I am in Oviedo, Spain, attending the International Conference on Coal Science & Technology. It’s good to reacquaint with friends and colleagues whom I have known for several decades. My conversations with friends from Japan and Germany, prompt me to write this post on the nuclear power after the Fukushima disaster.
The massive earthquake and the awesome tsunami it engendered wreaked a terrible havoc on the people in Japan, particularly those living in and around Fukushima. About 15,000 people lost their lives from the tsunami, and hundreds of thousand were rendered homeless. The Dai-ichi nuclear power plant shut down in response to the earthquake, but it needed power to keep water flowing around the fuel rods. Downed power lines meant that the plant could not receive power from plants elsewhere to keep the cooling water circulating, and since the tsunami had knocked out all the backup diesel generators, the plant had only a few hours of power from its batteries, not long enough to restore power connection. Bad things happen to the light water reactors when the coolant is lost, and the Dai-ichi plant experienced a series of those: at least partial meltdown of the fuel rods, generation of hydrogen from steam reacting with hot metal, venting of gas pressure in primary containment to keep it from blowing, build up of hydrogen in the secondary containment, hydrogen explosion and release of radioactive materials.
The Scale of the Disaster
Each day brought news of a worsening situation. As events unfolded, comparisons were made with previous nuclear accidents. Initial reports placed this accident below or at the same level of severity as Three Mile Island, level 5 on the International Nuclear Events Scale (INES) scale. As more information became available, it was recognized that radiation released from the Dai-ichi plant was much larger and the incident was re-classified as a level 7 disaster; the same level as Chernobyl. It turns out that 7 is the highest rating on the INES scale.
By placing Chernobyl and Fukushima at the same level, we lose the value of the INES scale, which relates to radiation released and not its effect on people or environment. We need a different scale if to rate disasters. The situation is analogous to describing earthquake disasters using the Richter scale. The scale measures the energy released from the ground movement—not the effect it had on the structures and people. The 1989 earthquake in San Francisco registered a magnitude of 6.8 and caused the death of 63 people and rendered about 4,000 homeless. The Kobe earthquake of 1995, although of a similar magnitude registering 6.8 on the Richter scale, was much more devastating. It resulted in the death of about 6,400 people and rendered about 300,000 homeless.
At Fukushima the primary reinforced containment did not fail, and held back most of the radioactive materials. In the Chernobyl disaster there was no secondary containment, and when the only un-reinforced structure failed and particles from the core were dispersed into the environment by a large explosion. The cloud of radioactive materials was then dispersed by the wind over a large part of northern and western Europe. In the Chernobyl disaster nuclear material there were at least 47 fatalities from acute radiation, hundreds suffered radiation illness, and 600,000 people exposed to low-level radiation causing an estimated 4,000 additional cases of cancer (lower bound numbers). In the Fukushima incident there were explosions from hydrogen in the secondary containment structures, but they were not carrying core particles. To date there has been no fatality from acute radiation, although a few brave workers have suffered radiation illness.
Risk from Long-Tern Exposure to Low-Level Radiation
Understandably, there is much concern about the effect of low-level radiation on the people living around Fukushima. The fear of unknown is palpable, and parents are mistrustful of assurances by the government and industry spokespersons. Large areas were evacuated and radiation was detected in the food and water from that region. A friend of mine who lives in the neighboring Ibaraki prefecture wrote to me asking for help in locating a Geiger counter so he could check the radioactivity in the food and milk his family is getting. A quick check on eBay showed many vendors selling Geiger counters and radiation dosimeters, and many listed options for "shipping to Japan." Evidently my friend wasn’t the only one in Japan looking for this device.
I gained some perspective on the health risks of radiation while doing research for the Cubic Mile of Oil book. I hope this perspective will be of help to the readers. While there are health risks from radiation exposure, the anxiety about it also poses a health risk.
An acute exposure of 1 Sv is barely noticeable, above that, people suffer from radiation sickness manifesting in nausea and hair loss. LD50 of acute radiation is 3 Sv, and exposure to 10 Sv is generally lethal within a few days. The workers in Fukushima were in danger of suffering from acute radiation illnesses; fortunately, their exposure levels were monitored and managed, and as far as I know, none of them developed symptoms associated with acute radiation poisoning. The other concern from radiation is from long-term exposure to low levels, which can lead to cancer. This concern is the relevant one for the people living in Northern Japan. The consensus of health professional is that an exposure of 0.25 Sv (or 250 mSv) increases the chances of contracting cancer by 1%. This correlation is based on extrapolation of high-level exposure to very low levels, and does not allow for any self-correction or healing of the radiation damage by the body. It therefore serves as an upper bound to the risk.
We are constantly bombarded by radiation from all forms of natural (and man-made) sources. Living on earth entails exposure to about 3 to 4 mSv (milli Sieverts) per year, mostly from cosmic radiation and from rocks around us. Over a 100 years of lifespan, a person would have therefore been exposed to 300 mSv of radiation and that would increase the person's chances of contracting cancer by a little more than 1%. Now, cancer is a very common disease, and as such afflicts about 20% of the population.
I was looking at the radiation levels in the different prefectures of Japan at the Japan Times website. In Fukushima the levels are about 2.77 uSv (microSv) per hour, in Miyago and Ibaraki it is less than 0.1 uSv/hr and elsewhere about 0.05 uSv/hr. A steady exposure of 0.1 uSv/hr would over a year amount to a dose of 876 uSv or 0.88 mSv. Over a 100-year lifespan, this dose would add up to 88 mSv. Since 250 mSv increase the chance of contracting cancer by 1%, the dose of 88 mSv can be expected to increase the cancer risk for the individual by about 0.3%; from 20% to 20.3%.
There are a lot of statistics here, and I am aware that statistics offer little solace when one is considering health of near and dear ones. However, I sincerely hope, this information allays some of the concerns by placing the risks in perspective. Remember that anxiety is also deleterious to one’s health as it increases the risk of a cardiac illness.