The necessity for environmental surveillance in the evaluation of nuclear power plant sites

In order to determine the suitability of a particular site for a nuclear power plant, the potential radiological burden to the surrounding population must be predicted to ensure that the radiological protection guidelines will not be exceeded when the plant is in operation. In the Federal Republic of Germany, however, the necessary information for such predictions is often known only on a 'global' basis. Although conservative values have generally been assumed for prediction purposes, their use does not guarantee adherence to the guidelines in all situations, especially where environmental transport of 131I over the pasture-cow-milk pathway is concerned. This problem is, therefore, studied for typical topographical conditions found in the Federal Republic of Germany. The influences of the meteorological, topographical and ecological conditions on the potential radiological burden are studied in detail, and critical conditions that have to be considered when determining the need for environmental surveillance are classified accordingly. In addition, the locations where pre-operational and operational environmental monitoring are necessary are discussed, referring also to the use of biological samples as indicators of potential radiation burdens and environmental contamination. Considering the restrictive dose rate guideline of 90 mrem/a to the thyroid, the necessity of environmental surveillance is confirmed for those sites located in mountain-valley complexes or near large bodies of water, or for facilities equipped with short stacks. Because of the possibility of environmental accumulation of long-lived isotopes as a result of future growth of the nuclear industry, environmental surveillance would prove useful for all sites. Finally, to illustrate the need for environmental surveillance when site-specific information is not available, an example of a site located in a mountain-valley complex has been included. (author)