Abstract
Silicon cross-sections, being important for a criticality safety of final spent fuel disposals, were recently reevaluated within the IAEA INDEN project. Similarly, the thermal Scattering Law matrix for silicon dioxide, which is also important for criticality safety, was also reevaluated in the ENDF/B-VIII.0 library. Due to these reasons, a series of validation experiments with silica sand were performed at the LR-0 reactor. This paper describes these validation experiments, which used two different amounts of silica sand placed in the core. The first part of validation was carried out as critical experiments in order to benefit from the suitability of integral experiments for validation. The second part -fast neutron spectrum measurement in the sand -was performed in order to obtain knowledge of its characteristics and its agreement with a calculation. The results showed significant improvement of the Thermal Scattering Law matrix for silicon dioxide available in the ENDF/B-VIII.0 library. They also showed that the new INDEN evaluation of silicon cross-sections, together with its description in the ENDF/B-VIII.0 gives disagreement rate closest to the experiments carried out without silica sand insertions. The spectrum measurement showed that the calculations of fast neutron spectra in the sand show only slight differences between different evaluations of silicon cross-sections. However, the fast neutron spectrum is not dependent on the Thermal Scattering Law. The calculated spectra show relatively good agreement with the measurement.
Highlights
Despite the fact that the silicon is not substantially present in the present reactors, it can be assumed as important nuclide from the point of view of criticality safety
It is necessary to take into account criticality safety, and one postulated accident is the burial of the reactor in the sand [1]
It is apparent that the large experiment has a larger bias. This bias is most likely caused by modeling simplifications and 234U content, which is neglected in the benchmark model
Summary
Despite the fact that the silicon is not substantially present in the present reactors, it can be assumed as important nuclide from the point of view of criticality safety. Silicon is irradiated in the reactor (silicon doping), or it is considered as material for fuel cladding (in the form of silicon carbide) Besides these facts, there are repeated discussions about the use of nuclear reactors in space. There are repeated discussions about the use of nuclear reactors in space Even in this case, it is necessary to take into account criticality safety, and one postulated accident is the burial of the reactor in the sand [1]. It is necessary to take into account criticality safety, and one postulated accident is the burial of the reactor in the sand [1] Due to these reasons, silicon and its compounds are important materials for the nuclear industry, which means that it is important to know its properties properly
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