Japan Earthquake: nuclear plants

zapperzero

Eh. Maybe it's dry. Or maybe it's full.

rmattila

I don't think it would be possible for the water level inside the supression chamber to be below that in the torus room, as water is constantly being pumped inside the PCV and pumped out from the turbine buildings in order to keep the water level there about 1 meter below the ground water. I see no other mechanism than leaking to the torus room for the water in the PCV to get out, and this requires the water level in the PCV to be above that in the torus room.

EDIT: This was meant as a reply to a comment regarding the possibility of the water level in the PCV possibly being below that in the torus room. The comment was apparently removed while I was typing the reply, so this post is now quite irrelevant.

tsutsuji

Well, thanks for your reply anyway. Also the water level was measured with the endoscope as being a few centimeters above the drywell bottom. So it was quite stupid of me to imagine it could be much lower than this.

Tepconium-311

There is groundwater inflow and outflow in basements.
Just helping disposal of radionuclides dissolved in basement water by slowly diluting them into ocean via groundwater.

Proceeding in such manner is helpful reducing storage tank hassles.
Good old Tepco already did some necessary preparations.
For example, covering seabeds around Fukushima-1 with concrete.
This delays and dilutes groundwater-supported disposal by spreading over larger area.

To be honest, wouldn't be installing a water tight barrier too early just be a big mistake?

LabratSR

Typhoon Guchol to hit Japan,

http://www.theweatherspace.com/news/...hol-japan.html

http://www.wunderground.com/tropical.../wp201205.html

tsutsuji

http://www.tepco.co.jp/en/press/corp...5638_1870.html Release of the Fukushima Nuclear Accidents Investigation Report (Japanese only for now)

http://www.tepco.co.jp/nu/fukushima-...20619_02-j.pdf at 12:19 on 19 March an employee found 8 wounds and heard noise coming from the wounds in a gas duct of the PCV gas extraction system at unit 3. At 14:40 it was confirmed that the gas was not released outside the duct as the negative pressure was maintained. PCV pressure, PCV hydrogen concentration, PCV gas extraction system flow rate remain unchanged. As an emergency measure, the duct was repaired with tape.

http://www.tepco.co.jp/en/nu/fukushi...20619_02-e.pdf Unit 3 PCV Gas Control System Duct Damage

http://www.tepco.co.jp/en/nu/fukushi...20615_02-e.pdf The Protection Platform Installation on Unit 4 Spent Fuel Pool

( http://www.tepco.co.jp/en/nu/fukushi...20608_03-e.pdf Purpose of protection platform on unit 4 spent fuel pool - 2012-06-08 )

http://genpatsu-watch.blogspot.com/2...126191800.html (from 19 June Tepco press conference) and http://www.tepco.co.jp/nu/fukushima-...20619_02-j.pdf 2/2 : A worker working to prepare the ground for the foundations of the unit 4 cover structure had his fingers (of both hands) pinched at 10:30 on 19 June when he was changing the "pit" (a part at the tip) of a boring machine. A supposedly attached casing fell down. He was sent to the unit 5/6 medical room, then to J-village and sent from J-village to a hospital in Iwaki at 12:51. It will take him 3 months to recover.

tsutsuji

http://www3.nhk.or.jp/news/genpatsu-...620/index.html Tepco released its final report. It generalises saying "As preparations against nuclear accident were complacent, pratical thinking was not sufficient". But many questions such as the cause of the large radioactive substance releases or the consequences of the earthquake remain unanswered more than one year after.

The report is based on hearing 600 people, on onsite surveys and data analysis.

There is no big difference with the interim report as regards the accident's causes, and it concludes: "It is impossible not to say that retrospectively there was complacency as regards tsunami estimates, and the insufficiency of preparations to resist tsunamis is the fundamental cause".

The response to the accident is evaluated as being basically appropriate as the people onsite responded desperately in a situation that exceeded assumptions. About the operation of emergency cooling equipments that the cabinet investigation committee had criticized as being inappropriate, while recognizing that there are points where preparedness was insufficient, it merely argues in defense that "response was in fact difficult".

Then it concludes, "As preparations against nuclear accident were complacent, during the response they were unable to imagine what was really happening onsite, and practical thinking was not sufficient".

Concerning the interference of the government, instructions quite out of touch of the real situation onsite were directly or indirectly given, "the plant manager was only torn between conflicting demands, and it was not a way to improve accident containing results".

The report also includes concrete proposals for the future: to study accident management under the assumption that nearly all equipment functions are lost, to complete meltdown preventing countermeasures, about the chain of command during an emergency, and the way to release information to the population.

Nuclear engineering specialist, Mr Miyano of Tokyo university says the report "is not sufficiently analysing the problems in past countermeasures and regulations". "It is questionable whether the true nature of the accident can be approached with this report only. 'concretely what should be regretted, what should be changed ?' it is necessary to extract the lessons, but it is difficult for this to be done by the accident's main protagonist Tokyo Electric alone. The conclusions must be drawn by analysing from the eyes of a third party."

MadderDoc

I think I've finally figured out what those dark structures at the seaside of unit 2 and Unit 1 turbine buildings really are. :-( Darned to have been so daft, thinking about it I had boxed myself in the vain hope that it might have been something to do with basic ground work to stopping contamination of the ocean, but alas, it is likely not.

