#Fukushima I Reactor 2: Thermocouples in Containment Vessel Are Acting Up Again

The temperature is either 88 degrees Celsius, or 20 degrees Celsius, depending on which thermocouple you believe.

Or none of the above, and both thermocouples are broken. Given the previous history (from 2012 when one thermocouples after another was failing inside the Containment Vessel of Reactor 2), it is possible that both are broken.

Mainichi Shinbun (4/7/2015) reports:

福島第１原発:２号機格納容器内の温度計が異常な上昇表示

東京電力は７日、福島第１原発２号機格納容器内の温度計が異常値を示したことを明らかにした。

３日午前５時に２０．９度だった温度が同１１時に７０度に急上昇。５日午後５時には８８．５度まで上昇したが、２号機の別の温度計は平常値を示しており、東電は「原子炉の制御に影響はない」として、原因を調べている。

Thermocouple inside the Containment Vessel of Reactor 2 at Fukushima I Nuclear Power Plant shows abnormal rise in temperature

On April 7, TEPCO disclosed that a thermocouple inside the Containment Vessel of Reactor 2 at Fukushima I Nuclear Power Plant showed abnormal temperature.

The temperature was 20.9 degrees Celsius at 5AM on April 3 but it rapidly rose to 70 degrees Celsius at 11AM. On 5PM on April 5 it further rose to 88.5 degrees Celsius. Other thermocouples show normal temperatures. TEPCO says "It does not affect the control of the reactor," and is currently investigating.

Here's the latest temperature parameters for Reactor 2 Containment Vessel from TEPCO's plant parameters page, which omits the particular thermocouple that spiked:

So which thermocouple spiked? It is the thermocouple "supply air D/W cooler(TE-16-114K#1)". There is a site that continues to plot charts from the plant parameter data disclosed by TEPCO, and here's the chart plotting all "supply air D/W cooler" thermocouples:

Looking at the chart, it is more likely that this particular thermocouple broke, and the temperature inside the Containment Vessel remains between 20 and 30 degrees Celsius.

Quickly checking the measuring devices installed inside Reactor 2 (information from TEPCO's site), broken and malfunctioning devices are numerous.

As of July 2014, only 8 thermocouples out of 24 inside Reactor 2 Containment Vessel are monitored in accordance with the safety procedures set by regulatory authorities (meaning only 8 are properly functioning), according to TEPCO's information.

In contrast, 16 thermocouples out of 21 are functioning properly in Reactor 1 Containment Vessel, and all 19 thermocouples are functioning properly in Reactor 3 Containment Vessel.

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#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: Source of Neutron Detected on March 13-15, 2011 May Be Plutonium and Uranium Released by Core Melt

(UPDATED with clarification on the neutron dose rates in the translation, and information on the monitoring car at the bottom.)

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that then somehow escaped from the Reactor Pressure Vessel, Containment Vessel, and finally Reactor Building, according to TEPCO.

TEPCO just released the latest reports of its on-going data analysis and simulation of the nuclear accident at Fukushima I Nuclear Power Plant that they've been doing since 2011. I'm reading the report, but for now I quickly share a short snippet that piqued my interest.

In sum, TEPCO now thinks the source of neutrons detected right after the start of the accident in March 2011 was the actinide species including plutonium and uranium that somehow escaped the reactors as the reactor core melted (which more or less coincided with the rise in pressure inside the reactors), and neutrons were emitted by spontaneous fission of plutonium and curium.

Neutron detection on March 13 is attributed to the core melt of Reactor 3, and detection on March 14/15 to the core melt of Reactor 2.

Just how did those actinide species escape the pressure vessels and containment vessels? TEPCO only says continued investigation is needed to understand the mechanism and to secure the safety of workers at the plant.

From one of TEPCO's reports titled "Relationship between the neutrons detected at the time of the accident and the core melt" (original in Japanese, quick translation is by me, subject to change later; part):

(Background)

モニタリングカーは、3 月 13 日早朝、及び、3 月 14 日夜から 3 月 15 日未明にかけての二つの期間に中性子を検出した。検出された中性子の線量率は、中性子検出器の検出限度の 0.01μSv/h、および、その 2 倍の 0.02μSv/h と非常に小さい値である。測定場所は正門近辺であり原子炉建屋からかなり距離が離れた場所であることから、原子炉から直接飛来した中性子を検出したものではないと考えられるが、放射性物質が放出され発電所内のガンマ線の線量率が上昇したタイミングで中性子が検知されたという状況でもないため、これまで中性子の検出の原因については不明としてきた。また、発電所内の土壌から、ウランやプルトニウム等が検出されているが、その漏えいタイミング、経路についても不明としてきている。 ここでは、これまでに明らかになった福島第一原子力発電所 1～3 号機の事故進展挙動から、中性子検出についての説明を試みる。

Our monitoring car detected neutrons in two periods - in the early morning of March 13, and from the evening of March 14 to the early hours of March 15. The dose rates measured were extremely low: 0.01μSv/h (detection limit of the neutron detector) and 0.02μSv/h. The location where neutrons were detected was near the main gate of the plant, far away from the reactor building; thus it is considered that the neutrons detected did not come directly from the reactors. At the same time, the neutron detection didn't coincide with the rise in gamma ray dose rates as radioactive materials were released. So far, the reason why neutrons were detected has been deemed unknown. Uranium and plutonium have been detected in the soil inside the plant, but the timing of the leak and the leak process have also been undetermined. In this paper, we will attempt to explain the detection of neutrons based on the accident development behavior of Reactors 1 through 3 at Fukushima I Nuclear Power Plant which has been revealed so far.

