Posted on 03/14/2011 6:39:05 AM PDT by Lil Flower
TOKYO, March 14 (Reuters) - Nuclear fuel rods at a quake-stricken Japanese nuclear reactor are now fully exposed, Jiji news agency said, quoting the plant's operator, Tokyo Eletcric Power Co .
(Excerpt) Read more at mobile.reuters.com ...
Meaning what methods. If there aren't enough working pumps to get the seawater to the reactors...what other than water can cool these?
I think even a partial meltdown means they’ll be pumping water in there for a long time. I.e, if the rods deformed conventional cooling is out of the question as sustained higher temps are likely from the deformed mass of fuel providing greater density of reactive material. Deformed rods will likely stay unusually hot for a long time until they’ve spent themselves. So they’ll be pumping sea water in for quite some time I think.
One other concern I have is for cracked reactor vessels. I’ve heard some reactors were scheduled to be shut down soon due to end of service life. Reactor vessels purportedly become brittle towards the end of their life. If the earthquake cracked the reactor vessel that might explain the initial loss of coolant and inability to maintain adequate water levels.
Well...I have been on this earth during during WW2, multiple above ground nuclear bomb tests, the Chernobyl disaster and so far so good..
I do worry about those working on the problems and those near the plants in Japan..
From what I have heard so far ..the containment structures are intact..the vapor is what is emitting radiation
I am dismayed by the panic of people so far from what is going on..
Pray for those trying to get the pumps working to cover the rods.
I do pray food water and shelter for those affected by the earthquake and tsnunami.
May God help those poor people of Japan.
God help the rescuers and the engineers.
It means there's nothing to stop the heat from generating. Eventually the rods will get so hot they'll melt everything - including the bottom floor of the tank, then the ground under, then when it hits water they'll be an explosion - steam radioactive material etc... If these are the rods with plutonium in them we could have problems for years - maybe thousands of years...
Then again, the worst case scenarios almost never happen... and probably won't happen here either.
“Japanese officials say the nuclear fuel rods appear to be melting inside all three of the most troubled nuclear rreactors - AP”
Yes. This is consistent with what I just said. Melting of the rods is not a “meltdown” in the China Syndrome sense. The principal protection against major environmental damage is the concrete containment vessel. It is designed to completely contain a full melting of the rods. I hope GE designed the concrete vessel well. If they did, then the Japanese have a huge and expensive local cleanup problem but nothing more. I think the bigger danger is quake damage to the concrete vessel. If it is breached, then everything changes. So far, there’s no evidence of a breach of the concrete vessel.
Your link was excellant in discribing what has happened, is happening, and worst that could happen. Thank you.
My concern though is when it melts into that chamber is it strong enough to keep it there? That does seem to be the concern. Would the earthquake have affected it’s ability to do that?
Radioactive contamination found on 17 U.S. Navy crewmembers in Japan
OK so lets say that after all melts the vessel holding this is compromised...and it cannot be contained as hoped. Having used Boric and other elements to stop the process...wouldn't there be little actual radiation left to damage as extensively as some indicate?
Here’s the background on nuclear power plants: Nuclear power plants are composed of a fuel assembly, a containment vessel, a cooling assembly and a power assembly.
The fuel assembly is contained within the containment vessel. The fuel is “nuclear” (Uranium, plutonium) This fuel is shaped into pellets (cylindrical shape) that are encased in metal, forming “rods”. The rods are assembled and placed in proximity to each other to create heat. There is a coolant mechanism within the containment vessel that is connected to a heat exchanger outside the containment vessel. The heat exchanger absorbs some (most) of the heat from the inside coolant mechanism. The heat exchanger then uses the superheated fluid to make steam that turns steam turbines that make electricity.
The containment vessel, a very thick “kettle” keeps the nuclear material and radiation from escaping to the outside. The whole system is dependent on each of the components working. The earthquake and tsunami damaged the mechanisms outside the containment vessel. The “outside” mechanism failed to keep the “inside” mechanism cool. The inside coolant overheated and had to be vented from its piping into the containment vessel. This created high pressure inside the containment vessel. The operators then had to vent off some of the pressure to the outside air. The venting allowed hydrogen gas to contact outside air and water. There were explosions when the hydrogen and oxygen in the air ignited. This blew apart the building that housed the containment vessel. These were the explosions that were on the news.
Due to the fact that the outside pumps were damaged or there was no power, the cooling system failed. The “evaporation” of the cooling fluid inside the containment vessel dropped the level of coolant below the tops of the fuel rods, causing the rods to overheat. This melted the metal casing of some of the fuel rods and the uranium. This is a partial melt down. The containment vessel has not (yet) been breached. –and may not be breached.
There is, however, the possibility that this might happen. If that happens, radioactive fuel (uranium) would be released to the outside (it first would melt into a molten blob of metal at the bottom of the containment vessel. The metal would eventually melt through the bottom and be released to burn its way into the ground. If it did this, it would be a matter of time until it hit ground water. The ground water would then be made into radioactive steam that would shoot explosively into the atmosphere. The steam cloud would then drift with the wind –probably towards North America.
Right now, the operators are pumping sea water and boron into the pool of water in the containment vessel in an effort to keep the reactor from melting any further. By pumping sea water in, they are forced to allow some steam of gasses (hydrogen) to be released into the atmosphere. (Picture a pressure cooker on your stove. The pressure cooker can hold some pressure but not all the pressure that can be generated. It’s a very bad situation but they are doing everything they can to prevent a meltdown. Unfortunately, there a bunch of reactors with varying levels of the problem.
Hope this helps.
