There is currently no way to re-use ray trace files in CFX. By default, the ray trace file is created in the run directory and deleted after the run completes. For a parallel run, a separate ray trace file will be written for each partition. When using the Monte Carlo or Discrete Transfer radiation models, the output files discussed in section 3.2.16. CFX Radiation File can be obtained by setting the Diagnostic Output Level to 1 or 2 under Solver Control > Advanced Options > Thermal Radiation Control (see 10.8.5.2. Diagnostic Output Level in the CFX Modeling Guide).