News story

The latest advice on Japan from the Government’s Chief Scientific Adviser

Sir John Beddington, Chief Scientific Adviser, with Jill Mearer (Health Protection Agency) and Hilary Walker (Department of Health), held a teleconference with the British community in Tokyo on 7 April.

This was published under the 2010 to 2015 Conservative and Liberal Democrat coalition government

The teleconference was chaired by the Deputy Head of the British Embassy, David Fitton. This is the transcript of the conference.

[Sir John Beddington (JB)] The first thing to say is that although the situation is still extremely serious it’s improved for two reasons. First, TEPCO has now established an electricity supply to the plants, and is now able to use freshwater for cooling the reactors and it’s really helped a lot. Second, the natural processes of radioactive decay coupled with the short half life of Iodine 131, means that any threats to your health from any future emissions at the plant have significantly reduced.

As TEPCO work to manage the situation at the plant what we can expect is that from time to time there will be relatively small releases of radiation into the environment. We’ve seen that over the past weeks and we’re likely to see it in the forthcoming few weeks. We understand TEPCO are planning to inject nitrogen into the main containment unit of Unit 1 and the reason for this is that nitrogen is an inert gas and it’s going to cut down the chance of a hydrogen based explosion so it’s a very sensible thing to be doing and certainly our experts in the UK support this. This injection of nitrogen may mean from time to time there is a release of what looks like smoke or gas or steam from a reactor and there will be some radiation in this steam. But the radiation emitted will be nothing like the sort of levels associated with the meltdown of a reactor or burning of a pond.

The situation then is that things are improving in terms of practically managing the situation at the plant and as natural processes Iodine 131 and the other assorted elements have already decayed. In addition there is an overall decline in the level of energy in the reactors. I think that this is the basis on which we felt it would be perfectly sensible to change the travel advice because as you probably recall from earlier conversations, even in the very worst case scenario of the reactors and ponds all going up together, there was only a very moderate concern about the level of radiation in the Tokyo area, even when combined the worst weather and the main concern at that time was to do with the radioactive iodine which might be there and actually that has pretty much disappeared as a health risk in the Tokyo region. So, all in all, we feel that the situation, although it’s extremely serious, is improving. I’m going to ask Hilary and Jill to expand a little bit in a moment on the issues to do with food and water and so on, but I think there will be continuing concerns for many weeks and months on any food and water from the area and in particular seafood, because we are aware of quite significant amounts of radiation that actually have been released into the ocean close to the plant. But in terms of immediate concerns for human health in the Tokyo region, we believe this has significantly reduced over the last couple of weeks, and that was the basis for being confident to indicate that FCO could modify travel advice.

[David Fitton (DF)] Thanks very much. I think we’d agree with that here, from our point of view too, the input we had to the travel advice changes. Could I ask your colleagues to say a few words about the food and health situation please?

JB I’ll ask Hilary first and then Jill to comment if I may.

[Hilary Walker (HW)] Just to reassure everybody that John’s advice, which is absolutely what we all agree with, is that in the Tokyo region the potential risk, and it was only a potential risk, has now really disappeared because of course the isotope Iodine 131 has now decayed away. The key now is for those of you that happen to be living or working nearer to the plant and for those of you that like to eat your fish and your seafood is you really do need to follow the Japanese authorities’ who are banning the fish and food from the affected regions, not to eat food and fish which comes from the area round the reactor and I’m sure that Jill can give you a little bit more information about that.

JB OK thanks very much Jill. I think the only other thing to say is that, which is essentially to repeat a point we made when we last spoke on one of these calls, was that the Japanese regulations in terms of permissible radiation levels are at least as stringent than those applying in the UK and Europe. I think that’s probably all from our side David, we’re happy to take questions now.

[DF] OK thanks very much. If I may I’ll just ask a couple of very quick questions which somebody’s asked me to raise, they couldn’t join us today. The first is really on that last point about food and seafood. Clearly a lot of people here are worried about the discharge into the sea around Fukushima, and we heard your comments last time about not eating shellfish or seaweed if you could avoid it from that area. Another area that people are worried about is milk, eggs, dairy products from that area or some of the neighbouring prefectures. Is there anything you could say about that?

JB I’d probably pass to Jill. I think the advice is much the same in the sense that the Japanese will actually be testing these food products, and their regulations are really quite stringent, and if any contamination was detected in any samples from other areas that would very quickly become apparent, but I’ll pass to Jill on that now.

