bsimic@fesb.hr

UPDATE: The pressure required to lift up the upper biological shield is 3,1 bar. (actual pressure is held between 0,7 and 0,9 bar during normal operation). I don't know whether these pressures are ABSOLUTE or GAUGED, sorry.

@ Steve Savage: ...

UPDATE: The pressure required to lift up the upper biological shield is 3,1 bar. (actual pressure is held between 0,7 and 0,9 bar during normal operation). I don't know whether these pressures are ABSOLUTE or GAUGED, sorry.

@ Steve Savage: In the TMI accidend melted fuel never left the reactor vessel, but even if it did, there was still the containment building. There was no explosion, whatsoever.

Posted by Guest on Fri 01 Jan 2010 18:14:45 PST

Scott

I wouldn't lay the blame for this disaster entirely on the communist party. There are plenty of examples of capitalist entities that have been lack in safety standards, construction designs and training.

And there are also plenty of...

I wouldn't lay the blame for this disaster entirely on the communist party. There are plenty of examples of capitalist entities that have been lack in safety standards, construction designs and training.

And there are also plenty of examples of democratic governments bungling disaster relief "Katrina" anyone.

The bottom line for me is that there probably isn't ANY nuclear power plant on the planet that is 100% safe.

And while it might be the "safest and most efficient" way to generate power, all it takes is one huge catastrophe to kill hundreds of thousands of people. Its difficult to say that about say--a coal power generating station.

And I'd also point out that Chernobyl, as much of a cluster fuck as it was, could have been much MUCH worse. When the Soviet government finally responded they did a pretty good job of saving the Ukraine and Belarus.

Posted by Guest on Thu 01 Oct 2009 15:26:47 PDT

bsimic@fesb.hr

To timi: I don't believe in that! If the Russians were conducting such experiments, these were on much smaller scale and had nothing to do with the Chernobyl disaster! The reactor containment building wasn't built simply because of high costs and the...

To timi: I don't believe in that! If the Russians were conducting such experiments, these were on much smaller scale and had nothing to do with the Chernobyl disaster! The reactor containment building wasn't built simply because of high costs and the reactor explosion took place due to operational error made by operators who didn't know enough about the reactor operation.

Posted by Guest on Sun 08 Feb 2009 16:08:53 PST

timi

well there have been reports from workers that the russian government let out radiation into the atmoshpere to see how they would cope if there ever was a nuclear war.

Posted by Guest on Wed 14 May 2008 16:25:26 PDT

bsimic@fesb.hr

To Snyder: don't be too impressed by the weight of the upper biological shield. The gas pressure which is only one atmosphere higher on the bottom side than on the top side is enough to lift it up if it was set loose! The fuel channels simply ruptured...

To Snyder: don't be too impressed by the weight of the upper biological shield. The gas pressure which is only one atmosphere higher on the bottom side than on the top side is enough to lift it up if it was set loose! The fuel channels simply ruptured due to excess steam production and pressure increased inside the reactor vessel. This was enough to 'pop' the top lid and create a disaster.

Posted by Guest on Sun 27 Jan 2008 18:28:01 PST

bsimic@fesb.hr

It is believed among scientists and engineers that the containment building made by the western standards at the time of the construction of the reactor would sustain the explosion at the reactor 4 and contain the radiation inside.

Posted by Guest on Sun 27 Jan 2008 18:18:13 PST

bsimic@fesb.hr

To wildespace: is the amount of reaction controlled by the depth the control rods are inserted to the core? Could the tips of the rods be made of graphite to make the reactor control more extensible?

Posted by Guest on Sun 27 Jan 2008 18:14:55 PST

nuke worker

nuclear power is still the safest energy and most efficiant source of energy around

Posted by Guest on Fri 21 Sep 2007 08:21:13 PDT

wildespace

When are people going to stop saying "graphite control rods"? The control rods in Chernobyl reactor were made of boron. Their role was to ABSORB neutrons to hamper the reaction, NOT to moderate it like graphite does. Graphite was actually on the ends of...

When are people going to stop saying "graphite control rods"? The control rods in Chernobyl reactor were made of boron. Their role was to ABSORB neutrons to hamper the reaction, NOT to moderate it like graphite does. Graphite was actually on the ends of the control rods, and it's purpose was to stop the coolant goin in when the control rods were being extracted. By itself, it wasn't a flaw, the flaw was in the dact that the graphite tips didn't cover the whole length of the rod channel, and some coolant was still present at the bottom when the rods were fully extracted. Once the SCRAM button was pressed, the graphite tips displaced that bit of coolant and caused a spike in reaction.

