diff --git a/src/ace.F90 b/src/ace.F90
index 3ab71869f4..32894116c3 100644
--- a/src/ace.F90
+++ b/src/ace.F90
@@ -13,7 +13,7 @@ module ace
   use material_header,      only: Material
   use output,               only: write_message, print_nuclide, header
   use string,               only: split_string, str_to_int, str_to_real, &
-                                  lower_case, int_to_str
+                                  lower_case, to_str
 
   implicit none
 
@@ -203,7 +203,7 @@ contains
           ! Check to make sure S(a,b) table matched a nuclide
           if (mat % sab_nuclide == 0) then
              message = "S(a,b) table " // trim(mat % sab_name) // " did not match &
-                  &any nuclide on material " // trim(int_to_str(mat % id))
+                  &any nuclide on material " // trim(to_str(mat % id))
              call fatal_error()
           end if
        end if
diff --git a/src/endf.F90 b/src/endf.F90
index 5f35da5b07..92103b5c7e 100644
--- a/src/endf.F90
+++ b/src/endf.F90
@@ -1,7 +1,7 @@
 module endf
 
   use constants
-  use string, only: int_to_str
+  use string, only: to_str
 
 contains
 
@@ -72,7 +72,7 @@ contains
     case (N_NPA)
        string = '(n,npa)'
     case (N_N1 : N_N40)
-       string = '(n,n' // trim(int_to_str(MT-50)) // ')'
+       string = '(n,n' // trim(to_str(MT-50)) // ')'
     case (N_NC)
        string = '(n,nc)'
     case (N_GAMMA)
@@ -122,27 +122,27 @@ contains
     case (444)
        string = '(damage)'
     case (600 : 648)
-       string = '(n,p' // trim(int_to_str(MT-600)) // ')'
+       string = '(n,p' // trim(to_str(MT-600)) // ')'
     case (649)
        string = '(n,pc)'
     case (650 : 698)
-       string = '(n,d' // trim(int_to_str(MT-650)) // ')'
+       string = '(n,d' // trim(to_str(MT-650)) // ')'
     case (699)
        string = '(n,dc)'
     case (700 : 748)
-       string = '(n,t' // trim(int_to_str(MT-700)) // ')'
+       string = '(n,t' // trim(to_str(MT-700)) // ')'
     case (749)
        string = '(n,tc)'
     case (750 : 798)
-       string = '(n,3He' // trim(int_to_str(MT-750)) // ')'
+       string = '(n,3He' // trim(to_str(MT-750)) // ')'
     case (799)
        string = '(n,3Hec)'
     case (800 : 848)
-       string = '(n,a' // trim(int_to_str(MT-800)) // ')'
+       string = '(n,a' // trim(to_str(MT-800)) // ')'
     case (849)
        string = '(n,tc)'
     case default
-       string = 'MT=' // trim(int_to_str(MT))
+       string = 'MT=' // trim(to_str(MT))
     end select
 
   end function reaction_name
diff --git a/src/geometry.F90 b/src/geometry.F90
index 0c5945c09b..983cf5d3c1 100644
--- a/src/geometry.F90
+++ b/src/geometry.F90
@@ -7,7 +7,7 @@ module geometry
   use global
   use output,          only: write_message
   use particle_header, only: Particle, LocalCoord, deallocate_coord
-  use string,          only: int_to_str
+  use string,          only: to_str
   use tally,           only: score_surface_current
 
   implicit none
@@ -249,7 +249,7 @@ contains
 
     surf => surfaces(abs(p % surface))
     if (verbosity >= 10 .or. trace) then
-       message = "    Crossing surface " // trim(int_to_str(surf % id))
+       message = "    Crossing surface " // trim(to_str(surf % id))
        call write_message()
     end if
 
@@ -274,7 +274,7 @@ contains
 
        ! Display message
        if (verbosity >= 10 .or. trace) then
-          message = "    Leaked out of surface " // trim(int_to_str(surf % id))
+          message = "    Leaked out of surface " // trim(to_str(surf % id))
           call write_message()
        end if
        return
@@ -383,7 +383,7 @@ contains
           p % coord0 % uvw = (/ u, v, w /)
        case default
           message = "Reflection not supported for surface " // &
-               trim(int_to_str(surf % id))
+               trim(to_str(surf % id))
           call fatal_error()
        end select
 
@@ -396,7 +396,7 @@ contains
 
        ! Diagnostic message
        if (verbosity >= 10 .or. trace) then
-          message = "    Reflected from surface " // trim(int_to_str(surf%id))
+          message = "    Reflected from surface " // trim(to_str(surf%id))
           call write_message()
        end if
        return
@@ -428,7 +428,7 @@ contains
 
     ! Couldn't find next cell anywhere!
     if ((.not. found) .and. (.not. plotting)) then
-       message = "After particle crossed surface " // trim(int_to_str( &
+       message = "After particle crossed surface " // trim(to_str( &
             surfaces(abs(p%surface)) % id)) // " it could not be located in &
             &any cell and it did not leak."
        call fatal_error()
@@ -455,9 +455,9 @@ contains
     lat => lattices(p % coord % lattice)
 
     if (verbosity >= 10 .or. trace) then
-       message = "    Crossing lattice " // trim(int_to_str(lat % id)) // &
-            ". Current position (" // trim(int_to_str(p % coord % lattice_x)) &
-            // "," // trim(int_to_str(p % coord % lattice_y)) // ")"
+       message = "    Crossing lattice " // trim(to_str(lat % id)) // &
+            ". Current position (" // trim(to_str(p % coord % lattice_x)) &
+            // "," // trim(to_str(p % coord % lattice_y)) // ")"
        call write_message()
     end if
 
@@ -495,14 +495,14 @@ contains
     i_x = p % coord % lattice_x
     i_y = p % coord % lattice_y
     if (i_x < 1 .or. i_x > lat % n_x) then
-       message = "Reached edge of lattice " // trim(int_to_str(lat % id)) // &
-            " at position (" // trim(int_to_str(i_x)) // "," // &
-            trim(int_to_str(i_y)) // ")."
+       message = "Reached edge of lattice " // trim(to_str(lat % id)) // &
+            " at position (" // trim(to_str(i_x)) // "," // &
+            trim(to_str(i_y)) // ")."
        call fatal_error()
     elseif (i_y < 1 .or. i_y > lat % n_y) then
-       message = "Reached edge of lattice " // trim(int_to_str(lat % id)) // &
-            " at position (" // trim(int_to_str(i_x)) // "," // &
-            trim(int_to_str(i_y)) // ")."
+       message = "Reached edge of lattice " // trim(to_str(lat % id)) // &
+            " at position (" // trim(to_str(i_x)) // "," // &
+            trim(to_str(i_y)) // ")."
        call fatal_error()
     end if
 
