SEC Petition Evaluation Report 

Petition SEC-00082 

Report Rev # 0 Report Submittal Date 3-26-2007 

Subject Expert(s): Christopher J. Miles, Michael S. Kubiak 

Site Expert(s): N/A 

Petitioner Administrative Summary 

Petition Under Evaluation 

Petition # Petition 

Type 

Petition A 

Receipt Date DOE/AWE Facility Name 

SEC-00082 83.14 January 22, 2007 W. R. Grace (Tennessee) 

Proposed Class Definition 

The NIOSH-proposed class includes all AWE employees who were monitored, or should have been 

monitored, for potential exposure to thorium while working in any of the 100 series buildings or 

Buildings 220, 230, 233, 234, 301, or 310 at the W. R. Grace site at Erwin, Tennessee, for a number 

of work days aggregating at least 250 work days from January 1, 1958 through December 31, 1970, 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 

None 

Related Evaluation Report Information 

Report Title DOE/AWE Facility Name 

None 

ORAU Lead Technical Evaluator: Christopher J. Miles ORAU Review Completed By: Michael Kubiak 

Peer Review Completed By: [Signature on file] 

Tom Tomes 

3/27/2007 

Date 

SEC Petition Evaluation Reviewed By: [Signature on file] 

Jim Neton 

3/28/2007 

Date 

SEC Evaluation Approved By: [Signature on file] 

Larry Elliott 

3/29/2007 

Date 
SEC-00082 03-26-07 W. R. Grace (Tenn.) 

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Evaluation Report Summary: SEC-00082, W. R. Grace 

This evaluation report by the National Institute for Occupational Safety and Health (NIOSH) 

addresses a class of employees proposed for addition to the Special Exposure Cohort (SEC) per the 

Energy Employees Occupational Illness Compensation Program Act of 2000, as amended, 42 U.S.C. 

§ 7384 et seq. (EEOICPA) and 42 C.F.R. pt. 83, Procedures for Designating Classes of Employees 

as Members of the Special Exposure Cohort Under the Energy Employees Occupational Illness 

Compensation Program Act of 2000. 

NIOSH-Proposed Class Definition 

The NIOSH-proposed class includes all AWE employees who were monitored, or should have been 

monitored, for potential exposure to thorium while working in any of the 100 series buildings or 

Buildings 220, 203, 233, 234, 301, or 310 at the W. R. Grace site at Erwin, Tennessee, for a number 

of work days aggregating at least 250 work days from January 1, 1958 through December 31, 1970, or 

in combination with work days within the parameters established for one or more other classes of 

employees in the SEC. 

Feasibility of Dose Reconstruction 

Per EEOICPA and 42 C.F.R. § 83.14(b), NIOSH has established that it does not have sufficient 

information to complete dose reconstructions for individual members of the class with sufficient 

accuracy. NIOSH lacks thorium-specific dosimetric data, making reconstruction of internal thorium 

doses infeasible. 

Health Endangerment Determination 

The NIOSH evaluation did not identify evidence supplied by the petitioners or from other sources that 

would establish that the class was exposed to radiation during a discrete incident likely to have 

involved exceptionally high-level exposures, such as nuclear criticality incidents or other events 

involving similarly high levels of exposures. However, the evidence reviewed in this evaluation 

indicates that some workers in the class may have accumulated chronic radiation exposures through 

intakes of thorium. Therefore, 42 C.F.R. § 83.13(c)(3)(ii) requires NIOSH to specify 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. 

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Table of Contents 

Evaluation Report Summary: SEC-00082, W. R. Grace......................................................................... 3 

1.0 Purpose and Scope....................................................................................................................... 7 

2.0 Introduction ................................................................................................................................. 7 

3.0 NIOSH-Proposed Class Definition and Petition Basis................................................................ 8 

4.0 Radiological Operations Relevant to the Proposed Class ........................................................... 8 

4.1 Operations Description ....................................................................................................... 9 

4.2 Radiation Exposure Potential from Operations ................................................................ 10 

4.3 Time Period Associated with Radiological Operations.................................................... 11 

4.4 Site Locations Associated with Radiological Operations ................................................ 11 

4.5 Job Descriptions Affected by Radiological Operations ................................................... 12 

5.0 Summary of Available Monitoring Data for the Proposed Class .............................................. 12 

5.1 Internal Personnel Monitoring Data ................................................................................. 13 

5.2 External Personnel Monitoring Data ................................................................................ 13 

5.3 Workplace Monitoring Data............................................................................................. 13 

5.4 Radiological Source Term Data ....................................................................................... 13 

