Japan Earthquake: nuclear plants

tsutsuji

Quote by SteveElbows

Page 6 we see an example of how to fix leaks at the large equipment hatch, with diagram.

I had seen that diagram a number of times, but I did not realise what this was about. As it was only this diagram without a narrative and without dimensions, not being aware that there was a trouble at unit 3 and that this was badly needed, I though it was just an example, of the kinds of technologies that might be needed if you want to enter the PCV with a robot or something.

MadderDoc

Quote by SteveElbows

<..>
Reactor 2 they have the assumption that water in the torus room may have helped cool the S/C

Perhaps that is more like a fact than an assumption:

"From approximately 01:00 until around 02:00 on March 12, the shift team members
equipped with self-contained air breathing sets (self-air-set), small flashlights and rubber
boots went to the RCIC room on the first basement floor of the R/B of Unit 2 to inspect
the operating condition of the RCIC system. The RCIC room was flooded
and the water level was just below the upper edge of their rubber boots.
When they opened the door, water gushed out of the room and they could not go in."

"At approximately 02:10 that day (March 12th), members of the shift team with the same outfits as the previous
went to the RCIC room of the R/B at Unit 2. Though the level of water inside the room had risen,
the shift team members went inside to check the operating condition of the RCIC system.

"It was confirmed with Unit 2 at around 04:00 on March 12 that water level showed a
decrease for the condensate storage tank, the water source for the RCIC. Accordingly,
the shift team decided to change the water source for the RCIC from the condensate
storage tank to the S/C in order to maintain the water level of the condensate storage
tank and control increase in S/C water level."
accordingly..
"From around 04:20 to around 05:00 that day, some shift team members wearing the
level C outfits and full-face masks went to the RCIC room on the first basement of the
Unit 2 R/B. The RCIC room was flooded and the depth of water was up to about the
upper edge of the rubber boots the team members were wearing
and the temperature and humidity were high. "

MadderDoc

Quote by SteveElbows

Page 17 we see a robot view up the north-east stairs of reactor 3, where there is much debris. Daylight can be seen through hole above. I attempt to relate this to recent discussion about black/hole area of reactor 3, and offer the suggestion that a stairwell in this area is involved.

The outline of the landing of that staircase at the fifth floor is somewhat north of the big black hole. I believe its outline can be made out from photos of the building top, but its state cannot be seen since too much debris has landed on top of it. I believe the view up to the sky has been enabled by yet another black hole in the fifth floor, east of that staircase landing, and close to the wall. This latter hole seems to have relatively clean edges, and to coincide with the position of some stationary equipment likely connected to a penetration of the 5th floor there. The equipment at the wall in that corner of the building was pushed out through the wall frames during the explosion, and could be seen hanging on to the wall outside apparently in defiance of gravity, before that platform for debris clearance came up.

SteveElbows

I speak of assumptions because this stuff is about modelling, and the assumptions they feed into the model. I do not doubt that there was water in the torus room.

westfield

Quote by MadderDoc

Unless we will introduce assumptions of something quite out of the ordinary about the pool (e.g. a leak/sloshing/siphoning event that had drained most of its water, or re-criticality), the pool could not have been a meaningful source of steam in the context of the unit 3 explosion.<snip.

Cheers.

MadderDoc

Quote by SpunkyMonkey

Thanks tsutsuji!

Looks like the track guide of the FHM is located (identified as '3' on the overhead map photo above) about right where we'd expect it to be, implying that the crane was just slightly dislodged from its track and fell straight down from where it was, still largely in its original east-west orientation.

However note that '4' , photographed in a perpendicular to direction to '3', and at some distance from it, is the lower NW end of the north face of the bridge, which on the intact machine was mounted just above, and only a meter away from the track guide. Indeed the video of '4' shows the flange through which this corner was connected to the frame piece that is/was mounted on top of the track guide (albeit the mounting flange now looks sadly beaten up, de-bolted and without its partner)

MadderDoc

Quote by SteveElbows

I speak of assumptions because this stuff is about modelling, and the assumptions they feed into the model. I do not doubt that there was water in the torus room.

Sorry, I think it was the pleonastic use of 'assumption' and 'may' in your expression that threw me off.

westfield

Quote by MadderDoc

<snip>
I believe the view up to the sky has been enabled by yet another black hole in the fifth floor, east of that staircase landing, and close to the wall. This latter hole seems to have relatively clean edges, and to coincide with the position of some stationary equipment likely connected to a penetration of the 5th floor there. The equipment at the wall in that corner of the building was pushed out through the wall frames during the explosion, and could be seen hanging on to the wall outside apparently in defiance of gravity, before that platform for debris clearance came up.

