Off the Chart: 225 Sieverts per hour at Reactor No. 1 — Highest radiation dose yet measured

Published: May 30th, 2011 at 9:43 am ET


Radiation dose, Unit 1 nuclear power plant Hukushima,, May 29, 2011:

h/t Lucas Whitefield Hixson

Published: May 30th, 2011 at 9:43 am ET


Related Posts

  1. Highest radiation dose yet at Reactor No. 1 — 204 Sieverts per hour in drywell May 25, 2011
  2. Radiation dose spikes to 48 sieverts per hour at Reactor No. 1 — Highest level in months — Remained stable until 10-fold increase — Instrument failure? February 20, 2012
  3. “Highest radiation level since the start of the nuclear crisis”: 10 sieverts per hour measured outside between Reactors No. 1 and 2 August 1, 2011
  4. Highest Yet: Radiation inside Reactor No. 1 drywell rises to 250 Sieverts per hour June 4, 2011
  5. New indoor radiation dose record at Fukushima — 5 sieverts per hour detected at Reactor No. 1 — May be higher as it exceeded capacity of measuring device August 2, 2011

92 comments to Off the Chart: 225 Sieverts per hour at Reactor No. 1 — Highest radiation dose yet measured

  • radegan

    Not critical….critical….not critical….critical – the Blob is flashing!

    • SteveMT

      Refresher conversion information:

      Basic conversions:

      1 gray (Gy) = 100 rad
      1 rad = 10 milligray (mGy)
      1 sievert (Sv) = 1,000 millisieverts (mSv) = 1,000,000 microsieverts (μSv)
      1 sievert = 100 rem
      1 becquerel (Bq) = 1 count per second (cps)
      1 curie = 37,000,000,000 becquerel = 37 Gigabecquerels (GBq)

      For x-rays and gamma rays, 1 rad = 1 rem = 10 mSv
      For neutrons, 1 rad = 5 to 20 rem (depending on energy level) = 50-200 mSv
      For alpha radiation (helium-4 nuclei), 1 rad = 20 rem = 200 mSv

      • SteveMT

        More information about what these numbers mean [before they are changed or disappear]:

        Yearly dose examples:

        Maximum acceptable dose for the public from any man made facility: 1 mSv/year[15]

        Dose from living near a nuclear power station: 0.0001–0.01 mSv/year[9][11]

        Dose from living near a coal-fired power station: 0.0003 mSv/year[11]

        Dose from sleeping next to a human for 8 hours every night: 0.02 mSv/year[11]

        Dose from cosmic radiation (from sky) at sea level: 0.24 mSv/year[9]

        Dose from terrestrial radiation (from ground): 0.28 mSv/year[9]

        Dose from natural radiation in the human body: 0.40 mSv/year[9]

        Dose from standing in front of the granite of the United States Capitol building: 0.85 mSv/year[16]

        Average individual background radiation dose: 2 mSv/year; 1.5 mSv/year for Australians, 3.0 mSv/year for Americans[6][11][12]

        Dose from atmospheric sources (mostly radon): 2 mSv/year[9][17]

        Total average radiation dose for Americans: 6.2 mSv/year[18]

        New York-Tokyo flights for airline crew: 9 mSv/year[12]

        Dose from smoking 30 cigarettes a day: 13-60 mSv/year[16][17]

        Current average dose limit for nuclear workers: 20 mSv/year[12]

        Dose from background radiation in parts of Iran, India and Europe: 50 mSv/year[12]

        Dose limit applied to workers during Fukushima emergency: 250 mSv/year[19]

        Single dose examples:

        Dental radiography: 0.005 mSv[5]

        Average dose to people living within 16 km of Three Mile Island accident: 0.08 mSv during the accident[6]

        Mammogram — Single Exposure, Equipment Mean: 2 mSv[7]

        Mammogram — Procedural Mean, Equipment Variation: 4 mSv – 5 mSv[7]

        Brain CT scan: 0.8–5 mSv[8]
        Chest CT scan: 6–18 mSv[8]

      • Dr. Strangleglove

        The alpha radiation factor can be higher than 1000. The 20 figure is from the same source that brought you nukes in the first place.

