DRACCAR code validation against the ballooned cluster experiment A2R038 of the ACHILLES experimental program

This report describes the work performed by ENEA on the DRACCAR code validation against the ballooned cluster experiment A2R038 of the ACHILLES experimental program. The selected test was a forced reflooding experiment carried out on an assembly containing ballooned rods which simulate a partial flow blockage for incoming water and steam. The boundary conditions of the test were the same as for the unballooned cluster experiment A1R030, simulated with the 2.1 version of DRACCAR code during the first period of NURESAFE project. The obtained numerical results and the comparison with experimental data are discussed in the report. All calculations have been performed with the new 2.2 version of DRACCAR. The documented activity complies with the ENEA commitments of the NURESAFE (NUclear REactor SAFEty simulation platform) Project, in the Work Package 3.1.1 (Improvements and developments of system codes and coupled fuel–thermal-hydraulics codes).