@@ -512,8 +512,8 @@ contains
     ! Find cell in next lattice element
     call find_cell(p, found)
     if (.not. found) then
-       message = "Could not locate particle in universe: " // &
-            int_to_str(universes(p % coord % universe) % id)
+       message = "Could not locate particle " // trim(to_str(p % id)) // &
+            " in universe " // to_str(universes(p % coord % universe) % id)
        call fatal_error()
     end if
 
diff --git a/src/initialize.F90 b/src/initialize.F90
index 248387a8b6..1bcae2ef36 100644
--- a/src/initialize.F90
+++ b/src/initialize.F90
@@ -17,7 +17,7 @@ module initialize
                               print_plot, create_summary_file
   use random_lcg,       only: initialize_prng
   use source,           only: initialize_source
-  use string,           only: int_to_str, starts_with, ends_with, lower_case
+  use string,           only: to_str, starts_with, ends_with, lower_case
   use tally,            only: create_tally_map, TallyObject
   use timing,           only: timer_start, timer_stop
 
@@ -375,8 +375,8 @@ contains
                 i_array = dict_get_key(surface_dict, abs(id))
                 c % surfaces(j) = sign(i_array, id)
              else
-                message = "Could not find surface " // trim(int_to_str(abs(id))) // &
-                     " specified on cell " // trim(int_to_str(c % id))
+                message = "Could not find surface " // trim(to_str(abs(id))) // &
+                     " specified on cell " // trim(to_str(c % id))
                 call fatal_error()
              end if
           end if
@@ -389,8 +389,8 @@ contains
        if (dict_has_key(universe_dict, id)) then
           c % universe = dict_get_key(universe_dict, id)
        else
-          message = "Could not find universe " // trim(int_to_str(id)) // &
-               " specified on cell " // trim(int_to_str(c % id))
+          message = "Could not find universe " // trim(to_str(id)) // &
+               " specified on cell " // trim(to_str(c % id))
           call fatal_error()
        end if
 
@@ -403,8 +403,8 @@ contains
              c % type = CELL_NORMAL
              c % material = dict_get_key(material_dict, id)
           else
-             message = "Could not find material " // trim(int_to_str(id)) // &
-                   " specified on cell " // trim(int_to_str(c % id))
+             message = "Could not find material " // trim(to_str(id)) // &
+                   " specified on cell " // trim(to_str(c % id))
              call fatal_error()
           end if
        else
@@ -416,8 +416,8 @@ contains
              c % type = CELL_LATTICE
              c % fill = dict_get_key(lattice_dict, id)
           else
-             message = "Specified fill " // trim(int_to_str(id)) // " on cell " // &
-                  trim(int_to_str(c % id)) // " is neither a universe nor a lattice."
+             message = "Specified fill " // trim(to_str(id)) // " on cell " // &
+                  trim(to_str(c % id)) // " is neither a universe nor a lattice."
              call fatal_error()
           end if
        end if
@@ -434,8 +434,8 @@ contains
              if (dict_has_key(universe_dict, id)) then
                 l % element(j,k) = dict_get_key(universe_dict, id)
              else
-                message = "Invalid universe number " // trim(int_to_str(id)) &
-                     // " specified on lattice " // trim(int_to_str(l % id))
+                message = "Invalid universe number " // trim(to_str(id)) &
+                     // " specified on lattice " // trim(to_str(l % id))
                 call fatal_error()
              end if
           end do
@@ -454,8 +454,8 @@ contains
              if (dict_has_key(cell_dict, id)) then
                 t % cell_bins(j) % scalar = dict_get_key(cell_dict, id)
              else
-                message = "Could not find cell " // trim(int_to_str(id)) // &
-                     " specified on tally " // trim(int_to_str(t % id))
+                message = "Could not find cell " // trim(to_str(id)) // &
+                     " specified on tally " // trim(to_str(t % id))
                 call fatal_error()
              end if
           end do
@@ -470,8 +470,8 @@ contains
              if (dict_has_key(surface_dict, id)) then
                 t % surface_bins(j) % scalar = dict_get_key(surface_dict, id)
              else
-                message = "Could not find surface " // trim(int_to_str(id)) // &
-                     " specified on tally " // trim(int_to_str(t % id))
+                message = "Could not find surface " // trim(to_str(id)) // &
+                     " specified on tally " // trim(to_str(t % id))
                 call fatal_error()
              end if
           end do
@@ -486,8 +486,8 @@ contains
              if (dict_has_key(universe_dict, id)) then
                 t % universe_bins(j) % scalar = dict_get_key(universe_dict, id)
              else
-                message = "Could not find universe " // trim(int_to_str(id)) // &
-                     " specified on tally " // trim(int_to_str(t % id))
+                message = "Could not find universe " // trim(to_str(id)) // &
+                     " specified on tally " // trim(to_str(t % id))
                 call fatal_error()
              end if
           end do
@@ -502,8 +502,8 @@ contains
              if (dict_has_key(material_dict, id)) then
                 t % material_bins(j) % scalar = dict_get_key(material_dict, id)
              else
-                message = "Could not find material " // trim(int_to_str(id)) // &
-                     " specified on tally " // trim(int_to_str(t % id))
+                message = "Could not find material " // trim(to_str(id)) // &
+                     " specified on tally " // trim(to_str(t % id))
                 call fatal_error()
              end if
           end do
@@ -518,8 +518,8 @@ contains
              if (dict_has_key(cell_dict, id)) then
                 t % cellborn_bins(j) % scalar = dict_get_key(cell_dict, id)
              else
-                message = "Could not find material " // trim(int_to_str(id)) // &
-                     " specified on tally " // trim(int_to_str(t % id))
+                message = "Could not find material " // trim(to_str(id)) // &
+                     " specified on tally " // trim(to_str(t % id))
                 call fatal_error()
              end if
           end do
@@ -533,8 +533,8 @@ contains
           if (dict_has_key(mesh_dict, id)) then
              t % mesh = dict_get_key(mesh_dict, id)
           else
-             message = "Could not find mesh " // trim(int_to_str(id)) // &
-                  " specified on tally " // trim(int_to_str(t % id))
+             message = "Could not find mesh " // trim(to_str(id)) // &
+                  " specified on tally " // trim(to_str(t % id))
              call fatal_error()
           end if
        end if
@@ -626,7 +626,7 @@ contains
        if (.not. (all(mat%atom_percent > ZERO) .or. & 
             all(mat%atom_percent < ZERO))) then
           message = "Cannot mix atom and weight percents in material " // &
-               int_to_str(mat % id)
+               to_str(mat % id)
           call fatal_error()
        end if
 
diff --git a/src/input_xml.F90 b/src/input_xml.F90
index f96682724a..e6c46cba60 100644
--- a/src/input_xml.F90
+++ b/src/input_xml.F90
@@ -8,7 +8,7 @@ module input_xml
   use global
   use mesh_header,     only: StructuredMesh
   use output,          only: write_message
-  use string,          only: lower_case, int_to_str, str_to_int, str_to_real,  &
+  use string,          only: lower_case, to_str, str_to_int, str_to_real,  &
                              split_string, starts_with, ends_with
   use tally_header,    only: TallyObject
 