Posted by Guest on Sun 16 Sep 2007 14:38:19 PDT

Christian

Chernobyl is a fantastic insight into the workings of the old soviet communist party.

Ignored warnings, arrogance, and rushed, flawed designs show how there were no checks and balances- commands came from the top down, and were followed...

Chernobyl is a fantastic insight into the workings of the old soviet communist party.

Ignored warnings, arrogance, and rushed, flawed designs show how there were no checks and balances- commands came from the top down, and were followed without question. Decisions were made by people who weren't qualified simply because they were in power.

The operators of the power plant at the time WEREN'T EVEN TRAINED IN REACTOR OPERATIONS. That says something right there. The fateful 'test' was carried out by an undermanned, inexperienced skeleton crew at night.

They didn't even understand reactor poisoning. No one but the designers at the time knew about the flaws with control rod design. The entire operation of an RBMK reactor is counter-intuitive, as they are extremely unstable at low-power settings (due to the high positive void coefficient among other things).

RBMK reactors are NOT good designs- the reason being you MUST factor in operational dangers such as user error in the reactor design. A gun is an inherently stable object, and very safe IN THE RIGHT HANDS. Same with a reactor. There should have been qualified personnel on staff that would have had authority to cancel the test.

There are several reactor simulators on the net you can download and play with- I am putting the finishing touches on one myself.

In response to another post- it does not take months to refuel a U.S. PWR reactor- The reactor must be shut down for a few days. Interestingly, since the fuel does not actually come in contact withe moderator/coolant water- In a few days the radioactivity in the water is all but gone, and divers can actually enter the core and perform maintainance/repairs before the fuel is reinsterted.

Posted by Guest on Mon 14 May 2007 08:16:56 PDT

Aled

Some amazing photos in this gallery, certainly interesting and show only a small insight into the true horror of what happened. Seeing as there are some people here who know what they are talking about, are there any people actually involved in the...

Some amazing photos in this gallery, certainly interesting and show only a small insight into the true horror of what happened. Seeing as there are some people here who know what they are talking about, are there any people actually involved in the Nuclear Physics industry? I guess it's not to wide compared to other physics based sectors but I'm just wondering. I've been interested in it for sometime, and still have a few years to think about it and I was wondering if anyone had any information about it.

Posted by Guest on Wed 25 Apr 2007 10:46:43 PDT

jdd

It is impossible for a nuclear reactor to detonate in a nuclear reaction not only because the uranuim is at a level of insufficient enrichment, but also there would be no way to compress the core into a Critical Mass. (unless of course a black hole...

It is impossible for a nuclear reactor to detonate in a nuclear reaction not only because the uranuim is at a level of insufficient enrichment, but also there would be no way to compress the core into a Critical Mass. (unless of course a black hole suddenly formed in the middle of the reactor, in which case a nuclear explosion is not the biggest problem...)

Also, the RMBK design features (get this) VERTICAL COOLANT PIPES! if you have not already figured it out (which I expect most of you have) this leads to much easier steam buildup.
steam buildup means that coolant flow is restricted, this is not good...
then of course, some dope activated SCRAM and inserted a bunch of graphite control rods part of the way into the reactor core. (for those of you who dont know, graphite accelerates a nuclear reaction by slowing down the neutrons, this might not make sense to those of you who are not nuclear phisicists... but trust me, it's true.)
having inserted the control rods the thermal output spiked by AN ORDER OF MAGNITUDE (from 3ish GWs, to 30ish GWs)
Gues what happens if you put off 30 GigaWatts of heat into a vertical coolant pipe in which coolant flow is already decellerated? (the answer is painfully obvious...)

Posted by Guest on Tue 03 Apr 2007 13:28:45 PDT

Geat

The problem with Three Mile Island was that the instrument panels only showed what instructions had been executed, not if they had been run successfully. The operators invoked the closing of a safety valve, and that's what the panel showed them had...

