SEC Petition Evaluation Report 

Petition SEC-00156 

Report Rev #: 0 Report Submittal Date: January 12, 2010

Subject Expert(s): Michael Kubiak 

Site Expert(s): N/A 

Petitioner Administrative Summary 

Petition Under Evaluation 

Petition # Petition 

Type 

Petition A 

Receipt Date DOE/AWE Facility Name 

SEC-00156 83.14 November 27, 2009 Area IV of the Santa Susana Field Laboratory 

NIOSH-Proposed Class Definition 

All employees of the Department of Energy, its predecessor agencies, and their contractors and subcontractors 

who worked in any area of Area IV of the Santa Susana Field Laboratory from January 1, 1959 through 

December 31, 1964, for a number of work days aggregating at least 250 work days, occurring either solely 

under this employment or in combination with work days within the parameters established for one or more 

other classes of employees included in the Special Exposure Cohort.

Related Petition Summary Information 

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

SEC-00093 83.13 Area IV of the Santa 

Susana Field Laboratory 

Class included in the 

SEC for 1955-1958 

Related Evaluation Report Information 

Report Title DOE/AWE Facility Name 

SEC Petition Evaluation Report for Petition SEC-00093 Area IV of the Santa Susana Field Laboratory

ORAU Lead Technical Evaluator: Michael Kubiak ORAU Review Completed By: James Mahathy

Peer Review Completed By: [Signature on file] 01/12/2010 

Lara Hughes Date 

SEC Petition Evaluation Reviewed By: [Signature on file] 01/14/2010 

J. W. Neton Date 

SEC Evaluation Approved By: [Signature on file] 01/14/2010 

Stuart L. Hinnefeld Date 
SEC-00156 01-12-10 Rev. 0 FINAL SSFL – Area IV

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Evaluation Report Summary: SEC-00156, 

Santa Susana Field Laboratory-Area IV 

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

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

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

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

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

Compensation Program Act of 2000. 

NIOSH-Proposed Class Definition

All employees of the Department of Energy, its predecessor agencies, and their contractors and 

subcontractors who worked in any area of Area IV of the Santa Susana Field Laboratory from January 

1, 1959 through December 31, 1964, for a number of work days aggregating at least 250 work days, 

occurring either solely under this employment or in combination with work days within the 

parameters established for one or more other classes of employees included in the Special Exposure 

Cohort. 

Feasibility of Dose Reconstruction Findings

NIOSH lacks sufficient information, which includes biological monitoring data, sufficient air 

monitoring information, or sufficient process and radiological source information, to allow it to 

estimate with sufficient accuracy the potential internal exposures to various radionuclides to which the 

proposed class may have been subjected during the time period from January 1, 1959 through 

December 31, 1964. NIOSH finds that it is likely feasible to reconstruct external dose, including 

occupational medical dose, for Area IV of the Santa Susana Field Laboratory workers with sufficient 

accuracy. 

The NIOSH dose reconstruction feasibility findings are based on the following: 

 There is currently one class of Santa Susana Field Laboratory, Area IV workers associated with a 

previous NIOSH evaluation of SEC petition SEC-00093. The period currently designated for 

inclusion in the SEC extends from January 1, 1955 through December 31, 1958. 

 Through the course of ongoing dose reconstruction, continued data capture efforts, and 

investigations associated with SEC-00093, NIOSH has since determined that although bioassay 

data are available for some monitored workers after 1958, some SSFL-Area IV workers could 

have received intakes of radioactive materials after 1958 that went unmonitored. 

 During the development of co-worker distribution models to assess potential internal dose to 

unmonitored workers, NIOSH has found that the available bioassay data have limitations which 

preclude the development of adequate co-worker models for the years prior to 1965. Therefore, 

NIOSH determined that it is necessary to propose an extension of the SEC time period for the 

SSFL-Area IV site through December 31, 1964. 
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Although NIOSH found that it is not possible to completely reconstruct radiation doses for the 

proposed class, NIOSH intends to use any internal and external monitoring data that may become 

available for an individual claim (and that can be interpreted using existing NIOSH dose 

reconstruction processes or procedures). Therefore, dose reconstructions for individuals employed at 

Area IV of the Santa Susana Field Laboratory during the period from January 1, 1959 through 

December 31, 1964, but who do not qualify for inclusion in the SEC, may be performed using these 

data as appropriate. 

