The current edition of “Guideline of Inspection and Evaluation for Reactor Internals issued by Japan Nuclear Safety Institute (JANSI) consists of inspection target, inspection method, and evaluation. Recently, the guideline is revised based on the safety function of the Reactor Internals, domestic operation experience, and the new knowledge. In this report, summary of “Guidelines of Inspection and Evaluation for Reactor Internals [Core Shroud] and [Shroud Support]....
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Guideline for BWR Inspection Program Revision Policy of Guidelines for Core Shroud and Shroud Support

Weld Overlay is a typical technique which took many years and huge amount of efforts for standardization in Japan, though it had already been well-developed with many application examples abroad as one of the repair methods. There has not an application example in Japan at all in spite of many efforts. This paper keeps a record of some backgrounds on standardization process of the weld overlay in Japan so as to consider better processes in the future....
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Some Backgrounds on Standardization of Weld Overlay Technique in Japan

It is important for maintenance of nuclear power station facilities in the future to promote mathematical techniques which support judgement to modify maintenance practices, such as maintenance tasks, maintenance implementation timing, and so on. Mathematical Maintenance Working Group, which has been established by Maintenance Standardization Committee since July 6, 2018, is investigating application examples of such mathematical techniques in maintenance planning as influence evaluation of changing maint...
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Investigation on application examples of mathematical techniques to support judgement to modify maintenance practices

It is necessary to improve not only plant system but also human system for maintenance to optimize maintenance for industrial plants like nuclear power plants. Codes and standards for design and construction of plant system have been already well developed. On the contrary, standardization of documents relating to human system including maintenance implementation plan, field work procedures etc. have poorly developed. So we have established the special committee in Japan Society of Maintenology to standardi...
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Necessity and Direction of Consideration of Maintenance Standardization

Using the Significance Determination Process of the US Reactor Oversight Process, we will clarify the significance level of the expected inspection findings in Decommissioning Reactors and the factors that increase the significance level. We will also summarize the differences in the inspection program for Decommissioning Reactors in Japan and the USA. Then, based on the characteristics of safety significance/ risk and the comparison of inspection program in Japan and the USA, we make grounded recommendatio...
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Reasonable Regulation/Inspection Program for Decommissioning Reactors (How understand the Safety Significance of Decommissioning Reactors)

By using the FCVS technology, we had started to develop a high decontamination air cleaning system to remove multi-nuclides for radiation protection to conduct decommissioning the Fukushima NPP. High efficiency multi-nuclide aerosol filters for radiation protection during a process of cutting core debris has been developing at Hokkaido University. A plasma cutter, laser cutter, wire cutter, drilling machine, etc., will be used and will generate aerosols. Therefore, the air cleaning system should be needed f...
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Development of a high efficiency multi-nuclide aerosol filters for radiation protection during a process of cutting core debris(3) Improvement for Wet-Type Filter

By using the FCVS technology, we had started to develop a high decontamination air cleaning system to remove multi-nuclides for radiation protection to conduct decommissioning the Fukushima NPP. High efficiency multi-nuclide aerosol filters for radiation protection during a process of cutting core debris has been developing at Hokkaido University. A plasma cutter, laser cutter, wire cutter, drilling machine, etc., will be used and will generate aerosols. Therefore, the air cleaning system should be needed f...
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Development of a high efficiency multi-nuclide aerosol filters for radiation protection during a process of cutting core debris (4) Improvement for Wet-Type Filter

At Tokai No. 2 Power Plant, the fourth monitoring test is conducted to confirm the tendency of reactor pressure vessel steels to become brittle due to neutron irradiation. From the results of the Charpy impact test, the amount of transition of the upper shelf absorbed energy and the related temperature was evaluated, and it was confirmed that there was no significant tendency to embrittlement. We report the results of the 4th monitoring test and discuss the results. ...
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Report of the reactor pressure vessel steel material surveillance test results (the 4th) at Tokai No. 2 Power Station

It has been newly required as a regulatory standard that the blowout panel installed in the reactor building of BWR can be closed promptly when it is opened. In Tokai No. 2 Power Plant, a blowout panel closing device was developed to meet this requirement. In this report, we describe the design of blowout panel closing device and report the result of vibration test conducted in E-Defense....
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Development of reactor building blowout panel closing device for Tokai No.2 power station

At Tokai No. 2 Power Station, a special inspection is conducted in line with the application for approval of extension of operating period. In particular, for reactor pressure vessels, ultrasonic flaw inspection is performed on the base metal part of the trunk which has not been inspected during the conventional in-service inspection. For water supply nozzles, we are conducting eddy current flaw detection inspection for low alloy steel, which is the first in Japan. As a result of these inspections, no defec...
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Reactor pressure vessel inspection for extension of operation period at Tokai No. 2 power station