23Na evaluation with CONRAD for fast reactor applications

For sodium-cooled fast reactor (SFR), sodium void reactivity effect (SVRE) is a key parameter being particularly sensitive to sodium nuclear data.. Present evaluations of 23Na available in the major libraries (JEFF-3.1.1, ENDF/B-VII.0, JENDL-3.3 and TENDL-2009) exhibit large discrepancies especially in the high energy range. These differences translate into uncertainties in the prediction of integral parameters and, in fine, into expensive safety margins. A new evaluation of sodium nuclear data is currently under way using the CONRAD code at CEA Cadarache. Several extensive developments have been made to implement ECIS and TALYS codes interface into CONRAD for optical and statistical model calculations. The modeling of the 23Na cross-sections and angular distributions are based on a robust and innovative methodology, which takes into account both differential and integral experiments in the evaluation process. First, we show the impact of sodium nuclear data from different libraries on SVRE in MASURCA and ZPPR experiments. The methodology using CONRAD to produce an adjusted 23Na evaluation, based on differential and integral experiments, is described. Finally, the preliminary results obtained with this methodology is presented. (authors)