Furthermore, the nuclear reaction w/in the MOX fuel has been poisoned by the affect of the moderating rods being fully inserted into the nuclear pile. That means that any more heat is not being generated within the nuclear pile.
That being said: the mass of U235, and zirconium fuel rods, and reaction moderating rods is immense. The residual heat contained therein is enormous and must be exhanged into heat-sink. That'll take time within the enclosed system as its been designed.
The problem is that if the temp of the core remains above some critical value for too long, the zirconium fuel rods holding the MOX pellets, catalyze water by dissociating it into its hydrogen and oxygen components. The catalyst then reacts chemically with the molecular oxygen (O2) to form zirconium oxide; the MOX pellet holders essentially are transformed to dust. This could allow raw MOX pellets to re-initiate criticality of some degree (nuclear exothermic reaction) as they deform configuration and get too close to their neighbors. That would be really really bad.
IF they have to refill the primary reactor loop again, there will be some release of radiation. Depending on how they're venting the primary loop pressure - most likely through radiation scrubbers - they don't have the enjoyment of the secondary scrubbers that were undoubtedly in place in the secondary containment building; its been Ba_BOOMED; subsequent primary coolant venting will be released immediately into the general environment.
My guess would be subsequent primary coolant loop pressure purge and / or coolant re-filling will result in some increased radiation ccntamination of the environment. However, it won't be doomsday either (primary coolant loop radiation scrubbers are still in place).
Now, if the primary pressure vessel containment is compromised: all bets are off. But if that's true: then the radiation Ah-OOOOOOH-Gah horns be sounding off to grimace proportion. But I have no confidence in that unless the engineers misplaced a two, or put the decimal place one spot to the left or right of where it should've been due to too much saki the day they designed the reactor.
BTW, if that be true: we'll be seeing news reports of several hundred (if not thousands) of hari-kari's happening all over the next few weeks by nuke plant engineers.
“OK so lets say that after all melts the vessel holding this is compromised...and it cannot be contained as hoped. Having used Boric and other elements to stop the process...wouldn’t there be little actual radiation left to damage as extensively as some indicate?”
As I understand it, Boric acid reduces the danger of the nuclear material reaching critical mass. That is, of nuclear explosion. But that has never been much of an issue here anyway. The worst case is if the concrete containment is breached after a meltdown, a lot of somewhat enriched Uranium Oxide would enter the environment in large concentrations. I don’t think boric acid changes that. And that would be a bad thing.
But to date, this looks nothing like Chernobyl, where a crappy communist containment vessel burst. From Wikipedia: “According to a report released by the Chernobyl Forum ... the disaster killed twenty-eight persons due to acute radiation syndrome,[4] could possibly result in up to four thousand fatal cancers at an unknown time in the future[5] and required the permanent evacuation of an exclusion zone around the reactor. The Chernobyl plant had containment buildings not constructed to a correct standard, allowing the concrete containment cap on the reactor to be ejected in the explosion.” http://en.wikipedia.org/wiki/Nuclear_meltdown
To date, the Japanese situation looks more like three mile island, where the melted core was completely contained inside the containment vessel. A disaster for the company that loses the reactor and has to clean it up. But not a great public disaster.
It is, however, a huge !wooppee!! party for the American media, who would like to force America to rationing and solar energy. Nuclear power is a big threat to that goal. The disinformation you are seeing and the scary story stuff is designed to that end. Most reporters don’t seem to understand the difference between a core meltdown (three mile island) and a breach of the containment vessel (chernobyl). Or they want to deliberately conflate the issues to the public.
The interesting thing is the laser focus of the media on a situation that at worst will kill far fewer people than the earthquake and tsunami (using the Chernobyl numbers as a guide). The natural forces in Japan have already caused a far bigger disaster than the nukes can possible cause.
Wonder if that high-power pumping capacity could not be harnessed somehow for this job...
We have too many Chicken Little's running around screaming, "the sky is falling, the sky is falling"
Yes, there is going to be a big mess to clean up once the engineers get these reactors stabilized, but there won't be a large radiation danger to anyone except for the engineers and technicians doing the actual clean up.
http://http://energyfromthorium.com/ has a post that describes exactly why we are seeing certain radioactive elements detected and what each element is telling us.
If we pay attention, we are going to learn several important safety rules and procedures we can use to improve the safety of the nuclear reactors across the world. Just remember these reactors are 40 years old, and there are 3 newer and safer generations of reactors that have already solved several of the problems that have occurred
Even with so much being neuetralized? But yes, I understand that is the concern now..that it can be contained..unfortunately nobody will know until it happens.
Chernoybal was coal fed and exploded ,I understand , which caused the release of radiation. Japans are not coal fed. More like 3 mile IS...which did have a partial melt down...but contained.
I understand 5 years til they could examine to see how far it had gone...most were shell shocked with the discovery how had it actually was.
Chernoybal was coal fed and exploded ,I understand , which caused the release of radiation. Japans are not coal fed. More like 3 mile IS...which did have a partial melt down...but contained.
I understand 5 years til they could examine to see how far it had gone...most were shell shocked with the discovery how bad it actually was.
Yes...was my concern as they cannot assess the damage to these from the quake. Time will tell but hopefully we won’t have to know if they can or not contain. Very serious no matter how it plays out..but amazing these reactors and crew there have gone as far as they have with all considered.
Last I heard pumps wer down pretty much...so water was not getting to where it needs to be and why partial melting. Imagine trying to keep three reactors stable! Mind-boggling. No doubt great courage in the face of huge fears for these workers. Amazing stamina!
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