Perspectives on nuclear data for advanced reactor design and analysis

Abstract

Nuclear reaction cross section and other neutron physics data are basic inputs to reactor design and analysis. The physical constants such as reaction cross section and other physical constants are usually generated in labs with neutrons as probes, are then coded and subject to detailed evaluation and qualification and finally are made ready for use for potential reactor applications. The nuclear data measurement requires cutting edge technologies from generation of mono-energetic source of neutrons to developing pure targets and covering the entire range of neutron energies and reaction channels. The evaluated data which are created from a best fit of several experiments are then processed to a reactor-specific dataset which again is a multi-parametric and required different treatment in different energy regimes and is also for different target isotopes. The life cycle of these physical constants from lab to the user is very large, sometimes spans over a few decades. This field of nuclear data physics, which entails multi-physics covering the entire gamut from experiments to processing, is an exciting branch of reactor design. This paper attempts to give an overview of the importance of these cross-section data for design studies, safety and operation of reactors. Emphasis is mainly in the condensed nuclear datasets used of design simulations. Advanced reactor designs use newer materials, are optimized for better fuel utilization and are required to model more complex phenomenon. All these require that the uncertainties in the basic nuclear data be minimized. The deviations in core parameters due to the variations in basic nuclear cross sections are estimated as sensitivity or uncertainty coefficient, which are then accounted for in the design margins. This paper will cover the various aspects of the nuclear data, i.e., experiments to reactor-specific data, its use in reactors, the influence on operational parameters and sensitivity studies.