Improvement of plant reliability based on combining of prediction and inspection of crack growth due to intergranular stress corrosion cracking

Uchida, Shunsuke; Chimi, Yasuhiro; Kasahara, Shigeki; Hanawa, Satoshi; Okada, Hidetoshi*; Naito, Masanori*; Kojima, Masayoshi*; Kikura, Hiroshige*; Lister, D. H.*

Nuclear Engineering and Design, 341, p.112 - 123, 2019/01

https://doi.org/10.1016/j.nucengdes.2018.10.021

Improvement of plant reliability based on reliability-centered-maintenance (RCM) is going to be undertaken in NPPs. RCM is supported by risk-based maintenance (RBM). The combination of prediction and inspection is one of the key issues to promote RBM. Early prediction of IGSCC occurrence and its propagation should be confirmed throughout the entire plant systems which should be accomplished by inspections at the target locations followed by timely application of suitable countermeasures. From the inspections, accumulated data will be applied to confirm the accuracy of the code, to tune some uncertainties of the key data for prediction, and then, to increase their accuracy. The synergetic effects of prediction and inspection on application of effective and suitable countermeasures are expected. In the paper, the procedures for the combination of prediction and inspection are introduced.

Criticality and doppler reactivity worth uncertainty due to resolved resonance parameter errors; Formula for sensitivity analysis

Zukeran, Atsushi*; Nakagawa, Tsuneo; Shibata, Keiichi; Ishikawa, Makoto*; Hino, Tetsushi*

JAERI-Research 2004-026, 102 Pages, 2005/02

JAERI-Research-2004-026.pdf:7.68MB

Reactivity uncertainties such as effective multiplication factor can be estimated by the sensitivity coefficients of the infinitely diluted cross section and resonance self-shielding factor to the changes of resonance parameters of interest. In the present work, the uncertainties of the resolved resonance parameters for the evaluated nuclear data file JENDL-3.2 were estimated on the basis of Breit-Wigner Multi-level formula. The resonance self-shielding factor based on NR-approximation is analytically described. Reactivity uncertainty evaluation method for the effective multiplication factor k, temperature coefficient , and Doppler reactivity worth is developed by means of the sensitivity coefficient against the resonance parameter. Final uncertainties are estimated by means of error propagation law using the level-wise uncertainties. Preliminary uncertainty of Doppler reactivity worth results about 4% at the temperature 728 K for large sodium-cooled FBR.