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Effects of an earthquake on a nuclear reactor?

Former Member

Hi,

 

After the earthquake in Japan, and the tsunami and subsequent nuclear incident, I was thinking - what would the effects of an earthquake be on a nuclear reactor? Is it more likely that the neutrons might escape the control rods? Or is there something else? I mean, it seems to me as though the problems with the cooling system were to do with its power supply being cut - after the earthquake, the reactors were automatically shut down and the tsunami swamped the diesel generators. I'm sure there was good reason for shutting down the reactors, its just that I can't think what it is...

 

 

Anyway, I hope I don't come across as ignorant or anything - I don't mean to be!

 

Thanks,

 

Dom.

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  • Hi Dom,

    You questions are very pertinent.  The Japanese reactors use boiling water to make steam that powers the generators.  When running, each reactor generates Mega Watts of energy and need a constant flow of cooling water to keep the reactor pile from overheating.  During the earthquake, the power lines went down and the reactor had to be shunted into a dummy load while they slowly lowered the control rods to slow the fission reaction.  Unfortunately, the Tsunami destroyed the cooling system that provided the pile with fresh water.  As a result, the reactor rods overheated.  They are using sea water to cool the pile, but that generates a lot of steam and where the water reacts with metal in the reactor, a lot of hydrogen gas.

    Think of the reactor like a big ship.  It takes a while to get the mass moving at a given speed.  It also takes a long time to slow the ship down.  Thats the problem with the Japanese reactors, you just don't turn them on and off like a light switch.  So they now have to manually cool down the reactors to the point where the pile can be neutralized.  This process normally takes several days when everything is working correctly.  Who know how long it will take with most of the safety devices damaged.  With luck, they can get all of the reactors down to a normal temperature in the next couple of days.  If not, then we all have to hope that the inner container shell holds.  If the container is breached, then you will get a very hot plume of air rising out of the reactor, which could carry some very nasty elements into the atmosphere.

    I have two Japanese exchange daughters in Japan.  So far they claim everything is ok with them, but one has a lot of family members up in Sendai.  So we should all do everything we can to help, but we also need to follow the Japanese example and not panic.

    I hope my rambling has helped you understand the issue and concerns.

    Thanks

    DAB

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  • Hi Dom,

    You questions are very pertinent.  The Japanese reactors use boiling water to make steam that powers the generators.  When running, each reactor generates Mega Watts of energy and need a constant flow of cooling water to keep the reactor pile from overheating.  During the earthquake, the power lines went down and the reactor had to be shunted into a dummy load while they slowly lowered the control rods to slow the fission reaction.  Unfortunately, the Tsunami destroyed the cooling system that provided the pile with fresh water.  As a result, the reactor rods overheated.  They are using sea water to cool the pile, but that generates a lot of steam and where the water reacts with metal in the reactor, a lot of hydrogen gas.

    Think of the reactor like a big ship.  It takes a while to get the mass moving at a given speed.  It also takes a long time to slow the ship down.  Thats the problem with the Japanese reactors, you just don't turn them on and off like a light switch.  So they now have to manually cool down the reactors to the point where the pile can be neutralized.  This process normally takes several days when everything is working correctly.  Who know how long it will take with most of the safety devices damaged.  With luck, they can get all of the reactors down to a normal temperature in the next couple of days.  If not, then we all have to hope that the inner container shell holds.  If the container is breached, then you will get a very hot plume of air rising out of the reactor, which could carry some very nasty elements into the atmosphere.

    I have two Japanese exchange daughters in Japan.  So far they claim everything is ok with them, but one has a lot of family members up in Sendai.  So we should all do everything we can to help, but we also need to follow the Japanese example and not panic.

    I hope my rambling has helped you understand the issue and concerns.

    Thanks

    DAB

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