Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[clancy688]

It's actually worse than that: out of three active reactor units affected, FOUR blew up

Great line, I really had to laugh out loud. Both hilarious and depressing.

Tell me how I can trust nuclear industry after this. Am I to believe French or US nuclear stations are better prepared, when more natural and conservative conclusion is 'French and US nuclear stations just didn't have their "extended SBO + all EDGs off" scenario. Yet. Just wait'?

I agree, trust is gone, for me, too. I was totally pro-nuke before Fukushima, but now I'm against it.
But overall I'd say that damn tsunami probably chose the one plant out of all those 500 stations in service worldwide which was actually the most vulnerable against such an attack. Pretty bad luck I'd say. And keep in mind that the whole station was from the same generation as Chernobyl and even TMI.
(By the way, we had three major accidents in civil NPPs and all of them happened in Units designed and built in the late sixties...)

 

[zapperzero]

(By the way, we had three major accidents in civil NPPs and all of them happened in Units designed and built in the late sixties...)

I blame the pot. On a more serious note, I think it has been definitively proven unwise to operate NPPs that are past their design life.

Oh, if only decommissioning one were not such an involved and costly affair.

 

[Most Curious]

Is this a technical forum - or a political one?

With enviornmental whackos preventing construction of coal fired base load plants and opposing ALL new nukes what PRACTICAL alternative is there? Hard to shut down an operating plant when there is nothing to replace it!

These kooks would have us all freeze to death in the dark.

If I choose to be anti-nuke I want it based on sound science, NOT political considerations or activist driven pseudo science.

I come here to study and learn science.

 

[clancy688]

Is this a technical forum - or a political one?

You ought to check out this https://www.physicsforums.com/showthread.php?t=490122".
It's closed but there were some good pro and contra nuke arguments going on.
And then there's the "more political" thread https://www.physicsforums.com/showthread.php?t=486089".

I think I'll answer to the rest of your post in that one. ;)

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20111107/2100_hoanin.html The NISA declared that Tepco's report on Xenon was valid.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20111110/0500_kanshi.html Tepco said it would implement a system to measure Xenon continuously, for the purpose of being able to quickly assess criticality. Concerning temperature measurements, Tepco said that there is a 20°C uncertainty, so that in order to be sure to achieve 100°C as requested by the "cold shutdown" requirement, the thermometer values have to be below 80°C.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20111109/1400_kouteihyo-shiji.html and http://www3.nhk.or.jp/news/genpatsu-fukushima/20111109/1650_30nen.html The ministers of Industry (Edano) and Nuclear accident (Hosono) have asked Tepco to prepare a schedule where spent fuel pool fuel removal is started within 2 years after completion of step 2. This is one year earlier than recommended in the report from the middle and long term commission that was completed on 9 November. Concerning molten fuel removal, the start is within 10 years.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20111112/0615_tsuruga.html The NISA is asking Japco to provide the operation data of the isolation condenser of Tsuruga unit 1 over the past 10 years because it is similar to the one of Fukushima Daiichi unit 1, and it might shed light on what went wrong at Fukushima Daiichi.

 

[nikkkom]

I agree, trust is gone, for me, too. I was totally pro-nuke before Fukushima, but now I'm against it.
But overall I'd say that damn tsunami probably chose the one plant out of all those 500 stations in service worldwide which was actually the most vulnerable against such an attack. Pretty bad luck I'd say.

How did you figure that out?
Do a mental exercise: imagine that all EDGs on all NPPs on the planet have vanished into thin air; then cut all power - put all NPPs into extended SBO.
Can you honestly say that F1 would be the only station where in this mental experiment events would take the worst turn? All other ones would be better off? That's statistically unlikely.

And keep in mind that the whole station was from the same generation as Chernobyl and even TMI.

We were told that they are upgraded with new safety systems and thus are safe. We ended up with station personnel not knowing how to turn on ICs and/or vent containment without electricity.

 

[clancy688]

put all NPPs into extended SBO.
Can you honestly say that F1 would be the only station where in this mental experiment events would take the worst turn?

