[en] Several recent theoretical studies have considered the problem of the probability of fast fracture in pressure vessels due to induced flaws. These studies assume all relevant quantities to be randomly distributed and independent, whereas service experience suggests that the presence of defects and inferior-toughness material may be correlated to some degree. The lack of statistical data on spatial distributions of material properties precludes a detailed analysis, but it is possible to develop simplified models to examine some aspects of the problem. In particular it is possible to devise an upper bound on the influence of correlation effects, making minimal use of statistical information. A lower bound on failure probability is given by the analysis based on completely randomly distributed properties. It can be shown that in some applications the effects of correlation are not significant, without necessarily knowing what correlation exists. In other instances the effect of correlation is to introduce a common-mode element which significantly increases the failure probability. (orig.)

[en] The C-E ALWR is an upgrade of the proven System 80 NSSS standard design and so is referred to as System 80+. Both plants are rated at 3817 Mwt, but System 80+ incorporates a number of modifications to the design. A best-estimate small break study addressed the economic concern of how large a break size can be tolerated without the two-phase fluid level falling below the top of the core. With a best-estimate analytical procedure and no single failure the core was shown to remain covered for breaks up to, and including, that of a 10 in. dia. break. A large break licensing analysis confirms that adequate reflood exists following the end of SIT discharge without a LPSI system

No abstract available

[en] The purpose of this research is to introduce the technical standard of accident sequence precursor (ASP) analysis, and to propose a case study using the dynamic-probabilistic safety assessment (D-PSA) approach. The D-PSA approach can aid in the determination of high-risk/low-frequency accident scenarios from all potential scenarios. It can also be used to investigate the dynamic interaction between the physical state and the actions of the operator in an accident situation for risk quantification. This approach lends significant potential for safety analysis. Furthermore, the D-PSA approach provides a more realistic risk assessment by minimizing assumptions used in the conventional PSA model so-called the static-PSA model, which are relatively static in comparison. We performed risk quantification of a steam generator tube rupture (SGTR) accident using the dynamic event tree (DET) methodology, which is the most widely used methodology in D-PSA. The risk quantification results of D-PSA and S-PSA are compared and evaluated. Suggestions and recommendations for using D-PSA are described in order to provide a technical perspective

[en] The books (2 volumes) on ''Life assessment of dynamically loaded materials and structure'', are the proceedings of the 5th European Conference on fracture, held in Portugal 1984. The conference concerned the current status of methods and theories dealing with the subject. The papers presented included the topics: crack initiation, welds and welded joints, fracture toughness and fatigue, manufacturing processes, stress intensity factors, elastoplastic fracture mechanics, and metallurgical aspects, applications, non-metallic and pm materials, creep, and testing techniques. Three papers were selected and indexed separately. (U.K.)

[en] This paper describes how the observed mechanical properties of ceramic surfaces after ion implantation are related to the structural changes occurring in the surface, and presents a number of criteria designed to enable prediction of the mechanical property modifications that will ensue after implantation of a given substrate with a given ion. These include the application of a bond-type criterion to determine the amorphisation dose (amorphisation critically affecting mechanical properties) and an elasticity criterion to determine the maximum likely implantation induced surface stress. (author)

[en] A portable barrier strip is described having retractable tire-puncture means for puncturing a vehicle tire. The tire-puncture means, such as spikes, have an armed position for puncturing a tire and a retracted position for not puncturing a tire. The strip comprises a plurality of barrier blocks having the tire-puncture means removably disposed in a shaft that is rotatably disposed in each barrier block. The shaft removably and pivotally interconnects the plurality of barrier blocks. Actuation cables cause the shaft to rotate the tire-puncture means to the armed position for puncturing a vehicle tire and to the retracted position for not puncturing the tire. Each tire-puncture means is received in a hollow-bed portion of its respective barrier block when in the retracted position. The barrier strip rests in its deployed position and substantially motionless as a tire rolls thereon and over. The strip is rolled up for retrieval, portability, and storage purposes, and extended and unrolled in its deployed position for use. 13 figs

[en] In this paper, the development of advanced analytical capabilities for the treatment of piping systems is reported. It is a three-dimensional structural-response analysis of piping systems that considers both the hoop and flexural stresses, including bending in both planes. The analysis is also coupled with modified fluid-flow algorithms that takes into account the three-dimensional motion of the piping systems. A three-dimensional uniform cross-section pipe element with eight degrees of freedom at each node is described. The degrees of freedom are: three displacements along three orthogonal directions, three rotations about the three axes (one torsional and two bending rotations), pipe shell hoop displacement and pipe shell bending rotation. Thus, hoop, flexural, axial, and torsional modes of response are considered in the element. (orig.)

[en] Analysis of the response of high energy lines after the occurence of pipe rupture has received considerable attention in recent past, with an array of different modelling techniques proposed and available in the literature. Information on relative merits of such methods is scarce and the present study provides tentative guidelines to the designer confronted with the selection of an appropriate model for a given system. The criteria of evaluation are, implicitly, the time required for analysis and the computer cost involved and, explicitly, the degree of accuracy of the solutions. The models compared are grouped into four classes: (i) one-degree-of-freedom-systems that introduce a stationary plastic hinge and require simple hand calculations, (ii) kinematic models incorporating the concept of a travelling hinge, easily analysed by means of inexpensive computer programs, (iii) engineering beam models considering elasto-plastic pipe behavior and (iv) two dimensional finite element systems based on plane stress theory. The kinematic model, proposed earlier by the authors, is used to conduct a qualitative analysis of the response as a function of the magnitude of external force, gap size and rigidity of the restraint. The engineering beam model gives results that practically coincide with those generated by the plane stress approach, although consistently a little higher than the latter. The methods were applied to typical configurations with bilinear restraints and the results obtained prove that the single-degree-of-freedom model may lead to non conservative solutions whereas the straight application of the kinematic model would always underestimate the maximum deformation of the restraint. (orig.)

No abstract available