ASSESSMENT OF THE ENVIRONMENTAL-IMPACT FROM TRITIUM RELEASES UNDER NORMAL OPERATION CONDITIONS AND AFTER ACCIDENTS

In view of the public acceptance and the licensing procedure of projected fusion reactors, the release of tritium during normal operation as well as after accidents is a significant safety aspect. Tritium, being chemically identical to hydrogen and thus interacting directly with water and organic substances, differs considerably from the behaviour of other radionuclides in the environment. Therefore, the two consequence UFOTRI and NORMTRI have been applied to estimate the doses to the public from releases of tritium under accidental respectively. In the frame of ITER (International Thermonuclear Experimental Reactor) and SEAFP (Safety and Environmental Aspects of Fusion Power) the dose/release translation has been determined for typical and various worst case release scenarios. Under worst case accidental release conditions, the dose/release translation for the early dose to an individual at the fence may range from 0.5 to 1 mSv/g HTO. The result for the EDE at the fence is up to 3 mSv/g HTO. The collective accidental dose/release translation is about 2.5 manSv/g HTO. However, due to processes inside the facility, only a small fraction of the mobilised activity may be released into the environment. Finally, the current status of the present assessment models is shortly analysed with regard to the strength and weakness of their approaches which led to the recommendation to concentrate on the plant physiological parts of the tritium codes.