Review Status of Area IV Santa Susana Field 

Laboratory SEC Petition-00235

Doug Farver, SC&A

Bob Barton, SC&A 

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Advisory Board on Radiation and Worker Health

Albuquerque, NM 

December 13–14, 2017
Work Group Members

 Phillip Schofield (Chair)

 Henry A. Anderson, M.D.

 Josie Beach

 Wanda I. Munn

 John W. Poston, Sr.

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SEC-00235 Background

August 9, 2016: Petition SEC-00235 received for class: 

• All employees of North American Aviation, to include corporate 

successors and subcontractors who worked at Area IV of the 

SSFL from December 31, 1964 through present.

February 1, 2017: NIOSH qualified the petition for the 

following class:

• All employees who worked at Area IV of the Santa Susana Field 

Laboratory from August 1, 1991 through June 30, 1993.

• Petition qualified for evaluation report (ER) based on lost, 

falsified, or destroyed dosimeter data due to the site’s use of CEP 

as a contractor providing internal dosimeter data for the period 

August 1991 to June 1993. 

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SEC-00235 Background (cont.)

August 2017: SC&A tasked to review SEC-00235 ER 

focusing on NIOSH’s position that the lack of 1991–1993 

data does not affect NIOSH’s ability to perform sufficiently 

accurate internal dose reconstructions for monitored or 

unmonitored workers. 

November 2017: SC&A issued SCA-TR-2017-SEC011, 

Revision 0, A Focused Review of the NIOSH SEC-00235 

Petition Evaluation Report for Santa Susana Field 

Laboratory Area IV.

December 4, 2017: SSFL Work Group (WG) meeting to 

discuss SC&A report and path forward.

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Previous Petitions Qualified for Evaluation

2009: Petition SEC-00093

• January 1, 1955, through December 31, 1958 

2010: Petition SEC-00156

• January 1, 1959, through December 31, 1964 

2017: Petition SEC-00234 

• January 1, 1965, through December 31, 1988 

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Summary of SC&A Review Findings

 Employee monitoring and workplace monitoring data sufficient 

to bound external exposures. 

 Review of available documentation does not indicate significant 

changes in the nature of radiological work or unusual 

occurrences during the SEC period that would preclude dose 

reconstruction. 

 The bioassay data obtained during the remediation period did 

not exceed the bioassay data from the operations period (pre1988) that are proposed for use in dose reconstruction. 

 Extending uranium, plutonium, and mixed fission product 

intake rates in ORAUT-OTIB-0080 would likely bound potential 

intakes during the CEP period for these radionuclides (assuming 

is adequately established via air sampling that conditions did not 

appreciably change).

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Remaining Areas of Concern

 SC&A’s review of ORAUT-OTIB-0080 identified several 

findings relevant to the 1991–1993 period. These findings 

and observations have not been resolved. 

 Not clear how NIOSH will reconstruct internal exposures 

to other actinide contaminants, such as americium and 

thorium, during the evaluated period.

 Suggest comparison of general air and breathing zone data 

from the 1991–1993 period to other decontamination and 

decommissioning (D&D) activities as well as the 

operational period to assure radiological conditions are 

sufficiently similar or bounding for use in internal dose 

assessment.

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SSFL Internal Coworker Model: OTIB-0080

 NIOSH proposes to use the internal coworker data from 

the operational period to reconstruct intakes during the 

SEC period (August 1991–June 1993).

 OTIB-0080 was approved in March 2014 and provides 

intake values for plutonium, uranium, and fission 

products:

 Plutonium intakes developed for 1965–1986

 Uranium intakes developed for 1965–1988

 Fission product intakes developed for 1965–1991

 SC&A reviewed OTIB-0080 in November 2014, with a 

total of 15 findings.

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SSFL Internal Coworker Model: OTIB-0080 (cont.)

What SC&A OTIB-0080 findings are still relevant to SEC-00235?

