Oak Ridge National Laboratory

Special Exposure Cohort 

Petition Evaluation Report

SEC-00189

Timothy Taulbee, PhD, CHP

Research Health Scientist

National Institute for Occupational Safety and Health

Division of Compensation Analysis and Support

September 2012

Denver, CO
Special Exposure Cohort

Evaluation Team

 DCAS Lead – Timothy Taulbee

 ORAU SEC Lead – Mike Kubiak

 ORAU Lead Technical Evaluator – Mike Domal

• Roger Halsey

• Keith Varnado

• Ray Clark
Petition Overview

 83.13 petition received on July 18, 2011

 Petition qualified on October 11, 2011

 Notification to ABRWH on January 6, 2012 that 

NIOSH would exceed 180-day deadline due to 

data retrieval difficulties

 SEC Evaluation Report sent to ABRWH on August 

22, 2012

 SEC Evaluation Report received by Petitioner on 

August 31, 2012
Petition Overview – cont.

 Petitioner requested class:

All contractor employees, subcontractor 

employees, and AEC employees who were 

monitored or should have been monitored for 

any of the various radionuclides and fission 

products present at the X-10 plant while working 

in all areas at the Oak Ridge National Laboratory 

(X-10) from January 1, 1943 through December 

31, 1952.
Petition Overview – cont.

 Class evaluated by NIOSH:

All employees of the Department of Energy, its 

predecessor agencies, and their contractors and 

subcontractors who worked in any area at the 

Oak Ridge National Laboratory (X-10) in Oak 

Ridge, Tennessee, from January 1, 1943 through 

July 31, 1955.
Proposed Class Definition

All employees of the Department of Energy, its 

predecessor agencies, and their contractors and 

subcontractors who worked in any area at the Oak 

Ridge National Laboratory (X-10) in Oak Ridge, 

Tennessee, from June 17, 1943 through July 31, 

1955, for a number of work days aggregating at 

least 250 work days, occurring either solely under 

this employment, or in combination with work days 

within the parameters established for one or more 

other classes of employees in the Special Exposure 

Cohort.
Overview

 How did NIOSH develop this recommendation?

• ORNL Historical Background

• Evaluation of Critical Exposure Issues

• Monitoring Data

• Feasibility of Dose Reconstruction
ORNL Historical Background

 Construction of X-10 started in February 1943

Bldg 205 - May 1943

Bldg 105 – June 1943

ORNL Website 2012
ORNL Background

 Reactor Critical on November 4, 1943

Bldgs. 105 and 205 – October 1943 ORNL Web site 2012
Start of Radiological Operations

June 17, 1943

 Ground breaking February 1943

 Photographic evidence indicates construction still in 

June 1943

 First uranium slug shipment from Aluminum 

Company of America (ALCOA) left on June 17, 1943

 Uranium stored somewhere onsite until being 

loaded into the graphite reactor around October 31, 

1943 
Early ORNL Milestones

 Graphite Reactor Critical – November 4, 1943

 First discharge of irradiated uranium targets – End 

of November 1943 

 1.54 mg of plutonium separated and sent to 

University of Chicago – December 31, 1943

 First shipment of plutonium to Los Alamos in 

February 1944

 By the end of war, 326.4 grams of plutonium had 

been produced (1945)
ORNL Map - 1955
Reactor Development

 1943 – Graphite reactor 

 1945 – Critical experiments in Bldg. 205

 1949 – Low Intensity Test Reactor (LITR)

• Full scale mock-up of the MTR reactor (INL)

 1950 – Bulk Shielding Reactor (BSR)

• Swimming pool style

 1952 – Homogeneous Reactor Experiment (HRE)

 1952 – Tower Shielding Experiment

 1953 – Aircraft Reactor Experiment
ORNL Reactors

Tower Shielding Reactor

LITR

Homogeneous Reactor Vessel

(before installation and operation) Bulk Shielding Reactor
Isotope Production

 August 1946 - First 

radioisotope 

shipment for medical 

research

 First year of 

production 60 

different isotopes 

were shipped

Removal of first radioisotopes for medical research Aug 1946
Isotope Production

 Main isotopes shipped were C-14, P-32, I-131 

 Y-12 Connection

• Calutrons - stable isotopes

• Cyclotron - radioisotopes 

 Some separations 

conducted at ORNL (X-10) 

Review 1992 Vol 25 No 3&4
Uranium-233 Production

 1944 - Labscale preparation and testing of thorium 

carbonate 

 1946 – Research and Development for Uranium-233 

extraction (Thorium is the target material)

