Analysis of Temporary Cooling Strategy for CPR1000 Power Plant Under Situation Similar to Fukushima Severe Accident

2013 ◽  
Author(s):  
Dongyu He ◽  
Xing Chen ◽  
Jiming Lin
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Tohoku Earthquake ◽  
Severe Accident ◽  
Fukushima Accident ◽  
Injection Strategy ◽  
Equipment Failures ◽  
Weak Points ◽  
Cooling Ability

The Fukushima Daiichi nuclear accident was a series of equipment failures, nuclear meltdowns, and releases of radioactive materials at the Fukushima I Nuclear Power Plant, following the Tōhoku earthquake and tsunami on 11 March 2011. According to the cause and process of Fukushima severe accident, several possible scenarios for CPR1000 nuclear power plant were analyzed in this paper, under the assumed situation similar to Fukushima severe accident, with the severe accident analysis code MAAP4. According to the analysis results, several weak points of CPR1000 power plant under situation similar to Fukushima accident were found. The electric power and cooling ability for CPR1000 power plant appear to be most important factors under such accident. Then, several temporary cooling strategies for CPR1000 power plant were suggested, including ASG water supply strategy, temporary injection strategy for primary loop, temporary injection strategy for secondary loop, which would improve the safety of CPR1000 power plant under the situation similar to Fukushima accident. At the last, assessments of effectiveness for these strategies were performed, and the results were compared with analysis without these strategies. The comparisons showed that correctly actions of these strategies would effectively prevent the accident process of CPR1000 power plant under situation similar to Fukushima accident.

Investigating the Gap Between Actual and Perceived Distance from a Nuclear Power Plant: A Case Study in Japan

2015 ◽  
Vol 10 (4) ◽  
pp. 627-634 ◽  
Author(s):  
Takaaki Kato ◽  
◽  
Shogo Takahara ◽  
Toshimitsu Homma ◽  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Tohoku Earthquake ◽  
Personal Attributes ◽  
Fukushima Accident ◽  
Straight Line ◽  
Straight Line Distance ◽  
Accident Response ◽  
Straight Lines

This study investigates factors in gaps between perceived and actual straight-line distance to Japan’s Kashiwazaki-Kariwa nuclear power plant (KKNPP). The distance to areas in the official accident response plan is defined using straight lines from the NPP, making it important to determine whether area residents understand these distances correctly. Adults living in the two municipalities cohosting the NPP were surveyed randomly in 2005, 2010 and 2011. In this study, we consider three groups of factors — geographical features, personal attributes, and experience in events highlighting nuclear safety. The Niigata-ken Chuetsu-oki earthquake hit the NPP between the first and second of these three surveys, and the Tohoku earthquake and the March 2011 Fukushima nuclear accident occurred between the second and the third surveys. Before the Fukushima accident, overestimations of straight-line distance were common among respondents, and geographical features such as lack of NPP visibility aggravated bias between actual and perceived distance. After the Fukushima accident, underestimation of the distance became common and personal attributes became more influential as the factor of the perceived-actual distance gap.

Phenomenological Analysis of Melt Progression in LWRS: Proposal of an In-Vessel Corium Progression Scenario in the Unit 1 of Fukushima Dai-ichi Nuclear Power Plant

2016 ◽  
Vol 2 (4) ◽  
Author(s):  
Payot Frédéric ◽  
Seiler Jean-Marie
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Large Scale ◽  
Initial Conditions ◽  
Physical Models ◽  
Severe Accident ◽  
Fukushima Accident ◽  
Support Plate ◽  
The Core

In the field of severe accident, the description of corium progression events is mainly carried out using integral calculation codes. However, these tools are usually based on bounding assumptions because of the high complexity of phenomena. The limitations associated with bounding situations [1] (e.g., steady-state situations and instantaneous whole core relocation in the lower head) led CEA to develop an alternative approach to improve the phenomenological description of the melt progression. The methodology used to describe the corium progression was designed to cover the accidental situations from the core meltdown to the molten core–concrete interaction (MCCI). This phenomenological approach is based on the available data (including learnings from TMI-2) on physical models and knowledge about the corium behavior. It provides emerging trends and best-estimate intermediate situations. As different phenomena are unknown, but strongly coupled, uncertainties at large scale for the reactor application must be taken into account. Furthermore, the analysis is complicated by the fact that these configurations are most probably three-dimensional (3D), all the more so because 3D effects are expected to have significant consequences for the corium progression and the resulting vessel failure. Such an analysis of the in-vessel melt progression was carried out for the Unit 1 of the Fukushima Dai-ichi Nuclear Power Plant. The core uncovering kinetics governs the core degradation and impacts the appearance of the first molten corium inside the core. The initial conditions used to carry out this analysis are based on the available results derived from codes such as the MELCOR calculation code [2]. The core degradation could then follow different ways: (1) Axial progression of the debris and the molten fuel through the lower support plate, or (2) lateral progression of the molten fuel through the shroud. On the basis of the Bali program results [3] and the TMI-2 accident observations [4], this work is focused on the consequences of a lateral melt progression (not excluding an axial progression through the support plate). Analysis of the events and the associated time sequence will be detailed. Besides, this analysis identifies some number of issues. Random calculations and statistical analysis of the results could be performed with calculation codes such as LEONAR–PROCOR codes [5]. This work was presented in the frame of the OECD/NEA/CSNI Benchmark Study of the Accident at the Fukushima Dai-ichi Nuclear Power Station (BSAF) project [6]. During the years of 2012 and 2014, the purpose of this project was both to study, by means of severe accident codes, the Fukushima accident in the three crippled units, until 6 days from the reactor shutdown, and to give information about, in particular, the location and composition of core debris.

