SEC Petition Evaluation Report 

Petition SEC-00028 

Report Rev #0 Report Submittal Date: 4-7-2006 

Subject Expert(s): Bill Tankersley, Mel Chew, Bryce Rich 

Site Expert(s): Tim Adler, George Kerr 

Independent Technical Reviewer: Dan Stempfley 

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 thorium 

exposures while working in Building 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. 

Related Petition Summary Information 

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

SEC-00026 83.13 Y-12 Plant Designation Completed 

SEC-00018 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 

Lead Technical Evaluator 

(Document Owner): 

Signature on file 

Al Wolff 

April 7, 2006 

Date 

Peer Review Completed By: Signature on file 

Lavon Rutherford 

April 7, 2006 

Date 

SEC Petition Evaluation Reviewed By: Signature on file 

Jim Neton 

April 7, 2006 

Date 

SEC Petition Evaluation Approved By: 

Signature on file 

Larry Elliott 

April 7, 2006 

Date 
SEC-00028 Y-12 Plant 

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SEC-00028 Y-12 Plant 

Evaluation Report Summary: SEC-00028, Y-12 Plant 

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 USC 

(EEOICPA) and 42 CFR 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. 

Petitioner Requested Class Definition 

Petition SEC-0028, qualified on April 29, 2005, requested NIOSH to consider the following class: All 

steamfitters, pipefitters, and plumbers who worked at Y-12 from October 1944 through December 

1957. 

NIOSH Proposed Class Definition 

Based on its research, NIOSH reduced the requested class because the feasibility of performing dose 

reconstruction for all workers employed from March 1943 through December 1947 has been 

addressed in a separate evaluation report: SEC-00018. Further, based on a detailed review of facility 

records and available information, the NIOSH proposed class covered in this evaluation includes: 

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

been monitored for thorium exposures while working in Building 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. 

This evaluation was conducted in accordance with the requirements of EEOICPA, 42 C.F.R. pt. 83 

and the guidance contained in NIOSH’s Internal Procedures for SEC Evaluations, OCAS-PR-004. It 

provides information and analyses germane to considering a petition for adding a class of employees 

to the SEC. It does not provide any determinations concerning the feasibility of dose reconstruction 

that necessarily apply in the particular case of any individual energy employee who might require a 

dose reconstruction from NIOSH. 

Feasibility of Dose Reconstruction 

The feasibility determination for the class of employees covered by this evaluation report is governed 

by the requirements of the Energy Employees Occupational Illness Compensation Program Act of 

2000, as amended, 42 USC § 7384-7385 (EEOICPA) and 42 C.F.R. pt. 83. This section of the rule 

states that “Radiation doses can be estimated with sufficient accuracy if NIOSH has established that it 

has access to sufficient information to estimate the maximum radiation dose for every type of cancer 

for which radiation doses are reconstructed, that could have been incurred in plausible circumstances 

by any member of the class, or if NIOSH has established that it has access to sufficient information to 

estimate the radiation doses of members of the class more precisely than an estimate of the maximum 

radiation dose.” 

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SEC-00028 Y-12 Plant 

NIOSH has established in this evaluation that it does not have access to sufficient information to 

estimate either the maximum radiation dose incurred by any member of the proposed class or to 

estimate such radiation doses more precisely than a maximum dose estimate. The sum of information 

from the available resources is not sufficient to document or estimate the potential maximum internal 

thorium exposure to members of the proposed class, under plausible circumstances during the period 

of radiological operations at the Y-12 Site evaluated in this report. 

Health Endangerment 

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

governed by EEOICPA and 42 C.F.R. pt.83. Under these requirements, if it is not feasible to estimate 

with sufficient accuracy radiation doses for members of the class, NIOSH must also make a 

determination whether or not there is a reasonable likelihood that such radiation doses may have 

endangered the health of members of the class. The regulation requires 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 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 (excluding aggregate work day requirements). 

Per EEOICPA and 42 CFR § 83.13(c)(3), a health endangerment determination is required because 

NIOSH has determined that it does not have sufficient information to estimate the thorium internal 

dose for the members of the proposed class. 

NIOSH did not identify any evidence from the petitioners or from other resources that would establish 

that any members of the proposed class were exposed to radiation during any 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 

thorium. Consequently, NIOSH has determined that health was endangered for those 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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SEC-00028 Y-12 Plant 

Table of Contents 

Evaluation Report Summary: SEC-00028, Y-12 Plant ........................................................................... 3
 

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

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

3.0 Petitioner Requested Class/Basis and NIOSH Proposed Class/Basis ............................................ 8
 

4.0 Data Sources Reviewed by NIOSH................................................................................................ 9 

4.1 Site Profile Technical Basis Documents (TBDs) .................................................................. 9 

4.2 ORAU Technical Information Bulletins (OTIBs) and Technical Reports ............................ 9 

4.3 Facility Employees and Experts .......................................................................................... 10 

4.4 Previous Dose Reconstructions ........................................................................................... 10 

4.5 NIOSH Site Research Database .......................................................................................... 11 

4.6 ORAU Center for Epidemiologic Research Database......................................................... 11 

4.7 Y-12 Health Physics Progress Reports................................................................................ 12 

4.8 Y-12 Delta View Imaging System ...................................................................................... 12 

4.9 Documentation and/or Affidavits Provided by Petitioners ................................................. 12
 

5.0 Radiological Operations Relevant to the Proposed Class ............................................................ 12 

5.1 Y-12 Plant and Process Descriptions .................................................................................. 13 

5.2 Y-12 Functional Areas ........................................................................................................ 13 

5.2.1 Y-12 Key Uranium Processes ................................................................................. 14 

5.2.2 Y-12 Lithium Isotope Separation Process............................................................... 15 

5.2.3 Y-12 Thorium Studies ............................................................................................. 16 

5.2.4 Y-12 Waste Disposal in the S-3 and New Hope Ponds........................................... 17 

5.2.5 ORNL and Non-Uranium Activities at Y-12 .......................................................... 17 

5.3 Radiological Exposure Sources from Y-12 Operations ...................................................... 19 

5.3.1 Alpha Particle Emissions......................................................................................... 20 

5.3.2 Beta/Photon Radiation Fields .................................................................................. 20 

5.3.3 Neutron Sources ...................................................................................................... 21 

5.3.4 X-ray and Electron Generating Equipment ............................................................. 22 

5.3.5 Recycled Uranium and Other Radionuclides of Concern ....................................... 22
 

6.0 Summary of Available Monitoring Data for the Proposed Class ................................................. 23 

6.1 Y-12 Internal Monitoring Data............................................................................................ 24
 

6.2 Y-12 External Monitoring Data........................................................................................... 25 

6.3 Y-12 Air Sampling Data...................................................................................................... 26 

6.4 Summary of CER Data ........................................................................................................ 26 

6.5 Y-12 Health Physics Progress Reports................................................................................ 27
 

7.0 Feasibility of Dose Reconstruction for the Proposed Class ......................................................... 28 

7.1 Analysis of Data Sufficiency and Reliability ...................................................................... 29 

7.2 Internal Radiation Doses at Y-12 ........................................................................................ 30 

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SEC-00028 Y-12 Plant 

7.2.1 Process-related Internal Doses at Y-12 ................................................................... 31 

7.2.1.1 Urinalysis Information and Available Data........................................... 31 

7.2.1.2 Analysis of Coworker Bioassay Data.................................................... 32 

7.2.1.3 Other Types of Bioassay/Workplace Indicators .................................... 34 

7.2.1.4 Airborne Levels ..................................................................................... 34 

7.2.1.5 Other Radionuclides .............................................................................. 34 

7.2.2 Ambient Environmental Internal Radiation Doses at Y-12 .................................... 36 

7.3 External Radiation Doses at Y-12 ....................................................................................... 36 

7.3.1 Film Badge Monitoring at Y-12 .............................................................................. 37 

7.3.1.1 Gamma/X-ray, Beta, and Non-Specific Beta-Gamma Exposures......... 37 

7.3.1.2 Neutron Exposures ................................................................................ 37 

7.3.2 Ambient Environmental External Radiation Doses at Y-12 ................................... 38 

7.4 Evaluation of Petition Basis for SEC-00028 ....................................................................... 38 

7.4.1 Evaluation of General Concerns Raised in Petition SEC-00028............................. 38 

7.4.1.1 Inadequate Monitoring .......................................................................... 38 

7.4.1.2 Exposure Potential ................................................................................. 39 

7.5 Summary of Feasibility Findings for Petition SEC-00028.................................................. 39
 

8.0 Evaluation of Health Endangerment for Petition SEC-00028...................................................... 40
 

9.0 NIOSH Proposed Class for Petition SEC-00030.......................................................................... 40
 

10.0 References .................................................................................................................................... 42 

Attachments: Appendix 1: Monitoring Data Sufficiency 

Appendix 2: Spreadsheet 

Tables 

Table 4-1: Y-12 Claims Submitted Under Dose Reconstruction Rule1 ................................................ 11
 

Table 5-1: Y-12 Key Uranium Operations ............................................................................................ 14 

Table 5-2: Chronology of Lithium Production Operations ................................................................... 16 

Table 5-3: Beta and Photon Energies .................................................................................................... 21 

Table 5-4: Neutron Sources used at the Y-12 Plant .............................................................................. 21
 

Table 6-1: Non-Uranium Bioassay Results from Delta View ............................................................... 24 

Table 6-2: Summary of Available Monitoring Data for Y-12 Workers (1948-1960)........................... 26
 

Table 7-1: Type-M Uranium Intake Periods and Rates......................................................................... 32 

Table 7-2: Type-S Uranium Intake Periods and Rates .......................................................................... 33 

Table 7-3: Combined Uranium Intake Periods and Rates ..................................................................... 33 

Table 7-4: Summary of Feasibility Findings for SEC-00028 ............................................................... 40 

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SEC-00028 Y-12 Plant 

SEC Petition Evaluation Report for SEC-00028
 

1.0 Purpose and Scope 

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

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

petition for adding a class of employees to the congressionally-created Special Exposure Cohort 

(SEC). 

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

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

National Institute for Occupational Safety and Health (NIOSH). This report does not make the final 

determination as to whether or not the proposed class will be added to the SEC (see Section 2.0). 

This evaluation was conducted in accordance with the requirements of EEOICPA, 42 CFR 83, and the 

guidance contained in the Office of Compensation Analysis and Support’s Internal Procedures for the 

Evaluation of Special Exposure Cohort Petitions, OCAS-PR-004. 

2.0 Introduction 

The EEOICPA and 42 CFR 83 require NIOSH to evaluate qualified petitions requesting the 

Department of Health and Human Services (HHS) to add a class of employees to the SEC. The 

evaluation is intended to provide a fair, science-based determination of whether or not it is feasible to 

estimate with sufficient accuracy the radiation doses of the class of employees through NIOSH dose 

reconstructions.1 

42 CFR § 83.13(c)(1) states: Radiation doses can be estimated with sufficient accuracy if NIOSH has 

established that it has access to sufficient information to estimate the maximum radiation dose, for 

every type of cancer for which radiation doses are reconstructed, that could have been incurred in 

plausible circumstances by any member of the class, or if NIOSH has established that it has access to 

sufficient information to estimate the radiation doses of members of the class more precisely than an 

estimate of the maximum radiation dose. 

Under 42 CFR § 83.13(c)(3), if it is not feasible to estimate with sufficient accuracy radiation doses 

for members of the class, NIOSH must also make a determination whether or not there is a reasonable 

likelihood that such radiation doses may have endangered the health of members of the class. The 

regulation requires 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 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 at least 250 aggregated work days either solely under the 

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 www.cdc.gov/niosh/ocas. 

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SEC-00028	 Y-12 Plant 

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

classes (excluding aggregate work day requirements). 

NIOSH is required to document the evaluation in a report. For development of the evaluation report, 

NIOSH relies on its own dose reconstruction expertise as well as technical support from Oak Ridge 

Associated Universities (ORAU). Upon completion, the report is provided to the petitioners, the 

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

evaluation report, together with the petition, petitioner(s) comments, and other information 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 decisions on behalf of HHS. The Secretary of HHS 

will make final decisions, taking into account the NIOSH evaluation, the advice of the Board, and the 

proposed decision issued by NIOSH. The petitioner(s) may also seek a review of certain types of final 

decisions issued by the Secretary of HHS.2 

3.0 Petitioner Requested Class/Basis and NIOSH Proposed Class/Basis 

Petition SEC-00028, qualified on April 29, 2005, requested that NIOSH consider the following class: 

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

1957. 

The petitioner provided information and affidavit statements in support of the petitioner’s belief that 

accurate dose reconstruction over time is impossible. NIOSH considered the following information 

and affidavit statements sufficient to qualify SEC-00028 for evaluation. 

The petitioner asserted by affidavit that the energy employees listed on the petition did not receive 

or witness monitoring of radiation exposures or radiation doses for steamfitters, pipefitters, and 

plumbers. 

Steamfitters, Pipefitters, and Plumbers worked mostly in maintenance and new construction. New 

construction would have limited their exposure potential. However, maintenance activities were 

conducted all over the site. Worker interviews indicate that maintenance personnel had the 

potential to be exposed to all sources of exposure on site, because the maintenance group 

supported the entire site. Therefore, the maintenance personnel had the potential for exposure to: 

•	 Uranium isotopes during uranium enrichment and recycling operations (neptunium) 

•	 Thorium when two test batches were processed through the Building 9204-3 calutrons (for 

enrichment), during Research and Development activities in Buildings 9202, 9204-1, 9204-3, 

9206, and 9212, and when used as a co-precipitation media to increase the uranium recovery 

percentage from decontamination solutions. 

•	 Plutonium during the 1950s when plutonium was enriched with the calutrons 

•	 Polonium 208 when polonium was produced with the cyclotron 

•	 Other short lived radioactive isotopes produced by the cyclotron 

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

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

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SEC-00028 Y-12 Plant 

The information provided by the petitioner supported the qualification of the petition for further 

consideration by NIOSH, the Board, and HHS. 

