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Research experiments generate data, publications, new scientific discoveries, and—almost always—waste. For special nuclear materials (SNM) research supporting the Laboratory’s stockpile stewardship mission, handling that waste safely requires expertise and diligent care.
The Laboratory is tasked with modernizing two aging nuclear warheads, as well as conducting annual assessments of three others. Scientific expertise with SNM is a key element in Lawrence Livermore’s ability to conduct these assessments and certify modernized warheads as safe, secure, and effective without conducting an underground nuclear test. Laboratory scientists study the physical, chemical, and metallurgical qualities of SNM, such as highly enriched uranium and plutonium, as well as tritium. Tests analyze existing nuclear components, duplicate the mechanical motion and temperatures expected over a weapon’s lifetime, and review approaches to replace components in the future. Along with research results come clothing, tools, debris, and residues contaminated with very small amounts of plutonium and other human-made radioactive elements.
Waste from elements with an atomic number greater than uranium and radioactivity exceeding a specific limit is labeled “transuranic” or “TRU” waste. The National TRU Program in the Department of Energy (DOE) Office of Environmental Management is charged with the safe disposal of TRU waste accumulating at DOE sites dedicated to SNM research, weapons production, and cleanup. “Lawrence Livermore takes special care to properly manage and dispose of all hazardous and radioactive waste,” says Reggie Gaylord, manager of the Laboratory’s Radioactive Hazardous and Waste Management (RHWM) Program. “Handling TRU waste adds another level of detailed planning and execution.” Adding to the complexity of this task, only one location can accept the material: DOE’s Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico.
Located in a nearly 610-meter-deep mine within a salt dome, storage areas at WIPP isolate and entomb TRU waste. Evaporation cycles 250 million years ago created WIPP’s salt beds, and the fact that salt remains today indicates a lack of groundwater intrusion. To support the nation’s nuclear defense programs, the National Academy of Sciences determined that geologically stable, impermeable salt beds were the best option to isolate radioactive waste to protect human health and the environment for millions of years. The salt rock is easily mined to create disposal rooms yet creeps slowly to seal all fractures and naturally close openings.
Construction of WIPP started in the 1980s, and TRU waste was first accepted there in 1999. Since its commissioning, WIPP has accepted TRU waste from 22 sites in the DOE complex. The bulk of the waste has come from former weapons production sites such as the Rocky Flats Environmental Testing Site and Los Alamos and Idaho national laboratories. Smaller amounts have arrived from the Savannah River Site, the Nevada National Security Site, and national laboratories such as Lawrence Livermore.
WIPP stores two types of TRU waste: contact-handled (CH) TRU waste—about 96 percent of the total at WIPP (and the only TRU waste generated at Livermore)—or remote-handled (RH) waste. The radiation dose of CH TRU waste, measured at the waste container’s surface, does not exceed 200 millirem (mrem) per hour compared to RH TRU waste’s dose rate of up to 1,000 rem per hour. The average American is exposed to 200 mrem annually from natural radiation in the environment and diagnostic x rays. During transportation, lead shielding around all TRU waste shipping casks reduces radiation doses to very low levels. Once inside WIPP, CH TRU waste barrels and boxes are stacked in rows in underground disposal rooms, while higher dose rate RH TRU waste canisters are placed in boreholes drilled into WIPP’s salt walls.
Shipments of radioactive waste from DOE facilities ceased between 2014 and 2017 following the 2014 accidental leak of TRU waste from a storage drum generated at a DOE site and emplaced a year earlier. Although the public was never at risk, DOE enacted improved storage and monitoring practices. The Environmental Protection Agency (EPA) recertified WIPP as safe for radioactive waste disposal in 2017, and the facility regained DOE accreditation for high safety and health performance. WIPP operates under stringent controls to prevent the release of radioactive materials.
Operations staff in the Laboratory’s Weapons and Complex Integration (WCI) Principal Directorate consider waste management strategies during experiment design and facility startup to ensure the waste has a disposal path. Day-to-day, TRU waste generated onsite is segregated into mixed debris such as gloves, tape, tools, paper, and aluminum foil; solidified inorganics and organics (liquids transformed to solids by clay); and salts. Debris, the largest component of this waste stream, is broken down into individual pieces of metal, plastic, even balls of tape. This painstaking task is performed in a large glovebox located in the Laboratory’s plutonium facility—the Centralized Waste Processing Line—by RHWM program personnel. “The level of training required at every stage of this process is incredible,” says Gaylord. “To become a Certified Fissile Material Handler takes many months, and handlers are overseen by supervisors with multiyear training and experience.”
After sorting, waste characterization ensures TRU waste can be shipped safely to WIPP. First, waste that cannot be accepted at the disposal site, such as liquids, batteries, and sealed containers, is identified and segregated. Trained visual inspectors examine waste during generation while older waste undergoes radiographic testing. In the next step, gamma-ray spectroscopy performed with high-purity germanium detectors identifies and measures radioactive isotopes present in waste containers. Finally, container headspace sampling using gas chromatography–mass spectrometry looks for flammable volatile organic compounds and other gasses, such as hydrogen and methane, that can form from the interaction between radiation and plastics or organic waste. Acceptable Knowledge, defined as a combination of waste generation process knowledge, data analysis, and facility records, complements the three-part waste characterization process. “The level of detail required to complete each waste characterization step has increased tremendously since the 2014 accident at WIPP,” says Rod Hollister, the Laboratory’s TRU waste subject matter expert. “The biggest challenge has been meeting the level of Acceptable Knowledge associated with each waste stream.”