Health Endangerment Determination

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

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

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

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

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

through intakes of fission products and other radionuclides and from direct exposure to radioactive 

materials. Therefore, 42 C.F.R. § 83.13(c)(3)(ii) requires NIOSH to specify that health may have 

been endangered for those workers covered by this evaluation who were employed for a number of 

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

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

employees in the Special Exposure Cohort. 
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Table of Contents 

Evaluation Report Summary: SEC-00156, Santa Susana Field Laboratory-Area IV............................. 3

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

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

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

4.0 Radiological Operations Relevant to the Proposed Class ........................................................... 9

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

4.2 Radiation Exposure Potential from Operations................................................................ 11

4.3 Time Period Associated with Radiological Operations.................................................... 12

4.4 Site Locations Associated with Radiological Operations ................................................ 12

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

5.0 Summary of Available Monitoring Data for the Proposed Class.............................................. 13

5.1 Data Capture Efforts and Sources Reviewed ................................................................... 13

5.2 Internal Personnel Monitoring Data ................................................................................. 13

5.3 External Personnel Monitoring Data................................................................................ 14

5.4 Workplace Monitoring Data............................................................................................. 15

5.5 Radiological Source Term Data ....................................................................................... 15

6.0 Feasibility of Dose Reconstruction for the Proposed Class ...................................................... 15

6.1 Feasibility of Estimating Internal Exposures ................................................................... 16

6.2 Feasibility of Estimating External Exposures .................................................................. 17

6.3 Class Parameters Associated with Infeasibility................................................................ 17

7.0 Summary of Feasibility Findings for Petition SEC-00156........................................................ 18

8.0 Evaluation of Health Endangerment for Petition SEC-00156................................................... 18

9.0 NIOSH-Proposed Class for Petition SEC-00156 ...................................................................... 19

10.0 Evaluation of Second Similar Class .......................................................................................... 19

11.0 References ................................................................................................................................. 21
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SEC Petition Evaluation Report for SEC-00156

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

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

Michael Kubiak, MJW Technical Services. These conclusions were peer-reviewed by the individuals 

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

associated text. 

1.0 Purpose and Scope 

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

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

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

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

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

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

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

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

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

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

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

report. 

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

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

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

2.0 Introduction 

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

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

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

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

reconstructions.1

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

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

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

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

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

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

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

 

1

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

the detailed implementation guidelines available at http://www.cdc.gov/niosh/ocas. 
SEC-00156 01-12-10 Rev. 0 FINAL SSFL – Area IV

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

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

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

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

3.0 NIOSH-Proposed Class Definition and Petition Basis 

The NIOSH-proposed class includes all employees of the Department of Energy, its predecessor 

agencies, and their contractors and subcontractors who worked in any area of Area IV of the Santa 

Susana Field Laboratory from January 1, 1959 through December 31, 1964, for a number of work 

days aggregating at least 250 work days, occurring either solely under this employment or in 

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

employees included in the Special Exposure Cohort. During this period, employees at this facility 

were involved with the operation of various types of nuclear reactors and particle accelerators, 

low-power criticality testing, manufacture of reactor fuels, and the disassembly and inspection of 

reactor components and fuel assemblies. 

The evaluation responds to Petition SEC-00156 which was submitted by an EEOICPA claimant 

whose dose reconstruction could not be completed by NIOSH due to a lack of sufficient dosimetryrelated information. NIOSH’s determination that it is unable to complete a dose reconstruction for an 

EEOICPA claimant is a qualified basis for submitting an SEC petition pursuant to 42 C.F.R. § 

83.9(b). 

There is currently one class of Santa Susana Field Laboratory (SSFL)-Area IV workers associated 

with the previous NIOSH evaluation of SEC petition SEC-00093, for which the Secretary of Health 

and Human Services (HHS) has designated inclusion in the Special Exposure Cohort: 

Class added to the SEC effective July 18, 2009: Employees of the Department of Energy (DOE), 

its predecessor agencies, and DOE contractors and subcontractors who worked in any area of 

Area IV of the Santa Susana Field Laboratory for a number of work days aggregating at least 250 

work days from January 1, 1955 through December 31, 1958, or in combination with work days 

within the parameters established for one or more other classes of employees in the SEC (HHS, 

2009). 

Detailed information associated with the worker class added to the SEC can be found in the NIOSH 

evaluation report, SEC Petition Evaluation Report, Petition SEC-00093 (NIOSH, 2009). The basis for 

the designated 1955-1958 SEC class is the determination that NIOSH does not have access to 

sufficient personnel monitoring, workplace monitoring, or source term data to bound potential internal 

exposures from the various radionuclides for the evaluated worker class at Area IV of SSFL during 

the period from January 1, 1955 through December 31, 1958 (HHS, 2009). 