6.0 Feasibility of Dose Reconstruction for the Proposed Class ...................................................... 14 

6.1 Feasibility of Estimating Internal Exposures ................................................................... 14 

6.2 Feasibility of Estimating External Exposures .................................................................. 15 

7.0 Summary of Feasibility Findings for Petition SEC-00082........................................................ 16 

8.0 Evaluation of Health Endangerment for Petition SEC-00082................................................... 16 

9.0 NIOSH-Proposed Class for Petition SEC-00082 ...................................................................... 17 

10.0 Evaluation of Second Similar Class .......................................................................................... 17 

11.0 References ................................................................................................................................. 19 

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SEC Petition Evaluation Report for SEC-00082 

1.0 Purpose and Scope 

ATTRIBUTION AND ANNOTATION: This is a single-author document. All conclusions drawn from 

the data presented in this evaluation were made by the ORAU Team Lead Technical Evaluator: 

Christopher J. Miles, CHP; Quantaflux, LLC. These conclusions were peer-reviewed by the 

individuals listed on the cover page. The rationales for all conclusions in this document are explained 

in the associated text. 

This report evaluates the feasibility of reconstructing doses for employees who worked at specific 

facilities during a specified time. It provides information and analysis germane to considering a 

petition for adding a class of employees to the Congressionally-created SEC. 

This report does not make any determinations concerning the feasibility of dose reconstruction that 

necessarily apply to any individual energy employee who might require a dose reconstruction from 

NIOSH, with the exception of the employee whose dose reconstruction could not be completed, and 

whose claim consequently led to this petition evaluation. The finding in this report is not the final 

determination as to whether or not the proposed class will be added to the SEC. This report will be 

considered by the Advisory Board on Radiation and Worker Health (the Board) and by the Secretary 

of Health and Human Services (HHS). The Secretary of HHS will make final decisions concerning 

whether or not to add one or more classes to the SEC in response to the petition addressed by this 

report. 

This evaluation, in which NIOSH provides its findings on both the feasibility of estimating radiation 

doses of members of this class with sufficient accuracy and on health endangerment, was conducted in 

accordance with the requirements of EEOICPA and 42 C.F.R. § 83.14. 

2.0 Introduction 

Both EEOICPA and 42 C.F.R. pt. 83 require NIOSH to evaluate qualified petitions requesting the 

Department of Health and Human Services to add a class of employees to the SEC. The evaluation is 

intended to provide a fair, science-based determination of whether it is feasible to estimate, with 

sufficient accuracy, the radiation doses of the proposed class of employees through NIOSH dose 

reconstructions.1 

NIOSH is required to document its evaluation in a report, and to do so, relies upon both its own dose 

reconstruction expertise as well as technical support from its contractor, Oak Ridge Associated 

Universities (ORAU). Once completed, NIOSH provides the report to both the petitioners and the 

Advisory Board on Radiation and Worker Health. The Board will consider the NIOSH evaluation 

1

 NIOSH dose reconstructions under EEOICPA are performed using the methods promulgated under 42 C.F.R. pt. 82 and 

the detailed implementation guidelines available at http://www.cdc.gov/niosh/ocas. 

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report, together with the petition, comments of the petitioner(s) and such other information as the 

Board considers appropriate, to make recommendations to the Secretary of HHS on whether or not to 

add one or more classes of employees to the SEC. Once NIOSH has received and considered the 

advice of the Board, the Director of NIOSH will propose a decision on behalf of HHS. The Secretary 

of HHS will make the final decision, taking into account the NIOSH evaluation, the advice of the 

Board, and the proposed decision issued by NIOSH. As part of this final decision process, the 

petitioner(s) may seek a review of certain types of final decisions issued by the Secretary of HHS.2 

3.0 NIOSH-Proposed Class Definition and Petition Basis 

The NIOSH-proposed class includes all AWE employees who were monitored, or should have been 

monitored, for potential exposure to thorium while working in any of the 100 series buildings or 

Buildings 220, 230, 233, 234, 301, or 310 at the W. R. Grace site at Erwin, Tennessee, for a number 

of work days aggregating at least 250 work days from January 1, 1958 through December 31, 1970, or 

in combination with work days within the parameters established for one or more other classes of 

employees in the SEC. During this time period, employees at this facility worked with processes 

involving various forms of uranium and thorium. Beginning in 1966, employees also worked with 

processes involving plutonium. 

The evaluation responds to Petition SEC-00082, which was submitted by an EEOICPA claimant 

whose dose reconstruction could not be completed by NIOSH due to a lack of sufficient dosimetryrelated information. This claimant was employed as a Shift Foreman at W. R. Grace from 1962 to 

1976. NIOSH’s determination that it is unable to complete a dose reconstruction for an EEOICPA 

claimant is a qualified basis for submitting an SEC petition pursuant to 42 C.F.R. § 83.9(b). 