NIOSH has already completed an evaluation of the feasibility of performing dose reconstruction for 

all workers at Y-12 employed from March 1943 through December 1947. The evaluation, 

summarized in report: SEC-00018, found that it was not feasible to estimate the radiation doses of this 

class of employees. SEC-00018 was considered by the Advisory Board on Radiation and Worker 

Health (the Board) on July 5-7, 2005 and the Board recommended the addition of the class to the 

SEC. The Secretary of HHS approved the addition of the class to the SEC on August 25, 2005. The 

designation of this class to the SEC became effective on September 24, 2005. 

 The NIOSH-proposed class evaluated in this report includes employees of the DOE or DOE 

contractors or subcontractors who were monitored or should have been monitored for thorium 

exposures while working in Building 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. This report completes the evaluation of Petition SEC-00028. 

4.0 Data Sources Reviewed by NIOSH 

NIOSH identified and reviewed many data sources to determine the availability of information 

relevant to determining the feasibility of dose reconstruction. This included determining the 

availability of information on personal monitoring, area monitoring, industrial processes, and 

radiation source materials. The following sections summarize the data sources identified and 

reviewed. 

4.1 Site Profile Technical Basis Documents (TBDs) 

A Site Profile provides specific information concerning the documentation of historical practices at 

the specified site. Dose reconstructors can use the Site Profile to evaluate internal and external 

dosimetry data for monitored and unmonitored workers, and to serve as a supplement to, or substitute 

for, individual monitoring data. A Site Profile consists of an Introduction and five Technical Basis 

Documents (TBDs) that provide process history information, information on personal and area 

monitoring, radiation source descriptions, and references to primary documents relevant to the 

radiological operations at the site. As part of this evaluation, the following TBDs were reviewed: 

• TBD for the Y-12 Plant – Introduction, ORAUT-TKBS-0014-1; October 11, 2005 

• TBD for the Y-12 Plant – Site Description, ORAUT-TKBS-0014-2; October 11, 2005 

• TBD for the Y-12 Plant – Occupational Medical Dose, ORAUT-0014-3; October 11, 2005 

• TBD for the Y-12 Plant – Occupational Environmental Dose, ORAUT-0014-4; October 11, 2005 

• TBD for the Y-12 Plant – Occupational Internal Dose, ORAUT-0014-5; February 14, 2006 

• TBD for the Y-12 Plant – Occupational External Dose, ORAUT-0014-6; February 14, 2006 

4.2 ORAU Technical Information Bulletins (OTIBs) and Technical Reports 

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SEC-00028	 Y-12 Plant 

ORAU Technical Information Bulletins (OTIB) and Technical Reports are general working 

documents that provide guidance concerning the preparation of dose reconstructions and particular 

sites or categories of sites. NIOSH reviewed the following OTIBs and Technical Reports which 

described the individual dose adjustment procedure and internal dosimetry coworker data at the Y-12 

Plant: 

•	 Technical Information Bulletin: Individual Dose Adjustment Procedure for Y-12 Dose 

Reconstruction, ORAUT-OTIB-0013; September 9, 2004 

•	 Technical Information Bulletin: Bayesian Methods for Estimation of Unmonitored Y-12 External 

Penetrating Doses with a Time-Dependent Lognormal Model, ORAUT-OTIB-0015; September 9, 

2004 

•	 Technical Information Bulletin: Internal Dosimetry Coworker Data for Y-12, ORAUT-OTIB0029; April 5, 2005 

•	 Analysis of Electronic Personnel Exposure Data from Y-12, ORUAT-RPRT-0022; June 24, 2005 

•	 Historical Evaluation of the Film Badge Dosimetry Program at the Y-12 Facility in Oak Ridge, 

Tennessee: Part 1—Gamma Radiation, ORAUT-RPRT-0032; March 21, 2005 

•	 Historical Evaluation of the Film Badge Dosimetry Program at the Y-12 Facility in Oak Ridge, 

Tennessee: Part 2—Neutron Radiation, ORAUT-RPRT-0032; March 21, 2005 

•	 Technical Information Bulletin: External Radiation Monitoring at Y-12 During 1948-1949 Period, 

Rev. 01, ORAUT-OTIB-0047; September 20, 2005 

4.3 Facility Employees and Experts 

Additional information was obtained by interviewing nine Y-12 workers employed for at least some 

time during the 1948 to 1957 operational period. Selection was based on document references and 

distribution lists, recommendations from those being interviewed, and personal knowledge from 

within the Center for Epidemiological Research (CER). Efforts were made to interview people who 

held differing job types. The employee interviews ultimately included employees who worked on 

production lines, held supervisory positions, were members of the proposed class, and were health 

physicists. 

Information obtained during the employee interviews contributed to the general knowledge base for 

Y-12 activities, thus, aiding in the dose reconstruction feasibility determination. The information 

gained from the employee interviews included (but was not limited to) processing details and 

timelines, supervisory roles and responsibilities, exposure potential, contamination minimization 

efforts, weapons assembly/disassembly activities, and information about monitoring practices. 

4.4 Previous Dose Reconstructions 

NIOSH reviewed its dose reconstruction database, NIOSH OCAS Claims Tracking System (NOCTS), 

to identify dose reconstruction cases under EEOICPA that might provide information relevant to the 

petition evaluation. Table 4-1 provides a results summary of this review for the January 1948 through 

December 1957 timeframe (Data available as of: March 8, 2006). 

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SEC-00028 Y-12 Plant 

Table 4-1: Y-12 Claims Submitted Under Dose Reconstruction Rule1 

Description Totals 

Total number of cases submitted for energy employees who meet the class definition criteria 96 

Number of dose reconstructions completed for energy employees who were employed during the 

years identified in the class definition 49 

Number of cases for which internal dosimetry records were obtained for the identified years in the 

class definition 10 

Number of cases for which external dosimetry records were obtained for the identified years in the 

class definition 0 

Note: 

1

Results summary for the time period of January 1948 through December 1957. 

NIOSH reviewed each claim to determine whether internal and/or external personal monitoring 

records could be obtained for each employee. 

NIOSH has been able to obtain personal monitoring records and area monitoring data applicable to the 

evaluation of the proposed class in this report. When looking at previous dose reconstructions, NIOSH 

also reviewed the interviews conducted with claimants for these cases to determine whether they had 

provided relevant information for dose reconstruction. The interviews provided some information that 

would be useful for future dose reconstructions (i.e., work locations, hours worked, and hazards 

encountered). 

4.5 NIOSH Site Research Database 

The NIOSH Site Research Database (SRDB) was reviewed for documents to support the evaluation of 

the proposed class. Currently, there are 496 documents contained within this database pertaining to Y12; these documents are largely in the form of reports, manuals, and memos. These documents include 

information for Y-12 regarding dust sampling, dose rate surveys, urinalysis data, the radiological 

control program, the film badge dosimetry program, medical monitoring, process materials, as well as 

process description information for the Y-12 Site. 

4.6 ORAU Center for Epidemiologic Research Database 

From 1978 through the 1980s the Y-12 Site delivered electronic files of worker data to the Center for 

Epidemiologic Research as a resource for the Health and Mortality Studies conducted for the 

Department of Energy (DOE) and its predecessor agencies. Files containing records for more than 

17,000 Y-12 workers were received on magnetic tapes and included beta, gamma, and neutron 

radiation measurements, penetrating dose and skin dose, urinalyses results, and additional relevant 

information. CER transferred all the data from tape to disk and later constructed a carefully linked 

relational database with a standardized file format. Since 2002, the data have resided in a Microsoft © 

SQL Server database. Records contain all data elements received from the original Y-12 files 

unaltered, including first, middle, and last name, plant badge number, social security number, year of 

record, quarter of record, quarterly summations of dose readings for the monitoring period (weekly, 

monthly, or quarterly), and other work history, processing, and demographic data. This database 

includes 834,399 external monitoring records dating from 1950 through 1998; 694,221 urinalysis 

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SEC-00028 Y-12 Plant 

(bioassay) records spanning from 1950 through 1998; and 100,652 whole body counting records 

dating from 1961 through 1991. Details of the availability and quality of data relevant to the subject 

class is presented and discussed in Section 7.0 of this evaluation and Appendix 1. 

4.7 Y-12 Health Physics Progress Reports 

In addition to the numerous memos and other documents that NIOSH has available regarding Y-12, 

NIOSH has discovered that Y-12 Health Physics activities were documented in a series of reports that 

have been kept on file within the Y-12 Plant. These reports were produced with varying frequency 

over time (monthly, quarterly, and semi-annually) and have been retrieved from as early as September 

1947. 

Data typically contained within the Health Physics Progress reports includes external exposure rate, 

contamination level ranges (minimum, mean, and maximum results), alpha hand counting data, 

sampling locations, and sampling frequencies. Air contamination concentrations are most frequently 

presented as average uranium air concentrations in d/min/m3

. Sampling locations are detailed as are 

sample type (e.g. swipe, scan, breathing zone, general air, etc.) and specific jobs are assessed. Overall 

sampling frequencies reflect an effort to assess contamination levels in all plant areas with some 

regularity but maintain a focus on the known highest exposure locations associated with production. 

Contamination and exposure potentials associated with new and/or short duration research and 

developmental type activities were also assessed and documented. Longer lasting, non-uranium 

production activities such as the cyclotron work were given regular attention within the monitoring 

program and progress reports. 

4.8 Y-12 Delta View Imaging System 

Maintained by Y-12, the Delta View image system is comprised of scanned images of hard copy 

reports and monitoring data print-outs associated with Y-12 personnel. Not a typical database, Delta 

View stores copied images of documents that are searchable to the extent that key words have been 

associated with the individual images when initially loaded. The images in Delta View are therefore 

accessible by individual name and/or ID numbers, analysis, and sample type among other parameters. 

Delta View’s focus has been primarily to maintain worker records that are generally not associated 

with the “routine” uranium urinalysis and external monitoring program. Examples of data in Delta 

View include information describing special studies, non-uranium urinalyses, medical evaluations, 

and corrections to memos. 

4.9 Documentation and/or Affidavits Provided by Petitioners 

In qualifying and evaluating the petition, NIOSH reviewed the following document submitted by the 

petitioners and received March 28, 2005: 

1. Affidavit by petitioner, March 24, 2004; SECIS document id: 8544 

5.0 Radiological Operations Relevant to the Proposed Class 

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The following subsections summarize the radiological operations at the Y-12 Plant from January 1948 

to December 1957 and the information available to NIOSH to characterize particular processes and 

radioactive source materials. From available sources, NIOSH has gathered process and source 

descriptions, information regarding the identity and quantities of each radionuclide of concern, 

information describing the process through which the radiation exposures of concern may have 

occurred, and information regarding the physical environment in which radiation exposures may have 

occurred. 

Claimant interviews indicate that the work performed by the class defined by the petitioner varied 

considerably. Some workers were assigned to an individual task within a single area for an extended 

period and other workers were assigned to multiple areas over their employment period. However, the 

wide-spread application of the worker class duties warrants summarizing the broad scope of 

radiological operations that occurred during the 1948 through 1957 timeframe. Predominantly 

functioning in new construction, maintenance, or repair capacities, it is expected that members of this 

proposed class generally had only intermittent affiliation with many of the activities and exposure 

sources described within this section, Section 5.0. Potential exposures received by members of this 

class from a given production activity for example, would in general be expected to be lower than 

doses received by daily operators for that production activity. A comparison of available monitoring 

results for the petitioner proposed class to other worker monitoring results is provided in Appendix 1. 

5.1 Y-12 Plant and Process Descriptions 

Located at the eastern section of the Oak Ridge Reservation in Oak Ridge, Tennessee, the Y-12 Plant 

occupies approximately 811 acres (0.67 mile wide and 3.2 miles long). The plant was initially 

constructed in the fall of 1942 under the direction of the U.S. Army Corps of Engineers of the 

Manhattan Engineer District (MED). Stone and Webster Construction Co. of Boston, Massachusetts 

served as the general engineering contractor for the Y-12 Facility, which eventually cost over $400 

million. 

Using an electromagnetic separation process within a calutron, the original mission of Y-12 was to 

separate fissionable isotopes of uranium (uranium-235) from uranium feedstock for use in the 

Hiroshima Atomic Bomb. Radiological operations, processes, and dose reconstruction information 

relevant to this specific uranium enrichment work is covered in a separate evaluation report: SEC 

Petition Evaluation Report SEC-00018. 

While the SEC-00018 report evaluates the years1943 through1947, the SEC-00028 evaluation focuses 

on a time period that falls within what is generally described as the “second era” of Y-12 operational 

history. The electromagnetic separation process for uranium-235 enrichment (calutrons) was 

discontinued in 1947 in favor of the more efficient gaseous diffusion process. Extending from 1947 

through1992, the primary mission of the second era was the production of key components of nuclear 

weapons and test devices. During this time, the vast majority of the work at Y-12 involved uranium 

processing, although other radioactive materials such as thorium, tritium, polonium, and transuranics 

were also present in very small quantities during the SEC period. During the 1948 through 1957 time 

period, the Y-12 operating contractors were Carbide and Carbon Chemicals and Union Carbide 

Nuclear Company, both divisions of Union Carbide Corporation predecessor companies. 

5.2 Y-12 Functional Areas 

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Y-12 Plant operations included the following functional areas: 

• Key Uranium Processes 

• Lithium Isotope Separation Process 

• Thorium Studies 

• Waste Disposal in the S-3 and New Hope Ponds 

• ORNL and Non-Uranium Activities at Y-12 

5.2.1 Y-12 Key Uranium Processes 

The following table, Table 5-1, summarizes the key uranium processes as well as the buildings and 

dates of operation involved. 

Table 5-1: Y-12 Key Uranium Operations 

Key Uranium Operations Buildings Involved Dates of 

Operation 

Uranium Recovery and Recycle: Y-12 stopped enriching 9202, 9203, 9206, 9212 1945–1951 

uranium after WWII and operations centered on uranium recovery ▪ 9202, 9203 received 1950s–1990s 

and recycling of residual uranium found on equipment and scrap depleted uranium, slightly 

material. Operations included mechanical scraping and brushing, enriched uranium, and normal 

nitric acid washing, and distillation and recovery of solid uranium uranium. 

compounds adhered to surfaces. Uranium contaminated materials ▪ 9206 was the main uranium 

included condensates, scrubber solutions, raffinates, destructive recovery and recycle facility 

distillates, oils, and miscellaneous residues. These Y-12 Facilities and housed sanding, grinding, 

handled mostly normal uranium and depleted uranium. chemistry and incinerator 

operations. 

