#Fukushima I NPP: Plan C Also Failed in Plugging Reactor 2 Trench... Now What?

Plan D of Course!

But first, recall that Plan A was to install freezing pipes at the head of the trench leading from Reactor 2 turbine building to create an ice plug so that the extremely contaminated water that had been sitting in the trench since the very beginning of the nuclear accident could be pumped out. TEPCO started the work in April this year.

That failed. The ice plug didn't quite form.

Then recall that Plan B was to dump tons (literally) of ice and dry ice in the trench near the freezing pipes to lower the temperature of the water around the freezing pipes so that the ice plug would finally form. Workers dumped ice all day and all night, in the high ambient radiation right at the trench. That was in hot August. Try to freeze the trench with ice in hot August.

That also failed. Dry ice clogged the pipe, and the ice plug didn't quite form, and TEPCO admitted there was water still coming into the trench from the turbine building. The water sitting in the turbine building comes from the reactor building after it cools the molten core somewhere in the building, and it is warm.

So TEPCO came up with Plan C.

What was Plan C? It was to fill the gap between the incomplete ice plug and the turbine building wall with fillers. TEPCO chose the combination of grout and concrete. A plug of ice, grout and concrete was formed. Sort of.

From TEPCO's document uploaded at Nuclear Regulation Authority's site on 11/21/2014, the plug - pink and light green in the diagram is grout (different types), dark green is concrete:

That failed, just as I predicted.

TEPCO finally admitted on November 17 that it was a failure after pumping out some 200 tonnes of this highly contaminated water on November 17 and seeing that the water level in the trench didn't go down as much as they had calculated. The water was still coming in from the turbine building, and the groundwater was probably seeping in.

But not to worry. TEPCO has Plan D, and it has been already approved by Nuclear Regulation Authority.

So what is Plan D? To fill the trench with cement while pumping out the water that gets displaced (in theory) by the cement.

(Do you want to bet whether that is going to fail?)

From Mainichi English (11/18/2014), from the original Japanese article on 11/17/2014:

An effort to stop contaminated water from flowing into a trench at the crippled Fukushima No. 1 Nuclear Power Plant failed to completely halt the flow, announced Tokyo Electric Power Co. (TEPCO), the plant's operator, on Nov. 17.

A TEPCO representative said, "We believe we have not completely stopped the water. Groundwater may also be entering the trench. We will closely analyze the changes in water level in the trench."

TEPCO says that when around 200 tons of contaminated water was removed from the trench, the water level in the trench should have fallen by around 80 centimeters if the point of leakage between the plant's No. 2 reactor turbine building and the trench had been fully sealed. However, the water level only fell by 21 centimeters, so TEPCO determined that the leak must be continuing.

...While the water remains in the trench, TEPCO cannot create a planned underground wall of frozen soil around the No. 1 through 4 reactor buildings to stop water leakages.

And this image from Tokyo Shinbun (11/21/2014):

and reference to Plan D:

トンネルから汚染水を少しずつ抜きながら、水中で薄く広がる特殊なセメントを流し込んでトンネルをふさぐ方法への切り替えを提案する

(TEPCO) will propose (to Nuclear Regulation Authority) a new method of plugging the trench by pouring in the special cement that spread thin and wide in the water while removing the contaminated water in the trench gradually.

Special cement?

TEPCO says in the document (page 9) they submitted to NRA that it will be a mixture of cement, fly ash and underwater-inseparable admixtures (セメント、フライアッシュおよび水中不分離混和剤などの配合調整). They will use the tremie concrete placement method.

(Do you want to bet whether that is going to fail?)

The NRA meeting on November 21, 2014 was funny without participants intending to be funny, from what I read in the tweets by people watching the meeting.

At one point, Commissioner Fuketa exasperatedly asked TEPCO representatives, "So what was the point of trying to freeze the water? Was freezing even necessary at all?"

The answer was no. TEPCO's Shirai admitted (according to the tweet by @jaikoman on 11/21/2014) that there was a talk inside TEPCO that the ice plug was not necessary.

So why did they do it, and why did NRA approve it?

No one knows and no one is held accountable, while workers had to set up freezing pipes, then to pour ice, dry ice, grout, concrete, and to pump this highly contaminated water over the past 8 months in high radiation exposure. TEPCO hasn't disclosed the radiation exposure for the workers.

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#Fukushima I NPP Progress Report on Ice Plug in Reactor 2 Trench: Time for Plan C (and Diaper Polymer May Be Back...)

Plan A, if you recall, was to freeze the highly contaminated water at the head of the trench right outside the Reactor 2 turbine building (Shaft A, on the northeast corner of the turbine building) to create an ice plug by placing several freezing pipes in the trench. Why is a plug needed? Because TEPCO wants to drain the highly contaminated water from the trench.

