Disclosures and disclaimers:
1. There is a mild conflict of interest when it comes to peaceful uses of nuclear energy, because I am training to become a nuclear medicine physician, and a part of my livelihood would depend upon functioning of ‘research’ nuclear reactors (which are much ‘smaller’ compared to nuclear power plants – the kind involved in Fukushima Daiichi station). So, any adverse opinion (informed or otherwise) against nuclear energy in general would tend to antagonize my career. [But of course, the other way of looking is that if I have chosen to enter and serve in this field with continual radiation exposure, I myself as well as several other well-informed people who work in nuclear energy related professions do not consider such an exposure alarming].
2. Though I hold a much better understanding of nuclear physics, related safety aspects, radiation biology, and effects on and interactions of ionizing radiation with the human body, etc. than the laypersons and some ‘opinion-makers’ I have encountered, I am not very knowledgeable about operation of nuclear reactors and how a nuclear disaster might unfold. Nor do I have great knowledge of the past nuclear ‘incidents’/’accidents’, viz., the much talked about Three Mile Island incident and Chernobyl nuclear explosion. So, whatever I write here is to be taken merely as personal opinion of a layperson and not some kind of authority over such matters. However, I will try my best to back up whatever I say with reason.
I had posted a comment in response to a blog post that was urging people to not spread rumors associated with Fukushima disaster (in this particular case, the suggestion that rains in Chennai would be radioactivity-laden and how one must try to prevent the consequent harms). So, I thought I would convert that comment into a blog post with some more inputs. Also, I was getting frustrated to see ill-informed people post sensational tweets on the matter. In addition, most of the coverage in the media has been such that only the seemingly frightening aspects of the Fukushima incidents have been highlighted. It goes without saying that as such nuclear energy has earned itself a very bad name, and with misinformation or selective dissemination of information, people would get further (unduly) frightened.
My understanding about the Fukushima events was largely built based on the following two articles:
1. What Happens During a Nuclear Meltdown? (click) by Scientific American. I also recommend readers to go through the comments section.
Another good article putting in perspective the various exposure rates is this – Fast Facts about Radiation from the Fukushima Daiichi Nuclear Reactors (click) by Scientific American.
One prominent feature of news related to Fukushima has been the assumption that any kind of exposure to ionizing radiation would have catastrophic consequences. Saying that “radiation will screw us” is almost as inane as saying “bacteria will screw us”. Bacteria come in many sizes and shape, some are even beneficial. A bacterial colony in petri dish would not be harmful, but even a single bacterium in the blood stream might divide, overwhelm the immune system and eventually cause lot of harm or even death. Similar is the case with ionizing radiation. Just like we cannot envisage a world without bacteria because of their near universal presence at least on the Earth’s crust, it is impossible to live without radiation ‘exposure’, because ionizing radiation is quite literally omnipresent. So, there is no such thing as ‘zero radiation exposure’, because there are many naturally occurring radioactive isotopes, and some of them had gone on to constitute the most primitive of organisms much before humans had evolved and had a chance to build the first nuclear reactor or test the first fission device. Hence, there is only such thing as ‘background radiation exposure’, and not all of it is because of human activities. So, how much a certain radiation exposure would harm the human body is determined by many factors:
1. The kind of ionizing radiation (and its ‘energy’, which would determine to an extent the penetration power of that particular kind of radiation).
2. The ‘dose’ of exposure. Also, how acute or protracted this exposure is would be an important factor. E.g. 500 ‘units’ of radiation if incident on a person within a few seconds could be lethal, but same dose taken over a few decades would do no discernible harm.
3. The route of exposure – largely classified into internal and external.
So, simply pointing out “there is this much/this many times radioactivity” does not convey much information with regard to the possible effects on health. So many people are talking in sensational terms like ‘radioactivity is 400 times the normal outside the reactors’ or ‘increased radioactivity found in Tokyo’. But the problem is few go one or few steps ahead and ask the right questions!
