From 37e3e6e9b5bbd141dafed057b1ceefa658aea116 Mon Sep 17 00:00:00 2001
From: Paul Romano <romano7@gmail.com>
Date: Fri, 6 Apr 2012 09:27:06 -0400
Subject: [PATCH] Fixed bug with analog fission tallies when using UFS.

---
 src/particle_header.F90 |  1 +
 src/physics.F90         | 16 ++++++++--------
 src/source.F90          |  1 +
 src/tally.F90           |  7 ++++---
 4 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/particle_header.F90 b/src/particle_header.F90
index 4330dfb882..7ce921bca1 100644
--- a/src/particle_header.F90
+++ b/src/particle_header.F90
@@ -57,6 +57,7 @@ module particle_header
 
      ! Post-collision physical data
      integer    :: n_bank        ! number of fission sites banked
+     real(8)    :: wgt_bank      ! weight of fission sites banked
 
      ! Energy grid data
      integer    :: IE            ! index on energy grid
diff --git a/src/physics.F90 b/src/physics.F90
index 382cce60b3..c38464dde9 100644
--- a/src/physics.F90
+++ b/src/physics.F90
@@ -213,8 +213,9 @@ contains
     if (tallies_on .and. n_analog_tallies > 0) &
          call score_analog_tally()
 
-    ! Reset number of particles banked during collision
-    p % n_bank = 0
+    ! Reset banked weight during collision
+    p % n_bank   = 0
+    p % wgt_bank = ZERO
 
   end subroutine collision
 
@@ -934,11 +935,7 @@ contains
        fission_bank(i) % xyz = p % coord0 % xyz
 
        ! Set weight of fission bank site
-       if (ufs) then
-          fission_bank(i) % wgt = ONE/weight
-       else
-          fission_bank(i) % wgt = ONE
-       end if
+       fission_bank(i) % wgt = ONE/weight
 
        ! sample cosine of angle
        mu = sample_angle(rxn, E)
@@ -1039,7 +1036,10 @@ contains
 
     ! increment number of bank sites
     n_bank = min(n_bank + nu, 3*work)
-    p % n_bank = nu
+
+    ! Store total weight banked for analog fission tallies
+    p % n_bank   = nu
+    p % wgt_bank = nu/weight
 
   end subroutine create_fission_sites
 
diff --git a/src/source.F90 b/src/source.F90
index d5a82fe41f..0c8caeb499 100644
--- a/src/source.F90
+++ b/src/source.F90
@@ -193,6 +193,7 @@ contains
     p % wgt           = ONE
     p % last_wgt      = ONE
     p % n_bank        = 0
+    p % wgt_bank      = ZERO
     p % n_collision   = 0
 
     ! remove any original coordinates
diff --git a/src/tally.F90 b/src/tally.F90
index 2169af5c14..f6d18eaa18 100644
--- a/src/tally.F90
+++ b/src/tally.F90
@@ -440,7 +440,7 @@ contains
                 ! bank. Since this was weighted by 1/keff, we multiply by keff
                 ! to get the proper score.
 
-                score = keff * p % n_bank
+                score = keff * p % wgt_bank
 
              end if
 
@@ -495,10 +495,11 @@ contains
     ! score by keff to get the true nu-fission rate. Otherwise, the sum
     ! of all nu-fission rates would be ~1.0.
 
-    score = keff
-
     ! loop over number of particles banked
     do k = 1, p % n_bank
+       ! determine score based on bank site weight and keff
+       score = keff * fission_bank(n_bank - p % n_bank + k) % wgt
+
        ! determine outgoing energy from fission bank
        E_out = fission_bank(n_bank - p % n_bank + k) % E