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Chernobyl (Finally) Shuts Down
wpanderson writes "The Ukrainian nuclear power station at Chernobyl has finally been closed down by President Leonid Kuchma, according to the BBC News.
The plant has been plagued with problems - the most public and visible was the failure of Reactor 4 on 26th April 1986, although there have been more problems since. The most recent was a "malfunction" in Reactor 3 which caused a shutdown, just 9 days before the closure date.
Although the plant is now closed, and the Ukrainian government has pledged not to use the site for electricity generation again, it will "be 2008 before the fuel rods can be safely removed from the plant".
There are quite a few pictures taken inside the ill-fated Reactor 4 (cyrillic link) for the morbid!"
Here is a nice map: http://www.angelfire.com/tx/atomicveteran/
The disaster at Chernobyl was the final nail in the coffin of nuclear fission generators, and when the last one is shut down, I suspect that I'll be one of the only people not cheering.
Nuclear power should have (and in almost all cases has) lived up to much of it's "great promise." Properly done, it is cheap, efficient, and safe.
Safe? That's right--it's hard to come up with a safer form of electricity than a good reactor. Coal? Not a chance! Hydropower? Maybe, but it's not very 'environmentally clean.'
But popular opinion matters more than facts, and one disaster like Chernobyl (which still hasn't killed a fraction as many people as coal) will push popular opinion over the edge.
Here's the problem: Chernobyl-class reactors are badly designed, lacking in a lot of safety features, and fairly scary. It STILL took years of substandard maintenance, lack of care, bad luck, and gross negligence on the part of several operators to kick off the meltdown. In a well maintained and properly designed reactor (CANDU!!!), an operator _couldn't_ cause that kind of disaster, no matter how they tried.
But it's pointless to argue the merits. Nuclear power is on its way out. Ah well. Hopefully we'll get serious about wind before long.
"People who do stupid things with hazardous materials often die." -- Jim Davidson on alt.folklore.urban
That there are still several aging Chernobyl class reactors still in use.
In Lithuania, for example, the Ignalina plant provides something like 80% of the countries electricity, and is rapidly approaching the end of it's life. The problem is that they can't afford to shut it down, and they can barely afford to keep it running.
We're not out of the woods yet; the Chernobyl legacy will play out for many years to come.
One (slightly used) glow-in-the-dark water heater, near-mint condition. Still operates with the efficiency and safety it did when it was new.
Currently listed as item number #102934613 on ebay.
Buyer assumes all liability for maintenence, disposal and heating costs. Buy now and I'll throw in free shipping!
As is usually the case in any accident, a number of things combined to cause this one at Chernobyl. Unlike power
reactors operating in the U.S. and other nations, the Chernobyl RBMK reactor (which is a graphite rather than a
light water system) has a built-in instability that occurs at low power, which is how the reactor was operating at
the time of the accident. If some of the cooling water in this reactor converts to steam, the RBMK increases in
power. This in turn causes more steam to form, which causes _another_ increase in power. (In Western light
water reactors, the power decreases.)
The power increase feature of the RBMK caused a rupture in the cooling system and a large steam explosion
occurred. This caused the cooling system to fail and the outer covering (or cladding) of the fuel elements to
increase in temperature. The cladding was hot enough to react with the steam, causing hydrogen to form. The
hydrogen then caused a second explosion. The release of this energy set the graphite core on fire.
In spite of its dangerous features, the RBMK -- unlike other reactors -- had no actual containment structure to
prevent release of contamination. Such a design could not be licensed by the Nuclear Regulatory Commission in
this country, nor in most countries of the world. Studies done since the Chernobyl accident have shown that its
releases would have been successfully contained by a U.S. type reactor. As a matter of fact, a test of a 37-foot
tall scale model of a nuclear plant containment building was made at Sandia National Laboratories in New Mexico
in 1987. The test showed that the type of light water containment used at U.S. nuclear plants could withstand
more than three times the pressure it was designed for without rupturing or fragmenting.
