Clarify generator control and turbine status

src/reactor_sim/commands.py

@@ -24,6 +24,7 @@ class ReactorCommand:
     primary_pumps: dict[int, bool] | None = None
     secondary_pumps: dict[int, bool] | None = None
     generator_units: dict[int, bool] | None = None
+    generator_auto: bool | None = None
     maintenance_components: tuple[str, ...] = tuple()
 
     @classmethod

src/reactor_sim/dashboard.py

@@ -47,29 +47,45 @@ class ReactorDashboard:
         self._log_handler: Optional[logging.Handler] = None
         self._previous_handlers: list[logging.Handler] = []
         self._logger = logging.getLogger("reactor_sim")
-        self.keys = [
+        self.help_sections: list[tuple[str, list[DashboardKey]]] = [
+            (
+                "Reactor / Safety",
+                [
                     DashboardKey("q", "Quit & save"),
                     DashboardKey("space", "SCRAM"),
-            DashboardKey("g", "Toggle primary pump 1"),
-            DashboardKey("h", "Toggle primary pump 2"),
-            DashboardKey("j", "Toggle secondary pump 1"),
-            DashboardKey("k", "Toggle secondary pump 2"),
-            DashboardKey("b", "Toggle generator 1"),
-            DashboardKey("v", "Toggle generator 2"),
-            DashboardKey("t", "Toggle turbine"),
+                    DashboardKey("r", "Reset & clear state"),
+                    DashboardKey("a", "Toggle auto rod control"),
+                    DashboardKey("+/-", "Withdraw/insert rods"),
+                    DashboardKey("[/]", "Adjust consumer demand −/+50 MW"),
+                    DashboardKey("s/d", "Setpoint −/+250 MW"),
+                ],
+            ),
+            (
+                "Pumps",
+                [
+                    DashboardKey("g/h", "Toggle primary pump 1/2"),
+                    DashboardKey("j/k", "Toggle secondary pump 1/2"),
+                    DashboardKey("m/n", "Maintain primary pumps 1/2"),
+                    DashboardKey(",/.", "Maintain secondary pumps 1/2"),
+                ],
+            ),
+            (
+                "Generators",
+                [
+                    DashboardKey("b/v", "Toggle generator 1/2"),
+                    DashboardKey("x", "Toggle generator auto"),
+                    DashboardKey("B/V", "Maintain generator 1/2"),
+                ],
+            ),
+            (
+                "Turbines / Grid",
+                [
+                    DashboardKey("t", "Toggle turbine bank"),
                     DashboardKey("1/2/3", "Toggle turbine units 1-3"),
                     DashboardKey("y/u/i", "Maintain turbine 1/2/3"),
                     DashboardKey("c", "Toggle consumer"),
-            DashboardKey("r", "Reset & clear state"),
-            DashboardKey("m/n", "Maintain primary pumps 1/2"),
-            DashboardKey(",/.", "Maintain secondary pumps 1/2"),
-            DashboardKey("B/V", "Maintain generator 1/2"),
-            DashboardKey("k", "Maintain core (requires shutdown)"),
-            DashboardKey("+/-", "Withdraw/insert rods"),
-            DashboardKey("[/]", "Adjust consumer demand −/+50 MW"),
-            DashboardKey("s", "Setpoint −250 MW"),
-            DashboardKey("d", "Setpoint +250 MW"),
-            DashboardKey("a", "Toggle auto rod control"),
+                ],
+            ),
         ]
 
     def run(self) -> None:
@@ -146,6 +162,8 @@ class ReactorDashboard:
                 self._toggle_generator_unit(0)
             elif ch in (ord("v"), ord("V")):
                 self._toggle_generator_unit(1)
+            elif ch in (ord("x"), ord("X")):
+                self._queue_command(ReactorCommand(generator_auto=not self.reactor.generator_auto))
             elif ch in (ord("t"), ord("T")):
                 self._queue_command(ReactorCommand(turbine_on=not self.reactor.turbine_active))
             elif ord("1") <= ch <= ord("9"):
@@ -259,6 +277,7 @@ class ReactorDashboard:
         self.reactor = Reactor.default()
         self.start_state = None
         self.pending_command = None
+        self._last_state = None
         self.reset_requested = False
         self.log_buffer.clear()
 
