05 Nuclear fuels (scientific, technical)

97101223 Tensile properties of polyester mortar using PET and fly ash wastes Rebeiz, K. S. et al. J. Mater. Sci. Left., 1996, 15, (14), 1273-1275. Discusses how the replacement of up to 50% sand with coal fly ash in polyester mortar formulations with recycled PET resulted in an increase of tensile strength. Replacement of more than 50% sand results in lack of resin for coating the large surface area of fly ash. The tensile modulus of elasticity of the mortar decreased as the amount of fly ash increased, since fly ash less stiff than sand. A low tensile modulus of elasticity is beneficial when the mortar is used as an overlay on Portland cement concrete, as the intensity of shear stress between the two materials is minimized.

97101224 Treatment of alkaline fly ashes Hon, Y. et al. Jpn. Kokai Tokkyo Koho JI) 08, 155, 417 [96, 155, 4171 (Cl. B09B3/00), 18 Jun 1996, Appl. 941302, 003, 6 Dee 1994, 8 pp (In Japanese). As detailed in this paper alkaline fly ashes are treated by kneading with water, blowing COZ, mixing with phosphoric acid-base heavy metal-fixing agents and kneaded to prevent elution of heavy metals and scale components. The treatment is especially suited for soot and dust containing alkalis such as unreacted slaked lime.

97101225 Treatment of molten fly ashes Azuma, Y. Jpn. Kokai Tokkyo Koho JP 08, 155, 424 [96, 155, 4241 (Cl. B09B3/00), 18 Jun 1996, Appl. 94/331,631,8 Dee 1994,8 pp (In Japanese). Details treatment of molten fly ashes, generated by melting of incinerated materials containing valuable metals at a prescribed melting temperature to give slags involves the following steps; (1) collecting the molten fly ashes from waste gas emitted from the melting treatment, and dissolving into aqueous solutions, (2) electrolysis of the aqueous solutions using specific valuable metals as anodes to precipitate and recover valuable metals with lower ionization tendency on cathodes, (3) adding alkalis into the aqueous solutions to precipitate and recover the residual valuable metals as hydroxides, and (4) drying and oxidizing the hydroxides to give oxides which are introduced to the melting process, Preferably, soluble electrodes are used to prevent generation of toxic gases such as chlorine The method enables the reduction of volume of incineration ashes and fly ashes by recovering valuable metals such as Pb, Cu, and Hg.

97101226 Use of amino phase adsorbent for biomass tar sampling and separation Brage, C. er al. Fuel, 1997, 76, (2). 137-142. Discusses how, in order to reduce sampling and sample separation time, a highly efficient method based on solid-phase adsorption (SPA) on amino phase was designed. This method is suitable for intermittent trapping of tar compounds ranging from benzene to coronene prevailing in product gases from thermal decomposition of biomass at 700-1000°C. Using eluotropic elution, adsorbates are selectively desorbed into aromatic and phenolic fractions and then determined by gas chromatography with flame-ionization detection. The method can be readily applied to establish cold-trap and filter performance and for industrial emission control. The usefulness of the method is compared with the cold-trapping techniques and the novel solid- phase micro extraction (SPME) technique, not tested earlier for tar sampling.

97101227 Using of coal extraction products to prevent corro- sion of metals Samoilenko, G. V. et al. Khim. Tverd. TopI. (Moscow), 1996, (2). 85-92. (In Russian) Presents a study in which the humic compounds obtained by extraction of four types of coals in quinoline solutions are considered as potential corrosion inhibitors for metals in acidic media (e.g. HCI, HzS04) and as additives to industrial inhibitors. Products of coal extraction had high anti- corrosion activity and were recommended as efficient corrosion inhibitors. A 0.5% solution of coal extracts in 15% HCI at 20” provided the best protection of steel (99.8%).

97101226 Utilization of power station residues in the Rhenish lignite district, Germany Oster, A. Glueckauf, 1996, 132, (7), 351-356. (In German) The work presents a study on the utilization of ashes and flue gas desulfurization (REA) gypsum from the power stations of the Rhenish lignite district. Because of the high CaO content of the ashes they have good hydraulic properties and are used together with REA-gypsum for the refilling of opencast mines. Seventy percent of the REA-gypsum are used in building industries. The ashes with high CaO and MgO content also can be used in forestry and agriculture as fertilizers, or against the acidification of rocks removed from the opencast mines.

