Abstract
Tritium is one of the naturally occurring radionuclides and distributed widely in the environment. A huge amount of tritium is planned to use in a nuclear fusion facility, therefore the environmental and biological impact becomes an important issue. In the WS, tritium inventory and confinement technology in the nuclear fusion facility and present environmental and biological knowledge will be addressed. The WS is composed of 5 topics which are 1) the outline of the nuclear fusion facility, 2) recent environmental tritium level, 3) environmental modeling, 4) recent studies on biological effects of tritium, and 5) the mutagenic and apoptotic effects on mice. The tritium in the nuclear fusion facility will become the largest amount we have ever experienced and then scientific knowledge leading to safety management of the nuclear fusion facility is required on confinement technology as well as biological and environmental aspects.