March 29, 2011
15th Interview with My Dad, a Nuclear Engineer, about the Fukushima Daiichi Nuclear Power Plant Disaster in Japan
|Picture of a Boiling Water Reactor Nuclear Power Plant like the Fukushima Plants. My dad refers to this image in his interview.|
EVELYN: Good evening dad
MARK: Good evening.
EVELYN: Are you ready for our interview?
MARK: I am
EVELYN: Alright, let’s get started. My name is Evelyn Mervine, and this is going to be an interview with my dad, Mark Mervine, who is a nuclear engineer. This is the 15th in a series of interviews that we have been doing about the Fukushima Nuclear power plant disaster in Japan. Today is the 29th of March, and it is currently 9pm EDT. In today’s interview it is going to be the usual format: my dad is going to give an update—and there has been some more news about Fukushima in the last 24 hours since our last update; and then I’m going to ask him a couple of questions. With that, dad, why don’t you go ahead and get started.
MARK: Ok, actually I spent a fair amount of time today taking a look at the news from various different websites and there actually isn’t a great deal of news. I’ll editorialize in a minute. What we do know from today—and I’ll just briefly kind of give an update for those that haven’t been able to listen to the last couple of interviews. There are six reactors at this site, of which numbers one through four have been the ones of the most concern. Five and six were the least impacted, and they were able to get electricity restored to five and six sooner than the others. Both of those plants are in a cooled down, safe shut down condition. As a reminder there are seven spent fuel pools—on at each reactor and then a common one. As we’ve reported they’ve also been able to restore electricity and cooling to the common spent fuel pool.
That brings us to reactors one through four. The progress has been slow at these reactors. To our knowledge they have electricity back to the control room for lighting, and they’ve been working on trying to restore instrumentation to some of these units, but it’s not been reported that they’ve had any success restoring any of the cooling systems to any of these reactors. The biggest news we’ve had in the past few days is that they’ve shifted from pumping seawater into reactors one, two, and three to pumping freshwater into those reactors. The other news in the past 24 hours is they’ve also shifting to using fresh water for the spent fuel pools. For reactors two and three they are now pumping fresh water into those spent fuel pools. For reactor two they are using a temporary motor driven pump, and reactor three they are using a truck with a pump to pump that water in; and they are making plans to be able to pump fresh water into the spent fuel pool at reactor four in the next few hours. So that’s the update, technically, from the plant.
Now a little bit of editorilization here. We’re two–and-a-half weeks into this, and although it’s very much a very serious situation and we don’t want to take anything away from the efforts that a lot of people are making: risking their lives, making these efforts, working under extreme conditions to try to minimize the situation and prevent it from getting any worse. What I think is surprising now at the two-and-a-half week point is ‘where is the information on exactly what is going on?’ TEPCO has a lot of nuclear engineers, they run many, many nuclear power plants. They can certainly free some people up to do a better job of providing information and briefing the public. It really is almost impossible to get any kind of detail. In the first week when events were happening every day, and the situation was getting worse, I think you could understand that. But at this point, two-and-a-half weeks in, there should be complete and comprehensive briefings given every day as to the status of these plants. If you look at their press releases from today they’re incomprehensible…garbage, essentially.
EVELYN: Well, and we’ve talked about in the last couple days that organizations like the IAEA and the NEI have tried to step up their reporting efforts, but if they’re…
MARK: And they have, but…
EVELYN: …not able to get information from TEPCO, how can they step up their reporting efforts?
MARK: And they have, but at this point in the game, with as many resources as they have, it shouldn’t be that hard to put together a team of two or three engineers that can take the information from the plant and put together a comprehensive briefing on exactly what’s happening. I’m just really kind of surprised at this point. I…when we started doing these I had no idea there would be any value in us continuing as far as we have, because you would have figured by now—first off that they would have made a little more progress than they have, but second off that they should be able to provide fairly transparent information themselves at this point. It just doesn’t seem like it would be that hard to
me. With that being said I’ll step back now. It is very frustrating, and I know that people are kind of
counting on us to get information—and it’s very hard. I spent a lot of time today trying to get more
comprehensive information, and it just isn’t out there.