And those right questions would be:
1. Okay 400 times higher activity outside the reactor, but how much ‘outside’?
Remember, dose rates follow inverse-square law. If the distance increases by ten times, the dose rates would fall by hundred times. So, if activity is 400 times normal one meter outside the reactor, it would be 0.000001 times that just 1 km away! Which is truly insignificant.
2. Okay, radioactivity has been detected just outside the reactor, but what kind of emission is it?
If it is gamma emission then (depending on their energy) they can penetrate through the skin. If they are beta/alpha emissions, they would not be able to breach the dead layer of the skin. Though I must add here that if no active fission reactions would be occurring in the reactors (which they should not occur as the control rods had been dipped fully and had been able to ‘shut off’ the reactor), no alpha particles would be produced. Of course, if this radioactivity enters the body (through inhalation or ingestion – say because of contaminated water), then the beta emissions can cause some harm depending on the total ingested dose and the element ingested. However, people around the reactors have already been administered stable iodine, which will block the entry of (radioactive) iodine-131 into the thyroid, and thus not cause any significant harm. [The institute where I work has administered iodine-131 to over 8,500 patients for treatment of thyroid cancers and hyperthyroidism – no increased incidence of any kind of cancers, fetal malformations or infertility in the patients or in the employees has been found].
3. Okay, radioactivity has been found, but what are the half-lives of the isotopes getting leaked out of the reactors?
Most of the detected radioactivity is because of cesium-137 and iodine-131. Former is a relatively long-lived radioisotope, but is unlikely to be inhaled as it is a heavy metal. Moreover, its half life is long, which is bad, but which is also good, because longer the half-life, fewer the nuclear disintegrations that occur per unit time, lesser the number of ionizing particles/photons emitted per unit time, and which in turn means lower the ‘activity’ and lower the exposure rates arising out of cesium-137 decay. The last thing is good, because fewer the number of ionizing particles/photons emitted per unit time, lesser would be the chance of their interacting with nearby DNA (in the nuclei of cells), and which in turn would mean fewer mutations and lesser chance of cancer development (carcinogenesis). Iodine-131 has a half-life of 8 days. And thus any of iodine-131 released would become negligible in merely few months.
4. Okay, even if the radioactivity is found increased at far off places (like Tokyo), is that a bad thing? And how bad?
First of all, merely the presence of radioactivity in a region does not automatically cause cancers. Though, I must add here that the ‘model’ used by (IRCP) scientists currently to predict risk of cancers from radiation assumes that there is no level of ionizing radiation exposure below which risk of radiation-induced cancer would be zero. Also, this model assumes that the probability of cancer related deaths rises linearly with increased radiation dose. Meaning, if 10 units of radiation dose causes cancer related death in 1 out of 1,000 persons, then, 100 units of radiation dose would cause 10 cancer related deaths in the same population. These cancer and related deaths are known as ‘stochastic effects’ of radiation exposure and the model is called ‘linear non-threshold model’. However, the data was based largely on exposures from Hiroshima-Nagasaki bombings, which are not exactly reliable, because the exposure was lot more acute and intense as compared to what might result from recent events in Japan. In deed, in our daily life we keep on getting exposed to some level of radiation – in fact, some of it also enters our body through the food we eat, because there are ‘naturally occurring’ radioactive isotopes! So, in fact farther from the site of leak radioactivity is found we can be assured that with such large scale dispersion the radioactivity must have got ‘diluted’ and its actual amount in any geographical area would be too negligible to have any significant undesirable consequences.
I would also like to add that many of the radioisotopes found just outside the reactor must have been short-lived positron emitters because of sea water that was used for emergency cooling. The half-life of these positron emitters does not extend beyond one hour. So, in just 24 hours they would be almost completely eliminated. However, these positron emitters would have greatly contributed to the ‘400 times higher activity than normal found in Fukushima reactors’, and when their production stops, the activity would be reduced proportionately.
