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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 boeck@ati.ac.at

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 boeck@ati.ac.at

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