▪ 9212 housed the largest 

chemical operations for 

enriched uranium purification, 

recovery and chemical 

conversion, as well as normal 

and depleted uranium 

machining operations 

Uranium Salvage: Salvage operations involved recovery of 

uranium from materials not considered production equipment, such 

as liquid and solid waste materials from maintenance/cleanup 

activities such as mop water, laundry washes, and floor drain 

residues. In an effort to recover uranium, combustible materials 

such as wood, rags, sponges, filter paper, and carbon solids were 

burned in muffle furnaces and incinerators. Other salvage 

operations included mechanical scraping and brushing, nitric acid 

washing, and distillations. 

9206, 9207, 9211 

▪ 9206 housed salvage 

operations and process 

operations were similar to 

9207 and 9211. 

▪ 9207 and 9211 processed 

incinerated solid waste and 

recovered normal and slightly 

enriched uranium. 

1945–1951 

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Table 5-1: Y-12 Key Uranium Operations 

Key Uranium Operations Buildings Involved Dates of 

Operation 

Uranium Preparation/Recycle for Weapon Component 

Operations: Y-12 began a continuous growth of uranium weapons 

component manufacturing operations and handled a variety of 

uranium compounds and enrichment. Enriched uranium prepared 

for reduction to metal involved conversion of uranium hexafluoride 

to uranium fluoride purification of uranyl nitrate solutions, 

precipitation for uranium recovery, and then reduction to uranium 

metal. 

 9212 

▪ 9212 housed the largest 

chemical operations for 

enriched uranium purification, 

recovery and chemical 

conversion, as well as normal 

and depleted uranium 

machining operations 

1952–1995 

Uranium Forming/Machining for Weapon Component 

Operations: Y-12 had operations capable of casting, rolling, and 

machining uranium metal. These operations handled enriched 

uranium, depleted uranium, and normal uranium. Uranium was 

pressed, rolled, shaped, and machined into finished weapon 

components. 

9201-5, 9204-4, 9215, 9998 

▪ 9201-5, 9204-4 housed 

depleted uranium 

▪ 9215 housed enriched 

uranium 

▪ 9998 contained H-1 foundry 

operations that included 

depleted uranium recycle and 

parts manufacturing. 

1952–1995 

Uranium Component Assembly: Machined components were sent 9202, 9204-2, 9204-2E 1952–1995 

through finishing operations that included drilling, welding, ▪ 9204-2, 9204-2E housed 

brazing, polishing, and final specification checks. Assembly uranium assembly operations. 

operations generally were not associated with significant releases ▪ 9202 was primarily used for 

of uranium compounds. Any measurable amounts of uranium were early pilot scale operations 

recovered and recycled back into the production stream. Uranium that involved design and 

was routinely recovered from articles such as rags, paper towels, implementation of fabrications 

oils, and liquid waste products. Process exhaust stacks were and assembly processes and 

equipped with high efficiency particulate air (HEPA) filtrations and final inspection procedures. 

periodically inspected for buildup of uranium. 

5.2.2 Y-12 Lithium Isotope Separation Process 

Following the Soviet test of a Hydrogen Bomb in 1953 in which lithium was detected in the fallout, a 

"crash" program implemented for the purpose of developing a large scale lithium separation plant. 

Thus, when the decision was made to pursue the development of the hydrogen bomb, Y-12 was 

chosen as the site for the separation of lithium-6 from the more abundant lithium-7. 

NOTE: Although not a source term for dose reconstruction, the Lithium Isotope Separation process 

provides additional detail of the activities conducted during the class period.. 

The process concentrated lithium-6 and combined the lithium with deuterium, a heavy isotope of 

hydrogen, to form lithium deuteride. Lithium deuteride is the major source of fuel for the hydrogen 

fusion which takes place in a hydrogen bomb explosion. 

Not unlike the earlier Manhattan Project, a massive mobilization of personnel and material resulted in 

operational plants in less than fifteen months. Lithium production cascades were housed in large 

buildings formerly used for uranium separation. Production for various separation processes started 

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between 1953 and 1955. The chronology of lithium operations and facilities is described below in 

Table 5-2: 

Table 5-2: Chronology of Lithium Production Operations 

Time Period Operations 

1950, 1951 Operated building 9733-2 - Development facility for elex (Electrical Exchange) 

process 

1951, 1952 Operated building 9733-1 - Development facility for Orex (Organic Exchange) 

process 

September 1951 - 1955 Operated building 9201-2 - Pilot plants for elex and colex processes 

April 1953 - May 1955 Operated building 9201-2 - Pilot plant for Orex process 

1953 - Spring 1956 Operated building 9204-4 - Elex Production Plant 

January 1955 - February 1959 Operated building 9201-5 - Colex Production Plant 

Production activities stopped after 1959. In 1962 partial operations resumed thru May of 1963. 

Lithium production at Y-12 was terminated in 1963 as the stockpile grew, and the material could be 

recycled from retired warheads. 

5.2.3 Y-12 Thorium Studies 

During the 1948 through 1958 time period, quantities of thorium at Y-12 ranged from tens of 

kilograms in 1948 to hundreds of kilograms in 1952 to thousands of kilograms in 1955. Work with 

thorium at Y-12 during this time period was mainly of a research and development nature with the 

exception of one activity. During the class period there were a number of activities conducted that 

involved quantities of thorium. These activities are presented in chronological order below: 

1.	 Decontamination and decommissioning of the calutrons (primarily the 9201 Buildings) 

occurred when the uranium enrichment operations using the alpha-track calutrons were 

terminated in 1946. This work involved cleaning out the uranium from the calutron vacuum 

chambers and the product “pockets.” The uranium was removed by scraping and acid 

dissolution. A note in a Y-12 Health Physics Progress report indicates that thorium was used 

as a co-precipitation media to increase the uranium recovery percentage from decontamination 

solutions. Although, uranium enrichment with the calutrons stopped in 1947, it’s not clear 

whether Y-12 continued to use Thorium as a co-precipitating agent for later calutron 

operations. 

2.	 In 1952, the Isotopic Separation program, which utilized the beta calutrons in Building 9204-3, 

used small quantities of thorium for specific isotopic separation and purification (Y-12 Plant; 

Y-12 Plant, 1991). 

3.	 In 1956, thorium-oxide blending and slurry work associated with Research and Development 

activities in Building 9204-1(Y-12 Plant, 1956). 

4.	 Thorium was used (kilogram quantities) in the Research and Development laboratories to 

develop and define the processes that would be incorporated in major thorium processing that 

occurred after the time period evaluated in this report. As reported in a 1957 Health Physics 

Progress Report, thorium work is confined to one area in Building 9202, where the 

Development Department does some work with thorium (Y-12 Health Physics Department, 

1957). 

5.	 Thorium was used in kilogram quantities to support ORNL Research and Development 

activities in Buildings 9206 and 9212 at Y-12. 

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Based on the Y-12 thorium activity research performed for this evaluation report, another activity was 

performed with potential thorium exposure. However, the timeframe for this activity falls outside of 

the SEC period evaluated in this report. The information is provided as supporting information for the 

class definition time period. This thorium work began as a pilot program in 1958. Following the pilot 

program was a 17-year period, beginning in 1960, where metric tons of thorium were processed 

(ORAUT-TKBS-0014-2 Rev. 00). This also corresponds to the period of available personnel 

monitoring and the incorporation of in vivo monitoring in the Y-12 Health Physics program. One 

hundred and three thorium fecal sample results were included in Delta View for the 1958 through 

1960 time period; a small number of samples were also identified for the years of 1961 and 1962. 

Based on a review of the monitoring data, lung counting was the primary bioassay method used for 

thorium internal monitoring during the full scale operational period. 

5.2.4 Y-12 Waste Disposal in the S-3 and New Hope Ponds 

Between 1951 and 1984, four seepage pits known as the S-3 ponds were used to dispose of over 

2,700,000 gallons of a variety of liquid wastes, including concentrated acids, caustic solutions, mop 

waters, and by-products such as uranium and other heavy materials, from the uranium recovery 

processes. These unlined seepage pits, referred to at one time as a "witch's cauldron," were designed 

to allow liquid either to evaporate or percolate into the ground. Various metal impurities and 

radionuclides stripped from highly enriched uranium during the solvent extraction steps in Buildings 

9212 and 9206 (approximately 10% to 30% of recycled uranium, plutonium, neptunium, and 

technetium) were discharged with the dilute nitric acid and other process-derived acid wastewater in 

to the S-3 ponds prior to the mid 1980s (ORAUT-TKBS-0014-2 Rev. 00). 

New Hope Pond was constructed and placed in operation in the 1950s to provide a retention basin at 

the East end of Y-12. The pond facilitated mixing of water and offered a sampling point for rainwater 

runoff, once-through cooling water, steam plant boiler blow-down, and secondary production process 

wastewaters. The pond also functioned to remove any suspended contamination from rainwater, 

miscellaneous releases from various tank farms and storage yards, and inadvertent releases from 

process buildings. 

5.2.5 ORNL and Non-Uranium Activities at Y-12 

Space at Y-12 was utilized by the Oak Ridge National Laboratory (ORNL) Research and 

Development divisions for several projects. Four of the projects included the beta calutrons, the 86­

inch cyclotron, the Criticality Experiments Facility, and the 5-MeV Van de Graff Accelerator, all of 

which are briefly summarized below. Several of these projects involved the production and/or 

separation and purification of both stable and radioactive isotopes. A listing of these isotopes is 

presented in Appendix 2. The radioactive isotopes were produced generally in small quantities and/or 

had short half lives. 

Work performed at these facilities presented external and internal radiation exposure potential. At 

times, Y-12 workers supported efforts at the facilities and in some cases Y-12 employees were 

administratively transferred to ORNL. 

Beta Calutrons 

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During the 1950s, the calutrons at Y-12 were used for the production, enrichment, and purification of 

an extensive list of stable and radioactive isotopes for medical research worldwide (see Appendix 2). 

A plutonium isotopic separation program using the calutrons was also in the planning and design 

stages during the period evaluated in this report (Wilcox, 1999). 

Based on a series of progress reports (approximately 30) that were produced by the Electromagnetic 

Research Division and subsequent organizations, it is evident that plutonium isotopic enrichment 

work was occurring in 1952 and 1957. Also documented, plutonium urinalyses were performed 

during the years 1952 through at least 1965, air monitoring was performed, and personnel protection 

was provided for by clothing and respiratory protection. Calutron facilities provided for double 

containment of the calutron(s) and glove box handling of collection pockets. 

86-Inch Cyclotron 

The 86-inch cyclotron began operation in November 1950 and was used to perform radiation damage 

studies for the Nuclear Aircraft Project. As the world's largest fixed-frequency proton cyclotron, it 

produced a proton beam four times more intense than any other cyclotron. One of the original uses of 

the Oak Ridge 86-inch cyclotron was the production of polonium-208 (ORNL-1392; Butler 1963; 

Johnson, 1994). Polonium was produced in the 86-inch cyclotron as early as 1951. In 1952, internal 

revisions of the position and mounting of the ion source resulted in proton energy of 23 MeV. At the 

higher energy, the polonium-208 yield was more than doubled and a total of approximately 9 Ci of 

polonium-208 were produced before the project was terminated in August of 1953 (ORNL-1392). 

During the next few years, the groundwork was laid for the production of neutron-deficient 

radioisotopes (Butler, 1963). However, from 1952 to 1961, the 86-inch cyclotron was used primarily 

for nuclear physics research by the ORNL Electronuclear Research Division (Howard 1954; 

Livingston, 1958). Isotope production time was made available only when it did not interfere with the 

primary program (Butler, 1963). 

Appendix 2 contains information regarding the stable and radioactive isotopes produced and/or 

separated and purified at Y-12. 

Critical Experiments Facility 

Prior to the construction of the Critical Experiments Facility in 1950, several critical experiment 

programs had been carried out at ORNL and the K-25 Oak Ridge Gaseous Diffusion Plant 

(ORNL/TM-349 Rev. 1). However, in 1949, due to the expected demands for further experimentation 

in (1) the safety of metallurgical and chemical processes and (2) the support of new reactor designs, 

the inadequacy of the previous facilities was recognized. This inadequacy was further emphasized by 

a program in Oak Ridge on the development of nuclear propulsion for aircraft (Johnson, 1994). As a 

result, it was decided that a laboratory adequate for a wide variety of critical experimentation be 

established, and that the various programs of critical experiments in Oak Ridge be combined and the 

work administered by ORNL (ORNL/TM-349 Rev. 1). Thus, near-critical and criticality experiments 

were started at the Critical Experiments Facility in late August and early September 1950. 

The Critical Experiments Facility was at a remote site in the Southwest portion of the Y-12 complex 

in a pocket formed by surrounding hills as much as 200 feet higher than the Critical Experiments 

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SEC-00028 Y-12 Plant 

Facility building itself (ORNL/TM-349, ORNL/TM-349 Rev. 1). During its operational years, access 

to the Critical Experiments Facility was restricted by means of a chain link fence (ORNL/TM-349, 

ORNL/TM-349 Rev. 1). 

5-MeV Van de Graff Accelerator 

A 5-MeV Van de Graff accelerator was also operated in the East end of Building 9202-2 in the early 

1950s for a period of about one year while a permanent structure was being built for the accelerator at 

the X-10 site. The 5-MeV Van de Graff Accelerator was an X-10 project and the health physicists 

and all other workers at the 5-MeV Van de Graff were X-10 employees. 

5.2.6 Weapons Assembly and Disassembly 

Information regarding weapons assembly and disassembly work at Y-12 was obtained through 

document reviews and through a series of interviews with employees with first-hand knowledge of Y12 weapons activities during the evaluated class time frame. Six Y-12 employees were interviewed 

who had the following job titles while employed at Y-12: 

• Assembly Division Head 

• Assembly Dept Head 

• Assembly Foreman 

• Disassembly Foreman 

• Chemical Operator 

• Health Physicist 

From these sources it was learned that weapons assembly/disassembly work began as early as 1952­

1953. Typically, weapons components were assembled at Y-12 and then sent to other site(s) for 

further assembly. Much more assembly work was done than disassembly work. Prior to 1960, work 

was done in glove boxes or in open areas which were by necessity, very clean environments. The 

exposure potential was from external radiation only, since the parts for assembly were essentially clad 

or otherwise sealed. Badges were worn on normal plant clothing. 

