Got rid of all but 16 leaked bytes for the basic model.

src/ace.F90

@@ -165,6 +165,10 @@ contains
       if (allocated(mat % sab_names)) deallocate(mat % sab_names)
 
     end do MATERIAL_LOOP2
+    
+    ! Avoid some valgrind leak errors
+    call already_read % clear()
+    
   end subroutine read_xs
 
 !===============================================================================

src/ace_header.F90

@@ -264,9 +264,11 @@ module ace_header
       if (allocated(this % data)) &
         deallocate(this % data)
         
-      if (associated(this % next)) &
+      if (associated(this % next)) then
         ! recursively clear this item
         call this % next % clear()
+        nullify(this % next)
+      end if
       
     end subroutine DistEnergy_clear
     
@@ -281,8 +283,10 @@ module ace_header
       if (allocated(this % sigma)) &
         deallocate(this % sigma)
       
-      if (associated(this % edist)) &
+      if (associated(this % edist)) then
         call this % edist % clear()
+        deallocate(this % edist)
+      end if
         
       call this % adist % clear()
       

src/dict_header.F90

@@ -428,5 +428,5 @@ contains
     end do
 
   end function dict_keys_ii
-
+  
 end module dict_header

src/global.F90

@@ -420,7 +420,7 @@ contains
     call active_tracklength_tallies % clear()
     call active_current_tallies % clear()
     call active_tallies % clear()
-
+    
   end subroutine free_memory
 
 end module global

src/initialize.F90

@@ -400,7 +400,7 @@ contains
       index_cell_in_univ(i_univ) = index_cell_in_univ(i_univ) + 1
       univ % cells(index_cell_in_univ(i_univ)) = i
     end do
-
+    
   end subroutine prepare_universes
 
 !===============================================================================