The hydraulic shear before it was encased in a structure designed to prevent release of contamination to the outside environment at Technical Area 54 at Los Alamos National Laboratory. Photo Courtesy N3B
N3B’s Waste Retrieval Operations Supervisor Juan Garcia guides a mock-up pipe, filled with cement that does not contain radioactive waste, while it is loaded onto a pipe-roller conveyor belt before being cut into sections. The ends of the actual corrugated metal pipes to be retrieved from an underground storage site will be covered in full containment sleeves. Photo Courtesy N3B
N3B NEWS RELEASE
N3B Los Alamos recently installed a hydraulic shear system for remediating transuranic (TRU) waste contained in large, corrugated metal pipes buried underground at Los Alamos National Laboratory (LANL) since 1986.
The project is part of a strategy by the U.S. Department of Energy’s Environmental Management Los Alamos Field Office, for which N3B is the prime contractor, to remove below-ground waste at Technical Area 54 (TA-54) Area G and ship it off-site for disposal. Area G is used to store, characterize and remediate LANL’s legacy transuranic and mixed and low-level waste before it is shipped off-site for permanent disposal.
After assessing various types of equipment for safely cutting the radiologically contaminated pipes to fit into standard waste boxes for off-site shipment, N3B selected and installed a commercially proven hydraulic shear system. The shear will create a clean cut, absent of excessive airborne dust.
The pipes are 20 feet long, about 30 inches wide and filled with cemented radioactive liquid waste. Each pipe weighs between 10,000 and 14,000 pounds. The waste comes from a former LANL radioactive liquid waste treatment facility that operated during the Cold War era at Technical Area 21 (TA-21).
After retrieving 158 corrugated metal pipes from their underground storage site, N3B operators will use the shear to cut them into about 790 sections for characterization. The pipe sections will be shipped for disposal to the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico.
N3B’s research team scrapped initial plans for a diamond wire saw when it identified a better cutting method in the hydraulic shear. The shear has been modified from its standard use — cutting piles above and below water levels in bridgework and oil drilling platforms. It significantly reduces safety concerns and requires fewer facility modifications.
“Research indicated the diamond wire saw would produce more than 80 pounds of radioactive particulate dust for every four cuts required for each metal pipe,” said David Wirkus, N3B’s radiation protection director and acting contact-handled transuranic waste radiological control operations manager. “A new diamond wire saw blade also would be required after every thirteenth cut, introducing a safety risk to workers. The expense for the blades and added personal protective equipment would be significant.”
Wirkus noted the hydraulic shear does not require blade replacements, and the shear cuts produce much less excess material to capture.
“This represents a huge safety risk reduction for our workers — a top priority for the cleanup mission,” Wirkus said.
Two mock-up pipes were recently processed to test operating procedures and train N3B staff in safe practices. The mock-up pipes allow testing without any radiological material, a common means of preparing new waste processing operations.
“Testing and training provides analysis of possible hazards, identification of all safety equipment needed and adjustment of procedures for final approval,” said Steve Godfrey, N3B project manager.
N3B will complete required adjustments identified during a recent contractor readiness assessment, followed by DOE authorization for startup of the pipe retrievals.
The pipe size-reduction activities will occur at TA-54 within a structure designed to prevent release of contamination to the outside environment. It has four primary high-efficiency particulate air (HEPA) filter ventilation units, and a ventilation contamination enclosure will be placed over each pipe during shearing.
Origin of contaminated pipes
From 1968 to 1978, wastewater from the former radioactive liquid waste treatment facility was collected and neutralized in special stainless steel, water-cooled storage tanks. The resulting contaminated sludge was mixed with cement. The mixture was pumped into corrugated metal pipes with a clean cement cap on each end and then stored underground.
In 1986, 158 contaminated pipes were retrieved from storage at TA-21, decontaminated and transported from TA-21 to Area G, where they were buried underground to stage them for eventual retrieval.