Fukushima Japan Earthquake: nuclear plants Fukushima part 2

[Sotan]

From an NHK article related to the issue mentioned above:

"TEPCO: Water in reactor half expected level

Officials with the operator of the damaged Fukushima Daiichi nuclear plant say the water level inside the No.2 reactor's containment vessel is about half what they had estimated.

Workers with Tokyo Electric Power Company used robotic probes to measure the level and temperature of cooling water inside the vessel.

They found the water was around 30 centimeters deep. They had estimated it would be 60 centimeters, based on images captured by an endoscope 2 years ago.

The water was around 35 degrees Celsius.

TEPCO officials say this suggests the melted fuel is being kept cool. But they say they don't know whether the fuel is entirely submerged.

They say they suspect water is leaking into a unit called a suppression chamber via a pipe that's around the same height as the water. They believe it's then flowing out of the reactor building through holes in the chamber.

TEPCO is planning to plug the holes and add water to the containment vessel before removing fuel from the reactor.

Jun. 9, 2014 - Updated 20:31 UTC"

 

[Sotan]

Results of the inspection of the S/C (torus) room walls at Unit 1 (June 13)
-report (in Japanese) here.
- photos and video here.

The robot was inserted through a hole made in the Northern area and advanced on the outside catwalk through the torus room. The goal this time was to visually inspect the 5 pipe penetrations present in the area and to see whether there are any water leaks from them.

The robot also release "tracers", some small particles which, by moving while suspended in water, could help point out water flows and leaks.

A detail on page 3 shows that some silicon sealing material is poured in, at construction time, in the spaces between pipe and wall, where the penetrating pipes go through the wall of the torus room.

Result 1: when the camera, located in air, examined the 5 penetrations, the surface of the water including floating particles did not show movement.

Result 2: examination of the penetrations, by submerging the camera in water, did not reveal any significant damage of the silicone seal regions. (For penetrations 3~5 examination was not possible due to obstacles.)

Result 3: tracers released in water around the penetrations did not show movement.

They seem satisfied with the results as they indicate the robot is capable of doing its job well. For penetrations 3~5 they might later use another method of investigation, employing the robot that is prepared now for underwater examination in Unit 2. They were also planning an ultrasound examination but they will reevaluate if it s really needed in these areas, considering that these results seem to indicate there are no leaks here.

From page 8 we have another short report - Results of the investigation of the upper area of the SE-E region of the S/C in the same Unit 1.

This investigation was similar to those done on May 27 and 30; at those times these regions (X-5F) couldn't be checked.

No water leaks were found this time, and the only large obstacle on the catwalk was a piece of metal sheet from some insulation cover.


---------------
Personal comment:
If you watch the video: those tracers... Yes, there is no disturbance in the vicinity of the penetrations, but all tracers clearly move quite fast (or slow, depends on how you want to describe it), in a nice parallel flow. Is it normal to have water movement in the torus at this time?

 

[zapperzero]

---------------
Personal comment:
If you watch the video: those tracers... Yes, there is no disturbance in the vicinity of the penetrations, but all tracers clearly move quite fast (or slow, depends on how you want to describe it), in a nice parallel flow. Is it normal to have water movement in the torus at this time?

Normal? No. But there is water being pumped in and then out of the building. Presumably some of it flows through the S/C.

 

[Sotan]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2014/images/handouts_140618_12-j.pdf
(in Japanese)

They are forced to make some changes to the plan regarding moving all that fuel from the SFP at Unit 4 to the common SFP.

Basically, they have been taking out fuel units from SFP Unit 4 and moving them to the common SFP.
But the common SPF had been pretty full even at the time of the accident, so they have been "making room" in it by taking out some of the cold spent fuel from there and transferring it into dry casks.
There is a delay in the arrival of dry casks, so now they don't have enough room in the common SFP for the 180 units of new (unused) fuel which are still in the SFP of Unit 4.
They decided they will move these 180 units of unused fuel into the SFP of Unit 6.
But that one is full too, so they will make room by taking 230 units of [strike]spent[/strike] new fuel out of it and moving them into the... storage space for new (unused) fuel of Unit 6. (Corrected above. It's confusing: there are 248 new fuel units being stored into the "spent fuel pool", even though they are new, not spent; and 230 of those new units will be moved into the "new fuel storage space", where maybe they should have been from the beginning? They must have (had) their reasons.)
(I didn't understand why they need to do this last move, and not skip it and simply take the 180 new units from SFP 4 and put them into the "storage space for new fuel" of Unit 6. Then I found a note which said they are in fact considering this possibility too. Although it might lead to increased radioactivity in the air around this storage area, they believe it would be possible to shield it properly.) The final plan, when decided on, will be presented to authorities for approval.

