Draft White Paper 

SC&A’S EVALUATION OF NIOSH’S APRIL 2012 MOUND 

LABORATORY Th-232 WHITE PAPER 

Contract Number 200-2009-28555 

Prepared by 

Ron Buchanan, PhD, CHP 

S. Cohen & Associates 

1608 Spring Hill Road, Suite 400 

Vienna, Virginia 22182 

Saliant, Inc. 

5579 Catholic Church Road 

Jefferson, Maryland 21755 

May 2012 

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 predecisional 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.
Effective Date: 

May 2, 2012 

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0 (Draft) 

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Page No. 

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NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

Document No. SC&A’s Evaluation of 

NIOSH Th-232 White Paper 

Effective Date: 

Draft – May 2, 2012 

S. COHEN & ASSOCIATES: 

Technical Support for the Advisory Board on 

Radiation & Worker Health Review of 

NIOSH Dose Reconstruction Program Revision No. 

0 (Draft) 

SC&A’s Evaluation of NIOSH’s April 2012 

Mound Laboratory Th-232 White Paper Page 2 of 5 

Task Manager: 

________________________ Date:____________ 

Ron Buchanan, PhD, CHP 

Supersedes: 

N/A 

Project Manager: 

________________________ Date:____________ 

John Stiver, CHP 

Peer Reviewer(s): 

 Joe Fitzgerald 

Record of Revisions 

Revision 

Number 

Effective 

Date Description of Revision 

0 (Draft) 05/02/2012 Initial issue 
Effective Date: 

May 2, 2012 

Revision No. 

0 (Draft) 

Document No. 

SC&A’s Evaluation of NIOSH Th-232 White Paper 

Page No. 

3 of 5 

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

1.0 INTRODUCTION 

On April 2, 2012, the National Institute for Occupational Safety and Health (NIOSH) provided a 

white paper titled, Retrospective Dose Reconstruction for Thorium-232 Activities at the Mound 

Laboratory (NIOSH 2012), to the Mound Laboratory (ML) Work Group (WG). 

A ML WG meeting was held on April 10, 2012, in which the issue of Th-232 bioassay 

monitoring and dose assignments was discussed. 

The following is a summary of SC&A’s evaluation of NIOSH’s white paper concerning Th-232 

monitoring and dose assignments at the ML.

2.0 SC&A’S EVALUATION OF NIOSH’S WHITE PAPER 

SC&A evaluated NIOSH’s white paper and found that it does demonstrate that thorium is an 

important consideration for some Mound works, and in general, concurs with the NIOSH method 

of dose reconstruction (DR) from potential thorium intakes (the purpose of this evaluation was 

not to analyze the DR process for thorium). However, there are still some issues concerning who 

was monitored and had their samples analyzed for thorium, and how often and under what 

circumstances this was performed. Some of these issues were discussed on a preliminary basis 

during the April 10, 2012, ML WG meeting, but are included in this summary for completeness 

and so that they can be documented. 

Item #1 – Control of Access to Thorium Material 

In evaluating the assignment of thorium dose to ML workers, it is important to determine if 

access to the thorium-containing materials was controlled, or if persons not directly associated 

with the materials also could have been inadvertently exposed. This brings up the following 

questions or issues: 

a. Was access to, and working with, the thorium-containing materials controlled by physical 

barriers and/or procedural requirements? 

b. Were only persons directly involved with handling the material allowed in the area, or 

could there have been other personnel, such as craft workers, maintenance workers, 

grounds keeper, etc., that may have worked around the material, but were not considered 

part of the thorium-handling crew? Exposures could have occurred not only during the 

periods the material was being handled, but also during dormant periods when no specific 

activity was taking place, and no health physics oversight was in place; thorium bioassays 

would not have been available for these types of workers under those circumstances. 

c. What situation or procedure triggered the need to obtain urine samples and have them 

analyzed for thorium and the results recorded? 

d. Was a list of personnel working with or around thorium-containing materials 

maintained? Relying on recorded thorium bioassays and/or applying a coworker model 

can only be used if it can reasonably be assured that the potentially thorium-exposed 

workers were bioassayed or identifiable for coworker dose application, unless the 

coworker dose is applied to all unmonitored workers. 
Effective Date: 

May 2, 2012 

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NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

Item #2 – Thorium Bioassay Records 

SC&A reviewed some of the ML workers’ DOE files and ORAUT-TKBS-0016-5 (ORAUT 

2009) to assess the validity of the thorium bioassay records. ORAUT-TKBS-0016-5 states: 

Page 30 – Th-230

Primary 230Th bioassay records consisted of a logbook, and apparently duplicate 

records in a brown notebook. Count data were typically recorded on Form 

O-318 followed by an “I” or “Io.” Secondary 230Th results started as weekly 

reports on March 17, 1958. Weekly reports included Name, Isotope, and Result. 