 

2

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

available at http://www.cdc.gov/niosh/ocas. 
SEC-00156 01-12-10 Rev. 0 FINAL SSFL – Area IV

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The timeframe of the designated SEC class was originally determined by NIOSH to correspond to the 

date after which an established bioassay program existed at SSFL and after which sufficient internal 

monitoring data were believed to have been identified (NIOSH, 2009). In the SEC-00093 Evaluation 

Report, NIOSH determined that the site initiated a routine bioassay program in August 1958, and that 

NIOSH had access to sufficient urinalysis results and other supporting data beginning in January 

1959. NIOSH determined that, beginning in late 1958, the practice at the facility was to collect 

quarterly urine samples based on job assignments that required exposures to radioactive materials 

(NIOSH, 2009). 

Through the course of on-going dose reconstruction, continued data capture efforts, and investigations 

associated with SEC-00093, NIOSH has since determined that there were insufficient access controls 

employed at SSFL-Area IV; as a result there were some workers who should have been monitored 

who were not. Although bioassay data are available for some monitored workers after 1958, NIOSH 

has determined that some SSFL-Area IV workers could have received intakes of radioactive materials 

after 1958 that went unmonitored. During the development of co-worker distribution models to assess 

potential internal dose to unmonitored workers, NIOSH has also found that the available bioassay data 

have limitations prior to 1965 (i.e., missing values for some positive sample results) which preclude 

the development of adequate co-worker models for the years prior to 1965. Therefore, NIOSH has 

determined that it is necessary to propose an extension of the SEC time period for the SSFL-Area IV 

site through December 31, 1964. 

4.0 Radiological Operations Relevant to the Proposed Class 

The following subsections summarize the radiological operations at the SSFL-Area IV site through 

December 31, 1964, and the information available to NIOSH to characterize particular processes and 

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

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

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

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

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

Unless otherwise indicated, information for Section 4.0 and its subsections was obtained from SEC 

Petition Evaluation Report for Petition SEC-00093, Santa Susana Field Laboratory-Area IV (NIOSH, 

2009), and its referenced documents. 

4.1 Operations Description 

This section describes the operations at SSFL-Area IV that are relevant to the NIOSH-proposed SEC 

class for all workers through December 31, 1964. 

SSFL consists of a total of 2,850 acres and is located in the Simi Hills of Ventura County, 

approximately 30 miles northwest of downtown Los Angeles, California. Based on ownership and 

operations, SSFL is divided into four administrative and operational portions—Area I, Area II, Area 

III, and Area IV. Department of Energy (DOE) operations were conducted in Rockwell Internationalowned and DOE-owned facilities on a 290-acre westernmost administrative and operational portion 

designated as Area IV. 
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Following World War II, the potential of atomic energy captured the interest of the United States 

Government and many companies. This interest resulted in the need for nuclear research and 

development (R&D) facilities. SSFL was initially established in 1947 by North American Aviation 

(NAA) to meet the requirements for a field test laboratory to static-fire large rocket engines; however, 

it also met NAA’s need for a nuclear research facility. As a result, Area IV was established in 1953 at 

SSFL as a nuclear research and development facility. EEOICPA-related radiological operations at 

SSFL-Area IV began in 1955 (DOE, 2010). Since then, SSFL-Area IV has housed both nuclear 

development and rocket development groups, although in distinct and separate locations. In 

December 1955, the nuclear development and rocket development groups were transformed into 

separate divisions: Atomics International (AI) and Rocketdyne. 

Two distinct AI groups were housed in Area IV and supported by DOE. One focused on development 

of civilian nuclear power, and the other was a center of excellence for research and testing of 

non-nuclear components related to liquid metals. These two groups were referred to as AI and Liquid 

Metal Engineering Center (LMEC), respectively. Nuclear R&D activities in Area IV increased 

rapidly from 1953 into the late 1960s, and then began to decline. AI was eventually merged into 

Rocketdyne in 1984 as a result of this decline. 

The LMEC was created in 1966 as a government-owned and contractor-operated organization; its 

purpose was to provide development and non-nuclear testing of Liquid Metal Reactor (LMR) 

components and to establish the Liquid Metal Information Center (LMIC) for the AEC’s Liquid Metal 

Fast-Breeder Reactor (LMFBR) program. The LMEC was renamed Energy Technology Engineering 

Center (ETEC) in 1978 to reflect DOE’s desire to broaden its mission beyond the LMFBR program. 

Several corporate mergers and organizational changes occurred over the years. In 1967, NAA merged 

with Rockwell Standard to become North American Rockwell. In 1973, the corporate name changed 

to Rockwell International (RI). Rockwell International continued to exist with AI and Rocketdyne as 

independent divisions until 1984 when AI was absorbed by the Rocketdyne division. The Boeing 

Company purchased RI in 1996; Rocketdyne is now a division of Boeing. 

