Footage reveals highly radioactive area in crippled Fukushima Daiichi
21 sept. 2021
The Nuclear Regulation Authority reveals footage of a highly radioactive area in Fukushima Daiichi, which may affect decommissioning plans.
Japan eyes disposal abroad of radioactive plant equipment
Watch out! Japan’s hoping to export now its radioactive junk!
September 20, 2021
Japan plans to ease regulations to allow exports of large, disused equipment from nuclear power plants for overseas disposal as a way to reduce the mountains of radioactive waste accumulating at home.
The setup would mark a major shift from the government’s existing principle of disposing of all radioactive waste inside the country.
The industry ministry mentioned the revised disposal policy in the draft of the updated Basic Energy Plan, which awaits Cabinet approval in October at the earliest.
Even if the plan is approved, it will likely take some time for the government and nuclear plant operators to clear a slew of hurdles, such as estimating the costs of the project and ensuring the safety of shipments.
The Ministry of Economy, Trade and Industry, which oversees the nuclear industry, is considering outsourcing the disposal of three kinds of large low-level radioactive equipment overseas: steam generators, feed-water heaters and nuclear fuel storing and shipping casks.
These components range in size from 5 to 20 meters and weigh 100 to 300 tons.
Although they are not highly contaminated, compared with nuclear debris generated by spent fuel, they must be disposed of and managed properly, including being buried deep in the ground for years.
The ministry is considering their export as an “exceptional measure” to deal with the grave issue of the radioactive waste accumulating at nuclear facilities across Japan.
“Export regulations will be reviewed to allow for export (of low-level radioactive waste) when certain conditions are met, such as their safe recycling into useful resources,” the draft for the latest version of the Basic Energy Plan said.
The industry ministry is soliciting public opinions on the outsourcing plan until Oct. 4.
Nuclear plant operators have decided to decommission 24 reactors, including the six units at the crippled Fukushima No. 1 nuclear plant.
Work to dismantle those reactors is expected to go into full gear starting in 2025.
Excluding the reactors at the Fukushima plant, the decommissioned units will produce an estimated 165,000 tons of low-level radioactive waste.
But more than 90 percent of that waste has nowhere to go for dismantling and disposal.
Japan still lacks a dedicated disposal site for equipment used at nuclear plants, forcing plant operators to store the waste at their facilities.
The ministry says the storage of the out-of-service equipment is getting in the way of the decommissioning process.
Experts say some businesses in the United States and Sweden clean, melt and recycle metal from radioactive waste sent by foreign countries.
“Japan should first learn the know-how of disposal by outsourcing the work to foreign businesses with a reliable track record in the area and eventually become capable of doing it at home,” said Koji Okamoto, a professor of nuclear engineering at the University of Tokyo.
Under the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management, signatory countries that produce radioactive waste are obliged, in principle, to dispose of it within their territories.
But they can export the waste as exceptional cases if they obtain the consent of countries where business partners are based.
However, Japan’s Foreign Exchange and Foreign Trade Control Law bans such exports.
Utilities have pressed the government for a change in the disposal policy, and the industry ministry has been reviewing the existing setup alongside experts on nuclear technology.
Although the ministry intends to follow the principle of doing away with the waste within Japan, it plans to approve exports of the three types of nuclear plant equipment on condition that they will be recycled.
Ministry officials say the plan can be achieved through a revised ministry directive, without having to change the law.
The equipment intended for recycling overseas could include components kept at nuclear plants that still generate power.
But the ministry needs to work out many issues to turn the plan into reality.
Nuclear plant operators have the primary responsibility for disposing of low-level radioactive waste. And the actual costs these Japanese companies would have to pay to recyclers overseas is still unknown.
The bill could be far more expensive than initially estimated.
How to safely ship the radiation-contaminated equipment abroad is another unresolved issue.
The amount of nuclear waste in Japan has been growing since the 2011 Fukushima nuclear disaster. Utilities have gradually resumed operations at nuclear plants, but some have decided to decommission reactors, particularly aging ones, largely because of the costs needed to upgrade them under new safety standards.
For decades, Japan has been unable to secure a final disposal site for such waste inside the country, mainly because of opposition from residents of candidate sites.
Decade after Fukushima disaster, Greenpeace sees cleanup failure
Greenpeace has recommended that Japan suspend the current return policies, which it says “ignore science-based analysis, including potential lifetime exposure risks to the population” and abandon plans to lift evacuation orders in six municipalities
Mar 4, 2021
Ten years after the worst nuclear accident since Chernobyl, land Japan identified for cleanup from the triple reactor meltdown of the Fukushima No. 1 power plant remains contaminated, according to a report from Greenpeace.
