<?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 depletable="true" id="2">
      <density units="g/cc" value="4.5" />
      <nuclide ao="1.0" name="U238" />
    </material>
  </materials>
  <geometry>
    <cell id="11" material="1" universe="11" />
    <cell id="12" material="2" universe="12" />
    <cell fill="21" id="101" region="-101" universe="0" />
    <lattice id="21">
      <pitch>2.0 2.0</pitch>
      <outer>12</outer>
      <dimension>2 2</dimension>
      <lower_left>-2.0 -2.0</lower_left>
      <universes>
11 12 
12 11 </universes>
    </lattice>
    <surface boundary="vacuum" coeffs="0.0 0.0 5.0" id="101" type="z-cylinder" />
  </geometry>
  <settings>
    <run_mode>eigenvalue</run_mode>
    <particles>1000</particles>
    <batches>10</batches>
    <inactive>5</inactive>
    <source strength="1.0">
      <space type="box">
        <parameters>-4.0 -4.0 -4.0 4.0 4.0 4.0</parameters>
      </space>
    </source>
  </settings>
  </model>
