New proposal suggests removing Fukushima plant’s melted nuclear fuel from side — The Mainichi

” A method to remove melted nuclear fuel debris on the bottom of the containment vessels of Fukushima No. 1 Nuclear Power Plant’s first, second and third reactors from the side was proposed by the Nuclear Damage Compensation and Decommissioning Facilitation Corporation (NDF) on July 31.

Hajimu Yamana, head of the NDF, which is tasked with considering how to remove fuel debris from the reactors, for the first time explained the organization’s specific method proposal to the heads of local governments at a countermeasures for the decommissioning and handling of the contaminated water council meeting held in Iwaki, Fukushima Prefecture.

The method would focus on prioritizing the removal of debris from the bottom of the vessels from the side, using robotic arms and other remote devices while flushing water over the debris. However, ways to block radiation and countermeasures against the scattering of airborne radioactive dust still remain unsolved. The central government and Tokyo Electric Power Co. (TEPCO) plan to finalize their policy to remove the debris and amend the decommission schedule in September.

In all three of the reactors, contaminated water has collected at the bottom of the containment vessels. The NDF had previously considered a “flooding method” that would fill the containment vessels completely with water to block radiation from leaking. However, measures to repair the containment vessels and prevent leakage of the radioactive water would be difficult, so the plan was put aside for having “too many issues.” “

by The Mainichi

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Fukushima cleanup chief urges better use of probe robot — The Seattle Times

” TOKYO (AP) — The head of decommissioning for the damaged Fukushima nuclear plant said Thursday that more creativity is needed in developing robots to locate and assess the condition of melted fuel rods.

A robot sent inside the Unit 2 containment vessel last month could not reach as close to the core area as was hoped for because it was blocked by deposits, believed to be a mixture of melted fuel and broken pieces of structures inside. Naohiro Masuda, president of Fukushima Dai-ichi Decommissioning, said he wants another probe sent in before deciding on methods to remove the reactor’s debris.

Unit 2 is one of the Fukushima reactors that melted down following the 2011 earthquake and tsunami.

The plant’s operator, Tokyo Electric Power Co., needs to know the melted fuel’s exact location as well as structural damage in each of the three wrecked reactors to figure out the best and safest ways to remove the fuel. Probes must rely on remote-controlled robots because radiation levels are too high for humans to survive.

Despite the incomplete probe missions, officials have said they want to stick to their schedule to determine the removal methods this summer and start work in 2021.

Earlier probes have suggested worse-than-anticipated challenges for the plant’s cleanup, which is expected to take decades. During the Unit 2 probe in early February, the “scorpion” robot crawler stalled after its total radiation exposure reached its limit in two hours, one-fifth of what was anticipated.

“We should think out of the box so we can examine the bottom of the core and how melted fuel debris spread out,” Masuda told reporters.

Probes are also being planned for the other two reactors. A tiny waterproof robot will be sent into Unit 1 in coming weeks, while experts are still trying to figure out a way to access the badly damaged Unit 3.

TEPCO is struggling with the plant’s decommissioning. The 2011 meltdown forced tens of thousands of nearby residents to evacuate their homes, and many have still not been able to return home due to high radiation levels.

Cleanup of communities outside of the plant is also a challenge. The cost has reportedly almost doubled to 4 trillion yen ($35 billion) from an earlier estimate. On Thursday, police arrested an Environment Ministry employee for allegedly taking bribes from a local construction firm president, media reports said. ”

by Mari Yamaguchi, The Associated Press

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VOX POPULI: There’s no end to Fukushima crisis while melted fuel remains — The Asahi Shimbun

” A massive concrete structure encases the wrecked No. 4 reactor at the Chernobyl nuclear power plant, site of the catastrophic 1986 accident.

Dubbed the “sarcophagus,” it was erected to contain the fuel that could not be extracted from the crippled reactor.

I never expected this word (“sekkan” in Japanese) to crop up in connection with the 2011 Fukushima nuclear crisis.

Local governments raised objections to the use of this word in a report compiled by a government organ that supports the decommissioning of the Fukushima No. 1 nuclear power plant.

While the report discusses the extraction of melted fuel as a requirement, it is written in such a way as to suggest that the construction of a sarcophagus is an option that should not be dismissed out of hand.