@@ -307,10 +326,23 @@ class ReactorDashboard:
         win.erase()
         win.box()
         win.addstr(0, 2, " Plant Overview ", curses.color_pair(1) | curses.A_BOLD)
-        y = 2
-        y = self._draw_section(
-            win,
-            y,
+        height, width = win.getmaxyx()
+        inner_height = height - 2
+        inner_width = width - 2
+        left_width = max(28, inner_width // 2)
+        right_width = inner_width - left_width
+        left_win = win.derwin(inner_height, left_width, 1, 1)
+        right_win = win.derwin(inner_height, right_width, 1, 1 + left_width)
+        for row in range(1, height - 1):
+            win.addch(row, 1 + left_width, curses.ACS_VLINE)
+
+        left_win.erase()
+        right_win.erase()
+
+        left_y = 0
+        left_y = self._draw_section(
+            left_win,
+            left_y,
             "Core",
             [
                 ("Fuel Temp", f"{state.core.fuel_temperature:8.1f} K"),
@@ -322,10 +354,10 @@ class ReactorDashboard:
                 ("Reactivity", f"{state.core.reactivity_margin:+.4f}"),
             ],
         )
-        y = self._draw_section(win, y, "Key Poisons / Emitters", self._poison_lines(state))
-        y = self._draw_section(
-            win,
-            y,
+        left_y = self._draw_section(left_win, left_y, "Key Poisons / Emitters", self._poison_lines(state))
+        left_y = self._draw_section(
+            left_win,
+            left_y,
             "Primary Loop",
             [
                 ("Pump1", self._pump_status(state.primary_pumps, 0)),
@@ -336,9 +368,9 @@ class ReactorDashboard:
                 ("Pressure", f"{state.primary_loop.pressure:5.2f} MPa"),
             ],
         )
-        y = self._draw_section(
-            win,
-            y,
+        self._draw_section(
+            left_win,
+            left_y,
             "Secondary Loop",
             [
                 ("Pump1", self._pump_status(state.secondary_pumps, 0)),
@@ -349,20 +381,16 @@ class ReactorDashboard:
                 ("Steam Quality", f"{state.secondary_loop.steam_quality:5.2f}"),
             ],
         )
-        y = self._draw_section(
-            win,
-            y,
-            "Generators",
-            self._generator_lines(state),
-        )
+
+        right_y = 0
         consumer_status = "n/a"
         consumer_demand = 0.0
         if self.reactor.consumer:
             consumer_status = "ONLINE" if self.reactor.consumer.online else "OFF"
             consumer_demand = self.reactor.consumer.demand_mw
-        y = self._draw_section(
-            win,
-            y,
+        right_y = self._draw_section(
+            right_win,
+            right_y,
             "Turbine / Grid",
             [
                 ("Turbines", " ".join(self._turbine_status_lines())),
@@ -381,18 +409,23 @@ class ReactorDashboard:
                 ("Demand", f"{consumer_demand:7.1f} MW"),
             ],
         )
-        y = self._draw_section(win, y, "Maintenance", self._maintenance_lines())
-        y = self._draw_health_bars(win, y)
+        right_y = self._draw_section(right_win, right_y, "Generators", self._generator_lines(state))
+        right_y = self._draw_section(right_win, right_y, "Maintenance", self._maintenance_lines())
+        self._draw_health_bars(right_win, right_y)
 
     def _draw_help_panel(self, win: "curses._CursesWindow") -> None:
         win.erase()
         win.box()
         win.addstr(0, 2, " Controls ", curses.color_pair(1) | curses.A_BOLD)
         y = 2
-        for entry in self.keys:
-            win.addstr(y, 2, f"{entry.key:<8} {entry.description}")
+        for title, entries in self.help_sections:
+            win.addstr(y, 2, title, curses.color_pair(1) | curses.A_BOLD)
             y += 1
-        win.addstr(y + 1, 2, "Tips:", curses.color_pair(2) | curses.A_BOLD)
+            for entry in entries:
+                win.addstr(y, 4, f"{entry.key:<8} {entry.description}")
+                y += 1
+            y += 1
+        win.addstr(y, 2, "Tips:", curses.color_pair(2) | curses.A_BOLD)
         tips = [
             "Start pumps before withdrawing rods.",
             "Bring turbine and consumer online after thermal stabilization.",
@@ -458,9 +491,15 @@ class ReactorDashboard:
     def _turbine_status_lines(self) -> list[str]:
         if not self.reactor.turbine_unit_active:
             return ["n/a"]
-        return [
-            f"{idx + 1}:{'ON' if active else 'OFF'}" for idx, active in enumerate(self.reactor.turbine_unit_active)
-        ]
+        lines: list[str] = []
+        for idx, active in enumerate(self.reactor.turbine_unit_active):
+            label = f"{idx + 1}:"
+            status = "ON" if active else "OFF"
+            if idx < len(getattr(self._last_state, "turbines", [])):
+                t_state = self._last_state.turbines[idx]
+                status = getattr(t_state, "status", status)
+            lines.append(f"{label}{status}")
+        return lines
 
