Abstract: The paper discusses the moderating problem to f the 14 MeV neutrons fromthe sealed neutron generator with mixed D-T beam for neutron radiography. Acombined structure of high density polythene with lead is proposed. The authorshave proved experimentally that adding some lead layer in polythene may decreasethe thermalization factor by one third compared with simple polythene and thatthe thermalization factor of this structure is less by 2--3 times than that withwater moderator. The experiments also prove that with and without lead in the moderator the change of cadium ratio is small.