4.0 Radiological Operations Relevant to the Proposed Class 

The following subsections summarize the radiological operations at W. R. Grace from January 1, 

1958 through December 31, 1970 and the information available to NIOSH to characterize particular 

processes and radioactive source materials. Using available sources, NIOSH has attempted to gather 

process and source descriptions, information regarding the identity and quantities of radionuclides of 

concern, and information describing processes through which the radiation exposures of concern may 

have occurred and the physical environment in which they may have occurred. The information 

included within this evaluation report is meant only to be a summary of the available information. 

2 See 42 C.F.R. pt. 83 for a full description of the procedures summarized here. Additional internal procedures are 

available at http://www.cdc.gov/niosh/ocas. 

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4.1 Operations Description 

The Davison Chemical Company, a division of W. R. Grace, began processing radioactive materials 

in the late 1950s at the site of the current Nuclear Fuels Services (NFS) facility near Erwin, 

Tennessee. The principal operation at the site has been converting highly enriched uranium (HEU) 

and low-enriched uranium (LEU) from UF6 to a form that could be used to manufacture nuclear fuel. 

Thorium, depleted uranium (DU), U-233, and plutonium have also been processed at the facility. 

Specific tasks performed at the facility included processing of ThO2 mixed with U-233 to make 

light-water breeder reactor fuel for the Shippingport Reactor, and fabricating plutonium and DU 

mixed oxide (MOX) fuel for the South-West Experimental Fast Oxide Reactor (SEFOR). These 

operations, along with all other AEC weapons-related operations, ceased in 1970. Other operations 

involved scrap recovery of uranium and other nuclear fuel material and cleaning empty cylinders used 

to transport low-enriched UF6. 

UF6 was received at the W. R. Grace facility in solid form in cylinders. To convert it to uranium 

metal, the UF6 first had to be vaporized and then reduced to UF4. Vaporization was accomplished by 

heating the UF6 cylinders in an electric oven. The UF6 vapor was piped into a reactor unit, where it 

was reduced with hydrogen to form solid UF4 powder. This powder dropped into a collection hopper, 

where it was metered into safe-diameter product cans. The UF4 was further reduced to uranium metal 

by heating it under vacuum with a reducing agent, such as magnesium metal. After cooling, the 

uranium metal derby was broken and separated from the slag. Uranium remaining in the slag was 

recovered in the scrap recovery operations described below. The uranium derbies were broken into 

smaller pieces on a large hydraulic press. The derbies were often re-melted and cast into various 

shapes or alloyed with other metals. Melting was done in a large vacuum induction furnace. 

Recovery operations involved grinding, pulverizing, sawing, chopping, oxidizing, and blending 

uranium-containing scrap material. Dissolver tanks using a nitric acid solution were then employed. 

For uranium of less than 2% enrichment, a 500-gallon tank was used; batch sizes were limited to 220 

lbs. of UO2. For all higher enrichments, a 20-gallon tank was used with each batch containing less 

than 400 grams of U-235. Although there is no evidence of thorium recovery operations, the 

uranium-containing scrap material sometimes contained thorium [e.g., urania-thoria scrap generated 

by the Elk River Reactor pellet fabrication (Dubinski, 1961)]. 

Fuel consisting of uranium oxide mixed with thorium oxide and/or zirconium oxide (MOX) was also 

produced at the W. R. Grace facility. According to the Site Profile, An Exposure Matrix for W. R. 

Grace and Company in Erwin, Tennessee, this process involved eleven steps (ORAUT-TKBS-0043, 

Section 2.1.4): 

1.	 Receiving and Storage: The material arrived as uranyl nitrate solution containing approximately 

150 g/L U-233. 

2.	 Concentration: The uranyl nitrate solution was concentrated by evaporation. 

3.	 Precipitation: A precipitating agent such as NH4OH was introduced. 

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4.	 Drying and Grinding: The precipitate was dried and ground to a fine powder. 

5.	 Calcination to UO2: The fine uranium powder was calcined to UO2 in a muffle furnace in a 

hydrogen atmosphere 

6.	 Blending: The UO2 was blended to homogeneity. 

7.	 Diluent Addition and Blending: Diluents of ThO2 and/or ZrO2 were weighed out and blended 

with the UO2. 

8.	 Binder Addition: A binder was mixed with the oxide blend, the wet mixture granulated and 

dried, and the granules broken up by screening. 

9.	 Lubricant Addition and Pressing: A lubricant was blended with the granules and the oxides were 

compacted into pellets on a 40-ton press. 

10.	 Binder Removal and Sintering: The resultant pellets were loaded into trays and heated to drive 

off the binder, and then sintered in a muffle furnace in a hydrogen atmosphere. 

11.	 Physical Measurement and Grinding: The pellets were inspected and ground to size 

specifications (as needed), cleaned with water, and dried. 

