Research on accelerator driven systems at the National Academy of Sciences of Belarus

Investigations in the field of nuclear physics, development of numerical calculation methods for nuclear reactors, neutron physics etc. are being carried out at the Joint Institute for Power and Nuclear Research-Sosny of the National Academy of Sciences of Belarus (JIPNR 'Sosny') since the 60s after putting into operation the research reactor and the critical assemblies. A wide range of different configuration (geometry,composition) of critical assemblies have been constructed at the NAS of Belarus during 25 years of studying of neutronics of the special purpose (fast and thermal) reactors. Later the research in the field of relativistic nuclear physics, the development of calculation methods of interaction of high energy particles and nuclei with fissile media and evaluation of nuclear data of fissile nuclides for Th-U and U-Pu fuel cycle were started. At present the research of physics of the subcritical systems driven by high energy accelerators intended for energy production and transmutation of long-lived fission products and minor actinides are carried out in STC 'Sosny' in the following main directions: - evaluation of nuclear data for nuclides of Th-U and U-Pu fuel cycle; - nuclear model theory and code's development for high energy nuclear data evaluation; - development of the calculation methods for ADS; - experimental investigation of neutronics of subcritical systems driven by high energy particles accelerators, - experimental investigation of high energy protons interactions with extended heavy metal targets (leakage neutron energy spectrum, neutron yields, spallation products etc.). Evaluation of actinide nuclear data are being performed on the basis of different sophisticated nuclear models: coupled-channel optical model, evaporation statistical model with pre-equilibrium emission of first neutron and statistical model with systematics of level density parameters. Nuclear data for 233-U, 242-Cm, 244-Cm, 235-U, 240-Pu, 239-Pu, 236-U, 241-Pu were evaluated and now files are the part of the BROND-2 library (CJD, Obninsk, Russia). In the framework of the ISTC project the files of evaluated neutron data for 243-Cm, 245-Cm, 246-Cm, 241-Am, 243-Am, 242-mAm, 242-gAm, 238-Pu, 242-Pu, 238-Np were created. Code SONET being developed for many years at the NAS of Belarus is dedicated to Monte Carlo simulation of intra- and inter-nuclear cascades in thick targets of arbitrary geometric configuration and material composition. It allows to calculate transport of nuclei (A<16), nucleons and pions in the energy range up to 10 GeV, to describe nuclear collision products by means of cascade-exciton model and provides complete descriptions of low (En < 10-20 MeV) energy neutrons produced in high energy spallation reactions. Further low energy neutron transport is described by means of methods developed for radiation shielding and nuclear reactor physics calculations. One of the versions of code SONET allows to calculate time evolution of nucleon-meson cascade that is of interest when considering external pulse sources. Experimental research in the field of ADS technology is being carried out on the basis of sub-critical assembly driven by high intensity DT and DD neutron generator. The facility allows to study the physics of multiplying media with thermal neutron spectrum at different sub-criticality levels in wide range of core configurations (geometry, composition) and external neutron sources (Cf-252, D(d,n)He-3, D(T,n)He-4. To investigate the dynamics features of the subcritical systems pulse neutron beam with duration from 0.5 μs up to 100 μs and pulse repetition from 1 Hz to 10000 Hz can be used. Further investigation carried out at the National Academy of Sciences of Belarus in the field of ADS-physics will be performed in the framework of strategy of booster sub-critical systems driven by neutron generator NG-12-1. The facility will be put into operation by the end of 2004. The basic idea of fast neutron spectrum booster coupled one way to a thermal neutron spectrum system is well known and consists in enhancement of spallation neutrons source importance by placing a booster around the source located at the core center with main sub-critical thermal spectrum part of the core surrounding the booster. Booster is intended for multiplication of the number of neutrons formed in inelastic interactions of neutron beam with lead target. With this purpose booster is arranged of highly enriched metallic and dioxide uranium fuel (90% and 36% enrichment by 235-U)