The invention is a tomograph modified to be in a clamshell configuration so that the ring or rings may be moved to multiple sampling positions. The tomograph includes an array of detectors arranged in successive adjacent relative locations along a closed curve in a first position in a selected plane, and means for securing the detectors in the relative locations in a first sampling position. The securing means is movable in the plane in two sections and pivotable at one point and only one point to enable movement of at least one of the sections to a second sampling position out of the closed curve so that the ends of the section which are opposite the point are moved apart a predetermined space.

A device is described for supporting a nuclear fuel rod in a fuel rod assembly which allows the rod to be removed without disturbing other rods in the assembly. A fuel rod cap connects the rod to a bolt which is supported in the assembly end fitting by means of a locking assembly. The device is designed so that the bolt is held securely during normal reactor operation yet may be easily disengaged and the fuel rod removed when desired.

This invention, which resulted from a contract with the United States Department of Energy, relates to a means for shifting the wavelength of light and, more particularly, to a means for changing the wavelength of a laser beam so that the beam can be effectively used in a process for separation uranium isotopes. As disclosed in US Patent 3,940,615, /sup 235/U can be separated from /sup 238/U by selectively ionizing the /sup 235/U isotope in a vapor containing both /sup 235/U and /sup 238/U, this ionization being effected by passing a laser beam having a proper frequency (or wavelength) through the vapor. Doppler shifting of the wavelength of a laser beam to obtain an optimal light wavelength for ionizing /sup 235/U in such a separation process has been proposed heretofore. However, the applicants are aware of no apparatus for Doppler shifting of the wavelength of light that has the features or advantages of apparatus constructed in accordance with the principles of their invention. A light beam is reflected back and forth between a rotating body having a retroreflection corner at opposite ends thereof and a fixed mirror to change the wavelength of the light beam by the Doppler effect.

Microspheres for nuclear waste storage are formed by gelling droplets containing the waste in a gelation fluid, transferring the gelled droplets to a furnace without the washing step previously used, and heating the unwashed gelled droplets in the furnace under temperature or humidity conditions that result in a substantially linear rate of removal of volatile components therefrom. Fuel particles were also produced using this method.

A roundness calibration standard is provided with a first arc constituting the major portion of a circle and a second arc lying between the remainder of the circle and the chord extending between the ends of said first arc.