Review of One Advisory Board-Selected 

Case Reworked for the Evaluation of Norton 

Dose Reconstruction Template Revisions 

(DCAS-PER-059, Subtask 4)

Kathleen Behling, SC&A, Inc.

Advisory Board on Radiation and Worker Health, 

Subcommittee for Procedure Reviews

February 15, 2022
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Summary of Norton Facility operational 

history

 Worked with thorium and uranium

 Operational period 1945 through 1957

 Residual radiation period 1958 through October 2009 

 No technical basis documents

 Dose reconstruction (DR) methodology incorporated into a 

template
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DCAS-PER-059, “Norton Company”

 Issued April 2015 due to revisions to the Norton Company 

template

 Revision included: 

– Modified template to include second SEC class corresponding to 

portion of residual period (January 1, 1958, to October 10, 1962) 

– Incorporated updated ORAUT-OTIB-0070, revision 01, guidance, which 

adopted a lower depletion rate of 0.067% per day for residual 

contamination starting October 10, 1962, through 2009
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SC&A’s review of DCAS-PER-059

 SC&A’s May 2017 review identified three findings

 Summary of findings:

– Finding 1: Insufficient information in template to identify critical data and 

parameters needed to duplicate and/or confirm model for estimating external 

deep and shallow doses starting with the residual period of 1962

– Finding 2: Cited references for “air dust” survey data identifies five of nine 

references containing “operational” thoria and uranium data with dates 

starting in 1958 and continuing through 1964

– Finding 3: 1962–1963 air concentration and daily intake values for uranium 

derived by SC&A are a factor of 2 lower than values listed in template

 All findings were discussed and closed during Subcommittee 

for Procedure Reviews meeting October 31, 2018
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DCAS-PER-059 subtask 4 review of one 

reworked case

 ABRWH selected one reworked case for SC&A’s review in 

April 2021, based on the following criteria:

– assignment of external dose during the residual period

– assignment of internal dose during the residual period

 SC&A reviewed the reworked case in December 2021 to 

determine if external and internal doses were correctly 

assessed in accordance with DCAS-PER-059
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NIOSH’s reworked DR

 NIOSH’s rework of the case:

– Used applicable DR tools 

– Recalculated all annual doses 

– Re-ran IREP

 Revised DR report not sent to the U.S. Department of Labor 

because the compensation decision did not change
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Case background

 Energy employee (EE) worked at Norton Company for multiple 

brief periods during the residual period

 EE was not monitored for radiation exposure

 Diagnosed with qualifying cancer about 25 years after 

employment termination
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Comparison of NIOSH’s reworked doses 

versus original doses

 Original DR calculated external and internal doses of 

<0.001 rem

 Reworked DR calculated modest external and internal doses
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Original external dose calculations

 Used guidance in template available in 2010 for external dose 

during the residual period

 No prorating for partial years of employment

 Applied dose conversion factor (DCF) of 1.000

 Derived dose of <0.001 rem
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Reworked external dose calculations

 Used residual period external exposure values from updated 

2011 template

 No prorating for partial years of employment. 

 Applied exposure DCF of 1.44 for the thyroid as the surrogate 

organ

 Assigned dose of ~0.030 rem
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SC&A’s conclusions on external dose

 Appropriate dose values selected from revised template

 Correct surrogate organ was selected, based on ORAUT-OTIB0005, revision 05

 Appropriate DCF value was applied

 No partial-year prorating applied, as an efficiency and claimantfavorable measure

 Review confirmed doses were accurately entered in IREP 

 As expected, reworked DR external dose increased from that 

calculated in the original DR

 SC&A had no findings about reworked external dose assignment
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Original internal dose calculations

 Inhalation and ingestion intakes from DR methodology 

template 

 Used CADW to compare doses from U-234 absorption types M 

and S with Th-232 absorption types M and S, with Th-232 

type M resulting in the highest dose

 Calculated dose of <0.001 rem 
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Reworked internal dose calculations

 Used inhalation and ingestion exposure values from updated 

template 

 Assumed isotopic mix of U-234, Th-232, Th-228, Ac-228, 

Ra-228, Ra-224, and Rn-220 

 Compared solubility types M and S, with type M resulting in 

more claimant-favorable dose

 Using CADW, calculated dose of <0.020 rem
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SC&A’s conclusions on internal dose

 Reviewed NIOSH’s CADW files for the reworked DR and 

confirmed that correct intake values were used, based on data 

in updated template 

 SC&A verified: 

– Type M solubility resulted in the higher dose

– Dose data appropriately entered in IREP table

– Doses were assessed to the date of cancer diagnoses

 SC&A had no findings about the assessment of internal dose in 

the reworked case
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Questions?