During the weapons assembly and disassembly operations, a small crew (a maximum of three plus 

one foreman) was used. These crews never included maintenance or crafts people. The workers 

interviewed agreed that presence of pipefitters, plumbers, and steamfitters in the assembly areas was 

infrequent and only after the assemblies were either covered and/or removed, thus, making radiation 

exposure potential essentially nonexistent. In addition, when maintenance personnel were needed in 

the area, they were always required to wear personal dosimeters. 

5.3 Radiological Exposure Sources from Y-12 Operations 

Over the 1948 through 1957 time period, many individual research and development projects occurred 

at Y-12 involving various radiological exposure sources. Besides the thorium associated with two test 

batches processed through Building 9204-3 calutrons (for enrichment), Research and Development 

activities in Buildings 9202, 9204-1, 9206, and 9212 and when used as a co-precipitation media the 

principal source term at the plant was (and continues to be) uranium process materials. The uranium 

materials existed in any of the standard ICRP-68 clearance classes or in any combination thereof. 

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Additionally, because Y-12 served primarily as a nuclear weapons fabrication and production facility 

during this time, the uranium that was present included natural uranium, depleted uranium (uranium238), and enriched uranium (uranium-235). 

5.3.1 Alpha Particle Emissions 

Both uranium-235 and uranium-238 are primarily alpha-particle emitters. As such, gamma radiation 

exposure potential was very low for most members of this class. The majority of the radiological 

exposure potential at Y-12 has been internal and chronic in nature, resulting from inhalation or 

ingestion of particles comprised of various forms of uranium during nuclear material fabrication and 

processing work. Uranium-bearing chemicals present at the facility during the 1948 through 1957 

time period included (but are not limited to): 

• Uranium oxide (U3O8) 

• Uranium dioxide (UO2) 

• Uranium trioxide (UO3) 

• Uranium hexafluoride (UF6) 

• Ammonium diuranate [(NH4)2U2O7] 

• Uranyl nitrate [UO2(NO3)2] 

• Uranium peroxide (UO4 ·2H2O) 

• Uranium tetrachloride (UCl4) 

• Uranium pentachloride (UCl5) 

• Uranium tetrafluoride (UF4) 

Research and Development activities, as previously discussed, involving thorium (including thorium230 and thorium-232 in limited quantities) were also performed during the evaluation period. 

However, concerns associated with thorium alpha emissions/exposures were limited to Building 9202, 

9204-1, and 9204-3. 

5.3.2 Beta/Photon Radiation Fields 

Though less of a threat than internal exposure, significant external exposure potential existed at times 

in specific locations/activities. The external workplace radiation fields of most concern were due to 

processes involving either enriched uranium or depleted uranium. Additional radiation fields of 

concern (summarized in Table 5-3 below) involved industrial radiation generating equipment (X-rays 

and electron accelerators) and isotopic gamma-ray and neutron sources for testing purposes (e.g., 

cobalt-60, californium-252, and radium-beryllium or polonium-beryllium neutron sources). 

As noted previously in Section 5.3.1, the uranium-235 and uranium-238 contained in Y-12 uranium 

materials are primarily alpha emitters. However, uranium-235 does emit a 185-KeV photon in 54% of 

its decays and short lived uranium-238 decay products (thorium-234, protactinium-234m, and 

protactinium-234) are beta and photon emitters. From an external dose standpoint, the most significant 

radiations emitted by these decay products of uranium-238 are: (1) the 2.29-MeV beta particle from 

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protactinium-234m, and (2) the photons emitted by protactinium-234 with energies as large as 1.962 

MeV. 

Table 5-3 summarizes beta and photon energies as associated with various Y-12 processes (ORAUTTKBS-0014-6 Rev. 00). 

Table 5-3: Beta and Photon Energies 

Y-12 Site Processes Building Operations Radiation type Energy 

Selection Percent Begin End 

Enriched uranium product recovery 

and salvage operations 

9203 1947 1951 Beta 

Photon 

> 15 KeV 

30-250 KeV 

100% 

9206a

 1947 1959 100%

9211 1947 1959 

9201-1 1952 1963 

Uranium chemical operations and 

weapon production operations 

9202 1947 1995 Beta 

Photon 

> 15 KeV 

30-250 KeV 

100% 

9206a

 1947 1995 100%

9212b

 1949 Ongoing 

Special nuclear material receiving and 

storage 

9720-5 1949 Ongoing Photon 30-250 KeV 100% 

Uranium forming and machining for 

weapon component operations 

9201-5 1949 Ongoing Beta 

Photon 

> 15 KeV 

30-250 KeV 

100% 

9204-4 1949 Ongoing 100%

9215 1950 Ongoing 

Depleted uranium process operations 

9201-5 1949 Ongoing Beta 

Photon 

> 15 KeV 

30-250 KeV 

> 250 KeV 

100% 

50% 

50% 

9204-4 1949 Ongoing 

9766 1949 1995 

9998 1949 Ongoing 

Final weapon component assembly 

operations 

9204-2 1952 Ongoing Beta 

Photon 

> 15 KeV 

30-250 KeV 

100% 

9204-2E 1952 Ongoing 100%

ORNL 86-inch cyclotron 9201-2 1950 Ongoing Photon 30-250 KeV 

>250 KeV 

50% 

50% 

Chemical assay and mass 

spectrometry laboratories 

9203 1947 Ongoing Photon Specific to 

radiation 

source. Photon 

default values: 

30-250 KeV 

>250 KeV 

50% 

50% 

Radiographic laboratory 9201-1 1947 Ongoing Photon 

Calibration laboratory 9983 1949 Ongoing Photon 

Weapon component assay laboratory 9995 1952 Ongoing Photon 

Notes:
 a

Building 9206 Complex includes Buildings 9768, 9720-17, 9409-17, 9510-2, 9767-2, and the east and west tank farm 

pits.

b

Building 9212 Complex includes Buildings 9809, 9812, 9818, 9815, and 9980. 

5.3.3 Neutron Sources 

Radionuclide sources that produced neutrons by alpha particle reactions in boron or beryllium 

provided a convenient source of neutrons for a number of applications (Rees, 1967). Their use at the 

Y-12 Plant has been summarized in the following table. 

Table 5-4: Neutron Sources used at the Y-12 Plant 

Location Y-12 Building Neutron Source 

Assay Laboratorya 

Critical experiments Facilityb 

9203 (Room 8), 9205 

9213 

Radium-Beryllium, Polonium-Beryllium 

Polonium-Beryllium, Plutonium-Beryllium 

Fission Neutrons 

Electromagnetic Researchc 9201-2, 9204-3 Polonium-Beryllium 

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86-Inch Cyclotron 

Health Physicsd 

Instrument Departmente 

Chemical Operationsf 

9983 (Calibration Laboratory) 

9737

9202, 9206, 9212 

Polonium-Beryllium, Americium-Beryllium 

 Polonium-Beryllium 

Highly Enriched Uranium Fluoride and Oxide 

Compounds 

Sources: 

a

Struxness, 1949; Stuxness, November-December 1950 

b

Stuxness, November-December 1950; Struxness, January-June 1953; ORNL/TM-349, ORNL/TM-349 Rev. 1
 c

Struxness, January-June 1951; Struxness, November-December 1950; ORNL 1173; ORNL 1196, ORNL 1392, 

Struxness, July-December 1951; Struxness, January-July 1952; Livingston (1958) d

Struxness, January-June 1951; Struxness, January-July 1952; Y-12 Plant, 1963
 e

Struxness, January-June 1951 

f

ORAUT-TKBS-0014-2 Rev. 00, DOE (2000)
 

Neutron sources were used in basic research (Buildings 9201-2 and 9204-3), critical assembly and 

reactor research (Building 9213), calibration of radiation dosimeters and radiation detection 

instruments (Buildings 9737 and 9983), and material assay (Buildings 9203 and 9205). Shielding was 

used to protect workers from unnecessary exposures to the radionuclide sources. Nevertheless, some 

dose was received even in shielded areas and some dose was also received from the bare sources. The 

largest exposure would occur while sources were withdrawn from their shields during the calibration 

of radiation instruments or during periodic tests for leakage of radioactive materials from the sealed 

containers about the sources. 

Two other neutron sources not listed in the table above are a Cockcroft-Walton linear accelerator 

capable of producing a maximum of 1 × 1010 fast neutrons per second (Struxness, January-June, 1953) 

and a 5-MeV Van de Graff accelerator capable of producing a fast neutron flux as high as 560 fast 

neutrons per cm2 second near the target (Struxness, January-June 1951; Struxness, July-December 

1951). The Cockcroft-Walton was installed in the Oak Ridge National Laboratory Biology Division 

(Building 9207) in early 1953, and the 5-MeV Van de Graff was installed in the East end of the 

building housing the Oak Ridge 86-inch cyclotron (Building 9201-2) in late 1951. The 5-MeV Van de 

Graff was operated at Y-12 during part of 1951 and part of 1952 while a permanent structure was 

being built for the accelerator at the ORNL Site (Johnson, 1994). 

5.3.4 X-ray and Electron Generating Equipment 

The X-ray or electron generating equipment used at Y-12 included linear electron beams, electron 

beam welders, scanning electron microscopes, X-ray photoelectron spectrometers, secondary ion mass 

spectrometers, enclosed beam diffraction equipment, and medical diagnostic X-ray equipment. The 

emitted energy range is from 15 KeV to 9 MeV. 

5.3.5 Recycled Uranium and Other Radionuclides of Concern 

From 1953 until 1999 recycled uranium activities introduced radionuclides intoY-12 plant systems 

unlike those typically associated with the Y-12 weapons processes. These contaminants were a result 

of fission and activation processes of a variety of uranium enrichment isotope mixtures which were 

irradiated in production and test reactors. As a result, the recycled uranium contained transuranic 

material, fission products and reactor-generated uranium products. After completing their useful life in 

the reactors, the unused uranium in the spent fuel elements or targets was recovered in chemical 

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extraction plants and returned to the inventories in the DOE system along with trace quantities of the 

contaminants. 

The primary recycled uranium contaminants of concern at Y-12 began in 1953 with shipments of very 

highly enriched uranium from the Idaho Chemical Processing Plant with the Savannah River Plant 

sending large quantities of highly enriched uranium/very highly enriched uranium recycled uranium 

materials a few years later. The primary contaminants were plutoinium-238 (plutonium-239 in lesser 

quantities), neptunium-237, and technetium-99. All of the highly enriched uranium/very highly 

enriched uranium was processed through chemical extraction, which had been designed to remove 

other contaminants such as trace metals. However, some removal of recycled uranium radioisotopic 

contaminants occurred (in parts per billion quantities) and was generally disposed of with the 

raffinates. 

Shortly after recycled uranium was introduced at Y-12, AEC directed that an effort be made to 

remove neptunium-237 from process streams for use as targets in the production of plutoinium-238 in 

the production reactors. X-10 designed the ion exchange system for liquid processes, which contained 

neptumiun-237 and Y-12 installed this system on the liquid feed to the chemical processing plant. 

The spent columns were removed and sent off-site for further processing. No significant handling of 

these sources of neptunium occurred at Y-12. 

6.0 Summary of Available Monitoring Data for the Proposed Class 

The following descriptions of available monitoring data contain information on the subject class under 

evaluation and on the Y-12 Plant worker population and monitoring programs as a whole. The more 

general information and data are included because the feasibility of performing dose reconstruction 

for the proposed class relies in part on the utilization of data from workers in higher exposure 

potential jobs to calculate maximum plausible exposures for the proposed class members. 

The majority of the data evaluated are results obtained from employee monitoring during the proposed 

class time period (1948 through 1957). However, monitoring results from years immediately 

following the proposed class timeframe were also reviewed as the plant activities were generally 

similar (see Section 5). As such, the availability of data through 1960 is discussed. 

Historically, the main purpose of the radiation monitoring programs at the Y-12 Plant have been to 

assure that worker exposures to radiation be kept below the annual prescribed occupational exposure 

limit in effect at that time. This is evidenced by text found in essentially all of the acquired Health 

Physics Progress reports, many memos and reports (available in the NIOSH Site Research Database), 

and as explained by several workers that were interviewed. Personal radiation dosimetry data in the 

early years (prior to 1961) was seldom collected for workers who were considered to have low 

potential for exposure. Monitored workers were usually those believed by health physics staff to have 

potential for external radiation exposures greater than 10% of the radiation protection guidelines in 

effect during that period of time. Determination of monitoring needs was based on the results of health 

physics assessments which included air sampling (area and breathing zone), surface swipes, and 

radiation surveys. As early as 1947, results of the health physics department’s activities were 

documented in progress reports; these progress reports are available to NIOSH. External penetrating 

and shallow exposures to particulate and photon radiation were monitored using radiation sensitive 

materials housed in personnel badges worn by workers. Detailed historical evaluations of the Y-12 

gamma, neutron, and beta monitoring programs including applicable radiation protection guidelines 

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can be found in parts one and two of reports titled Historical Evaluation of the Film Badge Dosimetry 

Program at the Y-12 Facility in Oak Ridge, Tennessee (ORAU Technical Report 2004-0888; ORAU 

Technical Report 2004-1406). Internal exposures to radionuclides were monitored by counting 

radioactive emissions in workers’ excreta (urine) and via air sampling. Routine in vivo chest counting 

at Y-12 was not initiated until 1961. However, limited data is available for the thorium related 

activities associated with two test batches processed through Building 9204-3 calutrons (for 

enrichment), Research and Development activities in Buildings 9202, 9204-1, and 9204-3, and when 

used as a co-precipitation media that preceded the 17-year period where metric tons of thorium were 

processed which started in 1960. 

6.1 Y-12 Internal Monitoring Data 

The earliest urine sample results available are from 1950 when samples were collected monthly. 

Weekly collection began in 1951. As was the case for external monitoring, collection of routine urine 

samples was based on exposure potential. However, available Y-12 records show that the number of 

employees receiving internal monitoring was generally greater than the number of employees who 

received external monitoring (see following CER Data summary in Section 6.4). Fluorometric 

analyses were performed on samples submitted from workers in natural and depleted uranium work 

areas and electrodeposition of uranium followed by gross alpha counting for samples submitted by 

workers in enriched uranium areas. 