Um, nope. I rather meant that the SBO only happened because the tsunami "chose" the single one plant which would actually lose everything if hit.
True, other plants will probably live through the same experience if confronted with a multiple-day SBO. But the actual event (earthquake + tsunami) may not be enough to trigger such a SBO at other stations.
A NPP will suffer meltdowns if confronted with a long and total SBO. And a plane will crash if all engines fail and can't be restarted. That's why you engineer those things the way that this shouldn't happen. But at Fukushima, nobody apparently thought of the obvious, a giant tsunami inundating the whole plant, and that triggered the SBO.
In my opinion, the problem is not the SBO. It are the events which could lead to SBOs. Or high-pressure meltdowns. Or whatever else. The events which no engineer thought of when constructing the plant. And those events exist, as Fukushima proved.

We were told that they are upgraded with new safety systems and thus are safe. We ended up with station personnel not knowing how to turn on ICs and/or vent containment without electricity.

Is it even possible to turn ICs on/off and/or vent the containment without electricity? I honestly don't know.

 

[NUCENG]

Two things I discovered by skimming through the report:

Unit 2 - If I read the section about Unit 2 correctly (and I'm not really sure I did, perhaps NUCENG could look over the sections regarding Units 1-3? There's a certain emphasis on venting valves), then Unit 2 never vented. The workers established a vent path, but a rupture disc never failed, even though the pressure was higher than the pressure needed to break it.
So when Unit 2 finally depressurized, it wasn't done through venting - but through containment failure.

Unit 3 - RCIC didn't fail on March 14th, it failed on March 12th at 11:36 local time, HPCI provided core cooling until the morning of March 14th. Was that fact known before?

I am not sure I can add much to what you have read. I have one criticism as this report is a narrative and does not provide references on how each statement was developed. As a result I think we need to review the vast amount of claims, statements, descriptions and timelines to find support or conflict. OTOH, this is exactly the kind of event summary that can make that a manageable exercise.

The narratives of units 1 to 4 are all plausible as far as I can see. I was sceptical about the Unit 3 source for the hydrogen explosion in unit 4, but the recent photos of damage on the 4th floor are persuasive, if not conclusive. I thought that the reverse flow through the unit 4 SBGT filters was problematic. But this report explains that unit 3 was able finally to vent at a fairly high containment pressure. It clarifies that the SBGT system dampers fail open. It confirms there are no backdraft dampers to prevent flow to the adjacent unit.

From the descriptions I note a new issue that may affect other multiple unit sites. The military term is fratricide and refers to casualties to friendly forces close to a an intended target. Unit 1 explosion damaged response equipment at unit 2. Unit 3 explosion damaged additional response equipment for other units. The issue here is the physical separation of units or location of emergency hookups to shield the equipment and workers from failures in adjacent units.

On Unit 2 There are two things to point out. First RCIC probably failed due to inability to cool or rediuce pressure in containment. RCIC exhausts to the suppression pool and the combination of low steam pressure and high exhaust pressure was the probable cause of RCIC failure. I see nothingin the report that indicates unit 2 containment venting was successful. Containment failure of the torus is still a likely explanation for the "loud noise."

I had seen the reports that unit 3 had HPCI running when the preferred system should have been RCIC which failed. This is another example of an issue that needs careful investigation. The number of work-arounds and alternative methods tried by operators to vent containments, operate SRVs, provide alternate power to instruments, and to reenergize other systems was very impressive. But it is probable that some of these methods were subject to delays to figure out how to do them. In my experience, some of these methods are proceduralized and exercised at US plants.

Hope this helps the discussion.

 

[NUCENG]

Um, nope. I rather meant that the SBO only happened because the tsunami "chose" the single one plant which would actually lose everything if hit.
True, other plants will probably live through the same experience if confronted with a multiple-day SBO. But the actual event (earthquake + tsunami) may not be enough to trigger such a SBO at other stations.
A NPP will suffer meltdowns if confronted with a long and total SBO. And a plane will crash if all engines fail and can't be restarted. That's why you engineer those things the way that this shouldn't happen. But at Fukushima, nobody apparently thought of the obvious, a giant tsunami inundating the whole plant, and that triggered the SBO.
In my opinion, the problem is not the SBO. It are the events which could lead to SBOs. Or high-pressure meltdowns. Or whatever else. The events which no engineer thought of when constructing the plant. And those events exist, as Fukushima proved.



Is it even possible to turn ICs on/off and/or vent the containment without electricity? I honestly don't know.

The report explains that the containment vent valves had manual operation capability and that operators eventially provided additional pneumatic pressure (compressor and air bottles) and alternative power from batteries to operate the system. In addition to remote operation from the control room theat means there were multiple ways to operate the valves, including manual and alternate power.

