Kitazawa: Reactors surface temperatures below 100C

Japan's Defense Minister says the surface temperatures of the 4 damaged reactors at the Fukushima Daiichi nuclear power plant are lower than 100 degrees Celsius. Toshimi Kitazawa told a news conference in Tokyo on Saturday that water-spraying proved to be effective in cooling down the temperature of the spent fuel rod pool of the No.3 reactor.

He said SDF officials measured the temperatures while observing the damage from a helicopter.

Kitazawa said the government's disaster task force reports that a temperature of less than 100 degrees Celsius shows the reactors are more stable than had been expected.

...snip...

Kitazawa said he believes the sprayed water is filling the spent fuel rod pool to a significant degree.




http://www3.nhk.or.jp/daily/english/19_24.html

I'm not so sure I want to believe a word of that. Nothing on your part FBaggins but I'm an old man who has been paying attention for many years concerning nuclear energy and the only constant I've found is they lie. I know this man is not an employ of the company so he's just passing along this info but he got his information from the nuke boys

Too much heat carried away too quickly coupled with too small of a surface area to allow that to happen =, yup you got it, another more than likely lie.

The surface temperature where the water is hitting that surface may show a 100 degree celsius reading but take that water away for a bit and see where the temperature goes. There is simply not enough surface area for the water spraying on the reactor to have much if any effect on whats going on inside. This information is designed to mislead an already and rightly so scared public is my opinion of this.

The liquid water would either (1) turn to vapor within the pool of water and bubble out or (2) vaporize at the surface.

In any case, the heat is leaving through other modes than "radiation, convection, or conduction".

Nothing wrong with your skepticism about the PR, though.

We don't get all the details that we would like. I assume this is an IR scan of the building itself looking at surface temperatures.

It's entirely possible for spots inside the building to be hotter than that and not have it show from a helicopter. So the fuel pool could still be boiling and not have that be clear (based on this limited report).

It does, however, mean that you don't have a boiled-dry pool (that water just isn't getting to), with burning fuel rods raging away. But we already knew that (since there aren't billowing masses of smoke).

Frankly... I don't know why they don't just fly a hobby copter right into the hole and send out pictures of the pool. I've got one that should be able to do the job... surely the Japanese have them.

That's just a guess. NASA certainly succeeds in having electronics operate in high radiation environments, but it may be that there is nothing readily available that is sufficiently hardened and can be used as you suggest.

Even in an almost-dry pool, by far the highest levels of radiation would be directly above it... By which time you've already got the image.

Besides, mine was $40 at Costco. They could have 100 of them give it a try. It isn't as if there isn't already debris in the pool.

I'm pretty sure it says somewhere on your hobby copter's package not to discard the batteries in a nuclear reactor fuel rod pool.

They're probably worried about the environmental damage. :)

providing you didn't build it yourself.
I can't wait until my grand daughter gets old enough to appreciate one so I can buy her one as I want to play with an RC coptor like they sell so bad but don't want to look like an old fool out here playing with one on my own, :-)

About that reactor and best I remember that was the subject, spraying water on its surfaces isn't going to help much if any. The latent heat of evaporation isn't enough to do the job plus the heat transfer through the steel vessel is not very good either so inside that bugger its hotter'n hell.

Yep... that's the one I got too. :)

Don't go for the $30-50 styrofoam models that are sold all over the place. They just aren't nearly as controllable.

The next step up (really a bit below true "hobby" class) are usually $100-$150, but Costco has had one twice that came in rought around $40. Far more stable... far easier to control. Far more damage if you crash it, but it's easier to avoid crashing it.

About that reactor and best I remember that was the subject, spraying water on its surfaces isn't going to help much if any. The latent heat of evaporation isn't enough to do the job plus the heat transfer through the steel vessel is not very good either so inside that bugger its hotter'n hell.

If we're talking about spraying the building or the concrete containment that's pretty sure to be true. Spraying hot exposed fuel rods would not be a waste... particularly when you can keep the spray up for hours on end. If you compare that to water in a pool where the water is not circulating to some form of heat exchange (radiator/whatever) there there isn't much different. Once the pool heats up, the net cooling (if you ignore overspray/missing the target) should be about the same.

that says they have bored a couple of holes into two reactors to relieve pressure. It did not say which reactors, and I think, they are incorrectly calling the outer buildings, reactors. What question comes to mind, is which two reactors, because the buildings housing problem reactors seem to have ample ventilation at this point. That leaves #5 and #6 which I thought their ponds had been stabilized by sharing a generator for pumping and circulation.

Anyone heard any information on these new attempts to reduce pressure at two reactors?

For one thing... the other reactors already have "vent holes" in them. :) (Ah... I see you made the same point).

Could be an expected modification in the future. I'd guess that the plant's ability to vent hydrogen (which you need over fuel pools anyway) is probably electric. They need to add a few windows (whatever) that can be opened manually.

which I thought their ponds had been stabilized by sharing a generator for pumping and circulation.

Reactors in normal operation keep a careful watch on spent-fuel pools for hydrogen buildup. There isn't much over a cool pool, but it does happen. I think it's all pretty automatic when the power is on.

as the wind direction changes back toward habitation. The explosions so far have been through hydrogen build up, and devastated the inner workings of the reactor buildings more often than not. Why risk a similar explosion, and the little remaining infrastructure for cooling, if the electricity ever gets reconnected.

I don't think that they've used any seawater (etc) in those two (can't see why they would anyhow).

The other four are the obvious priority, but it would really suck to lose multi-billion-dollar assets because you took your finger off the button for a few hours. Drilling a few holes is a cheap insurance policy. Do it when radiation levels are high on the other end of the plant and you won't even waste critical manpower.