  • Well I guess 225 is ok …. remember this:
    Japan detects radiation up to 700 milliserverts at Fukushima nuke plant

    TOKYO, May 9 (Xinhua) — Tokyo Electric Power Co. (TEPCO) on Monday detected radiation levels in the building housing the faltering No.1 reactor that far exceeded expected levels reaching as high as 700 millisieverts per hour, the utility firm said.

    The latest readings for the troubled reactor has lead Japan’s Nuclear and Industrial Safety Agency to embark on new radiation shielding measures so that work to bring the crisis under control can go ahead with risks of massive doses of deadly radiation poisoning hopefully being lessened for the TEPCO workers and their affiliates as they attempt to embark on a massive project to install a nuclear fuel cooling system ….

    • Of course its not okay … but is is 30% of May 9ths emmissions… good lord!

      • Fap

        225 sievert/h (= 225000 millisievert/h)

      • Judge H. O.

        I hate to be the bearer of unbearable news, but the current 225 Sv/hr reading in the drywell of reactor #1 is 32000% MORE than the May 9th reading. “Skyrocketed” is almost a minimalizing euphemism!

        • Oh yes, got my sieverts and millisieverts mixed up!

          Retraction – RUN FOR THE HILLS – IT IS NOT OK AT ALL!!

          Thanks for clarifying it for me!

          • SteveMT

            Guess what happens with 10 sieverts IN ONE DAY?…death!

            Symptoms of acute radiation (dose received within one day):[4]

            0 – 0.25 Sv (0 – 250 mSv): None

            0.25 – 1 Sv (250 – 1000 mSv): Some people feel nausea and loss of appetite; bone marrow, lymph nodes, spleen damaged.

            1 – 3 Sv (1000 – 3000 mSv): Mild to severe nausea, loss of appetite, infection; more severe bone marrow, lymph node, spleen damage; recovery probable, not assured.

            3 – 6 Sv (3000 – 6000 mSv): Severe nausea, loss of appetite; hemorrhaging, infection, diarrhea, peeling of skin, sterility; death if untreated.

            6 – 10 Sv (6000 – 10000 mSv): Above symptoms plus central nervous system impairment; death expected.

            Above 10 Sv (10000 mSv): Incapacitation and death.


    • Adam

      Please check your facts before posting B.S. on this bulletin board. You are comparing sieverts to millisieverts. This is ignorance at it’s greatest level. The current Millisievert releases are 225,000 Millisieverts per day. That’s a HUGE MAGNITUDE worse than the article you quote from may 7th. Get your facts straight or shut your piehole. Nobody needs to hear the senseless drivel that comes from uninformed people. get education then post something USEFUL.

  • Fap

    I still don’t understand why the reports of an instrument with “failure” are worth to be posted as news. The readings don’t seem to be reliable at all, or am i getting something wrong?

    • Judge H. O.

      Indeed, Fap. Without knowing failure modes of this instrument, we really can’t even make a guess which, if either, of the apparent two modes of detection are valid (the wiggly lower readings or the wiggly higher readings). Because both extremes are “wiggly” indicates operation, but radiation doesn’t come and go, so it’s one or the other or neither. Not very definitive, eh?

      • Fap

        Thanks, Judge.

        There are so many important (bad) news that i don’t think it’s very helpful to post these (worthless) readings. They may eventually discredit the whole website to be panic-mongering.

      • nyc

        Yeah, I could see a one-time jump from the 50s to the 200s, but it’s gone back and forth twice now, which doesn’t make much physical sense.

        • radegan

          Could be it’s flashing in and out of criticality – when it’s fissioning, the count is up.

      • It was also mentioned a few days back here that the data from is not reliable – best to the MEXT & TEPCO figures instead.

        Oddly, neither site is loading for me at present!

