To ensure requirement of application of defence in depth for nuclear power plants in Vietnam

To ensure requirement of application of defence in depth for nuclear power plants in Vietnam (Internet image)

Article 7 of Circular 30/2012/TT-BKHCN stipulates requirement of application of defence in depth for design of nuclear power plants in Vietnam as follows:

- The application of defence in depth is to prevent and mitigate the consequences of the accidents that could lead to harmful effects on people and the environment.

- The levels of defence in depth shall be independent as far as is practicable. The safety of the nuclear power plant under each state must be proven when the protection level decreases.

- Multiple physical barriers to the release of radioactive material to the environment shall be provided.

- The failures and deviation from normal operation are minimized, and accidents are prevented as far as is practicable. The minor deviation in the parameter of the nuclear power plant does not lead to a cliff edge effect.

- The control of plant behavior by means of inherent and engineered features must be provided such that failures and deviations from normal operation that require actuation of safety systems are minimized or excluded.

- The safety systems must be able to be automatically activated in accident conditions.

- The structures, systems, components, and procedures for mitigating the consequences of failures and deviations during normal operation that exceed the capability of safety systems shall be provided.

- Multiple means for ensuring that the fundamental safety functions are performed shall be provided, thereby ensuring the effectiveness of the barriers and mitigating the consequences of any failure or deviation from normal operation

- To ensure that the defence in depth is maintained, the following factors shall be prevented as far as is practicable: The challenges to the integrity of physical barriers; The failure of one or more barriers; The failure of a barrier as a consequence of the failure of another barrier; The harmful consequences of errors in operation and maintenance.

- The capability of the first, or at most the second, level of defence, ensured as far as is practicable when a failure or deviation from normal operation occurs.

More details can be found in Circular 30/2012/TT-BKHCN, which comes into force from February 11, 2013.  

Le Vy

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