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A little high-level summary of knowns, unknowns and speculation from someone who hasn't been following all that closely, please complete/correct :

  • They have been pumping seawater into the reactors (and, I presume, the spent fuel storage pools) and need to continue to do so in order to prevent overheating
  • Is the topping-up required because of evaporation (boiling?) or because of leaks? Or both? In what proportion?
  • Are they still hosing the reactors and/or reactor buildings externally too? Is this necessary for heat dissipation too?
  • One of the reactors is cracked, therefore leaking
  • Others may be leaking from cracked pipes or burnt-out gaskets
  • Fuel rods are partially melted in some (all?) of the reactors, therefore the entire generation/cooling circuit contains fission products which would normally be confined inside the fuel rods themselves, and are now able to reach the outside world insofar as these circuits are leaking
  • I have no idea if there are any pumps currently working on any of the cooling systems : if they were, then surely they would not need to continue adding water, as circulation would be sufficient to dissipate the heat (unless the topping up is required because of leaks...
  • Perhaps they are afraid to run the pumps for fear of exacerbating leaks, or causing new ones?
  • They need to evacuate the contaminated water somehow, they have been sandbagging figuratively, and now literally
  • Prediction : they will announce barges within the next 12 hours (since this was first suggested on ET, what, 12 hours ago?)


It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II
by eurogreen on Tue Mar 29th, 2011 at 05:53:32 AM EST
Well we're not certain about the one of the reactors actually being leaking, it could be just broken pipework.

and your predicyion is optimistic, it usually appears to take 48 hours to announce an idea then a day or two more to implement it

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 06:00:19 AM EST
[ Parent ]
has been mentioned on ET, I find references on the net to a NYT article from Friday, but this article has since been redacted and no longer contains the paragraph in question. However, a syndicated version exists here which still has this :

Concerns about Reactor No. 3 have surfaced before. Japanese officials said nine days ago that the reactor vessel may have been damaged.

A senior nuclear executive who insisted on anonymity but has broad contacts in Japan said that there was a long vertical crack running down the side of the reactor vessel itself. The crack runs down below the water level in the reactor and has been leaking fluids and gases, he said.

The severity of the radiation burns to the injured workers is consistent with contamination by water that had been in contact with damaged fuel rods, the executive said.

"There is a definite, definite crack in the vessel -- it's up and down and it's large," he said. "The problem with cracks is they do not get smaller."

The contamination of the water in the basement of the turbine building where the workers were injured -- a separate building adjacent to the one that houses the reactor -- poses a real challenge for efforts to bring crucial cooling pumps and other equipment back online.

"They can't even figure out how to get that out, it's so hot" in terms of radioactivity, he said. A big worry about reactor No. 3 is the mox fuel. The nuclear industry has no experience with mox leaks, and it is possible that unusual patterns in the dispersal of radioactivity from the plant partly result from the mox, he said.

It's hard to imagine how anyone could make this stuff up and get quoted in the NYT. (Making stuff up and getting quoted in the NYT is not hard to imagine, but requires powerful interests to be at work.)

Officially, of course, no reactor crack exists. They don't tell us anything unless they absolutely have to.

It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II

by eurogreen on Tue Mar 29th, 2011 at 07:33:41 AM EST
[ Parent ]
We need to add to this the problem with the spent fuel pools, especially the one at #4, which has a working core also in storage. The problem with water that has +1 Sievert surface radioactivity is that it makes access to everything more problematic. Plus, there is an excellent chance that the spent fuel pool at #3 boiled dry or almost dry at one point.

I still do not know if they have applied boron powder or boric acid to the spent fuel pools or the cores. Of course boric acid is soluble and will leak out if there are leaks but will crystallize and remain if pools or reactor cores boil dry.

Metalic boron melts at 4000K, is insoluble in most acids and forms an oxide when heated in air. I don't know if it forms a surface, oxide-like, anodization that prevents further oxidation, but it seems to be a good substance to turn into small granules and drop into spent fuel pools with water. It is a good conductor of heat at higher temperatures also.  

"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 10:31:49 AM EST
[ Parent ]
Boron oxide is a glass.  (Think pyrex)

I would go with borax (sodium borate decahydrate) personally.  It's readily available, non-toxic, and at higher temperatures it releases lots of steam and turns into glass.  It is also anty-toxin.

by njh on Wed Mar 30th, 2011 at 07:36:00 AM EST
[ Parent ]
eurogreen:
They have been pumping seawater into the reactors (and, I presume, the spent fuel storage pools) and need to continue to do so in order to prevent overheating
They have reduced the throughput and have said they need to switch to fresh water ASAP.

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 11:05:38 AM EST
[ Parent ]
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 ]
This Facebook page is a valuable information hub on the Fukushima situation. I will not bother to list links and secondary references.

For what I heard, the prevailing winds the next two months are towards the ocean, as Siberia warms up slowly so far. Then the winds will turn more chaotic, and will blow mainly towards the continent later in  the summer. If the reactors are ot buried under concrete in two months, Japan will never be the same as we now it. On the other hand, the bottom has to be protected as well as the ground watertable is low.

by das monde on Wed Mar 30th, 2011 at 12:06:30 AM EST
[ Parent ]

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