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.

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.

scholarly journals The Fukushima accident was preventable

2015 ◽  
Vol 373 (2053) ◽  
pp. 20140379 ◽  
Author(s):  
Costas Synolakis ◽  
Utku Kânoğlu
Keyword(s):  
Emergency Preparedness ◽  
Nuclear Power ◽  
Hazard Analysis ◽  
Severe Accident ◽  
Regulatory Structure ◽  
Fukushima Accident ◽  
Critical Facilities ◽  
Safety Studies ◽  
New Research ◽  
Large Earthquakes

The 11 March 2011 tsunami was probably the fourth largest in the past 100 years and killed over 15 000 people. The magnitude of the design tsunami triggering earthquake affecting this region of Japan had been grossly underestimated, and the tsunami hit the Fukushima Dai-ichi nuclear power plant (NPP), causing the third most severe accident in an NPP ever. Interestingly, while the Onagawa NPP was also hit by a tsunami of approximately the same height as Dai-ichi, it survived the event ‘remarkably undamaged’. We explain what has been referred to as the cascade of engineering and regulatory failures that led to the Fukushima disaster. One, insufficient attention had been given to evidence of large tsunamis inundating the region earlier, to Japanese research suggestive that large earthquakes could occur anywhere along a subduction zone, and to new research on mega-thrusts since Boxing Day 2004. Two, there were unexplainably different design conditions for NPPs at close distances from each other. Three, the hazard analysis to calculate the maximum probable tsunami at Dai-ichi appeared to have had methodological mistakes, which almost nobody experienced in tsunami engineering would have made. Four, there were substantial inadequacies in the Japan nuclear regulatory structure. The Fukushima accident was preventable, if international best practices and standards had been followed, if there had been international reviews, and had common sense prevailed in the interpretation of pre-existing geological and hydrodynamic findings. Formal standards are needed for evaluating the tsunami vulnerability of NPPs, for specific training of engineers and scientists who perform tsunami computations for emergency preparedness or critical facilities, as well as for regulators who review safety studies.

Analysis of Early Stage Accident at TEPCO’s Fukushima Daiichi NPS

2013 ◽  
Author(s):  
Hiroshi Ono ◽  
Hideo Konishi
Keyword(s):  
Nuclear Power ◽  
Early Stage ◽  
Severe Accident ◽  
Sensitivity Analyses ◽  
System Behavior ◽  
Power Station ◽  
Detailed Simulation ◽  
Fukushima Daiichi ◽  
Relap5 Code ◽  
Plant Control

The operation of the Isolation Condenser (IC) played an important role in the progression of the accident at the unit 1 of Fukushima Daiichi nuclear power station. Analyses of Unit 1 accident in the early stage (prior to the occurrence of core melt) were performed using plant dynamics analysis code RELAP5/MOD31 and the results were compared with measured data. In the RELAP5 code, analysis scope of target is not a severe accident. But, the detailed simulation in the early stage of accident including the plant control system behavior is possible. Moreover, some sensitivity analyses were conducted and the reactor behavior under IC operations was examined.

Application of Level 2 PSA in the Design of Cavity Injection System for Nuclear Power Plant

2018 ◽  
Author(s):  
Wentao Zhu ◽  
Wenjing Li
Keyword(s):  
Decision Making ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Assessment Tool ◽  
Quantitative Risk Assessment ◽  
Severe Accident ◽  
Injection System ◽  
Retention Strategy ◽  
Level 2

After Fukushima nuclear power plant accident, severe accident is getting more and more concerns all over the world. In order to mitigate severe accident and improve the safety of nuclear power plant, two different strategies are applied in different plants. One is in-vessel melt retention strategy, and the other is ex-vessel melt retention strategy. Tianwan nuclear power plant is an improved Gen II nuclear power plant and in-vessel melt retention strategy is adopted in the plant. In order to achieve this strategy, cavity injection system is designed for the plant. Probabilistic Safety Analysis is the most commonly used quantitative risk assessment tool for decision-making in selecting the optimal design among alternative options. For this plant, in order to optimize the design of cavity injection system, improve the safety level of nuclear power plant, and meanwhile, improve the engineering implementation and economization, Level 2 PSA was used for this decision-making process. In this paper, the Level 2 PSA for this plant and the application for the design of cavity injection system are introduced.

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.

