Nuclear Reactors Hit By Earthquake In Japan

Discuss life, the universe, and everything with other members of this site. Get to know your fellow polywell enthusiasts.

Moderators: tonybarry, MSimon

Skipjack
Posts: 5645
Joined: Sun Sep 28, 2008 2:29 pm

Postby Skipjack » Sun Mar 27, 2011 11:59 pm

I might be missunderstanding something, but did somebody here seriously believe that there was a nuclear explosion of some sorts?
LOL

Betruger
Posts: 2237
Joined: Tue May 06, 2008 11:54 am

Postby Betruger » Mon Mar 28, 2011 12:51 am

chrismb wrote: hydrogen that doesn't burn with an invisible flame.
http://www.youtube.com/watch?v=MMB2VR0087w
I'm all ears.

Roger
Posts: 787
Joined: Fri Jul 06, 2007 2:03 am
Location: Metro NY

Postby Roger » Mon Mar 28, 2011 4:44 am

I've been looking at the list of isotopes that TEPCO started releasing from March 24th. And I have a question concerning the BA-140, LA 140 Cerium-140 decay chain.

heres the source info from the water in the turbine room @#3:

http://www.tepco.co.jp/en/press/corp-co ... 503-e.html

Image

Barium 140 half life is 12.8 days, Barium 140 decays to lanthunum 140 (half life of 40.5 hours) which then decays to the stable cerium 140.

http://energyfromthorium.com/tech/physics/decay2/

The ratio of Ba to La seems to suggest fission occurring after March 12th, roughly. But then if you look at the sample from March 26th

http://www.nisa.meti.go.jp/english/file ... 27-1-5.pdf

The ratio of Ba to La still suggests recent fission. Lets guess and say around March 14th.

If we then look at Technetium99m (Tc99m, half life of 6.02 hrs.) we see this present in samples from both the 24th and the 26th.

Does this not suggest fission as recently as 60 hrs from the time the sample was taken? If we assume that 45% of the fuel rods in Reactors #2&3 were uncovered, and 45% then "fell on the floor" of the reactors, are we talking the possibility of low level recriticality in reactors 2 & 3 ?
I like the p-B11 resonance peak at 50 KV acceleration. In2 years we'll know.

icarus
Posts: 818
Joined: Mon Jul 07, 2008 12:48 am

Postby icarus » Mon Mar 28, 2011 8:11 am

Skipjack wrote:I might be missunderstanding something, but did somebody here seriously believe that there was a nuclear explosion of some sorts?
LOL


No, who said that?

What was said was that the reactor vessel had most likely popped ... as in over-pressure failure and breached containment. If you examine the video you'll see the amount of concrete debris that gets airbourne (tall, narrow, gray plume) is more than just the few roof panels that reactor1's hydrogen explosion, (white smoke), tossed around. There is also a bright orange/yellow flame deep down in the building that is not consistent with hydrogen explosion explanation.

Skipjack
Posts: 5645
Joined: Sun Sep 28, 2008 2:29 pm

Postby Skipjack » Mon Mar 28, 2011 10:46 am

Ok, that makes more sense.
So when the reactor vessel blows that is simply a pressure explosion. How would that explain the flames?
They still have not sent in any darn robots yet?

KitemanSA
Posts: 6069
Joined: Sun Sep 28, 2008 3:05 pm
Location: OlyPen WA

Postby KitemanSA » Mon Mar 28, 2011 11:21 am

skipjack wrote: They still have not sent in any darn robots yet?
With a volume that "hot", would a robot work? Remember, the Space Shuttle main computer has processer equivalent to the old intel 286 generation because anything with smaller features is too subject to derangement by radiation.

Does any robot in Japan have features the size of a 286? Would even THAT size stand up to the radiation described in some of the publicatios (>1 Sv/hr)?

Sometime lower tech is better than higher tech, but if you have none...

Skipjack
Posts: 5645
Joined: Sun Sep 28, 2008 2:29 pm

Postby Skipjack » Mon Mar 28, 2011 12:23 pm

http://jalopnik.com/#!5786275/this-is-the-scariest-tsunami-video-yet


After watching this video, I have a hole different level of appreciation for the stability of that nuclear power plant. It seems really hard to compete with forces like that...

With a volume that "hot", would a robot work? Remember, the Space Shuttle main computer has processer equivalent to the old intel 286 generation because anything with smaller features is too subject to derangement by radiation.


