<?xml version='1.0' encoding='utf-8'?>
<model>
  <materials>
    <material depletable="true" id="1">
      <density units="g/cc" value="4.5"/>
      <nuclide ao="1.0" name="U235"/>
      <nuclide ao="1.0" name="H1"/>
      <sab fraction="0.5" name="c_H_in_H2O"/>
    </material>
    <material depletable="true" id="2">
      <density units="g/cc" value="4.5"/>
      <nuclide ao="1.0" name="U235"/>
      <nuclide ao="1.0" name="C0"/>
      <sab name="c_Graphite"/>
    </material>
    <material depletable="true" id="3">
      <density units="g/cc" value="4.5"/>
      <nuclide ao="1.0" name="U235"/>
      <nuclide ao="1.0" name="Be9"/>
      <nuclide ao="1.0" name="O16"/>
      <sab name="c_Be_in_BeO"/>
      <sab name="c_O_in_BeO"/>
    </material>
    <material depletable="true" id="4">
      <density units="g/cm3" value="5.90168"/>
      <nuclide ao="0.3" name="H1"/>
      <nuclide ao="0.15" name="Zr90"/>
      <nuclide ao="0.1" name="Zr91"/>
      <nuclide ao="0.1" name="Zr92"/>
      <nuclide ao="0.05" name="Zr94"/>
      <nuclide ao="0.05" name="Zr96"/>
      <nuclide ao="0.1" name="U235"/>
      <nuclide ao="0.15" name="U238"/>
      <sab name="c_Zr_in_ZrH"/>
      <sab name="c_H_in_ZrH"/>
    </material>
  </materials>
  <geometry>
    <cell id="1" material="1" region="1 -2" universe="1"/>
    <cell id="2" material="2" region="2 -3" universe="1"/>
    <cell id="3" material="3" region="3 -4" universe="1"/>
    <cell id="4" material="4" region="4 -5" universe="1"/>
    <surface boundary="vacuum" coeffs="-10" id="1" type="x-plane"/>
    <surface coeffs="-5" id="2" type="x-plane"/>
    <surface coeffs="0" id="3" type="x-plane"/>
    <surface coeffs="5" id="4" type="x-plane"/>
    <surface boundary="vacuum" coeffs="10" id="5" type="x-plane"/>
  </geometry>
  <settings>
    <run_mode>eigenvalue</run_mode>
    <particles>400</particles>
    <batches>5</batches>
    <inactive>0</inactive>
    <source particle="neutron" strength="1.0" type="independent">
      <space type="box">
        <parameters>-4 -4 -4 4 4 4</parameters>
      </space>
    </source>
  </settings>
  </model>
