Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[AtomicWombat]

The debris hanging from the base of the hole in Unit 4's secondary containment looks like insulation.

I'm happy to be proven wrong on this and I can only say the tongue looks like corium lava.

[PLAIN]http://www.cernobilturkiye.com/content_images/1/ch/chernobyl.jpg

[URL]http://files.abovetopsecret.com/images/member/bf822b7d3b8e.gif[/URL]

[PLAIN]http://upload.wikimedia.org/wikipedia/en/6/65/Pictureofchernobyllavaflow.jpg

See:
http://en.wikipedia.org/wiki/Corium_%28nuclear_reactor%29"

The hole appears to be above the floor of the concrete structure of the reactor building.

I disagree completely. Fukushima 1 units 2, 3 & 4 all have a clear ridge around the external building that denotes the boundary between the floor level - the level of the reactor "mouth" and the top of the spent fuel pool - and the concrete containment and other concrete support. The hole is clearly below this level.

 

[Astronuc]

I disagree completely. Fukushima 1 units 2, 3 & 4 all have a clear ridge around the external building that denotes the boundary between the floor level - the level of the reactor "mouth" and the top of the spent fuel pool - and the concrete containment and other concrete support. The hole is clearly below this level.

Yeah - on review, it does seem to be the first panel below the floor level. I also appears to be above several louvered areas, which I would expect are heat removal or ventilation systems, though the louvered areas seem to be in a build between the containment and the photographer.

That was a panel that blew out, but it does not appear to be concrete. The actual construction seems somewhat different than the published images (artists rendering) of the Mk I containment. I'd like to see a close up of the area.

 

[TCups]

Maybe we could work a trade with those intent on nuclear terrorism: all the high level radioactive waste you can carry in return for some good close up shots.

 

[MadRocketSci2]

Unfortunately for now I'll have to match your BOTE calculation with my own BOTE calculation.

From:
http://allthingsnuclear.org/post/385...r-core-cooling
Assume the fuel heat is equivalent to a boil-off rate of 50 gal/min (approx 10-20 days after removal from reactor).
This is equivalent to about 8 MW.
Using the stefan-Boltzman Law: Power = 5.67E−8*T^4, one square metre of Zironium will give off about 1.15 MW of heat (as a black body) at its melting T = 2128K. That requires about 8/1.15 say 6 m^2 of unobstructed radiation area to dissipate.

But we don't need to reach 2128K, we only need to reach 1500 K where zirconium reacts exothermically in air or steam. (Note zirconium is protected by a passivating layer that breaks down at this temperature.) The oxygen-Zr reaction gives off 12MJ/kg; the H2O-Zr reaction gives off 5.8MJ/kg.

I was talking about the spent fuel. The core probably can melt down if it isn't cooled long enough. The spent fuel though should be putting out heat at a fraction of what the core fuel is putting out though - we shouldn't have 50 gallons per minute evaporation from that! At 3 months, we should have 10% of the power density of 1 day after shutdown.

 

[TCups]

I was talking about the spent fuel. The core probably can melt down if it isn't cooled long enough. The spent fuel though should be putting out heat at a fraction of what the core fuel is putting out though - we shouldn't have 50 gallons per minute evaporation from that! At 3 months, we should have 10% of the power density at shutdown.

But do I misunderstand? The core fuel in Unit 4 was in the SFP, not in the core. Certainly there must be something fundamentally different between the SFP of Units 4, 5, and 6 if only Unit 4 exploded.

 

[PietKuip]

Japan's science ministry says radiation levels of up to 0.17 millisieverts per hour have been detected about 30 kilometers northwest of the quake-damaged Fukushima Daiichi nuclear power plant.

http://www3.nhk.or.jp/daily/english/17_38.html

Stay inside!

 

[MadRocketSci2]

Just the same problem that they've been having with all the reactors - the buildings were confined and allowed hydrogen to build up in them:

The Unit 4 pool lost water - it should have taken days according to NEI, but there must have been a leak in the pool or something - ditto the #3 pool, but #3 is already open to the air from the previous hydrogen explosion, so no hydrogen buildup no matter what it does.

From the thermometers in the #5 and 6 pools, apparently there is still water in there.

 

[Astronuc]

But do I misunderstand? The core fuel in Unit 4 was in the SFP, not in the core. Certainly there must be something fundamentally different between the SFP of Units 4, 5, and 6 if only Unit 4 exploded.

