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King, F.; Stroes-Gascoyne, S.
Atomic Energy of Canada Ltd., Pinawa, Manitoba (Canada)1996
Atomic Energy of Canada Ltd., Pinawa, Manitoba (Canada)1996
AbstractAbstract
[en] Microbially influenced corrosion (MIC) of copper nuclear fuel waste containers may occur in a disposal vault located 500-1000 m underground in the granitic rock of the Canadian Shield. The extent and diversity of microbial activity in the vault is expected to be limited initially because of the aggressive conditions produced by γ-radiation, elevated temperatures and desiccation of the clay-based buffer in which the containers will be embedded. Experimental results on the heat- and radiation-sensitivity of the natural microbiota in buffer material are presented. The data suggest that the low water activity in the buffer material will severely limit the growth of microbes near the container. The most likely form of MIC involves sulphate-reducing bacteria (SRB). Electrochemical experiments using a clay-covered copper electrode have shown that sulphide ions produced by SRB could diffuse through buffer material and induce corrosion of the container. A method to predict the long-term corrosion behaviour is presented. (author)
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Aug 1996; 15 p; NATO advanced research workshop on microbial degradation processes in radioactive waste repository and in nuclear fuel storage areas; Budapest (Hungary); 9-12 May 1996; COG--96-274; 16 refs., 6 figs.
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Oscarson, D.W.; Dixon, D.A.; Onofrei, M.
Atomic Energy of Canada Ltd., Pinawa, Manitoba (Canada)1997
Atomic Energy of Canada Ltd., Pinawa, Manitoba (Canada)1997
AbstractAbstract
[en] In the Canadian concept for nuclear fuel waste management, both clay-based materials and concrete are proposed for use as barriers, seals or supporting structures. The main concern when clays and concrete are in proximity is the generation of a high-pH environment by concrete since clay minerals are relatively unstable at high pH. Here we examine the OH--generating capacity of two high-performance concretes when in contact with several solutions. We also investigate various aspects of claylconcrete interactions. They are: (1) the alkalimetric titration of clay suspensions, (2) the effect of Ca(OH)2 (portlandite) on the swelling and hydraulic properties of compacted bentonite, and (3) the influence of cement grout on a backfill clay retrieved from the 900-d Buffer/Container Experiment at the Underground Research Laboratory of AECL. The results indicate that although high-performance concretes establish significantly lower poresolution pH (9 to 10) than does ordinary portland cement, the pH is still somewhat higher than that of clay/groundwater systems of about pH 8. Hence, even if high-performance concrete is used in a disposal vault, the potential still exists for clay minerals to alter over long periods of time if in contact with this concrete. The data show, however, that clays have a substantial buffering capacity, and clay-based barriers can thus neutralize much of the OH- potentially released from concrete in a vault. Moreover, even after reacting for 120 d at 85oC with up to 5 wt.% Ca(OH)2, compacted bentonite (dry density = 1.2 Mg/m3 ) retains much of its swelling capacity and has a permeability low enough (hydraulic conductivity ≤ 10-11 m/s) to ensure that molecular diffusion will be the main transport mechanism through compacted clay-based barriers. Furthermore, according to X-ray diffractometry, the clay mineral component of backfill was not altered by contact with a cement grout for 900 d in the Buffer/Container Experiment
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Jan 1997; 39 p; COG--96-562-I; 53 refs., 16 tabs., 16 figs.
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Coleman, C.E.; Cheadle, B.A.
Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)1997
Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada)1997
AbstractAbstract
[en] The service life of CANDU fuel channels is determined by the component that has to withstand the most severe conditions, the Zr-2.5Nb pressure tube. The latest fuel channels are expected to have a lifetime of over 30 years. The properties that control service life are fracture and deformation. For fracture, a defence-in-depth approach is used - preventing crack initiation and invoking leak-before-break. Confidence in the serviceability of fuel channels is based on current knowledge of the state of health of the components evaluated by surveillance. Degradation of properties with service is slow, allowing sufficient time to judge and act when end-of-life is reached. Methods for improving the properties of components are outlined. (author)
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Jan 1997; 8 p; 5. International topical meeting on nuclear thermal hydraulics operations and safety (NUTHOS-5); Beijing (China); 13-16 Apr 1997; 8 refs., 2 tabs., 4 figs.
