This development looked somewhat alarming. Apparently the spent fuel pool from the Fukushima Daiichi reactor 4 building has lost cooling as of 6:25 AM EST Saturday Morning (6/30/2012) as per
WSJ MarketWatch. According to TEPCO the temperature climbed at a rate of 0.26 C by late Saturday afternoon. Quoting
MarketWatch:
[...]
If Tepco continues to be unable to cool the pool, the temperature could
reach 65 C, which is the upper limit designated in the safety
regulations, on Tuesday morning.
[...]
Here is another estimate from
Fukushima Diary if the spent fuel pool cooling is offline for a longer period:
[...]
Prof. Takeda [Link] estimates the coolant water of SFP4 will reach 100℃ in the evening of 7/5/2012 (Thursday).
[...]
Spent fuel pool 4 contains
1535 fuel rods and there have been continued fears that a collapse of the elevated pool due to another earthquake could cause a massive release of radiation in to the environment, possibly rendering Japan uninhabitable.