3 days on POLARIS are requested to study three pyrochlore compositions in the Na2O●Bi2O3●TiO2 system that has been reported only once in the literature, without any characterisation. Unpublished electrical data shows low conductivity comparable to insulating Na0.5Bi0.51TiO3+δ perovskite but much lower than oxide-ion conducting Na0.50Bi0.49TiO3-δ (NB49T) even though the oxygen vacancies concentration in the pyrochlores is much higher. In dielectric measurements, relaxor behaviour is observed near room temperature. Variable temperature Neutron diffraction should enable to determine the unit cells, ion displacements and occupancies. This information will be valuable to comprehend the dielectric behaviour and electrical conduction mechanism(s) in this and other NBT related systems.