     def _total_load_supplied(self, state: PlantState) -> float:
         return sum(t.load_supplied_mw for t in state.turbines)
@@ -504,6 +543,8 @@ class ReactorDashboard:
         if not state.generators:
             return [("Status", "n/a")]
         lines: list[tuple[str, str]] = []
+        control = "AUTO" if self.reactor.generator_auto else "MANUAL"
+        lines.append(("Control", control))
         for idx, gen in enumerate(state.generators):
             status = "RUN" if gen.running else "START" if gen.starting else "OFF"
             spool = f" spool {gen.spool_remaining:4.1f}s" if gen.starting else ""
@@ -518,17 +559,18 @@ class ReactorDashboard:
             return height - 2
         win.addstr(start_y, 2, "Component Health", curses.A_BOLD | curses.color_pair(1))
         bar_width = max(8, min(inner_width - 18, 40))
+        label_width = 16
         row = start_y + 1
         for name, comp in self.reactor.health_monitor.components.items():
             if row >= height - 1:
                 break
-            label = f"{name:<12}"
+            label = f"{name:<{label_width}}"
             target = 0.0 if comp.failed else comp.integrity
             filled = int(bar_width * max(0.0, min(1.0, target)))
             bar = "#" * filled + "-" * (bar_width - filled)
             color = 3 if comp.integrity > 0.5 else 2 if comp.integrity > 0.2 else 4
             win.addstr(row, 4, f"{label}:")
-            bar_start = 4 + len(label) + 1
+            bar_start = 4 + label_width + 1
             win.addstr(row, bar_start, bar[:bar_width], curses.color_pair(color))
             percent_text = "FAILED" if comp.failed else f"{comp.integrity*100:5.1f}%"
             percent_x = min(width - len(percent_text) - 2, bar_start + bar_width + 2)
@@ -540,7 +582,8 @@ class ReactorDashboard:
         if index >= len(pumps):
             return "n/a"
         state = pumps[index]
-        return f"{'ON ' if state.active else 'OFF'} {state.flow_rate:6.0f} kg/s"
+        status = getattr(state, "status", "ON" if state.active else "OFF")
+        return f"{status:<8} {state.flow_rate:6.0f} kg/s"
 
     def _current_demand(self) -> float:
         if self.reactor.consumer:

src/reactor_sim/generator.py

@@ -17,6 +17,7 @@ class GeneratorState:
     spool_remaining: float
     power_output_mw: float
     battery_charge: float
+    status: str = "OFF"
 
 
 @dataclass
@@ -32,6 +33,7 @@ class DieselGenerator:
             return
         state.starting = True
         state.spool_remaining = self.spool_time
+        state.status = "STARTING"
         LOGGER.info("Generator starting (spool %.0fs)", self.spool_time)
 
     def stop(self, state: GeneratorState) -> None:
@@ -41,6 +43,7 @@ class DieselGenerator:
         state.starting = False
         state.spool_remaining = 0.0
         state.power_output_mw = 0.0
+        state.status = "OFF"
         LOGGER.info("Generator stopped")
 
     def step(self, state: GeneratorState, load_demand_mw: float, dt: float) -> float:
@@ -51,12 +54,15 @@ class DieselGenerator:
             if state.spool_remaining <= 0.0:
                 state.starting = False
                 state.running = True
+                state.status = "RUN"
                 LOGGER.info("Generator online at %.1f MW", self.rated_output_mw)
         elif state.running:
             available = self.rated_output_mw
             state.power_output_mw = min(available, load_demand_mw)
+            state.status = "RUN" if state.power_output_mw > 0 else "IDLE"
         else:
             state.power_output_mw = 0.0
+            state.status = "OFF"
 
         if state.running:
             state.battery_charge = min(1.0, state.battery_charge + 0.02 * dt)

src/reactor_sim/reactor.py

@@ -44,6 +44,7 @@ class Reactor:
     turbine_unit_active: list[bool] = field(default_factory=lambda: [True, True, True])
     shutdown: bool = False
     meltdown: bool = False
+    generator_auto: bool = True
     poison_alerts: set[str] = field(default_factory=set)
     maintenance_active: set[str] = field(default_factory=set)
 
