No abstract available

[en] The fuel element with circular cross-section for BWR and PWR consists of a core surrounded by a compound jacket container where there is a gap between the core and jacket during operation in the reactor. The core consists of U, Pu, Th compounds and mixtures of these. The compound jacket consists of zircaloy 2 or 4. In order to for example prevent the corrosion of the compound jacket, its inner surface has a metal barrier with smaller neutron absorbers than the jacket material in the form of a zirconium sponge. The zirconium of this metal barrier has impurities of various elements in the order of magnitude of 1000 to 5000 ppm. The oxygen content is in the range of 200 to 1200 ppm and the thickness of the metal barrier is 1-30% of the thickness of the jacket. (DG)

[en] Load relaxation rests were performed on Zircaloy-2 and Zircaloy-4 sheets with varied textures and microstructures. Experimental data in the form of logarithmic stress versus logarithmic strain rate curves showed characteristics which can be used to identify the deformation mechanisms involved. The low flow stress and the absence of grain boundary sliding at temperatures below 350⁰C found in the 0⁰ texture Zircaloy-4 make it potentially useful as a material for fuel element cladding. (orig.)

[en] Process of calibration and deep centring of blanks before broaching is developed and studied. Investigations are performed at a semi-industrial screw rolling mill MISiS-100 T. Blanks made of 40Kh, 60, 50, 45KhN2MFA, 30KhGSNA steels 80, 85, and 90 mm in diameter and 300 mm long were calibrated and centered after heating in a furnace to a depth of 200 mm at shafts and faces with different calibration. 30KhN2MFA steel is chosen for face material; heat treatment is conducted under the following conditions: heating up to 950-1000 deg C and hold-up during 30-35 min with the following cooling in the air. The above experimental investigations reveal that the process of calibration and deep centring accomplished at a three-shaft screw rolling mill is rather stable and provides a high accuracy of centering hollow marking

[en] Electron microprobe studies on solute distribution in oxide layers and in the regions near oxide metal interface have been carried out in the case of zircaloy-2 and zirconium binary alloys containing niobium, tin, iron, copper, chromium and nickel and oxidised in steam at 550 deg C. In the case of alloys having higher oxidation rates, the oxide of solute element was found to dissolve in ZrO₂ without any composition variation. However, for solute addition with limited solubility like Cr, Cu and Fe, solute enrichment at metal/oxide interface and depletion of the same matrix has been observed. The intensity profiles for nickel distribution were also found to be identical to Fe or Cr distribution. The mode of solute distribution has been discussed in relation to oxidation behaviour of these alloys. (author)

[en] The influence of crystallographic anisotropy on the mechanical properties of Zircaloy-2 was investigated as a function of stress state and plastic strain at 273 and 623 K. Zircaloy-2 plates were tested in the cold worked, stress relieved condition. Crystallographic textures were quantitatively characterized by the Kearns texture number, f, and plotted on direct and inverse pole figures. Uniaxial tension, compression, and plane strain compression tests were performed on 1.27 cm thick plates of Zircaloy-2 having two markedly differential initial crystallographic textures. The test data was used to construct monotonic yield loci as a function of texture and plastic strain. The complex shapes of the different yield loci indicate a strong anisotropic mechanical behavior in the low plastic strain range at room temperature. The uniaxial flow stresses were found to be a unique function of the texture number, f. The mechanical behavior of Zircaloy-2 is a strong function of the controlling deformation mechanisms and of the texture derived constraint. These deformation mechanisms include prism slip, < c + a> slip and twinning. Plastic deformation was found to cause significant texture rotation after as little as 1.5% plastic strain. The severest texture rotation occurs with [10anti 12] twinning which gives an 85⁰ rotation of the c axis. Measurements of the transverse plastic strain ratio R as a function of plastic strain were correlated with the texture number, f, and flow stress measurements. A marked strength differential effect was observed when the stress axis is parallel to a direction of high basal pole density. (orig.)

[en] Zirconium alloys used in the LWR industry crystallize in the hexagonal crystal structure below approximately 1136 K and many of the fabrication steps are performed below this temperature. The hexagonal structure possesses a limited number of slip systems and normal deformation processes result in extensive twinning. The twinning process results in the development of a fabrication texture, the type and extent of which is a function of the strain path used in the fabrication process. The texture which develops is important for two reasons. First, the texture at a given point in the fabrication process will determine the ease with which the next strain increment may be taken. Second, the texture of the completed part will have a significant effect on its in service performance because properties such as yield strength, creep strength, and fatigue and stress corrosion cracking resistance are a strong function of texture. Currently there is little data available concerning the evolution of textures as a function of strain path during the fabrication process of Zircaloy. Consequently this experimental investigation was conducted to determine the effect of textures on the mechanical behaviour of Zircaloy-2 with a primary emphasis on the evolution of texture during plastic deformation. (author)

[en] Internally pressurized tubes of Zircaloy-2 and Zr-2.5 wt% Nb were irradiated in a fast neutron flux of 1.75 x 10¹⁷ n(m².s) at about 330 K for up to 27 000 h. Periodic measurements of diameters and lengths have shown that strain rates are still changing after 27 000 h and that the ratio of transverse to axial strains is consistent with that calculated from the crystallographic texture. Annealed Zircaloy-2 showed smaller strains than either cold worked Zircaloy-2 or cold worked Zr-2.5 wt% Nb at equivalent stresses. (orig.)

No abstract available

[en] The main points from the papers presented at the ASTM Symposium held in Quebec City, August 1976 are summarized under the following topical headings: cladding behaviour in loss-of-coolant accident; oxidation in high temperature transient conditions; corrosion in normal reactor operation; irradiation effects on creep and deformation; mechanical properties; fracture related phenomena; and stress corrosion. (U.K.)