When people think of cataclysms reported by the media in their lifetimes, few would omit three accidents afflicting nuclear power plants. Three Mile Island is listed as a disaster in the index of the 2017 World Almanac, despite the fact that not a single person was harmed by that 1979 core meltdown, nor was there any private property damage. Far more unambiguously deserving of our cataclysm trophy is the fearsome 1986 Chernobyl event, which quickly killed forty-nine plant workers and early responders and is likely to eventually claim somewhere between four thousand and ten thousand cancer victims.
More recently, the vast majority would probably deem Japan’s 2011 Fukushima power plant accident a cataclysm, although it resulted in no radiation-induced deaths and the radiation exposure for people living in Fukushima was so small compared to background radiation that it may never be possible to find statistically significant evidence of cancer increases. One can reach half a dozen fatalities if one includes those who died during evacuation procedures or who died due to exacerbations of their medical conditions when they were forced to move from local hospitals.1
In the 2011 event sequence, it’s even harder to apply the cataclysm label to the Fukushima nuclear mishap when it’s compared to the far greater casualties caused by the precipitating earthquake and tsunami earlier that same day, or when it’s compared to the Banda Aceh tsunami seven years earlier, which claimed 230,000 lives.
Still, two of these three nuclear events involved explosions. All had near-light-speed runaway chain reactions. If rapid motion is necessary to meet our criteria for a cataclysm, such frenzy was abundantly present each time. Besides, they all possessed fear factors that were off the scale, which caused them to be widely perceived as cataclysms. But more than that, they decisively shaped global opinion in a way that effectively brought an end to widespread nuclear power plant construction, and with that went realistic hopes for an end to carbon emissions. How deeply this will ultimately affect the planet’s biosphere is not yet fully known.
When the twentieth century began, science was just realizing that the atom was not the smallest thing in nature, as had been believed since the ancient Greeks (who’d coined the word). The first subatomic particle, the electron, was theorized to exist in 1896 and discovered three years later. In the next three decades, physicists found the major components of every atom’s nucleus. There was the proton, a heavy particle, the number of which in a nucleus is solely responsible for that atom being, say, oxygen as opposed to, say, carbon. Then there was the neutron, which was even a bit more massive. The neutron lurks in every element except ordinary hydrogen. It gloms on to protons and other neutrons in the nucleus, held there solely because of a truly strange attractive property physicists named, in an exuberant moment of poetic license, “the strong force.”
Energy, lots of it, is released when an atom is altered, particularly if the strong force is thwarted. So in a massive element with hundreds of protons and neutrons, where the nuclear particles are barely hanging on, a chunk of the nucleus can spontaneously break off. If a neutron flies away, and if the surroundings are sufficiently crowded, it may crash into adjacent atoms and knock off a neutron or two there too. In no time (actually, a millionth of a second), you can have a billion trillion neutrons frantically flying and crashing, each emitting energy.
The emissions experienced by victims of radiation accidents amount to free neutrons flying through the body, which isn’t good for you, along with flashes of gamma rays, the most energetic form of electromagnetic radiation, which, similarly, no one would seek out as any sort of tonic. Gammas travel at light speed and will break apart atoms and molecules like a cue ball striking a rack of billiard balls. These are cataclysms of their own even if they lie in a realm too small for even microscopes to visualize.
A nuclear reactor is a place where breakups of heavy atoms like uranium-235 and plutonium-239 are encouraged, with energy released in the form of heat. The number after the element’s name is simply the total number of particles in the nucleus. For example—and bear with me if you remember all of this from high-school physics or chemistry—uranium is uranium because it has exactly 92 protons. It also usually has 146 neutrons clinging to its nucleus, making a total of 238 nucleons (protons plus neutrons). This nucleon inventory is why it’s called uranium-238, and there’s probably some of this material in the earth beneath your home. It’s rather unstable, so neutrons and even protons can spontaneously break off, though you wouldn’t want to sit around waiting for it to happen. Every four and a half billion years, half of the uranium in any sample will lose enough nucleons to decay to a stable form of lead.
If you’re in a hurry to see uranium break up, then you’ll want to play with a somewhat unusual form of it that makes up only 0.7 percent of Earth’s natural uranium inventory. This is uranium-235. It has the mandatory 92 protons so it can be called uranium, but it possesses only 143 neutrons. It is a particularly unstable atom. If hit with a stray neutron, it will cough up two of its own, and each of these will fly at nearly light speed into another atom of nearby uranium-235, which will in turn lose two neutrons, and such a geometric progression ensures that in short order, you’ve got neutrons flying everywhere.
