On Friday, April 10, 2014, a high-tech robot was sent inside the primary containment (PCV) of Fukushima Daiichi unit #1. The device had traversed more than two-thirds of its planned path when it became stuck. It would no longer move. The robot’s camera, radiation detector, and temperature monitor continued to fully function. But, after two days of trying to get the robot moving again, the operators decided to sever the connecting power cable and abandon it.

Now, here’s the problem. The robot recorded that the radiation level inside the PCV was 9.7 sieverts per hour. All but one of the Press outlets in Japan said that this would kill a human being in an hour. (1)  The clear implication being that if a person were in a radiation field of this magnitude for an hour, they would literally keel over dead. This is pure science fiction, most recently depicted in last fall’s movie Blackhat. In Blackhat, a person inside the high-exposure-level control room succumbs to the radiation in about 10 minutes.

It would never happen like that with the radiation levels depicted in the movie, and certainly not with those detected inside F. Daiichi unit #1’s PCV. If a person were on the 9.7 Sv/hr field for an hour, the exposure would certainly cause Acute Radiation Syndrome (ARS), and the person would possibly die. But, not on the spot!

ARS symptoms from this level of exposure would take time to manifest. In general, the symptoms would be (at ~10 Sievert exposure over a short period of time); nausea and vomiting beginning about an hour after exposure, diarrhea in 1-3 hours, headache in 1-2 hours, moderate to severe elevated body temperature (fever) in about an hour, and an onset of detectible nervous system dysfunction in less than 24 hours. Nearly all symptoms will literally disappear after a day or two, but resurface a few days later with more intensity. Without medical attention, death would take 2-4 weeks to occur.

But not all persons exposed to 10 Sieverts would die… some, perhaps, but not all. As the time needed to reach a potentially lethal exposure increases, our natural cellular and genetic repair mechanisms can significantly counteract the damage being experienced. Thus, an exposure that takes an hour to accumulate will have a much less potential for lethality than one that takes but a few minutes. Further, it is with exposures of 30 Sieverts or more over a short period of time where everyone would certainly die. A key point is that the lowest one-hour exposure that might cause a person to almost immediately swoon is in the 50-100 Sievert range.

The CDC explains that for ARS to occur the radiation dose must be high, the radiation be a type that penetrates (i.e. gamma or neutron), the entire body (or most of it) exposed, and the dose must be absorbed in a short period of time, typically within minutes. The CDC emphasizes that, “After the initial symptoms, a person usually looks and feels healthy for a period of time, after which he or she will become sick again.” In addition, the typical cause of death (if it occurs) would be destruction of enough bone marrow to allow severe infections and internal bleeding. (2)

In other words, a 9.7 Sievert exposure over the course of an hour would take at least a week for death to occur with some people, but it is not an absolute death sentence! Only one Japanese Press outlet (that I have found) got it right – Wall Street Journal’s Japan RealTime. It says, “…short-term exposure to 10 sieverts is enough to kill a person within a few weeks.” (3)

All of the above information could have been uncovered on the internet in less than an hour by any responsible journalist. It is not rocket science, per se. Thus, all of Japan’s Press could have easily, and correctly, reported the medical truth, however all but one failed to make the effort.

Clearly, the Japanese Press needs a good education on radiation; what it can do, and what it cannot. Having radiation-ignorant reporting will eventually cause loss of credibility with the Japanese public. In a country with millions upon millions who suffer radiophobia (mortal fear of radiation), it seems a moral imperative to relate such information correctly and not in a fashion that only proliferates science-fiction-based misinformation.


1. Radiation Levels Reach 9.7 Sieverts inside TEPCO N-Reactor; Jiji Press; 4/13/15. http://jen.jiji.com/jc/eng?g=eco&k=2015041300788 (a representative example from a relatively objective news outlet)

2. Acute Radiation Syndrome (ARS): A Fact Sheet for the Public; Center for Disease Control.  http://emergency.cdc.gov/radiation/ars.asp

3. What the Robot Saw: Images from Inside Fukushima Reactor; Japan RealTime, 4/14/15. http://blogs.wsj.com/japanrealtime/2015/04/14/what-the-robot-saw-images-from-inside-fukushima-reactor/