From 5cd42014bf5f7fe39c21c3fa3138490a43294efd Mon Sep 17 00:00:00 2001
From: John Stilley <1831479+john-science@users.noreply.github.com>
Date: Tue, 25 Oct 2022 16:21:32 -0700
Subject: [PATCH] Thanks, Chris!

---
 armi/reactor/blocks.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/armi/reactor/blocks.py b/armi/reactor/blocks.py
index 8e5dc6595..683631c2a 100644
--- a/armi/reactor/blocks.py
+++ b/armi/reactor/blocks.py
@@ -447,7 +447,7 @@ def getMicroSuffix(self):
         xsType = self.p.xsType
         if len(xsType) == 1:
             return xsType + bu
-        elif len(xsType) == 2 and ord(bu) < ord("A"):
+        elif len(xsType) == 2 and ord(bu) > ord("A"):
             raise ValueError(
                 f"Use of multiple burnup groups is not allowed with multi-character xs groups!"
             )