Long-time experience in neutron flux moni- toring on irradiation in the LVR-15 research reactor in R y ez y proved that Au?Mn?Rb and Au?Mo?Rb(?Zn) monitor sets for short and long irradiation, respectively, are more suitable in our conditions than the most frequently used Au?Zr set. The advantages of the former monitor set have been described previously, in the present work we discuss the advantages of the latter monitor set for long irradiations in varying active core configurations of the LVR-15 reac- tor. The successful application of the Au?Mo?Rb(?Zn) monitor set has been verified by comparative determination of the neutron flux parameters a (epithermal flux distribu- tion parameter), f (thermal-to-epithermal neutron flux ratio), and Fc,Au (comparator factor) using this and the Au?Zr monitor set, and by analyses of certified reference materials, namely NIST SRMs 1547 Peach Leaves, 2711 Montana Soil, and 1633b Trace Elements in Coal Fly Ash.