The neutron emission from fast tritons in plasmas with different magnetic shear configurations has been investigated in a dedicated experiment on JET. Short pulses of neutral beam injection were used to deposit fast tritons in deuterium plasmas. By comparing the measured neutron yield with predictions based on DT reaction calculations, fast triton losses can be assessed. The latter are expected to be very low according to neoclassical predictions based on Fokker-Planck simulation. Much larger "anomalous" beam-ion losses (up to 40%) have been reported in TFTR experiments for plasma conditions with reversed magnetic shear. The TFTR experiments indicated an excess DT rate in the simulation and, to a lesser extent, in the DD rate and plasma stored energy. This was interpreted as anomalous beam-ion loss associated with reverse shear due to an unidentified loss mechanism. Evidence of a similar effect was searched for in the JET experiments reported in this paper.