Module 03 Pressurized Water Reactors (PWR) Generation 3+

Transcription

1 Module 03 Pressurized Water Reactors (PWR) Generation Prof.Dr. Böck Technical University Vienna Atominstitut Stadionallee 2, 1020 Vienna, Austria ph:

2 Flow Diagram of a PWR - Details 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

3 World Nuclear Power Plant Types NPP Types World Totals Pressurised Water Reactor (PWR) 270 Boiling Water Reactor (BWR) 91 Pressurised Heavy Water Reactor 'CANDU' (PHWR) 46 Gas-cooled Reactors 16 Light Water Graphite Reactor (RBMK) 16 Fast Breeder Reactors 2 Total NPP operating 442 *Status , ATW 2016, p 271

4 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

5 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 MW e First EPR is built in Olkiluoto/Finland to be in operation by 2012 delayed to 2018 Two more EPR s to be built in Flamanville/France

6 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

7 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

8 EPR: Evolutionary Design based on Experience from the most recent Reactors Evolutionary development Solid Basis of Experience with Confirmed Performance

9 Evolutionary Design based on N4 and Konvoi NPPs NPPs commissioned in in France: Chooz 1 & MW N4 Civaux 1 & MW N4 in Germany: Neckarwestheim MW Konvoi Isar MW Konvoi Emsland 1290 MW Konvoi

10 Double walled reinforced concrete Reinforced Concrete Shield Building Annulus 1,8 m Prestressed Concrete Containment Building Steel Liner Outside Inside BASEMAT

11 Aircaft Impact on EPR Boeing 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

12 Fighter plane impact on a section of a containmant wall of a US plant

13 Main Technical Data Type of Plant N4 EPR KONVOI Core thermal power (MWth) (4500) 3850 Electrical output (Mwe) No.of fuel assemblies Type of fuel assemblies 17x17 17x17 18x18 Active length (cm) Total F.A.length (cm) Rod linear heat rate (W/cm) No.of control rods Total flow rate (kg/s) Vessel outlet temp ( C) Vessel inlet temp ( C) S.G.:heat exch.surface (m²) Steam pressure (bar) ,5

14 EPR General Lay-out

15 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

16 Horizontal Cross Section

17 Strict Physical Separation

18 Core Catcher

19 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%

20 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

21 Reactor Core Thermal Power 4500 MW th Operating pressure 155 bars Nominal inlet temperature ºC Nominal outlet temperature ºC Active fuel length 4200 mm Average linear heat rate W/cm Number of fuel assemblies 241

22 Initial Core Loading G High enrichment with Gd High enrichment without Gd Medium enrichment Low enrichment

23 Core after several Fuel Cycles

24 Fuel Assemblies Fuel rod array 17x17 Number of rods per assembly 265 Number of guide tubes per assembly 24 Fuel discharge burn-up > MWd/t Rod outside daimeter Cladding thickness Cladding material 9.5 mm 0.57 mm Zircalloy M5

25 Fuel Assembly Number of spacers: 10 Fuel pellets: UO 2 or MOX* with or without GdO 2 as burnable poison (2-8 wt%) 8 to 28 Gd poisoned rods per assembly depending on fuel management scheme *MOX= UO 2 mixed with PuO 2

26 Fuel Assembly Cross Section

27 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 mm Upper part material: B 4 C Outer diameter 7.47 mm Length mm Cladding SST Filling gas Helium Stepping speed 375 mm/min or 750 mm/min Maximal scram time 3.5 s

28 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

29 Main Data Reactor Pressure Vessel RPV is most limiting component can t be exchanged Characteristics Unit Konvoi N4 EPR Design life time y RPV fluid volume m³ RPV total height m RPV inner diameter mm RPV inner diameter under cladding mm None Cladding thickness mm none 7 7,5 RPV body wall thickness mm RPV closure wall thickness mm Distance core outlet Nozzle axis mm Total core zone height mm Active core height mm

30 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

31 Steam Generator Number of steam generators 4 Heat transfer surface per SG m 2 Primary design pressure 176 bar Primary design temperature 351ºC Secondary design pressure 100bar Secondary design temperature 311ºC Number of tubes Overall height Total mass 23 m 500 t

32 Main Data Reactor Coolant System Characteristics Unit Konvoi N4 EPR Design life time y Core thermal loops MW Number of loops Operating pressure bar Design pressure bar ,3 176 Total primary fluid volume m³ Total mass flow rate kg/s 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

33 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

34 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

35 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

36 Special Safety Features of the EPR

37 EPR Olkiluoto OL3 (Finland) in a Nutshell Investment decision and start of the project contract signed: Total budget: about 3 Billion Electric output: approximately 1600 MWe Commercial operation: end of 2018 Contractor: AREVA Plant location: Olkiluoto, 150 km west of Helsinki, two BWR already at this site

38 Olkiluoto Site Layout

39 OL3 Main Structures and Data Thermal power 4500 MW th Electric power 1600 MW e Net efficiency 37 % Building volume: m 3 Excavation volume: m 3 Amount of concrete m 3 Structural steel t

40 January 2004

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42 Summer 2007

43 Summer 2008

44 Placing the dome

45 TVO/Hannu Huovila Summer 2012

46 End of 2012

47 Summer 2015

48 OL1/2/3 Artist view when construction finished

49 Flamanville 3 Sep 2009

50 Flamanville 3 Dec 2011

51 Flamanville 3 Dec 2011

52 Flamanville site

53 References ents/brochure-epr-8pages/areva-8p- EPR%202014_update_09_2014_page.pdf

54 AP 1000 Overview Prof.Dr. H. Böck Atominstitute of the Austrian Universities Stadionallee 2, 1020 Vienna, Austria

55 Pressurized Light Water Reactor Reactor heats water from 279 to 315 deg. C Pressurizer keeps coolant pressure 15.5 MPa; boiling is not allowed

56 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.

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58 Construction Schedule Time from breaking ground to criticality: 5 years Site preparation: 18 month Site construction: 36 month Start up and testing: 6 month

59 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 kw/litre Number of assemblies increased from 121 to 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.

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61 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. High negative temperature coefficient of reactivity

62 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

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64 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.

65 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

66 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.

67 Enhanced Safety Features

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69 Operating Characteristics Withstand the following operations without reactor scram or actuation of safeguard systems - From 15 % % FP, +/- 5 % /minute ramp load change; From 15 % %, +/- 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.

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72 What you should remember Light water as coolant and moderator Uses low enriched UO2 as fuel and Zircaloy as cladding PWR pressure 160 bars, no boiling About 80 kw/lt power density One primary loop and two to four secondary loops Pressurizer keeps pressure constant Control rods enter the core from top About 2/3 of all NPPs are PWR New PWR s with core catcher, fuel cycle up to 24 month, life time up to 60 years

73 References InfDocuments/English/gc58inf-4_en.pdf