本研究では、PWRプラント運転を想定した熱時効初期の残留応力緩和メカニズム解明の一環として、LP、WJP、バフ研磨の三工法および機械加工を施した600合金について、熱時効時の組織変化を明確にすることを目的とした。各工法の施工材についてEBSD解析を行うことにより、応力緩和過程に関与すると考えられる組織学的因子の検討を実施した。...
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Microstructural Investigation of Residual Stress Relaxation Process of Ni-based Alloy by EBSD Analysis

In order to prevent primary water stress corrosion cracking (PWSCC), water jet peening (WJP) has been used on the welds of Ni-based alloys in pressurized water reactors (PWRs). However, the compressive residual stresses induced by WJP might be relaxed during the actual operation because of the elevated temperature environment. Therefore, the stability of the compressive residual stresses caused by WJP has been investigated during thermal aging. The result shows that the compressive residual stresses has...
英字タイトル:
Relaxation behavior of residual stress generated by water jet peening under operation temperature environment ― Evaluation for long term stability of residual stress improving treatment on Ni base alloy (report 1) ―

Recently, preventive maintenance tasks for welding of safe-end nozzles of reactor vessels and steam generators of PWRs in Japan had been carried out sequentially. Before the maintenance tasks, inspection services were carried out and several crack indications were found by eddy current testing (ECT). These indications were found in the welding which made b y 600 series nickel base alloy and evaluated as stress corrosion cracks which were oriented to the axial direction of the nozzle. Then investigations to...
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Development of the advanced phased array UT technique for accurate sizing of cracks in the nozzlewelding

When developing a maintenance program to be able to provide optimal maintenance activities for a whole plant system, positive adhesion to a maintenance system in compliance with each piece of equipment, facility and degradation mode is not sufficient; it is necessary to reflect considerations about the importance of facilities and matching between failure mode and maintenance system, arrangement for renewal of system components, as well as various requirements for the plant including the design basis. Thi...
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Comprehensive methodology for developing a maintenance program for plant system, and verification on nuclear plant

Abstract: This paper discusses a development of the quantitative method to evaluate the reliability for the maintenance plan with respect to the risk impact both for Core Damage Frequency and Plant Trip Frequency. The quantitative approach includes the considerations for the effect of the Condition Based Maintenance (CBM) changing in addition to the Time Based Maintenance (TBM), and the reliability for the maintenance plan is evaluated using the actual plant-specific maintenance information collected ...
英字タイトル:
A Study on the Reliability Evaluation Method for Maintenance Planning Using Risk Information

This paper discusses an improvement of the quantitative method to evaluate the reliability for the maintenance plan with respect to the risk impact both for CDF (Core Damage Frequency) and Plant Trip Frequency. The quantitative approach includes the considerations for the effect of the Condition Based Maintenance (CBM) changing in addition to the Time Based Maintenance (TBM), and the reliability for the maintenance plan is evaluated using component failure rate which is presumed from experimental maintena...
英字タイトル:
A Study for the Reliability Evaluation Method for the Maintenance Plan Using the Risk Information II : - Part1 : The evaluation Method of failure rate based on degraded state analysis of component part ?

This paper discusses an improvement of the quantitative method to evaluate the reliability for the naintenance plan with respect to the risk impact both for CDF (Core Damage Frequency) and Plant T rip requency. The quantitative approach includes the considerations for the effect of the Condition Based Taintenance (CBM) changing in addition to the Time Based Maintenance (TBM), and the reliab ility for the naintenance plan is evaluated using component failure rate which is presumed from experimental naintena...
英字タイトル:
A Study for the Reliability Evaluation Method for the Maintenance Plan Using the Risk Information II? Part 2: An application example of the evaluation method of failure ratebased on degraded state analysis of component part ?

保全の体系化について(第1回)―原子力発電所の保全活動の現状― 設楽 親,Chikashi SHITARA,千種 直樹,Naoki CHIGUSA,岩見 裕,Hiroshi IWAMI......

1．はじめに：普遍性と階層構造原子力発電設備でとられている保全の基本原理の中に「階層性」と「階層原理」を導入できないかという命題は検討に値する。階層原理とは、例えば原子力プラントが電力を生産するまでにたどるプロセスは、設計と建設と運転管理、の三つの部分からなり、それらが階層的な役割を果たしながら全体として電力の安定供給という機能を果たしている仕組みを言う。階層性が存在し階層原理が正常に機能すれば、設計、建設、運転管理の三つの行為が適切に機能し、その結果電力は正常に国民に供給される、という目標が達成される。......

1．はじめに原子力発電に関わらず、プラントの保全は設計・運転・管理に携わるエキスパートによってその内容が立案され実施されている。計画立案の際に最も有効な情報は実はエキスパートの業務経験に基づく知識であり、過去のトラブル等の運転実績である。特に原子力の場合、他の産業に比べて日が浅いことから、現場の人たちの試行錯誤によって保全計画の改善がなされてきた側面が強い。しかしながら、運転経験の蓄積にともない従来の経験に基づく保全から理論に基づいた保全へと移行する機運が高まってきた。保全の体系化とはこの一連の流れにおい......