<?xml version='1.0' encoding='utf-8'?>
<model>
  <materials>
    <material depletable="true" id="1">
      <density units="sum"/>
      <nuclide ao="0.0049817" name="U235"/>
    </material>
    <material id="2">
      <density units="atom/b-cm" value="0.017742"/>
      <nuclide ao="1.0" name="C0"/>
      <sab name="c_Graphite"/>
    </material>
    <material id="3" name="Lead">
      <density units="g/cm3" value="10.32"/>
      <nuclide ao="0.014" name="Pb204"/>
      <nuclide ao="0.241" name="Pb206"/>
      <nuclide ao="0.221" name="Pb207"/>
      <nuclide ao="0.524" name="Pb208"/>
    </material>
    <material id="4">
      <density units="atom/b-cm" value="0.00054464"/>
      <nuclide ao="1.0" name="He4"/>
    </material>
    <material id="5" name="Zirc4">
      <density units="sum"/>
      <nuclide ao="0.02217" name="Zr90"/>
      <nuclide ao="0.004781" name="Zr91"/>
      <nuclide ao="0.007228" name="Zr92"/>
      <nuclide ao="0.007169" name="Zr94"/>
      <nuclide ao="0.001131" name="Zr96"/>
    </material>
  </materials>
  <geometry>
    <cell id="1" material="1" region="-1 2 -3" universe="1"/>
    <cell id="2" material="2" region="1" universe="1"/>
    <cell id="3" material="4" name="coolant" region="-4 2 -3" universe="2"/>
    <cell id="4" material="5" name="zirconium_shell" region="4 -5 2 -3" universe="2"/>
    <cell id="5" material="3" name="lead_shell" region="5 -6 2 -3" universe="2"/>
    <cell id="6" material="2" name="matrix coolant surround" region="6 2 -3" universe="2"/>
    <cell id="7" material="2" universe="3"/>
    <cell fill="4" id="8" name="container cell" region="-7 8 -9 -12 10 11 2 -3" universe="5"/>
    <hex_lattice id="4" n_rings="2" name="regular fuel assembly">
      <pitch>1.4</pitch>
      <outer>3</outer>
      <center>0.0 0.0</center>
      <universes>
 2
2 2
 1
2 2
 2</universes>
    </hex_lattice>
    <surface coeffs="0.0 0.0 0.7" id="1" type="z-cylinder"/>
    <surface boundary="reflective" coeffs="0.0" id="2" type="z-plane"/>
    <surface boundary="reflective" coeffs="10.0" id="3" type="z-plane"/>
    <surface coeffs="0.0 0.0 0.293" id="4" type="z-cylinder"/>
    <surface coeffs="0.0 0.0 0.35" id="5" type="z-cylinder"/>
    <surface coeffs="0.0 0.0 0.352" id="6" type="z-cylinder"/>
    <surface boundary="reflective" coeffs="1.4" id="7" type="y-plane"/>
    <surface boundary="reflective" coeffs="-1.4" id="8" type="y-plane"/>
    <surface boundary="reflective" coeffs="1.7320508075688772 1.0 0.0 2.8" id="9" type="plane"/>
    <surface boundary="reflective" coeffs="-1.7320508075688772 1.0 0.0 -2.8" id="10" type="plane"/>
    <surface boundary="reflective" coeffs="1.7320508075688772 1.0 0.0 -2.8" id="11" type="plane"/>
    <surface boundary="reflective" coeffs="-1.7320508075688772 1.0 0.0 2.8" id="12" type="plane"/>
  </geometry>
  <settings>
    <run_mode>eigenvalue</run_mode>
    <particles>1000</particles>
    <batches>5</batches>
    <inactive>2</inactive>
    <source particle="neutron" strength="1.0" type="independent">
      <space type="box">
        <parameters>-0.9899494936611666 -0.9899494936611666 0.0 0.9899494936611666 0.9899494936611666 10.0</parameters>
      </space>
    </source>
    <output>
      <summary>false</summary>
    </output>
    <seed>22</seed>
  </settings>
  </model>