In all simpleness, I believe those dark structures have been the construction sites for the sections to cover the lower east part of Unit 3, towards its turbine building. Here seen in an image from late May 2012:



And here below is a marked up view to the putative construction site for those cover sections, detail from original photo taken on February 28th 2012:

MadderDoc

Yes, since water treatment started about a year ago, the volume of water Tepco is handling has roughly doubled, corresponding to a net accumulation of about 400 m³/day, and it is too much to believe that this net inflow figure represents _only_ inflow.

Now groundwater-supported disposal proper is not something that happens fast, if it were only that I suppose doing something effective about the problem might wait until 2014. But I think the case is that the ground we are talking about is a landfill, now turned a radioactive dump, and under the surface it is criss-crossed with trenches, pipes and ducts -- that the area on the whole is as designed to facilitate fast liquid discharge to the ocean, and not at all a slow leaching bed. In that situation, to let on that it can wait years to put a stop to it is just disgraceful.

SteveElbows

Not much left of the upper parts of reactor 4 building now. I believe what we may be seeing in this video is dust caused by the cutting away of remaining parts of upper north-west wall.

http://www.youtube.com/watch?v=ZrTcxVVU1ng

tsutsuji

http://www.tepco.co.jp/en/nu/fukushi...20608_02-e.pdf Pictures of the faulty pump cables.

This leak has been investigated: a water level meter was wrong.

http://www.tepco.co.jp/en/press/corp...5585_1870.html "The leaked water is assumed to have come from the coagulation-sedimentation equipment of the decontamination apparatus. As a result of site investigation on June 15, it is assumed that the leaking part is the interspace of the piping penetration hole on the top side of waste liquid strage tank. And also it is assumed that the water of the tank flowed out, since the water did not flow downstream by shutting down the flow regulating valve of downstream pipes due to instantaneous descent of the level meter of the tank and inflow from upper stream was continued. The integrity verification was conducted on the same day, and the problem was confirmed. The level meter has been decided to be fixed".

http://www.tepco.co.jp/en/nu/fukushi...20618_03-e.pdf "Investigation Result of the Water Leak from the Decontamination Apparatus" with pictures and diagrams giving details about the failed tank.

http://www3.nhk.or.jp/news/genpatsu-...626/index.html Tepco made additional measurements of unit 4's reactor building walls' tilt. Last month a tilt thought to have been caused by the bulge created by the hydrogen expolsion was found at the western wall with a measurement of a 3.3 cm tilt for 13 m of height, which was about half the limit set by the Building Standards Act. Now they found 4.6 cm for 13 m of height on the third floor on the western side. All tilts are within the limits of the Building Standards Act. Tokyo Electric says the pool is supported by other pillars, etc. that are different from the outer walls where tilting was found, and that as a result of seismic analysis, there is no seismic safety problem.

http://photo.tepco.co.jp/date/2012/2...20625_02j.html pictures of the unit 4 wall measurements (Japanese version)
http://www.tepco.co.jp/cc/press/2012/1205832_1834.html press release about the new unit 4 wall measurements (Japanese version)
http://www.tepco.co.jp/cc/press/betu...20625j0201.pdf press release attachment (Japanese version) (with diagrams, etc...) "Report dealing on a study about seismic safety taking into consideration local outer wall bulging at Fukushima Daiichi unit 4 reactor building"

zapperzero

Any words on measuring error? Or was there actual change between one measurement and the next?

zapperzero

Quite so. I wonder if anything of that can be seen on the newly-shielded radiation counters at the site boundary.
EDIT: I stopped wondering and started looking
http://www.tepco.co.jp/en/nu/fukushi...1_lgraph-e.gif
lo and behold, there is a slight uptick starting on 6/23 or thereabouts.

Joffan

I don't see the uptick, and I'm usually pretty good at spotting graphical subtleties. I wouldn't expect much because unit 4 wasn't very radioactive in the first place, and all (or almost all) the dust will be from concrete that hasn't seen the outside world since it was poured during construction.

zapperzero

Look again . The detector near the main building shows the most visible trend. You can also get the data in the tables (on the same page) and play with it. There might be another cause, of course, such as high winds.

tsutsuji

They are not measuring the same measurement points. The new measurement with the 46 mm horizontal difference is located on the 3rd floor, halfway between the rows R6 and R7, while the older measurement of "approx. 33 mm" for "West 2" in http://www.tepco.co.jp/en/nu/fukushi...20525_05-e.pdf 6/17, was located on the same floor but exactly on row R6.

There might be a small change of 1 mm between both measurements on west2/R6-3rd floor as the report now says 32 mm (instead of "approx. 33 mm").

I attach translations of the bottom of page 7/57 and of page 9/57 of http://www.tepco.co.jp/cc/press/betu...20625j0201.pdf

page 7/57

page 9/57

Attached Thumbnails

     

SteveElbows

The camera zoomed in further when they did the next days cutting operation on east upper wall:

http://www.youtube.com/watch?v=BlIr7w2Ymks

I'm more interested in how the painfully slow debris-removal is going at reactor 3, but cranes & stack tower tend to obscure the view of that, and we need a better resolution anyway.