SSFL-Area IV operations included two functional areas: Nuclear Reactor Development and Testing; 

and Nuclear Support Operations. Additional information regarding SSFL-Area IV functional areas 

and radiological operations can be found in ORAUT-TKBS-0038-2 and the SEC-00093 Evaluation 

Report (NIOSH, 2009). 
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SSFL-Area IV Nuclear Reactor Development and Testing included operations associated with: 

 Homogeneous Water Boiler Reactors 

 Sodium-Cooled Graphite-Moderated Reactor, designated as the Sodium Reactor Experiment 

(SRE) 

 Uranium-Zirconium Hydride Reactors associated with the Systems for Nuclear Auxiliary Power 

(SNAP) program 

 Critical Test Facilities 

 Civilian Nuclear Power Test Facilities 

 Organic Moderated Reactor (OMR) 

 Sodium Graphite Reactor (SGR) 

 Advanced Epithermal Thorium Reactor (AETR) 

 Fast Critical Experiment Laboratory 

SSFL-Area IV Nuclear Support Operations included work associated with: 

 Reactor Fuel Manufacturing 

 Fuel Storage 

 Disassembly and Examination of Reactors and Used Reactor Fuel Assemblies 

 Fabrication, Use, and Storage of Radioactive Sources 

 Preparation of Radioactive Material for Disposal 

 Research on Reprocessing Used Reactor Fuel 

 Operation of Particle Accelerators 

 Research using Radioisotopes 

 Fuel Storage 

 Corrosion Testing 

 Mechanical Component Development 

 Sodium Disposal 

4.2 Radiation Exposure Potential from Operations 

There were many different types of facilities and processes conducted at Area IV of the SSFL, which 

included reactors, critical test facilities, fuel preparation and post-irradiation examination facilities, 

accelerator and calibration facilities, and support facilities. Most reactors were low-power (a few 

kilowatts), with the maximum being 20 thermal MW, and all had relatively short operating histories. 

There was a Van de Graaff (deuterium-tritium) accelerator producing neutrons with a maximum 

energy of 14 MeV. The fuel examination and manufacturing facilities, reactors, and critical facilities 

handled fissionable fuels with various enrichments, mostly compounds of uranium including carbides. 

They also handled relatively small quantities of plutonium and thorium, with the exception of 

Buildings 4023, 4029, and 4030 where no thorium or plutonium was handled. Area IV of the SSFL 

did declad some fuels in the hot cells, resulting in the release of considerable quantities of fission 

products with high fission yields (e.g., Sr-90 and Cs-137) into the hot cell environment; there were 

smaller amounts of Eu-152, Eu-154, and tritium (ORAUT-TKBS-0038-6). The separations of 

irradiated fuel consisted only of pilot-scale operations conducted outside the hot cells; therefore, there 

were minimal contamination issues with gross fission products in non-hot-cell areas. 
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The operations summarized above resulted in potential internal and external radiation exposures for 

SSFL-Area IV workers during the DOE operations period 1955 through 1988. Because NIOSH has 

found indications that not all potentially-exposed workers were included in the personnel radiation 

monitoring program, an individual worker’s potential for radiation exposure at SSFL-Area IV cannot 

be determined based solely on the existence or non-existence of individual monitoring records. 

Additional information regarding the radioisotopes, work areas, and operations associated with 

radiation exposures at SSFL-Area IV can be found in the NIOSH evaluation report, SEC Petition 

Evaluation Report, Petition SEC-00093 (NIOSH, 2009). 

4.3 Time Period Associated with Radiological Operations 

Per the DOE Office of Health, Safety and Security, the time period associated with DOE operations at 

SSFL-Area IV is from 1955-1988, with a DOE remediation period from 1988 to the present (DOE, 

2010). As presented in Section 3.0 of this report, HHS has already designated that SSFL-Area IV 

workers during the period from January 1, 1955 through December 31, 1958 be included in the SEC. 

NIOSH has subsequently determined that the inability to estimate, with sufficient accuracy, the total 

internal dose for the employees of SSFL-Area IV extends through December 31, 1964. The period of 

radiological operations associated with this evaluation begins on January 1, 1959 (the end of the 

current SEC class designation) and continues through December 31, 1964. 

4.4 Site Locations Associated with Radiological Operations 

The class of workers already designated for inclusion in the SEC includes all employees of DOE, its 

predecessor agencies, and DOE contractors and subcontractors who worked in any area of Area IV of 

the Santa Susana Field Laboratory during the period from January 1, 1955 through December 31, 

1958. Through the course of ongoing dose reconstruction and continued research, NIOSH has 

determined that the site-specific and claimant-specific data available for SSFL-Area IV for the time 

period of this subsequent evaluation (1959-1964) are insufficient to allow NIOSH to characterize 

worker movements throughout the site. NIOSH is therefore unable to define individual worker 

exposure scenarios based on specific work locations within SSFL-Area IV. 

