Coupling Fixed-Source Criticality or Criticality and Shielding Modes Within TRIPOLI-4® Monte Carlo Code

A specific simulation mode has been implemented in the TRIPOLI-4® Monte Carlo code to deal with subcritical or critical configurations together with the use of variance reduction techniques usually dedicated to shielding studies. This multiple mode enables a coupling between the fixed-source criticality (or the criticality) mode with the shielding mode, within the Monte Carlo code, with the aims to simplify the calculation and help users run the code. Test cases with a fuel assembly in borated water are presented to illustrate the use of this feature in a subcritical case. An experimental setup is then investigated in a critical case. It is based on the Criticality Accident Alarm System benchmark experiment conducted in the SILENE critical assembly facility. Stability and efficiency issues are examined, and promising results are presented and discussed in both cases.