Slow-positron beamline temperature rise reduction at Kyoto University Research Reactor

[摘要] Temperature rises of a reactor-based slow-positron beamline at Kyoto University Research Reactor (KUR) were measured during reactor operation and solenoid-coil excitation. During KUR operation at 5 MW, the temperature of the top of the beamline reached 300 degrees C. This temperature which is close to the melting point (321 degrees C) of Cd was used to enhance positron generation. On the other hand, the temperature of the flange supporting the beamline was approximately 50 degrees C and it was sufficiently low in terms of the strength of the beamline. The temperature of the top of the beamline was successfully reduced to 240 degrees C by introducing a He gas flow around the vacuum duct of the beamline. Beamline temperatures calculated using a finite element method were in agreement with measured temperatures. Such calculation is useful for future experiments with longer or irregular KUR operation.

[发布日期] 2019-12-15

[关键词] Research reactor;Slow positron beam;Cadmium;Nuclear heating;Thermal conductivity;Helium gas