Savannah River Site (SRS) Special Ex

Cohort Petition Evaluation Repo

Addendum #3 – Thorium (post 19

Timothy D. Taulbee, Ph.D., CHP

Research Health Scientist

National Institute for Occupational Safety and Health

Division of Compensation Analysis and Support

December 2012

Knoxville, TN
Petition Overview

 November 2007: Petition received

 December 2008: Evaluation Report presen

the Advisory Board

 May 2010: Evaluation Report Addendum #

Thorium presented to SRS Work Group

 January 2011: Work Group/Sanford Cohen 

Associates comments received

• Significant Work Group finding: Potential thor

work in other areas not discussed in the EvaluaReport Addendum
Petition Overview—cont.

 February 2011: SRS status update presente

the Advisory Board

 August 2011: In SRS Addendum #2, NIOSH

recommended adding a class of thorium ex

workers in the 773‐A and TNX to the SEC fr

January 1953 to October 1972 and propose

identifying the class based on dosimeter b

location

 August 2011: NIOSH indicated more resea

was needed for the post‐Oct 1972 time pe
Petition Overview—cont.

 December 2011: Advisory Board partially

concurred with NIOSH recommendation;

however, recommended expansion of the 

to include all workers at SRS

 March 2012: HHS Secretary added a class o

workers at SRS from January 1953 to Octo

1972 to the SEC

 November 2012: NIOSH issued third adden

to the SEC petition evaluation report regar

thorium (to cover the time period October 

through December 2007)
Recommendation to the Advisory 

 NIOSH believes reconstruction of thorium

exposures is feasible and that doses can be

reconstructed with sufficient accuracy for

compensation purposes from October 197

through December 2007

 How NIOSH reached this conclusion

• Very low inventory (source term)• Minimal use in certain defined locations

• Knowledge of the processes

• Radiological controls• Alternate bioassay data
Thorium Inventory

(Presented in August 2011—Addendum #2
Additional SEC End Date Resea

(Presented in August 2011—Addendum #2)

 Inventories indicate some small thorium w

later years
Additional NIOSH Research

 Reviewed

• Inventory reports (1972‐2007)

• SRL and Works monthly technical reports

• Radiological surveys

• Evaluated

• Whole body count data• Other bioassay methods

• Learned

• Large spike of thorium work in 1977 that was

reported in August 2011 was the receipt of spethorium fuel in the receiving basin for offsite f

(Receiving Basin for Offsite Fuels ‐ RBOF)
Receiving Basin for Offsite Fuels 

 Encapsulated spent nuclear fuels

 Fuels repackaged underwater Fuels stored underwater

Repacka

Stored spent fuel

RBOF Building Photos from WSRC-MS-99-00678 accessed via 

http://sti.srs.gov/fulltext/ms9900678/ms9900678
After Additional Review of Rec
Thorium Inventory

w/o water stored, encapsulated spent fuel
Expanded Scale of Previous Gr

 Inventories indicate very small thorium inventory 19
Research vs. Waste and Stora

 Most of the thorium

inventory was waste

and storage

 Less than 1% of the

thorium on site was

available forpotential exposure
Minimal Locations

Table 5‐2: SRS Thorium Inventory, 1972‐2007 (kg) (partial)

Year 773A 723A 235‐F 772‐F Lab MArea 777 M 217‐A Storage 100‐K Basin 10

B

1973 154.01 ‐‐‐2 0.03 ‐‐‐ 57.2 6.4 0.03 52.0 

1974 104.0 ‐‐‐ ‐‐‐ ‐‐‐ ‐‐‐ ‐‐‐ ‐‐‐ 52.0 1975 104.0 0.5 1.1 1.1 43.2 5.4 ‐‐‐ 52.0 

1976 89.4 1.1 0.9 0.9 40.7 2.0 0.0 52.0 

1977 85.4 1.1 0.9 0.9 25.4 2.0 0.0 52.0 

1978 56.6 ‐‐‐ 4.0 4.0 25.2 2.1 0.0 52.0 

1979 83.4 ‐‐‐ 4.0 4.0 31.1 2.1 0.0 52.0 

1980 108.6 ‐‐‐ 4.5 4.5 31.1 ‐‐‐ 8.0 52.0 3.1 
Minimal Locations—cont.
Thorium Nitrate

