Fuel debris possibly found in Fukushima Daiichi’s Reactor 3

Images show possible fuel debris

Engineers at the Fukushima Daiichi nuclear power plant are working to scrap the facility’s damaged reactors. For the first time, they’ve found what’s likely to be fuel debris in one of them.

The engineers have been trying to locate molten fuel in the No.3 reactor. The fuel is thought to have melted and fallen to the bottom of the containment vessel.

They lowered a submersible robot into the 6-meter-deep cooling water in the vessel. The image sent back by the robot shows an orange substance on a device that operates the fuel control rods. Objects shaped like icicles are also visible.

The engineers plan to use the robot to look for fuel debris at the bottom of the containment vessel.

Removing the molten fuel from the reactors is the biggest hurdle to decommissioning them.

https://www3.nhk.or.jp/nhkworld/en/news/20170722_04/

 
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TEPCO surveys bottom of reactor containment vessel

The operator of the Fukushima Daiichi nuclear power plant has carried out another robotic survey in one of the damaged reactors. The probe is meant to confirm the existence and status of fuel debris consisting of molten fuel and reactor parts.

Officials of Tokyo Electric Power Company, or TEPCO, say the probe took place at the bottom of the containment vessel in the No.3 reactor on Saturday. The vessel’s bottom is thought to hold much fuel debris.

TEPCO used a robot designed to move through cooling water in the vessel.

The survey follows Friday’s release of photographs taken during the previous underwater robotic probe of the same vessel. The robot did not reach the vessel’s bottom during the first probe.

The images show rock-like lumps located near walls of a reactor-supporting structure and various other parts of the vessel.

TEPCO officials say it is very likely the lumps are fuel debris created after nuclear fuel in the reactor melted, mixed with reactor parts, and fell. If confirmed, this would be the first time fuel debris has been found in the No.3 reactor.

Robotic probes have so far failed to provide clear evidence showing the existence and status of fuel debris in other 2 damaged reactors.

Removing the fuel debris is one of the major hurdles to decommissioning the reactors which continues to emit extremely high levels of radiation.

https://www3.nhk.or.jp/nhkworld/en/news/20170722_22/

“Possible” melted fuel seen for first time at Fukushima plant

“Possible” – “apparently” – “what is believed to be” – “suggesting” …
A lot of qualifiers here, and obligatory glee for our cute ‘little sunfish’, but they got one thing absolutely right in this report: they didn’t call it a ‘crippled plant’, it’s now officially the “destroyed plant”; and the most important fact or folly is buried towards the end: “to remove the melted fuel, a process expected to begin sometime after the 2020 Tokyo Olympics…
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TOKYO — An underwater robot captured images of solidified lava-like rocks Friday inside a damaged reactor at Japan’s crippled Fukushima nuclear plant, spotting for the first time what is believed to be nuclear fuel that melted six years ago.
Plant operator Tokyo Electric Power Co. said the robot found large amounts of lava-like debris apparently containing fuel that had flowed out of the core into the primary containment vessel of the Unit 3 reactor at Fukushima. The plant was destroyed by a massive earthquake and tsunami in March 2011.
Cameras mounted on the robot showed extensive damage caused by the core meltdown, with fuel debris mixed with broken reactor parts, suggesting the difficult challenges ahead in the decades-long decommissioning of the destroyed plant.
Experts have said the fuel melted and much of it fell to the chamber’s bottom and is now covered by radioactive water as deep as 6 meters (20 feet). The fuel, during meltdown, also likely melted its casing and other metal structures inside the reactor, forming rocks as it cooled.
TEPCO spokesman Takahiro Kimoto said it was the first time a robot camera has captured what is believed to be the melted fuel.
“That debris has apparently fallen from somewhere higher above. We believe it is highly likely to be melted fuel or something mixed with it,” Kimoto said. He said it would take time to analyze which portions of the rocks were fuel.
In an earlier survey Wednesday, the robot found severe damage in the vessel, including key structures that were broken and knocked out of place.
The robot, nicknamed “the Little Sunfish,” on Friday went inside a structure called the pedestal for a closer look. TEPCO plans to send the robot farther down on Saturday in hopes of finding more melted fuel and debris.
Experts have said the melted fuel is most likely to have landed inside the pedestal after breaching the core.
Kimoto said the robot probe in its two missions has captured a great deal of useful information and images showing the damage inside the reactor, which will help experts eventually determine a way to remove the melted fuel, a process expected to begin sometime after the 2020 Tokyo Olympics.
“It’s still just the beginning of the (decades-long) decommissioning. There is still a long way to go, including developing the necessary technology,” he said. “But it’s a big step forward.”
Locating and analyzing the fuel debris and damage in each of the three wrecked reactors is crucial for decommissioning the plant. The search for melted fuel in the two other reactors has so far been unsuccessful because of damage and extremely high radiation levels.
The submersible robot, about the size of a loaf of bread, is equipped with lights, maneuvers with five propellers and collects data with two cameras and a dosimeter. It is controlled remotely by a group of four operators. It was co-developed by Toshiba Corp., the electronics, nuclear and energy company charged with helping clean up the plant, and the International Research Institute for Nuclear Decommissioning, a government-funded consortium.
The material has smooth thick edges making it unlikely to be rust, though there are considerable areas of rust inside containment. This material also does not match any known material from previous reactor meltdowns or melted fuel (corium) research. TEPCO makes no specific mention of this substance.
Evident inside the pedestal area is a pale colored thick substance that has adhered to solid surfaces. This same material is seen throughout the area of the containment structure inspected with a scope earlier. Now this same material is found inside the pedestal area.
Special credits to Fukushima Response Campaign & Fukuleaks

