Tag Archives: radioactive water Fukushima

Fukushima in 2018: Radioactive Mud

Radioactive cesium from the crippled Fukushima No. 1 nuclear power plant continued to flow into Tokyo Bay for five years after the disaster unfolded in March 2011, according to a researcher.  Hideo Yamazaki, a former professor of environmental analysis at Kindai University, led the study on hazardous materials that spewed from the nuclear plant after it was hit by the Great East Japan Earthquake and tsunami on March 11, 2011.

Five months after disaster caused the triple meltdown at the plant, Yamazaki detected 20,100 becquerels of cesium per square meter in mud collected at the mouth of the Kyu-Edogawa river, which empties into Tokyo Bay.  In July 2016, the study team detected a maximum 104,000 becquerels of cesium per square meter from mud collected in the same area of the bay, Yamazaki said.

He said cesium released in the early stages of the Fukushima disaster remained on the ground upstream of the river, such as in Chiba Prefecture. The radioactive substances were eventually washed into the river and carried to Tokyo Bay, where they accumulated in the mud, he said.

On a per kilogram basis, the maximum level of radioactivity of cesium detected in mud that was dried in the July 2016 study was 350 becquerels.  The government says soil with 8,000 becquerels or lower of radioactive cesium per kilogram can be used in road construction and other purposes.  The amount of radioactive cesium in fish in Tokyo remains lower than 100 becquerels per kilogram, the national safety standard for consumption.

Excerpts from  NOBUTARO KAJI,  Cesium from Fukushima flowed to Tokyo Bay for 5 years, June 7, 2018

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Robots to the Rescue: Fukushima Japan

jorange on equipment probably melted nuclear fuel

A robot operating deep inside a failed reactor at the stricken Fukushima nuclear plant north of Tokyo has revealed what appears to be stalactites of melted nuclear fuel, the plant's operator has said.
The discovery is considered a key development in the decommissioning process of the plant, which suffered a catastrophic meltdown in 2011 after a huge tsunami swamped the facility.
Operating remotely within submerged parts of the Fukushima Daiichi plant's Unit 3 reactor, the robot sent back 16 hours worth of images of massive, lava-like fuel deposits on the floor of the pedestal, a part of the reactor that sits underneath and supports the core....

The discovery is key to determining how to further advance the cleanup of the plant, a process that is expected to take decades.  "This was the first time that we could confirm the status inside the pedestal," TEPCO spokesperson Maki Murayama said. "This is a big step towards the decommission process."..

Having entered the stricken Pressure Containment Vessel (PCV) through a pipe designed to prevent the escape of radioactive gas, the robot descended into the cooling water which accumulated following the accident.
The device was equipped with thrusters to navigate through the water, and featured front and rear cameras.  The small "radiation-hardened, screw-driven" submersible robot was designed to fit through the narrow, 14-centimeter (5.5-inch) diameter entrance of the pipe, according to the Tokyo-based International Research Institute for Nuclear Decommissioning (IRID), which developed the device alongside technology company Toshiba.

As the robot navigates through the ruined reactor, melted equipment and the fuel deposits can be seen.

The mission was launched after previous photographic inspection of the Unit 3 reactor suggested that, "during the accident, fuel assemblies melted from the excess heat, dropping from their original position down to the pedestal area," according to a statement released by TEPCO.

Excerpt from Euan McKirdy and Yoko Wakatsuki, Fukushima robot reveals first sign of melted fuel in submerged reactor, CNN, July 24, 2017

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Not for the Fainthearted: total nuclear waste at Fukushima

Rubble Japan earthquake. image from wikipedia

Each form of waste at the Fukushima Daiichi Nuclear Power Station, where three reactors melted down after an earthquake and a tsunami on March 11, 2011, presents its own challenges.

400 Tons of Contaminated Water Per Day
The Tokyo Electric Power Company is pumping water nonstop through the three reactors to cool melted fuel that remains too hot and radioactive to remove. About 400 tons of water pass through the reactors every day, including groundwater that seeps in. The water picks up radiation in the reactors and then is diverted into a decontamination facility.  But the decontamination filters cannot remove all the radioactive material. So for now, all this water is being stored in 1,000 gray, blue and white tanks on the grounds. The tanks already hold 962,000 tons of contaminated water, and Tokyo Electric is installing more tanks. It is also trying to slow the flow of groundwater through the reactors by building an underground ice wall.

Within a few years, though, and no one is sure exactly when, the plant may run out of room to store the contaminated water. “We cannot continue to build tanks forever,” said Shigenori Hata, an official at the Ministry of Economy, Trade and Industry.  The authorities are debating whether it might be acceptable, given the relatively low radioactive levels in the water, to dilute the contaminated water and then dump it into the ocean. But local fishermen are vehemently opposed. Many people still do not trust Tokyo Electric because of its bungled response to the disaster, the worst nuclear accident since Chernobyl.

