NXE-Core: Application of the NXE Stability Framework to Nuclear Fuel Burnup Optimization

We present NXE-Core v4.3, an application of the NXE empirical stabilityframework to nuclear fuel burnup optimization in commercial light-waterreactors. The model is now accompanied by an interactive HTML simulatorand calibrated benchmark against typical PWR evolution. Through computational simulation on a 16×16 fuel cell lattice, wedemonstrate that modulating neutron flux according to NXE principlesenables active transmutation of U-238 into Pu-239. KEY FINDINGS:- Control protocol (PWR baseline): burnup stalls at ~8.2%, no Pu-239.- NXE-Shift protocol (optimized): 100% burnup, Pu-239 peak ~77%.- Stress-Test protocol: instant rupture, Γ → 2.0, full consumption in 36 pulses.- PWR calibrated benchmark: with flux=50, λ=0.05, C2=0.1 the model reproduces a complete fuel cycle (U-235 depletion, Pu-239 accumulation and subsequent fission), reaching 100% burnup in ~117 pulses. CONTENTS OF THIS REPOSITORY:- nxe_core_paper.py — original Python script generating all protocols and figures.- nxe_core_benchmark.py — extended script with calibrated PWR benchmark, CSV export, and comparative plots.- simulador_uranio_nxe.html — interactive browser-based simulator (no installation required) implementing the same NXE physics.- benchmark_results_calibrado.csv — time-series of isotopic composition, burnup (GWd/tU), Γ, κ, m_eff for the calibrated PWR case.- nxe_vs_pwr_summary.csv — qualitative comparison of NXE vs. typical PWR behaviour (Pu-239 rise, peak shape, depletion trends).- benchmark_plots_calibrado.png — isotopic evolution and Γ vs. burnup from the calibrated benchmark.- nxe_vs_pwr_comparison.png — side-by-side comparison of NXE and reference PWR curves (U-235, U-238, Pu-239).- protocolo_1_control.png, protocolo_2_nxe_shift.png, protocolo_3_stress_test.png, comparativa_burnup.png — Pre-generated figures from the original three protocols. CALIBRATION DETAILS:To approximate a real PWR cycle, the benchmark uses LAMBDA_QCD = 0.05(close to the initial eigenvalue of U-238 cells), high flux (50) andstrong coupling (C2=0.1, BETA0=1.0). This produces a gradual burnupcurve with a Pu-239 peak, followed by complete consumption. The mappingfrom simulation pulses to burnup (GWd/tU) is included in the CSV. ROADMAP FOR EXPERIMENTAL VALIDATION (unchanged):(1) coupled simulations with MCNP/FRAPCON, (2) research reactorirradiation tests, (3) single commercial fuel assembly validation,(4) full core deployment. All code is provided with a fixed random seed (2026) for exactreproducibility. The interactive HTML tool allows real-time explorationof parameter space without any local setup.