First published July 2010, updated March 2011

I'll be up front - I'm not a fan of nuclear power as a solution to reducing electricity related greenhouse gas emissions. I doubt I ever will be. While some of my reservations have to do with the period of time I grew up in; and Chernobyl (and now Japan) type nuclear emergencies aside - it's still not as environmentally friendly as renewable energy options such as solar power. 

I'm not totally against nuclear energy, I just prefer the closest nuclear reactor being 93 million miles away (the sun).
   
Regardless, nuclear energy does have some very attractive attributes in a world becoming increasingly conscious of peak oil and climate change. It's understandable many people feel it's a solution.
  
How does nuclear power work?
 
Essentially, nuclear power seems quite simple. Nuclear fission heats water to generate steam, the steam turns turbines connected to a generator which in turn produces electrical power. It's basically the same process as coal fired generation; just using what is a very, very unstable fuel.

Nuclear fission is the splitting of atoms, a process in which a great deal of energy in the form of heat is produced. Where things get complex are the controls and resources needed to keep the fission reaction safe.
 
Advantages of nuclear energy

• The actual generation of electricity using nuclear energy involves little in the way of carbon emissions.
• A single nuclear power plant can generate a huge amount of electricity.
• Nuclear reactors have a long life span.
• Fuel appears to be abundant; however this is hotly debated.

Disadvantages of nuclear power

Mining

Uranium mining destroys landscapes and uranium and other radioactive substances are released in the process. The mining and extraction process requires large volumes of water and various acids and alkalis. Contaminated water can leak from tailings dams into groundwater.

Greenhouse gas emissions

I mentioned that electricity generation using nuclear fuel is emissions free - but that's just the generation. All the processes leading up to that point involve carbon emissions; but how those stack up compared to coal I'm not sure.

Accidents
  
In a word - Chernobyl .. but now there's also Japan. 
  
While the Chernobyl accident occurred decades ago, its legacy continues and may even worsen if the old plant isn't properly dealt with. Even today, an exclusion zone of approximately 20 miles exists around the Chernobyl reactor and estimates are the region will not be safe for agricultural purposes for 200 years. The effects of Chernobyl are still measurable in countries as far away as the UK.
 
As for the current Japan nuclear emergency at two nuclear reactors at  Fukushima power plant, north of Tokyo  - that situation is still evolving; but when I last checked the news, the likelihood of a nuclear meltdown having occurred was increasing.

A nuclear meltdown can be caused by a number of issues, such as a failure in a plant's cooling system, but my understanding is basically the fuel rods overheat to the point they melt. Beyond that meltdown, the worst case scenario is where the containment structures then also fail - they may rupture due to a build-up of steam pressure inside. At that point, dangerous levels of radioactivity can be released and as in the case of Chernobyl, affect a very wide area.
  
Aside from the general immediate health and environmental effects should the Japan situation deteriorate into a Chernobyl-scale incident; imagine having to tie up so much land in an exclusion zone in a country with so little land available - and perhaps for centuries. 

The current incident in Japan should give us pause for thought - if the Japanese can't guarantee a safe nuclear power facility, I really don't know who can.

Water consumption

Nuclear power plants are thirsty operations. According to the Union of Concerned Scientists, for every three units of thermal energy generated by the reactor core, two units of waste heat go into the environment. Cooling systems for plants require huge volumes of water and a nuclear power station will use more water than a similar sized coal fired power station.

Water intake and discharge has a negative effect on aquatic ecosystems - through the processing of the water itself which kills organisms and the raising of waterway temperatures during discharge. 

In a world where fresh water supplies are becoming increasingly unreliable in many places; there's also no guarantee a plant that is built today will have the water it needs in a decade from now without causing even more related environmental problems.

Waste

The issue of radioactive waste is an important one as what we do with it is a legacy that will affect future generations for thousands of years. The more nuclear power plants we have, the more waste is generated and it only takes a single incident to affect a wide area - and for a very long time. The waste can also be used by hostile parties to create "dirty bombs". Aside from the human costs of such devices being used, the environmental impact needs to be considered.

Time for construction

A solar power plant can be planned and constructed in a matter of months; a rooftop solar power system in a matter of weeks. A nuclear power plant can take decades - it's not a short term solution for our energy needs by any means.

Costs

Building a nuclear power plant is an expensive undertaking, usually requiring a good deal of taxpayer money. Because of the long planning and building process; costs invariably blow out - again, it's money that could be spent right now on renewables such as solar energy.

Contrary to popular (and even my own) belief - once constructed, the actual generation of electricity via nuclear means and general operating costs are incredibly expensive. Like the true cost of coal, the price isn't clearly visible in the cents per kilowatt hour tag we see quoted by the industry.

Harking back to the waste issue, imagine the cost involved with storing nuclear waste for thousands of years. I say "imagine" because nobody really knows what that cost will be. Additionally, the liability insurace subsidies the industry receives are so important that without them, nuclear power stations simply wouldn't exist as the true price per kilowatt hour of electricity generated would be far too high.

Misuse 

Nuclear energy based power generation is thought to be a front in some countries for nuclear weapons programs. You cannot build a nuclear missile from solar panels, nor with the equipment used to make them. A nuclear energy free future removes some opportunities for covert weapons development. 
 
Nuclear disarmament will likely fail if nuclear technologies are continually promoted as a solution to the world's energy needs. The lessons of Nagasaki and Hiroshima need to be heeded, not just for the sake of humanity, but for the wider environment.
 
Availability of uranium
 
While some say we have an "endless" supply of uranium, the same sort of spiel was once said about oil. Perhaps uranium is a plentiful resource, but how much of it is relatively easy to get to? Low-grade uranium ore contains as little as 0.01% uranium oxides and it takes a lot of uranium oxide to make nuclear fuel.
 
In addition to peak oil, will there be a "peak uranium"? Will we see a tar sands equivalent in uranium extraction in the not too distant future if nuclear power plants become more commonplace?

There are advantages and disadvantages for all power sources and I'd be the first to admit to the fact the oil and coal industry has caused far more damage than the nuclear energy sector has done - to date. However, nuclear power isn't as common. 

I still believe our immediate and long term answers lie in renewable energy sources such as wind and solar power; but equally as important is a huge push on energy efficiency - and that is something we all need to be involved in. 

Some may say solar can't provide baseload power. Yes it can. The technology already exists for clean and renewable energy based electricity generation to provide for all our needs. All it requires now is the political will and stripping the subsidies from fossil fuel and nuclear to make it a reality. Solar power is comparatively cheap already if you consider the true cost of coal. By the way, this article was written courtesy of solar power - and on a cloudy day too.

It's kind of sad to think we're willing to take the risks associated with nuclear energy in order to help power non-essential items such as big screen TV's and game consoles. 

Here's hoping the people of Japan are not again subjected to the nightmare of a widespread radiation incident on top of everything else they have to contend with at the moment.