Challenges ahead for debris removal at Fukushima — NHK World

” This year will mark the 7th anniversary of the nuclear accident at the Fukushima Daiichi plant that occurred in March, 2011. The plant’s operator is hoping to eventually remove fuel debris from the damaged reactors.

Fuel debris is a mixture of melted nuclear fuel and broken reactor parts. Removing the debris is considered to be the biggest hurdle to the decommissioning of the reactors.

Last year, Tokyo Electric Power Company, or TEPCO, investigated the inside of the containment vessels of 3 reactors and confirmed, for the first time, the existence of lumps that are believed to be fuel debris in the No.3 reactor.

TEPCO plans to conduct a fresh probe of the No.2 reactor this month to confirm whether a mass on the floor under the reactor, observed last year, is actually fuel debris.

The government and TEPCO aim to begin removing debris in 2021. They are planning to determine which reactor to start with, and how to conduct the procedure, during fiscal 2019.

Workers will try this year to figure out which details need to be considered in order to make the decision.

Removing the debris requires thorough safety measures. For example, radioactive materials must be prevented from spreading and workers must be protected from exposure to radiation.

This autumn, the operator also plans to start removing spent nuclear fuel rods from the storage pool of the No.3 reactor building. ”

by NHK World

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Work to finish ice wall at crippled plant to begin — NHK World

” The operator of the crippled Fukushima Daiichi nuclear plant will begin the final phase of creating an underground ice wall on Tuesday.

Tokyo Electric Power Company started the work 17 months ago, with the aim of preventing groundwater from entering reactor buildings and getting contaminated with radioactive substances.

The 1.5-kilometer ice barrier is deemed a key step to curb the buildup of tainted water at the plant.

The soil is frozen by sending liquid at minus 30 degrees Celsius into pipes buried around the buildings. But the utility has left a 7-meter section unfrozen, fearing the sudden fall in groundwater levels around the buildings.

There were concerns that the difference of water levels in and outside the reactor buildings would cause tainted water inside to leak out.

But last Tuesday, the Nuclear Regulation Authority said safety measures are ready and gave its approval to freeze of the final section.

Officials of the utility say they will carefully monitor the freezing process of the remaining section.

They say it may take longer to fully freeze than other areas, because the flow of groundwater has been concentrated in that section.

The officials expect that the wall, when completed, will reduce the inflow of groundwater to the buildings from 140 tons a day to less than 100 tons. ”

by NHK World

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Nuclear authority chief raps Tepco’s attitude toward Fukushima — The Mainichi

” TOKYO (Kyodo) — The head of Japan’s nuclear safety watchdog on Monday criticized the attitude of Tokyo Electric Power Company Holdings Inc. toward decommissioning of the crisis-hit Fukushima Daiichi nuclear power plant and questioned the company’s ability to resume operation of other reactors.

 “I feel a sense of danger,” Nuclear Regulation Authority Chairman Shunichi Tanaka said during a special meeting with the company’s top management, adding that Tokyo Electric does “not seem to have a will to take initiative” toward decommissioning of the crippled Fukushima Daiichi plant.

Takashi Kawamura, the chairman of the power company known as Tepco, and its president, Tomoaki Kobayakawa, attended the meeting. The authority felt it is necessary to hear from the top executives before it could make a decision on whether to approve Tepco’s plan to resume operation of the Nos. 6 and 7 reactors at its Kashiwazaki-Kariwa plant in Niigata Prefecture.

Tepco filed for state safety assessment of the two reactors in September 2013 to reactivate them, hoping to restore its financial condition as it needed massive funds to pay compensation related to the Fukushima Daiichi disaster, triggered by a huge earthquake and tsunami on March 11, 2011, and to scrap the plant that suffered meltdowns.

The watchdog’s safety screening has found Tepco’s failure to report insufficient earthquake resistance of a facility built to serve as the base to deal with a possible nuclear accident at the Niigata complex although it had acknowledged the insufficiency for three years.

In June, Tepco submitted to the watchdog its revised safety measures for the Kashiwazaki-Kariwa complex.

“An operator lacking will to take initiative does not have the right to resume operation of nuclear reactors,” Tanaka said.

Tepco’s chairman responded by saying, “There are citizens who believe nuclear power is necessary. Operating reactors is our responsibility.”

But he also admitted there is room for only two more years’ worth of space in the tanks to accommodate contaminated water stemming from the Fukushima complex.

At Monday’s meeting, the watchdog asked Tepco’s top management about the company’s safety measures for the Niigata complex on the Sea of Japan coast as well as its safety awareness.