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Prins, R.; Marais, G.F.; Marais, A.S.; Pretorius, Z.A.; Janse, B.J.H.
Application of DNA based marker mutations for improvement of cereals and other sexually reproduced crop plants. Proceedings of a final research co-ordination meeting1998
Application of DNA based marker mutations for improvement of cereals and other sexually reproduced crop plants. Proceedings of a final research co-ordination meeting1998
AbstractAbstract
[en] Twenty-nine lines with deletions in the Lr19 ('Indis') translocated chromosome segment were used to physically map Thinopyrum Restriction Fragment Length Polymorphism (RFLP) loci as well as the Sr25 and Sdl loci. The relative distances between marker loci on the translocation were then calculated. The information was then used as an aid to characterize several recombined forms of the translocation. The data confirmed the reported homoeology between the Lr19 segment and chromosome arm 7DL of wheat. Also, it seems that the Lr19 translocation in 'Indis' is very similar to the Lr19 segment in the T4 source and that the former may not derive from Thinopyrum distichum. Near-isogenic lines of the recombined segments were derived and used to study their expression of leaf rust resistance. It became evident that only one potentially useful recombinant was obtained in an earlier attempt to induce allosyndetic pairing between the Lr19 translocation and 7DL of wheat. (author)
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Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna (Austria); 125 p; ISSN 1011-4289; ; Mar 1998; p. 97-102; Advisory group meeting on implementation of burnup credit in spent fuel management systems; Vienna (Austria); 20-24 Oct 1997; 14 refs, 2 tabs.
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Frampton, P.H.; Ng, D.; Kephart, T.W.; Yuan, T.C.
TRIUMF, Vancouver, BC (Canada)1992
TRIUMF, Vancouver, BC (Canada)1992
AbstractAbstract
[en] The lepton family number violation Z boson decay, Z → e-e-μ+μ+ or e+e+μ-μ-, mediated by a dilepton, e.g. from an SU(15) theory, is calculated. The branching ratio of such exotic decay for allowed dilepton masses is found to be smaller than 10-10. (author)
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Oct 1992; 4 p; TRI-PP--92-96; VAND-TH--92-13; NUHEP-TH--92-20; 6 refs., 2 figs.
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Evans, G.J.; Bekeris, P.A.
Proceedings of the third international conference on containment design and operation. v.11994
Proceedings of the third international conference on containment design and operation. v.11994
AbstractAbstract
[en] Containment structures of nuclear power plants have many inner surfaces coated with nuclear grade paints. These may provide a valuable sink for radioiodine and hence may aid to minimize its release to the environment following a possible accident. The objective of this on-going work is to identify and evaluate significant parameters involved in the sorption of iodine on painted surfaces and thereby develop a kinetic model. To date two paints have been studied, an inorganic zinc primer and a vinyl paint. Experiments were performed by passing 131I2 gas in air through 0.25 inch glass tubing coated on the inner surfaces with paint. Tubing was used to produce well characterized and rapid gas phase mass transfer. The accumulation of iodine on the surface was monitored continuously using two parallel scintillation detectors coupled to a PC based multi-channel analyzer. Test parameters such as temperature, humidity, flow-rate, and iodine concentration could be adjusted independently. The zinc primer demonstrated a high affinity for iodine. The rate of adsorption was found to increase at lower temperatures and higher humidifies. The adsorption rate was directly proportional to the gas phase iodine concentration indicating a first order process. Desorption occurred at a relatively constant rate at surface coverages below 10-6 mol I2/cm2. Iodine that desorbed from these surfaces was mostly in the chemical form of elemental iodine (I2). The vinyl paint showed a much lower affinity for iodine. Steady state adsorption was found to increase with increased gas phase iodine concentrations. Humidity had no observable effect on the rate of adsorption. Desorption rates were found to increase with increased temperature and it is suggested that the desorption process is first order with respect to surface iodine loading. (author). 7 refs., 3 tabs., 7 figs
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Canadian Nuclear Society, Toronto, ON (Canada); 560 p; ISBN 0-919784-39-0; ; 1994; (v.1) [14 p.]; 3. International conference on containment design and operation; Toronto, ON (Canada); 19-21 Oct 1994
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George, T.L.; Singh, A.
