PANTEX SEC PETITION REVIEW

(Remaining years: 1951–1957, 1984–1991)

Brad Clawson, Chair, Pantex Plant Work Group

Joe Fitzgerald, SC&A Team

Advisory Board on Radiation and Worker Health

Idaho Falls, Idaho

July 16–17, 2013
WORK GROUP REVIEW: OVERVIEW

• November 20, 2007: Petition qualified

• August 8, 2008: NIOSH Evaluation Report issued

• October 20, 2011: ABRWH recommendation of SEC for 1958–1983

– “NIOSH lacked adequate information necessary to complete individual [DRs] 

with sufficient accuracy for internal radiological exposures due to uranium...”

– However, NIOSH believed it could bound uranium exposures in 1984–1989, 

during W28 system dismantlement using 1990 bioassay data

• January 2012: NIOSH issues white paper (Bihl and LaBone) providing dose 

reconstruction (DR) method for 1984–1989 

– NIOSH seeks additional W28 worker access information for start dates for 

disassembly

– SC&A reviews NIOSH white paper, holds technical conference call, conducts 

site data capture

• June 18, 2013: Work Group meeting on remaining SEC issues
REMAINING SEC ISSUES

• Uranium, 1951–1957: Presence of weapons system uranium sources with 

exposure potential during handling 

• Uranium, 1984–1989: Feasibility of DR based on proposed NIOSH method 

(assumed bounding intakes; Bihl and LaBone 2012)

• Uranium, 1990–1991: Feasibility of DR based on adequacy and 

completeness of uranium bioassay data

• Thorium, 1984–1991: Feasibility of DR based on proposed NIOSH method 

(mass ratio with uranium; Ruhter et al. 2011)
URANIUM, 1951–1957

• SC&A confirmed no weapons system dismantlements before 1958

• Fresh DU forms handled, but no evidence of exposure potential

• Burn pits and hydroshot testing involved DU, but sufficient air sampling 

data exist upon which NIOSH can base DR

• Work Group recommends acceptance of NIOSH’s ability to reconstruct dose 

from uranium exposures
URANIUM, 1984–1989

• NIOSH paper (Bihl and LaBone 2012) presents set of assumed intakes 

derived from excretion values from lognormal analysis of 1990 uranium 

urinalyses for W28 workers involved in 1989 contamination incident

• Five different intake timing assumptions used to define exposure scenarios 

from which bounding intake can be postulated; SC&A raised concerns over 

uncertainties involved

• Work Group discussion led to conclusion that proposed method may not 

reflect all sources of uranium exposure at Pantex, or when they may have 

occurred (including possible enriched uranium sources)

• Work Group recommends an SEC be considered for all employees at Pantex

for 1984–1989 based on the lack of a feasible method to reconstruct 

uranium exposures with sufficient accuracy
URANIUM, 1990–1991

• Following 1989 uranium contamination event on W28 disassembly line, 

Pantex initiated routine bioassay program with 431 and 239 workers 

enrolled in 1991 and 1992, respectively

• The year 1990 was a transition year, with bioassay data for 46 workers 

(essentially follow-up from 1989 incident)

• SC&A validated ER finding of adequate bioassay data in routine bioassay 

program; noted 1990 as transition year at Work Group meeting

• Work Group recommends an SEC be considered for 1990 based on 

insufficient bioassay data to support DR with sufficient accuracy (and 

recommends acceptance of NIOSH’s ability to reconstruct doses from 

uranium exposures for 1991)
THORIUM, 1984–1991

• Ruhter et al., 2011 assumes chronic intake of thorium pegged at 2% of DU intake 

for times when thorium is present with uranium in disassembly

• Based on mass ratio intake values derived from 1996 air samples taken during W55 

disassembly (considered “worst” thorium-containing weapons system)

• Applied retrospectively to 1984–1991, assuming thorium disassembly was 

“cleaner” due to fewer disassemblies and less time since fabrication for oxidation, 

and engineering safeguards were “largely unchanged”

• SC&A questioned the validity of these assumptions, particularly with installation of 

gloveboxed downdraft table for W55 disassembly in late 1991, which brought into 

question representativeness of 1996 mass ratio proposed for the pre-1992 period

• Uranium and thorium contamination likely varied between individual W55 units

• Work Group recommends SEC be considered for all employees at Pantex for 1991 

based on lack of feasible method to reconstruct thorium exposures with sufficient 

accuracy (1984–1990 period subsumed by uranium SEC recommendations; 

thorium DR relies upon mass ratio with uranium, which Work Group finds 

infeasible for 1984–1990).
SITE PROFILE ISSUES: STATUS

1. Adequacy of Internal Dose Records – Closed at June 2013 WG

2. Internal Dose Models for Uranium – Closed at June 2013 WG

3. Dose Estimate Approach for Plutonium – Closed

4. Dose Estimate Approach for Thorium – Closed at June 2013 WG

5. Internal Dose Approach for Metal Tritides – Closed

6. Interpretation of External Dosimetry Data* – NIOSH and SC&A to 

finalize/close

7. Neutron-to-Photon Ratio Not Bounding – NIOSH and SC&A to 

finalize/close

8. Completeness of Exposure Sources* – NIOSH and SC&A to finalize/close

9. Incidents Cited Limited, Incomplete* – NIOSH and SC&A to finalize/close

(* encompassed by SC&A white paper/NIOSH response)
SITE PROFILE ISSUES: STATUS (cont’d)

10. Inadequate Consideration Given to Firing Sites – Closed at June 2013 

WG

11. Validation Whether Most Exposed Workers Badged – Closed

12. Accuracy of Plant Exposure Data (Petitioner Issue) – Closed

13. Too Few Workers Monitored for Valid Dose Reconstruction (petitioner 

issue)* – NIOSH and SC&A to respond

14. Records Incomplete for Subcontractors, Temps, Short-term Employees 

(petitioner issue) – Closed

15. Exposure from Tritium Leaks (petitioner issue)* – NIOSH and SC&A to 

finalize/close

16. Badge Placement (petitioner issue) – NIOSH to follow up

17. Efficacy of HP and IH Programs (petitioner issue) – Merged with Other 

Matrix Issues – Closed at June 2013 WG

 (* encompassed by SC&A white paper/NIOSH response)
SUMMARY

• Work Group recommends full Advisory Board review and action regarding 

dose reconstructability of worker exposure at Pantex for:

– Uranium from 1984 through 1990, where an exposure potential existed with 

the disassembly of the W28

– Thorium during 1991, where an exposure potential existed with the 

disassembly of the W55

• Work Group recommends acceptance of NIOSH’s ability to reconstruct 

uranium exposures from 1951 through 1957, as provided in the Evaluation 

Report for SEC-0068, Pantex Plant

• Completes remaining SEC issues for petition period

• Work Group will continue to focus on resolving remaining site profile 

issues