Application of fractional scaling analysis (FSA) to loss of coolant accidents (LOCA): Methodology development

Abstract

A quantitative methodology is developed to (a) scale time-dependent evolution processes involving an aggregate of interacting modules and processes (such as a NPP) and (b) integrate and organize information and data of interest to NPP design and safety analyses. The methodology is based on two concepts: fractional scaling and hierarchy. Fractional scaling is used to provide a synthesis of experimental data to generate quantitative criteria for assessing the effects of various design and operating parameters on thermo-hydraulic processes in a NPP. The synthesis via fractional scaling is carried out at three hierarchical levels: process, component and system. The methodology is demonstrated by applying it to a LOCA. The fractional scaling analysis (FSA) identifies dominant processes, ranks them quantitatively according to their importance and provides thereby an objective basis for establishing phenomena identification and ranking tables (PIRT) as well as a basis for conducting uncertainty analyses. The paper also discusses the benefits to be realized by applying the methodology to presently operating NPP as well as to future design of NPP.