Tag Archives: radioactive water Fukushima

A Huge Headache: the Radioactive Water at Fukushima

What to do with the enormous amount of radioactive  water, which grows by around 150 tons a day at Fukushima, is a thorny question, with controversy surrounding a long-standing proposal to discharge it into the sea, after extensive decontamination.  The water comes from several different sources: Some is used for cooling at the plant, which suffered a meltdown after it was hit by a tsunami triggered by a massive earthquake in March 2011.  Groundwater that seeps into the plant daily, along with rainwater, add to the problem.

A thousand, towering tanks have now replaced many of the cherry trees that once dotted the plant’s ground. Each can hold 1,200 tons, and most of them are already full.  “We will build more on the site until the end of 2020, and we think all the tanks will be full by around the summer of 2022,” said Junichi Matsumoto, an official with the unit of plant operator TEPCO in charge of dismantling the site.

TEPCO has been struggling with the problem for years, taking various measures to limit the amount of groundwater entering the site.  There is also an extensive pumping and filtration system, that each day brings up tons of newly contaminated water and filters out as many of the radioactive elements as possible.

The hangar where the decontamination system runs is designated “Zone Y” — a danger zone requiring special protections.  All those entering must wear elaborate protection: a full body suit, three layers of socks, three layers of gloves, a double cap topped by a helmet, a vest with a pocket carrying a dosimeter, a full-face respirator mask and special shoes.  Most of the outfit has to burned after use.

“The machinery filters contain radionuclides, so you have to be very protected here, just like with the buildings where the reactors are,” explained TEPCO risk communicator Katsutoshi Oyama.  TEPCO has been filtering newly contaminated water for years, but much of it needs to go through the process again because early versions of the filtration process did not fully remove some dangerous radioactive elements, including strontium 90.

The current process is more effective, removing or reducing around 60 radionuclides to levels accepted by the International Atomic Energy Agency (IAEA) for water being discharged.  But there is one that remains, which cannot be removed with the current technology: tritium.

Tritium is naturally present in the environment, and has also been discharged in its artificial form into the environment by the nuclear industry around the world.  There is little evidence that it causes harm to humans except in very high concentrations and the IAEA argues that properly filtered Fukushima water could be diluted with seawater and then safely released into the ocean without causing environmental problems.

But those assurances are of little comfort to many in the region, particularly Fukushima’s fishing industry which, like local farmers, has suffered from the outside perception that food from the region is unsafe.

Karyn Nishimura, At Fukushima plant, a million-ton headache: radioactive water, Japan Times, Oct. 7, 2019
 

Where to Go? 1 Million Tons Radioactive Water at Fukushima

In August 2019, Tepco projected that storage of radioactive water at the Fukushima nuclear plant would reach full capacity by around summer 2022 even after the expansion — the first time it has issued such a precise estimate.  According to Tepco, the Fukushima No. 1 plant had 960 massive tanks containing 1.15 million tons of treated water as of July 18, 2019. Water that has touched the highly radioactive melted fuel debris has been cleaned up through water treatment machines and is stored in the tanks, but the high-tech treatment machines are able to remove most radionuclides except tritium. The plant currently sees an increase of contaminated water by 170 tons a day, Tepco says.

Releasing tritium-tainted water into the sea in a controlled manner is common practice at nuclear power plants around the world, and it was generally considered the most viable option as it could be done quickly and would cost the least.  The head of the Nuclear Regulation Authority, Toyoshi Fuketa, has long said that releasing the treated water into the sea is the most reasonable option, but people in Fukushima, especially fishermen, fear it will damage the region’s reputation.

Addressing those concerns, the government panel, launched in November 2016, has been looking for the best option in terms of guarding against reputational damage. Injecting it into the ground, discharging it as steam or hydrogen, or solidification followed by underground burial have all been on the table. Under the current plan, Tepco is set to increase the tank space to store 1.37 million tons of water a total, but estimates show that will only last until summer 2022.  But the more space it creates, the bigger the decommissioning headache becomes.

Excerpts from KAZUAKI NAGAT, Fukushima nuclear plant to run out of tanks to store tritium-laced water in three years, Tepco says, Japan Times, Aug. 9, 2019
BY KAZUAKI NAGATA

A Never-Ending Disaster: radioactive water at Fukushima

A Greenpeace report details how plans to discharge over 1 million tonnes of highly contaminated water into the Pacific Ocean was proposed by a Japanese government task force.  According to Greenpeace.

