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Germany shuts down seven reactors‎ because of Fokushima

reuters.com

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Re: Germany shuts down seven reactors‎ because of Fokushima

#61

Post by scott_s »

jgrahamc wrote: post #16
bhousel wrote: post #9

This strikes me more as a political stunt by Merkel to rally the conservative base in Germany than anything else. Still, it doesn't surprise me that this is such a hot button issue right now. I've long been a supporter of nuclear power, but the events of the past week have made me start to reconsider a lot of my beliefs about its safety.

Which beliefs? That a nuclear power station situated in a major earthquake zone next to the coast could magically survive a 9.0 earthquake and a tsunami? Right now, we don't know how serious this situation is, it could be that this will end with a small amount of radiation leaked and four reactors that have to be decommissioned. Or it could end with a major environmental disaster. We simply don't know yet. I'd cautio…

I think saying "magically survive" is being uncharitable to bhousel. What it has made me reconsider is the notion that even if we're able to design a system to withstand the problems we do foresee, it still may fail because of the problems we don't foresee or considered too unlikely.

I know this is almost a tautology, but when the stakes are as high as a nuclear powerplant, it's important to consider. Nuclear powerplants are the poster-child of massively redundant fail-safes. If we (as a species) are not able to design a system to withstand natural disasters when we know the stakes are as high as possible, then maybe we shouldn't play that game. While a massive tsunami is rare, it's not necessarily rare on the time scale that we expect nuclear plants to be operational. Given our track record, perhaps we can expect a serious problem once every 50 years. That's really infrequent - but it still might be too frequent considering the consequences.

I haven't come to any conclusions, and I don't think bhousel has, either. But the past few days have given us more data to churn on.

Re: Germany shuts down seven reactors‎ because of Fokushima

#62

Post by ugh »

masklinn wrote: post #38

Germany's green party has been trying to kill the nukes there fore quite some time now: the SPD/Greens officially announced their desire to phase out all nuclear power in Germany in 2000, and two power plants had been shut down in 2003 and 2005 and were planned for dismantling. The CDU (Merkel's party) was an opponent to the phase-out, and has been very open about it since 2008, but I'm guessing they saw the writing…

The phase out seems to have become political consensus during the last years, there is only disagreement about the time table.

Re: Germany shuts down seven reactors‎ because of Fokushima

#63

Post by scott_s »

nakkiel wrote: post #36
jgrahamc wrote: post #16

Earlier quoted context omitted.

Which beliefs? That a nuclear power station situated in a major earthquake zone next to the coast could magically survive a 9.0 earthquake and a tsunami? Right now, we don't know how serious this situation is, it could be that this will end with a small amount of radiation leaked and four reactors that have to be decommissioned. Or it could end with a major environmental disaster. We simply don't know yet. I'd cautio…

Nuclear Plant vs. 9.0 Earthquake & Tsunami. I honestly wouldn't have bet on the Nuclear Plant only a week ago. I'll add that besides the headlines, Thailand is considering to cancel its 5 plants project. Fortunately, this simply means lobbying will be a bit more expensive.

Considering hindsight bias, it's difficult to really know what we would have considered likely.

Re: Germany shuts down seven reactors‎ because of Fokushima

#64

Post by paganel »

krschultz wrote: post #54
paganel wrote: post #32

Earlier quoted context omitted.

> That a nuclear power station situation in a major earthquake zone next to the coast could magically survive a 9.0 earthquake and a tsunami? The un-posed question is "what happens if a group of terrorists fly an A380 directly into one of these plants"? Someone on reddit was mentioning that a nuclear plant in Texas was built to "withstand a direct hit from an F-16 traveling at supersonic speeds", but I guess an A380…

K=1/2*mv^2? My intuition (as a mechanical engineer, desinging military systems as my day job) is that the F16 going supersonic is far worse. Either way, there is no possible way you have enough information to make any of the claims you just made. A better question to ask yourself how safe your highway transportation is, because within an hour of my house we've had 15 people killed in bus accidents in the last 72 hour…

> Either way, there is no possible way you have enough information to make any of the claims you just made.

