[en] Originally the main purpose of the countries planning commercial reprocessing activities, has been obtaining plutonium for the initial loads of fast breeder reactors. Because fast breeder programmes have been delayed, there will be plutonium over the need of these programmes. As a consequence interest has arisen to recycle pluonium in LWRs. In this way, the need for storing plutonium could be avoided. Theoretical and experimental studies have shown that plutonium is technically speaking suitable fuel (mixed oxide fuel, mox) for LWRs. Moreover, the different phases of mox-fuel cycle have been tested in practice in several countries, for example in West Germany. By recycling plutonium and uranium acquired from reprocessing 30-40% of the natural uranium need can be covered. In this article a brief survey of using mox in a LWR has been presented including fabrication aspects and the future outlook of using mox in different countries

[en] NUFCOS is a multigoal nuclear fuel cycle optimization code with an arbitrary number of decision objectives. The multigoal decision-making is based on the evolving techniques of fuzzy optimization. After a short description of the fuel cycle model and the calculation methods this report gives the input instructions in the case of three optimization criteria: minimization of fuel cycle costs, economical risk and nuclear weapons proliferation risk. (author)

[en] Site investigations for the spent fuel repository in Finland are under way at three sites. One of them is near the Olkiluoto nuclear power plant at the coast of the Baltic sea. The two other investigation sites are inland. The site of the repository shall be selected by the end of 2000. The aim of the site-specific safety analyses is to scrutinize whether the updated canister and repository designs with site-specific repository layouts fulfil the safety requirements, and to evaluate whether there are any significant differences in the post-closure performance of the planned repositories at the three sites. The paper includes preliminary results from the interim report on safety analysis (TILA-96) to be published at the end of 1996. (author)

[en] Teollisuuden Voima Oy (TVO) is responsible for the management of spent fuel produced by the Olkiluoto power plant. TVO's current programme of spent fuel management is based on the guidelines and time schedule set by the Finnish Government. TVO has studied a final disposal concept in which the spent fuel bundles are encapsulated in copper canisters and emplaced in Finnish bedrock. According to the plan the final repository for spent fuel will be in operation by 2020. TVO's updated technical plans for the disposal of spent fuel together with a performance analysis (TVO-92) were submitted to the authorities in 1992. The paper describes the design principle of TVO's final repository and preliminary adaptation of the repository to site specific conditions. (author). 10 refs., 5 figs

[en] The excavation damaged rock zone (EDZ) adjacent to the surface of deposition holes in a nuclear waste repository has been considered to be a potential pathway for the flow of water and the migration of radionuclides diffusing out of a waste canister via the bentonite barrier. The properties of the excavation-damaged rock zone adjacent to the surface of experimental deposition holes in the Research Tunnel at Olkiluoto on the southwest coast of Finland have been measured and are used in this study to evaluate the effect of the excavation damaged rock zone on the transport of radionuclides escaping from a waste canister. Since the hydraulic conductivity of compacted bentonite is low, the predominant mode of migration of nuclides through such material will be diffusion. The effect of the excavation-damaged rock zone on the transport of radionuclides was analyzed by comparing two different cases: 1) diffusion through the bentonite and 2) transport through the excavation damaged rock zone by the processes of advection and diffusion. According to this study, hydraulic gradients three orders of magnitude higher than those estimated to currently exist would be required to achieve the transfer of significant quantities of non-sorbing neutral nuclides through the excavation-damaged rock zone. According to this evaluation, the excavation damaged rock zone is unlikely to be a significant migration route in normal cases in the absence of large hydraulic gradients. Copyright (2001) Material Research Society

[en] It has been suggested that a huge lake, Lago Amazonas, covered a large part of the Amazon basin until as recently as two thousand years ago. According to this hypothesis, the topmost sediments in western Amazonia are almost universally young deposit of lacustrine and deltaic origin. The hypothesis has gained some attention among biologists because of its implications for biological phenomena in Amazonia, especially bio geography and bio diversity. According to the available geological data, however, Amazonia is geologically far more complex than assumed by the lake hypothesis. This paper discussed the weaknesses of the Lago Amazonas hypothesis, and indicate alternative explanations of the surface geology that are based on tectonically controlled fluvial deposition. Some aspects of radiocarbon dating method are also presented. (author)

[en] The design basis, dimensioning and some manufacturing aspects of the Advanced Cold Process Canister (ACPC) for the nuclear waste disposal is summarized in the report. The strength of the canister has been evaluated in normal design load condition and in extreme high hydrostatic pressure load condition possibly caused by ice age (orig.)

[en] In Finland, the spent nuclear fuel will be emplaced in the bedrock at a target depth interval of 400-500 metres. Posiva Oy is the company responsible for high active nuclear waste management in Finland. Currently, an ONKALO URL (Underground Research Laboratory) has been under excavation since summer 2004 at the selected final disposal site. Construction of the actual final disposal facility will begin in early 2010's and the facility shall be operational in 2020. According to the present plans, the final disposal will be implemented in a way that fuel bundles as a whole will be sealed in canisters that are made of nodular cast iron, enclosed in a corrosion resistant, 50 mm thick copper shell. The canisters will be emplaced in holes drilled at the bottom of the tunnels excavated in the bedrock. The canisters are surrounded with compacted bentonite clay. Deep repository prevents unintentional human intrusion into the final disposal facility. The disposal facility is described in more detail by Tanskanen and Palmu (2003). The Finnish concept is nearly similar to the Swedish concept introduced by Swedish Nuclear Fuel and Waste Management Co (SKB). Posiva and SKB are in close co-operation in developing of the concept and technology. (authors)

[en] The work in the ESDRED In te grated Project Module 4, Temporary Sealing (using low pH cement) Technology, consisted first of designing a low pH cement formulation and then of preparing several concrete designs suitable for the construction of sealing plugs and for rock support using shot crete techniques. Regarding sealing plugs, a short plug was constructed at Aspo in Sweden and it was very quickly loaded to failure i.e. slippage by applying water pressure to one face. A second, full scale plug was subsequently constructed at Grimsel test site in Switzerland. It was loaded using the swelling pressure created by bentonite blocks which were artificially hydrated. At time of writing the targeted pressure on the plug was not reached. As the saturation of the bentonite is taking longer than expected the partners involved agreed to continue with the saturation of the bentonite blocks and the related data monitoring beyond the ESDRED Project. The studies on low-pH shot crete for rock sup port were based on available recipes of low-pH concrete mixtures for use in a repository. Pilot and full scale tests were carried out in Sweden and in Switzerland. (Author) 5 refs

[en] Conventionally, the effect of measurements on a quantum system is assumed to introduce decoherence, which renders the system classical-like. We consider here a microscopic meter, that is, an auxiliary essentially quantum system whose state is measured repeatedly, and show that it can be employed to induce transitions from classical states into inherently quantumlike states. The meter state is assumed to be lost in the environment and we derive a non-Markovian master equation for the dynamic system in the case of nondemolition coupling to the meter; this equation can be cast in the form of an (N_a)th-order differential equation in time, where N_a is the dimension of the meter basis. We apply the approach to a harmonic oscillator coupled to a spin-(1/2) meter and demonstrate how it can be used to engineer effective Hamiltonian evolution, subject to decoherence induced by the projective meter measurements