 1948 – Temproary pilot plant for thorium extraction 

built in 706HB

 1949 – Thorium extraction runs begin

 1954 – Thorex Pilot Plant installed in building 205 

(3019) 
Evaluation of Critical Exposure Issues

 Internal Dose 

• Plutonium

• Uranium

• Mixed Fission Products

• Thorium

• Exotic Radionuclides

 External Dose

• Beta / Gamma Monitoring

• Neutrons
Internal Dose Monitoring

 Hierarchy of internal data

• Personal bioassay 

—urine, feces, whole body count, chest count

• Personal breathing zone sampling

• Representative breathing zone sampling

• Surface contamination measurements

• Source term
Plutonium

 First plutonium monitoring data February 1945

 Urine samples sent to Argonne National Laboratory 

(ANL) for analysis

 Several positive results could have resulted from 

impure lanthanum carrier used in analysis

 Sampling and analysis improved over 6 month 

period 
Plutonium – cont.

 Urine monitoring 

decreased 

significantly in 1946 

but picked up in 

1947 and increased 

into the 1950s

 Plutonium production operations ended in 1945; 

however, research continued
Plutonium – cont.

 Approximately 1500 air samples are available from 

1944 through 1947

 Sample descriptions indicate many were taken 6” 

from hood face

 Interviews with former workers indicate the 

samplers were positioned at head height with the 

intent of sampling the breathing zone

 Most samples were from 706 Radiochemistry 

building (i.e. research)
Plutonium – cont.

 Based on availability of plutonium bioassay (urine) 

results in conjunction with alpha air sample data 

from research facilities, dose reconstruction from 

plutonium exposures is believed to be feasible. 
Uranium

 NIOSH has not located any uranium bioassay results 

until 1949

 A 1949 plutonium bioassay logbook indicates 

sample split and a co-analysis for Uranium-233 
Uranium – cont.

 According to a 1954 review of the urinalysis 

program, ORNL began processing plutonium and 

uranium urinalysis onsite in 1947

 NIOSH has not located any uranium urinalysis 

results before 1949
Uranium (Air Sample) – cont.

 Majority (80%) of 1944-1947 air sample data is for 

radiochemistry building (706)

 Limited data (8%) from separations facility (205) 

where plutonium was separated from uranium and 

mixed fission products

 NIOSH found a few air sample logsheets attached to 

correspondence indicating a routine air monitoring 

program 

 
Uranium – cont.

 Interviews with former workers confirmed routine 

air monitoring program 

 Monthly reports also indicate a routine air 

monitoring program and report number of samples 

collected 

• (≈ 60 samples per week in 1948 = 3000 per year)

 
Uranium – cont.

 To date, neither NIOSH nor DOE has been able to 

locate these air sample results through exhaustive 

records searches

 As a result, NIOSH finds that reconstruction of 

internal doses to uranium is infeasible from June 17, 

1943 through December 31 1948

 
Mixed Fission Products

 No mixed fission product bioassay has been located 

until 1950

 
Mixed Fission Products – cont.

 1954 review of urinalysis program indicated that 

the capability to monitor for mixed fission products 

was developed in 1949

 In August 1949 ORNL-368 Procedure for the 

radiochemical analysis of barium, strontium, and 

rare earths was published 

 Some very limited incident based sampling was 

conducted in 1949 based weekly and monthly 

reports
Mixed Fission Products – cont.

 Difficulties with obtaining fission product sampling 

and request methodology appears to have changed 

in 1951 resulting in more robust monitoring 

program 

 Most of the air sampling data was for product 

contamination in the air (alpha) 

 Limited air sampling data for beta/gamma emitters

 
Mixed Fission Products – cont.

 Limited data for separations facility (205), most air 

sample data was for Radiochemistry Building (706)

 Evidence indicates no bioassay program for mixed 

fission products until late 1949

 Limited air sample data for separations facility

 
Mixed Fission Products – cont.

 NIOSH finds that reconstruction of internal doses to 

mixed fission products is infeasible from June 17, 

1943 through December 31, 1949

 NIOSH believes that dose reconstruction from 

January 1, 1950 through July 31, 1955 may be 

feasible

 
Thorium

 ORNL began conducting research involving thorium 

in 1944 

 Most of the early research was conducted in the 

radiochemistry building (706) where NIOSH has 

located extensive alpha air sample results

 NIOSH has confirmed through records and 

interviews that these air sample results are 

representative of a worker’s breathing zone in the 

chemistry laboratory environment

 
Thorium – cont.

