Study on Description of Plant Status at Fukushima Accident by Emergency Action Level

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Kazufumi Nagashima ◽  
Nakahiro Yasuda
Keyword(s):  
Decision Making ◽  
Emergency Response ◽  
Protective Action ◽  
Severe Accident ◽  
Fukushima Accident ◽  
Reporting Scheme ◽  
Accident Management ◽  
Precautionary Action ◽  
Local Residents ◽  
Potential Improvement

Abstract This paper aims at verifying the current Japanese Emergency Response Guideline, especially the “notification” (reporting) scheme of emergency action level (EAL), through the analysis of the progress of Fukushima nuclear accident. We compared timing and emergency classification between two datasets of the plant statuses which expressed by the old prediction-based notification and the latest EAL-based notification, in order to assess the current EAL scheme along the effectiveness of protective action for the local residents. We observed that the plant statuses expressed by the current EAL-based notification gave more engineering insights in the earliest accident phase to identify the accident scenario. However, potential improvement area of the guideline was also observed in the following severe accident management (SAM) phase after the trigger of first precautionary action, where we are required to reduce uncertainties in both processes of the operator's notification and the government's decision making by evaluating the progression speed of the severe accident.

Study on Description of Plant Status at Fukushima Accident by Emergency Action Level

2018 ◽  
Author(s):  
Kazufumi Nagashima ◽  
Nakahiro Yasuda
Keyword(s):  
Decision Making ◽  
Emergency Response ◽  
Protective Action ◽  
Severe Accident ◽  
Data Sets ◽  
Fukushima Accident ◽  
Accident Management ◽  
Precautionary Action ◽  
Local Residents ◽  
Potential Improvement

This paper aims at verifying the current Japanese Emergency Response Guideline, especially the notification scheme of Emergency Action Level (EAL), through the analysis of the progress of Fukushima nuclear accident. We compared timing and emergency classification between two data sets of the plant statuses which expressed by the old prediction-based notification and the latest EAL-based notification, in order to assess the current EAL scheme along the effectiveness of protective action for the local residents. We observed that the plant statuses expressed by the current EAL-based notification gave more engineering insights in the earliest accident phase. We also identified a potential improvement area of the guideline in the following severe accident management (SAM) phase after the trigger of first precautionary action, where we are required to reduce uncertainties in both processes of the operator’s notification and the government’s decision-making, in order to compensate for the abstention of utilizing predictive information.

Method for Prognosis of LBLOCA Initiated Emergency Condition

2020 ◽  
Author(s):  
Wang Ning ◽  
Wang Renze ◽  
Yang Yapeng ◽  
Feng Zongyang ◽  
Jia Linsheng ◽  
...  
Keyword(s):  
Decision Making ◽  
Emergency Response ◽  
Nuclear Power ◽  
Early Stage ◽  
Severe Accident ◽  
Reactor Accident ◽  
Fukushima Accident ◽  
Conservation Equations ◽  
Emergency Condition ◽  
Loss Of Coolant

Abstract Fukushima accident shows again that the probability of reactor accident exists even though it is extremely small. In case of emergency in nuclear power plant, emergency condition of the reactor plays an important role in decision making. During emergency response, especially early stage of severe accident with large release of radioactive nuclides, decision making for protection actions should be based on emergency condition in NPPs. If emergency condition could be prognosed, more time could be bought for decision making and emergency response. In this paper, method for prognosis of large break loss of coolant (LBLOCA) initiated severe accident progression was established based on transient analysis for M310 reactor. Mass and energy conservation equations are the basis of the method. Separated flow model is used for prognosis of emergency condition for large break loss of coolant accident initiated severe accident. These conservation equations are solved approximately in order to significantly increase calculation speed. The active core is divided into 4 radial rings and 10 axial levels, which means there are 40 cells. Heat transfer calculation in the core is done using four experimental correlations. Based on the method established in this paper, a code using for prognosis of LBLOCA initiated severe accident emergency condition was developed. Research on method for prognosis of other severe accidents are being conducted.

Analysis of Complexity in Nuclear Power Severe Accident Management

1993 ◽  
Vol 37 (4) ◽  
pp. 377-381 ◽  
Author(s):  
Randall J. Mumaw ◽  
Emilie M. Roth ◽  
Isabelle Schoenfeld
Keyword(s):  
Decision Making ◽  
Cognitive Skills ◽  
Nuclear Power ◽  
Human Error ◽  
Severe Accident ◽  
Emergency Operations ◽  
Accident Management ◽  
Potential Sources ◽  
Plant Operations ◽  
Analysis Of Performance

A model of decision making has been developed for nuclear power plant operations and has been previously applied to the analysis of performance during emergency operations. The model was extended to identify the cognitive skills required, the types of complexity that can arise, and the potential for human error in severe accident management (SAM). Twelve SAM scenarios were developed to aid in this analysis. Potential sources of complexity and error are described and illustrated, and implications for training cognitive skills are discussed.

