Add enthalpy-based secondary boil-off and turbine mapping

tests/test_simulation.py

@@ -266,3 +266,31 @@ def test_auto_control_resets_shutdown_and_moves_rods():
     assert reactor.shutdown is False
     assert reactor.control.manual_control is False
     assert reactor.control.rod_fraction < 0.95
+
+
+def test_full_power_reaches_steam_and_turbine_output():
+    """Integration: cold start -> pumps/gens on -> ramp to ~3 GW -> steam -> turbines online."""
+    reactor = Reactor.default()
+    state = reactor.initial_state()
+    reactor.step(
+        state,
+        dt=1.0,
+        command=ReactorCommand(
+            generator_units={1: True, 2: True},
+            primary_pumps={1: True, 2: True},
+            secondary_pumps={1: True, 2: True},
+            rod_manual=False,
+        ),
+    )
+    for i in range(600):
+        cmd = None
+        if i == 200:
+            cmd = ReactorCommand(secondary_pumps={2: False})
+        if i == 300:
+            cmd = ReactorCommand(secondary_pumps={2: True})
+        if i == 400:
+            cmd = ReactorCommand(turbine_on=True, turbine_units={1: True, 2: True, 3: True})
+        reactor.step(state, dt=1.0, command=cmd)
+
+    assert state.secondary_loop.steam_quality > 0.02
+    assert state.total_electrical_output() > 50.0

tests/test_thermal.py

@@ -30,8 +30,9 @@ def test_secondary_heats_to_saturation_before_boiling():
 def test_secondary_generates_steam_when_energy_exceeds_sensible_heat():
     solver = ThermalSolver()
     loop = _secondary_loop(temp_in=330.0, flow=180.0, pressure=0.5)
+    loop.inventory_kg *= 0.1  # reduce mass to let boil-up happen quickly
     sat_temp = saturation_temperature(loop.pressure)
-    solver.step_secondary(loop, transferred_mw=120.0, dt=1.0)
-    assert loop.temperature_out == pytest.approx(sat_temp, rel=0.02)
+    solver.step_secondary(loop, transferred_mw=120.0, dt=100.0)
+    assert loop.temperature_out == pytest.approx(sat_temp, rel=0.05)
     assert loop.steam_quality > 0.0
     assert loop.steam_quality < 1.0