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Cocooning the past. Plutonium reactor in Eastern Washington encased in steel to protect the river

The K-East nuclear reactors stands stripped bare and decommissioned near the banks of the Columbia River at the Hanford Nuclear Reservation. Hanford’s “sister reactors”, the K-East and the K-West Reactors, were built side-by-side in the early 1950’s. K-East was the eighth. The two reactors both ran for more than fifteen years before being shut down in 1970 and 1971. The Hanford Nuclear Reservation was constructed as part of The Manhattan Project.

Beginning in 1943, the site was used to produce plutonium for the “Fat Man” bomb that was dropped on Nagasaki, Japan that brought an end to World War II. After a short lull, plutonium production was ramped up in 1947 and continued until 1987 when the last reactor ceased operation. Weapons production processes left solid and liquid radioactive wastes that posed a risk to the local environment including the Columbia River. In 1989, the U. S. Department of Energy (DOE), Environmental Protection Agency (EPA), and Washington State Department of Ecology began clean up of Hanford.

Tri City Herald, BY ANNETTE CARY OCTOBER 26, 2022

A reactor at the Hanford site has been “cocooned” for the first time in a decade. The addition of a new steel enclosure for the 1950s reactor is an “iconic change to the landscape” at the nuclear reservation along the Columbia River and helps protect the river, said John Eschenberg, president of Department of Energy contractor Central Plateau Cleanup Co. Eight of the nine plutonium production reactors that line the Columbia River in Eastern Washington are being put in temporary storage for up to 75 years to allow radiation in their core to decay to lower levels before a permanent solution is attempted.

The newest cocoon, with its straight sides and sloping roof, creates a new look for the Hanford skyline, much different from the other cocooned reactors which retain much of the original shape of the reactors. Completion of the cocoon over the K East Reactor leaves just one more to be cocooned at Hanford.

The K East Reactor was number seven, with its twin, the K West Reactor, not expected to be cocooned until about 2030. The ninth reactor, B Reactor, will remain unsealed and open for tours as part of the Manhattan Project Historical National Park. From World War II through the Cold War Hanford produced about two-thirds of the plutonium for the nation’s nuclear weapons program.

Production stopped with the end of the Cold War, and now the nation is spending for than $2.5 billion a year on environmental cleanup work at the 580-square-mile nuclear reservation by Richland.

For the K East Reactor a new form of temporary storage was used that Hanford officials expect to save money and better protect the reactor as it waits for final disposition in the coming decades.

No decision has been made on the final plan for disposing of Hanford’s defunct reactors, but allowing radiation to decay will provide safer conditions for workers then. In Hanford’s traditional cocooning, reactors are torn down to little more than their radioactive core, any openings are sealed up and the roof is replaced. NEW TYPE OF REACTOR COCOON But for the K East Reactor, a new, free-standing structure 123 feet tall and nearly 154 feet wide was built over the reactor for the first time.

The new method of cocooning should better protect the nearly 80-year-old concrete of the reactor from wind, sand and cycles of freezing and thawing that take a toll on Hanford structures, Eschenberg said. It also should reduce the need for roof maintenance.

Although the new steel enclosure was designed to last 75 years, Eschenberg said final disposition of the reactor is not likely to be done that late. No decision has been made on what final disposition will be.

Every five years Hanford workers will enter the reactor to check on its condition. New lighting installed within the reactor and between the steel cocoon and the original reactor walls will help make that easier as workers check the condition of the concrete, look for any rodents or other animals, and make sure there has not been any intrusion of water.

………………………………………………… DECADES OF CLEANUP BEFORE COCOONING The initial work at the K East Reactor to allow cocooning of the reactor, which operated from 1955 to 1971, started decades ago. The water basins at the K West and K East reactors were used to store uranium fuel irradiated at N Reactor but not processed to remove plutonium at the end of the Cold War.

The fuel was removed from the two basins, each holding 1.2 million gallons of water, in a 10-year project completed in 2004.

But the fuel had decayed after decades underwater, leaving a highly radioactive sludge that was not all contained and shipped to dry storage at Hanford’s T Plant until 2019, after first being consolidated at the K West Reactor.

Water next was drained from the K East Reactor basin, which is work not yet done at the K West Reactor. The dry K East Reactor basin was filled with grout that was then cut into pieces and removed, requiring the site to be backfilled.

A village of support structures had to be demolished, including the reactor’s powerhouse and fuel oil storage. In addition, sediment basins used for reactor cooling water had to be cleaned up.

Tens of thousands of tons of contaminated soil and debris, including underground piping and utilities, were removed, with most of it taken to a huge lined landfill in central Hanford for disposal.

Most of the soil contamination was from chromium, which was used as a corrosion inhibitor in reactor cooling water. Groundwater contaminated with chromium is pumped up, cleaned and returned to the ground before it enters the Columbia River, about 300 yards from the K Reactors. …………………………… more https://www.tri-cityherald.com/news/local/hanford/article267895437.html

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October 26, 2022 - Posted by | decommission reactor, USA

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