To comment on the following update, log in, then open the issue: http://www.openoffice.org/issues/show_bug.cgi?id=103303 Issue #|103303 Summary|unit 2 assignment for nuclear plant Component|Word processor Version|1.0.0 Platform|All URL| OS/Version|All Status|UNCONFIRMED Status whiteboard| Keywords| Resolution| Issue type|PATCH Priority|P3 Subcomponent|printing Assigned to|katie Reported by|erlingk
------- Additional comments from [email protected] Fri Jul 3 04:06:32 +0000 2009 ------- 1.The circulating water system functions to provide a heat sink for the main condenser under normal operating and shutdown conditions. Additionally, condensation of the steam creates a low pressure area (vacuum) for turbine exhaust, which enables the turbine to extract the maximum amount of work from the steam. At most plants the circulating water system consists of three or four circulating water pumps, condenser inlet and outlet waterboxes, associated interconnected piping and valves. The circulating water pumps, take suction on a water source, discharge cooling water into the condenser inlet waterbox via underground pipes. The water then passes through the condenser cooling tubes to remove heat from the turbine exhaust steam. From the tubes, the water then flows into the condenser outlet waterbox. The cooling water then moves past an outlet isolation valve and into a common discharge header then to a discharge canal. The discharge canal empties into the water source. 2.The Ultimate Heat Sink is the medium to which the residual heat can always be transferred, even if all other mediums for the removal of the heat have been lost or are insufficient.For NRC purposes, the UHS is defined as the complex of sources of service or house water necessary to operate, shut down, and cooldown a nuclear plant safely following a design basis accident. Water for the UHS is frequently supplied directly from large-surface water bodies, such as rivers, lakes, or oceans, by which the heat from the service water system can be dissipated safely. The UHS can also be supplied from dedicated ponds, spray ponds, and cooling towers. These devices frequently are small in relation to the heat loads imposed upon them and, thereby, operate at relatively high temperatures. The design considerations for the UHS are: (1) The UHS must be able to dissipate the heat of a design basis accident (e.g., a LOCA) of one unit plus the heat of a safe shutdown and cooldown of all other units it serves. (2) The heat sink must provide a 30-day supply of cooling water at or below the design basis temperature for all safety-related equipment. (3) The system must be shown to be capable of performing under the meteorological conditions leading to the worst cooling performance and under the conditions leading to the highest water loss. These must be the worst periods for water loss (30 days) and peak temperatures over the data period (usually at least 30 years) as determined by computer simulation. The Ultimate heat Sink is often referred to as Essential Cooling Water and is closely tied to the Emergence Core Cooling System. 3. The major secondary systems of a pressurized water reactor are the steam generating, main steam and condensate/feedwater system. Since the primary and secondary systems are physically separated from each other by the steam generator tubes, the secondary system should contain no radioactive material. 4. The steam generators, uses heat generated in the core and carried to the steam generators by the reactor coolant system, to produce the steam that drives the plant turbine generator. A Steam Generator is a vertical, U-tube heat exchanger with an integral economizer. Reactor coolant is inside the tubes and secondary coolant (feedwater) is on the shell side or outside of the S/G tubes. 5.The Main Steam System (MSS) is used to transport steam from the outlet nozzles of the steam generators through the containment wall to the turbine- generator (TG). The MSS is designed for a range of steam flow and pressures, varying from warmup to rated full power conditions. The system provides a means to dissipate heat during plant step load change and during plant startup. It also provides steam to the TG System second-stage moisture separator reheaters (MSRs), the turbine gland seal system, the turbine bypass system, the auxiliary steam system, and the process sampling system. The MSS is located both inside and outside the containment. The main steam piping begins at the steam generator outlet nozzles. Passes from the steam generators, through the containment and primary auxiliary building, and on to the inlet to the Main Turbine Generator Turbine (MTGT). Before reaching the MTGT branch piping leads to the main feed pump turbines, the auxiliary feedwater pump turbines, the turbine bypass valves, and other auxiliary equipment. Additionally, main steam piping supplies the main steam safety valve and the atmospheric dump valve branch lines. 6.Main Steam Safety Valves Each main steam line contains four spring-loaded safety valves, one main steam atmospheric dump valve, and one MSIV. All safety valves are located outside containment, but as close as possible to the Main Steam System containment penetration. The main steam safety valves are designed for in-service testing, in accordance with the American Mechanical Engineers Boiler and Pressure Vessel Code. The valves and their supports are designed to withstand operating and accident conditions. 7.Feedwater For low power operations a second point of feedwater injection into the steam generator is provided. The downcomer feedwater line penetrates the SG shell through a nozzle on the cold leg side. The nozzle contains a thermal sleeve to minimize stress in the shell/nozzle area. The feedwater then flows to a distribution ring in an arc of approximately 45° in both directions from the point of feedwater entry. The nozzle and feedwater header are on a level approximately one foot above the top of the evaporator tube bundle. Due to the location of the feed ring and flow path followed before entering the evaporator, feedwater introduced here is often referred to as downcomer feedwater. The use of downcomer feedwater is limited as low power (5 to 20%) and biased to 10% flow above 20% power. --------------------------------------------------------------------- Please do not reply to this automatically generated notification from Issue Tracker. Please log onto the website and enter your comments. http://qa.openoffice.org/issue_handling/project_issues.html#notification --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
