Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents

To obtain the knowledge that contributes to the safer operation of nuclear power plants and their prompt recovery and termination in the event of an accident, soft epoxy resins with rubber-based additives—used as insulators and airtight sealants in electrical penetrations in nuclear power plants—wer...

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Autores principales:	Yoshimichi Ohki, Hiroyuki Ishii, Naoshi Hirai
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	nuclear power plant steam exposure aging gamma rays electrical insulation sealant Technology T
Acceso en línea:	https://doaj.org/article/02f1faefd7e241dab061d8fa066aec98
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spelling	oai:doaj.org-article:02f1faefd7e241dab061d8fa066aec982021-11-11T15:45:46ZDegradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents10.3390/en142169321996-1073https://doaj.org/article/02f1faefd7e241dab061d8fa066aec982021-10-01T00:00:00Zhttps://www.mdpi.com/1996-1073/14/21/6932https://doaj.org/toc/1996-1073To obtain the knowledge that contributes to the safer operation of nuclear power plants and their prompt recovery and termination in the event of an accident, soft epoxy resins with rubber-based additives—used as insulators and airtight sealants in electrical penetrations in nuclear power plants—were aged under several simulated severe accident environments with different conditions of heat, gamma rays, and exposure to superheated steam containing no oxygen. Then, changes in structural, dynamic mechanical, mechanical, and dielectric properties were examined. It has been found that this resin becomes hard as a result of cross-linking if aged by irradiation with gamma rays. Since the cross-linking slows down the molecular motions, the glass transition temperature increases, whereas the dielectric permittivity and the dielectric loss factor decrease unless the steam penetrates the sample. Although the sample melts and disappears if directly exposed to superheated steam at 171 °C or 200 °C, the irradiation with gamma rays conducted prior to the steam exposure can mitigate the hydrolysis induced by the steam. Although the soft epoxy resin shows drastic changes in various properties, its properties after the aging approach or exceed the corresponding ones of the non-degraded ordinary hard epoxy resin. Therefore, it seems that using soft epoxy resin according to its purposes would not be a problem.Yoshimichi OhkiHiroyuki IshiiNaoshi HiraiMDPI AGarticlenuclear power plantsteam exposureaginggamma rayselectrical insulationsealantTechnologyTENEnergies, Vol 14, Iss 6932, p 6932 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	nuclear power plant steam exposure aging gamma rays electrical insulation sealant Technology T
spellingShingle	nuclear power plant steam exposure aging gamma rays electrical insulation sealant Technology T Yoshimichi Ohki Hiroyuki Ishii Naoshi Hirai Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents
description	To obtain the knowledge that contributes to the safer operation of nuclear power plants and their prompt recovery and termination in the event of an accident, soft epoxy resins with rubber-based additives—used as insulators and airtight sealants in electrical penetrations in nuclear power plants—were aged under several simulated severe accident environments with different conditions of heat, gamma rays, and exposure to superheated steam containing no oxygen. Then, changes in structural, dynamic mechanical, mechanical, and dielectric properties were examined. It has been found that this resin becomes hard as a result of cross-linking if aged by irradiation with gamma rays. Since the cross-linking slows down the molecular motions, the glass transition temperature increases, whereas the dielectric permittivity and the dielectric loss factor decrease unless the steam penetrates the sample. Although the sample melts and disappears if directly exposed to superheated steam at 171 °C or 200 °C, the irradiation with gamma rays conducted prior to the steam exposure can mitigate the hydrolysis induced by the steam. Although the soft epoxy resin shows drastic changes in various properties, its properties after the aging approach or exceed the corresponding ones of the non-degraded ordinary hard epoxy resin. Therefore, it seems that using soft epoxy resin according to its purposes would not be a problem.
format	article
author	Yoshimichi Ohki Hiroyuki Ishii Naoshi Hirai
author_facet	Yoshimichi Ohki Hiroyuki Ishii Naoshi Hirai
author_sort	Yoshimichi Ohki
title	Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents
title_short	Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents
title_full	Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents
title_fullStr	Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents
title_full_unstemmed	Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents
title_sort	degradation of soft epoxy resin for cable penetrations induced by simulated severe accidents
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/02f1faefd7e241dab061d8fa066aec98
work_keys_str_mv	AT yoshimichiohki degradationofsoftepoxyresinforcablepenetrationsinducedbysimulatedsevereaccidents AT hiroyukiishii degradationofsoftepoxyresinforcablepenetrationsinducedbysimulatedsevereaccidents AT naoshihirai degradationofsoftepoxyresinforcablepenetrationsinducedbysimulatedsevereaccidents
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Degradation of Soft Epoxy Resin for Cable Penetrations Induced by Simulated Severe Accidents

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