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Results from the overnight TMJets run with the prompt-jump model: T=60s: PASSES (10,044 reach-sets, 205 s wall) T=300s: PASSES (27,375 reach-sets, 591 s wall) T=1800s+: partial — exhausts 100k step budget past ~300s At T=300s the envelope is: n: [-0.00156, 0.0103] (slightly negative = sound overapprox) T_c: [272.4, 295.0] C T_f: [261.2, 302.7] C T_cold: [270.0, 289.5] C Discharges 5/6 inv1_holds safety halfspaces at 300s: fuel_centerline: +897 K margin ✓ t_avg_high_trip: +25 K margin ✓ t_avg_low_trip: VIOLATED (tube dips to 272.4, limit 280) n_high_trip: huge margin ✓ cold_leg_subcooled: +15 K margin ✓ The low_trip violation is TUBE looseness, not physical — nominal sim only dips to ~280 transiently. Fixable by tighter X_entry, higher orderQ, or refinement. Open item. Journal updated with full results table + limitation box. scram PJ reach ready to run but not yet executed (structure similar, simpler). Fix: siunitx \degreeFahrenheit, \degree, \microsecond now work via \DeclareSIUnit in preamble. UTF-8 passthrough in listings via literate= map for Δ, λ, μ, α, β, ρ, Σ, Λ, ≤, ≥, →, ±, °, ×, ε. Journal now compiles clean: 32 pages, 0 errors. App v2 Pluto cells land under §§9b–9d: live reach-result ingestion with computed per-halfspace margins, 2D projection chooser, PJ-reach overlay placeholder. 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().