The primary goal of this study was to develop a simulation model of a long counter available at Canadian Nuclear Laboratories (CNL). Using the Monte Carlo N-Particle version 6 (MCNP6) code, the model was used to calculate, as a function of incident energy, the number of counts recorded per source neutron, effective centre, and sensitivity. This study also carried out measurements of the neutron emission rate of and direct neutron flux at 2 m from an in-house 252 Cf neutron source.