@@ -224,7 +224,7 @@ contains
        ! Check to make sure that either material or fill was specified
        if (c % material == 0 .and. c % fill == 0) then
           message = "Neither material nor fill was specified for cell " // & 
-               trim(int_to_str(c % id))
+               trim(to_str(c % id))
           call fatal_error()
        end if
 
@@ -238,7 +238,7 @@ contains
        ! Check to make sure that surfaces were specified
        if (.not. associated(cell_(i) % surfaces)) then
           message = "No surfaces specified for cell " // &
-               trim(int_to_str(c % id))
+               trim(to_str(c % id))
           call fatal_error()
        end if
 
@@ -334,11 +334,11 @@ contains
        n = size(surface_(i) % coeffs)
        if (n < coeffs_reqd) then
           message = "Not enough coefficients specified for surface: " // & 
-               trim(int_to_str(s % id))
+               trim(to_str(s % id))
           call fatal_error()
        elseif (n > coeffs_reqd) then
           message = "Too many coefficients specified for surface: " // &
-               trim(int_to_str(s % id))
+               trim(to_str(s % id))
           call fatal_error()
        else
           allocate(s % coeffs(n))
@@ -359,7 +359,7 @@ contains
           s % bc = BC_PERIODIC
        case default
           message = "Unknown boundary condition '" // trim(word) // &
-               "' specified on surface " // trim(int_to_str(s % id))
+               "' specified on surface " // trim(to_str(s % id))
           call fatal_error()
        end select
 
@@ -507,14 +507,14 @@ contains
           m % density = 1.0e-24 * val
        case default
           message = "Unkwown units '" // trim(material_(i) % density % units) &
-               // "' specified on material " // trim(int_to_str(m % id))
+               // "' specified on material " // trim(to_str(m % id))
           call fatal_error()
        end select
        
        ! Check to ensure material has at least one nuclide
        if (.not. associated(material_(i) % nuclides)) then
           message = "No nuclides specified on material " // &
-               trim(int_to_str(m % id))
+               trim(to_str(m % id))
           call fatal_error()
        end if
 
@@ -534,7 +534,7 @@ contains
           ! Check for empty name on nuclide
           if (len_trim(nuc % name) == 0) then
              message = "No name specified on nuclide in material " // &
-                  trim(int_to_str(m % id))
+                  trim(to_str(m % id))
              call fatal_error()
           end if
 
@@ -542,7 +542,7 @@ contains
           if (len_trim(nuc % xs) == 0) then
              if (default_xs == '') then
                 message = "No cross section specified for nuclide in material " &
-                     // trim(int_to_str(m % id))
+                     // trim(to_str(m % id))
                 call fatal_error()
              else
                 nuc % xs = default_xs
@@ -733,7 +733,7 @@ contains
        if (len_trim(tally_(i) % filters % cell) > 0 .and. &
             len_trim(tally_(i) % filters % surface) > 0) then
           message = "Cannot specify both cell and surface filters for tally " &
-               // trim(int_to_str(t % id))
+               // trim(to_str(t % id))
           call fatal_error()
        end if
 
@@ -788,8 +788,8 @@ contains
              i_mesh = dict_get_key(mesh_dict, id)
              m => meshes(i_mesh)
           else
-             message = "Could not find mesh " // trim(int_to_str(id)) // &
-                  " specified on tally " // trim(int_to_str(t % id))
+             message = "Could not find mesh " // trim(to_str(id)) // &
+                  " specified on tally " // trim(to_str(t % id))
              call fatal_error()
           end if
 
diff --git a/src/interpolation.F90 b/src/interpolation.F90
index 8e3f083ff5..549b720e0b 100644
--- a/src/interpolation.F90
+++ b/src/interpolation.F90
@@ -5,7 +5,7 @@ module interpolation
   use error,       only: fatal_error
   use global,      only: message
   use search,      only: binary_search
-  use string,      only: int_to_str
+  use string,      only: to_str
 
   implicit none
 
@@ -118,7 +118,7 @@ contains
        r = (log(x) - log(x0))/(log(x1) - log(x0))
        y = exp((1-r)*log(y0) + r*log(y1))
     case default
-       message = "Unsupported interpolation scheme: " // int_to_str(interp)
+       message = "Unsupported interpolation scheme: " // to_str(interp)
        call fatal_error()
     end select
     
@@ -204,7 +204,7 @@ contains
        r = (log(x) - log(x0))/(log(x1) - log(x0))
        y = exp((1-r)*log(y0) + r*log(y1))
     case default
-       message = "Unsupported interpolation scheme: " // int_to_str(interp)
+       message = "Unsupported interpolation scheme: " // to_str(interp)
        call fatal_error()
     end select
     
diff --git a/src/main.F90 b/src/main.F90
index 9586f8bc40..199da60dc0 100644
--- a/src/main.F90
+++ b/src/main.F90
@@ -10,7 +10,7 @@ program main
   use physics,         only: transport
   use random_lcg,      only: set_particle_seed
   use source,          only: get_source_particle
-  use string,          only: int_to_str
+  use string,          only: to_str
   use tally,           only: synchronize_tallies, write_tallies, &
                              tally_statistics
   use timing,          only: timer_start, timer_stop
@@ -88,7 +88,7 @@ contains
        ! Start timer for computation
        call timer_start(time_compute)
 
-       message = "Simulating cycle " // trim(int_to_str(i_cycle)) // "..."
+       message = "Simulating cycle " // trim(to_str(i_cycle)) // "..."
        call write_message(8)
 
