다변량 로지스틱 회귀분석을 이용한 증기발생기 전열관 ODSCC의 POD곡면 분석
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Steam generator tubes play an important role in safety because they constitute one of the primal)' barriers between the radioactive and non-radioactive sides of the nuclear power plant. For tins reason, the integrity of file tubes is essential in minimizing the leakage possibility of radioactive water, The integrity of the tubes is evaluated based on NDE (non-destructive evaluation) inspection results. Especially ECT (eddy current test) method is usually used for detecting the flaws in steam generator tubes. However, detection capacity of the NDE is not perfect and all of the "real flaws" which actually existing in steam generator tubes is not known by NDE results. Therefore reliability of NDE system is one of tile essential parts in assessing tile integrity of steam generators. In this study POD (probability of detection) of ECT system for ODSCC in steam generator tubes is evaluated using multivariate logistic regression. The cracked tube specimens are made using the withdrawn steam generator tubes. Therefore the cracks are not artificial but real. Using the multivariate logistic regression method, continuous POD surfaces are evaluated from hit (detection) and miss (no detection) binary data obtained from destructive and non-destructive evaluation of tile cracked tubes. Length and depth of cracks are considered in multivariate logistic regression and their effects on detection capacity are evaluated.