diff --git a/src/calculation_target_reliability/router.py b/src/calculation_target_reliability/router.py
index 1b5022b..97d2781 100644
--- a/src/calculation_target_reliability/router.py
+++ b/src/calculation_target_reliability/router.py
@@ -57,10 +57,8 @@ async def get_target_reliability(
     #     oh_duration=duration
     # )
     
-    if not simulation_id:
-        if duration == 17520:
-            simulation_id = TR_RBD_ID
-        else:
+    if duration != 17520:
+        if not simulation_id:
             simulation = await run_rbd_simulation(
                 sim_hours=duration,
                 token=token
@@ -68,6 +66,19 @@ async def get_target_reliability(
             
             simulation_id = simulation.get("data") 
             await wait_for_workflow(simulation_id=simulation_id)
+        else:
+            temporal_client = await Client.connect(TEMPORAL_URL)
+            handle = temporal_client.get_workflow_handle(f"simulation-{simulation_id}")
+            desc = await handle.describe()
+            status_name = desc.status.name
+
+            if status_name in ["RUNNING", "CONTINUED_AS_NEW"]:
+                raise HTTPException(
+                    status_code=status.HTTP_425_TOO_EARLY,  # or 409 Conflict
+                    detail="Simulation still running. Please wait.",
+            )
+    else:
+        simulation_id = TR_RBD_ID
         
 
     results = await get_simulation_results(