diff --git a/src/reactor_sim/neutronics.py b/src/reactor_sim/neutronics.py
index 7a67cd4..45d335f 100644
--- a/src/reactor_sim/neutronics.py
+++ b/src/reactor_sim/neutronics.py
@@ -33,7 +33,7 @@ class NeutronDynamics:
     iodine_decay_const: float = 1.0 / 66000.0  # ~18h
     xenon_decay_const: float = 1.0 / 33000.0  # ~9h
     xenon_burnout_coeff: float = 1e-13  # per n/cm2
-    xenon_reactivity_coeff: float = 0.002
+    xenon_reactivity_coeff: float = 0.05
 
     def reactivity(self, state: CoreState, control_fraction: float, rod_banks: list[float] | None = None) -> float:
         if rod_banks:
@@ -101,4 +101,4 @@ class NeutronDynamics:
         return self._xenon_penalty(state)
 
     def _xenon_penalty(self, state: CoreState) -> float:
-        return min(0.03, state.xenon_inventory * self.xenon_reactivity_coeff)
+        return min(0.05, state.xenon_inventory * self.xenon_reactivity_coeff)
diff --git a/tests/test_neutronics.py b/tests/test_neutronics.py
index 3a15ce7..2c975d2 100644
--- a/tests/test_neutronics.py
+++ b/tests/test_neutronics.py
@@ -40,6 +40,6 @@ def test_xenon_penalty_caps():
     dynamics = NeutronDynamics()
     state = _core_state()
     state.xenon_inventory = 50.0
-    assert dynamics.xenon_penalty(state) == 0.03
-    state.xenon_inventory = 5.0
+    assert dynamics.xenon_penalty(state) == 0.05
+    state.xenon_inventory = 0.2
     assert dynamics.xenon_penalty(state) == pytest.approx(0.01)