Additionally, the source term varied in amount and 

form
Neptunium–cont.

Feasibility Determination‐cont. Quantities and activities associated with Neptunium 

Rocky Flats are similar to Hanford during the same 

period

 Based on this, NIOSH has concluded dose reconstru

not feasible for Neptunium exposures for 1962 thro
Neptunium–cont.

Why stop at end of 1983? Based on NIOSH’s review of documents very little to 

occurred with Neptunium after 1983

• Inventories relatively constant

 A 1981 Documents indicates that early work was do

open hoods but later “Alpha containment” was use

 In vitro bioassay techniques improved by 1981 and 

techniques improved by 1976

 NIOSH will continue to evaluate the 1984‐1988
Current SEC Classes

Employees of DOE, its predecessor agencies, or DOcontractors or subcontractors who were monitored 

should have been monitored for neutron exposure

working at the Rocky Flats Plant in Golden, Colorad

number of work days aggregating at least 250 worfrom April 1, 1952, through December 31, 1958, ...

Employees of DOE, its predecessor agencies, or DOcontractors or subcontractors who were monitored 

should have been monitored for neutron exposure

working at the Rocky Flats Plant in Golden, Colorad

number of work days aggregating at least 250 worfrom January 1, 1959, through December 31, 1966
Feasibility of Dose Reconstructi

 NIOSH ‐

• finds that internal doses cannot be estimated 

sufficient accuracy from April 1, 1952 through

December 31, 1983

• intends to use any related internal monitoring 

that may become available for individual claim

• will continue to evaluate potential Neptunium

exposures for the 1984‐1988 time period.
Summary

Feasibility Findings for SEC 0192 (Rev. 1) Rocky Flats

April 1, 1952 – December 31, 1983

Source of Exposure Reconstruction Feasible Reconstr

NOT Fea

InternalTritium XThorium X (1952-

U – 233 X (1964-

Neptunium X(1962-External – Not evaluated in this report (See SEC – 0030)
Recommended Class

All employees of the Department of Energy, 

predecessor agencies, and their contractors a

subcontractors who worked at the Rocky FlatPlant in Golden, Colorado, from April 1, 1952

through December 31, 1983, for a number of 

days aggregating at least 250 work days, occu

either solely under this employment, or in

combination with work days within the para

established for one or more other classes of

employees included in the Special Exposure C
Remaining Issues

 Data Falsification question

• Classified Interview to be conducted with individual wh

information concerning data falsification

 Continue to evaluate 1984‐1988 period for Neptu

exposure potential

 Evaluate the use and exposure potential for Mg‐T

at Rocky Flats

 Resolve open questions with SC&A and the work 

concerning tritium