Savannah River Site 

SEC Petition Evaluation Report Review 

Status Report

Mark Griffon, Chair, SRS Work Group

Joe Fitzgerald, SC&A Team

Advisory Board on Radiation and Worker Health

Augusta, Georgia 

April 29, 2014
Remaining Key Work Group Issues

Ongoing Review (post-September 1972):

• Neptunium-237

• Thorium

• Overall CTW to NCW internal dose comparison

• Subcontractor database validation

Other Open Issues, including:

• Recycled uranium

• Coworker model to be reviewed:

– Trivalent actinides, Am, Cm, Cf

– Fission and activation products

– Co-60

• Tritium/tritides

• Exotic radionuclides

• Internal dose due to incidents

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SC&A Review Activities

• Onsite Data Captures and Interviews:

– June 2013: Interview of crafts and construction workers

– August 2013: Joint NIOSH/SC&A data capture and interviews

– November 2013: Joint NIOSH/SC&A data capture and interviews

• Ongoing SRS Document Reviews

• Work Group/NIOSH/SC&A Technical Calls

• Work Group Calls/Meetings:

– February 5 and February 26, 2014 (neptunium and thorium)

– September 26, 2013, and April 7, 2014 [OPOS (One person-One sample)]

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Neptunium – Issue Status

• NIOSH Developed Coworker Model for Np-237 (ORAU-RPRT-0056, 2012)

– Proposes to use data for all workers based on conclusion that dose distributions of CTW 

and NCW workers were the same

– Proposes dose estimation methods for Np-237

• SC&A Provided Comments in July 2013 Review to which NIOSH Responded 

in January 2014:

– Findings 1–8 question CTW/NCW comparison and express concerns over OPOS

• Issues included whether both groups were monitored in same manner (or needed 

to be), statistical validity, minimum sampling size, and sample dominance

– Findings 9–19 address specific methods forNp-237 dose estimation

• Issues included use of chest vs. whole body geometry, whether 86.5 keV photons 

suitable for estimating Np-237, how whole body counts and urinalysis results 

actually compare, assumptions made about intake dates, and rationale for sharp 

discontinuities in observed in-vivo based intake rates for Np-237

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Neptunium – Work Group Actions

Work Group Meeting Call (February 26, 2014):

 

• Findings 1–8 of SC&A report address aspects devolving to comparability of 

CW:NCW — deferred to SEC Work Group for OPOS discussion

• Findings 9–19 address various concerns over current Np-237 dose 

estimation approach based on available bioassay data – NIOSH agreed to 

conduct additional comparative analysis of bioassay data and review new 

Np/Pu concentration ratio data for possible application

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Thorium – Issue Status

• NIOSH Issued Addendum #3 to ER Addressing Thorium (post-1972); 

Presented at the December 2012 Advisory Board Meeting, Knoxville 

– Addendum #3 concludes dose reconstruction feasible for thorium, 1972–2007, because 

of very low inventory, minimal use, process knowledge, radiological controls, and 

availability of alternate bioassay data (Am, Cm, Cf)

• SC&A Provided Comments in September 2013 Review to which NIOSH 

Responded in January 2014:

– Concerns over adequacy and completeness of NIOSH’s source term description (time 

and place); while NIOSH expanded Table 5-1, SC&A has issues with basis for table and its 

implementation

– Questions regarding monitoring configuration at tank farms to support bounding model 

for thoron exposure

– Concerns over wide variability observed in individual urine sample counts for thorium

– Other issues were deferred to SEC Work Group (OPOS-related), required provision of 

additional information, or were closed (e.g., chelation-related data not to be used)

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Thorium – Work Group Actions

Work Group Meeting Call (February 26, 2014):

• SC&A to prepare analysis of expanded Table 5-1 of OTIB-0081 used to 

identify SRS workers potentially exposed to thorium

• NIOSH to provide report of DAC-based approach to bound thorium doses 

after January 1, 1990

• NIOSH to obtain additional air sampling measurements for SRS tank farm 

to develop facility-specific bounding dose for thoron

• NIOSH to investigate derivation of coworker intakes for thorium given 

observed wide variability of counts for same urinalysis sample

• Issues related to CTW:NCW comparisons deferred to OPOS discussion

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Overall CTW to NCW Internal Dose Comparison –

SEC Work Group Deliberations

• ORAUT-RPRT-0053 (2012) introduced one person-one sample (OPOS) 

methodology as alternative to existing pooled-data approach for coworker 

models. Addresses problems of “data dominance” and correlation.

• General approach has specific application to SRS (e.g., Np and Th), but does 

not ameliorate concern over differences in CTW:NCW monitoring

• SC&A provided initial response to RPRT-0053, and more detailed response 

in September 2013 and Work Group presentation in April 2014:

– SC&A concludes that use of OPOS on fixed-period basis is not scientifically justified based 

on review of data dominance and correlation at SRS and Fernald, and statistical validity

– Should only be used where clear evidence of data dominance is present due to spike in 

samples from incident(s)

• NIOSH response (January 2014) and Work Group presentation (April 2014) 

dispute SC&A findings; will issue written response on presented SC&A 

issues

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Subcontractor Database Validation

Issue: 

Subcontractor dose records maintained in “company” hardcopy files prior to 

being migrated to electronic databases being used for dose reconstruction.

Questions:

• How complete were company files for various subcontractor tiers (i.e., 

company names, personnel identifiers)?

• Was all relevant information migrated to SRS electronic databases?

Work Group Action:

• Explore options to address these questions

• As a first step, NIOSH is reviewing NOCTS for claimants who were 

subcontractors and comparing with SRS electronic records

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