Monte Carlo simulations map neutron spectra in U-C and Th-C media for traveling wave reactor concepts
Preprint simulations identify lattice and absorber combinations that produce thermal, superthermal, or soft-fast neutron spectra in U-C and Th-C fission media. Findings support conceptual traveling-wave reactor designs but remain unvalidated by experiment. Evidence consists solely of Monte Carlo runs without burnup or feedback modeling.
The preprint reports Monte Carlo runs comparing homogeneous UC2 and UO2 media against channel-type heterogeneous U-C and Th-C lattices with varied pitches and burnable absorbers. Homogeneous dicarbide spectra peaked between 20 and 50 keV; heterogeneous thorium-carbon arrangements thermalized neutrons fully while uranium-carbon designs allowed superthermal shaping through cadmium or indium doping.
These results target traveling-wave fission concepts that rely on controlled spectrum softening without external enrichment cycling. The work connects to earlier traveling-wave reactor proposals by identifying concrete lattice parameters that could support either fast-soft or thermal modes in a single-channel geometry.
A key limitation is the absence of experimental benchmarks or coupled burnup calculations, leaving reactivity feedback and material evolution untested. Validation would require critical-assembly measurements and full-core depletion studies before any prototype claims.
Next steps include irradiation tests of candidate channel geometries and integration with burnup codes to assess long-term spectrum stability under realistic power densities.
Tarasov group: Critical-assembly measurements confirming the predicted 1-20 eV superthermal spectrum in a Cd-doped U-C lattice will appear in a peer-reviewed journal within 48 months if funding is obtained.
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2609.26798)
- [2]Supporting Source(https://doi.org/10.1016/j.anucene.2020.107689)