The POWER Interview: DOE’s Unique New Advanced Nuclear Reactor Test Beds
In October, the National Reactor Innovation Center (NRIC) kicked off a ceremony to repurpose the iconic Experimental Breeder Reactor-II (EBR-II) containment structure at Idaho National Laboratory (INL) as a new test bed for higher thermal power reactor projects.
Department of Energy (DOE) Assistant Secretary for Nuclear Energy Dr. Kathryn Huff shed more light on NRIC’s Demonstration of Microreactor Experiments (DOME), which is situated within INL’s Materials and Fuels Complex, along with the Laboratory for Operations and Testing in the U.S. (LOTUS), another test bed NRIC is designing and building at an INL site that once hosted an experimental reactor.
NRIC says DOME, which comprises an 80-foot concrete and steel edifice, is “flexible enough” to test four to five small modular reactors and can host microreactors up to 20 MWth that use high-assay low-enriched uranium (HALEU) fuels. The DOE recently picked three microreactor developers—Westinghouse, Radiant Nuclear, and Ultra Safe Nuclear Corp.—which will design the first experiments at DOME. (See the full story here: “DOE Picks Nuclear Designs for First Microreactor Experiments at INL’s New Test Bed.”) NRIC has now completed the final design for DOME and expects the facility to be ready for testing in 2026.
LOTUS will establish a Zero Physics Reactor (ZPRR) reactor cell as a Hazard Category 2 test bed with appropriate security controls to support testing of advanced reactor concepts (of up to 500 KWth) that use “highly enriched uranium and plutonium fuels.” Its first anticipated user may be the Molten Chloride Reactor Experiment (MCRE) being developed by Southern Co. and Terrapower. NRIC says it has completed the conceptual design of LOTUS, and it is expected to be operational as soon as the end of 2027.
POWER: What is DOME?
The Demonstration of Microreactor Experiments (DOME) is one of two new test beds being developed for fueled reactor tests at Idaho National Laboratory (INL). It will host microreactor tests generating up to 20 MWth. The test bed will provide the infrastructure where industry can test their concepts to generate data to support design verification and licensing activities.
The decommissioned Experimental Breeder Reactor-II (EBR-II) facility will be repurposed to support the DOME mission. The concept of DOME was introduced in 2020 in response to a gap assessment conducted by the National Reactor Innovation Center (NRIC) to identify national laboratory capabilities needed to enable advanced reactor testing and demonstration. DOME will have an approximately 78 ft diameter floor space to accommodate a shipping container-sized experiment. DOME will support testing of multiple reactors one experiment at a time, sequentially, approximately every 12 to 24 months.
POWER: What does repurposing EBR-II entail?
EBR-II was a 62.5-MWe reactor that operated for about 30 years inside a containment dome. Though EBR-II has been decommissioned, the containment structure is still in place. This containment facility will be repurposed to allow for testing of various advanced reactor concepts. Repurposing the EBR-II containment structure into DOME will include repairing and updating existing infrastructure, such as electrical, HVAC, mechanical, containment, and other support systems. By repurposing EBR-II, DOE is making use of existing infrastructure at a prime location central to the expertise of the Materials and Fuels Complex at the INL.
POWER: Will the DOE’s selections in October—Westinghouse, Radiant Nuclear, and Ultra Safe Nuclear Corp.—represent the first experiments at DOME?
This has not been decided yet. The three awardees will design experiments to operate in DOME. The awards will fund the experimental design process in collaboration with NRIC. Other reactor developers can choose to self-fund the front-end engineering and experiment design (FEEED) process and request to use DOME at any time. Based on design reviews and the maturity level of the experiment design, NRIC will establish a schedule for experiments to operate in DOME. The first could be as early as 2026.
POWER: How long would the experiments last? Is there an urgency to get them started and completed?
DOME is needed to spur the testing of advanced reactors by expediting the testing process and reducing overall project risk. Advanced reactor developers need to test their concepts to generate data to support design and licensing activities. The FEEED process will help confirm expected testing duration for each experiment. Developer testing campaigns and experiments are expected to run from as little as a few months to 24 months depending on the data they need to support their designs and the complexity of their tests. After operation is complete, the experiments will be decommissioned. The first could be as early as 2026.
POWER: Does DOE anticipate awarding more designs?
Possibly. Additional FEEED funding opportunities will depend on funding availability and interest from industry. There could also be opportunities for industry partners to work directly with NRIC to self-fund the FEEED process through a cooperative research and development agreement (CRADA) or strategic partnership project (SPP). Interested companies are welcome to contact NRIC for information on alternative mechanisms for conducting FEEED studies.
POWER: Where would LOTUS be sited? Also at EBR-II?
No. The Laboratory for Operations and Testing in the U.S. (LOTUS) is a separate test bed. Both test beds repurpose facilities that were originally built in the 1960s at the Materials and Fuels Complex at the INL site. Both LOTUS and DOME are being retrofitted to meet the demands of new technologies. LOTUS will repurpose a cell at the Zero Power Physics Reactor facility.
POWER: Why did the DOE consider these test bed capabilities essential? Why are they suited to these designs?
Advanced reactors offer many potential advantages such as improved efficiency and economics, relatively small physical footprints, reduced capital investment, ability to be sited in locations not possible for larger reactors, compatibility with renewable technologies, and provisions for incremental power additions. They also offer distinct safeguards, security, and nonproliferation advantages. DOE has a unique role to help offset early risks and support the development, demonstration, and commercialization of these innovative technologies. Both DOME and LOTUS help accomplish this goal by providing the necessary testing infrastructure needed to accelerate commercialization of advanced reactors.
Advanced reactor developers need to test their concepts to generate data to support design and licensing activities. It can be cost-prohibitive for private companies to construct their own testing facilities. These test beds are expected to defray the cost to build new containment structures and perform fueled reactor experiments for developers.
—Sonal Patel is a POWER senior associate editor (@sonalcpatel, @POWERmagazine).