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Chernobyl...18 Years Later
abysmilliard writes "A young Ukrainian woman has posted a photo journal of her motorcycle rides through Chernobyl and the area surrounding it. Included are pictures of the now-emptied city, maps of current radiation levels, and a discussion of how the area has changed. While the english is quite broken, it's often rather surreal, as well, with quotes like, 'I don't know how sound the silence to those tourists that they can not stand it, but to me after hitting a red line on my bike tacho it sound like all those ghosts cursing 1100cc kawasaki engin.'"
For the record, a free Angelfire site presently gets 1 GB of monthly bandwidth on which to serve up to 20 MB of content. Which means, when /. finishes off this site's bandwidth allowance, this site's gone for the month.
If somebody were to give this unfortunate person Angelfire's highest "element plan", it would cost $15 for the setup and $14.95 for the first month, and give her 30 GB of monthly traffic. That might be enough to survive a slashdotting.
(She - apparently by mistake - skipped page 16, which you can access by modifying the URL manually.)
http://alternatives.rzero.com/
She mentions that the radiation exposure in Kiev during the first few days was equivalent to about a year's worth of radiation at Chernobyl now. The bastards did not inform the populace until the wind blew into Europe and radiation alarms started going off, igniting international alarm. My wife, a child at the time, was belatedly rushed out of town along with all the children in Kiev a week later. I can't prove a link, but the fact is my wife had cancer surgery just last week. I'm sure that coal and gas are worse for the environment, and I support nuclear energy as a cleaner alternative, but a freak accident combined with a stupid reaction of a government made matters much worse than they should have been. People will be suffering due to Chernobyl for decades and centuries to come.
There is another page of pictures that you won't see clicking on the links, she has page 15 going directly to 17 by accident. This page shows the swimming pool.
When the bomb went off, you could actually see the bones in your hands from all the X-rays that were emitted from the bomb. True, but not for the Reason you stated. I dont care how bright the light is, you cant see X-Rays with your eyes. however, with a sufficiently bright light your hand becomes translucent and you can see the outline of your bones. Try this: With a very powerful flashlight (like a Maglite) go into a dark room and let your eyes adjust for a minute or two. Then hold your hand so the palm completely covers the flashlight part, dont let any light escape. Turn the flashlight on and you should be able to make out the outline of your bones, if the light is powerful enough. But you still cant see X-rays.
Insightful, but wrong...as with most nuclear anything-related posts on /.
The RBMK reactors have a positive void coefficient. The rod control mechanisms had been manually disabled for the turbine coast-down experiment (because they kept ramming in the rods, something which should have served as a Big Clue to the operators that what they were doing was a bad idea). When the cooling water began to boil, the reactivity jumped due to that positive void coefficient and the power level spiked 3-4 orders of magnitude in some milliseconds. That flashed the cooling water into steam, which exploded and blew the top off the roof. The 3,000+ degree graphite moderator was now exposed to open air and burst into flame and it was good night, Gracie.
Read Medvedev's book. Hell, read _any_ book.
Learn to spell: nickel, missile, lose, solely, amendment, speech, kernel, probably, ridiculous, deity, hierarchy, versus
There is another of that design under construction in Cuba.
The graphite moderator reactor has a positive temperature coefficient, so it is inherently unstable. The fact that the graphite burns isn't too neat either.
The only good weather is bad weather.
TMI was nothing like Chernobyl. Going to the dentist for an x-ray gives you more dangerous radiation than just about anybody got from TMI. Nobody died because of TMI.
The observed shining was caused by white-hot burning graphite.
Cherenkov radiation is not observed in air (you need particles with mass traveling with speed higher than the speed of light in given medium , and the optical density of air is low (close to vacuum), the particles would have to travel at speeds near to c - which are difficult to obtain because of relativistic effects. (You can get that from accelerators, but not from fission)
You can see Cherenkov typicaly in water - the blue shine around immersed fuel rods or intense radioisotope source.
There is similar-looking bluish shine/flash around extremely strong sources, like criticality accident with Pu, U, or in nuclear explosion (the mushroom has bluish envelope). This shine is caused by intense ionisation of air molecules by radiation, mostly X-ray. The recombination of ions produces excited states whis give away the surpluss of energy by emission in UV/vis , which also appears bluis white.
I doubt that we will ever figure out - and I suspect that even if we did figure out we couldn't do much about it
The situation at TMI was pretty serious. Although no one died, the fuel rods in the core of the reactor did melt. That's how hot it was. There was a lot of contamination inside of the containment building (it served its designed purpose) and it took a long time to clean it up.
Here is zipped copy of the entire thing, including a fix of page 16 (+ links) mentioned by another /.'er below. I wanted a personal copy, figured I would offer it to anyone else who wanted to keep this excellent site...
I lived not that far from Cernobyl. I was 8 at the time. When it happened it was so downplayed that nobody outside that small area realized the impact, until much later. It was on the evening news and it was a 5 minute thing, my dad was a little worried but said it's probably something minor. They showed a cloud of smoke comming from the place and that's all, then other daily news followed. I also remember later, my mom saying how that year many of her plants outside had died, don't know if it is related or not. The worst is when the government had asked for volunteers to help clean-up the mess and promised appartments for those who sign up. They didn't say that when they come home to those new appartments, they won't have that time much to enjoy them. There were rumours how people with heavy doses where "cooked" that the skin and meat was comming of their bones and they couldn't even feel that.
Yeah.. Lesson One is don't use an RBMK reactor with no secondary containment. Current (and future) designs have Fail-Safe systems where, should the control system fail, the whole shebang fails into a "safe" mode (control rods are dropped which effectively stops the reaction and free-flowing coolant is delivered to alleviate residual core heat). TMI would have failed safe, except for incorrect operator intervention.
