Module 03 Pressurized
Water Reactors (PWR) Generation 3+
Status 1.10.2013
Prof.Dr. Böck Vienna University of Technology Atominstitute Stadionallee 2 A-1020 Vienna, Austria ph: ++43-1-58801 141368 [email protected]
Flowdiagram PWR
1 Reactor vessel 8 Fresh steam 15 Cooling water 2 Fuel elements 9 Feedwater 16 Feedwater pump 3 Control rods 10 High pressure turbine 17 Feedwater pre-heater 4 Control rod drives 11 Low pressure turbine 18 Concrete shield 5 Pressurizer 12 Generator 19 Cooling water pump 6 Steam generator 13 Exciter 7 Main circulating pump 14 Condenser
Flow Diagram of a PWR - Details
World Nuclear Power Plant Types 31.12.2012
NPP Types World Totals
• Pressurised Water Reactor (PWR) 266
• Boiling Water Reactor (BWR) 90
• Pressurised Heavy Water Reactor 'CANDU' (PHWR) 47
• Gas-cooled Reactors 18
• Light Water Graphite Reactor (RBMK) 15
• Fast Breeder Reactors 2
• Total NPP operating 438
*IAEA Nuclear Technology Review 2012, p 10, lists 437 NPP
in operation and 65 NPP under construction*
(*http://www.iaea.org/programmes/a2/)
PWR Generation 3+
• EPR by AREVA
• AP 600 and AP 1000 by Westinghouse
• APWR by Mitsubishi
• APR 1400 by South Korea
• ATMEA by AREVA with Mitsubishi
• AES-2006, MIR-1200 by Atomenergoproject
European Pressurized Water Reactor (EPR)
• EPR is a new generation of pressurized water reactors
• New technical safety standards have been implemented
• Electrical power of a EPR is 1600 MWe
• First EPR is built in Olkiluoto/Finland to be in operation by 2012
• Two more EPR‘s to be built in Flamanville/France
European Pressurized Water Reactor (EPR)
• EPR has a containment designed to with-stand military and commercial airplane crashes and major earthquakes
• Heavy components are built at the lowest possible level
• Strict separation of redundant systems
• Maintenance procedures have been taken into consideration at the design for easier access, lower radiation levels and shorter maintenance times
European Pressurized Water Reactor (EPR)
• No evacuation of people needed in case of accident
• Better utilization of uranium and less production of waste
• Designed for 60 years life-time
• Comparable national contribution
• Increased grace periods by enlarged water inventories of primary components
• Improved man-machine interface
Solid Basis of Experience
with Confirmed Performance
Evolutionary
development
EPR: Evolutionary Design based on Experience from the most
recent Reactors
Evolutionary Design based on N4 and Konvoi NPPs
NPPs commissioned in 1988-1999
• in France:
–Chooz 1 & 2 1450 MW N4
–Civaux 1 & 2 1450 MW N4
• in Germany:
–Neckarwestheim 2 1269 MW Konvoi
– Isar 2 1400 MW Konvoi
–Emsland 1290 MW Konvoi
Double walled reinforced concrete
BASEMAT
Prestressed
Concrete
Containment
Building Reinforced
Concrete
Shield Building
Annulus
Steel Liner
1,8 m
Inside Outside
Aircaft Impact on EPR
Boeing 767-400
Wing span: 51 m
Air craft engine separation: 15 m
Results for direct impact: No part of the engine or jet fuel enters the containement
Main Technical Data
Type of Plant N4 EPR KONVOI
Core thermal power (MWth) 4250 4300(4500) 3850
Electrical output (Mwe) 1475 ≈ 1600 1450
No.of fuel assemblies 205 241 193
Type of fuel assemblies 17x17 17x17 18x18
Active length (cm) 427 420 390
Total F.A.length (cm) 480 480 483
Rod linear heat rate (W/cm) 179 155 167
No.of control rods 73 89 61
Total flow rate (kg/s) 19420 22245 18800
Vessel outlet temp (°C) 330 328 326
Vessel inlet temp (°C) 292 296 292
S.G.:heat exch.surface (m²) 7308 7960 540
Steam pressure (bar) 73 78 64,5
EPR General Lay-out
EPR Containment Vertical Cross Section
Thick shell of highly reinforced concrete protecting the inner walls and the inner structures from the direct impact and from resulting vibrations
Horizontal Cross Section
Strict Physical Separation
Core Catcher
Enhanced Economic Competitiveness
• Thermal power increased about 1 %
• Electrical power increased about 10 %
• Efficiency 36 % - 37 %
• Shorter construction times
• Designed for 60 years lifetime
• Better fuel utilization
• Availability up to 92%
Improved Safety Features
• Severe accidents taken into account from the very beginning (Core Catcher)
• Digital I&C with analog backup for key safety functions
• Aircraft crash and major earthquake has been taken into account in dimensioning and layout of containment
Reactor Core
• Thermal Power 4500 MWth
• Operating pressure 155 bars
