Trends on major actinides from an integral data assimilation

CEA, DEN, DER, SPRC, Cadarache, F-13108 St Paul-Lez-Durance, FRANCE

^* Corresponding author: gerald.rimpault@cea.fr

Published online: 30 September 2020

Abstract

The objective of this work is to revisit integral data assimilation for a better prediction of the characteristics of SFR cores.

ICSBEP, IRPhE and MASURCA critical masses, PROFIL irradiation experiments and the FCA-IX experimental programme (critical masses and spectral indices) with well-mastered experimental technique have been used. As calculations are performed without modelling errors (with as-built geometries) and without approximations with the TRIPOLI4 MC code, highly reliable C/E are achieved.

Assimilation results suggest a 2.5% decrease for ²³⁸U capture from 3 keV to 60 keV, and a 4-5% decrease for ²³⁸U inelastic in the plateau region. For this energy range, uncertainties are respectively reduced to 1-2% and to 2-2.5% for ²³⁸U capture and ²³⁸U inelastic respectively.

The increase trends on ²³⁹Pu capture cross section of around 3% in the [2 keV-100 keV] energy range come from a low PROFIL ²⁴⁰Pu/²³⁹Pu ratio C/E. For ²⁴⁰Pu capture cross section, the increase trend of around 4% in the [3 keV-100 keV] energy range goes in the same direction as the recent ENDF/B.VIII evaluation though at a much lower level.

The nuclear data uncertainty associated to SFR ASTRID critical mass is reduced to 470 pcm.