Aging management technical evaluation is required for LWRs every 10 years at and after 30 years operation in Japan. Thermal aging evaluation of austenitic cast stainless steel components is one of the items of aging evaluation. Technical basis of thermal aging evaluation for BWR components such as thermal aging behavior of cast stainless steel used in Japanese BWRs, applicability of thermal aging prediction models and basic way of integrity evaluation of the components are described in this paper....
英字タイトル:
Technical basis of thermal aging evaluation of stainless steel cast steel components in BWR

NRRC (Nuclear Risk Research Center) is focusing on support of voluntary safety improvement activities of electric utilities. In this paper, several approaches to implement good PRA are described....
英字タイトル:
Approach of NRRC for implementation of Good PRA

Between 2010 and 2015 the American Society of Testing and Materials (ASTM) developed a new embrittlement trend curve (ETC) to represent trends in a large international collection of reactor pressure vessel (RPV) surveillance data. This work was concluded in 2015 and resulted in an update to the ASTM Standard E900. In this paper we explore options for using an E900-15 style fitting function to represent trends in surveillance data collected from Japanese nuclear power plants....
英字タイトル:
Options for Using an ASTM E900-15-Style Function to Represent Trend in Domestic RPV Surveillance Data

The PD Center of Central Research Institute of Electric Power Industry (CRIEPI) commenced performance demonstration examinations (PD examination) for flaw depth sizing of austenitic stainless steel pipes in March 2006. At the end of FY 2018, 50 examination sessions had been completed and 68 candidates had passed the examination. The total number of PD examinee including re-examination and re-certification was 116. Passed candidates can perform depth sizing of SCC flaws with a high level of accuracy. Mean of...
英字タイトル:
Current status of Japanese PD examination for 13 years

The PD Center of Central Research Institute of Electric Power Industry (CRIEPI) commenced performance demonstration examinations (PD examination) for flaw depth sizing of austenitic stainless steel pipes in March 2006. At the end of FY 2020, 54 examination sessions had been completed and 72 candidates had passed the examination. The total number of PD examinee including re-examination and re-certification was 124. Passed candidates can perform depth sizing of SCC flaws with a high level of accuracy. As a re...
英字タイトル:
Current status of Japanese PD examination for 15 years

When an excess pressure and temperature are added to a containment vessel (CV) of a nuclear power plant (NPP) by a severe accident, overpressure damage of the CV is assumed to be possible. When the CV falls into such a situation, radioactive materials in the CV are released into the environment. Filtered containment venting systems (FCVS) that is installed in the exhaust systems reduce pressure in the CV while mitigating the release of the radioactive materials by the multi-scrubbers (venturi-scrubber, wet ...
英字タイトル:
Development of technical basis for filtered containment venting system and its utilization

人材の育成は原子力発電所で RIDM プロセスを実現させるために非常に重要であり、意思決定者のみならず、RIDM プロセスに関わる組織の構成員全てが役割に応じて RIDM プロセスに関する知識を理解していることで、RIDM プロセスがより円滑に実施される。加えて、RIDM に資するリスク評価のための PRA の専門知識を持った実務者も必要となる。NRRC におけるこれら発電所の人材育成をサポートするための取り組みを概説する。...
英字タイトル:
NRRC's approach to human resource development for RIDM

Irradiation embrittlment prediction of Japanese surveillance data and MTR irradiation data was performed by using five different embrittlement trend curves, RG.1.99R2, ENOY, E900-15, EDF2010 and JEAC4201-2007[2013 addendum] (JEAC4201-2013). The comparison result showed that the prediction by JEAC 4201-2013 brought more appropriate prediction results than those by the other curves....
英字タイトル:
Embrittlement predictions of Japanese surveillance data using the typical embrittlement trend curves in the world

近年、原子力発電所の確率論的リスク評価(PRA)の評価技術の向上に伴い、人的過誤によるリスクへの影響も重要なものとなっている。このため、人間信頼性解析(HRA)をもちいて、人的過誤事象を体系的に分析し現実的な評価とすることが課題となっている。これらに対応した HRA の定性分析における実施手順及び、具体的な評価適用事例を示した NRRC の HRA 定性分析ガイドについて概説する。...
英字タイトル:
Development of Guide for Qualitative Analysis in the Human Reliability Analysis (HRA) and Improvement of the HRA Method

Flow Acceleration Corrosion (FAC) is one of the mechanisms of pipe wall thinning in power plants. The wall thinning caused by FAC is usually found between 90 ℃ and 230 ℃ with a peak at about 150 ℃. However, FAC has been reported at temperatures below this range. This study evaluated the effect of DO and Cr content on wall thinning rate at 50 ℃. Raman spectroscopy was performed to identify the constituent species of the oxide film. FAC rate was seen to decrease by increasing Cr content. In terms of DO, wall ...
英字タイトル:
Combined Effect of Cr content and Dissolved Oxygen Concentration on Wall Thinning Rate by Low Temperature FAC