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Goods contamination by radiation

  1. Sep 14, 2011 #1
    Hello,

    Since the Fukushima incident I have wondered if goods manufactured in Japan could be contaminated by radiation. Before posting this thread I have found scattered mentions to this subject in Fukushima threads but I didn't find any clear conclusion on this. I hope not to question about something already discussed.

    I would like to know the chances that exports could be contaminated. I'm not talking about food, I'm considering also cars, watches, electronics, etc... is metal more likely to be contaminated? Are there radiation level controls on goods? are they reliable?

    Sorry about my ignorance on this subject...

    Thanks a lot,

    East River
     
  2. jcsd
  3. Sep 14, 2011 #2

    swl

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    The government falsely claims to have control of radiation levels of goods.
    Other than used car shipments being stopped in Russia, the only news I've read is in regard to contaminated agricultural produce.
    There are certainly many used cars contaminated with radiation, and I expect that, whole or in pieces, most of them will be exported.

    Geiger counters are cheap. Maybe you can stipulate 'no radioactive contamination' in your sales contracts.
     
  4. Sep 15, 2011 #3

    Drakkith

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    Do you have reliable references? I have a difficult time believing this. While no one can control 100% of radiation levels, claiming that the government has no control is flat out wrong.

    I feel compelled to point out the fact that we are surrounded by natural radiation every day of our lives. As such, there is effectively no way to enforce this "no radioactive contamination" policy, as a sensetive enough device will always detect some sort of radiation. Given the fact that different types of particles emit different types of radiation, I also don't believe a simple geiger counter would even be effective in the first place in detecting all contamination. Also it is exceedingly unlikely that any contamination would result in large increases in exposure compared to the background level.

    Many of these articles claiming to detect radiation in agriculture products are detecting levels so low that you can exceed those levels by flying in an aircraft.
     
  5. Sep 16, 2011 #4
    Government? Lying? Can't be! :D

    But it's kinda easy to detect that something is wrong when said device starts showing that gamma levels are increased by an order of magnitude near some goods, isn't it?

    Caesium is the most easily dispersed contamination, and it *is* a strong gamma emitter, so yes, "simple geiger counter" is a fairly effective at detecting contamination: anything contaminated with Sr-90 (pure beta), plutonium (alpha), etc will be surely also contaminated by Caesium and therefore will emit lots of gammas.

    You base this conclusion on what exactly?
     
  6. Sep 16, 2011 #5

    Drakkith

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    I could claim the reverse. Government telling mostly the truth?! Can't be!

    Only in severe contamination.

    Even if it is effective, the average person has absolutely no clue how to use a geiger counter correctly and would probably panic at any reading. I simply don't think that it would be an effective tool for the OP.

    Probability.
     
  7. Sep 16, 2011 #6
    x10 background level is not a *severe* contamination.

    IIRC, the *natural* variability of background radiation from place to place is about x3. The most naturally radioactive place on Earth in Ramsar, Iran, has natural background radiation one hundred times higher than average.
     
  8. Sep 16, 2011 #7
    Well, you might be right about it, as average person is, unfortunately, dumb.

    But one doesn't have to be a genius to be able to notice that counter usually shows N counts per minute, but when you bring it close to this particular Japanese car, it starts to show 10*N counts per minute.
     
  9. Sep 16, 2011 #8

    swl

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    Keep in mind that sampling of miniscule amounts of produce can only detect a miniscule amount of contaminated goods. The government claims it is too expensive and that they don’t have enough equipment for testing all of the food. In that case, I suppose even a statistically insignificant sampling plan is better than nothing.

    All links are in Japanese. I'm not aware of these issues being reported in the English MSM. Use google for a poor machine translation if you don't read Japanese.