Prior to 1958, secondary 230Th results were reported on Form O-634 including 

Name, Badge Number, Date, Type of Analysis, Isotope, and Result. However, 

some secondary documents have problems with reporting units. Some results are 

reported to be cph [counts per hour] per 24-hour sample when primary records 

indicate that they are actually cpm [counts per minute] per aliquot. The ORAU 

database should therefore be considered a secondary record extracted from 

primary records. 

Page 32 – Th-232

Thorium-232 records are diverse due to programs conducted for many years. 

Primary 232Th bioassay data were entered into a small brown spiral notebook 

marked “Radium-Thorium” and “Radium-Thorium Separation from 8/15/1955 to 

2/2/1959 (Meyer 1992). Additional primary 232Th bioassay data were recorded in 

a large hardcover record book. However, the first 38 pages from this record 

book were removed from 7/6/59 to 1/9/61, 7/13/64 to 11/15/64 and 5/30/65 to 

6/6/65. These record books apparently do not contain true primary data, but 

calculated results such as cpm excreted per day. Secondary records in weekly 

reports contained 232Th results as cpm/24-hr samples beginning March 17, 1958. 

In August 1959, secondary results were reported on form O-756. The ORAU 

database is a record of secondary 232Th bioassay data extracted from other 

primary records (ORAU 2003e). [Emphasis added.] 

From this information, it is not apparent that the dose reconstructor has access to copies of all the 

original data sheets, or where they are located. SC&A’s scan of some of the DOE files located 

several of these forms with thorium bioassay data recorded. However, there does not appear to 

be much assurance that all the primary data are available to the dose reconstructor. 

Item #3 – Thorium-Containing Materials at the ML during All Periods 

In addition to the drummed material from United Lead Corporation (ULC), Mound also received 

thorium-containing materials from the St. Louis Airport, according to page 15 of ORAUTTKBS-0016-2 (ORAUT 2004): 

SW building was used in the Cotter Concentrate (St. Louis Airport Cake) starting 

in the early 1970s and terminated late in that decade. Pilot plant operations in 

SW were to recover Th-230 and Pa-231. 
Effective Date: 

May 2, 2012 

Revision No. 

0 (Draft) 

Document No. 

SC&A’s Evaluation of NIOSH Th-232 White Paper 

Page No. 

5 of 5 

 This report has been reviewed for Privacy Act information and has been cleared for distribution. 

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82. 

NOTICE:

The Cotter concentrate contained 99.9 g/drum of Th-232 and 11.1 g/drum of Th-230, according 

to page 16. Additionally, thorium was used in other areas at Mound as stated on page 12 of 

ORAUT-TKBS-0016: 

Thorium-232 was often substituted for 238Pu compounds for modeling purposes in 

research and development, because this isotope was less expensive and less 

hazardous, and had physical characteristics similar to 238Pu. It is possible, 

therefore, to find 232Th compounds identical to the 238Pu compounds. 

These were not included in the paper that SC&A could find, and most likely not in the cleanup 

date of September 1975 as stated on page 20 of the paper. Although the drummed material from 

ULC most likely presented the greatest exposure potential, the issue of thorium 

exposure/monitoring did not go completely away in mid-1975. These other sources of thorium, 

and thorium contamination present during decontamination and decommissioning (D&D), are 

sources that could also result in personnel exposures and require bioassay data for DR. 

3.0 SUMMARY 

SC&A found that NIOSH’s white paper demonstrated that thorium intakes and doses are 

important considerations during DR for some Mound works; however, identifying all the Mound 

workers potentially exposed to thorium, and determining if all primary thorium bioassay records 

are available for these workers, is not as apparent and has not been adequately addressed. 

4.0 REFERENCES 

Meyer, H.E., 1992. History of Mound Bioassay Programs, MLM-MV-93-93-0003, EG&G 

Mound Applied Technologies, Miamisburg, Ohio. [SRDB Ref ID: 1962] 

NIOSH 2012. Retrospective Dose Reconstruction for Thorium-232 Activities at the Mound 

Laboratory, Rev. 00. National Institute for Occupational Safety and Health, Office of 

Compensation Analysis and Support, Cincinnati, Ohio. April 02, 2012. 

ORAU (Oak Ridge Associated Universities) 2003e. Database of Excretion Data for Other 

Radionuclides, ORAU file locator, DOE Site Images, Mound Laboratory, Data Capture 09-24- 

03, Folder 1806, Office of Compensation Analysis and Support, Cincinnati, Ohio. [SRDB Ref 

IDs: 8755, 8757] 

ORAUT 2004. Technical Basis Document for the Mound Site – Site Description, Rev. 00, 

ORAUT-TKBS-0016-2. Oak Ridge Associated Universities Team, Cincinnati, Ohio. March 30, 

2004. 

ORAUT 2009. Technical Basis Document for the Mound Site – Occupational Internal 

Dosimetry, Rev. 00 PC-01, ORAUT-TKBS-0016-5. Oak Ridge Associated Universities Team, 

Cincinnati, Ohio. March 13, 2009.