        ! Set all tallies to zero
diff --git a/src/output.F90 b/src/output.F90
index b09b97fb52..7b2898528c 100644
--- a/src/output.F90
+++ b/src/output.F90
@@ -10,7 +10,7 @@ module output
   use global
   use mesh_header,     only: StructuredMesh
   use particle_header, only: Particle, LocalCoord
-  use string,          only: upper_case, int_to_str, real_to_str
+  use string,          only: upper_case, to_str
   use tally_header,    only: TallyObject
 
   implicit none
@@ -67,9 +67,9 @@ contains
     ! Write information on number of processors
 #ifdef MPI
     write(UNIT=OUTPUT_UNIT, FMT='(1X,A)') '     MPI Processes: ' // &
-         trim(int_to_str(n_procs))
+         trim(to_str(n_procs))
     write(UNIT=UNIT_SUMMARY, FMT='(1X,"MPI Processes:",1X,A)') &
-         trim(int_to_str(n_procs))
+         trim(to_str(n_procs))
 #endif
 
   end subroutine title
@@ -213,13 +213,13 @@ contains
     ! display type of particle
     select case (p % type)
     case (NEUTRON)
-       write(ou,*) 'Neutron ' // int_to_str(p % id)
+       write(ou,*) 'Neutron ' // to_str(p % id)
     case (PHOTON)
-       write(ou,*) 'Photon ' // int_to_str(p % id)
+       write(ou,*) 'Photon ' // to_str(p % id)
     case (ELECTRON)
-       write(ou,*) 'Electron ' // int_to_str(p % id)
+       write(ou,*) 'Electron ' // to_str(p % id)
     case default
-       write(ou,*) 'Unknown Particle ' // int_to_str(p % id)
+       write(ou,*) 'Unknown Particle ' // to_str(p % id)
     end select
 
     ! loop through each level of universes
@@ -227,26 +227,26 @@ contains
     i = 0
     do while(associated(coord))
        ! Print level
-       write(ou,*) '  Level ' // trim(int_to_str(i))
+       write(ou,*) '  Level ' // trim(to_str(i))
 
        ! Print cell for this level
        if (coord % cell /= NONE) then
           c => cells(coord % cell)
-          write(ou,*) '    Cell             = ' // trim(int_to_str(c % id))
+          write(ou,*) '    Cell             = ' // trim(to_str(c % id))
        end if
 
        ! Print universe for this level
        if (coord % universe /= NONE) then
           u => universes(coord % universe)
-          write(ou,*) '    Universe         = ' // trim(int_to_str(u % id))
+          write(ou,*) '    Universe         = ' // trim(to_str(u % id))
        end if
 
        ! Print information on lattice
        if (coord % lattice /= NONE) then
           l => lattices(coord % lattice)
-          write(ou,*) '    Lattice          = ' // trim(int_to_str(l % id))
-          write(ou,*) '    Lattice position = (' // trim(int_to_str(&
-               p % coord % lattice_x)) // ',' // trim(int_to_str(&
+          write(ou,*) '    Lattice          = ' // trim(to_str(l % id))
+          write(ou,*) '    Lattice position = (' // trim(to_str(&
+               p % coord % lattice_x)) // ',' // trim(to_str(&
                p % coord % lattice_y)) // ')'
        end if
 
@@ -261,13 +261,13 @@ contains
     ! Print surface
     if (p % surface /= NONE) then
        s => surfaces(p % surface)
-       write(ou,*) '    Surface = ' // int_to_str(s % id)
+       write(ou,*) '    Surface = ' // to_str(s % id)
     end if
 
-    write(ou,*) '  Weight = ' // real_to_str(p % wgt)
-    write(ou,*) '  Energy = ' // real_to_str(p % E)
-    write(ou,*) '  IE = ' // int_to_str(p % IE)
-    write(ou,*) '  Interpolation factor = ' // real_to_str(p % interp)
+    write(ou,*) '  Weight = ' // to_str(p % wgt)
+    write(ou,*) '  Energy = ' // to_str(p % E)
+    write(ou,*) '  IE = ' // to_str(p % IE)
+    write(ou,*) '  Interpolation factor = ' // to_str(p % interp)
     write(ou,*)
 
   end subroutine print_particle
@@ -281,12 +281,12 @@ contains
     type(Reaction), pointer :: rxn
 
     write(ou,*) 'Reaction ' // reaction_name(rxn % MT)
-    write(ou,*) '    MT = ' // int_to_str(rxn % MT)
-    write(ou,*) '    Q-value = ' // real_to_str(rxn % Q_value)
-    write(ou,*) '    TY = ' // int_to_str(rxn % TY)
-    write(ou,*) '    Starting index = ' // int_to_str(rxn % IE)
+    write(ou,*) '    MT = ' // to_str(rxn % MT)
+    write(ou,*) '    Q-value = ' // to_str(rxn % Q_value)
+    write(ou,*) '    TY = ' // to_str(rxn % TY)
+    write(ou,*) '    Starting index = ' // to_str(rxn % IE)
     if (rxn % has_energy_dist) then
-       write(ou,*) '    Energy: Law ' // int_to_str(rxn % edist % law)
+       write(ou,*) '    Energy: Law ' // to_str(rxn % edist % law)
     end if
     write(ou,*)
 
@@ -315,28 +315,28 @@ contains
        unit_ = OUTPUT_UNIT
     end if
 
-    write(unit_,*) 'Cell ' // int_to_str(c % id)
+    write(unit_,*) 'Cell ' // to_str(c % id)
     temp = dict_get_key(cell_dict, c % id)
-    write(unit_,*) '    Array Index = ' // int_to_str(temp)
+    write(unit_,*) '    Array Index = ' // to_str(temp)
     u => universes(c % universe)
-    write(unit_,*) '    Universe = ' // int_to_str(u % id)
+    write(unit_,*) '    Universe = ' // to_str(u % id)
     select case (c % type)
     case (CELL_NORMAL)
        write(unit_,*) '    Fill = NONE'
     case (CELL_FILL)
        u => universes(c % fill)
-       write(unit_,*) '    Fill = Universe ' // int_to_str(u % id)
+       write(unit_,*) '    Fill = Universe ' // to_str(u % id)
     case (CELL_LATTICE)
        l => lattices(c % fill)
-       write(unit_,*) '    Fill = Lattice ' // int_to_str(l % id)
+       write(unit_,*) '    Fill = Lattice ' // to_str(l % id)
     end select
     if (c % material == 0) then
        write(unit_,*) '    Material = NONE'
     else
        m => materials(c % material)
-       write(unit_,*) '    Material = ' // int_to_str(m % id)
+       write(unit_,*) '    Material = ' // to_str(m % id)
     end if
-    write(unit_,*) '    Parent Cell = ' // int_to_str(c % parent)
+    write(unit_,*) '    Parent Cell = ' // to_str(c % parent)
     string = ""
     do i = 1, c % n_surfaces
        select case (c % surfaces(i))
@@ -349,7 +349,7 @@ contains
        case (OP_DIFFERENCE)
           string = trim(string) // ' !'
        case default
-          string = trim(string) // ' ' // int_to_str(c % surfaces(i))
+          string = trim(string) // ' ' // to_str(c % surfaces(i))
        end select
     end do
     write(unit_,*) '    Surface Specification:' // trim(string)
@@ -377,12 +377,12 @@ contains
        unit_ = OUTPUT_UNIT
     end if
 
