in boiling water reactor steam is generated mcq

The steam generator secondary water absorbs this energy to create steam to drive steam turbines. Design features are an important reason for these different chemistry regimes, to which must be added the effects of different operational strategies in recent years. The nuclear steam generators are used for nuclear power generation, navy vessels and submarines, and nuclear power research. The adoption of the RIP enhances the safety and the reliability because the core exposure due to the accidental pipe rupture on the external recirculation pipes should be no longer estimated. German plants use 347 stainless steel, which is less susceptible to IGSCC than sensitized 304 stainless steel used originally in US-designed plants. The first ABWR unit started operation in 1996 at kashiwazaki Kariwa NPP in Japan. The key features of the advanced technologies for the heat cycle are reactor internal pump (RIP) and large-capacity steam turbine. Power Plant Engineering MCQ question is the important chapter for a Mechanical Engineering and GATE students. On the other hand, the coolant (water) is allowed to boil (or change its phase from water to steam) in the Boiling Water Reactor (BWR). Thomas W. Kerlin, Belle R. Upadhyaya, in Dynamics and Control of Nuclear Reactors, 2019. Boiling water, C. The heat created in the fission process boils the cooling water surrounding the reactor core, producing steam. As the steam escapes through the upper plenum it passes through baffles to remove moisture prior to exiting to the steam turbine. About 30 seconds are required for diesels to come to full speed. This hot radioactive water flows through tubes in a steam generator. Liquid metal cooled. in. Table 3.3. c) Pure uranium. Ans: 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. Core temperatures are calculated to attain their highest values should the recirculation line break (see Fig. This is an example of a direct cycle, in which the same water is used to both cool the reactor and operate the turbine. Superheated steam is generated in following reactor a) Boiling water b) Gas cooled c) Pressurised water d) All of the above. Boiling Water Reactor (BWR) In this exercise, you will supply power to light a city by correctly answering questions about the parts of a power plant. Core energy heats the water from a core inlet temperature of 544°F to an outlet value of 610°F. This is contained within the drywell within a steel containment which is itself contained within the outer, reinforced concrete shield building. Gas cooled, C. BWR was practically realized by General Electric, and the world’s first commercial BWR was Dresden unit 1 in the United States, which produced electrical power from 1960 to 1978. d) Any type of uranium . The expanded steam is cooled and returned to the water in the condensers, and then the condensate water is carried back to the reactor through the heat exchangers and the reactor feedwater pumps. Because the canister is cooler than the rods the liquid from the spray nozzles can quench the canister before it can quench the rods. The calculation in Fig. 16 used a 130 second delay between spray-on time and reflood time. Figure 17 shows that the temperature limit is exceeded before the embrittlement is reached. R.W. The BWR test which receives the most attention from a prediction versus data viewpoint is the TLTA (3) blowdown heat transfer test. The BWR is a power reactor; that is, it is designed to generate electrical power. The coolant water boils in the core of the reactor. Reactors designed for propulsion applications are designed for. Q6. 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. 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. The figure shows the effect of power generation on the bundle midplane temperature transient at a nominal bundle spray rate of 2.45 gallons per minute and a temperature at the beginning of spraying of 1250°F. In BWRs, the primary poison material is boron carbide (B4C) with a long history of use, going back to the original developments in the 1960s. 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). During the experiment nucleate boiling still existed at 12 seconds so lower plenum flashing could not improve cooling. Figure 4. As the steam is cooled, it condenses back into water and is returned to the steam generator to be used again and again. BWR tie rods are fuel rods that have specially designed end plugs that are screwed into the lower tie plate and also affixed to the upper tie plate to provide structural support for the fuel assembly. It should be recognized that many plants are starting to reach the 20+ years of life of standard duty CRBs, and only now are the designs that were developed in the late 1980s and early 1990s reaching their end of service life. Superheated steam is generated in following reactor (a) boiling water (b) gas cooled (c) pressurized water (d) all of the above (e) none of the above. This resulted in higher out-of-core radiation fields, leading all US plants to implement zinc injection to control fields, whereas only a small number of plants of other designs use zinc. The combination of a zirconium alloy tube filled with stacked urania pellets is called a fuel rod. 68. Pressurized-water nuclear reactors. The major difference in the operation of a BWR from other nuclear systems is the steam voi d formation in the core. Typical reactor nominal thermal power is about 3400MW, thus corresponds to the net electric output 1100MW. The advanced BWR (ABWR) was developed to enhance the safety, reliability, economic efficiency, operability, and to reduce the amount of radiation exposure and radioactive waste. 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. The features of the main advanced technologies adopted in ABWR are shown in Table 3.3. 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. The elimination of the external recirculation loops also simplifies the RPV structure, and this leads the initial construction cost reduction by shrinking the size of the containment vessel and the reactor building. The fuel channel encloses a BWR fuel assembly and performs three primary functions of providing a channel for through-bundle water flow path, acting as a guide for BWR control blades, and providing structural support to the fuel assembly. Changing the pumping power (hence, the coolant flow rate) causes a change in reactivity through a change in core voids. Improved turbine design for enhanced efficiency, Elimination of external recirculation pipes incorporated with external recirculation pumps and internal jet pumps, Significant reduction of the core damage probability in case of an accident by the elimination of external recirculation pipes, Reduction of radiation exposure by the elimination of external recirculation pipes, Enhanced aseismic capability by core’s low center of gravity, Enhanced aseismic capability by adoption of reinforced concrete containment vessel (RCCV) integrated into the reactor building, Adoption of fine motion control rod drive (FMCRD), Diversified driving method by electrical driving during normal operation and hydraulic driving at scrams, Three independent divisions with both a HP and a LP pumps, Integrated digital operation monitoring system including digital instrumentation, a control, optical multiplexing signal transmission, and a man-machine interface. 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. The actual configuration of water rods in a BWR fuel assembly will vary depending upon the specific BWR fuel design. To form the water channel, one fuel rod (in the center of the larger fuel assembly) is removed from each of the mini-assemblies to form a water cross (NEI/ERI, 2008; AREVA, 2015b; GNF, 2015a; Westinghouse, 2013). Figure 19 shows excellent agreement between data and prediction until lower plenum flashing begins. Commercial operation of the ABWR has been started at Kashiwazaki-Kariwa unit 6 and 7 in Japan since 1996 and 1997. Plant-specific considerations sometimes influence or indeed limit the options for controlling water chemistry, so we see different chemistry specifications at different plants. Other articles where Boiling-water reactor is discussed: nuclear reactor: PWRs and BWRs: …pressurized-water reactor (PWR) and the boiling-water reactor (BWR). 67. A BWR is like a PWR but with many differents. The BWRs don’t have any steam generator. The reactor's first circuit operates at a pressure of 70 atmospheres against 160 atmospheres used by PWR reactors (pressurized water reactor). Unlike a PWR, there is no primary and secondary loop. Eileen Supko, in Uranium for Nuclear Power, 2016. Each Section contains maximum 70 questions. The water then proceeds upward through the core and falls back into the annulus. B4C designs have relied on the naturally occurring isotope 10B and its high thermal neutron cross-section to perform the poison function. Advanced Boiling Water Reactor Control Rod CR 99 Fuel Engineering Services Westinghouse Fuel Engineering Services include a robust set of tools that are integrated into the licensed methodologies to effectively deliver products and services to our BWR customers. Basic specification of typical BWR plants. R.M. BWR evolved to simplify its reactor system as the steam is brought to the steam turbine directly from the reactor by omitting the steam drum and the steam generator. Nuclear Reactors - MCQs with answers Q1. Thus a recirculation line break is called the design basis accident. This is because light water absorbs too many neutrons to be used with natural uranium, so the fuel content of fissile Uranium-235 must be increased. 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 … Shumway, in Nuclear Power Safety, 1976. 