diff --git a/src/DEPENDENCIES b/src/DEPENDENCIES
index d6a8591c6c..7d70c783ef 100644
--- a/src/DEPENDENCIES
+++ b/src/DEPENDENCIES
@@ -179,6 +179,7 @@ physics.o: geometry_header.o
 physics.o: global.o
 physics.o: interpolation.o
 physics.o: material_header.o
+physics.o: mesh.o
 physics.o: output.o
 physics.o: particle_header.o
 physics.o: random_lcg.o
diff --git a/src/global.F90 b/src/global.F90
index dae61fa6ad..5da8782b5c 100644
--- a/src/global.F90
+++ b/src/global.F90
@@ -156,6 +156,11 @@ module global
   real(8), allocatable :: entropy_p(:,:,:,:) ! % of source sites in each cell
   type(StructuredMesh), pointer :: entropy_mesh
 
+  ! Uniform fission source weighting
+  logical :: ufs = .false.
+  type(StructuredMesh), pointer :: ufs_mesh => null()
+  real(8), allocatable :: source_frac(:,:,:,:)
+
   ! Write source at end of simulation
   logical :: write_source = .false.
 
diff --git a/src/input_xml.F90 b/src/input_xml.F90
index 039f8cb653..1b7f423c44 100644
--- a/src/input_xml.F90
+++ b/src/input_xml.F90
@@ -236,6 +236,60 @@ contains
        entropy_on = .true.
     end if
 
+    ! Uniform fission source weighting mesh
+    if (size(uniform_fs_) > 0) then
+       ! Check to make sure enough values were supplied
+       if (size(uniform_fs_(1) % lower_left) /= 3) then
+          message = "Need to specify (x,y,z) coordinates of lower-left corner &
+               &of UFS mesh."
+       elseif (size(uniform_fs_(1) % upper_right) /= 3) then
+          message = "Need to specify (x,y,z) coordinates of upper-right corner &
+               &of UFS mesh."
+       elseif (size(uniform_fs_(1) % dimension) /= 3) then
+          message = "Dimension of UFS mesh must be given as three &
+               &integers."
+          call fatal_error()
+       end if
+
+       ! Allocate mesh object and coordinates on mesh
+       allocate(ufs_mesh)
+       allocate(ufs_mesh % lower_left(3))
+       allocate(ufs_mesh % upper_right(3))
+       allocate(ufs_mesh % width(3))
+
+       ! Allocate dimensions
+       ufs_mesh % n_dimension = 3
+       allocate(ufs_mesh % dimension(3))
+
+       ! Copy dimensions
+       ufs_mesh % dimension = uniform_fs_(1) % dimension
+
+       ! Copy values
+       ufs_mesh % lower_left  = uniform_fs_(1) % lower_left
+       ufs_mesh % upper_right = uniform_fs_(1) % upper_right
+
+       ! Check on values provided
+       if (.not. all(ufs_mesh % upper_right > ufs_mesh % lower_left)) then
+          message = "Upper-right coordinate must be greater than lower-left &
+               &coordinate for UFS mesh."
+          call fatal_error()
+       end if
+
+       ! Calculate width
+       ufs_mesh % width = (ufs_mesh % upper_right - &
+            ufs_mesh % lower_left) / ufs_mesh % dimension
+
+       ! Calculate volume fraction of each cell
+       ufs_mesh % volume_frac = ONE/real(product(ufs_mesh % dimension),8)
+
+       ! Turn on uniform fission source weighting
+       ufs = .true.
+
+       ! Allocate source_frac
+       allocate(source_frac(1, ufs_mesh % dimension(1), &
+            ufs_mesh % dimension(2), ufs_mesh % dimension(3)))
+    end if
+
     ! Check if the user has specified to write binary source file
     if (trim(write_source_) == 'on') write_source = .true.
 
@@ -812,6 +866,9 @@ contains
        ! Set upper right coordinate
        m % upper_right = m % lower_left + m % dimension * m % width
 
+       ! Set volume fraction
+       m % volume_frac = ONE/real(product(m % dimension),8)
+
        ! Add mesh to dictionary
        call dict_add_key(mesh_dict, m % id, i)
     end do
diff --git a/src/intercycle.F90 b/src/intercycle.F90
index be5fa749af..d44e00c7f3 100644
--- a/src/intercycle.F90
+++ b/src/intercycle.F90
@@ -446,4 +446,55 @@ contains
 