3,519 Containers of Radioactive Sludge
The process of decontaminating the water leaves radioactive sludge trapped in filters, which are being held in thousands of containers of different sizes.Tokyo Electric says it cannot quantify the amount of radioactive sludge being generated. But it says it is experimenting with what to do with it, including mixing it with cement or iron. Then it will have to decide how to store it.

64,700 Cubic Meters of Discarded Protective Clothing
The estimated 6,000 cleanup workers at the site put on new protective gear every day. These hazmat suits, face masks, rubber gloves and shoe coverings are thrown out at the end of each shift. The clothing is compressed and stored in 1,000 steel boxes stacked around the site.To date, more than 64,700 cubic meters of gear has been discarded, the equivalent of 17 million one-gallon containers. Tokyo Electric says it will eventually incinerate all this contaminated clothing to reduce the space needed to store it.

Branches and Logs From 220 Acres of Deforested Land
The plant’s grounds were once dotted with trees, and a portion was even designated as a bird sanctuary. But workers have cleared about 220 acres of trees since the meltdown spewed radiation over them.Now, piles of branches and tree trunks are stacked all over the site. Officials say there are about 80,000 cubic meters of this waste, and all of it will have to be incinerated and stored someday.

200,400 Cubic Meters of Radioactive Rubble
Explosions during the meltdown filled the reactors with rubble. Workers and robots are slowly and carefully trying to remove this tangled mass of crushed concrete, pipes, hoses and metal.  Tokyo Electric estimates that more than 200,400 cubic meters of rubble — all of it radioactive — have been removed so far and stored in custom-made steel boxes. That is the equivalent of about 3,000 standard 40-foot shipping containers.

3.5 Billion Gallons of Soil

Thousands of plastic garbage bags sit in neat rows in the fields and abandoned towns surrounding the Fukushima plant. They contain soil that was scraped from land that was exposed to radiation in the days after the accident.  Japan’s Ministry of the Environment estimates that it has bagged 3.5 billion gallons of soil, and plans to collect much more. It will eventually incinerate some of the soil, but that will only reduce the volume of the radioactive waste, not eliminate it.  The ministry has already begun building a massive, interim storage facility in Fukushima prefecture and negotiating with 2,360 landowners for the thousands of acres needed to complete it. And that is not even a long-term solution: The government says that after 30 years it will need another site — or sites — to store radioactive waste.

1,573 Nuclear Fuel Rods
The ultimate goal of the cleanup is to cool and, if possible, remove the uranium and plutonium fuel that was inside the three reactors at the time of the disaster.  Hundreds of spent fuel rods are in cooling pools inside the reactors, and the company hopes to have cleared away enough rubble to begin removing them next year. The much bigger challenge will be removing the fuel that was in use in the reactor core at the time of the meltdown.

The condition and location of this molten fuel debris are still largely unknown. In one reactor where a robot was sent in January, much of the melted fuel is believed to have burned through the bottom of the inner reactor vessel and burrowed into the thick concrete foundation of the containment structure.  The plan is to completely seal the containment vessels, fill them with water and use robots to find and remove the molten fuel debris. But the rubble, the lethal levels of radiation and the risk of letting radiation escape make this an exceedingly difficult task.

In January 2017, the robot sent into one of the reactors discovered radiation levels high enough to kill a person in less than a minute. Another had to be abandoned last month after debris blocked its path and radiation disabled it.

Tokyo Electric hopes to begin removing fuel debris from the reactor cores in 2021. The entire effort could take decades. Some say the radioactive material may prove impossible to remove safely and have suggested leaving it and entombing Fukushima under a concrete and steel sarcophagus like the one used at Chernobyl.

But the Japanese government and Tokyo Electric say they are committed to removing all the waste and cleaning the site, estimated at a cost of $188.6 billion.

Excerpts from MOTOKO RICH, Struggling With Japan’s Nuclear Waste, Six Years After Disaster, Mar. 11, 2017

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Nothing Outlasts the Fukushima Disaster: it keeps going and going….

energizer

As Prime Minister Shinzo Abe moves to reopen Japanese nuclear plants that were all shut after the disaster on March 11, 2011, a distrustful public is pushing back. A court on March 9, 2016ordered Kansai Electric Power Co. to halt two of the four reactors that have been restarted, saying the utility had failed to show the public they were safe. The utility called the ruling “unacceptable” and said it would appeal....However, near the ruined Fukushima reactors......Growing swaths of land are covered with black bags full of slightly radioactive soil.

