Thermometers working again at 3 reactors

[ReturnoftheDjedi]

Tokyo Electric Power Company says thermometers are working again at 3 of the reactors at the quake-hit Fukushima Daiichi nuclear power plant.

The March 11th earthquake and tsunami cut off power and the reactors' measurement equipment stopped working.

TEPCO tried to restore the instruments' functions with make-shift power sources, including batteries. It says the thermometer at the Number 3 reactor started working again last Saturday morning.

At that time, the temperature of the reactor's external surface was 366 degrees Celsius, much higher than normal. The company increased the amount of sea water it was using to cool down the reactor.

The thermometers for the Number 1 and Number 2 reactors were restored on Sunday.

The power company says it will pour more water onto the Number 1 reactor, as its temperature was 394 degrees on 3:30 PM on Tuesday.

TEPCO says the functioning thermometers, along with devices to measure pressure and water levels, will provide better information about the condition of the reactors.
Wednesday, March 23, 2011 06:12 +0900 (JST)
http://www3.nhk.or.jp/daily/english/23_10.html

These are temperatures readings from the external surface of the reactors.

394 C = 741 F

If these reactors are over 700 degrees F on the outside, it is almost certain that they are well over 1000 F on the inside.

Something is cooking in there.
They should be a lot cooler than this by now, unless a meltdown is, in fact, occurring.

[flamingdem]

1. Did you see the Arnie Gundersen interview about the thermal images?

He thinks temperatures are over 1000 F

[ReturnoftheDjedi]

2. this would seem to be proof of his claim. 750F on the outside, easily >1000 on the inside

but don't believe your lying eyes.

they're going to put it out with a firehose.

[flamingdem]

3. Turns out Arnie has a clue

And ding.. it's not looking good, no one is asking the right questions.

The US govt. probably knows what's up but what can they do now?

[Statistical]

4. No he said thousands of degrees. Plural would imply 2000+.

"I don’t believe the highest temperature is anywhere near that. It’s probably much nearer to thousands of degrees"

Arnie is full of shit given that stainless steel melts at 2500 degrees.

[flamingdem]

5. He meant thousands meaning over 1,000 degrees, in my opinion nt

[Statistical]

6. Lame. Nobody uses plural to indicate a singular.

"Man this sucks it is going to cost me thousands of dollars to fix my car". Most people wouldn't assume that actually means $750 to maybe $1000. They would rightly assume you mean THOUSANDS of dollars (as in $2K to some unknown thousands).

[ReturnoftheDjedi]

7. it could be thousands, we don't know. but it's at least 1000F, at least you can admit that, right?

[Statistical]

8. We don't know that is is AT LEAST 1000F. It may be 920F for example, or 870F or 780F.

It is high, it is beyond operating specs, and it is at least 700F+. Stainless steel is an effective heat conductor so the belief that the core would need to be many multiples hotter than reactor surface isn't true.

Still even 1000F is far less critical than the doomsday scenarios already predicted by some weeks ago. Like a molten core burning throgh containment.

Liguifying the nuclear fuel would require sustained 2200F temperatures and melting containment would require 2500F. The situation is severe and enough water needs to be added to remove heat from the core however there isn't an immediate threat of full meltdown even with 1000F temperatures. It has taken days of inadequate cooling for temp to rise from 300F to roughly 1000F. Obviously cooling (specifically improving heat transfer as you can't remove the source of heat you would a fire) needs to improve but it would take many more days of inadequate cooling before we get to a molten core scenario.

[CRH]

9. If the reactor vessel is made of very thick metal, ...

and metal readily conducts heat, isn't it possible the heat inside the vessel is very close to the outside temperature?

To me the largest concern is the destruction of the circulation system. If the heat inside the vessel is from normal decay of the cooling rods or some melt down, is of little difference at this point. Without circulation the only method of even maintaining this elevated temperature is through venting off pressure, i.e. radioactive steam. The pumps are sophisticated and but a small part of the cooling system. The repairs might not even be possible with the current conditions near the reactor, even if the parts can be shipped to Japan and moved into position for repairs. This could be days turned to months of status quo venting, just to maintain today's temperatures.

The first ten days have already put 50% of the Chernobyl volume of cesium into the atmosphere. With this and maybe other reactors needing venting possibly for months, and if the cooling ponds problems don't find a solution soon, the accumulative effects of a modest containment will be incredible.

Pray the cooling systems are not in as sad a condition as they appear.

[jberryhill]

10. Rectal or oral?