Possible reactor meltdown in Japan

[Al]

n the case of TMI the Fuel melted but did not breach the Reactor Vessel. Even if it would have, the fuel would have melted through the vessel and the Reactor building had already 9 feet of water.

The concrete in the area of the vessel was around 8 feet of concrete as I recall. It was poured on bedrock. The amount of heat absorption there was immense. And the Reactor building had reinforced walls of 3' thick concrete and could maintain an internal pressure of 56 psi. It had a steel liner 3/8" thick and could take a direct het by an airliner.

I don't know if the Japanese reactors have this kind of system and what the actual Reactor Building consists of.

As we speak the core is still producing 100 million Btu's/hour.

 

[demarpaint]

I heard the tail end of a news report that said when they constructed that plant they didn't construct it with a quake of the magnitude they just had in mind. That pretty much sums it all up.

 

[Cristobal]

No matter what, the quake made a terrible mess.

 

[hpichris]

Well, radiation levels have dropped. SO far so good. Told you I had faith.

 

[Bluestream]

I just saw a US expert on CNN, say that 5 nuke plants are having cooling system problems with cooling the core, and 2 have gone critical. This is a nuclear catastrophe in the making and the news will only get worse IMO.

 

[JHZR2]

Oh boy... Look for oil to go up on this, NG too... As that is how we will be making power for the foreseeable future...

 

[JHZR2]

Originally Posted By: Al


As we speak the core is still producing 100 million Btu's/hour.


Which core? One in Japan or TMI? Isn't TMI still functioning, with only a very small amount of steam or another fluid that released? Isn't TMI supposed to be making millions of BTU?

 

[mrsilv04]

Originally Posted By: demarpaint
While I'd like to believe that, and I pray for those people, do you really believe the Japanese gov't is telling the truth?


Although I'm not sure about the government, the Japanese business culture has a long-standing issue in dealing with the word "ooops"...

See: Toyota.

 

[Al]

Originally Posted By: hpichris
Well, radiation levels have dropped. SO far so good. Told you I had faith.

Thats bc the gaseous fission products made when the fuel failed were initially released and got dispersed. But this initial release doesn't last long. Same thing happened at TMI. Everyone was contaminated initially. I think it was Zenon-137. They obviously know at this time how much of the fuel failed. At least they should.

 

[MolaKule]

Quote:
At this point, events in Japan bear many similarities to the 1986 Chernobyl disaster. Reports indicate that up to 1.5 meters (4.9 feet) of the reactor fuel was exposed. The reactor fuel appears to have at least partially melted, and the subsequent explosion has shattered the walls and roof of the containment vessel — and likely the remaining useful parts of the control and coolant systems.


A totally ridiculous statement. There is NOT a meltdown. And Three Mile Island only had a partial MD beacuse of the backup flooding systems.

The nuclear reporting on the Japanese reactor situation has been irresponsible and stupidly PPoor.

Chernoble was a graphite pile or Graphite Moderated Reactor, was poorly designed and had few safety features and little cooling redundancy.

The explosion seen on TV was due to a hydrogen gas buildup in the outer building, not the core.

In most Boiling Water Reactors (BWR) there are total of three vessels surrounding the actual core.

The hydrogen gas resulted from the nuclear fuel rods and cladding and combined with the oxygen in the air to produce an explosion, which relieved pressure. I did see a blast wave and it was impressive.

One of the reactor's safety feature is that it drops control rods slowly reducing neutron activity and criticality. Another safety feature is the flooding of the reactor vessel and the containment building, depending on the design. They are now pumping in sea water to keep things cooled down.

If the earthquake caused a malfunction of the control system in the dropping of the moderator rods, then the core may not have been moderated to total shutdown.

A reactor core doesn't cool down instantaneously.

Boric acid can be pumped in to further moderate the core if necessary, depending on the design and support systems.

Xe-135 is formed by the dacay of I-135 and is often builds up after shutdown.

 

[Cause4Alarm]

Quote:

The explosion seen on TV was due to a hydrogen gas buildup in the outer building, not the core.



this would mean that the other two layers of containment would have to be breached for the gas to get to the outer containment building, and japan has admitted to partial meltdown....so don't go spouting off about people making ridiculous statements when you just made one yourself......and yes information is being handled poorly, not how the Japanese govmt is saying everything other than they have it under control

 

[Cause4Alarm]

also notice how the evacuation radius keeps getting bigger

 

[Bluestream]

Chernobyl info here: http://en.wikipedia.org/wiki/Chernobyl_disaster

Very differnet cause, but result may be the same. in Japan they are currently flooding the reactor with sea-water in a last vain attempt to cool it down. Army has been called to to take over

 

[MolaKule]

Not necessarily. The neutron radiation from the Uranium dioxide fuel rods could have interacted with the water in one of the containment areas to produce hydrogen gases. If the Zircalloy cladding for the fuel rods got very hot, they can interect with the water to produce some hydrogen gas.

The Cesium release reported, be it Cesium 134 or 137, is a normal Noble gas byproduct found in the circulating cooling water.

As more steam and gasses are released, the dispersion of radionucleotides will increase. Expanding the evacuation radius is a smart move.

 

[LS2JSTS]

Well it didn't take Greenpeace too long to seize the "opportunity" from this unfortunate event...


"How many more warnings do we need before we finally grasp that nuclear reactors are inherently hazardous? The nuclear industry always tells us that situation like this cannot happen with modern reactors, yet Japan is currently in the middle of a potentially devastating nuclear crisis,"

"Once again, we are reminded of the inherent risks of nuclear power, which will always be vulnerable to the potentially deadly combination of human error, design failure and natural disaster."
-Jan Beranek, Greenpeace

 

[Al]

Originally Posted By: MolaKule

The Cesium release reported, be it Cesium 134 or 137, is a normal Noble gas byproduct found in the circulating cooling water.

To get these radiation levels there would have to be failed fuel. That means to get the radionuclides into the air you have 3 failed barriers..fuel rods, Reactor Vessel, and Contaionment building.

Originally Posted By: MolaKule

In most Boiling Water Reactors (BWR) there are total of three vessels surrounding the actual core.

Are you sure you are not referring to PWR's which have 2 to 4 steam generators?

 

[Bluestream]

The Cesium release reported is very bad news:
http://www.cnn.com/2011/WORLD/asiapcf/03/12/japan.nuclear/index.html?hpt=T1&iref=BN1

Click play...

 

[MolaKule]

Yes, of course, life idealistically should be a zero risk situation.

And CNN and other outlets are consulting Robert Alvarez of the IPS about the JPN's. IPS is an anti-nuke environmentalist group.

Geez people, consult some nuclear engineers and physicists.

 

[Bluestream]

Originally Posted By: MolaKule
Geez people, consult some nuclear engineers and physicists.


Actually they have had several on already...

 

[Al]

Originally Posted By: MolaKule

Geez people, consult some nuclear engineers and physicists.

When you have Cesium 137, Iodine 129 its pretty clear what is happening. The Fission Products have left the barn. The high amount of initial radioactivity was probably these two which decay off pretty quickly.

The big challenge will be dealing with the long term decay heat. They need to be able to circulate the water through a heat exchanger. If they don't highly contaminated water will contaminate everything or the steam will continue to be a radioactive offgas. Chernoble didn't have that problem and TMI constructed two backup systems for long term cooling.

In the case of TMI..two steam generators and Reactor Coolant Pumps took care of decay heat. They need to have a core cooling system (other than sea water) soon or things will go bad quickly.