According to the test parameters, the thermal output of the reactor should have been no lower than 700 MW at the start of the experiment. [...] The day shift workers had been instructed in advance and were familiar with the established procedures. A special team of electrical engineers was present to test the new voltage regulating system. [...] The Chernobyl plant director [...] postponed the test. Despite this postponement, preparations for the test not affecting the reactor's power were carried out, including the disabling of the emergency core cooling system or ECCS, a passive/active system of core cooling intended to provide water to the core in a loss-of-coolant accident. Given the other events that unfolded, the system would have been of limited use
At 23:04, the Kiev grid controller allowed the reactor shutdown to resume. This delay had some serious consequences: the day shift had long since departed, the evening shift was also preparing to leave, and the night shift would not take over until midnight, well into the job. According to plan, the test should have been finished during the day shift, and the night shift would only have had to maintain decay heat cooling systems in an otherwise shut-down plant.
As the reactor power output dropped further, to approximately 500 MW, Toptunov mistakenly inserted the control rods too far—the exact circumstances leading to this are unknown because Akimov and Toptunov died in the hospital on May 10 and 14, respectively. This combination of factors rendered the reactor in an unintended near-shutdown state, with a power output of 30 MW thermal or less.
The reactor was now only producing around 5 percent of the minimum initial power level established as safe for the test.[28]:73 Control-room personnel consequently made the decision to restore power by disabling the automatic system governing the control rods and manually extracting the majority of the reactor control rods to their upper limits.[32] Several minutes elapsed between their extraction and the point that the power output began to increase and subsequently stabilize at 160–200 MW (thermal), a much smaller value than the planned 700 MW.
The operation of the reactor at the low power level and high poisoning level was accompanied by unstable core temperature and coolant flow, and possibly by instability of neutron flux. Various alarms started going off at this point. The control room received repeated emergency signals regarding the levels in the steam/water separator drums, and large excursions or variations in the flow rate of feed water, as well as from relief valves opened to relieve excess steam into a turbine condenser, and from the neutron power controller. In the period between 00:35 and 00:45, emergency alarm signals concerning thermal-hydraulic parameters were ignored, apparently to preserve the reactor power level.
The flow exceeded the allowed limit at 01:19, triggering an alarm of low steam pressure in the steam separators. [...] Nearly all of the control rods were removed manually, including all but 9 of the "fail-safe" manually operated rods,[clarification needed] which were intended to remain fully inserted to control the reaction even in the event of a loss of coolant. While the emergency SCRAM system that would insert all control rods to shut down the reactor could still be activated manually, the automated system that could do the same had been disabled to maintain power, and many other automated and even passive safety features of the reactor had been bypassed.
To say that it was "way too easy" is grossly wrong. While they were unaware of a number of the mechanics through which different events happened, they had to explicitly disable most of the safety systems and do the test anyway way under the minimum proscribed powerlevel.
Of course they *can* still explode. Why Chernobyl did was because they were operating it in unsafe ways that even they were aware of at the time they probably shouldn't have been.
Mistakes were made, but they are taking responsibility for the mess. This is what is needed for Nuke Inc. USA and Japan. Get it done
What the hell is this supposed to mean? We should get around to building our own sarcophagus properly over *our* Chernobyl? Oh, that's right...we didn't have one.
Or are you saying the US should take responsibility for Japan's Fukushima reactors? Why?
While both incidents are classified as INES level 7, that seems rather misleading...every quoted statistic related to damage caused is at least 4x more for Chernobyl. And they say 80% of the Fukushima radiation ended up in the Pacific Ocean, as opposed to being scattered mostly across populated areas of Europe.
They didn't actually decommission all the rest of the reactors until 2000, either. Must have been "interesting" working there afterwards.
reactor 1 -- decommissioned 1996 reactor 2 -- fire broke out and shut down in 1991 reactor 3 -- shut down 2000 reactor 4 -- destroyed 1986
Huh...apparently 3 and 4 were actually second-generation RBMKs.
Reactor Nos. 3 and 4 were second generation units, whereas Nos. 1 and 2 were first-generation units (like those in operation at Kursk Nuclear Power Plant). Second-generation RBMK designs were fitted with a more secure accident localization system, as can be seen in pictures. It is fortunate that the accident happened in a second-generation unit; if it had happened in a first-generation unit, it could have been even more devastating. Today, many countries that were in the Soviet Union have been paid money from the European Union to shutdown such first-generation units, as they pose a threat to the environment.[citation needed]
A bigger problem was a flawed graphite-tip control rod design, which initially displaced neutron-absorbing coolant with moderating graphite before introducing replacement neutron-absorbing boron material to slow the reaction.