A second factor in the Chernobyl accident involved a safety experiment being conducted. It required that the
reactor be run in a very unusual manner. Because of a series of operational problems, the operators found
themselves running the reactor far outside its safety limits. In their efforts to finish the experiment anyway, the
operators --in spite of running the reactor under unfamiliar conditions-- turned off seven of the safety systems in
the reactor and its control systems. Any one of these seven automatic controls could have prevented the accident
had it been on.
All this reflects important differences between Western and Soviet operators and their training. Unlike the Soviets,
U.S. reactor operators take continued training in classroom situations and on reactor simulators. Further, operators
in Western countries are strictly bound by what are called "technical specifications" which forbid operation of the
reactor outside of preset safety limits. All of which could be debaitable anyway.
Trust the source!
The accident at Chernobyl came about from the decision to conduct a specific low-power test; namely, if the plant scrammed and lost its connection to outside sources of power, would the residual power from decay products be enough to run the coolant pumps and so forth?
To drop the plant to a power level that would simulate that scenario, they had to move through several instability regions where the nuclear properties of the moderator and coolant caused positive feedback loops and the reactor's safety mechanisms kept "getting in the way". Xenon buildup made it difficult to work around these problems, and since the test was being conducted in the middle of the night and the reactor physicists were all snug in their beds, on-site personnel decided to disable the safety control mechanisms. They had the reactor down at (if memory serves) 30 kW or some trivial number when they hit another feedback loop. In the course of the next few seconds, the temperature of the coolant rose with the power level (power spiked to something like 30,000MW in a tenth of a second), the coolant then flashed into steam, the steam pressure blew the roof off the building, and the 3,000 degree graphite moderator was exposed to the air, at which time it burst into flame, cracked, and generaly became a Problem.
The RMBK design of reactor has positive reactivity coefficients. It's a "bad" design in that it requires intervention when the laws of physics want to put it on a runaway. However, unless things go horribly awry, human operators are more than capable of operating such a reactor safely.
The problem at Chernobyl was not the reactor, but the people operating it. Many people around the world want to see nuclear power eliminated because even with the safer designs of the Western world, a ragingly inept (or malicious) employee with access to the wrong places can make Bad Things happen. To me, that's the wrong reaction; a spiteful mechanic at United Airlines could cause the deaths of hundreds of people but we don't see a call for the elimination of air travel.
Learn to spell: nickel, missile, lose, solely, amendment, speech, kernel, probably, ridiculous, deity, hierarchy, versus
One of the interesting things about Chernobylite is that it appears to be made from fuel melting into the sand which surrounded the reactor itself. We are working on converting radwaste into a glass form for final disposal, and this got there quite by accident. It also did a remarkable job of flowing without melting through things; it's all over the floors, but doesn't appear to have gone any significant distance though them. If someone wanted to budget the money for the robots and such, it shouldn't be terribly hard to break the stuff into chunks using hammers and shovel it up into canisters to cart away. In any event, it's not an immediate problem because it's quite well immobilized as-is. The bigger problem is the stuff on the ground floor of the building that's in small particles or dust form, because it can be leached or blown into the air by a building collapse or just the wind.
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Time is Nature's way of keeping everything from happening at once... the bitch.
From the page: (credit, copyrights go to Chernobyl Charity Online, please visit their site)
-Erik
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-Erik
Good, it was an unsafe design anyhow
Heheh... Positive control coefficient, and a moderator that doesn't boil away.
It was an *insane* design, bordering almost on the criminal.
And yeah, there are still more than a dozen of the damned things running.
<sigh> I know that the RBMK reactor was designed for three goals: price, efficiency, and plutonium production (for weapons). And since that didn't include safety, I guess the engineers got what they wanted.
