A sensitivity analysis of thermal lattices kinetic parameters with respect to the spectral weighting function using ultrafine B-N method

作者：Fallah Vahid Farhang; Salehi Ali Akbar; Vosoughi Naser^*; Ayyoubzadeh Seyed Mohsen

来源：Progress in Nuclear Energy, 2016, 88: 310-320.

DOI：10.1016/j.pnucene.2016.01.016

• Point kinetic equations
• Thermal lattice
• Multigroup approach
• Adjoint spectrum
• Ultrafine B-N method
• NJOY data processing

Accurate calculation of kinetic parameters is of utmost importance in the safety analysis of a nuclear reactor. In the current paper, two approaches are investigated to evaluate these parameters in energy phase space. In the first approach, these parameters are derived from an energy-continuous form of the forward and adjoint transport equations and then integrals with respect to the energy variable are replaced by weighted summations over the energy groups, while in the second approach these parameters are extracted from the multi-group forward equation and its associate adjoint equation in which their multigroup constants are weighted by forward spectrum. The difference of weighting functions in these two approaches would naturally lead to different values for the kinetic parameters. This paper mainly compares the outcome of these two approaches in calculating kinetic parameters for two main types of thermal critical lattices: Mixed Oxide (MOX) and Uranium Oxide (UOX) using ultrafine B-N method. The results show that calculations which are based on using the forward weighted spectrum for generating the kinetic parameters underestimate prompt neutron generation time in both thermal lattices, while effective delayed neutron fraction is overestimated in UOX thermal lattice and underestimated in MOX one.

• 出版日期2016-4