Aging state analysis of cables insulated with ethylene propylene diene rubber exposed to simulated severe accident conditions

Takefumi Minakawa, Masaaki Ikeda, Naoshi Hirai, Yoshimichi Ohki

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Several cables in safety-related systems in nuclear power plants (NPPs) are required to perform their safety functions in severe accident conditions even after they experience inservice aging. For such cables, the behavior of their insulation under the accidents is a matter of concern. In this research, after cables insulated with ethylene propylene diene rubber (EPDM) were preconditioned by exposing them to concurrent heat and radiation to simulate aging that would be incurred in their service life in normal operating condition of NPPs, they were exposed to radiation and high temperature steam that simulate harsh accident conditions postulated inside the primary containment vessel. The changes in chemical structures and thermal and mechanical properties were analyzed by Fourier transform infrared spectroscopy, thermogravimetry, and indentation hardness measurements. As a result, it has been confirmed that the pre-aging and radiation exposure induce chain scission by oxidation and cross-linking, whereas the steam exposure causes bleedout of additives compounded in EPDM.

Original languageEnglish
Pages (from-to)380-386
Number of pages7
JournalIEEJ Transactions on Fundamentals and Materials
Volume139
Issue number9
DOIs
Publication statusPublished - 2019 Jan 1

Fingerprint

Propylene
Accidents
Rubber
Ethylene
Cables
Aging of materials
Radiation
Nuclear power plants
Steam
Containment vessels
Indentation
Service life
Fourier transform infrared spectroscopy
Thermogravimetric analysis
Insulation
Thermodynamic properties
Hardness
Oxidation
Mechanical properties
Temperature

Keywords

  • Ethylene propylene diene rubber
  • Nuclear power plant
  • Safety-related cable
  • Severe accident
  • Steam exposure

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

Cite this

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abstract = "Several cables in safety-related systems in nuclear power plants (NPPs) are required to perform their safety functions in severe accident conditions even after they experience inservice aging. For such cables, the behavior of their insulation under the accidents is a matter of concern. In this research, after cables insulated with ethylene propylene diene rubber (EPDM) were preconditioned by exposing them to concurrent heat and radiation to simulate aging that would be incurred in their service life in normal operating condition of NPPs, they were exposed to radiation and high temperature steam that simulate harsh accident conditions postulated inside the primary containment vessel. The changes in chemical structures and thermal and mechanical properties were analyzed by Fourier transform infrared spectroscopy, thermogravimetry, and indentation hardness measurements. As a result, it has been confirmed that the pre-aging and radiation exposure induce chain scission by oxidation and cross-linking, whereas the steam exposure causes bleedout of additives compounded in EPDM.",
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AU - Ikeda, Masaaki

AU - Hirai, Naoshi

AU - Ohki, Yoshimichi

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N2 - Several cables in safety-related systems in nuclear power plants (NPPs) are required to perform their safety functions in severe accident conditions even after they experience inservice aging. For such cables, the behavior of their insulation under the accidents is a matter of concern. In this research, after cables insulated with ethylene propylene diene rubber (EPDM) were preconditioned by exposing them to concurrent heat and radiation to simulate aging that would be incurred in their service life in normal operating condition of NPPs, they were exposed to radiation and high temperature steam that simulate harsh accident conditions postulated inside the primary containment vessel. The changes in chemical structures and thermal and mechanical properties were analyzed by Fourier transform infrared spectroscopy, thermogravimetry, and indentation hardness measurements. As a result, it has been confirmed that the pre-aging and radiation exposure induce chain scission by oxidation and cross-linking, whereas the steam exposure causes bleedout of additives compounded in EPDM.

AB - Several cables in safety-related systems in nuclear power plants (NPPs) are required to perform their safety functions in severe accident conditions even after they experience inservice aging. For such cables, the behavior of their insulation under the accidents is a matter of concern. In this research, after cables insulated with ethylene propylene diene rubber (EPDM) were preconditioned by exposing them to concurrent heat and radiation to simulate aging that would be incurred in their service life in normal operating condition of NPPs, they were exposed to radiation and high temperature steam that simulate harsh accident conditions postulated inside the primary containment vessel. The changes in chemical structures and thermal and mechanical properties were analyzed by Fourier transform infrared spectroscopy, thermogravimetry, and indentation hardness measurements. As a result, it has been confirmed that the pre-aging and radiation exposure induce chain scission by oxidation and cross-linking, whereas the steam exposure causes bleedout of additives compounded in EPDM.

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