Japan nuclear crisis

myth_kill

the article at http://www.marketwatch.com/story/fed...-us-2011-03-13 says that the radiationw ont affect the US

but id ont think its correct as nuclear radiation can move aorund at fas rate to go to atleast he coastal areas of U.S


any opinions?

The Gentleman

If the current reports from the Japanese government are accurate then you should have nothing to worry about. The quoted amount of radiation that has been released and the type will not be of any harm to anyone in the US

Astronuc

If the core remains flooded, then most of the problem is contained within the containment or at the site.

Naty1

I don't think anyone really knows what the current situation is. Reports of "meltdown" as far I have so far seen are either hype or specultion.

Astronuc has posted some really good factual material ....in Nuclear Engineering

http://www.physicsforums.com/showthr...panese+nuclear

Give the Japanese authorities at least a week or two to figure out what has happened and then release real information....clearing a 13 mile radius is mostly likely precautionary not a positive indication of "disaster" and 10,000 years of contamination....But who knows what information, if any, is being suppressed.....

daumphys

From now on we have to change our nuclear power station design concept.
We have to design our power station based on safety first concept.
If the station has any trouble, the power station should go to no nuclear reaction state immediately.

Trouble -----------> No nuclear reaction state. very safe state
Only very safe state ----> electric power generation.

Current nuclear reactor problem is the nuclear reaction is always going on, and only cooling is
to control the all safety.
When there is some trouble, at any situation, we can cease nuclear reaction, if not the fission reaction increase the reactor temperature, and it makes big trouble.

vanesch

That is already the case.

No, the nuclear reactions were stopped immediately, and this is indeed the case for all "Western" power plants. It is a requirement.

What is the trouble there is the evaculation of REST HEAT. The decay heat of the burned fuel (which is of the 1% level or lower than the reactor power when "on") must be removed during the days and weeks AFTER the stop, and that's what was not going on. If you leave that for too long a time, you start fusing your fuel (that's the famous "meltdown").

So this heat is SLOWLY building up, and sooner or later you have to cool it. And release the build-up steam (and unfortunately, hydrogen). And as the environment has been destroyed there, their only option now is to pump seawater in the thing to cool it. That's what they are doing.

So the main problem is: even a stopped nuclear reactor (of ANY kind that is based on fission) needs SOME (not much) cooling in the hours, days, and weeks that follow.

joema

The *designs* have already been changed long ago. It is well understood how to make a passively-safe fission reactor. However you can't tear down 400 existing plants worldwide and replace them with passively safe designs.

On that point, can anyone comment how the various passively-safe designs would have fared in the Japan earthquake? Assume the same parameters: E.g, grid power down, diesel backup generators flooded, batteries eventually depleted.

A key parameter is time to restore power, which itself is dependent on design of reactor and support equipment. Say one week.

Also, if the passively-safe designs still have actively-cooled on-site spent fuel pools, what's the solution for that?

daumphys

There are many reasons to do this. But, is the reactor temperature too high at the safety point? At any situation, the fuel do not have to be fused. We have to think safety first, economy is next. My thought, many engineers might think about this problem seriously.
But more perfect safety design is required.

Drakkith

I almost can't understand what you are saying here, but I think I get it.

Safety is already a primary concern. It took THE LARGEST EARTHQUAKE EVER RECORDED FOR JAPAN for this to happen. I'd say thats a pretty good safety record. As soon as an earthquake was detected, every core went into shutdown successfully. When they lost commercial power for the coolant pumps, the backup generators kicked on successfully. When the backup generators were flooded due to a Tsunamai that got past their sea wall, backup battery power kicked in. EVERY part of the emergency action plan worked as intended. Would you blame the power plant if the earthquake had swallowed the entire reactor building and say that we should have had a plan to tunnel down to it to make sure the core was still being cooled?

That plant had been operational for FORTY YEARS. Forty years and no major problems. I'd most definately say this is due to a focus on safety and reliability.

daumphys

This is my idea, but it is required some money. How about installing liquid nitrogen plant near nuclear power plant? Liquid nitrogen is very efficient coolant and has no pollution problem.
At the emergency situation we can use it as a coolant.

Drakkith

They already have coolant. They are having trouble because of the loss of ALL electricity to power the coolant pumps. The earthquake destroyed the grid connections to the plant, then the tsunamai swamped their backup generators, then the backup batteries ran out of power, and once they got portable generators and batteries on site they had trouble connecting them because everything was flooded. Doesn't matter what coolant you have if you cant circulate it. The coolant that was inside the core when the pumps stopped heated up and evaporated, building up pressure and lowering the amount of coolant, eventually causing some of the fuel to be exposed to air inside the core. The exposed portions of the fuel have NO coolant on them, which is a bad thing.

Along with the loss of power, once the pressure starts to rise in the core it become harder and harder to pump fresh coolant in because you are working against the pressure.

Suffice it to say, they design everything, including the fuel itself, to avoid any kind of catastrophe as best as they can. You CANNOT plan for every occurrence however.

vanesch

You have any idea what happens when a tsunami floods a liquid-nitrogen plant with huge stocks ?

daumphys

Always thermal hazard makes big problem on the nuclear reactor operation, liquid nitrogen is fast and no pollution method. I think the liquid nitrogen storage tank is always protected as the same level of nuclear reactor.

Borek

I love it when people have ready solutions for things that were analyzed in details for many years by others.

QuantumPion

My idea was to simply install a fuel cell inside containment, with the fuel source well protected underground. That way no matter what happens to the plant, as long as the containment is still intact they would have enough electrical power to run the emergency cooling systems. One of my colleague's idea was to just stick a generator on the terry turbine, even easier to do.

Drakkith

Apparently you don't understand or havn't read anything anyone has posted here. This thread should be locked, as it isn't going anywhere and has gotten off topic.

Emreth

Back to the original topic, anybody have ideas on how the radioactive material would spread, possible to US, in the worst case scenario?