EVELYN: We both have full time jobs as we’ve said before, and my dad does a lot of time researching this. We do the best we can, but our reports are not going to be perfect. Part of that is because it is just so difficult to get information in one place that is easy to understand. If my dad, who is a nuclear engineer, has so much trouble, it must be extremely frustrating for the general public, as we’ve said before. It hasn’t, I guess, improved to the point where we feel we can stop doing these interviews.
MARK: For instance—how about a statement on just how much progress they are making on restoring electrical power. I mean, if the news isn’t good—give us the bad news. Give us some expectation as to when they’re going to be able to get cooling systems restored in some of these units. There is just no news…umm, it’s surprising—and shocking—to be honest with you.
EVELYN: Ok, do you have anything else with the update before I ask a couple of questions?
MARK: No, and I wish I could give a more comprehensive update. But…again, what we know is they are injecting fresh water into units one, two, and three, and they are now getting some fresh water to some of the spent fuel cooling pools. Other than that the status doesn’t appear to have changed a lot in the last 48 hours.
EVELYN: All right, well I’m going to ask you a couple of questions, then. A few listeners sent in today an article—I believe it was in The Guardian—and it was talking about there being some trouble with reactor number two. I don’t know if you can confirm this in any way, but the article said that there was a possibility that the fuel had actually…I guess…melted through part of the containment? It was actually sort of resting on the concrete base of the containment. I’m not sure what the evidence was for this, but can you comment on this at all? Have you seen more about that?
MARK: Ok, so what they’re talking about is that the fuel would have melted through the reactor
vessel. So there are supposed to be three barriers to the environment: the first is the fuel
cladding itself. The second is the reactor pressure vessel—which is a huge thick steel
pressure vessel that normally contains the reactor, and the water, and the steam, control rods—all
those things. And then the containment building, which is a steel and concrete structure around the
reactor that will contain anything that does leak out of the reactor if there was a leak.
I think…given the information that we have, that would be speculation on somebody’s part. I’m not saying that that isn’t the case, but I don’t know of any way to confirm it. What we do know is there’s very high radiation and contamination levels in the unit two turbine hall. How that got there is not clear. I think there are three possibilities:
–One: it is possible that the fuel in the number two spent fuel pool is damaged, and the flooding
of water from all the spray and the helicopters and those type of thing has carried a lot of that damaged fuel down in the building, to the basement…
EVELYN: We talked about that being a possibility at…number three…
MARK: Well, it’s a possibility at any of these plants, right…I mean, you don’t…
EVELYN: Yeah, I think maybe we were not perfectly clear on that yesterday. All the water, if it goes over those fuel rods and splashes out or something when they’re throwing it from helicopters, that can carry radiation with it if there is spent fuel damage, correct?
[Two]: We also know that we vented a lot of steam, especially early on in this accident. That
was vented into the reactor building. We know that that caused the explosion. Unit two has the least
damage to its reactor building, but it does have some damage. Again, if that fuel was seriously damaged, then that radioactivity is in that steam. Some of it escaped, but some of it’s going to condense—and again, be washed down to the bottom.
The third possibility is that:
[Three]: That there could be some sort of leak in the containment building that with all this
water that they keep adding that some of that is leaking out into the basement of the building.
EVELYN: None of those are good things, none of those three options, right?
MARK: No. But what we do know is that for there to be this much radiation and radioactivity in
the basement of that building that it is coming from damaged fuel. There is a good probability that
both…that there is a significant amount of damage to the fuel in the reactor and, potentially, damage to the fuel in the spent fuel pool. So it could be from either of those sources, or a combination of both. But from other indications in terms of reports from the IAEA that reactor vessel water level in all these units is about half core-height, it seems kind of implausible that the core would have melted to the bottom of the reactor vessel and still have water in it, but again, without having more information as to exactly what’s going on it’s hard to actually give an answer.
It would be…as much as that person is speculating that the core may have partially melted through the reactor vessel, it’s speculation on my part saying that the radiation and radioactivity in the terminal is coming from spent fuel damage from either the reactor, or the spent fuel pool, or both. We obviously don’t have access to the precise radiation and contamination levels, we don’t know what else is going on in the plant, again—where is the transparency from TEPCO as to exactly what’s happening?
