Module 04

WWER/ VVER
(Soviet designed
Pressurized Water Reactors)
Prof.Dr.
Prof.Dr. H. Böck
Vienna University of Technology /Austria
AtominstituteStadionallee 2,1020 Vienna, Austria
boeck@ati.ac.atVVER=
Veda-Vodyanoi Energetichesky
Reaktor=
Water Cooled Power Reactor
WWER 440/230
WWER 440/213
WWER 1000/320

Common Features of VVERs (1)• Hexagonal fuel assembly cassettes• Horizontal steam generator• Primary circuit and secondary circuit using
different materials• Reduced inspection possibilities of components• Little documentation (440/230)

Common Features of VVERs (2)mainly valid for 440/230• Lack of indepentent control and regulatory
supervision• Quality lack in instrumentation, control and dataprocessing• Not reproducable safety analysis• Low power density due to high ratio of water
volume to thermal power

Common Features of VVERs (3)Technical Aspects of VVERs
for 1st Generation• VVERs are the „workhorses“ of former
Sovietunion• Simple, cheap and robust contructions• Rely more on overdimension than on
sophisticated computer codes• Little automatisation, human reliability is higher
than the reliabilty of I&C systems• Accident prevented with choice of material andmaterial dimension

DevelopmentofVVERs

VVER Fuel Assembly

VVER Fuel Pellets

Refuelling

VVER

New FuelVVER Primary Circuit

VVER Steam Generator

Structure of the steam generators in VVER-440 units
1 - steam generator body, 2 - primary cold leg collector, 3 - primary hot leg collector, 4 - manhole,
5 - heat exchanger tubes, 6 - vertical distance grid, 7- horizontal distance grid, 8 - feedwater pipeline,
9 - separator, 10 - perforated sheet, 11 - steam header, 12 - primary circuit header cover, 13 - secondary circuit
header cover, 14 cover seals for the primary and secondary circuit, 15 - secondary circuit seal cover monitoringlocation, 16 secondary circuit air vent, 17 - primary circuit seal cover monitoring location, 18 - primary circuit air vent,
9 - header periodic blowdown, 20 - steam generator periodic blowdown, 21 - steam generator permanent blowdown,
22 - nozzle, 23 - pipe unions for steam generator level checking.

VVER Generations

WWER 440/230

VVER 440 / 230 Safety Aspects• Six primary loops• Motor driven valves in all six loops• Fuel follower control rods
• Two NPP on one site
• Common turbine generator hall for both NPPs
• Rooms designed to withstand higher pressure instead offull pressure containment• No full capacity emergency core cooling system in caseof main coolant pipe rupture• Accelerated material embrittlement due to fast neutron
irradiation of pressure vessel

VVER 440/213

Legend: 1.Reactor pressure vessel, 2.Steam generator, 3.Refueling machine,
4.Spent fuel pit, 5.Confinement system, 6.Make-up feedwater system, 7.Protectivecover, 8.Confinement system, 9.Sparging system, 10.Check vales, 11.Intake air unit,
12.Turbine, 13.Condenser, 14.Turbine block, 15. Feedwater tank with degasifier,
16. Preheater, 17.Turbine hall crane, 18.Electrical instrumentation and controlcompartments.

VVER 440/213 Safety Aspects• Many safety deficits of VVER 440/230 removed• Pressure suppression system through bubble condensor• Emergency core cooling system designed for maximum
LOCA• Safety systems in 3 x 100% redundancy, separated fromoperational I&C system• Improved fire protection• Separated emergency control room
• Reduction of neutron fluence to pressure vessel wall
• Surveillance system of safety relevant primary components

VVER 1000/320 Safety Aspects• Full pressure containment designed 0.5 MPa• Emergency cooling system designed for whole

spectrum of LOCA
• Improved materials for primary and secondarycomponents• Improved access for reinspection and maintenance• Low leakage core loading to reduce neutron
fluence to pressure vessel wall
• For Temelin only:• Replacement of total I & C system, byWestinghouse• Fuel elements produced by Westinghouse

NPP Temelin• Czech Republic• VVER 1000/320• 2 Reactors• 2 x 981 MWeNPP Mochowce• Slovak Republic• VVER 440/213• 2 Reactors• 2 x 440 MWe

NPP Dukovany• Czech Republic• VVER 440/213• 4 Reactors• 4 x 440 MWe

References• http://www.nti.org/db/nisprofs/russia/reac
tor/power/novovoro.htm• http://www.npp.hu/index-e.htm• http://www.nrc.gov/