scholarly journals Investigation of the Unit-1 nuclear reactor of Fukushima Daiichi by cosmic muon radiography

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
Hirofumi Fujii ◽  
Kazuhiko Hara ◽  
Kohei Hayashi ◽  
Hidekazu Kakuno ◽  
Hideyo Kodama ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Pressure Vessel ◽  
Nuclear Power ◽  
Fuel Loading ◽  
Concrete Wall ◽  
Cosmic Muon ◽  
Muon Radiography ◽  
Fuel Assemblies ◽  
Reactor Building ◽  
Fukushima Daiichi

Abstract We have investigated the status of the nuclear fuel assemblies in the Unit-1 reactor of the Fukushima Daiichi nuclear power plant by cosmic muon radiography. In this study, muon tracking detectors were placed outside the reactor building. We succeeded in identifying the inner structure of the reactor complex, such as the reactor containment vessel, pressure vessel, and other structures of the reactor building, through the concrete wall of the reactor building. We found that a large number of fuel assemblies were missing in the original fuel loading zone inside the pressure vessel. The natural interpretation is that most of the nuclear fuel was melted and dropped down to the bottom of the pressure vessel or even below.

scholarly journals Investigation of the Status of Unit 2 Nuclear Reactor of the Fukushima Daiichi by the Cosmic Muon Radiography

2020 ◽  
Author(s):  
Hirofumi Fujii ◽  
Kazuhiko Hara ◽  
Shugo Hashimoto ◽  
Kohei Hayashi ◽  
Hidekazu Kakuno ◽  
...  
Keyword(s):  
Pressure Vessel ◽  
Nuclear Power ◽  
Nuclear Reactor ◽  
Fuel Loading ◽  
Concrete Wall ◽  
Cosmic Muon ◽  
Muon Radiography ◽  
Reactor Building ◽  
The Status ◽  
Fukushima Daiichi

Abstract We have investigated the status of the nuclear debris in the Unit-2 Nuclear Reactor of the Fukushima Daiichi Nuclear Power plant by the method called Cosmic Muon Radiography. In this measurement, the muon detector was placed outside of the reactor building as was the case of the measurement for the Unit-1 Reactor. Compared to the previous measurements, the detector was down-sized, which made us possible to locate it closer to the reactor and to investigate especially the lower part of the fuel loading zone. We identified the inner structures of the reactor such as the containment vessel, pressure vessel and other objects through the thick concrete wall of the reactor building. Furthermore, the observation showed existence of heavy material at the bottom of the pressure vessel, which can be interpreted as the debris of melted nuclear fuel dropped from the loading zone.

scholarly journals Detection of alpha particle emitters originating from nuclear fuel inside reactor building of Fukushima Daiichi Nuclear Power Plant

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yuki Morishita ◽  
Tatsuo Torii ◽  
Hiroshi Usami ◽  
Hiroyuki Kikuchi ◽  
Wataru Utsugi ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Fuel ◽  
Alpha Particle ◽  
Nuclear Power ◽  
Reactor Building ◽  
Fukushima Daiichi

scholarly journals Approaches to Safety Justification for Loading of VSC-VVER Containers in ZNPP DSFSF

2019 ◽  
pp. 82-87
Author(s):  
Ya. Kostiushko ◽  
O. Dudka ◽  
Yu. Kovbasenko ◽  
A. Shepitchak
Keyword(s):  
Nuclear Fuel ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Spent Nuclear Fuel ◽  
Operating Conditions ◽  
Spent Fuel ◽  
Fuel Assemblies ◽  
Fuel Storage ◽  
The Government

The introduction of new fuel for nuclear power plants in Ukraine is related to obtaining a relevant license from the regulatory authority for nuclear and radiation safety of Ukraine. The same approach is used for spent nuclear fuel (SNF) management system. The dry spent fuel storage facility (DSFSF) is the first nuclear facility created for intermediate dry storage of SNF in Ukraine. According to the design based on dry ventilated container storage technology by Sierra Nuclear Corporation and Duke Engineering and Services, ventilated storage containers (VSC-VVER) filled with SNF of VVER-1000 are used, which are located on a special open concrete site. Containers VSC-VVER are modernized VSC-24 containers customized for hexagonal VVER-1000 spent fuel assemblies. The storage safety assessment methodology was created and improved directly during the licensing process. In addition, in accordance with the Energy Strategy of Ukraine up to 2035, one of the key task is the further diversification of nuclear fuel suppliers. Within the framework of the Executive Agreement between the Government of Ukraine and the U.S. Government, activities have been underway since 2000 on the introduction of Westinghouse fuel. The purpose of this project is to develop, supply and qualify alternative nuclear fuel compatible with fuel produced in Russia for Ukrainian NPPs. In addition, a supplementary approach to safety analysis report is being developed to justify feasibility of loading new fuel into the DSFSF containers. The stated results should demonstrate the fulfillment of design criteria under normal operating conditions, abnormal conditions and design-basis accidents of DSFSF components.  Thus, the paper highlights both the main problems of DSFSF licensing and obtaining permission for placing new fuel types in DSFSF.

