Last updated on March 1, 2013
11:20(CET)/09:20(UTC)/18:20
NISA has increased the level of the Fukushima accident to 7 on the INES scale, 7 is the highest level on the scale. Before Fukushima only Chernobyl was on that level, the descriptions of levels 5, 6 and 7 are these
Level 7.
- Major release of radio active material with widespread health and environmental effects requiring implementation of planned and extended countermeasures
Level 6.
- Significant release of radioactive material likely to require implementation of planned countermeasures.
Level 5.
- Limited release of radioactive material likely to require implementation of some planned countermeasures.
- Several deaths from radiation.
- Severe damage to reactor core.
- Release of large quantities of radioactive material within an installation with a high probability of significant public exposure. This could arise from a major criticality accident or fire.
The levels are as you can see quite loosely defined. We have been expecting it to be be increased from 5 but it has not been clear if it was gonna end as a 6 or a 7. Up until today Fukushima was a 5 on the scale due to the severe core damage(any one of the items on the list for INES 5 is enough by itself to classify it as a 5). Now NISA has upgraded it due to the large releases of radioactive material, even though there is yet no assumption that the release will lead to large scale health effect.
World Nuclear News has published a map from IAEA of the fallout from Fukushima (attached at the end) and writes this about how much radioactive materials has been released in total.
“As a result of re-evaluation, total amount of discharged iodine-131 is estimated at 1.3×1017 becquerels, and caesium-137 is estimated at 6.1×1015 becquerels. Hence the Nuclear and Industrial Safety Agency has concluded that the rating of the accident would be equivalent of Level 7.”
One can see from the map that the majority of fallout has landed in a limited area, it remains to be seen how large parts of that area wont be fit for agriculture anymore.
Chernobyl released 17.6*1017 Bq of I-131 and 85*1015 Bq of Cs-137, so compared to Chernobyl we are looking at around 10% of release of the volatile fission products.
However TEPCO also announced today that the total amount of radioactive material released might exceed that of Chernobyl if they can not stop the leakage of radioactive water. It is good to keep in mind though that this release is going into the sea where it will quite quickly dilute, in Chernobyl everything went into the air and then could be spread over farmland, cities etc. Anything going into the sea will have very limited, if any, health impact.
Chief cabinet secretary Edano made this statement about the INES level.
“The change in the level reminds us the accident is very big. What’s different here from the Chernobyl accident is that we have not yet seen a direct impact on the health of the people as a result of the nuclear accident. The accident itself is big, but we will make, as our first priority, our utmost effort to avoid any health impact on the people.”
This statement is very important and it highlights a fact that media now seems to neglect, the raising of the INES level is due to the total amount of radioactivity released (most if it was released during the first week), not due to expected or already occurring health consequences. So far the Fukushima accident has not killed a single person and it seems unlikely the radiation dosages to the public have been so large that they can cause any significant(i.e detectable) increase in cancer rates. The increase on the INES scale doesn’t mean the situation has turned dramatically worse, it is just a raising of the level due to the high releases that occurred initially.
The Neutron Economy has a very good blog post, Fukushima Daiichi to INES Level 7 – Some Numbers on Why, about the INES rating, Fukushima and eventual consequences if one applies the Linear No Threshold model of the risk of radiation exposure.
Links(English)
CNBC Nuclear Power Fears at New Heights Despite Safety, Viability
World Nuclear News Fukushima moved to Level 7
CNN Japan nuclear disaster tops scale
BBC Fukushima: What happened – and what needs to be done
Reuters Japan raises nuclear crisis to same level as Chernobyl
Blogs(English)
NEI Nuclear Notes “Years of Unchallenged Mythology”
Depleted Cranium On the Ground Pictures of Fukushima
Atomic Insights As Fukushima gets moved from 5 to 7 remember that 0 (deaths) is still an applicable number
Idaho Samizdat Fukushima accident rating from 5 to 7 on INES?
Atomic Power Review Fukushima Accident: Level 7.
