Ground-based Air-sampling Measurements Near the Nevada Test Site After Atmospheric Nuclear Tests

Abstract

Historical air-sampling data measured within 320 km (200 mi) of the Nevada Test Site (NTS) have been reviewed for periods following atmospheric nuclear tests, primarily in the 1950s. These data come mostly from high-volume air samplers, with some from cascade-impactor samplers. Measurements considered here are for beta radiation from gross fission products. The resulting air-quality data base is comprised of almost 13,000 samples from 42 sampling locations downwind of the NTS. In order to compile an accurate air-quality data base for use in estimating exposure via inhalation, raw data values were sought where possible, and the required calculations were performed on a computer with state-of-the-art algorithms. The data-processing procedures consisted of (1) entry and error checking of historical data; (2) determination of appropriate background values, air-sampling volumes, and net air concentrations; and (3) calculation of integrated air concentration (C) for each sample (considering fallout arrival times). Comparing C values for collocated high-volume and cascade-impactor samplers during the Upshot-Knothole series showed similar lognormal distributions, but with a geometric mean C for cascade impactors about half that for the high-volume air samplers. Overall, the uncertainty in C values is about a factor of three. In the past, it has been assumed that C could be related to ground deposition by a constant having units of velocity. In our data bases, simultaneous measurements of air concentration and ground deposition at the same locations were not related by a constant; indeed, there was a great amount of scatter. This suggests that the relationship between C and ground deposition in this situation is too complex to be treated adequately by simple approaches.

A Methodology for Calculation of Internal Dose Following Exposure to Radioactive Fallout from the Detonation of a Nuclear Fission Device

“…Based on data derived from measurements on pasture-type vegetation by Lindberg et al (1959) and Romney et al (1963), 19 a more appropriate value of 0.39 m 2 kg −1 was derived by Whicker and Kirchner (1987) for dry fallout. The smaller value of μ observed following the tests of nuclear weapons is most likely due to larger sizes of particles in NTS fallout (Cederwall et al 1990) as compared to the small droplets and particles or vapors examined by Chamberlain. Almost all measurements of the retention of fallout downwind of the NTS discussed in this paragraph were separated according to total fallout and fallout associated with particles of physical diameter < 44 μm.…”

“…The ORERP did not develop a general methodology of calculating dose from inhalation, except where measurements of airborne radionuclides had been made (Cederwall et al 1990; Ng et al 1990). ORERP investigators tried to find a general relationship between airborne concentrations and ground deposition but were not successful.…”

Derivation of Effective Resuspension Factors in Scenarios for Inhalation Exposure Involving Resuspension of Previously Deposited Fallout by Nuclear Detonations at Nevada Test Site

“…Data on particle-size distributions of activity in fallout discussed above were obtained at NTS or at off-site locations within about 20 miles of ground zero of a detonation. Data on particle-size distributions of activity in off-site fallout at locations farther from NTS, such as data reported by Larson et al (1966) and Cederwall et al (1990), also could be considered. However, those data are of limited relevance to our analysis when a much higher fraction of the activity in off-site fallout was attached to smaller, inhalable particles, compared with on-site fallout, due primarily to the pronounced decrease in fall times to Earth with increasing particle size.…”

Inventory and distribution of residual 137cs on and near the Nevada Test Site

“…Between 1980 and 1985, all of the available data on fallout from the NTS were reanalyzed as part of the ORERP (Beck 1984;Anspaugh et al 1990;Beck et al 1990;Cederwall et al 1990;Church et al 1990;Quinn 1990;Ward and Whicker 1990;Whicker et al 1990;Beck and Anspaugh 1991;Grossman and Thompson 1993;Thompson et al 1994 The strategy adopted for the RIDP combined three methods: Aerial surveys, soil-sample collection and analysis, and field-gamma-ray spectrometry. The aerial surveys, carried out with an array of scintillation detectors mounted on a helicopter, showed overall distribution patterns but were not useful for quantifying individual radionuclides.…”