Thermodynamic performance tests of the cold neutron source at the reactor KUR

This report described thermodynamic performance tests of the Kyoto University Reactor (KUR) Cold Neutron Source (CNS), which is operated by a closed thermosiphon cooling loop. Close agreement between observed and numerical simulations of the normal operations of the CNS was obtained. Dynamic factors relating to the time-delay caused by the mass transfer in the moderator transfer tube were not considered in those simulations. The authors conclude that time-delaying phenomena due to pressure and flow oscillations in the line are estimated to be negligible in their CNS. The data of TOF spectra showed that the ratio of the fraction of cold neutrons in the cold moderator to that in the ambient moderator is about 20 where the wavelengths are longer than 6 A using liquid hydrogen as a moderator