TY - JOUR
T1 - Microreactor Applications, Research, Validation, and Evaluation (MARVEL) Demonstration
T2 - Mission and Design Evolution
AU - Abou-Jaoude, Abdalla
AU - Jackson, John
AU - Johnson, Justin
AU - Baily, Carl
N1 - Publisher Copyright:
© This material is published by permission of the Battelle Energy Alliance, LLC, for the U.S. Department of Energy under Contract No. DEAC07-05ID14517. The US Government retains for itself, and others acting on its behalf, a paid-up, non-exclusive, and irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.
PY - 2026/5/21
Y1 - 2026/5/21
N2 - Under the auspices of the U.S. Department of Energy’s Microreactor Program, the Microreactor Applications, Research, Validation, and Evaluation (MARVEL) reactor has been designed by Idaho National Laboratory (INL) for construction and operation at INL, affording a unique opportunity to discuss its overall design maturation in an open forum and to share key lessons learned with the broader nuclear community. MARVEL is a small, fully functional advanced reactor that utilizes uranium zirconium hydride fuel and generates a thermal output of 85 kW(thermal). It represents a unique opportunity for scaled demonstrations that may dramatically accelerate the design, licensing, and deployment of commercial microreactors for power production or process heat applications. The design activities were kicked off in 2020, with the reactor system achieving 90% design completion in September 2023. In early 2024, it finished undergoing an independent project assessment, and later that year its preliminary documented safety assessment was submitted. In 2025, the balance of plant was modified to incorporate findings from the nonnuclear 1:1-scale engineering demonstration unit (EDU), also referred to as the Primary Coolant Apparatus Test. Fabrication of long-lead components and fuel, the safety analysis review, and procurement for construction are already underway. Assembly and construction of MARVEL is expected to begin in 2026, with fuel loading expected in 2027. Initial criticality will be performed in a dry condition in late 2027, followed by loading of sodium-potassium coolant and startup testing. Approximately 6 months thereafter, release for unrestricted operations will enable subsequent testing of microreactor characteristics, microgrid integration, and select heat extraction applications. This article provides an overview of the microreactor’s evolution throughout its design lifecycle. Findings obtained from the operation of the EDU, the manufacturability assessment, and the start of fabrication were all incorporated into the design.
AB - Under the auspices of the U.S. Department of Energy’s Microreactor Program, the Microreactor Applications, Research, Validation, and Evaluation (MARVEL) reactor has been designed by Idaho National Laboratory (INL) for construction and operation at INL, affording a unique opportunity to discuss its overall design maturation in an open forum and to share key lessons learned with the broader nuclear community. MARVEL is a small, fully functional advanced reactor that utilizes uranium zirconium hydride fuel and generates a thermal output of 85 kW(thermal). It represents a unique opportunity for scaled demonstrations that may dramatically accelerate the design, licensing, and deployment of commercial microreactors for power production or process heat applications. The design activities were kicked off in 2020, with the reactor system achieving 90% design completion in September 2023. In early 2024, it finished undergoing an independent project assessment, and later that year its preliminary documented safety assessment was submitted. In 2025, the balance of plant was modified to incorporate findings from the nonnuclear 1:1-scale engineering demonstration unit (EDU), also referred to as the Primary Coolant Apparatus Test. Fabrication of long-lead components and fuel, the safety analysis review, and procurement for construction are already underway. Assembly and construction of MARVEL is expected to begin in 2026, with fuel loading expected in 2027. Initial criticality will be performed in a dry condition in late 2027, followed by loading of sodium-potassium coolant and startup testing. Approximately 6 months thereafter, release for unrestricted operations will enable subsequent testing of microreactor characteristics, microgrid integration, and select heat extraction applications. This article provides an overview of the microreactor’s evolution throughout its design lifecycle. Findings obtained from the operation of the EDU, the manufacturability assessment, and the start of fabrication were all incorporated into the design.
KW - advanced reactor
KW - liquid metal
KW - Microreactor
KW - reactor design
UR - https://www.scopus.com/pages/publications/105039948741
U2 - 10.1080/00295450.2026.2644118
DO - 10.1080/00295450.2026.2644118
M3 - Article
AN - SCOPUS:105039948741
SN - 0029-5450
SP - 1
EP - 21
JO - Nuclear Technology
JF - Nuclear Technology
ER -