A shape selection method corresponding to energy discrimination above the detection threshold
energy was used to eliminate unwanted events disturbing evaluation of exposed CR-39 etched track
detectors. Detectors were irradiated with monoenergetic protons (0.5-3.5 MeV) and etched in 6 N NaOH
solution at 70?C for various times (2.5-31 h) to determine the energy discrimination level for protons,
established as 0.5?0.1 MeV. Recoil protons generated by fast neutrons emitted by 252Cf were detected with
a shape selection technique at various distances from the source in air and berated water. The threshold level
for fast neutrons and neutron-induced recoil charged particles is discussed. Etching time is optimised for
detecting fast neutrons emitted by spent fuel assemblies, with special consideration for recoil H, C and O
ions.
