The influence of nuclear models and Monte Carlo radiation transport codes on stray neutron dose estimations in proton therapy

•Monte Carlo code and nuclear model impact neutron spectra, dose and CR39 calibration.•Codes have larger neutron spectra variation in distal versus lateral positions.•The influence of nuclear models on secondary neutron production is visible for 180 and 210 MeV proton beams.•Calculated neutron dose equivalent varied up to 45% between the codes.•CR39 calibration factors varied within 10% and 5% between codes and nuclear models.