Southern Nuclear, Southern Firm’s nuclear energy plant operations enterprise, introduced in late September that it had acquired “first-of-a-kind approval” from the Nuclear Regulatory Fee (NRC) to make use of superior gasoline—accident tolerant gasoline (ATF)—exceeding 5% enrichment of uranium-235 (U-235) in Plant Vogtle Unit 2. The gasoline is anticipated to be loaded in 2025 and could have enrichments as much as 6 weight % U-235. The corporate stated this milestone “underscores the trade’s effort to optimize gasoline, enabling elevated gasoline effectivity and long-term affordability for nuclear energy vegetation.”
“5 weight % was deeply ingrained in all of our regulatory foundation, licensing foundation for cargo containers, licensing foundation for the operation of the vegetation—it was considerably of a line drawn within the sand,” Johnathan Chavers, Southern Nuclear’s director of Nuclear Fuels and Evaluation, defined as a visitor on The POWER Podcast. “Testing of the elevated enrichment element has been a licensing and regulatory train to see how we’d transfer ahead with present licensing infrastructure to put in weight percents above that legacy 5 weight %,” Chavers advised POWER.
In a press launch, Southern Nuclear acknowledged this regulatory train and its significance to grid stability. “Nuclear energy accounts for practically half of our nation’s clear power, and Southern Nuclear is dedicated to pushing for modern, game-changing applied sciences just like the deployment of Accident Tolerant Gasoline that can advance efficiency and additional help our potential to strengthen grid reliability with 24/7 era,” stated Southern Nuclear President Pete Sena. “Realizing the numerous function nuclear energy performs in our nation’s power infrastructure, I particularly need to acknowledge the NRC’s thorough but well timed overview of this set up to help the way forward for business nuclear energy in our nation.”
Accident Tolerant Gasoline Advances
Chavers stated ATF turned a focus for the trade in March 2011 following the magnitude 9.0 Tohoku-Oki earthquake—the biggest earthquake in Japan’s trendy historical past. A tsunami related to the earthquake reached heights of greater than 30 meters and inundation propagated inland greater than 5 kilometers from the Pacific coast, inflicting a disaster on the Fukushima nuclear energy plant.
“In 2012, Congress used the time period ‘accident tolerant gasoline’ for the primary time in an Appropriations Act, and that’s the place all of it started,” Chavers defined. “It was actually for the labs and the DOE [Department of Energy] to incentivize enhanced security for our gasoline in response to the Fukushima incident.”
In 2015, the DOE issued a report back to Congress outlining particulars of its accident tolerant gasoline program. The report, titled “Improvement of Mild Water Reactor Fuels with Enhanced Accident Tolerance,” set a goal for inserting a lead gasoline meeting right into a business gentle water reactor by the top of fiscal yr 2022. Notably, Southern Firm achieved the purpose 4 years early.
“We had been the primary on the earth to set up fueled accident tolerant gasoline assemblies of various applied sciences that had been developed by GE at our Hatch unit in 2018,” Chavers famous. The next yr, Southern Nuclear put in 4 Framatome-developed GAIA lead gasoline assemblies containing enhanced accident-tolerant options utilized to full-length gasoline rods in Unit 2 at Plant Vogtle. “That is the third set that we’re truly putting in that could be a Westinghouse-developed accident tolerant gasoline, which additionally contains enrichments that exceed the historic limits of 5 weight %,” Chavers defined.
Going Past 5 Weight %
Chavers stated there are primarily three “buckets” of nuclear gasoline enrichments—the % composition of the isotope of U-235. “Low-enriched uranium, or LEU, is uranium that’s from pure as much as 5 weight %. Excessive-assay low-enriched uranium—HALEU loads of occasions it’s referred to—the authorized definition is 5 weight % to twenty%. After which above 20% is the fabric that’s used for nationwide protection functions, such because the Navy,” he stated.
“We’re truly moving into that HALEU space, however we’re staying on the very low finish of HALEU and referring to it as LEU+ in lots of phrases, as a result of we’re not going above 10% is what we count on for the present gentle water reactor fleet,” stated Chavers.
The advantages of going past conventional enrichment norms are important, not just for the present fleet, but additionally for brand spanking new reactors being developed inside the trade. “Lots of the superior reactors require HALEU gasoline—between 5% and 20%—and we’re making that first step with a legacy plant, which helps pave the way in which for the superior reactor group to put in that materials additionally,” Chavers stated.
The place gasoline enrichment ranges finally find yourself remains to be a subject of debate and should range primarily based on particular person plant circumstances. Chavers stated gasoline for present gentle water reactors will seemingly keep beneath 10 weight % U-235. “The most probably situation goes to be 6, 7, possibly 8%. There are economics right here, at which, the upper you go up, the extra the fabric will value us for enrichment providers. We’ve obtained to stability that out with the advantages we obtain from the elevated enrichment in our gasoline utilization or our power efficiency,” he stated.
The Advantages of ATF
Whereas enhanced security is probably essentially the most important profit supplied by ATF, superior nuclear gasoline can also be essential in reducing the price of electrical energy. “Our final purpose is to allow 24-month [refueling] cycles for all U.S. nuclear energy vegetation, to enhance the standard of life for our employees, to decrease the price of electrical energy,” stated Chavers.
“Essentially, [nuclear power] is a clear inexperienced energy supply—carbon-free. The extra we will preserve it working—that’s one thing we’re making an attempt to go after,” famous Chavers. “We see loads of positives on this program in that not solely are we enhancing security, reducing the fee, however we’re additionally growing the quantity of megawatts electrical we will get out of the nuclear belongings.”
To listen to the complete interview with Chavers, which comprises extra about ATF, the businesses concerned in its improvement, how collaboration is a key to success, the security implications of ATF, and its significance to future nuclear energy plant operations, take heed to The POWER Podcast. Click on on the SoundCloud participant beneath to hear in your browser now or use the next hyperlinks to achieve the present web page in your favourite podcast platform:
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—Aaron Larson is POWER’s govt editor (@AaronL_Power, @POWERmagazine).