4.5 Job Descriptions Affected by Radiological Operations 

The class of workers already designated for inclusion in the SEC includes all employees of DOE, its 

predecessor agencies, and DOE contractors and subcontractors who worked in any area of Area IV of 

the Santa Susana Field Laboratory during the period from January 1, 1955 through December 31, 

1958. Through the course of ongoing dose reconstruction and continued research, NIOSH has 

determined that the site-specific and claimant-specific data available for SSFL-Area IV for the time 

period of this subsequent evaluation (1959-1964) are insufficient to allow NIOSH to determine that 

any specific work group was not potentially exposed to radioactive material releases or possible 

subsequent contamination. NIOSH has insufficient information associating job titles and/or job 

assignments with specific radiological operations or conditions and is, therefore, unable to define 

potential radiation exposure conditions based on worker job descriptions. 
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5.0 Summary of Available Monitoring Data for the Proposed Class 

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

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

monitoring data from breathing zone and general area monitoring are used to estimate the potential 

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

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

information characterizing and quantifying the source term. 

This same hierarchy is used for determining the external exposures to the cancer site. Personal 

monitoring data from film badges or thermoluminescent dosimeters (TLDs) are the primary data used 

to determine such external exposures. If there are no personal monitoring data, exposure rate surveys, 

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

exposure. 

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

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

Dose Reconstruction Implementation Guideline. These documents are available at: 

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

5.1 Data Capture Efforts and Sources Reviewed 

In addition to examining its Site Research Database (SRDB) to locate documents supporting the 

evaluation of the proposed class, NIOSH identified and reviewed numerous data sources to locate 

information relevant to determining the feasibility of dose reconstruction for the class of employees 

proposed for this petition. This included determining the availability of information on personnel 

monitoring, workplace monitoring, and radiological source term data. 

NIOSH’s continuing data capture efforts since the evaluation of petition SEC-00093 (April 2009) 

have included visits to the SSFL site in September and November 2009, and one visit to the San 

Bruno Federal Records Center in September 2009. NIOSH has worked with representatives from 

DOE Legacy Management and the SSFL site in an attempt to gather documents and data relevant to 

dose reconstruction of SSFL-Area IV claims. NIOSH’s SRDB currently contains over 900 documents 

associated with the SSFL-Area IV site. 

5.2 Internal Personnel Monitoring Data 

Radionuclides of concern for the facilities and processes at Area IV of the SSFL were primarily 

fission products. Exposure to fissionable material, transuranics, and activation products was also 

possible (NIOSH, 2009). Summaries of the available in vitro and in vivo data, as well as general 

overviews of sampling and analytical protocols, are provided in the previous NIOSH evaluation 

report, SEC Petition Evaluation Report, Petition SEC-00093 (NIOSH, 2009). Additional details, 

including analytical methods, detectable activities, and reporting protocols can be found in ORAUTTKBS-0038-5. 
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Subsequent to the NIOSH evaluation of SEC-00093, which identified data deficiencies through 

December 31, 1958, NIOSH continued data capture activities in an attempt to refine the methods and 

data available for the development of internal dose coworker distributions beginning in 1959. NIOSH 

worked with current site representatives for Area IV of SSFL to obtain an improved database of 

internal monitoring results. 

NIOSH determined that SSFL used a number of bioassay labs throughout its history. Each vendor 

had its own reporting methods and report format. SSFL historically maintained the results as reported 

and also transferred these results onto sheets summarizing the results for an individual; these were 

called the McBee cards and are relatively consistent through time. For some analyses of interest, the 

McBee cards had only a "+" entered when the result was positive and the reviewer was directed to go 

to the original lab card for the magnitude of the result. NIOSH worked with the SSFL site 

representative to evaluate the varying formats for the original vendor lab reports, and to assign more 

appropriate and descriptive field names, enter missing information, and recombine the data into a 

searchable database. 

Through continuing data capture activities, NIOSH has obtained additional data and reports that may 

be useful for determining the exposure potential for various work groups at SSFL-Area IV. However, 

NIOSH has evaluated the available database and supporting reports, and finds that the database still 

contains a substantial amount of ambiguous or indeterminate field entries for years prior to 1965, 

making the available database inadequate to support NIOSH’s development of bounding coworker 

distribution models for years prior to 1965. The database contains over 1100 urinalysis results for 

1963, and over 1400 for 1964, but there are still approximately 135 analyses for these years that are 

indicated to be positive for which NIOSH does not have a value to quantify the positive result. 

Beginning in 1965, the data available to NIOSH are sufficient for the development of bounding 

coworker internal dose distributions. The database contains over 1350 urinalysis results for the year 

1965, with adequate values being given for positive results. The database contains over 17,000 results 

for the years post-1964, and NIOSH has determined the data to be sufficient for statistical modeling. 

