Review of the Resuspension Factor Employed during the Residual
 

Contamination Period at General Steel Industries
 

December 10, 2013 

J.W. Neton 

The selection of the appropriate resuspension factor (RF) to be used during periods of residual 

contamination is discussed in ORAU-OTIB-0070 (Sharfi 2012). Although this document 

-6	 -1 suggests a default value of 10 m during residual periods, in cases where the contaminated area 

is still involved in active operations, it states that a site-by-site analysis of the appropriateness of 

-6	 -1 the 10 m value should be done. In NIOSH’s latest assessment of inhalation doses during the 

-6	 -1 residual period at GSI (i.e., after 6/30/1966) a resuspension factor of 1x10 m was used (Allen 

2013). In a recent review, SC&A questioned the appropriateness of this value and suggested that 

-5	 -1 the use of a value of 10 m would be more appropriate when one considers the conditions in 

existence at the plant during the residual period (Anigstein and Mauro 2013). SC&A’s concerns 

-5 -6 were largely based on the abrupt reduction of the RF value from 10 to 10 , even though the 

facility continued to conduct normal operations during this period. It was argued that the 

potential existed for active disturbance of the residual contamination. 

NIOSH has re-evaluated the RF value during the residual contamination period and now believes 

that a value of 10-5 is more appropriate. The reasons for this determination are: 

1.	 The initial surface contamination value of 1.34×105 dpm/m2 was estimated using
 

modeled values as opposed to having been measured. Thus, there is a degree of
 

uncertainty associated with this value.
 

2.	 There were reports that certain sections of the GSI facility had been cleaned prior to the 

conduct of the FUSRAP contamination surveys. Because of this, the contamination 

depletion factor of 0.00067 d-1 was based on the average value observed at other AWE 

facilities. Thus, there is also some degree of uncertainty associated with this value as 

well. 

3.	 As SC&A pointed out, the facility was actively involved in steel processing activities, 

resulting in the increased potential for the resuspension of particulates. 

Because of the uncertainties in the initial contamination value and the source depletion rate, as 

well as the degree of activity associated with ongoing operations, NIOSH has decided that it 

would be appropriate to use a claimant favorable RF value of 10-5 throughout the entire covered 

period, including that associated with residual contamination. Appendix BB of TBD-6000 will 

be revised to use this value in all dose reconstructions. It should be pointed out that, even though 

the RF was increased by an order of magnitude, there will only be minor increases in internal 

dose. This is because the air concentrations during the residual period were estimated to be very 

-5	 -1 low. For example, using an RF of 10 m , the air concentration at the end of the residual 

contamination period is 2.3×10-3 dpm/m3 . 
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2 

References
 

Allen, D. 2013. “GSI White Paper: Issues Raised in February 21, 2013 Work Group Meeting.” 

http://www.cdc.gov/niosh/ocas/pdfs/dps/dc-gsiwgiss-0413.pdf 

Anigstein, R., and J. Mauro. 2013. “SC&A Response to NIOSH White Paper: ‘Summary Dose 

Estimates for GSI’.” Memo to Advisory Board on Radiation and Worker Health Work Group on 

TBD-6000. http://www.cdc.gov/niosh/ocas/pdfs/abrwh/scarpts/sca-gsisde-100613.pdf 

Sharfi, M. M. 2012. “Dose Reconstruction During Residual Radioactivity Periods at Atomic 

Weapons Employer Facilities,” ORAUT-OTIB-0070, Rev. 01. 

http://www.cdc.gov/niosh/ocas/pdfs/tibs/or-t70-r1.pdf. 

This is a working document prepared by NIOSH or its contractor for use in discussions with the ABRWH or its 

Working Groups or Subcommittees. Draft, preliminary, interim, and White Paper documents are not final NIOSH or 

ABRWH (or their technical support and review contractors) positions unless specifically marked as such. This 

document represents preliminary positions taken on technical issues prepared by NIOSH or its contractor. 

NOTICE: This report has been reviewed to identify and redact any information that is protected by the Privacy Act 5 

USC §552a and has been cleared for distribution.