 Radioactive cesium detected in the urine of 100 children after the catastrophic accident of TEPCO Fukushima Daiichi nuclear power plant

 Cesium concentration found in more than 70% of the urine samples tested in Fukushima Prefecture

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Amounts of radioactive cesium, Cs-137 and Cs-134, in 24 h urine of 37 children have been determined using a HP-Ge detector, in Fukushima Prefecture between February 2014 and March 2016.

As comparisons, those of 25 children have been also measured who live in Western Japan from September 2016 to March 2017, and that of one child in Ibaraki Prefecture from April 2014 to January 2017.

We have found the cesium concentrations in the more than 70 % of urine samples from Fukushima Prefecture are in the ranges from 0.06 to 0.30 Bq/L.

No radioactive cesium is observed in the samples from Western Japan, under the detection limit of 0.1 Bq/L.

In the case of Ibaraki, the radioactivity keeps its value around 0.20 Bq/L during the inspection period, indicating the chronic ingestion of the radioactive cesium in his daily life.

http://www.lib.kobe-u.ac.jp/handle_kernel/81009860

javascript:PdfLink(‘default’,’81009860′,’http://www.lib.kobe-u.ac.jp/repository/81009860.pdf’,’G0000003kernel’)

Tepco chairman’s remark on water release goes radioactive

Comment draws ire from Fukushima residents, fishermen and watchdog

0721N_TEPCO_article_main_imageTakashi Kawamura, a former Hitachi chairman, took up his current post just last month.

 

TOKYO — Comments by Tokyo Electric Power Co. Holdings’ chairman about releasing nuclear wastewater into the ocean are being met with anger from fisheries groups and many others.

Tepco Chairman Takashi Kawamura told news outlets earlier this month that the utility “has made its decision” on the release of tritiated water from the crippled Fukushima Daiichi power plant to the ocean. Tritiated water is a radioactive form where the usual “light” hydrogen atoms are replaced with tritium.

Kyodo News reported the following day that the company shares the view of Shunichi Tanaka, chairman of the Nuclear Regulation Authority, that spilling the water into the sea would not cause any problem, scientifically speaking.

Tepco immediately released a statement saying Kawamura’s comments “did not intend to announce the concluded policy of the company on the matter.”

Nonetheless, the national cooperative of fishermen has protested. And rather unexpectedly, Tanaka criticized Kawamura for using his name to promote the company’s agenda. This is a worrying development for Tepco, since increased mistrust by the NRA could affect the utility’s medium- to long-term strategies, including restarting nuclear power plants.

Tritiated water is also released from normally functioning nuclear power plants. In Japan, water meeting official standards can be dumped into the sea.

But local residents have protested the idea, out of concern that rumors and misunderstandings could damage their community. At the Industry Ministry, a special committee has been considering the matter. Kawamura’s remarks were seen as getting ahead of that process, hence the backlash.

The wastewater in question still sits inside a number of storage tanks at the Fukushima power plant, with nowhere to go. Tepco and the government want to find a solution quickly, but the latest controversy shows that skipping careful and thoughtful communication with various stakeholders could end up costing them more time.

http://asia.nikkei.com/Business/Companies/Tepco-chairman-s-remark-on-water-release-goes-radioactive

Potential releases of 129I, 236U and Pu isotopes from the Fukushima Dai-ichi nuclear power plants to the ocean during 2013 to 2015

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After the Fukushima Dai-ichi Nuclear accident, many efforts were put into the determination of the presence of 137Cs, 134Cs, 131I and other gamma-emitting radionuclides in the ocean, but minor work was done regarding the monitoring of less volatile radionuclides, pure beta-ray emitters or simply radionuclides with very long half-lives.