5.3 External Personnel Monitoring Data 

NIOSH has access to photon, beta, and neutron external dosimetry results, as well as other supporting 

data for the entire period evaluated in this report (available for all years of site operation). The policy 

at SSFL was to assign the applicable dosimetry to anyone with the potential for photon, beta, or 

neutron exposure; it was assigned based on job assignments that required exposure to radioactive 

materials (NIOSH, 2009; ORAUT-TKBS-0038-6). Summaries of the available external monitoring 

data can be found in the previous NIOSH evaluation report, SEC Petition Evaluation Report, Petition 

SEC-00093 (NIOSH, 2009). Details regarding the various analyses used, and the associated minimum 

detectable activities, are presented in ORAUT-TKBS-0038-6. 

Through the course of on-going dose reconstruction and investigations associated with SEC-00093, 

NIOSH determined that although external monitoring data are available for almost all monitored 

workers at SSFL-Area IV, some workers could have received external radiation exposures that went 

unmonitored. To assess potential external dose to unmonitored workers, NIOSH has developed a coworker dose distribution model (ORAUT-OTIB-0077). 
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5.4 Workplace Monitoring Data 

NIOSH has access to limited workplace air, surface, and environmental monitoring data for 

SSFL-Area IV prior to 1965. The data available prior to 1965 are inadequate for sufficiently accurate 

dose reconstructions in the absence of personnel monitoring data. Summaries of the available 

workplace and air monitoring data can be found in the previous NIOSH evaluation report, SEC 

Petition Evaluation Report, Petition SEC-00093 (NIOSH, 2009) and ORAUT-TKBS-0038-4. 

5.5 Radiological Source Term Data 

The diverse reactor, accelerator, and support operations at the SSFL-Area IV site resulted in potential 

exposures to radioisotopes of cobalt, strontium, cesium, europium, uranium, thorium, plutonium, and 

americium. The source term and activity data available to NIOSH for years prior to 1965 are 

inadequate for sufficiently accurate dose reconstructions in the absence of personnel or workplace 

monitoring data. Summaries of the general and building-specific source term information available to 

NIOSH for the SSFL-Area IV site can be found in the previous NIOSH evaluation report, SEC 

Petition Evaluation Report, Petition SEC-00093 (NIOSH, 2009) and ORAUT-TKBS-0038-2. 

6.0 Feasibility of Dose Reconstruction for the Proposed Class 

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

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

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

doses of individual members of the class with sufficient accuracy. 

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

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

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

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

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

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

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

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

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

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

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

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

of a class of employees to the SEC. 

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

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

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

the same statutory and regulatory criteria that govern consideration of all SEC petitions. 
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6.1 Feasibility of Estimating Internal Exposures 

NIOSH has evaluated the available personnel and workplace monitoring data and source term 

information and has determined that there are insufficient data for estimating internal exposures, as 

described below. 

As presented in Section 3.0 of this report, HHS has previously designated an SEC class for SSFLArea IV workers for the period from January 1, 1955 through December 31, 1958 (HHS, 2009). In 

the class designation letter, HHS states: 

NIOSH has concluded that it cannot reconstruct pre-1959 internal doses for the evaluated worker 

class at Area IV of SSFL. NIOSH does not have access to sufficient personnel monitoring, 

workplace monitoring, or source term data to bound potential internal exposures from the various 

radionuclides for the evaluated worker class at Area IV of SSFL during the period from January 

1, 1955 through December 31, 1958. Consequently, NIOSH finds that it is not feasible to 

estimate, with sufficient accuracy, the total internal dose for the class of employees covered by this 

evaluation.

In its previous evaluation report, SEC Petition Evaluation Report, Petition SEC-00093 (NIOSH, 

2009), NIOSH determined that a routine bioassay monitoring program was established at SSFL-Area 

IV in late 1958, and therefore, sufficiently accurate internal dose reconstruction was feasible 

beginning in 1959. Subsequent to NIOSH’s SEC-00093 evaluation, through the course of on-going 

dose reconstruction, continued data capture efforts, and related investigations, NIOSH determined that 

there were insufficient access controls in place at SSFL-Area IV; as a result, there were some workers 

who should have been monitored who were not. Although bioassay data are available for some 

monitored workers after 1958, NIOSH has determined that some SSFL-Area IV workers could have 

received intakes of radioactive materials after 1958 that went unmonitored. To assess potential 

internal dose to unmonitored workers, NIOSH continued its data capture activities in an attempt to 

refine the methods and data available for the development of internal dose coworker distributions 

beginning in 1959. As presented in Section 5.3 of this report, NIOSH has since determined that the 

available data contain a substantial amount of ambiguous or indeterminate results for periods prior to 

1965, making the available data inadequate for developing bounding coworker distribution models for 

years prior to 1965. 