Nuclear Power Safety Development and Accident Emergency in China

2012 ◽  
Vol 512-515 ◽  
pp. 2509-2514
Author(s):  
Zi Ying Jiang ◽  
Fan Yu
Keyword(s):  
Emergency Response ◽  
Emergency Preparedness ◽  
Nuclear Power ◽  
Power Development ◽  
Fukushima Accident ◽  
Nuclear Power Development ◽  
History Of ◽  
Potential Risks ◽  
Power Safety ◽  
Safety First

Nuclear power is clean, safe, but not zero risk, which has been evidenced by the history of nuclear power development. Nuclear accident emergency response is the final barrier of depth defense to reduce the potential risks that may arise from nuclear power development, which must be enhanced. The accident emergency preparedness in China and China responses to Fukushima accident are presented. Learning lessons from past nuclear power accidents (the Three Mile Island, Chernobyl and Fukushima), China would be keeping confidence in nuclear power development and advancing further improvement of emergency response capabilities to insist on the safety-first principle for nuclear power development.

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 Assessment of Radiation Doses for Lungs due to Some Radionuclides Released from a Hypothetical Nuclear Power Reactor Accident

2015 ◽  
Vol 17 (1) ◽  
pp. 30-37
Author(s):  
Md Moniruzzaman Khan ◽  
AHM Ruhul Quddus ◽  
Mir Md Akramuzzaman ◽  
Abdus Sattar Mollah
Keyword(s):  
Human Body ◽  
Nuclear Power ◽  
Reactor Core ◽  
Reactor Power ◽  
Dose Effect ◽  
Severe Accident ◽  
Reactor Accident ◽  
Nuclear Power Reactor ◽  
North East ◽  
Sensitive Organ

Different radionuclides are emitted from the reactor core after the nuclear accident. These radionuclides are entered into human body through different pathways, which damage the cells. The dose consequence to the sensitive organ like lungs of human body is considered in the present study to show the dose effect for various radionuclides from a hypothetical nuclear reactor accident. The calculations were made with the in-house developed computer program “RaDARRA”. Cardinal directions like E, ENE, ESE, N, NE, NNE, NNW, NW, S, SE, SSE, SSW, SW, W, WNW and WSW are considered to observe the dose effect along the directions. For the calculations, lungs dose arising from 8 radionuclides e.g., 89Sr, 91Y, 95Zr, 95Nb, 131I, 133I, 140Ba and 144Ce have been considered. Of all these radionuclides the maximum and minimum dose contribution mainly come from 144Ce (30%) and 95Nb (4.43%). It is marked that dose is maximum along North East (NE) direction for all the distances and for all types of the radioisotopes. Methodology used in the present study can also be utilized for any type of severe accident and any type of reactor power. DOI: http://dx.doi.org/10.3329/bjnm.v17i1.22489 Bangladesh J. Nuclear Med. 17(1): 30-37, January 2014

LBLOCA Initiated Emergency Condition Analysis for a China Three-Loop PWR

2018 ◽  
Author(s):  
Wang Ning ◽  
Chen Lei ◽  
Zhang Jiangang ◽  
Yang Yapeng ◽  
Xu Xiaoxiao ◽  
...  
Keyword(s):  
Severe Accident ◽  
Feed Water ◽  
Fukushima Accident ◽  
Flow Paths ◽  
The Core ◽  
Emergency Condition ◽  
Severe Accidents ◽  
Loss Of Coolant Accident ◽  
Station Blackout ◽  
Control Volumes

Great interest in severe accident has been motivated since Fukushima accident, which indicates that the probability of severe accident exists even though it is extremely small. Emergency condition is important in decision making in case of severe accident in NPP. Although many studies have been conducted for severe accident, there was necessary to investigate emergency condition of severe accidents that could possibly happen and haven’t been sufficiently analyzed. Since station blackout (SBO) happened in Fukushima accident, a number of studies in severe accidents initiated by SBO have been carried out. Off-site power is assumed to be lost during large break loss of coolant accident (LBLOCA), but there is few study to find out emergency condition during LBLOCA if both of off-site and on-site power are lost. A hypothetical severe accident initiated by LBLOCA along with SBO in a China three-loop PWR was simulated in the paper using MELCOR code. Emergency condition was obtained including start of core uncover, start of zirconium-water reaction, failure of fuel cladding and failure of the lower head. Thermal-hydraulic response of the core during the accident was also analyzed in the paper. The model for this study consists of 46 control volumes (27 in primary loop, 17 in secondary loop, 1 in containment and 1 in environment) and 52 flow paths. High pressure safety injection (HPSI) and low pressure safety injection (LPSI) are lost because of loss of on-site and off-site power, and simultaneously main feed water and auxiliary feed water of the steam generators are lost for the same reason. The accumulator can inject water into the core since it is passive and doesn’t need any power. Results of the study will be useful in gaining an insight into detailed severe accident emergency condition that could happen in a China three-loop PWR and may provide basis for severe accident mitigation.

Sign in / Sign up

Export Citation Format

Share Document