diff --git a/src/ace.F90 b/src/ace.F90
index fb42180da0..6d4f3c740c 100644
--- a/src/ace.F90
+++ b/src/ace.F90
@@ -7,7 +7,7 @@ module ace
   use error,            only: fatal_error, warning
   use fission,          only: nu_total
   use global
-  use list_header,      only: ListElemInt, ListInt
+  use list_header,      only: ListInt
   use material_header,  only: Material
   use output,           only: write_message
   use set_header,       only: SetChar
@@ -1563,16 +1563,11 @@ contains
 
     integer :: i ! index in nuclides array
     integer :: j ! index in nuclides array
-    type(ListElemInt), pointer :: nuc_list => null() ! pointer to nuclide list
 
     do i = 1, n_nuclides_total
-      allocate(nuclides(i) % nuc_list)
-      nuc_list => nuclides(i) % nuc_list
       do j = 1, n_nuclides_total
         if (nuclides(i) % zaid == nuclides(j) % zaid) then
-          nuc_list % data = j
-          allocate(nuc_list % next)
-          nuc_list => nuc_list % next
+          call nuclides(i) % nuc_list % append(j)
         end if
       end do
     end do
diff --git a/src/ace_header.F90 b/src/ace_header.F90
index 6d339891c9..76492dfe80 100644
--- a/src/ace_header.F90
+++ b/src/ace_header.F90
@@ -2,7 +2,7 @@ module ace_header
 
   use constants,   only: MAX_FILE_LEN
   use endf_header, only: Tab1
-  use list_header, only: ListElemInt
+  use list_header, only: ListInt
 
   implicit none
 
@@ -97,7 +97,7 @@ module ace_header
     real(8)       :: kT      ! temperature in MeV (k*T)
 
     ! Linked list of indices in nuclides array of instances of this same nuclide
-    type(ListElemInt), pointer :: nuc_list => null()
+    type(ListInt) :: nuc_list
 
     ! Energy grid information
     integer :: n_grid                     ! # of nuclide grid points
@@ -114,7 +114,7 @@ module ace_header
 
     ! Resonance scattering info
     logical              :: resonant = .false. ! resonant scatterer?
-    character(10)        :: name_0K ! name of 0K nuclide, e.g. 92235.00c
+    character(10)        :: name_0K = '' ! name of 0K nuclide, e.g. 92235.00c
     character(16)        :: scheme ! target velocity sampling scheme
     integer              :: n_grid_0K ! number of 0K energy grid points
     real(8), allocatable :: energy_0K(:)  ! energy grid for 0K xs
@@ -416,6 +416,8 @@ module ace_header
         deallocate(this % reactions)
       end if
 
+      call this % nuc_list % clear()
+
     end subroutine nuclide_clear
 
 end module ace_header
diff --git a/src/cross_section.F90 b/src/cross_section.F90
index 0620cf11f8..fddc79dff0 100644
--- a/src/cross_section.F90
+++ b/src/cross_section.F90
@@ -342,21 +342,22 @@ contains
     integer, intent(in) :: i_nuclide ! index into nuclides array
     real(8), intent(in) :: E         ! energy
 
-    integer :: i_energy   ! index for energy
-    integer :: i_low      ! band index at lower bounding energy
-    integer :: i_up       ! band index at upper bounding energy
-    real(8) :: f          ! interpolation factor
-    real(8) :: r          ! pseudo-random number
-    real(8) :: elastic    ! elastic cross section
-    real(8) :: capture    ! (n,gamma) cross section
-    real(8) :: fission    ! fission cross section
-    real(8) :: inelastic  ! inelastic cross section
-    logical :: same_nuc   ! do we know the xs for this nuclide at this energy?
+    integer :: i            ! loop index
+    integer :: i_energy     ! index for energy
+    integer :: i_low        ! band index at lower bounding energy
+    integer :: i_up         ! band index at upper bounding energy
+    integer :: same_nuc_idx ! index of same nuclide
+    real(8) :: f            ! interpolation factor
+    real(8) :: r            ! pseudo-random number
+    real(8) :: elastic      ! elastic cross section
+    real(8) :: capture      ! (n,gamma) cross section
+    real(8) :: fission      ! fission cross section
+    real(8) :: inelastic    ! inelastic cross section
+    logical :: same_nuc     ! do we know the xs for this nuclide at this energy?
     type(UrrData),  pointer, save :: urr      => null()
     type(Nuclide),  pointer, save :: nuc      => null()
     type(Reaction), pointer, save :: rxn      => null()
-    type(ListElemInt), pointer    :: nuc_list => null()
-!$omp threadprivate(urr, nuc, rxn, nuc_list)
+!$omp threadprivate(urr, nuc, rxn)
 
     micro_xs(i_nuclide) % use_ptable = .true.
 
@@ -381,18 +382,16 @@ contains
     ! this energy but a different temperature, use the original random number to
     ! preserve correlation of temperature in probability tables
     same_nuc = .false.
-    nuc_list => nuc % nuc_list
-    do
-      if (E /= ZERO .and. E == micro_xs(nuc_list % data) % last_E) then
+    do i = 1, nuc % nuc_list % size()
+      if (E /= ZERO .and. E == micro_xs(nuc % nuc_list % get_item(i)) % last_E) then
         same_nuc = .true.
+        same_nuc_idx = i
         exit
       end if
-      nuc_list => nuc_list % next
-      if (.not. associated(nuc_list % next)) exit
     end do
 
     if (same_nuc) then
-      r = micro_xs(nuc_list % data) % last_prn
+      r = micro_xs(nuc % nuc_list % get_item(same_nuc_idx)) % last_prn
     else
       r = prn()
       micro_xs(i_nuclide) % last_prn = r