Evaluation of soil radioactivity data from the Nevada Test Site

Abstract

Since 1951, 933 nuclear tests have been conducted at the Nevada Test Site (NTS) and test areas on the adjacent Tonopah Test Range (TTR) and Nellis Air Force Range (NAFR). Until the early 1960s. the majority of tests were atmospheric, involving detonation of nuclear explosive devices on the ground or on a tower, suspended from a balloon or dropped from an airplane. Since the signing of the Limited Test Ban Treaty in 1963, most tests have been conducted underground, although several shallow subsurface tests took place between 1962 and 1968. As a result of the aboveground and near-surface nuclear explosions, as well as ventings of underground tests, destruction of nuclear devices with conventional explosives, and nuclear-rocket engine tests, the surface soil on portions of the NTS has been contaminated with radionuclides. Relatively little consideration was given to the environmental effects of nuclear testing during the first two decades of operations at the NTS. Since the early 1970s, however, increasingly strict environmental regulations have forced greater attention to be given to contamination problems at the site and how to remediate them. One key element in the current environmental restoration program at the NTS is determining the amount and extent of radioactivity in the surface soil. The general distribution of soil radioactivity on the NTS is already well known as a result of several programs carried out in the 1970s and 1980s. However, questions have been raised as to whether the data from those earlier studies are suitable for use in the current environmental assessments and risk analyses. The primary purpose of this preliminary data review is to determine to what extent the historical data collected at the NTS can be used in the characterization/remediation process.