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[en] Goals: – Develop the fundamental scientific basis to understand, predict, and measure changes in materials and systems, structures and components (SSCs) as they age in environments; – Apply this knowledge to develop and demonstrate methods and technologies that support safe and economical long-term operation of existing reactors; – Research new technologies that enhance plant performance, economics, and safety.
[en] This publication results from a technical meeting on phenomenology and technologies relevant to in-vessel melt retention (IVMR) and ex-vessel corium cooling (EVCC). The purpose of the publication is to capture the state of knowledge, at the time of that meeting, related to phenomenology and technologies as well as the challenges and pending issues relevant to IVMR and EVCC for water cooled reactors by summarizing the information provided by the meeting participants in a form useful to practitioners in Member States.
[en] The key to risk management is to make efforts so as not to deviate from the form of 'appropriate safety.' In order to do so, it is essential for the parties concerned to understand and share common safety goals. In addition, the safety goal is also a 'promise with society,' and it should not be understood that safety goals can be objectively derived only by scientific and technological knowledge regardless of the values society has. Based on this recognition, this paper reconsiders the ideal way of safety goals in Japan. (A.O.)
[en] In a hypothetical severe accident in a light water reactor (LWR) the failure of decay heat removal might lead to the destruction of the reactor core. After the reactor pressure vessel has melted through, the molten core of the reactor reaches the concrete basement. This leads to a Molten Core - Concrete Interaction, in which the melting of the concrete starts. In order to assess the safety and the development of the so-called fourth phase of a core decomposition accident, the consequences of such an interaction are of great interest.
[en] The surface tension and the density of the Sn1-xBi-x system with Bi concentrations of 5, 10, and 15 at% have been studied using the lying drop method in a temperature interval of 470–800 K and under a vacuum of 10 Pa. The DROP program is used to obtain experimental values of the studied physical quantities. The addition of bismuth to tin was found to decrease the surface energy of the Sn1-xBix melts. It is also shown that there are linear temperature dependences for the surface tension coefficient and the density of the studied system. (author)
[en] The purpose of the Technical Meeting is to provide a platform for detailed presentations and technical discussions on recent progress in R&D activities on in-vessel melt retention (IVMR) and ex-vessel corium cooling (EVCC) during severe accidents at water-cooled reactors (WCRs).
[en] Conclusion: IVR is one of important severe accident management strategies of CAP1400. The purpose of IVR-ERVC experiments is to obtain CHF at RPV lower head and research its relevant mechanism. IVR-ERVC experiment facility was designed and built with a series of improvements. Insights achieved in IVR-ERVC experiments contribute to IVR evaluation, design improvement and safety review of CAP1400.
[en] In various technical fields of nuclear energy, computer codes are often used for transient simulations of target phenomena. Some of the codes were developed many years ago and have been revised with newly acquired findings, rather than newly developed, because of many encompassed numerical models and complexity of algorithms. In many cases, available outputs for users are output text files and graphs showing temporal variations of parameters, despite diversified and huge number of output information items are posing difficulty to the users in grasping the whole picture of the reproduced phenomena. This report compiles a series of know-hows in building a post-processor software for large simulation codes which serves as an interactive tool for code users in understanding the reproduced consequence with visually understandable information items. These know-hows are acquired through post-processor developments for LWR severe accident simulation codes RELAP/SCDAPSIM and MELCOR. A CD-ROM is attached as an appendix. (J.P.N.)
[en] The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Center of World Intelligence Project for Nuclear Science/Technology and Human Resource Development (hereafter referred to “the Project”) in FY2018. The Project aims to contribute to solving problems in nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the “Development of Semantic Survey Map Building System Using Semi-autonomous Mobile Robots for Surveying of Disaster Area and Gathering of Information in Nuclear Power Station”. The objective of the present study is to research and develop semi-autonomous mobile robot systems (multi-sensor fusion system, semantic simultaneous localization and mapping (SLAM), system for traversable-route learning and safe traversable-route presentation, etc.) that simply, safely, and rapidly make semantic survey maps including multiple information (air dose rate, temperature, obstacles, etc.). The system will be applied to the investigation of the situation inside the building of the nuclear power station where people cannot access at the time of disaster. (author)
[ja]日本原子力研究開発機構(JAEA)廃炉国際共同研究センター(CLADS)では、平成30年度英知を結集した原子力科学技術・人材育成推進事業(以下、「本事業」という)を実施している。本事業は、東京電力ホールディングス福島第一原子力発電所の廃炉等をはじめとした原子力分野の課題解決に貢献するため、国内外の英知を結集し、様々な分野の知見や経験を、従前の機関や分野の壁を越えて緊密に融合・連携させた基礎的・基盤的研究及び人材育成を推進することを目的としている。平成30年度の新規採択課題から実施主体を文部科学省からJAEAに移行することで、JAEAとアカデミアとの連携を強化し、廃炉に資する中長期的な研究開発・人材育成をより安定的かつ継続的に実施する体制を構築した。本研究は、研究課題のうち、平成30年度「被災地探査や原子力発電所建屋内情報収集のための半自律ロボットを用いたセマンティックサーベイマップ生成システムの開発」について取りまとめたものである。本研究の目的は、災害時においてヒトの立ち入りが困難となった原子力発電所建屋内の状況調査を対象に、簡単・安全・迅速に複数種類の情報(空間線量, 温度, 障害物等)を含んだセマンティックサーベイマップを生成する半自律移動ロボットシステムの研究・開発(カメラシステム, セマンティックSLAM, 移動経路学習及び安全な経路提示システム)である。(著者)