Contact Author:
Dr. Pavel V. Tsvetkov
tsvetkov@tamu.edu
P:(979) 845-7078
F:(979) 845-6443
129 Zachry Engineering Center, 3133 TAMU
College Station, TX 77843-3133
USA
Coupled Hybrid Monte Carlo - Deterministic Analysis of VHTR Configurations with Advanced Actinide Fuels
Pavel V. Tsvetkov (Texas A&M University)
Partitioning and transmutation of minor actinides (MA) is expected to have a positive impact on the future of nuclear technology since it incinerates hazardous nuclides and potentially provides additional fuel supply. The objective of the U.S. DOE University NERI Project is to assess the possibility, advantages and limitations of achieving ultra-long life VHTR (Very High Temperature Reactor) configurations by utilizing minor actinides as a fuel component. The analysis takes into consideration and compares capabilities of pebble-bed and prismatic core designs with advanced actinide fuels to approach the reactor lifetime long operation without intermediate refueling. The ultra-long life VHTR systems are developed and analyzed focusing on control, dynamics, safety, and proliferation-resistance during reactor lifetime long autonomous operation. The principal mechanism being envisioned to achieve ultra-long life systems is an enhanced involvement of self-generated fissile compositions based on spent LWR fuel to the energy generation process. Depending on neutron spectra in the considered core configurations, neptunium, americium and curium may serve as burnable poisons or fuel materials contributing to small reactivity swings (self-stabilization) over prolonged irradiation periods yielding high levels of burn-up. Utilization of minor actinides as a fuel component would facilitate development of new fuel cycles and support sustainability of a fuel source for nuclear energy assuring future operation of Generation IV nuclear energy systems. Within the computational scheme, the key technical issues are being addressed and resolved by implementing efficient automated modeling procedures and sequences, combining continuous energy Monte Carlo and multigroup Monte Carlo and deterministic approaches, developing and applying realistic 3D coupled neutronics-thermal-hydraulics models with multi-heterogeneity treatments, developing and performing experimental/computational benchmarks for model verification and validation, analyzing uncertainty effects and error propagation. To assure comprehensive, realistic assessment of the VHTR design and operation targeting passive safety confirmation, the adequacy of computational methods and models used to compute performance characteristics must be supported by comparisons with experimental data covering an appropriate range of conditions. Validation data are available from power reactors as well as past critical experiments. The results describe performance of the entire VHTR power unit and allow conclusions regarding the configuration’s feasibility, performance and possible directions for further analysis and development. Presented up-to-date results are in agreement with the available data and confirm the chosen approach. Studies of VHTRs with MAs suggest promising performance.