Conversion of the RB reactor neutrons by high-enriched uranium fuel and lithium deuteride

A converter of thermal to fast neutrons has been constructed at the RB reactor. The material used for the conversion of thermal neutrons is highly enriched uranium fuel of Soviet production applied in Yugoslav heavy water experimental reactors RA and RB. Calculations and preliminary measurements show that the spectrum of converted neutrons only slightly differs from the fission one. The basic characteristics of converted neutrons can be expressed by the neutron radiation dose of 800 rad (8 Gy) for reactor operation during 1 h at the power level of 1 kW. This dose is approximately 10 times higher than the neutron dose at the same place without converter. At the same time, thermal neutron and gamma radiation doses are negligible. The constructed neutron converter offers wide possibilities for applications in reactor and nuclear physics and similar disciplines, where neutron spectra of high energies are required, as well as in the domain of neutron dosimetry and biological irradiations in homogeneous fields of larger dimensions. We have also considered the possibility to convert thermal reactor neutrons to neutrons of energy 14 MeV by lithium deuteride which is made from natural lithium. (author)