From 1b5033dab4e92d2b99bdcc1960c0bc954dae56cc Mon Sep 17 00:00:00 2001
From: GuySten <62616591+GuySten@users.noreply.github.com>
Date: Fri, 12 Dec 2025 08:21:46 +0200
Subject: [PATCH] IFP creates fatal error in all run modes except eigenvalue.
 (#3681)

---
 src/tallies/tally.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/tallies/tally.cpp b/src/tallies/tally.cpp
index 9daeb1d69..6eef1da9c 100644
--- a/src/tallies/tally.cpp
+++ b/src/tallies/tally.cpp
@@ -215,7 +215,7 @@ Tally::Tally(pugi::xml_node node)
                       "number of inactive cycles.");
         }
         settings::ifp_on = true;
-      } else {
+      } else if (settings::run_mode == RunMode::FIXED_SOURCE) {
         fatal_error(
           "Iterated Fission Probability can only be used in an eigenvalue "
           "calculation.");