Another operation will also be needed (page 5): bringing unit 6 in a state of "temporary closed" configuration, which also means the closing of the gate of the SFP at unit 5 (it is now open). Only in this configuration can they operate the casks for fuel transfer.

 

[zapperzero]

Meanwhile, jiji reports there's a bit of trouble with the ice wall
www.japantimes.co.jp/news/2014/06/1...ctive-fukushima-water-hits-snag/#.U6H6IyhiOsR

 

[nikkkom]

I don't understand what is the plan wrt water.
Do they plan to keep units flooded for decades on end?

 

[turi]

Tepco has posted some clarification regarding ice wall vs trench freezing: http://www.tepco.co.jp/en/press/corp-com/release/2014/1237950_5892.html

 

[Rive]

I don't understand what is the plan wrt water.
Do they plan to keep units flooded for decades on end?

AFAIK the plan is to 'corner' the water, that's OK. They will try to dry up the trenches, then the turbine buildings, and then when all the holes on the PCVs are patched the reactor basements.

What I can't understand is that how they plan to deal with the groundwater. Some contamination is already out and if they stop the inflow to the basements then it'll slowly contaminate the entire area within the frozen walls. That's an insane amount of ground to clean up.

Somehow they should keep up some kind of artifical/controlled water flow within the frozen walls.

Ps.: a good article about the trench/wall thing on ExSKF

 

[Sotan]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2014/images/handouts_140620_11-j.pdf
(in Japanese)

Two page report with several photos. They completed the removal of larger debris from the 1st floor of the Reactor 3 building, using remote-controlled robots. Gathered debris (pieces of concrete, fences, drum cans, nitrogen cans and radioactive paper waste) filled 38 bags of 0.5 ton capacity and 23 bags of 1 ton capacity. Small photos show two examples of areas before- and after debris removal.
On 6/23 they will begin the next step of decontamination using a vacuum-cleaner type robot (MEISTeR) which will retain and remove dust-size, powder contaminated debris.

(Note: 1st floor usually means ground floor in Japan.)

 

[nikkkom]

AFAIK the plan is to 'corner' the water, that's OK. They will try to dry up the trenches, then the turbine buildings, and then when all the holes on the PCVs are patched the reactor basements.

What I can't understand is that how they plan to deal with the groundwater. Some contamination is already out and if they stop the inflow to the basements then it'll slowly contaminate the entire area within the frozen walls. That's an insane amount of ground to clean up.

Why would you want to clean it up? It's already below ground and poses risk only to the bacteria in that soil. Digging it up creates more problems than it solves.

 

[Hiddencamper]

The bigger concern is with the water that leaks INTO the plant. Because this creates new contaminated water. If they can stop water leaking in, yes they may still have to deal with the stuff that's already gotten out, but they can prevent new contaminated water from being created. This greatly simplifies the problem.

However, the long term goal, and the reason they are looking to plug all the leaks, is to flood up the containment vessels to provide sufficient shielding so that they can open up the containment heads and start digging out the nuclear fuel.

 

[Rive]

Why would you want to clean it up? It's already below ground and poses risk only to the bacteria in that soil. Digging it up creates more problems than it solves.

Well, with time it'll make its way to the ocean.
I know that it's not really much as it is now (compared to the previously released amounts), but it would mean an unwelcome precedent. The water leaking IN creates contaminated water under control. The water leaking OUT creates contaminated water (and soil) OOcontrol. Even if the former - as measurable and visible - might be more sensitive topic, I don't like these stuffs stuffed under the rug.

I think the way through this is to decontaminate that water and release it afterwards.
The continuous failures of the ALPS is not really an excuse, there is no emergency now. They should be able to deal with it.

Previously there was some discussions about the release of water with tritium. I've found some interesting opinions regarding this: right now I'm checking the sources mentioned here.

 

[ronaldkr]

Previously there was some discussions about the release of water with tritium. I've found some interesting opinions regarding this: right now I'm checking the sources mentioned here.

Unfortunately the author of these pages, "The Hiroshima Syndrome", Leslie Corrice, seems to be a shill for the nuclear industry. Not only that he posits that tritium poses no risk for mankind ("oh, it's so small an energy of the betas" despite acknowledging that these betas are ionizing, only you must not call them "beta rays").
I read his tractate on Chernobyl (yes, I had better stopped, I know). He totally disappeared the xenon effect. But describing the aftermath he serves the sentence: "To be blunt, no negative long-term health effects have been detected in the monitored population, other than those that could have been medically anticipated if the Chernobyl accident had never happened." Tell that to the population. Even the governments know better.

 

[Sotan]

From the METI site:

Progress Status and Future Challenges of the Mid-and-Long-Term Roadmap towards the Decommissioning of TEPCO’s Fukushima Daiichi Nuclear Power Station Units 1-4 (Outline)(May 29, 2014)(PDF:4,510KB) PDF File

It's the English translation of the roadmap report of May 29th (most recent). You can find it here.

