Hanford Reactor Dome Comes Down
Jan 17, 2011
Hanford reactor dome comes down (w/ gallery)
By Annette Cary, Herald staff writer
RICHLAND — The iconic dome of Hanford's Plutonium Recycle Test Reactor just north of Richland no longer stands.
The 80-foot-high dome was one of the most distinctive and visible Hanford sights, rising over buildings in the 300 Area just north of Richland.
While the nine boxy reactors in north Hanford produced plutonium for the nation's nuclear weapons program, the test reactor with its round dome was built for President Eisenhower's Atoms for Peace initiative. It was used to test alternative fuels for commercial power production.
Saturday the containment dome of the reactor was lifted off, as contractor Washington Closure Hanford got a break in the windy weather to do the work.
"It went as planned," said Gary Snow, deputy director of deactivation and demolition for Washington Closure. "The folks involved did a terrific job of planning it in a safe manner."
Work was under way months ago to remove hazardous materials from the dome and then start cutting it.
The dome was made of carbon steel a little more than a quarter-inch thick and stood on top of concrete and steel circular walls. Workers drilled holes around the perimeter of the base of the dome and then made 42 cuts between the holes to slice off the top.
The cuts were made with a saw attached to a crane that was used within the dome when the reactor was operating. The crane rotates completely around the interior of the dome.
"Washington Closure Hanford did a good job of engineering (the demolition) so they could use that crane," said Mark French, Department of Energy project director for environmental cleanup along the Columbia River.
As cuts were made in the 80-foot-diameter dome, clips were installed and held with pins to secure the dome.
The final cuts were made Saturday, French said, and then the pins were pulled to release the clips.
The dome, which weighed about 71 tons, was lifted off in a single piece and lowered to the ground by Barnhart Crane & Rigging, using a crane that weighed 500 tons and had a 200-foot boom.
The dome, which has some radioactive contamination, will be cut into pieces and disposed of at the Environmental Res-toration Disposal Facility, a landfill for low-level radioactive waste in central Hanford.
Construction of the test reactor, which is attached to a large building, began in the late 1950s with Sen. Henry Jackson driving a bulldozer for the ceremonial ground breaking. When construction company Shaw & Estes Co. fell almost a year behind schedule, it was replaced by the J.A. Jones Co. Catch-up work went around the clock seven days a week.
The reactor started up in 1960 and ran for about 10 to 14 days at a stretch and then was shut down to remove the fuel for study and to insert new fuel. There was little slack time, retired Hanford engineer Ed Utz remembered in 1999 when maintenance was being done on the unused reactor.
"It was used to prove a concept -- that it was possible to reprocess unburned fuel and put it back in the reactor and have it run again," Utz said this weekend.
DOE documents describe it as a heavy water moderated, 100 megawatt experimental reactor used to demonstrate the effectiveness of various plutonium oxides containing blends of plutonium, uranium and other metals.
The reactor shut down in September 1965 for six months when an experiment went awry. A fuel rod containing plutonium oxides was deliberately damaged by boring a pinhole in the casing to see what would happen to it in a reactor.
The hole unexpectedly grew to the size of a thumb and fuel escaped from the casing. Heat and pressure burst a processing tube, sending the reactor's gases through the containment dome. The reactor automatically shut down.
After it was restarted, the reactor operated until 1969 when a flaw in a coolant valve was discovered. Repairs were under way when the Atomic Energy Commission ordered it into standby, which proved to be the end of operations.
About 90 percent of the research had been completed by then, Utz said.
The next step in the reactor facility's demolition will be pulling out the crane in its dome and then taking down the concrete walls that supported the dome. That will leave the underground portion of the reactor building, where reactions occurred. It extends about 80 feet underground, including heavy shielding beneath the reactor.
"It's a significant piece of work," French said. "It's going to take a couple years to take out the reactor and the underground portion."
The above ground work should be completed this year, he said.
"It's just another very visual sign of the progress we're making" to clean up Hanford, he said.
Read more: http://www.thenewstribune.com/2011/01/17/v-lite/1505372/hanford-reactor-dome-comes-down.html#ixzz1BJQR5gTO
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