Readings at the plant, taken at 10.20am, varied considerably. Edano told reporters that the highest level around one of the reactors was 400 millisieverts, with a reading of 100 millisieverts around another.
We\’ve moved from microsieverts to millisieverts and yes, we are now very definitely in the range which is dangerous to human health.
One nuclear worker who has commented around here says that his annual measured dosage is around 2 millisieverts.
Four points occur to me.
1) We are assuming that the difference between micro and milli hasn\’t got garbled somewhere along the line. I wouldn\’t put much weight on this but it\’s not impossible that it has.
2) Let\’s compare it to Chernobyl. There, right by the reactor, levels were (according to WikiP) 30,000 roentgens. 3,600 sieverts. There are one thousand milli sieverts to one sievert. So we\’ve perhaps reached 400/3,600,000 or roughly 1/1o,000 th of the level of Chernobyl radiation.
3) Dosage in a particular place and time is what matters to that person in that place and time. What matters to us as a whole is total dosage released. We have no information on this at present but it would be astonishing if there was as much as 1/10,000 th of Chernobyl released.
4) Finally, it depends hugely on what it actually is producing the radiation. If it\’s the hydrogen build up, which will contain N16, then this is a problem for those actually on the site. But for anyone more than a few hundred metres away it isn\’t: half life is about 5 seconds when it turns back into O16, that thing we all breathe all the time. If it\’s Cs 137 say, (a product of the actual fission process in the rods itself) then this will be around for a lot, lot, longer. And is thus more of a danger.
If the reports are true then this is worse than I thought it could be. And if the reports are true, the amounts of radiation are larger than we can make jokes about Banana Equivalent Doses about. But even assuming the reports are true it isn\’t as bad as some will paint it.
Stick with the 1/10,000 th of a Chernobyl for a moment.
Just one accident like Chernobyl can release 35 times as much radiation in 10 days as the total radioactive emissions from coal power plants on the entire planet Earth over the course of a century. The Chernobyl accident is estimated to have released 25–50 million curies (1–2 exabecquerels) (IAEA estimations), whereas the collective radioactivity resulting from all coal burning worldwide between 1937 and 2040 is estimated to be 2,700,000 curies or 0.101 EBq).
Call that century of coal emissions 10% of a Chernobyl. We are at 1,000 th of that. Maybe 6 weeks of what coal fired plants pump out all the time.
And that is assuming that what is coming out of Fukushima is long lived radionucleides, rather than that very short lived N16 etc.
More information needed, obviously.
“worse than I thought it could be” … yes indeed, me too. One is inclined to think that there is still a chain reaction occurring and that this is going to get much worse.
Has anybody got an real info on how quickly the residual activity should fall away after reactor shutdown?
“Ongoing chain reaction” – you heard it hear first.
Updates and explanations available here:
http://ansnuclearcafe.org/2011/03/11/media-updates-on-nuclear-power-stations-in-japan/
and here
http://bravenewclimate.com/2011/03/13/fukushima-simple-explanation/
and here
http://bravenewclimate.com/2011/03/15/fukushima-15-march-summary/
There is no ongoing chain reaction, the power plants shut down automatically as designed.
The tsunami knocked out all 6 banks of back up generators.
These were supposed to supply emergency power, to cool the reactors which still have intermediate fission material in them which needs to be cooled. They are now being cooled, and of course normal decay within the system will naturally decline so less heat is produced.
The likely outcome is as follows:
earthquake and tsunami kill 20,000. disease might kill some more.
2 workers die in industrial accidents during the emergency shutdown of three reactors.
Dozens of mostly very old nuclear reactors survive an earthquake seven times as strong as they were designed for.
Long term health effects and life expectancy of the local population will be roughly the equivalent of switching from cigarettes to roll-ups.
EU politicians will seek to shut down 40% of our generating capacity.
blokeinfrance – “Long term health effects and life expectancy of the local population will be roughly the equivalent of switching from cigarettes to roll-ups.”
