Monday, October 23, 2006

Bye, Bye, China Syndrome

The most terrifying vision of nuclear power from the ‘70’s was the image of the self-melting radioactive lava from a former reactor core eating its way to China. People seemed to understand it intuitively no matter how over-represented the risk.

The new reactors make that scenario obsolete with a solution that’s “as dumb as a brick” - hire a bunch of boilermakers to lay down a brick patio under the reactor vessel. Of course, one has to use high temperature alumina brick and lay it about 1.5 meters (~5 feet) thick and wide enough to act as a “cookie sheet.” There will be minor specification changes necessary but nothing that the refractory industry can’t handle easily. Alumina brick is already used for lining glass furnances and slag pits.

Yet, I’ve have NEVER heard or read of the nuclear industry mentioning this in public. We engineers know about it but the ramifications of this feature on the public debate haven’t yet been communicated to the world. In my marketing classes at B-school, I was taught to never confuse a feature and a benefit (unintentionally, that is.) Nobody CARES about our firebrick patio, especially if we insist on calling them "passive corium barriers." But tell them that there can never be a China Syndrome in the new designs, that the China Syndrome is obsolete, and you’ve communicated a real benefit.

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3 comments:

Anonymous said...

[antinuke mode]

Aha - you see, the new reactors CAN melt down! Why else would they put this molten core-catcher under the reactor, when earlier builds didn't bother? These ones must be even worse than the last ones!
Bombs, radiation, birth defects, pollution, cancer, bombs! Please give generously!!

[/antinuke]

Kirk Sorensen said...

Or you could use a fluid-fueled reactor where the fuel is in a solution. In those reactors the probability of meltdown is 100%.

In all seriousness, what you're really after is a system to passively remove decay heat after the reactor has shut down. Assuming that you have a core-catcher, everything else must have already failed. Do they plan to embed the core-catcher with active cooling elements or do they assume that the thermal inertia of the core-catcher is sufficient to absorb decay heat? (at some point the thing will come into thermal equilibrium with its surrounding, but at what temperature?)

Joseph Somsel said...

A "core catcher" is, to my mind, the term properly used where criticality is a concern, ie for highly enriched fuel and are usually internal to the vessel. Fermi 1 had a core catcher. For LWRs with their low enrichment, corium can not go critical in any configuration therefore they do not have core catchers.

In any case, the short and sweet message is that the China Syndrome is a thing of the past and not a concern for advanced LWRs.

Let the anti's play defense on highly technical issues this time.