The hardest parts of the cleanup haven’t even begun. Tepco, as Tokyo Electric is known, has yet to draw up plans for removing highly radioactive nuclear fuel that melted through steel containment vessels and now sits at the bottom of three Fukushima reactors.The company estimates that the nearly $20 billion job of decommissioning the plant could take another three or four decades. That is not counting damages and cleanup costs expected to reach some $100 billion or more, including about $50 billion paid to evacuees. Legal wrangling over the disaster continues. In February 2016, three former Tepco executives were charged with professional negligence.

Tepco also is working to reduce a total 400 tons of rain and groundwater that breach the plant’s defenses daily, becoming contaminated and requiring treatment and storage. But a wall of frozen earth meant to reduce the flow has run into resistance from regulators.On large parts of the site, workers can now walk around without full-face shields or hazmat suits, using simple surgical masks for protection.Fukushima was once a prized post for elite engineers and technicians in Japan’s nuclear heyday. Now, unskilled laborers make up the bulk of a workforce of about 6,000 workers, down from a peak of 7,450 in 2014. “There’s a constant stream of people who can’t find work elsewhere,” said Hiroyuki Watanabe, a Communist city councilman in Iwaki, about 30 miles away. “They drift and collect in Fukushima.”...

Looking ahead, the biggest issue remains the reactors. No one knows exactly where the molten nuclear debris sits or how to clean it. Humans couldn’t survive a journey inside the containment vessels, so Tepco hopes to use robots guided by computer simulations and video images. But two attempts had to be abandoned after the robots got tripped up on rubble.“The nature of debris may depend on when the nuclear fuel and concrete reacted,” said Pascal Piluso, an official of France’s Alternative Energies and Atomic Energy Commission. “We are talking about extremely varied and complex debris.”....A government panel recently questioned Tepco’s ability to tackle the daunting task of decommissioning while seeking profit for its shareholders. The disaster nearly pushed the company to bankruptcy, prompting the government to buoy it with ¥1 trillion ($9 billion  (really????) in public money and pledge government grants and guarantees to help Tepco compensate victims.”...

Excerpts  from Fukushima Still Rattles Japan, Five Years After Nuclear Disaster, Wall Street Journal, Mar. 8, 2016

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2015 Unsolved Conundrum: Fukushima Nuclear Waste

Fukushima Nuclear Disaster, March 2011 to ?

Nuclear hand, logo of the anti-nuclear movement. image from wikipedia

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How to Release Radioactive Waste to the Pacific Ocean: IAEA on Fukushima

storage tanks for nuclear water Fukushima

From the Report of the IAEA regarding  Radioactive Water at Fukushima:  While the IAEA is recognizing the usefulness of the large number of water treatment systems deployed by TEPCO for decontaminating and thereby ensuring highly radioactive water accumulated at the site is not inappropriately released to the environment including the adjacent Pacific Ocean, the IAEA team also notes that currently not all of these systems are operating to their full design capacity and performance. ....The IAEA team is of the opinion that the present plan to store the treated contaminated water containing tritium in above ground tanks, with a capacity of 800,000 m 3 , is at best a temporary measure while a more sustainable solution is needed. Therefore the present IAEA team reiterates the advisory point of the previous decommissioning mission: “The IAEA team believes it is necessary to find a sustainable solution to the problem of managing contaminated water at TEPCO’s Fukushima Daiichi NPS. This would require considering all options, including the possible resumption of controlled discharges to the sea. TEPCO is advised to perform an assessment of the potential radiological impact to the population and the environment arising from the release of water containing tritium and any other residual radionuclides to the sea in order to evaluate the radiological significance and to have a good scientific basis for taking decisions. It is clear that final decision making will require engaging all stakeholders, including TEPCO, the NRA, the National Government, Fukushima Prefecture Government, local communities and others”.

From the IAEA report Released on May 14, 2015 MISSION REPORT IAEA INTERNATIONAL PEER REVIEW MISSION ON MID-AND-LONG-TERM ROADMAP TOWARDS THE DECOMMISSIONING OF TEPCO’S FUKUSHIMA DAIICHI NUCLEAR POWER STATION UNITS 1-4 (Third Mission) Tokyo and Fukushima Prefecture, Japan 9 – 17 February 2015

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Controlling Radioactive Water: Leaks of Fukushima to the Pacific Ocean

pacific

Sensors at the Fukushima nuclear plant have detected a fresh leak of highly radioactive water to the sea, the plant's operator announced on Feb. 22, 2015, highlighting difficulties in decommissioning the plant.  Tokyo Electric Power Co (Tepco) said the sensors, which were rigged to a gutter that pours rain and ground water at the Fukushima Daiichi plant to a nearby bay, detected contamination levels up to 70 times greater than the already-high radioactive status seen at the plant campus.  Tepco said its inspections of tanks storing nuclear waste water did not find any additional abnormalities, but it shut the gutter to prevent radioactive water from going into the Pacific Ocean.
Fresh leak detected at Fukushima N-plant, Agency France, Presse, Feb. 23, 2015

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The Seven Samurai and 70 000 Nuclear Refugees: Fukushima

Fukushima construction of emergency  pumps

The first three of Fukushima Dai-ichi’s six reactors melted down in March 2011 and the fourth was damaged. TEPCO’s early guess was that decommissioning would take 30-40 years. That is certainly optimistic.