NIOSH does not have access to sufficient personnel monitoring, workplace monitoring, or source 

term data to estimate potential internal exposures to fission products and other radionuclides during 

the period from January 1, 1959 through December 31, 1964. Consequently, NIOSH finds that it is 

not feasible to estimate, with sufficient accuracy, internal exposures to fission products and other 

radionuclides and resulting doses for the class of employees covered by this evaluation. 

Although NIOSH found that it is not possible to completely reconstruct internal radiation doses for the 

period from January 1, 1959 through December 31, 1964, NIOSH intends to use any internal 

monitoring data that may become available for an individual claim (and that can be interpreted using 

existing NIOSH dose reconstruction processes or procedures). Dose reconstructions for individuals 

employed at Area IV of the Santa Susana field Laboratory during the period from January 1, 1959 

through December 31, 1964, but who do not qualify for inclusion in the SEC, may be performed using 

these data as appropriate. 
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6.2 Feasibility of Estimating External Exposures 

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

to fission products and other radionuclides could not be reconstructed for a dose reconstruction 

referred to NIOSH by DOL. As noted above, HHS will consider this determination to be sufficient 

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

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

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

of workers covered by this report. 

In its previous SEC class designation for SEC-00093, HHS states: 

NIOSH has access to sufficient personnel monitoring and workplace monitoring data to bound 

potential external exposures for workers at Area IV of SSFL during the period from January 1, 

1955 through December 31, 1958. NIOSH also finds it is feasible to reconstruct occupational 

medical dose with sufficient accuracy for workers at Area IV of SSFL.

This current evaluation has found no evidence to the contrary for the period January 1, 1959 through 

December 31, 1964; NIOSH has established that it has access to sufficient information to either: (1) 

estimate the maximum external 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 (2) estimate the external radiation doses to members of the class more precisely than a 

maximum dose estimate. 

Adequate reconstruction of medical dose is likely to be feasible by using claimant-favorable 

assumptions in the technical information bulletin titled Dose Reconstruction from Occupationally 

Related Diagnostic X-Ray Procedures (ORAUT-OTIB-0006) and SSFL-Area IV site profile 

documents (ORAUT-TKBS-0038). 

6.3 Class Parameters Associated with Infeasibility 

HHS has already designated an SEC class for SSFL-Area IV workers for the period from January 1, 

1955 through December 31, 1958 (HHS, 2009). Through the course of on-going dose reconstruction, 

continued data capture efforts, and investigations associated with SEC-00093, NIOSH has determined 

that the inability to estimate, with sufficient accuracy, the total internal dose for the employees of 

SSFL-Area IV extends through December 31, 1964. NIOSH therefore recommends that the proposed 

class include the period from January 1, 1959 through December 31, 1964. 

As discussed in Section 4.4, NIOSH is unable to define individual worker exposure scenarios based 

on specific work locations within SSFL-Area IV. Therefore NIOSH recommends that the proposed 

class definition include all areas of Area IV of the Santa Susana Field Laboratory during the specified 

time period. 

NIOSH has found insufficient documentation associating job titles and/or job assignments with 

specific radiological operations or conditions. Without such information, NIOSH is unable to define 

the proposed SEC class based on worker job descriptions or the availability of individual monitoring 

data. NIOSH therefore recommends that the proposed class definition include all employees of the 
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Department of Energy, its predecessor agencies, and their contractors and subcontractors who worked 

at SSFL-Area IV during the specified time period, regardless of whether a worker was monitored for 

radiation exposure. 

7.0 Summary of Feasibility Findings for Petition SEC-00156 

This report evaluates the feasibility for completing dose reconstructions for employees at Area IV of 

the Santa Susana Field Laboratory from January 1, 1959 through December 31, 1964. NIOSH 

determined that members of this class may have received radiation exposures from intakes of fission 

products and other radionuclides. NIOSH lacks sufficient information, which includes biological 

monitoring data, sufficient air monitoring information, or sufficient process and radiological source 

information that would allow it to estimate the potential internal exposures to which the proposed 

class may have been exposed. 

NIOSH has documented herein that it cannot complete the dose reconstructions related to this petition. 

The basis of this finding demonstrates that NIOSH does not have access to sufficient information to 

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

radiation doses more precisely than a maximum dose estimate. 

Although NIOSH found that it is not possible to completely reconstruct radiation doses for the period 

from January 1, 1959 through December 31, 1964, NIOSH intends to use any internal or external 

monitoring data that may become available for an individual claim (and that can be interpreted using 

existing NIOSH dose reconstruction processes or procedures). Dose reconstructions for individuals 

employed at Area IV of the Santa Susana Field Laboratory during the period from January 1, 1959 

through December 31, 1964, but who do not qualify for inclusion in the SEC, may be performed using 

these data as appropriate. 