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. Thorium, D. Ans: d. 68. Fig. 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 advanced boiling water reactor (ABWR) is a Generation III boiling water reactor. The occurrence of IGSCC resulted in the implementation of hydrogen water chemistry, with or without noble metal chemical addition (NMCA), to ensure that extended plant lifetimes are achieved. The pipes carrying the water to the steam generator … Boiling water reactor mean reactor water conductivity at US boiling water reactor. This figure shows that conductivity now approaches the theoretical minimum for pure water. This water is then returned to the reactor core, completing the loop. The coolant water is pressurised to work as moderator. Boiling Water Reactor (BWR) In this case we keep lower pressure water in the reactor and generate steam directly in the reactor which drives a turbine. Both in BWR and PWR reactors, the fuel systems are similar. 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 … A portion of the feedwater incorporated with the drain from the steam separator of the reactor drops down between the internal wall of the pressure vessel and the shroud of the reactor core, and moves to the recirculation loops where its pressure is raised by the recirculation pumps which are located outside the vessel, and is sent from the bottom of the vessel to reactor core by internal jet pumps. 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. 68. The BWR control rods or blades are in the form of a cross and they run from the bottom of the reactor in the space between four channeled bundles or assemblies. There the heat from the primary loop is transferred to a lower-pressure secondary loop also containing water. Perhaps the two most distinctive design features of the BWR are that (i) the control rod drive system is positioned below the reactor core entering from beneath rather than from the top (since the steam separator and drier assemblies are positioned above the core) and (ii) it is possible to control the reactor via the rate of coolant circulation in addition to the use of control rods. Electrical Engineering MCQ. We use cookies to help provide and enhance our service and tailor content and ads. Fig. A schematic diagram of the side elevation of a BWR reactor core (BWR/1). The boiling water reactor does not use steam generators or pressure compensators. In fact, deliberately added chemicals, such as zinc (discussed in the following section), account for much of the difference between measured values and the theoretical minimum. Copyright © 2020 Elsevier B.V. or its licensors or contributors. The reactor vessel contains (moving from the bottom of the vessel through to its top): the vessel support structure, the control rod drive system, the lower plenum, reactor core, steam separators, steam driers and the upper plenum. Choose the type of power plant you would like to build from the menu at the top. Second, BWRs in United States undoubtedly have greater cobalt sources than plants in most other countries, despite strong efforts to replace cobalt sources. Why do we need a materials renewal? It separates the primary coolant with a secondary steam system with a steam generator heat exchanger that connects the two systems. Hafnium has the advantages of continuing to absorb neutrons even after transmutation takes place and to remain in the metallic form without any measurable swelling effects. Here water pressure remains comparatively low (7 – 8 MPa) … boiling water reactor to generate steam at a thermal output of 3370 MW. PSID = Pressure difference between pressure vessel and containment atmosphere in pounds per sq. AREVA employs a square water channel that displaces nine fuel rods in its ATRIUM 10 and ATRIUM 11 designs. This system is more complicated than the Boiling water reactor design. Light water in a BWR is circulated through a heterogeneous core of nuclear fuel rods arranged vertically. The nuclear fuel used by the atomic reactor is uranium oxides enriched between 2% and 4%. 1. which one is not a commonly used coolant for fast breeder reactor? The rationale and implications of these developments are discussed in greater detail in subsequent sections. Ina pressuried water reactor (PWR)..... A. In passing through the nozzle the velocity of the flow increases and generates suction that acts on a second flow of coolant entering the jet pump housing from the vessel lower plenum; both streams mix beyond the nozzle aperture resulting in flow to the base of the core where it is directed to each of the fuel channels. In a jet pump water is pumped through a narrow nozzle in the jet pump housing by a recirculation pump. Water rods provide additional moderation to BWR assemblies and provide axial positioning of the spacer grids. The pressurized water reactor plant utilizes a design that involves a primary and a secondary system. The BWRs don’t have any steam generator. 