(Detection of neutrons on March 13, 2011)

表１に 3 月 13 日に中性子が検出された時刻を示す。図 5 は正門付近での線量率（ガンマ線）の時間変化を示したものに、中性子の線量率が 0.01μSv/h となった時刻のプロットを青、中性子の線量率が 0.02μSv/h となった時刻のプロットを赤としたものである。中性子が検出された 3 月 13 日の午前は、9 時頃の原子炉減圧とそれに伴う S/C からのベントの影響で線量が上昇しているが、中性子検出とガンマ線線量率の変化に相関関係は見られない。すなわち、中性子検出は、ガンマ線線量率の上昇の原因となった放射性物質放出とは、関係しない現象によって引き起こされたものと考えられる。

Table 1 shows the time when neutrons were detected on March 13. Chart 5 shows the change of the dose rate (gamma ray) at different times near the main gate, with times when the neutron dose rate was 0.01μSv/h marked in blue and with times when the neutron dose rate was 0.02μSv/h marked in red. In the morning of March 13, the dose rate rose due to reduction of pressure in the reactor and vent from the suppression chamber. However, no correlation can be observed between the detection of neutrons and the change in gamma-ray dose rate. In other words, the phenomenon that caused the neutron detection was not related to the release of radioactive materials that caused the rise in the gamma-ray dose rate.

(Table 1)

(Chart 5)

一方で、厳密には一致しないが、原子炉水位の変化から予想される、3 号機で燃料溶融が発生したと推定される時間帯を考慮すると、中性子検出と燃料溶融の関連が示唆される。すなわち、燃料溶融により一部気中に放出されたウランやプルトニウムなどのアクチニド核種が、ガンマ線線量率の上昇を引き起こした放射性物質放出とは異なる経路で原子炉建屋外に漏えいし、これらに含まれるプルトニウムやキュリウム等の自発核分裂により放出された中性子が検出された可能性がある。実際、過去の核実験時のフォールアウトによって蓄積したプルトニウムと同程度ではあるものの、プルトニウムの同位体組成から、明らかに福島第一原子力発電所での事故起因と考えられるプルトニウムが、発電所構内の土壌中から 検出されている。

On the other hand, although it is not an exact match, when we consider the time period when the core melt started in Reactor 3, as estimated from the change in water levels in the reactor, there may be a relationship between the detection of neutrons and the core melt. In other words, some actinide species such as uranium and plutonium were generated because of the core melt, and leaked outside the reactor building through a different route than the one in which the release of radioactive materials that resulted in the rise in the gamma-ray dose rate took place. In fact, plutonium has been detected in the soil inside the plant; even though it is about the same level as plutonium accumulated in the soil from the past atmospheric nuclear testing, it is clearly originated in the Fukushima I Nuclear Power Plant accident as determined by the isotopic composition.

なお、中性子が検出された正門付近は、図 6 に示すとおり約 1km 距離が離れていることから、原子炉からの中性子を検出したものである可能性は小さい。

The main gate where neutrons were detected is about 1 kilometer away from the reactors as shown in the Chart 6, and the possibility is small that neutrons from the reactor were detected.

(Chart 6)

(Detection of neutrons on March 14/15, 2011)

一方で、図 7 に中性子の検出時間と 2 号機の原子炉・格納容器圧力の関係を示すが、中性子は原子炉圧力の上昇が始まった後に検出されている。前述の通り、この原子炉圧力上昇は、消防車による注水が炉心部に到達し蒸気が発生したことによると考えられ、また、この際には水-ジルコニウム反応が発生して大量にエネルギーが放出され燃料が溶融したと考えられる。すなわち、原子炉圧力の上昇のあった時間帯に発生した燃料溶融によりウランやプルトニウムなどのアクチニド原子が一部気中に放出され、ガンマ線線量率の上昇を引き起こした放射性物質放出とは異なる経路で原子炉建屋外に漏えいし、これらに含まれるプルトニウムやキュリウム等の自発核分裂により放出された中性子が検出された可能性がある。

Chart 7 shows the time when neutrons were detected and the pressure inside Reactor 2's reactor/containment vessel. Neutrons were detected after the pressure inside the reactor started to rise. As we said before, this rise in pressure in the reactor is considered to have occurred when the water injected from the fire engine reached the reactor core and generated steam. This also caused the water-zirconium reaction which released a large amount of energy, causing the fuel to melt. In other words, our hypothesis is that core melt took place during the time period when the reactor pressure rose, releasing part of the actinide atoms such as uranium and plutonium. These actinide atoms then leaked outside the reactor building through a different route than the one in which the release of radioactive materials that resulted in the rise in the gamma-ray dose rate took place. Then the spontaneous fission of plutonium and curium released neutrons, which were detected.

(Chart 7)

I'll try a separate post on the mechanism of Reactor 2's core melt, which was accelerated, or so TEPCO thinks, by water injection by the fire engines.

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As far as I remember, there was one monitoring car at the time of the accident at Fukushima I NPP. I'll try to verify, but I do recall wondering aloud why there wasn't any more monitoring car at the plant. There was no electricity at the plant during the time period this TEPCO's paper covers, and the plant's regular monitoring stations were not working (as they operate on electricity). Power to the plant wasn't restored until early April, 2011.

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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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Nikkei Shinbun's Interview of Haruki Madarame (4/7): The Worst Case Would Be "High-Pressure Melt Through", Politicians Thought Recriticality Was Nuclear Explosion

(Continued from Part 1, Part 2 and Part 3, from Nikkei Shinbun: Testimony of Dr. Madarame, in the third year of the accident: "Worst case scenario was possible for Fukushima" by Junichi Taki, editorial board member)

■「食い違いがあることに気づかず議論をしていた」

"We were talking past each other, and we didn't even know it."


――12日午後に１号機で爆発が起きたとき、どう思ったのか。

--What did you think when an explosion happened in Reactor 1 in the afternoon of March 12, 2011?

「映像を見た瞬間に水素爆発だと思った。その時の記憶はあいまいだが、下村健一・内閣審議官（当時）の書いたものよると、私は『建屋に水素が漏れて、建屋には水素があるので爆発した』と淡々と説明したとされている。多分、事実だろう」

"I thought it was a hydrogen explosion the moment I saw the image. I don't remember clearly, but according to what Kenichi Shimomura, who was a cabinet counselor at that time, wrote, I calmly explained that "hydrogen leaked into the building, and since there is hydrogen (sic) [probably "oxygen"] in the building an explosion happened." I think it is probably true."

