A set of adjustments to the data library used in conjunction with the U.S. wims code was recently reported by Halsall. The relatively large effects of the recommended data changes on the prediction of LWHCR neutron-balance components are discussed in the context of lattice measurements carried out at the PROTEUS reactor facility. The consistency of both k∞ and reaction rate ratio results has been found to improve markedly with the new data library. An apparent shortcoming which remains, however, is the overprediction of reactivity for a fully-voided LWHCR core. © 1986.