Insulation performance of safety-related cables for nuclear power plants under simulated severe accident conditions

To examine electrical insulation behavior of cables under severe accident environmental conditions, safety-related low voltage cables used as severe accident management equipment were subjected to two tests that simulated two environments: 1) at 155°C, which is the simulated highest assumed temperature when proper accident management measures are taken, 2) at 200°C, which is the maximum durable temperature of a primary containment vessel. In addition, electrical insulation resistance was measured for the cables during steam exposure in the two tests. As a result, all the cables passed the acceptance criteria of the tests. The minimum volume resistivity of the cables during the test at 155°C was around 108Om, confirming that the cables have a sufficient insulation performance. On the other hand, the minimum volume resistivity during the severer test at 200°C was around 105Om due to the increase in leak current.