Actually I would have thought that would be rather bad for you. More to the point, if Three Mile Island is anything to go by, the stress of the evacuation will probably cause more cancers than the accident itself.
“EU politicians will seek to shut down 40% of our generating capacity.”
Tools. But you’re right.
Latest press release suggests that tepco has had some success in controlling and releasing the reactors’ latent heat. No leaks from reactor PV to containment vessel have been measured. The problem with the design is that equipment does not seem specified to operate when hydrogen gas is present, hence the explosions while venting.
http://www.tepco.co.jp/en/press/corp-com/release/11031507-e.html
The other thing to remember is that Chernobyl itself was much hyped.
Nasty as the accident was, the predictions of millions of early deahs from cancer, three-headed babies and man-eating trees that glow in the dark have not been born out by reality.
Indeed according to one NatGeo* programme I saw, the exclusion zone around the plant is now a wildlife haven and the incidence of cancers and birth defects in the assorted bambies and wild boar that now roam the area are no higher than those seen elsewhere.
*An organisation that can hardly be called a nuclear industry apologist.
What blokeinfrance said.
If BraveNewClimate is right – and he appears to be a damn sight better informed and detailed than the MSM by many many orders of magnitude – then the 400 millisieverts is indeed a journalist not understanding the difference between milli- and micro-
That any journalist anywhere could report on anything at all without appreciating the difference between milli- and micro- is staggering. That a journalist reporting on anything remotely technical should do is a travesty and I would be looking for some sackings and resignations.
But even assuming the reports are true it isn’t as bad as some will paint it.
Maybe not. But
a) the situation is developing very quickly, things are by no means yet under control, and we still really don’t know how bad it’s going to get.
b) given that you prematurely jumped in to guarantee that the whole thing is no worse than eating a few bananas, I would suggest you’re not in much position to criticise other people’s hyperbole.
My bad – looks like it is 400mSv and not a journalist fouling up.
This may be more interesting as it had looked as though they were getting cooling back on line and the temps in the reactors below boiling point.
🙁
N.B. Radiation dose rates are the inverse square of the distance from the radiation source.
i.e. A dose rate of 400 millisieverts at say 10m from the reactor would be 100 millisieverts at 20m distant.
Let’s get some perspective here.
20,000 have probably died in the natural disaster, there are probably more than 200,000 displaced persons. Meanwhile 2 have died in the nuclear “meltdown”, 22 have been exposed to an overdose of radiation.
The burning oil refinery is probably producing more radiation than the nuclear plants, there’s usually a fair bit of radon in crude.
Gas pipelines are ruptured and will probably set off more fires.
The smell alone will hamper rescue efforts.
communications – rail, road, air, telecoms – are all down. So is the clean water and sewage system, presenting a major health risk.
Meanwhile a toxic cloud of ignorant bullshit has settled over Western Europe.
Who says there’s no fall-out?
Larry, you do have a point. It’s just so easy to kneejerk in this way because the Usual Suspects started shooting their mouths off from the get go. I’ve lost count of the number of times they’ve said primary containment has been breached. It didn’t happen in units 1 & 3 and so far it seems it hasn’t happened in unit 2 despite the damage. Let’s hope it stays that way.
exeng – “No leaks from reactor PV to containment vessel have been measured.”
Yeah but they have found caesium and iodine outside the reactor. The BWR does not have a secondary coolant loop – the water that runs through the core also runs through the power generators. So to say there has been no leak into the containment vessel is interesting when clearly radioactive waste has escaped the fuel elements, presumably going into the cooling water, hence escaping directly into the general environment. Without spending much time in the containment building itself. If any.
“The problem with the design is that equipment does not seem specified to operate when hydrogen gas is present, hence the explosions while venting.”