Documentation showing the process steps for PuO2-containing MOX is unavailable. However, based 

on similar operations at other Department of Energy (DOE) sites, it is likely that the steps for 

producing plutonium-containing MOX would have been similar to those for thorium-containing MOX 

described above (ORAUT-TKBS-0043, Section 2.1.5). 

4.2 Radiation Exposure Potential from Operations 

The potential for external radiation dose existed at all locations where radioactive materials were 

handled or stored. Based on the site operations outlined in Section 4.1, sources of exposure included 

beta, photon, and neutron radiation emitted from materials containing uranium, thorium, and 

plutonium. 

The primary sources of internal radiation exposure at the site were uranium and thorium dust 

produced during the handling of the source material and during preparation of nuclear fuels (ORAUTTKBS-0043, Section 3.0). Beginning in 1966, there was also the potential for internal dose from 

plutonium-containing dust. 

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4.3 Time Period Associated with Radiological Operations 

The Report to Joint Committee on Atomic Energy Congress of the United States by the United States 

General Accounting Office, dated September 14, 1967, states: 

AEC authorized the Davidson Chemical Division of W. R. Grace & Company (Grace) to receive 

and process special nuclear material under license number SNM-124. Grace received its first 

material as an AEC licensee by lease agreement in March 1958 and its first nuclear material as 

an AEC contractor in May 1959. (GAO, 1967) 

The Site Profile indicates that processing of radioactive materials at W. R. Grace began in late 1957. 

This conclusion was made based on exposure monitoring data for existing claimants in the latter part 

of 1957 and is consistent with information provided at a U.S. Congressional hearing (Congress, 1986) 

and historical timeline provided on the NFS Web site (http://www.nuclearfuelservices.com). 

Based on currently-available information, the exact date that uranium or thorium processing began at 

W. R. Grace is uncertain. It is evident, however, that both thorium and uranium processing began 

very early in the site’s history of radiological operations. For the purpose of this evaluation, it is 

assumed that uranium and thorium operations were conducted during the entire period of AEC-related 

operations; this assumption maximizes the assumed exposure time and favors claimants. Work with 

uranium metals and compounds has been on-going at the site since processing began in the late 1950s 

and continues to the present day under NFS. Thorium operations began in 1957 and ended in 1970 

Congress, 1986). Plutonium operations at W. R. Grace began in 1966. All AEC weapons-related 

work (including work with plutonium) ended in 1970. 

4.4 Site Locations Associated with Radiological Operations 

According to the Site Profile, the following radiological materials were received, stored, or processed 

in the specified buildings (ORAUT-TKBS-0043, Table 2-1): 

•	 Uranium in various forms: 100, 105, 110, 110C, 110D, 110E, 111, 120, 130, 131, 132, 133, 135, 

220, 230, 233, 234, 234B, 234C, 300, 301, 302, 303, 304, 310, and 330. 

•	 Thorium: 110C, 110D, 111, 130, 234B, 234C, and 310. 

•	 Plutonium: 234A, 234B, 234C, 110C, and 110D. 

Following preparation of the Site Profile, via e-mail correspondence (NFS, Jun06) and a telephone 

interview (NFS, Aug06), NFS management suggested that all 100 series buildings may have 

processed thorium and that Building 301 was also used for thorium operations. In addition, a Health 

and Safety bulletin (Grace, 1962) indicates air concentrations of 50% MAC for thorium in Building 

233 in 1962. For the purpose of this evaluation, it is assumed that all 100 series buildings and 

Buildings 220, 230, 233, 234, 301, and 310 were potentially affected by thorium operations. 

Considering all sources of information currently available to NIOSH, there is no evidence suggesting 

that any other buildings at the W. R. Grace site in Tennessee were affected by thorium operations. 

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4.5 Job Descriptions Affected by Radiological Operations 

No documentation is currently available that associates job titles and/or job assignments with specific 

radiological operations. Without information that associates work locations with worker job 

descriptions, it is impractical to narrow down the job descriptions for those who may have been 

potentially exposed to radioactive materials. Therefore, it is not possible to determine that any 

specific work group was not potentially exposed to radioactive materials or possible subsequent 

contamination. 

5.0 Summary of Available Monitoring Data for the Proposed Class 

The primary data used for determining internal exposures are derived from personal monitoring data, 

such as urinalyses, fecal samples, and whole-body counting results. If these are unavailable, the 

personal air monitoring data or breathing zone air monitoring data are used to estimate the potential 

internal exposure. If personal monitoring and breathing zone air monitoring data are unavailable, 

internal exposures can sometimes be estimated using more general area monitoring, process 

information, and information characterizing and quantifying the source term. 

This same hierarchy is used for determining the external exposures. Personal monitoring data from 

film badges or thermoluminescent dosimeters (TLDs) are the primary data used to determine such 

external exposures. If there are no personal monitoring data, exposure rate surveys, process 

knowledge, and source term modeling can sometimes be used to reconstruct the potential exposure. 

