If the 1,600 megawatt Olkiluoto-3 reactor comes on stream in 2009 as planned, it could herald a new dawn for nuclear power, supporters say. They argue that Europe can't meet its pledge to reduce greenhouse gas emissions without more nuclear energy.

"The world needs more and more energy. If you must reduce the use of fossil fuels, nuclear power must be given a prominent role," said Sven Kullander, a professor of high energy physics at Sweden's Uppsala University.

Anti-nuclear campaigners - ever fewer in recent years after a heyday in the wake of the 1986 Chernobyl reactor meltdown that contaminated 150,000 square km (57,920 square miles) in Ukraine, Belarus and Russia - oppose Finland's fifth reactor.

"I try to believe that we could stop it," said Annaliisa Mattsoff of Finnish Women Against Nuclear Power.

Last month activists from environment lobby Greenpeace and other anti-nuclear groups demonstrated near Olkiluoto, carrying banners warning the area is "infected by nuclear disease".

"MEGALOMANIA"

The opponents say every new nuclear reactor increases the risk of terrorists getting hold of plutonium, the deadly radioactive material used in nuclear bombs.

Anti-nuclear activist Pirkko Lindberg described the Olkiluoto-3 project as "megalomania". She has written a book about the Pacific state of Tuvalu which is at risk of being submerged if oceans rise as a result of global warming.

"Nuclear power has no effect on the climate," said Stockholm University Meteorology Professor Bert Bolin, who led the United Nations climate change panel during the birth of the Kyoto protocol.

The international treaty, which is yet to come into force, commits industrialised nations to cut their greenhouse gas emissions.

Bolin said 10,000 big nuclear reactors would be needed to produce enough electricity to offset a meaningful cutback in fossil fuel use. "Do we want to have that many?"

Nuclear plants heat up water to steam, which drives a turbine generating electricity. The uranium fuel is extracted from abundant ore deposits mined in several countries.

Enriched uranium used in atomic reactors is highly radioactive and spent fuel remains hazardous for 100,000 years.

CHEAP ELECTRICITY

"I'm not afraid," said part-time farmer Tuomo Jalava, who lives 2 km (1.2 miles) from the two dull-red-and-grey-painted nuclear reactors built in the 1970s at Olkiluoto on Finland's west coast, 200 km (125 miles) northwest of Helsinki.

"It is positive for this community. It creates jobs," he said, seated on a red tractor.

Nuclear power produces some 16 percent of world electricity while coal, oil and gas - the fossil fuels whose carbon dioxide emissions are regarded by some scientists as the main global warming culprit - account for two thirds.

Finnish power group TVO, which runs Olkiluoto, puts domestic electricity demand growth at 1.5 to 2.5 percent a year.

"The forest industry needs nuclear power," said Risto Viitanen, an executive at Finnish forestry group UPM, the world's top paper maker. UPM, a co-owner of TVO, has already reserved almost 30 percent of Olkiluoto-3's output.

"This decision ensures a stable and affordable electricity price for UPM's factories," Viitanen said.

French state-controlled nuclear energy group Areva, whose Framatome ANP subsidiary won the Olkiluoto-3 reactor contract, hailed Finland's decision in 2002 as a milestone, saying it "strikes an encouraging chord for nuclear development".

GUINEA-PIGS

But it is a nightmare for anti-nuclear activist Lindberg.

"This is a prototype, it has been tested nowhere," she said of Framatome's new reactor design.

"France, the mother country of this monster, refuses to have it on its own ground. We are chosen to be guinea-pigs ... with the risks and that horrible deadly dangerous waste of plutonium."

Sweden, whose nuclear phase-out has resulted in the closure of one of 12 reactors, stores 4,000 tonnes of spent fuel in a high-security facility near its three-reactor Oskarshamn complex on the Baltic Sea coast 300 km (185 miles) south of Stockholm.

The facility's underground water basins holding spent fuel shimmer eerily blue. Leaning on the 1.5-metre-thick reinforced concrete basin wall, process engineer Stefan Nordh said anyone trying to grab the nuclear waste would die quickly of radiation.

At the nearby Aspo final disposal test site scientists work 460 metres (1,510 feet) below ground. Even earthquakes, rare in Scandinavia, would do little damage at that depth, said Swedish Nuclear Fuel and Waste Management spokeswoman Anni Bolenius.

"This represents ultimate security," she told Reuters during a tour of the cavernous tunnels.

Sweden has yet to decide where to build its final waste repository but the Aspo site resembles Finland's planned waste burial ground in the Olkiluoto bedrock.

Lindberg said: "The bedrock there is as full of ruptures as anywhere so it's impossible to say it's safe, maybe for a short time, then the waste will probably spread all over the place."