With the Copenhagen climate conference under way, the UK government under pressure to cut carbon emissions and Wylfa on Anglesey shortlisted for a new nuclear power station, BBC Wales' environment correspondent Iolo ap Dafydd asks if nuclear is the low carbon answer to energy security in the future.
Inside the ageing Wylfa plant there are four large turbines which are part of the process to produce electricity 24 hours a day.
When fully operational, they produce enough electricity to power both Liverpool and Manchester simultaneously.
With a predicted shortage of energy by 2015, should we build more nuclear power stations?
Surprisingly some environmentalists believe nuclear power is an acceptable way of making electricity - without the carbon emissions that comes from burning coal and gas.
Amongst them are Stephen Tindale, a former executive director of Greenpeace, Dr Patrick Moore, co-founder of Greenpeace and Mark Lynas, the author of two studies on climate change.
Professor Sir David King of Oxford University - the UK government's one-time chief scientific advisor - recalls how he told Tony Blair in 2003 at a cabinet meeting: "I still don't believe we could cut CO2 (carbon dioxide) without nuclear power."
Also the controversial scientist and author Professor James Lovelock, who wrote the "Revenge of Gaia", believes nuclear power is the only short-term way to provide enough energy without causing more climatic harm.
In 2004, he angered many fellow environmentalists by saying that "only nuclear power can now halt global warming".
But researchers at the Öko Institut in Darmstadt, Germany, who have analysed nuclear plants, claim that carbon-free energy does not exist.
Nuclear power has more than just a little greenhouse gas attached to it, when mining uranium ore, refining and enriching fuel, building the plant, and operating it are included. The same could be said of concrete foundations of on-shore wind farms, or building tidal lagoon.
Dealing with nuclear waste is a residual problem. There is still no long term answer or a national nuclear dump despite over £70bn being spent so far dealing with contaminated and radioactive waste.
In Wylfa, it is believed, energy security and climate change will force governments and people to adapt their views.
John Idris Jones heads Magnox North's socio-economic developments at Wylfa and Trawsfynydd. He says personally he would have no qualms living close to nuclear waste should Wylfa B get the go-ahead.
"There's a growing realisation about the importance of security of energy supply, and the significant impact of climate change on our environment," he says.
"Nuclear power, in my opinion, is part of the answer to those two critical problems. In terms of energy production, nuclear power is a source of low carbon energy production, on a par as renewables such as wind generation."
A group called People Against Wylfa B has been campaigning for over 20 years against a second atomic station on Anglesey - for health and costs reasons.
Dr Carl Clowes is a member, and a health consultant. He says: "I don't think they are a viable proposition. They are not only expensive, they are a dirty option. There are processes to deal with waste - but no solution.
"And we are going to see thousands and thousands of tonnes of increase in that waste unless we see a real alternative through alternative energy production."
As well as waste issues, Dr Clowes also has health concerns. Especially since a German government funded report showed that there were a higher degree of cases of leukaemia in children, the closer they lived to nuclear power stations.
This report has now been accepted by the government in Berlin, but other studies in the UK, claim that clusters of leukaemia could be down to a virus and movement of people.
More that health issues, or even climate change, it may well be the cost of nuclear power which will decide if Britain opts for more nuclear or invest in renewable energy like wind, solar and tidal schemes to keep the lights on in our homes and businesses in future.
A low carbon energy decision has to be made before closing down ageing reactors and old polluting coal power stations.