-    write(unit_,*) 'Universe ' // int_to_str(univ % id)
-    write(unit_,*) '    Level = ' // int_to_str(univ % level)
+    write(unit_,*) 'Universe ' // to_str(univ % id)
+    write(unit_,*) '    Level = ' // to_str(univ % level)
     string = ""
     do i = 1, univ % n_cells
        c => cells(univ % cells(i))
-       string = trim(string) // ' ' // int_to_str(c % id)
+       string = trim(string) // ' ' // to_str(c % id)
     end do
     write(unit_,*) '    Cells =' // trim(string)
     write(unit_,*)
@@ -406,13 +406,13 @@ contains
        unit_ = OUTPUT_UNIT
     end if
 
-    write(unit_,*) 'Lattice ' // int_to_str(lat % id)
-    write(unit_,*) '    n_x = ' // int_to_str(lat % n_x)
-    write(unit_,*) '    n_y = ' // int_to_str(lat % n_y)
-    write(unit_,*) '    x0 = ' // real_to_str(lat % x0)
-    write(unit_,*) '    y0 = ' // real_to_str(lat % y0)
-    write(unit_,*) '    width_x = ' // real_to_str(lat % width_x)
-    write(unit_,*) '    width_y = ' // real_to_str(lat % width_y)
+    write(unit_,*) 'Lattice ' // to_str(lat % id)
+    write(unit_,*) '    n_x = ' // to_str(lat % n_x)
+    write(unit_,*) '    n_y = ' // to_str(lat % n_y)
+    write(unit_,*) '    x0 = ' // to_str(lat % x0)
+    write(unit_,*) '    y0 = ' // to_str(lat % y0)
+    write(unit_,*) '    width_x = ' // to_str(lat % width_x)
+    write(unit_,*) '    width_y = ' // to_str(lat % width_y)
     write(unit_,*)
 
   end subroutine print_lattice
@@ -436,7 +436,7 @@ contains
        unit_ = OUTPUT_UNIT
     end if
 
-    write(unit_,*) 'Surface ' // int_to_str(surf % id)
+    write(unit_,*) 'Surface ' // to_str(surf % id)
     select case (surf % type)
     case (SURF_PX)
        string = "X Plane"
@@ -465,14 +465,14 @@ contains
 
     string = ""
     do i = 1, size(surf % coeffs)
-       string = trim(string) // ' ' // real_to_str(surf % coeffs(i), 4)
+       string = trim(string) // ' ' // to_str(surf % coeffs(i), 4)
     end do
     write(unit_,*) '    Coefficients = ' // trim(string)
 
     string = ""
     if (allocated(surf % neighbor_pos)) then
        do i = 1, size(surf % neighbor_pos)
-          string = trim(string) // ' ' // int_to_str(surf % neighbor_pos(i))
+          string = trim(string) // ' ' // to_str(surf % neighbor_pos(i))
        end do
     end if
     write(unit_,*) '    Positive Neighbors = ' // trim(string)
@@ -480,7 +480,7 @@ contains
     string = ""
     if (allocated(surf % neighbor_neg)) then
        do i = 1, size(surf % neighbor_neg)
-          string = trim(string) // ' ' // int_to_str(surf % neighbor_neg(i))
+          string = trim(string) // ' ' // to_str(surf % neighbor_neg(i))
        end do
     end if
     write(unit_,*) '    Negative Neighbors =' // trim(string)
@@ -520,10 +520,10 @@ contains
     end if
 
     ! Write identifier for material
-    write(unit_,*) 'Material ' // int_to_str(mat % id)
+    write(unit_,*) 'Material ' // to_str(mat % id)
 
     ! Write total atom density in atom/b-cm
-    write(unit_,*) '    Atom Density = ' // trim(real_to_str(mat % density)) &
+    write(unit_,*) '    Atom Density = ' // trim(to_str(mat % density)) &
          // ' atom/b-cm'
 
     ! Write atom density for each nuclide in material
@@ -532,7 +532,7 @@ contains
        nuc => nuclides(mat % nuclide(i))
        density = mat % atom_density(i)
        string = '        ' // trim(nuc % name) // ' = ' // &
-            trim(real_to_str(density)) // ' atom/b-cm'
+            trim(to_str(density)) // ' atom/b-cm'
        write(unit_,*) trim(string)
     end do
 
@@ -569,14 +569,14 @@ contains
        unit_ = OUTPUT_UNIT
     end if
 
-    write(unit_,*) 'Tally ' // int_to_str(t % id)
+    write(unit_,*) 'Tally ' // to_str(t % id)
 
     if (t % n_bins(T_CELL) > 0) then
        string = ""
        do i = 1, t % n_bins(T_CELL)
           id = t % cell_bins(i) % scalar
           c => cells(id)
-          string = trim(string) // ' ' // trim(int_to_str(c % id))
+          string = trim(string) // ' ' // trim(to_str(c % id))
        end do
        write(unit_, *) '    Cell Bins:' // trim(string)
     end if
@@ -586,7 +586,7 @@ contains
        do i = 1, t % n_bins(T_SURFACE)
           id = t % surface_bins(i) % scalar
           s => surfaces(id)
-          string = trim(string) // ' ' // trim(int_to_str(s % id))
+          string = trim(string) // ' ' // trim(to_str(s % id))
        end do
        write(unit_, *) '    Surface Bins:' // trim(string)
     end if
@@ -596,7 +596,7 @@ contains
        do i = 1, t % n_bins(T_UNIVERSE)
           id = t % universe_bins(i) % scalar
           u => universes(id)
-          string = trim(string) // ' ' // trim(int_to_str(u % id))
+          string = trim(string) // ' ' // trim(to_str(u % id))
        end do
        write(unit_, *) '    Material Bins:' // trim(string)
     end if
@@ -606,7 +606,7 @@ contains
        do i = 1, t % n_bins(T_MATERIAL)
           id = t % material_bins(i) % scalar
           m => materials(id)
-          string = trim(string) // ' ' // trim(int_to_str(m % id))
+          string = trim(string) // ' ' // trim(to_str(m % id))
        end do
        write(unit_, *) '    Material Bins:' // trim(string)
     end if
@@ -615,9 +615,9 @@ contains
        string = ""
        id = t % mesh
        sm => meshes(id)
-       string = trim(string) // ' ' // trim(int_to_str(sm % dimension(1)))
+       string = trim(string) // ' ' // trim(to_str(sm % dimension(1)))
        do i = 2, sm % n_dimension
-          string = trim(string) // ' x ' // trim(int_to_str(sm % dimension(i)))
+          string = trim(string) // ' x ' // trim(to_str(sm % dimension(i)))
        end do
        write(unit_, *) '    Mesh Bins:' // trim(string)
     end if
@@ -627,7 +627,7 @@ contains
        do i = 1, t % n_bins(T_CELLBORN)
           id = t % cellborn_bins(i) % scalar
           c => cells(id)
-          string = trim(string) // ' ' // trim(int_to_str(c % id))
+          string = trim(string) // ' ' // trim(to_str(c % id))
        end do
        write(unit_, *) '    Birth Region Bins:' // trim(string)
     end if
@@ -635,7 +635,7 @@ contains
     if (t % n_bins(T_ENERGYIN) > 0) then
        string = ""
        do i = 1, t % n_bins(T_ENERGYIN) + 1
-          string = trim(string) // ' ' // trim(real_to_str(&
+          string = trim(string) // ' ' // trim(to_str(&
                t % energy_in(i)))
        end do
        write(unit_,*) '    Incoming Energy Bins:' // trim(string)
@@ -644,7 +644,7 @@ contains
     if (t % n_bins(T_ENERGYOUT) > 0) then
        string = ""
        do i = 1, t % n_bins(T_ENERGYOUT) + 1
-          string = trim(string) // ' ' // trim(real_to_str(&
+          string = trim(string) // ' ' // trim(to_str(&
                t % energy_out(i)))
        end do
        write(unit_,*) '    Outgoing Energy Bins:' // trim(string)
@@ -751,14 +751,14 @@ contains
 
