For the planning of decommissioning and the establishment of appropriate safety control during its activity, risk assessment to understand the potential accident scenarios during decommissioning is essential. The decommissioning phase following permanent shutdown involves a complex process such as dismantling of equipment and facilities, demolition of building and structures. The decay heat and management of spent fuels also change by time during decommission. In comparison to nuclear power plants at operat...
英字タイトル:
Nuclear power plant risk after permanent shutdown to decommissioning

Mihama Unit 1 & 2 are the first decommissioned nuclear power plants in the Japanese PWR (Pressurized Water Reactor). FSD (Full System Decontamination) in PWR has never been conducted in Japan before. FSD in Mihama Unit 1 & 2 is the first one in the Japanese PWR. On the other hand, heat transfer tubes of steam generator are made of nickel alloy 690. Chemical decontamination for nickel alloy 690 has never been conducted in the world. As the result, the target which DF (decontamination factor) is over 30 is ac...
英字タイトル:
The nation’s first FSD for PWR decommissioning

To continuously improve the safety of Japanese nuclear power plants that were restarted after the Fukushima Daiichi Nuclear Power Station accident, Mitsubishi Heavy Industries Ltd. (MHI) has been continuously working on the voluntary improvement of the safety of nuclear power plants together with electric power companies. MHI has been performing Probabilistic Risk Assessment and Stress Test for nuclear power plants, extracting measures for further safety improvement while developing technologies for new fac...
英字タイトル:
Efforts to Continuous Safety Improvement of Nuclear Power Plants in Japan

For the purpose of reduction in onsite workload in nuclear power plants, our current issue is that metal plate embedding and the related measurement consume a huge amount of man days and processes due. For the purpose of improving efficiency, skipping reference marking by applying Mixed Reality device and using 3D photographic measurement for the inspection have been considered. We aim to start the practical use of photographic measurement in new plant constructions....
英字タイトル:
In the construction work of a nuclear power plant, the efficiency of measurement of the metal plate to embed is increased.

The SCC Protect Technology by Peening is registered in The Maintenance Heritage by JSM We introduce The SCC Protect Technology by Peening in NPS...
英字タイトル:
The SCC Protect Technology by Peening in NPS

In large-scale plants that are used for a long period of time, the replacement work due to aging degradation, discontinuance of production of electronic components, reaching the maintenance deadline, etc. has become a very important issue. Among them, the replacement of the monitoring and control system during operation affects many facilities, so that the replacement schedule is short and it is difficult to change the schedule. This paper describes the results of a large-scale replacement of monitoring and...
英字タイトル:
Large-scale Replacement of Monitoring and Control System (DCS Replacement), in Main Control Room etc. of Reprocessing Plant, JAPAN NUCLEAR FUEL LIMITED(JNFL)

In the seawater system of nuclear power plants (NPPs), piping with polymer lining material is used to prevent corrosion. In recent years, however, seawater leakages due to aging deterioration of lining material have occurred, and improvement of reliability is needed. In response to the development of a polyethylene lining material with high durability that greatly exceeds the performance of conventional products and the start of its application to NPPs in operation ,this paper introduces the current of effo...
英字タイトル:
Maintenance and Inspection Efforts to Improve the Reliability of Seawater System Piping

Taking the accident response at Fukushima Daiichi Nuclear Power Plant as an opportunity, we have tried not to damage as much as possible against various types of risk. Furthermore, even if damage occurred, it has been regarded as important to have the ability to recover(resilience). As MHI possessing technologies that can contribute to voluntary safety improvement of nuclear power plants, there are Multiple Radiological Emergency Assistance System for Urgent Response(MEASURES), VISION, and the like. Also, t...
英字タイトル:
The effort of MHI for voluntary safety improvement

While the importance of maintenance of NPP is now being well recognized, standardization on maintenance has been mainly implemented for hardware that is SSCs. The quality of the SSCs in service is ensured not only by recognition of physical characteristic of the SCCs, but also by activities of the organization and personnel for maintenance of the SSCs. This paper presents status of study on the guideline for management of repair activities, which provides a typical example of standardization on management o...
英字タイトル:
The Study on the Guideline for Management of Repair Activities

Management and maintenance of electrical and I&C equipment, such as cables of nuclear power plants require a great effort. This is because there is a lot of equipment in nuclear power plants and the information which should be managed is written on a lot of documents and drawings. Therefore, the management and maintenance methods are developed. In this report, the management method od electrical and I&C equipment which is qualified environmentally is introduced....
英字タイトル:
Development of management and maintenance for electrical and I&C equipment