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Restoration at nuke plant disrupted, radiation fears spread to Tokyo
Kyodo News Japan ^ | 24 March 2011

Posted on 03/23/2011 1:09:44 PM PDT by AwesomePossum

...black smoke was seen rising at the No. 3 reactor building...surface temperatures...have topped the maximum levels...high-level radiation amounting to at least 500 millisieverts per hour was detected...

(Excerpt) Read more at english.kyodonews.jp ...


TOPICS: Breaking News; Extended News; Front Page News; Japan
KEYWORDS: heat; nuke; pullback; radiation
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To: dayglored
Since we have the physics guys on the thread, the article contained the following quote:

"While the maximum vessel temperature set by the reactors' designers is 302 C degrees, the surface temperature of the No. 1 reactor vessel briefly topped 400 C and dropped to about 350 C by noon, and that of the No. 3 reactor vessel stood at about 305 C, the agency said."

350 C is only 662 F. That seems to be very low for a stainless steel structure. You could barely melt lead (327 C) at those temperatures. Stainless Steel shouldn't melt until over 1500 C. Is there something else going on here or do they just have a massive safety factor built into their warranties.
21 posted on 03/23/2011 1:39:13 PM PDT by GonzoGOP (There are millions of paranoid people in the world and they are all out to get me.)
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To: bvw

Who reading this forum is going to die from someone saying this stuff is incredibly bad? Anyone that weak?

And how? Suicide? Get over it. Nobody is saying it’s the end of the world. It is possibly the end of that area of Japan though.


22 posted on 03/23/2011 1:40:35 PM PDT by Tolsti2
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To: dayglored
I saw what happened to the containment roof when water was pumped into the reactor. Classic dry boiler explosion.

The spent rod pools are another matter since they are not contained under pressure. I still cannot figure out how you regain temperature control of an overheated core due to a total lack of cooling water? My industrial experience calls for the boiler fuel source to be locked out until the boiler is less than 100 degrees above ambient facility temperature. That can mean having to wait 24 hours to refire.

So I'm guessing that instead of cooling water pumps as reported, superheated steam has to be injected into the cooling system slowly. Then once the flow of superheated steam is able to peak at a manageable pressure, heat exchangers and makeup steam at incrementally reduced temperatures needs to happen. Something like no less than a few degree drop per six hours. I would thin once cooling steam reached condensate levels, you could introduce cooler makeup water and then really get thing cooled down. That whole proces would take months.

23 posted on 03/23/2011 1:40:46 PM PDT by blackdog
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To: meatloaf
2. The reactor vents into a torus, larged water filled structure, which reduces pressure.

That is true - the reactor vessel is where they're injecting sea water. The steam is vented into the large torus which is filled with cooler water. This reduces pressure by at least partially condensing the steam back down to water. The Torus is inside the containment structure as well. They have had to "burp" the containment structure on 1, 2, and 3 a couple of times because the pressure inside the containment was too high as a result of the torus not being adequate to cool the steam coming out of the reactor.

3. The spent fuel pools, stainless steel lined concrete, which are outside the primary containment and which are probably now exposed have been the target of the helicopter water drops and the water from the fire engine deck guns.

They also have one of those concrete booms up now to spray water into unit 4's pond since access to the spent fuel pond apparently is limited to using a hole in the side of the building. BTW, units 5 and 6 are using their normal cooling process to cool the spent fuel pools as well as the main reactor cores. They may be salvageable.

24 posted on 03/23/2011 1:43:42 PM PDT by meyer (We will not sit down and shut up.)
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To: GonzoGOP

Stainles steel becomes very brittle after temperature cycling in excesses. That is why rewelding cracked stainless welds is very difficult if you want anything more than cosmetic repairs.


25 posted on 03/23/2011 1:44:20 PM PDT by blackdog
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To: blackdog

I dont usually rely much on Wiki but if you do some reading about light water reactors in general and Fukushima in particular it may help, give your mechanical background

http://en.wikipedia.org/wiki/Fukushima_I_nuclear_accidents#Cooling_requirements

then come back here and explain it to us!


26 posted on 03/23/2011 1:46:40 PM PDT by silverleaf (All that is necessary for evil to succeed, is that good men do nothing)
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To: Tolsti2

You are a danger to all around you.


27 posted on 03/23/2011 1:46:54 PM PDT by bvw
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To: mewykwistmas; AwesomePossum
Countdown to ‘radiation is actually good for you’ posters showing up.

Isn't it frickin amazing? I was always taught that radiation is a disaster for living things and it would be around forEVER.

