Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[zapperzero]

While on a rant, [...]

I don't really think this belongs in here. There's a political thread.
https://www.physicsforums.com/showthread.php?t=486089

 

[LabratSR]

PNAS Report on the dispersion of various nuclides

http://www.pnas.org/content/early/2011/11/09/1111724108.full.pdf+html

 

[Astronuc]

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.

Units 1-4 at Fukushima Daichi will not restart. Units 5 and 6 may restart pending permission of the government.

Any Mk I BWR at the same elevation of FK-I near the ocean is potentially vulnerable IF the EDGs, fuel supply and electrical switch gear are similarly vulnerable. The Mk II units are less vulnerable.

Other units at different locations may be required to adopt site-specific measures before restart, while some older units may be permanently shutdown and decommissioned.

Furthermore, and in this specific point I 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 ?

What is the basis of said assumption. Utilities must have the ability to do a full core offload to the spent fuel pool. Spent (or now called 'used') fuel, after a specified miniumum cooling period, is placed in dry storage at the reactor sites pending receipt by the US government for reprocessing or disposal in a respository.

US BWRs had a number of retrofits that were apparently not applied to FK Daiichi units. In addition, there are design differences at most US BWRs that make them less vulnerable than the FK-I units.

 

[LabratSR]

IAEA Remediation Mission Issues Final Report
http://www.iaea.org/newscenter​/focus/fukushima/final_report1​51111.pdf

 

[nikkkom]

I reject your "thought experiment" unless you can show that there is a reason to believe the Fukushima scenario is plausible at other plants.

Fukushima happened. That is a fact. I am not willing to accept any amount of pseudo-scientific proofs that "extended SBO + all EDGs are dead" scenario is soooo unlikely that we can ignore the possibility. Sorry, I don't buy it. We need to add systems which cover that possibility.

This means you must identify a realistic set of external events and internal design vulnerabilities that can cause a similar result.

No, it's your (meaning: nuclear industry, not you personally) task to convince me that it can't happen. And with me, you won't be able to do that. Maybe younger, more naive people should be target audience for attempts to do so.

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.

I don't call for immediate shutdowns. I would settle for "fully passive cooling system should be added during next 10 years to every operating plant".

 

[Rive]

Some survey around U3 containment equipment hatch:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_111116_01-e.pdf

That white stuff around the wet parts looks like salt for me. It's not good if it IS salt.
http://www.tepco.co.jp/tepconews/pressroom/110311/images/111116_03.jpg

 

[clancy688]

Why isn't it good?


In the early stages of the accident, big fire engines were used to spray sea water directly onto the reactors (At Unit 4 for sure, and as far as I know at Unit 3 as well). They wanted to refill the spent fuel pools. So that's where the salt could've come from.

 

[SteveElbows]

Approx 1300 mSv/h detected near the surface of the northern rail is surely the main indicator that should cause concern?

Im not sure if the containment hatches themselves were compromised at some point during the indecent, or if the source of the substances is pipework above the hatch locations. Either way, I think there was some quite active stuff on the floor near the other (south western) hatch, which they previously tried to vacuum, and then placed sheets on the floor to reduce dose to workers.

 

[Luca Bevil]

What is the basis of said assumption. Utilities must have the ability to do a full core offload to the spent fuel pool. Spent (or now called 'used') fuel, after a specified miniumum cooling period, is placed in dry storage at the reactor sites pending receipt by the US government for reprocessing or disposal in a respository.

US BWRs had a number of retrofits that were apparently not applied to FK Daiichi units. In addition, there are design differences at most US BWRs that make them less vulnerable than the FK-I units.

I remember reading far from reinsuring data in several pages in March.

Now I looked up and found for example this page

http://blogs.reuters.com/gregg-easterbrook/2011/03/18/the-danger-of-spent-fuel-rods-and-the-yucca-mountain-project/

or

http://www.commondreams.org/view/2011/03/21-2

of course I woud be happy to read more reinsuring data/evaluations from you if you can point to more reliable information.

 

[NUCENG]

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 ?

I do not exclude any plant in any country from the basic process of learning from experience. Right now there is a new appreciation for the power of tsunamis in Japan. It is still nearly incomprehensible to me that the nation that gave us the word "tsunami" needed this lesson, but it happened. It proved that a 1000 year event can occur in a 40 or 60 year plant life and that the consequences of that rare event needed to be included in the design. It is clear that the costs of hardening the Fukushima plants against tsunamis would have been a bargain compared to what they are now facing. If utilities operating nuclear plants are slow or ineffective in taking actions, it depends on the regulators to step in and force the action or shut the plant down. This backup also failed in Japan. As a result we have the political backlash that is represented by prefectural governors blocking plant restarts in search of the "100% safe" myth. Italy and Germany have also taken a political decision which is their right and is supported by their citizens.

