March 15, 2011

4th Interview with My Dad, a Nuclear Engineer, about the Fukushima Daiichi Nuclear Power Plant Disaster in Japan

Posted by Evelyn Mervine

Update: All the interviews are now available on a vimeo channel. Here’s the vimeo channel:

Update: Announcing Daily Updates from My Dad 

Here is a vimeo video of the interview:

Update: I have cleaned-up the original transcript.

Update: Thanks to Michelle, transcript is now available after the jump. 

Interview 4: Tuesday Morning, March 15th, 2011
4 Days Since Tōhoku Earthquake and Tsunami

EM= Evelyn Mervine
MM = Mark Mervine

EM: Good morning, dad.

MM: Morning.

EM: All right, are you ready for Interview Number 4?

MM: I hope so.

EM: Okay. We’ve got our work cut out for us with all these interviews. So before we begin, I just want to let people know, who might not know, that this is actually the 4th in a series of interviews that I’ve done with my dad, who’s a nuclear engineer. I am not going to go into his credentials again in this interview, but if you would like to see what his credentials are and listen to the previous interviews, I encourage you to do that. They’re located, the previous interviews – both audio files and actually, now transcripts, thanks to some listeners— they’re located on my geology blog, Georneys ( You can also find them on the Skepchick website (

So, I’m just going start right out because there have been quite a few developments in the last 24 hours or so since we’ve spoken. And I was wondering if you could just give us an update on what’s going on in Fukushima.

MM: I’ll do my best. It’s extremely difficult because information is very hard to come by, and there are different bits and pieces available from different sources. But it’s very difficult to put together a complete picture.

EM: Okay.

MM: Let me start first with a little bit of good news, which is that, as we explained yesterday, there’s actually two sets of power plants: Fukushima 1, which has been the one that’s really been in the news, that has the serious issues that we’ll talk about in a few minutes, and Fukushima 2, which is a few miles away to the south. That site [Fukushima 2] has 4 reactors. They were also experiencing difficulties with loss of power. But the latest report from the Tokyo Electric Power Company website indicates that all 4 units there are now in cold shutdown. So that’s very good.

EM: That’s very relieving news. Do you know how far away the two plants are? Are they sort of close together and affected by the tsunami similarly?

MM: They’re about 7 miles apart.

EM: Okay.

MM: Now, with respect to Fukushima 1— which again, to remind everybody, has 6 nuclear power plants— it’s been a very challenging 24 hours. As best can be determined from the various different news reports, there was an explosion in the Number 2 reactor building, which, according to some reports, may have caused some damage within the primary containment of the reactor, in the suppression pool, at the bottom of the reactor. So, if you look at that picture that you posted yesterday, there’s kind of a doughnut-shaped tube that goes around the bottom of the reactor that holds water.

The purpose of that pool of water is to condense any steam that’s in the containment building and release the pressure. And, again, reportedly, there may be some damage to that suppression pool. The reports indicated that before the explosion, the containment building had about 3 psi [pounds per square inch, a unit of pressure] and afterwards, it was 1 psi.

EM: And yesterday you said that there was a possibility that there actually might be an explosion that could affect the containment itself. And you were saying that was because of the type of pump that they had to use? Is that what happened? Were they not able to actually get the normal pump running or do we not know?

MM: Well, what they’re trying to do, which is what they did at the 1 and 3 Reactors, is pump seawater into the core, to try to recover the core. In order to do that, because these pumps that they would be using for pumping seawater would be relatively low-pressure pumps, they would need to reduce the pressure in the reactor by venting the steam— initially, to the containment building and then, obviously, they have to worry about pressure in containment building, so eventually, whether they do it into the containment building or directly to the atmosphere, it’s going to get into the atmosphere of the reactor building.

And, as we saw in Units 1 and 3, based on indications that we have of cesium and iodine being in the atmosphere, based on the fact that we had an explosion, it was probably a hydrogen explosion, which was created by the overheating of the fuel, and H2O, or water, interacting with the zirconium cladding of the fuel and causing zirconium dioxide to be formed and hydrogen gas.