Atomic Power Review Level change note…
Atomic Power Review APRA Special: Observations on Fukushima Daiichi
Links(Swedish)
SvD Fukushima inte lika allvarligt som Tjernobyl
Aftonbladet Lika allvarligt som Tjernobyl
Expressen Japan skakat av nya skalv idag
SvD Japan uppgraderar kärnkrafthaveriet
DN Fukushimaolyckan på Tjernobyl-nivå
Blogs(Swedish)
Röda Malmö Vidden av katastrofen växer
APSO sverige Spridningen av Cesium 137
Blott sverige svenska preppers har Fukushima på samma nivå som Tjernobyl
Den svenska argus Sjuan kom
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“So far the Fukushima accident has not killed a single person”
I believe 2 workers were found dead within one of the reactor buildings, so your statement is not entirily true.
Well… true… they were killed by the tsunami… and one crane worker died at Fukushima Dai-ini when the earthquake struck.
But…
…for crying out loud, there was a 9.0 earthquake and a 14 meter tsunami! That’s what killed them. Are we going to put those deaths on the account of the nuclear accident?
Three years ago a contractor at the Oskarshamn Nuclear Power Plant died during a revision when an industrial scale bolt-tightener suffered a catastrophic failure and ejected parts which struck the unfortunate fellow. Shall we regard that as a “nuclear accident”?
…some people will…..
As Michael writes those deaths where unrelated to the following events at the plant. They where not killed by any event related to the failure of the reactors. Rather they where immediate killed when the tsunami struck. Tragic nonetheless.
Radioactive strontium detected more than 30 km from Fukushima plant
TOKYO, April 12, Kyodo
Minute amounts of radioactive strontium have been detected in soil and plants in Fukushima Prefecture beyond the 30-kilometer zone around the crippled Fukushima Daiichi Nuclear Power Station, the science ministry said Tuesday.
It is the first time that radioactive strontium has been detected since the Fukushima plant began leaking radioactive substances after it was severely damaged by the March 11 earthquake and tsunami.
There is no safety limit set by the government for exposure to strontium, but the amount found so far is extremely low and does not pose a threat to human health, the Education, Culture, Sports, Science and Technology said.
Experts, however, expressed concern that the accumulation of strontium could have adverse health effects. When strontium enters the human body, it tends to accumulate in bones and is believed to cause bone cancer and leukemia.
Samples of soil and plants were taken March 16 to 19 from a number of locations in Fukushima Prefecture.
http://english.kyodonews.jp/news/2011/04/85002.html
Jaha…
…och?
So, where do you find a good estimate of the collective dose, and collective dose commitments for Fukushima?
Regarding whether LNT is a good model or not, see:
“Cancer risks attributable to low doses of ionizing radiation: Assessing what we really know” David J. Brenner, Richard Doll, et alia.
http://www.pnas.org/content/100/24/13761.full
I especially like: “Above doses of 50–100 mSv (protracted exposure) or 10–50 mSv (acute exposure), direct epidemiological evidence from human populations demonstrates that exposure to ionizing radiation increases the risk of some cancers. ”
There is no compelling biophysical reason for the damage to be zero, at doses just below doses shown to be damaging.
There is no compelling biophysical reason for the damage to be zero, at doses just below doses shown to be damaging.
Actually there is: DNA repair.
DNA damage, due to environmental factors and normal metabolic processes inside the cell, occurs at a rate of 1,000 to 1,000,000 molecular lesions per cell per day.
To make a simple analog: if I were to take a gun, and go shoot one shot at your car every now and again, you would be able to repair it and it would still function fine.
If I were to do this however…
This is why dose rates are so important, and if you look at the quote you gave… “Above doses of 50–100 mSv (protracted exposure) or 10–50 mSv (acute exposure)” …you see this very principle in action.
“To make a simple analog: if I were to take a gun, and go shoot one shot at your car every now and again, you would be able to repair it and it would still function fine.”
Not so simple Mr. Karnerfors as it would depend on where the bullet hit the car. If the car explodes or catches fire because of a bullet hit the tank then most people would not bother repairing their car.
True. But then you also have to factor in that “environmental factors and normal metabolic processes” are also taking shots at the car at the same time, and at a rate that may be much higher than what I’m doing.
So it’s not until the shots I’m taking are numerous enough to be noticable above all the others that it’s meaningful to start talking about an added risk my shots are causing.
