scholarly journals Mitigation of high energy arcing faults in nuclear power plant medium voltage switchgear

2019 ◽  
Vol 51 (1) ◽  
pp. 317-324 ◽  
Author(s):  
Choong-koo Chang
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
High Energy ◽  
Medium Voltage ◽  
Arcing Faults ◽  
Medium Voltage Switchgear

Analysis of whipping effect on high energy pipe in a nuclear power plant

2020 ◽  
Vol 150 ◽  
pp. 111359
Author(s):  
Xiangyu Luo ◽  
Shaojie Wang ◽  
Jun Wang ◽  
Pengfei Wang ◽  
Yucheng Wang ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
High Energy

Applicability Study of Computed Radiography to NDE for Piping and Component in Nuclear Power Plant

2010 ◽  
Author(s):  
Takashi Hasebe ◽  
Nobuki Tamai ◽  
Syohei Tatsuno ◽  
Yuma Itahashi ◽  
Kiyoaki Tokunou
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Image Quality ◽  
Nuclear Power ◽  
Computed Radiography ◽  
High Energy ◽  
Thick Wall ◽  
X Ray ◽  
Digital Imaging Technology

In Radiography Testing (RT) that is an important nondestructive testing as the quality control, the digital imaging technology rapidly provides advancement. The digital imaging technology is more effective than the film method on an environmental side and the cost side, such as unnecessary of the film storage and a chemical treatment by digital output. Especially, in the medical field, the advancement by the digitalized image data processing is remarkable, and it is attempted the upgrade of the inspection technology. However, RT that uses the high-energy radiation and the fast film is a main current in an industrial field, and it has not arrived at digitalization yet. Therefore, in an industrial RT, digitalization is expected and the examination standardization is required also in ASME, JSME, and JIS. We, Mitsubishi Heavy Industries (MHI), studied an applicability of Computed Radiography (CR) to Non-Destructive Examination (NDE) for welds of piping and thick wall component in nuclear power plant. At first, MHI researched image quality of CR for piping. In this research, it was confirmed that the images of testing results by CR method are equivalent to that by film method in terms of visibility of IQI (Image Quality Indicator) and detection performance of welding defects. And we founded the optimized shooting conditions for piping. Second, MHI researched image quality of CR for thick wall component. In the result, the noise shown in fig.1 was occurred on CR image when the thick wall component such as pressure vessel is radiographed with high energy. It is speculated that the primary cause of this noise is the scattered X-ray effect (shown in fig.2). Therefore it is necessary to investigate the effect of the scattered X-ray on CR image. In this study, to reduce the scattered X-ray effect on CR image, we investigated the effect of 1) screen, 2) screen + filter on image quality of CR for thick wall component. And we studied the optimized shooting conditions and parameters for thicker component than piping to aim for more application. Finally, we applied CR to the pipings and components for nuclear power plant with the optimized shooting conditions and parameters.

Diagnostics and Life-Cycle Assessment of Medium-Voltage Cables in Nuclear Power Plants During Regular Overhaul Process

2016 ◽  
Vol 2 (4) ◽  
Author(s):  
Simon Podkoritnik ◽  
Marko Jansa ◽  
Stanko Manojlovic
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Good Practice ◽  
Maintenance Management ◽  
Medium Voltage ◽  
Electric Cables ◽  
Reliability Of Operation ◽  
Insulation Condition

The reliability of operation of a nuclear power plant substantially depends on the reliability of its individual components. Electric cables, particularly medium-voltage cables, represent an important constituent of the nuclear island as well as of the balance of the plant. It cannot be considered as satisfactory that the redundancy of a particular subsystem is ensured. For this purpose, it is important to check the cable insulation condition, which is supposed to be carried out during the overhaul activities. The lifetime of medium-voltage cables is estimated to attain somewhere around 40 years. However, due to electrical, thermal, and mechanical stresses, it may be significantly reduced. In order to avoid its likely failures and following outages, the insulation must be tested regularly. Based on obtained testing results, the condition of a cable or cable termination can be assessed and repaired or a replacement made, if necessary. The paper presents some of the most important nondestructive diagnostic measurements on cable connections recommended to be done during the overhaul of a nuclear power plant following a good practice of asset maintenance management.