    Radioactive beef eaten by children in school lunches at 296 schools over 12 prefectures of Japan. The sale and consumption of contaminated products is not limited to adult plant workers at dai ichi. Samples of the meat tested after consumption was suspended tested over 1200Bq/kg. The government claims that the amount of contamination is small and won’t affect the health of the children. FYI, at most public schools in Japan, consumption of entire school lunch is mandatory, and children are not permitted to bring their lunch from home.
    http://www.asahi.com/special/10005/TKY201108100664.html


    Ibaragi prefecture, located south of Fukushima prefecture, was contaminated by fallout from the meltdowns. An operation (farm?) in Ibaragi prefecture that grows sod (grass turf) sold their contaminated sod to a nursery school located in Akita prefecture. Neither the governments of Akita, Ibaragi nor Fukushima were able to prevent the shipment and planting of this contaminated sod at a distant nursery school. The silver lining to this radioactive cloud is that they were able to reduce radiation levels at the nursery school by digging up the contaminated sod and removing it.
    http://www.yomiuri.co.jp/e-japan/akita/news/20110907-OYT8T01135.htm? [Broken]


    Leaf compost sold by Cainz Home centers found with contamination over 14,000Bq/kg. The contaminated compost was sold to customers in Nagano prefecture and also used by children for planting flowers at public schools.
    http://www.pref.nagano.jp/nousei/nougi/hiryouhp/fuyoudo3.htm


    Contaminated beef exceeding 500Bq/kg was sold in 21 prefectures. Beef sold in Osaka measured as high as 4350Bq/kg and beef sold to, and stored in the home freezer of, a customer in Kochi prefecture measured 2710Bq/kg. Kochi and Osaka are both quite far from the Fukushima plant where the triple meltdowns occurred.
    http://www.yomiuri.co.jp/feature/20110316-866921/news/20110719-OYT1T00402.htm [Broken]

    There are plenty of other news reports regarding radioactive contamination in Japan. I encourage you to do your own research and let us know what news you find.
     
    Last edited by a moderator: May 5, 2017
  10. Sep 16, 2011 #9
    Keep in mind the Annual Limit of Intake (ALI) for Cs-137 is 100uCi (3.7 million Bq). This is the amount of radioactivity that would result in 1 year 5000mrem whole body or 50000mrem organ dose (whichever is more restrictive), so (after doing the math) a 1/4 pound hanburger has about 500Bq of Cs-137 (using the 4350 Bq/kg), which is about 700 urem WB or 7mrem organ dose - this is the accumulated dose over a whole year! That's not a lot of additional exposure.
     
    Last edited by a moderator: May 5, 2017
  11. Sep 17, 2011 #10

    swl

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    Thanks for letting me know that the food is safe with over 4000Bq/kg of cesium.
    Fascinating that the French would spend millions or billions of dollars to process nuclear waste containing only 17Bq/kg, when it's OK to eat [STRIKE]waste[/STRIKE] food containing over 4000Bq per kg. And the cost was not only dollars or francs, there were people injured and killed.

    Please share your expert guidance of what level of cesium contamination is acceptable, for the food I'm feeding my toddlers, in Bq/kg. My smallest boy weighs about 13kg.

    Thanks again for letting me know my family is safe. My wife and I had been worried.
     
  12. Sep 17, 2011 #11

    Borek

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    I don't remember reading they were processing nuclear waste. Yes, the explosion happened in the waste processing facility, yes, the were processing something - but calling it a waste doesn't automatically follow.

    17Bq/kg is less than the level of natural 40K radiation in the human body (activity of natural potassium in the 30Bq/g range, amount of potassium in the body in the 0.2% range, so 1 kg contains 2g of potassium, giving something like 60Bq/kg).

    My understanding is that what happened in France was just an industrial accident, not different from hundreds of others happening each year.
     
  13. Sep 17, 2011 #12
    I'm not an expert, but anyway.

    Human body naturally has about 50Bq per kg of activity. Natural variability of background radiation is so that in some places people have higher levels. I would guess activity of 200Bq/kg is not very rare, and ~5000 Bq/kg is the highest naturally occurring level.

