X-ray diffractometry measurements were made as a function of temperature on a series of polycrystalline LaV/sub x/Nb/sub 1-x/O/sub 4/ compounds (0 < x < 0.3) to determine the effect of V substitutions on the temperature of the monoclinic/tetragonal transformation. The purpose was to provide basic information relating to crystal lattice stability in ABO/sub 4/ compounds that are either candidates or are appropriate models for candidate materials for hosting nuclear-waste ions. Partial substitution of V/sup 5 +/ on the Nb/sup 5 +/ site significantly lowers the tetragonal scheelite (I4/sub 1//a) to monoclinic fergusonite (I2/c) transformation, from 770/sup 0/K in LaNbO/sub 4/ to approximately 215/sup 0/K for LaV/sub 0/ /sub 25/Nb/sub 0/ /sub 75/O/sub 4/ (the solubility limit is close to x = 0.35). The transformation is displacive, of second order, involving two coupled order parameters. Heat capacity measurements on LaV/sub 0/ /sub 25/Nb/sub 0/ /sub 75/O/sub 4/ showed that the specific heat anamoly at the transformation point is extremely small. It is concluded that the two polymorphic forms of LaV/sub x/Nb/sub 1-x/O/sub 4/ have very nearly the same free energies over a substantial range of temperature below the transformation.

Two principal underground energy storage technologies are discussed--Seasonal Thermal Energy Storage (STES) and Compressed Air Energy Storage (CAES). The Underground Energy Storage Program objectives, approach, structure, and milestones are described, and technical activities and progress in the STES and CAES areas are summarized. STES activities include aquifer thermal energy storage technology studies and STES technology assessment and development. CAES activities include reservoir stability studies and second-generation concepts studies. (LEW)

Pacific Northwest Laboratory (PNL) is currently conducting research for the US Nuclear Regulatory Commission (NRC) on uranium recovery process wastes for both active and inactive operations. NRC-sponsored uranium recovery research at PNL is focused on NRC regulatory responsibilities for uranium-recovery operations: license active milling and in situ extraction operations; concur on the acceptability of DOE remedial-action plans for inactive sites; and license DOE to maintain inactive sites following remedial actions. PNL's program consists of four coordinated projects comprised of a program management task and nine research tasks that address the critical technical and safety issues for uranium recovery. Specifically, the projects endeavor to find and evaluate methods to: prevent erosion of tailings piles and prevent radon release from tailings piles; evaluate the effectiveness of interim stabilization techniques to prevent wind erosion and transport of dry tailings from active piles; estimate the dewatering and consolidation behavior of slurried tailings to promote early cover placement; design a cover-protection system to prevent erosion of the cover by expected environmental stresses; reduce seepage into ground water and prevent ground-water degradation; control solution movement and reaction with ground water in in-situ extraction operations; evaluate natural and induced restoration of ground water in in-situ extraction operations; …

The vapor-liquid equilibrium of the Mg(NO/sub 3/)/sub 2/-HNO/sub 3/-H/sub 2/O system in concentrations of 0 to 70 wt % Mg(NO/sub 3/)/sub 2/ and 0 to 75 wt % HNO/sub 3/ at atmospheric pressure was correlated by two approaches. One was based on a dissociation equilibrium expression in which the activities of the reacting species (HNO/sub 3/, NO/sub 3//sup -/, and H/sup +/) were approximated with mole fractions. The activity coefficients of the undissociated HNO/sub 3/ and H/sub 2/O were correlated as functions of the concentrations of magnesium nitrate and nitric acid by second-order polynomials. The average absolute difference between predicted and experimental values was 8% for the mole fraction of acid in the vapor and 8/sup 0/K for the bubble-point temperature. The second approach was to correlate the mean ionic rational activity coefficient of water with a form of the excess Gibbs energy composed of two terms. One term, a function of the ionic strength, accounts for the coulombic (ionic) interactions; the other term accounts for the non-coulombic (molecular) interactions. The average absolute difference between predicted and experimental values was 9% for the mole fraction of acid in the vapor, and 10/sup 0/K for the bubble-point temperature.

Vertical poloidal asymmetries of hydrogen isotopes and low-Z impurity radiation in the PDX tokamak may be caused by poloidally asymmetric sources of these elements at gas inlet valves, limiters or vacuum vessel walls, asymmetric magnetic field geometry in the region beyond the plasma boundary, or by ion curvature drifts. Low ionization states of carbon (C II- C IV) are more easily influenced by edge conditions than is CV. Vertical poloidal asymmetries of CV are correlated with the direction of the toroidal field. The magnitude of the asymmetry agrees with the predictions of a quasifluid neoclassical model. Experimental data and numerical simulations are presented to investigate different models of impurity poloidal asymmetries.

Objectives and scope: The principal objectives of this study were to assess the past and current water quality of the impoundment, its major tributaries, and its discharge, and to address the environmental impact of raised pool levels. Data collection was directed toward documenting the temporal and spatial variations in physical, chemical, and biological characteristics of the water, to estimate annual nutrient and suspended sediment loading, and to determine the algal biomass, dominant genera, algal growth potential, and limiting nutrient.

The DOE/NSF Nuclear Science Advisory Committee (NSAC) is preparing a new Long Range Plan for the development of nuclear science. This document, written as input to the Long Range Plan subcommittees; describes a number of ways that experiments with incident neutrons impact on outstanding problems in nuclear reactions and spectroscopy. It is argued that major extensions of present capabilities are required to carry out these experiments.