On average, just 15% of land in the “Special Decontamination Area,” which is home to several municipalities, has been cleaned up, according to the environmental advocacy group’s analysis of government data. That’s despite the government’s claims that the area has largely been decontaminated, the group said.
In addition, Greenpeace said its own radiation surveys conducted over the last decade have consistently found readings above government target levels, including in areas that have been reopened to the public. The lifting of evacuation orders in places where radiation remains above safe levels potentially exposes people to an increased risk of cancer, the report said.
“The contamination remains and is widespread, and is still a very real threat to long term human health and the environment,” the report said.
Japan’s Ministry of Environment wasn’t immediately available for comment. Decontamination efforts have reduced radiation levels in residential areas by an average of 76%, according to the ministry’s website, which has compiled monitoring data through 2018. Fukushima Prefecture wasn’t immediately available for comment.
More than 160,000 people were evacuated from the area surrounding the Fukushima nuclear plant after a magnitude 9 earthquake, the biggest ever recorded to hit Japan, caused a massive tsunami that overwhelmed the plant. While the government has been steadily lifting evacuation orders on towns since 2014, roughly 36,000 people are still displaced.
Greenpeace recommended that Japan suspend the current return policy, which “ignore science-based analysis, including potential lifetime exposure risks to the population” and abandon plans to lift evacuation orders in six municipalities.
https://www.japantimes.co.jp/news/2021/03/04/national/fukushima-greenpeace-radiation-health-3-11/
Decades-long challenge to scrap Fukushima plant by 2051 in a bind
March 1, 2021
The decades-long challenge to scrap the Fukushima Daiichi nuclear plant, crippled by the massive earthquake and tsunami disaster that struck northeastern Japan in 2011, is becoming more complex as recent remote-controlled probes have highlighted just how damaged the reactors are.
Tokyo Electric Power Company Holdings Inc., operator of the six-reactor nuclear complex, aims to scrap the plant between 2041 and 2051. But critics have cast doubts on the schedule, citing not only the extremely high radiation levels, but problems associated with delayed probes and underdeveloped robots and other technology needed to extract an estimated nearly 900 tons of melted fuel debris.
Decommissioning of the plant, scene of the world’s worst nuclear accident since the 1986 Chernobyl disaster, is crucial for Japan if it wants to stick to using nuclear power safely and show the world that the nuclear crisis is under control.
“It is likely that the roadmap will not be completed as scheduled,” said Tetsuro Tsutsui, a member of the Citizens’ Commission on Nuclear Energy, a group comprising academics and nuclear experts.
He added the “melted debris is mixed with fractured parts of buildings and concrete material and is highly radioactive, making it hard for robots to clear the debris.”
The scrapping of the plant involves the daunting decision on how to dispose of the huge amount of radioactive waste left as a byproduct. This has been made worse as no municipality offered to become the final disposal site when the plant was operating.
Following a magnitude-9.0 earthquake and subsequent tsunami that hit the plant on March 11, 2011, Nos. 1 to 3 reactors at the Fukushima Daiichi plant suffered meltdowns, while hydrogen explosions damaged the buildings housing the Nos. 1, 3 and 4 reactors.
Photo taken on Nov. 12, 2011, shows the No. 3 reactor building at the Fukushima Daiichi nuclear power plant in Fukushima Prefecture, northeastern Japan, which was damaged by an explosion after the March 11 earthquake and tsunami.
Due to the instability of renewable energy, Japan projects atomic power will remain one of its major power sources, accounting for 20 to 22 percent of its total electricity generation in fiscal 2030. It may further push the emissions-free nuclear power as it aims to become carbon neutral in 2050.
Of the 33 reactors in Japan, excluding those set to be scrapped, just four are currently in operation, partly because they need to clear stricter safety regulations following the Fukushima accident.
Tsutsui, a former petrochemical complex engineer, points to how the risk of extracting debris has become “clearer” compared to when the roadmap was first compiled in December 2011. With that in mind, he urged the government to act responsibly and review the roadmap.
“Nearly 10 years have passed following the Fukushima accident but with respect to the long decommissioning process, we are still hovering around the start line. We have a long journey ahead,” said Fukushima Gov. Masao Uchibori in a recent briefing.
“The most difficult step is the safe and stable retrieval of the debris but we don’t know what state it is in,” he added.
Fukushima Daiichi nuclear complex on Feb. 21, 2018. From right, No. 1, No. 2, No. 3 and No. 4 reactors.
