Loss of MeV-energy protons to the first wall during H-minority second harmonic ion cyclotron range of frequency (ICRF) heating has been measured for the first time by neutron signals emitted by 11 B(p,n) 11 C reaction in B 4 C coated divertor tiles and boronized tiles in the JT-60U tokamak. Since the reaction has a threshold energy of 3.0 MeV, the neutron signal indicates loss of fast protons whose energy is more than 3 MeV. Measurements of gamma-ray lines emitted from reaction between the fast protons and plasma impurities are also used for measurements of confined protons accelerated up to 5 MeV.