U3. FL5, NE corner - large ducting right in the corner diving down into the floor & possibly the gravity defying equipment near it -

westfield

Quote by MadderDoc

However note that '4' , photographed in a perpendicular to direction to '3', and at some distance from it, is the lower NW end of the north face of the bridge, which on the intact machine was mounted just above, and only a meter away from the track guide. Indeed the video of '4' shows the flange through which this corner was connected to the frame piece that is/was mounted on top of the track guide (albeit the mounting flange now looks sadly beaten up, de-bolted and without its partner)

The orientation marked "4" on that diagram is misleading.

In the video & still shot marked "4" we are viewing the vertical plane of the northern side of the bridge not the horizontal "top" of the bridge as the arrow tends to indicate. What we are seeing most of is the personnel "catwalk" with the driveshaft under it which is\was? bolted along the northern face of the FHM bridge proper.

In the video we only see a small glimpse of the main part of FHM bridge truss structure in the background, through the "catwalk" truss and possibly the FH Machine itself in the furthest background. It's very difficult to tell how "apart" the various sections of the whole FHM are but as Madder Doc mentioned, it's clear the heavy "end" piece shown in view "3" parted from this catwalk section in view "4".

Here is a quick diagram I made that didn't turn out that clear and features some terrible abuses of perspective & photoshop :)

Also, to be clear, it's comparing to Unit 2's FHM which is a little different but close enough for the purpose. There are just no decent images of the northern side of U3's FHM as it was.

PS - if this sort of post is getting just too off track then someone please say so - it is a bit of a messy thread at times and perhaps another thread for this sort of PCV hatch \ FHM \ Holes in floor type of discussion would be useful and make this sort of thing less disruptive to this thread? Perhaps rename & recycle the Unit 2 thread which is very quiet.

clancy688

Different Topic:

Unit 1 IC mystery - why did they shut down the IC on March 11th after 6 pm when they activated it barely a couple of minutes ago?

So I had this idea...

Here's a 1991 GE patent for an Isolation Condenser:

http://www.patentgenius.com/patent/5158742.html

It's noted that:

In order for the isolation condenser to be effective for maximizing heat transfer from the reactor steam to the pool water, the tubes must be relatively thin and single walled, but, they must be also strong enough to contain the relatively highpressure of the reactor steam being channeled therethrough. Since the reactor steam is channeled through the containment building and through the condenser tubes disposed outside thereof, the tubes themselves provide only a single barrier againstrelease of the reactor steam, which is radioactive. If one or more of the condenser tubes fails during operation, the reactor steam will leak into the isolation pool and be released through a conventional vent to the atmosphere, which therefore wouldrelease radiation to the atmosphere outside the containment building.

In order to reduce the risk of radioactive steam release from the condenser in the event of a failure thereof, conventional isolation valves are provided both in the conduits leading from the pressure vessel or containment building to theisolation condenser and in the conduits returning the condensed steam back to the pressure vessel. The isolation valves are normally closed valves which must be energized to open during operation so that, upon any failure of the isolation condenserwhich might release steam therefrom, the fail-safe condition will allow the valves to close upon interruption of power thereto which will stop the flow of reactor steam to the isolation condenser and, therefore, prevent any further release of radiationto the atmosphere.

Perhaps they feared that high reactor pressure would burst the IC-tubes? And that's why they shut it down...

MadderDoc

Quote by westfield

The orientation marked "4" on that diagram is misleading.

I see what you mean, it also thought it could be more instructive. But the intent of the arrow to mislead is plausibly deniable. The arrow points as best it can to an object that is not visible in the drawing.

Here is a quick diagram I made that didn't turn out that clear and features some terrible abuses of perspective & photoshop :)

Neat. See that is more instructive! Attached is a suggestion for modification of the markup of unit 3 added x-beams, as I think they are at that end of the bridge.(Lest it might mislead into thinking you've seen more of the length of the bridge in that video, than you actually have.)

MadderDoc

Quote by clancy688

<..>
Perhaps they feared that high reactor pressure would burst the IC-tubes? And that's why they shut it down...

Yes, maybe. According to the most recent narrative of events, the IC was switched on, while it was observed whether steam would be emitted from the IC exhausts. (Immediate powerful steam emission from the exhaust on operation of the IC was apparently thought of as indicating correct operation) As little or no steam was observed it was thought the system was not operating properly due to low water level in the condenser, and the system was shut down out of fear that "uncooled steam may cause IC pipes to break and result in releasing contaminated radioactive steam into the atmosphere."

zapperzero

Quote by westfield

PS - if this sort of post is getting just too off track then someone please say so - it is a bit of a messy thread at times and perhaps another thread for this sort of PCV hatch \ FHM \ Holes in floor type of discussion would be useful and make this sort of thing less disruptive to this thread? Perhaps rename & recycle the Unit 2 thread which is very quiet.

