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Japan Earthquake: nuclear plants

by gmax137
Tags: earthquake, japan, nuclear
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JUrban
#847
Mar22-11, 11:28 AM
P: 8
Spent fuel pool watering method

Fluctuating radiation and isotope levels are making ground work dangerous and slow, with a potential to completely cease work (of which there appears considerable cooling system work) and ground based watering, at least for some time.

Discharged water from ground based watering trucks substantially disperses on its course over building walls up to about 150 feet in height, and suitable positioning of watering trucks is also limited.

Water volume needed to mitigate each spent fuel pool is substantial, in the hundreds of thousands of gallons, which, along with counteracting pool water loss, necessitates sufficient and reliable gallons per minute filling pool fill rate (of water actually received by pools).

Apparent lack of experimentation to find a more effective watering method (perhaps due to lack of anticipation and thought in nuclear industry for present situation) is concerning.

Thermal imaging (Figure 1) reveals rising temperatures likely in spent fuel pools, as well as critical planning information for placement of new watering method.

Critical to re-establish water in spent fuel pools, which hold most of the nuclear material, the material susceptible to break down over time without water and has no containment if aerosolized.

Based on careful analysis, most effective watering method (of many) involves deploying hose with grappling hook like structure at outflow end, to be caught at top of building structure near a hotspot location.

System is best deployed by helicopter lift operation, and due to relatively low level of precision needed and natural stabilization (see below), 1) lift cable can be in excess of 500 feet (long line lifting), optionally without nearby vertical reference ground spotter, and 2) completion of lift operation, during which building is approached from air, can be done in minimal time (minutes), substantially limiting radiation dose of air crew (JSDF carried out helicopter watering operation on 17th with short line; that day about 88 millisieverts per hour was measured at 300 foot elevation and about 4 millisieverts per hour at 1000 foot elevation).

In simplest deployment method, for completion of lift operation, hose is laid over side of building (Figure 2A) with outflow end (having grappling hook structure, not necessarily drawn to scale) lowered into area above spent fuel pool/hot spot (Figure 2B). Lift line release and helicopter departure can then occur.

When water is pumped through the inflow end of the hose at a relatively safe location (assume 1 mile hose length for calculations), the weight of the water in the section of hose ascending up the wall will create hose tension that pulls the outflow end back (Figure 2C), causing the relatively simple steel grappling hook structure to become caught on surrounding structure and serve as an anchor. Assuming an ascending hose length of 150 feet, for a 2 inch diameter hose the water weight is about 200 pounds, or for a 4 inch diameter hose the water weight is about 800 pounds. It's seen that such weights are similar to what conventional grappling hooks experience.

In simplest deployment method, at beginning of lift operation a sufficient length of hose, such as lay-flat discharge/irrigation hose (Figure 3) often encountered on the order of miles in length, is prepared at a safe staging area for lifting (Figure 4A). During air transport the entire hose section can hang from lift cable (Figure 4B), ready for imprecise laying of the hose (Figure 4C), likely followed by some pulling/dragging near the end of the lay to achieve good longitudinal placement. Irrigation hose can have excellent abrasion and puncture resistance. By laying a relatively long section of hose, intermediate coupling operations on the ground can be avoided, although are also a viable approach if radiation levels permit.

A benefit of this lay/minimal pull deployment method is that the grappling hook at hose outflow end is naturally stabilized for its placement. In particular rotational and for/aft motion is stabilized, with also some side to side stabilization due to lateral friction and hose constraint with debris on the ground.

For a 100 gallons per minute flow rate through 1 mile of hose, a 4 inch diameter hose will have only about a 12 psi pressure drop, with greater drops for smaller hoses. Assuming a 150 foot hose rise over the building wall, an additional 65 psi of pressure is added for pumping to overcome, which is well within reasonable range. Medium duty lay flat irrigation hose is typically rated for 150 psi.

