Abstract
A high-fidelity neutronics model of the Oak Ridge National Laboratory High Flux Isotope Reactor (HFIR) with a representative core and experiment loading was developed to serve as the new basis for performance and safety basis assessments. HFIR provides one of the highest steady-state neutron fluxes of any research reactor in the world to support high-impact applied and basic neutron science research. The newly developed model better characterizes ongoing and envisioned research activities at HFIR, in comparison to the legacy Cycle 400 (operated in 2004) model. The new reactor model serves as the reference for safety basis, reactor operation, in-core experiment, reactor upgrade, and other research activities. It also serves as the reference for high-enriched uranium to low-enriched uranium conversion studies, enabling consistent performance and safety metrics comparisons. Neutronic performance and safety metrics calculational methods and results including, but not limited to, cycle length estimates, flux and fission distributions, point kinetics data, reactivity coefficients, intra cycle and post shutdown source terms, and control element worths are documented herein. These neutronics results provide essential input to higher accuracy follow-on heat deposition, thermal–hydraulic, thermal-structural, reactor transient, and severe accident analyses and directly support safety analysis upgrades, startup and operations calculations, and fuel storage and transportation evaluations. Furthermore, thermal–hydraulic safety limit calculations for inlet coolant temperature, flux-to-flow, and inlet vessel pressure that utilized the neutronics results obtained with the new reactor model are discussed herein. The use of the new neutronics results led to a significant gain in thermal safety margin and enabled the removal of previous conservatism based on low-fidelity calculations.
| Original language | English |
|---|---|
| Article number | 110752 |
| Journal | Nuclear Engineering and Design |
| Volume | 366 |
| DOIs | |
| State | Published - Sep 2020 |
Funding
ORNL is funded by the US Department of Energy (DOE) National Nuclear Security Administration’s Office of Material Management and Minimization to evaluate the conversion of HFIR’s fuel from HEU to LEU as part of the effort to reduce the enrichment used in research reactors in support of international nuclear nonproliferation objectives. HFIR is one of the five US high-performance research reactors currently evaluating conversion; the other four include the Advanced Test Reactor at the Idaho National Laboratory, the National Bureau of Standards Reactor at the National Institute of Standards and Technology, the Massachusetts Institute of Technology Reactor at the Massachusetts Institute of Technology, and the University of Missouri Research Reactor at the University of Missouri. The authors would like to acknowledge the support and funding for this work that was provided by the ORNL Research Reactors Division, which itself is funded by the US DOE Office of Science , and the US DOE National Nuclear Security Administration’s Office of Material Management and Minimization . This material is based upon work supported by the US DOE, Office of Science, Basic Energy Sciences under contract number DE-AC05-00OR22725. The authors would like to thank Kara Godsey and Charles Daily of ORNL for their technical review of this manuscript. The authors would like to acknowledge the support and funding for this work that was provided by the ORNL Research Reactors Division, which itself is funded by the US DOE Office of Science, and the US DOE National Nuclear Security Administration's Office of Material Management and Minimization. This material is based upon work supported by the US DOE, Office of Science, Basic Energy Sciences under contract number DE-AC05-00OR22725. The authors would like to thank Kara Godsey and Charles Daily of ORNL for their technical review of this manuscript.
Keywords
- Depletion
- High Flux Isotope Reactor
- Neutronics
- Reactor physics
- Research reactor
- Thermal-hydraulics