Experimental and analytical studies on penetration integrity of the lower pressure vessel under external vessel cooling in the KNGR

A program on estimation of penetration integrity in the lower reactor vessel has been performing under external vessel cooling in the Korean Next Generation Reactor (KNGR). The objective of this program is to carry out experiments and analysis on integrity estimation 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 pressure vessel. This study is focused on the detailed analysis of KNGR-ICI 2,3 experiments on performing the estimation of system pressure and corium mass effects, respectively. The test results have been evaluated using the LILAC computer code. The test results have shown that an increase in system pressure from 0.9 MPa to 1.5 MPa was not effective, but an increase in corium mass from 40 kg to 60 kg was effective on penetration damage. It justifies the test results and analytical model that the LILAC results are very similar to the test results on the depth of weld ablation