diff --git a/src/constants.F90 b/src/constants.F90
index e6dcfe7554..eff1196395 100644
--- a/src/constants.F90
+++ b/src/constants.F90
@@ -219,7 +219,7 @@ module constants
        N_3HEC  = 799, N_A0    = 800, N_AC   = 849, N_2N0   = 875, N_2NC   = 891
 
   ! Depletion reactions
-  integer, parameter :: DEPLETION_RX(6) = [N_GAMMA, N_P, N_A,N_2N, N_3N,N_4N]
+  integer, parameter :: DEPLETION_RX(6) = [N_GAMMA, N_P, N_A, N_2N, N_3N, N_4N]
 
   ! ACE table types
   integer, parameter :: &
diff --git a/src/nuclide_header.F90 b/src/nuclide_header.F90
index 33ad2abb62..5d046dbcc0 100644
--- a/src/nuclide_header.F90
+++ b/src/nuclide_header.F90
@@ -978,12 +978,13 @@ contains
         end if
       end associate
 
-      !Depletion-related reactions
+      ! Depletion-related reactions
       if (need_depletion_rx) then
-        !Initialize entire array to zero in case we skip
-        !any threshold reaction.
+        ! Initialize all reaction cross sections to zero
         micro_xs % reaction(:) = ZERO
-        !there shouldn't be a threshold check for (n,gamma).
+
+        ! 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))
         if (i_rxn > 0) then
           associate (xs => this % reactions(i_rxn) % xs(i_temp))
@@ -992,10 +993,11 @@ contains
                f * xs % value(i_grid - xs % threshold + 2)
           end associate
         end if
-        !looping from element 2 to element 6.
+
+        ! Loop over remaining depletion reactions
         do j = 2, 6
-          !If reaction is present and energy is greater than threshold, set
-          !the reaction xs appropriately
+          ! If reaction is present and energy is greater than threshold, set the
+          ! reaction xs appropriately
           i_rxn = this % reaction_index(DEPLETION_RX(j))
           if (i_rxn > 0) then
             associate (xs => this % reactions(i_rxn) % xs(i_temp))
@@ -1003,9 +1005,11 @@ contains
                 micro_xs % reaction(j) = (ONE - f) * &
                      xs % value(i_grid - xs % threshold + 1) + &
                      f * xs % value(i_grid - xs % threshold + 2)
-              !Check if we are below the (n,2n) and/or (n,3n) reaction thresholds to
-              !skip remaining depletion-xs construction.
               elseif (j >= 4) then
+                ! One can show that the the threshold for (n,(x+1)n) is always
+                ! 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).
                 exit
               end if
             end associate