Could an Earthquake Rip Open a Nuclear Powerplant?

[Nebula815]

This is just a question that has been bugging me for awhile, but, in a worst-case scenario, if you say had an earthquake where the ground split open, and a nuclear plant was right over the split, could the reactor literally be "ripped open" in such an instance? And if so, would this cause the radiation to be released?

Or is this just a scenario for Hollywood movies?

 

[QuantumPion]

I believe "The Earth swallowing an entire power plant whole" would fall beyond what is considered a design basis accident.

 

[Astronuc]

And earthquake that large would be catastrophic.

Likely the Earth would slump (due to strong shear) and the plant could remain intact. It is beyond design basis.

That's why nuclear plants are built away from known fault zones. Part of planning for the plant is a detailed site evaluation and characterization.

 

[gmax137]

This is just a question that has been bugging me for awhile, but, in a worst-case scenario, if you say had an earthquake where the ground split open, and a nuclear plant was right over the split, could the reactor literally be "ripped open" in such an instance? And if so, would this cause the radiation to be released?

Or is this just a scenario for Hollywood movies?

What happens in an earthquake is that the ground shakes - up & down and back & forth. It doesn't really 'split open.' The splitting open is what Hollywood likes to show because it's a lot more dramatic. Nuclear plants are designed to take the shaking. Each plant has a maximum amount of shaking that has to be designed for. It is generally twice the shaking that you might expect based on previous earthquakes in the area of the plant. And for that 'expected' level of shaking (ie, the half value) the plant doesn't just survive, it is designed to operate right through the quake.

 

[Nebula815]

Thanks for the answers people. However, Astronuc, when you say the Earth would "slump," what do you mean exactly? You mean its axis of rotation would change?

 

[Astronuc]

Thanks for the answers people. However, Astronuc, when you say the Earth would "slump," what do you mean exactly? You mean its axis of rotation would change?

NPP containments are massive structures of reinforce concrete. If the Earth opened as in the case of a fault, I would expect the shear forces at the periphery of the containment structure to cause the ground supporting the containment to shear and give way.

You were asking if the Earth opened up (as would be the case in fault). To open the contaiment up, the shear force on the containment would have to be significant, and the ground supporting the containment would have to remain rigid. I would suspect the ground would yield.

Such event would be extraordinary. But its rather moot given the siting requirements of NPPs.

I'm nevertheless curious, and I will ask some seismic experts what they think about the matter. I'm sure their first reaction would be that no one would probably bother to analyze that, because no one would build a plant where that would be a risk. But maybe they have analyzed that case in order to test the code and methodology.

 

[mheslep]

...But its rather moot given the siting requirements of NPPs.

I thought http://maps.google.com/maps?hl=en&s...=A&ved=0CA4QpQY&sa=X&ei=y4MZS8uYFIq-M6y4pI8B" was very close to, if not on, a fault. I recall seeing some video featuring one of the site designers discussing extraordinary lengths taken to isolate the site from quake shocks.

 

[Astronuc]

I thought http://maps.google.com/maps?hl=en&s...=A&ved=0CA4QpQY&sa=X&ei=y4MZS8uYFIq-M6y4pI8B" was very close, if not on, to a fault. I recall seeing some video featuring one of the site designers discussing extraordinary lengths taken to isolate the site from quake shocks.

http://earthquake.usgs.gov/earthquakes/recenteqsus/Maps/US2/34.36.-122.-120.php

There are two faults north and south of the plant. In the image, the plant is just below the 'a' in San in San Luis Obispo.

 

[chayced]

I think the point here has been lost.

Could an Earthquake Rip Open a Nuclear Powerplant?
Yes

Would anyone care about the powerplant if an earthquake that large had happened?
No

It also hinges around the what you mean by "Rip Open".

If you mean rip open as in containment broken and fuel laying on the ground, then yes a large enough earthquake could do this. But on that same note a large enough earthquake could topple Everest. A more likely scenario is an earthquake causing a large enough disruption of systems that the core melts down or the spent fuel does. Still it would take enough of an earthquake on a western powerplant that the lives lost from the contamination would be miniscule compared to the earthquake itself. Look at the deathtoll from Cherynoble then compare it to a major earthquake.

 

[Hologram0110]

Personally, I would be surprised if it were possible for an Earth quake to 'rip open a nuclear reactor'. I say this because I would expect that the reactor core, and containment around the core to be strong enough that while it might be damaged and otherwise deformed I don't think it would never tear open or shear open. Typically, reactors are built with extremely thick outer shells of nearly solid metal.

An Earth quake that large would certainly destroy the core, and perhaps cause a meltdown if all cooling systems were destroyed. A more likely source of radioactive contamination from an Earth quake that large would be from the spent fuel ponds.

 

[Thermodave]

An Earth quake that large would certainly destroy the core, and perhaps cause a meltdown if all cooling systems were destroyed. A more likely source of radioactive contamination from an Earth quake that large would be from the spent fuel ponds.

If an event of this scale happened I would suspect that radiation might be the least of our concerns since the quake would likely kill everyone. Like others have said, the core wouldn't shear in half. The real risk in a PWR I suspect would be a loss of primary fluid combined with some human error that could cause melt, but even then the risk of exposure to anyone outside of the plant is pretty small.

Personally, I think there are better odds on an employee being exposed to gamma radiation and turning into the Hulk and then tearing the core in half. Earthquakes are accounted for in design. The Incredible Hulk is not, no?

 

[aquitaine]

During the great SiChuan earthquake in China last year, wasn't there some radiation leaks?

 

[mheslep]

During the great SiChuan earthquake in China last year, wasn't there some radiation leaks?

Google shows no reliable reports of radiation, but if there was any it would be from a military program, not a commercial reactor.

Military nuclear research and bomb making facilities based in the city of Mianyang were in the earthquake zone. Officials from both the Ministry of Environmental Protection and the army have said there was no leakage of radioactive materials from the site.

http://www.rsc.org/chemistryworld/News/2008/June/18060801.asp

 

[Homer Simpson]

Would anyone care about the powerplant if an earthquake that large had happened?
No

This is not true... nuclear plants are, rightfully so, held to a much higher standard than other industries.

An earthquake could topple down a 100 story hospital full of women and babies right onto a collection of schools and the reaction would be less, and not nearly as long lasting, with not nearly as much impact on peoples perceptions than if it caused a release with no injury from a nearby nuke plant.

Look at TMI, no death, no significant dose to public, but huge story, and everyone cared.

 

[gmax137]

I still think the notion that an earthquake could rip the primary piping apart is false. The relatively small size of the NSSS means you won't see forces shearing the piping; rather, the whole thing shakes. The design ensures that the natural frequency is too high to get a lot of differential motion (eg, reactor vessel going east-west while the SG's are heading west-east).

In an event much stronger than the design basis, I suppose you could see the branch lines ripping off, or maybe the steam lines tearing off the top of the SG's. As someone says above, the possible consequence is core damage, but you don't see the NSSS itself split apart.