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Old 10-13-2019, 09:35 PM   #25576
PhantomCruiser
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Originally Posted by Abdallah View Post
 Let's restart Chernobyl
Are you volunteering?

As far as I know; units 1 and 3 are viable, but way out of date. The cost of a restart plus updating the safety systems are pretty high. Just finishing WBN2 was 3 billion and 5 years over and beyond estimated cost (and it had already gone through hot functional testing before being put on hold). Just updating WBN1 to meet standards after Fukashima ran a refueling outage over by weeks (and millions), and we had years to prepare for it.

I don't have the numbers for Browns Ferry unit 1 handy, but it far exceeded the initial cost estimates to restart after the fire. But here's a safety tip: When looking for air leaks, don't use a candle... seriously...


Given that small modular reactors seem to be the future, unless there is an extremely high demand for electricity, I doubt that Chernobyl will ever be anything other than a historical site (under constant monitoring) for the next few centuries.

Last edited by PhantomCruiser; 10-13-2019 at 09:39 PM.
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Old 10-14-2019, 03:45 AM   #25577
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Originally Posted by PhantomCruiser View Post
 Are you volunteering?

As far as I know; units 1 and 3 are viable, but way out of date. The cost of a restart plus updating the safety systems are pretty high.
I don't know. Could an RMBK even be updated to modern safety standards? I assume that the RMBKs still operating are more just grandfathered in than actually running on a design that could get a permit for construction, even in Russia, today.
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Old 10-14-2019, 09:26 AM   #25578
Urwumpe
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Originally Posted by Linguofreak View Post
 I don't know. Could an RMBK even be updated to modern safety standards? I assume that the RMBKs still operating are more just grandfathered in than actually running on a design that could get a permit for construction, even in Russia, today.
Since they attempted it at Ignalina: No.

But the Ignalina powerplant operated with far less incidents than others, despite still being a major health risk for the people around it (like all RBMKs)

I think the problem already starts at the requirement to use a robust, explosion-resistant containment building, especially after Fukushima.
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Old 10-14-2019, 11:24 AM   #25579
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I am not a nuclear scientist.

Surely if a reactor cannot explode it needs no explosion proofing. Well, yeah, if.......the core collapses and forms a critical mass, then we can forget about negative void/power/whatever coefficient.

I just think that Ukraine should make it's next nuclear power plant Chernobyl itself, just with the RBMK replaced by a self-regulating uranium hydride reactor similar in size and looks. The biggest reason is just that it would be a cool way to preserve this historic station. The reactor can't explode, so no need for blast shell. But of course, core collapse and nuclear explosion needs thinking......a reactor that operates on pulses of prompt criticality.....it is already exploding as hard as it can, so no bigger explosion is possible.....can't say
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Old 10-14-2019, 12:42 PM   #25580
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Originally Posted by Abdallah View Post
 Surely if a reactor cannot explode it needs no explosion proofing. Well, yeah, if.......the core collapses and forms a critical mass, then we can forget about negative void/power/whatever coefficient.
Are you sure having tons of superheated water around is no explosion hazard?

Remember, in Chernobyl the nuclear reaction produced the energy, but the steam did the work.

German containment buildings have to be large and robust enough that all water inside the reactor vessel could suddenly evaporate without breaking the containment building ("Volldruck-Containment" in German).

While RBMKs only operate at about 7 MPa, its still twice as much as a steam train used to have at the peak of their performance (1.5-2 MPa). (Except the German DR H 02 1001 prototype, which operated at 12 MPa)
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Old 10-14-2019, 02:44 PM   #25581
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If a reactor is physically incapable of providing the energy, then steam is incapable of boiling violently and Chernobyl is incapable of exploding. You know, like a bomb that doesn't work.

That's why I thought, dropping a tiny subcritical ball of uranium in a moderated core and setting it off like a micro-nuke is kinda safe (if it's practical). The reactor is already exploding as hard as it can.

Last edited by Abdallah; 10-14-2019 at 03:02 PM.
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Old 10-14-2019, 04:11 PM   #25582
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Originally Posted by Abdallah View Post
 If a reactor is physically incapable of providing the energy, then steam is incapable of boiling violently and Chernobyl is incapable of exploding. You know, like a bomb that doesn't work.
But shouldn't the reactor also provide electrical power? How is it supposed to produce electrical power, if there is no thermal power?
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Old 10-14-2019, 06:19 PM   #25583
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If a reactor is physically incapable of providing the energy, then steam is incapable of boiling violently and Chernobyl is incapable of exploding. You know, like a bomb that doesn't work.
I think what you meant to say is "if the reactor is physically incapable of providing the energy necessary to produce an explosion that ruptures the pressure vessel". Which is basically the exact same thing as Urwumpe was saying all along when talking about an explosion-resistant containment building. It's a shield around the reactor designed to contain its energy output when it goes critical.

The thing that probably confuses you in all of this is that the energy released at critical mass of any reactor is magnitudes higher than the energy it is designed to put out at regular operation. "Going critical" isn't refering to the reactor itself, as in it is suddenly outputing more power than it could handle. It refers to a state of the fissile material itself. Reaching critical mass means that the chain reaction in the fissile fuel has gone out of control to a point that it is now *physically impossible* to stop it. The material will quite literally blow itself apart and release a lot of energy doing so, and there's nothing anybody can do about it anymore.

This is not a state you can run a reactor in by design, as you can't control the reaction at that point. As such, you cannot design a fission reactor to operate at that energy output. All you can do is build another layer of protection around it that can contain that energy.
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Old 10-14-2019, 08:39 PM   #25584
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Originally Posted by jedidia View Post
 It's a shield around the reactor designed to contain its energy output when it goes critical.

Actually reactors do go critical, in their engineering lingo. It is achieved by reaching zero reactivity or in other words, when the nuclear chain reaction is self-sustaining and no special neutron source is needed to keep it running.



What you mean there is supercriticality, which is usually the cause of criticality events: When the reactivity becomes positive and power increases without any control input.



No containment building is yet designed specifically to handle criticality events. When there is a supercritical event like the secondary chernobyl explosion happening, even a modern european containment building will not last long. Those events are not impossible with current reactor designs, but more unlikely for some reactor types than others.


But: when a full volume steam explosion happens, you can be sure that the remaining reactor will sure not be in any controlled state and fighting a criticality event will be very hard to impossible.
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Old 10-15-2019, 01:56 AM   #25585
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They are putting in solar farms at Chernobyl and IIRC also at Fukushima. There is a small 1 MW demonstration right by Unit 4.


Makes sense - large exclusion zones with uninhabitable real estate available and power lines capable of handling several GW of power to pipe it out.



This is also what is being done with station grounds after fossil plants are closed and torn down.
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