A part from a decommissioned nuclear power plant in San Onofre, San Diego County, California will rest permanently in an engineered disposal cell at the EnergySolutions Clive Disposal Facility about 50 miles west of Lake Point.
EnergySolutions announced that the reactor pressure vessel from the previously decommissioned Unit 1 of the San Onofre Nuclear Generating Station arrived at their Clive facility on July 22.
The Nuclear Regulatory Commission describes reactor pressure vessels as “thick steel containers that hold nuclear fuel when the reactors operate.”
The vessels provide one of several barriers that keep radioactive material out of the environment, according to the NRC.
“This is a significant milestone for the SONGS (San Onofre Nuclear Generating Station) decommissioning project,” stated Ken Robuck, president and CEO of EnergySolutions. “We appreciate the thousands of hours over the course of a three year period that our EnergySolutions employees dedicated to safely transport and dispose of the RPV. We also would like to thank Emmert International and their crew for their support in the safe execution of this project.”
The RPV shipping container was 15’6” in diameter and 38’6” long and weighed approximately 670 tons.
The RPV package was a Class A radioactive waste shipment — the least hazardous class of low-level radioactive waste. It met all regulations for disposal at EnergySolutions’ Clive disposal facility, according to EnergySolutions.
The contact dose rate for the RPV package was less than 0.1 millirem an hour, which is 500 times below the Department of Transportation limit for these types of shipments. A chest X-ray provides a dose of 10 millirem, for comparison, according to the songscommunity.com website.
The RPV package traveled by rail from California to Apex, Nevada using a thirty-six axle Schnabel car — the largest in the world — with a capacity to transport loads up to 880 tons. Rail transport took four days covering 366 miles with a maximum speed of 15 mph.
Rail transport planning included machining the carbon steel sides of the shipping container to comply with extremely tight railroad bridge clearances, multiple 3D laser surveys of the rail route and third party structural evaluations of dozens of railroad bridges and structures.
This effort was further complicated by challenges associated with very specific travel periods and limitations and the restrictions caused by the COVID-19 pandemic, according to EnergySolutions’ press release.
Once the RPV arrived in Nevada, crews prepared the RPV package to be transferred to a hydraulic platform trailer with 384 trailer tires for road transport.
The road conveyance consisted of six large trucks that pushed and pulled the RPV trailer 400 miles through Nevada and into Utah with a maximum speed of 10 mph over a 10 day period.
“This project was a very complex undertaking that required approvals and/or coordination with over two dozen federal, state and local agencies and government entities,” stated Todd Eiler, EnergySolutions projects group director. “The coordinated effort with the rail lines and departments of transportation in California, Nevada and Utah resulted in another safe and successful large component shipment managed by the EnergySolutions projects group.”
Southern California Edison announced in 2013 that it would close the San Onofre Generating Station.
Unit 1 at SONGS, where the RPV came from, operated from 1968 to 1992 when it was closed and partially decommissioned.
The metal shell of the RPV from Unit 1 was initially placed inside a huge steel cylinder. The cylinder was filled with grout for shielding against radiation, sealed, and was stored safely at SONGS site. The RPV contains no spent nuclear fuel and there is no liquid inside the RPV container, according to Southern California Edison.
During 2001 and 2002, the RPV was removed from the Unit 1 containment building at SONGS and placed in a specially designed transport and disposal container.
The original plan was to barge the RPV via the Panama Canal around the tip of South America to a radiological disposal facility in South Carolina. These initial plans were rejected for various reasons and the RPV had been in temporary storage onsite at the SONGS site since then.
At Clive, the RPV will be placed in engineered embankments, or cells, designed for permanent containment of low-level radioactive waste.
A monitoring system ensures the integrity of the cell is maintained. Water and air monitoring stations are located throughout the site to ensure the environment is not compromised, according to EnergySolutions.