Hooker Electrochemical

Special Exposure Cohort 

Petition Evaluation 

Update

Henry A. Anderson, M.D.

Chairman 

Uranium Refining AWE Work Group

December, 2011

Tampa, FL
Background

 Hooker Electrochemical classified as an 

Atomic Weapons Employer (AWE) facility 

from 1943 to 1948 

 Residual contamination period through 

1976

 Primarily produced non-radioactive 

chemicals (P-45) for the MED

 Concentrated uranium-contaminated 

magnesium fluoride slag using waste 

hydrochloric acid from P-45 process
Background

(Continued) 

 Building was constructed to perform the 

concentrating operation; Building was 

completed on July 11, 1944

 Most slag-handling conducted outdoors

 P-45 operations ended January 15, 1946

 Concentration of incoming material was 

0.2% uranium by mass

 Material was concentrated to 1% to 2%
Process at Hooker

 C-2 slag was received in 500-pound 

barrels from Electro Metallurgical

• The barrels were dumped onto a conveyor belt 

that carried slag to one of three digest tanks

• Waste HCL from the P-45 plant was added to 

the tank and diluted to a ph of 4.0

• The tank was agitated for 20 hours

• Once in two days the liquid was decanted and 

more HCL was added.

• At the end of the digestion, the slurry was 

neutralized with lime and pumped to a filer 

press

• The filtered material was rebarreled
Special Cohort Petition 

Bases and Concerns

 Unmonitored workers

• Petition presented an affidavit 

indicating there was no internal or 

external radiation monitoring at Hooker.

• No indication of monitoring was found 

in records.
Hooker TBD

 Dose reconstruction methodology was 

originally described in Appendix AA to 

Battelle-TBD-6001 

 Hooker TBD replaced Appendix AA and 

changed proposed method of dose 

reconstruction, including revising 

approach to use of surrogate data for the 

internal dose
Petition Timeline Overview

 Submitted on March 6, 2009 – proposed class 

was for the “furnace room”

 Proposed finding sent to petitioner 5/15/2009 

– not qualified for evaluation

 Petitioner revised proposed class 9/26/2009

 Qualified for evaluation 10/16/ 2009

 Evaluation Report issued on 5/3/2010

 AWE Workgroup assigned review
Petition Timeline Overview

(Continued)

 8/2011 AWE Workgroup recommends denial

 8/2011 ABRWH Board tables motion 

• requests expanded paper on surrogate data assessment

• Allow more time for petitioner review

 AWE Workgroup tasks SC&A to prepare 

whitepaper – Thurber Sept 22 memo 

 AWE Workgroup meets 11/21/2011
Internal Exposure Modeling

Use of Surrogate Data

 Based on 18 air samples for handling C-2 slag 

at Electromet, Fernald, and Mallinckrodt

 Used upper 95th percentile of air sampling 

results

 More than 70% of air samples are BZ

 For residual period deposition/ resuspension

model used with resuspension factor of 1E- 06/m and no source term decay
External Exposure Modeling

 Exposure to workers handling slag in 

wooden barrels based on MCNPX 

calculations

 Exposure to workers from surface 

contamination based on MCNP 

calculations of slag dust settling from 

95th percentile air concentrations

 External doses rates for residual period 

same as for operating period
Work Group Review

Use of Surrogate Data

 In May 2011, NIOSH issued a white paper 

evaluating the use of surrogate data at 

Hooker against ABRWH criteria. 

 The Work Group requested that NIOSH 

revise the white paper to fully document 

sources of air samples, and requested that 

SC&A review the revised white paper. 
Work Group Review 

Use of Surrogate Date

(Continued) 

 SC&A reviewed the revised NIOSH white 

paper and concluded that: 

“Based on our review, we believe that NIOSH has 

addressed the ABRWH surrogate data criteria in an 

appropriate manner, and that the use of surrogate data 

at Hooker is consistent with the Board criteria. Use of 

the selected surrogate data will result in plausible 

bounding estimates for internal exposures at Hooker.”
Work Group Review 

Use of Surrogate Date

(Continued)

 Thurber Sept 22, 2011 memo 

• SC&A review includes an expanded group of air 

samples – 67-72 vs NIOSH 18

• 95% upper confidence limit in the range of NIOSH’s

– NIOSH 806 dpm/m3 SC&A 555 - 759 dpm/m3 

• The 95th percentile is not particularly sensitive to 

reasonable but differing technical judgments in 

sample selection 
Work Group Recommendation 

 After 11/17 meeting discussions, Work 

Group continues to believe surrogate data 

use proposed follows ABRWH criteria 

 Doses for workers at Hooker can be 

plausibly reconstructed using information 

in the Hooker TBD (revised June 2011). 

 Work Group continues to recommend that 

Petition SEC-0014 be rejected. 
Remaining Issues for ABRWH

 Is proposed use of surrogate data 

appropriate? 

 Is the Fernald monitoring data reliable?

 Petitioners have requested ABRWH Board 

defer decision until after petitioners 

receive response to FOIA request