A more detailed discussion of the information required for dose reconstruction can be found in 

OCAS-IG-001, External Dose Reconstruction Implementation Guide, and OCAS-IG-002, Internal 

Dose Reconstruction Implementation Guide. These documents are available at: 

http://www.cdc.gov/niosh/ocas/ocasdose.html. 

Personal monitoring data are available through DOE for monitored individuals who worked at the 

W. R. Grace site from the latter part of 1957 through the present time. Data capture efforts for this 

site have included formal requests to the current operator (NFS), the State of Tennessee Division of 

Radiological Health, and the Office of State and Tribal Programs of the U. S. Nuclear Regulatory 

Commission (NRC). Information was also received from NFS via e-mail exchanges (NFS, Jun06) 

and by telephone interview (NFS, Aug06). A Worker Outreach meeting was held on July 21, 2005 

with members of the United Steelworkers of America Local 5-3677 in Erwin, Tennessee. The 

transcript of this meeting is available at: 

http://www.cdc.gov/niosh/ocas/pdfs/tbd/outreach/wo072105.pdf. In addition, documents with 

information specific to the W. R. Grace site have been acquired through Internet searches and from 

data capture visits to the DOE Germantown Office, the National Archive and Records Administration 

in Atlanta, and other AEC sites (e.g., Fernald). All site-specific documents identified from these 

combined efforts are available on the ORAU Team Site Research Database (SRDB) or the Special 

Exposure Cohort Information System (SECIS). 

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5.1 Internal Personnel Monitoring Data 

Beginning in 1964, urine bioassay data for uranium are available for monitored workers at the site. Of 

the 57 claimants in NIOSH’s claimant database at the time of this report, 41 have uranium in vitro 

results and 33 have in vivo results. These data include over 2300 uranium in vitro results and over 

700 in vivo results. In vitro results are in units of dpm/L; in vivo results are in units of μg of uranium 

or nCi. Urine bioassay data for plutonium are available for monitored workers during the time period 

of plutonium operations (beginning in 1966). In vivo counting at W.R. Grace began in 1970. Internal 

monitoring data for thorium exposures are not available until the late 1980s, after the cessation of 

AEC operations. 

5.2 External Personnel Monitoring Data 

Personal monitoring data for external radiation exposures at the site are available for monitored 

employees from the beginning of AEC operations in 1958. Of the 57 claimants in NIOSH’s claimant 

database at this time, 52 have external personal monitoring data. In the early years at W. R. Grace, 

film badge dosimetry was provided by Nuclear Chicago. Beginning January 1, 1961, film badges 

were provided and processed by R. S. Landauer, Jr. & Company. Film dosimeters were replaced by 

TLDs in 1989. These data include whole-body and shallow dose estimates. Some extremity 

monitoring data are also available from wrist and finger-ring dosimeters. Neutron dosimetry data are 

not available. 

5.3 Workplace Monitoring Data 

There are two AEC reports containing uranium air monitoring data from samples collected in 1959 

and 1961 (HASL-75, 1959; HASL-61-9, 1961). These data are presented in the Site Profile, Tables 

3-3 through 3-8 (ORAUT-TKBS-0043). Although it is clear, based on Health and Safety bulletins, 

that other routine workplace air and surface contamination monitoring was performed at the site, those 

data are generally unavailable. NIOSH has been unable to locate workplace monitoring data that are 

specific to thorium or plutonium. 

5.4 Radiological Source Term Data 

The aforementioned Report to Joint Committee on Atomic Energy Congress of the United States by 

the United States General Accounting Office, dated September 14, 1967, also states: 

NFS has received substantial quantities of special nuclear material under lease, contract, and 

supply agreement. The NFS records showed that, from start-up to October 31, 1966, the material 

received by NFS, excluding non-Section 53 material for contracts then active, included 29,838 

kilograms of U-235. (GAO, 1967) 

Section 2.1.2 of the Site Profile (ORAUT-TKBS-0043) describes scrap recovery operations involving 

batch sizes limited to 220 pounds of UO2 if less than 2% enrichment; otherwise, batch sizes were 

limited to less than 400 grams of U-235. Section 2.1.4 of the Site Profile describes a typical shipment 

of uranyl nitrate solution as containing approximately 7 kg of U-233, with a U-233 concentration of 

150 g/L. Section 3.3 of the Site Profile describes production of MOX fuel containing 99% by weight 

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232/228ThO2 with a breakdown of 50% Th-232 activity and 50% Th-228 activity. Due to criticality 

concerns, only 4 kg of this material could be processed at a time. MOX fuel containing a plutonium 

mixture of 12% by weight PuO2 is also described in Section 3.4 of the Site Profile. 

