Vietnam: Requirements for design of the containment of nuclear power plants

According to Article 41 of Circular No. 30/2012/TT-BKHCN of the Ministry of Science and Technology of Vietnam, control of radioactive releases from the containment of nuclear power plants is prescribed as follows:

- The containment shall be designed to ensure that the radioactive release from the nuclear power plant to the environment is kept as low as reasonably achievable, and below the acceptable limit.

- The containment structure, the systems and components affecting the leak tightness of the containment system shall be designed and constructed so that the leak rate can be tested at the containment design pressure during the operation of the plant.

- The design of the penetrations through the containment must satisfy the following requirements:

+ The number of penetrations through the containment must be kept to a minimum. The features and other requirements applicable to the penetrations shall be kept at a level similar to that of the containment itself.

+ The penetrations shall be able to withstand the impacts caused by pipe movement and pipe whip, or accidents relevant to missiles, external or internal events.

Moreover, according to Article 42 of Circular No. 30/2012/TT-BKHCN, each line that penetrates the containment as part of the coolant pressure boundary or that is connected directly to the containment atmosphere shall:

- Be automatically and reliably sealable in the event of an accident;

- The leak tightness prescribed in Point a of this Clause shall be fitted with at least two containment isolation valves or check valves arranged in series (usually, a valve is located inside and the other is located outside the containment and shall be provided with suitable leak detection systems. The isolation valves and check valves shall be located as close to the containment as possible; each valve must be capable of independent and reliable actuation, and be periodically tested;

- The fulfillment of the requirements prescribed in Points a and b of this Clause may not be necessary for the instrument lines, or in cases in which the implementation of such requirements reduces the reliability of the safety system that includes the penetrations through the containment.

Each line that penetrates the containment and is neither part of the coolant pressure boundary nor connected directly to the containment atmosphere shall have at least one containment isolation valve located outside the containment and as close to the containment as possible.

View details at Circular No. 30/2012/TT-BKHCN of the Ministry of Science and Technology of Vietnam, effective from February 11, 2013.

Le Vy

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