Environmental Risk Assessment of Nuclear Excavation Tests: Chagan Underground Nuclear Test at the Semipalatinsk Test Site, Kazakhstan, a Case Study (LNBL-T2-0237-KZ)
Tech Area / Field
- ENV-EHS/Environmental Health and Safety/Environment
- ENV-WPC/Water Pollution and Control/Environment
6 Project underway
Senior Project Manager
National Nuclear Center of the Republic of Kazakstan / Institute of Radiation Safety and Ecology, Kazakstan, Kurchatov
- Japan Atomic Energy Agency / Fukushima Environmental Safety Center, Japan, Fukushima
Project summaryThe Semipalatinsk Test Site (STS) is one of the largest sites for testing nuclear weapons in the world. From 1949 to 1989, the STS was for nuclear tests. The largest contribution to the contamination of the STS was made by surface and excavation explosions, compared with high-altitude nuclear explosions. Capacity of all excavation explosions with soil outburst was over 140 kt, 99% of the power of these explosions is accounted for the blast carried out in Borehole 1004. It was held on January 15, 1965, at the confluence of the Aschisu and Shagan Rivers at a depth of 178 meters. Power of the explosion was 140 kt. The blast led to the release of many long-lived radionuclides: plutonium-239+240 – 8.5 Ci, cesium-137 – 800 Ci; cobalt-60 – 80 Ci; europium-152 – 120 Ci, strontium-90 – 400 Ci, and tritium – 4*105 Ci. 30-40% of the generated radionuclides precipitated in the explosion crater area.
The soil outburst caused by the explosion resulted in a formation of the crater 430 m in diameter crater, with the ] height at the crest of 20-35 m, and a width of crater rim of 400 m. Volume of the visible crater, from the rim was 10,300 thousand m3. Afterward, spring water flooded the crater, causing the formation of two water reservoirs: the internal one in the crater with volume of 7 million m3 and surface areal extent of 0.5 km2, and external one with volume of 10 million m3 and the surface areal extent of 3.5 km2 (hereinafter the system of both internal and external reservoirs is called the "Atomic Lake"). The rock-earth dam, having a bottom discharge and a surface flood spillway, bound the reservoir. The reservoir was the first hydroelectric complex of this kind and was regarded as an experimental hydrotechnical site.
However, due to improper maintenance of the hydraulic structure, unauthorized activities of scrap metal scavengers in the former STS, and blows and failure of the bottom floodgates, leakage of water from the experimental reservoir occurred in 1994. In recent years with relatively warm winters with little precipitation and snow, water flooding was insufficient, so that the water level in the reservoirs significantly dropped, while the exposed surface of the rim increased by 12-15 thousand m2.
Currently, the former bottom surface is being used for grazing livestock, inhabited by the local fauna. The wind erosion of the dried up soil areas may increase the radiation doses (i.e., internal intake of radionuclides) to the people living in the area surrounding the "Atomic Lake." Radiation exposure may also increase to domestic animals and wild populations of plants and animals that inhabit the region, as well as waterfowl (ducks, geese, etc.) due to the increase of radionuclides in plants and sediments in the water.
The use of available data from long-term monitoring at the former STS radioactively contaminated areas as research objects allows scientists to get enough data to assess the impact of nuclear power on the environment. The results of experimental studies are of great interest to international scientific organizations, engaged in resolving problems related to ensuring the safe operation of nuclear power plants, radioactive waste disposal sites. The findings of the comprehensive studies on the radio-ecological situation in the Atomic Lake area will contribute to the development of monitoring systems for radiation-ecological conditions at facilities with elevated radioactive risk.
Goals of the Project are:
- Assessment of the Atomic Lake impact on the ecosystem of the region and artificial reservoir;
- Development of proposals for use of «Atomic Lake» for scientific and industrial purposes.
To achieve these goals, in the first year of the project 4 main tasks to be addressed:
Task 1. Synthesis and analysis of available historical information
Task 2. Development of the GIS structure and specific blocks of the GIS
Task 3. GIS Project Population.
Task 4. Development of recommendations for further use of the Atomic Lake.
The results of the project can be used to assess redistribution of radionuclides in the environment, and to assess radiation exposure arising from other nuclear accidents such as Chernobyl and Fukushima Daiichi and other polluted open water (for example, in the cooling pond of the Chernobyl nuclear power plant in Ukraine, PAR pond in DOE Savannah River, USA).
The project will develop a proposal for the further use of the Atomic Lake for scientific and practical purposes, including the testing of data base management systems (e.g., ASCEM Data Management System) developed by the U.S. Department of Energy, verification and testing the approaches to the assessment of radiation exposure and development of the system for further radiological environmental monitoring.