Safety Approach and Ageing Management in Czech Rules and Standards

2009 ◽  
Author(s):  
Jaroslav Bartonicek ◽  
Lubomir Junek ◽  
Milan Vrana ◽  
Stanislav Vejvoda
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
High Energy ◽  
Proactive Approach ◽  
Plant Safety ◽  
Operation Conditions ◽  
Concept Usage ◽  
Time Required

There are basic technical (protection) objectives determined for assurance of nuclear power plant safety and the following generally belong among them: - Reactor pressure vessel shut down, - Long term maintenance of sub-critical state, - Long term cooling, - Prevention of radioactivity leakage. To ensure these objectives multi-step concept of deep protection is used for the design of a nuclear power plant and it includes: - Prevention of failures during normal and abnormal operation, - Control of failures and their consequences, - Minimizing of risks during accidents. Failure of operating systems is conservatively postulated for determination of systems requirements using for failure ensure as piping breaks. Ensure of these postulated failures come under multilevel safety approach. Failure consequences should be mainly ensured by design measures as separation of high energy piping, whip piping restrains etc. Efficiency of design measures have to be demonstrated. This passive safety procedure during design of new NPP can be applied. Application of this passive procedure for operating NPP can lead to technical and economical problems. It can be done by non precise and non sufficient requirements, current standards and documents. Leak before break concept (LBB) is very often out due to break operation conditions for successful concept usage. Beak preclusion concept was defined in Germany thirty years ago. The concept is developed from this time. Required quality of SSC is basic of this concept. The quality has to be received during manufacturing and assembly of new components to system or the quality passport has to be documented for SSC in operation before enlistment to the concept. During next operation they are sufficient and redundant measures necessary to control and to manage ageing phenomena (conceptual, technological, and physical) for exclusion of premature ageing. This proactive approach is also basic of documents from the last year’s required ageing and lifetime management. In Czech NPPs postulated failures and their consequences in accord with producer knowledge state at that time were insured. Postulated failures and their consequences were insured partly design measures and partly design supposed quality too. It is very difficult to realize new requirements on needed design provision on NPP in operation. It is impracticable in any cases. Needed national law for approach application exists in Czech from 1997. Regulation on lifetime management and national nuclear standards with specific requirements exist in Czech too. There are backgrounds for application proactive approach as it is used in Germany NPPs. New safety approach was provided in Czech NPPs. SSC are separated into three groups on the base safety approach: - SSC must not fail (guarantee of quality), - SSC may fail in rare case (preventative maintenance), - SSC may fail (failure orientated maintenance). The contribution deals about new Czech safety concept aspects, boundary conditions, needed document and proactive measures.

The Activation Sources of Reactor Internals During Decommissioning

2017 ◽  
Author(s):  
Jianchun Han ◽  
Yan Zhou ◽  
Hui Li ◽  
Qiliang Mei
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Neutron Flux ◽  
Nuclear Power ◽  
Power Plants ◽  
Neutron Transport ◽  
Three Dimensional ◽  
High Energy ◽  
Pressurized Water ◽  
Dimensional Distribution

As China’s first nuclear power plant connected to the grid, the first Qinshan nuclear power plant is approaching the decommissioning period. Other nuclear power plants also turn into the preparation phase of decommissioning in succession. In order to facilitate decommissioning, source survey is conducted during the pre-decommissioning phase, which can provide radioactive inventory, contamination distribution, species and quantities of nuclides. The internals of the reactor work under the most severe radiation environment. During the reactor operation, the materials of internals are irradiated by high-energy neutrons. So activated nuclides are generated due to the neutron capture reaction, which are the main radioactive waste to be treated during decommissioning. In this paper, the neutron irradiation and the generated activation source of the internals for pressurized water reactors (PWR) are studied and analyzed. Firstly, core modeling was carried out, and the neutron transport calculation is performed to obtain three-dimensional distribution of the neutron flux. Secondly, according to the three-dimensional distribution of the material composition and the neutron flux rate of the reactor, the activation calculation is carried out to obtain the activation source.

scholarly journals Drinking high-energy electrolytic water decreases internal radiation exposure caused by the Fukushima Daiichi Nuclear power plant disaster

2016 ◽  
Vol 31 (2) ◽  
pp. 173-178
Author(s):  
Masahiko Sawajiri ◽  
Shoichi Miyamoto ◽  
Kohkoh Yamanouchi ◽  
Shoji Wada ◽  
Preeyaporn Srimawong ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Test Group ◽  
High Energy ◽  
Control Group ◽  
Oxygen Species ◽  
Hydrogen Water ◽  
Electrolytic Hydrogen ◽  
Fukushima Daiichi

The Fukushima Daiichi Nuclear Power Plant disaster on March 11, 2011, caused radiation hazards throughout Fukushima Prefecture. Cesium was absorbed by soil and plants and transferred to livestock. Removing radioactive cesium from the bodies of farm animals and humans is essential. It has recently been reported that H2 scavenges reactive oxygen species and suppresses oxidative stress-related diseases. The hypothesis is that ?active hydrogen? (hydrogen water) scavenges active oxygen species. We hypothesized that high-energy electrolytic hydrogen water will effectively decontaminate cesium-exposed chickens. A test group of chickens drank high-energy electrolytic hydrogen water, while the control group drank regular water. Cesium contents in the test group were significantly lower than in the controlled one, possibly because more cesium excretion occurred in the test group than the control group. Lower 137Cs concentrations were found in test-group tissues than in control-group tissues, showing that high-energy electrolytic hydrogen water increased the rate of elimination of 137Cs incorporated into chicken tissue.

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