[en] Isotope shift of the recycled uranium atoms including the ²³⁶U was measured by laser induced fluorescence method. Eight even levels at 2 eV and three odd levels at 4 eV were measured with isotope shifts among ²³⁸U, ²³⁶U and ²³⁵U obtained. As for the measurement of the 4 eV levels, the Doppler free two photon absorption method was used, and the hyperfine structure of the ²³⁵U was analyzed simultaneously. The isotope shift of ²³⁴U was also observed in the three transition. (J.P.N.)

[en] Three-dimensional numerical calculations of an inviscid gas flowing past scoops in a gas centrifuge are performed by solving the Euler equations using the explicit Roe upwind scheme with a second-order of accuracy. The scoops are placed close to the bottom end plate, there is no covering baffle plate and no inlet flow is assumed. The numerical grid employed is of the multibox type. For a cylindrical scoop model a detached bow shock is formed in front of the scoop. Behind the shock, strong radially inward motion of gas towards the central axis is induced, and it excites an upward flow which becomes a countercurrent. The inward flow just in front of the scoop produces a vortex column in the upstream region of the scoop. For a wing-shaped scoop model, an oblique shock attached to the scoop is formed, and an inward flow is induced behind the shock. The shock is not so strong as that in the case of a cylindrical scoop model. The drag coefficient of the wing-shaped scoop is almost one-fourth of that of the cylindrical scoop. The addition theorem of the scoop drag is verified for the wing-shaped scoop. (author)

[en] Two new phosphoroorganic liquid ion exchangers: an equimolar mixture of mono- and di-nonylphenyl phosphoric acids (NPPA) and an equimolar mixture of mono- and di-hexylphenyl phosphoric acids (HPPA) were tested in the process of uranium recovery from wet-process phosphoric acid used to the production of the fertilizers. Both NPPA and HPPA can be utilized in a double circuit recovery system in which uranium(4) is extracted with a kerosene solution of NPPA or HPPA in the first stage, and then uranium (6) is stripped with a recycled stripping solution (concentrated phosphoric acid) containing an oxidative reagent. Afterwards uranium is concentrated by means of the extraction process with mixtures of di- (2-ethylhexyl) phosphoric acid (D2EHPA) and trioctylphosphine oxide (TOPO) diluted with kerosene. (NH)₄UO₂(CO₃)₃.2H₂O, as a final product, is salted out from this solution by acting with gaseous NH₃ and CO₂. Equilibrium data are presented using pure phosphoric acid and industrial liquids as the aqueous feed phase. Statistical regression equations describing the influence of process parameters of the recovery process are presented. 20 refs., 9 figs., 2 tabs. (author)

[en] Nuclear Fuel Bureau of Ministry of Nuclear Industry (MNI) of China has experiences of diffusion enrichment. This paper describes the development and comparison of the different enrichment techniques. It deals with the centrifuge development currently being undertaken in China. It also describes the status of R and D work about Laser Isotope Separation. The paper concludes with our preference of development programme on uranium enrichment

[en] There are two types of laser uranium enrichment methods: those using vapor uranium (atomic processes) and those using UF₆ (molecular processes). For the latter methods, a dye laser, combined with another laser for exciting it, is thought to work ef1ectively. For the excitation, the copper vapor laser appears promising. The present report describes the mechanism, structure and characteristics of the copper vapor laser, which may be used alone or in combination with a series of master oscillator power amplifiers (MOPA chain system), and also addresses some recent topics concerning the development of these lasers. The features of the copper vapor laser are discussed first, focusing on the main electric circuit, thermal and electrical characteristics, and radial distribution of the laser beam intensity. In this type of laser, vaporized neutral copper atoms are excited to a higher energy level as they collide with electrons, and then transit down to the original level while emitting light. The MOPA chain system is then discussed, focusing on the structure and performance of the oscillator, pulsed light stretching cell, amplifier, and assembled chain system. (N.K.)

[en] Gaseous diffusion plants that operate in the United States represent a unique combination of nuclear and chemical hazards. Assessing and controlling the health, safety and environmental risks associated with these plants require a unique methodology. Such a methodology has been developed for the diffusion plants and will soon be utilized to assess and control the risk of operating the plants. - The methodology provides an organized approach for identifying hazards and ranking the resulting risk to health, safety and the environment. The analysis is intended to be comprehensive, defendable and cost effective. To meet the goals of the US Department of Energy, a methodology was developed that required modification of existing analysis methods in order to address the unique hazards associated with gaseous diffusion plants. - Several state of the art risk based methods were modified and linked together to form a unique analysis approach that meets the specific safety goals of the gaseous diffusion plants. This approach will address the unique hazards that exist in diffusion plants as well as the unique consequences that can be caused by natural phenomena hazards. A three step approach is used to identify the risk involved in operating the plants. A brief description of each step and information on the transfer of analysis results from one step to the next are provided. - The specific results of the Accident Analysis allow the plants to develop the operating safety requirements, or limits of operation, which define the envelope of operations ensuring that the safety risk is maintained at an acceptable level. (author). 2 refs, 1 fig

[en] BNFL is in a unique position in that it has commercial experience of diffusion enrichment, and of centrifuge enrichment through its associate company Urenco. In addition BNFL is developing laser enrichment techniques as part of a UK development programme in this area. The paper describes the development programme which led to the introduction of competitive centrifuge enrichment technology by Urenco and discusses the areas where improvements have and will continue to be made in the centrifuge process. It also describes the laser development programme currently being undertaken in the UK. The paper concludes by discussing the relative merits of the various methods of uranium enrichment, with particular reference to the enrichment market likely to obtain over the rest of the century

[en] Published in summary form only

[en] This patent describes a method for recovering uranium values from ground uranium-containing ore. It comprises: separating the ore into coarse and fines fractions; adding to the fines fraction a diluent solid material; contracting the mixture of the fines fraction and the diluent solid material with a first leachant and separating a pregnant leach solution

[en] The introduction of safety system to the gaseous diffusion plants gave rise to the need for some method of assuring that the testing, identification, and changes to safety system are reviewed and controlled by authorized personnel. This need has been satisfied through the implementation of a configuration control system. The configuration control system involves each major division of the plant and provides a record of the tests, maintenance activities and a historical record of these activities for each safety system