Although spring/pull-line directional control of water discharge is possible, it's likely sufficient to simply implement a water outflow pattern that is somewhat divergent to compensate for any misalignment with storage pool, considering the high flow rate effectively discharged directly into the area, as apposed to attempting to discharge from outside of the building and near ground level as has been done thus far. Also, discharge distance effectively adjusted by varying pumping pressure.

In the case of buildings with intact rooftops (such as unit 2) yet inability to water spent fuel pools due to excessive radiation levels, a hole of sufficient size can be punctured above the spent fuel pool area and a single hook metal structure with hose can be deployed by air lift into the puncture to then catch upon pumping (Figure 5, again not necessarily drawn to scale) as described earlier. All intact reactor buildings have already lost negative gauge pressure (including units 5 and 6 in which intentional vents were made in the rooftops).
Attached Thumbnails
importantfigs.jpg   Figure1.jpg   Figure5.jpg  
Arcer
#848
Mar22-11, 11:31 AM
P: 14
Quote Quote by AntonL View Post
Here is a time line of the explosions and reported CV venting
Unit 1 - 12.03.2011 at 15:36 : CVv 15:00 on 12.03.11
Unit 3 - 14.03.2011 at 11:01 : CVv 09:20 on 13.03.11
Unit 4 - 15.03.2011 at 06:14
Unit 2 - 15.03.2011 at 06:20 : CVv 11:55 on 13.03.11

There is a correlation between Unit 1 CV venting and Hydrogen blast.

Below SFP data FU = fuel units followed by pool volume and heat load of the FU
Unit 1 - 292 FU 1200m3 60kW
Unit 2 - 587 FU 1425m3 400kW
Unit 3 - 514 FU 1425m3 200kW
Unit 4 - 1331 FU 1425m3 2000kW + 200 brand new FU (yes 2MW not a typo)

This sets a new light on my earlier proposal
Unit 1 exploded due to H2 leak of venting system - possibly earth quake damage
Unit 2 to 4 exploded due to hydrogen generation from equipment pools.
Very interesting that units 4 and 2 had explosions withing 6 minutes of each other both on the 15 March.
Arcer
#849
Mar22-11, 11:44 AM
P: 14
http://www.youtube.com/user/KurtsFilmeVideo#p/u

Speculation again but it's possible that those bits of roof (steel) still remaining on building 3 are actually being supported by the gantry crane. Although against that I remember there was opinion that the crane might have landed on a low level building adjoining the north side of building 3.

And at exactly 2.50 into the video could that long green object lying on the ground be a green gantry crane blown out of one of the buildings likely 3 as the most explosive. So three alternatives for what happened to the gantry crane?
AntonL
#850
Mar22-11, 11:50 AM
P: 521
Quote Quote by JUrban View Post
Spent fuel pool watering method
filling of unit 4 SFP by concrete lifter


I am amazed by the protection suits, two piece, open collar, construction helmet ...
Compare to clothing in this video http://www.youtube.com/watch?v=apryc...feature=relmfu

and workers/inspectors then drive home in their cars, I presume after a hosing down, but is that effective?
TCups
#851
Mar22-11, 11:53 AM
TCups's Avatar
P: 494
Quote Quote by Arcer View Post
Very interesting that units 4 and 2 had explosions withing 6 minutes of each other both on the 15 March.
So, Unit 4 with the same starting volume of coolant in the SFP (1425 M2), but with a heat load 10 times greater than the SFP of Unit 3, generated enough heat and hydrogen to explode, but only did so 19 hours later than Unit 3, and with (apparently) a smaller explosion.

And Unit 3 exploded, albeit 26 hours after venting the overheating reactor vessel.

Again, I wish I cold compare the seismic recordings of Units 1-4 and compare their magnitude.

No expert on explosions, but I think the faint upward blast component from the explosion of Unit 1 was a ground-reflected shock wave. There was very little material ejected straight upward by the primary blast, compared to Unit 3, and yes, perhaps that had something to do with the concrete walls of Unit 3.