I don't believe 5 and 6 were as badly damaged, and their EDGs may actually be working. Unit 6 has Mk II containment, but Unit 5 is Mk I and similar to Unit 4.

Units 5 and 6 may have been shutdown earlier - which means cooler fuel, or perhaps they reloaded the cores, so the spent fuel pool does not have the burden of the reinsert fuel.

 

[andyr]

kfmfe04: The process of repatriation by itself would strengthen the Yen; however, BOJ has stated that there has been little repatriation by insurance companies, etc. because they have sufficient liquidity without selling US assets. In other words, the strenthening of the Yen has been caused by speculation. I hope that the hedge funds get burned bad by a massive multi-national effort to weaken the Yen. Would serve them right.

http://en.wikipedia.org/wiki/Carry_(investment )

Last nights yen surge did not look like speculation. I saw it tick for tick. It would appear that someone, or something big (a country maybe) had to buy a lot of yen after unwinding a trade, the yen was practically bidless.

The most hurt pair was the New Zealand dollar vs Yen which would make it seem like a carry trade unwind. The concept is you borrow a cheap to borrow currency like the yen, convert it to NZD, and then make 5% or so on NZD bonds or whatever you choose. This is a carry trade.

The borrowing rate is very low, and the return rate is decent. Of course is the currency shifts a lot the currency losses can outweigh the gains on the foreign investment. Now imagine if a lot of people are doing this, and one person capitulates. The next person may now face losses and capitulates sending the yen higher and higher, and so on.


Back on topic anyway:
I've seen figures for how much energy is generated when the plant was shutdown, a few hours after and and a day after. What is the figure after a week? Is there some rule of thumb for calculating this?

 

[Borek]

I've seen figures for how much energy is generated when the plant was shutdown, a few hours after and and a day after. What is the figure after a week? Is there some rule of thumb for calculating this?

Perhaps this earlier post will be helpful?

https://www.physicsforums.com/showpost.php?p=3192902&postcount=301

 

[Borek]

Have you seen Fukishima NPP on Google earth? I just did. One thing caught my attention. Plant is on the shore, and the place was leveled for the construction. That's nothing unusual, but it seems like the ground was leveled down, by digging into the hill. I don't want to sound like one of those armchair specialists, but I don't understand why - in the place that is at high risk of tsunami - they have not built the plant a little bit higher. They already had to move large volumes of the sand & rock.

I understand they have their own port, and it is easier to operate loading/unloading when the plant is at lower level, but it seems to me the difference in safety if the plant was - say - 5 meters higher would be enormous.

 

[MadRocketSci2]

The Japanese did apparently plan for earthquakes and tsunamis at this plant. They had something like a 6 m sea-wall around it - they got a 7 m wave this time due to the unexpected magnitude of the event.

A lot of Japan's plants are along the coast - I suppose the reasoning was easy access to cooling water. I imagine in the future, they will build them further up, and build pipes down to the shore, or alternatively pay much closer attention to waterproofing the backup generators, or build newer generation plants that passively cool. There really isn't any part of Japan where they can build that doesn't get earthquakes. Furthermore, they don't have native coal supplies, so they had to rely on nuclear for a good portion their power.

 

[LanceV]

I'm happy to be proven wrong on this and I can only say the tongue looks like corium lava.

To me it looks like insulation as well.
Also, keep in mind that the temperature of the SFP was reported to be 84°C on the 15th. Hard to imagine that it would heat up to the several 1000°C required for melting in just one day. Even if there was no water and we were talking about unspent fuel rods. Furthermore radiation would have spread much farther if a molten core would just be flowing out of a building.

Meanwhile conflicting information appears concerning the possibility of the spent fuel rods igniting:
http://news.sciencemag.org/scienceinsider/2011/03/contention-over-risk-of-fire-fro.html?ref=ra

 

[Naty1]

I keep hearing news reports that helicopters are dropping water to cool REACTORS...

That's crazy, right? ... if containment structures are largely intact...so are they trying to refill and cool some spent fuel pools?

 

[Hologram0110]

I keep hearing news reports that helicopters are dropping water to cool REACTORS...

That's crazy, right? ... if containment structures are largely intact...so are they trying to refill and cool some spent fuel pools?

Yes. As I understand it, they were trying to get water in the the pools (it has been boiling off) because of the decay heat. As I understand it, the helicopter thing didn't really work at all. They are going to go in and spray the fuel ponds from the ground. This is taking a while because there is a huge amount of radiation if you don't have enough water to provide shielding.