     ! Basic nuclide information
     write(unit_,*) 'Nuclide ' // trim(nuc % name)
-    write(unit_,*) '  zaid = ' // trim(int_to_str(nuc % zaid))
-    write(unit_,*) '  awr = ' // trim(real_to_str(nuc % awr))
-    write(unit_,*) '  kT = ' // trim(real_to_str(nuc % kT))
-    write(unit_,*) '  # of grid points = ' // trim(int_to_str(nuc % n_grid))
+    write(unit_,*) '  zaid = ' // trim(to_str(nuc % zaid))
+    write(unit_,*) '  awr = ' // trim(to_str(nuc % awr))
+    write(unit_,*) '  kT = ' // trim(to_str(nuc % kT))
+    write(unit_,*) '  # of grid points = ' // trim(to_str(nuc % n_grid))
     write(unit_,*) '  Fissionable = ', nuc % fissionable
-    write(unit_,*) '  # of fission reactions = ' // trim(int_to_str(nuc % n_fission))
-    write(unit_,*) '  # of reactions = ' // trim(int_to_str(nuc % n_reaction))
-    write(unit_,*) '  Size of cross sections = ' // trim(int_to_str(&
+    write(unit_,*) '  # of fission reactions = ' // trim(to_str(nuc % n_fission))
+    write(unit_,*) '  # of reactions = ' // trim(to_str(nuc % n_reaction))
+    write(unit_,*) '  Size of cross sections = ' // trim(to_str(&
          size_xs)) // ' bytes'
 
     write(unit_,*) '  Reaction    Q-value   Mult    IE    size(angle) size(energy)'
@@ -792,18 +792,18 @@ contains
     if (nuc % urr_present) then
        urr => nuc % urr_data
        write(unit_,*) '  Unresolved resonance probability table:'
-       write(unit_,*) '    # of energies = ' // trim(int_to_str(urr % n_energy))
-       write(unit_,*) '    # of probabilities = ' // trim(int_to_str(urr % n_prob))
-       write(unit_,*) '    Interpolation =  ' // trim(int_to_str(urr % interp))
-       write(unit_,*) '    Inelastic flag = ' // trim(int_to_str(urr % inelastic_flag))
-       write(unit_,*) '    Absorption flag = ' // trim(int_to_str(urr % absorption_flag))
+       write(unit_,*) '    # of energies = ' // trim(to_str(urr % n_energy))
+       write(unit_,*) '    # of probabilities = ' // trim(to_str(urr % n_prob))
+       write(unit_,*) '    Interpolation =  ' // trim(to_str(urr % interp))
+       write(unit_,*) '    Inelastic flag = ' // trim(to_str(urr % inelastic_flag))
+       write(unit_,*) '    Absorption flag = ' // trim(to_str(urr % absorption_flag))
        write(unit_,*) '    Multiply by smooth? ', urr % multiply_smooth
-       write(unit_,*) '    Min energy = ', trim(real_to_str(urr % energy(1)))
-       write(unit_,*) '    Max energy = ', trim(real_to_str(urr % energy(urr % n_energy)))
+       write(unit_,*) '    Min energy = ', trim(to_str(urr % energy(1)))
+       write(unit_,*) '    Max energy = ', trim(to_str(urr % energy(urr % n_energy)))
     end if
 
     ! Write total memory used
-    write(unit_,*) '  Total memory used = ' // trim(int_to_str(size_total)) &
+    write(unit_,*) '  Total memory used = ' // trim(to_str(size_total)) &
          // ' bytes'
 
     ! Blank line at end of nuclide
@@ -861,8 +861,8 @@ contains
 
     ! print summary of unionized energy grid
     call header("UNIONIZED ENERGY GRID", unit=UNIT_SUMMARY)
-    write(UNIT_SUMMARY,*) "Points on energy grid:  " // trim(int_to_str(n_grid))
-    write(UNIT_SUMMARY,*) "Extra storage required: " // trim(int_to_str(&
+    write(UNIT_SUMMARY,*) "Points on energy grid:  " // trim(to_str(n_grid))
+    write(UNIT_SUMMARY,*) "Extra storage required: " // trim(to_str(&
          n_grid*n_nuclides_total*4)) // " bytes"
 
     ! print summary of variance reduction
@@ -872,9 +872,9 @@ contains
     else
        write(UNIT_SUMMARY,100) "Survival Biasing:", "off"
     end if
-    string = real_to_str(weight_cutoff)
+    string = to_str(weight_cutoff)
     write(UNIT_SUMMARY,100) "Weight Cutoff:", trim(string)
-    string = real_to_str(weight_survive)
+    string = to_str(weight_survive)
     write(UNIT_SUMMARY,100) "Survival weight:", trim(string)
 
     ! Format descriptor for columns
@@ -893,16 +893,16 @@ contains
     call header("PLOTTING SUMMARY")
 
     ! Print plotting origin
-    write(ou,100) "Plotting Origin:", trim(real_to_str(plot_origin(1))) // &
-         " " // trim(real_to_str(plot_origin(2))) // " " // &
-         trim(real_to_str(plot_origin(3)))
+    write(ou,100) "Plotting Origin:", trim(to_str(plot_origin(1))) // &
+         " " // trim(to_str(plot_origin(2))) // " " // &
+         trim(to_str(plot_origin(3)))
 
     ! Print plotting width
-    write(ou,100) "Plotting Width:", trim(real_to_str(plot_width(1))) // &
-         " " // trim(real_to_str(plot_width(2)))
+    write(ou,100) "Plotting Width:", trim(to_str(plot_width(1))) // &
+         " " // trim(to_str(plot_width(2)))
 
