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TEPCO released data for all spent fuel rods. Here is the diagram from Asahi Shimbun:

The top row with numbers is the capacity of the spent fuel pools in cubic metres. The second the number of rods in them. In No. 4, the 1331 number includes 783 spent fuel rods and 548 half-used rods from the core.

The third row is the heat production of the fuel in the ponds, in units of ten thousand kilo-calories per hour. They say that the water in the No. 4 pool heated up at a rate of 2°C/h (apparently taking the displacement of the fuel rods into account), and would completely boil away in ten days.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Mar 18th, 2011 at 03:12:24 PM EST
[ Parent ]
At a rate of 30-40 tons of water a day, it will take a lot of time to replenish the No. 4 spent fuel pond... even if cooling systems can be re-started.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Fri Mar 18th, 2011 at 03:48:41 PM EST
[ Parent ]
Especially if some of the spent fuel pools don't hold water. In that case dropping boron and sand would seem to be indicated. Then water could be dropped on that. This disaster is no where near Chernobyl levels -- yet. But it still has great and terrible potential. Per NBC Evening News the US has recommended covering the exposed and evaporating spent fuel pools with sand and boron but the Japanese have not agreed. What valid considerations might there be for not covering them?

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Fri Mar 18th, 2011 at 08:20:30 PM EST
[ Parent ]
I am guessing here, but if they get water cooling working they know how to handle it and eventually get the waste out of there. If covered with sand and boron, then what? Chernobyl-style sarcofagus and hope it is not broken by another quake?

Sweden's finest (and perhaps only) collaborative, leftist e-newspaper Synapze.se
by A swedish kind of death on Sat Mar 19th, 2011 at 05:14:37 PM EST
[ Parent ]
If covered with sand and boron, then what?

If no cement was used, just remove the sand and boron, wet or dry. Use a giant vacuum if dry or siphon if wet. Same principle as you use to clean the bottom of an aquarium, but instead of a 1/4" tube (6mm) use a 4" (105mm) pipe. It would create tons of additional material requiring special disposal but would protect against recriticality and/or fire which could spread MOX dust in the atmosphere. Not doing that seems like a gamble that they are not going to have a fire started with dry fuel rods. Doing it creates additional cleanup expense.

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Sat Mar 19th, 2011 at 09:11:35 PM EST
[ Parent ]
Then I can see no reason not to do it.

Sweden's finest (and perhaps only) collaborative, leftist e-newspaper Synapze.se
by A swedish kind of death on Sun Mar 20th, 2011 at 03:56:09 PM EST
[ Parent ]
so 1425 cubic metres is 1425000 kilos of water at 2 degrees per hour thats 11970000 Kj per hour output, enough to  turn 5,303 kilos of water to steam. so each hour five tons of water are vanishing from the reactor pool minus some for heat to leak into the environment through the pool walls. big question is how much of that leakage occurs (from their figures they reckon 10 days and that would be 6 tons per hour turning to steam) I feel some of their figures somewhere are a little loose.

Any idiot can face a crisis - it's day to day living that wears you out.
by ceebs (ceebs (at) eurotrib (dot) com) on Fri Mar 18th, 2011 at 04:02:12 PM EST
[ Parent ]
so 1425 cubic metres is 1425000 kilos of water

I think they took the displacement of the fuel rods into account, so less.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Mar 18th, 2011 at 04:17:10 PM EST
[ Parent ]
  • If the fully loaded tank is assumed to heat by 2°C, then they assume 1,000 tons of water.

  • 2,000,000 kilocalories per hour is 8,360,000 kJ/h. At 2,257 kJ/kg, this can evaporate 3,704 kg/h. In ten days, that would be 889 t. Checking, the article actually says 10 to 11 days.


*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Fri Mar 18th, 2011 at 04:25:07 PM EST
[ Parent ]

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