Posted on Tuesday, 29th March 2011 @ 08:38 AM by Text Size A | A | A

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I could not remember ever learning much about nuclear power in all my years in college, so I decided to get in touch with a nuclear engineer. Unfortunately, former President Jimmy Carter did not return my phone calls, so I rang up Tony, a guy with whom I went to school and a person who currently works as a “nukehead”—as they call engineers—at the Piketon, Ohio atomic facility. Not long after he suggested that I only ever call him when I want something, he settled in to telling me the story of everything nuclear. This article could not have been written without his infinite patience.

Tony was quick to point out that nuclear energy has its pros and cons. On the plus side, nukes do not depend on fossil fuels, so less Carbon Dioxide makes it to the atmosphere (thereby not worsening climate change). Also, the cost of nuclear power is not affected by the fluctuations in oil prices.

On the down side, mining and purifying Uranium is a dirty business. Even transporting nuclear fuel poses a contamination risk. And once the fuel is spent, it remains deadly. This fuel, or what the engineers call radioactive waste, emits heat, and so it will eventually corrode any container. And, of course, there is also a risk of nuclear accidents. “But that doesn’t happen much anymore, does it?” I asked. He didn’t say anything, so I changed the subject. Exactly how, I wondered, do these plants work? He sighed and launched into a lecture I was certain he had given many times before.

As of March, 2011, there are more than 430 operational nuclear power plants, together providing 15% of the world’s electricity. Of the thirty-one countries using these plants, some depend on nukes more than others. For instance, in France, 77% of the electricity comes from nuclear power, whereas in the USA, 104 plants supply a total of 20% of our electricity.

Nuclear power plants operate much like a coal-burning power plant. Both heat water into steam, which in turn drives a turbine generator. The difference is in the way the water is heated. Nuclear plants depend on the heat from nuclear fission. This fission occurs in nature every day. Uranium, for example, constantly undergoes spontaneous fission very slowly. This is why the element radiates and is why it is a logical choice for the induced fission that nuclear power plants require.

Uranium-238 has a half-life of 4.5 billion years and it makes up 99% of all the uranium on earth. However, Uranium-235 (which accounts for less than 1%) has a property that makes it great for producing nuclear power and weapons: it is one of the few elements that can undergo induced fission. If a free neutron hits a Uranium-235 nucleus, the nucleus absorbs the neutron, becomes unstable, and splits.

To transform nuclear fission into electricity, the power plant operators must control the energy given off by the enriched Uranium and let it heat water into steam. Workers at the plant bend the enriched Uranium into pellets that are about the size of a dime, and then arrange the pellets into long rods, which are in turn collected into bundles. The bundles are dropped into water inside a pressure vessel. There, the water acts as a coolant.

To prevent overheating, control rods are inserted into the Uranium bundle. So, when the operator wants the core to produce more heat, he raises the rods and when he wants less heat, he lowers them into the bundle. In case of accidents, dropping the rods all the way into the bundle shuts the reactor down. Simply put, the Uranium bundle heats the water and turns it to steam. The steam drives a turbine which spins a generator to produce power.

Because a nuke can emit dangerous levels of radiation, the companies do take precautions. A concrete liner houses the reactor’s pressure vessel and acts as a radiator shield. That liner, then, is kept inside an even bigger steel containment vessel. This vessel holds the reactor core, along with the equipment to refuel and maintain the reactor. This vessel also acts as a barrier to prevent leaks of radioactive gas or fluid from the plant. Outside of this is a concrete building that serves as the outer layer. The outer structure should be able to withstand earthquakes and the effects of jet aircraft crashing into them. In the event of an accident, the secondary containment structure should prevent the escape of radiation or steam. It was the lack of these containment structures, Tony assured me, that allowed radioactive material to escape in Chernobyl.

“There have only been two occasions where I suspected the world was about to come to an end,” confided Dr. Gregory Jones of Ottawa University. “The first was the Cuban Missile Crisis in 1962. The other was the nuclear accident at Chernobyl in 1986. See what you can find out about that one.” Phil Mershon, cub reporter, to the rescue!

Piketon, Ohio Atomic Plant

Because Tony did not feel like talking about accidents—for a minute I thought he was interested in job security or something—I had to look elsewhere for my research on Chernobyl. Much of the information available is contradictory. However, unless otherwise noted, all of the following information conforms with the unanimous conclusions of eight agencies’ research findings as of 2,006: The International Atomic Energy Agency (IAEA), the Massachusetts Institute of Technology (MIT), the Ukrainian Academy of Sciences, the Kurchatov Institute, the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), Agenci pour l’energie nucleaire, the World Health Organization (WHO), and The Other Report on Chernobyl (TORCH), the latter sponsored by the European Greens.

The world’s largest reported nuclear accident happened a little after 1AM on April 26, 1986, at the Chernobyl nuclear facility in the Ukraine. The plant had four working reactors at the time. Operators ran a test on an electric control system at Unit 4. A combination of engineering deficiencies (such as the lack of a secondary shield) and human error conspired to allow an uncontrollable power surge to occur. As a result, the nuclear fuel overheated, in turn causing a series of steam explosions that wrecked the reactor building and destroyed Unit 4.

Less than one full day into the accident, the super-heated material in the reactor set fire to combustible gas, yielding a fire that burned for ten days, during which time radioactive materials were released. These deposited with great intensity within 20 kilometers of the reactor, although mid-range contamination reached Belarus, the Russian Federation, and the Ukraine, with smaller—yet significant—distribution covering a 1200 kilometer circumference, which reached Warsaw, Moscow, Istanbul, Athens, Rome, Munich, Paris, Oslo, and Helsinki.

