The Los Alamos Scientific Laboratory has an unirradiated enriched uranium reprocessing facility. Various types of solutions are generated in this facility, including distillates and raffinates containing ppm of uranium and concentrated solutions with up to 400 grams U/t. In addition to uranyl nitrate and HNO{sub 3}, the solutions may also contain zirconium, niobium, fluoride, and small amounts of many metals. A uranium solution assay system (USAS) has been installed to allow accurate and more timely process control, accountability, and criticality data to be obtained. The USAS assays are made by a variety of techniques that depend upon state-of-the-art high-resolution Ge(Li) gamma-ray spectroscopy integrated with an interactive, user-oriented computer software package. Tight control of the system's performance is maintained by constantly monitoring the USAS status. Daily measurement control sequences are required, and the user is forced by the software to perform these sequences. Routine assays require 400 or 1000 seconds for a precision of 0.5% over the concentration range of 5--400 g/t. A comparison of the USAS precision and accuracy with that obtained by traditional destructive analytical chemistry techniques (colorimetric and volumetric) is presented.

A new type of electron-positron collider based on superconducting linacs is proposed. As in other schemes, the bunch energy is recovered by deceleration in the opposite linac, but the spent bunches are dumped after a single pass, thus avoiding many problems connected with their re-use. The needed low energy particles are produced by the monochromatic photons radiated coherently by the high energy bunches in a wiggler magnet before deceleration.

During the development of nuclear energy, a number of apparent anomalies have become evident in nuclear criticality. Some of these have appeared in the open literature and some have not. Yet, a naive extrapolation or application of existing data, without knowledge of the anomalies, could lead to potentially serious consequences. This report discusses several of these anomalies.

The technique of capture reaction studies of giant resonance properties is described, and a number of examples are given. Most of the recent work of interest has been in proton capture, in part because of the great utility (and availability) of polarized beams; most of the discussion concerns this reaction. Alpha capture, which has been a useful tool for exploring isoscalar E2 strength, and neutron capture are, however, also treated. 46 references, 14 figures. (RWR)

The computer program SEPHIS, developed to aid in determining optimum solvent extraction conditions for the reprocessing of nuclear power reactor fuels by the Purex method, is described. The program employs a combination of approximate mathematical equilibrium expressions and a transient, stagewise-process calculational method to allow stage and product-stream concentrations to be predicted with accuracy and reliability. The possible applications to inventory control for nuclear material safeguards, nuclear criticality analysis, and process analysis and control are of special interest. The method is also applicable to other counntercurrent liquid--liquid solvent extraction processes having known chemical kinetics, that may involve multiple solutes and are performed in conventional contacting equipment

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The procedure for fabrication of porous sintered-ceramic separators and the technical feasibility of using such separators in Li-Al/molten LiCl-KCl/FeS battery cells have been investigated. Processing techniques have been developed to fabricate ~1.5-2.5 mm thick, ~35-60% porous, flat, sintered Y{sub 2}O{ sub 3} and MgO separator plates with sufficient strength to allow handling prior to and during cell assembly. These separators performed successfully in laboratory-scale cells for up to ~2000 h and 283 cycles, indicating that the concept of a sintered separator is viable for Li-Al/FeS batteries. The particularly attractive features of these separators are potentially low cost, pre-fabricated form that allows easy cell assembly, and small pore size (average diameter 0.5-1.0 ~m) which provides good particle retention. The test results from the sintered-separator cells indicate that Y{sub 2}O{ sub 3} is probably unsuitable for long-term performance in Li-Al/FeS cells because of its reaction with the positive active material. This is in agreement with the recently reported data on cells with Y{sub 2}O{ sub 3} felt and powder separators. Sintered MgO separators, however, showed good chemical and mechanical stability in the cell environment. (auth)

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As a result of the reduced nuclear power demand and the growing concerns over the potential proliferation of sensitive nuclear materials, there has not been a necessity to make immediate decisions regarding near-term reprocessing and breeder reactor commercialization. Programs which formed the basic thrust of nuclear development in the early 1970's have already been adjusted: increased emphasis on problems of radioactive waste management; increased attention to nonproliferation objectives and subsequent reorientation of the overall fuel cycle and breeder programs; increased emphasis on a once-through light-water reactor technology; increased concern for a more detailed knowledge of the uranium resource base; reorientation of the uranium enrichment programs; and exploration of alternative fuel cycles (such as thorium) to minimize the use of plutonium. Nevertheless, major strategic decisions still loom over breeder commercialization, the breeder's requisite demand for reprocessing, and the future role of more proliferation-resistant nuclear technologies. The current program in the United States is organized to provide the necessary technology for the reprocessing of breeder fuels on a timetable that is consistent with the reactor development and demonstration program. Also addressed in this paper are the present day concerns of environmental protection, safety, nuclear material safeguards, and proliferation resistance. It is structured …

The resources and talents of many national and international organizations and laboratories, both governmental and industrial, are being used to establish analysis methods for predicting the embritlement condition of light water reactor (LWR) primary systems.. The exact interrelationships and responsibilites between those developing, uderstanding, combining, and apply state-of-the-art technology in dosimetry, metallurgy, and fracture mechanics for reactor systems analysis are being carefully reviewed and studied. This has resulted in a more comprehensive definition of the scope of new and updated ASTM standards required for the analysis and interpretation of LWR pressure vessel survillance results. Fifteen new and updated ASTM standards have now been identified, together with a restructuring of the main interfaces between the individual standard practices, guides, and methods. This paper briefly discusses these standards and the initial results of multi-laboratory research work involved in their validation and calibration.

This report addresses the automated electron microprobe identification of materials in stream sediments for he national uranium resources evaluation program.

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An introduction is given to some of the major processes which take place when low energy electrons collide with molecules. Temporary negative ion states, dissociative electron attachment, and vibrational and rotational excitation are emphasized. Resonances and some comments on H{sub 2}O are also covered. 45 refs.

This paper extends the procedure to analyse the heterogeneous FBR spectra with depletion.

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This report talks about Calculations of Flow Oscillations During Reflood Using Relap4/MOD6

The Los Alamos Scientific Laboratory has an unirradiated enriched uranium reprocessing facility. Various types of solutions are generated in this facility, including distillates and raffinates containing ppm of uranium and concentrated solutions with up to 400 grams U/t. In addition to uranyl nitrate and HNO{sub 3}, the solutions may also contain zirconium, niobium, fluoride, and small amounts of many metals. A uranium solution assay system (USAS) has been installed to allow accurate and more timely process control, accountability, and criticality data to be obtained. The USAS assays are made by a variety of techniques that depend upon state-of-the-art high-resolution Ge(Li) gamma-ray spectroscopy integrated with an interactive, user-oriented computer software package. Tight control of the system`s performance is maintained by constantly monitoring the USAS status. Daily measurement control sequences are required, and the user is forced by the software to perform these sequences. Routine assays require 400 or 1000 seconds for a precision of 0.5% over the concentration range of 5--400 g/t. A comparison of the USAS precision and accuracy with that obtained by traditional destructive analytical chemistry techniques (colorimetric and volumetric) is presented.