The bigger problem is where the hell the hydrogen came from. This is a big deal. At Chernobyl, which was also a steam/hydrogen explosion, it came from the reaction of steam with the graphite. It should not appear in a BWR. OK, radiation causes some production of hydrogen gas from the water but only in small amounts. If the hydrogen comes from a reaction of the zirconium metal from the fuel elements and water, this is a problem. It means the fuel elements have melted. Which we knew anyway given the escape of that caesium. But the size of the explosion suggests a lot of fuel elements have melted. This is actually a bit of a problem.
blokeinfrance – “Meanwhile 2 have died in the nuclear “meltdown”, 22 have been exposed to an overdose of radiation.”
By overdose you mean a larger than ideal dose, or a fatal dose? Careful with the language here.
Hydrogen can also be formed by the dissociation of water at high temperature.
I’ve lost count of the number of times they’ve said primary containment has been breached.
Yeah well. I’ve lost count of the number of times the Usual Suspects have told us everything is now under control, and anyway even the worst case scenario is no worse than eating a banana, and how could anyone be so stupid to think otherwise?
Whereas the fact is that the first wall of defense has indeed been damaged, possibly breached, as witnessed by a sudden drop in internal pressure to 1 atmosphere. Meanwhile cooling is still very difficult, and melting fuel-rods are on the cards. (The hint there is that injecting seawater is an absolutely last-ditch measure.)
I very much wish it was otherwise, but what we have is by any standards an extremely serious ongoing situation. And I don’t see how pretending everything is hunky-dory is any help to anyone.
(Disclaimer: I am not a pro or anti nuclear campaigner. I am worried about friends and family in Japan.)
Josh – “Hydrogen can also be formed by the dissociation of water at high temperature.”
I should have included that as well. Thank you. Yes, that is true. But at 2000 C what percentage of the water would have split? 1 or 2 percent? In a BWR that is quite a lot I suppose, but those were big explosions. I don’t know about the alloy used offhand, but Zirconium melts at a lower temperature than that. If temperatures got up around 3000 C I think they would have bigger problems than the hydrogen.
@2blokeinfrance – my question presupposes your answer.
I would expect the residual decay to fall off by the hour, yet some days after the reactors are still very hot.
“Ongoing chain reaction” .. you heard it here first.
Larry said: “b) given that you prematurely jumped in to guarantee that the whole thing is no worse than eating a few bananas, I would suggest you’re not in much position to criticise other people’s hyperbole.”
“guarantee that the whole thing is no worse than eating a few bananas”
“other people’s hyperbole.”
“guarantee”
“hyperbole”
The Banana Equivalent Dose is an easy way to reconcile the information available at that time with something people have ready knowledge and appreciation of.
Eating 20 bananas a day, every day is no small thing but it does put the radiation levels reported *at that time* into some kind of context.
Gareth, I appreciate that you’re an illiterate halfwit, but Tim was laying down the law with great confidence about “Absolutely the worst that could happen, absolutely the worst possible outcome”.
Yes, “guarantee”. Not “hyperbole”.
Whatever your opinions on the matter (no doubt they’re imbecilic), he now concedes that he was entirely wrong in that diagnosis. And I’m just pointing out that it puts in him in a rather awkward position if he’s going to start lambasting others when they start exaggerating on the basis of ignorance of the facts.
“What matters to us as a whole is total dosage released.”
What matters to us is commentators understand that a nuclear reactor dose not release a dosage, it produces radioactivity from decaying atoms measured in Becquerel.
The dose absorbed by a medium measured in Gray, is multiplied by weighted factors to take into account the composition of that medium, and thus if Human tissue to provide an estimation of biological effect, measured in Sievert, the so-called equivalent dose.
It is then a gauge of biological effect not radioactivity.
The decay will release gamma radiation to which the inverse square rule applies as mentioned elsewhere in the comments – which does not make anything radioactive or cause fall out.
A Medical X-ray machines when the tube is energised and generating X-rays can have the equivalent dose measured but this is meaningless with regard to risk to people walking about outside the hospital or on the next town, nor does it tell anything about the characteristics of the X-rays generated, their intensity or penetrating power.
