Abstract:
A method and a system for catalytic recombination of hydrogen, which is carried in a gas flow, with oxygen, has the gas flow passed through a reaction zone with a number of catalytic converter elements, with steam being added to the gas flow before it enters the reaction zone. The method and system ensure a particularly high operational reliability of the recombination device, even in varying operating conditions or with varying operating methods, in particular with regard to a hydrogen feed, which is provided as required, in the steam/feed water circuit of the installation. For this purpose, the feed rate of the steam to be added is adjusted in dependence on a measured value which is characteristic of a current actual temperature in the reaction zone.
Abstract:
A safety system for a nuclear plant includes a plurality of catalytic recombiner elements each triggering a recombination reaction with oxygen when hydrogen is entrained in an onflowing gas flow, so that reliable elimination of the hydrogen from the gas mixture is ensured with an especially high degree of operational safety even based on comparatively extreme conditions or scenarios of the aforementioned type. The recombiner elements and/or the flow paths each connecting two recombiner elements on the gas side are configured in such a way that a pressure pulse triggered in the gas medium by an ignition during the recombination reaction in a first recombiner element triggers a gas displacement process having a flow rate of at least 5 m/s in the onflow region of a second, adjacent recombiner element. A nuclear plant with a safety system is also provided.
Abstract:
A recombination device (1, 1′) for catalytically recombining hydrogen and/or carbon monoxide with oxygen in a gaseous mixture comprises at least one catalyst system (2) in which a housing (4) is mounted through which the gaseous mixture can flow in free convection in the operational phase. According to the invention, said catalyst system (2) is provided with a plurality of sub-areas (T1, T2) in the direction of flow. A first sub-area (T1) comprises in the incoming direction a catalyst body (6) with a surrounding throttle layer (8) for inhibiting the diffusion of the incoming and/or discharged reaction gases. A second sub-area (T2) that adjoins the first sub-area (T1) comprises at least one catalyst body (6) that is directly accessible by the reaction gases.
Abstract:
A process for obtaining a sample from an atmosphere in a closed gastight vessel, preferably from a reactor safety vessel of a nuclear power station, includes passing a sample through a venturi nozzle immediately upon entry of the sample into a sample-taking container in a vessel. The sample is mixed in the venturi nozzle with a transport fluid serving as a washing liquid. Gaseous constituents of the sample being soluble and/or condensable in the washing liquid are subsequently discharged together with the washing liquid from the sample-taking container and from the vessel by triggering a pressure reduction. A device for obtaining samples from an atmosphere in a closed gastight vessel, preferably from a reactor safety vessel of a nuclear power station, includes a sample-taking container having a bottom and a given volume. A washing liquid is disposed in the sample-taking container and has a volume being at most approximately equal to half of the given volume. A venturi nozzle dips into the washing liquid in the sample-taking container above the bottom. An inlet channel leads into the sample-taking container below the venturi nozzle.
Abstract:
A method and apparatus for pressure relief of a nuclear power plant includes the feeding of fluid from an outlet opening of a containment through a filter to a stack. The filter is operated with sliding pressure regulated as a function of the pressure in the containment.
Abstract:
A sampling system for taking a sample from the atmosphere in a reactor containment of a nuclear plant, includes a sampling line which is connected to a vacuum system and to an analysis system. The sampling line opens into the reactor containment and has a restriction device connected upstream thereof on the gas side for connection to the atmosphere in the reactor containment. A method for taking such a sample is also provided.
Abstract:
A nuclear engineering plant has a containment, whose interior chamber is subdivided by a wall into a systems chamber and an operating chamber which is accessible during normal operation. The containment ensures a particularly high operational reliability, in particular also in incident situations, in which hydrogen is released in the systems chamber. For this purpose, a number of overflow openings are provided in the partition wall, the respective overflow opening is closed by a closure element of a closure apparatus which opens automatically when a trigger condition associated with the respective overflow opening is reached. Closure apparatuses are provided which open both as a function of pressure and independently of pressure. The closure apparatus furthermore has a closure element containing a bursting film or a bursting diaphragm. The closure apparatus is configured such that it frees the overflow opening automatically when a predetermined environment-side trigger temperature is reached.
Abstract:
In a method for catalytic oxidation of a gas, the outlay required is kept at a low level for reliably treating even relatively large quantities of gas and/or high concentrations of the gas fraction that needs to be treated. For this purpose, a gas stream including the gas being treated is circulated through a reaction zone and a return-flow zone, which is in communication with the inlet and outlet sides of the reaction zone. The circulation of the gas stream can be maintained effectively in the form of a passive system if the gas stream which includes the gas to be treated is guided in the upward direction in the reaction zone and the upward flow is assisted by convection resulting from the heat released during the oxidation reaction. Furthermore, the gas stream is preferably cooled locally in the return-flow zone by spray cooling.
Abstract:
A nuclear installation has a reactor containment which is connected to a pressure relief line. A Venturi scrubber, which is arranged in a vessel containing a washing liquid, and a throttle device are connected in series in the pressure relief line. The novel system restrains, with particularly high reliability, fine air-transported activities or aerosols during decompression such that release thereof into the environment is practically impossible. The Venturi scrubber and the throttle device are dimensioned in such a way that, in the case of a critical drop in pressure of an air-vapor mixture flowing in the decompression line, a flow speed of said air-vapor mixture of more than 150 m/s, preferably more than 200 m/s, can be adjusted with respect to the throttle device in the Venturi scrubber.
Abstract:
A hydrogen/oxygen reaction is initiated in a catalytic recombination or ignition device. The device has one or more catalyst bodies with a predetermined catalytic surface. Only a small portion of the entire available catalytic surface, preferably less than 5% of the surface, is permanently maintained at a temperature level above ambient temperature. The temperature is raised by introducing energy with a heater. The heated surface portion acts as an initial igniter.