Tuesday, June 28, 2011

Keeping Up the Appearance: TEPCO's Water Circulation System to Cool the Reactors

The system, as currently set up, is actually increasing the amount of highly contaminated water by 72 tonnes per day, because TEPCO is mixing in the fresh water.

This is the system diagram from TEPCO on June 28 press conference. It appears that the contaminated water is fed from the subdrain outside the Reactor 2 turbine building and from the Reactor 3 turbine building. Nothing from the Reactor 1. The treated water is combined with fresh water before it gets fed to the reactors. Water flow is being adjusted by the numerous valves (lower right of the diagram):

On a separate PDF file, there is an even more convoluted diagram of the contaminated water treatment system by Toshiba-Kurion-AREVA-Hitachi. By switching the valve, they can process the water in AREVA's system first, and then in Kurion's. Considering the frequent downtime of Kurion's system (vessels need to be changed often and flushed often), maybe that's a good idea.

This how it is all laid out physically, including PVC pipes connected to 4 kilometers long.

There are two more diagrams of the system. You can view all 4 diagrams in this file here.

Not so good news is hidden in one of the diagrams (page 3 of the above file) that says "Flow Rate of Treated Water Injected to Reactors: 13 cubic meters/hour".

The current total amount of water being fed to the reactors is 16 cubic meters/hour. They are using fresh (filtered) water in the amount of 3 cubic meters/hour.

So, at least for now, they are still ADDING the contaminated water by 72 cubic meters, or 72 tonnes, per day.

Well, that's infinitely better than adding 400 to 500 tonnes of it every day, like they have been doing for the past 3 months or so.


netudiant said...

As long as the system can process some 1200 tons/day to about 0.1% or less of the original contamination level, it does not matter even if TEPCO were to use exclusively fresh water to cool the reactors, because the water in the plant is getting removed gradually and shifted to lower level contamination storage tanks.

For a jury rig, this is performing pretty well, at least imho. That said, the replacement of zeolites by silica mentioned by TEPCO suggests Kurion is no longer involved.
Has that been confirmed?

Anonymous said...

Look at schematic #1 of this post. Reactor #4 and it's turbine building are not included in the water treatment and cooling systems. So there is no water being pumped OUT of the basement.

According to Tepco the water in the Spent Fuel Pool of #4 has been at 93 degrees Celsius for days now. I saw them pouring in cooled (fresh?) water with the longneck giraffe crane from the southside.

Still water in basement of the #4 Turbine building has DECREASED according to Tepco's latest press release.

Now, if that spent fuel pool is already filled to the brim with water, and they're pouring in more cooled water, where does the excess water go?

Oh, of course...



This excellent NHK-video (28.03.11) explains how and why.

Very illuminating, rarely honest, runs 07:25m


netudiant said...

There are 1200 tons of water removed daily from reactors 2 and 3 for treatment, according to the schematic. The site is sufficiently damaged that there are probably leak paths between the various units, so it does not much matter where the water is drawn.
The essential is to get as much water processed as possible as soon as possible, because that is the largest pool of contamination.
Reusing some of the cleaned water makes good sense and eventually we may be able to estimate the leakage into the groundwater by tracking how much makeup water needs to be added.
If TEPCO can clean up the plant water, it will have cut the accident emissions in half or more. That would be good news for everybody.

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