Sensitivity studies on cross-section generation and modeling for BWR core simulation using SAPHYR code system

The work presented in this report is a part of cooperative project between Pennsylvania State Univ. and CEA-Saclay. The objective of the project is to establish an accurate and efficient scheme for BWR core calculation with coupled codes of the SAPHYR system and validate this methodology against the available experimental data. The project is divided into three stages and uses as reference design the Peach Bottom 2 plant. The Peach Bottom 2 plant was selected as a reference design because of the available measured data at different conditions, which allows us to validate both cycle and transient calculation capabilities of SAPHYR. In the first stage of the project, the main focus is on performing studies to implement and validate cross-section generation and modeling methodology for boiling water reactor in order to identify and address the major sources of modeling assumptions in this process. The second stage involves studies on core-calculations with coupled 3D neutronics/thermal-hydraulic models and the relevant issues to obtain an optimal representation in terms of accuracy and efficiency. The third stage will focus on the validation of the coupled calculation scheme against the available experimental data. This paper presents the methodology for BWR assembly calculation with SAPHYR code system and shows results from performed sensitivity studies on cross-section modeling. (authors)