BWR DescriptionJacopo BuongiornoAssociate Professor of Nuclear Science and Engineering22.06: Engineering of Nuclear SystemsBoiling Water Reactor (BWR) Boiling Water Reactor (BWR) Public domain image from wikipedia.The BWR is a Direct Cycle Plant The BWR is a Direct Cycle Plant St MP 7 136 System pressure, MPa 7.136 Core thermal power, MWth 3323 Electric power, MWe 1130 Thermal efficiency, % 34 Vessel ID / Thickness / Height, m 6.4 / 0.16 / 22g, Core shroud diameter, m 5.2 Number of fuel assemblies 764 Core mass flow rate, kg/s 13702 Core inlet temperature, ºC 278.3 Core outlet temperature, ºC 287.2 Core exit quality, % 13.1 Feedwater flow rate, kg/s 1820 Feedwater temperature, ºC 220 St fl t k / 1820Steam flow rate, kg/s 1820 Steam temperature, ºC 287.2 Core power density, kW/L 50.5 Core flow bypass 14 % A.V. Nero, Jr., A Guidebook to Nuclear Reactors, 1979 Image by MIT OpenCourseWare.Steam lineReactor vesselFeedwaterCoreFeedpumpsDemineralizerCondensatepumpsTurbine generatorSeparators &dryersHeaterRecirculation pumps[MPa]Phase Diagram of WaterPhase Diagram of Water Pressure 737.3 Vapor Vapor 278 288 Temperature [C] Saturation line BWR core LiquidBWR CoreBWR Core Layout BWR Core Layout 0° Fuel Bundle Control Cell Bundle Peripheral Bundle Control BladeControl Blade 270° 90° Typical Control Cell Core Layout 180°180 © source unknown All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.BWR Fuel Assembly BWR Fuel Assembly Upper Tie Plate Channel Fastener Assembly Fuel Cladding Fuel Claddding Expansion Spring Fuel Channel Lower Plenum Spring Tie Plate Nose Piece Fuel Rod Fuel Pellet F l bli h d t ll t P07.cvs Single bundle 3D view uel assemblies have a duct wall to prevent vapor radial drifting Image by MIT OpenCourseWare.© source unknown All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse. FBWR Fuel Assemblies BWR Fuel Assemblies Image by MIT OpenCourseWare.Fuel Assembly Parameters for 9x9 Fuel Assembly Parameter Value Fuel Pellet OD (mm) 9.55 Fuel Pin OD (mm) 11.18 Clad Thickness (mm) 0.71 Fuel Pin Pitch (mm) 14.27 Active Fuel rod height (mm) 3707.9 Total Fuel Rod height (mm) 4178.7 Part Length Rod Height (mm) 2436 Fuel Pins / Water Rods per Fuel Assemblyp y 74/2 Number of Part Length Rods 8 Inner/Outer diameter of the water rods (mm) 23.37/24.89 Duct Thickness (mm) 2.54 Clearance between duct and peripheral fuel rods (mm) 3.53 Clearance between water rods and fuel rods (mm)( ) 1.79 Assembly Outer Dimension (mm) 137.54 Inter-Assembly Gap (mm) 14.86 Average Linear Power (kW/m) 16.46 Pressure Drop (kPa) 160 Average enrichment (wt%) Average enrichment (wt%) 4.314.31 Average Discharge Burnup (GWd/t) 56 Refueling scheme 4 batches Number of rods with gadolinia 8 Gadolinia concentration (wt%) 5 Hydrogen to Heavy Metal Ratio Hydrogen to Heavy Metal Ratio 453 4.53 Void Coefficient (pcm/% void) -144 Fuel Temperature Coefficient (pcm/K) -1.7 Approximate Assembly Weight (kg) 281Control BladeControl Blade Image removed due to copyright restrictions.Image by MIT OpenCourseWare.BWR Control Rod Drive System BWR Control Rod Drive System Image by MIT OpenCourseWare.BWR SPATIAL CORE PROPERTIES (WITH CONTROL RODS PARTIALLY INSERTED) Relative powerAverage void fractionCritical heat flux ratioin hot channel x0.11.51.00.500 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0Relative axial lengthRelative parametersBottom of core Top of coreImage by MIT OpenCourseWare.POWER IN FRESH FUEL ASSEMBLY AS ADJACENT COCONTROOL ROD ISS WITHDRAAWN TOOWARD BOOTTOM O A O “BWR/6: General Description of a BWR,” GE, 1980. Nodal power normalized to 1.0 over the core.(Bottom).2.4.6.81.01.21.41.61.8(Top)Axial Length of Fuel17 25 33 42 50 58 0Percent FullInsertion67Relative Power670Image by MIT OpenCourseWare.Connection of BWR Core Desiggn to Neutronics Why are the fuel rods spaced out more in a BWR than in a PWR? Why are the fuel rods spaced out more in a BWR than in a PWR? Why is the core power density lower in a BWR core than in a PWR? What is the purpose of spatial fuel enrichment zoning throughout a BWR fuel assembly? What function do the water rods perform? h h ldi df hb fhWhy are the BWR control rods inserted from the bottom of the core? Can dissolved boron be used as a means to control reactivity in a BWR core?BWR Bundle Design Advances BWR Bundle Design Advances Extended burnup features  More fuel ppins ((1010)) for a lower heat flux  Heavier fuel loadings Improved mechanical performance  “Barrier” cladding  Low growth, wear resistant materials Improved operational performanceImproved operational performance  Natural uranium blankets  Flow mixing grids to enhance margin to critical power  Part-Length Fuel Rods (Stability, SDM)  Large Central Water Channels (Stability,y, SDM)) (  Sophisticated poison & enrichment zoning Control RodFuel RodPart Length Fuel RodImage by MIT OpenCourseWare.© source unknown All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.BWR Vessel and Vessel BWR Vessel and Vessel InternalsBWR Vessel BWR Vessel Vessel bottom head accommodates CR penetrations Large vessel made of ring forgings to avoid welds in the core region ABWR RPV beltline forging, weight: 127 tons; dimensions: From: L.E. Fennern, ABWR Seminar – Reactor, 7.48 m outside diameter, 7.12 m inside diameter, 3.96 m high; Core & Neutronics. April 13, 2007. material: ASME SA 508, Class 3 EQ. © source unknown. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.BWR Vessel Internals BWR Vessel Internals From: V. Shah, P. MacDonald, Aging and Life Extension of Major LWR Components, 1993. © Elsevier. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.Source: Shah, V. N. and P. E. MacDonald. Aging and Life Extension of Major Light Water Reactor Components. Atlanta, GA: Elsevier Science, 1993. ISBN: 9780444894489.Steam Separators Steam Dome Steam Dryer Height Steam Dryers Drain Pipes Steam + Droplets From: V. Shah, P. MacDonald, Aging and Life Extension of Major LWR Components, 1993. © Elsevier. All rights reserved. This