NIOSH has been unable to locate documentation providing a comprehensive summary of the total 

quantities of uranium, thorium, or plutonium stored or used at the site. 

6.0 Feasibility of Dose Reconstruction for the Proposed Class 

42 C.F.R. § 83.14(b) states that HHS will consider a NIOSH determination that there was insufficient 

information to complete a dose reconstruction, as indicated in this present case, to be sufficient, 

without further consideration, to conclude that it is not feasible to estimate the levels of radiation 

doses of individual members of the class with sufficient accuracy. 

In the case of a petition submitted to NIOSH under 42 C.F.R. § 83.9(b), NIOSH has already 

determined that a dose reconstruction cannot be completed for an employee at the DOE or AWE 

facility. This determination by NIOSH provides the basis for the petition by the affected claimant. 

Per § 83.14(a), the NIOSH-proposed class defines those employees who, based on completed 

research, are similarly affected and for whom, as a class, dose reconstruction is similarly not feasible. 

In accordance with § 83.14(a), NIOSH may establish a second class of co-workers at the facility for 

whom NIOSH believes that dose reconstruction is similarly infeasible, but for whom additional 

research and analysis is required. If so identified, NIOSH would address this second class in a 

separate SEC evaluation rather than delay consideration of the claim currently under evaluation (see 

Section 10). This would allow NIOSH, the Board, and HHS to complete, without delay, their 

consideration of the class that includes a claimant for whom NIOSH has already determined a dose 

reconstruction cannot be completed, and whose only possible remedy under EEOICPA is the addition 

of a class of employees to the SEC. 

This section of the report summarizes research findings by which NIOSH determined that it lacked 

sufficient information to complete the relevant dose reconstruction and on which basis it has defined 

the class of employees for which dose reconstruction is not feasible. NIOSH’s determination relies on 

the same statutory and regulatory criteria that govern consideration of all SEC petitions. 

6.1 Feasibility of Estimating Internal Exposures 

There is no indication from available documentation that thorium bioassay monitoring was performed 

for workers at the W. R. Grace, Erwin, Tennessee, facility until the late 1980s, after the cessation of 

AEC operations. Thorium-specific workplace monitoring data, such as air monitoring or surface 

contamination monitoring, are also unavailable. NIOSH has been unable to determine through 

available data the quantity of thorium-containing materials processed at W. R. Grace. It is also not 

possible to ratio thorium intakes to monitored uranium intakes because research and production 

activities involving uranium and thorium were largely independent and the relative quantities 

processed are unknown. NIOSH does not have access to sufficient thorium bioassay monitoring, air 

monitoring, or source term data to estimate potential internal exposures to thorium during the period 

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of AEC operations. Consequently, NIOSH finds that it is not feasible to estimate with sufficient 

accuracy internal exposures to thorium and resulting doses for the class of employees covered by this 

evaluation. 

Information relevant to estimating internal exposure to uranium and plutonium is provided in the 

W. R. Grace Site Profile (ORAUT-TKBS-0043). Uranium bioassay monitoring at W. R. Grace began 

in 1964; internal uranium doses beginning in 1964 can likely be reconstructed using these data. While 

dose reconstruction methods are currently under development for a revision to the Site Profile, 

NIOSH considers it likely that pre-1964 uranium doses can be reconstructed using claimant-favorable 

assumptions along with available uranium air monitoring data and bioassay data from the post-1964 

time period. Plutonium bioassay monitoring was conducted during the entire period of plutonium 

operations; NIOSH considers it likely that internal plutonium doses can be reconstructed using these 

data. NIOSH considers the adequate reconstruction of internal doses resulting from inhalation and/or 

ingestion of isotopes of uranium and plutonium likely to be feasible. 

6.2 Feasibility of Estimating External Exposures 

This evaluation responds to a petition based on NIOSH determining that internal radiation exposures 

to thorium isotopes could not be reconstructed for a dose reconstruction referred to NIOSH by the 

Department of Labor (DOL). As noted above, HHS will consider this determination to be sufficient 

without further consideration to determine that it is not feasible to estimate the levels of radiation 

doses of individual members of the class with sufficient accuracy. Consequently, it is not necessary 

for NIOSH to fully evaluate the feasibility of reconstructing external radiation exposures for the class 

covered by this report. 

However, NIOSH considers the adequate reconstruction of external dose for W. R. Grace workers 

likely to be feasible because external beta and photon dosimetry data for monitored workers at the W. 

R. Grace facility are available. Guidance for interpretation of those data is given in the Site Profile 

(ORAUT-TKBS-0043). This and other guidance also provide methodologies for estimating neutron 

dose to workers monitored for photons, and for estimating external dose to unmonitored workers. 

NIOSH considers adequate reconstruction of external dose likely to be feasible for W. R. Grace 

workers at Erwin, Tennessee, from 1958 through 1970. 

