Don't calculate depletion reaction cross sections unless tallies need them

src/cross_section.F90

@@ -39,9 +39,6 @@ contains
     real(8) :: atom_density  ! atom density of a nuclide
     real(8) :: sab_frac      ! fraction of atoms affected by S(a,b)
     logical :: check_sab     ! should we check for S(a,b) table?
-    logical :: in_active     ! are we in active batches?
-
-    in_active = (active_tallies % size() > 0)
 
     ! Set all material macroscopic cross sections to zero
     material_xs % total          = ZERO
@@ -105,7 +102,7 @@ contains
              .or. i_sab /= micro_xs(i_nuclide) % index_sab &
              .or. sab_frac /= micro_xs(i_nuclide) % sab_frac) then
           call calculate_nuclide_xs(i_nuclide, i_sab, p % E, i_grid, &
-                                    p % sqrtkT, sab_frac, in_active)
+                                    p % sqrtkT, sab_frac)
         end if
 
         ! ======================================================================
@@ -144,7 +141,7 @@ contains
 !===============================================================================
 
   subroutine calculate_nuclide_xs(i_nuclide, i_sab, E, i_log_union, sqrtkT, &
-                                  sab_frac, in_active)
+                                  sab_frac)
     integer, intent(in) :: i_nuclide   ! index into nuclides array
     integer, intent(in) :: i_sab       ! index into sab_tables array
     real(8), intent(in) :: E           ! energy
@@ -152,7 +149,6 @@ contains
                                        ! material union energy grid
     real(8), intent(in) :: sqrtkT      ! square root of kT, material dependent
     real(8), intent(in) :: sab_frac    ! fraction of atoms affected by S(a,b)
-    logical, intent(in) :: in_active
 
     logical :: use_mp ! true if XS can be calculated with windowed multipole
     integer :: i_temp ! index for temperature
@@ -197,7 +193,7 @@ contains
           micro_xs(i_nuclide) % nu_fission = ZERO
         end if
 
-        if (in_active) then
+        if (need_depletion_rx) then
           ! Initialize all reaction cross sections to zero
           micro_xs(i_nuclide) % reaction(:) = ZERO
 
@@ -297,7 +293,7 @@ contains
         end associate
 
         ! Depletion-related reactions
-        if (in_active) then
+        if (need_depletion_rx) then
           do j = 1, 6
             ! Initialize reaction xs to zero
             micro_xs(i_nuclide) % reaction(j) = ZERO

src/input_xml.F90

@@ -3048,12 +3048,15 @@ contains
                  &please remove")
           case ('n2n', '(n,2n)')
             t % score_bins(j) = N_2N
+            t % depletion_rx = .true.
 
           case ('n3n', '(n,3n)')
             t % score_bins(j) = N_3N
+            t % depletion_rx = .true.
 
           case ('n4n', '(n,4n)')
             t % score_bins(j) = N_4N
+            t % depletion_rx = .true.
 
           case ('absorption')
             t % score_bins(j) = SCORE_ABSORPTION
@@ -3239,8 +3242,10 @@ contains
             t % score_bins(j) = N_NC
           case ('(n,gamma)')
             t % score_bins(j) = N_GAMMA
+            t % depletion_rx = .true.
           case ('(n,p)')
             t % score_bins(j) = N_P
+            t % depletion_rx = .true.
           case ('(n,d)')
             t % score_bins(j) = N_D
           case ('(n,t)')
@@ -3249,6 +3254,7 @@ contains
             t % score_bins(j) = N_3HE
           case ('(n,a)')
             t % score_bins(j) = N_A
+            t % depletion_rx = .true.
           case ('(n,2a)')
             t % score_bins(j) = N_2A
           case ('(n,3a)')

src/simulation.F90

@@ -451,8 +451,9 @@ contains
       end if
     end if
 
-    ! Reset current batch
+    ! Reset global variables
     current_batch = 0
+    need_depletion_rx = .false.
 
     ! Set flag indicating initialization is done
     simulation_initialized = .true.
@@ -535,7 +536,8 @@ contains
       if (check_overlaps) call print_overlap_check()
     end if
 
-    ! Reset initialization flag
+    ! Reset flags
+    need_depletion_rx = .false.
     simulation_initialized = .false.
 
   end subroutine openmc_simulation_finalize

src/simulation_header.F90

@@ -20,10 +20,11 @@ module simulation_header
   ! ============================================================================
   ! SIMULATION VARIABLES
 
-  integer    :: current_batch     ! current batch
-  integer    :: current_gen       ! current generation within a batch
-  integer    :: total_gen     = 0 ! total number of generations simulated
+  integer :: current_batch     ! current batch
+  integer :: current_gen       ! current generation within a batch
+  integer :: total_gen     = 0 ! total number of generations simulated
   logical(C_BOOL), bind(C) :: simulation_initialized = .false.
+  logical :: need_depletion_rx ! need to calculate depletion reaction rx?
 
   ! ============================================================================
   ! TALLY PRECISION TRIGGER VARIABLES

src/tallies/tally.F90

@@ -4381,6 +4381,9 @@ contains
           elseif (t % type == TALLY_SURFACE) then
             call active_surface_tallies % push_back(i)
           end if
+
+          ! Check if tally contains depletion reactions and if so, set flag
+          if (t % depletion_rx) need_depletion_rx = .true.
         end if
       end associate
     end do

src/tallies/tally_header.F90

@@ -48,6 +48,7 @@ module tally_header
     integer :: estimator = ESTIMATOR_TRACKLENGTH ! collision, track-length
     real(8) :: volume               ! volume of region
     logical :: active = .false.
+    logical :: depletion_rx = .false. ! has depletion reactions, e.g. (n,2n)
     integer, allocatable :: filter(:) ! index in filters array
 
     ! The stride attribute is used for determining the index in the results