So, they had an explosion in Reactor 2, but the news reports are very scattered, and it’s very difficult to get any kind of complete information as to the extent of the damage.

EM: Okay. So, maybe this is something that we’ll have to continue and update on a little bit later, when information is more available.

MM: The other thing that’s happened is there was a fire in Unit 4.

EM: Yes.

MM: Unit 4 was shut down for maintenance at the time of the tsunami and earthquake and had not been experiencing any problems cooling the core because they were already shut down and in cold shut down.

 But, if you remember yesterday— and part of the reason I asked you to put the picture of the Mark 1 Containment up is because of the potential that lots of water [could have been lost from] the spent fuel pools. And again, it’s very difficult to determine exactly what’s happening because the reports are very scattered. One report I’ve seen said that the fire was in the spent fuel pool, that potentially it was caused because the water level had lowered and fuel had started to melt and hydrogen had formed, which caused an explosion, which tore two holes in the building. Another report I saw said that the fire was in a lubricating oil system.

But then I also saw a report that they’d been unable to get water to the spent fuel pool. So it’s really unclear exactly what’s happening. And I think this is an important point that—you know, obviously these folks at these plants are under a lot of pressure and I’m sure a lot of people are working real hard and doing the best that they can, but the transparency, with respect to the communication to the public, is terrible. I mean they’re not providing any kind of real-time updates and the updates are not very detailed. So, it’s difficult for anyone to determine what’s actually going on at this plant.
And if, in fact, they did allow the water level of the spent fuel pooling cool— excuse me, the spent fuel cooling pool at Unit 4 to get below the top of the pool, in my opinion, that’s inexcusable. There should have been an operator that toured that building once an hour; at first that they noticed that they were having troubles, they should’ve gotten water up there and covered it, as we talked about, just with a fire hose, if necessary, yesterday. So, they really need to work on the transparency, and I think that the Japanese government has got to ensure that that happens and [that] they’re transparent with the general public.

EM: Well, I think that’s especially important. Because if you’re not transparent, then there’s going to be all sorts of false information that’s circulating around, and you don’t want that, because you don’t want people either to under- or over-react to a situation. You want them to have the proper information so that they can make an informed decision. Wouldn’t you agree with that, Dad?

MM: I think if there’s someone like myself, that has, you know, a significant understanding of how these plants work and you’re having difficulty piecing together the different pieces of information that are available, then I don’t know how you would expect someone in the general public to be able to know what’s going on. So again, I think that there’s got to be more transparency and more communication relative to this event that’s occurring at the Fukushima Plant.

EM: Okay. So, this question actually is perhaps somewhat related to this, this concept of the media and somewhat transparency. I don’t know. I know that you’re not really on Facebook or Twitter or anything, but maybe you have some idea of what Twitter is, Dad. So Twitter is this- basically this sort of social media, short messaging site, where you can—

MM: I’m fully aware what Twitter is, I just—

EM: Okay, I don’t know, you don’t even have Facebook, so—

MM: I just don’t have the time everyday to Twitter, so—

EM: Okay. Well, anyway, there was a Twitter user, and he actually, I believe, is a nuclear engineer. And he went on Twitter, which is kind of interesting that we can do this now on Twitter. His username is “arclight,” and he actually went on Twitter, and he was giving people these short updates about what was happening at Fukushima and his perspective on it and trying to inform them a little bit about nuclear power and basically just give people information because a lot of people go to Twitter for information these days. And he actually was given a Cease and Desist order from his employer, which is presumably a nuclear power plant. And they actually said that he cannot continue with Twitter, or they would threaten to terminate his employment. And so he actually had to stop posting his updates, which I think was disappointing for the public, and for people who were relying on him for some information. And I can’t comment on the accuracy of the information, but he was trying and he was a nuclear engineer.

Do you have any comments on that? Do you think that if you were currently in nuclear power, if you weren’t retired from nuclear power, would you be able to conduct an interview such as this?

