Add spool dynamics for pumps and turbines

tests/test_simulation.py

@@ -129,3 +129,18 @@ def test_secondary_pump_unit_toggle_can_restart_pump():
     assert reactor.secondary_pump_units == [True, False]
     assert reactor.secondary_pump_active is True
     assert state.secondary_loop.mass_flow_rate > 0.0
+
+
+def test_primary_pumps_spool_up_over_seconds():
+    reactor = Reactor.default()
+    state = reactor.initial_state()
+    # Enable both pumps and command full flow; spool should take multiple steps.
+    target_flow = reactor.primary_pump.flow_rate(1.0) * len(reactor.primary_pump_units)
+    reactor.step(state, dt=1.0, command=ReactorCommand(primary_pump_on=True, coolant_demand=1.0))
+    first_flow = state.primary_loop.mass_flow_rate
+    assert 0.0 < first_flow < target_flow
+
+    for _ in range(10):
+        reactor.step(state, dt=1.0, command=ReactorCommand(coolant_demand=1.0))
+
+    assert state.primary_loop.mass_flow_rate == pytest.approx(target_flow, rel=0.1)