In the wake of what has happened in Japan it is great relief for me to see that news agencies have once again started talking about nuclear technology versus nuclear disasters. For example, last Thursday the Times featured an article about a special kind of nuclear reactor that is currently being built in China, called a Pebble-bed reactor. This specific type of reactor is an HTGR or high-temperature gas cooled reactor meaning that instead of being cooled by water (like the majority of nuclear reactors out there are) this reactor is cooled with non-explosive helium gas. This means that if electricity were lost to the reactor (thus no water could be pumped for cooling), it could still be cooled by the gas. Great news right!
The Times talks about how instead of using "conventional fuel rod assemblies of the sort leaking radiation in Japan, each packed with nearly 400 pounds of uranium" the Chinese reactors will instead use "hundreds of thousands of billiard-ball-size fuel elements, each cloaked in its own protective layer of graphite"
Turns out that the "graphite coating" controls the speed of the nuclear reactions. It is truly awesome science. The Times even states that if the plant were to shut down due to an emergency, then the nuclear reactions would come to a stop all on their own (such smart little billiard balls of fuel).
So apparently this is old news...and this already started in Germany in the 1960s (but came to a halt and never preceded). Turns out that in the USA right now the government is working with Westinghouse and General Atomics to research similar ideas.
Sounds like a great idea to me. I hope to bring you more on the story...stay tuned!
PBMR's (pebble bed modular reactors) are also one of the favorite of the modular reactors being considered. The other is the VHTR (very high temperature reactor) known as the PSMR (prism small modular reactor). The technology is awesome in these things and the media needs to learn a little more about modern nuclear reactors such as these. Once they see the passive safety systems that are out now, the safety debate will change drastically. I am glad that you brought these up, as I was planning on talking about Gen IV reactors in the near future as well!
ReplyDeleteI'm not convinced this would change the safety debate drastically, because public fear is not really tied to what kind of reactor we implement. And until these things build up a track record...well, we'll have to see. I think some metaphors for explaining how these guys work would be very helpful--having "graphite shell" will mean nothing to most of the public.
ReplyDelete