      • I wonder if you might be kind enough to give me some advice. I’m a Japanese Art dealer and have a long relationship with Japan. Was in Tokyo on March 11th and it was not a trip I will soon forget. I foolishly assumed that TEPCO had the situation under control and it would take time but booked to fly back to Tokyo on June 7th. Sent a note to a friend in Tsukuba a bit north of Tokyo and as the whole issue seemed to drop out of the news here I was startled to get her message back…please don’t go north of Tokyo…make your trip as quick as possible…the radiation readings in my garden are very high…the government is lying to us…
        I thought at first that she must be experiencing post traumatic stress but since finding a few websites including this one have come to realize that the situation at Fukushima is anything but under control My question is that given your knowledge and experience with what is going on there…would you avoid going to the Tokyo area and south of that or am I worrying excessively? Being a lay person and looking at material on the web it is really hard for me to get a sense of which way to go. Would greatly appreciate your advice.
        Thanks, Jeff

        • Jack

          Please Don’t Go at All.
          We may not have any air service at all by June 7, anyway.

        • I would say – stay away from Tokyo.

          I’ve heard about high readings south of Tokyo, but someone can correct me if they know differently.

        • pAnIc

          I live in the north, halfway between Tokyo and Tsukuba.

          I don’t think a short stay will harm you as an adult. The readings in Tsukuba are actually lower than where I am, but it depends on the location. I am measuring daily outside and there has not been an increase since end of March at our location.

          Anyway, chances are that you’ll pick up more rays in the plane than here on the ground, especially if you spend most of your time indoors where values are almost normal.

          Have a look at this map and you will see that Tsukuba (and Tokyo) are fairly low. Some areas of Chiba are quite high, but no problem for the short term.

          So I’d say keep an eye on the news and this website, but don’t panic. Perhaps it is a good time to be with your friend here in Japan, we all need it badly.

    • bla

      What I don’t understand is why does TEPCO even publish values from a failed instrument.
      Either the values have some merit and they publish or they are complete rubbish and they just post a blank value with comments stating the instrument (or channel) is out of order.

      BTW, the readings have apparently fallen to 41.8Sv/h … 😮

      • The readings are unreliable because the instruments are unreliable because their operatives are unreliable because their bosses are unreliable because the system under which they all struggle is unreliable because it doesn’t cater to worst case scenarios, only accountants diktats to maximise profit for the shareholders.

        Any reading above 5Sv means death within a short time, so the _stakeholders_ die, the equipment dies – everything dies except the radiation.

        It amazes me they’re still putting out any figures at all.

          • mikael

            And dont forgett, that its messured Pr/h against Pr/Year.
            Dont forgett that, a aparently low level, can within a months time, be lethal.

            And a contradiction.
            The radiation level cant, if its messured on a fixst location, jump up and down like that. Particulary, inside the plant. Because of the radiation decay is varying from days to years, and its not a linear scale, its exponential.

            So, correct me if I am wrong.

  • Jeremie

    Something I don’t understand is that it is the value inside the RPV, (or containment vessel?). So isn’t it obvious that it must be very high? (at least if the corium is still there). I guess the values are pretty high under normal conditions to. How much is it roughly while the reactor is working normaly? Does not matter if the radiation is very high there, if only it wouldn’t be leaking more and more.

  • tony wilson

    stop being so negative we fixed the cooling ponds in record time.
    full speed ahead on the nylon circus tents.
    8 or 9 months until cold storage shutdown and full decon conditions.
    in the mean time tourists are invited to the site,with complimentary fuky drink and snack.
    for afters a trip to the smoke and mirrors hot dripping tent to view the new hitlarious comedy movie films.
    honey i mutated the kids and the class of mutantfuky high.
    on your way out please donate coinage to are buy a bullet help kill a stray dog campaign.

  • Strange, the title of this article sounds hopeful, and it did explain that Angela Merkel is a scientist, but it did not explain why Merkel did her U-turn. I’m sure her decision had more to do with the possibility of an ELE (Extinction Level Event) than anything else.

    Nuclear power in Germany: The reasons behind Chancellor Merkel’s U-turn

    • Fap

      I think her reasons are quite obvious: Her actual coalition partner is extremely weak and she knows that it’s the only way for her to stay chancellor if she makes a coalition with the green party (which is incredible strong right now) possible. And the biggest barrier between Merkel’s party and the Greens in the past was their nuclear policy.

      • tigger

        Good for those Greens! I’m glad they don’t sit on their butts complaining, saying they can’t do anything about it–‘we’re screwed,’ etc. We so need their level of activism. Someone needs to light a fire under those in CA, for instance.