Because of the positive void coefficient of the RBMK reactor at low reactor power levels, it was now primed to embark on a positive feedback loop, in which the formation of steam voids reduced the ability of the liquid water coolant to absorb neutrons, which in turn increased the reactor's power output. This caused yet more water to flash into steam, giving yet a further power increase. During almost the entire period of the experiment the automatic control system successfully counteracted this positive feedback, continuously inserting control rods into the reactor core to limit the power rise. However, this system had control of only 12 rods, and nearly all others had been manually retracted.
Okay, I somewhat take back my reply...it was indeed partly a reactor design flaw. We have to read through a long list of really bad signs that should have given the operators pause to get to the bit of technobabble that actually says that, though. (Modern reactors are of course designed to have a *negative* void coefficient so that they are a lot more fail-safe.)
The only way I can see Chernobyl as "due to design flaws" was because the whole reason for the test was trying to remedy one of the flaws. The operators sound like they were very much aware of the limitations involved.
From the Wikipedia article, the plant manager knew they were operating it unsafely but they were trying to use the test to find a solution to a standing safety issue (the reactor would have no access at all to power for the first 60-75 seconds after a primary power loss, contrary to design). The test as performed was actually flagrantly against safety protocols (because it was below 700 MW at time of test). And it sounds like they were aware of the spike that would happen upon SCRAM as well, which was exactly what happened but I bet the operators realized they were fucked anyway at that point.
They also had issues where the test was postponed so the personnel who had been thoroughly briefed had left and the next shift was preparing to leave as well.
In summary, they could have done the test safely if they had done it differently. The reactors weren't good compared to now, but they did have safety features that would have worked if they hadn't done 4 or 5 bad things during the setup.
Which 4 incidents per century are you thinking of? I thought Chernobyl was the only one to really be that bad? (as I thought Fukushima destroyed the reactors but didn't actually release much radioactivity...and Three Mile Island was comparatively very minor...)
I get the point you're making but I'm not sure why you're hammering on the "equivalent of 1/3 of all the earth's current biomass" bit. It's a lot of harmful output, yeah, but comparing the energy to some other source doesn't really seem useful. And you imply that switching to biomass use directly would be totally infeasible, which could be used by some to say, "Well, we'd better keep using fossil fuels then."
This is a rather nitpicky issue, so feel free to ignore me.
If it takes basically an Act of God to breach the safety precautions of a nuclear reactor these days, I feel pretty good about the state of the industry.
And Chernobyl happened because they were purposely ignoring several key safety rules in the operation of an almost-first-gen reactor outside its designed limits.
Let's just extend the analogy to include a third party stretching a layer of saran wrap over the top of the pot so the frog can't jump out. I'm sure you don't have to think too hard to come up with some group that that represents.
It actually came in handy recently when I found my old PGP private key on an old hard drive that I had simply imaged to my backup server rather than clean out.
Yeah, that's a very good point. I've had to resort to this several times when I accidentally the wrong partition.
Conventional (pre-BD-XL) Blu-ray Discs contain 25 GB per layer, with dual layer discs (50 GB) being the industry standard for feature-length video discs. Triple layer discs (100 GB) and quadruple layers (128 GB) are available for BD-XL re-writer drives.
All I'm seeing in these reviews is a bunch of off-the-wall fiction completely unconnected to reality. Is this a joke?
1 star I've been saving up for over 14 lifetimes to purchase this box to help me record home movies, however I was very dissapointed with the product, as upon opening it burst into an array of colors to the likes of which I'd never seen, cured my mono, cured my dog's mono, gave me x-ray vision, allowed me to fly, raised my IQ by over 170 points, gave me the power of invincibility, gave me the power of invisibility, crafted me a working Iron Man Suit, and above all made me a sandwich that tasted like dreams. It did all these things but it didn't even work right when I tried to use it for my home movies with my dog. I threw it out yesterday.
Slashdot Mirror
According to the test parameters, the thermal output of the reactor should have been no lower than 700 MW at the start of the experiment. [...] The day shift workers had been instructed in advance and were familiar with the established procedures. A special team of electrical engineers was present to test the new voltage regulating system. [...] The Chernobyl plant director [...] postponed the test. Despite this postponement, preparations for the test not affecting the reactor's power were carried out, including the disabling of the emergency core cooling system or ECCS, a passive/active system of core cooling intended to provide water to the core in a loss-of-coolant accident. Given the other events that unfolded, the system would have been of limited use
At 23:04, the Kiev grid controller allowed the reactor shutdown to resume. This delay had some serious consequences: the day shift had long since departed, the evening shift was also preparing to leave, and the night shift would not take over until midnight, well into the job. According to plan, the test should have been finished during the day shift, and the night shift would only have had to maintain decay heat cooling systems in an otherwise shut-down plant.