This outraged the governor of Fukushima, Masao Uchibori, who lashed out, “Containing (the melted fuel) in a sarcophagus spells giving up hope for post-disaster reconstruction and for returning home.”

The government organ has since deleted the word from the report, admitting that it was misleading and that constructing a sarcophagus is not under consideration.

The report lacked any consideration for the feelings of local citizens. But more to the point, just deleting the word does not settle this case.

Even though five years have passed since the disaster, nothing has been decided yet on how to extract the melted fuel. How, then, can anyone guarantee that the fuel will never be “entombed”?

I am reminded anew of the sheer difficulty of decommissioning nuclear reactors. The Fukushima edition of The Asahi Shimbun runs a weekly report on the work being done at the Fukushima No. 1 plant.

The report portrays the harsh realities at the site, such as leaks of contaminated water and accidents involving workers. Efforts to decommission the crippled reactors continue day after day, but the task is expected to take several decades.

Elsewhere in Japan, the rule that requires nuclear reactors to be decommissioned after 40 years is becoming toothless, and preparations are proceeding steadily for restarting reactors that have remained offline.

“Normalcy” appears to be returning, but there is a huge gap between that and the unending hardships in the disaster-affected areas. ”

by Vox Populi.

“Vox Dei is a popular daily column that takes up a wide range of topics, including culture, arts and social trends and developments. Written by veteran Asahi Shimbun writers, the column provides useful perspectives on and insights into contemporary Japan and its culture.”

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Tepco releases first images of Fukushima reactor 3’s containment vessel: Fox News Latino; The Asahi Shimbun

Fox News Latino:

” The operator of Japan’s troubled Fukushima nuclear power plant has released the first pictures of the interior of reactor 3, thanks to two cameras that revealed a substance that could be melted nuclear fuel.

Tokyo Electric Power, or TEPCO, technicians introduced the cameras through a pipe, along with a thermometer and a measuring device, into the reactor’s containment vessel to assess the state of the nuclear fuel.

Radiation levels were recorded at about 1 sievert per hour – more than 1 million times the maximum recommended level – inside the vessel, while the temperature was between 26 C and 27 C above the ambient temperature, TEPCO said.

The radioactive water at the bottom of the vessel is 6.5 meters (21 feet) high, in line with technical estimates, and has a temperature of about 33-35 C.

The video and photographs taken by the remote-control operated cameras did not confirm damage to the containment vessel caused by molten nuclear fuel.

One of the cameras showed sediment similar to mud, which could be melted fuel.

TEPCO is expected to take water samples this week to analyze the concentration of radioactive substances.

An earthquake and tsunami in northeastern Japan on March 11, 2011, killed 15,853 people, left 3,282 others missing and damaged the Fukushima nuclear power plant, causing the worst nuclear accident since Chernobyl. EFE ”

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The Asahi Shimbun:

” More than four years after the triple meltdown, Tokyo Electric Power Co. on Oct. 20 got its first look inside the containment vessel of the No. 3 reactor at the Fukushima No. 1 nuclear plant.

Images from an industrial endoscope inserted into the containment vessel along a wall confirmed no damage to pipes and other equipment, according to TEPCO.

The early survey results for the days-long study also found radiation levels inside the containment vessel were 1 sievert per hour, a reading too high for humans to work there.

TEPCO also said 6.4 meters of water had accumulated on the bottom of the containment vessel, which was in line with the utility’s estimate.

Water temperatures were 33 to 35 degrees and air temperatures were 26 to 27 degrees inside the vessel, according to TEPCO.

The survey is being carried out to prepare for the eventual extraction of melted fuel from the containment vessel.

TEPCO carried out endoscope surveys at the containment vessels for No. 1 and No. 2 reactors in 2012. The radiation level at the No. 3 reactor was lower than those at the No. 1 and No. 2 reactor buildings. ”

source with a video of the Reactor 3 containment vessel

JAEA opens Fukushima R&D center for decommissioning reactors — The Asahi Shimbun

” NARAHA, Fukushima Prefecture–The Japan Atomic Energy Agency officially christened its new facility here on Oct. 19 that will develop technologies to decommission the reactors at the crippled Fukushima No. 1 nuclear power plant.

The Naraha Remote Technology Development Center will conduct research to develop remote-control decommissioning technologies as radiation levels within the reactors remain too high for workers to enter following a triple meltdown in the aftermath of the 2011 Great East Japan Earthquake and tsunami.

