Erbium: alternative poison? Stabilisation additive? What future?

Abstract Erbium was proposed as alternative poison to gadolinium at a very early stage. The potential interest of this poison compared to gadolinium is that it presents a relatively low ( 167 Er) absorption cross section in the thermal range and a non-negligible resonance integral that leads to a relatively slow consumption kinetic rather adapted to long or even very long cycles. The poisoning mode with this element, when homogeneous in low concentration (