Following characterization, waste drums are stored under tightly controlled conditions in RHWM’s nuclear facilities. When enough certified containers accumulate to warrant shipment, Laboratory and WIPP experts collaborate to ensure TRU waste is packaged and shipped in compliance with EPA and Department of Transportation regulations. TRU waste is shipped in a specially designed shipping container called the TRUPACT II, certified by the Nuclear Regulatory Commission to provide the highest level of safety and the capability to withstand severe accidents. Trucks en route to WIPP are tracked by satellite and come equipped with redundant communication systems.
Removing TRU waste has priority for DOE’s National Nuclear Security Administration (NNSA) to ensure workplace and public safety as well as uninterrupted SNM research. However, shipments to WIPP must be paced to avoid overtaxing limited shipping resources and overwhelming the facility. Prior to 2020, the Laboratory shipped TRU waste in 2004 and again between 2009 and 2010. Recognizing that Laboratory waste storage capacity limits would be reached after approximately 10 years, WCI operations staff started planning in 2016 for a 2020 campaign. “Approaching waste storage capacity in Superblock laboratories impacts programmatic work, since the drums of waste often must be stored in laboratories and work areas,” says Hollister.
Hollister and project manager Clint Conrad, with more than 60 years in waste management experience between them, developed a detailed, multiyear plan to execute a 2020 TRU waste shipment to WIPP. “With that plan in hand, we obtained $16 million from NNSA for activities culminating in a 2020 shipment campaign,” says Conrad. “Experts from WIPP’s Central Characterization Program (CCP) partnered with us to make the plan a success.”
The Laboratory and CCP share TRU waste management responsibilities during a campaign: the Laboratory ensures safe operation and handles any required remediation, and CCP is responsible for characterizing the waste. CCP inspectors relocate to the site for the duration of characterization activities. “Nothing leaves without our say,” says Jackie Hulse, a CCP inspector who has worked with TRU waste since 2009. She and her CCP colleagues participate in several hours of training each day. In fact, each CCP inspector’s credentials and training records in visual examination, nondestructive assay, or gas sampling are verified daily to qualify them for characterization activities.
For the 2020 campaign, the Laboratory–CCP team established onsite waste characterization capabilities by 2018, and the site was certified by DOE’s Carlsbad Field Office, which manages WIPP, as well as the State of New Mexico and the EPA. From summer 2019 through early 2020, 874 drums and waste boxes were characterized onsite with only a few containers requiring follow-up analysis or repackaging.
Despite the 2020 shelter-in-place orders issued for San Francisco Bay Area counties, review and approval of Laboratory processes related to generating, evaluating, and characterizing waste continued. NNSA, DOE, and WIPP coordinated eight-week rolling WIPP shipments for Livermore’s TRU waste. WIPP’s Mobile Loading Team arrived in September 2020 and began placing characterized waste into TRUPACT II containers for shipment to WIPP. Laboratory staff including riggers, material handling technicians, and Environmental Safety and Health staff supported the loading effort. California and Nevada Highway Patrol officers inspected the vehicles, and the first shipment left Livermore on September 21, 2020. In the months that followed, 18 shipments comprised of 624 waste drums and 13 standard waste boxes made their way to the New Mexico facility.
Following the 2020 campaign, the Laboratory team capitalized on the training efforts and characterization facilities created for the shipping effort and pursued an enduring TRU waste certification model. “With the enduring program, staff remain in a trained and ready state rather than gearing up for a new shipment campaign every 10 years,” says Gaylord. “Costs are lowered, and efficiency is increased.” Laboratory and CCP personnel established a certified visual examination process, eliminating the necessity of radiographic examination since all waste would be examined when generated. Inspected waste can be transferred directly to waste drums at the Centralized Waste Processing Line. The non-destructive assay is performed using a CCP-certified process, and CCP personnel conduct flammable gas analysis once waste is packaged and moved to the RHWM storage facilities.
In October 2021, two shipments consisting of 70 drums were successfully shipped to WIPP. The Laboratory is continuing to accumulate containers for additional shipments approximately every 9 to 12 months. “We have successfully shifted from a periodic to an enduring model for TRU waste generation, characterization, and shipping,” says Gaylord. “Not only have we increased our TRU waste-handling capabilities, we have created a more streamlined environment for the nuclear material testing and research that directly supports the Laboratory’s stockpile stewardship mission.”
Key Words: Acceptable Knowledge, Central Characterization Program (CCP), radioactive waste, special nuclear material (SNM), transuranic (TRU) waste, TRUPACT II, waste characterization, Waste Isolation Pilot Plant (WIPP).
For further information contact Reggie Gaylord (925) 423-1876 (email@example.com).