Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR

Core Disruptive Accident (CDA) has been considered as one of the important safety issues in the severe accident evaluation of Sodium-cooled Fast Reactor (SFR), since SFR core is not in the most reactive configuration. Initiating Phase (IP) is the earliest stage of CDA, and SAS4A code was designed to...

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Autores principales: Shinya ISHIDA, Ken-ichi KAWADA, Yoshitaka FUKANO
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Publicado: The Japan Society of Mechanical Engineers 2020
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spelling oai:doaj.org-article:f4429b19e3004e31886bd2182547456d2021-11-29T05:56:30ZValidation study of SAS4A code for the unprotected loss-of-flow accident in an SFR2187-974510.1299/mej.19-00523https://doaj.org/article/f4429b19e3004e31886bd2182547456d2020-02-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/7/3/7_19-00523/_pdf/-char/enhttps://doaj.org/toc/2187-9745Core Disruptive Accident (CDA) has been considered as one of the important safety issues in the severe accident evaluation of Sodium-cooled Fast Reactor (SFR), since SFR core is not in the most reactive configuration. Initiating Phase (IP) is the earliest stage of CDA, and SAS4A code was designed to precisely model the IP event progressions. Phenomena Identification and Ranking Table (PIRT) approach was applied to the SAS4A code in order to enhance its reliability in this study. This paper describes the study on the validation method and results of the validation of SAS4A using PIRT approach in a typical SFR. In this study, SAS4A validation was based on the generic PIRT process: (1) definition of issue of SAS4A code, (2) definition of PIRT objectives of using the PIRT approach, (3) selection of potential plant designs, (4) selection of potential scenarios, (5) selection of the figure of merit (FOM), (6) partition of scenario into convenient time phases, (7) definition of considerable physical regions, (8) identification of the phenomena, (9) ranking the important phenomena, (10) development of the code validation test matrix, and (11) test analyses for validation corresponding to the test matrix. Unprotected Loss Of Flow (ULOF) is selected as the specific scenario, since it is one of the most important and typical events in CDA. The average fuel temperature which corresponds to the energy release is selected as the FOM, since the energy release due to power excursion is important to evaluate whether the influence of CDA can be confined in the vessel. The phenomena are identified by the investigation of ULOF event progression and by making the system decomposition and hierarchy. These phenomena are ranked according to importance to the FOM. In the test matrix, the key phenomena are associated with SAS4A models, and the test cases used for validation of each model are shown. The results of the test analysis corresponding to this matrix show that the SAS4A models required for the IP evaluation were sufficiently validated. Furthermore, the validation with this matrix is highly reliable, since this matrix represents the comprehensive validation that also considers the relation among physical phenomena. In this study, the reliability and validity of SAS4A code were significantly enhanced by using PIRT approach to the sufficient level for CDA analyses in SFR.Shinya ISHIDAKen-ichi KAWADAYoshitaka FUKANOThe Japan Society of Mechanical Engineersarticlesevere accidentcore disruptive accident (cda)sodium-cooled fast reactor (sfr)sas4aphenomena identification and ranking table (pirt)Mechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 7, Iss 3, Pp 19-00523-19-00523 (2020)
institution DOAJ
collection DOAJ
language EN
topic severe accident
core disruptive accident (cda)
sodium-cooled fast reactor (sfr)
sas4a
phenomena identification and ranking table (pirt)
Mechanical engineering and machinery
TJ1-1570
spellingShingle severe accident
core disruptive accident (cda)
sodium-cooled fast reactor (sfr)
sas4a
phenomena identification and ranking table (pirt)
Mechanical engineering and machinery
TJ1-1570
Shinya ISHIDA
Ken-ichi KAWADA
Yoshitaka FUKANO
Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR
description Core Disruptive Accident (CDA) has been considered as one of the important safety issues in the severe accident evaluation of Sodium-cooled Fast Reactor (SFR), since SFR core is not in the most reactive configuration. Initiating Phase (IP) is the earliest stage of CDA, and SAS4A code was designed to precisely model the IP event progressions. Phenomena Identification and Ranking Table (PIRT) approach was applied to the SAS4A code in order to enhance its reliability in this study. This paper describes the study on the validation method and results of the validation of SAS4A using PIRT approach in a typical SFR. In this study, SAS4A validation was based on the generic PIRT process: (1) definition of issue of SAS4A code, (2) definition of PIRT objectives of using the PIRT approach, (3) selection of potential plant designs, (4) selection of potential scenarios, (5) selection of the figure of merit (FOM), (6) partition of scenario into convenient time phases, (7) definition of considerable physical regions, (8) identification of the phenomena, (9) ranking the important phenomena, (10) development of the code validation test matrix, and (11) test analyses for validation corresponding to the test matrix. Unprotected Loss Of Flow (ULOF) is selected as the specific scenario, since it is one of the most important and typical events in CDA. The average fuel temperature which corresponds to the energy release is selected as the FOM, since the energy release due to power excursion is important to evaluate whether the influence of CDA can be confined in the vessel. The phenomena are identified by the investigation of ULOF event progression and by making the system decomposition and hierarchy. These phenomena are ranked according to importance to the FOM. In the test matrix, the key phenomena are associated with SAS4A models, and the test cases used for validation of each model are shown. The results of the test analysis corresponding to this matrix show that the SAS4A models required for the IP evaluation were sufficiently validated. Furthermore, the validation with this matrix is highly reliable, since this matrix represents the comprehensive validation that also considers the relation among physical phenomena. In this study, the reliability and validity of SAS4A code were significantly enhanced by using PIRT approach to the sufficient level for CDA analyses in SFR.
format article
author Shinya ISHIDA
Ken-ichi KAWADA
Yoshitaka FUKANO
author_facet Shinya ISHIDA
Ken-ichi KAWADA
Yoshitaka FUKANO
author_sort Shinya ISHIDA
title Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR
title_short Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR
title_full Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR
title_fullStr Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR
title_full_unstemmed Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR
title_sort validation study of sas4a code for the unprotected loss-of-flow accident in an sfr
publisher The Japan Society of Mechanical Engineers
publishDate 2020
url https://doaj.org/article/f4429b19e3004e31886bd2182547456d
work_keys_str_mv AT shinyaishida validationstudyofsas4acodefortheunprotectedlossofflowaccidentinansfr
AT kenichikawada validationstudyofsas4acodefortheunprotectedlossofflowaccidentinansfr
AT yoshitakafukano validationstudyofsas4acodefortheunprotectedlossofflowaccidentinansfr
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