Tag Archives: spent fuel pools

Institutions Go Way But Not Nuclear Waste

The Trump administration  is asking Congress for money to resume work on the Yucca Mountain nulcear waste storage in Nevada.  But that may not end local opposition or a longstanding political stalemate. And in the meantime, nuclear plants are running out of room to store spent fuel….As the waste piles up, private companies are stepping in with their own solutions for the nation’s radioactive spent fuel. One is proposing a temporary storage site in New Mexico, and another is seeking a license for a site in Texas.

Most experts agree that what’s needed is a permanent site, like Yucca Mountain, that doesn’t require humans to manage it.  “Institutions go away,” says Edwin Lyman, acting director of the Nuclear Safety Project at the Union of Concerned Scientists. “There’s no guarantee the owner will still be around for the duration of time when that waste remains dangerous, which is tens or hundreds of thousands of years.”

A California company says it has a viable plan for permanent storage. Deep Isolation wants to store spent fuel in holes drilled at least 1,000 feet underground in stable rock formations. The company says the waste would be separate from groundwater and in a place where it can’t hurt people.  “I like to imagine having a playground at the top of the Deep Isolation bore hole where my kids and I can go play,” says CEO Elizabeth Muller.  In November 2018, Muller’s company conducted a test north of Austin, Texas. Crews lowered an 80-pound canister into a drilled hole. It was a simulation, so no radioactive substances were involved. The goal was to determine whether they could also retrieve the canister.  The test was successful, and that’s important. Regulators require retrieval, because new technology could develop to better deal with the spent fuel. And the public is less likely to accept disposal programs that can’t be reversed, according to the International Atomic Energy Agency.

Proving the waste can be retrieved may be the easy part. The bigger challenge is federal law, which doesn’t allow private companies to permanently store nuclear waste from power plants.  Current law also says all the waste should end up at Yucca Mountain in Nevada. By contrast, Deep Isolation’s technology would store waste at sites around the country, likely near existing nuclear power plants.

Jeff Brady, As Nuclear Waste Piles Up, Private Companies Pitch New Ways To Store It, NPR, Apr. 30, 2019

Never-Ending CleanUp: Fukushima

 The operator of Japan’s wrecked Fukushima nuclear plant completed in April 2019 the removal of the first fuel rods from a cooling pool high up in a badly damaged reactor building, a rare success in the often fraught battle to control the site.  The batch of 22 unused fuel assemblies, which each contain 50-70 of the fuel rods, was transferred by a trailer to a safer storage pool, the last day of a four-day operation, Tokyo Electric Power Co, or Tepco, said in a statement.

The company must carefully pluck more than 1,500 brittle and potentially damaged assemblies from the unstable reactor No.4., the early stages of a decommissioning process following the 2011 earthquake and tsunami that wrecked the site.

Tepco estimates removing the damaged assemblies from reactor No.4 alone will take a year. Some experts say that timeline is ambitious.  Still, it is an urgent operation. They are being stored 18 meters (59 feet) above ground level in a building that has buckled and tilted and could collapse if another quake strikes.  Carefully plucking the damaged fuel assemblies from the reactor building is being seen as a test of Tepco’s ability to move ahead with decommissioning the whole facility – a task likely to cost tens of billions of dollars and take decades.  The removal has to be conducted under water. If the rods are exposed to air or if they break, huge amounts of radioactive gases could be released into the atmosphere. Each assembly weighs around 300 kg (660 pounds) and is 4.5 meters (15 feet) long.  The hazardous removal operation has been likened by Arnie Gundersen, a veteran U.S. nuclear engineer and director of Fairewinds Energy Education, to trying to pull cigarettes from a crushed pack

Exerpts from In Start of Long Operation, Fukushima Removes First Fuel Rods, Reuters, April 2019

Devil’s Idea for Tokyo’s End: Fukushima

By late March 2011… after tsunami struck the Fukushima Daiichi plant—it was far from obvious that the accident was under control and the worst was over. Chief Cabinet Secretary Yukio Edano feared that radioactive material releases from the Fukushima Daiichi plant and its sister plant (Fukushima Daini) located some 12 km south could threaten the entire population of eastern Japan: “That was the devil’s scenario that was on my mind. Common sense dictated that, if that came to pass, then it was the end of Tokyo.”

Prime Minister Naoto Kan asked Dr. Shunsuke Kondo, then-chairman of the Japanese Atomic Energy Commission, to prepare a report on worst-case scenarios from the accidenta .  Dr. Kondo led a 3-day study involving other Japanese experts and submitted his report (Kondo, 2011) to the prime minister on March 25, 2011. The existence of the report was initially kept secret because of the frightening nature of the scenarios it described. An article in the Japan Times quoted a senior government official as saying, “The content [of the report] was so shocking that we decided to treat it as if it didn’t exist.” …

One of the scenarios involved a self-sustaining zirconium cladding fire in the Unit 4 spent fuel pool. Radioactive material releases from the fire were estimated to cause extensive contamination of a 50- to 70-km region around the Fukushima Daiichi plant with hotspots significant enough to require evacuations up to 110 km from the plant. Voluntary evacuations were envisioned out to 200 km because of elevated dose levels. If release from other spent fuel pools occurred, then contamination could extend as far as Tokyo,…There was particular concern that the zirconium cladding fire could produce enough heat to melt the stored fuel, allowing it to flow to the bottom of the pool, melt through the pool liner and concrete bottom, and flow into the reactor building.