I do agree that spent nuclear fuel is a major issue in the US. But this issue is a result of political issues overriding technical solutions that were promised by the government and paid for by the nuclear industry, but not delivered. Plants have installed dry cask storage to reduce fuel pool loading. The risks of terrorism and seismic activity are being reviewed. Actions have been taken to upgrade security, and GI-199 was already being finalized into regulatory requirements when the earthquake hit Japan. You may disagree, but the industry, the regulators, and the general public in the US support that process.

 

[NUCENG]

Fukushima happened. That is a fact. I am not willing to accept any amount of pseudo-scientific proofs that "extended SBO + all EDGs are dead" scenario is soooo unlikely that we can ignore the possibility. Sorry, I don't buy it. We need to add systems which cover that possibility.



No, it's your (meaning: nuclear industry, not you personally) task to convince me that it can't happen. And with me, you won't be able to do that. Maybe younger, more naive people should be target audience for attempts to do so.



I don't call for immediate shutdowns. I would settle for "fully passive cooling system should be added during next 10 years to every operating plant".

You are still missing the point, nikkom, your thought experiment jumps to the condition of an extended SBO at every plant because it happened at one plant. I agreed that extended SBOs could cause another accident, but I insist that there be a legitimate path to that condition.

In terms of nuclear power accidents we are worried about very low risk events with high consequences. I am frustrated that the public readily accepts high risk low consequence accidents every day that cumulatvely dwarf the consequences of a nuclear accident. Your thought experiment jumps to the consequences with no consideration of risk.

It is not my (meaning: nuclear industry) task to convince you that "it can't happen." It can happen, but the risk is low and the lessons learned from Fukushima will make it even lower. It IS my task to balance the fuzzy logic and misinformation represented by your thought experiment. I respect your right to disagree with me, but the "younger people" you distrust will remain naive if they only hear your side.

 

[Rive]

Im not sure if the containment hatches themselves were compromised at some point during the indecent, or if the source of the substances is pipework above the hatch locations.

- By the linked PDF document the radiation levels are extreme around only one rail there.
- If the equipment hatch is any similar to http://www.tva.com/news/pix/a_4.jpg" , then there are no pipes so close that a leak would affect only one rail.

IMHO.

(Picture index is here: http://www.tva.com/news/pix/index.htm )

 

[nikkkom]

You are still missing the point, nikkom, your thought experiment jumps to the condition of an extended SBO at every plant because it happened at one plant. I agreed that extended SBOs could cause another accident, but I insist that there be a legitimate path to that condition.

In terms of nuclear power accidents we are worried about very low risk events with high consequences. I am frustrated that the public readily accepts high risk low consequence accidents every day that cumulatvely dwarf the consequences of a nuclear accident.

Why are you frustrated by it? There are no practical ways to get rid of automobile transportation. There are no legal ways to prohibit smoking (for now). Therefore, those activities will continue.

But there are practical way to make nuclear power plants safer. They do exist.

F1 should have been safer wrt the accident conditions which actually were experienced. It's a pity the problems there were not fixed before F1, but it's history now. The question now is, will we (humanity as a whole) at least take action *after* it was empirically shown at F1 that currently nuclear industry isn't as safe as we want it to be?

The "stupid Japanese" theory leads us in the direction where only Japanese NPPs and their personnel will improve their safety systems and training. The rest of the world will need to wait for another wakeup call. I don't like it.

 

[nikkkom]

I do agree that spent nuclear fuel is a major issue in the US.

I thought dry cask storage solves the problem in medium term?
(a) dry casks are rather safe wrt natural disaster or industrial damage and theft
(b) the fuel from dry casks can be reprocessed in the future, it does not deteriorate
(c) the fuel in dry casks becomes less and less radioactive over time - making it less, not more dangerous with time
(d) dry cask storage is not very expensive

Am I missing something?

 

[SteveElbows]

- By the linked PDF document the radiation levels are extreme around only one rail there.
- If the equipment hatch is any similar to http://www.tva.com/news/pix/a_4.jpg" , then there are no pipes so close that a leak would affect only one rail.

IMHO.