In addition to the uranium urinalyses, non-uranium/special urinalyses were performed. These data are 

maintained in a separate Y-12 database known as Delta View (see Section 4.8). Delta View is 

comprised of approximately 470,000 scanned images of hard copy reports and monitoring data print 

outs associated primarily with Y-12 personnel. Information on these images is varied and can include 

general information in addition to bioassay data. Examples include selected dose calculation reports, 

data from both Y-12 and X-10 analytical labs, and lab reports of bioassay urine and fecal analysis 

results. 

The following table, Table 6-1, is a summary compilation of non-uranium bioassay results extracted 

from approximately 6,000 images stored in the Delta View Database. These 6,000 images were 

extracted from the system using pre-defined keywords located in comments fields that were thought to 

represent Y-12 bioassay data on non-uranium isotopes for the period of interest. 

Table 6-1: Non-Uranium Bioassay Results from Delta View 

Isotope 1952 1953 1954 1955 1956 1957 1958 1959 1960 

Alpha emitters in urine 2 0 0 0 0 0 0 0 0 

Hydrogen-3 0 0 0 0 605 0 0 0 0 

Polonium 0 18 0 0 0 0 0 0 0 

Plutonium 275 100 277 52 36 0 45 30 71 

Thorium 0 0 0 0 0 0 44 37 12 

As indicated in Table 6-1, some fecal analysis data, starting in 1958, is available for the thorium 

related activities associated with Research and Development performed in Building 9202, 9204-1, and 

9204-3. A total of 103 thorium fecal sample results were identified in the Delta View database for the 

1958 through 1962 time period. Additional details regarding the various analyses used and the 

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associated minimum detectable activities are presented in the Y-12 Occupational Internal Dose 

Technical Basis Document ORAUT-TKBS-0014-5, Rev. 01-A. 

Whole-body counting was not routinely practiced a Y-12. The primary in vivo detection method was 

chest counting. The Y-12 in vivo chest-counting facility was developed in the late 1950s but was not 

put into routine use until 1961. Chest counting was done for uranium and thorium isotopes, 

neptunium, and other radionuclides. 

No in vitro or in vivo bioassay data specific to thorium monitoring related to the period evaluated in 

this report, was identified in any of the documentation reviewed by NIOSH for this evaluation. 

6.2 Y-12 External Monitoring Data 

Prior to 1950, external monitoring was performed on a small scale to monitor the external exposures 

of individuals working in the Assay Laboratories, Radiographic Shop, Spectrographic Shop, and 

Machine Shops where uranium metals were being handled (Murray, January 1948; Murray, February 

1948; Struxness, May 1948; Struxness, December 1948). External monitoring was accomplished by 

wearing pocket ionization chambers (PICs), also called pocket meters or pocket chambers typically 

changed on a weekly basis. A limited set of external monitoring data exists for 1948 and 1949 (West, 

1980). ). NIOSH has also obtained an electronic file with 11,492 records covering the period 

evaluated in this report. Data elements in the electronic file include film badge ID, date of weekly 

readings, PIC readings, three photographic film dosimeter readings, and descriptive comments. 

NIOSH is attempting to link the film badge ID in the Y-12 pre-1950 external monitoring file with Y12 worker names in the ORAU DOE facility database, but has not yet verified the accuracy of this 

linkage. The data are, however, currently useful in a variety of ways for dose reconstruction. Details 

regarding this monitoring period and associated data set have been documented in External Radiation 

Monitoring at the Y-12 Facility During the 1948-1949 Period (ORAUT-OTIB-0047 Rev.00-A). 

An expanded personnel monitoring program for external radiation exposure was initiated at Y-12 in 

1950 (McLendon, 1960). All Y-12 personnel working with (1) depleted uranium, (2) discrete gamma, 

beta, or neutron sources, (3) X-rays, and (4) materials contaminated with fission products were 

required to wear a film badge dosimeter. The film badges were also augmented with film rings to 

assess the radiation exposure to the hands of uranium metal workers. Dosimetry practice was to record 

weekly dose to skin from beta particles (and low energy X-rays) or the penetrating doses from gamma 

rays as zero if they were less than 30 mrem (West, 1993). Film badges containing a nuclear track 

emulsions type-A film (so-called NTA film) were used to monitor neutron exposures. These NTA 

equipped badges were assigned only to those workers who had a substantial potential for neutron 

exposure and were exchanged on a biweekly schedule (Kerr, 2005). The minimum detection limit 

(MDL) of the neutron film is uncertain, but it is believed to be about 50 mrem for all years of usage at 

Y-12 (ORAUT-TKBS-0014-6 Rev. 00). 

Dosimetry policy from 1952 through mid-1956 was to assign the MDL dose for weeks with 

monitoring results less than the MDL for either beta or gamma radiation. The MDL was 50 mrem for 

1952 (weeks 1-38 approximately), all of 1953, and 1954 (weeks 1-30, approximately). In 1952 the 

MDL was 43 mrem for weeks 39-52. For the remainder of 1954 and all of 1955 and 1956, the MDL 

was 30 mrem. In practice, however, weekly doses less than the MDL were often left blank. 

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The Oak Ridge Associated Universities Center for Epidemiologic Research received a copy of the Y12 monitoring records from Y-12. These files contained records for more than 17,000 Y-12 workers. 

From the Y-12 records, available external data relevant to the subject class are presented by year in 

Section 6.4. 

6.3 Y-12 Air Sampling Data 

In addition to personal monitoring for internal and external doses, thousands of air samples were 

collected during the 1948 through 1957 time period. Most air samples were obtained from general air 

samplers placed in areas where some possibility of airborne contamination existed. Breathing zone 

samples were also collected. Samples were predominantly analyzed for uranium and, to a lesser 

extent, thorium. The results were generally reported as disintegrations per minute (dpm)/m3 uranium 

in air. Thorium air sampling for the 1948 through 1957 time frame was limited. To date, NIOSH has 

obtained a limited number of these thorium air sampling results. No thorium production level work 

occurred in the period evaluated in this report. Full production did not get underway until 1960 with 

the highest thorium production activity occurring between the years 1962 through 1965 and 1970 

through 1975. Over 80,000 thorium air sampling records are available covering the production years 

extending from 1960 through 1976. 

6.4 Summary of CER Data 

The following table, Table 6-2, summarizes the general types and numbers of monitoring data records 

electronically available to NIOSH to support dose reconstructions relevant to the proposed class. 

Originally obtained from Y-12, the data summarized within the table are from databases maintained 

by the ORAU Center for Epidemiologic Research. 

Table 6-2: Summary of Available Monitoring Data for Y-12 Workers (1948-1960) 

Urinalysis (uranium) Air Monitoring External Monitoringa 

Year Total Number 

of Employees 

# of 

Records 

# of 

Employees 

Monitored 

# of Uranium 

Records 

# of 

Records 

 # of 

Employees 

Monitored 

1948 2,511 - - - 3,599 162 

1949 2,248 - - - 7,893 49 

1950 2,552 1,110 166 - 268 148 

1951 4,036 4,124 367 15,655 406 184 

1952 4,169 13,317 393 - 1,157 498 

1953 4,866 14,222 490 8,010 793 387 

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Table 6-2: Summary of Available Monitoring Data for Y-12 Workers (1948-1960) 

Urinalysis (uranium) Air Monitoring External Monitoringa 

Year Total Number 

of Employees 

# of 

Records 

# of 

Employees 

Monitored 

# of Uranium 

Records 

# of 

Records 

 # of 

Employees 

Monitored 

1954 5,817 23,430 1,316 20,217 1,240 682 

1955 5,768 28,806 1,225 26,976 1,920 624 

1956 5,443 29,914 1,119 36,280 2,181 730 

1957 5,169 33,443 1,443 41,354 2,510 796 

1958 5,164 38,783 1,791 77,373 2,879 996 

1959 5,460 47,339 2,277 66,150 3,664 1,266 

1960 5,593 46,381 2,193 44,433 4,296 1,336 

Notes: 

- Indicates No Data Available a External monitoring records include all currently known available gamma, beta, and neutron data. 

6.5 Y-12 Health Physics Progress Reports 

In addition to the monitoring data listed in Table 6-2, other aspects of the Y-12 Health Physics 

Program are documented in Y-12 Health Physics Progress reports kept within Y-12 plant records. 

Reports from as early as the fall of 1947 have been retrieved. Written by Y-12 Health Physics staff, 

the reports’ contents reflect a health physics program focused on determining maximum exposure 

areas within the plant, and documenting compliance with applicable standards. The reports present 

general period activities and incidents with the potential personnel exposure potential, regular 

radiological and chemical sampling result summaries, and detail measurements made. Additionally 

they document sampling protocols, procedures followed, training given, and recommendations made 

to increase worker safety (e.g. increased ventilation, personal protective equipment use, or new 

shielding requirements). 

Data typically contained with the Y-12 Health Physics Progress reports include exposure rate and 

contamination level ranges (minimum, mean, and maximum results) including alpha hand counting 

data, dating as far back as 1947. However, the report contents vary somewhat between different 

reporting periods and by measurement types. Air contamination concentrations are most frequently 

presented as average uranium air concentrations in d/min/m3

. Sampling locations are detailed as are 

sample type (e.g. swipe, scan, breathing zone, general air, etc.) and specific jobs are assessed. Overall 

sampling frequencies reflect an effort to assess contamination levels in all plant area and are highest in 

the exposure locations associated with production. Contamination and exposure potentials associated 

with new and/or short duration research and developmental type activities are also documented. 

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Longer lasting, non-uranium production activities, such as the cyclotron work, were regularly 

addressed in the monitoring program and progress reports. 

Below is an example of the content from a Y-12 Health Physics Progress Report for the time period of 

January 1, 1952 through July 1, 1952. This table of contents is provided to demonstrate the scope of 

work performed and discussed within these reports. 

Topics Included in the Y-12 Health Physics Progress Report for January 1, 1952 through July 1, 1952 

INTRODUCTION 

New Facilities 

Visitors 

Orientation and Training 

S INDUSTRIAL HYGIENE 

Air Sampling 

Hood Design 

Stack Sampling 

Mercury Analysis in Urine 

Hexone Analysis 

PERSONNEL 

MONITORING 

Film Badges, Pocket 

Chambers, and Rings 

Urinalysis Processing 

and Results 

AREA MONITORING 

Air Sampling 

Surface Surveys 

Shipments and Intraplant 

Transfers 

Building Surveys 

ACCELERATORS 

86-Cyclotron 

Isotope Production Program 

Neutron Shielding 

Medical Examinations 

External Exposures 

Air-borne Contamination 

Target Handling Facilities 

Decontamination Facilities 

Alignment Dry Box 

Cyclotron Change House 

Air Ventilation 

Plastic Covers 

Other Accelerators 

ANALYTICAL 

REASEACH 

Fluorophotometric 

Analysis of Urine for 

Uranium 

SPECIAL STUDIES 

Internal Uranium 

Exposures 

Neutron Monitoring 

Aerosol Generator 

Particle Size Studies 

7.0 Feasibility of Dose Reconstruction for the Proposed Class 

The feasibility determination for the proposed class of employees covered by this evaluation report is 

governed by EEOICPA and 42 CFR § 83.13(c)(1). Under this Act and Rule, NIOSH must establish 

whether or not it has access to sufficient information to either, estimate the maximum radiation dose 

for every type of cancer for which radiation doses are reconstructed that could have been incurred 

under plausible circumstances by any member of the class, or to estimate the radiation doses to 

members of the class more precisely than a maximum dose estimate. If NIOSH has access to 

sufficient information for either case, then it would be determined that it was feasible to conduct dose 

reconstructions. 

In making determinations of feasibility, NIOSH begins by evaluating whether current or completed 

NIOSH dose reconstructions demonstrate the feasibility of estimating with sufficient accuracy the 

potential radiation exposures of the proposed class. If not, NIOSH systematically evaluates the 

sufficiency of different types of monitoring data, process and source or source term data, which 

together or individually might assure NIOSH can estimate either the maximum doses members of the 

class might have incurred, or more precise quantities that reflect the variability of exposures 

experienced by groups or individual members of the class. This approach is specified in the SEC 

Petition Evaluation Internal Procedures (OCAS-PR-004 Rev. 0) and implements the SEC Rule 

requirements and is available at www.cdc.gov/niosh/ocas. 

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Common to performing a majority of the internal and external dose reconstructions for this class is the 

utilization of coworker data for estimating exposures to radionulcides, other than thorium. The 

monitoring data used include data from members of the proposed class and data from workers outside 

the proposed class that were performing jobs entailing higher exposure potentials than members of the 

proposed class. This approach provides a means of estimating claimant-favorable radiation doses for 

class members that were unmonitored or had gaps in their monitoring records. 

Utilizing available personal and process monitoring data to calculate claimant favorable radiation 

doses for unmonitored employees is appropriate and possible only if the data are of sufficient quality. 

In addition to determining appropriate sampling, measurement, and analytical techniques, data quality 

sufficiency is dependant upon confidence that the selection of monitoring locations and personnel 

were appropriate and included the highest exposure locations and activities within the plant 

throughout the evaluated time frame. Similarly, it is important to determine that exposure potential 

associated with activities that were not production oriented, new, and/or short-lived (e.g., research and 

development) were also evaluated. 

Monitoring devices, sampling techniques, and analytical methods were well documented for 

exposures to radionuclides other than thorium in many collected historical documents reviewed by 

NIOSH for the period evaluated in this report. Additional information supporting sampling device and 

method adequacy is presented in the Y-12 Site Profile (ORAUT-TKBS-0014-1 Rev. 00) and in 

Historical Evaluation of the Film Badge Dosimetry Program at the Y-12 Facility in Oak Ridge, 

Tennessee: Part 1 and 2 (ORAU Technical Report 2004-0888; ORAU Technical Report 2004-1406). 

Also contained within these documents is information indicating that activities and personnel 

associated with the highest exposure potentials were regularly monitored. This evaluation has 

included additional data sources and analyses as part of the verification of the sufficiency of coworker 

data to calculate maximum exposure potentials. These include: 1) the retrieval and review of Health 

Physics Progress reports and additional monitoring related documents, 2) conducting focused 

interviews with plant workers employed during the subject time frame, and 3) a statistical analysis of 

available personal monitoring data. 

