Extended set of activation monitors for NCT beam characterization and spectral conditions of the beam after reactor fuel conversion

• Conversion from HEU to LEU has only no impact on the spectral characteristics of BNCT beam.
• Neutron flux after conversion is comparable with the flux before the conversion.
• ZN64G, GA71G, AS75G, PD110M, AG109M, SB121G, SB123G reaction are promising for beam monitoring.

Since 2010 the LVR-15 reactor has been gradually converted from highly enriched fuel (36 wt% 235U) to low enriched fuel with the enrichment of 19.75 wt% 235U. Paper presents influence of the core pattern changes on the neutron characteristics of the epithermal beam. The determination of neutron spectrum free in the beam was done with a set of neutron activation monitors. After the reactor conversion the change in neutron spectrum is not provable as differences are in the range of measurement errors.