Calculation of moderator analogues for 14 MeV neutrons as source were made at a IBM/PC AT computer using TAMAKER-ANISN program and 46 groups (25 neutron groups, 21 photon groups) UW cross section data. The intensifying effect of lead and natural uranium for moderating 14 MeV neutrons is confirmed. Adopting proper structure of the moderator, the intensifying factor M (times) may be larger than 3. Using lead and natural uranium in sub-critical assemblies (or call boosters), with 14 MeV neutrons as source, with the same dimension as that of above, the intensifying effect is also confirmed. With a proper structure of sub-critical assembly, the intensifying factor M may be close to or even larger than (1-k)^-1 where k is the effective multiplication factor.