diff --git a/src/ace_header.F90 b/src/ace_header.F90
index 0b838fb8c9..3caa5eb563 100644
--- a/src/ace_header.F90
+++ b/src/ace_header.F90
@@ -197,7 +197,6 @@ module ace_header
 
      ! Information for URR probability table use
      logical :: use_ptable  ! in URR range with probability tables?
-     logical :: recalculate ! indicate whether we need to recalculate ptables
   end type NuclideMicroXS
 
 !===============================================================================
diff --git a/src/cross_section.F90 b/src/cross_section.F90
index fbec5221ee..18706fe1e8 100644
--- a/src/cross_section.F90
+++ b/src/cross_section.F90
@@ -168,11 +168,9 @@ contains
     ! probability tables, we need to determine cross sections from the table
 
     if (urr_ptables_on .and. nuc % urr_present) then
-       if (micro_xs(index_nuclide) % recalculate) then
-          if (p % E > nuc % urr_data % energy(1) .and. &
-               p % E < nuc % urr_data % energy(nuc % urr_data % n_energy)) then
-             call calculate_urr_xs(p, index_nuclide)
-          end if
+       if (p % E > nuc % urr_data % energy(1) .and. &
+            p % E < nuc % urr_data % energy(nuc % urr_data % n_energy)) then
+          call calculate_urr_xs(p, index_nuclide)
        end if
     end if
 
@@ -365,10 +363,6 @@ contains
             micro_xs(index_nuclide) % fission
     end if
 
-    ! As long as the energy of the neutron doesn't change, we don't need to
-    ! recalculate probability table data
-    micro_xs(index_nuclide) % recalculate = .false.
-
   end subroutine calculate_urr_xs
 
 !===============================================================================
diff --git a/src/physics.F90 b/src/physics.F90
index 27312d72bb..767dcc2aa5 100644
--- a/src/physics.F90
+++ b/src/physics.F90
@@ -66,9 +66,6 @@ contains
     ! Initialize number of events to zero
     n_event = 0
 
-    ! Set recalculate ptables to true by default
-    micro_xs(:) % recalculate = .true.
-
     ! find energy index, interpolation factor
     do while (p % alive)
 
@@ -200,10 +197,6 @@ contains
     ! Reset number of particles banked during collision
     p % n_bank = 0
 
-    ! Since a collision has occurred, we need to recalculate probability tables
-    ! for any nuclide
-    micro_xs(:) % recalculate = .true.
-
   end subroutine collision
 
 !===============================================================================
diff --git a/src/utils/core_map.py b/src/utils/core_map.py
new file mode 100755
index 0000000000..4b5e7f7b8a
--- /dev/null
+++ b/src/utils/core_map.py
@@ -0,0 +1,36 @@
+#!/usr/bin/env python
+
+import sys
+
+import numpy as np
+import matplotlib.pyplot as pyplot
+
+# Get filename and file object
+filename = sys.argv[1]
+axial_level = int(sys.argv[2])
+fh = open(filename,'r')
+
+# Read size of mesh
+words = fh.readline().split()
+nx, ny, nz = [int(item) for item in words]
+
+# Read values
+value_dict = {}
+for line in fh:
+    words = line.split()
+    i, j, k = [int(item) for item in words[:3]]
+    value = float(words[3])
+    value_dict[i,j,k] = value
+
+# Set up matrix
+matrix = np.array([[value_dict[i+1,j+1,axial_level] for i in range(nx)]
+                   for j in range(ny)])
+
+# Make figure
+pyplot.pcolor(matrix)
+pyplot.colorbar()
+pyplot.xlim([0,nx])
+pyplot.ylim([0,ny])
+pyplot.xticks([])
+pyplot.yticks([])
+pyplot.show()