Re: Estimate DAC [Resuspension factor]

[Duane Schmidt <DWS2@nrc.gov>]

On 6/11/97, Paul Ruhter wrote to RADSAFE about resuspension factors
measurements that had been performed at the TMI-2 facility in the recovery work for
that facility. 

I am currently involved, with others at the Nuclear Regulatory Commission (NRC), in
work which could benefit greatly from access to data of the type that Paul described. 

As many of you know, the NRC is in the process of developing a rule on radiological
criteria for decommissioning of licensed facilities. In support of the rule, the NRC is
developing screening-level dose assessment models, which will be used to show
compliance with the dose criteria of the decommissioning rule. A few scenarios are
considered in these models, but the resuspension data may have applicability to
dose estimates for contaminated buildings and surfaces. 

For contamination remaining on surfaces, the model uses the resuspension factor
approach for estimating air concentrations from surface concentrations (the
resuspension factor is concentration in air [Bq/m^3 or similar] per surface
concentration [Bq/m^2 or similar], so the units are per meter, or similar). In searching
for parameter values to use for INDOOR resuspension factors, the NRC and its
contractor have found very few published studies with measured data. Most studies
located have involved OUTDOOR resuspension, generally from soil, which is not
really applicable to indoor surfaces. With very few studies to go on, the development
of default valus of the indoor resuspension factor is quite difficult, and there is
considerable uncertainty involved. Thus, any additional data on resuspension factors
in indoor environments would be quite useful to the work we are doing. 

If Paul or any other RADSAFER has access to data on resuspension factors,
including in the form of unpublished or internal reports, that you would be willing to
share, we would appreciate help in obtaining this kind of data. Though I am not the
project leader on this work, I am involved, and you should feel free to contact me
about this.

Thanks for any help.

Duane W. Schmidt
U.S. Nuclear Regulatory Commission
e-mail: dws2@nrc.gov