Despite the use of computer simulations and small-scale internal probes using remote cameras, data is scarce about the exact locations and other details of the melted fuel — crucial information to determine the retrieval methods and develop the appropriate technology and robots.
Robotic probes at the Nos. 2 and 3 units have captured images of large amounts of material that appear to be melted fuel, but attempts so far have been unsuccessful at the No. 1 unit.
TEPCO opted to start the fuel removal at the No. 2 unit as it has the best grasp of the internal conditions there but no time frame has been set for the two other units.
In a setback for retrieval efforts, the company said in late December removing melted fuel from the No. 2 unit would be delayed from its initial starting period in 2021 by at least a year as the coronavirus pandemic has stalled the development in Britain of a robotic arm to be used for the extraction.
That robotic arm, however, can only extract a few grams of melted fuel debris at a time. To completely remove the hundreds of tons of melted fuel from the reactor larger machinery is required, experts say.
In another development that may affect the decommissioning process, a Nuclear Regulation Authority study group said in January a high concentration of radioactive cesium is likely to have accumulated in the lids of the containment vessels for the No. 2 and No. 3 reactors.
The regulator’s findings in a new interim report draft on the Fukushima accident came as a shock because it was previously believed that most of the radioactive material remained at the bottom of the reactors in the form of melted nuclear fuel debris.
While industry minister Hiroshi Kajiyama has acknowledged the “delays” and “difficulties in making predictions,” he insisted the overall decommissioning process is making “steady progress.” The government and TEPCO say they will stick to the current roadmap.
TEPCO, whose biggest shareholder is the Japanese government, has not given an estimate of the costs for the debris removal, which would add to the 8 trillion yen ($75 billion) already forecast for the decommissioning process.
The utility and the government have also been grappling with the buildup of radioactive water, which is generated in the process of cooling the meltdown reactors.
Part of the water is stored inside massive tanks set up inside the premises, having gone through a system that removes various radioactive materials except tritium, which is difficult to separate from water.
Tanks containing treated water including radioactive tritium are stored on the premises of the Fukushima Daiichi nuclear complex on Feb. 21, 2018.
The government is considering dumping the water into the Pacific after diluting it to a radiation level below the legal limit, saying the tanks are filling up. It says space is needed to store debris once it is extracted from the damaged reactors.
But discharging the water remains a sensitive issue especially for the local fishing industry struggling to revive its business following the accident. Neighbors South Korea and China as well as U.N. human rights experts have expressed caution about the discharge.
Releasing it into the ocean could lead to a continued ban on exports from this area or an introduction of new export restrictions, observers say.
According to Yasuro Kawai, another member of the commission, the government’s decision to release treated water into the sea is in fact the government’s attempt to minimize the impact of the Fukushima crisis and say dismantling work is on track.
“But the roadmap is nothing but pie in the sky,” he said.
The commission says it is more logical to keep the debris inside the reactors than to retrieve it and suggests constructing a shield around the reactors and postpone taking out the melted fuel until 100 years or 200 years later when radioactive activity levels have decreased.
Fukushima College robot wins top prize for nuclear decommissioning
The Mehikari robot developed by a team at Fukushima College
Jan 25, 2021
Fukushima – A robot created by a team from a technology college in northeastern Japan recently won the top prize in a robotics competition that had the theme of decommissioning the Fukushima No. 1 nuclear power plant.
The Mehikari robot of Fukushima College earned praise for its speed as well as ability to employ different methods to retrieve mock debris similar in size to that at the plant, the site of a nuclear disaster triggered by a massive earthquake and tsunami on March 11, 2011.
The robot completed the set task in about 2 minutes, the fastest time, in the annual competition aimed at fostering future engineers that was attended by students from 13 colleges belonging to the National Institute of Technology.
Sunday’s competition was the fifth of its kind. Students in 14 teams from the colleges across the country such as in Osaka and Kumamoto prefectures were tasked this year with developing robots to remove fuel debris from the plant, organizers said.
“I’ll be happy if our robot is useful on the ground,” said Hiroha Toba, the 18-year-old leader of the winning team.
The robots were required to pass through a 4-meter-long pipe, land on a pedestal, collect balls representing fuel debris situated 3.2 meters below and return within 10 minutes.
The robots had to be remotely operable without a direct line of sight.
Also according to the contest rules, radio waves could not penetrate certain sections of the field, resembling the real-life situation in which the Fukushima No. 1 plant is covered by thick concrete walls. This meant the teams had to transmit directions by wire when the robots passed those areas.
