Abstract
A conceptual neutronic design of the cold-neutron source (CNS) for the Egyptian second research reactor (ETRR-2) was done using the MCNP code. Parametric analysis to chose the type and geometry of the moderator, and the required CNS dimensions to maximize the cold neutron production was performed. The moderator cell has a spherical annulus structure containing liquid hydrogen. The cold neutron gain and cold neutron brightness are calculated together with the nuclear heat load of the CNS. Analysis of the estimated performance of the CNS has been done regarding the effect of void fraction in the moderator cell together with the ortho: para ratio.