Nuclear Power

With the threat of global warming and the potentially disastrous results it is necessary to look at all energy alternatives. For example hydroelectric and solar power. Also ones that have fallen into disfavor with the public need to be considered. Nuclear energy was once thought to be the answer to all of our energy problems. But after 3-Mile Island and Chernobyl it quickly lost its' luster. Fast forward 20 years and it is now time to take another look at it.

Although the nuclear power industry has kept a lower profile it does supply 20% of the power in the US and 80% in France. One of the main arguments against the technology is the waste that it produces. In the US approximately 2,000 tons of solid waste is generated per year. This is compared to 100,000,000 tons of ash and sludge from the coal fueled power plants each year. In addition there have been no fatalities from civilian nuclear power plants for the last 40 years in the US. Compare to this the people who die each year on coal mining accidents and the ten thousand Americans who die from pollution caused by burning coal.

The main issue with the public has been the concerns about the safety of nuclear power. Not unfounded concerns to be sure. Traditional nuclear power plants are water-cooled and need to have the core at high pressure so the water stays a liquid at such high temperatures. A new type of reactor has been designed called 'The Integral Fast Reactor', IFR, which uses a liquid metal as a coolant. This allows the core of the reactor to be ran close to ambient pressure which significantly reduces the chance that the core would lose its' coolant. The core and primary cooling pumps are immersed in a pool of liquid sodium. This makes the chance of losing the primary coolant a remote possibility. The reactor is also designed so that the cooling of the coolant is done through natural convection. This means that loss of power will not result in a run away nuclear reaction. The heat provided by the reactor is sufficient to keep the coolant circulating. This dramatically increases the safety of nuclear reactors.

The IFR reactors are also designed in a 'passively safe' configuration. This means that the fuel and cladding are designed to let neutrons escape with increased temperatures. Release of neutrons reduces the rate of the fission chain reaction. If the reactor got hot enough these escaping neutrons would be able to stop the reactor without any external intervention. So a runaway chain reaction is not possible.

With all good things there is a downside. That is liquid sodium is highly reactive with air or water. So if there were a leak of the liquid sodium you would end up with a sodium fire if air were involved and an explosion if water were involved. The IFR is designed for this and I'll cover this in the next article in this series.