(This post is by Dr Rianne Teule, Senior Climate and Energy Campaigner for Greenpeace International)

The most common question asked when I’m at a party and someone finds out I work for Greenpeace is: “What about nuclear energy?”

Most people don’t want to know about blocking whaling ships in an inflatable, or whether I recently climbed a smokestack of a coal-fired power station. No, they want to discuss nuclear.

So I say that Greenpeace has always fought - and will continue to fight - against nuclear power because it is expensive, poses an unacceptable risk to the environment and to humanity, and will not help in solving the climate problem.

“But nuclear energy is clean!” No.

Nuclear energy might cause less carbon emissions than fossil fuels, but it is far from clean. It produces radioactive waste and causes radioactive pollution all over the world. Nuclear power gambles with people’s health and the environment from the very beginning of the nuclear chain - mining for uranium. I spoil the party by telling people about my rather depressing visit to Niger, where uranium mining contaminates the air, water and soil, and creates huge volumes of radioactive waste. On top of that, nuclear power creates tens of thousands of tons of lethal waste, which is radioactive for hundreds of thousands of years. No solution has yet been found for the safe and secure storage of the dangerous waste over such a long time period, which potentially spans many Ice Ages.

“But there are new and safer nuclear technologies!” No.

There are no new technologies that offer a solution for the waste or guarantee the safety of nuclear plants. This time i share my experiences of visiting the area around the Chernobyl nuclear power plant that exploded in 1986 – large areas, even up to more than 100km from the plant are still unsafe to live. And a continuous stream of incidents and accidents in nuclear reactors and other nuclear installations prove how vulnerable the technology is.

  • In September 2010, 79 workers at Koeberg nuclear power plant near Cape Town were exposed to significant levels of radioactive cobalt. The alarms did not go off, and the incident was only detected after the workers ended their shift. Currently one of the Koeberg reactors is shut down because one or more defective fuel rods caused higher levels of radioactivity in the reactor.

  • In December 2010, more than 30 million litres of radioactive sludge from three cracked waste pools has leaked into the environment at a uranium mine in Niger, operated by French nuclear company AREVA. At least 20 hectares of land are contaminated.

  • The Nuclear Regulatory Commission in the US found that radioactive tritium is leaking from at least 27 of the nation's 104 nuclear reactors, raising concerns about how it is escaping from the aging nuclear plants.

  • The number of ‘significant events’ or incidents in nuclear facilities in France has increased over the last decade.

“But nuclear power is cheap!” No.

Nuclear power is often described as “the most expensive way to boil water.” Despite what the nuclear industry tells us, building enough nuclear power stations to make a meaningful reduction in greenhouse gas emissions would cost trillions of dollars. The construction costs of new nuclear power plants in Finland and France are soaring.

And we so desperately need these resources to implement real climate change solutions! Nuclear power undermines the real solutions to climate change by diverting urgently needed investments away from clean, renewable sources of energy and energy efficiency.

Nuclear power is a bad idea. And not a very stimulating subject to discuss at a party...