Silicone resin experiments of EPA leak characterization test in the ALPHA program (SLB001, SLB002)

In the ALPHA (Assessment of Loads and Performance of a Containment in a Hypothetical Accident) program, several tests are conducted to clarify phenomena which influence the integrity of a containment in LWR severe accidents. One of the tests in the ALPHA program is the EPA (Electrical Penetration Assembly) leak characterization test which includes silicone resin experiments. Purposes of the silicone resin experiments are; 1) to obtain database on melt progression of the silicone resin under thermal-hydraulic conditions in a containment during a severe accident, 2) to investigate influence of metal part on the silicone resin behavior in the EPA. The experiments have been performed using the small-scale test section which simulates silicone resin, cable conductor, shroud and header plate of an EPA of a nuclear power plant. Two experiments were so far performed increasing the temperature in the atmosphere of a leak test vessel at a rate of 1 K/min from room temperature. Leakage initiation was detected at about 410 K and 430 K in the two experiments. Temperature distribution in the test section showed that heat conduction along the metal portion such as the shroud and the cable conductor has a strong effect on the silicone resin behavior. Post-test observation of the test section in the second experiment and temperature distribution measured in the both experiments indicated that the initial leak path was formed along the shroud. (author)