Now we learn that it's a little thing that's not really important and it'll only be here for a little while. Hmmmmph. Whodathunkit?

If it's such a little problem, I don't get (even more!) why we can't have nukes in this country.

28 posted on 03/23/2011 1:47:37 PM PDT by HeartlandOfAmerica (Insane, Corrupt Democrats or Stupid, Spineless Republicans - Pick America's poison.)
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To: AwesomePossum

More robots sent in to tackle crisis at Fukushima
http://www.newscientist.com/blogs/onepercent/2011/03/more-robots-to-be-sent-in-to-t.html


29 posted on 03/23/2011 1:48:17 PM PDT by Selene
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To: bvw

Thanks, better to be feared than loved I guess. lol


30 posted on 03/23/2011 1:49:03 PM PDT by Tolsti2
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To: meyer
BTW, units 5 and 6 are using their normal cooling process to cool the spent fuel pools as well as the main reactor cores. They may be salvageable.

Not if they used salt water to cool them. There is going to be scale all over everything in the reactor Bessel and nobody is going to crawl in there to scrape it off. Once you get salt water into a system like this it isn't coming back. And heck the things were due to be taken out of service in less than a year anyways. No reason to take the risk of restarting a possibly damaged reactor. Just finish the shutdown.
31 posted on 03/23/2011 1:49:25 PM PDT by GonzoGOP (There are millions of paranoid people in the world and they are all out to get me.)
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To: meatloaf
The pressure vessels are part of the safety systems, but also become the problem once the reactor is overheated due to lack of cooling water/steam. The pressure vessels are really just steam bomb casings once a reactor superheats and any sort of cooling water is reintroduced.

What coolants do not expand under high temperature? (they would have to also be mighty plentiful)

32 posted on 03/23/2011 1:50:24 PM PDT by blackdog
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To: blackdog
Stainles steel becomes very brittle after temperature cycling in excesses.

Thanks. I knew the physics guys would have an answer.
33 posted on 03/23/2011 1:51:34 PM PDT by GonzoGOP (There are millions of paranoid people in the world and they are all out to get me.)
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To: bvw

Those without survival fear, soon perish. Think about it.


34 posted on 03/23/2011 1:51:43 PM PDT by Revel
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To: Errant

DUCK AND COVER!


35 posted on 03/23/2011 1:52:00 PM PDT by dfwgator
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To: Tolsti2

Feared? Only if that fear is like the fear of a nut who would light a match to check the level in a gas rank.


36 posted on 03/23/2011 1:52:39 PM PDT by bvw
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To: Cementjungle

37 posted on 03/23/2011 1:52:46 PM PDT by lonevoice (Where the Welfare State is on the march, the Police State is not far behind)
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To: GonzoGOP
350 C is only 662 F. That seems to be very low for a stainless steel structure. You could barely melt lead (327 C) at those temperatures. Stainless Steel shouldn't melt until over 1500 C. Is there something else going on here or do they just have a massive safety factor built into their warranties.

It's the concern over the fuel rods themselves that are of concern. If the reactor vessel is 300 C, then the fuel within is certainly hotter. The heat, as I understand it, damages and can break down the plating on the rods in such a way that at some point, a nuclear reaction can occur which would produce an enormous amount of heat.

The idea is to cool the fuel down to prevent it from going "critical".

Ideally, the entire fuel assembly should be covered with water (normally, circulating through a heat exchanger of some sort as part of its circulation, to remove excess heat). They're trying to achieve that with sea water, and they're adding boron or boric acid (not sure which) to further reduce and block neutron flow so that the fuel is much less likely to go critical.

38 posted on 03/23/2011 1:54:43 PM PDT by meyer (We will not sit down and shut up.)
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To: Revel

Think about what? Panic is not a survival skill, nor is fear mongering, nor is second-guessing and bad mouthing those at the situation and dealing with it.


39 posted on 03/23/2011 1:57:04 PM PDT by bvw
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To: blackdog; dayglored

The reason they can do that is because they are continuously venting.

I also believe they are doing more than venting. Remember the report yesterday about how they increased the amount of sea water by 9 times in reactor core 1(I believe) in order to cool it down.

Now it does not take much understanding to figure out that the coolant outlet is therefore wide open with the water running onto the land and into the sea. I believe that there no longer is a coolant loop. They are simply blasting water in and letting it run out into the environment. A continuing last effort attempt to prevent total meltdown. This prevents steam pressure buildup.


40 posted on 03/23/2011 1:58:23 PM PDT by Revel
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