Design considerations shutdown

The reactor and steam generator internals important to acoustic and flow-induced design considerations comprise those systems, components, and structures whose structural integrity in service is essential to maintaining the safety function of the Neutron Control System and the Reseirve Shutdown Control Equipment. 

Gas Distrihutor The gas distributor has a considerable effect on proper operation of the flmdized bed. Basically there are two types (1) For use when the inlet gas contains solids and (2) for use when the inlet gas is clean. In the latter case, the distributor is designed to prevent Back flow of sohds during normal operation, and in many cases it is designed to prevent back flow during shutdown. In order to provide distribution, it is necessary to restrict the gas or gas and solids flow so that pressure drops across the restriction amount to from 0.5 kPa (2 in of water) to 20 kPa (3 Ibf/iu ). 

If casing limitations are fixed by user-supplied relief valves, this information should be conveyed to keep the vendor from rating the compressors on other data. Evaluations can be more of a problem if the same design basis isn t universal with all vendors. Startup and shutdown consideration influence various components, shaft end seals, seal system pressures, and even thrust bearings in some instances. The use of an alternate startup gas, or the desire to operate a gas compressor on air to aid in plant piping dryout should be covered. 

A primary focus in process design is to produce designs that have good overall operability characteristics, as determined by safety and environmental considerations, low product variability, low operating costs, and ease of startup/shutdown. The process design and control system... 

Within oil-field production, treating equipment is selected in a similar manner. As the amount of water produced will vary over the life span of an oil field, equipment is often added as needed to an oil-field treating facility. The design of existing facilities will allow the addition of equipment to occur with minimal disruption during periodic maintenance shutdowns (or turnarounds ) if proper consideration has been given to the potential of changing production fluids. 

Corrosion occurs in various forms and is promoted by a variety of causes, all related to process operating conditions to which equipment and support structures are subjected. It is a continuous problem that can lead to contaminated process streams. This subsequently leads to poor product quality and unscheduled equipment shutdowns, the consequence of which is reduced production, high maintenance costs, and equipment replacement costs. Minimizing corrosion is a key consideration for the designer and can be accomplished in two ways (1) proper material selection for apparatus, and (2) preventive nraintenance practices. Both of these approaches must be examined. 

The PPIS receives signals from the ex-vessel detectors of the NCSS or other protection system sensors and interprets these signals to determine appropriate protective actions. In all DBEs except DBE-2, the control rod drives are tripped and their function is completed in the very early stages of the event. For DBE No. 2, which Includes shutdown by the reserve shutdown control equipment, the shutdown action (release of the reserve shutdown material) is delayed for a brief interval (i.e., minutes). However, if the shutdown action should take place after considerable delay (i.e., several hours), the RSCE is designed to withstand the most severe environment to which it might be exposed prior to completing the required action. 

Design Basis is the design inputs, the design constraints, and the design analysis and calculations, It includes topical areas such as seismic qualification, fire protections, and safe shutdown, It encompasses consideration of such factors as plant availability, plant efficiency, costs, and maintainability, and that subset that relates to safety and the authorization basis. 

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