Also you have to factor in synergy effects… such as hormesis.
http://en.wikipedia.org/wiki/Radiation_hormesis
Research from the Chernobyl Exclusion zone suggests this process may even be boosing the DNA repair in permanent residents (especially mice were looked at) of the area.
It’s a myth that a car explodes or catch fire by bullets. Exept in Hollywood.
From the article by David J. Brenner:
“1. Direct epidemiological evidence demonstrates that an organ dose of 10 mGy of diagnostic x-rays is associated with an increase in cancer risk (3, 16).
2. At an organ dose of 10 mGy of diagnostic x-rays, most irradiated cell nuclei will be traversed by one or, at most, a few physically distant electron tracks. Being so physically distant, it is very unlikely that these few electron tracks could produce DNA damage in some joint, cooperative way; rather, these electron tracks will act independently to produce stochastic damage and consequent cellular changes.
3. Decreasing the dose, say by a factor of 10, will simply result in proportionately fewer electron tracks and fewer hit cells. It follows that those fewer cells that are hit at the lower dose will be subject to (i) the same types of electron damage and (ii) the same radiobiological processes as would occur at 10 mGy.”
The car repair analogy does not hold, since the repair mechanisms are (IIRC) cell based.
I said it was a simple (or rather: simplified) analog. 🙂
And how else are you going to explain that different dose rates make for different odds ratios… that a protracted dose makes for less increase in risk than the same dose delivered acutely?
Thanks for the link, I will send it to some friends that know a lot more about the topic than I do.
My spontaneous remark is that one hasn’t seen any increase in cancer in areas of the world with high background radiation(70+ mSv). I think then one can question the papers conclusion that effects have been seen in the 50-100 mSv range for long term exposure.
There is also this case that I find very interesting.
http://www.jpands.org/vol9no1/chen.pdf
An extraordinary incident occurred 20 years ago in Taiwan.
Recycled steel, accidentally contaminated with cobalt-60 (half-life:
5.3 y), was formed into construction steel for more than 180
buildings, which 10,000 persons occupied for 9 to 20 years. They
unknowingly received radiation doses that averaged 0.4 Sva
collective dose of 4,000 person-Sv.
Based on the observed seven cancer deaths, the cancer
mortality rate for this population was assessed to be 3.5 per
100,000 person-years. Three children were born with congenital
heart malformations, indicating a prevalence rate of 1.5 cases per
1,000 children under age 19.
The average spontaneous cancer death rate in the general
population of Taiwan over these 20 years is 116 persons per
100,000 person-years. Based upon partial official statistics and
hospital experience, the prevalence rate of congenital
malformation is 23 cases per 1,000 children. Assuming the age and
income distributions of these persons are the same as for the
general population, it appears that significant beneficial health
effects may be associated with this chronic radiation exposure.
But radiation protection it’s not really my table except some very basic education in it. But I think when one is talking about dosages that are comparable to the normal background radiation, then there is a good argument for why it shouldn’t be dangerous.
I haven’t seen any good numbers on collective dose yet. If I find it, then it will be posted asap 🙂
From the discussion in the paper by W.L. Chen, et alia.
“Although it is a critical factor, the age distribution of the exposed population has not yet been determined”
Cancer is very much related to age, which imho makes the study very preliminary.
This population seems to be an _excellent_ subject for research though, so I really hope there are some well done articles.
About collective dose estimates: I checked with Strålsäkerhetsmyndigheten today, and they do not seem to know about any estimates so far.
I really hope there is enough air data collected, so you can do good studies when things quiet down a bit.
I agree, I think there are WAY to many assumptions in that paper to draw any conclusion. But it’s very interesting for sure. I will try and see if there are any follow ups.
