Abstract In order to reduce the time for core verification or visual inspection of BWR fuels, the underwater camera using a High- Definition camera has been developed. As a result of this development, the underwater camera has 2 lights and 370×400×328mm dimen sions and 20.5kg weight, Using the camera, 6 or so spent-fuel IDs are identified at lor 1.5m distance at a time, and 0.3mm $ pin-h ole is recognized at 1.5m distance and 20 times zoom-up. Noises caused by radiation less than 15Gy/h are not affected th...
英字タイトル:
Development of underwater camera using High-Definition camea

The reasons of accidents are reported frequently that “I was too busy to avoid an error“ or “I had no time to make a check“. Though there is a view on that personnel reduction and increase in quantity of occupations heighten the feeling of busyness of workers, there are few previous studies on the factors that affect the feeling of busyness. Then, the questionnaire about the feeling of busyness is developed. In this study, in order to make clear the background factors influencing the feeling of busyness, ...
英字タイトル:
A Study of the Background Factors Influencing the Feeling of Busyness of Plant Workers

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 ?

This study proposes a novel nondestructive evaluation method of chill contents in gray cast irons by means of AC magnetization method. For the purpose, magnetic properties of cast irons w ith different chill contents were evaluated by B-H loop analyzer. Results were discussed in view of matrices and graphite, and it was found that some magnetic parameters, especially B-H l oop area, correlate well with ratio of cementite area to graphite one. Focusing on the fact, AC magnetic method was applied to evaluati...
英字タイトル:
Evaluation of Chill Contents in Flaky Cast Irons Based on AC Magnetization Method

Magnetic properties derived from major hysteresis loops are sensitive to the microstructures of iron-based steels and have therefore been used for nondestructive evaluation of degradation in ferromagnetic materials contained in structural components. A permeability obtained from ac small field excitation may be a more us eful parameter than one obtained from a major hysteresis loop from the viewpoints of electricity consumption and real-time measurement. In this paper, the relati on between the ac permeabi...
英字タイトル:
Evaluation for Mechanical Properties of Ferromagnetic Steels by AC Permeability

Various activities were doing for the decommissioning of Fukushima Daiichi nuclear power station. In present, activities are limited by remote operation or short time manual operation, because these areas are still high radiation rate. In this situation, it is expected to reduce the radiation rate of these areas by the decontamination, shielding and removal radiation souses, et al. At the national project “Development of remote decontamination technology for reactor building”, we selected adoptable de...
英字タイトル:
Development of Remote Dry-ice Blast Decontamination Vehicle for the lower part of the Reactor Building such as floor and wall

Abstract: This study tries to clarify the maintenance activities that can be applied risk information to, and determine priority of the application. For that purpose, first, we investigated the maintenance activities themselves, and broke them down into 75 “Maintenance Elements”. Second, we evaluated whether each “ Maintenance Element” could be applied risk information to. Third, we determined the priority of the risk application on “application merit” and “possibility” aspects. This study has revealed t...
英字タイトル:
Study of Application of Risk Information to Maintenance Management

In this paper, experimental and numerical studies are carried out to understand the pipe-wall thinning caused by the flow accelerated corrosion behind an orifice in a circular pipe. The measurement of mass transfer coefficient is carrie d out using a wall material of benzoic acid in a water flow, which allows the measurement of mass transfer behind the orifice in a circular pipe at Schmidt number 300 and 700, which is comparatively close to the actual condition in the prototype pipeline of nuclear power pl...
英字タイトル:
Study on Mass Transfer Phenomenon behind an Orifice in a Circular Pipe - Effect of Schmidt Number -