Solid- fuel for nuclear reactions may be fabricated into various small shapes such as (a) plates (b) pallets (c) pins (d) any one of the above (e) none of the above. B. As the system pressure starts its next rapid decrease, core cooling is aided by bubble formation in the lower plenum which swells some of the lower plenum water up through the core. This reflects the uncertainty of how much water is in the lower plenum at the end of blowdown and the rate which spray and LPCI can penetrate to the lower plenum against the steam upflow. Core temperatures are calculated to attain their highest values should the recirculation line break (see Fig. Page-10 section-1 Learn Power Plant Engineering MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Thorium, D. D. None of the above Their principle of operation exploits the Venturi effect: the reduction in fluid pressure that results when a fluid flows through a constricted section of a pipe. STANDARD BWR PLANT CORE STANDBY COOLING SYSTEM DELIVERY CAPABILITY. The first nuclear power plant was built in India at which place? In the BWR the zirconium alloy is mostly Zircaloy-2 and in the PWR the zirconium alloy may be Zircaloy-4, M5, or Zirlo in most Western countries (Motta et al., 2015). These systems are activated by signals of a low reactor vessel water or by high pressure signals from the drywell region surrounding the vessel. 1. which one is not a commonly used coolant for fast breeder reactor? Natural convection boiling water reactors limit complexity by dispensing with the need for pumping water within the reactor vessel. Evolution of Boiling water reactor chemistry options from 1977 to 2008. ScienceDirect ® is a registered trademark of Elsevier B.V. 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URL: https://www.sciencedirect.com/science/article/pii/B978008100962800010X, URL: https://www.sciencedirect.com/science/article/pii/B9780128152614000135, URL: https://www.sciencedirect.com/science/article/pii/B9780123884466000022, URL: https://www.sciencedirect.com/science/article/pii/B9780081003077000132, URL: https://www.sciencedirect.com/science/article/pii/B9780080217444500142, URL: https://www.sciencedirect.com/science/article/pii/B9780080560335000823, URL: https://www.sciencedirect.com/science/article/pii/B9780081003145000038, URL: https://www.sciencedirect.com/science/article/pii/B978012817503300002X, URL: https://www.sciencedirect.com/science/article/pii/B978008056033500077X, URL: https://www.sciencedirect.com/science/article/pii/B9781845695118500202, Linear and Non-Linear Stability Analysis in Boiling Water Reactors, 2019, NEI/ERI, 2008; AREVA, 2015b; GNF, 2015a; Westinghouse, 2013, GENERAL FEATURES OF EMERGENCY CORE COOLING SYSTEMS, Material Performance and Corrosion/Waste Materials, Steam turbine cycles and cycle design optimization, Advances in Steam Turbines for Modern Power Plants. A sample of experimental rod temperature data from the BWR-FLECHT experiment is shown in Fig. 1. which one is not a commonly used coolant for fast breeder reactor? This system is more complicated than the Boiling water reactor design. Ina pressuried water reactor (PWR)..... A. A major variable on the map is the time at which core reflooding begins. Changing the pumping power (hence, the coolant flow rate) causes a change in reactivity through a change in core voids. Figure 3 shows the rate of implementation of HWC, zinc and NMCA, and online noble metal addition (OLNC). Secondary water in the steam generator boils at pressure approximately 6-7 MPa, what equals to 260°C (500°F) saturated steam. The key features of the advanced technologies for the heat cycle are reactor internal pump (RIP) and large-capacity steam turbine. An important feature of the BWR design is the jet pump, of which there is typically an array of between 16 and 24 (dependent on the specific reactor boiler arrangement of a given design) located between the core shroud and the vessel housing. The steam is directly used to drive a turbine, after which it is cooled in a condenser and converted back to liquid water. Boiling Water Reactor Plant Inside the boiling water reactor (BWR) vessel, a steam water mixture is produced when very pure water (reactor coolant) moves upward through the core abso rbing heat. This is why the corium of BWRs has a higher percentage of metal mass (resulting from the larger inventory of both stainless steel and zircaloy). In spite of boiling water in the reactor, Dresden unit 1 arranged a steam drum and a secondary steam generator before supplying steam to the turbine. The CRGTs are also functioning as obstacles to melt progression. U₂₃₅, A. For example, a key issue facing BWRs in the United States concerns IGSCC of reactor internals, as discussed in other chapters. In PWRs the control rods driving mechanisms are mounted on the head of the pressure vessels and are inserted from above into the reactor. After the remaining water boils off, the CRGTs are heated up and melted. Supertheated steam is generated in following reactor (a) boiling water (b) gas cooled (c) pressurised water (d) all of the above (e) none of the above. Strasser and Yario1 list initial details of several different designs and the typical design parameters. Electrical Engineering MCQ. Figure 1. In a PWR, the primary coolant is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms. Here steam is generated in a heat exchanger outside the nuclear reactor. Copyright © 2020 Elsevier B.V. or its licensors or contributors. The coolant water boils in the core of the reactor. The BWR bundles may contain shorter rods and the entire bundle or assembly is encased in a slender box called channel, which are also made of Zircaloy-2 alloy. A CANDU reactor uses _____. Each Section contains maximum 70 questions. A schematic of the elevation of a BWR/1 is provided in Fig. Heat is produced by nuclear fission in the reactor core, and this causes the cooling water to boil, producing steam. Solid- fuel for nuclear reactions may be fabricated into various small shapes such as (a) plates (b) pallets (c) pins (d) any one of the above (e) none of the above. Figure 4. The influence of lower plenum flashing at 10 to 12 seconds does not appear on the temperature curves shown in Fig. Thus a recirculation line break is called the design basis accident. In Nuclear Safety in Light Water Reactors, 2012. In a pressurized-water reactor, the reactor core heats water and keeps it under pressure to prevent the water from turning into steam. The BWR design8 development has comprised six stages beginning with the BWR/1 (embodied by the example of the Dresden plant in the United States, 180 MWe commissioned in 1955) through to the BWR/6 at 1100 MWe pioneered in the early 1970s. The supercritical steam generator is a proven technology. Here steam is generated within the reactor itself. Thus, the great number of CRGTs not only affects the progress of melt relocation, but also contributes to the metal mass in corium. d) Any type of uranium . Second, BWRs in United States undoubtedly have greater cobalt sources than plants in most other countries, despite strong efforts to replace cobalt sources. Here the water in the primary loop is maintained at high pressure (15 – 17 MPa) to avoid boiling at reactor exit. BWRs have characteristics that distinguish them from the other types of reactors: refrigerant undergoes a phase change in the reactor core and is a direct cycle. 