These data still do not contradict, and may in fact, support my contention that the explosion in Unit 3 was a combination of two things, hydrogen from delayed leakage of the primary containment and hydrogen from the SFP, vs an explosion immediately following hydrogen leakage from a damaged venting system in Unit 1, and delayed explosion of hydrogen only from the SFP of Unit 4.

Anton?
Borek
#852
Mar22-11, 11:55 AM
Admin
Borek's Avatar
P: 23,535
Quote Quote by AntonL View Post
I am amazed by the protection suits, two piece, open collar, construction helmet ...
Surprising - yes. But somehow I think they knew what they were doing.
TCups
#853
Mar22-11, 12:18 PM
TCups's Avatar
P: 494
Quote Quote by Borek View Post
Surprising - yes. But somehow I think they knew what they were doing.
I hope they had respirators or some type of filtered breathing apparatus.
M. Bachmeier
#854
Mar22-11, 12:32 PM
P: 184
Quote Quote by TCups View Post
I hope they had respirators or some type of filtered breathing apparatus.
Even a simple dust mask would provide substantial protection, but I would go for an organic vapors mask & cartridge with removable dust caps. Radioactive dust would tend to collect on such surfaces, but switching out dust pre-filters would be quick and easy.

The full face mask would also (which is sealed against the skin) prevent air from seeking a path of least resistance around its filter which could develop resistance too air flow because of dust and moist vapor from exhalation. Air goes in through the filters and out through a release valve. However, I've see several videos where simple dust masks are used (working around radioactively contaminated areas), go figure?
AntonL
#855
Mar22-11, 12:33 PM
P: 521
Quote Quote by TCups View Post
These data still do not contradict, and may in fact, support my contention that the explosion in Unit 3 was a combination of two things, hydrogen from delayed leakage of the primary containment and hydrogen from the SFP, vs an explosion immediately following hydrogen leakage from a damaged venting system in Unit 1, and delayed explosion of hydrogen only from the SFP of Unit 4.

Anton?
TCups neither you or I or any other forum contributer will determine the cause of hydrogen in Units 1, 2 and 3. Many will get Ph.D's in the future when studying this event.

I myself, as a problem solver, always look for common factors among multiple events, and will challenge easy or obvious solutions just to make every one think a bit deeper.

Here is another idea, the buildings are pretty air tight and normally under pressure so nothing can escape. Stale air is vented after scrubbing and cleaning, this I think happens at a common scrubbing station to the south of the plant next to the souther exhaust stack. Now my mad idea, what happened if building 4 distributed the hydrogen via the scrubber to all the other buildings, people where entering these to work on valves and check on the reactor, so doors would be open and possibly some vents if they exist, this would not have been necessary at unit 4 as nobody would want to enter unit 4, so if unit 4 started to pressurize as all doors are closed it would set up a transfer of air to the other buildings via the exhaust air venting system. One needs the air conditioning and venting details to check this.

As I said I can have some weird and un-imaginable ideas.


Follow the pipes to the south (top o picture) exhaust stacks
fukushima_daiichi_march14_2011 (wide angle)

Watch left exhaust stack (northen side) what is happening there? http://www.youtube.com/watch?v=RxAHo...eature=related (9-14 and 20-25 seconds)
fusefiz
#856
Mar22-11, 12:39 PM
P: 7
Where did UCS/All Things Nuclear find their information for the number of fuel elements in reactor 4's spent fuel pool? From memory, I believe their first number referenced two newspaper articles in Japanese. Again, from memory, I believe this was the number picked up by the NY Times (1479):
| http://www.nytimes.com/interactive/2...rs-status.html

The most recent figure of 1331 fuel elements from UCS/All Things Nuclear does not explicitly furnish the references:
| http://allthingsnuclear.org/post/400...s-at-fukushima

After a couple of days of interrogation, the French agency IRSN said last week that it had a "confirmed" number of 1500 fuel rods in reactor 4's spent fuel pool. This seems like a suspiciously round number, given that its "confirmed" counts for reactors 1 to 3 were 292, 587, and 514 respectively.