scholarly journals Consecutive sexual maturation observed in a rock shell population in the vicinity of the Fukushima Daiichi Nuclear Power Plant, Japan

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Toshihiro Horiguchi ◽  
Kayoko Kawamura ◽  
Yasuhiko Ohta
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Sexual Maturation ◽  
Nuclear Power ◽  
Tohoku Earthquake ◽  
Site Specific ◽  
Thais Clavigera ◽  
Rock Shell ◽  
Fukushima Daiichi ◽  
A Site

AbstractIn 2012, after the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) that followed the Tohoku earthquake and tsunami in March 2011, no rock shell (Thais clavigera; currently recognized as Reishia clavigera; Gastropoda, Neogastropoda, Muricidae) specimens were found near the plant from Hirono to Futaba Beach (a distance of approximately 30 km). In July 2016, however, rock shells were again found to inhabit the area. From April 2017 to May 2019, we collected rock shell specimens monthly at two sites near the FDNPP (Okuma and Tomioka) and at a reference site ~ 120 km south of the FDNPP (Hiraiso). We examined the gonads of the specimens histologically to evaluate their reproductive cycle and sexual maturation. The gonads of the rock shells collected at Okuma, ~ 1 km south of the FDNPP, exhibited consecutive sexual maturation during the 2 years from April 2017 to May 2019, whereas sexual maturation of the gonads of specimens collected at Hiraiso was observed only in summer. The consecutive sexual maturation of the gonads of the specimens collected at Okuma might not represent a temporary phenomenon but rather a site-specific phenotype, possibly caused by specific environmental factors near the FDNPP.

scholarly journals Estimation of Dietary Intake of Radionuclides and Effectiveness of Regulation after the Fukushima Accident and in Virtual Nuclear Power Plant Accident Scenarios

2018 ◽  
Vol 15 (8) ◽  
pp. 1589 ◽  
Author(s):  
Michio Murakami ◽  
Takao Nirasawa ◽  
Takao Yoshikane ◽  
Keisuke Sueki ◽  
Kimikazu Sasa ◽  
...  
Keyword(s):  
Cost Effectiveness ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Dietary Intake ◽  
Emergency Preparedness ◽  
Nuclear Power ◽  
Food Distribution ◽  
Fukushima Accident ◽  
Accident Scenarios ◽  
Effectiveness Of Regulation

Evaluation of radiation exposure from diet is necessary under the assumption of a virtual accident as a part of emergency preparedness. Here, we developed a model with complete consideration of the regional food trade using deposition data simulated by a transport model, and estimated the dietary intake of radionuclides and the effectiveness of regulation (e.g., restrictions on the distribution of foods) after the Fukushima accident and in virtual accident scenarios. We also evaluated the dilution factors (i.e., ratios of contaminated foods to consumed foods) and cost-effectiveness of regulation as basic information for setting regulatory values. The doses estimated under actual emission conditions were generally consistent with those observed in food-duplicate and market-basket surveys within a factor of three. Regulation of restricted food distribution resulted in reductions in the doses of 54–65% in the nearest large city to the nuclear power plant. The dilution factors under actual emission conditions were 4.4% for radioiodine and 2.7% for radiocesium, which are ~20 times lower than those used in the Japanese provisional regulation values after the Fukushima accident. Strict regulation worsened the cost-effectiveness for both radionuclides. This study highlights the significance and utility of the developed model for a risk analysis of emergency preparedness and regulation.

Research and Software Implementation of Seismic Probabilistic Safety Analysis Quantification Method

2017 ◽  
Author(s):  
Wei Gao ◽  
Guofeng Tang ◽  
Jingyu Zhang ◽  
Qinfang Zhang
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Fragility Curves ◽  
Safety Analysis ◽  
Fukushima Accident ◽  
Binary Decision ◽  
Plant Level ◽  
Accurate Quantification ◽  
Probabilistic Safety

Seismic risk of nuclear power plant has drawn increasing attention after Fukushima accident. An intensive study has been carried out in this paper, including sampling of component and structure fragility based on Monte Carlo method, fragility analysis on system or plant level, convolution of seismic hazard curves and fragility curves. To derive more accurate quantification results, the binary decision diagram (BDD) algorithm was introduced into the quantification process, which effectively reduces the deficiency of the conventional method on coping with large probability events and negated logic. Seismic Probabilistic Safety Analysis (PSA/PRA) quantification software was developed based on algorithms discussed in this paper. Tests and application has been made for this software with a specific nuclear power plant seismic PSA model. The results show that this software is effective on seismic PSA quantification.

