A theoretical approach was used to calculate an inside layer of paraffin to moderate neutrons generated by a 20 MBq Californium-252 (Cf-252) source and subsequently an outside layer of lead to shield the gammas being produced in the paraffin. Materials are evaluated in terms of moderating power, absorbing ability, cost limitation and material availability. The results showed that the combination of thickness of 45.7 cm of paraffin with 7.05 cm of lead permits the meet the safety requirement to the planned dose limit outside of shielding.