Nuclear Safety Assessment for the Passive System of the Nuclear Power Plants (NPPs) in Safety Margin Estimation

Author(s):  
Taeho Woo
Author(s):  
Zhilin Chen ◽  
Ping Huang ◽  
Chunhui Wang ◽  
Zhiyuan Chi ◽  
Fangjie Shi ◽  
...  

It’s the trend to extend the operating license time, called Operating License Extension (OLE) in China, of nuclear power plants (NPPs) in the future. It needs to be adequately demonstrated by licensees and approved by the regulator to gain an extended license time, such as 20 years. The demonstration methods for OLE are different among countries due to the different management systems for NPPs. Safety assessment, environment effect evaluation and update of the final safety analysis report (FSAR) will be the main aspects during OLE demonstration of NPPs in China according to the technical policy issued by National Nuclear Safety Administration (NNSA). Technical methods for scoping and screening, aging management review and time-limited aging analyses, which are the main contents of safety assessment are established based on the technical policy drafted by NNSA and international experiences in order to assist the operators to implement the safety assessment for OLE of NPP.


2021 ◽  
Author(s):  
Le Li ◽  
Zhihui Zhang ◽  
Chao Gao ◽  
Fei Zhou ◽  
Guangqiang Ma

Abstract With the development of digital instrument and control technology for nuclear power plants in recent decades, communication networks have become an important part of safety digital control systems, which takes charge in data exchange between the various sub-systems, and extremely impact on the reliability and safety of the entire I&C system. Traditional communication systems where some special features, such as reliability, safety, real-time, certainty, and independence are not strictly required are various illustrated. However, how to implement a communication system in a safety I&C system is rarely stated in current research. In this research, a reliable safety communication system applied in nuclear power plants is designed and analyzed. The five key characteristics of nuclear safety communication networks are explained, followed by explanation of how to achieve these characteristics. The analysis and verification of the designed system are also stated in this paper, which contributes to proving that the designed nuclear safety communication system could applied in the nuclear power plants.


2021 ◽  
Author(s):  
Yuhang Zhang ◽  
Zhijian Zhang ◽  
He Wang ◽  
Lixuan Zhang ◽  
Dabin Sun

Abstract To ensure nuclear safety and prevent or mitigate the consequences of accidents, many safety systems have been set up in nuclear power plants to limit the consequences of accidents. Even though technical specifications based on deterministic safety analysis are applied to avoid serious accidents, they are too poor to handle multi-device managements compared with configuration risk management which computes risks in nuclear power plants based on probabilistic safety assessment according to on-going configurations. In general, there are two methodologies employed in configuration risk management: living probabilistic safety assessment (LPSA) and risk monitor (RM). And average reliability databases during a time of interest are employed in living probabilistic safety assessment, which may be naturally applied to make long-term or regular management projects. While transient risk databases are involved in risk monitor to measure transient risks in nuclear power plants, which may be more appropriate to monitor the real-time risks in nuclear power plants and provide scientific real-time suggestions to operators compared with living probabilistic safety assessment. And this paper concentrates on the applications and developments of living probabilistic safety assessment and risk monitor which are the mainly foundation of the configuration risk management to manage nuclear power plants within safe threshold and avoid serious accidents.


2012 ◽  
Vol 260-261 ◽  
pp. 103-106
Author(s):  
Yi Chun Lin ◽  
Yung Nane Yang

The ripples of the tsunami crisis in Japan triggered introspections of nuclear plant safety issues in the worldwide. Many countries have claimed the suspension of nuclear power plants. However, some countries such as Taiwan, under nearly 99% energy is exported, the disasters force government and citizen to face the importance of nuclear safety, especially the neighborhoods nearby the nuclear power plants. We have to face the nuclear safety since there is no other alternative energy presently. The 3rd nuclear power plant located in the south of Taiwan, which has the same geographic features with Fukushima, Japan. Presently, there is no precedent in Taiwan of precaution and rescue team and civil supervised mechanic on nuclear security issue. This paper will review according to transparent information, public participation and cross-organization cooperation to propose the execution and work division principles, including information monitor, educational propagation, hide and evacuation, emergence aid and care, rear and refuge service. The ultimate target is to establish self-governance inside nearby neighborhood to confront nuclear disaster at the critical moment.


Author(s):  
Motonori Nakagami ◽  
Seiji Komatsuki ◽  
Kyosuke Fujisawa ◽  
Takashi Nishio ◽  
Thomas Quercetti ◽  
...  

As one of the studies on “yoyushindo disposal” whose concept is similar to an intermediate disposal, the development of a disposal container has been conducted by the Federation of Electric Power Companies of Japan. To assess a drop event of a waste package in which stored the radioactive wastes from nuclear power plants, the toughness of the disposal container was evaluated by drop tests using three specimens which have actual dimensions, drop analysis, fracture mechanics assessment and macroscopic tests. The three specimens for drop tests were manufactured in consideration of the design specifications and the manufacture operations in nuclear power plants. The lid plates of the specimens were welded to the body plates without pre- and post-weld heat treatment by using a remote automated welding machine. The drop tests showed that no penetration cracks or splash of its content occurred in the disposal container under conservative conditions such as the maximum weight and height in the handling. Drop analysis and the fracture mechanics assessment indicate that the strain induced by the drop impact did not exceed the fracture strain and an unstable fracture did not occur. And macroscopic tests showed that penetration cracks did not occur at 8m drop events. These tests and evaluations confirmed that the disposal container had sufficient toughness.


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