NIOSH also considers the adequate reconstruction of medical dose for W. R. Grace workers likely to 

be feasible by using claimant-favorable assumptions as well as the applicable protocols in the 

complex-wide Technical Information Bulletin, Dose Reconstruction from Occupationally Related 

Diagnostic X-Ray Procedures (ORAUT-OTIB-0006). Site-specific information regarding medical 

dose at W. R. Grace is provided in Section 4.5 of the Site Profile (ORAUT-TKBS-0043). 

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7.0 Summary of Feasibility Findings for Petition SEC-00082 

This report evaluated the feasibility for estimating the dose, with sufficient accuracy, for all AWE 

employees who may have been exposed to thorium while working at the W. R. Grace site from 

January 1, 1958 through December 31, 1970. NIOSH determined that it lacks internal dosimetry data 

necessary to reconstruct the internal exposures to thorium during this time period. Consequently, 

NIOSH finds that it is not feasible to estimate with sufficient accuracy the radiation doses resulting 

from internal thorium exposures received by members of this class of employees. 

Thorium is assumed to have been processed during the entire period of AEC weapons-related work. 

There is some discrepancy regarding the exact time period that W. R. Grace began working with 

nuclear materials at the Tennessee site. One document (GAO, 1967) states that the site received its 

first material in March 1958; however, NIOSH has personal exposure monitoring data starting in late 

1957 (see the discussion in Section 4.3 herein). NIOSH has therefore recommended that the class 

include the entire time period specified on the DOE Advocacy website (1958 through 1970; 

interpreted herein as January 1, 1958 through December 31, 1970). 

Buildings associated with thorium work included the 100 series buildings and buildings 220, 203, 233, 

234, 301, or 310 (see Section 4.4). Since exposure potential within each of these buildings may not 

have been limited to only specific groups of workers, NIOSH recommends that the class definition 

include all employees that worked in the specified buildings during the specified time period. 

NIOSH has documented in its evaluation that it cannot complete the dose reconstruction related to this 

petition. The basis of this finding is specified in this report, which demonstrates that NIOSH does not 

have access to sufficient information to estimate either the maximum radiation dose incurred by any 

member of the class or to estimate such radiation doses more precisely than a maximum dose 

estimate. 

Members of this class may have received radiation exposures from thorium inhalation and ingestion. 

NIOSH lacks sufficient information, which includes bioassay results, workplace monitoring data, or 

sufficient process and radiological source information that would allow it to estimate the potential 

internal exposure to which members of the proposed class may have been exposed. The adequate 

reconstruction of internal dose due to uranium and plutonium isotopes, external exposures from all 

radionuclides, and occupational medical doses for this class of workers is considered likely to be 

feasible. 

8.0 Evaluation of Health Endangerment for Petition SEC-00082 

The health endangerment determination for the class of employees covered by this evaluation report is 

governed by EEOICPA and 42 C.F.R. §§ 83.14(c) and 83.13(c)(3). Pursuant to these requirements, if 

it is not feasible to estimate with sufficient accuracy radiation doses for members of the class, NIOSH 

must determine that there is a reasonable likelihood that such radiation doses may have endangered 

the health of members of the class. The regulations require NIOSH to assume that any duration of 

unprotected exposure may have endangered the health of members of a class when it has been 

established that the class may have been exposed to radiation during a discrete incident likely to have 

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involved levels of exposure similarly high to those occurring during nuclear criticality incidents. If 

the occurrence of such an exceptionally high-level exposure has not been established, then NIOSH is 

required to specify that health was endangered for those workers who were employed for a number of 

work days aggregating at least 250 work days within the parameters established for the class or in 

combination with work days within the parameters established for one or more other classes of 

employees in the SEC. 

NIOSH has determined that members of the class were not exposed to radiation during a discrete 

incident likely to have involved levels of exposure similarly high to those occurring during nuclear 

criticality incidents. However, the evidence reviewed in this evaluation indicates that some workers in 

the class may have accumulated chronic radiation exposures through intakes of thorium. 

Consequently, NIOSH is specifying that health was 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. 

9.0 NIOSH-Proposed Class for Petition SEC-00082 

The evaluation defines a single class of employees for which NIOSH cannot estimate radiation doses 

with sufficient accuracy. This class includes all AWE employees who were monitored, or should 

have been monitored, for potential exposure to thorium while working in any of the 100 series 

buildings or Buildings 220, 230, 233, 234, 301, or 310 at the W. R. Grace site at Erwin, Tennessee, 

for a number of work days aggregating at least 250 work days from January 1, 1958 through 

December 31, 1970, or in combination with work days within the parameters established for one or 

more other classes of employees in the SEC. 