 

[nikkkom]

Unfortunately the author of these pages, "The Hiroshima Syndrome", Leslie Corrice, seems to be a shill for the nuclear industry. Not only that he posits that tritium poses no risk for mankind ("oh, it's so small an energy of the betas" despite acknowledging that these betas are ionizing, only you must not call them "beta rays").

I don't know anything about this guy, but re tritium, he is right. It's one of the most benign contaminants: low energy, not bioaccumulating, not accumulating in soils or sediment.

 

[ronaldkr]

[re tritium] It's one of the most benign contaminants: low energy, not bioaccumulating, not accumulating in soils or sediment.

Well, the "low energy" comes into play when tritium is an external contamitant. Electrons with av. 5.4 keV are sufficient to break bonds in organic matter. And there is some double action: the former T, now He will not bind to its former place, leaving an OH- or carbon radical, which is not helpful for cell chemistry either.

Indeed it's not bioaccumulating, and having a large body of water at the doorstep thinning would be a good idea. Good if the ALPS would be working. But then the introduction of tritrated water to the Pacific seems to be politically blocked, the credibility of both TEPCO and the government being below zero.

 

[Rive]

Unfortunately the author of these pages, "The Hiroshima Syndrome", Leslie Corrice, seems to be a shill for the nuclear industry.

As long as he is giving sources which can be tracked, checked for relevance, credibility and further sources I don't mind how is the man titled.

I'm not yet completely through tracking the sources down to the secondaries but till now that article seems to be correct.

 

[ronaldkr]

More on tritium: the report referenced by Sodan has this passage that indicates that TEPCO plans to do tritium removal.

8. Others
Public offering of the contaminated water-treatment technology verification project (tritium-separation technology verification test project) commenced
・ This project is conducted to collect the latest insights concerning tritium-separation technology as of today. Specifically, it aims to verify (1) the separation performance related to tritium-separation technology and (2) if the equipment is installed in the Fukushima Daiichi Nuclear Power Station, the construction and running costs of the equipment required to treat water after treatment by the multi-nuclide removal equipment, which is actually generated. This does not constitute confirmation that separation and treatment of tritium will commence.
・ The term of public offering is from Thursday, May 15 to noon Japan time on Thursday, July 17, 2014.
・ A briefing session is scheduled from 13:00 to 15:30, Tuesday, June 3, 2014 (planned), at the hall on the 1 st floor of Bellesalle Onarimon-ekimae. This briefing session will be simultaneously delivered via the Internet on the dedicated website of the Mitsubishi Research Institute, which serves as secretariat of this project. Following the briefing session, a video of the session will also be available.

 

[Sotan]

http://www.tepco.co.jp/nu/f2-np/handouts/j140624a-j.pdf
(in Japanese)

One page report – short but packed with info about Fukushima Daini plant. Summary as follows:
- The plant is still in stable cold shutdown state.
- The 764 fuel units from Unit 1 Reactor are being transferred to the Spent Fuel Pool (since June 2). Although the operation is basically automatized, people are stationed even on the Fuel Handling Machine to visually observe the work and make sure everything goes well. (One photo shows a worker looking into the reactor using binoculars.)
- 382 units of fuel have already been moved by June 13. In the upper right of the page there is a detailed presentation of the procedure for removing fuel units. For every group of 4 fuel units there is a control rod in the center. Two fuel units are removed so two are remaining, diagonally, to support the control rod. An auxiliary device is then inserted to support the control rod while the remaining two fuel units are removed. Then the control rod is pulled out, and then the auxiliary device removed. In all, it is computed that 1200 such “steps” will be needed to remove the 764 fuel units.
- Lower left rectangle talks about results obtained in 1 year of activity by the 4 teams established last year in July with an aim to improve the technical capacities of the plant staff. One team is responsible for removal of debris; one deals with “replacement of motors”, one with cables and one with pumps. They train to be able to get better at their tasks and to be able to make repairs and replacements quicker and better, if needed.
- Lower right rectangle speaks about the fact that on June 21 Unit 3 has reached 30 years since start of operation. The law requires an evaluation of the facility at this time. Tepco has applied for this evaluation. It has already received similar approvals for Units 1 and 2.

A little bit larger photos are available here.

Edit: sorry for the confusion, made it clearer now that this is about Daini plant.

 

[Sotan]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2014/images/handouts_140624_09-j.pdf
(in Japanese)

- Pages 1-9 present the planned investigation of S/C (torus) room at Unit 2 in Fukushima Daiichi, meant to check the functioning of two new robots that are developed for the purpose of finding the water leaks in such areas. The plan is to have this done by July 24.
- One robot floats through water and has mainly the role of taking images of pipe penetrations and walls. The other one crawls under water on the floor and performs Doppler (ultrasound) examination.