I'm all for nuclear power. You can't burn fossil fuels because of price per MWh and emissions. You can't build damns everywhere, because there are great environmental consequences to those - and they're only practical where there's a large river. (ie. Hoover Damn powers a lot of L.A., but how far from L.A. is it, with resulting efficiency losses in the lines?) You can't build tidal, wind or solar plants yet, because the technology still isn't practical even in the parts of the world that energy is abundant enough to effectively harness.
Western Europe has been shutting down its nuclear plants and increasing its reliance on natural gas. Fine, gas is easy to manage and it's clean as far as fossil fuels go. It's also abundant in neighboring Russia.
Ironically, as Western Europe shuts down its reactors, Russia keeps on commissioning and retrofitting their pressurized water and dangerous RBMK reactors so that they don't have to divert any natural gas that would otherwise be sold to Europe.
As is usual with the policies enforced by environmental lobby groups, it backfired. Fine, the reactors in Western Europe are being shut down. And replaced with far more dangerous Russian reactors. Good work, you stupid long-haired hippie tree-huggers. (Ooops. I have long hair and I like Five Man Electrical Band, I guess I can't insult hippies.)
Before you moderate me down for saying that environmentalists are idiots, check out this link, which has to do very specifically with the Russian reactors vs. Western Europe natural gas fiasco. While environmentalists are full of great intentions, they're generally ignorant of science or the basic fundamentals of how a marketplace economy works.
Like it or not, nuclear power is going to be here for a while.
Let's encourage safe and responsible use of nuclear power, at least until something more practical comes along. Let's try to not ban nuclear power, but to ban RBMK reactors.
Let's see a day when all the running nuclear reactors in the world have *negative* control coefficients (ie. won't run without a moderator) and use a moderator that will boil off and shut down the reactor in the case of an overheat.
Back when I was in high school, I got a summer internship down the road from Ottawa at a place called Chalk River Nuclear Laboratories. This was the home of Canada's nuclear program, and is one of those rare things that makes me proud to be a Canadian. Canada still leads the world in civilian nuclear technology.
At the time, they had three big research reactors there - the decommissionned "ZEEP" (Zero Energy Experimental Pile, put out *one watt* of heat, built in 1944 for the war effort and has a colorful history), the vertical-loading National Research eXperimental "NRX" (since decommissionned) and the horizontal-loading NRU. All three were of the CANDU design, though the ZEEP and NRX were very primitive.
I was assigned to the NRX. Every day, I'd travel from Deep River to Chalf River, don my dosimeter, walk through the checkpoints and head to the reactor. It was great fun, helping out with experiments. And irradiating golf balls for increased driving distance.
There was a Commodore PET on top of the reactor, and it used to record and monitor the temperature throughout different parts of the reactor vessel. Then, there were the tube computers (no kidding!) with ferrite core memories which were used to provide more critical functions. (Semiconductors don't like ionizing radiation if the reactor leaked, tubes are a lot more forgiving.)
And, let me tell you, there's no feeling in the world quite like standing there, on top of the reactor, looking down 30 feet or so to the people below you, feeling the slight vibration of the pumps running all around, and the sheer sense of power in the room as the reactor below you runs.
Food was forbidden in the reactor buildings, because ingestion of bits of radioactive dust was an (unlikely) possibility. Even so, people did eat there occasionally, and I was no exception, though you become very careful with the geiger counters before you put it in your mouth. Because there was (officially) no food allowed in the building, there was no kitchen, so hot snacks were a rarity. Canned stew was a special favorite: the cans fit right into the (sealed) sample tubes. Drop them in at the top, lower them slowly through the reactor, and then retrieve them at the bottom. If you timed it just right, the can was nice and warm. If you got distracted, the can burst and you'd have to clean out the sample tube. (And no, this was not a good idea, but it didn't put anyone at risk besides those of us who ate the food, and we all knew perfectly well how the food had been cooked.)
I'd have gone into nuclear physics as a career if I could have handled the math. <grin>
My favorite reactor design is the CANDU (CANadian Deuterium-Uranium). It's an elegant design. Uranium 238 ("natural uranium") is used instead of the U-235 used in most other reactors. U-235 requires the added steps of processing and is also vulnerable for use in weapons.