There is more information about the fuel pools in this recent documentation:
| http://resources.nei.org/documents/j..._16_Update.pdf

The following slide presentation (2 different links to the same document) mainly concerns dry storage and plans for future off-site storage, but it also contains information about onsite storage at Fukushima Daiichi:
| http://www.nirs.org/reactorwatch/acc...powerpoint.pdf
| http://www.zerohedge.com/sites/defau...nt%20Pools.pdf

The LA Times published a story with information from the NRC. The NRC believed it had "compelling evidence" that the reactor 4 spent fuel pool had a significant hole or crack and was empty. This evidence was "provided by key American contractors who were in the plant at the time".
| http://www.latimes.com/news/nationwo...413,full.story
The evidence to date, I believe, contradicts NRC's conclusion.

The French agency IRSN concluded that reactor 3's spent fuel pool was compromised, leaving as little as one meter of water (worst case) over the top of the fuel rods. In addition, I suppose all the pools could have some kind of cracks or slow leaks.

Last week IRSN was calculating how long it would take for the spent fuel pools to start boiling. Because reactor 4's pool has the most uranium, their calculations had it boiling first (on Monday of this week, I believe). But I suspect these calculations assumed a full pool. Boiling would start earlier if the pool water level were low.

Various reasons for fuel pool low water level have already been discussed in this thread -- here are some related links and short quotes.

| http://www.nytimes.com/2011/03/18/wo...pagewanted=all
Sloshing in California: "… much of the water may have sloshed out during the earthquake. Much smaller earthquakes in California have produced heavy water losses from sloshing at storage pools there, partly because the pools are located high in reactor buildings."

| http://spectrum.ieee.org/tech-talk/e...iation-worries
Sloshing in Japan: "Masashi Goto, a former Toshiba Corporation design engineer of nuclear containment vessels of the kind used in the Dai-1 Plant, said another possibility was 'sloshing': the water may have sloshed out of the storage pool due to the earthquake's shaking. Goto said this kind of splashing happened in 2007: 'This is what happened during the Kashiwazaki (Nuclear) Plant accident after the earthquake struck it and sloshed water outside the pool.'"

| http://allthingsnuclear.org/post/396...-fuel-pools-at
| http://www.ucsusa.org/nuclear_power/...-03-19-11.html
Gate seal deflation: "At the Hatch plant, it took, I think, about four or five hours for the inflatable seal to deflate, and 141,000 gallons of water, about half of the water of the spent fuel pool, leaked out through that little gap between the gate and the walls."

Here is a reference to general gate damage, which says there are in fact two gates in the pool inclosure. I suppose the second gate is used for removing spent fuel (and also for bringing in new fuel, although the water cover would be unnecessary for this).
| http://www.nytimes.com/2011/03/19/wo...pagewanted=all
"The steel gates at either end of the storage pool are also vulnerable to damage during an earthquake and could leak water if they no longer close tightly."

The explosion in the reactor 4 building blew out the metal roof panels. The French agency IRSN noted that this explosion also blew out the east and south concrete walls, and inferred that the explosion occurred (also?) underneath the service deck.

For the explosion in the reactor 4 building, most of the discussion I've seen on the internet concludes that it was a hydrogen explosion, with the the presence of hydrogen requiring the exposure of fuel rods in the pool. The French agency IRSN was the first source I saw that concluded the hydrogen was from radiolysis in the pool.

| http://en.wikipedia.org/wiki/Spent_fuel_pool
"Radiolysis, the dissociation of molecules by radiation, is of particular concern in wet storage, as water may be split by residual radiation and hydrogen gas may accumulate increasing the risk of explosions. For this reason the air in the room of the pools, as well as the water, must permanently be monitored and treated."

