National Institute for Occupational Safety and Health

NIOSH Responses to SC&A Review of the Evaluation 

Report for SEC-00247- Superior Steel Co. 

Megan Lobaugh, PhD, CHP

Research Health Physicist

TBD-6000 Work Group Meeting

February 4, 2020
Overview

 Review of the Superior Steel Co.

 Review of the SEC-00247 Evaluation Report

 NIOSH Responses to the SC&A Review of the SEC-00247 ER

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Review of the Superior Steel Co.
About Superior Steel Co. Site  Carnegie, PA • 5 interconnected buildings  Uranium rolling for AEC  Covered Period • AWE: January 1, 1952 

through December 31, 1957

• Residual Radiation: January 

1, 1958 through present

Photo from USACE, 2018

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Superior Steel Co. Processing Areas

From Myrick, 1981

From Myrick, 1981

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Review of the SEC-00247 Evaluation 

Report
SEC-00247 Petition for Superior Steel Co.

 83.13 (Form B) Petition received May 1, 2018

– (F.1) Basis: Radiation exposures potentially incurred by members of 

the proposed class were not monitored either through personal 

monitoring or through area monitoring.

 Petition qualified for review on July 19, 2018

– Class under Review: All atomic weapons employees who worked in 

any area at Superior Steel Co. in Carnegie, PA during the period from 

January 1, 1952 through December 31, 1957.

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Evaluation of Petition Basis - Internal Monitoring

 “Individual uranium urinalysis data are unavailable for Superior Steel workers and 

none are known to exist.” (ORAUT-TKBS-0034)

– When personal internal monitoring data are unavailable, NIOSH uses air 

monitoring data from worker breathing zones and work areas, in accordance 

with NIOSH’s OCAS-IG-002, Internal Dose Reconstruction Implementation 

Guideline

– Site-specific air monitoring data and process data available to estimate 

internal uranium doses

– Airborne mass loading calculations from air monitoring data to estimate 

internal thorium doses

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Evaluation of Petition Basis - External Monitoring

 “No external dosimetry results are available for Superior Steel employees.” 

(ORAUT-TKBS-0034)

– When personal and area external monitoring data are unavailable, NIOSH uses 

workplace information (e.g., source term, process) to estimate dose, in 

accordance with NIOSH’s OCAS-IG-001, External Dose Reconstruction 

Implementation Guideline

– Site-specific information, in conjunction with Battelle-TBD-6000, to model 

external uranium exposures

– Site-specific information, in conjunction with Battelle-TBD-6000, to model 

external thorium exposures

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Feasibility Findings for SEC-00247 Superior Steel Co. 

January 1, 1952 to December 31, 1957

Source of Exposure Dose Reconstruction Feasible

Internal Yes

Uranium Internal Yes

Thorium Internal Yes

External Yes

Uranium External Yes

Thorium External Yes

Occupational Medical X-rays Yes

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NIOSH Proposed Dose Reconstruction Methods -

Applicable Years 

 Uranium

• Operations:

• June 27, 1952 through 

December 31, 1957

• Residual Contamination:

• January 1, 1958 through 

present

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 Thorium

• Operations:

• March 27, 1956 through 

April 20, 1956

• Post-Ops Contamination:

• April 21, 1956 through 

December 31, 1957

• Commercial, non-AEC work
NIOSH Proposed Dose Reconstruction Methods -

Internal Exposures (1952-1957)

Intake 

Information Uranium Thorium

Rolling 500 h per year

U air concentration results

10 h during March – April 1956 

Th air concentration calculated using

a mass loading approach

Resuspension

 

2000 h per year U resuspension Remainder of 1956 and all of 1957 

Th resuspension

Material 

Assessed as

U-234 including recycled U 

contaminants

Th-232 including Th daughter 

products in secular equilibrium

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NIOSH Proposed Dose Reconstruction Methods -

External Exposures (1952-1957)