8.0 Evaluation of Health Endangerment for Petition SEC-00156 

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

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

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

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

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

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

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

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

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

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

the class may have accumulated chronic radiation exposures through intakes of fission products and 

other radionuclides and from direct exposure to radioactive materials. Consequently, NIOSH is 

specifying that health was endangered for those workers covered by this evaluation who were 

employed for a number of work days aggregating at least 250 work days within the parameters 

established for this class or in combination with work days within the parameters established for one 

or more other classes of employees in the SEC. 

9.0 NIOSH-Proposed Class for Petition SEC-00156 

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

with sufficient accuracy. This class includes all employees of the Department of Energy, its 

predecessor agencies, and their contractors and subcontractors who worked in any area of Area IV of 

the Santa Susana Field Laboratory from January 1, 1959 through December 31, 1964, for a number of 

work days aggregating at least 250 work days, occurring either solely under this employment or in 

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

employees included in the Special Exposure Cohort. 

10.0 Evaluation of Second Similar Class 

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

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

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

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

time, NIOSH has not identified a second similar class of employees at Area IV of the Santa Susana 

Field Laboratory for whom dose reconstruction may not be feasible. 
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11.0 References 

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

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

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

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

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

19392 

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

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

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

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

Program Act of 2000; as amended; OCAS website 

DOE, 2010, U.S. Department of Energy, Office of Health, Safety, and Security; Energy Employees 

Occupational Illness Compensation Program; Find facilities List: 

http://www.hss.energy.gov/healthsafety/fwsp/advocacy/faclist/findfacility.cfm 

HHS, 2009, HHS Designation of Additional Members of the Special Exposure Cohort under the 

Energy Employees Occupational Illness Compensation Program Act of 2000, Designating a Class of 

Employees from Santa Susana Field Laboratory – Area IV Santa Susana, California; Department of 

Health and Human Services (HHS); July 23, 2009; OSA Ref ID: 109364 

NIOSH, 2009, SEC Petition Evaluation Report for Petition SEC-00093, Santa Susana Field 

Laboratory-Area IV; National Institute for Occupational Safety and Health; April 28, 2009; available 

on OCAS website at: http://www.cdc.gov/niosh/ocas/pdfs/sec/area4/ssfler-r1.pdf; SRDB Ref ID: 

76961 

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

Procedures, Rev. 03 PC-1; Oak Ridge Associated Universities (ORAU); Oak Ridge, Tennessee; 

December 21, 2005; SRDB Ref ID: 20220 

ORAUT-OTIB-0077, External Coworker Dosimetry Data for Area IV of the Santa Susana Field 

Laboratory, the Canoga Avenue Facility (Vanowen Building, and the De Soto Avenue Facility 

(sometimes referred to as Energy Technology Engineering Center [ETEC] or Atomics International), 

Rev. 00; Oak Ridge Associated Universities (ORAU); Oak Ridge, Tennessee; August 3, 2009; SRDB 

Ref ID: 72162 

ORAUT-TKBS-0038-1; Atomics International – Introduction, Rev. 01; Oak Ridge Associated 

Universities (ORAU); Oak Ridge, Tennessee; August 30, 2006; SRDB Ref ID: 30080 

ORAUT-TKBS-0038-2; Energy Technology Engineering Center – Site Description, Rev. 00; Oak 

Ridge Associated Universities (ORAU); Oak Ridge, Tennessee; February 2, 2006; SRDB Ref ID: 

22140 
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ORAUT-TKBS-0038-3; Atomics International – Occupational Medical Dose, Rev. 01; Oak Ridge 

Associated Universities (ORAU); Oak Ridge, Tennessee; September 8, 2006; SRDB Ref ID: 30081 

ORAUT-TKBS-0038-4; Area IV of the Santa Susana Field Laboratory, the Canoga Avenue Facility 

(Vanowen Building), the Downey Facility, and the De Soto Avenue Facility (sometimes referred to as 

Energy Technology Engineering Center [ETEC] or Atomics International) – Occupational 

Environmental Dose, Rev. 01; Oak Ridge Associated Universities (ORAU); Oak Ridge, Tennessee; 

March 8, 2007; SRDB Ref ID: 30622 

ORAUT-TKBS-0038-5; Energy Technology Engineering Center – Occupational Internal Dose, Rev. 

00; Oak Ridge Associated Universities (ORAU); Oak Ridge, Tennessee; February 22, 2006; SRDB 

Ref ID: 22287 

ORAUT-TKBS-0038-6; Atomics International – Occupational External Dose, Rev. 01; Oak Ridge 

Associated Universities (ORAU); Oak Ridge, Tennessee; November 16, 2006; SRDB Ref ID: 30082