I'd rather not, given the #3 explosion thread debacle. Perhaps we all could start using post titles properly instead?

tsutsuji

http://www.meti.go.jp/earthquake/nuc...120423_02n.pdf Plan to reduce volumes of groundwater seeping into units 1~4 buildings by groundwater bypass

Page 2/12
Outline
Measures dealing with liquid waste

Concerning liquid waste, in the future we shall perform the necessary studies mentioned below, and by performing the related countermeasures, it is intended not to simply release contaminated water into the sea.

①Radical measures against groundwater seeping into reactor buildings, etc., which is responsible for water increase.
②Measures for securing the upgrading of the decontamination capacity of the water decontamination facilities and for securing the stable running of those facilities including backup equipments to be used during breakdowns.
③Further installation of onshore equipments for contaminated water management
It must be noted that without the approval of concerned ministries, releases into the sea will not be performed.
↓
It will continue in the future
↓
As a radical measure against groundwater seeping into buildings, we are currently working for the recovery of the subdrains, but especially around the reactor buildings, the radiation dose being high, the degree of difficulty is high.
↓
As an auxiliary measure in support of the subdrain, the following items are proposed:
↓
■ The groundwater that flows down from the mountain side is to be pumped from a point upstream from the buildings (O.P. + 35 m level), and the watercourse is changed (groundwater bypass).
■ As a consequence of the groundwater bypass, the underground water level in the surroundings of the buildings (especially on the mountain side) is lowered, and the seeping volume into building basements is regulated.
■ The pumped water is bypassed to the sea using a special channel. Also, monitoring of the water quality is performed.

Page 3/12
Concept

Present status
■Water mainly flows through the permeable layer from mountain side to seaside.
■Part of the groundwater seeps into the buildings during its way to the sea → increase of accumulated water inside buildings
■In order to regulate the volume of groundwater seeping into the buildings, the subdrain system is under restoration

↓
Proposal
■ The groundwater that flows down from the mountain side is pumped from a point upstream from the buildings, and the underground water's watercourse is changed (groundwater bypass).
■ As a consequence of the groundwater bypass, the underground water level in the surroundings of the buildings (especially on the mountain side) is lowered, and the seeping volume into building basements is regulated.
■As before, the subdrain system restoration work continues

Page 4/12
Feasibility status

Page 5/12
Estimated effects
Assumption used to calculate effects : groundwater flows through building side walls as a consequence of the difference between the groundwater level and the inside building water level.

tsutsuji

page 6/12
Implementation steps
【Step 1】 check of water quality using the existing 3 boreholes
【Step 2】 check of water quality in pumping wells (sequentially implemented)

【Step 3】 Lowering of groundwater level due to groundwater bypass (gradually implemented)

* As a result of operating gradually and of monitoring, implementation is done while checking water quality and groundwater level decline status etc.
* In accordance with the groundwater level decline, the lowering of the buildings' accumulated water levels is performed.
* As the lowering (recovery) of the water level surrounding buildings takes several months, water level management is carefully performed so that the buildings' accumulated water does not leak outside.

page 7/12
Abridged schedule

While checking water quality and groundwater level decline status, etc. , implementation is done gradually and carefully.

tsutsuji

page 8/12
Attachment 1: Present status of groundwater water quality

*Cs-134 and Cs-137 are, as shown below, below 1 Bq/l when added together.
*In the future, continuous monitoring is planned

Analysed nuclides : all gamma nuclides, all alpha, all beta nuclides, tritium
Analysis results : all gamma nuclides, all alpha, all beta nuclides were below detection threshold

※ detection threshold : all alpha = 3.0 Bq/l, all beta=6.7 Bq/l, Cs-134, 137: see table below

※ radiation monitoring performed by ministry of environment for groundwater and public bodies of water

Tritium detection

* At A and C it is not detected. At B a low concentration (one thousandth of the notification standard) was detected.
* It is presumed that as a consequence of the nuclear plant accident, tritium was released as steam, and fell on the ground, and was absorbed.
* The beta rays generated by tritium have a low energy and the effect of exposure is small.

measuring time= 15,000 seconds, notification threshold= 60,000 [I guess it is Bq/l]

tsutsuji

page 9/12
Attachment 2: Check of feasability (seapage flow analysis) (1)
Groundwater level status (subdrain shutdown)

page 10/12
Attachment 3: Check of feasability (seapage flow analysis) (2)
Groundwater level and flow speed vector (subdrain shutdown, groundwater bypass in operation)

page 11/12
Attachment 4: Check of feasability (seapage flow analysis) (3)
Groundwater level decline

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SteveElbows	I speak of assumptions because this stuff is about modelling, and the assumptions they feed into the model. I do not doubt that there was water in the torus room.