“The decision not to develop water processing technology that could remove radioactive tritium was motivated by short term cost cutting not protection of the Pacific ocean environment or the health and livelihoods of communities along the Fukushima coast,” said Kazue Suzuki, Energy Campaigner at Greenpeace Japan. “  The report concludes that the water crisis remains unresolved, and will be for the foreseeable future. The only viable option to protect the environment and the communities along the Fukushima coast being long term storage for the contaminated water.

The discharge option for water containing high levels of radioactive tritium was recommended as least cost by the Government’s Tritiated Water Task Force and promoted by Japan’s Nuclear Regulation Authority (NRA). The Task Force concluded in 2016 that “sea discharge would cost 3.4 billion yen (US$30 million) and take seven years and four months to complete. It concluded that this was cheapest and quickest of the five methods.” However, technical proposals for removing tritium were submitted to the same Government Task Force by multiple nuclear companies with estimated costs ranging from US$2-US$20 billion to US$50-US$180 billion depending on the technology used. These were dismissed as not viable but without detailed technical consideration.

TEPCO has claimed since 2013 that its ALPS technology would reduce radioactivity levels “to lower than the permissible level for discharge.” However, in September 2018 TEPCO admitted that the processing of over 800,000 tons of contaminated water in 1000 storage tanks, including strontium, had failed to remove radioactivity to below regulatory limits, including for strontium-90, a bone seeking radionuclide that causes cancer. TEPCO knew of the failure of the technology from 2013. The Greenpeace report details technical problems with the ALPS system.

The Fukushima Daiichi site, due its location, is subject to massive groundwater contamination which TEPCO has also failed to stop. Each week an additional 2-4000 tonnes of contaminated water is added to the storage tanks.

Excerpts from Technical failures increase risk of contaminated Fukushima water discharge into Pacific, Greenpeace Press Release,  Jan. 22, 2019

What to Do with Radioactive Pools

More than 60,000 tons of highly radioactive spent nuclear fuel is stored on the shores of four of the five Great Lakes at the Border between United States and Canada — in some cases, mere yards from the waterline — in still-growing stockpiles…It remains on the shorelines because there’s still nowhere else to put it…

The nuclear power industry and its federal regulator, the U.S. Nuclear Regulatory Commission, point to spent nuclear fuel’s safe on-site storage over decades. But the remote possibility of a worst-case scenario release — from a natural disaster, a major accident, or an act of terrorism — could cause unthinkable consequences for the Great Lakes region.   Scientific research has shown a radioactive cloud from a spent fuel pool fire would span hundreds of miles, and force the evacuation of millions of residents in Detroit, Chicago, Cleveland, Toronto or other population centers, depending on where the accident occurred and wind patterns.

For five years, Michigan residents, lawmakers, environmental groups and others around the Midwest have, loudly and nearly unanimously, opposed a planned Canadian underground repository for low-to-medium radioactive waste at Kincardine, Ontario, near the shores of Lake Huron. Meanwhile, spent nuclear fuel, vastly more radioactive, sits not far from the shores of  four Great Lakes — Michigan, Huron, Erie and Ontario — at 15 currently operating or former nuclear power plant sites on the U.S. side. In Michigan, that includes Fermi 2; the Donald C. Cook nuclear plant in Berrien County; the Palisades nuclear plant in Van Buren County, and the former Big Rock Point nuclear plant in Charlevoix County, which ceased operation in 1997 and where now only casks of spent nuclear fuel remain.

Neither the U.S. nor the Canadian government has constructed a central collection site for the spent nuclear fuel. It’s not just a problem in the Great Lakes region — more than 88,000 tons of spent nuclear fuel, an amount that is rising, is stored at 121 U.S. locations across 39 states.

Spent nuclear fuel isn’t only radioactive, it continues to generate heat. It requires storage in pools with circulating water for typically five years before it can be moved into so-called dry-cask storage — concrete-and-steel obelisks where spent fuel rods receive continued cooling by circulating air.In practice, however, because of the high costs associated with transferring waste from wet pools to dry casks, nuclear plants have kept decades worth of spent fuel in wet storage. Plant officials instead “re-rack” the pools, reconfiguring them to add more and more spent fuel, well beyond the capacities for which the pools were originally designed.

Only in recent years have nuclear plants stepped up the transition to dry cask storage because there’s no room left in the wet pools. Still, about two-thirds of on-site spent nuclear fuel remains in wet pools in the U.S….That’s a safety concern, critics contend. A catastrophe or act of terrorism that drains a spent fuel pool could cause rising temperatures that could eventually cause zirconium cladding — special brackets that hold the spent fuel rods in bundles — to catch fire.  Such a disaster could be worse than a meltdown in a nuclear reactor, as spent nuclear fuel is typically stored with nowhere near the fortified containment of a reactor core.

