The Zogby poll for June 6, 2008 offered some surprises. It showed that 67% of Americans favored building nuclear power plants. That's good news for the country, but the same poll showed that 51% favored building new coal-fired plants.
The same surprise came from the Rasmussen poll for July 2, 2008. 52% disagreed with Senator Harry Reid's observation that "Coal makes us sick."
Health experts have been telling us for decades that coal pollution isn't just making us sick, it's killing us. The most authoritative study done, the Abt report, confirms what studies have been showing for decades, that thousands of Americans die every month because of burning coal to generate electricity.
How is it possible that something this important is unknown to most Americans? Clearly, the news media haven't been doing their job. Commentators have complained for as long as I can remember that the news media only cover novel and photogenic stories.
Let's take the accident at Three Mile Island. It received saturation coverage. Ever since, it's been known as The Worst Nuclear Accident in American History. Any time nuclear energy is mentioned in the news, the public is reminded of this stellar fact. What the news stories never mention is that no harm came to anyone because of the accident. See the Kemeny Report for details. Well, the owners of the plant lost big time, but that's not what we're talking about here.
As one would expect, misinformation flowed in to fill the information vacuum. Irresponsible political groups like Greenpeace and Friends of the Earth and their many imitators have fed the appetites of news media for lurid and frightening what-if scenarios. The fact that these scenarios are based on fantasy and not on reality doesn't bother media reporters in the slightest. The misinformation gets stories published and that's all that matters.
Why don't the political groups campaign against coal, since it truly is dangerous? That's more complicated. Greater coal consumption is the inevitable consequence of less nuclear energy. If they publicized the facts about coal, they'd have to admit they were wrong about nuclear energy. We can, however, note with new-found respect that the Sierra Club is intervening to stop the construction of new coal-fired plants. It will be interesting to observe whether or not the Sierra Club breaks ranks with less-credible political groups. Will the Sierra Club ever show the moral courage of environmental heavyweights like James Lovelock and Hugh Montefiore and reverse its position on nuclear energy?
In the meantime, what can be done to overcome the information deficit? The Nuclear Energy Institute does a valiant job of informing the public where it can, even sending spokespersons to public meetings. Anything NEI says, though, will naturally be discounted since its job is to promote a particular viewpoint. One might wonder if spending its budget on a race car really is effective at promoting nuclear energy, but the alternative would be sending out video documentaries no one would watch. One has to hope NEI knows what it's doing.
For the rest of us, the best we can do is inform ourselves as well as possible so we can offer good information whenever the subject comes up around us. This blog is an effort in that direction, as are the blogs recommended in the sidebar. Since the other side is working hard at spreading confusion and misinformation, we just have to hope readers can tell the difference. If people knew the truth about coal, the support for nuclear energy would be much higher than 67%.
Showing posts with label Three Mile Island. Show all posts
Showing posts with label Three Mile Island. Show all posts
Sunday, July 6, 2008
Tuesday, January 29, 2008
Nuclear Accidents
There have been two serious accidents involving nuclear power reactors and it's right that they have received very much attention. They are at the heart of the debate over whether or not to expand nuclear energy to minimize global warming.
The reactor at Chernobyl was different from all the other power reactors outside the Soviet Union: it was inherently unstable, meaning that the reactivity in the core went up when it got hotter so that once the operators lost control there was no way to get it back.
The accident happened this way[source]. The night crew was told to perform a test to see if the reactor could sustain a sudden disconnection from the power grid. It happened that the night crew was inexperienced (presumably because of seniority rules), though that probably wouldn't have made any difference. What was supposed to happen was that the flywheel inertia of the turbine blades in the electrical generators would give enough power to run the coolant pump until the diesel-powered generators could start and power up.
The crew didn't know that the reactor was operating at an abnormal condition, having run at full power all day and then being cut back to part load, but that probably wouldn't have made any difference, either.
It's not clear why, but the coolant pumps were run at their maximum flow. Possibly the crew thought they were increasing the safety margin. But the resulting cooler temperatures lowered the steam pressure and water filled more of the reactor's internals. Water absorbs neutrons more than steam does, so the control rods had to be withdrawn to maintain power.
The automatic controls would ordinarily have shut down the reactor under these conditions, so the crew disabled the emergency cooling system and the emergency shutdown rods (usually called SCRAM rods).
The crew disconnected the plant from the power grid. But the pump power from the turbine blades wasn't sufficient so the reactor started heating up. Because of the instability this reactor had, the higher temperature raised the reactivity rate, causing more heating, etc. At that point the reactor was out of control. Steam drove water out of the core, and reactivity increased more. Once the crew realized something was wrong, they inserted the control rods. But the control rods inserted slowly, not quickly as the shutdown rods would have. To make matters worse, the tips of the control rods were made of graphite instead of boron. Graphite raised the reactivity rate instead of lowering it as boron would have done. The rods jammed when they were partly inserted.
The reactor continued to heat up. A steam explosion drove some parts out through the sheet-metal roof that kept rain off the reactor. Finally, the reactor body, which was made of graphite, reached its ignition point. The hole in the roof allowed air to enter and the reactor caught fire.
