Safety systems




 

Under normal operation, nuclear power plants do not pose a risk to the personnel, population and environment. NPPs can be considered as hazards only during emergency situations and accidents. Therefore, when designing, technical measures aimed at preventing or limiting the effects of accidents are determined in advance. Special safety systems are used for these purposes.

 

There are active and passive safety systems designed to provide in depth protection and maintain the protective barriers.


Active safety systems are driven by energy sources.

 

Passive safety systems are powered by natural processes without use of electricity and staff involvement.

By the nature of their functions, safety systems are divided into four groups:

Protective systems – are used to prevent or limit damage to the first three protective safety barriers – fuel matrix, fuel cladding, primary circuit, piping and equipment containing radioactive substances.

 

Localizing systems are designed to prevent or limit the spread of radioactive substances into the environment during accidents at nuclear power plants. The melt localization device and the containment vessel (containment) are examples of a complex and most effective localizing safety system on modern NPPs.

 

 

 

MELT LOCALIZATION DEVICE 

 

The melt localization device (or the melt trap) is an important innovation in NPP passive safety system. The melt trap is located in the concrete pit below the reactor vessel and provides melt localization thereby preventing the melt moving beyond the containment under any situation at the NPP. This device is designed to reduce the effects of severe accidents and has been implemented in the Tianwan NPP project for the first time in the world. 

  

Control systems – triggers other safety systems, controls and monitors those in the process of performance of specified functions

 

Supporting systems – are designed to supply energy and working medium to the safety system. Those create conditions necessary for reliable operation of the safety systems

 

An automated radiation monitoring system monitors the integrity of the barriers at the Akkuyu NPP. The automated system has sensors that detect the radiation level around radiation-dangerous facilities in real time.