Research for Crossing Strait Transportation Accident of Nuclear Fuel Assemblies

2013 ◽  
Author(s):  
Xiaoxiao Xu ◽  
Xuexin Wang ◽  
Jiangang Zhang ◽  
Chaoduan Li ◽  
Gao Fan ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Fuel ◽  
Nuclear Power ◽  
Hainan Island ◽  
Radioactive Material ◽  
Sea Transport ◽  
Fuel Assemblies ◽  
Qiongzhou Strait ◽  
Transport Accidents

Hainan nuclear power plant (HNPP) is the first nuclear power plant built on China’s Hainan Island. Therefore the nuclear fuel assemblies must transport through the Qiongzhou Strait. There are two transportation plans to be used in crossing strait transportation of the fuel assemblies. One plan is railway ferry stretching across sea; the other is road vehicular crossing strait on roll-on/roll-off (Ro/Ro) ships. According to crossing strait transportation scenario and statistical analysis of sea transport accidents in Qiongzhou Strait, three ferrying transportation accidents are considered in this paper. Through research of ship-to-ship collision, fire and sunk, the following conclusions: Collision, fire or foundered are not caused by the leakage of radioactive material, the environmental impact is very small. The accident hazards of crossing strait transportation does not lie in the radiological consequences, but in the effects of public psychology and international repercussions.

scholarly journals Preliminary Assessment of Criticality Safety Constraints for Swiss Spent Nuclear Fuel Loading in Disposal Canisters

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 494
Author(s):  
Alexander Vasiliev ◽  
Jose Herrero ◽  
Marco Pecchia ◽  
Dimitri Rochman ◽  
Hakim Ferroukhi ◽  
...  
Keyword(s):  
Fuel Assembly ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Operating Conditions ◽  
Design Parameters ◽  
Fuel Loading ◽  
Pressurized Water ◽  
Fuel Assemblies ◽  
National Cooperative ◽  
Criticality Safety

This paper presents preliminary criticality safety assessments performed by the Paul Scherrer Institute (PSI) in cooperation with the Swiss National Cooperative for the Disposal of Radioactive Waste (Nagra) for spent nuclear fuel disposal canisters loaded with Swiss Pressurized Water Reactor (PWR) UO2 spent fuel assemblies. The burnup credit application is examined with respect to both existing concepts: taking into account actinides only and taking into account actinides plus fission products. The criticality safety calculations are integrated with uncertainty quantifications that are as detailed as possible, accounting for the uncertainties in the nuclear data used, fuel assembly and disposal canister design parameters and operating conditions, as well as the radiation-induced changes in the fuel assembly geometry. Furthermore, the most penalising axial and radial burnup profiles and the most reactive fuel loading configuration for the canisters were taken into account accordingly. The results of the study are presented with the help of loading curves showing what minimum average fuel assembly burnup is required for the given initial fuel enrichment of fresh fuel assemblies to ensure that the effective neutron multiplication factor, keff, of the canister would comply with the imposed criticality safety criterion.

scholarly journals Minimizing the Standard Deviation of the Thermal Load in the Spent Nuclear Fuel Cask Loading Problem

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4869
Author(s):  
Joaquín Bautista-Valhondo ◽  
Lluís Batet ◽  
Manuel Mateo
Keyword(s):  
Standard Deviation ◽  
Nuclear Fuel ◽  
Thermal Load ◽  
Nuclear Power ◽  
Spent Nuclear Fuel ◽  
Search Algorithm ◽  
Deterministic Algorithm ◽  
Mixed Integer ◽  
Spent Fuel ◽  
Fuel Assemblies

The paper assumes that, at the end of the operational period of a Spanish nuclear power plant, an Independent Spent Fuel Storage Installation will be used for long-term storage. Spent fuel assemblies are selected and transferred to casks for dry storage, with a series of imposed restrictions (e.g., limiting the thermal load). In this context, we present a variant of the problem of spent nuclear fuel cask loading in one stage (i.e., the fuel is completely transferred from the spent fuel pool to the casks at once), offering a multi-start metaheuristic of three phases. (1) A mixed integer linear programming (MILP-1) model is used to minimize the cost of the casks required. (2) A deterministic algorithm (A1) assigns the spent fuel assemblies to a specific region of a specific cask based on an MILP-1 solution. (3) Starting from the A1 solutions, a local search algorithm (A2) minimizes the standard deviation of the thermal load among casks. Instances with 1200 fuel assemblies (and six intervals for the decay heat) are optimally solved by MILP-1 plus A1 in less than one second. Additionally, A2 gets a Pearson’s coefficient of variation lower than 0.75% in less than 260s CPU (1000 iterations).

Monitoring of the Recovery Process of the Fukushima Daiichi Nuclear Power Plant from VHR SAR Images

2016 ◽  
Vol 11 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Wen Liu ◽  
◽  
Fumio Yamazaki ◽  
Tadashi Sasagawa ◽  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Recovery Process ◽  
Sar Images ◽  
Reactor Building ◽  
Building Footprint ◽  
Intensity Images ◽  
Fukushima Daiichi ◽  
Very High

The Mw9.0 earthquake hitting the Tohoku area on Japan's Pacific coast on March 11, 2011, triggered huge tsunamis and a Fukushima Daiichi nuclear power plant breakdown. Due to high radiation levels, plant damage could only be assessed from satellite images. Our study involves four very-high-resolution (VHR) TerraSAR-X/TanDEX-X SAR intensity images taken under different acquisition conditions and used to try and determine reactor building damage. Layover and radar shadow areas were specified first based on building footprint and height, then backscattering patterns in these areas were modeled by introducing sectional views of the target building. Criteria for detecting damage from individual SAR scenes were used to compare simulated backscattering patterns to actual SAR intensity images. Damage to other reactor buildings was then identified based on these criteria. Results were confirmed by comparisons to two optical VHR WorldView-2 images and ground photos.

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