Improving Nuclear Safety of Fast Reactors by Slowing Down Fission Chain Reaction

Table 3

Properties of neutron moderators at 20°C.

Moderator	Average logarithmic energy loss	Moderating ratio	Neutron age; (0.1 MeV0.5 eV); (cm^2)	Diffusion length (cm)	Mean lifetime of thermal neutrons (ms)
H2O	0.95	70	6	3	0.2
D2O	0.57	4590	58	147	130
BeO	0.17	247	66	37	8
^12C	0.16	242	160	56	13
Pbnat	0.00962	0.6	3033	13	0.8
^208Pb	0.00958	477	2979	341	598