   end subroutine calculate_keff
 
+!===============================================================================
+! COUNT_SOURCE_FOR_UFS determines the source fraction in each UFS mesh cell and
+! reweights the source bank so that the sum of the weights is equal to
+! n_particles. The 'source_frac' variable is used later to bias the production
+! of fission sites
+!===============================================================================
+
+  subroutine count_source_for_ufs()
+
+    real(8) :: total         ! total weight in source bank
+    logical :: sites_outside ! were there sites outside the ufs mesh?
+#ifdef MPI
+    integer :: n             ! total number of ufs mesh cells
+#endif
+
+    if (current_batch == 1 .and. current_gen == 1) then
+       ! On the first cycle, just assume that the source is already evenly
+       ! distributed so that effectively the production of fission sites is not
+       ! biased
+
+       source_frac = ufs_mesh % volume_frac
+
+    else
+       ! count number of source sites in each ufs mesh cell
+       call count_bank_sites(ufs_mesh, source_bank, source_frac, total, &
+            sites_outside=sites_outside)
+
+       ! Check for sites outside of the mesh
+       if (master .and. sites_outside) then
+          message = "Source sites outside of the UFS mesh!"
+          call fatal_error()
+       end if
+
+       ! Normalize to total weight to get fraction of source in each cell
+       if (master) source_frac = source_frac / total
+
+#ifdef MPI
+       ! Send source fraction to all processors
+       n = product(ufs_mesh % dimension)
+       call MPI_BCAST(source_frac, n, MPI_REAL8, 0, MPI_COMM_WORLD, mpi_err)
+       call MPI_BCAST(total, 1, MPI_REAL8, 0, MPI_COMM_WORLD, mpi_err)
+#endif
+
+       ! Since the total starting weight is not equal to n_particles, we need to
+       ! renormalize the weight of the source sites
+
+       source_bank % wgt = source_bank % wgt * n_particles / total
+    end if
+
+  end subroutine count_source_for_ufs
+
 end module intercycle
diff --git a/src/main.F90 b/src/main.F90
index bf5b922bc4..9cd90d6d0e 100644
--- a/src/main.F90
+++ b/src/main.F90
@@ -2,16 +2,17 @@ program main
 
   use constants
   use global
-  use finalize,        only: finalize_run
-  use initialize,      only: initialize_run
-  use intercycle,      only: shannon_entropy, calculate_keff, synchronize_bank
-  use output,          only: write_message, header
-  use plotter,         only: run_plot
-  use physics,         only: transport
-  use source,          only: get_source_particle
-  use string,          only: to_str
-  use tally,           only: synchronize_tallies, add_to_score
-  use timing,          only: timer_start, timer_stop
+  use finalize,   only: finalize_run
+  use initialize, only: initialize_run
+  use intercycle, only: shannon_entropy, calculate_keff, synchronize_bank, &
+                        count_source_for_ufs
+  use output,     only: write_message, header
+  use plotter,    only: run_plot
+  use physics,    only: transport
+  use source,     only: get_source_particle
+  use string,     only: to_str
+  use tally,      only: synchronize_tallies
+  use timing,     only: timer_start, timer_stop
 
 #ifdef MPI
   use mpi
@@ -78,6 +79,9 @@ contains
           ! Set all tallies to zero
           n_bank = 0
 
+          ! Count source sites if using uniform fission source weighting
+          if (ufs) call count_source_for_ufs()
+
           ! ====================================================================
           ! LOOP OVER HISTORIES
 
@@ -106,11 +110,6 @@ contains
           ! Distribute fission bank across processors evenly
           call synchronize_bank()
 
-          ! Add to analog estimate of keff -- since the creation of bank sites
-          ! was originally weighted by the last cycle keff, we need to multiply
-          ! by that keff to get the current cycle's value
-          call add_to_score(global_tallies(K_ANALOG), n_bank * keff)
-
           ! Stop timer for inter-cycle synchronization
           call timer_stop(time_intercycle)
           
diff --git a/src/mesh_header.F90 b/src/mesh_header.F90
index 8088972ce0..a26178b6f3 100644
--- a/src/mesh_header.F90
+++ b/src/mesh_header.F90
@@ -3,7 +3,7 @@ module mesh_header
   implicit none
 
 !===============================================================================
-! STRUCTUREDMESH represents a tesslation of n-dimensional Euclidean space by
+! STRUCTUREDMESH represents a tessellation of n-dimensional Euclidean space by
 ! congruent squares or cubes
 !===============================================================================
 
