The British Chief Scientist’s estimate of Fukushima fallout zone

by nuclearhistory

BBC asks Beddington to describe what would happen if material was released from the reactors at Fukushima in meltdown:

Beddingon: “In that situation you would get an explosion and radioactive material would be emitted. But it would be emitted to about 500 metres and it would be a relatively short duration of the order of an hour or so. Compare that with Chernobyl…”

(BBC material rebroadcast by SBS TV Australia, 15 March 2011)

In the first instance, I compare it with the Taranaki feathers.


Am 241 readings, Taranaki. (Source: Burns et al, “Radioactive Contamination at Maralinga”, Australian Radiation Laboratory).



TOKYO (Kyodo) — The government has detected plutonium apparently from the crippled Fukushima Daiichi power plant outside the compound of the plant for the first time, science ministry officials said Friday.

The plutonium was detected at six locations in Fukushima Prefecture, including Iitate village around 45 kilometers northwest of the Fukushima complex, they said, adding the amounts were small and posed no danger to health.

The radioactive substance may have been carried by vapor or fine particles from the nuclear plant, said an official of Tokyo Electric Power Co., the operator of the plant.
A government map displaying radiation levels in the area around the Fukushima No. 1 Nuclear Power Plant.
A government map displaying radiation levels in the area around the Fukushima No. 1 Nuclear Power Plant.

Plutonium has an extremely long half-life and is associated with a high risk of cancer if it enters the human body by breathing or other means. As plutonium is heavy, it does not spread far.

The Ministry of Education, Culture, Sports, Science and Technology also detected radioactive strontium at various locations including one around 80 km from the plant.

(Mainichi Japan) October 1, 2011

Academic paper : Deposition of fission and activation products after the Fukushima Dai-ichi nuclear power plant accident

Deposition of fission and activation products after the Fukushima Dai-ichi nuclear power plant accident

Katsumi Shozugawaa, Corresponding author contact information, E-mail the corresponding author,
Norio Nogawab,
Motoyuki Matsuoa

a Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
b Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan

Received 22 August 2011. Revised 24 December 2011. Accepted 1 January 2012. Available online 20 January 2012.


The Great Eastern Japan Earthquake on March 11, 2011, damaged reactor cooling systems at Fukushima Dai-ichi nuclear power plant. The subsequent venting operation and hydrogen explosion resulted in a large radioactive nuclide emission from reactor containers into the environment. Here, we collected environmental samples such as soil, plant species, and water on April 10, 2011, in front of the power plant main gate as well as 35 km away in Iitate village, and observed gamma-rays with a Ge(Li) semiconductor detector. We observed activation products (239Np and 59Fe) and fission products (131I, 134Cs (133Cs), 137Cs, 110mAg (109Ag), 132Te, 132I, 140Ba, 140La, 91Sr, 91Y, 95Zr, and 95Nb). 239Np is the parent nuclide of 239Pu; 59Fe are presumably activation products of 58Fe obtained by corrosion of cooling pipes. The results show that these activation and fission products, diffused within a month of the accident. end quote

A bit more realistic than the old “Cesium and Iodine” garbage. For instance, heres Tony Jones trying to pull the answer to “What is in the clouds” (of fallout from Fukushima) from a head nuclear honcho (Imperial College, London) in March 2011:

Australian Broadcasting Corporation

Broadcast: 17/03/2011

Reporter: Tony Jones

TONY JONES, PRESENTER: Joining us from London to discuss the ongoing crisis at Fukushima nuclear plant is Professor Robin Grimes, the Director of the Imperial Centre for Nuclear Engineering, the Imperial College, London.

Thanks for joining us.


TONY JONES: And has your early optimism now been proven wrong about how well the Japanese were handling this crisis?

ROBIN GRIMES: Well I think the early optimism that the containment would manage to hold all the radiation in is definitely overconfident. There have been releases of radiation, particularly in the vicinity of reactor buildings, and that’s always a cause for concern.

TONY JONES: I mean, a few days ago you thought they were handling the event so well it was an endorsement of the safety of modern nuclear reactors. Have you changed your mind on that just to start with?

ROBIN GRIMES: Well, I mean, I want to really stress the difference between a modern nuclear reactor and this generation-one nuclear reactor. There are certain design features of this generation-one reactor which really would not be allowed, would actually never have passed muster anywhere else.

It’s really quite surprising in many ways. The generation-two reactors – and there are a number of them in the same region remember in Japan – have all performed very well, and in fact they’re back up and generating and many of them were back up and generating before the conventional power stations. It’s the specifics of this very old generation-one reactor.

TONY JONES: And what are the specifics? What are the things that worry you about its design? What is it that’s made it particularly vulnerable to this kind of accident?

ROBIN GRIMES: So there are two things that would not be able to pass a safety inspection for a new reactor at the moment and of them, one is the idea that they have this large condensing ring, this doughnut-shaped thing that we’ve been hearing about which is actually outside the containment vessel.

In a modern design, anything to do with a reactor in which the primary circuits are concerned would have to be within a very strong containment vessel. The containment vessels have actually done very well, despite the fact this is a 40-year-old reactor. It’s these doughnut-shaped exterior structure that seems to have failed in a couple of the cases to some extent. So that’s one thing.

