Wednesday, May 21, 2008

Site evaluation - 4

Hey, I'm not getting any indication that this is interesting for anybody! Anyway it's interesting for me, so I'll soldier on for a little while longer, even though I think it ends in a vale of tears when I get to Canada.

The neat thing about this US site was that I thought the original document was ripped to shreds by the USNRC, and then I saw the next day they got their permit. Obviously, I was wrong! I expect the same thing to happen in Canada.

The other great thing was that they did absolutely no new work for this, they just rehashed the 30 year old stuff (ok, maybe they had a little tour for sand blows). The thick books were all compiled by the big US consultants, who doing the same for OPG. They are real pros at this!

Ok, everything hinges on the grand old ideas of the 70's that a nuclear plant is actually threatened by an M7 earthquake a couple of hundred kilometres away. This is shown by their graph, which breaks down main contributor to seismic hazard by magnitude and distance.

Note that for the lower frequencies (the most damaging energy), it's all M7's in the New Madrid Zone.

How can this be? Wouldn't you think the recent Japanese Nuclear Earthquake would give pause for thought? How about this recent spate of 'super-shear' or what I call 'super-quakes'? Surely somebody would think that the science has changed in the last 30 years? But, alas, the answer is no.

That's because the old engineers still think a nuclear plant can be damaged by a long rumbler set some distance away. They come to that conclusion by using shake table testing, and very old computer analysis that puts in a lot of amplification for piping systems. Even though it is known that the big pipes and forged nuclear vessels can never be damaged by an earthquake. Again, look at Japan!

And so, they are locating this nuclear plant in a very interesting area. It is right on the outer fringe of the New Madrid seismic zone, right where there have been a lot of big earthquakes recently (and more can be expected!).

Now, I personally think this site is one of the most challenging for the new breed of reactor designs. I mean, how close can you get to New Madrid an still live? They include a nice map of the big ugly zone.

This is a great map! So, in the end, they come up with a uniform hazard response spectrum at median 10-5, blah, blah. What they don't mention is the huge multiples between 10-4, 10-5, and 10-6, for this area. Personally, I think there is a good chance of being directly hit by a super quake, at these low probabilities. Really, this is one of the most active zones in all of ENA!

So, they got away with this, rah rah. Next, we'll look at Ontario, and the very vague requirements here. Or maybe I won't! This is probably getting too close for comfort, and my anxiety attacks!

1 comment:

disasterman said...

Well, I find the series interesting! Please keep 'em coming.