Improved Mixed Oxide Fuel Calculations with the Evaluated Nuclear Data Library JEFF-3.2

Abstract

An overestimation of the k eff values for MOX fuels was identified with Monte-Carlo (TRIPOLI4) and deterministic (APOLLO2) calculations based on the Evaluated Nuclear Data Library JEFF. The overestimation becomes sizeable with the Pu-ageing, reaching a reactivity change of ∆ρ ≃ +700 pcm for integral measurements carried out with MOX fuel containing a large amount of Americium. This bias was observed on various critical configurations performed in the zero power reactor EOLE of the CEA Cadarache, France. The present work focuses on the improvements achieved with the new 239 Pu and 241 Am Evaluated Nuclear Data Files available in the latest version of the JEFF library (JEFF-3.2). The Resolved Resonance Range of the plutonium evaluation was re-evaluated at ORNL (Oak Ridge National Laboratory) with the SAMMY code in collaboration with the CEA Cadarache. The resonance parameters of the Americium evaluation were obtained with the REFIT code in collaboration with the research institutes IRMM

The joint evaluated fission and fusion nuclear data library, JEFF-3.3

“…A detailed explanation of the evaluation work and the benchmark results can be found in Refs. [83,84]. Resonance parameters for n + 241 Am were derived by adjusting them in a least squares fit to experimental data that are reported in the EXFOR library together with the transmission and capture data obtained by Lampoudis et al [85] at the GELINA facility.…”

“…The 111 stable nuclide evaluations from TENDL adopted in the JEFF-3.3 neutron sub-library Nuclides 17,18 O, 20,21,22 Ne, 31 P, 32,33,34,36 S, 36,38 Ar, 39,41 K, 40,42,43,44,46 Ca, 45 Sc, 46−50 Ti, 51 V, 64,[66][67][68]70 Zn 69,71 Ga, 75 As, 74,[76][77][78]80 Se, 79,81 Br, 80,[82][83][84]86 Kr, 85 Rb, 84,86−88 Sr, 93 Nb, 100,101 Ru, 102,110 Pd, 107 Ag, 122,124 Sn, 120,…”