Due to the coronavirus pandemic, the teams submitted videos of the robots’ performance to the organizers in advance. They were evaluated based on speed, accuracy and originality of retrieval method.
The competition was mainly organized by the Japan Atomic Energy Agency and had the support of the education ministry and other entities.
Agency: Fukushima plant workers should be heard
Oct. 11, 2020
A government agency overseeing the decommissioning of the crippled Fukushima Daiichi nuclear plant is urging the plant’s operator to take into account the views of workers in removing radioactive debris, set to start next year.
Each year, the Nuclear Damage Compensation and Decommissioning Facilitation Corporation compiles its technical policy for the plant’s decommissioning. This year’s plan was recently announced.
It refers to the removal of fuel debris from the plant’s No.2 reactor starting next year. It warns that the work will take place in conditions where there is little information about the interior environment and a high level of radiation.
The agency proposes that Tokyo Electric Power Company seriously take into account the views and concerns of on-site workers, such as the operators of machinery used to remove fuel debris.
It calls for the information obtained from workers to be reflected in the design of equipment used to scrap the reactor.
The agency’s proposals will be reflected in TEPCO’s mid- and long-term schedules for decommissioning the plant.
Japan diver reflects on unsung workers exposed to radiation as Fukushima 10th anniv. Looms
Hisashi Okazaki is seen doing diving work at the Fukushima Daiichi Nuclear Power Plant’s No. 3 reactor in May 2006, in this image provided by Okazaki.
October 11, 2020
Have you ever heard of atomic divers? Hisashi Okazaki, 58, who has worked at nuclear power plants as a diver while being exposed to radiation, wants people to know that professional divers like himself work in dangerous conditions for nuclear reactors to run, as the 10-year anniversary of the Fukushima nuclear disaster approaches.
Among the places he has worked in his 33-year career as a professional diver is the Fukushima Daiichi Nuclear Power Plant, which would later go on to enter a meltdown following the Great East Japan Earthquake and resultant tsunami in March 2011.
Hisashi Okazaki is seen in Ehime Prefecture on Sept. 18, 2020.
After graduating high school, Okazaki, a resident of Seiyo in the western Japan prefecture of Ehime, entered the Japan Ground Self-Defense Force. Four years later he left, and got his professional diving license. Since then, he has worked primarily as a self-employed diver taking on jobs both at home and abroad, fulfilling tasks including laying oil pipelines and tetrapod sea defenses, as well as fixing sea walls damaged after the 1995 Great Hanshin Earthquake. He keeps illustrations of his dives as a record of what he’s done, and in all he has amassed more than 3,670 so far.
In 2006, a diver Okazaki knew invited him to work nuclear jobs. It was his first time working inside nuclear power facilities and being exposed to radiation, but he agreed to do it. Looking back, he said he did it because “I thought I wanted to experience anything I could. I had no fears.” His daily pay was 47,000 yen, almost twice the regular pay of around 25,000 yen for a day’s normal diving work.
Ahead of the job, 20 divers came together to train at a facility belonging to a heavy machinery maker situated in Kanagawa Prefecture south of Tokyo. They had on special heavy helmets weighing around 15 kilograms, and wore dry suits altered to stop water from entering them. They were hooked up to six cables, including for an air hose, photography, and radiation measurements. Both of their arms and legs as well as their chests were fitted with dosimeter equipment. After a week of training, the divers were dispersed to a number of nuclear plants across the country. Okazaki was dispatched to the Fukushima Daiichi Nuclear Power Plant’s No. 3 reactor.
There, he dived into the plant’s suppression chamber, which cools the reactor containment vessel in the event that the release of steam causes its pressure to rise. The chamber is a doughnut-shaped facility in the lower part of the vessel, with water about 3 meters deep in it. The maintenance work Okazaki undertook had to be done while it was filled and he did the work with another diver to exchange equipment in the facility.
An illustration of a diver replacing equipment underwater is seen in this image provided by Hisashi Okazaki.
The area where they worked had high doses of radiation, and in a single day’s diving they could work for about two hours. When they approached an area with a particularly high dosage, they would be instructed via a voice cable not to proceed further. The divers stayed in Fukushima Prefecture for about a month. Legal occupational exposure limits to radiation for a worker are set at 50 millisieverts per year, but in just the 12 days Okazaki worked at the plant, he was exposed to a total of 7.34 millisieverts. At the end of the job, the contaminated equipment they’d used was all put into a drum and disposed of.
