DOD Advances X-Energy Mobile Nuclear Microreactor as Second Project Pele Design

The Department of Defense (DOD) has moved to develop a second transportable microreactor under Project Pele, granting X-energy a contract option to advance the design of its mobile advanced nuclear microreactor prototype.

The one-year contract option will continue to provide funding for X-energy’s nuclear technology development, allowing the firm to develop its design to meet the DOD’s Project Pele technical requirements, the federal agency said on Sept. 13. On Sept. 15, X-energy confirmed it signed an agreement with the DOD under a federal initiative, but it noted that the agreement expands an existing contract with the agency to advance its prototype through a $17.49 million award.

Project Pele stems from the 2019 National Defense Authorization Act, in which Congress directed the DOD and the Department of Energy (DOE) to develop a plan to design, build, and test a microreactor at a DOD installation no later than December 2027. When the DOD’s Strategic Capabilities Office (SCO) formally released a record of decision (ROD) to proceed with the program in April 2022, it said it would pursue a  high-temperature gas-cooled (HTGR) mobile microreactor that will be capable of producing 1 MWe to 5 MWe for more than three years without refueling. The SCO considered two engineering designs selected as part of a preliminary design competition, which wrapped up in March 2021: an HTGR design from BWXT Advanced Technologies and X-energy’s Mobile Nuclear Power Plant.

Microreactors—small nuclear reactors that produce up to 20 MW of electricity or equivalent amounts of heat—are designed for small applications away from the centralized electric grid such as remote communities and military bases. Source: INL

The DOD in June 2022 ultimately picked BWXT’s microreactor, a selection that implied the much-watched contest to build what could be the nation’s first advanced microreactor was closed. On Wednesday, however, the SCO said the contract option extended to X-energy could provide future optionality. “Due to their extraordinary energy density, nuclear reactors have the potential to serve multiple critical functions for meeting resiliency needs in contested logistical environments,” said Dr. Jeff Waksman, Project Pele program manager. “By developing two unique designs, we will provide the Services with a broad range of options as they consider potential uses of nuclear power for both Installation and Operational energy applications in the near future.”

The SCO, however, clarified that the contract option “will not result in a completed engineering design,” though it will allow a “thorough analysis of design options, leading to a Preliminary Engineering Design and initiation of a regulatory pre-application process.”

X-Energy Expects to Advance Its Prototype Design

According to Project Pele’s final environmental impact statement, which the DOD made public in February 2022 prior to its ROD, X-energy proposed a “Mobile Nuclear Power Plant” concept that will employ a TRISO-fueled reactor coupled to a high-reliability power conversion system—“each contained in separate ISO-compliant containers to achieve maximum siting flexibility, limit hardware activation, and improve maintainability.” 

X-energy in 2020 revealed it was working on a 7-MWe “Xe-Mobile power generation system,” which will use X-energy’s proprietary TRISO-X fuel. However, the company has not publicly disclosed its Project Pele concept.

An X-energy spokesperson on Thursday told POWER that the company is currently focusing its mobile microreactor work “around one practical, cost-effective microreactor that can be deployed for use in remote military locations as well as commercial or industrial use.” X-energy’s transportable microreactor “is designed to generate in the range of 3 to 5 MW and is differentiated to be cost-competitive with remote diesel power. The microreactor is designed to use TRISO-based fuel,” he said.

On Friday, Harlan Bowers, X-energy president, who led a project team during the initial phase of Project Pele work, said the company will draw from the “tremendous” experience it gained from DOD subject matter experts during the first phase.

“We intend to build on the knowledge and experience from the first phase of work to create a clean, practical, and cost-effective microreactor to be competitive with fossil fuel-based power generation used today,” he said. “We expect this next phase of work to include the refining of our design, prototype testing, and initiation of reviews with the U.S Nuclear Regulatory Commission [NRC] to ensure our microreactor meets safety standards and can be licensed for civilian use in the U.S.” Pre-licensing engagement with the NRC will “enable a broad range of deployment possibilities to decarbonize off-grid, remote, or small-scale grid resiliency needs,” the company added.

The technology firm’s more prominently known offering is its larger 80-MWe (200-MWth) Xe-100 design. The company is notably slated to demonstrate a proposed four-unit 320-MWe Xe-100 advanced nuclear reactor facility at a Dow chemical materials manufacturing site in Seadrift, Calhoun County, Texas, as part of the DOE’s Advanced Reactor Demonstration Program (ARDP).

