A macroscopic cross-section model for BWR pin-by-pin core analysis

Abstract

A macroscopic cross-section model used in boiling water reactor (BWR) pin-by-pin core analysis is studied. In the pin-by-pin core calculation method, pin-cell averaged cross sections are calculated for many combinations of core state and depletion history variables and are tabulated prior to core calculations. Variations of cross sections in a core simulator are caused by two different phenomena (i.e. instantaneous and history effects). We treat them through the core state variables and the exposure-averaged core state variables, respectively. Furthermore, the cross-term effect among the core state and the depletion history variables is considered. In order to confirm the calculation accuracy and discuss the treatment of the cross-term effect, the k-infinity and the pin-by-pin fission rate distributions in a single fuel assembly geometry are compared. Some cross-term effects could be negligible since the impacts of them are sufficiently small. However, the cross-term effects among the control rod history (or the void history) and other variables have large impacts; thus, the consideration of them is crucial. The present macroscopic cross-section model, which considers such dominant cross-term effects, well reproduces the reference results and can be a candidate in practical applications for BWR pin-by-pin core analysis on the normal operations.

Application of Quick Subchannel Analysis Method for Three-Dimensional Pin-by-Pin BWR Core Calculations

“…As shown in Fig. 1, the subchannels in the region adjacent to the channel box and water rod, i.e., regions (1), (2), and (5), were narrower than those in the other regions. Thus, the void fraction reduced in these narrow regions.…”

“…Note that the void distribution of SUBARU TH was normalized by Eq. (2). In this section, no coupled neutronics/thermalhydraulics analysis is carried out.…”

“…1) Pin-by-pin fine mesh calculation in a three-dimensional geometry 2) Multigroup treatment 3) Based on the SP3 transport theory 3) 4) Response matrix method using partial currents 5) Capability to treat a staggered mesh 4) 6) Semianalytic nodal method with a flat source and leakage approximations in the radial direction 5) 7) Scattered source subtraction (SSS) method 6) to reduce the spatial discretization error in the radial direction 8) Semianalytic nodal method with a second-order source and leakage approximations in the axial direction 7) 9) Acceleration by the generalized coarse mesh rebalance (GCMR) method 8) 10) Treatment of assembly rotation In the burnup calculation, a macroscopic cross-sectional model for the pin-by-pin BWR core analysis has been investigated. 2) Furthermore, a theoretical approach to establishing the energy group structure has been studied. 9) As described above, the pin-by-pin BWR core analysis has been investigated from the viewpoint of performing transport and burnup calculations.…”

“…In our previous study, the applicabilities of the transport 1) and burnup calculations 2) were primarily investigated. In the transport calculation, a three-dimensional pin-by-pin neutronics core analysis code was developed.…”

Generación de librerías optimizadas con cuantificación de incertidumbres para cálculos realistas (BEPU) de reactores nucleares de agua ligera

“…Por ejemplo, [127] y [44] utilizan un desarrollo en serie de Taylor de segundo orden en las secciones eficaces para reactores del tipo RBMK y BWR respectivamente. La desventaja de este modelo es que su validez se restringe a puntos cercanos a las condiciones nominales, por lo que su empleo en escenarios accidentales no es posible.…”