General Steel Industries (GS

Special Exposure Cohort

David Allen

Dose Reconstruction Health Physics Team Leader

National Institute for Occupational Safety and Health

Division of Compensation Analysis and Support

June 2012

Santa Fe, NM
Background

 General Steel Industries (GSI) was classifie

an Atomic Weapons Employer (AWE) facili

from 1953 to 1966

 Residual contamination period through 19

 Performed radiography examinations of ur

metal using betatrons

 No correction of defects or other manipula

of uranium metal was reported
Sources of Radiation: Intern

 Dust from uranium corrosion

 Dust from activated steel
Sources of Radiation: Extern

 Direct radiation from betatrons Activated steel

 Uranium Radiography with isotopic sources Portable x‐ray machines
Betatrons

 Two betatron buildings on site, new and o

• Old betatron was built in 1952 and was report

have a maximum energy of 24 MeV

• New betatron was moved from Eddystone,

Pennsylvania, to Granite City in 1963 and was

reported to have a maximum energy of 25 Me

 Photon energy was high enough to cause

activation
Betatron Buildings
Activated Steel

 Betatron energy was high enough to cause

activation of steel castings

 MCNP, a computer program, was used to m

this activation using favorable scenarios

• Reported intensity

• Drawings of the aluminum compensator and io

chamber

• Maximum electron energy• Reported distances between betatron and cast
Isotopic Sources

 Two 500 mg Ra‐226 sources until 1962

• Used fishing pole technique to place sources

• Interview with former operator described tech

details

• Sources used both inside a radiography room i

building and throughout the plant
Isotopic Sources—cont.

 Purchased two Co‐60 sources in 1962

• Discontinued use of Ra‐226 at the request of t

of Illinois

• Purchased two Co‐60 sources in 1962

• Sources were 260 mCi and 280 mCi

• Sources were to be used in the radiography ro

• Workers reported sources also used throughou

plant
Isotopic Sources—cont.

 St. Louis Testing

• Contracted to perform some radiography as w

provide other services (instrument calibration

• Used 50 Ci Ir‐192 source and 10 Ci Co‐60 sourc

site at various times

• GSI employees were not involved with radiogr

performed by St. Louis Testing
Other Sources of Radiation

 GSI owned two portable x‐ray machines

• GE OX‐250

• Andrex

 Reports of the frequency and location of u

conflicting

• The few memories of machines indicate infreq

use

• Former supervisor indicated machine was test

when bought and not used again
Data Sources: Film Badges

 Film badge dosimetry from Landauer

• Covers November 1963 through 1972• Only those associated with radiography were i

film badges

• Weekly exchange• Reporting level of 10 mrem

• 99.7% of readings less than reporting level
Data Sources: Film Badges—co

 Prior to 1963, film badges were worn

• Unable to locate reports of film badges

• Information from interviews and pictures of fo

workers show film badges being worn

• One former worker provided a film badge sum

report
Data Sources: NRC

 Co‐petitioner obtained GSI documents from

Nuclear Regulatory Commission (NRC) via 

Freedom of Information Act (FOIA) reques

 Documents mainly licenses and application

licenses and renewals

 License first granted in 1962 prior to purch

Co‐60 sources
Data Sources: NRC—cont.

 Information includes:

• Drawing and radiation surveys of radiography 

• Type and strength of isotopic sources (Ra‐226 

60)

• Sparse information on source utilization and p

exposures

• Detail drawing of new betatron building

• Survey outside new betatron shooting room w

Ci Co‐60 source exposed
Data Sources: Former Worke

 Many workers were interviewed at various 

by various people (Co‐petitioner, NIOSH, S

 Some interviews were group settings and s

individual
Data Sources: Former Workers

 Information includes:

• Work practices when using source outside

radiography room

• Violations of practices both routine and abnor

• Frequency and duration of x‐rays using the bet

• Badge practices including removing film badge 

working outside betatron building
Dose Estimate: Internal

 Uranium modeled using uranium slug

production values from Battelle‐TBD‐6000

• Slug production involved some abrasive work 

GSI did not perform any destructive work on uranium metal

 Dose from uranium fission and activation

products were included in the estimate

 Internal dose from activated castings was

considered by assuming an individualcontinuously ground on a freshly activatecasting
Dose Estimate: External

(Betatrons)

 New Betatron building was modeled in MC

 Model was checked against a 1971 80 Ci Co

source survey

 Building model was then used to determin

rates outside the building when betatron w

operating at various locations and orientat
Dose Estimate: External—cont

(Betatrons)

 Dose rate at the film badge storage locatio

determined for each orientation

 Orientations were chosen based on weekly 

rate at badge rack for each orientationconsistent with the utilization described by operators
Dose Estimate: External—con

(Betatrons)

 Hours per week of each orientation was th

used to determine dose at various location

while betatron was operating

 Dose from steel and uranium after operati

was determined and added to this dose
Dose Estimate: External—cont

(Betatrons)

 Typical durations for x‐rays of steel and ura

were assessed from worker interviews

 Separate dose estimates were derived for 

 The two dose estimates were combined us

uranium work frequencies derived from

purchase orders
Dose Estimate: External

(Layout man)

 Operators often marked castings for upcom

shots outside the betatron building

 When performing this work, film badges w

not worn (kept in the betatron building)

 Exposed to betatron radiation while it was

operating and to activated steel
Dose Estimate: External—cont

(Layout man)

 Dose from betatron determined using wor

location and orientation frequencies previdetermined

 Dose from activated steel determined usin

worst‐case scenario for moving castings inout of the betatron building.
Dose Estimate: External

(Co‐60 sources)

 A 1962 survey around the radiography roo

used in combination with source utilizatio

reported by the Atomic Energy Commissio(AEC)

 Source strength and reported work practic

outside the radiography room were used t

determine that dose

 Highest of the two scenarios to be used
Dose Estimate: External

(Ra‐226 sources)

 Source strength and reported work practic

outside the radiography room were used t

determine that dose

 Assumed radiography room did not exist b

1962

 Information since then indicates it did exis

was routinely used

 Estimate for radiography room was done b

SC&A
Dose Estimate: External

(St. Louis Testing Sources)

 Reported that GSI radiographers did not he

Louis Testing perform radiography

 Estimate based on continuous occupancy a

boundary
Dose Estimate: External

(Portable X‐rays)

 Reported frequency of use was very low

 Qualitative estimate used to estimate dos

would be lower than other potential sourc