 

[NUCENG]

How did you figure that out?
Do a mental exercise: imagine that all EDGs on all NPPs on the planet have vanished into thin air; then cut all power - put all NPPs into extended SBO.
Can you honestly say that F1 would be the only station where in this mental experiment events would take the worst turn? All other ones would be better off? That's statistically unlikely.



We were told that they are upgraded with new safety systems and thus are safe. We ended up with station personnel not knowing how to turn on ICs and/or vent containment without electricity.

nikkom, a mental exercise probably doesn't belong on this thread. But while you're at it why not throw in a loss of gravity accident?

 

[Rive]

nikkom, a mental exercise probably doesn't belong on this thread. But while you're at it why not throw in a loss of gravity accident?

I have a slightly better question to chew on: with all those makeup pipes all around, are they ready for the winter?

What would happen if some water transfer pipes gets blocked by ice? What would happen with the SFPs? With the makeup cooling of the SFPs?

 

[NUCENG]

I have a slightly better question to chew on: with all those makeup pipes all around, are they ready for the winter?

What would happen if some water transfer pipes gets blocked by ice? What would happen with the SFPs? With the makeup cooling of the SFPs?

If you are talking about the hoses and pipes at Fukushima, I would hope that they are providing insulation and heat taping to prevent freezing. If you are talking about the emergency hookups at operating plants, consider that simply draining the external piping can prevent ice plugs, just as most homeowners do with their outdoor yard faucets. Or consider the fire hydrants used in most cities, fires happen in winter, too.

 

[Rive]

If you are talking about the hoses and pipes at Fukushima, I would hope that they are providing insulation and heat taping to prevent freezing.

Of course operating plants can handle a winter - they had some, and they are still operational.

I'm talking about Fukushima, the crippled plants and the equipment there.

Pictures about piping 'in the wild':
http://www.tepco.co.jp/en/news/110311/images/111022_20.jpg
http://www.tepco.co.jp/en/news/110311/images/111022_26.jpg
http://www.tepco.co.jp/en/news/110311/images/111022_08.jpg

From here: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111022_02-e.pdf

I have some doubts.

 

[NUCENG]

Of course operating plants can handle a winter - they had some, and they are still operational.

I'm talking about Fukushima, the crippled plants and the equipment there.

Pictures about piping 'in the wild':
http://www.tepco.co.jp/en/news/110311/images/111022_20.jpg
http://www.tepco.co.jp/en/news/110311/images/111022_26.jpg
http://www.tepco.co.jp/en/news/110311/images/111022_08.jpg

From here: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111022_02-e.pdf

I have some doubts.

I have doubts as well, but pretty small ones. In the outdoor pictures I see some hoses that probably will need to be insulated and or heated. Components in the buildings and tent shelters can be heated with space heaters. Some piping of chemicals may not be close to freezing (salt water is more susceptible to freezing as salinity is reduced.) Fluids can be heated. If a spent fuel pool has a small layer of ice, the water below probably isn't evaporating, and I doubt that winters could freeze more than 2o feet deep to where the fuel is located in spent fuel pools.

You asked a valid question, but it is not a show stopper.

 

[Rive]

...it is not a show stopper.

The show will go on anyway, but if they are not already prepared then it can turn in some unexpected directions... That's what I'm worried about. And judged by the pictures, they are not thoroughly prepared.

We will see.

 

[Shinjukusam]

I have some doubts.

Well, and bear in mind that I've been to Fukushima in winter, it's not a very cold area.

from the Fukushima international exchange website:http://www.pref.fukushima.jp/kokusai/contents/chiiki/nz/fukushima.html"

Coastal Region
As the region is located at the southern most part of the northeastern region of Japan, it is fairly mild throughout the year. The average temperature for winter wavers between 2-3°C while temperatures rise up to mid 20s in the summer. Mostly dry & sunny winters with little snowfall, while in the summer sandy beaches prove to be the popular summer destination for all.

(although that last line will likely be revised)

 

[zapperzero]

http://cryptome.org/eyeball/daiichi-111211/daiichi-111211.htm
photo-reportage

 

[Rive]

Well, and bear in mind that I've been to Fukushima in winter, it's not a very cold area.

Well, IMHO they should prepare for the worst, for this time - they are already failed with that once, with the tsunami...

 

[NUCENG]

Well, IMHO they should prepare for the worst, for this time - they are already failed with that once, with the tsunami...

As the Boy Scouts say, "Be Prepared!"

