diff --git a/src/reactor_sim/reactor.py b/src/reactor_sim/reactor.py
index 161f474..5b0bd8b 100644
--- a/src/reactor_sim/reactor.py
+++ b/src/reactor_sim/reactor.py
@@ -252,15 +252,16 @@ class Reactor:
         turbine_electrical = state.total_electrical_output()
         generator_power = self._step_generators(state, aux_demand, turbine_electrical, dt)
         aux_available = turbine_electrical + generator_power
-        power_ratio = 1.0 if aux_demand <= 0 else 1.0
-        if aux_demand > 0 and aux_available < 0.5 * aux_demand:
+        supplied = aux_available if aux_demand <= 0 else min(aux_available, aux_demand)
+        power_ratio = 1.0 if aux_demand <= 0 else min(1.0, supplied / max(1e-6, aux_demand))
+        if aux_demand > 0 and aux_available < 0.99 * aux_demand:
             LOGGER.warning("Aux power deficit: available %.1f/%.1f MW", aux_available, aux_demand)
         state.aux_draws = {
             "base": aux_base * power_ratio,
             "primary_pumps": aux_pump_primary * power_ratio,
             "secondary_pumps": aux_pump_secondary * power_ratio,
             "total_demand": aux_demand,
-            "supplied": aux_available,
+            "supplied": supplied,
             "generator_output": generator_power,
             "turbine_output": turbine_electrical,
         }