about radiation

Dear friends,

I am in Tokyo and came back from the US 2 days ago. I was shocked to see how media is sensationalizing the issue of Fukushima.

I told Don about this and he sent me the following email with good internet link.

Here is a good article Don sent me to read:


Below is his email:

In short (from the article)


This is the point at which the media confusion starts. Many stories concentrating on the reactor accidents were illustrated with blazing pictures of a natural gas plant explosion and a burning oil refinery, much more visually impressive than a building with the façade stripped off, but giving the false impression of a blazing inferno at the reactors.

Several headlines said “nuclear explosion,” which is something very different from “an explosion in a nuclear power plant.”

Anti-nuclear politicians like Congressman Ed Markey and anti-nuclear activists from groups like the Institute for Policy Studies warned ominously of “another Chernobyl” ― which this isn’t and never will be; the reactors are wildly, radically, different in design. (More on this below.)

Television talking heads talked about the “containment building.” Which is strictly true, since the building in which the containment is housed would be the “containment building” ― but misleading and confusing, because the containment for all three reactors remained intact.

So there’s the first bottom-line point: at least so far, the inner, steel, containment vessel on all three Fukushima reactors remains intact.



When the gases started to be released from the containment vessels, that meant there was some release of radiation. With their usual nuance, the media reported only that there was radiation released; since there was detectable radioactivity on the clothes and bodies of the men injured in the explosion - this erroneously got reported as “radiation poisoning,” even for the poor guy who had the heart attack.

But how much radiation was really released? There are several ways to measure radiation, but what we’re usually concerned with is the dose received ― that is, how much radiation has hit the body of someone who gets exposed. It can be thought of like sunburn ― if you’re out in strong sunlight for fifteen minutes, you are getting a “small dose” of sun; four hours, and you get a “big dose” and may get a sunburn.

In the U.S., this is usually measured as Roentgen, named for the discoverer of X-rays. (Strictly, it’s measured as “Roentgen absorbed dose” or rad, and the dose in humans is “Roentgen equivalent in man” or rem, but for our purposes it’s close enough to say 1 Roentgen = 1 rad, = 1 rem.) In the rest of the world, dose is measured in Sievert, with 100 Roentgen to 1 Sievert. A whole-body dose of 6 Sievert or 600 Roentgen is called the “LD 50/30 dose,” meaning that 50 percent of the people who get that dose will die within 30 days.

The highest dose rate ― that is, the dose received in a period of time ― that was observed around the Fukushima reactors was about 1015 microSeiverts per hour, but rapidly dropped to about 70 microSeiverts per hour. In other words, 0.001015 Sieverts per hour, or about 0.1 Roentgen per hour. The highest total body dose reported so far has been 106 milliSieverts, 0.106 Sieverts, or about 10 Roentgen. [this means that the highest Fukushima level - which was taken of a worker in the plant who is being constantly exposed (as opposed to a person many miles away) is still 60 times LESS than the dose that is considered seriously dangerous to about 50% of the people who get it].

What does this mean? Well, in the U.S., the average background [sunshine and other natural] radiation is around 7 milliSieverts (700 milli-Roentgen) a year; we here in Colorado nearly double that (more in some places, like Leadville) and some places have a background radiation of 50 times that or more.

So 1015 microSieverts is pretty significantly above normal background radiation, but that’s not the whole story either. By comparison, a CT scan exposes you to about 5 milliSieverts, 0.5 Roentgen; the total dose of the highest exposure reported has been about 20 CT scans. High altitude commercial flights have more radiation than normal background; 10 Roentgen [the highest recorded Fukushima body dose] is only about twice what a intercontinental flight attendant gets in a year.

Effects of radiation

There’s no question that the effects of big doses of radiation are pretty awful; various systems break down, you can’t absorb food ― in fact, vomiting and diarrhea are some of the first symptoms, along with hair loss ― and eventually, your immune system fails and you die as a result of massive infections, or hemorrhaging, or dehydration. These effects are known as acute radiation syndrome, ARS.

Low levels of radiation are another thing. Obviously, we all are exposed to some radiation because of the normal background. The usual model, based on the people affected in Hiroshima and Nagasaki, and later Chernobyl, is called a “linear dose response model,” and assumes that if a dose of 100 rem causes there to be 10 percent more deaths in a population, then a dose of 10 rem will mean 1 percent more, 1 rem about 1/10th of one percent more, and so on.

This is a conservative model, but it has a problem ― it predicts that places with high background radiation, like Colorado, will have higher cancer rates than places with low background radiation.

What really happens is exactly the opposite ― we in Colorado have a lower cancer rate than people at sea level.

Why this would happen is currently unknown, and in any case the rates of cancer are small enough it’s hard to be sure how much of it is due to normal radiation exposure anyway, but there’s certainly some reason to think that the linear dose-response model is too conservative, that some amount of radiation has no particular harmful effect.

What happens, though, is that the model affects how we think about radiation. Very small amounts of radiation are detectable ― it’s literally “shining a light” at us, begging to be detected. Following the linear dose response model, there are assumed to be health effects of very small radiation exposures, and that means the regulations require even very very small releases to be reported.

Another Chernobyl?