Tanaka said the authority does not view that it received sufficient responses from Tepco at the meeting and requested that the company submit more explanation on its plan to decommission the Fukushima complex and resume operation of the two reactors at the Kashiwazaki-Kariwa plant.

Tanaka plans to conduct on-site checkups at the two reactors of the plant in Niigata, saying, “Tepco, which caused the (Fukushima) accident, is not an ordinary operator.”

The two boiling water reactors at the Niigata plant are the same type as those that suffered core meltdowns at the Fukushima Daiichi complex, and no such reactors have cleared the authority’s safety screening since the Fukushima disaster. “

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Study: Possible water problem at storage sites in Fukushima — The Asahi Shimbun

” Bags of radiation-contaminated soil could be sinking into the ground at temporary storage sites in Fukushima Prefecture, allowing water to accumulate within instead of flowing to outside tanks for testing, the Board of Audit said.

No confirmation has been made that the ground at the sites is actually sinking or if contaminated water has pooled inside. But Board of Audit officials are asking the Environment Ministry to consider additional safety measures if signs indicate that this is actually occurring.

The board’s study focused on 34 of the 106 temporary storage sites that the Environment Ministry set up for soil removed through decontamination work after the disaster in March 2011 unfolded at the Fukushima No. 1 nuclear power plant.

Construction of the storage sites started in 2012, and the transfer of contaminated soil to these facilities was completed in 2015.

The temporary storage sites were designed to have a slight mound on the ground in the center to allow water from the bags to flow down into surrounding collection tanks for periodic measurements of radiation levels.

Internal Environment Ministry guidelines called for this setup at storage sites containing bags that are not waterproof.

The Board of Audit studied 34 temporary storage sites where the bags are not waterproof. These bags were piled five deep or higher at those sites.

The study showed that at 31 of the sites, the weight of the bags may have not only flattened the mound in the center, but it also could have created an indent in the ground where the leaking water could accumulate.

If the water does not flow to the tanks, it will be difficult to determine the radiation levels.

The study also noted that the foundations at the sites were soft to begin with and may be unable to support the bags of soil. The sinking phenomenon could worsen as time passes.

The Environment Ministry played down the risk of the water contaminating areas around the storage facilities.

“Even if the ground has sunk, the structure is designed so water does not leak outside the site,” a ministry official said. “Eventually, the water should collect in the tanks. We will make every effort to oversee the sites as well as use waterproof bags as much as possible.”

A total of 4.16 billion yen ($40 million) was spent to construct the 31 temporary storage sites.

The Environment Ministry designed the temporary storage sites under the precondition they would be used for only three years and then removed. For that reason, measures were not taken to strengthen the foundations to prevent the ground from sinking, even if soft farmland was chosen for a site.

The plan is to eventually return the land where the temporary storage sites have been built to its original state and return it to the landowners.

However, the Board of Audit’s study adds another concern for residents, many of whom had opposed construction of the temporary storage sites in their neighborhoods.

Toshio Sato, 68, has evacuated to Fukushima city from his home in Iitate village, where four of the possible problem storage sites are located.

“There are some people who want to resume growing rice once they return home,” Sato said. “If water is accumulating, there is the possibility it could unexpectedly overflow into surrounding areas. The concerns just seem to emerge one after another.”

The government plans to lift the evacuation order for a large part of Iitate in March 2017. ”

by Kosuke Tauchi, Shoko Rikimaru, Kenji Izawa and Akifumi Nagahashi

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Radioactive soil turns up at Fukushima high school — The Asahi Shimbun

” FUKUSHIMA–Highly radioactive soil that should by law be removed by the central government has been left dumped in the corner of a schoolyard here because the construction of a local storage site for waste has been stalled.

Students at the school were not given an official warning that the radioactive soil was potentially hazardous to their health.

When a teacher scooped up soil samples at the site and had their radiation levels measured by two nonprofit monitoring entities–one in Fukushima and another in Tokyo–the results showed 27,000-33,000 becquerels of radioactive cesium per kilogram.

The law stipulates that the central government is responsible for disposing of waste measuring more than 8,000 becquerels per kilogram.

But as a central government project to build an interim storage site for highly radioactive waste near the nuclear power plant has been stalled, the school appears to have no alternative to indefinitely keeping it in the schoolyard.

Principal Seiichi Takano at Fukushima North High School said the school does not plan to take extra safety measures with regard to the storage of the polluted dirt, saying the waste is not believed to be outright dangerous.

“The prefectural board of education has not set any criteria for us to conclude at what levels of radiation are hazardous to people,” he said.

The fallout is a result of the nuclear disaster at the Fukushima No. 1 power plant, which unfolded following the Great East Japan Earthquake and ensuing tsunami on March 11, 2011.