(Picture index is here: http://www.tva.com/news/pix/index.htm )

Given that containment hatch/personnel airlock's are one of a number of containment failure points highlighted in studies of containment under severe accident conditions, I certainly do not require pipework to exist in the vicinity in order to explain the contamination in this area. But I can't completely rule it out either, nor can I state that pipework absolutely must be within a certain proximity in order to contaminate only one rail.

An example of the sort of study I refer to is this one http://www.osti.gov/bridge/servlets/purl/6409677-0h1aot/6409677.pdf

 

[SteveElbows]

TEPCO have released a large number of previous unpublished videos, taken over many months.

http://www.tepco.co.jp/en/news/110311/111111-e.html

Has anybody watched many of these videos yet? I've watched just over half of them so far. Main themes of note to me so far are:

Many looks at the upper building of reactor 4, during numerous fuel pool measuring or spraying activities. Get a look at the reactor well in one of them.

A few videos showing workers performing pipework-related activities inside reactor buildings, often having to climb stairs to a higher level.

A video that shows what's going on under the less-collapsed part of reactor 1 buildings roof. When zoomed in some clouds can be seen, I strongly presume we are looking at the fuel pool. They then proceed to study the remains of the roof above this section, and in a later video it appears that they sprayed something through part of this roof, creating a hole (its not labelled as such but seems like this may be how they initially added water to unit 1's fuel pool)

A couple of videos of reactor 3 pool spraying, where the operator spends quite soon time zooming into an area which, if my orientation is correct, is around the area where the fuel pool-to-reactor gate is.

There are lots of other videos but these were not so notable to me.

One particular reactor 4 pool video gives us a much extended view underwater of the pool & its contents. It goes on for many minutes and offers a much clearer and more comprehensive view than the videos of months ago. I am not especially interested in the pool anymore, but it was still an interesting video. The link is below, and underwater stuff starts at around the 10 minutes 40 second mark (or just before half way of the position slider if you can't tell how far throughout he video you are because of the way TEPCO have delivered these videos in web browser).

http://www.tepco.co.jp/en/news/110311/movie_1111/1111_21-e.html

I must admit I was slightly surprised to see what appears to be a fuel bundle on its own, with a slightly bent handle, sitting quite upright but not inside multi-bundle racking like all the other fuel. I do not presume that this has anything to do with the accident, but I'd like to know a little more about it. It is briefly visible towards the end of the video, when the camera has panned to the right of the pool, and then pans downwards after previously looking up at a section of pool wall. Around the 21:25 to 21:29 mark.

 

[NUCENG]

Why are you frustrated by it? There are no practical ways to get rid of automobile transportation. There are no legal ways to prohibit smoking (for now). Therefore, those activities will continue.

But there are practical way to make nuclear power plants safer. They do exist.

F1 should have been safer wrt the accident conditions which actually were experienced. It's a pity the problems there were not fixed before F1, but it's history now. The question now is, will we (humanity as a whole) at least take action *after* it was empirically shown at F1 that currently nuclear industry isn't as safe as we want it to be?

The "stupid Japanese" theory leads us in the direction where only Japanese NPPs and their personnel will improve their safety systems and training. The rest of the world will need to wait for another wakeup call. I don't like it.

First, if I have given you the impression that I oppose taking action based on lessons learned from Fukushima because it is low risk, that is not the case. But the simplistic cookie cutter approach of requiring all plants to retrofit completely passive heat removal systems is not warranted if it can be shown that the combination of active and passive systems already in place are sufficient to meet the risk of internal and external events. Installing and protecting additional AC, DC, or pneumatic power sources to extend operation of existing active systems may suffice.

I do not recommend eliminating automobiles, but I would be less frustrated if more people recognized the daily decisions we make to accept risk in return for the benefiits of our activities. I want the same kind of risk/benefit balance in decision making about nuclear power.

Why do you keep harping about the "stupid Japanese" theory? I have clearly stated that it is nonsense and does not excuse other countries from taking action.

I will give you one more consideration. All of the hype and, in my opinion, misinformation is likely to seriously delay or abort efforts to build new plants that do have passive safety designs. Concerns over global warming are threatening operation of fossil fuel plants. You have seen the impact of the plant shutdowns on the Japanese economy. The end result, to avoid similar impacts on other economies could be to continue to extend operation of the plants with the highest risks.

 

[NUCENG]

I thought dry cask storage solves the problem in medium term?
(a) dry casks are rather safe wrt natural disaster or industrial damage and theft
(b) the fuel from dry casks can be reprocessed in the future, it does not deteriorate
(c) the fuel in dry casks becomes less and less radioactive over time - making it less, not more dangerous with time
(d) dry cask storage is not very expensive

Am I missing something?