@@ -96,6 +97,8 @@ class Reactor:
         self.meltdown = False
         self.primary_pump_active = False
         self.secondary_pump_active = False
+        self.primary_pump_units = [False] * len(self.primary_pump_units)
+        self.secondary_pump_units = [False] * len(self.secondary_pump_units)
         self.turbine_unit_active = [False] * len(self.turbines)
         self.turbine_active = any(self.turbine_unit_active)
         if self.consumer:
@@ -115,10 +118,18 @@ class Reactor:
             mass_flow_rate=0.0,
             steam_quality=0.0,
         )
-        primary_pumps = [PumpState(active=self.primary_pump_active, flow_rate=0.0, pressure=0.5) for _ in range(2)]
-        secondary_pumps = [PumpState(active=self.secondary_pump_active, flow_rate=0.0, pressure=0.5) for _ in range(2)]
+        primary_pumps = [
+            PumpState(active=self.primary_pump_active and self.primary_pump_units[idx], flow_rate=0.0, pressure=0.5)
+            for idx in range(2)
+        ]
+        secondary_pumps = [
+            PumpState(active=self.secondary_pump_active and self.secondary_pump_units[idx], flow_rate=0.0, pressure=0.5)
+            for idx in range(2)
+        ]
         generator_states = [
-            GeneratorState(running=False, starting=False, spool_remaining=0.0, power_output_mw=0.0, battery_charge=1.0)
+            GeneratorState(
+                running=False, starting=False, spool_remaining=0.0, power_output_mw=0.0, battery_charge=1.0, status="OFF"
+            )
             for _ in self.generators
         ]
         turbine_states = [
@@ -218,6 +229,14 @@ class Reactor:
                     pump_state.pressure, desired_pressure, dt, self.primary_pump.spool_time
                 )
                 pump_state.active = (unit_enabled and power_ratio > 0.05) or pump_state.flow_rate > 1.0
+                if unit_enabled and pump_state.flow_rate < max(1.0, desired_flow * 0.8):
+                    pump_state.status = "STARTING"
+                elif not unit_enabled and pump_state.flow_rate > 1.0:
+                    pump_state.status = "STOPPING"
+                elif pump_state.active:
+                    pump_state.status = "RUN"
+                else:
+                    pump_state.status = "OFF"
                 total_flow += pump_state.flow_rate
                 loop_pressure = max(loop_pressure, pump_state.pressure)
             state.primary_loop.mass_flow_rate = total_flow
@@ -239,6 +258,7 @@ class Reactor:
                 pump_state.pressure = self._ramp_value(
                     pump_state.pressure, state.primary_loop.pressure, dt, self.primary_pump.spool_time
                 )
+                pump_state.status = "STOPPING" if pump_state.flow_rate > 1.0 else "OFF"
         if self.secondary_pump_active:
             total_flow = 0.0
             target_pressure = 12.0 * 0.75 + 2.0
@@ -257,6 +277,14 @@ class Reactor:
                     pump_state.pressure, desired_pressure, dt, self.secondary_pump.spool_time
                 )
                 pump_state.active = unit_enabled or pump_state.flow_rate > 1.0
+                if unit_enabled and pump_state.flow_rate < max(1.0, desired_flow * 0.8):
+                    pump_state.status = "STARTING"
+                elif not unit_enabled and pump_state.flow_rate > 1.0:
+                    pump_state.status = "STOPPING"
+                elif pump_state.active:
+                    pump_state.status = "RUN"
+                else:
+                    pump_state.status = "OFF"
                 total_flow += pump_state.flow_rate
                 loop_pressure = max(loop_pressure, pump_state.pressure)
             state.secondary_loop.mass_flow_rate = total_flow
@@ -278,6 +306,7 @@ class Reactor:
                 pump_state.pressure = self._ramp_value(
                     pump_state.pressure, state.secondary_loop.pressure, dt, self.secondary_pump.spool_time
                 )
+                pump_state.status = "STOPPING" if pump_state.flow_rate > 1.0 else "OFF"
 
