[Henk]

The major problem with restarting them is if they can't do it right away (4 to 6 hrs), then they will have to wait until the xenon dead time passes. This takes about a day I think.

Xenon builds up when the reactor is shut down. It prevents the nuclear reaction from occurring. During operation, the reaction overcomes the production of xenon by "burning" it up as fast as it is produced. Once shut down, the xenon builds up and there is not enough reactivity ("ooomph") in the core to get a chain reaction started again.

Here's a link describing the phenomenon.

[ThirdMate]

Thanks for the solid info. Would they attempt a startup using standby diesels, or wait for outside power?