Neutron poison burnout and effects on SNS moderator performance

Abstract

Detailed neutron absorber burnup calculations were performed for the poison plate and decoupler layers of the decoupled ambient water and liquid hydrogen moderators of SNS. Although local poison burnout was identified for the water moderator at 32 GWh and local decoupler burnout was becomes apparent at the hydrogen moderator at 37 GWh delivered proton beam energy, both moderators see major impacts to the moderator performance by increases of pulse widths and spectral changes only past the stated burnout energies.