The evaluation that follows examines separately the availability of information necessary for 

reconstructing internal and external radiation doses of members of the proposed class, as well as data 

sufficiency and reliability, and the petition basis and other issues relevant to the evaluation of this 

petition. A summary of the feasibility findings, based on the examinations performed in the process of 

evaluating this petition, is also included. 

7.1 Analysis of Data Sufficiency and Reliability 

Performing internal and external dose reconstructions requires worker monitoring data. Worker 

monitoring data includes data from members of the proposed class as well as data from workers 

outside the proposed class who were performing jobs with higher exposure potentials. Using worker 

monitoring data provides a means of calculating claimant-favorable and maximum potential radiation 

doses for class members who were unmonitored or have gaps in their monitoring records. 

Utilizing available personal and process monitoring data to calculate claimant favorable radiation 

doses for unmonitored employees is appropriate and possible only if the data are of sufficient quality. 

In addition to determining appropriate sampling, measurement, and analytical techniques, data quality 

29 of 46 
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sufficiency is dependant upon confidence that the selection of monitoring locations and personnel 

were appropriate and included the highest exposure locations and activities within the plant 

throughout the evaluated timeframe. Similarly, it is important to determine that exposure potential 

associated with activities that were not production oriented, new, and/or short-lived (e.g., research and 

development) were also evaluated. 

In addition to the sampling, analytical, and record keeping information, NIOSH also evaluated other 

documentation related to Y-12. Historical Y-12 documents include detailed information about 

monitoring devices, sampling techniques, and analytical methods. In addition to historical document 

resources, further information supporting the adequacy of monitoring devices, sampling techniques, 

and analytical methods is presented in the Y-12 Site Profile (ORAUT-TKBS-0014-2 Rev. 00; 

ORAUT-TKBS-0014-6; ORAUT-TKBS-0014-6, Rev.00; ORAUT-TKBS-0014-1, Rev. 00; ORAUTTKBS-0014-3, Rev.00; ORAUT-TKBS-0014-5, Rev. 01-A) and in Historical Evaluation of the Film 

Badge Dosimetry Program at the Y-12 Facility in Oak Ridge, Tennessee: Part 1 and 2 (ORAU 

Technical Report 2004-0888; ORAU Technical Report 2004-1406). Also contained within the Y-12 

Site Profile and in Historical Evaluation of the Film Badge Dosimetry Program at the Y-12 Facility 

in Oak Ridge, Tennessee: Part 1 and 2 is information supporting the proposition that activities and 

personnel associated with the highest exposure potentials were regularly monitored. 

Documentation supports NIOSH findings that activities and personnel associated with the highest 

exposure potential were regularly monitored. However, given the importance of verifying coworker 

data sufficiency, additional activities focused on historical monitoring selection and data credibility 

have been included in this evaluation and are presented in Appendix 1. The additional activities 

included: 

•	 Statistical analysis of available personal monitoring data 

•	 Examination of the monitoring data set to determine data consistency 

•	 Interviews with plant workers employed during the subject time frame 

•	 Retrieval and review of Health Physics Progress reports and additional monitoring related 

documents 

7.2 Internal Radiation Doses at Y-12 

The principal source of internal radiation doses for members of the proposed class was airborne 

uranium particulate material. This dust could be inhaled by individuals and then be deposited in the 

respiratory tract. The dust would also settle onto surfaces and be available for re-suspension back into 

the air where it could be inhaled or ingested in the body by transfer from contaminated surfaces via 

hand to mouth. Exposures over the history of operations were considered to be chronic in nature. 

Although there are no bioassay results from before 1950, the first intake period was assumed to begin 

on January 1, 1947. Primary operations from 1947 through 1951 consisted of salvage, recovery, and 

recycle operations (from previous uranium enrichment work), with uranium preparation and 

machining beginning in 1949. The information in the Y-12 documentation reviewed by NIOSH for 

this evaluation, supports the assumption that exposure conditions beginning in 1947 were similar to 

those in the early 1950s. 

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In addition to uranium, which is the primary radionuclide contributing to internal dose at Y-12, 

exposure to various other radionuclides would have occurred from uranium salvage work and from 

two other Oak Ridge National Laboratory programs; one of which involved a proton-accelerating 

cyclotron and the second program which used the same cyclotron to create neutron-deficient 

radionuclides. The other radionuclides of concern included fission/activation products, thorium, and 

transuranics. 

The subsections below summarize the extent and limitations of information available for 

reconstructing the internal doses of members of the class. Most of the information summarized below 

is provided in greater detail in the individual TBDs and other document sources as described in 

Section 4.0. Methods for utilizing coworker data to perform internal dose reconstruction for this class 

of workers are detailed in the Technical Information Bulletin Internal Dosimetry Coworker Data for 

Y-12 (ORAU-OTIB-0029). 

7.2.1 Process-related Internal Doses at Y-12 

The following subsections summarize the extent and limitations of information available for 

reconstructing the process-related internal doses of members of the proposed class. 

7.2.1.1 Urinalysis Information and Available Data 

Y-12 began in vitro urinalysis using flourometry in1948. The primary purpose of this initial program, 

in conjunction with medical examinations, was to monitor for nephrotoxicity from uranium. However, 

beginning in 1950, workers in uranium production areas were placed on the urinalysis program for 

estimating internal dose. The program expanded to include certain maintenance workers in 1954. A 

monthly monitoring frequency was initially established with some employees monitored on a weekly 

basis. Beginning in 1957, specific workers with the potential for exposure to plutonium or tritium 

were monitored for intakes by urinalysis accordingly. Also, records were identified where urinalysis 

for polonium was performed as a result of an unusual exposure that occurred from a ruptured 

polonium-beryllium source. No thorium in vitro bioassay results were identified during NIOSH’s 

reviews, for the time period evaluated in this report. 

NIOSH has access to thousands of urinalysis results representing approximately 7% to 40% of the Y12 worker population at different times during the period covered by this report. Approximately 12 

percent of members of the proposed class received urinalysis monitoring during the 1950 through 

1957 timeframe. This lower monitoring frequency reflects the program focus on the highest exposure 

potential activities and the personnel performing those activities. The urinalysis program was 

implemented primarily for employees working in uranium production and recovery areas, and the 

program was further differentiated for most of the period on the basis of the type uranium managed in 

each area, i.e. natural, depleted, or enriched. Records indicate that non-routine urinalyses were also 

performed for plutonium and tritium in work areas where these exposures occurred. Specific methods 

for dose reconstruction using bioassay data have been developed and include provisions for missed 

doses, including the period from 1948 to 1950 when no urinalysis records are available. Conservative 

intake values for radionuclides associated with the recycled uranium work are also accounted for; the 

associated methods are provided in Y-12 Occupational Internal Dose TBD (ORAUT-OTIB-0047 Rev. 

00-A) and the Technical Information Bulletin Internal Dosimetry Coworker Data for Y-12 (ORAUOTIB-0029). 

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Because the uranium isotopes present at Y-12 have very long half-lives and the material is retained in 

the body for long periods, excretion results are not independent. For example, an intake in the early 

1950s could contribute to urinary excretion in the 1980s and later. To avoid potential underestimation 

of intakes for people who worked at Y-12 for relatively short periods, each intake was fit 

independently, using only the bioassay results from the single intake period. This will likely result in 

an overestimate of intakes, particularly for assumed Type-S exposures, extending through multiple 

assumed intake periods (ORAUT-OTIB-0047 Rev. 00-A; ORAU-OTIB-0029) 

Uranium compounds—in enriched, depleted, and natural isotopic abundances— exhibiting all 

solubility classes would have been present in various operations at the Y-12 Plant during the site’s 

history (ORAUT-TKBS-0014-1, Rev. 00). Chemically soluble forms in solution, moderately soluble 

compounds, and relatively insoluble compounds could have been encountered by site workers. 

Section 5.1.1 of the ORAU Technical Report 2004-0888 notes, “while the exceptional cases with 

unusually protracted lung clearance are important, it is more important to note that, for the vast 

majority of individuals, lung clearance took place in approximate accordance with the ICRP 

Publication 2 “Insoluble” model, which fits within the current “Type-M framework.” Because there 

have been cases of very insoluble material noted on the site, both types M and S were evaluated. 

7.2.1.2 Analysis of Coworker Bioassay Data 

Analysis of Coworker Bioassay Data for Internal Dose Assignment describes the general process used 

for analyzing bioassay data for assigning doses to individuals based on coworker results (ORAUTOTIB-0019). Bioassay results were obtained from the Oak Ridge Institute for Science and Education 

(ORISE) Center for Epidemiologic Research Dosimetry Database, which contains uranium urinalysis 

records from the Y-12 site for 1950 to 1988. 

As described in Analysis of Coworker Bioassay Data for Internal Dose Assignment, uranium urine 

results were fit using a Type-M material (ORAUT-OTIB-0019). Results of the individual fits are not 

shown here but they fit reasonably well. Table 7-1 summarizes the intake periods and corresponding 

intake rates for the 50th and 84th percentiles. At the time of this evaluation, internal exposure coworker data sets, specific to radionuclides other than uranium, have not been established for Y-12. 

However, methods to relate those exposures to the uranium exposure do exist in some cases. 

Table 7-1: Type-M Uranium Intake Periods and Rates 

Start Date Stop Date 

Uranium Intake Rate (dpm/day) 

50 GSD th percentile 84th percentile 

01-01-1947 02-28-1978 169.34 598.93 3.54 

01-01-1947 04-30-1952 354.59 1,154.9 3.26 

08-01-1953 11-30-1953 547.22 1,963.1 3.59 

01-01-1956 02-28-1959 226.90 825.31 3.64 

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Table 7-1: Type-M Uranium Intake Periods and Rates 

Start Date Stop Date 

Uranium Intake Rate (dpm/day) 

50 GSD th percentile 84th percentile 

06-01-1961 12/31/1962 248.68 866.81 3.49 

10-01-1968 12/31/1972 160.67 601.60 3.74 

03-01-1978 09-30-1984 80.03 355.93 4.45 

10-01-1984 12-31-1988 44.203 223.85 5.06 

The intake periods used in the Type-M fits were also applied to the Type-S material fits. Table 7-2 

summarizes the intake rates for the 50th and 84th percentiles. The geometric standard deviations 

(GSDs) were determined by dividing the 84th percentile intake rates by the 50th percentile intake rates. 

Table 7-2: Type-S Uranium Intake Periods and Rates 

Start Date Stop Date 

Uranium Intake Rate (dpm/day) 

50 GSD th percentile 84th percentile 

01-01-1947 02-28-1978 1,844.4 6,544.2 3.55 

01-01-1947 04-30-1952 5,210.4 16,970 3.26 

08-01-1953 11-30-1953 17,983 64,559 3.59 

01-01-1956 02-28-1959 5,694.6 20,560 3.61 

06-01-1961 12-31-1962 6,849.4 23,632 3.45 

10-01-1968 12-31-1972 3,290.3 12,415 3.77 

03-01-1978 09-30-1984 1,280.3 5,802.9 4.53 

10-01-1984 12-31-1988 884.85 4,340.6 4.91 

Several intake periods overlapped, so they were combined to make 12 distinct intake periods, with a 

single intake rate and associated geometric standard deviations (GSD) for each. For 1947 through 

February 1978, all GSDs were within 10% of each other, so the largest GSD for the period was 

assigned to all intake rates for simplicity. Table 7-3 summarizes the 12 intake periods. Note that these 

are equivalent to the eight intake periods specified in Table 7-2, but provide a chronological layout of 

the changing intake rates over time. 

Table 7-3: Combined Uranium Intake Periods and Rates 

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Start Date Stop Date Type-M Intake Rate 

(dpm/day) 

Type-S Intake Rate (dpm/day) 

50th 

Percentile 

84th 

Percentile 

GSD 50th 

Percentile 

84th 

Percentile 

GSD 

01-01-1947 04-30-1952 523.93 1,753.83 3.74 7,054.4 23,514.2 3.77 

05-01-1952 07-31-1953 169.34 598.93 3.74 1,844.4 6,544.2 3.77 

08-01-1953 11-30-1953 716.56 2,562.03 3.74 19,827 71,103.2 3.77 

12-01-1953 10-31-1956 169.34 598.93 3.74 1,844.4 6,544.2 3.77 

11-01-1956 02-28-1959 396.24 1,424.23 3.74 7,539 27,104.2 3.77 

03-01-1959 05-31-1961 169.34 598.93 3.74 1,844.4 6,544.2 3.77 

06-01-1961 12-31-1962 418.02 1,465.73 3.74 8,693.4 30,176.2 3.77 

01-01-1963 09-30-1968 169.34 598.93 3.74 1,844.4 6,544.2 3.77 

10-01-1968 12-31-1972 330.01 1,200.53 3.74 5,134.4 18,959.2 3.77 

01-01-1973 02-28-1978 169.34 598.93 3.74 1,844.4 6,544.2 3.77 

03-01-1978 09-30-1984 80.03 355.93 4.45 1,280.3 5,802.9 4.53 

10-01-1984 12-31-1988 44.20 223.85 5.06 884.85 4,340.6 4.91 

7.2.1.3 Other Types of Bioassay/Workplace Indicators 

Other in vitro or in vivo techniques for evaluating occupational uptakes were not implemented at Y-12 

until after the period covered by this report. These other techniques were fecal sampling begun in the 

1960 to investigate uranium clearance and chest counting by gamma spectroscopy. This was 

accomplished by using NaI (sodium iodine) scintillation detectors put into routine use in 1961 

(ORAU-OTIB-0029). Although these procedures began after the time period covered by this report, 

the data combined with clearance models can be used to supplement determination of internal uptakes 

and resultant internal doses for the class covered in this evaluation. 

7.2.1.4 Airborne Levels 

A review was made of the available site information that described process activities conducted during 

the time period of the proposed class. An air monitoring program was in place during this time period 

that emphasized sample collection in those process areas with higher potential for airborne 

contamination. In addition to general area airborne concentration levels, there are data available from 

job-specific breathing zone air sampling events. Using the thousands of air sample results available 

for the period covered by the proposed class, NIOSH can establish a maximum exposure scenario 

based on an assumed isotopic uranium (enriched uranium, natural uranium, and depleted uranium) 

source term, process data, and the available air sampling and bioassay results. However, sufficient air 

monitoring data does not exist to establish a maximum thorium exposure scenario. 