What TEPCO did not say was the existence of many obstacles at the trench head - i.e. numerous pipes for electrical wires and water transport. So the freezing pipes couldn't be placed in part of the duct where these pipes go through, and after two months of trying TEPCO admitted to the problem that the water remained unfrozen. Also, TEPCO admitted that there was a constant flow of water from the turbine building into the trench through many openings (pipes go through the building walls into the trench after all) that prevented the water from freezing. (Duh.)

(A red-shaded rectangle in the bottom right in the slide below is the intended ice plug)

So, on to Plan B.

Plan B, if you recall, was to dump crushed ice and dry ice to lower the temperature of the water in the trench to 5 degrees Celsius so that (in TEPCO's mind) the water would freeze even if there was a flow of water:

Plan B ran into trouble almost as soon as it started in late July, when crushed dry ice clogged the pipe in early August and crushed ice was seen floating around on the water surface (see photo). In the end, laws of physics prevailed and the contaminated water did not completely freeze, as TEPCO finally admitted, albeit in a very convoluted way in their report to Nuclear Regulation Authority on August 19, 2014 (Japanese only, PDF).

The report by TEPCO claims that 92% of the ice plug was formed in the Reactor 2 Shaft A. Well, a failure is a failure, as TEPCO admits the water continues to flow from the turbine building into the trench even at a faster speed now that the opening is narrower.

What's worse, in the open duct that TEPCO dug at a different location (southwest corner of the Reactor 2 turbine building), the water hasn't frozen at all despite 2 months of effort using the freezing pipes.

The water temperature remains mostly above 8 degrees Celsius:

and no sign of ice:

So now, time for Plan C.

So what is Plan C? Use some (yet to be determined) type(s) of filler to completely fill the trench head, while the water is still running.

So, what are the materials TEPCO says they are considering? According to TEPCO's report on August 19, 2014 (page 24),

• sand (drawback: can't stop water, can't be dumped in large amount)

• iron sand (can't stop water, can't be dumped in large amount)

• sodium polyacrylate, aka "diaper polymer" (has to be used in combination with other methods)

• grout (depending on the types, may not fill small/large gaps)

• solidifying material (mixture of powder and liquid; powder may clog up the pipe)

• waterglass (cannot fill openings)

Hmmm, diaper polymer, waterglass... where did I see this before?

April 2011, at the water intake for Reactor 2, where pouring diaper polymer and concrete in the pit didn't stop the extremely contaminated water from pouring into the plant harbor. That water did not stop until waterglass was injected into the base rock UNDERNEATH the trench.

I have a feeling they will soon need Plan D.

But why fight running water? Why can't they just pump out the water right there at the shaft?

Or as one of the long-time readers of this blog "netudiant" suggested before, why not build a mobile ALPS on a barge inside the harbor?

I think I know the reason: It simply doesn't occur to them. Just like it didn't occur to them to transport batteries for controlling the reactors without the required government permit, on March 12, 2011. (See my post from October 6, 2012.)

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#Fukushima I NPP Progress Report on Ice Plug in Reactor 2 Trench: Dry Ice Clogged the Freezing Pipe, No Discernible Effect on Freezing the Contaminated Water

The latest on the progress (or lack thereof) of TEPCO's tragi-comical effort to freeze highly contaminated water in the trench leading from the Reactor 2 turbine building (see my post on 7/28/2014 for details) is that the pipe they've been using to dump ice and dry ice got clogged with dry ice. TEPCO admits there has been no discernible effect of ice/dry ice on freezing the water.

So what's your Plan C?

From TV Asahi News (8/12/2014; part):

“切り札”投入したら「詰まった」東電・福島第一

Fukushima I NPP: TEPCO plays its "ace", which ends up clogging the pipe

福島第一原発の汚染水対策として、地下の坑道を凍らせて水を止める工事で、凍結の“切り札”として投入されたドライアイスの効果が表れていないことが分かりました。

It has been revealed that dry ice, which is being poured [into the freezing pipe] as the surest bet to freeze the water in the underground trench as part of the measures to deal with contaminated water at Fukushima I Nuclear Power Plant, has had no effect.

国と東電は、高い濃度の汚染水がたまる地下の坑道に金属性の管を設置し、冷却液を流して汚染水ごと凍らせる作業を続けてきました。しかし効果が表れないため、先月30日からは氷の投入を始め、今月11日朝までの間に、合わせて222tの氷を投入しました。東電は11日の会見で、凍結の効果について「分からない」としていて、目に見える成果が出ていないことを認めました。さらに、凍結の“切り札”として7日にドライアイス1tを投入しようとしたところ配管が詰まってしまい、それ以降はドライアイスの投入を見合わせているということです。

The national government and TEPCO have been trying to freeze the highly contaminated water in the underground trench by installing a metal pipe and pouring liquid coolant through the pipe [since April this year]. But as the effort has failed to freeze the water, TEPCO has started to pour ice since July 30. Total 222 tonnes of ice have been poured into the pipe as of the morning of August 11. In the press conference on August 11, TEPCO said the effect [of ice] in freezing the contaminated water was "unknown", admitting that there was no discernible effect. Further, when they tried to pour in 1 tonne of dry ice on August 7 as the "surest bet" to freeze the water, it clogged up the pipe. TEPCO has halted the pouring of dry ice.