05 NUCLEAR FUELS

Scientific, Technical

97101229 Behaviour of criticality eigenvalues of one-speed transport operator with linearly anisotropic scattering Sahni, D.C. et al. Ann. Nucl. Energy, 1996, 24, (2). 135-145 Considers the c-eigenvalue problem of the one-speed transport equation with linearly anisotropic scattering and vacuum boundary conditions. The variation of the full c’-spectrum with the system parameters is studied numerically and explained theoretically. The article notes that the c- eigenvalues are complex only for a finite interval of h,, the strength of anisotropic scattering. It is shown that the simple buckling approximation is valid for large systems, irrespective of the form or positivity of the scattering function.

97101230 Calculation of the systematic error and correction factors in gamma waste assay system Dung, T. Q. Ann. Nucl. Energy, 1997, 24, (1) 33-47. Presents a model for the calculation of systematic errors and correction factors in a Segmented Gamma Scanner. The calculation values exhibit good agreement with experimental values. Through a simple code the results can be used to estimate the range of measured uncertainty, and for giving the correction terms to improve accuracy.

97101231 Detection of subcooled boiling in a PWR using noise analysis and calculation of the steam void fraction Laggiard, E. and Runkel, J. Ann. Nucl. Energy, 1997, 24, (1). 49-54. The temperature fluctuations of thermocouples situated above the core in a 1300 Mw pressurized water reactor (PWR). as well as the neutron noise of self power neutron detectors (SPNDs) located in the upper part of the core were analysed. Subcooled boiling was detected. The changes observed in the noise functions due to the presence of bubbles were compared to the behaviour of the same functions measured by other authors during boiling simulated experiments. The cross-sectional average volumetric void fraction was calculated following a profile-fit model of subrooled boiling and used to interpret the temperature and neutron fluctuations measured in the PWR.

97101232 A 1-D multigroup diffusion equation nodal model using the orthogonal collocation method Feiz, M. Ann. Nucl. Energy. 1997, 24, No. 3, 187-196. Presents a I-D nodal model for solving the multigroup diffusion equation. The neutron flux is calculated at certain collocation points within a given node using an iterative process. The partial currents are used at the nodal interfaces, The location of the collocation points within a node is determined from the roots of the transformed Legendre polynomials. Two sample problems were used to test the accuracy of the model. In hoth sample problems the results of the nodal model matched the results of the fine-mesh finite-difference calculations. The model presented here has been developed in a general format and the necessary equations for any number of collocation points can be obtained with ease.

97101233 A Markov Chain approach for deriving the statistics of time-correlated pulses in the presence of non-extendible dead time Degweker, S. B. Ann. Nucl. Energy, 1997, 24, (I), l-20. Presents a study into the problem of statistical derivation of time-correlated detector pulses in the presence of a non-extendible dead time. The study was conducted by constructing a Markov Chain to describe the process. Expressions for the transition matrix are derived for problems in the passive neutron assay of Pu and (zero-power) reactor noise. Perturbative and numerical solutions of the master equations are discussed for a simple problem in the passive neutron assay of Pu. Expressions for the mean count rate and variance in a given interval are derived.

97101234 Monitoring of the temperature reactivity coefficient at the PWR nuclear power plant Kostid, L. Ann. Nucl. Energy, 1996, 24, (1). 55-64. Details a method for monitoring temperature coefficient of reactivity of pressurized water reactors based on the correlation of fluctuations in signals of in-core neutron detectors and core-exit thermocouples and neural network paradigm. It is shown that the moderator temperature coefficient of reactivity can be predicted with the aid of the backpropagation neural network technique by measuring the frequency response function between the in-core neutron flux and the core-exit coolant temperature.

97101235 Neutronic model for modal multichannel analysis of out-of-phase instability in boiling water reactor cores Hashimoto, K. et al. Ann. Nucl. Energy, 1997, 24. (2), 99-l 11. Discusses the derivation of a neutronic model for linear multichannel analysis of out-of-phase (regional) instability in a BWR core. In this model, the zero-power transfer function of a spatial-harmonic mode, the nodal component of the harmonic amplitude and the node-wise feedback

98 Fuel and Energy Abstracts March 1997