“I couldn’t feel satisfied doing a job that leaves no trace of it behind,” Okazaki said. On his way back from Fukushima to Tokyo, Okazaki asked himself while in a car the purpose of his work that exposed him to radiation, and the younger diver who worked with him on the job said, “We did this for that view (of the city) at night, didn’t we?” Okazaki felt a little bit relieved by what they’d said, and after that he went on to do underwater cleaning work at the Onagawa Nuclear Power Station in northeast Japan’s Miyagi Prefecture.
Then, in March 2011, the Great East Japan Earthquake struck. Okazaki watched images of the hydrogen explosion at the Fukushima Daiichi Nuclear Power Station’s No. 3 reactor from a TV on a work barge in the sea off the Muroto Misaki cape in Kochi Prefecture, western Japan. “I’d never imagined the power would be lost and it would explode,” he said.
The use of divers for the decommissioning of the crippled nuclear reactor, such as in removal work and other tasks, is being considered. Even now, around 4,000 people are working at the Fukushima Daiichi plant each day. The decommissioning work, which is expected to take decades from now to finish, is employing robots to complete some tasks, but still the role of radiation-exposed human workers is vital. Okazaki said, “Even at the reactors that use the most technologically advanced equipment, there are sections which only human hands can deal with, and divers are part of the group of workers who take up such jobs.”
(Japanese original by Shunsuke Sekiya, City News Department)
https://mainichi.jp/english/articles/20201009/p2a/00m/0na/020000c
Ikata nuclear reactor to be shut down – 40 year decommissioning process
Regulator approves Ikata 2 decommissioning plan
Japan’s Nuclear Regulation Authority (NRA) today approved Shikoku Electric Power Company’s decommissioning plan for unit 2 of its Ikata nuclear power plant in Ehime prefecture. Decommissioning of the unit is expected to be completed by 2059.
07 October 2020
Ikata 2 is a 538 MWe pressurised water reactor that began operating in March 1988. It was taken offline in January 2012 for periodic inspections. Shikoku announced in March 2018 that it did not plan to restart the reactor. It said the cost and scale of modifications required to upgrade the 40-year-old unit to meet the country’s revised safety standards made it uneconomical to restart it.
The utility submitted an outline of its plans for decommissioning the unit to the NRA on 10 October, 2018. Shikoku also submitted requests to Ehime prefecture and the municipality of Ikata, as specified under nuclear safety agreements concluded with those authorities.
Following a review, which included a total of seven public meetings, the NRA has today approved the decommissioning plan for Ikata 2.
According to the plan, decommissioning of the unit will take about 40 years and will be carried out in four stages. The first stage, lasting about 10 years, will involve preparing the reactor for dismantling (including the removal of all fuel and surveying radioactive contamination), while the second, lasting 15 years, will be to dismantle peripheral equipment from the reactor and other major equipment. The third stage, taking about eight years, will involve the demolition of the reactor itself, while the fourth stage, taking about seven years, will see the demolition of all remaining buildings and the release of land for other uses.
During the first stage, all fuel is to be removed from the unit. This includes 316 used fuel assemblies that will be sent for reprocessing and 102 fresh fuel assemblies that will be returned to the fuel fabricator.
“In the future, we will obtain the consent of Ikata Town and Ehime Prefecture, based on the safety agreement,” Shikoku said.
Shikoku decided in March 2016 to decommission unit 1 of the Ikata plant, also a 538 MWe PWR, which began commercial operation in September 1977. That unit had been taken offline in September 2011 for periodic inspections. Upgrades costing more than JPY170 billion (USD1.5 billion) would have been needed at the unit in order for it to operate beyond 40 years. The NRA approved Shikoku’s decommissioning plan for Ikata 1 in June 2017. That plan also sees the unit being decommissioned in four stages over a 40-year period.
The utility said, “As with unit 1, we will steadily proceed with the decommissioning of unit 2 with the highest priority given to ensuring safety.”
https://www.world-nuclear-news.org/Articles/Regulator-approves-Ikata-2-decommissioning-plan
9 1/2 years after meltdowns, no end in sight for Fukushima nuke plant decommissioning
The No. 1 reactor building is seen at the Fukushima Daiichi Nuclear Power Station in Okuma, Fukushima Prefecture, on Sept. 1, 2020.
September 22, 2020
It has been some 9 1/2 years since the triple-meltdown disaster at the Fukushima Daiichi Nuclear Power Station in northeast Japan, and in early September I visited the plant to get a close-up look at the reactor buildings and find out how much progress is being made in dismantling them.
The trip began aboard a microbus, which stopped on an inland promontory running north to south at an elevation of 33.5 meters above sea level. Getting off the bus, I looked east, over the Pacific Ocean. And then I saw them, just 100 meters away or so: the buildings containing the plant’s No. 1 to 4 reactors.
