SEC Petition Evaluation Report 

Supplement to Petition SEC-00028 

Report Rev # 0 Report Submittal Date: 6-9-2006 

Subject Expert(s): N/A 

Site Expert(s): Tim Adler, Bill Tankersley, George Kerr, Mel Chew, Bryce Rich, Dan 

Stempfley 

Independent Technical Reviewer: N/A 

Petition Administrative Summary 

Petition Under Evaluation 

Petition # Petition 

Type 

Qualification Date DOE/AWE Facility Name 

SEC-00028 83.13 April 29, 2005 Y-12 Plant 

Feasible to Estimate Doses with Sufficient Accuracy? 

Single Class Multiple Classes Determination Established for All Classes 

Yes No X Yes No X Yes X No

Petitioner Class Definition 

All Steamfitters, Pipefitters, and Plumbers who worked at Y-12 from October 1944 through December 1957. 

Proposed Class Definition 

Employees of the DOE or DOE contractors or subcontractors who were monitored or should have been monitored for: 

1) thorium exposures while working in Building 9201-3, 9202, 9204-1, 9204-3, 9206, or 9212 at Y-12 for a number of work 

days aggregating at least 250 work days during the period from January 1948 through December 1957 or in combination 

with work days within the parameters established for one or more other classes of employees in the SEC; or 

2) radionuclide exposures associated with cyclotron operations in building 9201-2 for a number of work days aggregating at 

least 250 work days during the period from January 1948 through December 1957 or in combination with work days within 

the parameters established for one or more other classes of employees in the SEC. 

Related Petition Summary Information 

SEC Petition Tracking #(s) Petition Type DOE/AWE Facility Name Petition Status 

SEC-00018 83.13 Y-12 Plant Designation Completed 

SEC-00026 83.13 Y-12 Plant Designation Completed 

Related Evaluation Report Information 

Report Title DOE/AWE Facility Name 

SEC Petition Evaluation Report SEC-00018 Y-12 Plant 

Completed By: Signature on file June 8, 2006 

Lavon Rutherford Date 

Reviewed By: Signature on file June 8, 2006 

Jim Neton Date 

Signature on file June 8, 2006 

Approved By: Larry Elliott Date 
 

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Supplement to Y-12 SEC Petition Evaluation Reports 

SEC-00028 

June 9, 2006 

Discussion of Issues Related to the Advisory Board on Radiation and Worker Health’s 

(ABRWH) Review of the Y-12 Evaluation Report 

Introduction 

During the May 18, 2006 meeting of the ABRWH Y-12 Working Group, discussions were held on 

two SEC issues that NIOSH believed warranted further evaluation. This supplement to the 

evaluation report for petition SEC-00028 identifies the issues raised at this meeting and provides an 

evaluation of the effect these issues have on the proposed class designation. 

Issue 1 

A thorough review of the (thorium) material balance ledgers at the Y-12 facility for all 

applicable years needs to be completed and a determination made if the thorium in these 

buildings and areas created an exposure hazard that can not be bounded using existing process 

knowledge. 

As an accountable nuclear material, the receipt and movement of thorium at the Y-12 facility was 

closely monitored by site personnel. The quantities of thorium present on site at any given time were 

tracked in documents called mass balance ledgers which assigned each movement a unique account 

number. To evaluate the potential locations where thorium exposure may have been a concern at Y12, the mass balance ledgers covering the years 1949 through 1957 were examined. 

Table 1 provides a listing of the additional accounts found that are not associated with the buildings 

currently proposed in the class definition for SEC-00028. The account numbers listed are provided 

for identification purposes only and are not the account numbers assigned in the ledgers. The first 

six of these accounts can be directly tied to four buildings (9201-3, 9203, 9213, and 9995); while the 

remaining two account are not building specific. Account 7, with a location/activity description of 

the “control” account, was a master list of the total site thorium inventory at any given time. As 

such, it is not associated with production activities at the site. Account 8 records the disposal of a 

small quantity of thorium in a waste pit and is also not associated with production activities. 

Of the six accounts tied to buildings, the only ones with quantities of thorium of sufficient magnitude 

to be considered production operations are the three accounts associated with activities in Building 

9201-3 While NIOSH is unaware of the nature of these activities, the titles of the account numbers 

seem to indicate experimentation related to reactor technology. The quantities of thorium present 

during the SEC period were of sufficient magnitude to generate significant amounts of airborne 

activity. As there are no air sampling or bioassay data to reconstruct doses for these activities, 

NIOSH does not believe that plausible upper bounds can be placed on the internal doses for these 

workers. 