Dry cask storage is only necessary because the US government did not meet its commitment for a federal depository.

Right now there are more than 100 temporary storage sites requiring security and protection.

Reprocessing options were discarded in the US nearly 40 years ago and only recently have been discussed again as a serious potential.

As you say, spent fuel becomes less dangerous with time - a LOOOOOONG time. The same can be said for fuel in a pool or in a geological depository.

Finally, dry cask storage ain't cheap.

 

[nikkkom]

Right now there are more than 100 temporary storage sites requiring security and protection.

Are they co-located with NPPs which already require the same?

As you say, spent fuel becomes less dangerous with time - a LOOOOOONG time.

A 90-year old spent fuel is more than 10 times less radioactive than 4-year old one, right? I imagine reprocessing plant designers would like this fact.

 

[westfield]

Has anybody watched many of these videos yet? I've watched just over half of them so far. Main themes of note to me so far are:

Many looks at the upper building of reactor 4, during numerous fuel pool measuring or spraying activities. Get a look at the reactor well in one of them.

<snip>


I must admit I was slightly surprised to see what appears to be a fuel bundle on its own, with a slightly bent handle

< snip.

This one? Appears to be towards the SE corner of the Unit 4 SFP. We've never seen right into this SE corner of the pool perhaps due to the limitations of the camera rig they are using.

I didn't see any of the Unit 4 reactor void, which clip was that?
I saw the camera get as far as looking beyond the FHM down onto the Cask area in the NW corner of the SFP but no further.
Also saw them get the water spray boom very jammed up under the unit 4 main crane, I imagine a change of pants was in order when that sprang free!, appeared to do some minor damage to the camera\thermocouple lowering rig. Short clip http://s1185.photobucket.com/albums/z360/fukuwest/misc/?action=view&current=U4boomsnag.mp4

Some views of the Unit 1 "service shaft", the very bent main crane, the FHM etc which has been hiding under the roof debris -

The unit 3 SFP videos reveal where these earlier images of the U3 SFP came from.

Apr 14th Still Image
http://i1185.photobucket.com/albums/z360/fukuwest/misc/sfp_boom_14Apr110415_1f_4_1.jpg


Apr 18th image from video - Near the NW corner of the U3 SFP
http://i1185.photobucket.com/albums/z360/fukuwest/misc/1312011111712_51_55.jpg (zoomed out, ladder visible in centre of image)
http://i1185.photobucket.com/albums/z360/fukuwest/misc/1382011111715_56_57.jpg (zoomed in)

In that video they seem to be checking the water level of the SFP against the SFP Skimmer outlet as they are adding water - the outlet is a dark rectangle in the wall of the sfp barely visible amongst the steam. The camera operator also zooms in on a large object in the SFP, more towards the eastern side of the pool. It has some characterisics of a FHM but it's not clear enough to see if it is part of the FHM or not. This area is the source of the other previously released SFP image.

 

[NUCENG]

Are they co-located with NPPs which already require the same?



A 90-year old spent fuel is more than 10 times less radioactive than 4-year old one, right? I imagine reprocessing plant designers would like this fact.

Not all spent fuel storage is at active plants, some are at decommissioned sites that have storage licenses. When you talk about 90 years, does that mean you expect plant license extensions that long? Obviously, if we can't eventually move this stuff offsite, the answer to your question will eventually be NO!

If your number is correct and spent fuel after 90 years is only 10% of the radiation levels of 4 year old fuel, I have to paraphrase a previous comment of mine, "10% of a big number is still a big number." I would like to see serious attention to reprocessing fuel. I believe we will still need geological storage of high level wastes.

 

[Rive]

An example of the sort of study I refer to is this one http://www.osti.gov/bridge/servlets/purl/6409677-0h1aot/6409677.pdf

Thanks.

It's interesting that the expected failure pressure is close to the expected containment cap failure pressure, if I take it right. So if this one failed then the other one might failed too.

Regarding the 'new' videos: did anybody managed to find the U3 FHM?

 

[nikkkom]

If your number is correct and spent fuel after 90 years is only 10% of the radiation levels of 4 year old fuel, I have to paraphrase a previous comment of mine, "10% of a big number is still a big number."

Sure. I am not implying that 90 year old fuel is harmless. Of course not. It is still so radioactive that it can kill nearby human in seconds if unshielded.

I would like to see serious attention to reprocessing fuel.