This one might also be of interest to you, a joint report by the French academy of science and the French academy of medicine
http://inderscience.metapress.com/app/home/contribution.asp?referrer=parent&backto=issue,1,15;journal,22,27;linkingpublicationresults,1:110875,1
This conclusion against the validity of LNT is based on several types of data: 1. Epidemiology has not evidenced cancer excess in humans for doses below 100 mSv. 2. Experimental animal data have not evidenced a carcinogenic effect for doses below 100 mSv. Moreover, dose-effect relationships are very seldom linear; most of them are linear-quadratic or quadratic. A practical threshold or hormetic effects have been observed in a large number of experimental studies. 3. Radiobiology: LNT assumes that the genotoxic risk (per unit dose) is constant irrespective of dose and dose rate and thus that the efficacy of the two guardians of the genome, DNA repair and elimination by death of cells with DNA damage do not vary with dose and dose rate. This assumption is not consistent with a large number of recent radiobiological data, for example mutational effect and lethal effect vary (per unit dose). The second assumption is that a given DNA damage has the same probability of initiating a cancer irrespective of the number of other DNA damage in the same cell and in the neighbouring cells. This assumption is also non consistent with recent data and modern concepts of carcinogenesis in which the microenvironment and tissue disorganisation play an important role. The existence of a threshold dose in individuals or animals contaminated by radium or thorium shows that the irradiation of a cell surrounded by non-irradiated cells does not initiate carcinogenesis. It is the responsibility of the proponents of LNT to demonstrate the validity of these two assumptions in order to justify the use of LNT. The recent reports do not provide such demonstrations.
and Brenners rebutal
http://www.springerlink.com/content/0x73320354211606/
and more discussion about the biology
http://radiology.rsna.org/content/251/1/13.short
Dang, you beat me to it!
The authors of the paper you sent are a bunch of heavyweights in the field, so one is inclined to assume they have done the statistical analysis in a very proper way.
High background areas do hint however that there might be a threshold, other studies hints hormetic effects might exist, others hint the opposite. Only honest evaluation is that nobody knows for sure and as the authors state, we might never know.
Everyone of course favors different angles and I think the arguments for a threshold or even hormesis is quite strong.
I think at the end of the day it doesn’t really matter all that much if LNT is valid all the way down to 0 dose or not. Because the risk is so low anyway compared to the risk of anything else (what for instance is the risk due to the pollutants that was released in the refinery fires?).
Whenever one starts to calculate increases in cancer rates that are impossible to pick out statistically from the noise of normal cancer cases, then one is walking on sketchy ground imo.
I think the whole situation and question exist due to the fact that we can measure such insignificantly low levels of radiation. If other pollutants where that easily measurable one would have been forced to try and quantify the risk of minute exposure to them, but it seems like since they are not very detectable one brushes it under the carpet.
Temperatures rise at No.4 spent fuel storage pool
The Tokyo Electric Power Company, or TEPCO, says the water temperature in the spent fuel storage pool at the No. 4 reactor in the crippled Fukushima nuclear plant has risen to about 90 degrees Celsius. It fears the spent fuel rods may be damaged.
TEPCO took the temperature on Tuesday using an extending arm on a special vehicle. It found the temperature was much higher than the normal level of under 40 degrees.
To cool the fuel, TEPCO sprayed 195 tons of water for 6 hours on Wednesday morning.
The company thinks the pool’s water level was about 5 meters lower than normal, but 2 meters above the fuel rods.
TEPCO believes the water level is likely to rise by about one meter after the water spraying on Wednesday.
The company also believes temperatures rose after the loss of the reactor’s cooling system.
TEPCO says high levels of radiation at 84 millisieverts per hour were detected above the water surface, where radiation is rarely detected.
http://www3.nhk.or.jp/daily/english/13_35.html
Thank you for the the links Johan.
Sometimes it is actually good for you and other people, if you play the moralist card.
When you weight the evidence for and against harmful effects of low doses and low dose rates of ionizing radiation, you should look for the truth, and how to best model it.
If you are doing it in a really serious manner, it means you should make a systematic literature search, and a systematic review of what you have found.
Do not let your own or other peoples opinion about nuclear power or anything whatsoever lead you astray. Concentrate on the evidence, and the underlying science.
For what it is worth, I am pro nuclear power, since it looks like the combined costs (production costs + externalities) seem to be quite low compared to other energy sources and compared to not producing power. (Eg, not spending energy for ventilation has bad effects.)
Engineering facts don’t lie or sugar coat, so neither should you. The truth shall set you free.