But please,Rive, take a deep breath and relax. There are many more threats that warrant your concern more than this. There is much less decay heat to remove today than in March. Even if something did freeze up, there is time margin to restore flow today that they didn't have then. If, and this is a big IF, they haven't already considered winterization, this is not even on the same continent as the failure to design for the tsunami. You raised a valid point, but you lose credibility if you overstate the issue. We don't even know if it has already been addressed or planned.

 

[Rive]

...

If what I said was like an overstatement, then: sorry. You are right, of course even worst case the result will be far from catastrophic.

But I want them to pass this second exam (proper handling of the events is like a second exam for them, IMHO, ?!) so I'm still worried, even if the consequences of a fail are not, nowhere in match with the original accident :-)

We will see.

 

[nikkkom]

nikkom, a mental exercise probably doesn't belong on this thread. But while you're at it why not throw in a loss of gravity accident?

Loss of gravity is (a) implausible and (b) wouldn't matter anyway, since all other human infrastructure would be destroyed by it, not only NPPs.

SBO and EDG failures are plausible failure modes.

 

[nikkkom]

A NPP will suffer meltdowns if confronted with a long and total SBO. And a plane will crash if all engines fail and can't be restarted. That's why you engineer those things the way that this shouldn't happen.

Sorry, but it is not true. Many *existing* NPPs will suffer meltdowns in this case. By now I think we need to mandate that all new NPP must be designed, and most existing NPPs retrofitted with means to prevent that. *Passive* means: EDGs do not count.

Is it even possible to turn ICs on/off and/or vent the containment without electricity? I honestly don't know.

If you mean, "was it possible at F1?" then I am interested in the answer too.

 

[NUCENG]

Loss of gravity is (a) implausible and (b) wouldn't matter anyway, since all other human infrastructure would be destroyed by it, not only NPPs.

SBO and EDG failures are plausible failure modes.

You proposed: "Do a mental exercise: imagine that all EDGs on all NPPs on the planet have vanished into thin air; then cut all power - put all NPPs into extended SBO." and call that plausible?

This is a technical forum. If your intent was simply to state that if an extended SBO could result in another accident, then you are correct. However, for such an event to occur, absent a similar design deficiency as the tsunami at Fukushima is very low risk. For it to occur at every plant on the planet simultaneously is a risk on the same order of probability as loss of gravity.

If you want to make your post topical, please explain how "EDGs vanish into thin air" and "cut all power" is probable at even one other plant unless there is another 1000 year external event. Then please explain why you think lessons learned from this accident won't make another accident even less likely.

I am not questioning your concerns or fears, but at least on this thread, let the anti-nuke hysteria be based on something more credible than your mental exercise appears to be.

 

[rmattila]

Another issue to take into consideration is the separation between "regular" EDGs and specific (usually air-cooled) SBO diesels fitted to some plants to enable certain vital safety functions even if all EDGs are lost. If they have sufficiently diversified power supply lines, they might provide some extra depth against severe accidents in station blackout situations. There seems to be a variety of opinions on how such dedicated SBO diesels should be treated in the post-Fukushima station blackout analyses.

 

[nikkkom]

You proposed: "Do a mental exercise: imagine that all EDGs on all NPPs on the planet have vanished into thin air; then cut all power - put all NPPs into extended SBO." and call that plausible?

This is a technical forum. If your intent was simply to state that if an extended SBO could result in another accident, then you are correct. However, for such an event to occur, absent a similar design deficiency as the tsunami at Fukushima is very low risk. For it to occur at every plant on the planet simultaneously is a risk on the same order of probability as loss of gravity.

The thought experiment wasn't meant to simulate a SBO over entire planet. That is not plausible. It was meant to construct an (implausible) situation in which every currently existing NPP is forced to go through real Fukushima event.

I am saying that I do not believe that almost every plant will survive. IOW: I don't believe in "stupid Japanese are to blame" theory.

 

[nikkkom]

I have a slightly better question to chew on: with all those makeup pipes all around, are they ready for the winter?

What would happen if some water transfer pipes gets blocked by ice? What would happen with the SFPs? With the makeup cooling of the SFPs?

OTOH, in winter uncovered SFPs have naturally better cooling :D

 

[NUCENG]

The thought experiment wasn't meant to simulate a SBO over entire planet. That is not plausible. It was meant to construct an (implausible) situation in which every currently existing NPP is forced to go through real Fukushima event.