 However, NIOSH has only been able to locate air 

sample data from 1944 through 1947

 No air sample data post 1947 has been located

 As discussed in the uranium section, a routine air 

monitoring program was conducted, but neither 

NIOSH nor DOE has been able to locate the records

 
Thorium – cont.

 NIOSH has not been able to locate any thorium 

bioassay prior to August 1955

 Generally urinalysis for thorium results in a missed 

dose that has been characterized as insufficiently 

accurate 

 At ORNL, however, thorium was monitored via fecal 

analysis 

 NIOSH has obtained thorium fecal results for ORNL 

workers starting in August 1955

 
Thorium – cont.

 Uranium-233 separations increased significantly 

upon receipt of irradiated thorium from the 

Savannah River site in 1956 and 1957

 Following receipt of this irradiated thorium, the 

ORNL bioassay program also increase 

 
Thorium – cont.

 Due to extensive representative air samples available 

from 1944 through 1947, NIOSH believes dose 

reconstruction for thorium exposure may be feasible

 Due to the lack of air sample data from 1948 through 

July 1955, NIOSH finds that dose reconstruction of 

thorium exposure is infeasible

 Due to availability of thorium fecal samples in August 

1955, NIOSH believes that dose reconstruction for 

thorium exposures may be feasible

 
Exotic Radionuclides – cont.

 Starting in 1944 ORNL began producing polonium210 (Dayton Labs) and lanthanum-140 (LANL)

 By 1946, ORNL also produced C-14, P-32, I-131, Y-90 

 By 1948 hundreds of isotopes were being produced, 

and there was a special Isotopes Production 

Division at ORNL

 Based on NIOSH’s research to date, this division 

appears to have operated the calutrons and 86-inch 

cyclotron at Y-12 

 
Exotic Radionuclides – cont.

 
Exotic Radionuclides – cont.

 NIOSH initiated an 83.14 evaluation of isotope 

productions from the cyclotron and calutrons at the 

Y-12 facility in March 2012

 The ORNL SEC-00189 team began to evaluate which 

radionuclides were produced and separated at 

ORNL; we discovered that there was significant 

overlap in research

 Table 5-3 and Table 5-4 lists isotope production that 

NIOSH has found to date

 
Exotic Radionuclides – cont.

 Due to resource overlap, NIOSH decided to Reserve

the exotic radionuclide evaluation at ORNL and 

combine with the Y-12 83.14 effort once SEC-00189 

was completed and presented 

 On August 30, 2012 NIOSH/ORAUT had a kick-off

meeting for this combined effort

 NIOSH will update the ABRWH as we progress in 

our evaluation

 
Internal Dose Monitoring

 Summary of internal monitoring data

Year

Internal Sources 43 44 45 46 47 48 49 50 51 52 53 54 55

Plutonium Air Bio Air Bioassay

Uranium No Data Bioassay

Thorium Air Data No Data 

Fission Products No Data Bioassay

Exotic 

Radionuclides Reserved for a joint ORNL (X-10) and Y-12 evaluation

 Overall internal dose reconstruction is infeasible 

from June 17, 1943 through July 31, 1955
External Monitoring

 Beta – Gamma

• Pocket Ionization Chambers

—12721 readings – December 1943

• Film Badge Dosimeters

 Neutron

• 1944 – Neutron / Photon Surveys

• 1947 – Special Fine Grain Films

• 1949 – NTA

 
External Beta / Gamma Monitoring

Number of External Records by Year in Exposure Database

Year Record Count No. of Names

1943 1345 857

1944 4117 2106

1945 2946 1747

1946 2674 1799

1947 3215 2266

1948 3793 2584

1949 2516 2039

1950 3442 2599

1951 4174 3086

1952 4355 3271

1953 3953 3158

1954 4536 3336

1955 4536 3471

--- Total = 46,928 ---
Neutron Monitoring

 Cadmium filtered neutron badge

 Capability for both thermal and fast neutrons

• Used 14N(neutron,proton)14C reaction for thermal 

neutron response (584 keV proton)

• Thermal response of neutron dosimeter calibrated using 

a thermal column from the graphite reactor

 1947 studies of track fading by Joseph Checka

 
Other Neutron Monitoring Data

 Graphite Reactor 

• Neutron / photon surveys

 Low Intensity Test Reactor (LITR)

• Full scale mockup of MTR and neutron / photon surveys 

of MTR indicate a NP ratio of 0.58

 Bulk Shielding Reactor (BSR)

• Typically zero 20 feet of water

• Experiments lowered into pool

• Neutron / photon surveys

 
Other Neutron Monitoring Data – cont.

