From 20ce145e366a50240fbec7e552f6fb60ed46c3d7 Mon Sep 17 00:00:00 2001
From: Adam Nelson <nelsonag@umich.edu>
Date: Mon, 21 Nov 2016 20:30:54 -0500
Subject: [PATCH] Read in total_nu as a derived product for MT=18 if it only
 exists as summed, and more correctly treated yields

---
 openmc/data/neutron.py |  3 +++
 openmc/plotter.py      | 50 +++++++++++++++++++++++-------------------
 2 files changed, 30 insertions(+), 23 deletions(-)

diff --git a/openmc/data/neutron.py b/openmc/data/neutron.py
index f478aafc7..581adc417 100644
--- a/openmc/data/neutron.py
+++ b/openmc/data/neutron.py
@@ -511,6 +511,9 @@ class IncidentNeutron(EqualityMixin):
                 rxs = [data[mt] for mt in SUM_RULES[mt_sum] if mt in data]
                 if len(rxs) > 0:
                     data.summed_reactions[mt_sum] = rx = Reaction(mt_sum)
+                    if rx.mt == 18 and 'total_nu' in group:
+                        tgroup = group['total_nu']
+                        rx.derived_products.append(Product.from_hdf5(tgroup))
                     for T in data.temperatures:
                         rx.xs[T] = Sum([rx_i.xs[T] for rx_i in rxs])
 
diff --git a/openmc/plotter.py b/openmc/plotter.py
index d6c9527bd..f576dd8a6 100644
--- a/openmc/plotter.py
+++ b/openmc/plotter.py
@@ -1,5 +1,6 @@
 from numbers import Integral, Real
 from six import string_types
+from itertools import chain
 
 import numpy as np
 
@@ -371,38 +372,41 @@ def _calculate_xs_nuclide(this, types, temperature=294., sab_name=None,
                         funcs.append(pw_funcs)
                     else:
                         funcs.append(nuc[mt].xs[nucT])
-                elif mt == 5 and mt in nuc:
-                    # Only consider the (n,misc) products if neutrons are
-                    # included in the outgoing channel since (n,misc) is only
-                    # explicitly needed for scatter cross sections.
-                    for prod in nuc[mt].products:
-                        if prod.particle == 'neutron' and \
-                            prod.emission_mode in ('total', 'prompt'):
-                            if yields[i]:
-                                func = openmc.data.Combination(
-                                        [nuc[mt].xs[nucT], prod.yield_],
-                                        [np.multiply])
-                            else:
-                                func = nuc[mt].xs[nucT]
-
-                            funcs.append(func)
-                            break
-                    else:
-                        funcs.append(lambda x: 0.)
-
                 elif mt in nuc:
                     if yields[i]:
-                        for prod in nuc[mt].products:
+                        for prod in chain(nuc[mt].products,
+                                          nuc[mt].derived_products):
                             if prod.particle == 'neutron' and \
-                                prod.emission_mode in ('total', 'prompt'):
+                                prod.emission_mode == 'total':
                                 func = openmc.data.Combination(
                                     [nuc[mt].xs[nucT], prod.yield_],
                                     [np.multiply])
                                 funcs.append(func)
                                 break
                         else:
-                            # Assume the yield is 1
-                            funcs.append(nuc[mt].xs[nucT])
+                            # Total doesn't exist so we have to create from
+                            # prompt and delayed
+                            func = None
+                            for prod in chain(nuc[mt].products,
+                                              nuc[mt].derived_products):
+                                if prod.particle == 'neutron' and \
+                                    prod.emission_mode != 'total':
+                                    if func:
+                                        func = openmc.data.Combination(
+                                            [nuc[mt].xs[nucT], prod.yield_,
+                                             func], [np.multiply, np.add])
+                                    else:
+                                        func = openmc.data.Combination(
+                                            [nuc[mt].xs[nucT], prod.yield_],
+                                            [np.multiply])
+                            if func:
+                                funcs.append(func)
+                            else:
+                                # If func is still None, then there were no
+                                # products. In that case, assume the yield is
+                                # one as its not provided for some summed
+                                # reactions like MT=4
+                                funcs.append(nuc[mt].xs[nucT])
                     else:
                         funcs.append(nuc[mt].xs[nucT])
                 elif mt == UNITY_MT: