[en] For emergency cooling of the PWR, a compact water jet is introduced into the upper part of the pressure vessel and is there spread by baffle plates. It provides about 1/4 of the quantity of water for energency cooling. It is introduced via the hot coolant pipes. The remainder of the emergency coolant is introduced by the cold cooland pipes in the lower part of the pressure vessel. (DG)

[en] This invention concerns a recirculation sump for the safety and spraying injection systems of a nuclear reactor, specifically for making up safety devices for a pressurized water nuclear reactor

[en] The French PWR type reactor unit CHOOZ A, a 300 MW plant built 25 years ago, was the first in the construction programme which meanwhile covers 34 reactors of 900 MW, 20 reactors of 1300 MW, and 2 reactors of 1400 MW rated capacity, some of them not yet installed but at least ordered. The framework concept of this construction programme is set out, starting with the first licence obtained from Westinghouse, and reviewing the subsequent French development activities to date. The significant features of the various design types are explained, together with special aspects of the French nuclear programme in fields such as reactor safety, radiation protection, and adjustment to the requirements of the integrated grid. (orig./DG)

[en] A simulation study of a station black-out ATWS has been performed by applying Response Surface Methodology (RSM) on the data obtained by inspecting the ALMOD code. The case under study has shown that the a priori information which alone could be inadequate, is optimally utilized if coupled with a preliminary sensitivity analysis through RSM techniques. In particular the engineering selection of the model variables and the rank order of the remaining ones had to be modified after an RSM preliminary sensitivity analysis. Another qualifying feature of the exercise is the use of the randomization of the variables not included in the model in order to coherently exploit the methodology in its full efficiency. This procedure is able to give a figure of merit of the global importance of the neglected variables through the analysis of residuals. Results show that the proposed technique is an effective tool for selecting the most important accident variables and that the body of information gained is significant with respect to the number of observations performed. (orig.)

[en] The invention relates to a new emergency cooling system and applies in particular to pressurized water power stations. It can work independently and in closed circuit for most of the cooling. This result is achieved by condensing some of the steam produced in an air condenser of which the operating energy is provided by another part of the steam, and the condensed water is recycled towards the emergency reserve

[en] The subject of this invention is a pressurization system with an intermediate reserve thereby enabling the pressure of the coolant of a PWR to be maintained at a significantly constant level, in a given time interval, by reducing in particular the effect of thermal cyclyings and by doing away with the triggered electro-valve. The first containment or 'pressurizer' includes a shower system at its upper part and a first heating system. A second containment or 'intermediate reserve' at intermediate temperature includes a second heating system. A pipe connects the bottom of the reserve with the vessel. A second one way pipe allows the liquid to pass from the bottom of the pressurizer to the top of the reserve and a third one-way pipe passes the liquid from the top of the reserve to the shower system

[en] A water cooled nuclear reactor is described which comprises a reactor core, a primary water coolant circuit and a pressuriser arranged as an integral unit in a pressure vessel. The pressure vessel is divided into an upper and a lower chamber by a casing. The reactor core and primary water coolant circuit are arranged in the lower chamber and the pressuriser is arranged in the upper chamber. A plurality of spray pipes interconnect a steam space of the pressuriser with the downcomer of the primary water coolant circuit below a heat exchanger. A plurality of surge ports interconnect a water space of the pressuriser with the primary water coolant circuit. The surge ports have hydraulic diodes so that there is a low flow resistance for water from the water space of the pressuriser to the primary water coolant circuit and high flow resistance in the opposite direction. The spray pipes provide a desuperheating spray of cooled water into the pressuriser during positive volume surges of the primary water coolant. The pressuriser arrangement may also be applied to integral water cooled reactors with separate pressurisers and to dispersed pressurised water reactors. The surge ports also allow water to flow by gravity to the core in an emergency. (author)

[en] Nuclear Power International (NPI), a joint subsidiary of Framatome and Siemens was established in April 1989 to coordinate the development and marketing of a common PWR technology for the world market. Both parent companies command well proven PWR technology and can rely on experience gained with over 100 000MWe of nuclear capacity in operation, under construction or on order. The technology from each is being offered through NPI until the joint PWR technology which is under development, becomes available. NPI's experience to date is reviewed. (author)

[en] In this article are reviewed the equipment used for data processing by local computer and main applications in documentation management, maintenance, daily dosimetry, monitoring, neutronic and thermics computation, material, effluents etc..

[en] Improved containment design concepts for future PWRs are being investigated in response to a recent amendment to the German Atomic Energy Act. This requires elimination of the need for off-site emergency measures in the event of a severe accident. Some of the design concepts are briefly described. These include a core catcher design to provide ex-vessel core melt cooling in a meltdown accident. Taking into account theoretical and experimental investigations on the short-term load associated with energetic hydrogen combustion processes, a novel ''composite'' containment has been proposed for a PWR with an integral core-catcher and reinforced pressure vessel support structure. In the event of accidental pressurization of the containment the load would be distributed over a strong inner steel shell and an outer reinforced concrete wall. The annulus between the two would act as a chimney for after-heat removal from the primary containment shell using filtered natural air convection flow. (UK)