Decommissioning of nuclear power plants and its effect on the environment

The three basic steps of nuclear power plant decommissioning are discussed. Each of them is characterized by two parameters: the physical state of the plant and its equipment, and the extent of inspections, surveillance and tests that must be performed or ensured in accordance with the physical state. The decommissioning involves two kinds of effort which are contradictory with respect to environmental risk: first, efforts are made to reduce to minimum the amount of radioactive products in the power plant equipment and buildings; this, however, is associated with substantial interventions into the contaminated facilities, which bring about enhanced risk of personnel exposure and radioactivity leaks into the environment. The basic principles are given that must be adhered to in order to protect the surroundings during the decommissioning. Actually, the surroundings and environment can be stressed appreciably by the large amounts of radioactive wastes emerging from the decommissioning activities. The composition of the wastes is diverse. The majority is solid waste, mostly scrap: for the decommissioned A-1 nuclear power plant in Jaslovske Bohunice the total amount of contaminated steel will be about 10 600 t. Liquid wastes are largely consist of spent decontamination solutions. As compared with normal operation, the risk of external irradiation as well as of internal contamination during the disassembling of the technological equipment is higher. In Czechoslovakia, the problem of nuclear power plant decommissioning became topical as early as 1977, after an accident during which a serious fuel element failure gave rise to a marked contamination of the primary and auxiliary circuits. For these reasons, the decommissioning process is very complicated and has not yet been fully solved. Some experience from the decommissioning of the A-1 nuclear power plant is summarized; in this activity, minimization of potential sources of radioactivity leaks into the environment is the issue of prime importance. (Z.S.). 1 tab., 6 refs