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Division Spotlight
Nuclear Installations Safety
Devoted specifically to the safety of nuclear installations and the health and safety of the public, this division seeks a better understanding of the role of safety in the design, construction and operation of nuclear installation facilities. The division also promotes engineering and scientific technology advancement associated with the safety of such facilities.
Meeting Spotlight
2024 ANS Winter Conference and Expo
November 17–21, 2024
Orlando, FL|Renaissance Orlando at SeaWorld
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Latest News
NRC okays construction permits for Hermes 2 test facility
The Nuclear Regulatory Commission announced yesterday that it has directed staff to issue construction permits to Kairos Power for the company's proposed Hermes 2 nonpower test reactor facility to be built at the Heritage Center Industrial Park in Oak Ridge, Tenn. The permits authorize Kairos to build a facility with two 35-MWt test reactors that would use molten salt to cool the reactor cores.
Adam Zabriskie, Sebastian Schunert, Daniel Schwen, Javier Ortensi, Benjamin Baker, Yaqi Wang, Vincent Laboure, Mark DeHart, Wade Marcum
Nuclear Science and Engineering | Volume 193 | Number 4 | April 2019 | Pages 368-387
Technical Paper | doi.org/10.1080/00295639.2018.1528802
Articles are hosted by Taylor and Francis Online.
The restart of the Transient Reactor Test facility (TREAT) will once again provide the capability for rapid transient testing of fuel concepts. Under the auspices of the U.S. Department of Energy’s Office of Material Management and Minimization, research is underway to assess the feasibility of converting the current high-enriched uranium (HEU) fuel in TREAT to low-enriched uranium (LEU) fuel. The LEU concept retains the fuel process that results in micrometer-sized UO2 fuel grains dispersed in a graphite moderator matrix. The LEU fuel design includes more 238U, which fundamentally changes the feedback mechanisms in the fuel. To explore the effects of conversion on a pulse transient, a simplified semi-infinite TREAT fuel element model of both the HEU and proposed LEU configurations was simulated using MAMMOTH with the requisite multiscale and multiphysics coupling. The developed method incorporates fission energy deposition at microscale locations from the Mesoscale Atomistic Glue Program for Integrated Execution (Magpie), heterogeneity effects from the microscale model in the form of time lag, and independent feedback temperature sources from the microscale fuel grain model and surrounding moderator. The fuel grain size was varied along with temperature feedback sources to explore the feedback mechanisms. Significant differences between fuel and graphite temperatures were found to develop for transients with large energy depositions, for large fuel grains, and for fission-fragment irradiated graphite. These differences in temperature do not influence the feedback for HEU fuel but have a significant effect on LEU fuel. The difference between HEU and LEU fuel is caused by the fuel temperature feedback coefficient for LEU fuel that is roughly 20% of the graphite temperature feedback coefficient. The immediate equilibrium assumption is invalid for LEU fuel in certain TREAT operating regimes. As the conversion of TREAT to LEU fuel aims to conserve HEU capabilities, MAMMOTH simulations of the LEU model explore the effects of matching the same period, peak power density, and deposited energy of the HEU model. The same pulse shape was not achievable due to the feedback mechanism changes.
