상부 탑재형 노내계측기(TM-ICI) 개발은 원자로하부헤드 대신 원자로상부헤드로 계측기를 삽입함으로써 중대사고 위험을 줄이기 위해 진행 중이다. 이 개발 과제의 일환으로, NUREG/CR-6909와 Code Case N-761의 두 방법에 따라 TM-ICI 노즐에 대한 환경피로평가가 수행되었다. TM-ICI 노즐은 level A, level B 및 시험 조건에서의 과도조건에 따른 하중을 받는데 이에 대해 피로평가를 해야 한다. 원자로냉각재환경이 고려된 TM-ICI 노즐의 누적사용계수는 1이하로 평가되었고, 이는 ASME Code 허용기준을 만족한다.

The development of Top-Mounted In-Core Instrumentation(TM-ICI) is an ongoing project to reduce the risk due to severe accidents by inserting the instrumentation into a reactor closure head instead of a reactor bottom head. As part of this project, environmental fatigue analyses for TM-ICI nozzle have been performed using two methods of NUREG/CR-6909 and Code Case N-761. TM-ICI nozzle is subjected to transient loads for level A, level B and test conditions that should be evaluated for a fatigue analysis. It is found that a cumulative usage factor considering reactor coolant environment for TM-ICI nozzle is evaluated as less than 1, which is ASME Code allowable criteria of a fatigue analysis.

• 윤효섭(한국전력기술(주) 기계설계그룹, KEPCO Engineering and Construction Company, Mechanical System Engineering Group) | Hyo-Sub Yoon
• 김종민(한국전력기술(주) 기계설계그룹, KEPCO Engineering and Construction Company, Mechanical System Engineering Group) | Jong-Min Kim Corresponding author
• 맹철수(한국전력기술(주) 기계설계그룹, KEPCO Engineering and Construction Company, Mechanical System Engineering Group) | Cheol-Soo Maeng
• 김기석(한국전력기술(주) 기계설계그룹, KEPCO Engineering and Construction Company, Mechanical System Engineering Group) | Gee-Seok Kim
• 김현민(한국전력기술(주) 기계설계그룹, KEPCO Engineering and Construction Company, Mechanical System Engineering Group) | Hyun-Min Kim