Fix initialization of depletion reaction xs

src/nuclide_header.F90

@@ -980,6 +980,9 @@ contains
 
       ! Depletion-related reactions
       if (need_depletion_rx) then
+        ! Initialize all reaction cross sections to zero
+        micro_xs % reaction(:) = ZERO
+
         ! Physics says that (n,gamma) is not a threshold reaction, so we don't
         ! need to specifically check its threshold index
         i_rxn = this % reaction_index(DEPLETION_RX(1))
@@ -1007,7 +1010,6 @@ contains
                 ! higher than the threshold for (n,xn). Thus, if we are below
                 ! the threshold for, e.g., (n,2n), there is no reason to check
                 ! the threshold for (n,3n) and (n,4n).
-                micro_xs % reaction(j:6) = ZERO
                 exit
               end if
             end associate