From e0e5936b7918fff27f660b4234996b653eaa4880 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Thu, 15 Apr 2021 16:29:14 -0500
Subject: [PATCH] Remove separate RNG stream for photons

---
 include/openmc/random_lcg.h | 10 ++++------
 src/particle.cpp            |  6 +-----
 src/physics.cpp             |  2 --
 3 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/include/openmc/random_lcg.h b/include/openmc/random_lcg.h
index f5d5aa15b..d73cc3ee2 100644
--- a/include/openmc/random_lcg.h
+++ b/include/openmc/random_lcg.h
@@ -10,13 +10,11 @@ namespace openmc {
 // Module constants.
 //==============================================================================
 
-constexpr int N_STREAMS         {6};
+constexpr int N_STREAMS         {4};
 constexpr int STREAM_TRACKING   {0};
-constexpr int STREAM_TALLIES    {1};
-constexpr int STREAM_SOURCE     {2};
-constexpr int STREAM_URR_PTABLE {3};
-constexpr int STREAM_VOLUME     {4};
-constexpr int STREAM_PHOTON     {5};
+constexpr int STREAM_SOURCE     {1};
+constexpr int STREAM_URR_PTABLE {2};
+constexpr int STREAM_VOLUME     {3};
 constexpr int64_t DEFAULT_SEED  {1};
 
 //==============================================================================
diff --git a/src/particle.cpp b/src/particle.cpp
index 2e2413174..037566290 100644
--- a/src/particle.cpp
+++ b/src/particle.cpp
@@ -135,11 +135,7 @@ void
 Particle::event_calculate_xs()
 {
   // Set the random number stream
-  if (type_ == Particle::Type::neutron) {
-    stream_ = STREAM_TRACKING;
-  } else {
-    stream_ = STREAM_PHOTON;
-  }
+  stream_ = STREAM_TRACKING;
 
   // Store pre-collision particle properties
   wgt_last_ = wgt_;
diff --git a/src/physics.cpp b/src/physics.cpp
index 8e4b027ba..4b359c92e 100644
--- a/src/physics.cpp
+++ b/src/physics.cpp
@@ -117,9 +117,7 @@ void sample_neutron_reaction(Particle& p)
 
   // Create secondary photons
   if (settings::photon_transport) {
-    p.stream_ = STREAM_PHOTON;
     sample_secondary_photons(p, i_nuclide);
-	  p.stream_ = STREAM_TRACKING;
   }
 
   // If survival biasing is being used, the following subroutine adjusts the