Fundamental study on LWR advanced technology to contribute to improvement of scientific rationality for regulation standard, safety margin enlargement for design, and Fukushima NPS decommissioning research.
Towards improvement of evaluation method for core and fuel/material behaviors under every conditions from normal operation to severe accident, based on mechanism evaluation.
Goal is to contribute to improved/enhanced safety performance of LWR.
（1）Fundamental study on fission product behavior
（2）Simulation technology of core degradation behavior
（3）Prediction method of long-term material integrity and characteristics for support to safety and rational LWR decommissioning
Boron carbide is used as control material at Fukushima Daiichi Nuclear Power Plants. Cesium is expected to react with the boron and to be transferred to the reactor building in the form of cesium borates. However, there is little thermodynamic data available in estimation of their transfer behavior. Therefore, we have performed vapor pressure measurements of cesium borates to obtain their thermodynamic data.●Adsorption Behaviors of Cesium on Stainless Steels（Detail）
Knowledge of Cs-deposition properties is essential to evaluate radiation dose of workers at Fukushima Daiichi Nuclear Power Plants from Cs deposits onto the structural materials. However, there is little information on the Cs-adsorption behaviors, especially those for chemisorption that would occur at high temperature. Therefore, we have started the research to elucidate the adsorption mechanism.●Development of Failure Evaluation Methods for the Pressure Vessel Lower Head（Detail）
To gain better awareness of the situation within the reactor pressure vessel (RPV) of the Fukushima Daiichi Nuclear Power Station (1F) and improve the current severe accident (SA) analysis codes, e.g. THALES2 developed by JAEA, we are conducting research and development to assess the rupture behavior of the RPV lower head due to relocation of the molten core. In this study, we are developing a coupled analysis method of thermal-hydraulics (TH) and structural analyses, which are to be applied to the behavior of a molten core and to the thermal-elastic-plastic-creep behavior of the structures, respectively. We are also developing methods for evaluating the failure time and locations of the RPV lower head due to creep-deformation.●The lucture in the internatinal forum commemorating the 30th anniversary of Chernobyl accident（Detail）
We participated "Chornobyl's Legacy for the Nuclear Safety of the World" sponsored by National Academy of Sciences of Ukraine. We have made the technical support to the invited lecture "International Community in Search for International Guarantees of the World Nuclear Safety" by the Special Advisor to the JAEA President Sakata. The need for global cooperation for the enhanced nuclear safety was adopted as the official declaration of the forum.
(Forum URL http://icd.kpi.ua/)
※You can search and browse research results of our group by JAEA Orignated Papers Searching System（JOPSS）
Japan Atomic Energy Agency
Nuclear Science & Engineering Center
LWR Key Technology Development Division
Development Group for LWR Advanced technology
1st Laboratory building-311, Nuclear Science and Engineering Institute
2-4 Shirane Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
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