The pipe through which workers have been dumping ice and dry ice (from TEPCO's photos and videos library 7/24/2014):

The pipe (in purple color) in the diagram:

I am grateful for the news, because it gave me the first laughter of the day. Laughing is good for one's health, I hear (regardless of the topic, I hope).

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(UPDATED) #Fukushima I NPP: TEPCO Defies Laws of Physics Claiming Water Freezes at 5 Degrees Celsius as Workers Dump Ice into Reactor 2 Turbine Bldg Trench

(UPDATE 8/12/2013) Plan B (ice/dry ice) seems to have failed. See my latest post.

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(UPDATE) According to @jaikoman who follows and tweets on every single TEPCO and NRA press conferences, TEPCO poured ice and dry ice, thinking ice would float, cooling the top layer of water, and dry ice would sink, cooling the bottom layer of water.

Well they need a Plan C. Dry ice pieces they pour were apparently too small, and they all floated. Water remain unfrozen, and TEPCO says they will know by mid August whether the operation will work.

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TEPCO says by dumping ice and dry ice they can lower the temperature of the contaminated water in the trench to about 5 degrees Celsius, then they will be able to form a continuous ice plug.

Here I thought that water freezes at zero degree Celsius. As the whole world is seemingly going crazy afresh this July, maybe TEPCO is correct that water does freeze at 5 degrees Celsius.

From TEPCO's photos and videos library, 7/24/2014:

On July 24, 2014, TEPCO started the experiment of dumping ice into the Reactor 2 turbine building trench, trying to freeze highly contaminated water which has refused to freeze despite 3 months of freezing effort. Workers dumped only 2 tonnes of ice, or 4 bags with 500 kilograms of ice each.

Workers seem to be wearing vests, probably to shield ambient radiation. The location is the oceanside (east side) of the turbine building, where, according to the latest survey map by TEPCO as of July 8, 2014 (which I had a very hard time locating in TEPCO's updated site) the radiation level looks to be about 0.20 millisieverts (or 200 microsieverts) per hour. According to TEPCO, workers spent two and a half hours dumping 2 tonnes of ice using shovels.

Locations of the trenches filled with highly contaminated water (most likely from April/May 2011), and the locations in blue squares TEPCO wants to create ice plugs so that no water from the turbine buildings enters the trenches, from TEPCO's presentation to Nuclear Regulation Authority on 7/7/2014, when TEPCO disclosed that after three months of attempt, the water was still not frozen (English labels are by me):

Part of TEPCO's survey map (7/8/2014) showing ambient radiation levels, with "Shaft A" marked (by me) in red square:

So why isn't the water freezing? According to TEPCO's convoluted explanation to NRA on 7/7/2014, it is because of the fluctuation of water levels in the turbine building which creates water flow through the gaps created by the pipes that go through the turbine building walls. The flow was strong enough to disturb the freezing process, which TEPCO hadn't anticipated from the mock-up.

I do remember from January, I believe, a meeting at Nuclear Regulation Authority in which TEPCO and NRA commissioners discussed these ice plugs. Commissioner Fuketa openly questioned the efficacy of the scheme, asking TEPCO why they were planning to create a plug right outside the turbine building where lots of pipes are going through in a narrow space, as you can see even in TEPCO's simplified presentation to NRA on 7/7/2014 (English labels are by me) below.

The red rectangle right outside the turbine building is the ice plug to be created. The purple pipe in the diagram going down to the red rectangle is where workers were dumping ice.

Commissioner Fuketa also expressed doubt that it would ever freeze. I think he even asked what TEPCO's "Plan B" was, in case it would not freeze. TEPCO's answer was that it would freeze. (Watching this futile exchange live, I kept thinking, "Why can't they just pour concrete?")

Well the water didn't freeze. Nowhere close. TEPCO's measurement shows the temperature of part of the water which should have frozen is as high as 15 degrees Celsius, after 3 months of freezing.

So dumping ice and dry ice, then, is TEPCO's "Plan B". And ask the god of physics to look the other way and make water freeze at 5 degrees Celsius at sea level.

Ahhh good (bad) old days are back... when TEPCO used diaper polymers, saw dusts, shredded newspaper to try to stop the same highly contaminated water in the same set of trenches from pouring into the plant harbor.

It feels it was only yesterday.

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