Comparison of Updated NIOSH and SC&A Exposure Assessments at GSI 

Robert Anigstein
 

S. Cohen & Associates
 

October 11, 2013
 
PERIODS OF SITE OPERATIONS,
 

DIVIDED ACCORDING TO LIMITING EXPOSURE SCENARIOS
 

• October 1, 1952: 	 Start of covered operations under EEOICPA 

o Two 500-mCi 226Ra sources used for radiography, in addition to 24-MeV betatron (“Old Betatron”) 

• May 21, 1962: GSI acquires two 60Co sources (260 and 280 mCi) to replace 226Ra 

•	 October 1, 1963: Assumed date “New Betatron” began operation at Commonwealth foundry in Granite 

City; Old Betatron upgraded to 25 MeV 

• June 30, 1966: End date of last MCW purchase order—beginning of residual period 
BOUNDING SOURCES OF EXTERNAL RADIATION EXPOSURE AT GSI 

(Entire period of AEC operations, unless otherwise noted) 

• Exposure to sealed radiography sources 

o 226Ra—2 sources, 500 mCi ea: October 1, 1952 to May 21, 1962 

• Exposure to direct penetrating radiation (photons + neutrons) from betatron operations 

o Stray radiation during betatron operation 

o Delayed radiation from activated metals 

• Exposure of skin to non-penetrating (beta) radiation 

o Natural uranium and photoactivated uranium isotopes 

o Activated steel 
BOUNDING EXTERNAL EXPOSURES OF NONADMINISTRATIVE PERSONNEL
 

(OPERATIONAL PERIOD)
 

Radium Era: Exposure to Penetrating (Photon) Radiation 

Dose/exposure Years 

Bounding scenario 

SC&A & NIOSH NIOSH SC&A 

6.279–9.69–15 rem* 1952–1957 1952–1960† 

Radiographer 

using Ra-226 6.279–9.69–12 rem* 1958–1963 1961–1962† 

* Triangular distribution–as per W-G meeting 2/21/2013 

† Revised dates, based on date of revised AEC rule 

New Betatron Building in Operation 

Bounding scenario Years Photon exposure Neutron dose (rem) 

Layout man 

SC&A NIOSH SC&A (R) NIOSH (rem) SC&A NIOSH 

1963-1966 1964-1966 9.20 4.483 0.46 0.148 
Basis for Disagreement Between SC&A and NIOSH:
 

External Photon Exposure of Layout Man During New Betatron Era
 

•	 NIOSH used 15 betatron scenarios 

o	 45o angle to axis not consistent with industrial radiography 

o	 Arbitrary selection of betatron positions and orientations 

o	 Normalized to 10 mR/week at film-badge storage rack 

• 	 Shielding by outer wall of control room understated due to assumed low density of concrete blocks 

• 	 No shielding by interior walls or equipment 

• 	 Landauer zeroed control badge (No. 000)—doses reported only if 

o	 >50 mrem or 

o	 >1⁄2 of worker badges 

• 	 No information on Badge No. 1: “BETATRON CTL”—may have been in Old Betatron Building 

(location of supervisor’s office) 

o	 Location of layout man on RR track unrealistic and not claimant favorable 

o	 SC&A scenario leads to reasonable upper-bound exposures 

•	 NIOSH included heavy steel door (0.85 in) 

o	 Workers described ribbon door, made of thin sheet metal 
1000 

0 

- 1 noo 

Layout man * 

SC&A Model of Exposure Geometry of Layout Man
 
 

 

 

 

BOUNDING SCENARIOS FOR NEUTRON AND BETA EXPOSURES
 

Year 

Neutron dose (rem/y) â dose to skin—betatron operator (rads/y) 

SC&A 

Betatron operator 

NIOSH 

Layout man 

Hands & forearms 

SC&Aa NIOSHb 

Other skin 

SC&Aa NIOSHb 

1952c-1957 

1958 

1959-1960 

1961 

1962 

1963 

1964 

1965 

1966d 

0.48 

0.48 

0.48 

0.48 

0.48 

0.47 

0.46 

0.46 

0.23 

0.148 

0.072 

33.4 28.5 

32.1 28.5 

30.9 28.5 

34.2 32.0 

27.2 24.5 

13.9 9.9 

10.7 6.4 

10.2 5.9 

4.8 2.7 

6.3 3.90 

6.2 3.90 

6.2 3.90 

6.3 4.07 

6.0 3.71 

5.6 3.00 

5.4 2.84 

5.4 2.81 

2.7 1.39 

a From SC&A White Paper: March 12, 2012 

b From Dave Allen’s White Paper: October 10, 2013 

c Covered period began October 1, 1952 

d Doses prorated to first 6 months 
 

 

 

BOUNDING INTERNAL EXPOSURES: Apply to All Employees


U work hours/year Inhalation dpm/cal. day

Start Date End Date Ä 

SC&A NIOSH SC&A NIOSH 

10/1/52 2/28/58 437.5 337.5 113.09 91.4 24% 

3/1/58 6/30/58 375.0 337.5 98.97 91.4 8% 

7/1/58 6/30/66 SC&A and NIOSH Concur — 

7/1/66 12/31/93 — — 14.3a,b 1.44a,c 890% 

a Exponentially decreasing during residual period, according to OTIB-70
 

b Based on RF = 10-5
 

c Based on RF = 10-6