770-ton load from San Onofre nuclear plant finishes trip to Utah
- Jul 21, 2020 9:22 am GMT
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The seven-week journey of a 770-ton shipment of an old but vital piece of the San Onofre nuclear power plant has been completed.
The reactor pressure vessel that helped generate electricity at Unit 1 of the plant arrived last week at a licensed disposal site about 75 miles west of Salt Lake City after being shipped by rail and then over highways in Nevada and Utah.
Doug Bauder, chief nuclear officer at Southern California Edison, said removing the vessel "is an important milestone" in the larger efforts to decommission the San Onofre Nuclear Generating Station, known as SONGS for short.
"The project required detailed planning and coordination between the SONGS oversight team and our contractors," Bauder said in an email. "From start to finish, the project was done with safety as the top priority."
The vessel left SONGS May 24 via rail before stopping at an industrial park in North Las Vegas, Nevada, where cranes helped assemble a trailer 122 feet long, with 45 axles, that slowly hauled the massive chunk about 450 miles along highways in Nevada and Utah to the Energy Solutions disposal facility in the town of Clive, Utah.
Six heavy-duty Class 8 trucks with combined 4,000-horsepower moved the the load. The convoy used 460 tires that were 18 inches wide to prevent damaging roads, bridges and public infrastructure. Contractors from Emmert International used hydraulic jacks to reinforce drainage culverts.
A spokesman for the Nevada Department of Transportation said it was the heaviest load to ever traverse the Silver State's roadways. Transportation officials in Utah said the shipment arrived July 14 without any issues.
The pressure vessel once held nuclear fuel at SONGS when Unit 1 was in operation between 1968 and 1992. For 18 years, the vessel sat on the north end of the plant, covered in a shell of steel two inches thick with a top and bottom each each inches thick to shield against radiation.
Encased in a carbon steel cylinder for the trip, the vessel contained pieces of radioactive metal and grout. The shipment was designated as Class A low-level waste, considered by the U.S. Nuclear Regulatory Commission as the least hazardous of radioactive waste classifications.
The shipment is one of many that will head to the Clive disposal facility as part of a scheduled eight-year process to dismantle SONGS, although future shipments will not be as large. Energy Solutions and construction giant AECOM have partnered to undertake the $4.4 billion demolition project, which began earlier this year.
The SONGS decommissioning plan is one of the nation's largest, with Energy Solutions telling the Salt Lake City Tribune it expects to yield about 13.4 million cubic feet of low-level waste. The company projects about 40 percent to 60 percent of the material to be free of damaging levels of radiation.
"However, because they are present within the licensed footprint, they must be considered and treated as being radioactively contaminated until the absence of excess levels of radioactivity can be confirmed," Energy Solutions spokesman Scott Walker told the newspaper.
If all goes as planned, by the time dismantlement at SONGS is completed, all that will remain will be two dry storage facilities holding 3.55 million pounds of used-up fuel, or waste, that accumulated during the time the plant produced power; a security building with personnel to look over the waste enclosed in casks; a seawall 28 feet high at its base; a walkway connecting two beaches north and south of the plant and a switch-yard with power lines.
The distinctive 200-feet-high twin domes that loom over Interstate 5 are scheduled to come down between late 2025 and 2027.
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