Report containing ongoing research and development of the Oak Ridge National Laboratory's Physics Division.

Report concerning the relatively inexpensive fabrication of an aluminum-based fuel element for the Oak Ridge National Laboratory's 250-Mw Advanced Test Reactor.

Manual for the Oak Ridge National Laboratory's Isotopes Development Center. Includes procedures for the production, storage, and shipment of radioisotopes.

Report containing ongoing research and development taking place at the Oak Ridge National Laboratory's Electronuclear Division.

Report containing ongoing research and experiments of the Oak Ridge National Laboratory's Instrumentation and Controls Division.

In a sense, the whole process of differentiation is one of directed functional mosaicism. It is, however, the accidental or random juxtaposition in the same organism of cells having actually or effectively different genotypes that is generally thought of as true mosaicism. The study of this condition constitutes a perfect meeting place for the fields of genetics and developmental biology, providing, as it does, interrelated information on mutability, cell lineage (including the special problems of cell lineage of the germ line), and the effect of genotype on part of the organism versus the whole. The discovery in recent years that most or all of one X chromosome of the normal mammalian female become randomly inactivated early in development, an event that leads to functional mosaicism, provides us with a great potential tool for the study of gene action. The present paper will attempt to bring together results of diverse observations and experiments (many of them as yet unpublished) bearing on both genetic and functional mosaicism in the mouse.

A replica electron microscope study of as-polished and cathodically etched surfaces of pyrolytic carbon coating on fuel particles has been made in an attempt to characterize coatings that showed as much as a 30% difference in bult density. High and low density coating could be characterized by their polished surface textures; however, these features were not indicative of the true structure as seen by direct electron transmission. Microvoids detected by the transmission study of cleavage flakes exist on too fine a scale to be observed either optically or by electron microscope examination of replicas of the polished surface. Other features such as the effect of cathodic and chemical etching, coating delamination, and duplex coating interfaces have also been examined.