tions IV.B and IV.C, it is the current policy of the NTPR program to report a central (“best”) estimate of external dose from exposure to photons along with an estimated 95th percentile upper bound, and the same approach has been taken in estimating external dose from exposure to neutrons in dose reconstructions for participant groups. However, only a single estimate of dose is reported when a beta dose to the skin or lens of the eye or an internal dose from intakes of radionuclides is calculated, and this estimate is intended to be at least a 95th percentile upper bound.1
Development of exposure scenarios for participants in the nuclear-weapons testing program involves consideration of assumptions about the locations of the participants of concern, their activities at those locations, and the time spent at each location and assumptions about the radiation environment at the assumed locations of the participants during the time spent at those locations (see Section I.C.2.1). Approaches to development of exposure scenarios used in the NTPR program are described in the standard operating procedures (DTRA, 1997) and in 32 CFR Part 218.
The dose reconstruction process requires that the analyst first determine whether a veteran’s records support his qualifying as a “participant” according to the definition in applicable laws and regulations. In this initial stage, military records are used to confirm that the veteran was present at the Nevada Test Site (NTS) or the Pacific test sites during designated intervals before and after tests of nuclear devices, was present in Hiroshima or Nagasaki during the occupation of Japan, or was a prisoner of war near Hiroshima or Nagasaki at the time of the atomic bombings. The burden of proof in establishing a veteran’s status as a participant is stricter if a veteran’s claim is filed for a presumptive disease under 38 CFR 3.309 than for a nonpresumptive disease under 38 CFR 3.311 (see Section I.B.4).
Once a veteran’s participation status has been confirmed and a dose reconstruction has been requested (usually by the Department of Veterans Affairs [VA] in response to a claim filed for alleged radiogenic health conditions), a government contractor (currently JAYCOR) undertakes extensive historical research based on archival records to reconstruct the movements and activities of the veteran during the period of participation.
An additional concept used in this report to represent the full range of uncertainty in a quantity is the confidence interval. For example, a 90% confidence interval of an uncertain quantity gives the range of values within which the true value should lie in 90% of all cases, and the lower and upper bounds of this confidence interval are the 5th and 95th percentiles, respectively.