<?xml version="1.0"?>
<materials>

  <!-- Definition of materials -->
  <material id="1">
    <density value="19" units="g/cc" />
    <nuclide name="U235" wo="0.21" />
    <nuclide name="U238" wo="0.68" />
    <nuclide name="O16" wo="0.11" />
  </material>

</materials>