「この爆発を機に、首相は私の言うことを信用しなくなった。『安全委員会にはほかに専門家はいないのか』と問われたので、『久木田豊委員長代理（当時）も詳しい』と答えると、『すぐに呼べ』と言われたので、久木田さんに来てもらい、私はオフィスに戻った」

"From this explosion on, Prime Minister stopped believing me. He asked me if there were other experts at the Nuclear Safety Commission. I answered that Acting Chairman Yutaka Kukita was also knowledgeable. He told me to "call him here immediately". So I had Mr. Kukita come, and I returned to my office."


――１号機の爆発のあった時間帯は、海水注入の議論をしていたころでもある。

--Around the time of the Reactor 1 explosion, the debate was ongoing on seawater injection [into the reactors].

「（海水注入の議論の中で）『再臨界の可能性はあるか』と首相から問われたら、『可能性はある』と答えたとしてもおかしくない。私には尋ねられた記憶がない」

"In discussing the seawater injection, it would not be odd if I had been asked by Prime Minister whether there was a possibility of recriticality and I had answered there was a possibility. I have no memory of being asked."

「実は水素爆発の前の時点から、海江田万里・経産相（当時）が議長になって海水注入の問題点を総理応接室（官邸５階）で話し合っていた。塩が析出し腐食も問題になるので長期間は無理だが、いまは炉心を冷やすことを何より優先し海水を入れろと私は主張していた。首相が海水注入を止めるよう言うはずはないと思う。海水注入中断の問題は、国会事故調査委員会などが指摘するように東電の武黒一郎フェローの勝手な判断が介在していたように思う。いずれにしても、吉田昌郎所長（当時）の判断で注入の中断はなかった」

"Even before the hydrogen explosion, Minister of Economy Banri Kaieda was chairing a meeting in the PM Reception Room (on the 5th floor of the PM Official Residence), and we were talking about the potential problems of seawater injection. I insisted that seawater be injected as cooling the reactor core was the first priority, even though it was not a long-term solution because of salt deposition and corrosion problem. I don't think Prime Minister would order a halt in seawater injection. The issue of halting the seawater injection arose, as pointed out in the National Diet accident investigation commission, from an arbitrary decision by TEPCO's Fellow Ichiro Takekuro. In any way, there was no halt thanks to Plant Manager Masao Yoshida."

「後に福山哲郎・官房副長官（当時）はじめ、政治家の人たちの著書を読んで気がついたのだが、みなさん再臨界イコール核爆発だと思っていたらしい。再臨界が仮に起きても核爆発とは違うことは、ＪＣＯ事故などからも明らかだ。食い違いがあることに気づかず議論をしていた」

"I realized later when I read books by politicians including Mr. Tetsuro Fukuyama (then-Deputy Chief Cabinet Secretary) that everyone had thought recriticality meant nuclear explosion. It is obvious from accidents like the JCO accident that even if criticality happens that's different from nuclear explosion. But we were talking past each other, and we didn't even know it."

――その日は深夜に自宅に戻るが、すぐにまた官邸に呼ばれる。

--You went home late that night, but was called back soon to the PM Official Residence.

「ほとんど寝ていない。ただ13日になると、いろいろな専門家から見解を聞く余裕が出てきた。とくに久木田さんとの意見交換は貴重で、その時点で最も怖いのは高圧溶融物放出（ＨＭＴ=High-pressure Melt Through）という現象だと意見が一致していた。これは溶融燃料によって圧力容器の壁が溶けて薄くなった末、圧力容器内と格納容器の圧力差によって燃料が容器を突き破って外に飛び出す現象だ。格納容器の壁まで貫通してしまう恐れがある」

"I hardly slept. But on March 13, I began to have more time [or "peace of mind"] to listen to other experts. Discussion with Dr. Kukita was particularly valuable, and we both agreed that the most frightening possibility at that time was the phenomenon called "High-pressure Melt Through" (HMT). HMT happens when the melted fuel melts the Pressure Vessel wall thin, and the melted fuel gets ejected through the Pressure Vessel due to the difference in pressure between the Pressure Vessel and the Containment Vessel. It is possible that the melted fuel could pierce through the wall of the Containment Vessel."

「14日の３号機の水素爆発の後、２号機の逃がし安全弁を急いで開くように助言したのは、２号機でＨＭＴが起きるのを心配して、圧力容器と格納容器の圧力を均一化した方がよいと考えたからだ。吉田所長はまずベントの準備を整えてからと主張していた。安全弁を開くと圧力容器内の水が水蒸気となって格納容器に流れ出し、燃料が空だきになる恐れがあるので、注水の備えがないと安全弁を開けない。難しい判断だ」

"After the hydrogen explosion of Reactor 3 on March 14, I advised that the relief safety valve of Reactor 2 should be opened quickly. I was worried that HMT might happen in Reactor 2, so I thought it would be prudent to equalize the pressure in the Pressure Vessel and the Containment Vessel. Plant Manager Yoshida insisted that preparation for the vent be done first. If the relief safety valve is opened, the water inside the Pressure Vessel becomes water vapor and flows into the Containment Vessel, leaving the fuel heated without water. So you cannot open the relief safety valve without preparation to inject water. It is a difficult decision."

――そう考えると、原子炉の底部から溶融燃料が落ちたのは不幸中の幸いと言えるか。

--In that sense, it was lucky that the melted fuel dropped from the bottom of the reactor.

「そうとも言える」

"You could say so."

