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Conversions / Safety Limits

Strontium Limits - Annual

Uranium for dummies

Radiation is very confusing, everyone has different units of measure.   There are lot's of opinions, and lots of highly motivated views by money and by the "love of science".   Those who understand nuclear "got off on it".

It took me about 4 hours to understand it, at least to sort out the conversions and the BS.

Conversion factors, and government set safety levels are all in here.   Also right at the top are data on neutron absorbers necessary to stop the ongoing nuclear reactions at Fukushima.  The absorbers will all melt unless you can also cool down the Blob.

I think I nailed it, and put it summary into a spreadsheet.   There are links and reference documents embedded right into the spreadsheet.   The link is to an Excel spreadsheet

OfficerDave noted this calculation. It is important to be able to quickly convert and tell what rad level are high and what are hype.

October 30, 2011 at 1:31 pm · Reply

(3.68 x 24 x 365)/1000 = 32.2 milli sieverts a year = 61.9% above mandatory evacuation level

Indeed that is the calc that brings it home.

A simpler calc for immediate consumption is to multiply the Micro per hour by 8, and that is a pretty good estimate of Milli-Sievert.

2 milli-sievert per year is damaging, why do 50% of us get cancer? But anything over 20 is serious stuff. And once it become internal emitters, you are pretty much screwed.

Radiation Units -

Sievert is a radiation exposure measurement; its Western counterpart terminology is the 'Rem.'

  1 Sievert (Sv) = 100 Rems

    1 Rem = 0.01 Sv

    1 milliSievert (mSv) = 100 milliRems (mRem)

    1 microSievert (uSv) = 100 microRems (uRem)

    1 milliRem = 0.01 milliSievert


  1. I read their section on radiation "limits" and conversions. What are you imagining when you see a radiation "limit"? So, for a nuclear worker, the yearly limit set by the NRC is 5 REM. And then the plant has an administrative limit and that is typically 2 REM. When you see "limit" what do you think? Are you imagining that this is the level in which things become dangerous? That, once you get over that limit, you are in danger?

    You know what a speed limit is, right? So what does that limit mean to you? Mostly it means that if you exceed it you will get a ticket. That is what it means in commercial nuclear too. That is why the plants have a lower administrative limit--because they will get a big ticket if they exceed the limit.

    When you were driving 80 in a 65 were you in danger? Probably not. But this is the LIMIT that somebody decided would be safe for you. It doesn't mean that if you go over it, you are in danger. It just means that feel we can reasonable assume that you are able to handle your car at 65 miles per hour. We feel you are very safe driving at this speed on the freeway.

    That is what a radiation dose limit is. It is just a number that somebody came up with to say, "We have no doubt that this amount of radiation will not harm you." That doesn't mean that going over it will harm you. It just means that is the number picked out to use as regulation. Like a speed limit. That is the number somebody picked out--could be 55, could be 70, could be no limit if you are on the autobahn.

    I see radiophobic people say, "this is x amount over the safety limit!!".There really isn't a "safety limit"--there are regulatory limits. A safety limit would imply that going over that amount is unsafe and that is not what a regulatory limit is saying. There is a number associated with deterministic effects--meaning a number (radiation dose) where you would see actual physical manifestations and that is very high and that is also an acute dose of radiation.

    1. Brenda thanks for your comments, and they make sense. The issue is, what is that safety limit and regulatory limit. With 66% of us getting cancer and health care being 20% of the whole economy, I don't think that anecdotal evidence says we have it right.

      And there is lots and lots of high power studies that show even low dose (4 mWv cumulative) is shown to cause cancer.

      awaiting your response, mahalo!

    2. Stock,

      I was a Naval Nuke. You don't sound like a nuclear professional.

      BTW you might want to look into cannabis if you need a cancer cure.

  2. What is the safety limit and regulatory limit? You are asking me what the NRC regulatory limit is for radiation exposure? For workers in the commercial nuclear power it is 5 REM a year. For the general public, dose from a nuclear power plant cannot exceed 100 milirem a year (.1 REM). There are other doses for pregnant workers and minors. These are the regulatory limits. This is not a "safety" limit. There is no implied safety factor at 5 REM--it is just the number that was picked.

  3. The thing about citing studies is you have to have criteria for what you consider to be an accurate study. Most of us don't have those kinds of skills. Studies involving people and low dose radiation are statistical studies--they take things like exposure, they come up with a number for how much dose the public or whoever got (understand, this is a very complicated thing as well and fraught with problems) and then it is compared to some pathology in the area--like diabetes or cancer or whatever. People get diabetes and cancer all the how does one parse out an increase in cancer or diabetes that is attributable to radiation? Think about how difficult this is.

    1. I call that the false argument of "its too difficult"

      PS I do have those skills, with a minor in probability and statistics.

  4. We have an increase in anencephaly in the mid Columbia valley. My friend can give me studies that says its pesticides in our farming community. Anti nuke people say its radiation. None of this makes sense to me. Folic acid deficiency is what causes these types of neural tube deficiencies. But why would we have an increase in them? Why would folic acid not be supplied in sufficient amounts here? Well, besides having a lot of farming and a lot of nuclear stuff, we have a lot of really big fat people. Some of the fattest in the US. Fat people don't absorb folic acid sufficiently.

    You can find studies that will make a correlation between anencephaly and radiation--because someobody can simply say--there is radiation there and there is anencephaly there. Solved. But correlation does not make causation. So, the study matters--the quality, the factors used, the method. Most of us are not able to discern a good study from a bad study.

    1. It takes a real "scientist" to ignore a preponderance of correlation, lol

    2. Microcephaly is a malformation associated with in utero exposed atomic bomb survivors and can be induced in mice by fetal exposure to ionizing radiation (IR). The pathogenesis of IR-induced microcephaly, however, has not been fully understood. Our analyses of high-coverage expression profiling (HiCEP) demonstrated that the abnormal spindle-like microcephaly associated gene (ASPM) was down-regulated in irradiated human diploid fibroblasts. ASPM was recently reported as the causative gene for MCPH-5, the most common type of congenital microcephaly in humans. Here, we show that the expression of the Aspm gene was significantly reduced by IR in various human and murine cells. Additionally, Aspm was found downregulated in the irradiated fetal mouse brain, particularly in the ventricular zones. A similar suppression was observed in the irradiated neurosphere cultures. This is the first report suggesting that the suppression of Aspm by IR could be the initial molecular target leading to the future microcephaly formation.

  5. You know that of that 66%--human papilloma virus has recently become responsible for nearly all of the cervical cancers, most of the throat cancers and rectal cancers. Turns out those cancers are sexually transmitted diseases. And we have a vaccine for HPV now. My daughter will not get cervical cancer. I used to think it was the toxins in tampons. I am still afraid of them. But its not--its a virus. People could have made a correlation between radiation and cervical cancer here, but it turns out that it is wrong. We know now what it is.

  6. TY, I didn't know that one. Since you seem such a good sport, I appreciate you weighing in on the chitin radiation link


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