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They have been pumping seawater into the reactors

Actually they switched to sweetwater a few days ago.

and, I presume, the spent fuel storage pools

No, only the reactors. They used special fire trucks to pump water into the spent fuel pools.

One of the reactors is cracked, therefore leaking

Tow of the containments are cracked, but that doesn't necessarily mean that there is a leak, because some reactors had water only in the pressure vessel (which is another level inside the containment).

Fuel rods are partially melted in some (all?) of the reactors

Meltdown in reactor cores happened when the reactor's last backup cooling system failed and before the improvised seawater pumping started up, so meltdown can presumably be put in past tense. But the rest of the conclusion is true in all cases.

circulation would be sufficient to dissipate the heat

Dissipate where?

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

by DoDo on Tue Mar 29th, 2011 at 11:13:10 AM EST
[ Parent ]
DoDo:
They have been pumping seawater into the reactors

Actually they switched to sweetwater a few days ago.

TEPCO : Press Release | Plant Status of Fukushima Daiichi Nuclear Power Station (as of 4:00 PM Mar 29th)
-At approximately 2:30 am on March 23rd, seawater injection to the nuclear reactor through the feed water system was initiated.
-At approximately 10:50 am on March 24th, white fog-like steam arising from the roof part of the reactor building was observed.
-At approximately 11:30 am on March 24th, lights in the main control room was restored.
-We had been injecting seawater into the reactor, but from 3:37 pm on March 25th, we started injecting freshwater.
-At 8:20 am on March 29th, we switched injection of fresh water from using fire engine to temporary electrical pump.


So, in what may be my last act of "advising", I'll advise you to cut the jargon. -- My old PhD advisor, to me, 26/2/11
by Carrie (migeru at eurotrib dot com) on Tue Mar 29th, 2011 at 11:16:41 AM EST
[ Parent ]
Freshwater into No. 1, start of pump:

TEPCO : Press Release | Status of TEPCO's Facilities and its services after the Tohoku-Taiheiyou-Oki Earthquake (as of 4:00PM)

-At approximately 2:30 am, March 23rd, we started the injection of sea
 water into the reactor from feed water system. After that, the injection
 of freshwater was started from 3:37 pm on March 25th (switched from the
 seawater injection). At 8:32 am, Mar 29th, transfer from the fire
 fighting pump to a temporary motor driven pump was made.

No. 2:

-From 10:10 am on March 26th, freshwater (with boric acid) injection was
 initiated. (switched from the seawater injection) At 06:31pm, Mar 27th,
 transfer from the fire fighting pump to a temporary motor driven pump was
 made.

No. 3:

-From 6:02 pm on March 25th, the injection of freshwater to the reactor
 was started (switched from the seawater injection). At 8:30 pm on March
 28th, the injection of fresh water is switched to temporary electricity
 pumps from the fire engine pumps.
-At approximately 12:34pm March 27th , the injection of water by the
 concrete pump truck was started. At approximately 2:36 pm, March 27th,
 the operation was finished.
-At approximately 2:17pm March 29th, the injection of fresh water by the
 concrete pump truck was started. (Sea water had been injected so far and
 transfer from seawater to freshwater was made)

(They don't say but the concrete pump truck relates to the spent fuel pool)

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

by DoDo on Tue Mar 29th, 2011 at 11:22:18 AM EST
[ Parent ]
Meltdown (my emphasis):

Radioactive water at No. 2 reactor due to partial meltdown: Edano | Kyodo News

He said the government has been informed by the Nuclear Safety Commission of Japan that ''water in a containment vessel that came into contact with fuel rods that partially melted at one point is believed to have been leaked,'' referring to the high levels of radioactive water found at the basement of the reactor's turbine building.

Edano told a news conference that the government believes the meltdown is not continuing.



*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Mar 29th, 2011 at 11:49:11 AM EST
[ Parent ]
But the meltdown could easily resume if they cannot continue present emergency measures. How do we calculate the time to cold shutdown in a reactor where there has been a partial meltdown. Seems we need better definitions of "partial". It matters whether the rods have cracked and the pellets have been exposed to sea water or whether the pellets have fallen out and collected on the bottom where recriticality is conceivable, especially in #3, with MOX fuel.

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Tue Mar 29th, 2011 at 03:00:29 PM EST
[ Parent ]
well we'd need to draw a graph of the temperature results, Im sure I saw in an Oildrum thread that  its cooling approximately 20% slower than the reference cooling curve.

Any idiot can face a crisis - it's day to day living that wears you out.
by ceebs (ceebs (at) eurotrib (dot) com) on Tue Mar 29th, 2011 at 03:22:15 PM EST
[ Parent ]
Certainly. Active cooling will be needed for years.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Mar 29th, 2011 at 05:10:20 PM EST
[ Parent ]

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