[en] Development of ATRIUM fuel elements for boiling water reactors. In addition to the fuel element types 9x9-9Q and 9x9-9QA an ATRIUM fuel element with a 10x10 rod configuration has been developed. An 11x11 variant is ripe for commercialization. Current examples of ATRIUM fuel elements which illustrate the internal water channel position, load discharge through the water channel, the TURBO spacer, the corner-reinforced fuel assembly box as well as the LTP cladding materials are described. (DG)

[en] A method is described of immobilizing cadmium and lead in a dry solid residue obtained from the burning of solid wastes. The method comprises mixing the residue with an amount sufficient to reduce the leaching of cadmium to a level less than about 1 ppm and of lead to a level less than about 5 ppm of approximately equi-molar proportions of lime and an aqueous solution of a soluble inorganic salt supplying sulfide

[en] By the end of 1990 Siemens had performed fuel element designs and in-core fuel management for 94 operating cycles in 27 pressurized and boiling water reactors of other manufacturers. Together with the client different fuel element designs are developed and proof is furnished of the reactor physics compatibility of different fuel elements from various producers, and of plant safety. (DG)

[en] Developments of the Siemens on the creation of improved fuel assemblies for the PWR and BWR types reactors are presented. Carefully designed fuel assemblies of the high burnup provide a way of decreasing costs of nuclear fuel cycle, improvement of using nuclear fuel, increasing reliability of assemblies when being in reactor. Comprehensive description of the FOCUS X5 and HTP X5 fuel assemblies making possible to achieve of the burnup to 70 MW day/kg as well as fuel assemblies of the ATRIUM 10 type is given

[en] Fuel cycle costs are an important key factor in order to achieve reduced power generation costs for the nuclear energy. A particularly effective contribution for reduction of costs is the increase of the burn-ups. It places high requirements to the fuel assemblies. Carefully developed high burn-up fuel elements of Siemens achieve today in pressurized water reactors and in boiling water reactors of different manufacturers outstanding operating results, further burn-up increases are in preparation. Siemens has profound high burn-up operational experience. The application experience od Siemens covers at present altogether 77,000 fuel elements with 9,9 million fuel rods, which were used world-wide at 55 PWR and 49 BWR. Of it 276 PWR and 28 SWR fuel assemblies reached burn-ups over 50 MWd/kgU. The maximum achieved fuel assembly burn-ups are at present 65 MWd/kgU for PWR and about 63 MWd/kgU for BWR. The new generation of Siemens PWR fuel assemblies FOCUS X5 and HTP X5 and the BWR fuel assembly ATRIUM 10 are designed for enrichments up to 5% U235 corresponding thereby to fuel assembly burn-ups up to 7= MWd/kg maintaining high reliability and the excellent operational behaviour. The bundling of the Knowledge and the creativity of experts of neutron physics, thermal hydraulics and structure mechanics as well as continuous expansion of design and material experiences ensure the development of advanced and reliable fuel elements for PWR and BWR. The application in different reactor types and the large fuel assembly variety enables itself flexible solutions. Thereby substantial cost reduction potentials are opened to the utilities. This potentials can be opened with the modern design methods by Siemens, first licenses for high enrichments have been already given. (Author)

[en] Siemens has collected approximately 30 years of experience in design and delivery of mixed oxide fuel assemblies. Advanced MOX fuel assemblies for both pressurized and boiling water reactors have design burnups equivalent to today's uranium fuel assemblies. Tails uranium, as carrier material and lower plutonium quality, is considered. To date, Siemens has delivered MOX fuel assemblies containing more than 200 tons of heavy metal. This quantity is projected to increase to about 500 tons by the year 2004 involving MOX-specific manufacturing services from supsuppliers in Belgium, France and the United Kingdom. (Author)

[en] A new precipitation method is proposed in which sulphuric acid is added to the eluate such that the resulting pH is 2.7 to 3. 10 to 12 g/l nitric acid is then added and the solution is neutralized with ammonia gas. A part of the ammonium diuranate suspension formed is thickened and returned to the stage of HNO₃ addition. The eluate thus obtained is again precipitated. The method allows obtaining a precipitate showing better sedimentation and filtration properties while the resulting filtrate has a reduced water content. (M.S.)

[en] In this paper author describes new system (PTK SVRK) for in-core monitoring system of the Mochovce nuclear power plant installed instead of the HINDUKUSH in-core monitoring system, which are determined to monitor the core parameters. This system (HINDUKUSH), supplied by the Russian party in scope of the original design, became old during the idle time, and the components, which is it built from, are not produced any more. Thus, its utilisation had to undergo a technical end economic analysis. It resulted in classification to the work complex of the technical specification of safety measures. Its implementation conditioned the commissioning of the power plant nuclear unit. The program and technical system of the in-core monitoring (PTK SVRK) consists of two levels - a 'closed' basic, which fulfils the task of the primal system operation for the Unit operators, and an 'open' top level, which serves as a tool for the additional tasks of a prognosis, monitoring, and analysis of the processes taking place in the nuclear core by the monitoring physicists. The basic level of PTK SVRK has 100% redundancy because of its composition and configuration. It is namely formed by two identical, equivalent, and independent sets. Any of them may be operational or redundant. Every set consists of an apparatus processing the signals coming from the technology or the calculation complex, which converts these signals to physical parameters and controls the physically mathematical model of the monitored equipment. The results are presented to the operational staff as outputs on the workstations in the control room in a form of cartograms, graphs, histograms, tables, etc. The bases of the system calculation model are time-proven programs BIPR7 and PERMAK, which are used also in this power plant. The top level of PTK SVRK has a structure supporting the system openness for its further utilisation. Today it is formed by a server and two workstations. Besides the above-mentioned tasks, the filing functions of the operational and system data, the communications of PTK SVRK with other informational and technological systems of the unit, as well as the functions of control and monitoring of the system itself and its devices are concentrated here. (author)

[en] Starting with the licensing requirements, the MOX fuel elements as designed for PWR and BWR type reactors are described and their use in reactors is illustrated. Another chapter deals with the state of fuel recycling. The main operational experiences are discussed. (orig./DG)

[en] Short communication