State of the Union is CNN’s Sunday morning discussion show. Candy Crowley is the interviewer. I’ve paired question and answer to make it easier to follow. (Transcript cleaned up just a bit to cover pauses.)
Crowley: As of right now, the status of the three troublesome reactors in Japan?
Chu: Certainly. Of the three reactors, one, two, and three, two of them we believe are intact, the main containment vessel.
Crowley: So no danger of meltdown in two of them?
Chu: that's true.
Chu: Well, I should be more precise. There’s a containment vessel. I think there is suspicion of damaged fuel rods in the reactors themselves. But the issue here now is whether the containment vessels are intact. The main containment vessels in two of them we believe are intact. We don't know the status of the third one.
Crowley: Okay. So inside two of them, you might have some damaged fuel rods. But the containment is secure?
Chu: That's what we believe at the moment. Correct.
Crowley: And the third one, I’m assuming is what they call number three?
Crowley: The one that you're still worried about?
Chu: No, number two is the one we're worried about.
Crowley: Number two, right. What are you worried about there?
Chu: Because of the higher levels of radiation, we take that as evidence that there might be a breech in that containment vessel. But they're not extraordinarily high. So it appears if there is a breech, it is a limited breech. Again, we don't really know.
Crowley: Is the worst over?
Chu: We believe so. I don't want to make a blanket statement. What you do in events like this is, as you go and get more information and as you bring back power online and do all those other things, that means you're mitigating and ensuring things are taken off the table and that's the process which the Japanese government and the people at Tepco are doing.
Crowley: We know that they need the power to try to cool the reactors and the core. Is power now linked up in at least one of those?
Chu: Very quickly after both the access to grid power was taken off line due to the earthquake and tsunami and the local power taken off line, emergency diesel generators were in place. And so what you're talking about is the mainline power from the place. And power has been restored and they're beginning to start to hook up the main equipment, the pumps and things of that nature.
Crowley: Do you feel comfortable now with the honesty and the knowledge that you are getting from Japanese authorities on what's going on at these plants?
Chu: Well, there's no evidence that I’ve ever heard that the Japanese were holding back. I mean, they're giving their people and us reports of what's going on. It’s sometime hard to tell because a lot of time the sensors are out. Remember, this is a place where there's no power. So we are getting information from them. We have confidence in that information. And we've actually loaned them and are working with them on other monitoring equipment.
Crowley: Then what accounts for the difference of assessments that the U.S. had early on about how serious the problem was and [what] the japanese had? Do you think they were hiding something? Did they not know? Did you know something they didn't know?
Chu: No.What we do is we have our own set of standards and safety and we thought we would err, the united states would err on the side of prudence and caution. and you're probably speaking about the different zones where you would have to evacuate. and that was just done out of abundance of caution.
Crowley: And U.S. officials seemed more alarmed at the time than japanese officials did.
Chu: Well, I don't know about that. Now you're beginning to read body language and things of that nature. I think both the Japanese officials and the united states officials are taking this very seriously. They’re working as best and as fast as they can to determine the situation. And most important to mitigate further risks.
Crowley: Disasters tend to happen when things you don't expect come along. The Japanese didn't expect an earthquake over 7.0. They didn't have reactors that could withstand that. They didn't expect a huge earthquake, 9.0 followed by a tsunami. What is it that the U.S. is not expecting? Could our reactors on the west coast withstand a 9.0 right now followed by a tsunami? [editorial note: See post “Quick Hits – The NRC, NYT and NRC Again” below. The NRC explains that no American nuclear energy plant can be struck by a tsunami.]
Chu: If a reactor is located in the vicinity of site -- it's forbidden to put a reactor on an earthquake fault, but if they're located in the vicinity of the site, then there is an estimate of what the largest ground motion would be at that site. And then you design above that ground motion criteria. The ground motion criteria we use is something where the probability is so low we're looking for a potential quake that would occur once every 7,000 to 10,000 years. And so you're allowing a huge span of time to allow for significant ground motion.
Crowley: What are they built for on the coast?
Chu: Again, it depends on the site of the reactor. Let me give you an example. Sometimes people translate this to scale of the Richter scale. But it's really an acceleration at the site. And, for example, it could be something like the canyon, I believe is something like two-thirds of the acceleration, vertical acceleration due to gravity. In lay person's language, that might translate into something like 6.2 [on the] Richter scale. But it's really at the site, the ground motion or what the geologists know.
Crowley: So anything above 6.2, let's say, in layman's terms, you might not be able to withstand on the coast?
Chu: Oh, no. That is the estimated, the maximum size of the ground shaking. Then you go well above that. So maybe 7.5.
Crowley: Okay. So a 9, as it was troublesome for Japan, would be troublesome for us?
Chu: Yes, except a 9 does not come from the type of faults around that reactor site. That is the other thing you have to consider. The very large earthquakes that Japan saw are what are known as subduction zone earthquakes where one piece of ground goes under another. And the -- other faults, slip faults like that, you simply don't get 9s in those.