diff --git a/openmc/data/photon.py b/openmc/data/photon.py
index 32ed3010a..9cc697b78 100644
--- a/openmc/data/photon.py
+++ b/openmc/data/photon.py
@@ -784,8 +784,9 @@ class IncidentPhoton(EqualityMixin):
                 sub_group = shell_group.create_group(key)
 
                 # Write atomic relaxation
-                if key in self.atomic_relaxation.subshells:
-                    self.atomic_relaxation.to_hdf5(sub_group, key)
+                if self.atomic_relaxation is not None:
+                    if key in self.atomic_relaxation.subshells:
+                        self.atomic_relaxation.to_hdf5(sub_group, key)
             else:
                 continue
 
diff --git a/tests/unit_tests/test_data_photon.py b/tests/unit_tests/test_data_photon.py
index c767d19e6..f7274e9c1 100644
--- a/tests/unit_tests/test_data_photon.py
+++ b/tests/unit_tests/test_data_photon.py
@@ -2,6 +2,7 @@
 
 from collections.abc import Mapping, Callable
 import os
+from pathlib import Path
 
 import numpy as np
 import pandas as pd
@@ -144,3 +145,9 @@ def test_export_to_hdf5(tmpdir, element):
            element2.bremsstrahlung['electron_energy']).all()
     # Export to hdf5 again
     element2.export_to_hdf5(filename, 'w')
+
+def test_photodat_only(run_in_tmpdir):
+    endf_dir = Path(os.environ['OPENMC_ENDF_DATA'])
+    photoatomic_file = endf_dir / 'photoat' / 'photoat-001_H_000.endf'
+    data = openmc.data.IncidentPhoton.from_endf(photoatomic_file)
+    data.export_to_hdf5('tmp.h5', 'w')
\ No newline at end of file