The problem with Three Mile Island was that the instrument panels only showed what instructions had been executed, not if they had been run successfully. The operators invoked the closing of a safety valve, and that's what the panel showed them had happened, but in actual fact the valve had malfunctioned - this exposed some of the core and lead to it melting. Modern systems presumably remedy this...

Posted by Guest on Thu 29 Mar 2007 14:00:00 PDT

Steve Savage

The Three Mile Island core did not suffer a "partial meltdown". In fact the entire core melted and pooled at the bottom of the containment vessel.
Would you call that a safe design, I wouldn't. I've always wondered why we would trust mere...

The Three Mile Island core did not suffer a "partial meltdown". In fact the entire core melted and pooled at the bottom of the containment vessel.
Would you call that a safe design, I wouldn't. I've always wondered why we would trust mere civilians with such dangerous things as nuclear power plants. They should all be run by military/government. Security is another issue, since its only a matter of time before a terrorist detonates a truck bomb next to a reactor vessel due to a poorly guarded plant facility.

Posted by Guest on Tue 30 Jan 2007 07:33:29 PST

Jakg

Oh my god, ive been to another reactor, and seen the UBS, it was huge - to think that that could be moved by an explosion is scarcely imaginable

Posted by Guest on Tue 09 Jan 2007 12:03:21 PST

$H@KTI

I have a question.On pictures you only see a gap in the roof and wall,butt what aboud other parts of the building such as the spent fuel pool and the foundation??how heavy is this damaged?And if you pour concrete arround the core can this help inother 2...

I have a question.On pictures you only see a gap in the roof and wall,butt what aboud other parts of the building such as the spent fuel pool and the foundation??how heavy is this damaged?And if you pour concrete arround the core can this help inother 2 keep the bealding from falling appart,so workers can build the second layer on this heavy dammaged building!!!

Posted by Guest on Wed 03 Jan 2007 14:28:29 PST

zether

RBMK reactors are based on a channel design with each fuel element residing in its own reactor channel that can be isolated from the rest of the reactor for refueling and such, a slightly more complicated design that heavy water reactors and having...

RBMK reactors are based on a channel design with each fuel element residing in its own reactor channel that can be isolated from the rest of the reactor for refueling and such, a slightly more complicated design that heavy water reactors and having advantages of staying online while being refueled. with US reactors the whole thing has to be shut down for a period of time, i think like a few months or a year, in order to be refueld. RBMK reactors stay online producing power the whole time while only one fuel channel is shut down for refueling at a time. and yes, RBMK reactors in rusia were primarily designed for weapons production, but i doubt any comercial RBMK reactors are currently being used for that purpose

Posted by Guest on Tue 26 Sep 2006 23:11:33 PDT

zether

i do remember reading an extensive article based on the TMI-2 operators eyewitness accounts that they were fearfull of a large explosion in the reactor due to a large amount of hydrogen in the reactor core. they were saying that the explosion would...

i do remember reading an extensive article based on the TMI-2 operators eyewitness accounts that they were fearfull of a large explosion in the reactor due to a large amount of hydrogen in the reactor core. they were saying that the explosion would have a significant chance of rupturing the primary containment at which point only the secondary containment building would have been left.

Posted by Guest on Tue 26 Sep 2006 23:06:58 PDT

sarah

thanks, but what is the diffrence with the reactors why are some types better than others? if they are?

Posted by Guest on Mon 17 Jul 2006 08:09:54 PDT

us

There is no TMI reactor, but Three Mile Island Unit 2 (TMI-2) was as pressurized water reactor, that experienced partial core damage after losing coolant.

Btw, I doubt any containment could withstand a power surge as in Chernobyl. It...

There is no TMI reactor, but Three Mile Island Unit 2 (TMI-2) was as pressurized water reactor, that experienced partial core damage after losing coolant.

Btw, I doubt any containment could withstand a power surge as in Chernobyl. It doesn't matter, though, since PWRs and BWRs cannot experience power surges, they are stable in all credible conditions.

Posted by Guest on Tue 04 Jul 2006 12:40:17 PDT

sarah

can some one please explain what a TIM reactor is, and how is it better than the one at chernobyl. i dont no anything bout reactors so please keep it kinda simple, thanks

Posted by Guest on Wed 14 Jun 2006 19:23:24 PDT

gt04

Ik, can we remind Juan, it may be my poor old mind going a bit haywire, but was it not a TMI reactor that went cactus at Three Mile Island?? I pretty certain it was. But even still, nuclear generated power, and all its benefits and drawbacks, one would ...

