The Fukushima Daiichi Nuclear Power Plant units 1, 2, and 3 were evaluated to determine whether their safety functions were effective. These units, which were under operation when the Tohoku - Pacific Ocean Earthquake occurred at 14:46 JST on March 11, 2011, were analyzed via a time series evaluation from the time the earthquake occurred to the subsequent tsunami attack. The cooling function of each unit was analyzed and the results show that the cooling functions were effective during the evaluation...
英字タイトル:
Time series evaluation on Fukushima Daiichi NPP units 1/2/3 from Tohoku - Pacific Ocean Earthquake to the tsunami invasion(2)

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

Fort Calhoun NPP(FCNPP) experienced flood due to the elevation of water level of Missouri river from June to August, 2011. FCNPP took various responses including constructing the berm around the important facilities, and could maintain the safety of the reactor with difficulty. The response of FCNPP, which includes both good and bad aspects, will help us in examining the response to flooding at Japanese nuclear plants. In response to the occurrence of the fire of safety related breaker at FCNPP, June ...
英字タイトル:
Response for Flooding and Effort of Plant Restart at Fort Calhoun NPP

Abstract: 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 accidents occurred in Unit 1, 2, 3 and 4. It is said that the height of tsunami attacked Fukushima NPP was more than 14m. After 50 minutes from the automatic shut-down, tsunami attacked the NPPs in Fukushima Daiichi NPPs. For example, the Unit 1 lost A/C power caused the loss of water injection function; it made the core meltdown and unu...
英字タイトル:
Standers and Guidelines should be Rules between Licensees and Regularly

It is very important to enhance safety and stable operation of nuclear power plants through maintenance technologies and human activities. Recent years, the capacity factor of Japanese plant is very low compared with the European and American plants. During a decades, the capacity factor of Japanese plants gett ing worth and worth. The old type of maintenance during annual inspection made to slowdown the development of new type maintenance, such as on line monitori ng and maintenance. Therefore we should d...
英字タイトル:
Obtain Public Trust through Safety and Stable Operation of Nuclear Power Plants by Conducting the Online Maintenance

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

In Fukushima accident on 2011, molten core supposed to be leaked on the concreate floor in containment vessel. Development of small type of core catcher which can be installed in operating nuclear power plant is needed. In this investigation, the thermal deterioration of concreate and Magnesia-Carbon brick observed trough surface observation by microscope and measurement of compressive strength, weight reduction, and difference of void ratio. In addition, permeability measurement for burned concreate was op...
英字タイトル:
Study on Thermal Deterioration of Concreate and Thermal durability of Ceramics

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 installed the heat removal system and filtered containment venting system (FCVS) from the lessons of TMI and Chernobyl Accidents. The new regulatory standard, the filtered vent system (FCVS) should be installed, and prevent the radioactive material in case of the severe accident and the overpressure breakage prevention of a primary co...
英字タイトル:
Development of High Efficiency Filtered Containment Venting System by using AgX

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