HKNIC - Consistent and Prompt Communication
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Consistent and Prompt Communication
The International Nuclear and Radiological Event Scale (INES) was established by the International Atomic Energy Agency to establish an internationally recognised standard and help the public, media and the nuclear community understand the significance of nuclear events. The scale has been adopted by China as a member state of the agency and has been used by Daya Bay since its commissioning.

An event is established on the scale based on the level of degradation of nuclear safety, the amount of radioactivity released within the nuclear power station and the amount of radioactivity released off-site.

In the highly regulated nuclear industry, any abnormal events are analysed and classified according to INES. Insignificant occurrences are classified at "Below Scale". Level 1 to Level 3 events are known as "Incidents", which have safety implications but involve very little or no impact on the environment. Level 4 to Level 7 events are called "Accidents" and involve various degrees of radiological impact. All events are identified, reported, analysed and corrected to prevent any recurrence.

The Three Mile Island Accident in the United States in 1979 represents the worst pressurised water reactor accident in history. It was classified at Level 5 on the INES Scale, even though the accident had limited off-site release of radioactivity, because of the extensive damage to the reactor core. In 1986, the Chernobyl Accident in the former Soviet Union, now Ukraine, was classified at Level 7. It led to extensive damage to Unit 4 of the Russian-built nuclear power station. The Chernobyl nuclear power station was of a completely different design to a pressurised water reactor, and such an accident could not happen at Daya Bay.


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