        Even if there’s only a small 3% chance that we can safely re-mediate this crisis, the world needs to uphold that solemn, constant duty and give it a 300% effort! We only need a 1% chance and successful execution… There is great honor and nobility in trying and failing. There is abhorrent dishonor in not even trying….

        • I agree.

          In the same way low levels of radiation can cause massive damage, low levels of support from millions of people can cause massive change.

          • Jack

            Sorry! SORRY! but NO FANTASIES NEEDED.
            “Charlie Brown, we are here in the Pumpkin Patch,
            and if We are Just SINCERE Enough, the GREAT PUMPKIN will come!
            Discretion is the Better Part of Valor.
            There are no Grand Solutions.
            This Planet is Toast.
            Read up about all the Prophecies which indicate
            this REALITY.
            Your Efforts should be toward Spiritual Understanding of this REALITY, and ATTUNING
            your Indivdual self, and your Kids to Christ.

          • Heart of the Rose

            I’m about patriotism.. not about clutching children..nevermind that ultimately it is about clutching children.

          • Heart of the Rose

            And yes Jack…we are toast.
            Scientific toast.

          • blackmoon


            I totally agree with your sentiments. And in that SPIRIT, check out this video:


        • tigger

          @ Jack,
          I too am deeply religious. As a result, my Faith would never allow me to abandon all hope and working toward a positive outcome. You cannot lose Faith. That’s surrendering to Satan… And you should not presume that you know the exact fate of the world–that’s blasphemy. Ultimately, the end only will be what each of us perceives and makes it to be.

        • Rica E

          Way to say it Tigger, here in Ca People have worked hard in the courts, local congresses, grassroots realms to put some of the best environmental law on the books in this country.(could be alot better) Yet the key method of change that made it all possible was ‘direct action’ , which is an effective way to augment other aspects of campaigns and empower oneself through ‘Doing’. A massive oil conglomerate bought a family owned holding of the last privately owned oldgrowth redwoods in nor cal. After years of pressure from a united consensus of poorly treated timber workers, enviro’s, global agencies, and alot of celebrity input, the company Maxxam fled the area. One of the main organizers was bombed by cointelpro and her trust won a huge settlement after her death a few years later. there is a movie coming out soon about the whole thing very inspiring and chilling. We have also successfully kept Mallwart out of a rather large radius of norcal! Check out the film End Civ that was recently released and see his theory about why educated people are rolling over on their backs unable to respond to our world . cheers!

          • Jack

            There in CA, You are about to LOSE! Everything!
            No future for the biggest welfare state in history.
            Back in ’86 they started closing the free clinics in
            CA because of Illegals. The Huge Initiative to Legalize
            pot turned out to mean nothing to the Police State
            Mafia. Efforts to Stop Diablo Canyon, Ditto…
            Get over yourselves with your “Direct Action!”
            I used to hang out with and write a little bit, and do
            Layout for the Free Venice Beachhead paper.
            It is fun to hang with like-minded people and talk
            about making things better.
            Then, what you see, is all the politically-correct
            Women giving us HO-bama, as if it was a VICTORY
            for all that is Good and Just. What a Crock!
            If You want to talk about FAITH, you need to gain
            some education about WHAT that really MEANS.
            “Faith” in your own Actions? You don’t know about
            Jesus Christ and all that is Taught about this here
            Lay not up your treasures where Moth and Rust doth Corrupt.

      • gimp

        Don’t forget the Election was done after Fukushima happened.

    • nyc

      Maybe her transition is the anti-event to George Monbiot’s transition event?

    • Pragmatist

      I’m sorry PU239, but, I don’t understand this obsession with the totally unsubstantiated ‘End of Life Event (ELE)’ concept as being the focus for abstaining from nuclear power. In my book something that has the potential to result in millions of casualties and to render large tracks of land uninhabitable for generations is BAD ENOUGH and reason enough. Last, there is plenty of evidence for the latter and none for the former.


    Routine radioactive emissions are dangerous because they are the main source of low-level radiation. Strong radiation comes from large accidents. Petkau discovered that the response is logarithmic to radiation, that means, concave downward. So the risk is higher at low doses of radiation than larger ones.

    The damage to the immune system due to low-level radiation can be controlled to some extent by measures that strengthen the immune system: antioxidant, vitamin C, vitamin E.