How did this happen? The Chernobyl reactor was a high output, multichannel type. It was a pressurized water reactor using light water as coolant and graphite as a moderator. The aforementioned power surge caused fuel fragmentation. Heat transferred from these fragments to the water, resulting in what is called a shock wave in the coolant, which in turn led to the failure of most of the lower transition joints. The cooling water encountered intense heat and turned into instant radioactive steam. Below is an exact diagram of the type of reactor in use at Chernobyl.

The melted core materials, or lava, drifted to the bottom of the core shaft, while the fuel settled into a metallic layer underneath the graphite. During the seventh day, the graphite layer burned off. Without this filter, volatile fission products from the fuel escaped into the air.

On the eighth day, corium (the magma that would be formed following the fusion of the core of a damaged nuclear reactor) melted through the lower biological shield and hit the floor of the sub-reactor, increasing the release of radionuclides (radioactive atoms). The Strontium-90 , Iodine-131 , Cesium-134 , and Cesium-137 . The total radioactivity from the reactor was 200 times the combined releases from the bombs dropped on Hiroshima and Nagasaki. Of the four major radioactive isotopes released, it was Iodine-131, with its brief half-life, which rendered the greatest health risk because it accumulates in the thyroid gland, and so growing children are particularly susceptible. Cesium-137, however, is still measurably in soils and food in many parts of Europe.

Of course, the people who received the highest doses of radiation were the 1,000 emergency workers and on-site personnel. The area closest to the power plant has been designated the Exclusion Zone. 116,000 people living there were immediately evacuated, and the remaining 220,000 were later relocated.

The immediate effects were less severe than expected. Two people died during the accident and twenty-eight others working at the plant died soon after. The long-term effects, while less precise, are statistically significant. In 1986—the year of the accident—the combined countries of Belarus, the Russian Federation and the Ukraine had a total number of 10 childhood thyroid cancer cases. In 1993, these same countries reported 781 such cases. On a more reassuring note, the incidence of childhood leukemia has not changed since the accident.

However, due to the breadth of the contamination (5% of Finland and Sweden, and 80% of Moldova, European Turkey, Slovenia, Switzerland and Austria were poisoned by Cesium-137), restrictions on food remain in much of Europe and Scandinavia.

* * * * * * * * * * * *

I read my boss Greg everything written to this point. He expressed pleasure in having someone read to him. He also interrupted me a few times to correct my pronunciation of chemical elements (“It’s stron-chum and sees-ee-um,” he told me; I guess I was okay with “Iodine”). Once I was finished, he said, “What about Finland, Sweden, and the dairy farms? I’m sure I remember warnings about the food there.”

In my excitement, I had forgotten I was dealing with a genuine man of the world, a fellow who spoke fluent Italian and who could rattle off the names of Norwegian cities faster than I could recall the names of my living relatives.

Although I discovered nothing more about Finland (other than that its capital is Helsinki, if anyone wants to know), I stumbled upon an intriguing article by Anthony Affigne, a Political Science professor at Brown University, and a man whose credentials I cite simply to point out that he has invested some time in the matter at hand, rather than to impress the reader with his stature. Back in 1990, he published an interesting article in the admittedly pro-environmental journal National Forum.

The article possessed more liveliness than my other sources. Affigne, relying on research by Richard Mould, talked about what went on inside Unit 4 at the time of the accident. Within the first few seconds:

temperatures in the core shot up from 280 degrees Celsius to 1700 degrees ]that’s 3,092 degrees Fahrenheit]. In the next second, when the uranium fuel surpassed 3,000 degrees [5400 Fahrenheit], the combined energies of steam and nuclear fission reached more than one hundred times the plant’s full power rating. Facing such unprecedented fury, the reactor’s steel and concrete vessel. . . could no longer contain the steam and heat. . . A powerful steam explosion blew the roof off. . . This. . . exposed the core to air and steam. White-hot pieces of nuclear fuel crashed through graphite, setting it ablaze at temperatures of 5000 Celsius [9, 032 Fahrenheit].

That was certainly the most imagistic attempt at writing about the event that I had encountered. Affigne further pointed out that, even without all the horrific description, “Compared to earlier accidents, the scale of the disaster was almost unimaginable: in the prior 42 years of the atomic age, 284 accidents had killed 33 people.”

I visualized Dr. Jones sitting in his office, developing a non-confrontational way of asking about Sweden. As it turns out, Greg was correct. The Swedes imposed the world’s harshest prohibitions on mushrooms, berries, fish and reindeer. Admittedly, that wasn’t a lot of information, although the implications were interesting, what with Sweden being nearly 1200 kilometers from ground zero.

Two other bits of data came serendipitously to my attention as I attempted to get to the bottom of this Sweden issue, both of which I came upon—as they say in nuclear circles—by accident. First, in my scientific illiteracy, I had imagined that the greatest threat posed by nuclear fallout was physiological: people vaporize, suffer from radiation poisoning, or develop forms of cancer. Once again my lack of imagination was the greatest flaw. As it happens, there is a biological component to all this. While perhaps not as dramatic as having someone disintegrate in a cloud of liquid fire, the most important biological effect of radiation is the production of changes in the genetic or chromosomal make-up, the most severe of which are permanent genetic mutations. So, for instance, two Swedes affected by fallout suffer genetic mutations, have a child together, and pass on the purity of that change. These genetic mutations don’t have much to do with hair or eye color, but they do have a lot to do with iron shortages and predispositions to colon cancer, among other maladies.

Second, in my handy copy of the McGraw-Hill Encyclopedia of Science & Technology, I encountered a list of the radioactive fission products, in addition to the four already mentioned. Some of the more interesting ones include Cobalt-60 , Barium-140 , Radium-226, and of course Plutonium-239 .

Greg’s reaction to all this was multi-layered, paradoxical, ironic, and brief. “I’m sorry I asked,” he said.

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