Uhm, no. I dont know where you are getting these ideas from.
People constantly bring their laptops, ipods and other computers to the ISS with them.
The Space Shuttle computers were updated several times during the lifetime of the Shuttles. The last update brought a full glass cockpit. You think that you can run that on 286 CPUs? I doubt it.
I heard that until recently many systems were using 486 CPUs, because they are very robust and still onyl require passive cooling, but 286? I am sure not.
Also, there are actually robots that were specifically developed to work in nuclear power plants in case of an accident. If anything, you should be able to shield them sufficiently.

D Tibbets
Posts: 2711
Joined: Thu Jun 26, 2008 6:52 am

Postby D Tibbets » Mon Mar 28, 2011 4:08 pm

Criticality would imply nuclear explosion- at least on a tiny scale- that is what is happening in a normal active nuclear reactor. . Under the proper conditions this could result in a lot of steam pressure building up and result in an explosion, or at least contribute to an ongoing chemical explosion.Certainly a similar steam explosion could occur from the decaying fuel rods after shutdown. There would not be any direct color from this steam explosion. If some pieces of fuel rod were pulverized, at a temperature of ~ 1200 degrees C they would probably be glowing ~ yellow. But they would not be part of the explosion unless some remarkable brief conditions were met that led to nuclear fission. I suspect this would be extremely difficult at uranium concentrations of less than 5 percent. If they were MOX fuel rods though, I have no idea how the plutonium would respond.
But, my point is that the yellow glow at the base of the explosion has many possible explanations without needing participation by the core or core steel container. Again, the radiation surge would have been huge and persistent if the core was disrupted and dispersed. I would be more suspicious that the spent fuel rod storage tank could have been disrupted than the 6 inch(?) thick stainless steel reactor vessel. If so, there should be spent fuel rods scattered around the floor of the containment building and once again the radiation readings would tell the story.

The differential decay ratios mentioned above are interesting, though I'm not sure how many scenarios could result in the ratios. I do wonder about the shutdown design of the reactor. If the fuel rods are reaching temperatures of ~ 1200 degrees C, then the aluminum alloy(?) control rods would possibly be melting and slumping to the base of the reactor. Would this allow the fixed fuel rods to start active (at least on a low but significant level) neutron driven fission? This seems an obvious design consideration, but surely it was addressed in the design!. Boron injection might mitigate this, but only if the solution covered the rods (or if the fuel rods also melted and pooled in the base of the reactor and mixed with the boron left behind as the solution evaporated.

Dan Tibbets
To error is human... and I'm very human.

KitemanSA
Posts: 6069
Joined: Sun Sep 28, 2008 3:05 pm
Location: OlyPen WA

Postby KitemanSA » Mon Mar 28, 2011 6:15 pm

D Tibbets wrote:Criticality would imply nuclear explosion- at least on a tiny scale- that is what is happening in a normal active nuclear reactor.
I think "criticality" in a powerplant merely means a sustained nuclear reaction while in an nuclear bomb it means a run-away nuclear reaction. Same basic reaction, different rates, by MANY orders of magnitude! I suspect that if the core COULD go bomb-type critical, they wouldn't have to worry about evacuating the nearest 20 km because the plant would have already evacuated that region for them. :?

chrismb
Posts: 3161
Joined: Sat Dec 13, 2008 6:00 pm

Postby chrismb » Mon Mar 28, 2011 7:24 pm

http://en.wikipedia.org/wiki/Criticality_accident

Can it go up like a bomb? Let's see, now. Lots of molten heavy isotopes around, more than critical mass, heavy ones sink, light ones float. Will a critical mass find itself in proximity to some moderator (water?). Best to hope that this combination doesn't happen. Can it go up like a bomb? If fissile material is out of control and melting whichever way it wants to, why might it not go up like a bomb? 'All you have to do' is accumulate a 50kg lump of U235. A core in melt down might do that for you, no?


"Tokyo Electric Power Co. said Wednesday it is considering spraying boric acid by helicopter to prevent spent nuclear fuel rods from reaching criticality again, restarting a chain reaction, at the troubled No. 4 reactor of its quake-hit Fukushima No. 1 nuclear power plant. "The possibility of recriticality is not zero," TEPCO said as it announced the envisaged step against a possible fall in water levels in a pool storing the rods that would leave them exposed."