That little half-page Wikipedia discussion is not a great reference, but I have not found much else. A couple of online discussions I've read did mention the possibility of radiolysis as the source of the hydrogen, but dismissed this possibility. I wonder if hydrogen/oxygen bleeding into the building would be enhanced if the pool level were low and the water boiling (i.e., in this case would there be less recombination in the pool and thus more gas escaping into the air?).

While searching for info, I did run across this off-subject suggestion of using the pool water to generate hydrogen fuel:
| http://www.freepatentsonline.com/y2010/0072074.html

For the hydrogen explosions in reactors 1 and 3, most explanations refer to the venting of hydrogen (formed by the reaction of steam with hot cladding). Pool radiolysis could also contribute, although there is much less fuel in these pools than in the reactor 4 pool. I do not understand exactly where this gas would vented. The following discussion explains more about the venting process than I want to know as well as the role of carbonized coconut shells in nuclear reactors (without explaining exactly where the gas would be vented):
| http://www.electronicspoint.com/see-...t178032p2.html
(See the long post, the final post in that thread as I write this.)

There is an interesting alternative source of hydrogen:
" … my view a far more plausible explanation is that hydrogen routinely injected in the Make Up Water System to control the corrosives (mainly O2) produced by radiolysis was released suddenly and catastrophically from outside the containment and within the reactor building. In reacting with oxygen from the atmosphere within the building at the correct concentration of hydrogen (4-74%) only a spark is required to detonate a hydrogen oxygen explosion."
| http://bravenewclimate.com/2011/03/1...echnical-info/
Follow this link for additional discussion of this possibility. I wonder if the reactor 4 building also contained a hydrogen inventory, despite the fact that the reactor was unloaded?

A couple of general references:

Here is a discussion of containment structures, with diagrams of the GE Mark I confinement structure. This document has been very recently posted or updated, for it already contains a reference to the Fukushima incident. Note that Table 4 says that 2 US Mark I systems have reinforced concrete confinement structures, while 22 have steel confinement structures. I suppose the steel structures also are surrounded by concrete for biological shielding. I wonder which design is used in Japan?
| https://netfiles.uiuc.edu/mragheb/ww...Structures.pdf
"A venting system was in place at the Fukushima plants to help relieve built-up pressure. With electrical power cut off in the aftermath of the earthquake and backup sources of power either failing or exhausted, workers injected seawater mixed with boron into the reactor to maintain control reportedly using fire engines pumps. They had difficulty venting the resulting steam with a report that the pressure relief valves were operated manually."

I was once a research physicist (not nuclear). Now I am particularly interested this problem because I am an investor in would-be uranium miners (at least, since last week when their stock prices fell, I am an investor). Besides wanting to know how probable a real disaster is at Fukushima, I'm interested in the reaction of the Chinese and Indian public and government (these countries have the largest planned reactor building programs), the reactions of other investors, etc. The following is a long rapidly assembled report which takes a high level view of this incident (such as power generation and electricity shortages in Japan, Asian reactions, etc.)
| http://www.nautilus.org/
| http://www.nautilus.org/publications...anReactors.pdf
bondboy
#857
Mar22-11, 12:42 PM
P: 6
Just pulled this...

"Iodine 131 detected in Tokyo hit 12,000 becquerels, compared with the previous day: a tenfold increase in both radioactive Iodine and Cesium." As for Hitachinaka City, which according to SPEEDI has seen a surge in radiation over the past 24 hours, things are far worse: "Hitachinaka City, Ibaraki Prefecture, saw the highest radioactive values recorded, with 12,000 becquerels of cesium, iodine and 85,000 becquerels."

Per Asahi (google translated):

Ministry of Education, under the influence of Fukushima Daiichi nuclear power plant accident, announced the results of such measurements with radioactive dust fell from the sky. Tended to increase mainly in metropolitan areas. 5300 becquerels per square meter of cesium in Shinjuku, Tokyo 137,3 detection of iodine 131 becquerels 12,000, compared with the previous day, rose about 10 times the concentration of both. The values ??that affect health, but prolonged monitoring is needed.

