Martin Li
LEVELS of radiation workers were exposed to at the Daya Bay Nuclear Power Station were within safe limits, China Guangdong Nuclear Power Holding Corp. (CGNPC) said in a statement on its Web site.
The statement follows Hong Kong media reports saying there had been a sharp increase in radiation at the power station.
The level of radiation to which workers at the power station were collectively exposed more than doubled from 175 millisieverts (mSv) in October to 355 mSv in November, the statement said.
A millisievert is the unit used to measure the average accumulated background radiation absorbed by a person.
However, the statement said there were no radiation leak in the period when the exposure level increased.
The company gave two reasons for the rise in collective exposure.
An increase in the number of workers during routine maintenance had increased, leading to an increase in the collective measurement of exposure, said the statement.
In addition, when the nuclear core facilities were opened to enable maintenance, radiation levels increased but remained well within safe limits.
CGNPC started maintenance and nuclear fuel replacement at the power station s No. 1 generating unit Oct. 22, which involved 1,743 staff and contract workers.
Individual radiation levels measured during the maintenance period were recorded at under 1 mSv, well within the national safety limit of 50 mSv per year and the annual 20-mSv limit set by the company, the statement said.
Maintenance was completed Nov. 28.
By Dec. 9, the No. 1 generating unit had operated for 3,000 days without an equipment failure since Jan. 12, 2002.
Hong Kong Nuclear Investment Co., which owns 25 percent of the Daya Bay plant, said last month there was a leak at the power plant Oct. 23, which was caused by a fault in a pipe carrying hot water from a reactor. However, it was denied in a statement, that this had led to any safety, health or environmental consequences for the safe operation of the power station and the surrounding area. The pipe section concerned and the residual heat removal system were completely sealed off in the enclosed solid containment building.
However, the company said the leak was rated a level-one incident, which was the lowest level on the International Atomic Energy Agency s International Nuclear and Radiological Event Scale.
The power plant is at Daya Bay in Longgang District north of Hong Kong.