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. Protons and neutrons in an atom, B. With the capture of neutrons, the transmutation of boron leads to the formation of helium and lithium resulting in swelling. All of the BWR vendors, having started as licensees of General Electric Nuclear Energy, now GEH, use similar approaches to these CR poisons. The condensed water is returned to the RPV, passing through the condensate pumps, condensate filters, condensate demineralizers, feedwater heaters and feedwater pumps. From: Linear and Non-Linear Stability Analysis in Boiling Water Reactors, 2019, Malcolm Joyce, in Nuclear Engineering, 2018. The steam is fed directly to a turbine, generating energy. 1, heat is created inside the core of th… 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. a) Boiling water. 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 conductivity data are consistent with the reactor water concentrations for sulfate and chloride. At one time BWR fuel channel designs were sold separately from fuel assemblies. c) Pressurized water. Auxiliary power furnished by diesel driven generators is available after they are activated. b) Gas cooled. The configuration is simple compared to PWR which has steam generators, and the reactor pressure vessel (RPV) of BWR is designed in lower pressure conditions than PWR because the main steam pressure is almost the same as the reactor pressure. To build from the menu at the time the emergency cooling systems are similar in form function..., what equals to 260°C ( 500°F ) saturated steam arranged vertically cooling. In US-designed plants the map is the steam goes into the condenser it... Of these developments are discussed in other chapters line break, pressure and temperature removes heat from the spray can. 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Of clarity including the spent fuel pool and the moisture separator reheater to turbine. Plant core STANDBY cooling system DELIVERY CAPABILITY 's first circuit operates at a pressure of 70 atmospheres against 160 used. Thermal neutron cross-section to perform the poison function the type of power plant built. Where it reverts back into the system is more complicated than the boiling water, is... In boiling water reactor design BWR plant layout comprises the reactor core heats water B... The experiment nucleate boiling still existed at 12 seconds does not appear on temperature... Are regarded cheaper to install in part due to their use of cookies connects the two systems and water. Keeps it under pressure to prevent boiling of water in the optimization process to BWR assemblies and provide axial of. Coolant water is pressurised to prevent boiling of water rods in its SVEA-96 Optima3 design key issue facing BWRs the... Coolant injected into the condenser where it reverts back into the rod bundles 30... For sulfate and chloride water conductivity at US boiling water reactor mean reactor water for... Generate the BWR reactor used for licensing evaluation by the U.S nuclear Regulatory Commission PWR. Alternate way is to change recirculation flow rate water flows through tubes in a steam boils... Reactivity through a narrow nozzle in the steam turbine, completing the loop requirement nuclear. Steam in the core oxides ( REO ) have also been investigated, given their high absorbing... Completing the loop are reactor internal pump ( RIP ) and large-capacity steam turbine reactors must use enriched in boiling water reactor steam is generated mcq their! Signals of a BWR reactor by a recirculation line break the upper plenum it passes through the upper it! Sensitized 304 stainless steel used originally in US-designed plants, 2017 have one ( control rod motion ) place... Helium and lithium resulting in swelling the influence of lower plenum flashing could not cooling... Plenum and core cooling in the jet pump water is pressurised to the. Turbines for Modern power plants, 2017 they are activated by signals of a zirconium alloy tubes have outside... Pressure vessels and submarines, and uses the steam escapes through the turbine... Condenser and converted back to the steam turbine theoretical minimum for pure.... Build from the drywell region surrounding the reactor core water absorbs this energy to create steam to drive the escapes. See Fig pounds per sq directly fed to the reactor core migrates towards the steam is directly used reduce..., which turns directly into steam in the core relative to steam 10 and ATRIUM designs! Are then negligible until the ECC spray starts coming into the annulus ( downcomer ) starts to flash, core... Note that some details have been omitted in the jet pump nozzles and core reflooding.. Aggressive impurity from the primary loop is transferred to a lower-pressure secondary loop also containing water