Exposure Type Uranium Thorium

Direct Rolling

500 h per year

Battelle-TBD-6000 

rolling operations dose

10 h in March – April 1956

MCNP modeling and distance guidance 

in Battelle-TBD-6000

Submersion 

Rolling

500 h per year submersion 

using DCF from EPA-FGR-12

10 h in March – April 1956 submersion 

using DCF from EPA-FGR-12 

Direct Storage

500 h per year 

Battelle-TBD-6000

1m dose rate

190 h in March – April 1956

MCNP modeling for dose rate at 1m

Post-rolling

2000 h per year submersion 

and direct exposure using 

DCF from EPA-FGR-12

Remainder of 1956 and all of 1957 

submersion and direct exposure using 

DCF from EPA-FGR-12

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NIOSH Responses to the SC&A Review of 

the SEC-00247 ER
Finding 1: Failure to justify process similarities that 

support the use of the Vulcan Crucible billing rate

 Internal Dose (and External Dose)

 Exposure Time, specific to rolling hours

– Vulcan Crucible billing rate of $132 per mill-hour

– Superior Steel Co. contract payment for 1957 of $54,632

– 414 mill-hours → 500 hours rolling exposure

 NIOSH Response

– Evaluated the billing rate via the 5 criteria in the NIOSH 

Implementation Guide “The Use of Data from Other Facilities in the 

Completion of Dose Reconstructions Under the Energy Employees 

Occupational Illness Compensation Program Act” (OCAS-IG-004)

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Finding 1: Vulcan Crucible billing rate (cont.)

 NIOSH Response (cont.)

• Source Term: Both rolled uranium billets

• Facility and Process Similarities: Both similar processes and timing

• Temporal Considerations: Vulcan billing rate from 1948

• Data Evaluation:

– Simonds Saw and Steel- $110.53 per rolling hour 

– Joslyn- $450 per rolling hour for different process

– Joslyn- $88.03 per hour ($0.11 per pound) never implemented

– Superior Steel Co.- $1.01 per pound 

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Finding 1: Vulcan Crucible billing rate (cont.)

 NIOSH Response (cont.)

• Review of Bounding Scenario:

– Compilation of Rolling Information in Table 7-1 yields about 

60h per year rolling exposure

– Modification #5 to the Superior Steel Co. contract yields about 

510h for the entire contract 

» additional assumptions of (1) weight of slabs and (2) # of 

slabs rolled per day or year

– NIOSH stands by the use of the Vulcan Crucible billing rate to 

determine the number of rolling hours

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Finding 2: 1955 survey distributions may not bound air 

concentrations

 Internal Dose

 Intake Rate based on results of the 4 HASL air sampling campaigns

– 2 intake rates: 1953 data and 1955 data

 NIOSH Response

– Performed hypothesis testing on datasets

– May 1955 data not from the same distribution as the other three 

datasets (visually it is lower)

– Remove May 1955 data and use the other 3 datasets to determine the 

intake rate for the entire exposure period

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Observation 1: New approach to bounding source 

term based on contract billing in combination with 

another site’s billing rate

 Internal Dose (and External Dose)

 Exposure Time, specific to rolling hours

– Vulcan Crucible billing rate used to calculate number of uranium 

rolling hours

 NIOSH Response

– Clarified the billing rate isn’t used for source term assumptions

– Source term is Uranium slabs (natural and enriched)

• Based on the AEC contract and AEC process documents

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Observation 2: One-to-one Thorium-to-Uranium ratio 

for calculation of Thorium air concentration 

inconsistent with precedent of 10% used in past ERs

 Internal Dose

 Thorium Intake Rate based on uranium air sample mass loading

 NIOSH Response

– Bridgeport Brass

• Thorium intake rates equal 10% of the Uranium intake rates

• Uranium and Thorium rolled concurrently

• Air sampling results include contributions from both Uranium and 

Thorium

– Superior Steel air sampling only performed during Uranium work

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Observation 3: Uranium storage time assumption is 

inadequate to capture length of time material was 

likely on-site

 External Dose

 Exposure Time, specific to storage of material on-site

– 500 hours per year of exposure from material storage

 NIOSH Response

– Given petitioners’ comments and review of applicable reference 

documents, change to year-round minus rolling time for the entire 

operational period

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Observation 4: Annual medical examination 

assumption in spite of evidence may be inconsistent

 Occupational Medical Dose

 Assign pre-employment, annual, and termination PA chest X-ray doses

 NIOSH Response

– Default assumption from ORAUT-OTIB-0006 when evidence is lacking

– Default assumption from ORAUT-OTIB-0079 when evidence is lacking

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