Engineers are grappling with problems with little precedent. Akira Ono, the plant manager, says cameras have begun peeking into the first reactor to check the state of 100 tonnes of molten fuel. A robot needs to be developed to extract the fuel. Last October the utility pushed back the start of this removal work by five years, to 2025. Dale Klein, a former chairman of America’s Nuclear Regulatory Commission, says that the schedule for decommissioning the plant is pure supposition until engineers figure out how to remove all the fuel.
One victory for engineers is with reactor four. Late last year the last of 1,535 highly toxic fuel rods was plucked from the spent-fuel pool a year ahead of schedule. The fear was that the complex could not withstand another strong earthquake.  Solutions create new problems. Water is pumped in to keep melted uranium at the bottom of reactors one, two and three from overheating. A purification system, known on-site as the “seven samurai”, is struggling to keep up with the flow of contaminated water being produced—370,000 tonnes and rising is stored in vast tanks. Even when the worst nuclides are filtered out, TEPCO will face huge opposition with plans to dump the water into the Pacific.

Then there is the ice wall. TEPCO is attempting to freeze the ground in a huge ring around the four damaged reactors to prevent toxins from reaching the groundwater and flowing into the sea. Workers have dug vast holes and filled them with coolant. In May they will begin refrigerating the coolant to up to -40ºC. Whether the wall can take another big earthquake or work in the baking summer is not proven. The cost for this so far: ¥32 billion ($272m).

Meanwhile, a lower-tech clean-up is taking place beyond the Dai-ichi site over a big swathe of Fukushima’s rolling countryside. Armed with Geiger counters, men in mechanical diggers or with shovels are skimming off contaminated soil. Once the land is clean, at least some residents have a hope of returning home—71,000 nuclear refugees remain in temporary housing. But it could take years.

The price tag for the whole clean-up is as uncertain as its duration. For one, decontamination costs depend on lowering annual radiation to 1 millisievert, a goal now widely seen as unrealistic, says Tatsujiro Suzuki, a former vice-chairman of the Japan Atomic Energy Commission.

TEPCO says decommissioning Dai-ichi’s four damaged reactors will cost ¥980 billion, but that does not include the clean-up, fuel storage or compensation. On a broader reckoning, the Japan Centre for Economic Research, a private research institute, puts the bill over the next decade at ¥5.7 trillion-¥20 trillion, but that still excludes compensation to the fisheries and farming industries. A still broader calculation by the same institute puts the entire cost of the disaster at ¥40 trillion-¥50 trillion. Thanks to government bail-outs, the company that so mismanaged Fukushima Dai-ichi carries on. It even says it will make a profit this year.

Fukushima Daiichi: Mission impossible, Economist, Feb.7, 2014, at 36

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Three Companies to Grapple with Fukushima Mess

tritium

The [Japanese] government picked three overseas companies to participate in a subsidized project to determine the best available technology for separating radioactive tritium from the toxic water building up at the Fukushima No. 1 nuclear plant.  Tokyo Electric Power Co. is currently test-running a system it says is capable of removing 62 types of radioactive substances from the contaminated water, but not tritium.  Thus tritium-laced water is expected to accumulate at the plant in the absence of any method to remove the isotope.

The three firms chosen from 29 applicants are U.S. firm Kurion Inc., which offers technologies to treat nuclear and hazardous waste; GE Hitachi Nuclear Energy Canada Inc., a joint venture of Hitachi Ltd. and U.S. firm General Electric Co.; and Federal State Unitary Enterprise RosRAO, a Russian radioactive waste management firm.

The government will provide up to ¥1 billion for each examination of the technologies and running costs, and consider whether any of them can be applied to treat the water at Fukushima No. 1, the industry ministry said.  The three companies are to conclude their experiments by the end of March 2016, a ministry official said.  The official cautioned there is no guarantee that any of the technologies will be put to practical use.

Three firms picked to help tackle toxic water at Fukushima No. 1, Japan Times, Aug. 26, 2014

In January 2014 it was made public that a total of 875 terabecquerels (2.45 g) of tritium are on the site of Fukushima Daiichi,and the amount of tritium contained in the contaminated water is increasing by approximately 230 terabecquerel (0.64 g) per year. According to a report by Tepco "Tritium could be separated theoretically, but there is no practical separation technology on an industrial scale."  See Wikipedia

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