7.2.1.5 Other Radionuclides 

Uranium has always been the dominant contributor to collective internal dose at Y-12. Monitoring for 

other radionuclides has been performed on a limited basis. Both the relatively small concentrations 

and the difficulty of analyses have contributed to the lack of data. One of the primary sources of 

significant contaminants (including the production of other than the normal uranium isotopes) that 

were introduced into the Y-12 plant systems were those associated with recycled uranium from 1953 

until 1999. These contaminants were a result of fission and activation processes of a variety of 

uranium enrichment isotope mixtures, which were irradiated in production and test reactors. 

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SEC-00028 Y-12 Plant 

The predominant recycled uranium and associated contaminants (plutonium, neptunium, technetium, 

and thorium) were in highly enriched uranium and very highly enriched uranium materials. However, 

all of the uranium at Y-12 came from other DOE facilities, which had also either generated and/or 

received recycled uranium materials. Therefore, nearly all of the uranium in the DOE facilities 

contained recycled uranium contaminants to varying degrees through being processed in the same 

equipment, blending with other materials to adjust the degree of enrichment, etc. For example, most of 

the depleted uranium received and processed at Y-12 was seldom chemically processed but was 

received in forms from which parts were produced by mechanical processing. However, even these 

materials were received from other plants, such as Fernald, which also had a recycled uranium 

contaminant inventory. Therefore, the depleted uranium contaminant levels at Y-12 were inferred 

from both the Fernald and the Idaho Specific Manufacturing Capability projects’ recycle reports 

(ORAU Technical Report 2004-0888; DOE 2000). 

The fundamental conclusion from a variety of reports is that for dose reconstruction purposes, a 

default level of recycled uranium contaminants can be derived and applied as a percentage increase to 

the derived uranium intake for each of the four major contaminants. Analytical information derived 

from a variety of sources allows the calculation or interpolation of the levels of the predominant 

recycled uranium contaminants in the uranium materials received, processed, and handled at Y-12. 

Details regarding these calculations are presented within the Technical Basis Document for the Y-12 

National Security Complex – Occupational Internal Dose (ORAUT-TKBS-0014-5). 

In addition to recycled uranium, vigorous programs were initiated and conducted at Y-12 during the 

time period evaluated in this report providing transition of operations from the electromagnetic 

enrichment of uranium to the separation/processing/enrichment of an extensive list of other stable and 

radioactive isotopes (See Appendix 2). The 72 beta calutrons (preserved for the purpose 

stable/radioactive separation and processing) and cyclotrons were used in the creation of a wide range 

of isotopes for research, biomedical, and weapons needs. These varied programs transitioned to X-10 

management and control in 1951 and are described in both Production reports and Health Physics 

Progress reports for all time periods. These reports provided information regarding operations of these 

facilities and the associated equipment including general information about, surface, and effluent 

monitoring results, as well as health and safety measures and related incidents (i.e.: target ruptures and 

other off-normal conditions) associated with the operations. All associated incidents or events that 

had the potential to, or did result in Y-12 personnel exposures were investigated by the Y-12 HP staff 

and documented in the these Production and Health Physics reports and (in the case where further of 

exposure evaluations were performed) in incident reports that are included in the applicable personnel 

files. The correlation, between incidents in the Production/HP reports and the existence of incident 

reports in individual files, was confirmed by NIOSH in the review of two cases where two individual 

claimants were involved in incidents that resulted in exposure assessments (involved in a 1958 and 

1961 (associated with cyclotron) incidents, respectively). 

NIOSH has access to the applicable Production/HP reports in the Site Research Database and through 

access to the Y-12 and Delta View Databases, which includes directly related X-10 monitoring data 

for X-10 operations performed at Y-12 (individual monitoring data for scientists and individuals 

directly involved in cyclotron work at Y-12). The complete set of Production/HP and incident reports 

are also maintained by the Y-12 Site records management group. This data will be used to 

supplement and support the information that exists in a claimant’s dosimetry records (including any 

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SEC-00028 Y-12 Plant 

incident reports) provided by the DOE. The internal dose reconstruction methods and requirements 

that are incorporated in the current EEOICPA dose reconstruction program will be applied and 

evaluated to determine the internal dose. In the case of an individual exposure or potential exposure is 

from a non-typical radioactive isotope (not calculable using the dose reconstruction tools available to 

NIOSH) the dose will be evaluated through the manual/hand application of the program requirements 

for dose reconstruction. 

NIOSH also has access to individual plutonium bioassay data, for the limited number of workers who 

had the potential for plutonium exposures and were therefore monitored accordingly, from the Delta 

View database for the 1951-1952 period. This data is also provided with the DOE individual 

dosimetry data when that data is requested from the DOE by NIOSH as part of the EEOICPA 

radiological dose reconstruction program. These data and sample information will be used to bound 

plutonium intakes during the years where the exposure potential existed. 

7.2.2 Ambient Environmental Internal Radiation Doses at Y-12 

Further evaluation regarding the ambient environmental internal radiation doses is not necessary 

because these doses are accounted for in the process related internal dose evaluation. 

7.3 External Radiation Doses at Y-12 

Potential external radiation exposures at Y-12 during 1948 to 1960 time period would have occurred 

as a result of uranium operations that included analysis, recovery and recycling, purification and 

conversion, forming, machining, and component assembly. Occupational external exposures could 

have included beta, gamma, and neutron radiations as well as X-ray exposures from required periodic 

medical examinations. 

The most prevalent potential source of external exposure to the majority of workers would have 

resulted from the gamma emissions from uranium-235 in the enriched uranium process areas of the 

plant and the beta and gamma emissions from the uranium-238 progeny (protactinium-234, thorium234, and protactinium-234m) in the depleted uranium plant areas. The depleted uranium process areas 

have historically had the largest workplace exposures. Additional external gamma exposure sources 

include activated materials in 86-inch cyclotron vault and activation/fission contaminants found in the 

recycled, highly enriched uranium. 

Exposure to neutron radiation also was possible at Y-12. Neutron exposures would have occurred 

primarily from reactions with the alpha particles emitted from highly enriched uranium interacting 

with low-Z material (e.g., fluorides and oxides of uranium), stray neutron fields while the 86-inch 

cyclotron was operating, and also from other neutron sources that were present at the site. These 

sources included both neutron emitting instrument calibration sources (e.g. polonium-beryllium, 

plutonium-beryllium, and radium-beryllium), and neutrons emitted from fissile material testing that 

took place onsite. 

Occupational medical exposures to X-rays, when such screening X-rays are a condition of 

employment, are also included in EEOICPA dose reconstructions. During this time period, individuals 

at the Y-12 Site were required to have pre-employment, annual, and termination chest X-ray 

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examinations. The Y-12 Occupational Medical Dose TBD (ORAUT-PROC-0042) documents the 

method and feasibility of reconstructing these medical exposures. 

The subsections below summarize the extent and limitations of information available for 

reconstructing external doses of members of the worker classes addressed by this report. More 

detailed information is provided in the Y-12 Site Profile (ORAUT-TKBS-0014-1 Rev. 00) and in 

Historical Evaluation of the Film Badge Dosimetry Program at the Y-12 Facility in Oak Ridge, 

Tennessee, Part 1 – Gamma Radiation (ORAU Technical Report 2004-0888). 

7.3.1 Film Badge Monitoring at Y-12 

External exposure monitoring of a limited number of workers began at the Y-12 site in 1948. The 

initial method used pocket ionization chambers (PICs) that were changed out on a weekly basis as 

well as hand film pads for uranium metal workers. Some film badges were also used at the onset of 

the program and replaced use of the PICs by 1950. Extremity monitoring of metal workers 

transitioned in 1951 from the hand film pads to film rings. 

The film badge used was a two element badge designed with a portion of the badge having an “open 

window” to measure significant beta radiation and a separate portion covered by cadmium filter for 

evaluating gamma exposure. Badges were exchanged on a weekly basis from 1948 to 1958 and on a 

monthly basis for the final two years covered by this evaluation. The routine monitoring practice 

during the timeframe covered by this evaluation was to require dosimetry badges for those employees 

who might receive a dose in excess of 10% or the Radiation Protection Guidelines in effect at that 

time. Upwards of 25% of the total employees required dosimetry at any given time during the period. 

Furthermore, the dosimeters also held a nuclear track Type-A emulsion (NTA) film used to measure 

neutron doses. However because neutron areas were limited to only a few departments, the NTA film 

was read only for those cases where a worker entered a neutron area. 

7.3.1.1 Gamma/X-ray, Beta, and Non-Specific Beta-Gamma Exposures 

The majority of the external radiation dose at the Y-12 site resulted from a variety of uranium work 

activities. NIOSH has access to the results of the film badge monitoring program for reconstructing 

both deep and shallow external dose components from the monitored population. Because those 

individuals monitored were selected based on having the highest exposure potential—i.e. greater than 

10% of the Radiation Protection Guidelines —external doses for missed doses or co-located, 

unmonitored workers could be conservatively calculated. Deficiencies in the monitoring program, 

such as non-conservative placement of the film badge on the worker relative to the source location, 

energy dependence of the film badge, and recording of doses as zero when results were less than the 

minimum detectable level have been addressed and methods developed for correcting the reported or 

missed doses in a dose reconstruction procedure (ORAUT-PROC-0042 Rev. 1; Kerr, 2005). 

7.3.1.2 Neutron Exposures 

There were only a few areas at the Y-12 facility were workers were exposed to neutrons on a routine 

basis, and in these areas, personnel monitoring was provided by film badges containing a neutron 

sensitive film (Emlet, 1956). Neutron exposures to Y-12 workers occurred primarily in the stray 

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radiation fields about the 86-inch cyclotron (Building 9201-2), areas used for storage of highly 

enriched uranium compounds of UF4 and UO3 (Building 9212 Complex), and the Criticality 

Experiments Facility (Building 9213). The stray neutron fields from these sources have been well 

characterized for use in dose reconstruction for Y-12 workers (ORAU Technical Report 2004-1406). 

Most of the neutron sources at Y-12 were small and produced neutrons by alpha particle reactions in 

beryllium. These small polonium-beryllium, plutonium-beryllium, and Americium-beryllium sources 

were used mainly in basic research (Buildings 9201-2 and 9204-3), critical assembly research 

(Building 9213), calibration of radiation detection instruments and dosimeters (Buildings 9737 and 

9983). The small neutron sources were shielded when not in use and neutron exposures to these 

sources during usage were rigidly controlled. The neutron fields around these small shielded sources 

have also been well characterized for use in dose reconstruction (ORAU Technical Report 2004-1406; 

ORAUT-OTIB-0055). 

A historical report has been prepared on neutron film badge usage at the Y-12 Plant (ORAU Technical 

Report 2004-1406). This reports states that NTA films for neutron dosimetry were added to the film 

badges in 1949. No personal neutron exposures appear to have been made prior to this time 

(Souleyrette, 2003). Occupational neutron exposure potential to Y-12 workers was primarily confined 

to the years from 1952 through 1962. During this period, there were 375 positive quarterly neutron 

doses among 143 workers at the Y-12 facility (ORAU Technical Report 2004-1406). 

The use of the available NTA film monitoring data in dose reconstruction for Y-12 workers is 

discussed in the document titled Effect of Threshold Energy and Angular Response of NTA Film on 

Missed Neutron Dose at the Oak Ridge Y-12 Facility (ORAUT-OTIB-0055). This technical 

information bulletin discusses and provides correction factors for missed dose due to the energy 

detection threshold and angular response of the NTA film. These factors are also applied to missed 

neutron dose to a worker that resulted from the routine practice of recording a zero when the quarterly 

neutron dose to the worker was less than the minimum detectable limit (MDL) of 50 mrem for the 

NTA film (ORAU Technical Report 2004-1406). The assignment of missed dose to Y-12 workers is 

also discussed in Effect of Threshold Energy and Angular Response of NTA Film on Missed Neutron 

Dose at the Oak Ridge Y-12 Facility (ORAUT-OTIB-0055). 

7.3.2 Ambient Environmental External Radiation Doses at Y-12 

An evaluation of ambient environmental external radiation doses is not necessary because this dose is 

accounted for in the process related external dose evaluation. 

7.4 Evaluation of Petition Basis for SEC-00028 

The following subsections evaluate the assertions made on behalf of petition SEC-00028 for the Y-12 

Plant. 

7.4.1 Evaluation of General Concerns Raised in Petition SEC-00028 

The following addresses general concerns raised in the discussion of petition SEC-00028. 

7.4.1.1 Inadequate Monitoring 

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The petitioner asserted by affidavit that the energy employees listed on the petition did not receive or 

witness monitoring of radiation exposures or radiation doses for steamfitters, pipefitters, and 

plumbers. 

Documentation in NIOSH/ORAU databases for the applicable time period for this proposed class 

have been reviewed and evaluated and it was determined that the databases do not contain monitoring 

data for Steamfitters, Pipefitters, and Plumbers employed during the earliest years of the proposed 

class time frame (1944-1947). However, with the exception of thorium exposure, monitoring data 

applicable for the later years of the proposed class time frame are available (post-1947), as discussed 

in the Y-12 Site Profile and Co-Worker Data OTIB. 

7.4.1.2 Exposure Potential 

Steamfitters, Pipefitters, and Plumbers worked mostly in maintenance and new construction. New 

construction activities on or at new facilities (that have not gone through startup), by the nature of that 

work, does not entail a significant exposure potential. New construction work in operational facilities 

are addressed under the same conditions as those expected for facility maintenance work which were 

potentially conducted in many areas at the Y-12 site. Worker interviews indicate that because the 

maintenance group supported the entire site, the maintenance personnel had the potential to be 

exposed to all sources of exposure on site. Therefore, the maintenance personnel had the potential for 

exposure to: 

•	 Uranium isotopes during uranium enrichment and recycling operations (neptunium) 

•	 Thorium when two test batches were processed through the Building 9204-3 calutrons (for 

enrichment), during Research and Development activities in Buildings 9202, 9204-1, and 

9204-3, and when used as a co-precipitation media to increase the uranium recovery 

percentage from decontamination solutions. 