MM: Well, obviously I can’t comment on what may have, or may not have transpired there. I’ll just go back and say that there needs to be more information provided, more often about what’s happening at Fukushima. And I think that the Nuclear Industry Organizations, such as the Institute of Nuclear Power Operations, the Nuclear Energy Institute, and the International Atomic Energy Agency, need to also be more transparent and provide more updates on their websites as to what’s

EM: Okay. Thank you for commenting on that. Do you have any other comments about the current situation today in Fukushima?

MM: I basically told you everything that I can. I think that today has been one of the more difficult days to pull any information together. Ee do know that, either due to the event at Unit 2 or the event at Unit 4, there was a fairly significant release of radiation to the environment. And it caused the radiation levels at the plant to go up significantly. And, again, I can only rely on the reports that I saw, but the radiation levels within the plant were to the point where they evacuated most of the workers at the plant.

And they were also— I saw one report that the [radiation] levels spiked quite high at the site
boundary and then came down. And even after— a couple of hours after the events yesterday, they were around 240 millirems per hour.

EM: Can you explain what that means?

MM:  That’s about as much radiation as the average person would get in an entire year from just normal background sources.

EM: Okay, but to get that all at once, does that pose a health risk?

MM: Well, at that level, if you were there for an hour, it would not. The disconcerting fact would be if it stayed at that level and you were there for a longer period of time. The dosage is cumulative. So, after 4 hours, you would’ve received almost a thousand millirems. And after 20 hours, or less than a day, you would exceed the limit for a radiation worker in the US.

EM: For what time period? For a year?

MM: For a whole year.

EM: Okay, so that’s quite serious, because if those radiation levels continue to stay that high, if they actually are that high, then the workers can’t even get in there to really deal with the situation, is that correct?

MM: Right. I believe the radiation levels have come back down. The fact that they went up that high does indicate that there had to be a fairly significant event that occurred.

EM: All right, so now I’m going to be asking you some questions and I’ve actually—as I said yesterday, I’ve been really surprised at how many people are listening to these interviews. I hope that they’re helpful to people. If people have any feedback on them, please let us know. If you have questions, send them in.  So, I have been receiving lots of questions and comments from different places. So, if I miss your question, I’m sorry, send it again. But we’ll just do our best.

MM: And a comment from my side is I hope the information that we provide is helping people. We’re trying to do it in a neutral way, just trying to explain what’s happening to people. And I hope we’re able to answer your questions this morning.

EM: And I just want to say thank you so much, Dad, for doing this and taking the time to do this, and I feel very fortunate that I can call you up and I can get my questions answered. And rather than just have you answer my questions, I thought it would be great if you can answer other people’s questions as well.

So, let’s start in on this. So, one question that I had from a few people, particularly people who are living in Tokyo, is people, especially [people] who are foreigners, are wondering if it would be an overreaction to actually consider leaving Japan for a couple of days, to actually get out of the country, in case there is more of a problem with the nuclear power plant. Do you have some advice on that?

MM: So, if somebody was in Tokyo, I would not be too alarmed. After yesterday evening’s events— US time, that is; it was morning obviously in Japan— the radiation levels, according to the government, did go up in Tokyo, but not anything that would be of any concern whatsoever. They were just maybe double the normal background levels. And we do know that a few hours after these events of the radiation levels around the plant have dropped. And I would not be overly concerned to be as far away as Tokyo. Now, of course, if you were closer to the plant, it may be more of a concern, but I think the destruction of the infrastructure due to the tsunami is probably more significant than any, any threat of radiation today. Now, the caveat is the unclarity with respect to what’s happening to the spent fuel pool in Reactor 4. The big concern, obviously, there is if they’re not able to keep that covered and if that melts, then releases radiation to the environment, there’s no containment to keep that in.

EM: So, how far could that potentially spread, if that were to happen?

MM: That depends…

EM: Okay. But that could be a serious concern?

MM: …on the amount of radiation released. But this point in the game, there haven’t been radiation levels in Tokyo that would cause any alarm.

EM: And they have evacuated, as you said, or they’ve tried to evacuate—

MM: They’ve asked people to either shelter or evacuate at a distance of 30vkilometers from the plant.

EM: Right. And there are still a few people within that zone. I’m not sure if they’re forcing people to evacuate, but at least yesterday when I read one news report—so this is from the news— there were some people who were refusing to evacuate, so I don’t know if any of those people are listening to this, but please, please do evacuate if you are close to the plant and the Japanese government has requested it.

