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With fewer than 30 days of unplanned downtime in its over 3,500 days of shot operation, the National Ignition Facility (NIF)—the world’s highest-energy laser—has been remarkably efficient since its operations began in 2009, achieving up to 400 planned shots each year. NIF’s energy, power, and precision enable cutting-edge science in extreme conditions, allowing researchers to study materials under extreme pressures, achieve fusion ignition, and more. Despite continuous improvements in its performance, much of NIF is over 20 years old, while some supporting infrastructure is approaching 40 years of operation. In addition to aging parts and obsolete technologies, NIF’s higher yield—with six instances of ignition achieved including the first on December 5, 2022—is degrading sensitive target area systems at a higher rate than in preceding years. To continue meeting and exceeding its operational goals for advancing key research initiatives, NIF requires regular maintenance and refurbishment activities to ensure its performance, accuracy, and reproducibility, together with a new Sustainment Plan that will ensure operation into the next two decades.
Continuous Maintenance
NIF operates 24 hours a day, seven days a week. Though two of the seven days are dedicated to system maintenance and preparation for the next five days of shot operations, longer maintenance windows called facility maintenance and refurbishment (FM&R) periods—which range from one to three weeks—are scheduled three times a year. During FM&Rs, NIF temporarily pauses experiments to enable more significant maintenance projects, reconfigurations, and the deployment of new capabilities. “These are highly critical times, similar to a factory outage,” explains Stanley Sommer, NIF’s facility and infrastructure systems manager.
FM&R periods require extensive planning to perform more intrusive work that cannot be done in short periods between experiments, including repairs and recalibrations of sensors, sometimes in areas that require additional safety precautions. “We have to be prepared because performing maintenance requires us to do work we don’t normally do and work in areas that can pose safety hazards. We need to make these areas safe so we can go in and do maintenance, repairs, and other activities that can affect shot operations,” says Sommer. One important safety consideration is oxygen deficiency in laser pathways. Portions of the laser path are filled with argon during experiments, which must be adequately removed and replaced with air before humans can enter to work on equipment.
Ensuring appropriate worker safety controls are defined, reviewed, authorized, and verified are crucial work activities in NIF. During the FM&R period in August 2024, engineers worked inside NIF’s vacuum systems—systems that are vital to facility function but also notoriously difficult to maintain—monitoring oxygen levels to ensure workers are safe to perform maintenance on the systems. Once the FM&R work was complete, the team had about an hour to celebrate before going back into operations.
Planning Sustainment
Despite ongoing maintenance, 15 years of operation has led to several larger issues within NIF that require even longer maintenance periods to address. Through years of use, the sealant along blast shields that protect NIF’s laser amplifier glasses has degraded, depositing unanticipated debris along the amplifiers. Similarly, years of target experiments have created significant debris in the final optics systems—a series of mirrors and lenses that focus NIF’s 192 laser beams into a target capsule about a centimeter tall and onto a target capsule about two millimeters in diameter. “Over time, that debris has increased damage, and we are concerned it may reach a point that we would have to lower the performance of NIF. If we don’t resolve these issues, damage could result,” says NIF Director Gordon Brunton.
Additionally, many of the key systems original to NIF construction are now obsolete, and the levels of spare parts are dwindling. Over the past several years, NIF has experienced an increasing number of delays from the systems’ hardware failures, resulting in a reduction in the level of critical data NIF provides for the National Nuclear Security Administration’s (NNSA’s) Stockpile Stewardship experimental programs. Though NIF has a plan to replace damaged parts with spare parts, many of its components are no longer made; NIF has already purchased all the spares in circulation and will likely run out within the next five years. “Combining all these factors and looking across the entire NIF landscape, we put together what we call the NIF Sustainment Plan,” says Brunton.
After gaining support from NNSA over the necessity of investing in a multiyear NIF Sustainment Plan, NIF and NNSA negotiated a funding agreement with Congress that began in 2023 and will continue through 2030. The plan consists of about 30 projects that will address the highest risks in the near future to allow NIF to continue operating at its highest levels of performance. “Making big science takes big investment,” says Brunton.
Brunton compares sustainment to taking care of a car. Regular upkeep—FM&R and the two days of maintenance each week—is similar to changing the oil and the filters, but the time eventually comes for larger investments to maintain the car’s longevity. The NIF Sustainment Plan will supplement weekly and quarterly efforts with a larger refurbishment to maximize NIF’s lifetime, value, and capabilities. “NIF has reached that point in time that it’s at midlife, and it needs a higher level of maintenance, such as a transmission overhaul. NIF sustainment will address a one-off large body of key system refurbishments and recapitalizations before going back to the regular kind of maintenance, like oil changes,” says Brunton.