 Homogeneous Reactor Experiment (HRE)

• Confirmed workers at HRE wore neutron dosimeters 

through review of claimant files

 Aircraft Reactor Experiment (ARE)

• Neutron / photon surveys

 Tower Shielding Reactor (TSR) 

• Neutron / photon surveys

• Neutron spectra

 
External Dose Summary

 Beta / Gamma Exposures

• Pocket ionization chambers and film badge data

 Neutron Exposures

• Neutron / photon surveys

• Neutron dosimeter (thermal and fast capability)

 Due to use and availability of pocket ionization 

chamber data, film badge dosimetry, neutron 

surveys, and neutron dosimetry, NIOSH believes 

external dose reconstruction is feasible

 
Conclusion from Research

 NIOSH has evaluated the available information 

and determined that it does not have access to 

sufficient personnel monitoring, workplace 

monitoring, or source-term data to sufficiently 

estimate potential internal exposures to:

• Uranium: June 17, 1943 – December 31, 1948

• Fission Products: June 17, 1943 – December 31, 1949

• Thorium: January 1, 1948 – July 31, 1955

 Combined infeasibility

• June 17, 1943 through July 31, 1955
ORNL SEC Petition 00189 – cont. 

 Why everyone?

• Unlike other large facilities (Savannah River, Idaho), ORNL 

was a relatively small main campus. The main campus is 

about the same size as the 700/300 area at Savannah 

River. The facility was largely open once you entered 

through the guard checkpoints. NIOSH could not find a 

practical way to identify the uranium, mixed fission 

product, and thorium exposed workers. Organizational 

charts could really only identify likely exposed workers 

based on job title and organizational function. 
ORNL SEC Petition 00189 – cont. 

 What about employees not included in the SEC?

• NIOSH intends to use any internal and external 

monitoring data, and medical doses that may become 

available for an individual claim (and that can be 

interpreted using existing dose reconstruction processes 

or procedures). Therefore, partial dose reconstructions 

for individuals employed at Oak Ridge National 

Laboratory during the period from June 17, 1943 through 

July 31, 1955, but who do not qualify for inclusion in the 

Special Exposure Cohort, may be performed using these 

data as appropriate.
Health Endangerment

 The evidence reviewed in this evaluation 

indicates that some workers in the class may 

have accumulated chronic radiation exposures 

through intakes of radionuclides and direct 

exposure to radioactive materials.

 Consequently, NIOSH is specifying that health 

may have been endangered for those workers 

covered by this evaluation who were employed 

for a number of work days aggregating at least 

250 work days within the parameters 

established for this class or in combination with 

work days within the parameters established for 

one or more other classes of employees in the 

SEC. 
Proposed Class

All employees of the Department of Energy, its 

predecessor agencies, and their contractors and 

subcontractors who worked in any area at the Oak 

Ridge National Laboratory (X-10) in Oak Ridge, 

Tennessee, from June 17, 1943 through July 31, 

1955, for a number of work days aggregating at 

least 250 work days, occurring either solely under 

this employment, or in combination with work days 

within the parameters established for one or more 

other classes of employees in the Special Exposure 

Cohort.
Feasibility Summary

Feasibility Findings for Oak Ridge National Laboratory (X-10)

SEC Petition SEC-00189 (January 1943 – July 1955)

Source of Exposure Reconstruction Reconstruction NOT 

Feasible Feasible

Internal 

- Plutonium X 

- Uranium Jan 49 – Jul 55 Jun 43 – Dec 48

- Thorium Jan 44 – Dec 47 Jan 48 – Jul 55

- Fission Products Jan 50 – Jul 55 Jan 44 – Dec 49

- Exotic Radionuclides Reserved Reserved

External

- Beta-gamma X 

- Neutron X 

- Occupational Medical X-ray X 
Feasibility Summary
Claimant Statistics

(July 10, 2012) 

 Total number of ORNL claims submitted: 2036 

 Total number claims with employment in 

proposed class: 1302 

• Number of dose reconstructions completed 1074

• Number of claims for which internal dosimetry 

records in the proposed class 236

• Number of claims for which external dosimetry 

records in the proposed class 668
Questions