A fundamental characteristic of V.C.H.P. for JMTR capsule

When a high dose is required within a short time, irradiation specimens are loaded in a high neutron flux position in the Japan Materials Testing Reactor (JMTR). Consequently, the temperature of the irradiation specimens is increased above 500 deg C by gamma heating. In order to investigate the posibility of low temperature irradiation in high neutron flux position, a capsule equipped with a variable conductance heat pipe (V.C.H.P.) for heat removal and temperature control was tested in out-of-pile condition. This paper reports the results of experiments and analysis on the out-of-pile test of V.C.H.P.. It is clear that the ability of the V.C.H.P. depends on the position of a evaporator part. (author)