Make loading the reactor from file update the "last" temperatures.

src/main/java/mekanism/api/reactor/IFusionReactor.java

@@ -58,4 +58,6 @@ public interface IFusionReactor extends IHeatTransfer
 	public double getPassiveGeneration(boolean active, boolean current);
 
 	public int getSteamPerTick(boolean current);
+
+	public void updateTemperatures();
 }

src/main/java/mekanism/generators/common/FusionReactor.java

@@ -137,6 +137,12 @@ public class FusionReactor implements IFusionReactor
 			kill();
 		}
 
+		updateTemperatures();
+	}
+
+	@Override
+	public void updateTemperatures()
+	{
 		lastPlasmaTemperature = plasmaTemperature < 1E-1 ? 0 : plasmaTemperature;
 		lastCaseTemperature = caseTemperature < 1E-1 ? 0 : caseTemperature;
 	}

src/main/java/mekanism/generators/common/tile/reactor/TileEntityReactorController.java

@@ -165,6 +165,7 @@ public class TileEntityReactorController extends TileEntityReactorBlock implemen
 			getReactor().setCaseTemp(tag.getDouble("caseTemp"));
 			getReactor().setInjectionRate(tag.getInteger("injectionRate"));
 			getReactor().setBurning(tag.getBoolean("burning"));
+			getReactor().updateTemperatures();
 		}
 
 		fuelTank.read(tag.getCompoundTag("fuelTank"));