I took out this from this report (http://www.euronuclear.org/reflections/nuclear-facilities.ht...), which I think was also mentioned by jgrahamc:

> The studies showed that even if knowledgeable insiders could disable key safety equipment, redundant systems would provide backup protection. In scenarios where all engineered safety systems were ruined, there was still a period of hours to take corrective actions before onset of core damage.

Now, you may argue that what indeed went wrong in the case of the Fukushima plant was that the "redundant systems" didn't provide the "backup protection" the experts relied on. I see this report is confident this would not be the case were the terrorists to hit a nuclear plant, but based on what happened in the last few days I'd say the confidence level for that scenario is bellow 100%.

Anyway, thx for those downvotting me, and I hope I'll never be proven right.

Re: Germany shuts down seven reactors‎ because of Fokushima

#65

Post by xlpz »

ErrantX wrote: post #37
xlpz wrote: post #25

Earlier quoted context omitted.

What potentially devastating consequences would there be if instead of a nuclear plant a windmill had been hit by an earthquake, tsunami and explosion? I honestly fail to be impressed by this kind of reasoning about nuclear energy's safety. Disclaimer: I still think fission power might be better in the long run than coal power (catastrophic global warming is worse than any nuclear disaster), but I'd rather do without…

The problem is that you can't (currently) replace that nuclear plant with a Windmill (or even a few Windmills) because the power production is still not high enough. So I don't feel that is an entirely fair comparison. What if such an event had hit, say, an Oil fired power station - you'd likely be looking at a reasonable level local oil contamination, and probably a large fire. I don't know how much more likely that…

I never said it'd easy, or that it wouldn't cost money. Everything costs money. Nuclear power plants are expensive, and they have vast hidden costs that are offset to society (how much will it cost to Japan to clean up this mess? is this added to the cost?). Many countries are already getting a very significant percentage of their energy from renewable sources, things like solar power or wind power are getting more efficient by the day, and if a real, massive and sustained investment was done in this area I think we wouldn't be having debates like this one in 10 years. And I won't even enter to discuss topics like energy independence, which are huge.

Anyway, clearly a complicated issue, not trying to convince anyone here of anything.

Re: Germany shuts down seven reactors‎ because of Fokushima

#67

Post by mironathetin »

drzaiusapelord wrote: post #45
mironathetin wrote: post #26

Earlier quoted context omitted.

I still remember the voices after Chernobyl: Light water reactors are safe and core meltdown can never happen, because the moderator is water. If it evaporates, the moderator is gone and the core will cool down. Chernobyl was a graphite moderated reactor. When the core overheated, the graphite melted together with the uranium and the nuclear reaction could not be stopped any more. Now we see how reliable those report…

By voices you mean Soviet propaganda for not only a poorly designed plant but also a poorly designed plant run poorly.

No, I am talking about german news reports. It makes no sense for the soviets to say that light water reactors are safe after a graphite moderated system has gone out of control.

Chernobyl could never happen in germany, because the construction of light water reactors is inherently safe. Thats what the news reported and the politicians claimed.

Do you see what happens now? Something like in Japan can never happen, because we don't have earthquakes and Tsunamis like they have.

These reports are not reliable. The basic idea, that a reactor has to shut down, if it gets out of control, is the right one. But it seems, the idea is not implemented well enough, even in the light water reactors.

Re: Germany shuts down seven reactors‎ because of Fokushima

#68

Post by asharp »

bhousel wrote: post #9

This strikes me more as a political stunt by Merkel to rally the conservative base in Germany than anything else. Still, it doesn't surprise me that this is such a hot button issue right now. I've long been a supporter of nuclear power, but the events of the past week have made me start to reconsider a lot of my beliefs about its safety.

The question is what exactly you expected of it. You've taken one of the oldest and least intrinsically safe designs since chernobyl (at least compared to anything recent like a nice pebble bed/molten salt reactor), hit it with an earthquake, washed it away with a tsunami and blown it up with hydrogen gas explosions.

And it's basically just that there, leaking a fairly small amount of radiation. Compare that to other objects that could cause environmental damage, like say an oil tanker or a chemical plant and try and compare it in similar circumstances.

