원자로헤드 관통부 노즐 J-Groove 용접부 검사기법 개선 연구

Abstract

ABSTRACT The development of the NDE for the J-Groove weld of PWR CEDM Nozzles

Yim, Song Jin Advisor : Prof. Song Jong Sun, Ph.D. Department of Nuclear Engineering, Graduate School of Chosun University

This study is to confirm the TOFD(Time of Flight Diffraction) UT coverage of the J-Groove weld of PWR CEDM Nozzles. PWR CEDM Nozzles themselves had been inspected by Ultrasonic Test(Volumetric test) since 2003 according to NRC Order EA-03-009, but there were no UT program to examine the J-Groove weld except the surface test such as PT and ECT. In order to inspect J-Groove weld by UT, this experiment tried to make the mock-up with same material from new replacing reactor vessel head which is installed in Hanbit unit 3. The mock-up that drilled by 3.2mm for 9 each and 2.0mm for 5 each was made as the same shape and manufacturing method of real reactor vessel head. TOFD-UT was implemented by using the mock-up , and this experiment figured out the possibility of getting the valuable signal of depth. In results in evaluation of the UT signals, it detected the signal until 0.4 inch from outer diameter. It means that the J-Groove weld of PWR CEDM Nozzles is possibly inspected by Volumetric test(UT) until 0.4 inch in depth and it will show the leak path if it has a crack inside. Therefore, it verified that the coverage of TOFD-UT is possible to analyze the volumetric defects inside the J-Groove weld in this experiment.