Why they can't fill the pool remotely is beyond me? All it should really take is pipe /w a sprinkler over the pool that you can hook up to from the outside. Maybe it has to do with the electrical problems or something (but I'm not sure).

 

[Borek]

The Japanese did apparently plan for earthquakes and tsunamis at this plant. They had something like a 6 m sea-wall around it - they got a 7 m wave this time due to the unexpected magnitude of the event.

It is difficult to judge, as the picture is taken directly from above, but I don't see the wall; check the Google Earth images. Looks like the plant is open to the sea, with high ground behind (steep slopes are very well visible and they are behind all reactor buildings).

I am far from saying they didn't plan for an earthquake and tsunami, and I am fully aware they have not much choice. Still, putting the plant few meters higher seems not that difficult, especially in this particular place. Using Google Earth data ground is 40 meters above sea level less than 300 meters from the reactor buildings.

Edit: image added.

 

[Astronuc]

I keep hearing news reports that helicopters are dropping water to cool REACTORS...

That's crazy, right? ... if containment structures are largely intact...so are they trying to refill and cool some spent fuel pools?

I would expect that it is water being added to the spent fuel pools. As we understand it, the containment is intact, so flooding the floor would only affect the spent fuel pools (SFPs), and they are probably depositing that in the SFPs.

If there is a breach between the SFP an containment, that's a different story altogether. There is a fuel transfer canal between containment and SFP. That is how fuel is transferred from the containment to SFP. The fuel is kept underwater.

If there is a breach (leak) in the gate(s) between SFP and containment, then the water could leak out of SFP into containment. I don't know that is the case though.

Also, if there was a breach in the SFP (I'm not say there is, because I just don't know), then the cooling water could leak out in addition to evaporating.

 

[marwood]

The reports are indicating that hydrogen escaping into the outer shell of the reactor building caused the explosion which blew off the top of reactor building 1. The steel frame atop the reactor building 1 is visible to the right in the photo at (http://www.greenpeace.org/international/ReSizes/OriginalWatermarked/Global/international/photos/nuclear/2011/digitalglobe-flickr-Fukushima-Japan.jpg) (source reliability considered but the photo does not appear to have been edited).

Reactor building 4 to the left of the picture reportedly suffered from two fires, at least one of which was attributed to lube oil combustion. However in the photo the majority of the lower and upper east facing wall of the building appears to be blown out between framing, while the roof appears to remain in place, and as the photo in post 305 shows, much of the cladding wall of the upper north facing wall of building 4 remains. That result would appear to indicate damage other than form a lube oil fire, and from a different sort of explosion than damaged building 1.

If the building 4 explosion were due to hydrogen from the spent fuel pool or from steam venting from the containment rising why would the roof and top wall cladding remain while the lower east facing wall appears to be blown out? The JAIF report for 1600 hours on March 17 suggests Unit 4 containment integrity is not damaged. Do the remains of building 4 suggest an explosion lower down in the containment and a major breach of the containment (or in the torus if it is not considered part of the containment)? Or is there a more likely explanation for the pattern of building 4 damage?

 

[uart]

It is difficult to judge, as the picture is taken directly from above, but I don't see the wall; check the Google Earth images. Looks like the plant is open to the sea, with high ground behind (steep slopes are very well visible and they are behind all reactor buildings).

I am far from saying they didn't plan for an earthquake and tsunami, and I am fully aware they have not much choice. Still, putting the plant few meters higher seems not that difficult, especially in this particular place. Using Google Earth data ground is 40 meters above sea level less than 300 meters from the reactor buildings.

Edit: image added.

Yes it's difficult to judge elevation from that image but I can see the rocks that build up the seawall there.

Borek, myself and others have been saying the same thing previously in this thread. I know it sounds like a case of 20/20 hindsight but I'm also very surprised that a nuclear power plant would be so poorly protected from a tsunami.

In my opinion the quake was unavoidable but the tsunami was optional. And it's that "option" that is costing them so dearly now. I can see no reason why the plant couldn't have been situated where it would be safe from a 15m tsunami.

 

[TCups]

Question on timelines

Local, I am in USA Eastern Daylight Savings time and note that there is sometimes a 1-day difference between the day and time an event is reported in Japan, vs. the day and time I am hearing "breaking news". It is Thursday, 12:57 PM here, now. It is Friday, 1:56 AM at Fukushima. Obviously the international time line is in play.