After the accident, the World Health Organization did an extensive investigation and continual followup; its findings were that actual deaths have numbered about 50 and theoretically there could be as many as 4000 fatal cancers in the future.[source] As tragic as that is, it doesn't approach the death rate due to burning coal. Even in the US, tens of thousands of people die every year just from the pollution from generating electricity with fossil fuels.[Abt Associates Report, Exhibit 6-4]
What's interesting is that a big part of the region around Chernobyl now is healthier than before the accident. The chemical refineries and coal-burning plants caused terrible health problems. Now that they're shut down, the air is clean. Some people have moved back into the parts which officially are quarantined but where radiation isn't especially high. They eat vegetables from their gardens and drink water from their wells, and take eggs from their bug-eating chickens, and they're doing just fine. Wildlife have flourished in the area, including the hot spots. Wildlife biologists are studying the animals and plants and even after all these years they're not finding any radiation-related health problems. There's a superb book on Chernobyl's aftermath: Wormwood forest : a natural history of chernobyl by Mary Mycio.
So what are the differences between Chernobyl-style Soviet reactors and all the power reactors in the rest of the world? There are too many differences to list here, but we'll tick off the major differences that led to the accident.
1. The reactor was unstable.
2. The reactor had no containment structure.
3. The reactor was made of graphite, protected only with a sheet-metal shed. Outside the Soviet Union, power reactors have multiple layers of steel and concrete protection.
4. The crew hadn't been trained for the test it was performing.
5. The crew was working without supervision and went against plant operating regulations.
To understand why the reactor was built and operated so unsafely, you'd have to understand how the Soviet system worked. I'm not qualified to explain it, but if you read some Solzhenitzyn you'll get the idea. The accident did, however, prove that anti-nukes had vastly overstated the harm such an accident could cause. It turned out that the consequences, serious as they were, were of the same scale as disasters that happen every year.
More important, the accident at Three Mile Island in Pennsylvania in 1979 totally destroyed the reactor but resulted in no adverse health effects, which validated the defense-in-depth designs used in all US power reactors.[source]
The reactor at Chernobyl was different from all the other power reactors outside the Soviet Union: it was inherently unstable, meaning that the reactivity in the core went up when it got hotter so that once the operators lost control there was no way to get it back.
The accident happened this way[source]. The night crew was told to perform a test to see if the reactor could sustain a sudden disconnection from the power grid. It happened that the night crew was inexperienced (presumably because of seniority rules), though that probably wouldn't have made any difference. What was supposed to happen was that the flywheel inertia of the turbine blades in the electrical generators would give enough power to run the coolant pump until the diesel-powered generators could start and power up.
The crew didn't know that the reactor was operating at an abnormal condition, having run at full power all day and then being cut back to part load, but that probably wouldn't have made any difference, either.
It's not clear why, but the coolant pumps were run at their maximum flow. Possibly the crew thought they were increasing the safety margin. But the resulting cooler temperatures lowered the steam pressure and water filled more of the reactor's internals. Water absorbs neutrons more than steam does, so the control rods had to be withdrawn to maintain power.
The automatic controls would ordinarily have shut down the reactor under these conditions, so the crew disabled the emergency cooling system and the emergency shutdown rods (usually called SCRAM rods).
The crew disconnected the plant from the power grid. But the pump power from the turbine blades wasn't sufficient so the reactor started heating up. Because of the instability this reactor had, the higher temperature raised the reactivity rate, causing more heating, etc. At that point the reactor was out of control. Steam drove water out of the core, and reactivity increased more. Once the crew realized something was wrong, they inserted the control rods. But the control rods inserted slowly, not quickly as the shutdown rods would have. To make matters worse, the tips of the control rods were made of graphite instead of boron. Graphite raised the reactivity rate instead of lowering it as boron would have done. The rods jammed when they were partly inserted.
The reactor continued to heat up. A steam explosion drove some parts out through the sheet-metal roof that kept rain off the reactor. Finally, the reactor body, which was made of graphite, reached its ignition point. The hole in the roof allowed air to enter and the reactor caught fire.
After the accident, the World Health Organization did an extensive investigation and continual followup; its findings were that actual deaths have numbered about 50 and theoretically there could be as many as 4000 fatal cancers in the future.[source] As tragic as that is, it doesn't approach the death rate due to burning coal. Even in the US, tens of thousands of people die every year just from the pollution from generating electricity with fossil fuels.[Abt Associates Report, Exhibit 6-4]
What's interesting is that a big part of the region around Chernobyl now is healthier than before the accident. The chemical refineries and coal-burning plants caused terrible health problems. Now that they're shut down, the air is clean. Some people have moved back into the parts which officially are quarantined but where radiation isn't especially high. They eat vegetables from their gardens and drink water from their wells, and take eggs from their bug-eating chickens, and they're doing just fine. Wildlife have flourished in the area, including the hot spots. Wildlife biologists are studying the animals and plants and even after all these years they're not finding any radiation-related health problems. There's a superb book on Chernobyl's aftermath: Wormwood forest : a natural history of chernobyl by Mary Mycio.
So what are the differences between Chernobyl-style Soviet reactors and all the power reactors in the rest of the world? There are too many differences to list here, but we'll tick off the major differences that led to the accident.
1. The reactor was unstable.
2. The reactor had no containment structure.
3. The reactor was made of graphite, protected only with a sheet-metal shed. Outside the Soviet Union, power reactors have multiple layers of steel and concrete protection.
4. The crew hadn't been trained for the test it was performing.
5. The crew was working without supervision and went against plant operating regulations.
To understand why the reactor was built and operated so unsafely, you'd have to understand how the Soviet system worked. I'm not qualified to explain it, but if you read some Solzhenitzyn you'll get the idea. The accident did, however, prove that anti-nukes had vastly overstated the harm such an accident could cause. It turned out that the consequences, serious as they were, were of the same scale as disasters that happen every year.
More important, the accident at Three Mile Island in Pennsylvania in 1979 totally destroyed the reactor but resulted in no adverse health effects, which validated the defense-in-depth designs used in all US power reactors.[source]
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