班目氏の行動（３月13日）
3:40ころ 自宅で原子力安全委事務局からの電話
5:00ころ 官邸へ（官邸到着前に安全委オフィスで他の安全委員らと意見交換）
この間、３号機の高圧注水系停止などの事態が進む
10:04 原子力災害対策本部の会議
13:55 安全委オフィスに戻り、官邸の状況を説明
14:35 官邸へ
この間、保安院の安井氏らも加わって、３号機の水素爆発の可能性を議論
15:30 官房長官記者会見に同席（これ以降、数回）
21:35 原子力災害対策本部の会議
久木田委員長代理と最悪のシナリオを議論。政治家にメルトスルー後のコンクリート反応を説明

Dr. Madarame on March 13, 2011:
3:40AM received call at his home from the secretariat of the Nuclear Safety Commission
5:00AM went to the PM Official Residence (after speaking with other commissioners at the Nuclear Safety Commission office)
The situation at the plant grew more serious as Reactor 3's high-pressure core injection system stopped.
10:04AM meeting of the Nuclear Disaster Response Headquarters
1:55PM went back to the Nuclear Safety Commission office, and explained the situation at the PM Official Residence
2:35PM went back to the PM Official Residence
Discussed the possibility of a hydrogen explosion in Reactor 3 with others including Mr. Yasui from NISA
3:30PM accompanied Chief Cabinet Secretary [Edano] in the press conference (would do a few more times later)
9:35PM meeting of the Nuclear Disaster Response Headquarters
Discussed the worst case scenario [high-pressure melt through] with Deputy Chairman Kukita of Nuclear Safety Commission. Explained the core-concrete reaction after the melt through to the politicians

It is interesting to note that, according to Dr. Madarame's March 13, 2011 schedule, he was debating with another nuclear expert (Kukita) about the worst case of "high-pressure melt through", in which the melted core (corium) will eject from the Pressure Vessel at a high speed, possibly piercing through the Containment Vessel, while telling the politicians a more "benign" core-concrete reaction scenario.

If HMT had happened in Reactor 2, as Dr. Madarame and Dr. Kukita feared, it may have been an immediate evacuation from the plant. The worst case that PM Kan says he received (but decided to sit on it for months and deny the existence of the report) may have come true then.

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#Fukushima I NPP: 2.2 Million Bq/L of All-Beta from Water Sample from an Observation Well Near the Plant Harbor

What's more significant than the number is Fukushima Minyu's interpretation that the contamination may be from the water in the trench(es) that contain extremely highly contaminated water from April/May 2011.

From Fukushima Minyu (1/11/2014):

海側井戸で220万ベクレル検出　第１原発、上昇傾向続く

2.2 million becquerels [per liter] detected from a well near the harbor at Fukushima I Nuclear Power Plant, upward trend continues

東京電力福島第１原発の海側にある観測用井戸の水から高濃度の放射性物質が検出されている問題で、東電は１０日、ストロンチウム９０などベータ線を出す放射性物質の濃度がさらに上昇し、過去最高値の１リットル当たり２２０万ベクレル検出したと発表した。

A large amount of radioactive materials have been detected from observation wells on the ocean side of Fukushima I Nuclear Power Plant. On January 10, TEPCO announced that the density of all-beta including strontium-90 had further increased and the latest measurement was 2.2 million becquerels per liter, the highest recorded so far.

井戸は２号機の東側にあり、海までの距離は約４０メートル。水は９日に採取した。昨年１２月３０日採取分の２１０万ベクレルを上回り、依然として上昇傾向が続いている。

The well is located on the east side of Reactor 2, about 40 meters from the plant harbor. The water sample was collected on January 9. The density was even higher than the sample taken on December 30, 2013 which had 2.1 million becquerels/liter.

この井戸の近くには、２０１１（平成２３）年３月の事故直後に極めて高い濃度の汚染水が漏れた電源ケーブル用の地下道（トレンチ）があり、汚染が地中で拡散しているとみられる。

The well is located near the underground trench for electrical cables where water with extremely high contamination was found leaking right after the March 2011 accident. It is likely that the contamination is spreading into the surrounding soil.

Jiji Tsushin reports the same news but it says "The cause of the high all-beta measurement is unknown."

The level of radioactive cesium in this water was ND (not detected).

How "extremely high" was the contamination of the water that was found leaking from the Reactor 2 turbine building via the trench into the harbor in April 2011?

From TEPCO's press release, 4/5/2011:

• Iodine-131: 5.2 billion Bq/Liter (or 5.2 million Bq/cm3)

• Cesium-134: 1.9 billion Bq/Liter (or 1.9 million Bq/cm3)

• Cesium-137: 1.9 billion Bq/Liter (or 1.9 million Bq/cm3)

The air dose rate measured above the water in April 2011 was over 1 Sievert/Hour (survey meter went overscale).

If this trench water is spreading in the soil, it makes sense that cesium is not detected from the water, as cesium has been bound to the soil.

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Video of Inside Reactor 2 Containment Vessel, 8/12/2013

I finally managed to download the video properly from TEPCO's Photos and Videos Library page.

For more about TEPCO's latest attempts to probe the Reactor 2 CV, see my posts, here and here.

By the way, I happened to watch a BBC news clip August 6, 2013 on Fukushima I Nuke Plant, and saw in amusement the snippet of the video inside the Reactor 2 Containment Vessel (the one I posted on my August 4, 2013 post). The snippet was used while the announcer was saying "It [groundwater]'s now so high the water will soon reach the surface. Then it will start flowing overground into the sea."

BBC seems to be trying to pass off the grating inside the Containment Vessel as a grating over some underground drain, about to be flowing overground...

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#Fukushima I Nuke Plant Reactor 2 Containment Vessel Probe: Camera Stopped Just Short of Pedestal Opening

So close. TEPCO posted a short report on August 12 with photos as if that was what had been planned all along - to stop right at the opening of the pedestal.

However, the worker who tweeted from Fukushima I Nuke Plant and now tweets from somewhere else, "Happy", said in his August 10 tweet that the probe was done on August 9, but TEPCO couldn't retrieve the camera and the water sample and had to abandon the probe.

