Defense Threat Reduction Agency

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April 1, 2002

Dr. Isaf Al-Nabulsi

Board on Radiation Effects Research

National Academy of Sciences

2001 Wisconsin Avenue, NW Washington, DC 20007

Dear Dr. Al-Nabulsi:

In response to your 26 February 2002 letter, we provide an explanation of the calculations in the computer printouts for cases 344921 and 201699. We are including the documented method for performing the calculations, its basis, and policy memorandum implementing the method’s use (see enclosed).

The documented method is contained in the attached computer code printout. The codes are what produce the computer printouts contained in your February 2002 letter. The basis for the codes is the National Academy of Sciences (NAS) report of “Film Badge Dosimetry in Atmospheric Nuclear Tests” (1989) (see excerpts enclosed). We implemented the performance of combined uncertainty analysis on multiple film badges in July 1992 (see policy memorandum enclosed). This memorandum implements the combined uncertainty analysis as prescribed in the 1989 NAS film badge study, except for the application of the deep-dose equivalence conversion and the use of 95% confidence intervals. We use the uncorrected film badge readings (factor of 1.0) for determining the total dose vice the deep-dose factor. We do this to preserve a one-to one correlation to the film badge record for the veteran to see evidence that original records are being used in the dose reconstruction and avoid the perception that we are lowering recorded doses. We use a 90% confidence interval vice 95% so that we have a consistent basis for combining the overall film badge reading uncertainty with reconstructed dose uncertainties, compiled and published in historical records at the 90% level.

The code computes the individual entries by selecting the applicable test series by inclusive operation dates. It then selects the bias factors (B) and uncertainty factors (K) for the applicable test series (see computer code printout as annotated). The Band K factors originate from pages 136, 143, and 152 of the 1989 NAS report (excerpts enclosed). They correspond to Operations CASTLE,

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