 Use of thorium nitrate is common in chemist
Process Knowledge

(Savannah River Laboratory 773A)

 1972: Alpha Material Laboratory used thor

oxide as a surrogate for Pu‐238 testing in g

boxes

 1973: Gram quantities of thorium dioxide 

were used in 773A hot cells to test vapor

deposition

 1977‐1980: Alternate Fuel Cycle Technolog

Program (AFCT) and Thorium Fuel CycleTechnology Program (TFCT)—several reseaprojects
Process Knowledge—cont.

(Savannah River Laboratory 773A)

 Multiple AFCT/TFCT studies

• Mechanical grinding of ThO2 in high level cave

• Study on effects of heat treatment on thorium 

• Testing on conceptual THOREX flowsheets of E

fuel in high level caves

• Analysis of off gassing of spent thorium fuel (E

Fuel – high level caves)

• Hanford prepared (encapsulated) 30 fuel rods 

80%ThO2 – 20%UO2 for irradiation at SRS. SRS

received rods in 1979 and stored them in a cag

773A. The program was cancelled in May 1980 

they could be irradiated.
Process Knowledge

(Other)

 Pu‐238 Fuel Form Facility (1980)

• Thorium used as a surrogate for some of the w

performed in the hot cells of the PuFF. Also us

doping agent of the iridium welding agents

 Galileo Project (1987)

• Thorium used as a surrogate for plutonium du

process testing

 Defense Waste Stabilization (1995‐2010)

• Thorium used as a surrogate for plutonium and 

radionuclides to test methods for defense was

stabilization and immobilization
Summary of Thorium Use

For more details please see Table 5‐3

Year Operation Locations Average Inventory (kg

1972‐ 1975 Storage, Surrogate 773A, M Area (storage) 158 

1976 ‐1981 alternative fuels program, tritium studies, storage, surrogate 773A, 235‐F, M Area (storage) 127 

1982‐1989 welding agent studies, storage, surrogate 773A, 235‐F, M Area (storage) 38 

1990‐2003 defense waste research, storage,

surrogate 773A, 235‐F 224 

2004‐2007 defense waste research, storage,

surrogate, D&D 773A 5 
Radiological Controls (1972‐19

 DPSOP‐40 Savannah River Plant Radiation 

Contamination Control and DPST‐RH Radia

Hazards Technical Standards covered:

1. Work in regulated areas

2. Investigating radiation and contamination inc

3. Protective clothing4. Injury in regulated areas

5. Disposal of contaminated waste

6. Fires in regulated areas

7. Radiation exposure control8. Internal radiation exposure control
Radiological Controls (1991‐20

 SRS implemented a new radiation control

manual (WSRC‐5Q) in 1991 to comply with 

Order 5480.11, it was updated as follows t

comply with:

• 1992 DOE Radiological Control Manual DOE N • 1994 DOE Radiological Control Manual DOE/EH• 1995 Occupational Radiation Protection 10CFR
Other Radiological Informati

 NIOSH has collected samples of contamina

surveys in 773‐A, M Area, 235‐F, and TNX f

1972 through 1988

 NIOSH has collected samples of air monito

surveys from 773‐A, 235F, and 244‐F from 

through 1988

 More contamination surveys and air samp

results are available in electronic form
Radionuclide Activities (199

Table 5‐4: Radionuclide Activities

Isotope Inventory (g) SA (Ci/g) Activity 

Th‐232 4.12E+07 1.10E‐07 

Np‐237 6.90E+04 6.90E‐04 

U‐233 1.34E+04 9.50E‐03 1

Cf‐252 2.50E‐01 5.40E+02 1

Pu‐239 5.13E+05 6.20E‐02 318

Am‐241 7.23E+04 3.20E+00 2313

Cm‐244 1.12E+04 8.20E+01 9159

Pu‐238 1.49E+05 1.70E+01 25330

Table includes waste that is not available for intain 1994 only 0.0176 Ci were non‐waste.
Alternate Bioassay Data

