The 2011 off the Pacific coast of Tohoku Pacific Earthquake and the Tsunami gave the serious damage to the Fukushima-Daiichi Nuclear Power Plants (NPPs). The lessons from the accidents, IAEA’s Integrated Regulatory Review Service (IRRS) team conducted review for NRA. The mission provided recommendations and suggestions for improvements in most of the areas covered by the review. include: 1) The NRA should work to attract competent and experienced staff, and enhance staff skills relevant to nuclear and r...
英字タイトル:
Improvement of NRA’s Inspection by IRRS recommendation and Innovative Integrated New Maintenance System for NPPs

Our Company, aims at tracking huge plant parameters (Big Data), managed by Nuclear Power Plants. By application of this Big Data, along with NEC Corporation we developed a system to detect any equipment abnormalities accurately and as much as possible at an early stage. After the implementation of the system, checks of the actual working of the system can be conducted and performance gains enhanced drastically. ...
英字タイトル:
Development of the Plant Monitor System utilized Invariant Analysis Technology and Big Data

During the Fukushima Daiichi Nuclear Power Plant accident, fuels in the each core in units 1, 3 and 2 melted, and the melted core might dropped down into the lower plenum of the RPV. The core debris heated the bottom structure of reactor vessels and dropped down onto the pedestal through the melted pass of the vessel bottom structure. High temperature core debris might attack concrete or PCV bottom. In order to protect core concrete reaction, several types of core catchers were developed, but they are...
英字タイトル:
Study on Compact-Type Core Catcher for Current Nuclear Power Plants

We have developed the prediction monitoring and diagnostic system for the purpose of the early detection of the abnormal behavior of the complicated system like a nuclear power plant. Furthermore, the techniques for the modeling of the relationships between sensors are applied to evaluate the system performance. The developed method is applied to the primary loop recirculation (PLR) pumps and the system performance indicator is calculated. The results are compared with the maintenance record of the PLR p...
英字タイトル:
Application of Prediction Monitoring and Diagnostic System to Plant Performance Evaluation

当社は、発電プラント（島根 2号機）が蓄積している膨大なプラントデータいわゆるビッグデータに着目し、日本電気株式会社（NEC）と共同で、このプラントデータを活用して、設備の異常を可能な限り早い段階で、かつ正確に検知する人工知能（ AI）を開発してきた。この AIはネットワーク障害対応用エンジン（ SIAT（System Invariant Analysis Technology））をプラント監視に応用した異常を早期に検知する予兆監視システムである。2013年には、プロトタイプのシステムによりこれまで蓄積してきた島根 2号機の運転データを用い種々の機能確認を行い、システムの有効性を確認し上で 2014年に島根 2号機に導入、同年運用を開始した。 2015年には 3号機に導入した。図 1に SIATのプラント常時監視画面を示す。図 1に表示されているのは、プラントの主要な系統である。表示の緑は系統が正常に運転中であることを示している。系統内の相関するセンサーデータがいつもと異なる動きをした場合、その相関の崩れの状態により系統表示は、緑（正常）から、黄（注意）、そして赤（異常）に変化し、警報を発報する。...

In the Fukushima daiichi accident, molten core supposed to be leaked from the pressure vessel to the concreate floor in the containment vessel. To keep the integrity of the containment, development of small type of core catcher which can be installed in present nuclear power plant is needed. In this investigation, the thermal deterioration of concreate and Magnesia-Carbon brick was evaluated by the surface observation and the measurements of compressive strength, weight reduction, and difference of void r...
英字タイトル:
Investigation on thermal deterioration of concreate in severe accident