Though NIF’s systems and components are interrelated and integrated, the projects that comprise the NIF Sustainment Plan are independent and vary in scope. For example, each of the nearly 4,000 amplifiers—three-inch-thick slabs of neodymium-doped phosphate laser glass about 76 centimeters wide by 38 centimeters tall—will be removed, cleaned of debris, and reassembled. Autonomous robots raise the glass slabs, which are grouped by four into an approximately 2.5-meter-tall assembly, into the beamline. This system has never been disassembled, and special equipment, including a processing facility for managing dirty parts, is being built to efficiently remove and prepare the glass. Sommer emphasizes the significant systems engineering approach that must be built into such maintenance projects for embedding engineering, installation, and commissioning processes into NIF’s operational schedule.
Other NIF sustainment work simply relies on removing a problem. “The neutrons generated during NIF shots can degrade electronic equipment, and as we go to higher yields, it would be more effective to remove these systems rather than to protect them,” says Brunton. For example, NIF’s higher yields impact a viewing system outside the Target Chamber that allows operators to see the 10-meter-long positioners used to align the laser beams. Regular replacements not only deplete the spares NIF has in stock but also require a significant time investment for NIF operators. To maintain the high number of annual experiments, the NIF Sustainment Plan will improve the efficiency of part removal prior to a shot and reinstallation of sensitive parts after the shot in addition to hardening some components to withstand higher neutron levels, such as analog tube cameras to replace some digital cameras.
Many Sustainment Plan projects will primarily take place during regular weekly maintenance and FM&R days, and for the most part, NIF will continue to operate while the Sustainment Plan is executed. Some projects, including the amplifier refurbishment, are larger in scope and cannot be fit into these periods. During the final four years of the Sustainment Plan (fiscal years 2027 through 2030), NIF will be scheduled in eight-week blocks, in which operations will fully shut down for two weeks to allow time for the larger projects and refurbish one section of the laser glass at a time, followed by six weeks of experiments. The procedure will have a minor impact on the experimental program during this time but is both manageable and the most effective method to execute this large scope of work.
Although NIF has a modular design that readily supports the refurbishment approach, undertaking such large-scale maintenance presents challenges. Brunton notes that sustainment, in some ways, is more difficult than the initial construction. For example, during NIF’s inception, experiments were not simultaneously firing, and potential problems or unexpected delays had fewer immediate consequences. Now, engineers and technicians must ensure that just after a maintenance period is completed, NIF can perform at least as well as it did before, which requires substantial preparation. Despite additional downtime for maintenance periods, NIF must continue to ensure the necessary productivity to satisfy annual program objectives supporting the nation’s nuclear deterrence.
The Next Generation of NIF
As action on the NIF Sustainment Plan progresses, the institutional memory of the early NIF pioneers remains crucial to avoid reinventing and reengineering solutions. “Many staff who were originally involved in designing, building, and operating NIF have retired or moved on and are being replaced by a new generation of people,” says Bruno Van Wonterghem, NIF operations manager. As only a handful of NIF’s original team remain at Lawrence Livermore, integrating new scientists, technicians, and engineers is key to sustaining NIF.
By the end of 2024, approximately 70 additional staff had joined NIF as part of the sustainment efforts. Because NIF’s systems are always in use, new employees—some of whom are younger than NIF itself—rarely have an opportunity to immerse themselves in its inner workings. “Sustainment is a great opportunity to understand how NIF works because we have to delve into the details, and underneath every detail are 10 more details to explore,” Van Wonterghem says. “This program creates an ideal training ground for our new and existing team members.”
In September 2024, building on the foundation of NIF sustainment and with the goal of continuing to push boundaries, NIF received Critical Decision 0 (CD-0) approval of the mission need for an Enhanced Yield Capability (EYC) project. The CD-0 decision—which took only one year, the fastest in NNSA history—allows NIF to develop a conceptual design for EYC. NIF’s original design plan left room for insertion of two additional power amplifiers that were ultimately unnecessary to meet the project performance requirements at the time. The EYC project proposes to install laser glass into these empty locations, which will increase NIF’s maximum laser energy from its current 2.2 megajoule (MJ) level to 2.6 MJ, potentially pushing yields well beyond its current 5.2-MJ record to the much higher yields that will be needed in the future. “Those higher yields unlock additional applications that we can directly use for stockpile stewardship missions and, in doing so, close the gap to the conditions that we used to have when we did underground testing,” says Brunton.
—Anashe Bandari
For further information contact Gordon Brunton (925) 423-4138 (brunton2 [at] llnl.gov (brunton2[at]llnl[dot]gov)).
