<?xml version='1.0' encoding='utf-8'?>
<model>
  <materials>
    <material id="1">
      <density units="g/cm3" value="1.0"/>
      <nuclide ao="1.0" name="W184"/>
    </material>
    <material id="2">
      <density units="g/cm3" value="5.0"/>
      <nuclide ao="1.0" name="Fe56"/>
    </material>
  </materials>
  <geometry>
    <cell id="1" material="void" region="-1" universe="1"/>
    <cell id="2" material="1" region="1 -2" universe="1"/>
    <cell id="3" material="2" region="2 -3" universe="1"/>
    <surface coeffs="0.0 0.0 0.0 1000.0 30.0 30.0" id="1" type="z-torus"/>
    <surface coeffs="0.0 0.0 0.0 1000.0 35.0 35.0" id="2" type="z-torus"/>
    <surface boundary="vacuum" coeffs="0.0 0.0 0.0 1000.0 40.0 40.0" id="3" type="z-torus"/>
  </geometry>
  <settings>
    <run_mode>fixed source</run_mode>
    <particles>1000</particles>
    <batches>10</batches>
    <source particle="neutron" strength="1.0" type="independent">
      <space type="point">
        <parameters>-1000.0 0 0</parameters>
      </space>
    </source>
  </settings>
  <tallies>
    <tally id="1">
      <scores>flux</scores>
    </tally>
  </tallies>
</model>
