ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
2026 Nuclear Energy Conference & Expo (NECX)
August 24–27, 2026
Dallas, TX|Hilton Anatole
Latest Magazine Issues
Jun 2026
Jan 2026
2026
Latest Journal Issues
Nuclear Science and Engineering
July 2026
Nuclear Technology
June 2026
Fusion Science and Technology
May 2026
Latest News
Antares achieves zero-power criticality at INL
Leveraging more than $140 million in private capital fundraising, over 322,000 square feet of operational manufacturing space, and multifaceted partnerships with the Departments of Energy and Defense, reactor start-up Antares has become the first company involved in the Reactor Pilot Program to achieve zero-power fueled criticality—a full month ahead of the July 4 deadline set by President Trump’s Executive Order 14301.
This milestone, announced yesterday, was achieved with the company’s Mark-0: a sodium heat-pipe-cooled, TRISO-fueled microreactor. The Mark-0 is a forerunner to the company’s flagship design, which it calls the R1. For Antares, this development represents a key validation of its reactor physics, control systems, and supply chain.
S. K. Combs, L. R. Baylor, C. R. Foust, A. Frattolillo, M. S. Lyttle, S. J. Meitner, S. Migliori
Fusion Science and Technology | Volume 68 | Number 2 | September 2015 | Pages 319-325
Technical Paper | Proceedings of TOFE-2014 | doi.org/10.13182/FST14-925
Articles are hosted by Taylor and Francis Online.
An existing pipe gun test facility at ORNL was used for an experimental study of propellant gas loads required for ITER-relevant pellet injection, with the key objective of determining the minimal amount of gas required for optimal pellet speeds. Two pellet sizes were tested, with nominal 4.4 and 3.2 mm diameters comparable to pellets planned for fueling and ELM pacing in ITER, respectively. A novel scheme was used to freeze solid pellets from room temperature gas; this facilitated operations at higher temperatures (14.5 to 16.5 K, similar to those planned for extruder operations for ITER pellet injectors) and thus lower pellet breakaway pressures and gas loads. Most of the single-shot D2 pellet tests were carried out with a relatively low H2 propellant gas load of ~0.0133 bar-L. Some limited testing was also carried out with a mixed propellant gas that consisted mostly of D2, which is more representative of the gas that will be used for ITER pellet injection. In testing it was found that this reference gas load resulted in pellet speeds in close proximity to a speed limit (~300 m/s) previously determined in a series of tests with D2 pellets shot through a mock-up of the curved guide tubes planned for the ITER installation (for pellet fueling from the magnetic high-field side). The equipment, operations, and test results are presented and discussed, with emphasis on the relevance for ITER operations.