Anyone have a source of a detailed local timeline for the events occurring at Fukushima that would avoid some of my confusion?

 

[Astronuc]

If the building 4 explosion were due to hydrogen from the spent fuel pool or from steam venting from the containment rising why would the roof and top wall cladding remain while the lower east facing wall appears to be blown out? The JAIF report for 1600 hours on March 17 suggests Unit 4 containment integrity is not damaged. Do the remains of building 4 suggest an explosion lower down in the containment and a major breach of the containment (or in the torus if it is not considered part of the containment)? Or is there a more likely explanation for the pattern of building 4 damage?

The size of the explosion depends upon the amount of hydrogen and how well it is mixed (on not) with O₂ at the time of ignition. Bear in mind that steam would also dilute the H₂ in air.

In Units 1 and 3, the hydrogen vented into the upper containment from the core, so perhaps steam did not dilute the hydrogen (hydrogen is lighter than steam), and the hydrogen-oxygen then ignited.

 

[Astronuc]

Yes it's difficult to judge elevation from that image but I can see the rocks that build up the seawall there.

Borek, myself and others have been saying the same thing previously in this thread. I know it sounds like a case of 20/20 hindsight but I'm also very surprised that a nuclear power plant would be so poorly protected from a tsunami.

In my opinion the quake was unavoidable but the tsunami was optional. And it's that "option" that is costing them so dearly now. I can see no reason why the plant couldn't have been situated where it would be safe from a 15m tsunami.

Clearly the height (or scale) of the tsunami was underestimated.

 

[BHamilton]

Question on timelines

Local, I am in USA Eastern Daylight Savings time and note that there is sometimes a 1-day difference between the day and time an event is reported in Japan, vs. the day and time I am hearing "breaking news". It is Thursday, 12:57 PM here, now. It is Friday, 1:56 AM at Fukushima. Obviously the international time line is in play.

Anyone have a source of a detailed local timeline for the events occurring at Fukushima that would avoid some of my confusion?

I don't have a simple link for that handy now, but the thing to remember is that JST is UTC+9, while EDT is UTC-4, so if you see times given in US Eastern, add 13 hours to get JST

 

[TCups]

I don't have a simple link for that handy now, but the thing to remember is that JST is UTC+9, while EDT is UTC-4, so if you see times given in US Eastern, add 13 hours to get JST

Yes but some of what I read says "Tuesday's explosion" etc. It isn't always clear. A single accurate timeline would be helpful. There must be one. I am just lazy and haven't searched thoroughly.

 

[BHamilton]

Yes but some of what I read says "Tuesday's explosion" etc. It isn't always clear. A single accurate timeline would be helpful. There must be one. I am just lazy and haven't searched thoroughly.

Ah, here we go: the wikipedia article has a timeline, and it's in JST and its probably as accurate as anything you'll find in news sources http://en.wikipedia.org/wiki/Timeline_of_the_Fukushima_nuclear_accidents"

 

[kfmfe04]

Interesting perspective from a Japanese insider:

http://www.asahi.com/english/TKY201103160136.html

 

[Reno Deano]

Does anyone know the type of fuel (standard U235 or Mixed Oxide/PU) used in the subject reactors? The reason is that MOX has a higher burn up rate and gap release than standard fuel.

 

[BHamilton]

Units 1 and 2 were on standard fuel, and 3 was MOX.

 

[uart]

Clearly the height (or scale) of the tsunami was underestimated.

I think the point is that the height of the tsunami couldn't have been be estimated when they built the plant, so more safety margin should have been allowed.

Everything else in the design seem to have safety margin and redundancy built in, but the elevation to protect from potential tsunami seems to have little safety margin. Six meters seems a bit like, "oh what's that biggest tsunami we've had in the last 100 years or so, yeah that will do, no need for any safety margin". The tsunami risk on the Pacific coast of Japan has been known to the Japanese for centuries. Even just restricting to the era of modern history, tsunamis bigger than 6m had been recorded.

Yes I know it's 20/20 hindsight, but this issue of site placement just seems like the biggest weakness in the whole design. Zero safety margin when compared to tsunamis from just the era of modern history. This surprises me since more elevation doesn't seem as if it would have been difficult problem.

 

[BHamilton]

What's the status of main power at the station right now? Is there any hope of getting primary pumping going again? As I understand it, the decay heat dies off quite slowly, somewhat of a power law, so more water will need to be continually added to the pressure vessels for quite a while.