[en] This paper provides an overview of the approaches used and results obtained to this date within the Swiss Project GaBE on ''Comprehensive Assessment of Energy Systems''. Based on the ''cradle to grave'' approach detailed environmental inventories for major fuel cycles have been generated. In comparison to earlier studies a very broad spectrum of resources and air and water pollutants has been covered. Also non-energetic resources such as land depreciation have been considered. Numerous examples of evaluations are provided in the paper, including comparisons of greenhouse gas emissions, land use, radiation and wastes, and illustrating the impact of consideration of full energy chains. In the part concerning severe accidents some evaluations based on the database established as the Paul Scherrer Institute are presented as well as the estimated contribution of hypothetical severe accidents to the external costs associated with a specific Swiss nuclear power plant. Results of applications of the large scale energy-economy model MARKAL to the Swiss energy system and greenhouse gas scenarios are described. This includes cost-optimal contributions of different technologies to reduce CO₂ emissions, and trade-offs on the national and international level. Finally, the content of other GaBE activities either being in progress or planned is provided. (orig.)

[en] The two-region rewetting model of a slab with a constant 'wet' side heat transfer coefficient and a zero 'dry' side one, is solved by the Wiener-Hopf technique (Jones's direct method) and by separation of variables. The Wiener-Hopf technique yields a solution for the rewetting temperature which is simple in form and more accurate than that obtained by separation of variables, especially for high Biot numbers. The two solutions are found to be in good agreement with each other and with those of Coney (1974) and Caflisch and Keller (1981). Accurate results for the rewetting temperature are presented for a wide range of Biot and Peclet numbers. (orig.)

[en] Some aspects concerning analytical models for the rewetting of hot surface are discussed. These include the problems with applying various forms of boundary conditions, compatibility of boundary conditions with the physics of the rewetting problems, recent analytical models, the use of the separation of variables method versus the Wiener-Hopf technique, and the use of transformations. The report includes an updated list of rewetting models as well as benchmark solutions in tabular form for several models. It should be emphasized that this report is not meant to cover the topic of rewetting models. It merely discusses some points which are less commonly referred to in the literature. 93 refs., 3 figs., 22 tabs

[en] An analysis of the experimental results and post-test calculations using RELAP5/MOD2 carried out for OECD-LOFT small break experiment LP-SB-3 are presented. Experiment LP-SB-3 was conducted on March 5, 1984 in Loss-of-Fluid Test (LOFT) facility located at the Idaho National Engineering Laboratory (INEL). The experiment simulated a small cold leg break, with concurrent loss of high pressure injection system, and cooldown and recovery by feed and bleed of the steam generator secondary side and accumulator injection, respectively. The analysis was under taken as a part of a program at EIR aimed at developing experience in using the latest generation of best estimate Loss of Coolant Accident (LOCA) analysis computer codes, and to improve understanding of Small Break LOCA transients and as well as a part of a program aimed at assessing the RELAP5/MOD2 code. The latest available version (Cycle 33 to 36.1) of the code was used. The particular test selected for the analysis included several phenomena potentially relevant to any PWR plant operation in Switzerland. This report documents a short post-test analysis of the experiment emphasizing the results of additional analysis performed during the course of this task. RELAP5/MOD2 input model and results of the post-test calculation are documented. Included in the report are the results of a sensitivity analysis which show the predicted thermal-hydraulic response to a different input model. 7 refs., 55 figs., 2 tabs

[en] The Dua and Tien (1976) model for the rewetting of a slab with precursory cooling is solved exactly by separation of variables. The solution for the rewetting velocity is found to agree very well with a Wiener-Hopf technique solution to this model by the author. Rewetting rates predicted by the approximate solution of Dua and Tien are found to agree with the present solution for small Peclet numbers, while underpredicting them for large Peclet numbers. Theoretical quench front velocities compare favorably with experimental data for copper quenched by liquid nitrogen. Precursory cooling is shown to be able to greatly increase the rewetting velocity, in particular for cases of high flow rates, while negelecting it in modelling may result in much too low quench velocities, as compared to experimental measurements. (orig.)

[en] Published in summary form only

[en] This article provides some reflections on future developments of Probabilistic Safety Assessment (PSA) in view of the present state of the art and evaluates current trends in the use of PSA for safety management. The main emphasis is on Level 1 PSA, although Level 2 aspects are also highlighted to some extent. As a starting point, the role of PSA is outlined from a historical perspective, demonstrating the rapid expansion of the uses of PSA. In this context the wide spectrum of PSA applications and the associated benefits to the users are in focus. It should be kept in mind, however, that PSA, in spite of its merits, is not a self-standing safety tool. It complements deterministic analysis and thus improves understanding and facilitating prioritization of safety issues. Significant progress in handling PSA limitations - such as reliability data, common-cause failures, human interactions, external events, accident progression, containment performance, and source-term issues - is described. This forms a background for expected future developments of PSA. Among the most important issues on the agenda for the future are PSA scope extensions, methodological improvements and computer code advancements, and full exploitation of the potential benefits of applications to operational safety management. Many PSA uses, if properly exercised, lead to safety improvements as well as major burden reductions. The article provides, in addition, International Atomic Energy Agency (IAEA) perspective on the topics covered, as reflected in the current PSA programs of the agency. 74 refs., 6 figs., 1 tab

No abstract available

[en] Particle tracking simulation studies of the beam-beam interaction (BBI) in circular colliders require large amounts of CPU time to determine particle distributions out to large amplitudes. This is due to the limited number of superparticles simulated and the rarity of correlated events which can drive a particle to such amplitudes. An alternative approach for determining the final particle distribution out to large amplitudes is explored. The method employs a combination of particle tracking over selected regions of the amplitude space followed by the solution for the equilibrium distribution of the particle flow through this space. The technique is described and preliminary results, when applied to the two-dimensional case are given

[en] The Swiss results on carbon dioxide control raise the question of how closely each individual country can be expected to comply with targets for global uniform reductions in greenhouse gases. Using almost hydroenergy and nuclear energy for electricity generation and very little coal for the end-use markets, Switzerland will find further reductions of CO₂ extraordinary difficult and expensive. The Swiss study concludes that the country can at best contribute to the goal of global warming if it also credited with reductions of CFCs and other greenhouse gases. On the other hand, the review of different international studies enhances the conclusion that a combination of carbon taxes on the national level together with a market of tradeable emission permits on the international level, is a favorable police towards climatic sustainability. (author) 3 figs., 3 tabs., 7 refs