I'm not sure the August 12 attempt was a third one (if "Happy" is correct), instead of second. But it's clear from TEPCO's report that they didn't collect the water, and they do not have the video.

On their initial attempt on August 2, 2013 and the video, see my post on August 4, 2013. TEPCO clearly intended, from the first attempt, to insert the camera inside the pedestal.

From TEPCO's Photos and Videos Library, 8/12/2013:

Temperature at (1) was 41 degrees Celsius, and temperature at (2) was 45 degrees Celsius, according to the same document. The radiation levels at those points are "under evaluation".

Click to enlarge the photos.

(1)

(2)

(3)

(4)

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#Fukushima I Nuke Plant: Latest Images and Video of Inside Reactor 2 Containment Vessel (8/2/2013)

There is a white brush sitting on top of the rail for the control rod driving mechanism...

(From TEPCO's video taken on 8/2/2013):

TEPCO has been trying to get better information inside the Reactor 2's Containment Vessel for some time, and have failed for one reason or another. This latest attempt was to reach inside the pedestal. The attempt failed again, when it simply took too long for the workers to manipulate the camera past the obstacles.

Workers threaded the CCD camera, dosimeter, and thermocouple through the penetration X53 in order to find out whether the CRD exchange rail has dropped or not, whether there is any obstacle on the rail, and whether there is anything dropped inside the pedestal (TEPCO's word in the handout on 8/2/2013).

The rail is there, and there are some items on the rail. TEPCO says they will try again in August 6 to reach inside the pedestal. They will also collect the water sample on August 5.

From TEPCO's Photos and Videos Library, 8/2/2013 (English labels are by me):

The condition of the rail reminded me of the guide rail for the Reactor 3 CV's equipment hatch - some blackish substance, though it could be just water in the dark.

Just like the first video of the inside of Reactor 2's Containment Vessel taken in January 2012, there are constant drops of water in the dark. And radiation:



If TEPCO is successful on August 6, we may get to see the corium for the first time.

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#Fukushima I Nuke Plant Groundwater Contamination: High Contamination Confirmed in Water in Shaft B Connected to Reactor 3 Turbine Building

But the level of contamination is less than water in Shaft C that connects to Reactor 2 turbine building.

TEPCO announced the results of nuclide analysis of the water sample taken from the Shaft B (see the diagram below, from TEPCO's 7/26/2013 document, with added English labels) at different water levels in the shaft.　Shaft B and the seawater intake pipe trench that connects to the shaft go to Reactor 3's turbine building.

In an effort perhaps to make the data more accessible to mere mortals, in addition to announcing the results in liter TEPCO also spelled out the numbers instead of using "x.xE+x" format. (I wish they just used Bq/cm3. Too many zeroes, and I couldn't grasp the numbers right away.)

From TEPCO's 8/1/2013 handout for the press in Japanese (English labels are by me):

Comparing Shaft B for Reactor 3 and Shaft C for Reactor 2, you will note:

• Chloride content is one order of magnitude bigger in Shaft B than in Shaft C.

• Cesium content is one order of magnitude smaller in Shaft B than in Shaft C.

• All-beta content is one order of magnitude smaller in Shaft B than in Shaft
  C.

Therefore, unlike the water in Shaft C and seawater pipe trench for Reactor 2, the water in Shaft B for Reactor 3 is not likely to be the highly contaminated water that leaked to the ocean in April 2011. Rather, the density is in the same order of magnitude as in the water that is currently in the Reactor 3 turbine building basement.

According to the most recent analyses of the contaminated water inside the turbine buildings,

Water in the Reactor 3 turbine building basement (as of 6/13/2013) has:

• Cs-134: 1.5E+04 Bq/cm3, or 15,000 Bq/cm3

• Cs-137: 3.1E+04 Bq/cm3, or 31,000 Bq/cm3

For reference, water in the Reactor 2 turbine building basement (as of 7/22/2013) has:

• Cs-134: 1.1E+04 Bq/cm3, or 11,000 Bq/cm3

• Cs-137: 2.5E+04 Bq/cm3, or 25,000 Bq/cm3

The numbers are comparable to water in the Reactor 3 turbine building basement but one order of magnitude smaller than the water sitting in the Shaft C and trenches connected to it.

Put the information yet another way for easier comparison, the numbers in Bq/cm3 instead of Bq/liter, except for chloride (click to enlarge):

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(UPDATED) Just In, from TEPCO's Tweet: High Levels of Strontium, Tritium in Groundwater Sampled Near Reactor 2 Turbine Building at #Fukushima I Nuke Plant

Notes from the press conference in my latest post.

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(UPDATE 4) It is per liter, confirms Kino. Phew. It is still very high for groundwater, supposedly not contaminated (at least not by much at all).

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(UPDATE 3) Jiji Tsushin says the unit is per liter, not per cubic centimeter.

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(UPDATE 2) Independent journalist Ryuichi Kino's tweet:

東電から会見メール。タービン建屋の海側の観測孔から高濃度の放射性物質が出たと。濃度はストロンチウムが１立方センチあたり１０の３乗。トリチウムが１０の５乗レベル。１０時から臨時会見。

— 木野龍逸 (Ryuichi KINO) (@kinoryuichi) June 19, 2013

Strontium at a level of 10^3 (in thousands) per cubic centimeter, tritium at a level of 10^5 (in hundred thousands) per cubic centimeter. (Update from Kino, it is per liter.)

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(UPDATE) "Higher than normal", says Jiji Tsushin.

=============================

Details to be discussed in the ad hoc press conference at 10AM, June 19, 2013 (Japan Standard Time).

TEPCO　Nuclear's tweet, about 30 minutes ago:

■お知らせ■本日（6/19）午前10時から本店本館3階において会見を開催し、２号機タービン建屋東側の観測孔でトリチウムおよびストロンチウムが高い値で検出されたことをご説明させていただきます。臨時会見はライブ配信でご覧いただけます。http://t.co/icHWTJJncR

— 東京電力　（原子力） (@TEPCO_Nuclear) June 18, 2013

We will hold a press conference at 10AM today (June 19) on the third floor of our headquarters building [in Tokyo] to explain about high levels of tritium and strontium [from the groundwater sampled] from one of the observation holes on the east side of Reactor 2 turbine building. This ad hoc press conference can be viewed via live stream.

