Numerical simulation of cables in widespread use in the nuclear power industry subjected to fire

Numerical simulation is used to increase the knowledge base for failure of instrumentation or control cables utilized in the nuclear power industry subjected to an industrial fire. The model used for the simulation includes the electrical core of the conductors, the enveloping insulation, the filler material, and the jacket. All told, 22 cables in present use in the nuclear industry are investigated. The focus of the work is to determine the time at which a cable ceases to perform. That time is based on a definition provided by NUREG/CR-6931: Cable Response to Live Fire. It was found that the time to failure is well correlated with the thermal mass per unit length of the cable. The correlating equation, useful for interpolation is, Time to failure=(1376) (total thermal mass per unit length)+111. In this equation, the time to failure is in seconds, and the thermal mass per unit length, defined in Eq. (4), has units of kilojoules per degree Kelvin per meter. When comparing the numerical simulation to experimentation reported in NUREG/CR-6931: Cable Response to Live Fire, the correlation was found to be a conservative estimate of the time to failure.

► Investigated cable viability in presence of fire.
► Twenty-two cables in present use in the nuclear industry are investigated.
► Numerical simulation was used for the research.
► The time to failure is correlated with the cables thermal mass per unit length.
► The equation is time to failure (sec)=(1376) (kJ/K-m)+111.