NIRS has this very interesting update on the spent fuel pool at Unit-4 at the Fukushima-1 nuclear complex:

"UPDATE, 11:30 am, Thursday, April 14, 2011. The fuel pool at Unit 4 apparently has experienced an inadvertent criticality at some point in the past month. Tokyo Electric Power (TEPCO) has confirmed that some fuel rods in the pool are damaged. A 400 milliliter water sampling from the pool taken Tuesday found elevated levels (as much as 100,000 times above normal) of Iodine-131, Cesium-134 and Cesium-137. As nuclear engineer Arnie Gunderson of Fairewind Associates points out, there should be no Iodine-131 detected at all. All of the fuel from Unit 4 had been removed from the core and placed in the pool well before the March 11 accident. With a half-life of 8 days, the likely way Iodine-131 would be detected in this water would be if there had been a criticality—which given the severe damage to the pool is more than just conjecture. TEPCO, however, suggests the readings may be caused by radioactive rubble in the pool or radioactive rainwater coming into the pool.

TEPCO says it so far has pumped out 700 tons of highly radioactive water from a trench to a condenser; but with 60,000 tons of this water across three reactors, that's a proverbial drop in the bucket."

Charley Noble, off on the road for a week