Measurement of equivalent dose in the Japanese reactors is only of any relevance to anyone in the immediate proximity, in order to determine if it is safe to appraoch.
If one wears X-ray protection with a monitor beneath it, the equivalent dose at that monitor in Sievert will be lower than that received by a monitor on the outside of the protection.
So Sievert is not a direct measure of the radioactivity being produced in the core and can depend on where the monitoring is being done, the effectiveness of shielding, distance, and also any decay of material outside the core.
As a measure of general risk, it is meaningless.
Hmm. Perhaps Our Genial Host wasn’t so incorrect as some commenters would imply.
Try The Register.
Of course, rather than debate the words, you can join the debate with numbers, and buy Japanese equities from Guardian readers…..
When it comes down to it,all the special scientific pleading going on in this thread cannot disguise the fact that building nuclear reactors in an area prone to tsunamis is 1) dangerous and 2) a gigantic waste of money.All the claims to superior or at least more practicable knowledge
made by those having a scientific education are well busted by the latest events showing a lack of any sense of geography and history ,since the Bristol Channel and its hinterland including the sites of Hinkley Point and Oldbury nuclear power stations were devastated by a tsunami in 1607.Some small amount of humility on the part of scientists ,who have assumed a dominant influence in our culture, would not come amiss.
DBC Reed – “When it comes down to it,all the special scientific pleading going on in this thread”
What special scientific pleading? You mean facts?
“building nuclear reactors in an area prone to tsunamis is 1) dangerous”
Yes but the whole of Japan is an area prone to Tsunamis. They have to build them somewhere. Notice how well these reactors have actually coped as well.
“and 2) a gigantic waste of money.”
How is it a gigantic waste of money? These reactors have been quietly producing billions of dollars worth of power for about 40 years without much trouble. I expect TEPCO has made a fortune from them.
“since the Bristol Channel and its hinterland including the sites of Hinkley Point and Oldbury nuclear power stations were devastated by a tsunami in 1607.”
And the chances of them being hit by another is what precisely?
“Some small amount of humility on the part of scientists ,who have assumed a dominant influence in our culture, would not come amiss.”
And closer acquaintance with the real world from their critics would be nicer.
@smfs
A pleasingly retro argument from the era of the Two Cultures debate : only scientists deal with the real world.Yeah right.Very realistic to build nuclear power stations in a tsunami
-prone area.It’s not just tsunamis either: the Blayais nuclear power plant on the Gironde was inundated by an ordinary storm surge in 1999, causing no little panic.
The argument that all of Japan is liable to
tsunamis is preoposterous:if it were ,no nuclear power stations should be built anywhere in Japan which torpedoes the whole hooray for nuclear argument. As it is “in the real world” much of the country is above sea level, I believe.
You cannot get away from the fact that building nuclear reactors near the sea has been shown to be impractical, going on stupid.
Mary Shelley got the number of arrogant male scientists at the beginning of the scientific era: no amount of pretentious over-elaboration of detail is going to make up for the fact that the basic premise may be wrong.
DBC Reed, do you demand 100% safety from other means of energy production?
DBC Reed – “A pleasingly retro argument from the era of the Two Cultures debate : only scientists deal with the real world.”
It is interesting to see you take a conclusion that applies to you and extend it to all other people who are not scientists. It is possible to point out one person is a fool without even suggesting that everyone else with an Arts degree is as well.
“The argument that all of Japan is liable to
tsunamis is preoposterous:if it were ,no nuclear power stations should be built anywhere in Japan which torpedoes the whole hooray for nuclear argument.”
Well no it doesn’t. It means that people have to accept risks. Reasonable risks. These reactors have come through with few problems – the problems have been unrelated to the actual reactor. Sea water got into the diesel fuel.
“You cannot get away from the fact that building nuclear reactors near the sea has been shown to be impractical, going on stupid.”
I don’t need to because it is not true.
Microsieverts, millisieverts, sooner or later you’re talking real sieverts.