     ! Print pixel width
-    write(ou,100) "Pixel Width:", trim(real_to_str(pixel))
+    write(ou,100) "Pixel Width:", trim(to_str(pixel))
     write(ou,*)
 
     ! Format descriptor for columns
@@ -944,7 +944,7 @@ contains
     ! display calculate rate and final keff
     total_particles = n_particles * n_cycles
     speed = real(total_particles) / time_compute % elapsed
-    string = real_to_str(speed)
+    string = to_str(speed)
     write(ou,101) "Calculation Rate", trim(string)
     write(ou,102) "Final Keff", keff, keff_std
     write(ou,*)
diff --git a/src/physics.F90 b/src/physics.F90
index 449ee990b5..685e379bd4 100644
--- a/src/physics.F90
+++ b/src/physics.F90
@@ -15,7 +15,7 @@ module physics
   use particle_header, only: Particle, LocalCoord
   use random_lcg,      only: prn
   use search,          only: binary_search
-  use string,          only: int_to_str, real_to_str
+  use string,          only: to_str
   use tally,           only: score_tally, score_surface_current
 
   implicit none
@@ -54,12 +54,12 @@ contains
     end if
 
     if (verbosity >= 9 .or. trace) then
-       message = "Simulating Particle " // trim(int_to_str(p % id))
+       message = "Simulating Particle " // trim(to_str(p % id))
        call write_message()
     end if
 
     if (verbosity >= 10 .or. trace) then
-       message = "    Born in cell " // trim(int_to_str(&
+       message = "    Born in cell " // trim(to_str(&
             cells(p % coord % cell) % id))
        call write_message()
     end if
@@ -126,7 +126,7 @@ contains
        ! If particle has too many events, display warning and kill it
        n_event = n_event + 1
        if (n_event == MAX_EVENTS) then
-          message = "Particle " // trim(int_to_str(p%id)) // " underwent " & 
+          message = "Particle " // trim(to_str(p%id)) // " underwent " & 
                // "maximum number of events."
           call warning()
           p % alive = .false.
@@ -168,7 +168,7 @@ contains
     ! Display information about collision
     if (verbosity >= 10 .or. trace) then
        message = "    " // trim(reaction_name(MT)) // ". Energy = " // &
-            trim(real_to_str(p % E * 1e6_8)) // " eV."
+            trim(to_str(p % E * 1e6_8)) // " eV."
        call write_message()
     end if
 
@@ -417,7 +417,7 @@ contains
           if (i > nuc % n_reaction) then
              message = "Did not sample any reaction for nuclide " // &
                   trim(nuc % name) // " on material " // &
-                  trim(int_to_str(mat % id))
+                  trim(to_str(mat % id))
              call fatal_error()
           end if
 
@@ -1136,7 +1136,7 @@ contains
              mu = mu0 + (sqrt(p0*p0 + 2*frac*(xi - c_k))-p0)/frac
           end if
        else
-          message = "Unknown interpolation type: " // trim(int_to_str(interp))
+          message = "Unknown interpolation type: " // trim(to_str(interp))
           call fatal_error()
        end if
 
@@ -1148,7 +1148,7 @@ contains
        end if
          
     else
-       message = "Unknown angular distribution type: " // trim(int_to_str(type))
+       message = "Unknown angular distribution type: " // trim(to_str(type))
        call fatal_error()
     end if
     
@@ -1455,7 +1455,7 @@ contains
                   p_l_k)/frac
           end if
        else
-          message = "Unknown interpolation type: " // trim(int_to_str(INTT))
+          message = "Unknown interpolation type: " // trim(to_str(INTT))
           call fatal_error()
        end if
 
@@ -1696,7 +1696,7 @@ contains
           KM_R = R_k + (R_k1 - R_k)*(E_out - E_l_k)/(E_l_k1 - E_l_k)
           KM_A = A_k + (A_k1 - A_k)*(E_out - E_l_k)/(E_l_k1 - E_l_k)
        else
-          message = "Unknown interpolation type: " // trim(int_to_str(INTT))
+          message = "Unknown interpolation type: " // trim(to_str(INTT))
           call fatal_error()
        end if
 
@@ -1826,7 +1826,7 @@ contains
                   p_l_k)/frac
           end if
        else
-          message = "Unknown interpolation type: " // trim(int_to_str(INTT))
+          message = "Unknown interpolation type: " // trim(to_str(INTT))
           call fatal_error()
        end if
 
@@ -1879,7 +1879,7 @@ contains
              mu_out = mu_k + (sqrt(p_k*p_k + 2*frac*(r3 - c_k))-p_k)/frac
           end if
        else
-          message = "Unknown interpolation type: " // trim(int_to_str(JJ))
+          message = "Unknown interpolation type: " // trim(to_str(JJ))
           call fatal_error()
        end if
 
diff --git a/src/source.F90 b/src/source.F90
index f296c2c5b6..1ecea63eda 100644
--- a/src/source.F90
+++ b/src/source.F90
@@ -9,7 +9,7 @@ module source
   use particle_header, only: Particle, initialize_particle
   use physics,         only: watt_spectrum
   use random_lcg,      only: prn, set_particle_seed
-  use string,          only: int_to_str
+  use string,          only: to_str
 
   implicit none
 
@@ -51,7 +51,7 @@ contains
        bytes = maxwork * 64 / 8
 #endif
        message = "Could not allocate source bank. Attempted to allocate " &
-            // trim(int_to_str(bytes)) // " bytes."
+            // trim(to_str(bytes)) // " bytes."
        call fatal_error()
     end if
 
@@ -64,7 +64,7 @@ contains
        bytes = 3 * maxwork * 64 / 8
 #endif
        message = "Could not allocate fission bank. Attempted to allocate " &
-            // trim(int_to_str(bytes)) // " bytes."
+            // trim(to_str(bytes)) // " bytes."
        call fatal_error()
     end if
 
@@ -74,7 +74,7 @@ contains
        p_max = external_source%values(4:6)
     else
        message = "Unsupported external source type: " // &
-            int_to_str(external_source%type)
+            to_str(external_source%type)
        call fatal_error()
     end if
 
diff --git a/src/string.F90 b/src/string.F90
index ae8991b849..2800d84c12 100644
--- a/src/string.F90
+++ b/src/string.F90
@@ -6,8 +6,8 @@ module string
 
   implicit none
 
-  interface int_to_str
-     module procedure int4_to_str, int8_to_str
+  interface to_str
+     module procedure int4_to_str, int8_to_str, real_to_str
   end interface
 
 contains
diff --git a/src/tally.F90 b/src/tally.F90
index 23d0e9bc9e..a1d66674ec 100644
--- a/src/tally.F90
+++ b/src/tally.F90
@@ -7,7 +7,7 @@ module tally
   use mesh_header,   only: StructuredMesh
   use output,        only: header
   use search,        only: binary_search
-  use string,        only: int_to_str, real_to_str
+  use string,        only: to_str
   use tally_header,  only: TallyScore, TallyMapItem, TallyMapElement
 