Me too.

I see no harm, though, in keeping spent fuel in dry casks for many years before reprocessing. It actually should make reprocessing easier. In 100 years, Kr-85 decreases by the factor of 1000 (meaning that airborne releases are greatly reduced), Cs-134 by 10^15 (practically zero), Cs-137 and Sr-90 by 10. What's not to like?

I believe we will still need geological storage of high level wastes.

Sure. Unless someone is willing to make an electric generator powered by heat of canisters filled by Cs-137 and Sr-90. :D

 

[SteveElbows]

Thanks.

It's interesting that the expected failure pressure is close to the expected containment cap failure pressure, if I take it right. So if this one failed then the other one might failed too.

Regarding the 'new' videos: did anybody managed to find the U3 FHM?

Given the locations of some of the steam we saw escaping from several reactors (most clearly number 3), I don't think many people would be at all surprised if drywall head was a leak point.

As for the FHM, I would not be at all surprised if it left the building during the explosion. There was more than enough debris to the immediate south of reactor 3 building to account for this, and I don't think the media or TEPCO were too interested in reporting its location. If it was ejected then I don't think it tells us much really.

 

[SteveElbows]

This one? Appears to be towards the SE corner of the Unit 4 SFP. We've never seen right into this SE corner of the pool perhaps due to the limitations of the camera rig they are using.

I didn't see any of the Unit 4 reactor void, which clip was that?

Yes that's the one. Any ideas about it? I wondered if perhaps it had been mishandled and damaged at some time in the past, and so was kept on its own? Or is there any such thing as a 'dummy' fuel bundle used for some purpose?

As for unit 4 reactor well, I made a stupid mistake having watched too many videos in one sitting. I knew it didn't look like the reactor well should, but I thought maybe it was something that had been temporarily placed in the region during the reactor shroud work. In fact it was the cask area of the fuel pool that you mention, my mistake.

 

[Rive]

As for the FHM, I would not be at all surprised if it left the building during the explosion.

Well, I would. Lot of other, less stable stuff remained there on the top...

But anyway, it's just my stupid theory about the falling overhead crane, pushing through the FHM on the drywell cap - no worth in discussing it without further details :-)

Yes that's the one. Any ideas about it?

IIRC the SE corner is where a 'Fuel Inspection Machine' or something like that were suspected. (It was around May, maybe...) I've posted a picture about it somewhere... It's for manual dry inspection of new bundles.

 

[SteveElbows]

Well, I would. Lot of other, less stable stuff remained there on the top...

But anyway, it's just my stupid theory about the falling overhead crane, pushing through the FHM on the drywell cap - no worth in discussing it without further details :-)

I don't see much other stuff remaining at that level of reactor 3. There is mostly just the overhead crane, and lots of roof debris.

I don't tend to see enough debris under the crane to account for the FHM, although the area is such a mess that I cannot be entirely certain. Certainly some portion of the circular plugs that sit above the drywall can be seen on a couple of different videos or images. A very small portion can be seen on old videos that showed steam escaping from the area where the edge of the reactor drywall connects to the storage pit/pool. Such footage tended to indicate that the overhead crane beam on this side had fallen quite neatly down to this level, quite parallel with the floor. And in the following image I believe we can see quite a portion of the eastern side of the cap. I will illustrate the area in question shortly.

http://www.tepco.co.jp/en/news/110311/images/111008_05.jpg

 

[SteveElbows]

OK so here is a version of the above image which I have marked. Within the yellow area is the edge of the circular drywell plug I mentioned. Within the orange area is possible another part of the plug edge, but I am less certain of this one. The X marks the spot where other images & video have shown steam escaping in the past.

This is a document which shows the area I marked with an X. The gap along the narrow edge of the removable pit gate is the main feature of interest due to the longstanding impression that this was a well visible point of containment failure, but in this case I am posting it so we can see what the edge of the drywell plugs looks like for comparison with above image.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110924_02-e.pdf

 

[SteveElbows]

Also please note that I cannot be certain that I have identified plug edges correctly in that photo, it could be something else, but the position seems about right.

 

[Rive]

... the position seems about right.

Agree. You can even see the FHM rails near the plug. Good find.
[URL]http://www.houseoffoust.com/fukushima/tepco_pics/R3_july21_1.jpg[/URL]
(The circle marks the pool gate: the rail is on the left near the reactor well.)

The 'spanner' (look it up in the thread here) was more in the way of the destruction than the FHM and it's still on the top level... More or less. So I think the FHM should be there too.