5050b9e71e
Scram PJ reach from the bounding-box union of: - hot-standby box (mode_boundaries.q_shutdown) - heatup-tight reach envelope (results/reach_heatup_pj_tight.mat) - operation-LQR reach envelope (results/reach_operation_result.mat) - LOCA operation envelope (results/reach_loca_operation.mat, 3s) with precursor + temperature outliers clamped to physical bounds. Results at probe horizons: T=10s: 10890 sets in 480s wall — n ∈ [-8e-4, 0.047] T_c [231, 362] T=30s: 16925 sets in 2892s wall — n ∈ [-4e-4, 0.021] T_c [229, 361] T=60s: 23919 sets in 705s wall — n ∈ [-2e-4, 0.009] T_c [226, 359] Monotone n decay, factor-of-5-per-minute even from the wide union. This is the defensible scram-obligation version: starts from anywhere the plant could plausibly be (including LOCA-perturbed operation state), proves n decays. X_exit(scram)=n≤1e-4 still not reached in 60s — same T_max-vs-plant-decay mismatch previously flagged. Fixed: missing Printf import that had failed the summary block on the first run (results still computed correctly, just the final print errored; the matwrite is after the print so the mat file wasn't saved on that run). Journal entry for 2026-04-21 extended with the fat-entry result + the LOCA-reach 3s-horizon numerical-looseness apass. 38 pages. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
code
Plant model, controllers, and reach-analysis toolchain for the HAHACS preliminary example. All Julia.
What this is
A 10-state coupled neutronics + thermal-hydraulics model (point kinetic equations + lumped thermal loop) with continuous-mode controllers for each of the DRC modes (shutdown, heatup, operation, scram), plus a hand-rolled linear reach-tube propagator, a Lyapunov-ellipsoid barrier attempt, and scaffolding for TMJets-based nonlinear reach.
Ported from MATLAB on 2026-04-20 once the reach experiments made it
clear that Julia's stack (OrdinaryDiffEq, MatrixEquations,
ReachabilityAnalysis, LazySets, @taylorize) was the right tool
for everything we need going forward. The MATLAB originals are in
the git history.
Running
First time:
cd code
julia --project=. -e 'using Pkg; Pkg.instantiate()'
Subsequent:
julia --project=. scripts/main_mode_sweep.jl # all 5 DRC modes, figures
julia --project=. scripts/reach_operation.jl # operation-mode linear reach
julia --project=. scripts/barrier_lyapunov.jl # Lyapunov barrier attempt
julia --project=. scripts/barrier_compare_OL_CL.jl # OL vs CL barrier
julia --project=. scripts/reach_heatup_nonlinear.jl # nonlinear heatup (10s cap)
Figures save to ../docs/figures/. Reach results save to
../reachability/*.mat (gitignored).
Structure
See CLAUDE.md for the architectural overview and ../journal/ for
the invention-log-style narrative of how this code got written.
Dependencies
From Project.toml:
OrdinaryDiffEq— ODE solver, Rodas5 for stiff systems.MatrixEquations—arecfor LQR Riccati,lyapcfor Lyapunov.ReachabilityAnalysis+LazySets— reach sets and set operations.Plots— figures (GR backend by default).JSON— read../reachability/predicates.json.MAT— save results.
Manifest.toml is gitignored; regenerate locally on first
Pkg.instantiate().