- From page 10 there is a report on what has been learned until now from research and investigations aimed at sealing the water leaks of the damaged reactors.
- Thus page 12 shows method considered for sealing water leaks in various areas of the lower side of the PCV. Weak points and strong points of each method are briefly stated. Red line shows the hypothetical new boundary of the PCV after sealing by use of those methods. The conclusion seems to be that the most promising method appears to be sealing the venting pipes that lead from the PCV towards the S/C.
- Page 13-17 deal with the investigations (performed until now and planned from now on) in the lower region of the PCV, both in order to discover leaks and to find ways how to plug them.
- Page 18 presents some results and plans for investigations of the upper region of the PCV, where there are pipe penetrations that may show cracks later on, after the PCV bottom has been fixed and they start raising the water level.
- Page 19 talks about investigations in the torus room using the two robots, one camera robot floating (suspended) in water and one ultrasound robot crawling on the floor (these two I mentioned in the previous post).
- Page 20 shows a proposed timeline of the various investigations mentioned above, for Unit 1. Page 21 = timeline for Unit 2. Page 22 = timeline for Unit 3.

 

[jim hardy]

(One photo shows a worker looking into the reactor using binoculars.)
- 382 units of fuel have already been moved by June 13. In the upper right of the page there is a detailed presentation of the procedure for removing fuel units. For every group of 4 fuel units there is a control rod in the center. Two fuel units are removed so two are remaining, diagonally, to support the control rod. An auxiliary device is then inserted to support the control rod while the remaining two fuel units are removed. Then the control rod is pulled out, and then the auxiliary device removed. In all, it is computed that 1200 such “steps” will be needed to remove the 764 fuel units.

They're lifting complete elements?
Do i understand then that they are in good enough shape to be lifted from the top, and so are the control blades?

 

[turi]

They're lifting complete elements?
Do i understand then that they are in good enough shape to be lifted from the top, and so are the control blades?

The report is about Daini, not Daiichi.

 

[nikkkom]

Well, the "low energy" comes into play when tritium is an external contamitant. Electrons with av. 5.4 keV are sufficient to break bonds in organic matter.

Wrong. Energy does matter a lot for internal irradiation too.

18 kEv electron from Tritium can break only a few bonds.

Compare that to two beta electrons from Sr-90 -> Y-90 -> Zr-90 decay chain, first electon is 546 kEv, second is 2280 kEv - more than two orders of magnitude more energy. They damage A LOT of molecules while decelerating.

 

[jim hardy]

The report is about Daini, not Daiichi.

Whew ! Thanks ..

 

[Sotan]

Sorry, wasn't clear enough. I edited that post to make it clearer.

 

[turi]

ALPS is fully back online:
http://www.tepco.co.jp/en/press/corp-com/release/2014/1238403_5892.html

On May 23 Unit B was the first to be restarted after the upgrades, followed by Unit A on June 9 and now Unit C on June 22.

 

[Sotan]

That's good news.
But there's some bad news too:
http://www3.nhk.or.jp/nhkworld/english/news/20140625_09.html

 

[Rive]

That's good news.
But there's some bad news too:
http://www3.nhk.or.jp/nhkworld/english/news/20140625_09.html

Ex-SKF article about the same thing.

 

[Sotan]

A new monthly "roadmap" report has been published on June 27. Unfortunately all materials are in Japanese only, at this time.
All the documents are here.
The summarized version of the progress report (the one that will be translated in about 2-3 weeks, if the past trend continues) is here.
I only took a quick look but it doesn't seem to contain new information, meaning which hasn't been at least mentioned here previously.
One exception - for me at least this was news: [STRIKE]the crane above the spent fuel pool[/STRIKE] a crane on the first floor at Unit4 is entering a mandatory inspection, which means that the extraction of fuel units from SPF 4 will take a break from July 1st till the beginning of September. This is a scheduled inspection, not an unexpected delay.

Edit: the crane and its location can be seen on the last page of this document.

 

[Sotan]

http://www.tepco.co.jp/nu/fukushima-np/handouts/2014/images/handouts_140707_01-j.pdf
(In Japanese)

They had to stop the cooling of the SFP at Unit 5 in Fukushima Daiichi, because of a leak that occurred at a valve located on the pipe that brings in sea water, to be used for cooling pumps and to remove heat from the water used for cooling the SFP.

The water leaked - clearly sea water, based on analysis, with no trace of radioactivity - amounts to ~1300 liters and most of it went down to the lower levels, about two floors.

The SFP is safe even without cooling for about 9 days. Should the repair last longer than that they consider diverting some cooling water from the circuits used for cooling the reactor itself. These circuits are working normally.