[ RadSafe ] Chernobyl

[KARAM, PHILIP]

Chernobyl was water-cooled and graphite-moderated, compared to most other commercial plants that are water-moderated and water-cooled. When our plants lose coolant they also lose moderation so fission stops. When Chernobyl lost cooling it did not lose moderation, so it kept producing power until the steam explosion blew the core apart.

I visited a Chernobyl-type reactor in Lithuania about 10 years ago. There was no containment, just a 7-meter thick plug of concrete, lead, and steel (the bioshield) set into the floor of the reactor hall with the reactor beneath. The structure itself had all the structural soundness of a Home Depot store - when the steam explosion blew the bioshield out of the floor there was nothing to contain the fission products that followed. Plus the burning graphite moderator, of course.

Andy