This was a semi-modular design I saw...
Posted on 01/30/2010 8:54:46 PM PST by Hostage
One of the more promising nuclear reactor technologies known today is the pebble bed nuclear reactor.
Offering many advantages over conventional reactors, the pebble bed reactor gets its name from the type of the nuclear fuel it consumes. Just like conventional reactors, the pebble bed reactor can fission uranium, thorium and/or plutonium as its nuclear fuel. But the similarities end there. Instead of forming the fuel into plates or pellets as in conventional reactors, the pebble bed reactor fuel is manufactured into spheres, known as “pebbles,” slightly smaller than a tennis ball. Simply stacking the pebbles together in a pebble bed in the reactor can form a critical geometry that initiates the nuclear fission process. Instead of being cooled by water as in a conventional reactor, helium gas is used to cool the spherical fuel elements.
The most widely used spherical fuel is made up of thousands of coated particles known as tristructural-isotropic (TRISO) particles. As shown in the diagram, the center of the particle is typically uranium dioxide, known as the fuel kernel, and is .5 mm in diameter. The fuel kernel is coated with a layer of porous carbon which serves to capture any fission product particles emitted from the fuel kernel. Three additional layers of carbon are then applied to each particle: an inner layer of pyrolitic carbon; a mid-layer of silicon carbide; and an outer layer of pyrolitic carbon. These layers provide the structural support necessary to endure irradiation during the fission process. Thousands of these TRISO particles are then embedded in a graphite matrix and formed into a sphere.
One of the major advantages of the pebble bed reactor is that it is extremely unlikely that it will ever suffer a catastrophic meltdown at high temperatures.
(Excerpt) Read more at nuclearstreet.com ...
Short conclusion is there exists an inherently safe more efficient nuclear power reactor design.
And from experience, safety is more than half of what makes conventional water-based nuclear core reactors so costly, i.e Pebble Reactors are the way forward.
Of course the libs will scare everyone away from such a viable source of energy....
I have been advocating this for years.
It is safe and scalable. I could see one of these providing energy for small towns.
This is what the USA should put its resources into developing, and export it to the rest of the world.
Street demonstrations start tomorrow.....Code Pink will lead parade.
Complete agreement with you but I don’t see anything of it in the mainstream press including Fox News.
Too practical. We’ll have to mandate that power companies turn it off if the wind isn’t blowing.
Thorium based reactors are another alternative I read a little about recently.
ping
Samething I think. There is a Thorium Pebble Reactor in Germany I believe. THe article says it can fission either Uranium or Thorium.
What makes the Pebble design so safe is the carbon packaging and something known as the doppler braodening of absorbed neutron energies as temperatures rise. In other words, the hotter it gets, the more it slows the heat generation, so that it ‘idles’ at a temperature far below meltdown.
Long and short, it can’t melt down and it can’t explode.
And its gas coolant makes it much more efficient so that it can be a lot smaller to yield the same power output.
Awesomeness!
A close friend of mine, a Nuclear professor at MIT, has been telling me about the advantages of the pebble bed reactor for the last ten or so years.
It was great to finally understand the technology that he was trying to teach me.
As an ex-executive of a large nuclear piping/valving/support corporation that went out of business after the dirth of contracts after three mile island, I’ve always looked at nuclear as the way forward.
Good to see that they have new designs! Now if we can only convince the public to drop the NIMBY crap!
Yeah it’s been around for quite awhile. Maybe the time has finally come for it to breakout. I sure hope NOT to see a revival in water-based nuclear core reactors. IMO they will always be too costly and invite endless safety questions and reviews.
This tech is the way to go forward.
“...TRISO particles are then embedded in a graphite matrix...”
Graphite matrix. Great!
When Chernobyl ripped apart due to steam lines rupturing and the fuel rods shattered by the force of the escaping steam, the graphite which was used to cool the fuel rods burned, sending out towering smoke clouds which carried the pulverized fuel particles hundreds of miles. That iconic photo of Chernobyl post-accident depicting a fire burning where the reactor had once been wasn’t of the fuel - it was the graphite coolant burning.
I read the official NRC report after the accident.
Yes, I know that the pebble bed reactor is supposedly safer but hell, the Titanic was unsinkable. The truth is that any nuclear facility is only as safe as the people hired to operate and manage it. If a facility is supposedly idiot proof the risk involves hiring people who are not as safety concious or as well trained as they should be.
High-pressure water reactors had a ready trained cadre of personnel available: the U.S. Nuclear Navy. Navy trained reactor operators as a source of employees was reliable; besides being thoroughly trained and experienced, they had already passed security checks and psychological screening. What would be the reliable source for pebble bed reator operators?
I wonder how much waste it produces relative to conventional reactor. It sounds like it could be a lot. Presumably the entire sphere will have to go to Yucca when it’s used up.
Yeah, and can’t possibly be used for weapons research as well or something like that.
Good points but a bit unfair to compare with Chernobyl which was a completely different design that would of course melt carbon graphite or most any number of materials.
And plant safety always depends on people whether fossil, nuclear or anything, so your point is well taken.
Also unfair to compare with the Titanic which was on its maiden voyage. The Pabble Reactor has been around a long time and has an auditable track record.
Good question but I would direct you to read about the much higher efficiency of its gas coolant design which alone should make it more fuel efficient, therefore less radioactive waste per kilowatt-hour.
Certainly seems that it would be more difficult to process for weapons grade fuel.
This was a semi-modular design I saw...
Chernobyl ripped itself apart because the dillweeds running the plant were doing “what if” tests they shouldn’t had been doing. Simply put, “pencil pushers” from central command, who had no damn business being there, got a fat ego and didn’t think things trough.
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