As the reactor power output dropped further, to approximately 500 MW, Toptunov mistakenly inserted the control rods too far—the exact circumstances leading to this are unknown because Akimov and Toptunov died in the hospital on May 10 and 14, respectively. This combination of factors rendered the reactor in an unintended near-shutdown state, with a power output of 30 MW thermal or less.
The reactor was now only producing around 5 percent of the minimum initial power level established as safe for the test.[28]:73 Control-room personnel consequently made the decision to restore power by disabling the automatic system governing the control rods and manually extracting the majority of the reactor control rods to their upper limits.[32] Several minutes elapsed between their extraction and the point that the power output began to increase and subsequently stabilize at 160–200 MW (thermal), a much smaller value than the planned 700 MW.
The operation of the reactor at the low power level and high poisoning level was accompanied by unstable core temperature and coolant flow, and possibly by instability of neutron flux. Various alarms started going off at this point. The control room received repeated emergency signals regarding the levels in the steam/water separator drums, and large excursions or variations in the flow rate of feed water, as well as from relief valves opened to relieve excess steam into a turbine condenser, and from the neutron power controller. In the period between 00:35 and 00:45, emergency alarm signals concerning thermal-hydraulic parameters were ignored, apparently to preserve the reactor power level.
The flow exceeded the allowed limit at 01:19, triggering an alarm of low steam pressure in the steam separators. [...] Nearly all of the control rods were removed manually, including all but 9 of the "fail-safe" manually operated rods,[clarification needed] which were intended to remain fully inserted to control the reaction even in the event of a loss of coolant. While the emergency SCRAM system that would insert all control rods to shut down the reactor could still be activated manually, the automated system that could do the same had been disabled to maintain power, and many other automated and even passive safety features of the reactor had been bypassed.
To say that it was "way too easy" is grossly wrong. While they were unaware of a number of the mechanics through which different events happened, they had to explicitly disable most of the safety systems and do the test anyway way under the minimum proscribed powerlevel.
Of course they *can* still explode. Why Chernobyl did was because they were operating it in unsafe ways that even they were aware of at the time they probably shouldn't have been.
Mistakes were made, but they are taking responsibility for the mess. This is what is needed for Nuke Inc. USA and Japan. Get it done
What the hell is this supposed to mean? We should get around to building our own sarcophagus properly over *our* Chernobyl? Oh, that's right...we didn't have one.
Or are you saying the US should take responsibility for Japan's Fukushima reactors? Why?
Because I'm sure they're lying about how much concrete they used rather than they just did it so hurriedly nobody kept accurate records.
While both incidents are classified as INES level 7, that seems rather misleading...every quoted statistic related to damage caused is at least 4x more for Chernobyl. And they say 80% of the Fukushima radiation ended up in the Pacific Ocean, as opposed to being scattered mostly across populated areas of Europe.
http://en.wikipedia.org/wiki/C...
Ah, this is the one I was thinking of but couldn't find: Kyshtym disaster
For some reason, it's mentioned in the list but not the table at http://en.wikipedia.org/wiki/N...
http://en.wikipedia.org/wiki/I...
They didn't actually decommission all the rest of the reactors until 2000, either. Must have been "interesting" working there afterwards.
reactor 1 -- decommissioned 1996
reactor 2 -- fire broke out and shut down in 1991
reactor 3 -- shut down 2000
reactor 4 -- destroyed 1986
Huh...apparently 3 and 4 were actually second-generation RBMKs.
Reactor Nos. 3 and 4 were second generation units, whereas Nos. 1 and 2 were first-generation units (like those in operation at Kursk Nuclear Power Plant). Second-generation RBMK designs were fitted with a more secure accident localization system, as can be seen in pictures. It is fortunate that the accident happened in a second-generation unit; if it had happened in a first-generation unit, it could have been even more devastating. Today, many countries that were in the Soviet Union have been paid money from the European Union to shutdown such first-generation units, as they pose a threat to the environment.[citation needed]
http://en.wikipedia.org/wiki/C...
A bigger problem was a flawed graphite-tip control rod design, which initially displaced neutron-absorbing coolant with moderating graphite before introducing replacement neutron-absorbing boron material to slow the reaction.
Dammit again.
Because of the positive void coefficient of the RBMK reactor at low reactor power levels, it was now primed to embark on a positive feedback loop, in which the formation of steam voids reduced the ability of the liquid water coolant to absorb neutrons, which in turn increased the reactor's power output. This caused yet more water to flash into steam, giving yet a further power increase. During almost the entire period of the experiment the automatic control system successfully counteracted this positive feedback, continuously inserting control rods into the reactor core to limit the power rise. However, this system had control of only 12 rods, and nearly all others had been manually retracted.