Again, every element has an established number of protons in its nucleus. Hydrogen has one, oxygen has eight, carbon has six, and uranium has ninety-two. There’s usually a matching number of neutrons in the same nucleus, so an ordinary oxygen has eight neutrons and an ordinary carbon has six. But as we saw in chapter 3, some rarer forms of oxygen or carbon have a different number of neutrons. Each variety is called an isotope, and it’s labeled, as we’ve seen, by the total number of nucleons in its nucleus. So, staying with carbon a bit longer, its most common form is carbon-12 because it has six protons and six neutrons. But one of every trillion carbon atoms in the CO2 in the air you breathe has two extra neutrons, and this is carbon-14. Such rarer isotopes are often unstable and emit radiation.
The half-life of carbon-14 is 5,730 years, which means that in that much time, half of any sample of it will change into something else. Such a long half-life implies that at any given moment, it’s emitting little or no radiation.
Or consider uranium-235. With a half-life of seven hundred million years, it’s not terribly radioactive either. But radium, whose most stable isotope is radium-226, has a half-life of sixteen hundred years. Since this is much quicker than the other atom varieties just mentioned, we would correctly infer that it’s more radioactive and hence more dangerous to handle. In any case, for nuclear power production, uranium-235 is often used, mostly because when it’s hit by a stray neutron, it fissions easily, perpetuating the chain reaction.
Whether you get intense heat and radiation capable of being channeled into steam and turbine operations for electrical-power generation or a city-destroying explosion depends on several important things.
First, the concentration of the fissionable material. A power plant’s fuel needs to have its U-235 concentration enriched from the normal 0.7 percent found in natural uranium to 4 percent. But this same 4 percent would never explode; for that you need a purity above 90 percent.
Second, the neutrons released by fission are far too fast to create further fissioning in a power plant. They need to be slowed down a millionfold, a process called moderating. In some power plants, graphite rods do the moderating, but in the majority, ordinary water does the job, and the water also serves as a coolant.
The third factor is the uranium-235: the quantity of it, how densely it’s packed, and even what shape its mass is in. An amount of U-235 that is barely critical (that is, able to sustain a chain reaction of continued neutron releases) can turn supercritical at an undesirable moment if some carelessness unfolds in its handling. Sadly, this has happened repeatedly.
For example, uranium is sometimes kept mixed with water. Given a safe subcritical storage, like a long, thin cylinder five inches wide and ten feet high, this solution might be safely pumped through pipes in a reactor until it’s dumped into a spherical container. Spheres are the most perilous shape in the reactor world. That’s because a globe has the smallest surface area of any three-dimensional shape, which means its contents are the most concentrated. In a spherical vessel, every uranium atom is close to the maximum number of other uranium atoms, and a well-behaved subcritical quantity of uranium in a skinny vessel can suddenly go supercritical when placed in a fat cylindrical tank of the correct dimensions, such as a squat soup-can configuration.
This can happen by accident. On December 10, 1968, in Mayak in Soviet Siberia, a worker unthinkingly poured four gallons of uranium water into a large pail. In a microsecond, the uranium atoms, which had been safely diluted simply by being in a tall narrow vessel, were now close enough to one another and in sufficient quantity to start a cascade of neutrons. This criticality of a neutron chain reaction begins so abruptly—with billions of trillions of atomic breakups or neutron releases in far less than a second—that the only sign of something amiss is a telltale blue flash of light as the room’s air atoms are broken apart or ionized.
On that cold day, an ordinary pail had become a nuclear reactor. The fierce sudden heat from all those atoms suddenly fissioning violently boiled off much of the uranium water and flung a couple of gallons into the air, onto nearby workers, and onto the floor. (Taken to the hospital, the worker who’d started the reaction survived—barely, having been exposed to seven hundred rem of radiation, an intensity that is often fatal.)2
But the peril wasn’t over. A bit later that night, the reactor plant supervisor arrived at that basement room to try to determine what had happened. He saw the heavy bucket on a shelf and innocuously moved it to the floor. Thanks to the boiling having splashed away some of the pail’s uranium water, the pail’s contents were now at subcritical mass and safe. But merely by setting down the bucket in the shallow pool of spilled uranium water on the concrete floor, the supervisor had unwittingly placed the uranium close to more of it. The mass went over the edge and back to a supercritical state. Suddenly there was sufficient uranium mass in a small enough area to start a reaction, and when it again went critical, it was accompanied by another blue flash. In an instant the supervisor absorbed 2,450 rem of radiation, enough to kill anyone twice over; he died two weeks later.
The same sort of accident happened on September 29, 1998, at Japan’s JCO nuclear plant. This time the culprit was forty-five liters of an 18 percent enriched uranium-235 solution. It was in a large tank that had, at its bottom, two bladelike propellers that could be stirred by an electric motor. The uranium water was floating atop a solution of a denser fluid, and the worker was supposed to mix them. He draped his body over the large tank so that he could look through a glass peephole viewer, reached over, and hit the button. The blades started turning. Suddenly there was a bang and a blue flash visible throughout the plant. The thirty-five-year-old operator felt unwell immediately and soon started vomiting. He had received seventeen hundred rem of neutrons and gamma rays, and he died eighty-two days later of “multiple organ failure.”
