Fix mixed-unit error in fission Q values
Fix mixed-unit error in fission Q values

liangjg/openmc,walshjon/openmc,amandalund/openmc,bhermanmit/openmc,amandalund/openmc,johnnyliu27/openmc,wbinventor/openmc,paulromano/openmc,walshjon/openmc,smharper/openmc,smharper/openmc,shikhar413/openmc,samuelshaner/openmc,smharper/openmc,shikhar413/openmc,amandalund/openmc,walshjon/openmc,paulromano/openmc,paulromano/openmc,wbinventor/openmc,mit-crpg/openmc,johnnyliu27/openmc,mit-crpg/openmc,walshjon/openmc,liangjg/openmc,wbinventor/openmc,mit-crpg/openmc,johnnyliu27/openmc,shikhar413/openmc,liangjg/openmc,wbinventor/openmc,smharper/openmc,liangjg/openmc,samuelshaner/openmc,samuelshaner/openmc,shikhar413/openmc,amandalund/openmc,bhermanmit/openmc,samuelshaner/openmc,mit-crpg/openmc,paulromano/openmc,johnnyliu27/openmc