Chernobyl was also utilized to produce weapons-grade plutonium as well as civilian electricity, which is why the graphite moderator was used (instead of water, as in US civilian designs). When the graphite burned, the temperature shot up very quickly and the reactor exploded through the pressure-seal which was the only line of defense (not the reinforced concrete secondary containment vessel in Western designs). TMI showed how well that design could withstand both an incident and poor handling of that incident.
I have something in common with Stephen Hawking...
Nuclear safety always should be more than just a guy with a rubber stamp - hopefully three mile island and the subsequent court case changed all of that.
Those who think nuclear accidents can never happen in the good old USA should consider superior or more expensive technology is worthless if the lowest bidding contactors don't even do the job, and no-one is there to see that they haven't done the job.
Different situation, different outcome, but we can learn from both, so long as we stick to the technical instead of the emotional, and keep nationalism out of it. The lesson I get from Three Mile Island is to watch your contractors - they may not care if what they do can result in a major catastrophe. The lesson I get from Chernobyl is that a steam explosion is far more catastropic when nuclear material can get scattered around - so the design has to avoid that and try to bring it down to a less major incident.The main problem with nuclear power today is we keep having to subsidise the plants we have - shutting them down is usually a bigger problem than keeping them going. We just have to pour cash in to keep this 1950's white elephant going - at least in the UK where they are not supported by the same weird financial misdirection that makes the US plants appear to make a profit. Maybe when defence in the USA gets pissed off and wants a bit more of their own budget it will also become clear to people in the USA nuclear plants are made up of a lot of expensive parts and require expensive maintainance - it's not a cheap way to boil water.
From what I read about the Chernobyl disaster it wasn't really the reactor design that was at fault but the dangerous experiments that were being carried out at the time.
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"The disaster began with a routine operation for maintenance and fuel change that commenced a day before the accident. In addition to these procedures, the technical crew wanted to perform a test of the plant's steam turbines. Their goal was to determine if the turbines would continue to provide power for the plant's safety systems after their steam supply was cut off. While attempting to perform this test, they committed a series of errors that culminated in catastrophe. More than simple blunders, the errors stemmed from a reckless disregard for safety procedures. The errors compounded, and the disaster would likely not have occurred if any one error had been avoided.
The crew began by reducing the reactor's power so they could start their experiment. They also switched off the reactor's emergency core cooling system. This meant that in the event of a malfunction the reactor would become dangerously hot, which is exactly what subsequently happened. At 12:28 A.M. the crew made another serious error by putting the reactor's regulator at much too low a setting for the planned experiment. At this point, the reactor should have been shut down and the experiment abandoned, but the crew feared a reprimand for the incorrect regulator setting, so they decided to bring the reactor back up to power. To do this, they removed most of the graphite rods that moderated the fissioning of nuclear materials in the reactor core. By 1:00 A.M., the power output had reached 200 MW, still too low for the experiment. At this point, they switched on two extra pumps for the circulation of more cooling water in the core. This action made the reactor highly unstable, and water and steam levels began to oscillate uncontrollably. The crew then made another major mistake by blocking the automatic shut-down system. At 1:23, they started their experiment, and a few seconds later they switched off the safety apparatus that would have come into operation as soon as the turbines stopped.
In less than a minute, the crew chief realized that he had a serious problem, and he ordered the graphite rods to be reinserted in the core. The rods did not fall home, probably because the rods or the nuclear fuel had been distorted by the heat. The rods were then disconnected so that they could fall into the core, but by this time the situation was hopeless. The reactor's power surged from 7 percent to several hundred times its normal level. An explosion rocked the core, followed by another one 4 seconds later. These explosions blew the roof off of the reactor and caused the collapse of a refueling crane into the core, destroying what was left of the cooling system. A reaction of the steam with the fuel rods' zirconium cladding caused the formation of hydrogen, which then ignited, setting off 30 separate fires through the plant. The graphite in the core also ignited."
http://www.fofweb.com/Subscription/Sci
Actually, it *was* partly the reactor design that was to blame, as well as operator error.
The Chernobyl design had control rods entering the core from top and bottom. This particular design causes the reactor to have, in certain operating regions, a positive temperature coefficient of reactivity (like positive feedback for you non-nukes.) This has the effect of the reactor power level rising in response to a rise in temperature - and in response to the bottom control rods rising into the core.
Western designs are almost all designed to have a negative temperature coefficient of reactivity in operating regions.
What happened was, as the reactor temperature rose, power followed, such that when they finally tried to shutdown the reactor, reactor power level shot way up (basically, the reactor went prompt critical - some experts have said that the reactor went prompt supercritical - I'm not sure myself since I'd have to go back and research the values for beta and beta-bar that Chernobyl was designed to.) As a result, the power level exceeded design values by a couple hundred times, and the resulting step rise in temperature and pressure caused a massive steam void to form in the reactor, which promptly escaped by rupturing the top of the reactor.
Had Chernobyl been built to western designs the disaster wouldn't have happened.
1. Cooling and fuel channels containing thousands of welded joints through which the coolant continually passes vs. a western design consisting of a single pressure vessel that holds the majority of the coolant covering the core with a few loops to circulate water to the steam generators. This makes the design much more prone to a leak in an inaccessible location.
2. Using graphite instead of water. Graphite has its uses - a power reactor is not one of them.
3. A positive temperature coefficient of reactivity. If you do *nothing* else, make sure your design has a negative coefficient in all operating regions.
4. A flimsy steel shed vs. a proper containment. Even when the reactor suffered a steam explosion, a proper containment structure would have caused Chernobyl to be a localized accident resulting in the contamination of the inside of the containment structure, instead of a disaster affecting the entire world.