    The biochemical mechanisms by which the immune system is damaged, are different from the damage to the DNA caused by high radiation doses.

    If you have low-level radiation in addition to other mechanisms, the formation of free radicals by antioxidants such as vitamin C or E can be lifted.

    The only way to really deal with the problem of low-level radiation, is, as soon as possible to switch off any atomic reactor .


    [NOTE: I think this guy still has what we thought was a fake chart at the top of his page, but I wonder if this chart now becomes true, based on recent readings and developments. Otherwise, he does have a lot of citations and discussion on Petkau Effect and studies].

    Doses delivered slowly and continuously over extended periods of time, such as from the ingestion or inhalation of fission-products, are hundreds of times as damaging as short, high-intensity exposures at the same small total dose produced by a brief X-ray.

  • WindorSolarPlease

    Any radiations dosages, is not good.

    I think most of us believe that this is a very bad situation for many Countries.

    If you are not in a bunker with pre disaster food or in South America, you and your environment is going to get radiated with layers after layers of this.

    They have not been able to control Nuclear Power. The risk is to great, the damage of this power, is greater than any positive thing that they might have.
    They should shut them all down.

    Thank you to the people who have Geiger Counters and letting their findings be known.

    • WindorSolarPlease

      you and your environment is going to get radiated with layers after layers of this.

      It should be:
      you and your environment is already getting radiated with layers after layers of this.

      I hate to say this but, it is already here, and has been with us for awhile now.

  • Well, governments have admitted that we are getting [only] low levels of radiation, and CRIIRAD tells us we’re getting about 10 times what Europe is getting. They usually affix the word “only” before the word “low”. This, despite evidence that low levels of radiation around regular, normal, working nuclear plants causes an increase in leukemia and other cancers. About 50% of U.S. service personnel know about the effects of DU, and the rate of abnormalities and cancers in southern Iraq and other places is just abominable. Sperm counts of Israeli men down 40% in the last decade?

    I fear that Merkel, being a scientist, understands this, but Obama doesn’t. Law and Poli Sci courses will not get you that Phd in Nuclear Engineering – although it should give you enough information to be able to read a chart, a Petkau chart, say.

    [I read somewhere on the web (recently) that low level radiation damages cells and passes the damage along genetically, whereas high level radiation kills cells outright. I’ll try and find that article].


    Since the tragic accident at Chernobyl on April 26, 1986, there has been mounting evidence of far more severe effects of very small doses of radiation from nuclear fission products in the environment than had been predicted on the basis of studies of the survivors of Hiroshima and Nagasaki.

    And yet, scientists and government policy makers continue to ignore the seriousness of all releases of fission products into the environment; they’ve made no effort to end nuclear weapons production and testing, nor to phase out nuclear reactors, which regularly release “low-level” radioactivity into the air and water under normal operating conditions.
    Before we can convince Obama, we have to convince ourselves. Then, apply massive effort on government to stop this nonsense, convert the entire world to renewables and get on with our lives.

    If nuclear…

  • Lawnmowerman

    Ask yourself,what does it take in material,man hrs and heavy machinery and machineing of specific parts to put a 6 unit nuclear plant together in ideal conditions.

    Now ask yourself what would it take to fix buildings that exploded,then had melt downs,and are a mess of wires and pipes,cement slabs…all in deadly radiation,all in air suits and only able to work in minutes

    Anyone that has worked with metal or knows construction of large buildings,its not possable.

    Its like saying to you,in a day or two,the engines we pulled from the titanic on the bottom of the sea bed….will be up and running,just like new…doesnt work that way people.

    • Poor Daddy

      Well lawnmowerman, since you put it that way..(screams)..”WE BE FUCKED!!!”

    • Judge H. O.

      Once again, lawnmowerman, you’ve made a spot-on observation. Not only do metalworkers and machinists understand the analogies, anyone involved in any large-scale construction should get it too. The bottom-line is, I think, that what we’ve kept hearing from the authorities has been utter BS. Until that first hydrogen blast, I gave the benefit of doubt to spokespeople. It was downhill for trustworthiness after that.

