added check if source is written to statepoint file that the statepoint will exist
added check if source is written to statepoint file that the statepoint will exist

mit-crpg/openmc,mjlong/openmc,amandalund/openmc,johnnyliu27/openmc,nhorelik/openmc,samuelshaner/openmc,samuelshaner/openmc,smharper/openmc,shenqicang/openmc,shenqicang/openmc,johnnyliu27/openmc,liangjg/openmc,paulromano/openmc,liangjg/openmc,amandalund/openmc,mit-crpg/openmc,shikhar413/openmc,wbinventor/openmc,paulromano/openmc,kellyrowland/openmc,kellyrowland/openmc,shikhar413/openmc,bhermanmit/openmc,wbinventor/openmc,nhorelik/openmc,paulromano/openmc,johnnyliu27/openmc,lilulu/openmc,shikhar413/openmc,walshjon/openmc,walshjon/openmc,samuelshaner/openmc,smharper/openmc,wbinventor/openmc,smharper/openmc,walshjon/openmc,mit-crpg/openmc,sxds/opemmc,walshjon/openmc,mit-crpg/openmc,liangjg/openmc,sxds/opemmc,shikhar413/openmc,smharper/openmc,lilulu/openmc,amandalund/openmc,wbinventor/openmc,paulromano/openmc,bhermanmit/openmc,lilulu/openmc,johnnyliu27/openmc,samuelshaner/openmc,liangjg/openmc,mjlong/openmc,amandalund/openmc