         self.thermal.step_core(state.core, state.primary_loop, total_power, dt)
         if not self.secondary_pump_active or state.secondary_loop.mass_flow_rate <= 1.0:
@@ -334,8 +363,15 @@ class Reactor:
             turbine_state = state.turbines[idx]
             if idx in active_indices:
                 turbine.step(state.secondary_loop, turbine_state, steam_power_mw=power_per_unit, dt=dt)
+                if power_per_unit <= 0.0 and turbine_state.electrical_output_mw < 0.1:
+                    turbine_state.status = "OFF"
+                elif turbine_state.electrical_output_mw < max(0.5, power_per_unit * 0.5):
+                    turbine_state.status = "STARTING"
+                else:
+                    turbine_state.status = "RUN"
             else:
                 self._spin_down_turbine(turbine_state, dt, turbine.spool_time)
+                turbine_state.status = "STOPPING" if turbine_state.electrical_output_mw > 0 else "OFF"
         self._dispatch_consumer_load(state, active_indices)
 
     def _reset_turbine_state(self, turbine_state: TurbineState) -> None:
@@ -343,6 +379,7 @@ class Reactor:
         turbine_state.electrical_output_mw = 0.0
         turbine_state.load_demand_mw = 0.0
         turbine_state.load_supplied_mw = 0.0
+        turbine_state.status = "OFF"
 
     @staticmethod
     def _ramp_value(current: float, target: float, dt: float, time_constant: float) -> float:
@@ -405,6 +442,8 @@ class Reactor:
             self.shutdown = True
             overrides["rod_fraction"] = self.control.scram()
             self._set_turbine_state(False)
+        if command.generator_auto is not None:
+            self.generator_auto = command.generator_auto
         if command.power_setpoint is not None:
             self.control.set_power_setpoint(command.power_setpoint)
         if command.rod_manual is not None:
@@ -446,8 +485,6 @@ class Reactor:
             LOGGER.info("Primary pump %s", "enabled" if active else "stopped")
         if not active:
             self.primary_pump_units = [False] * len(self.primary_pump_units)
-        elif active and not any(self.primary_pump_units):
-            self.primary_pump_units = [True] * len(self.primary_pump_units)
 
     def _set_secondary_pump(self, active: bool) -> None:
         if self.secondary_pump_active != active:
@@ -455,8 +492,6 @@ class Reactor:
             LOGGER.info("Secondary pump %s", "enabled" if active else "stopped")
         if not active:
             self.secondary_pump_units = [False] * len(self.secondary_pump_units)
-        elif active and not any(self.secondary_pump_units):
-            self.secondary_pump_units = [True] * len(self.secondary_pump_units)
 
     def _toggle_primary_pump_unit(self, index: int, active: bool) -> None:
         if index < 0 or index >= len(self.primary_pump_units):
@@ -512,6 +547,7 @@ class Reactor:
                     GeneratorState(running=False, starting=False, spool_remaining=0.0, power_output_mw=0.0, battery_charge=1.0)
                 )
         deficit = max(0.0, aux_demand - turbine_electric)
+        if self.generator_auto:
             if deficit > 0.0:
                 for idx, gen_state in enumerate(state.generators):
                     if not (gen_state.running or gen_state.starting):
@@ -526,8 +562,10 @@ class Reactor:
 
