An approach toward evaluation of long-term fission product distributions in the Fukushima Daiichi nuclear power plant after the severe accident

2021 ◽  
pp. 111256
Author(s):  
Shunsuke Uchida ◽  
Hidetoshi Karasawa ◽  
Chiaki Kino ◽  
Marco Pellegrini ◽  
Masanori Naitoh ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Fission Product ◽  
Nuclear Power ◽  
Severe Accident ◽  
Product Distributions ◽  
Fukushima Daiichi

scholarly journals Long-Term Aging of Chernobyl Fuel Debris: Corium and “Lava”

2021 ◽  
Vol 13 (3) ◽  
pp. 1073
Author(s):  
Bella Zubekhina ◽  
Boris Burakov ◽  
Ekaterina Silanteva ◽  
Yuri Petrov ◽  
Vasiliy Yapaskurt ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Mass Loss ◽  
Nuclear Power ◽  
Distilled Water ◽  
Chemical Alteration ◽  
Laboratory Conditions ◽  
Fukushima Daiichi ◽  
Important Basis

Samples of Chernobyl fuel debris, including massive corium and “lava” were collected inside the Chernobyl “Sarcophagus” or “Shelter” in 1990, transported to Leningrad (St. Petersburg) and stored under laboratory conditions for many years. In 2011 aged samples were visually re-examined and it was confirmed that most of them remained intact, although some evidence of self-destruction and chemical alteration were clearly observed. Selected samples of corium and “lava” were affected by static leaching at temperatures of 25, 90 and 150 °C in distilled water. A normalized Pu mass loss (NLPu) from corium samples after 140 days was noted to be 0.5 g/m2 at 25 °C and 1.1 g/m2 at 90 °C. For “lava” samples NLPu was 2.2–2.3 g/m2 at 90 °C for 140 days. The formation of secondary uranyl phases on the surface of corium and “lava” samples altered at 150 °C was confirmed. The results obtained are considered as an important basis for the simulation of fuel debris aging at Fukushima Daiichi nuclear power plant (NPP).

Accident Analysis of Fukushima Daiichi Nuclear Power Plant Unit 2 by the SAMPSON Severe Accident Code

2014 ◽  
Author(s):  
Atsuo Takahashi ◽  
Marco Pellegrini ◽  
Hideo Mizouchi ◽  
Hiroaki Suzuki ◽  
Masanori Naitoh
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Cooling System ◽  
Severe Accident ◽  
Accident Analysis ◽  
Unknown Boundary ◽  
Long Time ◽  
Fukushima Daiichi ◽  
Nuclear Power Plant Unit

The transient process of the accident at the Fukushima Daiichi Nuclear Power Plant Unit 2 was analyzed by the severe accident analysis code, SAMPSON. One of the characteristic phenomena in Unit 2 is that the reactor core isolation cooling system (RCIC) worked for an unexpectedly long time (about 70 h) without batteries and consequently core damage was delayed when compared to Units 1 and 3. The mechanism of how the RCIC worked such a long time is thought to be due to balance between injected water from the RCIC pump and the supplied mixture of steam and water sent to the RCIC turbine. To confirm the RCIC working conditions and reproduce the measured plant properties, such as pressure and water level in the pressure vessel, we introduced a two-phase turbine driven pump model into SAMPSON. In the model, mass flow rate of water injected by the RCIC was calculated through turbine efficiency degradation the originated from the mixture of steam and water flowing to the RCIC turbine. To reproduce the drywell pressure, we assumed that the torus room was flooded by the tsunami and heat was removed from the suppression chamber to the sea water. Although uncertainties, mainly regarding behavior of debris, still remain because of unknown boundary conditions, such as alternative water injection by fire trucks, simulation results by SAMPSON agreed well with the measured values for several days after the scram.

scholarly journals Birth Outcomes after the Fukushima Daiichi Nuclear Power Plant Disaster: A Long-Term Retrospective Study

2017 ◽  
Vol 14 (5) ◽  
pp. 542 ◽  
Author(s):  
Claire Leppold ◽  
Shuhei Nomura ◽  
Toyoaki Sawano ◽  
Akihiko Ozaki ◽  
Masaharu Tsubokura ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Birth Outcomes ◽  
Nuclear Power ◽  
Fukushima Daiichi

scholarly journals Radiological protection challenges facing business activities affected by a nuclear accident: some lessons from the management of the accident at the Fukushima-Daiichi Nuclear Power Plant

2021 ◽  
Author(s):  
T. Schneider ◽  
J. Lochard ◽  
M. Maître ◽  
N. Ban ◽  
P. Croüail ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Radiological Protection ◽  
Economic Activities ◽  
Protective Actions ◽  
Radiological Monitoring ◽  
Fukushima Daiichi

Lessons from the Fukushima-Daiichi nuclear power plant accident emphasize the difficulties for restoring the socio-economic activities in the affected areas. Among them, a series of radioligical protection challenges were noted, in particular concerning the protection of employees, the securing of the production and the guarantee provided to consumers of the radiological monitoring of products to restore their confidence. Based on case studies reporting the experience of employers deploying their activities in affected areas, an analysis of these radiological protection challenges has been performed. Characterizing the radiological situation was not always straightforward for the managers. With the help of radiological protection experts, protective actions have been identified and specific efforts have been devoted to provide information to employees and their families helping them to make their own judgement about the radiological situation. Respecting the decisions of employees and developing a radiological protection culture among them have proved to be efficient for restoring the business activities. Continuing or restoring the production not always manageable. It requires to develop dedicated radiological monitoring processes to ensure the radiological protection of workers and the quality of the production. Re-establishing the link with the consumers and organising the vigilance on the long-term were necessary for companies to maintain their production or develop new ones. Deploying a socio-economic programme for ensuring the community resilience in affected areas requires the adoption of governance mechanisms respecting ethical values to ensure the overall objective of protecting people and the environment against the risks of ionizing radiation and contributing to provide decent living and working conditions to the affected communities. It is of primary importance to rely on the involvement of local communities in the elaboration and deployment of the socio-economic activities with due considerations for ensuring the integrity of the communities, and respecting their choices.

