Some Features of the Operation of Pelletized Cryogenic Mesitylene-Based Moderators at the IBR-2 Pulsed Fast Reactor

— The radiochemical and neutron-physical characteristics of a pelletized cryogenic moderator based on a mesitylene mixture (a mixture in the form of frozen pellets) obtained during its operation at the pulsed fast reactor IBR-2 are presented. It is shown that changes in the properties of the mixture at high absorbed-irradiation doses (~100 MGy) have no significant effect on the spectrum of cold neutrons. The gain in the number of cold neutrons from the surface of a cold moderator in comparison with a water moderator reaches 10 times. There is no deterioration in the neutron flux at the end of the reactor duty cycle. If the technology of continuous modification of the working substance in the cryogenic moderator chamber is successfully developed, the frozen mixture of mesitylene and m -xylene can be recommended for use on powerful pulsed neutron sources.