Environmental radiation measurements at the former Soviet Union's Semipalatinsk nuclear test site and surrounding villages

摘要

Two scientists from the U.S. Department of Energy's Environmental Measurements Laboratory served as scientific experts to the International Atomic Energy Agency's (IAEA) Mission to Kazakhstan: Strengthening Radiation and Nuclear Safety Infrastructures in Countries of the former USSR, Special Task - Preassessment of the radiological situation in the Semipalatinsk and western areas of Kazakhstan. The former Soviet Union's largest nuclear test site was located near Semipalatinsk, Kazakhstan, and following Kazakhstan's independence, the IAEA committed to studying the environmental contamination and the resulting radiation exposure risk to the population due to 346 underground, 87 atmospheric and 26 surface nuclear detonations performed at the site between 1949 and 1989. As part of an 11-member team, environmental radiation measurements were performed during 2 weeks in July 1994. Approximately 30 sites were visited both within the boundaries of the Semipalatinsk nuclear test site as well as in and around surrounding villages. Specifically, the objectives of the EML team were to apply independent methods and equipment to assess potential current radiation exposures to the population. Towards this end, the EML scientists collected in-situ gamma-ray spectra, performed external gamma dose rate measurements using pressurized ionization chambers, and collected soil samples in order to estimate the inventory and to determine the depth distribution of radionuclides of interest. With the exception of an area near an 'atomic lake' and a 1 km(sup 2) area encompassing ground zero, all the areas visited by the team had external dose rates that were within typical environmental levels. The measurements taken within a 15 km radius of ground zero had elevated levels of (sup 137)Cs as well as the activation products (sup 152)Eu and (sup 60)Co, The dose rate within a 1 km radius of ground zero ranged from 500 to 30000 nGy h(sup -1).