Fukushima Daiichi NPP accident would be terminated, if sufficient accident countermeasures, such as water proof door, mobile power, etc. In case of Europe, it had already recommended to install core catcher from the lessons of Chernobyl Accidents. In this paper we introduce simplified core catch by using core catcher that used Basalt. Hokkaido University has tested the simplified core catcher, by using thermite process. We found that molten thermite debris and concrete interaction make concrete to erod...
英字タイトル:
Molten Core Concrete Interaction and Development of Core Catcher

In the Fukushima Daiichi Nuclear Power Plant unit 1, isolation condenser (IC) should play an important role in core cooling during the station blackout. To evaluate cooling capacity of the IC, two phase flow analyses with the TRAC-BF1 code and experiments simulating the IC were conducted. The analyses for the actual BWR indicated that the decay heat could be removed if the IC worked properly at 18:18. However, our results showed that core uncovery occurred at 17:30, which leaded to hydrogen production f...
英字タイトル:
Study on Evaluation of Cooling Capacity of Isolation Condenser in Fukushima Daiichi Unit 1

The water level in the fuel zone is an important parameter to conduct properly accident management. In the Fukushima Daiichi Nuclear Power Plant accident, measurement error of the water level occurred, which was caused by evaporation of water in a reference leg. To measure the water level properly, the reference leg connected to the condensing chamber must be filled with water. We focused on the method called backfill to keep the performance of water level gauge during severe accident. Backfill is applied ...
英字タイトル:
Study on keeping performance of water level gauge under the severe accident.

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

FuNushima Daiichi NPP accident would be terminated, if sufficient accident countermeasures, such as water proof door, mobile power, etc. In case of Europe, it had already installed the heat removal system and filtered containment venting system (FCVS) from the lessons o f TMI and Chernobyl Accidents. Decay heat removal system and CV spray cooling system with FCVS are ensured by using mobile generators and heat exchangers to Neep the ultimate heat sinN even in any natural disaster, such as large earthquaNe,...
英字タイトル:
Development of High Efficiency Filtered Containment Venting System by using AgX

In this study, we aimed to quantitatively evaluate cooling capacity of isolation condenser (IC) for core cooling in FuNushima Daiichi Nuclear Plant Unit 1. In order to evaluate cooling capacity, decay heat em ted from fuels in reactor core was calculated. We used the data of nuclear fuel and rated thermal power which is released by TEPCO. We analyzed IC with TRAC code. We made an experiment in order to checN IC’s input data. Because analysis data is close to experimental data, we made sure validity of inpu...
英字タイトル:
Evaluation on Decay Heat Removal Capability of Isolation Condenser for Depressurization and Cooling System

In this study, we aimed to quantitatively evaluate cooling capacity of isolation condenser (IC) for core cooling in Fukushima Daiichi Nuclear Plant Unit 1. In order to evaluate cooling capacity, we calculated decay heat which was emitted from core. We used the data of nuclear fuel and rated thermal power which is released by TEPCO. Analysis was conducted with TRAC code. We made an experiment in order to check input data for IC. Because analysis data was close to experimental data, we made sure of valid...
英字タイトル:
Study of Easing Severe Accident by Using Isolation Condenser

Wastage phenomena occur when a heat transfer tube is failed in a Steam Generator (SG) of Fast Breeder Reactor (FBR) and its mechanism is still unexplained. We focused on Liquid Droplet Impingement Erosion (LDIE) as a factor of the wastage phenomena and performed a basic study with a partial mock-up water test simulating a piping group in SG for quantitative evaluation of LDIE. First, we did visualization tests of high pressure and high speed jet into water. The test section consists of a failure heat ...
英字タイトル:
Study on Rapid Wastage due to Liquid Droplet Impingement on Heat Transfer Tube in SG of Fast Breeder Reactor