In this study we document the temporal evolution of 129I, 236U and Pu isotopes (239Pu and 240Pu) in seawater sampled during four different cruises performed 2, 3 and 4 years after the accident, and compare the results to 137Cs collected at the same stations and depths.

Our results show that concentrations of 129I are systematically above the nuclear weapon test levels at stations located close to the FDNPP, with a maximum value of 790 x107 at·kg-1, that exceeds all previously reported 129I concentrations in the Pacific Ocean.

Yet, the total amount of 129I released after the accident in the time 2011-2015 was calculated from the 129I/137Cs ratio of the ongoing 137Cs releases and estimated to be about 100 g (which adds to the 1 kg released during the accident in 2011).

No clear evidence of Fukushima-derived 236U and Pu-isotopes has been found in this study, although further monitoring is encouraged to elucidate the origin of the highest 240Pu/239Pu atom ratio of 0.293±0.028 we found close to FDNPP.

http://pubs.acs.org/doi/abs/10.1021/acs.est.7b03057

New TEPCO executives tripping over their tongues

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TEPCO Chairman Takashi Kawamura, right, receives a formal letter of complaint from an executive member of JF Zengyoren, a nation-wide federation of fishery associations, over his comment about dumping contaminated water to the sea on July 19 in Tokyo’s Chiyoda Ward.
Hoping to restore trust in embattled Tokyo Electric Power Co., the company’s new chairman and president have instead generated unwanted criticism and hostility in their first gaffe-filled month on the job.
They have added to the problems facing the operator of the crippled Fukushima No. 1 nuclear power plant, which also is hoping to bring its idled reactors back online.
On July 19, TEPCO Chairman Takashi Kawamura, who is also honorary chairman of Hitachi Ltd., was apologizing at the headquarters of JF Zengyoren, a nationwide federation of fishery associations, in Tokyo’s Chiyoda Ward. He was forced to explain “the true intention” of remarks he made last week regarding the release of diluted radiation-contaminated water into the sea.
On July 12, during a collective media interview session, Kawamura said “the decision has been made” to do so.
On the Fukushima plant premises, nearly 780,000 tons of water used to cool the reactors are stored, which had been decontaminated of radioactive cesium and plutonium but not tritium. Legally, the tritium-tainted water can be released into the sea, if diluted enough so the concentration of tritium is below a set standard.
However, as the release would add further adversity to the struggling fishing industry in Fukushima and neighboring prefectures, the central government has not made any clear decision on what to do with it.
Kawamura, however, also said, “I am on the same line as the opinion of chair Shunichi Tanaka (of Japan’s Nuclear Regulation Authority) that it is scientifically safe (to discharge water into the sea).”
On July 14, disaster reconstruction minister Masayoshi Yoshino expressed concerns that releasing the water now would “definitely affect public sentiment” over catches from Fukushima Prefecture, where full-scale fishing had been stalled.
At the July 19 meeting with the fishery federation, Kawamura retracted his comment, saying, “As a company or personally, no decision has ever been made whether to release contaminated water to the sea. The true intention of my comments were not properly understood by some media agency.” The TEPCO chairman apologized to Hiroshi Kishi, chairman of the federation, and others at the meeting.
Kishi, in return, submitted a letter of protest stating that they “strongly demand not to release radiation-contaminated water to the sea” and it is “unacceptable to the fishery industry and other Japanese people.”
On the same day, Kawamura admitted to the media what he said a week earlier, explaining that he meant “it cannot be independently decided by TEPCO.”
On July 19, in another part of Tokyo, NRA Chairman Tanaka told the media at a regular news conference that he is “boiling with anger” with Kawamura for including him in his comment. He also said Kawamura’s remark symbolizes his reluctance to face Fukushima residents.
“He used me as an excuse,” said Tanaka, who has suggested releasing water before the storage of contaminated water on the site reaches full capacity. “I have told him he needs to confront Fukushima issues as the first party to resolve them even if he faces a backlash. Despite that, he is still looking for an escape.”
On July 10, Kawamura and TEPCO President Tomoaki Kobayakawa attended a meeting with NRA members, including Tanaka, in Tokyo.
There, Kawamura said, “TEPCO has a responsibility to show that it can operate a nuclear power plant,” and he was warned by an NRA member for being “overly forward-looking.” Currently, none of TEPCO’s nuclear power plants are on-line.
On June 27, Kobayakawa also landed in hot water after referring to the town of Futaba, which co-hosts the Fukushima No. 1 nuclear plant, as “where the evacuation order is partially lifted” in a comment to a group of reporters. However, the town has been in a “difficult-to-return zone” since the accident, and no residents are allowed to return to their homes.
At a regular news conference on July 18, a disgruntled Fukushima Governor Masao Uchibori said, “I would like TEPCO to fulfill its responsibility as the operator that caused a severe accident.”