scholarly journals The Fukushima Daiichi Nuclear Power Plant accident and school bullying of affected children and adolescents: the need for continuous radiation education

2018 ◽  
Vol 59 (3) ◽  
pp. 381-384 ◽  
Author(s):  
Toyoaki Sawano ◽  
Yoshitaka Nishikawa ◽  
Akihiko Ozaki ◽  
Claire Leppold ◽  
Masaharu Tsubokura
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Radiation Effects ◽  
School Bullying ◽  
Nuclear Power Plant Accident ◽  
Fukushima Daiichi ◽  
Effects Of Radiation ◽  
Radiation Education

Abstract The health threats of radiation-release incidents are diverse and long term. In addition to direct radiation effects, it is imperative to manage the indirect effects of radiation such as stigma, prejudice and broader mental health impacts. Six years after the Fukushima Daiichi Nuclear Power Plant accident of March 2011, bullying caused by stigma and prejudice toward evacuees, including children, has become a social problem in Japan. This phenomenon may be associated with the fact that knowledge about radiation has still not reached the general public, and to a potential lack of motivation among Japanese citizens to learn about radiation and bullying. Continuous and sustained education regarding radiation is warranted in order to enhance the general knowledge level about the effects of radiation in Japan after the Fukushima Daiichi Nuclear Power Plant accident, and this education will become an important reference for education after future nuclear disasters.

Study on the Application of CDAG Methodology in EPR Nuclear Power Plant

2017 ◽  
Author(s):  
Yin Yuhao ◽  
Huang Yichao ◽  
Zhao Feng
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Fission Product ◽  
Damage Assessment ◽  
Nuclear Power ◽  
Severe Accident ◽  
Core Damage ◽  
Calculation Results ◽  
Design Characteristics ◽  
European Nuclear

The Westinghouse Owners Group Core Damage Assessment Guidance (CDAG), which has been authorized by the NRC staffs, is now used by licensee emergency response organization staff for estimating the extent of core damage that may have occurred during an accident at a Westinghouse nuclear power plant. On the other hand, EPR is a 3rd generation nuclear power plant, which applies the advanced European nuclear power technology. This paper introduced Core Damage Assessment Guidance methodology in detail. The CDAG methodology is then attempted to apply to the EPR nuclear power plant. Detailed calculations have been performed for the setpoints of containment radiation monitors (CRM) and core exit thermocouples (CETs) with EPR design characteristics, which are the two main methods for estimation core damage amount. This paper also focuses the discussion on the reasons of difference of core damage estimating results between CRM method and CETs method; based on the discussion, several advices are provided when the two methods show a reasonable discrepancy in conclusions. Several conclusions can be made from the discussions in this article that 1)the Westinghouse Owners Group CDAG methodology proved to be reasonable when applied to EPR power plant for core damage assessment under severe accident; 2) the CDAG methodology which reflect the latest understanding of fission product behavior, is very simple and timely for core damage assessment based on NPP (nuclear power plant) real-time parameters; 3) conservative calculation results of setpoints on CRM and CETs based on EPR design show a reasonable trend and range; 4) it is concluded that several factors such as the releasing way, RCS fission product retention, fuel burnups might have great impact on the estimating results, when the results from two main indications (CRM and CETs) show an unexpected response.

scholarly journals Optimizing long-term monitoring of radiation air-dose rates after the Fukushima Daiichi Nuclear Power Plant

2020 ◽  
Vol 220-221 ◽  
pp. 106281 ◽  
Author(s):  
Dajie Sun ◽  
Haruko M. Wainwright ◽  
Carlos A. Oroza ◽  
Akiyuki Seki ◽  
Satoshi Mikami ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Dose Rates ◽  
Long Term Monitoring ◽  
Fukushima Daiichi ◽  
Term Monitoring

What Could Have Saved Fukushima From Its Severe Accident

2018 ◽  
Author(s):  
Kenji Iino ◽  
Ritsuo Yoshioka ◽  
Masao Fuchigami ◽  
Masayuki Nakao
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
High Voltage ◽  
Nuclear Power ◽  
Radioactive Material ◽  
Severe Accident ◽  
Study Group ◽  
Tsunami Waves ◽  
Ac Power ◽  
Fukushima Daiichi

The Great East Japan Earthquake on March 11, 2011 triggered huge tsunami waves that attacked Fukushima Daiichi Nuclear Power Plant (Fukushima-1). Units 1, 3, and 4 had hydrogen explosions. Units 1, 2, and 3 had core meltdowns and released a large amount of radioactive material. Published investigation reports did not explain how the severity of the accident could have been prevented. We formed a study group to find what preparations at Fukushima-1 could have avoided the severity of the accident. We concluded that the severity could have been avoided if the plant had prepared a set of equipment, and had exercised actions to take against such tsunami. Necessary preparation included (1) A number of DC batteries, (2) Portable underwater pumps, (3) Portable AC generators with sufficient gasoline supply, (4) High voltage AC power trucks, and (5) Drills against extended loss of all electric power and seawater pumps. The most important preparation was item (5), i.e., to study plans and carry out exercises against huge tsunami. That alone would have identified all other necessary preparations.

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