 A large number of workers in 773‐A were

monitored for Am, Cm, and Cf

 Review of the bioassay method during

development of the co‐worker model for A

Cm, and Cf revealed that thorium would co

through in the analysis and the alpha emis

would be counted as if it were Am, Cf, or C
Alternate Bioassay Data—con

FE Butler and RM Hall, Analytical Chemistry Vol 4

pp. 1073‐1076 (1970):“A procedure was developed for sequential extra

plutonium, neptunium, and uranium with tri‐isooctylamine (TIOA), followed by extraction of tamericium, curium, berkelium, californium, and

einsteinium with bidentate. Compared with prev

methods, the new procedure is simpler, requires analysis time, and gives better recovery. The reco

Am‐Cm‐Cf from 250 ml of urine or 20 grams of fe

90%.”
Alternate Bioassay Data—con

“All alpha emitting actinides from thorium through

einsteinium extract, indicating an excellent gross alp

analytical procedure. The data show that in analysis 

americium, curium, and californium any contaminat

plutonium, neptunium, or uranium must be remove

this laboratory, thorium, berkelium, and einsteinium 

not present in biological samples in sufficient quanti

require separation or routine identification by alpha

spectrometry.”
Thorium Volume and Activit

 Mass

• 200 kg = 20.0 mCi

 Small volume

• 200 kg = approximately

ten 2L bottles of ThO2

 773‐A is a fairly large

building

• Small volumetric

source term
Alternate Bioassay Data

 No effort was made by the lab to remove th

thorium contaminant from the urine sample

 Why

• Activities were much lower

• Not viewed as a significant contaminant

• Thorium used as a surrogate because it was less

hazardous than plutonium (i.e. safer to use)

 Effectively we have alpha urine bioassay sam

that does not contain plutonium, uranium, 

neptunium, but does contain Th, Am, Cm, C

and Bk
Alternate Bioassay Data—con
Alternate Bioassay Data—con

 How high are the doses (1972‐1994)?

Estimated Organ Dose from Thorium (Intake: 1973‐19

Material Type Lung Dose (rem) Bone Dos

(rem)

Type M 2.60 18.66

Type S 79.92 23.34
Whole Body Count Data

 In 1995, SRS started using Alpha Spectrom

(not gross alpha counts)

 Thorium was not one of the alpha energie

evaluated

 Am, Cm, and Cf analysis only valid from 19

1994

 Must use Whole Body Count Data

• MDA for Th‐232 = 0.15 nCi
Dose from Whole Body Count D

Estimated Organ Dose from Thorium (1995‐20

Material Type Lung Dose (rem) Bone Dos

(rem)

Type M 56.94 174.3

Type S 15.40 1.75

During the Radiological Controls from 10CFR835
Whole Body Count Data

 NIOSH has concluded that by this time per

under 10 C.F.R. 835, people who should ha

been monitored were monitored

 NIOSH has also obtained lapel air sample d

from 2004 when remediation work was

conducted on a concrete pad that was

contaminated with thorium
Summary

 Very low inventory (source‐term)

• More thorium inventory in 1990s and 2000s tha

and 1980s

• Most thorium on site was waste/storage

 Minimal use in certain defined locations

• Mostly 773‐A (especially post‐1983)

 Knowledge of the processes

• Mostly used as a surrogate

• Except for AFCT/TFCT (1977‐1980)
Summary—cont.

 Radiological controls

• Procedures in place

• Routine monitoring of the workplace

• Survey data available• Air monitoring data available

 Alternate bioassay data

• Am, Cm, and Cf bioassay was effectively gross a

analysis that included thorium

• Doses are plausible
Feasibility Summary

Feasibility Findings for Savannah River Site 1972‐2007

Source of Exposure

Dose Reconstruction

Feasible

Dose Reconst

Feasi

Internal

‐ Thorium X
Recommendation

 For the period October 1, 1972 through

December 31, 2007, NIOSH finds that radia

dose from exposure to thorium can bereconstructed for compensation purposes

Class Feasibility Health Endang

October 1, 1972

–

December 31, 2007 Yes Yes