The retained deuterium inventory in JET and implications for tritium operation

Abstract Deuterium is found all over the interior surfaces of JET, at areal densities of up to 10 22 atoms m −2 . From all the analyses carried out on samples removed after each operational campaign, maps of the distribution of deuterium retained in the vessel and estimates of the total deuterium inventory can be obtained. Results from the operational periods 1985, 1986 and June-August 1987 are compared and show that the amount and pattern of retention has changed markedly. In particular the percentage retention has increased from ~ 4% in 1985/6 to ~ 40% or more in 1987, following installation of belt limiters and greatly increased areas of graphite wall tiles. The retention has implications for future tritium operations, and some of the retained gas is released on venting the vessel.