CSNI Code Validation Matrix (CCVM) Current Status and Development Needs

Abstract

For Anticipated Operational Occurrences (AOOs), Design Basis Accident (DBA), Beyond Design Basis Accident (BDBA) and Severe Accidents (SAs) as postulated accidents, computer code predictions are relied on nuclear reactor safety analysis. The computer codes are required to go through a rigorous Verification and Validation (V&V) and Uncertainty Quantification (UQ) process. The codes must be validated against data from scaled-down experimental facilities, both Separate-Effect Test Facilities (SETFs) and Integral-Effect Test Facilities (IETFs), to confirm their predictive capability with qualitative and quantitative accuracy. The experiments therefore play a key role to provide the needed knowledge and data. For decades, with internationally recognized experts, OECD/NEA/CSNI/PWG-2 and Working Group on Analysis and Management of Accidents (WGAMA) have taken a key role to identify: 1) Relevant phenomena important for reactor safety analysis; 2) Phenomena occurrence versus experimental facilities in NEA Member Countries; and 3) suitability of the experimental facilities, as they pertain to the phenomena of interest, for code assessment. The information has been summarized in several Committee for the Safety of Nuclear Installations (CSNI) Code Validation Matrices (CCVMs) with Phenomena Identification Ranking Tables (PIRTs) that list SETFs, and IETFs relevant to each of different reactor types. The CCVM aims to gather the best set of openly available data for code validation possibly with uncertainty assessment of the code constitutive models and calculated results. The accessibility to the CCVM suggested data is essential for the development of reliable safety assessed codes, to support knowledge management and transfer to young experts and newcomers. This paper summarizes the CSNI’s CCVM development activities related to Thermal-Hydraulic (TH) and SA reactor safety analysis codes. The paper underlines the current needs for various new designs, including Small Modular Reactor (SMRs), through the PIRT process and highlights experimental data needs for the key accident phenomena.