Causes and Radiological Consequences of the Chernobyl and Fukushima Nuclear Accidents

2018 ◽  
Vol 4 (2) ◽  
Author(s):  
L. Sihver ◽  
N. Yasuda
Keyword(s):  
Local Time ◽  
Emergency Response ◽  
Nuclear Power ◽  
Power Plants ◽  
Severe Accident ◽  
Nuclear Accidents ◽  
Emergency Response System ◽  
Response System ◽  
Accident Management ◽  
Fukushima Daiichi

In this paper, the causes and the radiological consequences of the explosion of the Chernobyl reactor occurred at 1:23 a.m. (local time) on Apr. 26, 1986, and of the Fukushima Daiichi nuclear disaster following the huge Tsunami caused by the Great East Japan earthquake at 2.46 p.m. (local time) on Mar. 11, 2011 are discussed. The need for better severe accident management (SAM), and severe accident management guidelines (SAMGs), are essential in order to increase the safety of the existing and future operating nuclear power plants (NPPs). In addition to that, stress tests should, on a regular basis, be performed to assess whether the NPPs can withstand the effects of natural disasters and man-made failures and actions. The differences in safety preparations at the Chernobyl and Fukushima Daiichi will therefore be presented, as well as recommendations concerning improvements of safety culture, decontamination, and disaster planning. The need for a high-level national emergency response system in case of nuclear accidents will be discussed. The emergency response system should include fast alarms, communication between nuclear power plants, nuclear power authorities and the public people, as well as well-prepared and well-established evacuation plans and evacuation zones. The experiences of disaster planning and the development of a new improved emergency response system in Japan will also be presented together with the training and education program, which have been established to ensure that professional rescue workers, including medical staff, fire fighters, and police, as well as the normal populations including patients, have sufficient knowledge about ionizing radiation and are informed about the meaning of radiation risks and safety.

scholarly journals ANYCaRE: a role-playing game to investigate crisis decision-making and communication challenges in weather-related hazards

2019 ◽  
Vol 19 (3) ◽  
pp. 507-533 ◽  
Author(s):  
Galateia Terti ◽  
Isabelle Ruin ◽  
Milan Kalas ◽  
Ilona Láng ◽  
Arnau Cangròs i Alonso ◽  
...  
Keyword(s):  
Decision Making ◽  
Emergency Response ◽  
Protective Action ◽  
Warning System ◽  
Role Playing ◽  
Interdisciplinary Cooperation ◽  
Strong Wind ◽  
First Results ◽  
Communication Challenges ◽  
Role Playing Game

Abstract. This study proposes a role-playing experiment to explore the value of modern impact-based weather forecasts on the decision-making process to (i) issue warnings and manage the official emergency response under uncertainty and (ii) communicate and trigger protective action at different levels of the warning system across Europe. Here, flood or strong-wind game simulations seek to represent the players' realistic uncertainties and dilemmas embedded in the real-time forecasting-warning processes. The game was first tested in two scientific workshops in Finland and France, where European researchers, developers, forecasters and civil protection representatives played the simulations. Two other game sessions were organized afterwards (i) with undergraduate university students in France and (ii) with Finnish stakeholders involved in the management of hazardous weather emergencies. First results indicate that multi-model developments and crowdsourcing tools increase the level of confidence in the decision-making under pressure. We found that the role-playing approach facilitates interdisciplinary cooperation and argumentation on emergency response in a fun and interactive manner. The ANYCaRE experiment was proposed, therefore, as a valuable learning tool to enhance participants' understanding of the complexities and challenges met by various actors in weather-related emergency management.

scholarly journals Perceptions, Uses, and Interpretations of Uncertainty in Current Weather Forecasts by Spanish Undergraduate Students

2021 ◽  
Vol 13 (1) ◽  
pp. 83-94
Author(s):  
I. Gómez ◽  
S. Molina ◽  
J. Olcina ◽  
J. J. Galiana-Merino
Keyword(s):  
Decision Making ◽  
Wind Speed ◽  
Undergraduate Students ◽  
Protective Action ◽  
Precipitation Amount ◽  
Weather Conditions ◽  
Uncertainty Range ◽  
Temperature Forecast ◽  
Probabilistic Forecasts ◽  
Precautionary Action