Analysis of Inertization Strategies for the Filtered Containment Venting System in Cofrentes Nuclear Power Plant

2018 ◽  
Vol 4 (3) ◽  
Author(s):  
Kevin Fernández-Cosials ◽  
Gonzalo Jiménez ◽  
César Serrano ◽  
Luisa Ibáñez ◽  
Ángel Peinado
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Computational Model ◽  
Nuclear Power ◽  
Inert Atmosphere ◽  
Severe Accident ◽  
Nitrogen Injection

During a severe accident (SA) in a nuclear power plant (NPP), there are several challenges that need to be faced. To coup with a containment overpressure, the venting action will lower the pressure but it will release radioactivity to the environment. In order to reduce the radioactivity released, a filtered containment venting system (FCVS) can be used to retain iodine and aerosols radioactive releases coming from the containment atmosphere. However, during a SA, large quantities of hydrogen can also be generated. Hydrogen reacts violently with oxygen and its combustion could impair systems, components, or structures. For this reason, to protect the integrity of the FCVS against hydrogen explosions, an inertization system is found necessary. This system should create an inert atmosphere previous to any containment venting that impedes the contact of hydrogen and oxygen. In this paper, the inertization system for Cofrentes NPP is presented. It consists of a nitrogen injection located in three different points. A computational model of the FCVS as well as the inertization system has been created. The results show that if the nitrogen sweeps and the containment venting are properly synchronized, the hydrogen risk could be reduced to a minimum and therefore, the integrity of the FCVS would be preserved.

Characterization of Atmospheric Radiological Dispersion Alongside Risky Location Designation and Shelter House Proposition Around the Planned Rooppur Nuclear Power Plant

2020 ◽  
Vol 6 (4) ◽  
Author(s):  
Afrida Fairuz ◽  
Md. Hossain Sahadath
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Arrival Time ◽  
Educational Institution ◽  
Fukushima Accident ◽  
Stability Class ◽  
Medical Centers ◽  
Commercial Area ◽  
The Stability

Abstract The prevailing meteorological conditions around the site of the proposed Rooppur Nuclear Power Plant have been studied vigorously. The in-depth perusal has revealed the existence of three seasons—summer, rainy, and winter with stability classes A, B, and A, respectively, during the day and F during the night. The eventual wind speed and direction of the seasons have been observed. Subsequent locations along the dispersion directions have been identified using googleearthpro, which includes highways, educational institution, medical centers, commercial area, etc. Dose contours corresponding to a source term equivalent to Fukushima accident have been created to verify the dispersion direction and perceive the plume arrival time in the designated locations using health physics code HotSpot. Strong dependency of plume arrival time on the stability classes has been observed, and lowest values are found for F stability class. Finally, some shelter houses are proposed to accommodate endangered inhabitants during emergency.

Estimation of Radiological Consequences at a Proposed Nuclear Power Plant Site Using Atmospheric Dispersion Code

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Kwame Gyamfi ◽  
Sylvester Attakorah Birikorang ◽  
Emmanuel Ampomah-Amoako ◽  
John Justice Fletcher
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Atmospheric Dispersion ◽  
Atmospheric Stability ◽  
Assessment System ◽  
Severe Accident ◽  
Dispersion Modeling ◽  
Stability Class ◽  
Total Effective Dose Equivalent

Abstract Atmospheric dispersion modeling and radiation dose calculation have been performed for a generic 1000 MW water-water energy reactor (VVER-1000) assuming a hypothetical loss of coolant accident (LOCA). Atmospheric dispersion code, International Radiological Assessment System (InterRAS), was employed to estimate the radiological consequences of a severe accident at a proposed nuclear power plant (NPP) site. The total effective dose equivalent (TEDE) and the ground deposition were calculated for various atmospheric stability classes, A to F, with the site-specific averaged meteorological conditions. From the analysis, 3.7×10−1 Sv was estimated as the maximum TEDE corresponding to a downwind distance of 0.1 km within the dominating atmospheric stability class (class A) of the proposed site. The intervention distance for evacuation (50 mSv) and sheltering (10 mSv) were estimated for different stability classes at different distances. The intervention area for evacuation ended at 0.5 km and that for sheltering at 1.5 km. The results from the study show that designated area for public occupancy will not be affected since the estimated doses were below the annual regulatory limits of 1 mSv.

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