Regular Article

Neutronics characterization of an erbia fully poisoned PWR assembly by means of the APOLLO2 code

ENEA, Via Martiri di Monte Sole 4, 40129 Bologna, Italy

^⁎ e-mail: roberto.pergreffi@enea.it

Received: 19 October 2016
Received in final form: 19 December 2016
Accepted: 24 January 2017
Published online: 21 March 2017

Abstract

Recently, increasing demands on the reduction of fuel cycle costs have led to higher burnup fuel designs. According to the erbia-credit super high burnup fuel concept, developed by mixing low content of erbia to UO₂ powder directly after reconversion process so that all fuel pins in a given fuel assembly are homogeneously doped, the present study aims to characterize, from a neutronic point of view, a 17 × 17 pressurized water reactor assembly enriched to 10.27 wt.% in ²³⁵U with an erbia content of 1 at.% (i.e. 0.7 wt.%) by means of the deterministic neutronic code APOLLO2. For this purpose, a simplified thermal-hydraulic analysis was performed in order to evaluate the effects on fuel thermal conductivity of adding erbia to uranium oxide. The results obtained allow to conclude that an Er-doped assembly enriched to >5 wt.% in ²³⁵U represents an advantageous solution for very long fuel cycles, and it is so suited for very high burnups.