The State Of the Art on Scaling elaborated in 2017 within OECD-NEA-CSNI-WGAMA has concluded that guidelines and training about scaling are necessary. Moreover, guidelines are also required for V&V-UQ and code scalability demonstration. Some reflections are collected and reported here, proposing guidelines for the successive steps of a BEPU methodology. In this Part 1, guidelines address the PIRT, the transient and scaling analysis including the design of integral and separate effect test facilities. Attention is drawn on how to identify thermal-hydraulic phenomena and on the role of bifurcating events. Then, some guidelines for scaling analysis address the selection of parameters of interest and of scaling equations at system and component scales. Guidelines give a list of the most useful equations depending on the transient of interest and specify the way to use them. Tools are also proposed to analyse a transient and to quantify scaling distortions in reduced scaled experiments and their effects on the figures of merit. Some of these tools are able to correct the scaling distortions. The use of hybrid calculations between an integral effect test and a reactor transient is discussed. The role of mature system codes in all these steps is emphasized. The methodology is illustrated by the application of these guidelines and tools to transients that benefit from many experimental investigations including counterpart tests and from extensive analyses: the small break and the large break loss of coolant accidents in a pressurized water reactor.
On Some Ways to Improve BEPU Methodologies – Part 1: Guidelines on PIRT - Transient Analysis - Scaling Analysis - IET and SET Design
Bestion Dominique;D’Auria Francesco
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2024-01-01
Abstract
The State Of the Art on Scaling elaborated in 2017 within OECD-NEA-CSNI-WGAMA has concluded that guidelines and training about scaling are necessary. Moreover, guidelines are also required for V&V-UQ and code scalability demonstration. Some reflections are collected and reported here, proposing guidelines for the successive steps of a BEPU methodology. In this Part 1, guidelines address the PIRT, the transient and scaling analysis including the design of integral and separate effect test facilities. Attention is drawn on how to identify thermal-hydraulic phenomena and on the role of bifurcating events. Then, some guidelines for scaling analysis address the selection of parameters of interest and of scaling equations at system and component scales. Guidelines give a list of the most useful equations depending on the transient of interest and specify the way to use them. Tools are also proposed to analyse a transient and to quantify scaling distortions in reduced scaled experiments and their effects on the figures of merit. Some of these tools are able to correct the scaling distortions. The use of hybrid calculations between an integral effect test and a reactor transient is discussed. The role of mature system codes in all these steps is emphasized. The methodology is illustrated by the application of these guidelines and tools to transients that benefit from many experimental investigations including counterpart tests and from extensive analyses: the small break and the large break loss of coolant accidents in a pressurized water reactor.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
