Abstract
To meet the requirements of one step lattice calculation on resonance effect, a self-developed design and construction of a resonance treatment code are composed based on subgroup method and HELIOS-1.11 library. Subgroup fixed source equations are solved by method of characteristics to get subgroup fluxes, which are subsequently used to deduce effective resonance cross sections combined with subgroup weights and subgroup levels. Bondarenko method is employed to handle resonance interference effect and a resonance category scheme and resonance geometry simplification method are introduced to improve efficiency. Benchmarks of single pin cells and assemblies of light water reactor are adopted for numerical validation and the calculating results indicate that this method can treat resonance effect both precisely and effectively.
Highlights
In traditional lattice physics codes, the three-step method and pin-by-pin method are widely used in light water reactor calculation (Cacuci, 2010)
Subgroup method based on HELIOS−1.11 library is adopted to develop the resonance calculating code in this work, which is capable to satisfy the requirement for resonance treatment in one-step reactor lattice physics calculation
This method could be combined with the transport module for arbitrary geometry to get subgroup fluxes for effective cross sections deduction
Summary
In traditional lattice physics codes, the three-step method and pin-by-pin method are widely used in light water reactor calculation (Cacuci, 2010). Traditional methods for resonance treatment are equivalent method (Askew et al, 1965; Zhang et al, 2015), which is based on the equivalence between heterogeneous and homogenous problems and the ultra-fine group method with extremely detailed division of groups (Ishiguro and Takano, 1971) The former method has good efficiency but shows obvious drawbacks in accuracy and geometry adaptability, while the latter one has a satisfactory accuracy, it’s hard to be applied to lattice scale problems since the calculating burden is unacceptable. It can be seen that SGFSP and resonance interference effect treatment occupy the most calculating time so optimizing method has been taken in this work to improve efficiency In this case, we use a smaller number of subgroups in SGFSP for simplification while a larger number of subgroups in deducing effective cross section to ensure accuracy, and an extrapolation of relevant data obtained by SGFSP is used between these two set of subgroups. The independent design and construction of a completed lattice physics analyze code is realized
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