 Some original findings/observations were obviated by SEC-00234 

(Findings 4, 11)

 Others are no longer relevant because OTIB-0080 has not been updated 

to reflect the time-weighted-one-person-one-statistic (TWOPOS) 

approach (Findings 5, 8, and 10)

 Most remaining findings center around the calculation of the coworker 

intakes during the operational period (likely not relevant to SEC 

determination but relevant to site profile issues):

 Combination of years for bioassay analysis

 Interpretation of “less than” bioassay results

 Inclusion criteria for usable bioassay results

 Finding 15: Other potential radionuclides (i.e., tritium, thorium, 

americium) – potentially relevant to the SEC

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OTIB-0080 Finding 15 (SEC Relevance)

 SEC-00234 was granted based mainly on the inability to 

reconstruct internal exposures to thorium and 

americium during the operational period.

 Current SEC-00235 evaluation does not discuss this 

potential source term or methods for reconstruction of 

these radionuclides during potentially relevant D&D 

activities.

 NIOSH has agreed to evaluate the exposure potential to 

these contaminants and/or develop methods to 

reconstruct internal exposures (if deemed necessary).

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Relevant Air Sampling During SEC Period

 Air sampling data available for major radiological areas during the 

SEC period:

 Rockwell International Hot Laboratory

 Radiological Material Disposal Facility

 System Nuclear Auxiliary Power Facility 

 Hot Laboratory data are available throughout SEC period.

 Other areas have partial data due to regulatory recommendations at 

the time.

 Other relevant air sampling may be available.

 NIOSH has agreed to determine the availability of air sampling 

records and evaluate relevant records to assure that radiological 

conditions during the SEC period are sufficiently similar to other 

D&D activities and are effectively bounded by operational coworker 

data.

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SC&A Survey of Affected Claimants

 30 total claims (1 more submitted since NIOSH SEC ER)

 SC&A reviewed claims for CATI information relevant to the SEC 

discussion:

 At least one incident described demolition work; however, it was not clear that 

radiological hazards existed in addition to general medical/health hazards

 No information identified in CATI reports to indicate significant changes in work 

practices or the general radiological environment during the SEC period

 Several claims indicated they were monitored externally and/or internally; 

however, no corresponding DOE monitoring records were identified

 DOE monitoring records:

 Internal data (whole body count): 5 of 29*

 External data: 10 of 29*

* One of the 30 claims had not yet received DOE monitoring records because it was 

recently filed.

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SC&A Survey of Affected Claimants (cont.)

 Survey of current population indicates 11 of 30 would likely require 

dose reconstruction if it is deemed feasible (others already 

compensated or have been administratively pulled).

 Past Dose Reconstruction Methods:

 Internal Dose: whole body counts used (where available), environmental 

internal exposures or program-wide guidance documents (i.e., OTIB0002 and OTIB-0018)

 External Dose: personal monitoring data (where available), ambient 

external exposures, or a combination of both

 SC&A Recommendation: If dose reconstruction is deemed feasible, 

it would be beneficial for the Board to review example dose 

reconstructions (hypothetical or actual) to understand how NIOSH 

intends to implement new internal/external coworker dose 

assignment. (Note: considered a site profile issue)

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NIOSH and SC&A Planned Path Forward

 Issue 1: NIOSH is to review and summarize available reports and extract 

summary air sample information for relevant facilities for the remediation 

period (post 1988). This is to rule out any abnormalities in the exposure 

potential during the CEP period, as well as before and after. The results will 

be presented to the WG as a white paper. This is not a dose reconstruction 

approach, but a summary of general levels of recorded air concentration 

information.

 Issue 2: NIOSH is to provide more detail and relevant references on the 

nature of the source term for thorium and americium during the residual 

period in continuation of the infeasibility of the later part of the 

operational period as outlined in SEC-00234.

 Issue 3: NIOSH is to provide sample dose reconstructions for the CEP 

period demonstrating the use of the coworker model. This is to be 

completed after Issues 1 and 2 have been discussed/resolved.

 NIOSH and SC&A are to review new information provided by the 

Petitioner just prior to the December 4, 2017, WG teleconference meeting.

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