A short breakdown, the reactors got hit by an earthquake, which they withstood with flying colors. But then the Tsunami came... All the security measures for the facility where built in the basement, the tsunami flooded the entire complex and submerged backup generators and batteries, meaning that the plant was literally dead. There was no way of preventing what happened next. The vital cooling systems were shut down and the reactor temperature (from decay heat) started rising, hydrogen started building up and that's what eventually precipitated the explosions.
These problems were all avoidable, let's call this a critical design error... And we can only hope that the people responsible for this have learned from these fundamental mistakes.
These explosions where hydrogen/steam explosions. No nuclear material exploded, which by the way is impossible in reactors. Read why...
The explosions caused volatile radioactive particles to be released into the atmosphere, and water containing radioactive particles spilled into the ocean and groundwater. Fortunately the particles have become incredibly dilute over time, meaning that they will pose little to no real threat.
Ben Heard from ThinkClimate has visited Fukushima and has written an interesting in depth article about the current situation in and around the complex
Not humbled, angered. The response to Fukushima is an ongoing mistake. Part 1
I don't want to come over as someone who sweeps all the bad under the rug, there are things that need to be addressed critically, that deserve a high measure of scrutiny and seriousness. If light/heavy/pressurized water reactors are concerned we need to be very vigilant, especially with the containment and safety measures.
That's the point where I progress, if someone would ask me : "would you like to see more solid fuel nuclear reactors?" my answer is clearly no. I don't want to see any new ones build, why? Because we can do better, far better.
There are two nuclear developments that are very promising in terms of safety, efficiency, and waste issues : The push for nuclear fusion and Generation IV Reactors. I'm absolutely psyched about nuclear fusion, however we are still in the "it will happen next decade"-stage.
The other sounds quite paradoxical, I'm an avid supporter for Molten Salt Reactors, these are now categorized as Generation IV reactors, but the idea is actually quite old, the first Molten Salt Reactor Experiment ran for a couple of years in the sixties. We had the capability to run this experiment for a couple of years more than fifty years ago.
The MSRE (image : http://www.the-weinberg-foundation.org)
What is a MSR? Basically all electricity generators run on the same basic principle : We convert energy content of some sort of feedstock (petroleum, coal, lignite, gas, uranium) into heat, this heat gets transported towards a turbine, which in term turns a big dynamo that generates electricity.
A light Water Reactor (image : http://en.wikipedia.org/wiki/Light_water_reactor)
Simplified : we boil water (or carbon dioxide or other transportation mediums), to run a dynamo. The boiling part is very different in a nuclear reactor. A contemporary nuclear reactor works with a solid fuel cycle, meaning that there are pellets of uranium stacked in a rod. The nuclear reactions might seem very ominous and difficult but generally speaking it isn't that hard. You take a fissile Uranium atom, hit it with a neutron, and it splits into smaller parts, releases two or more neutrons and heat. The neutrons are required to keep the process of splitting atoms going. We can stop the process by blocking the neutrons, this is done by "control rods", these basically stop the flow of neutrons, and thus stops the reactions. This does not mean that the fuel rods will cool down, there's also decay heat from the decaying atoms in the rods, so we need to keep them cool.
The energy content of an atom is stupendous, thanks to the mass-energy equivalence from Einstein we can deduce that using the energy that holds the atom together is an amazing source of energy.
In a MSR we change several paradigms :
- We do not use water as a cooling and working fluid but use a molten salt as the working and cooling fluid.
- We do not use solid fuel pellets, the fuel is mixed into the molten salt.
- We use significantly less water than in a contemporary reactor.
- We will be able to use more sources for fuel i.e. fertile and fissile materials.
A Molten Salt Reactor advertised by TransAtomic power
The Molten Salt Reactor is a game changer in the energy landscape, it can use materials more ubiquitous on Earth and in space : Thorium. Thorium by itself is not fissile, it is fertile. This means that it doesn't fission straight away if you hit it with a neutron. What you do is this : you hit it with a neutron, it turns into a different element which decays into a fissile uranium atom, you hit this with a neutron and you get the same as mentioned before : the atom splits into fission products, neutrons and energy gets released in the process. This process takes place in a so-called breeder reactor.
These reactors are inherently safe, this is because the working / cooling fluid has a high melting point, the melting point is (depending on the salt used) about 300 degrees Celsius. You basically have to keep heating it, in order for it to remain a fluid. This also means that if things go wrong, a freeze plug melts which in term drains the working fluid into subcritical drain tanks, in which the salt simply gradually cools down. If by some horrible accident salt got spilled, it would simply become a solid, relatively easy to clean up. The other basic safety feature in MSR's is that they run at atmospheric pressure, the liquids in the reactor do not "want" to get out, and maintenance is far easier.
- Fuel efficiency goes up dramatically from a meagre 3-4% to a staggering 90+%
- The MSR's are far cheaper than contemporary nuclear reactors. http://www.thoriumenergycheaperthancoal.com/
- MSR's can be mass-produced.
- Due to this higher efficiency, we will have significantly less nuclear waste, and shorter lived waste. It is a major game changer in terms of waste issues.
- The reactors are "walk away safe", which means that if there is a calamity, no people are required to keep backup systems running, the reactor has passive safety features such as sub critical dump tanks or buffer salts.
- No cooling water required i.e. alleviation of water stress.
- Some designs can "eat" Nuclear Waste and Nuclear Weapons, they turn them into electricity.
- Medical Radio isotope production (the stuff needed for cancer treatments, x-ray machines, MRI scanners, and a multitude of other medical diagnostic tools and processes.)
- Production of isotopes useable for small scale energy production i.e. RTG's used by NASA for space exploration.
- The propensity to desalinate massive amounts of water.
I am absolutely confident that the MSR will change the energy landscape, and it will change it significantly. It has the propensity to kick fossil fuel out of the picture, it will be a gradual process though, a process in which a lot of things need to be ironed out, but I'm quite confident that we will get there.
What is the nuclear promise to me? A plentiful source of energy, free of harmful emissions, which will raise the living standards for all inhabitants on earth, which solves our energy problems, our water issues and which makes a sustainable future on Earth possible. The added bonus is that it will help us go farther into space, it is there where a lot of solutions to our problems can be found, and it is the most inspiring thing we as human beings can do. Nuclear energy, in particular MSR's and Fusion Reactors will help us develop more knowledge and understanding, achieve more greatness, and help us continue on the path of innovation and discovery.Terrestrial Energy
A few notable contenders :
A few notable contenders :
Who else is working on Thorium based nuclear reactors?
More information on Molten Salt Reactors :
the weinberg foundation
Let's make it happen!