Daya Bay trip works to demystify nuclear power

By Thomas Tang

Dr Thomas Tang, GIFT’s managing director, was in the delegation that visited Daya Bay on 10 July 2007.

GIFT managing director Thomas Tang was in a delegation to the Daya Bay nuclear power plant in southern China that sought to find answers to an energy generation technology that remains controversial despite its growing support.

Many of the fears surrounding nuclear power are unfounded, a Hong Kong General Chamber of Commerce delegation to a nuclear power station in southern China has concluded.

The group toured Daya Bay Nuclear Power Station just north of Hong Kong on 10 July 2007, raising concerns over safety, waste disposal, and terrorism – subjects at the forefront of international debate – with top power company executive Steven Lau.

Chamber members were given a rare look at turbine chambers, an area of nuclear power stations that are usually out of bounds, which topped an instructive and informative day that highlighted the significance of nuclear energy to future energy needs.

China’s rapid economic growth is inseparable from its thirst for energy. In the first quarter of 2007, China’s economy grew at its fastest rate since 1994 – 11.1% faster than in the same period in 2006, National Bureau of Statistics show. With this growth is the need for energy to run a multiplicity of industries and to provide for the needs of a fast-growing consumer-driven population and drive export industries.

Nuclear power provides about 2% of the Mainland’s energy needs. This contrasts with 70% that comes from coal, which, with other fossil fuels, is raising concerns about China’s energy performance in global search for energy sources that do not contribute to global warming.

Ageing coal-fired power plants are a major source of atmospheric pollution in China, and the first target in any clean-up, not least the country’s reputation of having some of the world’s most polluted cities.

Among the many questions the Chamber members asked Mr Lau, who is First Deputy General Manager of the Daya Bay Nuclear Power Operations and Management Company, was is nuclear a viable power option?

National target
Mr Lau said over many decades nuclear power had given Japan and France in particular energy free of carbon emissions to support their national development programmes.

China has sixteen nuclear power stations in operation, is building seven and has plans for fifty-four more to reach its target of having nuclear power provide 20% of its national energy needs by 2020. This will be an equivalent output of 2.8 million MWh.

Guangdong Daya Bay Nuclear Power Station, one of two parts of the Daya Bay complex.

Daya Bay, where the power plants are located, is two hours north-east of Hong Kong’s northern neighbour, Shenzhen. There are two nuclear power stations there, Guangdong Daya Bay Nuclear Power Station (GNPS) and Ling Ao Nuclear Power Station (LNPS) that together provide an installed capacity of just under 4,000 MW.

Daya Bay operates pressurised water reactors (PWR), similar to the type of technology used in nuclear submarines. Reactor units transfer heat energy to a secondary loop dedicated to generating steam that in turn drives electricity generating turbines.

A quick-glance at how PWR technology works.

The two units at GNPS (each 984 MW capacity) were commissioned in 1994, and are based on French technology. Seventy per cent of the power they generate goes to the Hong Kong electricity grid owned by China Light and Power.

LNPS runs two units, each with the capacity to generate 990 MW. They have been in operation since 2002 supply Guangdong.

The GNPS and the LNPS reactors have similar power generation costs of an estimated US$1,800 per kW.

The visitors were treated to a rare incursion into the GNPS turbine chambers to see one of the control rooms. Inside, the striking impression was of calmness. Staff attended to walls of panels flashing quietly, and kept watch on meters that monitored the operation of different zones of the station.

Critical lessons
Mr Lau explained these systems resulted from key lessons learned over many years. Accidents such as the Three Mile Island partial core meltdown in Pennsylvania, US, in 1979, raised the need to clearly indicate switch zones in a plant’s system so staff will know immediately which ones to attend to in emergencies. Three Mile Island also runs PWRs, in contrast to the graphite-moderated nuclear power reactor of Chernobyl, where the worst civilian nuclear power accident to date occurred in 1986.

Uncoded switchboards at Three Mile Island compounded a series of factors that contributed to the partial meltdown, delaying operators from shutting down the reactor.

Away from Daya Bay’s control room, Mr Lau took Chamber members to the station’s museum where he used models to explain how the technology at Daya Bay worked, and what safeguards were in place.

They were also able to appreciate how the Daya Bay site had none of the fuel bunkers or yards associated with fossil fuel plants. The entire nuclear plant consumes about 30 tonnes of uranium 235 each year, largely in the form of fuel rods.

Radioactive waste and terrorism
Throughout the day, Chamber members asked many questions on safety, which Mr Lau fielded patiently.

construction blueprint.JPG

Ling Ao Units 3 and 4 under construction.

Observations
It appears that the safeguards used in the production of nuclear energy have improved markedly since Three Mile Island, as has the management knowledge of how to run nuclear power stations.

Nuclear energy is an option to meet our energy needs, though the technology and protective measures makes it expensive. Nevertheless, for every nuclear generated kilo-Watt-hour, there is a saving of 1kg of carbon dioxide – in Daya Bay’s case, that amounts to 7.5 million tonnes per year. Add to this the avoidance of several thousand tonnes of sulphur dioxide, nitrogen oxides and particulates that a similar fossil-fuel power plant would otherwise emit.

Mr Lau said most of Daya Bay’s radioactive waste was held on site in reinforced fuel pools for eight years before being transferred to a reprocessing plant in Jiayuguan, Gansu Province. There, up to 97% of the material can be re-used either as low-level radioactive sources or re-blended into fuel rods.

On security, especially terrorism, Mr Lau said Daya Bay was triply tight, with military personnel, the plant’s own security staff, and the local police force providing protection.

Nevertheless, the visitors asked how staff would cope in a natural disaster, similar to recent earthquakes in Japan that caused fires to break out at nuclear power plants. Daya Bay does not lie on any obvious fault lines, they were told. The plant has a 5km radius emergency preparedness plan.

Last on the day’s agenda, the visitors were taken to a viewing point overlooking the construction of two new units at Ling Ao. Units 3 and 4 are scheduled for commissioning in 2010. They will add 2,000 MW to Daya Bay’s generating capacity.