TEPCO's live stream video page is here: http://www.tepco.co.jp/tepconews/streaming/index-j.html

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#Fukushima I Nuke Plant: Two Very Dead Rats in the Transformer Box for Reactor 2 SFP Cooling System

(UPDATE 4/22/2013) It took workers 4 hours to remove the rats and make sure the transformer was OK. Cooling of Reactor 2 SFP resumed. The water temperature rose 0.1 degrees Celsius to 14 degrees Celsius during the halt.

======================================

They were discovered by a team of workers patrolling the premise. One of the rats, the gray one in the photo below, looks like he's been there quite a while.

From TEPCO's Photos and Videos Library, 4/22/2013:

The box that these rats were found is that small box on the ground on the left-hand side of the photo below:

Cooling of Reactor 2's Spent Fuel Pool was halted as of 11:36AM to remove the rats and make sure the transformer was not damaged. The temperature of the water in the SFP was 13.9 degrees Celsius. TEPCO estimates a few hours for the work of removing the rats and ensure safety of the transformer.

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Stating the Obvious: #Fukushima Reactor 2's Suppression Chamber May Be Leaking

TEPCO may have hoped that it was one of those vent pipes from the dry well to the suppression chamber in Reactor 2 that was leaking the water injected into the RPV, but the awkward 4-legged Robot by Toshiba couldn't find any leak. So the conclusion is that the suppression chamber is probably leaking.

I would think it will be much harder (near impossible) to plug, because the suppression chamber is submerged in highly contaminated water.

From Jiji Tsushin (3/15/2013; part):

圧力抑制室から漏水か＝福島第１原発２号機－東電

TEPCO says leak may be from the Reactor 2 suppression chamber

東京電力は１５日、福島第１原発２号機格納容器下部の圧力抑制室につながる「ベント管」を調べた結果、水漏れはなかったと発表した。原子炉建屋地下に漏れ出している水は、圧力抑制室から出ている可能性が高くなったという。

TEPCO announced on March 15 that there was no leak after examining the "vent pipes" that connect to the suppression chamber of Reactor 2 containment vessel at Fukushima I Nuclear Power Plant. The water leaked into the basement of the reactor building was likely to be coming from the suppression chamber.

In that press conference on March 15, TEPCO's spokesman (no longer Mr. Matsumoto, I don't know the name of this young person who croaks when he speaks) didn't explicitly admit that the leak was from the suppression chamber; instead, he said, in response to a question by the reporter from Tokyo Shinbun on how TEPCO felt about the discovery (after 27 minutes):

Since the leak is not from the PCV (primary containment vessel), it will be easier to plug the leak.

How could a repair job in an inaccessible part of the suppression chamber (lower half) be easier?

His reasoning was that the PCV was closer to higher contamination, so any repair work away from the PCV would be easier. He tried to spin it as a positive discovery. "The PCV is sound, and it's a good thing", he said. The only problem was how to find the leak in the lower half (submerged part) of the suppression chamber, or other locations, he said.

It didn't seem like an answer to me, but as usual, the reporter said "OK, I got it", and that was the end of his questions.

(I miss the previous spokesman Matsumoto, who looked like Doraemon. He didn't try to spin, like the current one does.)

One of the photos taken by Toshiba's robot, released on March 15, 2013. Lots of white noise (click to enlarge):

The radiation levels inside the Reactor 2 torus room is not known. TEPCO couldn't lower the camera and dosimeter through the hole drilled on the 1st floor when they found out there were unexpected pipes blocking the way.

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#Fukushima I Nuke Plant: Gamma-Ray Camera Image of Reactor 2 Operating Floor

As the new LDP administration under Shinzo Abe is very eager to be done with the Fukushima nuclear accident by urging TEPCO to do the decommissioning work way ahead of schedule (which is not feasible even its current form), TEPCO dutifully follows the government prompting (which is tantamount to an order without saying it is an order).

The effort to do things ahead of schedule, or to catch up on the behind-schedule work, has already resulted in dropping a fuel transfer machine part into the Spent Fuel Pool in Reactor 3 as the workers carried out the work in heavy snow.

Now, TEPCO just did the gamma-ray imaging of the Reactor 2 operating floor. Although the Reactor 2 building looks intact except for the open blowout panel, the radiation levels on the operating floor is just too high for the carbon-based or silicon-based workers. The lowest level is 40 millisieverts/hour, the highest 880 millisieverts/hour right above the reactor well, as mapped by the robot Quince No.2 in June last year.

What TEPCO did therefore was to build a platform on top of the turbine building to the height of the blowout panel, and lifted up the gamma camera onto the platform using a crane.

TEPCO says the analysis will take about a month.

From TEPCO's Photos and Videos Library, 2/22/2013:

According to the handout that accompanies the photo, TEPCO plans to "decontaminate" the floor whose air radiation doses are as high as 880 millisieverts/hour in order to remove fuel assemblies from the Spent Fuel Pool in the "future".

At a much lower air dose level of about 10 millisieverts/hour, Quince No.1 robot has been stranded on the 3rd floor of Reactor 2 since October 2011.

I have no idea how "decontamination" is possible.

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#Fukushima I Nuke Plant: Pipes That Should Not Be There Are Blocking the Way in Reactor 2 Torus Room

TEPCO send the workers to Reactor 2 building on January 27 to drill a hole through the 1st floor to the torus room. The location was carefully chosen so that they would have a clear shot at the water accumulated in the torus room. Through the hole, the workers were to feed the camera, dosimeter, and thermometer.

Surprise! When the workers managed to carefully drill a hole and looked in, huge pipes and gratings were in the way, and there was no way for the workers to do the planned work at that hole.