When a tsunami triggered by the March 11, 2011 Great East Japan Earthquake slammed into the coastal facility, reactors 1 to 3 were online, while No. 4 was shut down for a regular inspection. There were core meltdowns in all three of the active reactors, with the fuel mixing with material from the surrounding structure as it melted and turned into “fuel debris.” Later, the No. 4 reactor building, connected to the No. 3 building by plumbing, was blown apart by a hydrogen explosion.
To complicate matters further, the reactor buildings had fuel storage pools each containing between 392 and 1,534 nuclear fuel rods. However, the plant workers managed to keep the rods cool, averting a major secondary disaster.
On my visit, the No. 3 reactor building is encased in what looks like a Baumkuchen layer cake stood upright. Inside, operations are underway to remove the fuel rods from the 12-meter-deep storage pool.
“There’s a newly installed crane in there to take the fuel out,” said our guide Masayuki Ueda, who is a manager at the Fukushima Daiichi decommissioning unit of the plant’s operator, Tokyo Electric Power Company Holdings (TEPCO).
The hydrogen explosion choked the pool and surrounding area with debris, including fragments of the roof and bits of nearby machinery. Even after the clearing of this debris, equipment and other problems delayed the fuel removal operation by more than four years. The process finally got underway in April 2019. The special crane lifts the some 300-kilogram rods out of the pool one at a time, and they are then taken to a pool in a separate building. Of the 566 rods, 366 had been removed as of Sept. 11, 2020. Due to the high radiation in the building itself, the crane is operated remotely from a control facility about 500 meters away.
The hardest part of the task is yet to come; the handles on 16 of the rods were warped by falling debris, and can’t be extracted by the crane as they are. TEPCO is apparently working on a “grabbing tool” for the crane to lift out the damaged rods, among other methods, in hopes to finish the removal project by March 2021.
We get back on the microbus and head down the hill to a spot where we can look up at the No. 4 reactor building. Here, too, we can see the machinery for the so-called underground ice wall surrounding the No. 1-4 reactors.
Groundwater from the mountains flows relentlessly beneath the power station. The walls in the basement levels of the reactor buildings were cracked in the March 2011 quake, letting in the groundwater and rainwater that has come into contact with the nuclear fuel debris, contaminating it. The “ice wall,” which TEPCO began making in May 2013, is TEPCO’s attempt to control the problem.
The wall is made up of some 1,500 pipes sunk 30 meters into the ground, creating a subterranean perimeter about 1.5 kilometers long around the reactor buildings. Liquid cooled to minus 30 degrees Celsius is then run through the pipes, freezing the soil around them. The Japanese treasury spent about 34.5 billion yen (about $330.7 million) to make the wall, and the electricity and other maintenance to keep it going costs hundreds of millions of yen per year. These latter outlays are passed on to consumers in their power bills.
Previously, the stricken plant produced up to 600 metric tons of contaminated water per day. However, thanks to pumping up groundwater on the landward side of the plant and other measures, that was down to 160 tons per day in April through July this year. Under the plant decommissioning plan, TEPCO and the Japanese government intend to reduce that to 150 tons per day by the end of 2020, and 100 tons by 2025. TEPCO has said that, with work on new roofs over the reactor buildings proceeding, it believes it can meet the 150 ton target this year.
Meanwhile, with radiation levels around the reactor buildings gradually declining, the Nuclear Regulation Authority (NRA) believes it is the moment to consider going into the basement levels to patch the cracks in the walls. NRA Chairman Toyoshi Fuketa has said that “it’s about time to start discussing when to halt” the ice wall operation.
There are experts who doubt the efficacy of the ice wall. In 2018, TEPCO estimated the wall alone was preventing 95 tons of contaminated water from being generated per day. However, Hideyuki Ban, co-director of the nonprofit organization Citizens’ Nuclear Information Center, told the Mainichi Shimbun, “There needs to be an inquiry into whether the ice wall was ever really necessary.”
Parts of the Fukushima Daiichi decommissioning plan have been delayed repeatedly since its release in December 2011. At that time, the plan stated it would take 30-40 years to complete the project. However, after seeing the power station up close, I find it hard to imagine this.
