Vogtle 2 Installs World’s First Full Accident-Tolerant Fuel Assemblies
Credit to Author: Sonal Patel| Date: Fri, 05 Apr 2019 22:45:46 +0000
The world’s first complete advanced fuel test assemblies containing accident-tolerant fuel (ATF) have been installed at Southern Co.’s Alvin W. Vogtle Electric Generating Plant’s Unit 2 in Georgia.
Nuclear giant Framatome delivered the GAIA lead fuel assemblies containing enhanced ATF (EATF), including both pellets and cladding, to the plant owned by Georgia Power in January. Southern Nuclear, a Southern Co. subsidiary that operates the plant, installed the assemblies during the unit’s spring refueling outage that began on March 10 and ended April 3.
According to John Williams, Southern Nuclear fuel and analysis director, installation of the ATF assemblies marks a significant advancement in the potential commercial deployment of ATF technology. “This innovative technology is expected to enhance the plant’s already robust safety performance, as well as potentially lower plant operating costs,” he said April 5. “The safety and health of our customers and our employees is always our top priority, and we will continue to pursue innovations that enhance safety and offer more operational flexibility.”
Framatome, too, celebrated the milestone. Lionel Gaiffe, senior executive vice president at Framatome’s Fuel Business Unit, applauded Southern Nuclear’s “consistent support of EATF initiatives,” noting the company was “pleased to deploy an economical advanced fuel technology that offers operators additional response time and greater operational flexibility.”
Chromia-enhanced fuel pellets have a small amount of Cr2O3, or chromia, added to the current industry standard uranium dioxide (UO2) powder. This addition changes some properties of the fuel pellets to improve performance under accident conditions. Courtesy: Framatome
Accident-Tolerant Fuel Is Promising
ATF is an industry concept used to describe new technologies—in the form of new cladding and/or fuel pellet designs—that further enhance the safety and performance of nuclear materials. While ATF technologies have been under development since the early 2000s, they have received a marked boost in the wake of the Fukushima accident in March 2011 as the U.S. Department of Energy (DOE) aggressively implemented plans under its congressionally mandated EATF program to develop ATFs for existing light water reactors.
The program today casts a wide net of collaboration that includes several U.S. utilities, universities, and the Electric Power Research Institute (EPRI). The DOE has provided funding and technical backing for advanced ATF fuels concepts—including for fuel pellet and cladding materials. Concepts are under development by GE’s Global Nuclear Fuel (GNF), Westinghouse, and Framatome.
(For more, see, “Accident-Tolerant Fuels Could Be a Boon for Nuclear Industry” in POWER’s April 2018 issue.)
In March 2018, Southern Nuclear installed test ATF assemblies containing fuel segments made by GNF at the Edwin I. Hatch Nuclear Plant in southeastern Georgia. That test, which will assess iron-chromium-aluminum fuel cladding material known as “IronClad” and coated zirconium fuel cladding known as “ARMOR,” is slated to end in March 2020.
At Vogtle 2, Southern Nuclear plans to test Framatome’s EATF concept, which it helped developed under Framatome’s PROtect program, for 18 months, until the next refueling outage. The assemblies feature Framatome’s advanced chromium coating, which is added to M5 zirconium alloy cladding. The combination “improves high-temperature oxidation resistance and reduces hydrogen generation during loss of cooling,” the company explained. “The chromium coating also greatly reduces creep to maintain a coolable geometry and has mechanical properties that allow for more operator response time. Further, the innovative coating offers increased resistance to debris fretting during normal operations.”
But the assemblies also include chromic-enhanced fuel pellets, which “have a higher density, reduced fission gas release, and improved behavior during loss of cooling. Reduced Pellet Clad Interaction (PCI) also better supports power maneuvering,” Framatome added.
Technical Triumph Through International Collaboration
Framatome, which fabricated the fuel assemblies at its fuel manufacturing facility in Richland, Washington, as part of a 2017 contract with Southern Nuclear, said it worked for several years with the DOE’s EATF program, to “significantly improve” on its initial target to deploy the concept by 2022. The company is in tandem also expanding development efforts on its silicon carbide cladding concepts.
The DOE in January awarded GNF, Westinghouse, and Framatome $111.2 million through January 2021 to boost ATF development—with stiff requirements. During the first 14-month budget period, all three vendors must ensure an initial lead test assembly has been installed in a U.S. commercial power plant, and that prototypic pin segments have been installed in the Idaho National Laboratory’s Advanced Test Reactor’s (ATR) water loop. If Congress approves it, the agency is planning to provide an additional $55.6 million to the three developers in fiscal year 2020 and $30 million in fiscal year 2021 to continue ATF development. With those funds, “the vendors will expand operation of ATF-related concepts in DOE facilities—INL ATR, INL Transient Reactor Test (TREAT) facility, and out-of-pile tests—and commercial reactors with prototypic segments and rods,” the DOE said. “The companies would be expected to have agreed-upon licensing plans developed for future NRC approval for initial partial core loadings into commercial nuclear power plants during the mid-2020s.”
Framatome also credits European partners, including France’s Atomic Energy Commission, for initially exploring and identifying a suitable cladding coating process. Technology collaborators also include French utility EDF, which owns 75% of Framatome (Mitsubishi Heavy Industries owns 19.5%, and international engineering firm Assystem, the remaining 5%). Framatome also noted a series of research and development projects at Gösgen nuclear power plant in Switzerland helped develop new methodologies, irradiation capabilities, and equipment to support innovative fuel and cladding material characterization, which were applied to the EATF materials.
—Sonal Patel is a POWER associate editor (spatel@powermag.com, @POWERmagazine.com)
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