After Fukushima daiichi nuclear accident, it becomes more important risk communication with the public. In discussions with the public in nuclear safety, communication and discussions on risks that not only nuclear risks also social risks are important. Differences in viewpoints, understanding, and thought about risks become communication difficult. We need to discuss risks fairly, appropriately with the public and reduce total social risks. ...
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For Discussions with the Public for the Safety of Nuclear Power -Discussion with the Public -

There are various leak phenomena in nuclear power plants, such as thermal or vibration fatigue crack, grand of valve, valve sheet, mechanical seal and SG tubes, and so on. In the current power plant, engineers should find such probl ems by annual inspection. But, in case of severe accident, operators should conduct a prompt action without mistake. It is very difficult to do such action with limited information and AM tools. Therefore, authors have conducted to develop online leak rate evaluation method for...
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Development of Online Leak Rate Evaluation Method for Various Leak Phenomena in NPPs

Various leak events have happened in nuclear power plants so far. And plants have bad conditions because of these leakages. Several leak events must be investigated, and we have to prepare these leakages. Like this, systematizing evaluation s of several leak events brings upgrades in regulations or new system of inspections, plans for aging deterioration. By using this method, we know deeper about Fukushima-Daiichi NPP. For example, here, from changes of CV pressure, we can conclude that SB-LOCA was NO...
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Studies about Development of Leak Event Evaluation Method in Nuclear Power Plant

１F accident left various lessons & learn for "nuclear power generation." Lessons from safety assurance in the design and operation of power plants were immediately addressed, and new regulatory standards set requirements and criteria that are said to be "the strictest in the world." In nuclear disaster prevention, we propose the following efforts. Take countermeasures based on "indoor evacuation" in principle. The prefecture governor has the responsibility and authority for crisis management, and operates i...
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New Crisis management on Nuclear Accident

１． はじめに株式会社三菱総合研究所は、経済産業省原子力安全・保安院から、高経年化対策強化基盤整備事業（技術情報基盤の整備等）を受託している。本事業において、弊社は、減肉配管の耐震安全性評価に関する研究を日立GEニュークリア・エナジー株式会社及び株式会社東芝と共同で実施した。本研究は、合理的な評価手法の構築及び設計評価指針の作成からはじまり、平成18年度から平成20年まで3年間実施された。本研究の最終成果は、評価手法・設計評価指針の草案としてとりまとめられた。以下に3年間の成果の紹介を行いたい。２． ......

Particularly, Since the on Fukushima the system Dai-ichi safety assessment accident, the of importance plants in operation, of “system the safety” various has degradation been recognized. aspects with transiti on of time ha been emphasized. Accordingly, functional degradation will be the assessment target, reliability and assessment the changes will in the be made safety on codes the consolidation and the concept of of important safety will functions be dealt under with; a where, system, the not on individ...
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Lessons & Learns from Fukushima Daiichi Accident and New Concept of System Safety on Nuclear Power Plants

The reactor core cooling was lost due to the attack of huge Tsunami and the reactor building was severely damaged by the hydrogen explosion at units of Fukushima Daiichi NPS. Significant amount of radioactivity was released to the environment and broader and longer evacuation of the general public in the vicinity of the NPS was carried out to the extent much more than expected by the former Nuclear Safety Commission. Coupled by the effects of earthquake and tsunami, considerable number of indirect disaster ...
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Failure of Emergency Response around Fukushima NPS and the Further Improvement of Revised Response Procedures

Nuclear piping has various kinds of thermal fatigue failure modes. Main causes of thermal loads are structural responses to fluid temperature changes during plant operation. These phenomena have complex mechanisms and so many patterns, that their problems still occur even though well-known issues. To prevent thermal fatigue due to above thermal loads, the JSME guideline is adopted. Both thermal load and fatigue failure mechanism have been investigated and summarized into the knowledgebase. Based on abo...
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Development of thermal fatigue evaluation methods of piping systems

Since the Fukushima Dai-ichi accident, the importance of “system safety'' has been recognized anew. Particularly, system safety assessment of plants in operation from the various degradation perspectives, specifically, transition of time is very important. Accordingly, functional degradation will be the assessment target of degradation, and the changes in the safety standards and the concept of safety will be dealt with; where, the reliability assessment will be made on the consolidation of important func...
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Study of System Safety Evaluation on LTO of National Project - Functional Degradation and System Safety Assessment of Nuclear Plants in Operation