•	 Plutonium during the 1950s when plutonium was enriched with the calutrons 

•	 Polonium 208 when polonium was produced with the cyclotron 

•	 Other short lived radioactive isotopes produced by the cyclotron 

As a result of this evaluation, NIOSH has determined that it can estimate radiation doses with 

sufficient accuracy for the subject class and time frame to all identified potential exposures except 

those associated with thorium exposures while working in Building 9202, 9204-1, or 9204-3. 

7.5 Summary of Feasibility Findings for Petition SEC-00028 

This report evaluated the feasibility for completing dose reconstructions for employees at the Y-12 

Plant from January 1948 through December 1957. NIOSH found that the monitoring records, process 

descriptions and source term data available for determining thorium exposures are not sufficient to 

complete dose reconstructions for the proposed class of employees. 

Table 7-4 summarizes the results of the feasibility findings at the Y-12 Plant for each exposure source 

for the time period of 1948 through 1957. 

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SEC-00028 Y-12 Plant 

Table 7-4: Summary of Feasibility Findings for SEC-00028 

Source of Exposure Maximum Exposure can be 

Determined 

Maximum Exposure cannot be 

Determined 

Internal X 

- Uranium X 

- Thorium X 

- Other Radionuclides X 

External X 

 - Gamma X 

 - Beta X 

 - Neutron X 

 - Occupational Medical x-ray X 

8.0 Evaluation of Health Endangerment for Petition SEC-00028 

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

governed by EEOICPA and 42 CFR § 83.13(c)(3). Under these requirements, if it is not feasible to 

estimate with sufficient accuracy radiation doses for members of the class, NIOSH must also 

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

health of members of the class. The regulation requires 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 

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. 

Per EEOICPA and 42 CFR § 83.13(c)(3), a health endangerment determination is required because 

NIOSH has determined that it does not have sufficient information to estimate the thorium internal 

dose for the members of the proposed class. 

NIOSH did not identify any evidence from the petitioners or from other resources that would establish 

that any members of the proposed class were exposed to radiation during any 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 

thorium. Consequently, NIOSH has determined that health was endangered for those 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). 

9.0 NIOSH Proposed Class for Petition SEC-00028 

This evaluation defines a single class of employees for which NIOSH can estimate radiation doses 

with sufficient accuracy. This class includes employees of the DOE or DOE contractors or 

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SEC-00028 Y-12 Plant 

subcontractors who were monitored or should have been monitored for thorium exposures while 

working in Building 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. 

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10.0 References 

42 CFR 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 22296; May 2, 2002; SRDB Ref ID: Currently Not Assigned 

42 CFR 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 CFR 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: Currently Not Assigned 

42 USC. §§ 7384-7385, Energy Employees Occupational Illness Compensation Program Act of 2000 

[EEOICPA]; as amended; SRDB Ref ID: Currently Not Assigned 

OCAS-PR-004, Rev. 0, Internal Procedures for the Evaluation of Special Exposure Cohort Petitions, 

National Institute for Occupational Safety and Health, Cincinnati, Ohio, September 23, 2004; SRDB 

Ref ID: Currently Not Assigned 

ORAU Technical Report 2004-0888, Historical Evaluation of the Film Badge Dosimetry Program 

at the Y-12 Facility in Oak Ridge, Tennessee, Part 1 – Gamma Radiation; 2004; SRDB Ref ID: 

14995 

ORAU Technical Report 2004-1406, Historical Evaluation of the Film Badge Dosimetry Program 

at the Y-12 Facility in Oak Ridge, Tennessee, Part 2 – Neutron Radiation; 2004; SRDB Ref ID: 

16843 

ORAUT-OTIB-0019, Analysis of Coworker Bioassay Data for Internal Dose Assignment; October 7, 

2005; SRDB Ref ID: 19438 

ORAUT-OTIB-0029, Technical Information Bulletin 0029, Internal Dosimetry Coworker Data for 

Y-12; April 5, 2005; SRDB Ref ID: 19452 

ORAUT-OTIB-0047, Rev. 00, External Radiation Monitoring at the Y-12 Facility During the 1948-

1949 Period; September 20, 2005; SRDB Ref ID: 19462 

ORAUT-OTIB-0055, Effect of Threshold Energy and Angular Response of NTA Film on Missed 

Neutron Dose at the Oak Ridge Y-12 Facility; 2006; SRDB Ref ID: Currently Not Assigned 

ORAUT-PROC-0042, Accounting for Incomplete Personal Monitoring Data on Penetrating 

Gamma-Ray Doses to Workers in Radiation Areas at the Y-12 Plant Prior to 1961; August 9, 2004; 

SRDB Ref ID: 20212 

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SEC-00028 Y-12 Plant 

ORAUT-PROC-0042 Rev. 1, A Procedure to Account for Incomplete Personal Monitoring Data on 

Penetrating Gamma-Ray Doses to Workers in Radiation Areas at the Oak Ridge Y-12 Plant Prior to 

1961, Rev. 1; SRDB Ref ID: Currently Not Assigned 

ORAUT-TKBS-0014-2 Rev. 00, Technical Basis Document for the Y-12 National Security Complex 

-Site Description, Rev. 00; SRDB Ref ID: 20196 

ORAUT-TKBS-0014-6, Technical Basis Document for the Y-12 National Security Complex 

Occupational External Dosimetery; SRDB Ref ID: 20207 

ORAUT-TKBS-0014-6, Rev. 00, Technical Basis Document for the Y-12 National Security Complex 

– Occupational External Dosimetry, Rev.00; SRDB Ref ID: 20208 

ORAUT-TKBS-0014-1, Rev. 00, Technical Basis Document for the Y-12 National Security Complex 

– Y-12 Site Profile, Rev.00; SRDB Ref ID: 20193 

ORAUT-TKBS-0014-3, Rev. 00, Technical Basis Document for the Y-12 National Security Complex 

– Occupational Medical Dose, Rev. 00; SRDB Ref ID: 20200 

ORAUT-TKBS-0014-5, Rev. 01-A, Technical Basis Document for the Y-12 National Security 

Complex – Occupational Internal Dose, Rev. 01-A; SRDB Ref ID: 20206 

ORNL-1173, Progress Report - Part I, Electromagnetic Research Division; July 1, 1951 to 

September 31, 1951; SRDB Ref ID: 11943 

ORNL-1196, The Oak Ridge 86-Inch Cyclotron, Oak Ridge National Laboratory; SRDB Ref ID: 

11942 

ORNL-1392, Production of Polonium 208, Oak Ridge National Laboratory; August 1952; SRDB Ref 

ID: 11936 

ORNL/TM-349, A Safety Review of the Oak Ridge Critical Experiments Facility, Oak Ridge National 

Laboratory; 1962; SRDB Ref ID: 15646 

ORNL/TM-349 Rev. 1, A Safety Analysis of the Oak Ridge Critical Experiments Facility, Rev. 1, 

Oak Ridge National Laboratory; SRDB Ref ID: 15655 

Affidavit, 2004, Affidavit by Petitioner Regarding SEC Petition Number 00038, dated March 24, 

2004; SECIS Ref ID: 8544 

Butler, 1963, Isotopes Development Center Progress Report, Reactor and Clyclotron-Produced 

Isotopes, July to October 1962, Butler, T.A.; Oak Ridge National Laboratory: Oak Ridge, Tennessee; 

April 1, 1963; SRDB Ref ID: 11934 

DOE, 2000, Guide of Good Practices for Occupational Radiological Protection in Uranium 

Facilities, Washington, D.C.; 2000; SRDB Ref ID: 4617 

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SEC-00028 Y-12 Plant 

Emlet, 1956, Radiation Protection at UCNC Production Facilities, Union Carbide Nuclear Company; 

Letter dated August 29, 1956; SRDB Ref ID: Currently Not Assigned 

Howard, 1954, Electronuclear Research Division Semi-Annual Progress Report for Period Ending 

September 20, 1954, Howard, F.T.; Oak Ridge National Laboratory: Oak Ridge, Tennessee; SRDB 

Ref ID: 16637 

Johnson, 1994, Oak Ridge National Laboratory: The First Fifty Years, Johnson, L., and Schaffer, D.; 

The University of Tennessee Press: Knoxville, Tennessee; 1994; SRDB Ref ID: 11916 

Kerr, 2005, Miscellaneous Memos from and to TEC Personnel, Kerr, George; February, 2005; SRDB 

Ref ID: Currently Not Assigned 

Livingston, 1958, Electronuclear Research Division, Annual Progress Report for Period Ending 

October 1, 1957, Livingston, R.S.; Oak Ridge National Laboratory: Oak Ridge, Tennessee; April 15, 

1958; SRDB Ref ID: 11945 

Livingston, 1962, Electronuclear Division Annual Progress Report for Period Ending December 31, 

1961, Livingston, R.S. and Zucker, A.; Oak Ridge National Laboratory: Oak Ridge, Tennessee; 1962; 

SRDB Ref ID: 11949 

McLendon, 1960, Personnel Radiation Exposure Data Correspondence with G. W. Flack, 

McLendon, J. D.; August 25, 1960; SRDB Ref ID: 3694 

Murray, January 1948, Health Physics Progress Report, Murray, R.; Y-12 Plant: Oak Ridge, 

Tennessee; January 1-31, 1948; SRDB Ref ID: 8602 

Murray, February 1948, Health Physics Progress Report, Murray, R.; Y-12 Plant: Oak Ridge, 

Tennessee; February 1-29, 1948; SRDB Ref ID: 8602 

Rees, 1967, Health Physics: Principles of Radiation Protection, Rees, D. J.; The M.I.T. Press: 

Cambridge, Massachusetts; 1967; SRDB Ref ID: Currently Not Assigned 

Souleyrette, 2003, Summary of Historical Monitoring Techniques Provided to NIOSH for EEOICPA 

Data Requests, Souleyrette, M. L.; Y-12 National Security Complex: Oak Ridge, Tennessee; February 

18, 2003; SRDB Ref ID: Currently Not Assigned 

Stapleton, 1993, A Brief History of the Research Reactors Division of Oak Ridge National 

Laboratory, Stapleton, D.R.; Oak Ridge National Laboratory: Oak Ridge, Tennessee; 1993; SRDB 

Ref ID: 16542 

Struxness, May 1948, Health Physics Industrial Hygiene Progress Report, Struxness, E. G.; Y-12 

Plant: Oak Ridge, Tennessee; May 1-31, 1948; SRDB Ref ID: 8602 

Struxness, December 1948, Health Physics Industrial Hygiene Progress Report, Struxness, E. G.; Y12 Plant: Oak Ridge, Tennessee; December 1-31, 1948; SRDB Ref ID: 8602 

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SEC-00028 Y-12 Plant 

Struxness, 1949, Health Physics Hygiene Progress Report, Struxness, E. G.; Y-12 Plant: Oak Ridge, 

Tennessee; February 1-28, 1949; SRDB Ref ID: 8602 

Struxness, January-June 1951, Health Physics Progress Report, Struxness, E. G.; Y-12 Plant: Oak 

Ridge, Tennessee; January 1, 1951 to June 30, 1951; SRDB Ref ID: 8602 

Struxness, November-December 1950, Health Physics Progress Report, Struxness, E.G.; Y-12 

Plant: Oak Ridge, Tennessee; November 1, 1950 to December 31, 1950; SRDB Ref ID: 8602 

Struxness, July-December 1951, Health Physics Progress Report, Struxness, E. G.; Y-12 Plant: Oak 

Ridge, Tennessee; July 1, 1951 to December 31, 1951; SRDB Ref ID: 8602 

Struxness, January-July 1952, Health Physics Progress Report, Struxness, E. G.; Y-12 Plant: Oak 

Ridge, Tennessee; January 1, 1952 to July 1, 1952; SRDB Ref ID: 8602 

Struxness, January-June 1953, Health Physics Progress Report, Struxness, E. G.; Y-12 Plant: Oak 

Ridge, Tennessee; January 1, 1953 to June 30, 1953; SRDB Ref ID: 8602 

West, 1980, Names of Persons Having Dosimetry Information in the 1947-1950 Period in the Y-12 

Record Center, Internal Correspondence, Union Carbide-Nuclear Division; Oak Ridge Gaseous 

Diffusion Plant: Oak Ridge, Tennessee; October 16, 1980; SRDB Ref ID: Currently Not Assigned 

West, 1981, Discrepancy in 1954 Y-12 Film Badge Results, Union Carbide Nuclear 

Division Letter; Oak Ridge Gaseous Diffusion Plant: Oak Ridge, Tennessee; 1981; SRDB Ref ID: 

Currently Not Assigned 

West, 1991, Correction of Y-12 Film Badge Results in the 1950 Through 1955 Period, Memorandum 

to Distribution, West, C. M.; Oak Ridge Associated Universities: Oak Ridge, Tennessee; February 19, 

1991; SRDB Ref ID: Currently Not Assigned 

West, 1993, Brief History of the Y-12 External Monitoring Program, Memorandum, West, C. M.; 

Oak Ridge Institute for Science and Education: Oak Ridge, Tennessee; June 7, 1993; SRDB Ref ID: 

Currently Not Assigned 

Wilcox, 1999, An Overview of the History of Y-12, Wilcox, W., et al; Oak Ridge, Tennessee; April 

1999; SRDB Ref ID: 8358 

Y-12 Plant, Air Monitoring Reports for dates 1943 through 1959, Y-12 Plant: Oak Ridge, Tennessee; 

no date; SRDB Ref ID: 642 

Y-12 Plant, 1956, Y-12 Plant Health Physics Semi-Annual Report – July 1956-December 1956, Y-12 

Plant; Oak Ridge, Tennessee; January , 1957; SRDB Ref ID: 13248 

Y-12 Plant, 1963, Y-12 Plant Quarterly Health Physics Report – Fourth Quarter CY 1962, Y-12 

Plant; Oak Ridge, Tennessee; March 5, 1963; SRDB Ref ID: Currently Not Assigned 

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SEC-00028 Y-12 Plant 

Y-12 Plant, 1991, Internal Dosimetry: Weekly Highlights 10-21-91 through 10-25-91, Y-12 Plant: 

Oak Ridge, Tennessee; 1991; SRDB Ref ID: 1952 

Y-12 Health Physics Department, 1957, TheY-12 Health Physics Program, Y-12 Health Physics 

Department; Oak Ridge, Tennessee; December 1957; SRDB Ref ID: 16815 

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