Methodology study of qualification of electric wire and cable used in nuclear power plant

Abstract

Electric wire and cable used in the containment vessel of a nuclear power plant are exposed to weak radiation for the lifetime of the plant, which is expected to be more than 40 years. In addition, the materials in the vessel are predicted to be exposed to a higher thermal-radiation environment under a Loss of Coolant Accident (LOCA). LOCA is the basis for the design of power plants. The radiation dose and the temperature depend on the type of nuclear power plant. The maximum temperature and dose estimated in LOCA conditions is 150°C and 2 MGy, respectively, in pressurized water reactor. The properties of the wire and cable are also degraded by various stresses including steam and chemical spray added under LOCA conditions. This chapter demonstrates the importance of the synergistic relationship between thermal and nuclear radiation exposure in the heat- and radiation-induced degradation of elastomers used in electric wire and cable. This chapter describes an apparatus demonstrating LOCA conditions and gives examples of the test results. A procedure for the test with a particular emphasis on a valid accelerated irradiation condition and the synergistic relationship between heat and radiation on the degradation of elastomers is suggested. The suggestion proposes an ordering of the deteriorating factors added during LOCA conditions to establish an efficacious qualification procedure. © Springer Science+Business Media, LLC 2009.