AbstractThis quantitative study evaluates how 71 Spanish undergraduate students perceive and interpret the uncertainty inherent to deterministic forecasts. It is based on several questions that asked participants what they expect given a forecast presented under the deterministic paradigm for a specific lead time and a particular weather parameter. In this regard, both normal and extreme weather conditions were studied. Students’ responses to the temperature forecast as it is usually presented in the media expect an uncertainty range of ±1°–2°C. For wind speed, uncertainty shows a deviation of ±5–10 km h−1, and the uncertainty range assigned to the precipitation amount shows a deviation of ±30 mm from the specific value provided in a deterministic format. Participants perceive the minimum night temperatures as the least-biased parameter from the deterministic forecast, while the amount of rain is perceived as the most-biased one. In addition, participants were then asked about their probabilistic threshold for taking appropriate precautionary action under distinct decision-making scenarios of temperature, wind speed, and rain. Results indicate that participants have different probabilistic thresholds for taking protective action and that context and presentation influence forecast use. Participants were also asked about the meaning of the probability-of-precipitation (PoP) forecast. Around 40% of responses reformulated the default options, and around 20% selected the correct answer, following previous studies related to this research topic. As a general result, it has been found that participants infer uncertainty into deterministic forecasts, and they are mostly used to take action in the presence of decision-making scenarios. In contrast, more difficulties were found when interpreting probabilistic forecasts.

Innovative Practice of Severe Accidents Measures in CAP1400

2017 ◽  
Author(s):  
Likai Fang ◽  
Xin Liu ◽  
Guobao Shi
Keyword(s):  
Nuclear Power ◽  
Heat Removal ◽  
Severe Accident ◽  
Mitigation Measures ◽  
Spent Fuel ◽  
Fukushima Accident ◽  
Power Sources ◽  
Severe Accidents ◽  
Accident Management ◽  
Accident Conditions

CAP1400 is GenIII passive PWR, which was developed based on Chinese 40 years of experience in nuclear power R&D, construction&operation, as well as introduction and assimilation of AP1000. Severe accidents prevention and mitigation measures were systematically considered during the design and analysis. In order to accommodate high power and further improve the safety of the plant, also considering feedback from Fukushima accident, some innovative measures and design requirements were also applied. Based on the probabilistic&deterministic analysis and engineering judgment, considerable severe accidents scenarios were considered. Both severe accidents initiated at power and shutdown condition were analyzed. Insights were also obtained to decide the challenge to the plant. All known severe accidents phenomena and their treatment were considered in the design. In vessel retention (IVR) was applied as one of the severe accident mitigation measures. To improve the margin of IVR success and verify the heat removal capability through reactor pressure vessel, both design innovative measures and experiments were used. The melt pool behavior and corium pool configuration were also studied by using CFD code and thermodynamic code. Hydrogen risk was mitigated by installation of hydrogen igniters, which were comprised of two serials, and were powered by multiple power sources. To further improve the safety, six extra hydrogen passive recombiners were also added in the containment. Hydrogen risk was analyzed both inside containment and outside containment considering leakage effect. Other severe accident phenomena were also considered by designed or analyzed to show the containment robustness to accommodate it. As one of the Fukushima accident feedback, full scope severe accident management guideline were developed by considering both power condition and shutdown condition, accident management for spent fuel pool was also considered. As the basis of accident management during severe accidents, survivability of equipments and instruments that are necessary in severe accident were assessed and will be further tested and/or analyzed. Such tests will consider severe accident conditions arised from hydrogen combustion.

scholarly journals Analysis of Fuel Criticality during Severe Accidents

2015 ◽  
pp. 3-8
Author(s):  
I. Bilodid ◽  
J. Duspiva
Keyword(s):  
Severe Accident ◽  
Stress Tests ◽  
Fukushima Accident ◽  
Management Guidelines ◽  
Severe Accidents ◽  
Design Basis ◽  
Accident Management ◽  
The World ◽  
Criticality Safety

Interest in the analysis of beyond design basis accidents, involving a combination of several failures with fuel damage, has increased throughout the world after the Fukushima accident. Stress tests were performed at NPPs, and development of severe accident management guidelines was started. These activities necessitated calculations to analyze the probability of beyond design basis accidents and assess their initiating events and consequences. One of the aspects in analysis of beyond design basis accidents is to determine the potential for re-criticality during such accidents. The paper provides results of some criticality safety calculations for VVER reactors performed, in particular, by ÚJV Řež and SSTC NRS experts. It is shown how criticality can occur in different severe accident phases.

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