The Security Bureau today said it was notified by Guangdong Province's Nuclear Emergency Committee Office of an operational event at Ling Ao Nuclear Power Station, in which an isolation valve remained closed longer than required.

This incident did not affect the safety of the power station’s Unit 1, the health of the workers, the nearby public or the environment, the bureau added.

On May 7, Unit 1 was undergoing a planned overhaul for refuelling. During routine testing, station staff remotely closed one of the cooling water isolation valves of the standby equipment from the main control room to adjust the cooling water flow, and restored it to normal status on the same day.

Since the isolation valve remained closed for a duration exceeding the requirement of the technical specification, this event was classified as a Level 0 deviation on May 8 in accordance with the International Nuclear & Radiological Event Scale and relevant nuclear safety regulations. 

The bureau stressed that Unit 1 remained in a safe condition throughout the event, while the three safety barriers remained intact and there was no release of radioactive substances.