초록 ▼

1. 연구개발목표 및 내용$\bigcirc$ 성능기준 건전성평가를 위한 모델 및 통합 DB 구축- 전산모델 해석에 의한 전열관 파열 및 누설 모델 개발- 열화 생성 및 성장 추세 평가모델 개발- 표준경수로 원주균열 원인 규명$\bigcirc$ 검사 신기술 개발 및 검증- 고리1 구증기발생기 ECT Round Robin$\cdot$검사신기술 확보: X-probe, 균열 크기 평가$\cdot$자연결함 검사신호 취득 및 RR 평가- 전열관 부식균열 제조기술 개

1. 연구개발목표 및 내용$\bigcirc$ 성능기준 건전성평가를 위한 모델 및 통합 DB 구축- 전산모델 해석에 의한 전열관 파열 및 누설 모델 개발- 열화 생성 및 성장 추세 평가모델 개발- 표준경수로 원주균열 원인 규명$\bigcirc$ 검사 신기술 개발 및 검증- 고리1 구증기발생기 ECT Round Robin$\cdot$검사신기술 확보: X-probe, 균열 크기 평가$\cdot$자연결함 검사신호 취득 및 RR 평가- 전열관 부식균열 제조기술 개발$\bigcirc$ Fouling에 의한 SG 열성능 저하 평가기술 개발- Fouling에 의한 열성능 저하 평가 프로그램 개발2. 연구결과$\bigcirc$ 전열관 파열 및 누설 모델 개발- 위치별, 균열 유형별 총 12개 파열압력 예측식 개발- 위치별, 균열 유형별 총 6개 균열 개구면적 예측식 개발(누설률 평가용)$\bigcirc$ 열화 생성 및 성장 추세 평가모델 개발- 열화 생성 및 성장속도 예측방법을 확률론적 기법으로 개발$\bigcirc$ 표준경수로 원주균열 원인 규명- 슬러지 퇴적이 가장 직접적인 원인, 미세 덴트가 원주균열 발생을 촉진$\bigcirc$ 고리1 구증기발생기 ECT Round Robin 추진- Bobbin, Plus Point, X 및 I 탐촉자로 고리1 RSG 검사신호 취득- PIUS Point 검사신호 균열탐지 Round Robin 평가 수행- 국내 검사신호 균열크기 Round Robin 평가 수행- 2단계에서 hot lab. 분석과 통계분석후 검사기술 성능 DB로 활용 예정$\bigcirc$ 전열관 부식균열 제조기술 개발- 다양한 형상과 양질의 입계균열 생성기술 개발, 균열 크기 제어$\bigcirc$ Fouling에 의한 SG 열성능 저하 평가기 개발- 전열관 파울링에 의한 열성능 저하 평가프로그램 개발 및 시범 적용3. 기대효과 및 활용방안$\bigcirc$ 증기발생기관리프로그램을 위한 핵심 요소기술 개발 및 활용- 전열관 파열 및 누설 모델- 열화 생성 및 추세 예측 프로그램- 고리 1호기 구증기발생기 자연결함을 이용한 ECT Round Robin- 전열관 부식균열 생성기술 개발$\bigcirc$ 검사기술 개발을 위한 핵심 요소기술 확보- 본 과제의 검사기술 성능 검증 database는 검사기술 개발을 위한 핵심자료- 다른 검사기술 개발 과제에서 활용 가능

Abstract ▼

This project IS to develop the inspection and integrity assessment technologies, as the leading project of the integrated research program, 'Development of Technologies for Improving Integrity of Nuclear Steam Generators'.An ECT round robin program is implemented in order to demonstrate pe

This project IS to develop the inspection and integrity assessment technologies, as the leading project of the integrated research program, 'Development of Technologies for Improving Integrity of Nuclear Steam Generators'.An ECT round robin program is implemented in order to demonstrate performance of inspection techniques and analysts using degraded tubes in a steam generator retired from Kori Unit One in 1998. Inspection data acquisition was made using X and I probes as well as Bobbin and Plus Point probes, with specific interests in cracks at top of tube sheet, tube support and U-bend. Flaw detection round robin analyses were done on the RSG inspection signals by nine separate teams with three analysts each. Crack sizing round robin analyses were done on 100 indications from Korean plants under operation by six separate teams with two analysts each. The results of the RR will be used as a key DB of performance of inspection, after hot lab. analysis and statistical analysis.Technologies ofgenerating intergranular stress corrosion cracks in Alloy 600 tubes were developed to support inspection technologies. Inside/outside and axial/circumferential cracks were generated by optimized loading on sensitized Alloy 600 tubes under room temperature sodium tetrathionate solution. Crack Size could be monitored by direct current potential drop methods.Tube burst and leakage models were developed using finite element computer calculation to support assessment of performance criteria. A total of 12 burst pressure equations were suggested for four types of cracks in three different locations. Crack opening area equations were suggested for assessing leak rates from two different crack types in three different locations. It was found that the existing COA equation suggested by EPRI may not conservative enough.An algorithm was developed to project end of cycle flaws from inspection data using Monte Carl calculation. It was verified useful on wears of a few Korean plants and cracks in one Korean plants. An experts meeting was held on the root cause of the circumferential cracks at top of tube sheet of steam generators of Korean Standard Nuclear Plants. Sludge accumulation trend and specific stress analysis were followed. It is suggested that deposition of sludge on the tube sheet is the direct cause of the cracks, and that small dents under the sludge deposit could change stress distribution and thus accelerate cracking.A computer program was developed to assess degradation of thermal performance caused by fouling of tubes using plant operation databases. Its usefulness was demonstrated in two Korean units.