Still, what some people are saying is this is “another Chernobyl.” So let’s talk about Chernobyl for a minute. The accident at Chernobyl was the biggest reactor accident that’s well-known, although probably not the worst reactor accident of any kind. In the Chernobyl accident, a reactor of a radically different design, with a containment building but no containment vessel, overheated and exploded; most sources say the graphite that made up the bulk of the reactor core caught fire, although some sources say the graphite didn’t actually catch fire, combust, it just was very hot. According to the UN report, about 50 people died as a result of the accident, some of them dying from acute radiation syndrome. The highest exposure reported was about 16 Gray. 16 Gray dose is about 1600 Roentgen, 1600-1700 rem, or nearly three times the “lethal” dose. That’s 160 times as great as the worst dose reported from Fukushima.

What’s more, the Chernobyl fire distributed large amounts of radioactive material around ― including about 10 tons of the actual reactor core. Unlike the Fukushima reactors, Chernobyl had no containment vessel, so once it was burning it was open to the outside, and diffused easily through the atmosphere, eventually spreading across much of northern Europe and a good bit of western Asia.

At the time of the accident, there were many terrifying predictions of the long-term health effects of the radiation.

The UN investigated these effects, and reported on them, in 2005, 2008, and 2011. The report concludes that there may be as many as 4000 additional deaths total that can be attributed to the effects of Chernobyl, but that’s among all the deaths in one of the most densely populated parts of the world. In other words, the linear dose-response model predicts that perhaps one person in a million might die somewhat earlier than they would have otherwise. Statistically. But we can never know if the prediction is correct.

In fact, the 2005 report says that a much, much bigger effect on public health comes from the rumors and uncertainty:

Alongside radiation-induced deaths and diseases, the report labels the mental health impact of Chernobyl as “the largest public health problem created by the accident” and partially attributes this damaging psychological impact to a lack of accurate information. These problems manifest as negative self-assessments of health, belief in a shortened life expectancy, lack of initiative, and dependency on assistance from the state.

The fatalistic feeling of being doomed leads to passivity, as well as other more significant mental health issues; this is entirely due to poor information and uninformed alarmism.

[This article was written last week, and since then an additional radiation leak has occured in the pool of spent fuel rods that caught fire. but see below]


While I was asleep, there was a new and unhappy event at Fukushima Daiichi: stored spent fuel rods apparently caught fire. At least right now, this is considerably more exciting than the actual reactor problems. Here’s what the IAEA says:

As reported earlier, a 400 millisieverts (mSv) [0.4 sieverts or 4/10ths of a seivert / danger zone is 6 full sieverts] per hour radiation dose observed at Fukushima Daiichi occurred between units 3 and 4. This is a high dose-level value, but it is a local value at a single location and at a certain point in time. The IAEA continues to confirm the evolution and value of this dose rate. It should be noted that because of this detected value, non-indispensible staff was evacuated from the plant, in line with the Emergency Response Plan, and that the population around the plant is already evacuated.

As they say, that’s in one nasty spot in the plant, and unlike most of the radiation panic, this really is a kind of nasty dose. In the US, we more commonly do dose rates in “rem” ― Roentgen Equivalent Man ― and one rem is roughly 1/100 Sievert. So this is 40 rem/hr, and that’s not a neighborhood you want to be in a long time. 50 rem is about where you start seeing observable radiation changes, 100 rem in a short time will actually make you sick.

That being said, the dose rate at the gate of the Fukushima plant is this:

At 00:00 UTC on 15 March a dose rate of 11.9 millisieverts (mSv) per hour was observed. Six hours later, at 06:00 UTC on 15 March a dose rate of 0.6 millisieverts (mSv) per hour was observed.

That’s 1.2 rem/hr, going down to 0.06 rem/hr. [and remember that the dangerous dose in rem is 600!]

From the chart: http://xkcd.com/radiation/

This is a good chart for you to look at, now that you have the above background understanding to look at it. Besides the interesting fact that eating bananas and living in concrete buildings also causes us to absorb radiation (in addition to the "background radiation"of the sun & surrounding plant life):

The two highest doses measured - for a short period of time 50 miles NW of Fukushima was 3.6 mSV - about the same as one mammogram - which is about half of one CT scan. MOST of the surrounding areas did not even measure this much. Note, too, that the highest rate so far - that temporary 400mSV spike AT ONE SPECIFIC PART OF THE PLANT (but falling off from 400 to 12 mSV in the few meters from the plant to the plant hate...and then falling off in an hour from 12 to 6 from there) is at the rate that can sometimes cause SYMPTOMS, but is still 5 times lower than really bad radiation poisoning (2000 mSV) - and that levels of 10 times more (4 SV) can sometimes be still survivable with medical help (and that, remember, even at yet another 50% higher level - 6 SV - 50% of the people exposed survive.

Anyway, while too much radiation too soon can, indeed, cause many health problems (and at super-high enough levels, even death) - you can see that the numbers coming out of Fukushima - which are the numbers for THE PLANT ITSELF and not the surrounding countryside - so far are nothing like the cause for concern that the over-reaction in the States and China warrants. And if you keep that 6 SV (or 600 rad or rem) number in mind, and do the math on whatever future numbers that you do hear (milli = 1/1000ths and micro = 1/1,000,000th of a SV, rad or rem) you will be able to understand what is going on better than the stupid American press who ALWAYS want some new panic, fear, and "impending tragedy" to write about to sell papers and get TV viewers (and who made all this exact same fuss before at, eg, Three Mile Island, where the press covered it like the end of the wold was coming (literally!) - but ultimately not evn one person died, and years later - under A LOT of scientific study - it was determined that the incident -about the same level as Fukushima - led to NO increase in cancer or any other health problems, even within 10 miles of the plant.

So that's it, everyone! I hope this helps!












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