Division of Compensation Analysis and 

Support 

Program Evaluation Report

Document Number: DCAS-PER-051

Effective Date: 3/4/2015 

Revision No. 0

Weldon Spring Plant Page 1 of 2 

Author: Signature on file Date: 3/4/2015 S upersedes: None 

 Dave Allen, HP Team Leader 

Approval: Signature on file Date: 3/4/2015 

 J.W. Neton, Associate Director for Science 

RECORD OF ISSUE/REVISIONS 

ISSUE 

AUTHORIZATION 

DATE 

3/4/2015

 EFFECTIVE

DATE 

3/4/2015 

 REV. NO. 

0 

DESCRIPTION 

New document to determine the effect of 

a revision to the Weldon Spring Plant 

TBD on previously completed claims. 

 

1.0 Description 

A six section Technical Basis Document (TBD) for the Weldon Spring Plant (ORAUTTKBS-0028) is used for conducting dose reconstructions. Sections 3 through 6 of the 

TBD that contain information used to calculate doses were revised between 1/30/2013 

and 5/21/2013. This PER considers the effect of these changes on dose reconstructions 

that were completed using previous versions of the TBD. 

 

2.0 Issue Evaluation 

The revisions to the Weldon Spring Plant TBD included several changes that would 

cause an increase in calculated doses. Because the changes cover all operational time 

periods and job types, no claims were excluded from further evaluation based on job 

types or employment period. Thus, a detailed listing of changes made to the TBD is not 

necessary. Some of the changes that were made in the revision include: 

- Change in assumed isotopic ratios for uranium ore concentrates; 

- addition of a neutron to photon ratio; 

- addition of a geometry correction factor for external dose; 

- addition of a thoron exposure dose; 

- Change in recycled uranium contaminate fractions; and, 

- an increase in the radon exposure estimate. 

3.0 Plan for Resolution or Corrective Action 

A database search was conducted to develop of list of all claims that may have had 

employment at the Weldon Spring Plant. The search included employment at the 

 
Division of Compensation Analysis and 

Support

Program Evaluation Plan

Document Number: DCAS-PER-051

Effective Date: 3/4/2015 Revision No. 0 Page 2 of 2

“Weldon Spring Plant”, the “Weldon Spring Raffinate Pits” and the “Weldon Spring 

Quarry”. The original search resulted in 286 potentially affected claims.

Four claims were removed from the list that were completed using the revised TBD.

Five claims had been “pulled” from dose reconstruction by DOL and were removed from 

the list.

112 claims were removed because the previous dose reconstruction resulted in a 

probability of causation (POC) of 50% or greater.

46 of the remaining claims also had employment at Mallinckrodt and were part of the 

Special Exposure Cohort at that facility.

2 claims were excluded because they had no verified Weldon Spring employment and the 

Weldon Spring TBD was not used in the dose reconstruction.

2 claims were excluded because the employment only included the construction period 

prior to the start of any radiological operations.

This process left 115 claims to be evaluated further. During the evaluation, three more 

claims were removed from the list prior to being evaluated further. One was determined 

to meet the Mallinckrodt SEC criteria. A dose reconstruction for this claim was done 

prior to the designation of the Mallinckrodt SEC but no dose reconstruction would now 

be necessary for a compensation decision. The second was removed because the 

employment was outside the covered period for the site. The third claim was returned to 

NIOSH for a new dose reconstruction for other reasons. That claim will be revised using 

the current revision of the TBD.

Dose for the remaining 112 claims was recalculated using the current revisions of the 

TBD as well as any other applicable documents. The resulting Probability of Causation 

(POC) for 101 of the claims was below 45%. Eight of the claims resulted in a POC 

greater than 50%. The remaining three claims had a POC between 45% and 50%. For 

those 3 claims, IREP was run 30 times at 10,000 iterations per NIOSH procedures and 

the resulting POC was still less than 50% for the each of those claims.

NIOSH will provide the Department of Labor with the list of all the claims evaluated under 

this PER. Further, NIOSH will request that DOL return the 8 claims that would now result in 

a POC greater than 50%.