한국표준형원전 증기발생기 2차측 전장고온화학세정에 대한 고찰

Abstract

This study analysed Free EDTA and Fe concentration change, sludge removal amounts, the basic material corrosion rate and tube support plate MRPC result of steam generator secondary side of Hanbit nuclear power plant unit 6 which was performed the full length high temperature chemical cleaning being able to expect plant thermal efficiency improvement effect, life extension and stress corrosion cracking reduce of steam generator. The result is as following.

1. Free EDTA(Ethylene Diamine Tetra acetic Acid) concentration was showed decreasing as typical pattern in accordance with increasing Fe concentration. 2. Sludge removal amounts based on Fe3O4 was 3,001kg after performing the full length high temperature chemical cleaning, additionally sludge removal amount through Steam generator Lancing was 201kg. 3. Specimen corrosion rate of the basic metal of steam generator tube, Inconel 600 HTMA, was showed 0 mils which was under 10 mils of EPRI standard. 4. As a MRPC inspection result, sludge deposit amount after peformed the full length high temperature chemical cleaning decreased 99.7%. It showed that effectiveness of chemical cleaning was evaluated higher than a leading nuclear power plant. Also, Eggcrate TSP signal as C-SCAN result was showed very sharply and vividly. It was evaluated that sludge of TSP area was removed completely.

Through the KSNP steam generator secondary side full length high temperature chemical cleaning of the above, it is expected to be able to mitigate demage due to stress corrosion cracking at steam generator heat transfer tube by the sludge removal amount is increased over traditional chemical methods.