Proceedings of the third international conference on containment design and operation. v.11994
Proceedings of the third international conference on containment design and operation. v.11994
AbstractAbstract
[en] The GOTHIC computer program, under development at EPRI/NAI, is a general purpose thermal hydraulics computer program for design, licensing, safety and operating analysis of nuclear containments and other confinement buildings. The code solves a nine equation model for three dimensional multiphase flow with separate mass, momentum and energy equations for vapor, liquid and drop phases. The vapor phase can be a gas mixture of steam and non-condensing gases. The phase balance equations are coupled by mechanistic and empirical models for interface mass, energy and momentum transfer that cover the entire flow regime from bubbly flow to film/drop flow. A variety of heat transfer correlations are available to model the fluid coupling to active and passive solid conductors. This paper focuses on the application of GOTHIC to two separate effects tests; condensation heat transfer on a vertical flat plate with varying bulk velocity, steam concentration and temperature, and evaporative heat transfer from a hot pool to a dry (superheated) atmosphere. Comparisons with experimental data is included for both tests. Results show the validity of two condensation heat transfer correlations as incorporated into GOTHIC and the interfacial heat and mass transfer models for the range of the experimental test conditions. Comparisons are also made for lumped versus multidimensional modeling for buoyancy controlled flow with evaporative heat transfer. (author). 13 refs., 1 tab., 10 figs
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Canadian Nuclear Society, Toronto, ON (Canada); 560 p; ISBN 0-919784-39-0; ; 1994; (v.1) [14 p.]; 3. International conference on containment design and operation; Toronto, ON (Canada); 19-21 Oct 1994
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AbstractAbstract
[en] The third international conference on containment design and operation includes in volume 2 of the publication sessions on the following topics: structural analysis and response tests; passive safety systems; aerosol behaviour; containment reliability, integrity, and risk assessment; hydrogen deflagration and detonation. Due prominence was given to CANDU and other PHWR reactors. The individual papers have been abstracted separately
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1994; 580 p; 3. International conference on containment design and operation; Toronto, ON (Canada); 19-21 Oct 1994; ISBN 0-919784-39-0;
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Biswas, J.K.; Pendergast, D.R.
Proceedings of the third international conference on containment design and operation. v.21994
Proceedings of the third international conference on containment design and operation. v.21994
AbstractAbstract
No abstract available
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Canadian Nuclear Society, Toronto, ON (Canada); 580 p; ISBN 0-919784-39-0; ; 1994; (v.2) [1 p.]; 3. International conference on containment design and operation; Toronto, ON (Canada); 19-21 Oct 1994
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Kennedy, M.D.; Woodcock, J.; Gresham, J.A.
Proceedings of the third international conference on containment design and operation. v.21994
Proceedings of the third international conference on containment design and operation. v.21994
AbstractAbstract
[en] Westinghouse-GOTHIC is a thermal-hydraulics code well suited to analyzing passively cooled containments which depend on heat removal primarily through the containment shell. The code includes boundary layer heat and mass transfer correlations. A liquid film convective energy transport model has been added to the Westinghouse-GOTHIC code to account for the sensible heat change of the applied exterior water. The objective of this paper is to compare the code's predictions of the AP600 large scale test facility with and without the liquid film convective energy transport model. The predicted vessel pressure and integrated heat rate with and without the film convective energy transport model will be compared to the measured data. (author)
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Canadian Nuclear Society, Toronto, ON (Canada); 580 p; ISBN 0-919784-39-0; ; 1994; (v.2) [10 p.]; 3. International conference on containment design and operation; Toronto, ON (Canada); 19-21 Oct 1994; 12 refs., 3 tabs., 3 figs.
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