Okay, I somewhat take back my reply...it was indeed partly a reactor design flaw. We have to read through a long list of really bad signs that should have given the operators pause to get to the bit of technobabble that actually says that, though. (Modern reactors are of course designed to have a *negative* void coefficient so that they are a lot more fail-safe.)
The only way I can see Chernobyl as "due to design flaws" was because the whole reason for the test was trying to remedy one of the flaws. The operators sound like they were very much aware of the limitations involved.
From the Wikipedia article, the plant manager knew they were operating it unsafely but they were trying to use the test to find a solution to a standing safety issue (the reactor would have no access at all to power for the first 60-75 seconds after a primary power loss, contrary to design). The test as performed was actually flagrantly against safety protocols (because it was below 700 MW at time of test). And it sounds like they were aware of the spike that would happen upon SCRAM as well, which was exactly what happened but I bet the operators realized they were fucked anyway at that point.
They also had issues where the test was postponed so the personnel who had been thoroughly briefed had left and the next shift was preparing to leave as well.
In summary, they could have done the test safely if they had done it differently. The reactors weren't good compared to now, but they did have safety features that would have worked if they hadn't done 4 or 5 bad things during the setup.
http://en.wikipedia.org/wiki/C...
Which 4 incidents per century are you thinking of? I thought Chernobyl was the only one to really be that bad? (as I thought Fukushima destroyed the reactors but didn't actually release much radioactivity...and Three Mile Island was comparatively very minor...)
I get the point you're making but I'm not sure why you're hammering on the "equivalent of 1/3 of all the earth's current biomass" bit. It's a lot of harmful output, yeah, but comparing the energy to some other source doesn't really seem useful. And you imply that switching to biomass use directly would be totally infeasible, which could be used by some to say, "Well, we'd better keep using fossil fuels then."
This is a rather nitpicky issue, so feel free to ignore me.
If it takes basically an Act of God to breach the safety precautions of a nuclear reactor these days, I feel pretty good about the state of the industry.
And Chernobyl happened because they were purposely ignoring several key safety rules in the operation of an almost-first-gen reactor outside its designed limits.
Let's just extend the analogy to include a third party stretching a layer of saran wrap over the top of the pot so the frog can't jump out. I'm sure you don't have to think too hard to come up with some group that that represents.
Permanent for our purposes. Is civilization going to still be around in ten thousand years, let alone several billion?
Oh, now you're tempting me to call a fallacy on your invocation of a fallacy to say his data fallaciously called your data a fallacy.
It actually came in handy recently when I found my old PGP private key on an old hard drive that I had simply imaged to my backup server rather than clean out.
Yeah, that's a very good point. I've had to resort to this several times when I accidentally the wrong partition.
(still the most widely used browser) and (probably used by 98% of the people stupid enough to use Yahoo for anything)
are two different clauses. If they weren't, he would have said:
still the browser most widely used by 98% of the people stupid enough to use Yahoo for anything
Internet Explorer, still the most widely used browser
No.
http://en.wikipedia.org/wiki/I...
http://en.wikipedia.org/wiki/B...
Conventional (pre-BD-XL) Blu-ray Discs contain 25 GB per layer, with dual layer discs (50 GB) being the industry standard for feature-length video discs. Triple layer discs (100 GB) and quadruple layers (128 GB) are available for BD-XL re-writer drives.
All I'm seeing in these reviews is a bunch of off-the-wall fiction completely unconnected to reality. Is this a joke?
1 star
I've been saving up for over 14 lifetimes to purchase this box to help me record home movies, however I was very dissapointed with the product, as upon opening it burst into an array of colors to the likes of which I'd never seen, cured my mono, cured my dog's mono, gave me x-ray vision, allowed me to fly, raised my IQ by over 170 points, gave me the power of invincibility, gave me the power of invisibility, crafted me a working Iron Man Suit, and above all made me a sandwich that tasted like dreams. It did all these things but it didn't even work right when I tried to use it for my home movies with my dog. I threw it out yesterday.
But what's the point of recording your entire life if you have no bookmarks to get to the interesting parts?
What I'm more curious about is how the hell you end up with 75GB of text documents.
shields, such as those seen protecting spaceships in the Star Wars film series
won't be able to see a thing outside of your starfighter.
These two statements are incompatible.
So, more or less like any enemies they encountered in Enterprise, then ;-)
Seriously, it seemed like the hull plating could only ever take one hit without depolarizing.
They're all still stupid things to patent.