MM: I would follow the request of the authorities to either evacuate or shelter.

EM: Okay. Let’s continue. So another— I think we’ve sort of addressed the radiation levels— another reader was wondering, sort of how long Japan is going to still need to be worrying about this and the nuclear disaster. And, again, I think it depends on what’s actually happened. But as you mentioned yesterday, this is something that is not just going to be today or next week, this is something that’s going to be weeks and perhaps years to actually deal with this. How long do you think it’s going to take them to actually fully clean up and decommission and decontaminate everything?

MM: Well, to fully clean up and decommission and decontaminate the site, you’re talking years and years. I think what we’re more concerned about is how long until the situation is stable, and can we be assured that no more explosions or meltdowns— partial meltdowns or radiation leaks— are going to occur? And that’s a hard question to answer because if the radiation levels at the plant are such that they have to evacuate most of the workers, then until they can get that under control, they can’t even do any work.

EM: So, how do they do that? How do they bring radiation levels down when they cannot bring workers close to the plant?

MM: The way to do that is to make sure that the cores of these reactors are completely covered and to make sure that the spent fuel pools stay completely covered. Water  will cool; it’s also an excellent shield of radiation.

EM: So, they need to get water on these as quickly as possible?

MM: And so I think the most critical thing that they need to accomplish at these plants, beyond making sure that all of the fuel is covered by water and that all of the spent fuel is covered by water, is to try to restore power, so that they can begin to restore cooling and water flow to all of the 6 spent fuel pools[1] at this site. Because there’s 6 reactors, And obviously if they get power back, then they would be able to use more systems, which will help them control the situation at these plants.

EM: And they’ll have better monitoring equipment as well, so they’ll be able to have more warning when something’s going on, presumably. And, I mean, the good news is that Fukushima 2, as you said, is under control. Are they [Fukushima 2] operating? Is part of the problem here that there’s a power shortage— I mean, somehow, they must be able to get power to this Fukushima 1 site from a different power plant.

MM: As far as I can determine, the power that they have is from generators. I think that’s because of the damage to the electrical grid.

EM: Okay. All right, so I’m going to move on to another question. This one’s a little bit complicated, so hopefully my dad can help me interpret the question. So, a reader sent in something that he had read, and I’ll try to post the link up here, it’s from something called- it’s a commenter on something called “Next Big Future[2]”.

And the question was: “Someone cited a Sandia report, the GE BWR MK1 containment design has been estimated as having a potential 40% failure rate in the event of a full core meltdown. With pooling fuel having the capability to melt through the sides of the reactor containment walls.”
Can you, first of all, translate that question into English and [then] answer it?

MM: Okay. So, what he’s talking about is the Mark 1 Containment Design, which you posted the picture of on your website yesterday. And 5 of the 6 reactors at the Fukushima 1 site have a Mark 1 containment. Um, the first 5 units – 1 through 5. Six is a newer plant and has a little bit newer design. And what he’s saying is in the event of a full core melt that the core would melt through the reactor vessel and would have a 40% chance of melting through the containment structure, which in the case of this plant is a concrete and steel liner that surrounds the reactor. As long as they’re able to continue to get water into these reactor vessels, then that’s not going to happen. This would only happen in the event of not being able to get any water whatsoever into either the reactor vessel or the containment building.

EM: So, I guess a good point here is that although we should be reassured by the containment buildings, to a degree, they’re not magical boxes that contain all radioactivity. You do have to monitor the pressure in them, you do have to add water. There are some controls that are really important in making sure that those containments stay secure. Would you agree with what I just said, Dad?

MM: I agree. And, therefore, I go back to what I said a couple minutes ago that the priority needs to be on getting electrical power back to these units, so they can restore some of these systems that will allow them to better control what’s happening. I’m sure it’s a very difficult task, because the seawater, obviously, from the tsunami, flooded where the diesel generators were, which is also probably where a lot of electrical switch gear is. Seawater and electrical switch gear do not mix well. So, there’s probably a lot of work to restore the electrical switch gear and other things, but again, that would be, I think, a top priority, to try to get power back. You don’t need to repower the whole plant; you need to try to get it back to the most critical pumping systems.

