Improve reactor controls, reactions, and maintenance UI

tests/test_atomic.py

@@ -0,0 +1,54 @@
+from reactor_sim.atomic import AtomicPhysics, make_atom
+
+
+def test_alpha_decay_reduces_mass_and_charge():
+    physics = AtomicPhysics(seed=1)
+    parent = make_atom(92, 143)
+    event = physics.alpha_decay(parent)
+    daughter, alpha = event.products
+    assert daughter.protons == 90
+    assert daughter.neutrons == 141
+    assert alpha.protons == 2 and alpha.neutrons == 2
+    assert "alpha" in event.emitted_particles
+    assert event.energy_mev > 0
+
+
+def test_beta_minus_conserves_mass_number():
+    physics = AtomicPhysics(seed=2)
+    parent = make_atom(26, 30)
+    event = physics.beta_minus_decay(parent)
+    (daughter,) = event.products
+    assert daughter.mass_number == parent.mass_number
+    assert daughter.protons == parent.protons + 1
+    assert "beta-" in event.emitted_particles
+
+
+def test_beta_plus_and_electron_capture_lower_proton_count():
+    physics = AtomicPhysics(seed=3)
+    parent = make_atom(15, 16)
+    beta_plus = physics.beta_plus_decay(parent)
+    capture = physics.electron_capture(parent)
+    assert beta_plus.products[0].protons == parent.protons - 1
+    assert capture.products[0].protons == parent.protons - 1
+    assert "beta+" in beta_plus.emitted_particles
+    assert "gamma" in capture.emitted_particles
+
+
+def test_gamma_emission_keeps_nuclide_same():
+    physics = AtomicPhysics(seed=4)
+    parent = make_atom(8, 8)
+    event = physics.gamma_emission(parent, energy_mev=0.3)
+    (product,) = event.products
+    assert product == parent
+    assert "gamma" in event.emitted_particles
+    assert event.energy_mev == 0.3
+
+
+def test_spontaneous_fission_creates_two_fragments():
+    physics = AtomicPhysics(seed=5)
+    parent = make_atom(92, 143)
+    event = physics.spontaneous_fission(parent)
+    assert len(event.products) == 2
+    total_mass = sum(atom.mass_number for atom in event.products)
+    assert total_mass <= parent.mass_number
+    assert event.energy_mev > 0

tests/test_fuel.py

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+from reactor_sim.atomic import AtomicPhysics
+from reactor_sim.fuel import FuelAssembly
+from reactor_sim.state import CoreState
+
+
+def _core_state(
+    temp: float = 600.0,
+    flux: float = 1e6,
+    burnup: float = 0.05,
+    power: float = 100.0,
+) -> CoreState:
+    return CoreState(
+        fuel_temperature=temp,
+        neutron_flux=flux,
+        reactivity_margin=0.0,
+        power_output_mw=power,
+        burnup=burnup,
+    )
+
+
+def test_decay_reaction_power_positive_and_capped():
+    physics = AtomicPhysics(seed=7)
+    fuel = FuelAssembly(enrichment=0.045, mass_kg=80_000.0, atomic_physics=physics)
+    state = _core_state()
+    power = fuel.decay_reaction_power(state)
+    assert power > 0
+    # Should stay under 10% of current power_output_mw.
+    assert power <= state.power_output_mw * 0.1 + 1e-6
+
+
+def test_decay_reaction_power_scales_with_burnup_and_flux():
+    physics = AtomicPhysics(seed=9)
+    fuel = FuelAssembly(enrichment=0.045, mass_kg=80_000.0, atomic_physics=physics)
+    low = _core_state(burnup=0.01, flux=1e5, power=50.0)
+    high = _core_state(burnup=0.5, flux=5e6, power=200.0)
+    low_power = fuel.decay_reaction_power(low)
+    high_power = fuel.decay_reaction_power(high)
+    assert high_power > low_power
+    # Still capped to a reasonable fraction of the prevailing power.
+    assert high_power <= high.power_output_mw * 0.1 + 1e-6