Fukushima Update - Water Decontamination System Pumps Fail

Update # 46: August 7, 2011

by Nelle Maxey

Cleaning and recirculating the huge stores of contaminated water stopped again today at Fukushima. This at the same time the levels of stored waters are again becoming critical. TEPCO must keep pouring water onto the reactor cores to keep them cool whether this is done with fresh water or with "cleaned", recirculated water removed from the stores of contaminated water. As of August 5, the level of water in the Waste Treatment Facility was only 12 inches below the maximum space available.

TEPCO can't keep the decontamination system pumps working, it seems. The system was down on both Thursday and Friday. The outage today seems more serious however with a number of pumps in various locations down. See the Physics Forum comments below for critical water levels and "corrosion and gunk" in the pipes followed by my comments on the volumes of decontaminated, desalinated and stored contaminated water.

Decontamination system stops at Fukushima Daiichi

"The operator of the Fukushima Daiichi nuclear plant is facing yet another problem with its wastewater filtering system. The system came to a halt again on Sunday.

Tokyo Electric Power Company has been filtering highly contaminated water in basements to remove radioactive material and then pump the water back into the reactors as coolant.

Shortly after 7 AM on Sunday, some of the pumps in a US decontamination device stopped and could not be restarted. The equipment is used to remove radioactive cesium.

About an hour later, a pump in a French device also stopped working.

A back-up pump also failed to work, bringing the whole decontamination system to a halt. TEPCO says it is continuing to inject cooling water into reactors by using treated water.

The decontamination system has faced earlier problems. On Thursday, another pump stopped at one time. On Friday, an alarm went off and the system stopped operating.

TEPCO added a Japanese-made decontamination device to the system to make it more stable. But the utility wanted to treat wastewater before the test run of the new device, because there is little available storage space for the contaminated water.

TEPCO is trying to determine the cause of the malfunctions while working to restart the system." Sunday, August 07, 2011 12:46 +0900 (JST)

Over at Physics Forum

There is an on-going discussion on the decontamination system shutdowns.

There is a link to a Japanese NHK story which says they have postponed the testing of the new SARRY decontamination system. Remember they had announced they were shutting down this weekend to test this system. Well, they can't now. Too much build-up of contaminated water with the decontamination system only working intermittently.

Here is a quote from the thread linked above:

"The 700 l leak rang an alarm, after which the facility was stopped for more than 2 hours. Tepco has decided to delay the test run of SARRY initially planned to be performed for 2 days starting from 6 August. It is delayed to the middle decade of August or later. The reason is that this test requires to shut down the whole facility for 2 days, but Tepco cannot afford to do this as the water level in a waste treatment facility basement reached 30 cm [12 inches] below the maximum on 5 August."

Here is a reply from another blogger which suggests the piping (and pumps?) are plugging up with "corrosion and gunk" leading to reductions in injection rates of cleaned water into the reactors:

"It's amateur hour in there, still. TEPCO should have been relieved of command long ago, they have zero experience with crisis management and it shows. Trouble is, no-one else seems willing to accept the responsibility.

I worry about the "injection rate reductions". It can only mean corrosion and gunk. Keep adding pressure and sooner or later something's gonna give. At least, there's no shortage of alternative feed lines to the RPVs for now, thank goodness."

Here is a brief rundown on the decontamination system volumes and the total amounts of contaminated water and their locations. TEPCO releases the total volumes of stored water and the total volumes of decontaminated and desalinated water on a weekly basis in the JAIF Status reports:

According to their latest report, on Aug 2 they had decontaminated 35,300 cubic meters of water. However they had only desalinated 12,500 cubic meters.

The water can't be recycled for cooling the reactors until the salt is removed. This is done by the American portion of the decontamination system which is now not working as the NHK story states. The French portion of the system removes radioactive cesium from the water. The Japanese SARRY system will serve this same function once they get it running.

The total amount of stored contaminated water was at 120,770 cubic meters on Aug 2. (This equals 2.7 million Imperial gallons.)

25 percent of the water is in the Waste Treatment facility, 75 per cent is in the basements and tunnels of the reactor and turbine buildings.

When these areas reach capacity, water is transferred to the Waste Treatment facility which is now reaching maximum capacity itself.

The 12,500 cubic meters of desalinated water to date means only 10% of the stored water has been fully treated for use as recycled cooling water in the reactors. It is easy to see why the water in storage is building up. The 35,300 cubic meters of treated (but not desalinated) water represents 30% of the stored water.

Another interesting fact is that the 3 reactors (Units 1, 2 and 3) receiving recycled water now are using approximately (the injection rates fluctuate) 2,000 cubic meters of water per week. So the 12,500 cubic meters of desalinated water represents a 6 week supply of cooling water at current rates.

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