Before the cleanup operation at the school in the city’s Iizaka district on May 24-25, the teacher who took the samples called on school officials to take precautionary measures and issue an alert for students.

“Since it is highly radioactive, we should remind students and staff of the potential danger while taking a step to prevent the spread of polluted dust during cleanup,” said the teacher.

Highly radioactive dirt, which was mixed with tree branches and plants, amounted to 20 cubic meters, according to cleanup workers. It had been left for several years in an area near the parking lot for bicycles used by students.

School officials say they plan to bury the bags by digging deep holes on the school premises to temporarily store them, but they have no idea when they will finally be removed.

The polluted dirt in the latest cleanup first came to the attention of school officials in March when a preliminary survey detected 1.6 microsieverts per hour of radiation at a point 1 meter from the surface of the ground near the bicycle parking lot. The survey is routine before any cleanup gets under way in earnest.

A cleanup operation is conducted with the aim of lowering radiation exposure to below 0.23 microsieverts per hour, a long-term goal the central government has set to limit residents’ annual additional exposure to a maximum of 1 millisievert.

In the previous decontamination operation, the school’s playground was cleaned in August 2011 before classes were resumed for that academic year after a break after the nuclear accident.

A large amount of contaminated soil–far more radioactive than in the current incident–is still buried in the schoolyard for temporary storage.

Cleanup resumed only this spring for the rest of the school premises and its neighborhood in line with a general cleanup plan in Fukushima.

An official with the prefectural board of education said it is not considering additional safety measures concerning the storage of polluted soil kept at the school.

“We are going to ensure safety by taking an approach similar to the existing one before the polluted soil is transported to the interim storage facility,” said a board official. ”

by Masakazu Honda

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Japan’s worst quake since 2011 seen delaying nuclear starts — Bloomberg

” Japan’s biggest earthquake in five years may slow a government plan to restart the country’s atomic fleet that was shuttered amid safety concerns after the March 2011 earthquake and tsunami that caused the triple meltdown at Fukushima.

A series of earthquakes, including a magnitude-7.3 tremor that struck about 119 kilometers (74 miles) from the Sendai nuclear facility on the southern island of Kyushu this month, destroyed hundreds of homes, snapped bridges and left at least 49 people dead. It has also revived an effort to halt the plants’ operations.

The events may delay Prime Minister Shinzo Abe’s goal of returning the country’s nuclear power plants to operation. About 60 percent of Japanese citizens oppose restarting reactors, according to a Nikkei newspaper poll from February, and the earthquake is intensifying pressure on the country’s nuclear regulator to vet safety rules.

“Nuclear is under a magnifying glass now, so even the smallest problem can create big delays,” Michael Jones, a Singapore-based gas and power analyst at Wood Mackenzie Ltd. said in an e-mail. “Fukushima has changed everything, and earthquakes and volcanoes are only making things worse.”

Transport Disruptions

Trains and highways were damaged in the Kyushu earthquake and if there is a nuclear accident from another earthquake or volcanic eruption, evacuations may be difficult, Datsugenpatsu Bengodan, a group of lawyers working to wean Japan off nuclear power said in an April 19 statement. The group said Kyushu Electric Power Co.’s Sendai No. 1 and 2 reactors, which were the first to restart under post-Fukushima safety rules last year, should be shut.

An e-mail to Japan’s Nuclear Regulation Authority outside of normal business hours wasn’t immediately answered.

Evacuation Procedures

“Given this is the largest earthquake in over a century in Kyushu that has caused significant damage to infrastructure, it could slow down the pace of restarts,” said Tom O’Sullivan, founder of Mathyos, a Tokyo-based energy consultant. “It may now be even more imperative that emergency evacuation procedures are thoroughly tested.”

A nuclear accident at Sendai would require the evacuation of about 5,000 people in the surrounding 5 kilometers and more than 200,000 would need to seek immediate shelter within a 5- to 30-kilometer radius, according to a local government simulation from 2014.

The NRA, Japan’s nuclear regulator, said on April 18 that it sees no need to shut the two Sendai reactors. A high court on April 6 upheld a ruling that the Sendai reactors can withstand seismic damage and don’t pose a risk to the surrounding area.

A local court issued an injunction in March preventing the operation of Kansai Electric Power Co.’s Takahama No. 3 and 4 reactors, questioning whether evacuation plans and tsunami prevention measures — which had been endorsed by the government — were robust enough.

The earthquake near Japan’s only operating reactors “may boost the nation’s anti-nuclear sentiment,” Joseph Jacobelli, an analyst at Bloomberg Intelligence, said in an April 22 note. “Technical and political obstacles mean even those units approved for restart are returning at a snail’s pace.” ”

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