<?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"/>
    </material>
    <material id="2">
      <density units="g/cc" value="1.0"/>
      <nuclide ao="1.0" name="H1"/>
    </material>
  </materials>
  <geometry>
    <cell id="1" material="1" region="-1" universe="2"/>
    <cell id="2" material="2" region="1" universe="1"/>
    <cell fill="1" id="3" universe="2"/>
    <cell id="4" material="1" region="-2" universe="3"/>
    <cell id="5" material="2" region="2" universe="3"/>
    <cell fill="4" id="6" region="3 -4 5 -6" universe="5"/>
    <lattice id="4">
      <pitch>2 2</pitch>
      <dimension>4 4</dimension>
      <lower_left>-4 -4</lower_left>
      <universes>
2 3 3 3 
3 2 3 3 
3 3 2 3 
3 3 3 2 </universes>
    </lattice>
    <surface coeffs="0.0 0.0 0.7" id="1" type="z-cylinder"/>
    <surface coeffs="0.0 0.0 0.5" id="2" type="z-cylinder"/>
    <surface boundary="reflective" coeffs="-4.0" id="3" name="minimum x" type="x-plane"/>
    <surface boundary="reflective" coeffs="4.0" id="4" name="maximum x" type="x-plane"/>
    <surface boundary="reflective" coeffs="-4.0" id="5" name="minimum y" type="y-plane"/>
    <surface boundary="reflective" coeffs="4.0" id="6" name="maximum y" type="y-plane"/>
  </geometry>
  <settings>
    <run_mode>eigenvalue</run_mode>
    <particles>1000</particles>
    <batches>5</batches>
    <inactive>0</inactive>
    <source particle="neutron" strength="1.0" type="independent">
      <space type="point">
        <parameters>0.0 0.0 0.0</parameters>
      </space>
    </source>
  </settings>
  <tallies>
    <filter id="1" type="cellinstance">
      <bins>4 0 4 1 4 2 4 3 4 4 4 5 4 6 4 7 4 8 4 9 4 10 4 11 2 0 2 1 2 2 2 3 3 0 3 1 3 2 3 3</bins>
    </filter>
    <filter id="2" type="cellinstance">
      <bins>3 3 3 2 3 1 3 0 2 3 2 2 2 1 2 0 4 11 4 10 4 9 4 8 4 7 4 6 4 5 4 4 4 3 4 2 4 1 4 0</bins>
    </filter>
    <tally id="1">
      <filters>1</filters>
      <scores>total</scores>
    </tally>
    <tally id="2">
      <filters>2</filters>
      <scores>total</scores>
    </tally>
  </tallies>
</model>