EM: I see. Okay, moving on to the next question. This is actually a question that I’ve seen circulating around the internet, and someone did send this into me. They wanted to know if you could comment on the possible danger to US residents and if there’s any precautions that a reasonable person might take in the United States at this point.

MM: At this point in time, I don’t think there’s a concern, unless the situation gets worse. I think our biggest risk, based on what’s happened in the past 24 hours—and again, what we commented on yesterday— was making sure that the spent fuel pools stay covered at these site, so that would include the 6 spent fuel pools[3] at Fukushima 1 and also Fukushima 2. If they’re still struggling with electrical power there [at Fukushima 2], they would have the same issues with respect to cooling and water for the spent fuel pools there.

EM: Can you, can you give me an idea, Dad, because, I mean, my idea of one of these pools is kind of a giant swimming pool. How much water do you have to add to one of these pool— say, on an hourly basis, or a daily basis— to keep that [water] level at a good level to make sure that things are safe?

MM: So, that’s a good question. And the answer is: it’s going to depend. So, these reactors are refueled—and I don’t know the specifics of the refueling schedule at these particular plants— anywhere from every 12 months to every 24 months. So, depending on when it [the reactor] was last refueled will depend on how much heat generation there is in the spent fuel pool. So, for instance, at Unit 4, which was in an outage, they might have just recently removed the spent fuel from the reactor in the spent fuel pool, which means it’s still quite warm and generating quite a bit of heat. So, you could expect that, in that particular case, that you would have to provide more cooling to that spent fuel pool than you might for a reactor that, you know, last time it was refueled was 18 months ago, and the fuel has cooled way down already.

So, you can’t answer the question specifically, unless you know the specifics of when the last refueling was, how many fuel bundles were taken out of the reactor and put in the spent fuel pool, because they don’t replace all of the fuel all at the same time. They’ll replace approximately a third of the fuel every refueling outage. But depending on any other work that was going on, they might have been doing other work, either inspections or repairs to the reactor vessel. They might have taken all the fuel out, temporarily, from Unit 4, to do this work, and planned on putting two-thirds of it back, along with one-third of new fuel. So, without knowing the details, it’s hard to answer the question.

EM: I guess in over the past few days, we’ve [felt] sort of relieved that some of these plants were shut down for maintenance, but, actually, if there were a number of spent fuel rods in the pools, it sounds like that could actually be a problem and that may be what contributed to the fire.

MM: Well, [it would be a concern if there were] a large number of spent fuel modules that had recently been in the reactor. That  spent fuel [pool] could be full, but if all the fuel is 10 years old, it’s already pretty much cooled off. It’s really a function of how many of those fuel bundles were in the reactor most recently.

EM: Okay, I think that those are all the questions for today. Actually, Grandma had one question, but I’m about to run out of time, so I might have to call you back[4]; we’ll see if we make it. Grandma— my Grandma— wanted to know: Why do we build nuclear power plants next to the ocean? Is that necessary? Is that because we need, we need water? Can you answer that really quickly?

MM: So, as the steam goes through the turbine, it then needs to be cooled and turned back into water. You have three ways of doing that: either from a river or a lake, from an ocean, or from cooling towers. And in a lot of cases, power plants of all kinds— not just nuclear power plants— are built next to large bodies of water, because we need a lot of cooling to get the steam back into the water and pump it back into the boiler or the reactor, depending on the type of plant that it is. So, in this case, these plants were built along the coast. A lot of the nuclear power plants in Japan are built along the coast.

[1] As my dad discusses in subsequent interviews, there are actually 7 spent fuel pools at Fukushima 1: one for each reactor and also a large, common spent fuel pool.
[2] Look for this reference when going through past emails & comments.
[3] Again, there are actually 7 spent fuel pools at Fukushima 1.
[4] Originally, I used free recording software with a time limit. Shortly after this interview, a representative from Skype contacted me and generously gave me free recording software with no time limits.