Lessons Learned from the Fukushima Daiichi Accident for Spent Fuel Storage: The U.S. nuclear industry and its regulator should give additional attention to improving the ability of plant operators to measure real-time conditions in spent fuel pools and maintain adequate cooling of stored spent fuel during severe accidents and terrorist attacks. These improvements should include hardened and redundant physical surveillance systems (e.g., cameras), radiation monitors, pool temperature monitors, pool water-level monitors, and means to deliver pool makeup water or sprays even when physical access to the pools is limited by facility damage or high radiation levels….

[At nuclear power plants there must be…adequate separation of plant safety and  security systems so that security systems can continue to function independently if safety systems are damaged. In particular, security systems need to have independent, redundant, and protected power sources…]

Excerpts from Lessons Learned from the Fukushima Accident for Improving
Safety and Security of U.S. Nuclear Plants: Phase 2, US National Academies, 2016

Diving into a Nuclear Pool

United Kingdom: Specialist divers have completed their mission to deal with radioactive waste from Sizewell A Site’s nuclear fuel storage ponds, nearly two months ahead. The divers, who are shielded from radiation by the water in the ponds, successfully cut up and ‘size reduced’ all of the 35 waste storage containers left in Sizewell A’s ponds. They also cut up around 100 tonnes of other redundant equipment before removing all the radioactive sludge from the pond floor.

Conventionally, pond clean-out is done using remotely operated equipment to lift the whole radioactive skips  (waste containers) and other pond furniture clear of the water, exposing them to the air, where they are carefully cut and decontaminated. This process is slow with potential radiation dose risks for workers,” Magnox Sites said.  “Using this innovative underwater decommissioning technique, radiation levels for workers were around 20 times less than with conventional techniques of decommissioning the waste items in air,” it added. The diving technique also has a lower environmental impact, is quicker and more efficient and therefore cheaper.  The next phase of work is to take the waste out of the ponds where it will be treated and safely packaged. The ponds are set to be completely emptied and drained by the end of 2019.

The team of 12 nuclear divers was supplied by Underwater Construction UK Ltd. They tackled their first UK ‘nuclear dive’ at the Dungeness A Site in 2016 and arrived on site at Sizewell A in October 2017.

Sizewell A’s two 210 MWe Magnox gas-cooled reactors operated from 1966 until 2006. Defuelling began in 2009, with fuel removed from the reactors placed in the site’s used fuel storage ponds before being packaged in transport containers for shipment to the Sellafield complex for reprocessing. The final flask of fuel was shipped to Sellafield in August 2014. Sizewell A was declared completely fuel free in February 2015.

Excerpts from Divers Complete Radwast work at Sizewell A, World Nuclear News, Aug. 3,  2018

The Nuclear Complex of Sellafield

There is no other site like Sellafield in the world. It is where many major developments in the 20th century nuclear industry were pioneered.

It is home to:

–the Windscale Piles, which were used to create material for weapons

–the world’s first commercial-scale nuclear power station – Calder Hall, opened in 1956

–the world’s first large-scale advanced gas-cooled reactor, opened in 1963

–nuclear fuel storage ponds and waste silos, built in the 1940s and 50s

–nuclear fuel fabrication plants

–nuclear fuel reprocessing plants

–a fleet of nuclear waste storage facilities

Sellafield is a densely packed site of just 6sq km housing thousands of buildings. Many of them store highly hazardous waste. Its oldest facilities were built in great haste during the early years of the Cold War with no plans for how they would be decommissioned.  Record-keeping in the early days was poor by modern standards, meaning much work has had to be carried out to confirm the nature and state of the material kept in these facilities. There is no blueprint for decommissioning Sellafield’s oldest facilities. Staff and contractors had to come up with ground-breaking engineering projects in order to decommission these one-of-a-kind facilities.  And these highly complex projects have to be done on small parcels of land, often just feet away from buildings containing highly hazardous material, with all of the safety constraints this presents.

When an uncertain challenge is combined with highly constrained working conditions and a series of never-done-before projects, the result is a long, complex and costly decommissioning programme.  Huge strides have already been made at Sellafield, but it is fair to say the site will continue to test ingenuity in construction, engineering, nuclear science and project management for decades to come.

-Commissioned for use in 1952, the Pile Fuel Cladding Silo received and safely stored radioactive cladding―pieces of metal tubes—used for uranium fuel rods in some of the UK’s earliest nuclear reactors―first from military projects and later power plants. Other debris was added, and by 1964 the silo was full.  The Pile Fuel Cladding Silo is 69 feet (21 meters) tall and houses six compartments that hold some 4,200 cubic yards (more than 3,200 cubic meters) of intermediate-level waste. The job at hand is safely retrieving the waste and storing it in highly secure concrete containers.

The first of six holes on the silo were cut (August 2017). To remove the waste, a crane will extend through the cut holes, and a grabber will drop down to scoop the waste up.It will be lifted out of the container and into a specially-designed metal box.

Excerpts from  Nuclear Provision: the cost of cleaning up Britain’s historic nuclear sites updated 19 July 2017 

Sellafield decommissioning: Nuclear waste silo opened, BBC, Sept. 5, 2017

SELLAFIELD PILE FUEL CLADDING SILO RETRIEVAL, Bechtel