Measurement of radioactive fallout, we put the nation at 9:00 am on October 22 from 9 am to 21 the ministry, were analyzed.

The value of Tokyo, yesterday's Cs 560 Becquerel, Becquerel 2900 soared from iodine. Announced value of the cesium 22, 8 / 1 40,000 becquerels of radiation controlled area reference value, iodine value, amount to five quarters.

The values of cesium in other municipalities, the 1600 Becquerel Saitama City (790 becquerels day), Kofu, 400 becquerels (the non-detection), Utsunomiya 440 becquerels (250 becquerels same), and rose across the board.

The day before, in Hitachinaka City, Ibaraki Prefecture, the highest values ??were recorded, although down slightly, 12,000 becquerels of cesium, iodine and 85,000 becquerels, still higher values ??are recorded. Fukushima and Miyagi can not be measured.

In the east, where it snowed a lot of rain and dust and floating in the atmosphere, believed to have dropped radioactive material. The short half-life of iodine, 8 days half-life of cesium in 30 years, continue serving after getting off the ground a long period of radiation. Soil and water, because it could lead to radioactive contamination of agricultural products, should continue to monitor future.
AntonL
#858
Mar22-11, 12:53 PM
P: 521
Quote Quote by bondboy View Post
Just pulled this...

"Iodine 131 detected in Tokyo hit 12,000 becquerels, compared with the previous day: a tenfold increase in both radioactive Iodine and Cesium." As for Hitachinaka City, which according to SPEEDI has seen a surge in radiation over the past 24 hours, things are far worse: "Hitachinaka City, Ibaraki Prefecture, saw the highest radioactive values recorded, with 12,000 becquerels of cesium, iodine and 85,000 becquerels."
Weather conditions would push the plume over Tokyo today
AntonL
#859
Mar22-11, 12:55 PM
P: 521
Quote Quote by fusefiz View Post
Where did UCS/All Things Nuclear find their information ....[/url]
fusefiz thank you for an in-depth contribution
TCups
#860
Mar22-11, 01:07 PM
TCups's Avatar
P: 494
I have been studiously avoiding network news coverage of the Fukushima situation. The coverage is pretty meaningless. I also studiously avoid all of the chatter about radiation exposure and the hyper-phobia most have about it. Instead, I have just been trying to figure out what the pictures I see mean and what really happened and why.

Edited to remove my soapbox moment.
AntonL
#861
Mar22-11, 01:25 PM
P: 521
Quote Quote by TCups View Post
I have been studiously avoiding network news coverage of the Fukushima situation. The coverage is pretty meaningless. I also studiously avoid all of the chatter about radiation exposure and the hyper-phobia most have about it. Instead, I have just been trying to figure out what the pictures I see mean and what really happened and why.

Edited to remove my soapbox moment.
Oh, but I did enjoy the bit about Knut, you did bring the point home
TCups
#862
Mar22-11, 01:27 PM
TCups's Avatar
P: 494
Quote Quote by AntonL View Post
Oh, but I did enjoy the bit about Knut, you did bring the point home
I suspect it was the radiation that got him.

Want to see how long the average American's attention span is and how big a deal the death toll and human suffering in Japan are? Cruise the headlines on Drudge today: http://www.drudgereport.com/

Enough said.
AntonL
#863
Mar22-11, 01:58 PM
P: 521
Quote Quote by TCups View Post
Enough said.
but I have to add, just read that taxidermy will preserve Knut for eternity

end of off topic discussion
bondboy
#864
Mar22-11, 02:02 PM
P: 6
yeah sorry, didn't mean to add to the udue hysteria currently plaguing the MSM. The levels are miniscule. I wouldn't characterize it as hormesis but at that specific activity, you're not going to see any hair loss or alteration in blood counts. The real concern IMO is contaminated food/water supplies where you can build up a concentration of slowly decaying gamma emitters which could pick off your bone marrow over time. Pancytopenia -> Death.
I'll try to control myself moving forward...:)


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