If you were to take say a standard pesticide factory, hit it with an earthquake, followed by a tsunami, followed by multiple explosions, I would be very surprised if it could keep the same level of containment of its material.

To give you an example of what happens when a major chemical plant breaches, have a look at the Bhopal disaster. It isn't unreasonable to say that a major chemical breach is on the same scale as a small nuclear incident and as such I would consider the comparative reliability of nuclear plants to be rather remarkable and a testament to the engineering that goes into building them.

Also interesting to note is how things have progressed. Remember that this reactor was built in 1971. If you look at a newer design, such as a pebble bed reactor you would notice that it exhibits passive safety, ie. that if you were to subject it to the kind of failures that have befallen the fukushima plant, it would simply fail safe until it could be fixed. Even in the event of a catastrophic failure of the reactor core, very little radiation would be emitted as the core itself is encased as a series of nearly indestructible silicon carbide pellets, and the preferred coolant very rarely absorbs neutrons. This would also mean that coolant leaks would be a lot less of a concern environmentally as the coolant would not be as radioactive.

[1] http://en.wikipedia.org/wiki/Bhopal_disaster [2] http://en.wikipedia.org/wiki/Pebble_bed_reactor

Re: Germany shuts down seven reactors‎ because of Fokushima

#69

Post by bhousel »

jgrahamc wrote: post #16
bhousel wrote: post #9

This strikes me more as a political stunt by Merkel to rally the conservative base in Germany than anything else. Still, it doesn't surprise me that this is such a hot button issue right now. I've long been a supporter of nuclear power, but the events of the past week have made me start to reconsider a lot of my beliefs about its safety.

Which beliefs? That a nuclear power station situated in a major earthquake zone next to the coast could magically survive a 9.0 earthquake and a tsunami? Right now, we don't know how serious this situation is, it could be that this will end with a small amount of radiation leaked and four reactors that have to be decommissioned. Or it could end with a major environmental disaster. We simply don't know yet. I'd cautio…

I've done a ridiculous amount of reading the past few days, and I still believe that nuclear power is probably the best source of power that we have available to us.

But I didn't realize that keeping a reactor vessel (and fuel storage pools) cool after the reactor has been scrammed is such a challenge. I also didn't know that hydrogen explosions are a normal byproduct of cooling down a reactor core. Yes, I know that there are third generation reactor technologies available today that don't have all of these issues, and fourth generation technologies in development. I really do believe that we should be investing in these technologies to make nuclear power safer.

Unfortunately now we're stuck with a lot of aging reactors that are operating past their design life, and a public that is unwilling to bear the cost of the upgrades.

Japan is probably about the best prepared place that this incident could happen, and even they are having trouble keeping their scrammed reactors cool. And another earthquake could happen tomorrow, making the situation even more unmanageable.

I have far less confidence in almost any other country being able to handle a crisis like this. Nuclear power is clearly here to stay - Germany may eventually turn it's back on the technology, but there are dozens of third world countries running reactors now (or trying to).

Our focus really should be on making nuclear power as safe as possible, not on preventing it entirely. Perhaps the biggest problem with this current crisis is that it is the first nuclear incident where we can't just explain it away as 'human error'. Everything did work exactly as it was designed to, with the best trained people handling the crisis, and we still can't have complete confidence in the technology to cool itself off without releasing radiation into the environment.

Re: Germany shuts down seven reactors‎ because of Fokushima

#70

Post by paganel »

Qz wrote: post #52
paganel wrote: post #32

Earlier quoted context omitted.

> That a nuclear power station situation in a major earthquake zone next to the coast could magically survive a 9.0 earthquake and a tsunami? The un-posed question is "what happens if a group of terrorists fly an A380 directly into one of these plants"? Someone on reddit was mentioning that a nuclear plant in Texas was built to "withstand a direct hit from an F-16 traveling at supersonic speeds", but I guess an A380…

KE = 1/2mv^2, so depending on how supersonic they're talking about, it could very well withstand an A380 impact as well as a supersonic F16.

Supposedly an A380 carries much more fuel, whose explosive power might make up for the difference in impact speed.
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