         total_power = 0.0
         remaining = max(0.0, aux_demand - turbine_electric)
+        active_indices = [idx for idx, g in enumerate(state.generators) if g.running or g.starting]
+        share = remaining / len(active_indices) if active_indices and remaining > 0 else 0.0
         for idx, gen_state in enumerate(state.generators):
-            load = remaining if remaining > 0 else 0.0
+            load = share if idx in active_indices else 0.0
             delivered = self.generators[idx].step(gen_state, load, dt)
             total_power += delivered
             remaining = max(0.0, remaining - delivered)
@@ -640,6 +678,7 @@ class Reactor:
             "turbine_units": self.turbine_unit_active,
             "shutdown": self.shutdown,
             "meltdown": self.meltdown,
+            "generator_auto": self.generator_auto,
             "maintenance_active": list(self.maintenance_active),
             "generators": [
                 {
@@ -648,6 +687,7 @@ class Reactor:
                     "spool_remaining": g.spool_remaining,
                     "power_output_mw": g.power_output_mw,
                     "battery_charge": g.battery_charge,
+                    "status": g.status,
                 }
                 for g in state.generators
             ],
@@ -671,6 +711,7 @@ class Reactor:
         self.turbine_active = metadata.get("turbine_active", any(self.turbine_unit_active))
         self.shutdown = metadata.get("shutdown", self.shutdown)
         self.meltdown = metadata.get("meltdown", self.meltdown)
+        self.generator_auto = metadata.get("generator_auto", self.generator_auto)
         maint = metadata.get("maintenance_active")
         if maint is not None:
             self.maintenance_active = set(maint)
@@ -691,7 +732,12 @@ class Reactor:
         # Back-fill pump state lists for compatibility.
         if not plant.primary_pumps or len(plant.primary_pumps) < 2:
             plant.primary_pumps = [
-                PumpState(active=self.primary_pump_active, flow_rate=plant.primary_loop.mass_flow_rate / 2, pressure=plant.primary_loop.pressure)
+                PumpState(
+                    active=self.primary_pump_active,
+                    flow_rate=plant.primary_loop.mass_flow_rate / 2,
+                    pressure=plant.primary_loop.pressure,
+                    status="OFF",
+                )
                 for _ in range(2)
             ]
         if not plant.secondary_pumps or len(plant.secondary_pumps) < 2:
@@ -700,6 +746,7 @@ class Reactor:
                     active=self.secondary_pump_active,
                     flow_rate=plant.secondary_loop.mass_flow_rate / 2,
                     pressure=plant.secondary_loop.pressure,
+                    status="OFF",
                 )
                 for _ in range(2)
             ]
@@ -726,6 +773,7 @@ class Reactor:
                         spool_remaining=0.0,
                         power_output_mw=0.0,
                         battery_charge=1.0,
+                        status="OFF",
                     )
                 )
         for idx, gen_state in enumerate(plant.generators):
@@ -736,6 +784,7 @@ class Reactor:
                 gen_state.spool_remaining = cfg.get("spool_remaining", gen_state.spool_remaining)
                 gen_state.power_output_mw = cfg.get("power_output_mw", gen_state.power_output_mw)
                 gen_state.battery_charge = cfg.get("battery_charge", gen_state.battery_charge)
+                gen_state.status = cfg.get("status", gen_state.status)
         return plant
 
     def _handle_heat_sink_loss(self, state: PlantState) -> None:

src/reactor_sim/state.py

@@ -54,6 +54,7 @@ class TurbineState:
     condenser_temperature: float
     load_demand_mw: float = 0.0
     load_supplied_mw: float = 0.0
+    status: str = "OFF"
 
 
 @dataclass
@@ -61,6 +62,7 @@ class PumpState:
     active: bool
     flow_rate: float
     pressure: float
+    status: str = "OFF"
 
 
 @dataclass

tests/test_simulation.py

@@ -162,6 +162,8 @@ def test_full_rod_withdrawal_reaches_gigawatt_power():
     reactor.control.rod_fraction = 0.0
     reactor.primary_pump_active = True
     reactor.secondary_pump_active = True
+    reactor.primary_pump_units = [True, True]
+    reactor.secondary_pump_units = [True, True]
 
     early_power = 0.0
     for step in range(60):
@@ -180,6 +182,8 @@ def test_partially_inserted_rods_hold_near_three_gw():
     reactor.control.rod_fraction = 0.4
     reactor.primary_pump_active = True
     reactor.secondary_pump_active = True
+    reactor.primary_pump_units = [True, True]
+    reactor.secondary_pump_units = [True, True]
 
     for _ in range(120):
         reactor.step(state, dt=1.0)
@@ -206,6 +210,30 @@ def test_generator_spools_and_powers_pumps():
     assert state.primary_loop.mass_flow_rate > 0.0
 
 
+def test_generator_manual_mode_allows_single_unit_and_stop():
+    reactor = Reactor.default()
+    state = reactor.initial_state()
+    reactor.shutdown = False
+    reactor.control.manual_control = True
+    reactor.control.rod_fraction = 0.95
+    reactor.generator_auto = False
+    reactor.primary_pump_units = [True, False]
+    reactor.secondary_pump_units = [False, False]
+
+    reactor.step(state, dt=1.0, command=ReactorCommand(generator_units={1: True}, primary_pumps={1: True}))
+    assert state.generators[0].starting or state.generators[0].running
+
+    for _ in range(15):
+        reactor.step(state, dt=1.0)
+
+    assert state.generators[0].running is True
+    reactor.step(state, dt=1.0, command=ReactorCommand(generator_units={1: False}))
+    for _ in range(5):
+        reactor.step(state, dt=1.0)
+    assert state.generators[0].running is False
+    assert state.generators[1].running is False
+
+
 def test_meltdown_triggers_shutdown():
     reactor = Reactor.default()
     state = reactor.initial_state()