• Nominal inlet temperature 295.6 ºC
• Nominal outlet temperature 328.2 ºC
• Active fuel length 4200 mm
• Average linear heat rate 156.1 W/cm
• Number of fuel assemblies 241
Initial Core Loading
G High enrichment with Gd
High enrichment without Gd
Medium enrichment
Low enrichment
Core after several Fuel Cycles
Fuel Assemblies
• Fuel rod array 17x17
• Number of rods per assembly 265
• Number of guide tubes per assembly 24
• Fuel discharge burn-up >70 000 MWd/t
• Rod outside daimeter 9.5 mm
• Cladding thickness 0.57 mm
• Cladding material Zircalloy M5
Fuel Assembly
• Number of spacers: 10
• Fuel pellets: UO2 or MOX* with or without GdO2 as burnable poison (2-8 wt%)
• 8 to 28 Gd poisoned rods per assembly depending on fuel management scheme
• *MOX= UO2 mixed with PuO2
Fuel Assembly Cross Section
Control Assemblies
• Number of Rod Cluster Control Assemblies (RCCA): 89
• Number of control fingers per assembly 24
• Lower part material: Ag+In+Cd alloy
• Outer diameter 7.65 mm
• Length 1 500 mm
• Upper part material: B4C
• Outer diameter 7.47 mm
• Length 2 610 mm
• Cladding SST
• Filling gas Helium
• Stepping speed 375 mm/min or 750 mm/min
• Maximal scram time 3.5 s
Control Assemblies
• 37 RCCA control average moderator temperature and axial power distribution - these are subgrouped into 5 rod banks
• 52 RCCA are used as shut down rods
Main Data Reactor Pressure Vessel
• RPV is most limiting component – can’t be exchanged
Characteristics Unit Konvoi N4 EPR
Design life time y 40 40 60
RPV fluid volume m³ 132 140 150
RPV total height m 11864 12621 12708
RPV inner diameter mm 5000 4500 5000
RPV inner diameter under cladding mm None 4486 4885
Cladding thickness mm none 7 7,5
RPV body wall thickness mm 256 225 250
RPV closure wall thickness mm 242 192 230
Distance core outlet – Nozzle axis mm 1862 1630 2190
Total core zone height mm 4830 4810 4825
Active core height mm 3910 4270 4200
Reactor Pressure Vessel
• Reduced RPV embrittlement (larger diameter heavy neutron reflector)
• No penetrations below the nozzles • Reduced number of welds • Low Co content (< 0.06%) results in low
activation
Steam Generator
• Number of steam generators 4
• Heat transfer surface per SG 7 960 m2
• Primary design pressure 176 bar
• Primary design temperature 351ºC
• Secondary design pressure 100bar
• Secondary design temperature 311ºC
• Number of tubes 5 980
• Overall height 23 m
• Total mass 500 t
Main Data Reactor Coolant System
Characteristics Unit Konvoi N4 EPR
Design life time y 40 40 60
Core thermal loops MW 3850 4250 4500
Number of loops 4 4 4
Operating pressure bar 158 155 155
Design pressure bar 175 172,3 176
Total primary fluid volume m³ 400 420 460
Total mass flow rate kg/s 18800 19714 22135
Total coolant flow m³/s 18,8 27,61 31,48
RPV inlet temperature °C 291,3 292,1 295,9
RPV outlet temperature °C 326,1 329,1 327,2
Water consumption of an Average houshold per year 100m³/y
Steam Generator
• Improved version from French N4 reactors
• High steam saturation pressure (78 bars)
• Mass of secondary water increased to obtain SG dry out time of 30 min
• Fully shop built and transported to the site
Safety Injection (SI) and Residual Heat Removal System
(RHR)
• Medium Head Safety Injection System (MHSI) injects water below 92 bars
• Low Head Safety Injection System (LHSI) injects water below 45 bars
• In-containment Refuelling Water Storage Tank (IRWST)
• Accumulator Tanks
• System has dual functions for normal and accident conditions
• Four separate and independent systems
• These four systems are located in four separate buildings with strict physical separation
Containement Heat Removal System (CHRS)
• Prevention of high pressure core melt • Prevention of high-energy corium/water interaction • Containment design with respect to Hydrogen detonation • Corium retention (Core Catcher) • Containment heat removal system and long-term residual heat removal
Special Safety Features of the EPR
EPR Olkiluoto OL3 (Finland)
in a Nutshell
Investment decision and start of the project contract signed: 18.12.2003
Total budget: about 3 Billion €
Electric output: approximately 1600 MWe
Commercial operation: 2014 (NUCNET 211/2011)
Contractor: AREVA
Plant location: Olkiluoto, 150 km west of Helsinki, two BWR already at this site
Olkiluoto Site Layout
OL3 – Main Structures and Data
Fuel Building
Nuclear
Auxiliary
Building
Diesel Building
1+2
