Sunday, August 31, 2014

#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.)

Saturday, August 23, 2014

Three and a Half Years After the #Fukushima Nuclear Accident, Nature Slowly Taking Over Deserted Futaba-Machi

Futaba-machi is located just outside Fukushima I Nuclear Power Plant. Almost entire town is designated as "areas difficult for the residents to return" ("within 5 years", according to the national government's euphemism - oh wait, solid plan?) because of the high levels of radioactive contamination from the nuclear accident. Part of Futaba-machi was exposed to radiation levels as high as 1,590 microsieverts/hour on March 12, 2011, before the hydrogen explosion of Reactor 1.

Even though over 3,000 workers continue to work on any given day at the plant right outside the town, Futaba-machi is deserted, and the mother nature is slowly taking over.

Photographs of Futaba-machi taken in front of the arch at the town entrance that says "Nuclear Energy Is the Energy for the Bright Future":

April 25, 2011, from Asahi Shinbun. The street still looked neat and clean, as if nothing had happened.

July 2012, from the blog of Mineyuki Fukuda, LDP politician from Kanagawa:

About the same time period as the photo above, this photo was taken with a man holding the sign "Destruction" over the word "Bright" in "Bright Future" on the arch. It was his slogan he created when he was in the 6th grade:

July 2013, from Google Street View:

A differen part of Futaba-machi in July 2012, from Collabo Corp OB blog. The words on the arch says "Nuclear Energy Creates Rich Society and Rich Town":

The same arch, in 2014, from the 8/20/2014 tweet by @akauntok:

Railroad, from Google Street View (as of July 2013):

Tuesday, August 12, 2014

#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):


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


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.


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).

Saturday, August 9, 2014

(OT) Japanese Prime Minister Copies and Pastes Speech for Hiroshima AND Nagasaki Memorial Ceremonies for Atomic Bomb Victims

Somehow quite fitting for Mr. Shinzo Abe, who, along with his Minister of Education and Science, remains staunch supporter of Ms. Haruko Obokata, who copied and pasted and photoshopped her way to a very brief scientific fame (turned infamy) as a "Nature" author on STAP cells.

Unlike Ms. Obokata, who copied and pasted other people's work (among many other misconducts) without citation, Prime Minister Abe claims his is no misconduct, because the speeches he lifted for this year's ceremonies were his own speeches for the same occasions last year.

Tokyo Shinbun (8/8/2014) says the opening few paragraphs of Mr. Abe's speech in Hiroshima on August 6, 2014 were almost identical to his speech in 2013.

2013 speech on the left, 2014 speech on the right. Only the parts highlighted in blue are different:

It apparently got better (I know I should say "worse") in Nagasaki. Mr. Abe's speech on August 9, 2014 was identical except for the number of years since the atomic bomb was dropped in Nagasaki:

The Prime Minister's Office has the temerity to say this after the Hiroshima ceremony, according to Kyodo News (via Nikkan Sports):


Prime Minister's speech is to mourn for the victims and to express his determination to do his utmost for peace. This attitude is the same as the last year.


Praying for peace and mourning [for the victims] are shared by the government, atomic bomb victims and their families, and local residents. The part [that expresses such feeling] ends up being similar, no matter what.

Similar? How about "identical"?

I was amused by the reaction in Japan on Twitter, where people were rightfully angry and upset that the prime minister didn't bother to change this year's speech from the last year's, and that it was such an insult to the victims, Japanese citizens, and foreign dignitaries who attended the ceremonies. Many of them seem to think a prime minister, or any politician, is supposed to write his/her own speech, and that the more world-class he/she is the better speech he/she writes and gives.

'Tatemae' hurts.

To me, the ultimate insult is that the Japanese government hasn't owned up to its own culpability for the two atomic bombs dropped in Japan in August 1945, as 2011 NHK Special revealed, and that most Japanese refuse to face the possibility that their government was fully aware that those planes were carrying atomic bombs but let the bombing happen anyway, if the NHK documentary is correct. (For those who wants to know more about the NHK documentary, see my posts from last year, here and here.)

Meanwhile, Mr. Abe's comrade in copying and pasting, Ms. Obokata, is still with Riken drawing nice salary no doubt while she gets ready for delicate lab work and preparing tea, thanks to the strong pressure Mr. Abe and his Education Minister exerted on Riken, a research institution funded by public money, not to fire her.

Thursday, August 7, 2014

(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.)


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):


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.


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.