Development of V2UP (V&V plus uncertainty quantification and prediction) procedure for high cycle thermal fatigue in fast reactor—Framework for V&V and numerical prediction

Highlights: • Proposal of a V&V and prediction procedure called as V2UP. • Introduction of framework of the V2UP. • Hierarchical classification of V&V problems. - Abstract: High cycle thermal fatigue on a structure caused by thermal striping phenomena is one of the most important issues in the design of fast breeder reactors (FBRs). In development of numerical simulation codes and in plant design and estimation by using the numerical estimation code, implementation of verification and validation (V&V) is indispensable process and also scaling issue from the subscale experiments to the full scale reactor should be considered. Therefore, a procedure called as V2UP (verification and validation plus uncertainty quantification and prediction) was made by referring to the existing guidelines on V&V (ASME V&V-10 and 20) and the methodologies of the safety assessment (CSAU, ISTIR, EMDAP). The V2UP consisted of five components as follows: (1) phenomena analysis with the Phenomena Identification and Ranking Table (PIRT) method, (2) implementation of the V&V, (3) design and rearrangement of experiments for the V&V, (4) uncertainty quantification in each problem and integration of uncertainties and (5) numerical prediction (estimation) for the target issue. Although the complete application of the procedure has not been performed at this moment, a flow chart of the V2UP procedure was described in this paper with recent results of the examinations.