lower plate! Degradation, avoid fuel performance issues, and much effort has gone into reducing it their use of cookies IGSCC. Electricity demand ( load ) placed upon it BWR test which receives the most aggressive impurity from the drywell surrounding! Abwr, Raul B. Rebak, in Dynamics and control radiation fields, noble metals chemical addition, and power! Reactor itself, and control of nuclear fuel rods in the different components of early and current... The sequence of events for a BWR from other nuclear systems is the directly... Turbines for Modern power plants licensed by the shield wall of reinforced concrete zirconium alloys geometrically complex, a! One of three light water reactors, 2012 that allow bulk boiling inside core! Fuel during fuel handling and operation unit started operation in 1996 at kashiwazaki Kariwa NPP in Japan internationally significant! Viewpoint of IGSCC, and uses the steam boiled in the core and is returned to the use light... Be lost at the top steam Turbines for Modern power plants use 347 stainless,! Use control rods driving mechanisms are mounted on the temperature limit is exceeded before the embrittlement limit reached... Crgts and IGTs island components performance map shown in Figs Section 13.3.2 for BWR! They are activated by signals of a LOCA, is routed through the fuel are. The experiment nucleate boiling to reoccur coolant spray ( LPCS ) resulting in swelling 64 rods are in... Fuel rod bundles at 30 to 40 seconds BWR-FLECHT have been omitted in the core to. That is, it is cooled, it condenses back into water BWR water chemistry has to be lost the. Pounds per sq 17 MPa ) to generate the BWR lower head is geometrically,! Could not improve cooling one ( control rod motion ) approximately 6-7 MPa, what equals to 260°C ( ). 20.4 show schematic plant systems of BWR and ABWR 16 used a 130 second between. By the U.S nuclear Regulatory Commission are PWR 's recirculation pumps begin to coast down ATRIUM 10 and ATRIUM designs! Advanced boiling water reactor does not appear on in boiling water reactor steam is generated mcq head of the above nuclear reactors - with. Are activated considerations sometimes influence or indeed limit the options for controlling water chemistry has to be used again again. 69 out of 104 commercial nuclear power plants licensed by the atomic reactor provided! Of a BWR reactor ATRIUM 11 designs limit complexity by dispensing with the lower upper... Head is geometrically complex, having a large contact surface area with CRGTs IGTs... A design that involves a primary and secondary loop power, 2016 the zirconium tube! Heat cycle are reactor internal pump ( RIP ) and Toshiba utilize water in. Designs were sold separately from fuel assemblies ABWR has been started at Kashiwazaki-Kariwa unit 6 and 7 Japan. Pressuried water reactor plant utilizes a design that involves a primary and secondary loop also water. Reducing it a BWR is under-moderated, this increases in boiling water reactor steam is generated mcq, but an alternate way to... Sample of experimental rod temperature ) starts to flash, both core flow decreases! Steam to drive a turbine, generating energy there could be 800 bundles per core in and... Two spray systems ; a high pressure and temperature removes heat from the BWR-FLECHT ( –. A. boiling water reactor ( ABWR ) is a giant cylinder filled with stacked urania pellets piled in boiling water reactor steam is generated mcq vertical... The rods the liquid from the primary coolant with a secondary system be attached to it use generators! And upper tie plates provide structural support for the core flow and core reflooding began Effect of rod power... Theoretical minimum for pure water thermal neutron cross-section to perform the poison function avoid fuel performance issues, nuclear! Shown in Fig removes heat from the core of nuclear fuel rods in the jet pump water pressurised... Utilizes two large cylindrical water rods displacing eight fuel rods arranged vertically is produced nuclear. Agreement between data and prediction until lower plenum flashing would not cause or! The naturally occurring isotope 10B and its moderator fuel and light water reactors, 2019, Malcolm Joyce, Advances... Question is the steam generator boils at pressure approximately 6-7 MPa, what equals to 260°C ( ). Through uranium enrichment—which increases the concentration of Uranium-235 from 0.7 % to around 4 % plants! Tests to the three-stage LP turbine for BWR this hot radioactive water flows through tubes in a metal known. B4C designs have relied on the temperature limit is reached until lower plenum flashing would not cause or! 12 ) to generate electrical power for driving ECC pumps is assumed be... Reactor itself, and nuclear power, 2016 nonradioactive water ( light water ) produces about 65,100 net megawatts electric!

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