EVELYN: I feel like that should be an easy question for them to answer.
MARK: At this—again, early on we did question their transparency, but at the height of the accident
where there were explosions and things were getting worse every day…you might cut them some slack. But like I said, these people have lots of resources, they run lots of reactor plants. It can’t be that hard to get two or three reactor operators or engineers with knowledge of the plant to be able to translate the information that they’re getting, correlate that, and give some kind of comprehensive briefing.
EVELYN: Especially since there are so many international people involved with nuclear power who are offering them help. I mean, if they can’t do it, they could get help from somebody to do that.
MARK: Alright. Again, I can’t say…I can’t confirm it, I can’t totally rule it out.
EVELYN: Ok, well, let’s go on to the second question. I’ve received a few emails about this over the past few days. I think people are a little bit confused about what is going on with the venting of the steam–which I think is primarily hydrogen gas. I realize that one limitation is that you don’t know the exact design specifics of the Fukushima plants, but you’ve worked on similar plants. Can you talk a little bit more about what happens when they vent steam, where it goes, what that means?
MARK: Yes. I have to reference people back to that drawing that you posted several days ago…
EVELYN: I’ll post it again with this interview.
MARK: …as to the design of the containment of the Mark I containment. Let me just pull up the
picture myself so I can give people a good reference.
Ok, so in looking at that picture, down at the bottom is this round donut looking thing that is cut away.
That is the torus, and that torus is partially filled with water during normal operation. You
can see in the drawing some big pipes that come down at an angle, that are connected to a ring, and
spider/finger like pipes that go down underneath the water. What the concept of the torus and the water suppression are is that if you were to have a break in a pipe and be losing coolant—which would flash the steam obviously, then the water in the the torus serves as a suppression pool to cool that steam; the concept here was they could make the design of the containment a little bit more compact by having this water suppression pool to condense some of the steam and reduce the pressure within the containment structure. What they would have been doing to reduce pressure in the reactor vessel itself to allow first seawater, and now freshwater to be pumped in is they would be opening a valve at the top of one of the steam lines, and that would have a piece of pipe attached to it. That would be routed down and go into this suppression pool. So they were venting the steam out of the reactor and condensing it down in the bottom of this torus, or suppression pool. During operation, the Mark I containments are required to be oxygen free—they actually purge them with nitrogen so that there is no oxygen in there. The reason for that is to prevent an explosion inside the primary containment. So even if you get the fuel damage and the hydrogen, because there is no oxygen in the dry well portion of the containment, then you don’t have the oxygen to interact [with] and cause an explosion. Umm, let’s see…what else
EVELYN: So when they vent that, I guess there is some confusion about where that goes.
MARK: Ok, so there’s two different venting that would have went on. First, we vent steam into the
bottom of this torus, and it condenses. But eventually what happens if you vent enough steam,
then you start building up pressure in that containment building. In order to prevent exceeding the
pressure rating of that containment building, then you would do a second venting where you would
actually vent the containment. So initially we vented the reactor vessels, and we quenched that, but after a lot of doing that we build up a lot of pressure and steam inside the containment and
now we gotta to vent that.
EVELYN: And you vent that to the reactor building, or to the atmosphere, or both, or…?
MARK: Ok, and I think this is where a lot of confusion is coming from for people, because the original
design of these plants had that containment venting through a series of duct works and filters right in
the reactor building. There was a retro-fit required by the NRC back in the late 80s for all of the Mark
I containment structures—I think there are 23 of these in the US—to put in a hardened vent for the
containment. The hardened vents actually go into a fairly strong piping system that is outside of the
reactor building. If this particular scenario occurred at a US plant when they vented the containment, it would have been vented outside of the reactor building, and you wouldn’t have had the explosion of the reactor building. Generally speaking, most regulatory agencies around the world follow the directions and guidance of the NRC. In this particular case, apparently, the Japanese government did not require those modifications to the Mark I plants.
EVELYN: Well, and we know there had to be steam building up in there because we had the
explosions—I mean, there is nothing else that can explain those explosions, correct? I mean…and we’ve confirmed that that’s why.
