President Trump’s push to ramp up domestic nuclear power generation capacity from 100 GW to 400 GW by 2050 is expected to necessitate enhancements in transmission infrastructure, substations and grid interconnections.

Lawmakers are urging the Department of Energy to speed up the deployment of advanced nuclear technologies, including small modular reactors. Congressional talks have focused on permitting and cross-regional transmission.

But public concerns over additional nuclear waste could stall progress. Since 1942, the dawn of the nuclear age, nuclear waste has required geological burial for 300,000 years before radiation levels can return to levels found in nature. And the consequences of some nuclear power generation system failures have been catastrophic.

Working to address these challenges, Argonne National Laboratory in Lemont, Ill., is researching nuclear waste recycling, as well as ways to monitor plant design maturity, performance and nuclear reaction and breakdown.

On June 18, in tandem with the lab’s 80th anniversary, Argonne hosted a presentation by three scientists engaged in research applicable to most small modular reactors being developed today.

The lab has a rich history of nuclear reactor development, from the earliest reactors to light water technology and heavy water and graphite technology to fast reactor technology, which scientists continue to build on today.

Steve DelaCruz, a chemical engineer at Argonne, explained “pyroprocessing,” a process pioneered at Argonne in the 1950s and still being honed today. Spent fuel rods are immersed in salt, which liquifies at high temperatures. The salt is separated from the resulting metal to create a substance suitable for recycling for other uses.

The resulting salt substance requires geological burial for around 300 years, one-thousandth of the time previously required for returning nuclear waste to levels found in nature. While 300 years is still a long time, the stride represents significant progress, along with the fact that pyroprocessing significantly reduces the amount of waste actually requiring geological burial.

Xuan Zhang, principal materials scientist at Argonne, talked about nuclear materials operating in an extreme environment, making it difficult to analyze their nature without destroying them or risking contamination. Nondestructive probes offer a new ability to peer through the material without destroying it.

“We can generate 3D scans of samples and take pictures at super high speeds,” she said.

Zhang and the lab recently teamed up with a University of Illinois team to study damaged reactor bolts and were able to map crystals that formed inside of cracks to gain a better understanding of what led to their degradation. The effort was recognized by the U.S. Department of Energy as a milestone, likely to advance the safe deployment of new generation nuclear reactors.

Nora Shaheen, another chemical engineer affiliated with Argonne, talked about sensors that help monitor the reactor design maturity process, providing real-time feedback to designers on the performance of systems. She explained that solid-phase sensors track solid particles, leaks, impurities and fission reactions. Liquid sensors identify and measure dissolved materials.

The testing processes facilitate adaptive use of recycled materials by industry.

You can view the presentations by the three Argonne scientists here.

I asked Mark Williamson, division director of chemical fuel cycle technologies in Argonne's Nuclear Technologies and National Security Directorate, some questions to better understand how Argonne’s research supports deployment of the next generation of nuclear reactors.

1) How much nuclear waste is expected to be generated with these new recycling technologies?

Fission product waste accounts for approximately 3% by mass of the used fuel removed from the current light water reactors. The remaining approximately 97% of the used fuel can be recycled to an advanced reactor to produce additional energy. Continuous recycling of fuel materials in an advanced reactor will result in similar amounts of fission product waste per unit energy produced and yield improved uranium resource utilization. A key design feature of the fuel treatment process is, for example, to recycle processing media such as molten salts to minimize secondary waste production [as described by DelaCruz].

2) Can waste recycled through the processes being developed at Argonne be recycled again after reuse? Is it possible to recycle indefinitely, or are there natural limitations on this?

The energy-bearing materials in the used fuel discharged from current light water reactors can be recycled to advanced reactors such as a sodium-cooled fast spectrum reactor (SFR) to produce additional energy. Similarly, the fuel discharged from the advanced reactor can be continuously recycled to produce additional energy. Additional uranium will need to be added to the recycled fuel to offset the amount fissioned, but ample uranium is available from recycled light water reactor fuel. The combination of an SFR with continuous fuel recycling allows for full utilization of the energy content of the mined uranium.

3) While a reduction of 300,000 years to 300 is phenomenal, is there hope for further reducing the time for uranium to return to its natural state?

The combination of an SFR with continuous recycling produces a fission product waste stream that after 300 years of decay will be equivalent to the radiological toxicity of the natural uranium ore mined for energy production. The relative comparison to naturally occurring uranium ore provides a useful benchmark. The fission product decay process will continue and progressively approach zero radiological toxicity. 

4) What is the timeline for implementing these processes? 

The objective of our R&D is to lead the industrialization of a first-of-its-kind, pilot-scale used fuel recycling facility in the United States. The recycling facility should be developed in parallel with an SFR so that the product from the recycling facility can be used in the SFR. Several commercial entities have announced their plans to deploy used fuel recycling by approximately 2036.

5) How will these processes relate to the smaller reactors being developed today?

The recycling technologies discussed during the OutLoud lecture are applicable to most small modular reactors being developed today, and both the reactor and recycling technologies are being developed in parallel. Many of the small modular reactor concepts propose to use high-assay low enriched uranium (HALEU) fuel, so recycling will be essential to utilize the full energy content in that fuel.

6) In some instances, jet engines are being repurposed for energy production, in addition to other means, to power data centers. Would nuclear power create less noise and air pollution?

Dedicated nuclear energy systems with standard energy conversion technologies are well suited to provide power to data centers. In fact, many of the large data center owners have announced partnerships with nuclear companies to provide power to their systems. The size and number of reactors required to support the electrical needs of the data center will depend on the size of the data center. Nuclear energy systems would reduce the environmental impact (e.g., air pollution, noise, etc.) of power production for a data center.