From TEPCO's Photos and Videos, 1/28/2013, "Drilling Holes for the Investigation of Unit 2 Torus Room at Fukushima Daiichi Nuclear Power Station":

From the handout, this was what TEPCO had planned:

How did this happen? TEPCO chose the location because there wasn't supposed to be anything, according to the original drawings. However, as repairs and renovations were done over the years, the original drawings from the time the reactor was built became obsolete.

Don't they have the drawings of those repairs and renovations? Yes they do. But those drawings were stored in one of the buildings that was devastated by the March 11, 2011 earthquake and declared too dangerous to enter. There is no information as to whether anyone has gone back in to retrieve any document or data from the main building. Probably not, because, as we know well by now, TEPCO carefully abides by the rules and regulations from the authorities:

(Photo of the 2nd floor of the main building, Fukushima I Nuke Plant)

Independent journalist Ryuichi Kino tweeted:

福島第一の現況の把握が難しいことは、以前からわかっていた。原子炉の基本的な構造は設計当初のままだが、配管や細かい設備などは後から追加、修正をうけて、元の状況とは大きく変わっている。だからこれまでも、構造物に手を着ける作業は慎重に進められた。

It has been known that it is difficult to completely grasp the condition of Fukushima I Nuke Plant. The basic structures of reactors have been the same since the plans were drawn up, but pipes and other small facilities were added and modified later, making the current condition vastly different from the original condition. Therefore, any work that has to do with the structures have been carried out very carefully.

もうひとついうと、改修で配管が変更されていたため、窒素封入や冷却水の注入に使う配管の確認に手間取ってもいた。旧保安院もそうした経緯は知っていて、簡単ではないことも認識していた。では現況が把握できる図面はどこにあるのかと、保安院で聞いたことがある。

One such example: TEPCO had a difficult time in confirming which pipe to use for nitrogen gas injection and for cooling water injection, because the pipes had been switched around after repairs and renovations. Nuclear and Industrial Safety Agency knew this, and was aware that it was not easy. I once asked NISA, where, then, are the drawings that will allow us to grasp the current condition?

すると、図面や工事の書類などはすべて、福島第一の事務本館にあるという。だから、取りにいけないのだとのことだった。事務本館は地震でボロボロになって、立ち入り禁止になった。

They answered, all the drawings and documents from construction work are stored in the main building at Fukushima I Nuke Plant, and therefore they couldn't go in and retrieve them. The main building was devastated by the earthquake, and declared off-limits.

ということを聞いたのは、１年くらい前だったか。そういえばその後、事務本館に書類の回収に行ったのかどうか聞いてなかったので要再確認。とはいえ、今回の作業で予想外の配管が、何もないはずの場所の真ん中に通っていたことで、疑問が倍増してしまった。

That was about one year ago. I have to ask again if someone did go to the main building to retrieve the documents. However, the most recent work [drilling a hole through the floor of Reactor 2] revealed unexpected pipes right there in the middle of where they were not supposed to be. So I wonder.

現況の把握ができないと、実際に見えている範囲の作業を進めるのが精一杯になる。そうなると２号機トーラス室だけでなく、人が入れない場所の作業に大きく影響する。ロボットで作業するといっても、指示ができない。手探りの事故収束作業が、まだまだ続いている。

If they cannot grasp the current condition, the best they can do is to do the work in the areas that they are able to see. That wold affect the work not just in Reactor 2 torus room but everywhere where human workers cannot enter. Robots may be able to enter, but [since no one knows the actual condition of the place] no one can give directions to the robots. It is as if they feel their way in the dark, as they continue the work to end the accident.

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Update from TEPCO's Press Conference on Toshiba's 4-Legged Robot That Crashed in #Fukushima I Nuke Plant Reactor 2 Torus Room

It's so pathetic it is almost funny. Or at least the dialog between the reporters and TEPCO during the December 12, 2012 press conference was, probably unintentionally.

It was funnier reading about it via the tweets by @ystricera, who has tweeted almost all press conferences by TEPCO and the government regulatory agencies since March 2011.

Reporter: What time did the robot stop?
TEPCO: In the morning.
Reporter: It's evening now, and you don't know the exact time?
TEPCO: We will investigate all day tomorrow.

Two human colleagues from Toshiba had to get exposed to 1.36 millisievert radiation to retrieve the robot, but just to the outside the torus room.

For more of the mission of this clumsy Toshiba robot, see my previous post.

From his tweets on December 12, 2012, the remarks in parenthesis are either his explanation or the reporters' questions:

（2号機4本足ロボット調査、もともと1階北東側三角コーナーから親機入れて階段を降りてから）東電「階段をまず降りて地下のところまでいってトーラス室に行くのに登り階段がある、そこから登る操作していた所足をかけて上に上がろうとしていた所前足が浮いて後ろに倒れる形に　」

(Investigation of Reactor 2 by the 4-legged robot, it was to enter from the northeast corner on the first floor and climb down the stairs, then..?) TEPCO "The robot first climbed down the stairs to go to the basement, then there are stairs to climb up to the torus room. The robot started to climb. Then the forelegs went up in the air and the robot fell backward."

東電「遠隔段階、動作不能になったので2人いって回収。結果的には倒れているので想定していない不具合があったのかと思うが、状況としては前足を前にかけていて後ろ足をあげる段階で後ろ倒しになったと、バランス崩す制御になったと」

TEPCO "The robot was on a remote control. Two people went to retrieve the unresponsive robot. Since it fell down, we assume there were some unexpected problems. But the situation was that the forelegs were on the step already, and the robot was lifting the hind leg, then lost control and fell backwards."

東電「動作開始の直後。登り始めるところからスタートで登りはじめたらすぐ。」

TEPCO "It was right after the robot started to climb."