MARK: Correct. Again, this was a change in the design of the plants that was required for plants in the US, but it doesn’t mean that it was done to all the plants worldwide; and apparently it was not done to these plants in Japan. The other thing I guess I could comment on with respect to the containment is there was a lot of talk early on about—potentially—damage to the core in Reactor Two, that there was some type of explosion. There were also modifications ordered by the NRC to the torus areas of these containment designs to strengthen them. There were I think…three or four separate modifications that were done because after these plants were built there were studies that realized there was going to be a lot more stress and loading on some of this piping than was originally considered when the plant was built. Each of the utilities have had to go back and implement three or four different design changes and strengthen or modify how, exactly, some of those pipes are connected down in the torus. It’s again speculation, but my guess is that when this is all said and done and done, there may be something to be learned where whatever was going on in Reactor Two, the stresses exceeded the capability of some of that piping that you can see in the cutaway picture—and that may have been the source of the explosion that they heard. It might have just been simple failure of some supports or some piping. You would not expect a hydrogen explosion within the containment because it is inerted with nitrogen.
MARK: Ok, so again as a recap—the first venting we would do would be from the reactor vessel down a pipe, into the bottom of this dry…excuse me, torus, where the water would quench it. But if you keep injecting water, and keep venting, you’re going to build up enough steam and enough pressure with-in that dry well portion that you’re going to have to relieve the pressure of the containment—not the reactor vessel, but the containment. And the way it was obviously done at this plant was through this old method, because apparently they didn’t have the design change for the hardened venting, and that was within the reactor building. Again, speculation, but I assume since they’ve reported on Units Five and Six that since they’ve removed some roof panels or drilled some holes, that they didn’t do the modifications on those units, either. As much as we might criticize TEPCO—and we should—because they certainly were aware, made aware, by GE that the US was requiring this and they could have undertaken it themselves—but also, where was the Japanese government oversight to require these changes?
EVELYN: Well, I think there will be many hard lessons learned from Fukushima. I know the NRC is taking an active role in looking at all the US plants, but I hope Japan is does that as well. If that problem is at these plants, at Fukushima, who knows how many other plants this might be a problem at—not just in Japan, I guess, but worldwide.
MARK: So I know that our own regulatory body, the NRC, is not perfect, but this is one case where they did require these changes, and these changes were made at all of the plants that have this containment design in the US. I hope that clears it up for people, because I think people were confused because they see online what the NRC is requiring, and they’re wondering ‘well, if they have these vents outside the building, how are we getting explosions inside the building?’. The way that we did that is apparently these plants did not get those design changes.
EVELYN: Ok, well thanks for commenting on that, dad. Do you have anything else before we end the interview for tonight?
MARK: I don’t. Again, I really think that after this much time they just really have to step it up and
provide more information. It’s kind of sad that different people around the world have to speculate
on what’s happening when—again—they have a lot of resources at their disposal, and they should be
providing a comprehensive overview that just isn’t happening. Again, what happens is…they’re…if they have any credibility left, they’re destroying it by not being transparent.
EVELYN: As happy as we are that these interviews can help people, we’re not working on this full time; we don’t have the resources that they have, we don’t have the information that they have, I mean…this isn’t really our job to be doing this. But because there is so little cohesive information, we feel that we have to do these updates to the best of our ability. We try, but it’s not perfect and, really, it would be great if TEPCO and the Japanese government, and different organizations could step up so that we wouldn’t have to do these updates so we wouldn’t have to do them—and they could do them much better than we could, that’s for sure.
MARK: Do you have any other questions?
EVELYN: That’s it for tonight.
MARK: Ok, I’m not going to be able to do another interview for a couple days, because I’m going to be on an airplane, and be on another continent, but hopefully we can get together on Friday.
EVELYN: We’ll plan on doing that Friday. My dad will be in Europe, but we’re going to try and arrange a time so we can talk on Friday. That will be our next update. If you have any questions, send them in, and if there is developments over the next couple days we’re sorry, but we won’t be able to comment on that until Friday. So that’s it!
MARK: Alright, thank you Evelyn, goodnight.
EVELYN: Ok, goodnight dad!
26:36. End Interview.