Dow and X-energy are preparing a construction permit application for submittal to the NRC, and plant construction could begin in 2026. The firm in October 2022, meanwhile, kicked off construction of its TRISO-X Fuel Fabrication Facility (TF3) in Oak Ridge, Tennessee, targeting a commercial operational date in 2025.

DOD’s Second Major Microreactor Announcement In a Month

The SCO’s announcement comes on the heels of the U.S. Air Force’s selection of Oklo’s Aurora Powerhouse—a liquid metal-cooled fast reactor—for a nuclear microreactor pilot at Eielson Air Force Base in Alaska. The Air Force’s Micro-Reactor Pilot Program, which also responds to a 2019 National Defense Authorization Act requirement, seeks to build and operate at least one licensed microreactor by Dec. 31, 2027.

The Air Force, however, is exploring a different approach. Oklo will site, design, build, own, and commercially operate the stationary microreactor, while the Air Force will execute a land lease and the 30-year fixed price power purchase agreement with Oklo once the nuclear technology firm obtains a combined operating license from the NRC.

BWXT, meanwhile, has said its Project Pele transportable design “consists of multiple modules that contain the microreactor’s components in 20-foot long, ISO-compliant CONEX shipping containers.” In addition, the reactor is designed to be safely and rapidly moved by road, rail, sea, or air.

“The entire reactor system is designed to be assembled on-site and operational within 72 hours. Shut down, cool down, disconnection, and removal for transport is designed to occur in less than seven days,” it said. BWXT’s transportable reactor core and associated control system are pivotally designed to maintain safety “under all conditions, including transitional conditions throughout transport,” it added. These attributes meet the DOD’s specifications, it said.

Reactor fuel for the Project Pele demonstration is slated to be produced from DOE of highly enriched uranium (HEU) currently stored at the Y–12 National Security Complex in Oak Ridge, Tennessee, the DOD’s 2022 ROD noted. The fuel will be converted from a metal to an oxide at BWXT Technologies’ Nuclear Fuel Services facility in Erwin, Tennessee, and then downblended to high-assay low-enriched uranium (HALEU) and fabricated into tristructural isotropic (TRISO) reactor fuel at the BWXT facility in Lynchburg, Virginia.

Artist’s rendering of BWXT’s Project Pele transportable reactor modules arriving for set up and operation. Courtesy: BWX Technologies

BWXT Project Pele Project Readying for Delivery in 2025

During a webinar hosted by the American Nuclear Society (ANS) on Aug. 2, BWXT Advanced Technologies President Joseph Miller noted work is underway at its Lynchburg facility to ready the microreactor for a minimum three-year period of testing at Idaho National Laboratory (INL) in 2025.

Waksman, who heads up the SCO’s Project Pele, during the webinar said the BWXT DOD project is now in the “final bits of the design phase” in preparation for final approval by the DOE, which acts as the project’s “regulator.” SCO’s current schedule is to have the final design approved by the DOE by the spring.

After the DOE signs off, he said, SCO will assemble the reactors in Lynchburg over the course of 2024. “And if all goes according to schedule, by early 2025, we will have shipped the reactor to INL, where it will be fueled. It will then be shipped out to the desert, to a location we have selected to do the initial testing,” he said. “After we operate the reactor, we will then demonstrate this transportable reactor down, putting it on a truck, driving it around a bit, putting it back up again, and turning it back up again.”

The microreactor’s development is tailored to DOD purposes, largely focused on three applications: providing remote power; offsetting fossil fuels for strategic and operational advantages; and ensuring resilience. “Our reliance on long and vulnerable fossil fuel lines is a huge problem from a military perspective, so having power that does not require refueling for days or months or even years would be a huge advantage for us,” Waksman said.

Waksman, however, added that the DOD’s efforts could prove fruitful for larger industrialization. “Our plan from the start has always been that we want to build reactors that can have commercial spin-offs so that we can get the number of reactors coming off the assembly line to be enough that it will be cost-competitive,” he said.

Sonal Patel is a POWER senior associate editor (@sonalcpatel@POWERmagazine).

Editor’s Note: This story was substantially updated on Friday, Sept. 15, adding X-energy’s comments, details about the DOD’s award value, and project specifics.

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