Study of fission product release, plate-out and maintenance in helium turbomachinery

A feasibility study of HTGR-GT has been conducted in JAERI, as an assigned work by the Science and Technology Agency in Japan. So far, the conceptual or preliminary designs of 600, 400 and 300 MW(t) power plants have been completed. The block type core and pebble-bed core have been selected in 600 MW(t) and 400/300 MW(t), respectively. In this plant concept, maintenance of turbine rotor is one of the most important issues. This paper describes the results of preliminary estimation of generation in the fuel, release into coolant and plate out on the components of 137 Cs and 110m Ag. In addition, maintenance method of turbine rotor is discussed. (author)