    Therefore:

    Occasionally eating food with 5000 Bq/kg is not something which will kill me. Eating such food often should be avoided, though.

    I would consider food with activity 200 Bq/kg or below as "not contaminated".
     
  14. Sep 17, 2011 #13

    swl

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    But wait a minute, you only included the contamination from beef in your calculations. How much room does that leave for other goods such as vegetables, grains, and dairy products that are contaminated?

    Or even better, please tell me how many Becquerels you advise is safe to eat on a daily basis?
     
  15. Sep 17, 2011 #14

    Drakkith

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    Hrmmm, why do I sense much sarcasm in your posts?
     
  16. Sep 19, 2011 #15
    I never claimed it was safe. I claimed it was not a lot of additional exposure. The position of the NCRP. ICRP and regulatory agencies is that no additional exposure is 100% safe. However, the regulatory agencies do hold that the additional risk from a certain level of exposure is an acceptable risk.

    Please do not accuse of syaing things I did not say.
     
  17. Sep 21, 2011 #16

    swl

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    Please forgive me for misunderstand your assertion 4000Bq/kg is "not a lot of additional exposure" to mean safe. I hope you understand how a simple layman, such as myself, might misunderstand "not a lot" to be safe.

    Now that we've established that 4,000Bq/kg (weight of food) is not safe, can I ask a more important question?

    How many Bequerels per kg of body weight of Cesium is an "acceptable risk" to eat every day, for the life of a two year old child?
     
    Last edited: Sep 21, 2011
  18. Sep 22, 2011 #17
    From a regulatory standpoint, "acceptable risk" allows for a maximum of 100mrem per year whole body to a member of the public from licensed activities. In addition, doses to members of the public must be kept ALARA (As Low As reasonably Achievable). Note that this does not mean as low as possible. Generally (and very general), the NRC has previously said that any cost less than $1000 per person per rem per year is reasonable.

    This would equate to 2uCi. This is from internal deposition. Note that this is also the activity that is exempt from licensing, that is, you or I could buy it without a radioactive materials license.

    Again, there are some people who hold the opinion that no risk is acceptable.
     
  19. Sep 22, 2011 #18

    tsutsuji

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    All Becquerels are not equal. [STRIKE]The short-lived radioactive substances produce more harmful Becquerels than the long life ones.[/STRIKE] (*) The harm depends also on the exposure mode of the human body, whether through external exposure or through inhalation or ingestion. As the news report does not tell which substances were present in the furnace, it is not possible to elaborate much further. If the average radiation in the furnace is 17 Bq/kg, it could result of the mixing of 0.1% with 17,000 Bq/kg(*) with 99,9% with 0 Bq/kg. I guess in some cases only the surface of the materials processed is contaminated, while the inside is clean. Bq/kg is probably not a very useful unit when dealing with surface phenomenons.

    (*) Socodei's upper limit for waste acceptance seems to be 0.37 GBq/kg (370,000,000 Bq/kg) (the legal upper limit for "FMA-VC" mentioned at http://www.laradioactivite.com/fr/site/pages/DechetsFMAVC.htm ) (the legal upper limit for TFA is 100,000 Bq/kg: http://www.laradioactivite.com/fr/site/pages/DechetsTFA.htm )

    (*) edit: that part was wrong, as remarked below.
     
    Last edited: Sep 22, 2011
  20. Sep 22, 2011 #19

    Astronuc

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    I believe the "maximum of 100mrem per year whole body to a member of the public from licensed activities" applies to adults or folks 18 yrs and older. We had a cumulative dose number that started at 18. For those below 18, the cumulative dose was essentially zero.

    Pregnant women (actually, the fetus), infants and children are much more sensitive to effects of radiation because of the higher rate of mitosis.

    I'll try to find some better answers to swl's questions.
     
  21. Sep 22, 2011 #20

    Borek

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    While I agree Bq are not equivalent, as it depends on radiation type and energy, I don't see how it is related to the half life.
     
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