Ik, can we remind Juan, it may be my poor old mind going a bit haywire, but was it not a TMI reactor that went cactus at Three Mile Island?? I pretty certain it was. But even still, nuclear generated power, and all its benefits and drawbacks, one would think, no matter what the type of reactor you use, it's ultimately the operators in most accidents, that either are not trained in the case of "What if this happens" scenarios, or the lack of knowledge to read the signs that the whole shebang is about to go bang. Its just it's a f@#$*n big bang usually. Thankfully, there haven't been to many, and hopefully won't be to many more.

Posted by Guest on Sun 11 Jun 2006 08:10:25 PDT

lk

@Tim In RBMK reactor design "Upper biological shield" is reactor lid (this massive 1000 tons heavy circle shaped thing: http://www.pavrda.cz/cernobyl/img/centralni_sal.jpg ) below it is the core itself.
This "shield" absorbs radiation, so it is...

@Tim In RBMK reactor design "Upper biological shield" is reactor lid (this massive 1000 tons heavy circle shaped thing: http://www.pavrda.cz/cernobyl/img/centralni_sal.jpg ) below it is the core itself.
This "shield" absorbs radiation, so it is actually possible to be top of this reactor when it is at 100% without being iradiated

Posted by Guest on Sun 21 May 2006 12:19:58 PDT

Tim

This may seem a dumb question but what is a Upper biological shild and what does it do. I know nothing about reactors so I'm clueless.

Posted by Guest on Wed 17 May 2006 13:55:07 PDT

duralinux

Any reactor design with a positive void coefficient is a poor design as there is virtually no way to stop the reaction if you loose either moderator. It's like playing Russian Rollette... no pun intended.

Posted by Guest on Thu 04 May 2006 15:59:41 PDT

lk

@juan
RBMK isn't "crappy" design. Soviets knew what they were doing. RBMK has very big advantages ("on the fly" refueling, natural uranium consumption (no heavy water required), plutonium production, high power output, low construction costs...)...

@juan
RBMK isn't "crappy" design. Soviets knew what they were doing. RBMK has very big advantages ("on the fly" refueling, natural uranium consumption (no heavy water required), plutonium production, high power output, low construction costs...) Unfortunately main disadvantage is positive void coefficient and lack of containment structure. These disadvantages result in poor safety and stability, and nuclear plant's simply can't be allowed to be unsafe.
And haven't you ever heared of TMI? France is the country everybody should learn from on this topic.

Posted by Guest on Wed 03 May 2006 13:52:45 PDT

Juan

lol thats funny.... but seriously that is a really crappy design.... they should learn from us Americans... jk

Posted by Guest on Wed 03 May 2006 11:15:52 PDT

CaseLogic

I stand corrected in regard to the crane. I read about them in an old norwegian article from 1988 or thereabouts, when the authors probably had to guess because the Soviet government wouldn't tell. :)
Anyhow, there seemed to be consencus about the...

I stand corrected in regard to the crane. I read about them in an old norwegian article from 1988 or thereabouts, when the authors probably had to guess because the Soviet government wouldn't tell. :)
Anyhow, there seemed to be consencus about the assumption that a good containment building would have survived the explosion, and that Chernobyl didn't have one because of the need for cranes.

Posted by Guest on Wed 19 Apr 2006 12:17:17 PDT

lk

Yes, another explosion occured minutes after the first (steam explosion).

But about this second explosion, some people say that liquid hydrogen ignited and exploded (liquid hydrogen is used to cool graphite core (moderator), it flows...

Yes, another explosion occured minutes after the first (steam explosion).

But about this second explosion, some people say that liquid hydrogen ignited and exploded (liquid hydrogen is used to cool graphite core (moderator), it flows through tight space between fuel channels and graphite, and between control rods and graphite).
Some other people say that second explosion was also a steam explosion, which happened when a peace of core at few thousand degrees melted through few floors below reactor and when it reached water pond (below reactor, used to store some cooling water), there was a steam explosion.

Posted by Guest on Tue 04 Apr 2006 03:51:46 PDT

Radrat

The Chernobyl explosion was a steam explosion, followed by a chemical explosion.

Posted by Guest on Mon 03 Apr 2006 13:31:39 PDT