Transcript
ALI MOORE: Joining us now live from Melbourne is Dr Peter Karamoskos, he's a nuclear radiologist and a public representative of the Radiation Health Committee at the Australian Radiation Protection and Nuclear Safety Agency, although he's not representing ARPANSA tonight.
And he's also a board member of the international campaign to abolish nuclear weapons.
Dr Peter Karamoskos, many thanks for joining us.
DR PETER KARAMOSKOS, NUCLEAR RADIOLOGIST: Thank you, Ali. Thank you for having me.
ALI MOORE: We've just heard the latest about these reactors. Three have experienced explosions, there's been a fire at No. 4 in a spent fuel storage pond. Just a short time ago, there were reports of cooling problems at reactors 5 and 6. What's your assessment of the danger?
PETER KARAMOSKOS: Well, from what I understand, the IAEA, the International Atomic Energy Agency has said that
reactors 1 and 3 are in cold shutdown, so the risk there has significantly decreased so far as the cores go. The remaining reactors, that is a new development and clearly considerable risk there as well.
The problem with these reactors is that the challenge is to cool the core so that it doesn't go into meltdown, and then of course if it does go into meltdown, the containment structures need to remain intact. That's the fear, that's the danger and all attempts need to be addressed at reducing the temperature. Part of the problem of loss of coolant is fuel rods are getting exposed. Of course, with no coolant, they get hotter and hotter and eventually melt.
ALI MOORE: So even four days after the shutdown, there is still a risk, certainly in No. 2. We don't know what's happening in 4, 5 and 6. But there is a risk of meltdown?
PETER KARAMOSKOS: Reactors 1 and 3, if they're in shutdown as the IAEA says, there is probably no chance of it because the temperature would have dropped below 100 degrees Celsius and also the pressure in the reactor vessel is atmospheric pressure. That's what cold shutdown is. I think the risks have significantly dissipated in those three reactors.
The others, we're still in a state of flux. Like this whole ugly disaster has been, we have not been able to know which way it was going to go, and I think that's part of the fear that the inexorably, until the next level of problem arises, you don't know what's going to happen.
ALI MOORE: Tell us about spent fuel rods because that's where the spent fuel rod pool is, where the fire was at on Reactor 4 and the International Atomic Energy Agency says that radioactivity through that fire was being released directly into the atmosphere. Are the spent fuel rods potentially as risky as fuel rods inside the reactor?
PETER KARAMOSKOS: Just to give you a bit of a rundown of what spent fuel rods are about,
when the fuel rods are used in the reactor, they get contaminated to such a degree by the by-products of the reactions that they're removed and replaced. These rods are still quite hot so they need to be put into a swimming pool, like a pool of water, to keep them cool for several years before in dry-cask storage. In Fukushima,
these fuel rods are in the ceiling cavity if you like in these buildings outside the main structure. As long as these ponds remain intact and the rods covered with water, they're OK. Of course, these buildings have been blown up, so we don't actually know what has happened to these fuel ponds and one of the concerns I've had is that the authorities from Japan have not really been forthcoming in telling us what's happening with these fuel ponds.
There is also a common fuel pond. I might add, these fuel ponds house about 3,500 fuel assemblies. The reactor core houses 700 fuel assemblies. So five times as much in the fuel assemblies and ponds as there are in the core and they're not contained.
The whole area. Six reactors in this precinct, 6,500 fuel assemblies in ponds. This is just above the ground and we don't know whether this cooling pond has actually been contaminated with sea water. If it has, it's quite corrosive and the cladding that covers these fuel rods will be degraded and exposing the actual fuel rods themselves.ALI MOORE: And am I right that if these fuel rods, these spent fuel rods, these assemblies that they're known as, if they're too close together, we don't know. They could be tipped upside down, higgledy-piggledy because of the tsunami there is a risk of a fire, of an explosion?
PETER KARAMOSKOS: Two reasons you might get a fire in these fuel rods. Firstly they're hot so they need to be cooled. If the water is drained out of these ponds, then there is a high likelihood of them catching fire.
Secondly, if they have close proximity, the heat adds up and you get a very hot collection of fuel rods that will ignite. Once they ignite, of course all the radioactive compounds are released into the atmosphere, and I understand from the IAEA report today that the Reactor 4 fuel pond fire was releasing about 400 millisieverts per hour into the immediate environment.
To give you an idea, one millisievert is the regulated maximum for the general public. Now of course, remember this is 400 in the immediate area, I'm not suggesting that any of the public has been exposed to this but it gives you an idea of the intensity of the radiation that in that vicinity.
Of course, once you start getting to about a thousand, 5,000 millisieverts, they are lethal doses. These have dropped back. The IAEA has reported that the fire has been put out, but it's important to note that this is an ongoing risk with these fuel ponds. We need to get a status on the fuel ponds.
ALI MOORE: Indeed, you talk about the radiation levels and the government has said they have dropped back. Earlier they did say they were a risk to human health. What are the health implications? How long do you have to be exposed to these sorts of radiation levels to have a problem?
PETER KARAMOSKOS: Well, there are two types of radiation effects on human health. One is acute radiation sickness where you get many hundreds, thousands of millisieverts and that gets you acute radiation sickness and so you get things like bleeding in your gut, your blood bone marrow stops producing blood cells, you start getting bleeding from your cavities, people dehydrate and people die within days or weeks depending on the dose. That's acute radiation poisoning.
There is the longer term effects of much lower levels of radiation and these cause cancer. The risk of getting cancer eventually is directly proportional to the dose. So with very minor doses of radiation, your risk is very minimal, but as the dose increases it becomes significant, and this can take decades to appear.
So it's very hard to actually detect because cancer is very common in the population anyway, and because it doesn't happen so suddenly or very quickly after these events, it's not often, it doesn't have as great an impact as the acute radiation sickness that we see.
The other one I might point out of course is children. If you get iodine released from a nuclear reactor and also the fuel rods, children will contract thyroid cancer. Their thyroids are very sensitive to it. In fact, the Chernobyl disaster showed 6,000 cases of thyroid cancer in children. So they are the sort of health effects that the general public can be prone to and of course the emergency workers more particularly with the acute symptoms.
ALI MOORE: And would you say, we're only four days on. Are we still looking at a very long time until we have any real certainty about what is going on and some sort of resolution to the situation?
PETER KARAMOSKOS: Well, first I might point out that we still don't know how this is going to all pan out. It's comforting to know that the first three reactors are in cold shutdown. We don't know what's happening to the other reactors or what's happening to the spent fuel ponds. So any statements at this stage are very premature.
I note that there are several statement been made in the media about the degrees of radioactivity are not, in Australia I mean, are not of a level that would endanger public health. I think that's a very premature statement to make given that the disaster is unfolding as we speak.
ALI MOORE: Indeed. Look, thank you very much for joining us with your insights tonight
PETER KARAMOSKOS: My pleasure. Thank you.
http://www.abc.net.au/lateline/content/2011/s3164928.htm
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