Project Pele will “nurture” a second microreactor: X-energy’s Xe-Mobile

September 14, 2023, 3:06PMNuclear News

The Department of Defense announced on September 13 that it has awarded a contract option to X-energy for the “enhanced engineering design” of a microreactor that could serve as the transportable power source envisioned by the Strategic Capabilities Office’s (SCO) Project Pele. The DOD expects the award for one year of work to “allow a thorough analysis of design options,” resulting in a preliminary engineering design and “initiation of a regulatory preapplication process.”

“The Strategic Capabilities Office specializes in adapting commercial technology for military purposes,” said SCO director Jay Dryer. “By nurturing and developing multiple microreactor designs, SCO will not just provide options for the military services but will also help jumpstart a truly competitive commercial marketplace for microreactors.”

Project Pele background: A small, transportable nuclear reactor could address the DOD’s growing energy demands as a resilient, carbon-free energy source to support mission-critical operations in remote and austere environments. That was the vision described in a request for solutions issued by the SCO back in April 2019.

Three companies initially received contracts in March 2020: BWX Technologies, Westinghouse, and X-energy. In March 2021, the DOD announced that it had selected two of three teams (BWXT and X-energy) to move ahead with the development of a final design of a prototype mobile microreactor capable of producing 1–5 MWe (a reduction from the initial project specifications, which called for a reactor that could produce 1–10 MWe).

In April 2022, when the SCO released a record of decision for Project Pele, covering the design, build, transportation, and operation of a mobile microreactor at Idaho National Laboratory, that decision was based on a final environmental impact statement prepared to fit the designs from both candidate vendors at the time—BWXT and X-energy.

The ROD said in part, “SCO has full confidence that both teams have developed reactor designs which can be constructed to meet SCO’s minimum technical requirements. However, only one design will be selected and announced later this spring. The Pele reactor is to be a single prototype, which will be demonstrated only within the United States, under the safety oversight of the Department of Energy. A decision by the DOD on whether or not to transition the technology and to use it operationally will be made at a future date.”

In June 2022, the SCO selected BWXT to build a prototype microreactor.

The X-energy option: Project Pele manufacturing work is now underway, and it is not clear when the SCO decided to issue the additional contract option to X-energy, announced yesterday. X-energy has already performed two years of work under contract, and the additional one year of work will not result in a completed engineering design, according to the DOD’s announcement.

The announcement states: “By executing this contract option with X-energy, the SCO seeks to develop a complementary microreactor design that builds upon X-energy's developments completed under Project Pele in 2022. This option continues funding for X-energy to develop its design to meet the technical requirements of Project Pele, targeting a reactor design which is ready for licensing by the Nuclear Regulatory Commission for both commercial ventures and military resiliency.”

“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 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.”

Xe-Mobile specs: The DOD announcement does not mention X-energy’s Xe-Mobile design by name. However, X-energy’s website says the company “was selected through a competitive procurement to complete our design with specialized capabilities for the military.” The resulting Xe-Mobile design is capable of producing of 2–7 MWe of electrical power at full-power operations for over three years; can be transported by rail, truck, and sea in components housed in cargo containers; would use TRISO fuel; and provides multiple voltage outputs.

“We have developed one of the most advanced and feasible micro-mobile nuclear reactor solutions in the world an important step forward for clean energy innovation and leadership,” said Brad Rearden, director of X-energy’s government R&D division.

Update on BWXT’s Project Pele: Waksman participated in an ANS webinar in early August to provide an update on Project Pele together with Joe Miller, president of BWXT Advanced Technologies. While Waksman did not mention plans to contract with X-energy or to make further investments in any other microreactor designs, he did say during the webinar, “Our plan from the start for Project Pele 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'll be cost competitive.”

Waksman also said that the team working on BWXT’s Project Pele design was in “the final bits of the design phase,” and hoped “to have the final design approved by the Department of Energy by the spring.” If the project stays on schedule, he said, “by early 2025 we will have shipped the reactor to Idaho National Laboratory. At Idaho, it will then be fueled [and] shipped out to the desert to a location that we have selected to do the initial testing. The reactor will then go through a final operational readiness review, and if all—again—goes according to schedule, we will be able to turn the reactor on before the end of calendar year 2025.”

And then there were four: The DOD is supporting the development of four different reactors, all on the micro scale: BWXT’s Project Pele design (selected for demonstration in June 2022), X-energy’s Project Pele design (selected for engineering design work in September 2023), Oklo’s Aurora (tentatively selected for Alaska’s Eielson Air Force Base in August 2023), and DRACO—the Demonstration Rocket for Agile Cislunar Operations (BWXT was selected to manufacture the custom space-bound reactor in July 2023).


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