67. This same trend existed for a PWR. Table II. Fig. Table II shows that the amount of coolant injected into the system is increased as the pressure decreases. Ans: b . Accident Tolerant Materials for Light Water Reactor Fuels, Advanced Fuels/Fuel Cladding/Nuclear Fuel Performance Modeling and Simulation, Plant life management (PLiM) practices for boiling water nuclear reactors (BWR): Japanese experience, Understanding and Mitigating Ageing in Nuclear Power Plants, International Journal of Heat and Mass Transfer. Super-heated steam is generated in following reactor. Plant-specific considerations sometimes influence or indeed limit the options for controlling water chemistry, so we see different chemistry specifications at different plants. 17. Loss of pump power causes the core flow rate to decrease as the recirculation pumps begin to coast down. In the BWR the water in the reactor core is permitted to boil under a pressure of 75 atmospheres, raising the boiling point to 285°C and the steam generated is used directly to drive a steam turbine. 17. The reactor core within the reactor vessel is surrounded by a stainless steel shroud; this separates the downward flow of the cold coolant to its outside from the upward flow of coolant in the central regions. R.W. Regarding specification of the 1100 MWe class BWR shown in Table 3.2, 20 internal jet pumps are applied, and this reduces to two external recirculation loops against the early-designed five loops. The saturated steam passes through the main steam system piping and is used to drive the turbine and generator. Protons and neutrons in a nucleus, A. The steam then goes through the separator and steam dryer inside the reactor pressure vessel (RPV), where water droplets are removed from the steam, so that the steam becomes saturated. Figure 2 depicts the changing chemistry strategies over the past 30 years, showing the focus on improving water quality in the early 1980s and the move to educing chemistry to control IGSCC, which in turn resulted in increased radiation fields, subsequently controlled by zinc injection. With the capture of neutrons, the transmutation of boron leads to the formation of helium and lithium resulting in swelling. Figures 20.3 and 20.4 show schematic plant systems of BWR and ABWR. Feed water passes through the fuel elements in the core as coolant and also as moderator. 18. A BWR plant layout comprises the reactor vessel at its centre that is surrounded by the shield wall of reinforced concrete. In fact, sulfate is the most aggressive impurity from the viewpoint of IGSCC, and much effort has gone into reducing it. Basic specification of typical BWR plants. The steam is used to power a turbine generator. Light water in a BWR is circulated through a heterogeneous core of nuclear fuel rods arranged vertically. The actual configuration of water rods in a BWR fuel assembly will vary depending upon the specific BWR fuel design. 14). As the steam is cooled, it condenses back into water and is returned to the steam generator to be used again and again. The nuclear steam generators are used for nuclear power generation, navy vessels and submarines, and nuclear power research. Ina pressuried water reactor (PWR)..... A. Pressurized-water nuclear reactors. 15. The lower and upper tie plates provide structural support for the fuel during fuel handling and operation. Commercial operation of the ABWR has been started at Kashiwazaki-Kariwa unit 6 and 7 in Japan since 1996 and 1997. Ans: b. A boiling water reactor is cooled and moderated by water like a PWR, but at a lower pressure (7MPa), which allows the water to boil inside the pressure vessel producing the steam that runs the turbines. production of heavy water requires a dedicated plant to separate the D 2 O from ordinary water, raising the concentration of D 2 O from its natural concentration of much less than O.1% to the 99% used in a CANDU reactor. Tarapur Rana pratap sagar kalpakkam Narora 3. Enriched uranium, B. 66. The Westinghouse BWR design consists of four 5×5 mini-assemblies in its SVEA-96 Optima3 design. This steam is then condensed and recycled back to the reactor core. The major difference between a Boiling Water Reactor (BWR) and other types of nuclear power generating systems is the steam void formation in the reactor … Ans: b; Solid- fuel for nuclear reactions may be fabricated into various small shapes such as (a) plates (b) pallets (c) pins (d) any one of … One reason the embrittlement limit is reached at 2870°F for a BWR and 2470°F for a PWR is that BWR fuel cladding is thicker. The lower tie plate of a BWR assembly provides structural support for the lower end of the fuel rods and also serves to distribute and direct coolant flow entering the assemblies. The upright, cylindrical core sustains a critical chain reaction causing the water circulating in the fuel channels to boil and to be converted to a two-phase, steam–water mixture with the wet steam processed by a variety of systems in the plenum directly above the core. The BWR lower head is geometrically complex, having a large contact surface area with CRGTs and IGTs. If the leak rate from the vessel is high enough that the HPCS cannot keep the core covered, automatic depressurizing valves attached to the steam lines open to allow a more rapid depressurization rate. b) Enriched uranium. c) Pressurized water. The first requirement of plant chemistry is to maintain high-purity water in all coolant systems, including the need to avoid impurity transients, which are beyond the scope of this paper. Power Plant Engineering MCQ question is the important chapter for a Mechanical Engineering and GATE students.
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