The second thing is the arrangement of the spent fuel ponds, which are sort of – again in a sort of a doughnut at the top of the reactor. Having a very large mass and having the spent fuel very close to the reactor in that way is not something that we would do anymore. And in fact again, the generation-two type reactors are not built like that. And the kind of reactors that the world may be building in the future, generation-three reactors, are different even again from that.

TONY JONES: Is it clear how the water seems to have disappeared from these containment ponds which contain the fuel rods? Because that’s now what appears the biggest problem, and the Americans are saying the water has entirely boiled off in at least one of these pools in reactor four.

ROBIN GRIMES: Yeah, there are two very good points you’re making there. The first is that the Americans seem to be disagreeing with the Japanese. And so, I can’t see how this can be a matter of semantics. I mean, either there is some water or there isn’t some water.

How that water left, because certainly the Japanese are stating clearly that there is considerable water loss in number four. And I imagine that must be due to some earthquake damage, some cracking or something like that.

Now, in addition to that, because now the reactor’s uncovered and water’s not being replenished into those spent fuel tanks, then evaporation will be occurring, and the evaporation rate is a metre or so a day. I honestly don’t have the exact figure, but it’s of that order.

So after a few days, unless you replenish the tanks, the levels do start to go down. And if the water levels go down, then the temperature inside the tanks will go up.

TONY JONES: Because the fuel rods themselves generate heat and ultimately …


TONY JONES: … begin to melt and release radioactive isotopes into the atmosphere, is that right? And so the big question is: …

ROBIN GRIMES: That’s right. (breaks in)

TONY JONES: The big question is: how much of this material is in those tanks and how much could potentially be released into the atmosphere?

is this answering the question?
ROBIN GRIMES: Now, again, remember that these are 40-year-old tanks and they’ve had spent fuel in them for all of that time, or almost all of that time, so there will have been a build-up in the bottom of the tanks of small amounts of radioactive materials.

That would be due to the radiation affecting the sort of waters and things will have moved into the water, you know, dust particles and so forth. So, when you first start to get release of the water from those tanks, you would start to detect some of that radiation.

So, what we’ve been seeing, I think, is actually detection not necessarily of burst fuel rods initially, but actually of this sort of residual radiation that’s around the tanks anyway. Latterly we will almost certainly have seen the effects of the actual fuel pins themselves, which will have broken open, which will have become very distorted and so forth.

So, there are different types of radiation. That’s why it’s so crucial to keep watching, keep monitoring and find out not what the situation is at any one minute, but how that situation is changing with time. That tells you much more.

TONY JONES: Well there are incredibly high levels of radiation as we know above Reactor 4 and in fact above the whole complex. Now the helicopters can’t go anywhere near it so they have to drop water from a very long distance …

ROBIN GRIMES: That’s right.

TONY JONES: … up in the air. So if very high levels of radiation are being detected above the reactor, that means there’s a plume, does it not, and what’s in that plume? That’s what people want to know. Are they radioactive isotopes? Dangerous ones like iodine and caesium?

more avoiding the direct answer:
ROBIN GRIMES: Right. So again, remember you’ve got the water tanks now – the tops of the covers in number four has been blown off and now the water level’s dropped, which means the spent fuel has no longer got water on top of it.

Now the water actually has two jobs. It just – it doesn’t just cool the fuel, but it also acts as a radiation barrier. It turns our water is a really magnificent radiation barrier. So if there’s exposed fuel and it’s open to the atmosphere, then anything flying over the top of it will get radiation directly from the fuel rods, irrespective as to whether they’re broken or not.

TONY JONES: And just briefly – we’re nearly out of time, but what’s to stop that going into a very large cloud of dangerous radioactive isotopes that then descends on a major city like Tokyo?

ROBIN GRIMES: Ah, right, yeah, very good. Very good question. So there are two different ways in which radiation affects things. There’s like a, like turning on a torch, if you like, and if the fuel pins are exposed, it’s like a torch being turned on and the water level goes down. It’s like taking the cover off the torch and suddenly there’s a bright amount of radiation, and that’s called shine.

In addition to that, you’re absolutely right, some of those broken fuel rods will have given up some of their radioactive particles and those radioactive particles then go up into these plumes and they take the radiation inside the particles away from the site and that would include certain amounts of caesium and iodine.

The good news – if there is any good news – is that most of the iodine, in particular in the spent fuel, will have decayed away, because the spent fuel’s been in the ponds for quite a long time and radioactive iodine has a relatively shorter half life than many of the other fission products. But nevertheless, it is a concern.

TONY JONES: We’re nearly out of time, but I should say the bad news I imagine would be that it’s not only spent fuel rods in those ponds, but active fuel rods which were taken out for maintenance purposes, so, potentially there’s much higher levels of radioactive material in those ponds.

ROBIN GRIMES: No, those types of fuel rods, irrespective of whether they are spent or whether they’ve come out part of the way through their active useful life have the same – basically the same radiation coming from them. It’s pretty much the same stuff.

TONY JONES: OK. Robin Grimes, we thank you very much for taking the time to come and talk to us tonight.

ROBIN GRIMES: You’re very welcome. Thank you.