So taking all the above factors into consideration, I am tempted to conclude that except for those who are actually currently working *inside* the Fukushima Daiichi reactors, no civilian is at an increased risk for infertility, malformations in off spring or delayed cancer-induction. I will just not be able to comment upon similar risks for the radiation workers. Though, it is reported that one worker’s annual dose limit was exceeded by 10%. Let me try to put this in perspective. In India the annual dose limit for occupational radiation exposure is 20 milliSievert (mSv). This much exposure is expected to cause one cancer-related death in addition to thousand cancer-related deaths already taking place. E.g., if a town has a population of 1 million and if each year 1,000 cancer-related deaths occur with background exposure to ionizing radiation (~ 1-2 mSv) to each of the 1 million persons, then a 20 mSv exposure to each of the persons in the population would result in 1,001 cancer related deaths in a year (as against 1,000). Of course, the radiation exposure to the said worker must have been lot more acute than his/her getting it over a year, but if one goes by the above calculation, then if his/her baseline risk of dying of cancer was 20% (without radiation exposure), then now his her risk of dying because of cancer is 20.02% (with the above radiation exposure)!
There are other issues too with the idea of ‘radiation-caused’ cancer. One of the greatest issues is of attribution. How do we know that a certain instance of cancer is because of radiation exposure or because of passive cigarette smoke inhalation? Or even if it is because of ionizing radiation, it was because of exposure to background radiation or because of occupational exposure? So what scientists do here is to try to compare the incidence of certain cancers before a nuclear incident and after a nuclear incident. And if a particular kind of cancer’s incidence is found increased, then the excessive number of cases would be attributed to the said nuclear incident. However, the problem with such an approach is that it entails ‘active’ searching for cancer cases and because of which merely the detection of cancer cases would increase despite the actual incidence having remained unchanged. Despite these difficulties, even after Chernobyl disaster (which was much worse than Fukushima incident) all I could find was that perhaps, there were around 1,000 cases of cancer cases that could be attributed to the explosion. The corresponding figure according to Wikiepdia for Three Mile Island is ZERO! Number of cancer-related deaths attributed to Chernobyl disaster (according to Wikipedia) are 10 (ten). So I was flabbergasted when a journalist called Praful Bidwai in an interview on Times NOW said that Chernobyl disaster had resulted in 35,000 cancer related deaths. This figure is seriously unheard of (by me, at least). It is unfortunate that he was not questioned by the host as to what the source of his information was.
Though, not all is hunky dory with Fukushima in particular and nuclear energy in general. The greatest problem is that the immediate area (perhaps of few kilometers radius) would remain uninhabitable for next few decades because of increased background radiation. And this is a significant loss because land is a valuable resource.
Another serious issue with production of energy in nuclear power plants is of waste disposal. However, a Wikipedia article (click) had given me this startling piece of information:
In countries with nuclear power, radioactive wastes comprise less than 1% of total industrial toxic wastes, much of which remains hazardous indefinitely. Overall, nuclear power produces far less waste material by volume than fossil-fuel based power plants. Coal-burning plants are particularly noted for producing large amounts of toxic and mildly radioactive ash due to concentrating naturally occurring metals and mildly radioactive material from the coal. A recent report from Oak Ridge National Laboratory concludes that coal power actually results in more radioactivity being released into the environment than nuclear power operation, and that the population effective dose equivalent from radiation from coal plants is 100 times as much as from ideal operation of nuclear plants. Indeed, coal ash is much less radioactive than nuclear waste, but ash is released directly into the environment, whereas nuclear plants use shielding to protect the environment from the irradiated reactor vessel, fuel rods, and any radioactive waste on site.
Given the number of variables involved, of course, what would be the role of nuclear energy in future is a very complex subject, but at least I would very much like journalists/activists/environmentalists to stop using rhetoric, the media to not abuse information they become privy to, and people to try to build *informed* opinion.
What I very strongly want people to stop assuming is that “just about any kind of radioactive exposure will kill me/cause me cancer/will render me sterile/will cause malformations in my children”.
PS: I have deliberately not provided too many links, nor gone too much into technical details. But I would be glad to answer any queries by readers regarding radioactivity that I would be capable of answering. 🙂
PPS: Thanks to @keshda – a fellow tweeter for the encouragement he provided for me to blog on this topic.