Japan Earthquake: nuclear plants

M. Bachmeier

Does anyone know about the use of hydrogen peroxide in BWR's during shutdown. I'm interested in storage (in or out of reactor building), added concentrations in reactor and SFP.

For example:

"Appropriate biocides (hydrogen peroxide) at concentrations up to 1000 ppm were added (to the pool water) to control biofouling."

From: http://www-pub.iaea.org/MTCD/publica...e_0944_scr.pdf

Also anyone with knowledge about what chemicals might be stored/used (in or near reactor) during BWR shutdown that might interact with hydrogen peroxide (powerful oxidizer).

I have a feeling that hydrogen peroxide may have played a role in the explosion at the Fukushima Diiachi #4 reactor building.

I_P

My assessment, FWIW, is that TEPCO was mandated by the government to come up with a plan - so they have, in consultation with experts in and outside of Japan. Given what they know about the state of affairs, the plan is a reasonable place to start. However, working against them are: they don't yet appear to have a clear idea of the state of damage to the reactors (and the four units each have different problems). High radiation levels remain an obstacle to good assessment and will hamper remediation efforts. They really need access by workers to execute the cooling plan; There is a continuing threat of more aftershocks causing further damage and complications; failure of the cooling system now in place could lead to additional release of radiation and change the ground rules; because the state of damage is unknown there is always the possibility that, despite the current appearance of stability, processes at work in the reactors and fuel storage areas could lead to currently unrecognized problems.

This article from Asahi lays some of it out:
http://www.asahi.com/english/TKY201104190193.html

I would also say that the nuclear power community as a whole does not have a clear idea of how to proceed with so many unknowns - the problems faced are quite difficult and appropriate tools and procedures are lacking. Look at the debate on the pool chemistry taking place here and elsewhere - its all a 'grand' experiment - both fascinating and terrible at the same time.

rowmag

The first one is a suppression chamber strainer that they replaced.
The second one is inspected points on the jet pumps that are arrayed around the outside of the shroud.

Looks like they found a leaking fuel assembly. See page 26:
http://www.tepco.co.jp/nu/f1-np/pres...a/bi8a09-j.pdf

Would something like that have been left in the SFP after replacement, or would it have been stored in isolation somewhere else?

ascot317

Especially this being Japan.
I mean look at that:
http://www.youtube.com/watch?v=cFVlzUAZkHY

I can't figure out how they suddenly seem to be a 3rd world country in terms of technology.

Dmytry

article from 2000:
http://search.japantimes.co.jp/cgi-b...0000413b5.html
they cancelled the project within a year under notion that they don't need that.
Both Germany and France offered robots ages ago.

Joe Neubarth

I am quite a few pages behind, but before I go to bed, I wanted to ask to see if I am out in left field with a broken mitt.

TEPCO is still pouring water into the top of Reactor Two. Days ago there was steam flowing out to assure us that the reactor core was being cooled.

Now, the water is not reaching the core as no steam is being generated, but hot gases are erupting from the reactor as if it was a volcano.

Dudes, is this the beginning of a China Syndrome situation. Where the 'ell is the core? Maybe somebody has already answered this, if the water always seeks lowest ground and the core is going down as it melts what else could be happening? The Core went right and the water is going left or vice versa? How?

Is the core in the earth under the plant and debris has fallen in on it and the water has flushed a path to the sea or some underground pocket.......

Dmytry

i think core is in RPV cooking itself, and I think consequences of this may - in worst case - leave you wishing that it just melted through and mixed with some molten concrete etc, blown itself apart, or did something else that'd make it cook colder. I really have no idea into what fractions the corium is going to fractionally distillate itself, and I do not want to get educated on this topic by experimental data. I only know that the hotter fuel cooks, the more stuff gets out of it, and I estimate it can boil itself. Literally.

MJRacer

From

at about 51 seconds

at about 2:05



Why does it look like this?:



Notice how close the top of the reactor is to the outside wall in Mark I containment systems:



I have marked in red the part of the drywell that seems to have been blown away. But, if so, how?!!!

hoyrylollaaja

That is the control room, supposed to be at high SW corner of RB.

|Fred

where did you see that , I must admit i no longer watch nhk 247 (especially since they resume regular program)

ascot317

Only that it doesn't look like this and is nowhere close to it. Look a few frames back and forth. The Drywell is >10m wide and round, the piece in the video isn't.

|Fred

It does not, and it is not.
I can not be 100% positive that it is the floor control basement the only picture we have for this control room are from unit 3 an do not match

MJRacer

The object I have circled in red looks like it is round and does not appear to be in the corner, but away from both walls a certain distance.

Here is appears to be a picture of the control room:

MJRacer

Exactly. The drywell appears to be completely gone and it appears as if we are looking right at the stainless steel reactor vessel (sans yellow cap).

ascot317

No, not exactly. I'm saying your observation is wrong. This isn't a part of the drywell. And it's surely not a part of the pressure vessel. AND the yellow cap isn't part of the pressure vessel, either, it's part of the drywell/containment.

MiceAndMen

In your first picture you can see the drywell cap in the background (yellow). It is sitting on the floor of the refueling level in the reactor building. That floor is several meters above the top of the drywell cap when it's in place. There is no part of the reactor or drywell vessel high enough to block the view of the yellow cap when it's removed and on the floor.

As for the second and third pictures, at that point in construction the reactor vessel would not be in place yet. The middle picture shows the upper part of the drywell sticking up out of the construction site. Whatever the bulky thing in the top picture is, it's not part of the drywell or reactor vessel.

razzz

Everything is not totally wasted. Things could be worse, another good sized earthquake could finish off SFP 4 or even cause more junk to fall into it including the other pools. It flood and bleed for now, I don't think corium is traveling freely as the flooding along with nitrogen injection is preventing Unit 1 from freaking out again. 2 & 3 sitting might as well be sitting in a overflowing swimming pools but with such high contamination readings you can't do any meaningful work on any of them until they cool down.

TEPCO seems the most worried about Unit 4's pool so you know where their head is at.

They need to convert a Bobcat simulator(s) to real-time viewing/controls and keep cleaning up using remote operators before attempting the big stuff. If they can keep the contamination mostly localized anything escaping will hopefully just dilute in the air and water. Just don't need any more big event's.

I notice the think tank on this forum is pretty much silent and they are in the industry so they might know more than they are willing to say. Can't blame'em.