Ivy Matt
Posts: 674
Joined: Sat May 01, 2010 6:43 am

Postby Ivy Matt » Mon Mar 28, 2011 7:57 pm

D Tibbets wrote:Does boron burn with a yellow- orange flame?

Oh, I know the answer to this one:

http://www.youtube.com/watch?v=JzqdHkpXuy4

Skipjack
Posts: 5645
Joined: Sun Sep 28, 2008 2:29 pm

Postby Skipjack » Mon Mar 28, 2011 8:21 pm

I dont think it can go up like a bomb. Remember, building nuclear bombs is hard. The iranians have been trying for years without success. The North Koreans have not had much either.

ladajo
Posts: 5685
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Postby ladajo » Mon Mar 28, 2011 8:28 pm

D Tibbets wrote:Criticality would imply nuclear explosion- at least on a tiny scale- that is what is happening in a normal active nuclear reactor. . Under the proper conditions this could result in a lot of steam pressure building up and result in an explosion, or at least contribute to an ongoing chemical explosion.Certainly a similar steam explosion could occur from the decaying fuel rods after shutdown. There would not be any direct color from this steam explosion. If some pieces of fuel rod were pulverized, at a temperature of ~ 1200 degrees C they would probably be glowing ~ yellow. But they would not be part of the explosion unless some remarkable brief conditions were met that led to nuclear fission. I suspect this would be extremely difficult at uranium concentrations of less than 5 percent. If they were MOX fuel rods though, I have no idea how the plutonium would respond.
But, my point is that the yellow glow at the base of the explosion has many possible explanations without needing participation by the core or core steel container. Again, the radiation surge would have been huge and persistent if the core was disrupted and dispersed. I would be more suspicious that the spent fuel rod storage tank could have been disrupted than the 6 inch(?) thick stainless steel reactor vessel. If so, there should be spent fuel rods scattered around the floor of the containment building and once again the radiation readings would tell the story.

The differential decay ratios mentioned above are interesting, though I'm not sure how many scenarios could result in the ratios. I do wonder about the shutdown design of the reactor. If the fuel rods are reaching temperatures of ~ 1200 degrees C, then the aluminum alloy(?) control rods would possibly be melting and slumping to the base of the reactor. Would this allow the fixed fuel rods to start active (at least on a low but significant level) neutron driven fission? This seems an obvious design consideration, but surely it was addressed in the design!. Boron injection might mitigate this, but only if the solution covered the rods (or if the fuel rods also melted and pooled in the base of the reactor and mixed with the boron left behind as the solution evaporated.

Dan Tibbets


Dan,
I am not sure what you mean in the lead sentence. Criticality would imply a neutron induced self sustaining balanced power reaction. Not growing (supercritical) or declining (sub-critical).

ladajo
Posts: 5685
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Postby ladajo » Mon Mar 28, 2011 8:31 pm

Skipjack wrote:I dont think it can go up like a bomb. Remember, building nuclear bombs is hard. The iranians have been trying for years without success. The North Koreans have not had much either.


Wrong fuel type and wrong geometry. Power plants use slow fuels, hence the need for moderators. Weapons use fast fuel, and have dense geometry. Two different animals.

ladajo
Posts: 5685
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast

Postby ladajo » Mon Mar 28, 2011 8:37 pm

KitemanSA wrote:
D Tibbets wrote:Criticality would imply nuclear explosion- at least on a tiny scale- that is what is happening in a normal active nuclear reactor.
I think "criticality" in a powerplant merely means a sustained nuclear reaction while in an nuclear bomb it means a run-away nuclear reaction. Same basic reaction, different rates, by MANY orders of magnitude! I suspect that if the core COULD go bomb-type critical, they wouldn't have to worry about evacuating the nearest 20 km because the plant would have already evacuated that region for them. :?


A weapon is a fast neutron induced supercritical event in a fast fuel. The closest thing to it in a slow fuel plant is called "prompt criticality". Going prompt can induce a pressure transient explosion if there is a mechanical failure of the containment (vessel or components).
When a slow fuel core slags, and loses geometry, it can be setup for a prompt critical event. Reactor vessel designs are inclusive of prompt criticality events. The envisioned (and days of old tested event) was the ejection of control rods. When a core slags, it loses geometry controls, and thus can lose neutron damping and power up. In extreme cases you could go prompt. Loss of geometry is a BAD thing, it has no rules other than no control.


Return to “General”

Who is online

Users browsing this forum: No registered users and 5 guests