(Japanese original by Suzuko Araki, Science and Environment News Department)
https://mainichi.jp/english/articles/20200921/p2a/00m/0na/018000c
Robot to use brush to retrieve melted fuel at Fukushima plant
The robotic arm to be used for collecting melted fuel at the No. 2 reactor of the Fukushima No. 1 nuclear power plant (Provided by the International Research Institute for Nuclear Decommissioning)
A vacuum vessel to collect powdered nuclear debris (Provided by the International Research Institute for Nuclear Decommissioning)
July 27, 2020
FUKUSHIMA–A robotic arm under development in Britain will use a brush and vacuum vessel on its end to collect melted fuel in a step toward retrieving debris at the crippled Fukushima No. 1 nuclear power plant.
Details of the device, which will start collecting debris inside the No. 2 reactor on a trial basis next year, were announced on July 2.
The government and plant operator Tokyo Electric Power Co. plan to retrieve melted fuel at the No. 2 reactor ahead of two other reactors because radiation levels are relatively low.
The No. 2 reactor, along with the No. 1 and No. 3 reactors, suffered meltdowns following the Great East Japan Earthquake and tsunami in 2011.
The situation inside the No. 2 reactor is relatively known through past inspections. It has been confirmed that apparent debris in the lower part of its containment vessel can be collected with a robot.
Measuring 22 meters long and weighing 4.6 tons, the robotic arm will be made of high-strength stainless steel so it will not bend when stretched out.
It will be inserted into a closed box connected to a hole made on the side of the containment vessel and remotely operated to prevent radioactive substances from being released.
The arm will attach powdered nuclear debris to its brush and also suck the debris with its vacuum vessel.
Under the plan, debris totaling approximately 1 gram or so will be collected in each of the several rounds of the trial procedure.
An experiment will start in Britain as early as August with the use of a model of the containment vessel.
The robotic arm will be transported to Japan around February for the training of operators at the Japan Atomic Energy Agency’s facility in Naraha, Fukushima Prefecture.
The retrieved fuel will be measured for weight and radiation levels, put in a metal transfer vessel and moved to an analysis center in Ibaraki Prefecture.
In the full-scale retrieval stage, different equipment will be used.
Melted fuel to be removed is estimated to record a radiation reading of 6 millisieverts per hour even at distances of 20 centimeters from it.
That means the annual dose limit for ordinary individuals of 1 millisievert will be reached in 10 minutes.
Training is expected to reduce the time required for workers to put debris into the transfer vessel near the fuel.
Other measures to lessen workers’ doses will be taken, such as introducing panels to block radiation.
Experts propose two methods to scrap Daiichi plant
July 26, 2020
Japanese atomic energy experts have proposed two ways to decommission the crippled Fukushima Daiichi nuclear power plant.
The Atomic Energy Society of Japan floated the two methods in a report.
One proposal is to dismantle and remove all parts of the reactor buildings and leave the site vacant. The other is to dismantle and remove parts of the reactor buildings that are above ground and leave behind the underground structures.
The experts say each method has been studied in the United States and European countries.
They say amounts of radioactive waste to be generated during decommissioning work will vary significantly, depending on when the dismantling of reactor buildings begins — namely, starting to dismantle contaminated buildings soon or waiting a certain period for their radiation levels to drop.
A decommissioning timeline released by the Japanese government and the plant’s operator, Tokyo Electric Power Company, shows the scrapping process will be completed by 2051. But the plan is unclear on how the reactor buildings will be decommissioned.
Miyano Hiroshi, a member of the Atomic Energy Society of Japan, says it will be difficult to draw a conclusion from various arguments on how to decommission the plant. But he adds discussions are important and that he hopes the society’s report will contribute to the debate.
Fukushima decommissioning work to be downsized
April 17, 2020
Tokyo Electric Power Company Holdings, Inc. said Thursday that it is preparing to reduce the number of workers involved in decommissioning the Fukushima No. 1 nuclear power plant, in response to the state of emergency being expanded to all 47 prefectures.
About 3,000 employees and staff from partner companies are currently working at the plant to decommission the reactors and other tasks. The reduction in personnel is a measure to reduce the risk of the coronavirus spreading, however, the decommissioning process may be delayed if there is a prolonged reduction in staff.
TEPCO will maintain operations necessary for the stable management of the plant, including the cooling of melted fuel and nuclear fuel pools and the purification of contaminated water.
https://www.lmtonline.com/news/article/Fukushima-decommissioning-work-to-be-downsized-15207355.php
Japan’s 3/11 Recovery Stalled by Fukushima Decommissioning Delays
March 13, 2020
Delays in dismantling the disaster-stricken nuclear power complex cast doubt on whether recovery goals will move forward according to schedule.
