Operators of a nuclear power plant in Shenzhen have surrounded water intake pipes with gill nets to prevent the accumulation of shrimp that caused a minor safety incident last year.
The Nuclear Safety Consultative Committee, a Hong Kong-based watchdog that monitors the plants in Daya Bay and Ling Ao, reported six “below scale”(Level 0) incidents at the power stations last year, three of which occurred in a single month.
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But committee chairman Dr Raymond Ho Chung-tai said the stations appeared to be “upholding excellent safety performance standards” with “key operational indices reaching internally advanced levels in recent years”.
On October 4, station staff at Ling Ao’s Unit 2 found a deviation in the reading of a water pool level monitoring sensor during a planned outage during maintenance. It was later found that staffers had incorrectly closed a valve for the water level monitoring sensor during preparation.
On October 22, two valves in the initial cooling system were accidentally closed during periodic tests, causing a minor fluctuation in water temperature of the spent fuel pool.
On the same day, at Daya Bay Unit 1, a closed alarm used to measure nuclear reaction was not restored after fuel unloading preparations.
“Internationally, a level 0 event has no effect on the safe operation of the plant, the health of the workers or the nearby public and environment,” Ho said after an annual meeting with the operators.
Three other level 0 incidents occurred at Ling Ao between January and May. One involved the filters of a water intake pipe to the cooling pond being blocked by a large accumulation of 3mm-long, krill-like shrimp.
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“New nets were installed to [block] the very small shrimps from going through the water into coolant pond that caused one of the level 0 events last year,” Ho said.
Other devices such as sonar have also been installed to monitor rapid growth in marine life such as shrimp and jellyfish, which the committee believed was due to improved water quality.
Two reactors at Daya Bay – partly owned by CLP Power – provide Hong Kong with about a quarter of its electricity needs. Ling Ao does not supply the city but is located near Daya Bay.
Established in 1988, the 17-member committee advises the plant operators on safety measures and reports back to the Hong Kong public.
The current nuclear supply agreement with Daya Bay is scheduled to end in 2034 – the 40th year of operations – the minimum age at which an average nuclear power plant must be decommissioned and cleaned up.
Committee vice-chairman Tso Wong Man-yin said that in 2032 plant operators would either apply for decommissioning with national regulators or seek an extension to its life cycle.