 #ifdef MPI
@@ -966,7 +966,7 @@ contains
        t => tallies(i)
 
        ! Write header block
-       call header("TALLY " // trim(int_to_str(t % id)), unit=UNIT_TALLY, level=3)
+       call header("TALLY " // trim(to_str(t % id)), unit=UNIT_TALLY, level=3)
 
        ! Handle surface current tallies separately
        if (t % surface_current) then
@@ -1048,8 +1048,8 @@ contains
           do k = 1, t % n_macro_bins
              write(UNIT=UNIT_TALLY, FMT='(1X,2A,1X,A,"+/- ",A)') & 
                   repeat(" ", indent), macro_name(abs(t % macro_bins(k) % scalar)), &
-                  real_to_str(t % scores(score_index,k) % val), &
-                  trim(real_to_str(t % scores(score_index,k) % val_sq))
+                  to_str(t % scores(score_index,k) % val), &
+                  trim(to_str(t % scores(score_index,k) % val_sq))
           end do
           indent = indent - 2
 
@@ -1099,14 +1099,14 @@ contains
     end if
 
     do i = 1, m % dimension(1)
-       string = "Mesh Index (" // trim(int_to_str(i)) // ", "
+       string = "Mesh Index (" // trim(to_str(i)) // ", "
        len1 = len_trim(string)
        do j = 1, m % dimension(2)
-          string = string(1:len1+1) // trim(int_to_str(j)) // ", "
+          string = string(1:len1+1) // trim(to_str(j)) // ", "
           len2 = len_trim(string)
           do k = 1, m % dimension(3)
              ! Write mesh cell index
-             string = string(1:len2+1) // trim(int_to_str(k)) // ")"
+             string = string(1:len2+1) // trim(to_str(k)) // ")"
              write(UNIT=UNIT_TALLY, FMT='(1X,A)') trim(string)
 
              do l = 1, n
@@ -1125,15 +1125,15 @@ contains
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Outgoing Current to Left", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 bins(TS_SURFACE) = OUT_RIGHT
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Incoming Current from Left", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 ! Right Surface
                 bins(1:3) = (/ i, j, k /) + 1
@@ -1141,15 +1141,15 @@ contains
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Incoming Current from Right", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 bins(TS_SURFACE) = OUT_RIGHT
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Outgoing Current to Right", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 ! Back Surface
                 bins(1:3) = (/ i, j-1, k /) + 1
@@ -1157,15 +1157,15 @@ contains
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Outgoing Current to Back", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 bins(TS_SURFACE) = OUT_FRONT
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Incoming Current from Back", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 ! Front Surface
                 bins(1:3) = (/ i, j, k /) + 1
@@ -1173,15 +1173,15 @@ contains
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Incoming Current from Front", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 bins(TS_SURFACE) = OUT_FRONT
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Outgoing Current to Front", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 ! Bottom Surface
                 bins(1:3) = (/ i, j, k-1 /) + 1
@@ -1189,15 +1189,15 @@ contains
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Outgoing Current to Bottom", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 bins(TS_SURFACE) = OUT_TOP
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Incoming Current from Bottom", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 ! Top Surface
                 bins(1:3) = (/ i, j, k /) + 1
@@ -1205,15 +1205,15 @@ contains
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Incoming Current from Top", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
 
                 bins(TS_SURFACE) = OUT_TOP
                 score_index = sum((bins - 1) * t % stride) + 1
                 write(UNIT=UNIT_TALLY, FMT='(5X,A,T35,A,"+/- ",A)') & 
                      "Outgoing Current to Top", &
-                     real_to_str(t % scores(score_index,1) % val), &
-                     trim(real_to_str(t % scores(score_index,1) % val_sq))
+                     to_str(t % scores(score_index,1) % val), &
+                     trim(to_str(t % scores(score_index,1) % val_sq))
              end do
 
           end do
@@ -1243,38 +1243,38 @@ contains
     select case(filter_type)
     case (T_UNIVERSE)
        i = t % universe_bins(bin) % scalar
-       label = int_to_str(universes(i) % id)
+       label = to_str(universes(i) % id)
     case (T_MATERIAL)
        i = t % material_bins(bin) % scalar
-       label = int_to_str(materials(i) % id)
+       label = to_str(materials(i) % id)
     case (T_CELL)
        i = t % cell_bins(bin) % scalar
-       label = int_to_str(cells(i) % id)
+       label = to_str(cells(i) % id)
     case (T_CELLBORN)
        i = t % cellborn_bins(bin) % scalar
-       label = int_to_str(cells(i) % id)
+       label = to_str(cells(i) % id)
     case (T_SURFACE)
        i = t % surface_bins(bin) % scalar
-       label = int_to_str(surfaces(i) % id)
+       label = to_str(surfaces(i) % id)
     case (T_MESH)
        m => meshes(t % mesh)
        allocate(ijk(m % n_dimension))
        call bin_to_mesh_indices(m, bin, ijk)
        if (m % n_dimension == 2) then
-          label = "Index (" // trim(int_to_str(ijk(1))) // ", " // &
-               trim(int_to_str(ijk(2))) // ")"
+          label = "Index (" // trim(to_str(ijk(1))) // ", " // &
+               trim(to_str(ijk(2))) // ")"
        elseif (m % n_dimension == 3) then
-          label = "Index (" // trim(int_to_str(ijk(1))) // ", " // &
-               trim(int_to_str(ijk(2))) // ", " // trim(int_to_str(ijk(3))) // ")"
+          label = "Index (" // trim(to_str(ijk(1))) // ", " // &
+               trim(to_str(ijk(2))) // ", " // trim(to_str(ijk(3))) // ")"
        end if
     case (T_ENERGYIN)
        E0 = t % energy_in(bin)
        E1 = t % energy_in(bin + 1)
-       label = "[" // trim(real_to_str(E0)) // ", " // trim(real_to_str(E1)) // ")"
+       label = "[" // trim(to_str(E0)) // ", " // trim(to_str(E1)) // ")"
     case (T_ENERGYOUT)
        E0 = t % energy_out(bin)
        E1 = t % energy_out(bin + 1)
-       label = "[" // trim(real_to_str(E0)) // ", " // trim(real_to_str(E1)) // ")"
+       label = "[" // trim(to_str(E0)) // ", " // trim(to_str(E1)) // ")"
     end select
 
   end function get_label