That cataclysm of a hundred billion trillion fission events compressed into a single second also zapped a nearby forty-year-old co-worker with lethal high-speed neutrons, though he managed to hang on in a hospital for seven months before succumbing. The tank-turned-nuclear-reactor event also delivered significant but sublethal radiation doses to four hundred and forty other plant workers.
Why did this happen? The answer is fascinating. When the motor started the blades turning and the water stirring, the uranium water’s surface formed the shape every coffee drinker observes when stirring her cup, a kind of miniature whirlpool with a depressed center. It so happens that this configuration allowed more uranium atoms to descend into that whirlpool and be closer to the other uranium atoms in the liquid. The change in fluid shape was enough to bring the barely subcritical uranium into a state of prompt criticality. Flash!
The half a dozen similar reactor accidents that produced fatal radiation releases in the United States, Great Britain, Japan, and the Soviet Union between 1950 and the 1980s mostly stayed below the radar of the mass media. This was intentional. The public’s stance toward radiation ever since the early years of X-rays and fluoroscopes has varied between wary fascination and terror. Governments that actively invested huge sums in trying to develop and perfect nuclear electrical-power generation just as actively tried to keep the lid on accidents.
It didn’t help that nuclear-safety experts were themselves unsure how much radiation was harmful. After all, everyone receives background radiation. Some 360 annual millirem for each of us is normal and probably harmless. We get it from the ground, from bricks and stones, from dust from distant coal plants,3 and from cosmic rays, with the greatest intensity for those who live at high elevations. We get it from certain foods; a single banana delivers more radiation from its radioactive potassium-40 than a person will receive from living next door to a nuclear power plant for an entire year.
We get lots of it if radon gas leaks through basement cracks from the ground under our homes. We get some every time we fly in a jet—six millirem per round-trip coast-to-coast flight. The question is, How much is too much?
Until recently, health professionals trusted the linear-no-threshold (LNT) model, which says that all radiation is harmful and there is no lower limit to what can hurt you. In other words, though everyone agrees that one thousand rem will kill you, and four hundred and fifty rem has a 50 percent chance of killing you, most health professionals felt that a ten-rem dose might still produce the kind of DNA damage that would be expected to eventually kill one person in ten thousand.
If so, then many nuclear accidents are cataclysms, for if a mere ten rem was inadvertently released to bathe a large area of one hundred thousand residents, a hundred of them might eventually die. Not good.
But there was a problem—this wasn’t what seemed to be happening. Studies of large populations who had received low radiation doses showed, after decades, that far fewer of them were coming down with cancer than the LNT model predicted. Epidemiologists monitored Hiroshima and Nagasaki survivors and Chernobyl victims and did a decadelong study of seventy thousand residents near a radioactive, thorium-emitting black-sand beach in Kerala, India, and found cancer rates low. In a few cases, they were lower than in the control groups, leading some to conclude that very low radiation doses are good for you, a concept called radiation hormesis.
In 2005, the prestigious Journal of Radiology ran an article that concluded, “The linear-no-threshold (LNT) hypothesis for cancer risk is scientifically unfounded and appears to be invalid in favour of a threshold or hormesis. This is consistent with data both from animal studies and human epidemiological observations on low-dose induced cancer. The LNT hypothesis should be abandoned and be replaced by a hypothesis that is scientifically justified.”
More studies are under way. One of them is putting animals in a zero-radiation environment so that they’re shielded from even the normal earthly background of 360 microsieverts per year. Will they die sooner when they’re deprived of all radiation?
It’s too early to know. The biggest health organizations continue to advise people to avoid unnecessary radiation, and hormesis remains controversial.
This matters here because if an accident at a nuclear power plant releases small amounts of radiation into a wide area, as happened in 2011 around Japan’s Fukushima nuclear power plant, it might be labeled a cataclysm if many cancer deaths descend like a plague on the surrounding population in the subsequent decades. But if no one is harmed or if the region’s cancer rate is actually reduced by the event, then the label cataclysm vanishes.
In any case, how many deaths make an event qualify as a cataclysm? Every year in the United States, coal-fired power plants produce around twelve thousand deaths from respiratory illnesses such as emphysema and lung cancer. If these same twelve thousand annual deaths had resulted from a single nuclear power plant accident, it would exceed the total eventual death toll from the Chernobyl event, and it would certainly count as a cataclysm. But as things stand, those annual twelve thousand coal-power deaths are pretty much ignored by the media and the public. No headlines, no attention at all.
Since a far smaller casualty toll, like one that might kill just 1 percent of that coal-power number in a hypothetical nuclear plant mishap, would be a headline-grabbing disaster, it’s clear that nuclear accidents have their own separate cataclysm standards as far as the public is concerned. It is largely for this reason that we include them in the following pages.
The first of these headline-makers had an unfortunate PR prelude. It was almost as if some malevolent anti-nuke group had set the whole thing up, because the negative impact to nuclear power could not have been more devastating.