The moderator in a CANDU reactor is heavy water; deuterium instead of ordinary hydrogen. Deuterium is a rare but naturally-occurring isotope of hydrogen. It's ordinary hydrogen in every respect, except for the fact that there's a neutron in the nucleus. It's not radiactive (unlike hydrogen with two neutrons, called "tritium", which *is* radioactive). Deuterium water is heavier than regular water, simply because of that neutron in the hydrogen.
The heavy water serves as the moderator. It slows down the fast-moving neutrons coming off the U-238 so that they can sustain the fission chain reaction. Light (ordinary) water will not sustain this reaction - nor will no water.
Let's say everything fails. The computers go down, the control rods are all jammed out of the core, and the operators are idiots. A Chernobyl accident still cannot occur. It's physically impossible.
If a CANDU reactor gets out of control and overheats, the moderator (heavy water) can be drained away, shutting down the reactor. You can't do that with blocks of graphite like an RBMK reactor. With a CANDU, if there's a problem and the operator doesn't drain the moderator away, eventually a pressurized pipe will burst and the moderator will boil away. With no moderator, the reactor will cease to work. Since the fuel is uranium in non-water-soluble ceramic pellets, there will be minimal decay daughters in the resulting steam cloud. Which will be contained anyway in the concrete reactor house, which is held under a vacuum to prevent release.
Unlike Chernobyl, which drastically overheated. The solid graphite moderator began to burn. And still the chain reaction continued to produce heat, because the graphite moderator was still there... it burned for 9 days.
Let's take all those unemployed Chernobyl workers to see a CANDU or similar reactor in operation, train them extensively on it, and then help them build them to replace their aging and rickety designs.
Fire and Meat. Yummy.
The Chernobyl accident is far from over. I attended a special lecture by Professor William Zoller at the University of Washington, in which he described what happened, and is continuing to happen, at Chernobyl. It is not an entertaining lecture to attend. He told us a lot of things.
Professor Zoller showed us images of the radioactive goo at the bottom of the reacter. He told us that 3 people died to get the picture. The government just kept sending people down with cameras until someone went down, took a picture, and survived the trip back up, and then died. (Prof. Zoller was functioning as a UN inspector, or something. I have forgotten just what he was doing over there.)
If there are pictures of the interior of the building where the accident occured, you can pretty much assume people died to take them.
No, they didn't send robots to take those pictures.
All Russian nuclear plants were breeder plants. Apparently, they wanted plutonium for their weapons. Nuclear submarines, and, yes, NUCLEAR HANDGRENADES are the stupidest ideas in history, but, hey... There wasn't/isn't exactly a concern for human life over there.
Arctic dumping was the primary means of evacuating radioactive waste. Rivers were also a way of getting the waste out of there. As far as I can tell, people panicked, and thought, "Well, if we just dump this in the sea, it'll all just go away." In 10 years time, here in Seattle, we'll be told not to eat our fish. (This is according to Professor Zoller.) He also claims that the EPA knows about this, but is required to keep quiet. But, they continue to monitor the radioactivity of boats coming in on the ports here in Seattle.
The so-called "Brave Firefighters" who put out the fire were not brave. They were forced to put it out by the KGB.
There is a place called Chelyabink-Tomask (unfortunately, I don't have my notes with me and cannot spell the name correctly.) that is a living graveyard, guarded by the military; They are essentially, waiting to die. Nobody goes out, nobody goes in.
You can verify this yourself by contacting him. He will ask you if you are a member of the press. If you are, he is not allowed to talk about it with you. So ask him personally.
I wonder if posting an email to Slashdot is equivelent to being a member of the press.?
These notes are from my memory, not my written notes; I'm afraid there will probably be imprecise. But they are accurate. That is, what is described is true, though I may have numbers and names wrong. His lecture scared me immensly. The room had only about 10% of the people in it by the time he finished...
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