Nuclear safety

Nuclear safety, particularly avoidance of accidents, is ensured by good design and operation. In this respect, a defence in depth principle is generally applied in the design and operation of nuclear power station.

The construction and operation of GNPS and LNPS are bound by the relevant safety regulations for civilian nuclear installations of the People's Republic of China and have to comply with the national regulatory requirements for granting of the construction and operation license. The National Nuclear Safety Administration (NNSA) under the Ministry of Environmental Protection is responsible for licensing and siting nuclear power plants, ensuring nuclear safety, carrying out safety inspections and participating in the emergency response to accidents within a nuclear power plant, among other things. China Atomic Energy Authority under the Ministry of Industry and Information Technology is responsible for emergency response to an off-site nuclear emergency at the national level (through its National Nuclear Emergency Response Office).

The International Nuclear and Radiological Event Scale (INES) is used by GNPS and LNPS to classify events occurred at the plants.

The two well-known accidents on nuclear reactors at Chernobyl in 1986 and Three Mile Island in 1979 had significant impact to the nuclear industry around the world. It had brought about major changes to nuclear power plants to ensure nuclear safety, particularly in enhancement of operator training and emergency planning. Since then, there was no major nuclear accident until March 2011 when the accident at Fukushima occurred which had rekindled global concern about nuclear safety and preparedness in dealing with major nuclear emergencies. The IAEA and countries across the globe using nuclear energy have been taking proactive actions to enhance nuclear safety and emergency preparedness.

Chernobyl accident

Occurrence of the Chernobyl accident on April 26, 1986 was mainly due to a combination of severe design deficiencies of the reactor and its shutdown system, coupled with violation of procedures when conducting an experiment on the reactor unit. The Chernobyl-type accident could not occur at the nuclear power stations in Daya Bay which have reactors of entirely different design.

Three Mile Island (TMI-2) accident

The cause of the Three Mile Island (TMI-2) accident on March 28, 1979 was apparently attributed to a combination of component failure, deficient instrumentation, and human errors. The operators were unable to diagnose or respond properly to a "loss of coolant accident" due to a defective pressure relief valve. Although there was a partial melting of the reactor core at TMI-2, the radiological release was mainly confined within the containment building and the release to the environment is minimal and insignificant. There were also no injuries or adverse health effect as a result of the accident.

Fukushima accident

Occurrence of the Fukushima accident in March 2011 was mainly caused by a major earthquake happened on March 11, 2011 and the large tsunami it created which disabled the off-site power supply and almost all on-site power supply and damaged some cooling facilities of Fukushima Daiichi Nuclear Power Station, leading to loss of proper cooling to the reactors and the spent fuel pools. Consequently, three reactor cores were largely melted and containment buildings of four reactors suffered different degrees of damage. The reactors in Fukushima are boiling water reactors which are different from those in the nuclear power stations in Daya Bay.

The above information is provided by EMSD .

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