Development of PIRT and Assessment Matrix for Verification and Validation of Sodium Fire Analysis Codes

Abstract

Thermodynamic consequence in liquid sodium leak and fire accident is one of the important issues to be evaluated when considering the safety aspect of fast reactor plant building. The authors are therefore initiating systematic verification and validation (V&V) activity to assure and demonstrate the reliability of numerical simulation tool for sodium fire analysis. The V&V activity is in progress with the main focuses on already developed sodium fire analysis codes SPHINCS and AQUA-SF. The events to be evaluated are hypothetical sodium spray, pool, or combined fire accidents followed by thermodynamic behaviors postulated in a plant building. The present paper describes that the 'Phenomena Identification and Ranking Table (PIRT)' is developed at first for clarifying the important validation points in the sodium fire analysis codes, and that an 'Assessment Matrix' is proposed which summarizes both separate effect tests and integral effect tests for validating the computational models or whole code for important phenomena. Furthermore, the paper shows a practical validation with a separate effect test in which the spray droplet combustion model of SPHINCS and AQUA-SF predicts the burned amount of a falling sodium droplet with the error mostly less than 30%.

Semi-Empirical Model of Droplet Size Distribution From the Maximum Entropy Principle in Sodium Spray

“…According to the research of Sandia National Laboratory (SNL) on sodium spray fire accident phenomenon identification and ranking table, it is found that the prediction of droplet size distribution is very important in sodium spray dynamics (Olivier et al, 2010). However, there is still a lack of relevant physical phenomena, and the empirical model is also lack of experiment verification (Ohno et al, 2012).…”