Steam generating systems nuclear pressurized water reactors

Fig. 1. Pressurized water reactor (PWR) coolant system having U-tube steam generators typical of the 3—4 loops in nuclear power plants. PWR plants having once-through steam generators contain two reactor coolant pump-steam generator loops. CVCS = chemical and volume-control system.

The DOE N-Reactor is one of the plutonium production reactors located on the Hanford Reservation near Richland, Washington. It is graphite moderated, pressurized water reactors that in addition to production of special nuclear materials also provided steam to turbine generators owned by the Washington Public Power Supply System for electric power production. It began op ition in 1 is put into standby status in 1988 and closed because of similarities to Chernobyl. 

Power Production. Steam cycles for generation of electric power use various types of boilers, steam generators, and nuclear reactors operate at subcritical or supercritical pressures and use makeup and often also condensate water purification systems as well as chemical additives for feedwater and boiler-water treatment. These cycles are designed to maximize cycle efficiency and reliability. The fuel distribution of sources installed in the United States from 1990—1995 are as follow coal, 45% combined cycle, 27% miscellaneous, 14% nuclear, 11% solar, oil, and geothermal, 1% each and natural gas, 0.3%. The 1995 summer peak generation in the United States was 620 GW (26). The combined cycle plants are predominantly fired by natural gas. The miscellaneous sources include bagasse, black liquor from paper mills, landfill gas, and refuse (see Fuels frombiomass Fuels fromwaste). 

A concept of an evolutionary reactor is pursued with the joint French / German European Pressurized Water Reactor , EPR, a 1525 MW(e) plant with evolutionary steam generating system and innovative double-walled containment [20]. A three years basic design phase as a prerequisite for the beginning of the licensing procedure was finished in 1997. The characteristic feature is a core catcher to restrict a possible core melt to the power plant itself. The joint effort by Germany ind France, however, finds in both countries a situation where no further base load is required. The EPR, confirmed as a future standard in France, is projected to substitute decommissioned nuclear plants. 

The total cost of electricity sold in the United States in 1998 was 3.24 million gigawatt hours at a cost to consumers of 218.4 billion. The electricity generation plants use fossil fuel, nuclear, hydroelectric, cogeneration, geothermal, solar, and wind energies. The major players are fossil and nuclear steam supply systems. The two types of nuclear reactors are boiling water and pressurized water reactors. Some relevant data on the costs of corrosion estimated in 1998 are as follows nuclear facilities 1,546 billion fossil fuel sector 1,214 billion transmission and distribution 607 million hydraulic and other power 66 million. The total cost of corrosion in the electrical utilities industry in 1998 is estimated at 6,889 billion/year. 

PWR reactor Nuclear reactor where the core power is transported by pressurized water which circulates in a system of primary circuits. The production occurs within a set of Heat Exchangers (Steam Generators), using the thermal energy contained in primary water (PWR = Pressurized Water Reactor). 

The 1255 MW(th)/400 MW(e) Consolidated Nuclear Steam System (CNSS) is an integral pressurized-water reactor (PWR) with the reactor core and steam generators located within the reactor pressure vessel (see Figure 1). Reactor coolant system pressure Is controlled via an electrically heated pressurizer connected to the reactor vessel through four surge lines. 

Steam generators, control and protection system (CPS) drives, pressurizer system, reactor installation systems, biological shielding and other systems — the technologies widely used in NPPs with pressurized water reactors and shipboard reactors of the Russian nuclear fleet Widely used reactor technologies the operating experience of multi-purpose shipboard reactor installations exceeds 6000 reactor-years... 

Plans were underway to change from a manual main feedwater system in a pressurized water reactor at a nuclear power plant to an automatic switchover. The concern was whether the manual switchover was a safe procedure to follow during the transition to the automatic system. In different plants, this switchover could take from 5 to 60 min to perform. If the action was not performed in time, then the steam generator might run dry and cause a safety hazard. 

There are nearly 500 nuclear reactors in operations around the world and the most widely used is the pressurized water reactor (PWR). These nuclear reactors use water pressurized to around 160 bar to dissipate heat to achieve a high temperature and avoid boiling. The heat is transferred to a secondary system in a steam generator ... 

Pressurized Water Reactor. The PWR contains three coolant systems (1) the primary system, which removes heat from the reactor and partially controls nuclear criticality (2) the secondary system, which transfers the heat from the primary system via the steam generator to the turbine-driven electric generator (3) the service water system (the heat sink), which dumps the residual coolant energy from the turbine condenser to the environment. The service water is recirculated from a river, lake, ocean, or cooling tower. In the primary system (Fig. 31.21), dissolved boron is present to control nuclear criticality. Fixed-bed ion exchange units are used to maintain the water quality in both the primary and the secondary systems. In addition, the chemical and volume control system reduces boron concentration during the power cycle to compensate for fuel burnup. These operations are carried out continuously though bypass systems. A more complete... 

The process at Three Mile Island involved nuclear fission and subsequent reactor cooling using circulating water. The primary water was kept under pressure to prevent boiling. Heat was transferred to a secondary water system that supplied power to a steam generator. Upon completion of this step, steam condensate was recovered and recycled. All radioactive materials, including primary water, were enclosed in a lined concrete containment building to prevent their escape to the atmosphere. 

Gas cooled reactors use carbon dioxide under pressure as a recirculating heat transfer medium (coolant) between the hot nuclear reactor core and water in a secondary circuit in order to raise steam and electrical power in an otherwise conventional high pressure steam generator/turbine/condenser loop. The role played by ion exchange is denoted by systems A-D in Figure 8.22. 

A common thread in many of the reactor technologies that currently exist or that are under development is the use of water as the heat transport medium (the coolant ). In many respects, water is an ideal coolant, because it has a high heat capacity, can be obtained in a high purity, is inexpensive, has a wide liquid range (0-374.15 °C), is easily handled, and had been used since the dawn of steam power. Thus, in their most fundamental form, water-cooled nuclear reactors (WC-NRs) comprise a nuclear boiler, a heat transport system (piping, channels, steam generators, etc.), a set of turbines (high pressure, intermediate pressure, and low... 

The PWR has three main water circuits. The first is the primary circuit that carries heat energy from the nuclear reactor to the steam generators. The water is maintained at a pressure of sl50bar and an operating temperature of s573 K. Since the primary circuit is a closed loop, it is the only water circuit in the power station that contains radioactivity. The second water circuit is the water-steam cycle, and the final circuit is the water cooling system, which dissipates excess heat. 

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