10.0 Evaluation of Second Similar Class 

In accordance with § 83.14(a), NIOSH may establish a second class of co-workers at the facility, 

similar to the class defined in Section 9.0, for whom NIOSH believes that dose reconstruction may not 

be feasible, and for whom additional research and analyses is required. Such a class would be 

addressed in a separate SEC evaluation rather than delay consideration of the current claim. At this 

time, NIOSH has not identified a second similar class of employees at the W. R. Grace facility at 

Erwin, Tennessee for whom dose reconstruction may not be feasible. 

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11 .0 Re fe re nces 

42 C.F.R. pt. 81, Guidelines for Determining the Probability of Causation Under the Energy 

Employees Occupational Illness Compensation Program Act of 2000; Final Rule, Federal 

Register/Vol. 67, No. 85/Thursday, p. 22,296; May 2, 2002; SRDB Ref ID: 19391 

42 C.F.R. pt. 82, Methods for Radiation Dose Reconstruction Under the Energy Employees 

Occupational Illness Compensation Program Act of 2000; Final Rule; May 2, 2002; SRDB Ref ID: 

19392 

42 C.F.R. pt. 83, Procedures for Designating Classes of Employees as Members of the Special 

Exposure Cohort Under the Energy Employees Occupational Illness Compensation Program Act of 

2000; Final Rule; May 28, 2004; SRDB Ref ID: 22001 

42 U.S.C. §§ 7384-7385 [EEOICPA], Energy Employees Occupational Illness Compensation 

Program Act of 2000; as amended; OCAS website 

HASL-61-9, 1961, Davison Chemical Company; Erwin, Tennessee; Occupational Exposure to 

Radioactive Dust, Health Protection Engineering Division; Health and Safety Laboratory; NYOO; 

USAEC; August 23, 1961; SRDB Ref ID: 11771 [part of 240000707.pdf] 

HASL-75, 1959, Davison Chemical Company; Nuclear Reactor Materials Plant; Erwin, Tennessee; 

Occupational Exposure to Radioactive Dust, Field Services Branch; Environmental Sciences 

Division; Health and Safety Laboratory; NYOO; USAEC; November 4, 1959; SRDB Ref ID: 11771 

[part of 240000707.pdf] 

OCAS-IG-001, External Dose Reconstruction Implementation Guideline; Rev. 1; Office of 

Compensation Analysis and Support (OCAS); National Institute for Occupational Safety and Health 

(NIOSH); August, 2002; SRDB Ref ID: 22401 

OCAS-IG-002, Internal Dose Reconstruction Implementation Guideline; Rev. 0; Office of 

Compensation Analysis and Support (OCAS); National Institute for Occupational Safety and Health 

(NIOSH); August, 2002; SRDB Ref ID: 22402 

ORAUT-OTIB-0004, Estimating the Maximum Plausible Dose to Workers at Atomic Weapons 

Employer Facilities; Rev. 03 PC-2; Oak Ridge Associated Universities; February 6, 2006; SRDB Ref 

ID: 19421 

ORAUT-OTIB-0006, Dose Reconstruction from Occupationally Related Diagnostic X-Ray 

Procedures; Oak Ridge Associated Universities; December 21, 2005; SRDB Ref ID: 19422 

ORAUT-TKBS-0043, An Exposure Matrix for W. R. Grace and Company in Erwin, Tennessee; Rev. 

00, Oak Ridge Associated Universities; February 14, 2006; SRDB Ref ID: 22269 

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Congress, 1986, Erwin Nuclear Fuel Services – Hearing before the Subcommittee on Energy 

Conservation and Power of the Committee on Energy and Commerce House of Representatives, 

Ninety-ninth Congress, Second Session, Serial No. 99-178; U.S. Congress; Washington, D.C.; 

September 18, 1986; SRDB RefID: 18808 

Dubinski, 1961, Trip Report: Visit to Davison Chemical Company on February 7, 1961; Leo 

Dubinski, Division of Inspection, Oak Ridge Operations; 1961; SRDB Ref ID: 11732 

GAO, 1967, Review of Accountability Controls Over Special Nuclear Materials; Nuclear Fuel 

Services, Inc.; Report to the Joint Committee on Atomic Energy; Congress of the United States; 

Comptroller General of the United States; September 14, 1967; SRDB Ref ID: 7214 

Grace, 1962, Health & Safety [Bulletin], G. C. Loud, W. R. Grace Health & Safety; October, 1962; 

SRDB RefID: 11776 

NSF, Jun06, E-mail exchanges between OCAS Health Physicist and Nuclear Fuel Services (NFS) 

regarding thorium work at W. R. Grace; June 13, 2006: SECIS ID: 128 

NSF, Aug06, Telephone conversation between OCAS Health Physicist and Nuclear Fuel Services 

(NFS) regarding thorium work at W. R. Grace; August 1, 2006: SECIS ID: 131 

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