High-pressure core spray system

Several other systems are available to control room operators to keep the reactor cool during an emergency. These include the High Pressure Core Spray System, Low Pressure Core Spray System, Residual Heat Removal System, Low Pressure Coolant Injection, and Suppression Pool Cooling. All of these systems require both AC and DC power, plus a sufficient flow of coolant water connected to the ultimate heat sink. At Fukushima this ultimate heat sink was the Pacific Ocean (US Nuclear Regulatory Commission, n.d.a). 

These i high-pressure core spray (HPCS) system that replaced the HPCI system. The const e motor-driven pump train powered by its own electrical division complete with J diesel fhese plants also have a single train low-pressure core spray system, as well as a RHR system similar to the system design in the BWR. 3/4 group. 

Steam condensing Containment spray Suppression pool cooling High-pressure core spray (HPCS) system Low-pressure core spray (LPCS) system Automatic depressurization... 

Coolant Inventory Control and Core Heat Removal High Pressure Coolant Injection System Reactor Core Isolation Cooling System Low Pressure Coolant Injection System Low Pressure Core Spray System Control Rod Drive Cooling System Condensate System High Pressure Service Water System... 

To provide a capability for the removal of decay heat in conjunction with the high pressure safety injection system (or the high pressure core spray), the safety and/or relief valves and the suppression pool. 

These plants are designed with two independent high-pressure injection systems, namely reactor cooling sure coolant injection (HPCl). The associated pumps are each potiered fay turbine. also have a multi-loop core spray system and a multi-mode residual heat re sy.stem that can be aligned for low-pressure coolant injection, shutdown cooling, suppre.ssion pc containment spray functions. 

The typical ECCS for BWRs is also composed of three subsystems with equipment and flow path redundancy. The first subsystem is a high-pressure spray system that sprays water on the reactor core. For small pipe breaks, the high-pressure spray can maintain the water level in the reactor vessel so that the core remains covered. For larger breaks, this system cools the core by spraying water on the fuel rods. The second subsystem is a low-pressure spray system that delivers a large-volume water spray to the top of the core. The third subsystem is a low-pressure core injection system that provides a large flow of water to the reactor vessel to reflood and cover the core. 

A third example is the ICI patented use of core shell emulsions for use in internal can lacquers. The particles are not as easily deformed during high pressure airless spray applications as are conventional water based systems. The shell could contain a crosslinking comonomer such as n-methylolacrylamide to enable the emulsion to be self crosslinking when stoved. 

The reactor vessel contains the core, twelve once through steam generators, six canned rotor pumps at a high level in the vessel, and a control rod assembly in each of the 65 fuel assemblies. The top part of the vessel forms the pressuriser with its electric heaters. There is a passive spray system in the pressuriser which takes water from the riser region and sprays it into the steam space in the event of pressure rise in the core. The containment has a novel form of pressure suppression where the water for pressure control is contained in a tank farm connected to the reactor cavity by large diameter pipes. 

Flow proceeds from the lower plenum, through the core. The steam and water are separated the steam is then dried and passed to the turbine. Other flow (see above) returns to the recirculation system. Feedwater is introduced to the annulus between the core shroud and reactor vessel (Fig. 4). The recirculation system piping is a primary pressure boundary for the high-pressure, high-temperature reactor coolant. Type 304 stainless steel was selected for recirculation system piping and numerous other auxiliary systems (such as the reactor water cleanup system, residual heat removal system, core spray, and other emergency core cooling systems) for its corrosion resistance and adequate mechanical properties. Failures of weld heat affected zones... 

Low-Pressure Systems High-Pressure coolant injection Core spray... 

The plant s integrated control system attempted automatically to reduce reactor/turbine power in accordance with the reduced feedwater flow. The control rods were being inserted into the core and reactor power had been reduced to about 80%. At the same time the primary-side reactor operator held open the pressurizer spray valve in an attempt to keep the reactor coolant pressure below the high pressure reactor trip set point of 2300 psig (normal pressure is 2150 psig). However, the reduction of feedwater and subsequent degradation of heat removal from the... 

The containment for the PWR is generally similar, except that a steam quenching system is not necessary because of the high volume within the containment. Cold water sprays or ice condensers are employed, however, to remove heat and reduce the pressure in the containment building and to help retain any radioactivity released from the core. A typical PWR containment has been illustrated in Fig. 9.5. 

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