[JM] Yes that’s right, the primary concern at first is the radioactive iodine which has already undergone three half lives so it would be down to a quarter of the level that it would be when released from the plant. The radioactive iodine is also decaying within the plant itself because the reactors are not actually operating at the moment, therefore any future releases are not going to contain significant iodine. But, once again, if we’re thinking about the caesium contamination that might get on to the soil, grow through the grass, that is easy to detect and to regulate within the legal regime in Japan. And as I said with the vegetables, it may be that milk is banned from quite a wide area, even in areas where people can still live quite safely, but again we will look to what the real monitoring tells us which is a much more powerful way of finding out what the problem is than mere modelling.

[DF] OK that’s very clear, thank you. The other one was one I think Sir John’s already answered which was about the nitrogen injection which began last night. And I think he said that seems to be what we would expect them to do to try and reduce the pressure and to cope with the situation. So far it seems to be going on and I expect it will go on for a few more days, would that be right?

JB Yes, I think it’s a very sensible idea, because the reactors are surrounded by a containment vessel and the key is to try to ensure that pressure in the containment vessel, or indeed any potential for explosions, is kept as low as possible. Putting nitrogen gas in to purge the hydrogen gas means that you lessen the chance of any explosive activity which might have the potential to essentially break that containment vessel. So it’s extremely sensible, it’s the sort of thing that regulators throughout the world would actually advise and I think that we would expect it. As I said earlier, there will be occasional releases of gas or steam, which may look a bit alarming if you see them on the TV, but they are controlled, and the amount of radiation released will be quite small. The Japanese will be monitoring the amount of that radiation released due to the need to monitor the health of their workers on the plant.

[DF]OK. Thanks very much, I’ll ask others in this room first of all whether there are any questions they want to ask. Yes, you’ve got one, David?

[Q] Good morning. This may be a question for Hilary from the British School. Many staff and parents have returned to Tokyo in the last week or so, and are asking me about whether they should be receiving iodine that was given out by the Embassy. In the light of what you’ve said is it still necessary for iodine to be collected as a sort of backstop by these parents?

JB We think that in terms of the iodine as we’ve explained, the natural processes of radioactive decay have reduced the potential for a significant health impacts. In terms of taking iodine tablets, the only situation you should take them would be just before some form of radioactive plume came overhead, so there’s manifestly no need to take them at present. Actually we think the need for iodine tablets is probably over. We will discuss that in full detail at SAGE and we’ll put our advice in to COBR. Hilary over to you.

[HW] Thank you, Sir John. I think you’ve actually said what I needed to say. Basically the risk from iodine is now far, far less than it was when we sent over the potassium iodate tablets for you to use. And again we would not suggest anybody using them unless it was suggested by the Japanese authority. The risk is not there. If you have a stock and people still wish to be supplied with them, you may certainly let them have them, but we are not recommending that and it is most unlikely that you are going to need to use them.

[DF] If I could just add to that, the Embassy is still providing them to those who come in but we are obviously awaiting the outcome of that SAGE review and we’re keeping our own operation under review so it may end anyway depending on how that comes out. Any other questions?

[Q] Could I just ask about the Iodine-131 that decayed? As a non-scientist, could you just explain why there is not new Iodine-131 being produced still within the core of the reactors, or in the spent fuel ponds that might then leak out into the ground or water or atmosphere now?

[HW] Very, very simply, iodine is only produced when a plant is in operation, when the actual reaction is going on in the middle of the core. So once that core has been stopped from producing energy to produce electricity, iodine 131 is not produced any more at all. So all the iodine 131 that is in the core will start decaying and therefore the amount of iodine 131 will go down.
JB At the start, if you remember, when the earthquake happened, the reactors in fact did shut down. So from the moment the reactors shut down, the level of iodine was decaying.

[DF] OK, we’ve got another question here I think?

[Q] Yes, actually two questions. Firstly, for people who are going up to the quake affected area, for example, for relief work, is the 80 km exclusion zone around Fukushima still in force? And secondly, we’ve heard reports about the dumping of contaminated water into the sea and the amounts dumped sounded alarmingly large, and are there implications for seafood and fish on a much wider scale, given that fish presumably don’t stay still in the ocean?

