Fire Retardancy Analysis of the Aged Cables in Nuclear Power Plants: Flammability Modelling using Thermogravimetric Analysis and Differential Scanning Calorimetry

Abstract

The first step towards fire protection in nuclear power plants based on the concept of ‘Defense in-depth’ is realized through the minimization of combustibles. Regarding the realistic methods for minimizing combustibles in nuclear power plants, the fire retardancy of cables as the highest number of combustibles should be kept for design lifetime as well as at construction. The flame test, according to IEEE-383 and IEEE-1202, was conducted to assess the fire retardancy of aged and unaged cables, both of 1E and non-1E classes. However, previous editions of IEEE-383 (such as the 2015 edition) did not require non-1E class cables to be fire retardant. Therefore, a method to validate the fire retardancy of non-1E class cables installed in nuclear power plants (that had) got the construction permission before 2015 should be developed and implemented. Additionally, it is still unclear as to how the accelerated thermal aging specified in IEEE-383 is close to that of the real aged cables in nuclear power plants. Therefore, flammability modelling using thermogravimetric analysis and differential scanning calorimetry is proposed for solving the above mentioned issues and comprehending the flammability of cables beyond the test codes such as IEEE-1202.