Advancing fuel production and performance for the next generation of reactors

September 26, 2023, 7:05AMNuclear NewsW. A. “Art” Wharton III

W. A. “Art” Wharton III

Multiple market forces on nuclear fuel have arisen seemingly at the same time since the Russian war in Ukraine started. Accident tolerant fuels (ATF), lead test rods, and lead test assemblies have had their first shot in real operating conditions, in recent cycles. But the popularity of their so-called accident tolerance has nothing to do with accidents, since any practical nuclear professional knows that the safety of nuclear energy is already higher than that of any other electricity generation source. The popularity comes down to fuel performance. Are we on the cusp of a revolution in nuclear fuel performance under the guise of accident tolerance?

For pressurized water reactors, the design space for low leakage loading patterns with a maximum 4.95 percent uranium enrichment has been consistent for decades. The fuel cycle was in an equilibrium of sorts, with the exception of commodity price fluctuations. It allowed for demonstration of consistent margins to enable uprates and the slow evolutionary progression of cladding fuel performance.

The industry also has undergone a period of increased funding in fuel product and performance innovation. The 2011 Fukushima Daiichi accident acted as a convenient scapegoat for the sense of regulatory urgency and reason for funding. The concept today for ATF is that different cladding and different fuel chemical compositions will enable operational plants to load more uranium per bundle, whether by fuel material density, enrichment above 5 percent, or both, leading to longer fuel cycles with the potential for higher discharge burnup in the end.

PWRs are following in the footsteps of their boiling water reactor counterparts, shifting toward 24-month cycles. However, this is not the exercise in nuclear fuel efficiency it might once have been. After more than 10 years of “delivering the nuclear promise,” plants are understaffed, which threatens regular operations and ongoing initiatives for license extensions and cycle length adjustments. Whether the result of layoffs, a generational chasm that created an experience void, hiring and retention challenges due in part to “brain drain” and post-COVID personnel perspective shifts, or a combination of these factors, the outcome is the same. Though fewer outages will reduce the overall burden on the workforce, the benefits of using ATF and having a 24-month cycle are potentially overshadowed by staffing concerns.

A more highly differentiated nuclear fuel market with products that have greater than 5 percent uranium enrichment—as well as new claddings and coatings—is a new competitive space that requires significant capital investments. There are no circumstances in which the fuel revolution will be cheaper—at least in the short term—while that capital is paid off. However, there is a win-win to be had here. As new fuel products hit the market that will enable 24-month cycles in PWRs, the unwanted consequences of staff turnover due to the frequency of outages can be reduced. Additionally, new fuel products containing the accident tolerance that industry is aiming for could lead to the removal of plant systems and components that are required to meet probabilistic risk assessment guidelines in today’s normal uranium dioxide and zirconium alloy fuel products. A simplification of plant layout and equipment will benefit operations, maintenance, and surveillance procedures. This could reduce O&M costs to a greater degree than fuel costs, offsetting the cost rise per MWe.

If, as an industry, we can simultaneously simplify plant operations, reduce total costs, and meet the world’s emotional (but not necessarily rational) need for additional theoretical accident tolerance from the demonstrably safest form of electricity production available, then we should go forward. The world is a better place, because a long line of smart people perfected the current operating reactors and uranium dioxide fuels clad in zirconium alloys. As unnecessary as it may feel from an inside perspective, our duty to society is to continually prove that the nuclear industry can improve operational efficiency within the confines of national security and nonproliferation limitations. But, to paraphrase Thomas Edison, opportunity often arrives dressed in overalls, looking a lot like work.

Who will do all of this work during a resource crunch? If ever there was a time to forge new partnerships, this is it. We’ll be forced to “work smarter, not harder,” with advanced simulations, automation of engineering tasks, and discovery of how artificial intelligence can be appropriately used to improve decision-making and speed up design. Short-staffed utilities will need to tap into the expertise of the supplier community to apply common solutions to various types of reactors, rather than invest the time and effort of reinventing solutions from scratch in parallel with one other.

There is a lot of excitement in the new and advanced reactor community, but some fuel innovations can be applied to the current operating fleet, which is heading toward more subsequent license renewals—to 80 years—and showing early indications that 100-year extensions are within the realm of possibility. This underscores the notion that decisions we make today can affect the future on a generational scale. Let’s work together as an industry to meet our obligations to society and future generations by making these fuel innovations a reality. We are on the cusp of a fuel performance revolution so long as the right cooperative teams are formed to make it a reality.

W. A. “Art” Wharton is the business area president at Studsvik Scandpower Group, which provides nuclear engineering software and calculational methods to operating plants globally. An active member of the American Nuclear Society since 2004, Wharton most recently served two terms on the ANS Board of Directors and Executive Committee as treasurer of the Society.

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