東電「2号機ベント管調査の件、キャットウォークに登る階段を登りはじめた所で厳密に言うとトーラス室に入ったところ」（人がいって回収したのは間違いないか）「2人いって回収、入り口なのでそんなに大きいわけではなく実際の被曝量は多い方の方で1.36mSv」

TEPCO "The robot was just starting to climb the stairs leading to the catwalk. So to be precise, it was right inside the torus room." (So human workers went to retrieve it, is that correct?) "Two people went to retrieve the robot. Because the location was right at the entrance, the radiation level was not that high. The max exposure was 1.36 millisievert."

（共同池上　調査前にひっくり返った）東電「開始直後ですので調査はできていない」（明日は調査しない、終わり時期がよくわからないがいつくらいまでやる予定）「1日1本、2本、状況に応じてだが全部で8本あるのでそういうオーダーでできると作業継続」

(Ikegami of Kyodo News: So the robot flipped over before the investigation.) TEPCO "It happened right at the beginning of the work, so no, there was no investigation done." (So you're not going to do the investigation tomorrow? When will the investigation be over?) "One or two vent pipes a day, so depending on the situation, there are 8 vent pipes, we hope to carry out the investigation at that pace."

（回収は東電社員）「協力企業」（東芝の人）「そうだと思います」

(Did TEPCO employees retrieve the robot?) "Affiliate company." (Were they from Toshiba?) "I think so." [TEPCO doesn't even know that??]

（壊れた部分は）東電「倒れかかったということで、そんなに大きく壊れてないと。後ろの壁にもたれかかった。回収は手で運び出した」（建屋の外まで）「トーラス室の外の三角コーナーまで」（ロボット自体は今どこに）「三角コーナーに」

(What broke?) TEPCO "The robot didn't completely fall down, so we don't think it's damaged much. It was leaning against the wall behind it. Workers hand-carried it." (To outside the reactor building?) "To the landing just outside the torus room." (Where is the robot now?) "On the landing."

（仮置きしたのはおもいっちゅうのもあると思うが）東電「そこでバッテリーチャージもできますし」

(I suppose it is because the robot was so heavy that the workers had to leave it there for now.) TEPCO "Well, we can charge batteries there."

（ロボット三角コーナーに仮置きというお話されたが故障原因わからずにその場に仮置きだと修理しようがないが外に持ちだして確認したりは）東電「どういう調査するか含めて確認中」

(So the robot is temporarily placed on the landing, you say. But if you have it there temporarily without knowing the cause of the problem, there is no way to repair it. Are you going to take it outside [the reactor building] and inspect?) TEPCO "We're trying to figure out what to do."

（止まったのは何時）東電「朝」（夕方になってもわからないと）東電「明日1日調査する」

(What time did it stop?) TEPCO "In the morning." (It's evening now, and you don't know the exact time?) TEPCO: "We will investigate tomorrow all day."

AAAAGGGGHHHH....

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(UPDATED) #Fukushima I Nuke Plant: Toshiba's 4-Legged Robot Checked Vent Pipe in Reactor 2, No Leak, Damage Observed

(UPDATE) I just had a laugh for the night. In TEPCO's press conference on December 12, TEPCO has just said this robot has crashed. TEPCO was going to check one or two more vent pipes on December 12, but the robot lost its balance and collapsed on the staircase to the torus room and cannot move. TEPCO will investigate the cause of this malfunction tomorrow.

In the demonstration in Yokohama in November, humans had to carry the robot off the stairs when it froze. I suppose Toshiba workers will have to retrieve the robot from the torus room, braving the high radiation.

It was very stupid to send the clumsy robot like this on a task similar to the one that had caused it to freeze in the demonstration. TEPCO that cannot say no (or doesn't say no).

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In the video released by TEPCO on December 11, the Toshiba robot who froze with one leg up in the air during the demonstration in November in Yokohama takes time to put one leg forward and then another. It takes about 25 seconds for it to lift the left hind leg and put it on the next step.

I feel sorry for TEPCO for having to accept a dud like this.

The video title is "Investigation on the lower part of Unit 2 vent pipe at Fukushima Daiichi Nuclear Power Station (Mockup test)", indicating TEPCO is going to use this thing in Reactor 2.

(Video is being uploaded right now.)

And it did. TEPCO just released the photos of the vent pipe that was examined by the robot on December 11. There is no discernible leak or damage to this particular pipe.

From TEPCO's handout for the press, "Results of Investigation on the Lower Part of Unit 2 Vent Pipe at Fukushima Daiichi Nuclear Power Station" (12/11/2012), page 2 (click to enlarge):

No information on how long it took this robot to do the work. Page 3 says actual radiation dose was 1.75 millisievert, but no information whether that was for the robot or the robot operator(s).

Edge of vent pipe sleeve:

Edge of sand cushion drain pipe:

Lower part of vent pipe bellows cover:

On March 15, 2011, a loud sound was heard from the Reactor 2 torus room, and Reactor 2 is supposed to have released radioactive material an order of magnitude larger than the other reactors.

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#Fukushima I Nuke Plant: TEPCO Managed to Insert a New Thermocouple to Monitor Reactor 2 RPV

There was only one thermocouple left at the bottom of the Pressure Vessel of Reactor 2. Now there are two, greatly enhancing the TEPCO's capability to monitor the "cold shutdown state".

Workers from TEPCO and an affiliate company (most likely Toshiba, who's in charge of probing inside the Containment Vessels of Reactors 2 and 3) finally managed to insert a replacement thermocouple through one of the penetrations on the Containment Vessel of Reactor 2 to 5 centimeters inside the wall of the Reactor Pressure Vessel (RPV).

Of the six thermocouples that monitor the temperature at the bottom of RPV, 5 of them had failed since the start of the accident.

From TEPCO's Photos and Videos (10/3/2012):

It's been a while since TEPCO last announced the details on workers - how many of them, how many teams of workers, what company they belong to, and how much radiation exposure they got from performing the task. This particular work took 2.5 hours, according to TEPCO's handout for the press (in Japanese) of the same day.

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