At Fukushima…what almost happened — at the plant’s Unit 4 spent-fuel pool that gives nuclear watchdogs nightmares.  A hydrogen explosion four days into the disaster left the building housing the Unit 4 spent-fuel pool in ruins. The pool was seven stories up in a crumbling, inaccessible building.  It “was so radioactive, you couldn’t put people up there,” von Hippel said. “For about a month after Fukushima, people didn’t know how much water was in the pool. They were shooting water up there haphazardly with a hose, trying to drop it by helicopter.”  Two weeks after the earthquake and tsunami, the Japanese Atomic Energy Commission secretly conducted a worst-case scenario study of the ongoing disaster. The biggest fear that emerged: that a self-sustaining fire would start in the Unit 4 spent fuel pool, spreading to the nearby, damaged reactors. That, they found, would release radiation requiring evacuations as far away as 150 miles, to the outskirts of Tokyo and its more than 13.4 million residents. “That was the devil’s scenario that was on my mind,” Chief Cabinet Secretary Yukio Edano said during a special commission’s 2014 investigation of the accident.“Common sense dictated that, if that came to pass, then it was the end of Tokyo.”   What kept the spent fuel rods covered with water in Unit 4 was a miraculous twist of fate: The explosion had jarred open a gate that typically separated the Unit 4 spent fuel pool from an adjacent reactor pool.  “Leakage through the gate seals was essential for keeping the fuel in the Unit 4 pool covered with water,” a 2016 report on the Fukushima accident by the U.S. National Academies of Sciences, Engineering and Medicine concluded. “Had there been no water in the reactor well, there could well have been severe damage to the stored fuel and substantial releases of radioactive material to the environment.”

The U.S. nuclear industry sees Fukushima differently — in some ways as a success story.  “At Fukushima, you not only had a tsunami, you blew up the buildings … and you still did not drain the pool,” said Rod McCullum, senior director for fuel and decommissioning at the Nuclear Energy Institute, the trade association for nuclear utilities in the U.S.  “Those pools and those casks withstood explosions and earthquakes and tsunamis, all on the same day.”  A scenario where a fire can occur by the draining of water from a spent-fuel pool “has never been demonstrated,” McCullum said. He noted safety measures added in the U.S. since Fukushima include the ability to provide extra pumps and water supplies, in minutes or hours, should a spent fuel pool become breached and lose water — even if the disaster required that the resources be brought in by air from farther away….

Because nuclear power is much more widely used in Canada — the province of Ontario alone has 20 nuclear reactors at three plants — it also generates much more nuclear waste.  In Ontario, nearly 52,000 tons of spent nuclear fuel is stored on-site at nuclear plants along Lakes Huron and Ontario.“There’s a huge amount of high-level, radioactive waste stored right along the water,” said Edwards, the president of the nonprofit Canadian Coalition for Nuclear Responsibility  Like the U.S., Canada is seeking a long-term storage solution that will involve a central underground repository. Unlike the U.S., the Canadian government is seeking willing hosts, promising jobs and economic activity. …Even if a central repository is one day approved, another complication arises — how to get two generations of the most dangerous industrial waste man has ever created from sites all over the country to one point….

Germany, in the 1980s, tried using an abandoned salt and potash mine to store barrels of nuclear waste over 30 years, the Asse II mine.  It’s now prompting a cleanup that may take 30 years and cost nearly $12 billion U.S. dollars. The government has disputed the contention of workers at the mine that they were exposed to excessive levels of radiation, causing an unusual number of cancers….Nuclear power is projected to drop as a percentage of the world’s power generation mix from 10 percent in 2017 to just 5.6 percent by 2050, a report issued by the International Atomic Energy Agency this summer found…

If central repository solutions aren’t found, within years, the re-licensing of some early dry-cask storage facilities will come into play, as they meet a lifespan they were never expected to reach. “The age of nuclear power is winding down, but the age of nuclear waste is just beginning,” Edwards said.

Excerpts from Keith Matheny, 60,000 tons of dangerous radioactive waste sits on Great Lakes shores, Detroit Free Press, Oct. 19, 2018

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

Melted Nuclear Fuel at Fukushima

jA 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

Nuclear Waste at Fukushima: total amount

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