Design approach for mitigation of air ingress in high temperature gas-cooled reactor

One important safety design consideration for high temperature gas-cooled reactor (HTGR) is air ingress following a rupture of the reactor pressure boundary such as primary piping. The air intrusion to the reactor core held at high temperature through the break will results in significant oxidation...

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Autores principales:	Hiroyuki SATO, Hirofumi OHASHI, Shigeaki NAKAGAWA
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2016
Materias:	htgr air ingress accident natural circulation numerical analysis Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/e63370a532c14be5b0301ac48f908ad4
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spelling	oai:doaj.org-article:e63370a532c14be5b0301ac48f908ad42021-11-26T07:03:57ZDesign approach for mitigation of air ingress in high temperature gas-cooled reactor2187-974510.1299/mej.16-00495https://doaj.org/article/e63370a532c14be5b0301ac48f908ad42016-12-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/4/3/4_16-00495/_pdf/-char/enhttps://doaj.org/toc/2187-9745One important safety design consideration for high temperature gas-cooled reactor (HTGR) is air ingress following a rupture of the reactor pressure boundary such as primary piping. The air intrusion to the reactor core held at high temperature through the break will results in significant oxidation of graphite components and fuels. Such oxidation may leads to the weakening of core support structures as well as fuel element damage and subsequent fission product release. This paper intends to propose a practical solution to protect the reactor from severe oxidation against air ingress accidents without reliance on subsystems. Firstly, a change is made to the center reflector structure to minimize temperature difference during the accident condition in order to reduce buoyancy-driven natural circulation in the reactor. Secondly, a modified structure of the upper reflector is suggested to prevent massive air ingress against a rupture in standpipes. As a preliminary study, a numerical analysis is performed for a typical prismatic-type HTGR to study the effectiveness of the proposed design concept using simplified lumped element models. The analysis considers internal decay heat generation and transient heat conduction from inner to outer regions at the reactor core, cooling of vessel outer surface by radiation and natural convection, and natural circulation flow in reactor. The results showed that amount of air ingress into the reactor can be significantly reduced with practical changes to local structure in the reactor.Hiroyuki SATOHirofumi OHASHIShigeaki NAKAGAWAThe Japan Society of Mechanical Engineersarticlehtgrair ingressaccidentnatural circulationnumerical analysisMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 4, Iss 3, Pp 16-00495-16-00495 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	htgr air ingress accident natural circulation numerical analysis Mechanical engineering and machinery TJ1-1570
spellingShingle	htgr air ingress accident natural circulation numerical analysis Mechanical engineering and machinery TJ1-1570 Hiroyuki SATO Hirofumi OHASHI Shigeaki NAKAGAWA Design approach for mitigation of air ingress in high temperature gas-cooled reactor
description	One important safety design consideration for high temperature gas-cooled reactor (HTGR) is air ingress following a rupture of the reactor pressure boundary such as primary piping. The air intrusion to the reactor core held at high temperature through the break will results in significant oxidation of graphite components and fuels. Such oxidation may leads to the weakening of core support structures as well as fuel element damage and subsequent fission product release. This paper intends to propose a practical solution to protect the reactor from severe oxidation against air ingress accidents without reliance on subsystems. Firstly, a change is made to the center reflector structure to minimize temperature difference during the accident condition in order to reduce buoyancy-driven natural circulation in the reactor. Secondly, a modified structure of the upper reflector is suggested to prevent massive air ingress against a rupture in standpipes. As a preliminary study, a numerical analysis is performed for a typical prismatic-type HTGR to study the effectiveness of the proposed design concept using simplified lumped element models. The analysis considers internal decay heat generation and transient heat conduction from inner to outer regions at the reactor core, cooling of vessel outer surface by radiation and natural convection, and natural circulation flow in reactor. The results showed that amount of air ingress into the reactor can be significantly reduced with practical changes to local structure in the reactor.
format	article
author	Hiroyuki SATO Hirofumi OHASHI Shigeaki NAKAGAWA
author_facet	Hiroyuki SATO Hirofumi OHASHI Shigeaki NAKAGAWA
author_sort	Hiroyuki SATO
title	Design approach for mitigation of air ingress in high temperature gas-cooled reactor
title_short	Design approach for mitigation of air ingress in high temperature gas-cooled reactor
title_full	Design approach for mitigation of air ingress in high temperature gas-cooled reactor
title_fullStr	Design approach for mitigation of air ingress in high temperature gas-cooled reactor
title_full_unstemmed	Design approach for mitigation of air ingress in high temperature gas-cooled reactor
title_sort	design approach for mitigation of air ingress in high temperature gas-cooled reactor
publisher	The Japan Society of Mechanical Engineers
publishDate	2016
url	https://doaj.org/article/e63370a532c14be5b0301ac48f908ad4
work_keys_str_mv	AT hiroyukisato designapproachformitigationofairingressinhightemperaturegascooledreactor AT hirofumiohashi designapproachformitigationofairingressinhightemperaturegascooledreactor AT shigeakinakagawa designapproachformitigationofairingressinhightemperaturegascooledreactor
_version_	1718409751154393088

Design approach for mitigation of air ingress in high temperature gas-cooled reactor

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