Nine years after a quake-triggered tsunami sparked a triple meltdown at Fukushima Daiichi nuclear power plant, decontamination and decommissioning continues in northeastern Japan. The ultimate goal of removing all debris is expected to take anywhere between 30 to 40 years, but progress has been slower than originally planned. So far just one-fourth of decommission work has been completed, drawing attention to work that has not yet begun.
The Fukushima decommissioning and decontamination draft has been amended five times. While changes published in December offered a specific time frame for the first time, the latest timetable for debris removal has been pushed back five years, citing the need for additional safety precautions. Previously, the process of removing spent fuel was scheduled from 2021 to 2024. But work on reactor two looks more likely to start in 2025 and last until 2027, followed by reactor one work commencing sometime between March 2028 and March 2029.
The powerful tsunami, which reached over 40 meters in some areas, took the lives of 22,167 people. At the same time, the loss of power to the entire Fukushima Daiichi plant caused reactors one, two, and three to overheat, sparking hydrogen explosions and the release of radioactive contaminants. This forced 160,000 survivors to evacuate. Despite evacuation orders being lifted in some of the “difficult to return” areas, many still opt to stay away from their homes nine years later.
The next decommissioning stage sets out the removal of 4,471 spent fuel rods inside the cooling pools of reactors one to six. But the biggest obstacle is finding a way to locate and remove the molten nuclear fuel. With frequent delays, evacuees face a constant sense of uncertainty, tangled in a waiting game to see whether decommissioning work can be completed in 30 years.
Reactor two is seen as the safest and easiest option to start full-scale debris removal since it suffered the least structural damage with only “some fuel” melting through the pressure vessel and accumulating at the bottom of the containment vessel. But with no established method for debris retrieval, attempts to survey the location and distribution of molten nuclear fuel among the rubble requires a lengthy trial and error process. In mid-February 2019 an attempt to probe and collect samples from reactor two failed to find and lift the main nuclear fuel debris, instead lifting portions of pebble-like sediment with the lowest radiation readings from the surface. At this stage there is no way for TEPCO, the company that owns the Fukushima Daiichi plant, to determine where fuel debris lies among the rest of the metal debris. It’s estimated that reactor two alone contains 237 metric tons of debris while reactors one and three contain a combined 880 tons. The complexity of debris removal requires developing specialized technology that does not yet exist.
Also plaguing decommissioning efforts is the battle over how to safely dispose of 1 million tons of contaminated water that were used to cool nuclear fuel. Currently, huge tanks on the premises store the polluted runoff, which could fill 400 Olympic swimming pools, but space is expected to run out by mid-2022.
On average 170 tons of contaminated water is produced to cool fuel in nuclear reactors. Without constant cooling, nuclear fuel risks melting from its own heat in a process called decay heat. With two years needed to prepare a disposal method, time is running out for a final decision.
Government proposals to slowly release contaminated water into the ocean has sparked fierce backlash from locals and the agriculture and fishing industries, who argue traces of radioactive materials such as tritium still found in “treated” water could further harm a region still struggling to restore its international reputation.
Last month, International Atomic Energy Agency (IAEA) Chief Rafael Mariano Grossi visited the Fukushima nuclear power plant where he commended the government’s “dual approach” of decommissioning the plant while revitalizing the local community. Grossi said the IAEA could help provide reassurance to the public that Japan’s plan to release treated water into the ocean meets international standards.
To make matters worse, decommissioning operations have been temporarily suspended due to the spread of coronavirus. Tepco was forced to cancel on-site inspections of reactor one scheduled during March, which would have brought together some 1,800 experts and members of parliament, as well as local residents and student groups.
https://thediplomat.com/2020/03/japans-3-11-recovery-stalled-by-fukushima-decommissioning-delays/
Tepco estimates 44 years to decommission Fukushima No. 2 nuclear plant
They say that the first stage, comprising radiological surveys, will take ten years. The second stage, which will involve clearing the equipment from around the nuclear reactors, will last 12 years. Removal of the reactors (stage 3) and demolition of the reactor buildings (stage 4), will each last 11 years.
But these estimates are useless. The U.S. has been cleaning up Hanford, WA, site of the reactors that made the plutonium in the Alamagordo bomb, and then the Nagasaki bomb, for decades, at an every mounting cost and an ever-receding completion date. Turns out that generating large amounts of high-level nuclear waste turns out to be a bit more challenging to deal with than the techno-optimists ever dreamed. If there’s anyone around with the consciousness to care several hundred years from now, the creation of nuclear waste is going to be a very nasty reminder of how stupid we were.
METI eyes 2031 end to Fukushima No. 1 cleanup
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