    • Poor Daddy

      If YOU are being waterboarded, it IS torture.
      If you are doing the waterboarding, it becomes, in varying degrees, much more vague.
      The victors write history. “We do not torture, we use enhanced interrogation”…..and then only on “unlawful combatants”, never on prisoners of war. And we blissfully swim in a sea of semantic slime.
      Good guys wear white hats.

  • isnt that funny…
    It went up again… Exactly to where it’s plotted..

  • James Tekton

    May I ask, what is this HP forum?

    Please supply link if you could be so kind.

  • James Tekton

    Never mind, I just got it.

    Huffington Post! 🙂

  • Cassie

    I assumed they meant HuffPo too.
    But I could be wrong.

  • IS THIS POSSIBLE ? pls check it out

    UNIT 2

    RPV temperature (May 29 11:00)
    11157℃ at feed water line nozzle


    RPV temperature (May 23 11:00)
    112.5℃ at feed water line nozzle

  • Dr. Strangleglove

    The infant brain is sensitive to radiation. But don’t worry, few people actualy use them these days.

  • Major Domo

    Funny, I don’t see a Hat tip on Lucas Whitefield Hixson’s site, back to this news, reported here first by yours truly, a whole 9 minutes before lucas!


  • thanx bla, fancy them dropping a decimal like that……….

  • TEPCO Officially Decides to Decommission Units 1 to 4 at Fukushima
    Daiichi NPS, Scrapping Plans to Build Units 7 and 8

  • Lee

    Whats missing is most telling….. why no neutron readings? Since I-131 keeps being generated then odds are one of the melted cores are critical. Neutron flux is used to monitor reactor activity so there should be probes permanently mounted.

    • Judge H. O.

      Lee, I think you are being softly reserved. If you are aware of any process to create I-131 besides bombardment by fission-released neutrons, then do tell! 😉

      Clearly, the odds of ongoing criticalities are between 100% and 100%. The maintained Iodine-Cesium ratio corroborates what is indicated by high Iodine-131 readings alone. Ya know, it’s been so long since the earthquake and SCRAM activation that there should only be 0.09% of the original Iodine-131 left. I can’t imagine how huge a back-calculated original I-131 amount would have had to be, if we were to assume the reactor(s) were not going critical.

  • SteveMT

    NHK: Reactor #1 water: 2 million counts of cesium per cc.

    Tuesday, May 31, 2011 06:03 +0900 (JST)
    Tokyo Electric Power Company detected 2 million becquerels of radioactive cesium per cubic centimeter of water in the basement of the No. 1 reactor building.

    • bla

      That’s a big figure if correct!
      Imagine you hold a 33cl glass (a can of coke)of this water (do NOT drink, huh …), there would be 660 million atoms of cesium disintegrating every second, throwing gamma-ray at you
      It would need 1m of concrete to shield 🙁

  • RobD

    What happens if the corium eats it way to the water table, which is very close?

    Corium geyser + Hydrogen/Oxygen explosions?


  • Truth Teller


    You are purely a fucking disinormation troll from the TEPCO company intent on killing MILLIONS of Japanese and other citizns worldwide just to keep your shareprice and the market intact. Every human being in Japan needs to get the fuck out of there NOW. I you have kids and you stay in Japan then you are a fucking ignorant murdering bastard. LEAVE NOW.

    • ocifferdave

      If is having a slow article day (which has been known to happen) I have seen Anthony fill in the hours with lots of good article links/posts (I read them and they would be the kind of articles that enenews would link/post). Either you don’t like anthony messing up the sieverts/millisieverts thing (which is case in point why the media will post sieverts because it seems a lot less at first glance unless you catch the difference) or…your a gross booger eater. Yeah. (My wicked name calling is murderously plain.)

      • Jean Tanner

        Yes. I like Anrhony’s posted links and learn from them.
        I’d hate to see those sources dammed up!

  • ocifferdave

    Alex Jones has a respectable day job at PBS??! 😉

  • SteveMT

    500 meters from #1 & #2: 480 becquerels of radioactive strontium 90 per kilogram of soil. That’s about 100 times higher than the maximum reading recorded in Fukushima Prefecture following atmospheric nuclear tests carried out by foreign countries during the Cold War era.

    Looks like more fission occurring.