From 8965dd1e66f53db42f607e165c504ba354d65c64 Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Tue, 2 Aug 2022 22:11:37 -0500
Subject: [PATCH] Check for macroscopic data in materials when running
 Universe.plot

---
 openmc/universe.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/openmc/universe.py b/openmc/universe.py
index 78f75bbfc1..7dee19313a 100644
--- a/openmc/universe.py
+++ b/openmc/universe.py
@@ -334,6 +334,13 @@ class Universe(UniverseBase):
             if seed is not None:
                 model.settings.seed = seed
 
+            # Determine whether any materials contains macroscopic data and if
+            # so, set energy mode accordingly
+            for mat in self.get_all_materials().values():
+                if mat._macroscopic is not None:
+                    model.settings.energy_mode = 'multi-group'
+                    break
+
             # Create plot object matching passed arguments
             plot = openmc.Plot()
             plot.origin = origin