NIOSH did not, however, identify evidence that would establish that workers in Building 9201-3 

were exposed to radiation during discrete incidents likely to have involved exceptionally high levels 

of exposure. Consequently, NIOSH has determined that health was endangered for those workers 
 

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covered by this evaluation who were employed for at least 250 aggregated work days either solely 

under the employment or in combination with work days within the parameters established for other 

SEC classes (excluding aggregate work day requirements). Based on the above analysis, NIOSH 

amends the original proposed class definition to include workers in Building 9201-3. 

The account numbers associated with the remaining three buildings (9203, 9213 and 9995) had small 

quantities of thorium that do not appear to be related to production activities. The quantities were 

discrete amounts that most likely were related to the production of calibration sources and solutions. 

Since these are small discrete quantities of thorium, NIOSH believes that internal exposures can be 

bounded using source term information combined with the airborne dispersion factors described in 

NUREG-1400.1

 As a consistency check, these bounded values could be compared with the 

exposures estimated from the air sampling and bioassay data that were collected during thorium 

production operations starting in 1959. Because NIOSH believes that plausible upper bound internal 

doses can be established for exposure to this source term, we do not propose to add workers in these 

buildings to the class definition.

Issue 2 

There is insufficient bioassay or air sampling data in the available Y-12 databases to allow for 

the reconstruction of internal exposures to cyclotron workers. In light of the fact that NIOSH 

has been unable to locate incident reports for cyclotron workers during the SEC period, a 

determination needs to be made if internal doses for these workers can be reconstructed with 

sufficient accuracy. 

 

Because NIOSH could not locate sufficient bioassay or air monitoring data to evaluate internal 

exposures at the 86 inch cyclotron, the approach to reconstructing internal doses at this facility relied 

on the capture and review of a number of incident related documents from the Y-12 Delta View 

database. It was believed that, among the 800,000 plus pages of archived images in Delta View, 

there were a large number of reports that contained detailed descriptions of internal exposure related 

incidents. This belief was, to a large extent, based on the review of several cyclotron incident reports 

that were discovered in Department of Energy responses to NIOSH requests for claimant exposure 

information. After discussion with Y-12 records personnel, it was discovered that claimant specific 

incident reports of this type were automatically provided with NIOSH’s request for exposure 

information. A key word search of the Delta View database indicated the existence of approximately 

800 potentially incident related documents. Based on this, it was NIOSH’s belief that the Delta 

View database had a large collection of incident related data that could be used in dose 

reconstructions. 

Subsequent to the release of the Y-12 evaluation report on April 7, 2006, NIOSH conducted a 

thorough review of the incident related reports in the Delta View database and has not been able to 

locate any documents that would be useful in reconstructing internal exposures to workers at the 86 

inch cyclotron located in Building 9201-2. Although it is believed that these documents might exist 

at other storage locations within the Oak Ridge complex, NIOSH does not have any firm evidence 

that would help locate the records at this time. Because NIOSH is unable at this time to identify any 

1

 NUREG-1400, Air Sampling in the Workplace, U.S. Nuclear Regulatory Commission, Office of Regulatory Research, 

Washington, DC (1993). 
 

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documentation that would support the reconstruction of internal doses to cyclotron workers, NIOSH 

is amending the class definition to include cyclotron workers in building 9201-2 from January 1948 

through December 1957. 

NIOSH did not identify any evidence that cyclotron workers were internally exposed to radioactive 

materials during discrete incidents likely to have involved exceptionally high levels of exposure. 

However, there is evidence that some workers in the proposed class may have accumulated 

substantial chronic exposures through episodic intakes of a variety of radionuclides that were 

produced during the operating period of the cyclotron. Consequently, NIOSH has determined that 

health was endangered for those cyclotron workers covered by this evaluation who were employed 

for at least 250 aggregated work days either solely under the employment or in combination with 

work days within the parameters established for other SEC classes (excluding aggregate work day 

requirements).
 

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Table 1 

Summary of Thorium Quantities Present at Y-12 from 1949-1957 

Not Included in the Proposed Class Definition 

(as noted in Ledgers) 

Building Account # Location / Activity Description 

Quantity or Min - Max 

Range 

9201-3 1 ORNL Reactor Tech Division 

2 Aircraft Reactor Experiment 

3 Control, “SF Control Dept” 

Up to thousands of kg 

9203 4 Assay Lab. <<1 kg 

9213 5 “Prod Exp” <<1 kg 

9995 6 Analytical Lab. <1 kg 

No 

Building 

Identified 7 

Control Up to thousands of kg 

“ 8 

“Discarded salvage sent to S-2 

Pit” <<1kg