[en] Delta-plutonium, γ-uranium and alloys based on them have a number of anomalous properties not inherent in common metals and alloys. In addition to the properties known in the literature the paper discusses some other anomalous properties of these phases, in particular, an increase of the atomic volume as a result of cold working and prolonged room-temperature self-irradiation. A discussion is given as to the nature of the above phenomena. It is concluded that the anomalous properties of the phases considered result from the covalent component of the bond, that is due to the hybridization of the 5f and 6d levels and leads to a deviation of their structure from ideal fcc- and bcc-lattices. (Auth.)