@@ -11,6 +11,7 @@ module mesh_header
      integer :: id                          ! user-specified id
      integer :: type                        ! rectangular, hexagonal
      integer :: n_dimension                 ! rank of mesh
+     real(8) :: volume_frac                 ! volume fraction of each cell
      integer, allocatable :: dimension(:)   ! number of cells in each direction
      real(8), allocatable :: lower_left(:)  ! lower-left corner of mesh
      real(8), allocatable :: upper_right(:) ! upper-right corner of mesh
diff --git a/src/physics.F90 b/src/physics.F90
index 00c2508ce4..382cce60b3 100644
--- a/src/physics.F90
+++ b/src/physics.F90
@@ -12,6 +12,7 @@ module physics
   use global
   use interpolation,   only: interpolate_tab1
   use material_header, only: Material
+  use mesh,            only: get_mesh_indices
   use output,          only: write_message
   use particle_header, only: LocalCoord
   use random_lcg,      only: prn
@@ -839,6 +840,7 @@ contains
     integer :: nu           ! actual number of neutrons produced
     integer :: law          ! energy distribution law
     integer :: n_sample     ! number of times resampling
+    integer :: ijk(3)       ! indices in ufs mesh
     real(8) :: E            ! incoming energy of neutron
     real(8) :: E_out        ! outgoing energy of fission neutron
     real(8) :: nu_t         ! total nu
@@ -850,7 +852,9 @@ contains
     real(8) :: xi           ! random number
     real(8) :: yield        ! delayed neutron precursor yield
     real(8) :: prob         ! cumulative probability
+    real(8) :: weight       ! weight adjustment for ufs method
     logical :: actual_event ! did fission actually occur? (no survival biasing)
+    logical :: in_mesh      ! source site in ufs mesh?
     type(Nuclide),    pointer :: nuc
     type(DistEnergy), pointer :: edist => null()
 
@@ -886,12 +890,32 @@ contains
 
     ! TODO: Heat generation from fission
 
+    ! If uniform fission source weighting is turned on, we increase of decrease
+    ! the expected number of fission sites produced
+
+    if (ufs) then
+       ! Determine indices on ufs mesh for current location
+       call get_mesh_indices(ufs_mesh, p % coord0 % xyz, ijk, in_mesh)
+       if (.not. in_mesh) then
+          message = "Source site outside UFS mesh!"
+          call fatal_error()
+       end if
+
+       if (source_frac(1,ijk(1),ijk(2),ijk(3)) /= ZERO) then
+          weight = ufs_mesh % volume_frac / source_frac(1,ijk(1),ijk(2),ijk(3))
+       else
+          weight = ONE
+       end if
+    else
+       weight = ONE
+    end if
+
     ! Sample number of neutrons produced
     if (actual_event) then
-       nu_t = p % wgt / keff * nu_t
+       nu_t = p % wgt / keff * nu_t * weight
     else
        nu_t = p % last_wgt * micro_xs(index_nuclide) % fission / (keff * &
-            micro_xs(index_nuclide) % total) * nu_t
+            micro_xs(index_nuclide) % total) * nu_t * weight
     end if
     if (prn() > nu_t - int(nu_t)) then
        nu = int(nu_t)
@@ -899,6 +923,9 @@ contains
        nu = int(nu_t) + 1
     end if
 
+    ! Add to analog estimate of keff
+    call add_to_score(global_tallies(K_ANALOG), nu/weight * keff)
+
     ! Bank source neutrons
     if (nu == 0 .or. n_bank == 3*work) return
     do i = int(n_bank,4) + 1, int(min(n_bank + nu, 3*work),4)
@@ -907,7 +934,11 @@ contains
        fission_bank(i) % xyz = p % coord0 % xyz
 
        ! Set weight of fission bank site
-       fission_bank(i) % wgt = ONE
+       if (ufs) then
+          fission_bank(i) % wgt = ONE/weight
+       else
+          fission_bank(i) % wgt = ONE
+       end if
 
        ! sample cosine of angle
        mu = sample_angle(rxn, E)
diff --git a/src/xml-fortran/templates/settings_t.xml b/src/xml-fortran/templates/settings_t.xml
index f2b387316d..321565955f 100644
--- a/src/xml-fortran/templates/settings_t.xml
+++ b/src/xml-fortran/templates/settings_t.xml
@@ -20,7 +20,7 @@
     <component name="weight_avg" type="double" default="1.0" />
   </typedef>
 
-  <typedef name="entropy_xml">
+  <typedef name="mesh_xml">
     <component name="dimension" type="integer-array" />
     <component name="lower_left" type="double-array" />
     <component name="upper_right" type="double-array" />
@@ -30,13 +30,14 @@
   <variable name="cross_sections_" tag="cross_sections" type="word" length="255" />
   <variable name="cutoff_" tag="cutoff" type="cutoff_xml" dimension="1" />
   <variable name="energy_grid_" tag="energy_grid" type="word" length="7" />
-  <variable name="entropy_" tag="entropy" type="entropy_xml" dimension="1" />
+  <variable name="entropy_" tag="entropy" type="mesh_xml" dimension="1" />
   <variable name="ptables_" tag="ptables" type="word" length="3" />
   <variable name="seed_" tag="seed" type="integer" />
   <variable name="source_" tag="source" type="source_xml" />
   <variable name="survival_" tag="survival_biasing" type="word" length="3" />
   <variable name="verbosity_" tag="verbosity" type="integer" />
   <variable name="trace_" tag="trace" type="integer-array" />
+  <variable name="uniform_fs_" tag="uniform_fs" type="mesh_xml" dimension="1" />
   <variable name="write_source_" tag="write_source" type="word" length="3" />
 
 </template>