JB Yes, to answer your first question about the 80 km zone, we are going to be reviewing that at our very next SAGE meeting and providing advice on it. We have been monitoring the weather and assessing for various worst case scenarios what the likely dosage would be at different areas around the 80 km zone. We’re synthesizing those analyses now, and at our next SAGE meeting we will assess them and then we’ll provide advice in to COBR about whether it’s appropriate to continue with the 80 km zone or whether it can be reduced somewhat. So that’s work in progress. In terms of the radioactive brine or seawater that is actually being released into the ocean, they do seem very large volumes, but in fact in the context of the Pacific Ocean they are completely miniscule. So there is almost certainly a local area, but in a practical situation it is enormously unlikely that there would be significant contamination a substantial distance away. Basically, albeit the volumes sound really quite large in terms of what might fill a truck or a house, the Pacific Ocean is so enormous there won’t be anything. I’d like Hilary to add any comments on that.

[HW] Yes, I would just like to add the Japanese themselves are monitoring the fish and the food and are obviously banning the fish and the food in the local region round there so it should not be an issue for any nationals around the area.

[JM] Jill Mearer here. Can I just add that the units that the amount of radioactive material is measured in, the becquerel, is a tiny tiny unit. Each human being is emitting 4,000 becquerels of radiation just from the natural radiation, so you have to have lots and lots of millions and billions and even more noughts to get anything significant. And also there will be a dilution effect but the monitoring will double check on that and define any areas from which fishing is not appropriate.

[DF] OK thank you. Are there any more questions in this room for the moment? Perhaps others on the line want to ask a question? Any more questions from the other room in the Embassy perhaps?

We don’t have any.

[DF] No. OK, any more here? I think this is only natural with the change in the travel advice which is giving people some reassurance and the continuing telephone calls of this type have been very reassuring to people so you’ve probably answered everyone’s questions. But now’s your chance people, before we lose the experts.

[Q] …still interested in the quality of the water, drinking water…

[DF] I don’t know whether you could hear that Sir John? It’s about the quality of the drinking water. There was one day here where there was a particular warning about drinking water in Tokyo but only one day, and I think there is still just one village in the affected areas where drinking the local water is not allowed. I don’t know if you can say anything about drinking water?

JB Well I think the point that we made when we had this discussion previously is that the levels of radioactive iodine in the drinking water were a matter of concern at the time, but that the Japanese standards are actually much more stringent than we have in the UK and Europe, and because of the processes of the radioactive decay of the Iodine-131, we do not expect any issue of radioactive iodine in the drinking water. So the Japanese are monitoring it, if there is radioactive material in the drinking water they will detect and announce it, I don’t think this is an area of concern at the moment in Tokyo and areas a substantial distance outside the 80km zone. But within the 80km zone obviously there may be hot spots as Jill has already said, and, but I think that is very much a question of the monitoring on the ground.

[DF] OK, thank you. Any others? Everybody seems to be smiling here so, it doesn’t look as if we’ve got any more questions. One last chance if anybody wants to ask anything around the network? In which case I think we’re very grateful for you sparing the time quite early in your day in London, it’s just coming up to 8.00. So thanks very much for that, and as soon as we can possibly do so we’ll aim to get a transcript of this conversation on the internet as well.

JB David, thank you for that. I think I would just say that we will be having another SAGE meeting next week. And that we will be looking at some of these issues and will continue to monitor the situation. We do have the capability of monitoring, looking at the weather, looking at a worst case scenario and how that changes, looking at the radioactive decay, so we’re very much on the case on a pretty much full time basis. I think if we provide advice to COBR and if that advice indicates some further change in the travel regulations for example, some degree of relaxation of the 80 km zone is one such possibility, or a suggestion that actually you will need to continue to put out iodine tablets, we would be happy to come and answer questions and outline the reasons for that at that time. But the overall mood music is that things are getting better, the Japanese seem to be increasingly able to actually deal with what are really very difficult problems on the plant and the natural processes are on our side in the sense of radioactive decay. However, I would emphasise the situation is not over. There’s lots of uncertainty. But I think you know, there’s definitely, the direction of travel is comforting. Thank you.

[DF] Ok, we’ve just got one more question if you don’t mind?

[Q] Phil Robertson. There still seems to be quite a lot of seismic activity going on. Do you have any sense of when that might subside?

JB In terms of the seismic activity, what happens after a major earthquake like that, you do get, of course, aftershocks, but the size of those aftershocks tends to decay in a fairly well predicted manner. There will be variations around that. So we don’t, there’s no expectation from the geologists that there will be anything like the level of earthquake that you had initially, and any aftershocks will be decaying gradually with time. It is not possible really to say whether in fact there will be another large earthquake some time.

[DF] Ok, I suspect we ought to finish on that note then. Thank you very much again and we may speak to you in the future. Thanks very much.

Updates to this page

Published 2 May 2011