I am saying that I do not believe that almost every plant will survive. IOW: I don't believe in "stupid Japanese are to blame" theory.

Neither do I, but the failure of TEPCO to incorporate new information about tsunami threats was a huge mistake that was a root cause of the accident.

It is not enough to come up with a "thought experiment" of extended SBO to condemn nuclear power in general. That "extended SBO" must be plausible and that takes more than imagining EDGs vanishing into thin air and loss of all power.

I reject your "thought experiment" unless you can show that there is a reason to believe the Fukushima scenario is plausible at other plants. This means you must identify a realistic set of external events and internal design vulnerabilities that can cause a similar result. And you must show that the lessons learned from Fukushima cannot or will not mitigate that vulnerability. Finally you must explain why the risks outweigh the benefits of nuclear power generation as those vulnerabilities are addressed.

If that burden can be met for any nuclear plant, then I, too, want that plant shutdown immediately and until until the vulnerabilities are corrected. If even one of these criteria can be met the burden should shift to the operators of the plant to show cause why they should be allowed to continue to operate pending corrective action.

This seems to put a huge burden on the person or organization that opposes nuclear power, but don't bother with the tired complaint that it is up to the nuclear industry to prove that it is safe to operate. "Safe" is an illusion and is not the issue. Nuclear power has risks and every plant that has been licensed has met the regulatory standards to show that the risk is low.

I reject your "thought experiment" because it is intellectually dishonest to apply a standard of 100% safe to nuclear power while tolerating the risks of tobacco, fossil plant emissions, automobiles, and the millions of other activities that do not meet that standard.

 

[LabratSR]

New Video released by TEPCO.

http://youtu.be/Lq_5KI787pI

 

[Luca Bevil]

Neither do I, but the failure of TEPCO to incorporate new information about tsunami threats was a huge mistake that was a root cause of the accident.

It is not enough to come up with a "thought experiment" of extended SBO to condemn nuclear power in general. That "extended SBO" must be plausible and that takes more than imagining EDGs vanishing into thin air and loss of all power.

I reject your "thought experiment" unless you can show that there is a reason to believe the Fukushima scenario is plausible at other plants. This means you must identify a realistic set of external events and internal design vulnerabilities that can cause a similar result. And you must show that the lessons learned from Fukushima cannot or will not mitigate that vulnerability. Finally you must explain why the risks outweigh the benefits of nuclear power generation as those vulnerabilities are addressed.

If that burden can be met for any nuclear plant, then I, too, want that plant shutdown immediately and until until the vulnerabilities are corrected. If even one of these criteria can be met the burden should shift to the operators of the plant to show cause why they should be allowed to continue to operate pending corrective action.

This seems to put a huge burden on the person or organization that opposes nuclear power, but don't bother with the tired complaint that it is up to the nuclear industry to prove that it is safe to operate. "Safe" is an illusion and is not the issue. Nuclear power has risks and every plant that has been licensed has met the regulatory standards to show that the risk is low.

I reject your "thought experiment" because it is intellectually dishonest to apply a standard of 100% safe to nuclear power while tolerating the risks of tobacco, fossil plant emissions, automobiles, and the millions of other activities that do not meet that standard.

Are you excluding from this "burden of proof" the japanese plants that have not been restarted yet, I must suppose ..

While I cannot sware on the EDG, pump protection, anti-tsunami barriers and similar resilience factors for each and every one of them, it does seem to a first rough examination of basic plant topology, levels of rectors above OP, that many share the same basic vulnerabilities than Fukushima daiichi had.

They will be probably upgraded before restarting.

Furthermore, and in this specific pointI suppose you will agree, most if not all US plants do have an unsatisfactory spent fuel disposal management, with overloaded spent fuel ponds, that does expose them to a set of possible risks, terrorist airplane strike, or above design assumptions earthquake shock, being two of the simpest I can think of.
Do we need a burden of proof to require proper disposal of nuclear spent fuel as well ?

 

[Most Curious]

I would agree too much spent fuel is stored at various NPP and that some risk is associated with that storage.

Why is that? Not because of the plants operators but the environmental kooks that have stopped EVERY attempt at building a storage location. How many billion $ was spent on Yucca Mountain before the hand wringers stopped it, thereby creating a MORE SERIOUS problem?

While on a rant, let us also consider the much greater volume of waste (and the wastefulness of calling much of it waste!) because the US does not reprocess spent fuel to recover the useful fissionable material therein.