The opening ceremony was attended by 105 people, including Prime Minister Shinzo Abe, science and technology minister Hiroshi Hase and Fukushima Governor Masao Uchibori.

“The decommissioning process is a lengthy one that will take up to 40 years,” Abe said. “This facility was set up to consolidate the world’s knowledge to face the unknown.”

Featuring a life-sized mock-up of a damaged reactor and virtual reality systems, the center will test new machines and methods to remotely remove nuclear fuel from the Fukushima plant.

Experts hope that research and development at the facility will lead to a reduction in the number of failures of devices deployed at the crippled plant.

Abe witnessed a demonstration of a new scorpion-shaped robot, which will eventually be deployed inside the No. 2 reactor at the Fukushima plant.

The Naraha center will also erect in March a life-sized model of a reactor suppression chamber located beneath the containment vessel that was damaged in the 2011 disaster. Because the containment vessel has to be filled with water to remove the melted fuel inside, researchers plan to first develop technology to patch up the container to prevent leaks.

The facility is also equipped with a virtual reality system that projects onto a screen a computer-generated world simulating the space inside the damaged reactor buildings. The interior layouts of the crippled buildings are based on data collected by remote control robots deployed at the plant.

The technology will devise routes in removing melted fuel, along with coming up with methods to minimize the amount of radiation that workers will be exposed to.

The JAEA is also setting up a facility in Okuma to monitor the amount of radioactive materials inside the plant grounds. A total of 85 billion yen ($711.4 million) will be used to build the two JAEA facilities.

“There are still 100,000 people evacuated from the disaster,” said Toshio Kodama, JAEA president. “We hope to fulfill the role the JAEA is meant to play in the decommissioning process.” ”

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Editorial: No more half-baked plans for decommissioning Fukushima reactors — The Asahi Shimbun

” For the first time in two years, the government and Tokyo Electric Power Co. have announced a revised mid- to long-term road map for decommissioning nuclear reactors at the crippled Fukushima No. 1 power station. The removal of spent nuclear fuel from storage pools at the No. 1, No. 2 and No. 3 reactors will be delayed by up to three years.

The government and TEPCO explained this delay is due to their new policy of “risk reduction over speed.”

This delay, right from the start, must mean that the old road map was poorly planned.

Are the government and TEPCO really able to now foretell that the delay will be three years at most? And why was risk reduction not their top priority until now?

The government and TEPCO must draw concrete lessons from all the delays to date and apply the lessons to the long-term decommissioning road map.

Spent nuclear fuel in the fuel pools must be removed to a safe place as soon as possible. Delays in its removal are caused by the time-consuming preparatory work of debris removal and decontamination of workspace floors.

In autumn 2013, Prime Minister Shinzo Abe declared in his 2020 Olympics bid speech that the situation was “under control.”

Since then, it has become abundantly clear that the situation is anything but under control, and that the previous decommissioning road map failed to accurately assess the high level and extensive spread of radiation contamination.

Removing debris releases radioactive substances into the atmosphere, possibly causing them to spread beyond the plant grounds. Delays in decontamination expose workers to higher doses of radiation and limit their working hours.

Although nobody knew the amount or exact location of melted fuel in the reactors, the old road map indicated the “flooding method” of removal, meaning the containment vessels of the No. 1, No. 2 and No. 3 reactors were to be filled with water. This method is similar to the usual removal method.

But probing the conditions of the containment vessels by various means revealed the difficulties of stopping the water leakage and problems regarding earthquake-proofing. It is only natural that the new road map proposes to reject the flooding method for the time being and study other removal methods over the next two years.

What we do not understand is why the government and TEPCO continued to reject the recommendation of outside experts to study the matter more broadly.

Last month, TEPCO announced the “completion” of processing a massive amount of highly contaminated water that had collected in clusters of storage tanks. But work is still continuing on separating radioactive substances from about 300 tons of highly contaminated water, which is generated every day. Any water still contaminated by unremoved tritium continues to remain in the tanks.

The decommissioning of reactors after a nuclear disaster is a truly challenging task that Japan has never experienced before.

The government and TEPCO must proceed by prioritizing risk reduction while explaining the situation to the local communities and the nation at large to win their understanding of the decommissioning work itself. ”

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