An experimental study on penetration integrity of the reactor vessel under external vessel cooling in the KNGR

An experimental study on penetration integrity of the reactor vessel has been performing under external vessel cooling in the Korean Next Generation Reactor (KNGR). The objective of this study is to estimate failure or not of the penetration including the In-Core instrumentation (ICI) nozzle and the thimble tube in condition with external vessel cooling to maintain integrity of the reactor vessel. Two experiments in conditions with and without external vessel cooling have been performed using the test section including only one penetration and alumina melt of 40kg from the thermite ignition as a simulant. The tests results have shown that penetration in the no external vessel cooling case is more damaged than that in the external vessel cooling case. It is concluded from the experimental results that the external vessel cooling is very effective on the penetration integrity. Penetration failure was not occurred in two experimental cases because of lower thermal load to the penetration