Uncertainty quantification in RELAP5-3D© simulation of NACIE experimental facility focused on code validation
The best estimate plus the uncertainty quantification methods applied to a computer code play a key role in the development of the innovative Generation IV nuclear reactors for the improvement of knowledge and the good evaluation of the safety margins for new phenomena. The aim of this proposal is to validate an uncertainty quantification approach using the RAVEN code. RAVEN, developed at the Idaho National Laboratory, is a multipurpose probabilistic and uncertainty quantification platform, capable to communicate with any system code, implemented with an integrated validation methodology involving several different metrics. In this activity, a coupling calculation RELAP5-3D/RAVEN will be performed to validate the uncertainty quantification approach. The simulations will concern two test conducted on NACIE (NAtural CIrculation Experiment) facility, a non-nuclear loop-type system using Lead-Bismuth Eutectic (LBE) as coolant, realized at the ENEA Brasimone Research Centre (Italy) in order to support the development of the GEN-IV reactors. The experimental test aimed to investigate the phenomena related to the natural and gas enhanced circulation flow regimes of HLMs, and to test and validate the main components in a LBE environment. A numerical 1-D model of the NACIE facility will be realized and the post-test analysis will be carried out using RELAP5-3D© ver. 4.3.4. After that, a statistical analysis will be performed using RAVEN computer code.
In summary, the innovations which this activity aims to achieve are:
1. the validation of the uncertainty quantification methodology using RAVEN code;
2. the verification and validation of RELAP5-3D for HLM application