Office Building
Access Building
C.I. Electrical Building
Turbine Building
Safeguard
Building 2+3
Diesel
Building 3+4
Safeguard Building 1
Reactor Building
Safeguard
Building 4
Waste Building
Thermal power 4500 MWth
Electric power 1600 MWe
Net efficiency 37 %
Building volume: 950.000 m3
Excavation volume: 450.000 m3
Amount of concrete 250.000 m3
Structural steel 52.000 t
January 2004
Summer 2007
Summer 2008
Placing the dome
Summer 2012
© TVO/Hannu Huovila
OL1/2/3 Artist view when construction finished
Flamanville 3 Sep 2009
Flamanville 3 Dec 2011
Flamanville 3 Dec 2011
August 2012
Flamanville site
References
• www.areva.com
>Press Room>Press Kits>The EPR
• www.tvo.fi/130htm
>English>New NPP Project
• www.ktm.fi
• www.nei.org
• www.world-nuclear.org>Public Information Service
AP 1000 Overview
Prof.Dr. H. Böck Atominstitute of the Austrian
Universities Stadionallee 2, 1020 Vienna, Austria [email protected]
Pressurized Light Water Reactor •Reactor heats water from 279 to 315 deg. C •Pressurizer keeps coolant pressure 15.5 MPa; boiling is not allowed
AP 1000 Design Objectives
• Greatly simplified, the design meets or exceeds NRC safety goals, as well as ALWR Utility Requirements.
• Principal features: -use experience-based components -plant systems simplification -increased operating margin -reduced operator actions -passive safety features -modularity.
Construction Schedule
• Time from breaking ground to criticality: 5 years
• Site preparation: 18 month
• Site construction: 36 month
• Start up and testing: 6 month
Fuel Design
• Rod array: standard 17x17 fuel assemblies.
• Larger core: results in lower (25% less) power density core, normal average PWR core power density is 78.82 kW/litre
• Number of assemblies increased from 121 to 145.
• 264 rods per assembly.
• Lower fuel enrichment (2 - 4 % in three radial region)
• Less reliance on burnable absorbers
• Longer fuel cycle
• 15 % more in safety margin for DNB and LOCA.
Reactor Core & Fuel Design
• Stainless steel radial reflector - reduces neutron leakage - improve core neutron utilization, hence reduced fuel enrichment. Added benefit - reduce radiation damage on reactor vessel, extending design life.
• Reduced-worth control rods (“gray” rods) - to achieve load following capability without substantial use of soluble boron - eliminate the need of heavy duty water purification system.
• Temperature coefficient of core reactivity is highly negative.
Reactor Coolant System
• 2 heat transfer circuits or 2 loops.
• Each loop has one Steam Generator, one hot leg (78 cm inside diameter) and two cold legs (55 cm inside diameter) for circulating reactor coolant for primary heat transport.
• One Pressurizer in primary loop to keep pressure within operational limits
Reactor Coolant & Pump Steam Generators
• Two canned motor pumps mounted directly in the channel head of each Steam Generator.
• No seals - cannot cause seal failure LOCA
• Based on standard Westinghouse technology.
• U-tube SG design, using Inconel 690 for tube material - enhanced reliability - Westinghouse claims less than 1 tube plugged per SG per four years of operation.
Passive Safety Systems
• Requires no operator actions to mitigate design basis accidents.
• Rely on natural forces - gravity, natural circulation, compressed gas; no pumps, fans diesels, chillers used. Only few simple valves, supported by reliable power sources
Passive Core Cooling
• The PCC uses three sources of water to maintain core cooling:
• Core Makeup Tanks (CMTs)
• Accumulators
• In-containment Refueling Water Storage Tank (IRWST)
• All of these injection sources are connected directly to two nozzles on the reactor vessel.
Enhanced Safety Features
Operating Characteristics
Withstand the following operations without reactor scram or actuation of safeguard systems -
• From 15 % - 100 % FP, +/- 5 % /minute ramp load change;
• From 15 % - 100 %, +/- 10 % step load change
• Daily load following
• Grid frequency changes 10 % peak-to-peak, at 2 % per minute rate
• 20 % power step increase or decrease in 10 minutes
• loss of single feedwater pump.
References
• http://www.ap1000.westinghousenuclear.com/
• http://www.iaea.org/About/Policy/GC/GC55/GC55InfDocuments/English/gc55inf-5_en.pdf (=Nuclear Technology Review 2011)
• http://nuclearinfo.net/twiki/pub/Nuclearpower/WebHomeCostOfNuclearPower/AP1000Reactor.pdf
• www.tvo.fi/www/page/etusivu_eu