The AES-2006 reactor plant, a strategic choice

The AES-2006 reactor plant,a strategic choice

The AES-2006 reactor plant,a strategic choiceKey assets to support astrategic choiceEvolutionary, safe and innovativedesign The AES-2006 is a WWER typereactor plant of 1200 MW power.Its design is based on experiencefeedback from severalthousand reactor/years ofWWER NPP operation, it incorporatesthe most recent WWER-1000 technologies, applied toUnit 3 of Kalinin NPP, Unit 2 ofBalakovo NPP, Unit 1 of VolgodonskNPP in Russia, “Tianwan”NPP in China, “Kudankulam”NPP in India. The AES-2006 RP is currently underdevelopment for the sitesof Unit 2 of Novovoronezh NPPand Unit 2 of Leningrad NPP. The AES-2006 RP design integratesthe results of dozens ofR&D. The complex of multipurposedesign solutions is put inthe design basis for implementationof an evolutionary continuityconcept to exclude additionalextensive R&D. The AES-2006 RP has safety systemsthat allow for reducingthe exposure doses of personneland minimizing the releaseof radioactive substances intothe environment under anticipatedoperational occurrences,design basis accidentsand beyond design-basis accidents.The reactor plant is resistantto external hazards, especially,airplane crashes andearthquakes. Safety is ensuredby implementation of a defence-in-depthconcept. Designengineering solutions areaimed at application of inherentsafety properties of WWERreactors.High quality of engineeringsolutions and design documentationis based on applicationof home rules, regulationsand standards in thefield of nuclear power, recommendationsof IAEA, EUR,INSAG, ICRP, IEC and otherinternational recommendations,home rules in thefield of quality assurance,ISO 9001-2000 internationalstandards in the scope thatensures competitiveness atthe foreign market.Continuity in manufacture andconstruction technology The AES-2006 RP is a direct descendantof the well-provenWWER RPs, guaranteeing fullymastered technology. Application of the masteredtechnology excludes any design,manufacture and operatingrisks. The high level of professionalskills of the WWER NPP operatingpersonnel is maintained. Experience in designing, manufacturing,construction and operationof WWER NPPs in Russiaand abroad and PWR abroadis used.Competitiveness is achieved through: Unit electric power is 1200 MW; Efficiency factor (gross) is 35,9 %; Service life of irreplaceable equipment is at least 60 years; Enhanced fuel utilization; Operational factor, averaged, for the entire service life of the NPP is 92 %; Availability factor, averaged, for the entire service life of the NPP is 90 %; Use of up-to-date fuel cycles; Period between refuellings is 24 months; Specific capital investments in industrial construction of the AES-2006 (WWER-1200) NPP do not exceed35500 rouble/kW (prices of 2006), being 20 % lower than those for the WWER-1000 NPP; The electric power generation prime cost (without tax deductions) does not exceed 0,45 rouble/kWh(prices of 2006).23

The AES-2006 reactor plant,a strategic choiceThe AES-2006 RP:safety and technologicalinnovationsProven and safe designMainadvantages ofthe AES-2006 RP Design service life of theRP main equipment is increasedto 60 years withoutnecessity of its replacement. Possibility of further forcingthe reactor thermal powerfrom 3200 MW up to 3300MW by the R&D results toenhance heat exchange inthe core.The design of the AES-2006 RPmeets the high level of safety requiredworldwide for future nuclearpower plants. One of the AES-2006 RP mainfeatures is its simple design, thereactor plant comprises thereactor and four circulationloops, which includes circulationpipelines, reactor coolantpumps and horizontal steamgenerators. Multi-train concept of safetysystems is implemented in thedesign. One safety train can bealways laid up for a long-termrepair. Internal passive safety of thereactor plant, based on the inherentsafety concept, playsthe essential role in NPP safetyassurance. In comparison withPWR, high indices of usage ofthe inherent safety concept,incorporated in design basesof systems and equipment, referto a distinctive feature ofthe AES-2006 RP. It is expressedin RP ability to limit and localizedevelopment of initiatingevents and their consequenceswithin the boundaries of designsafety criteria in case of accidentsfor a long time, first of alldue to properties of WWER reactorpassive safety. The RP main equipment is accessibleto carry out in-serviceinspection and scheduled preventivemaintenance of equipmentin due time. RP lay-out allows effective introductionof means for smallscalemechanization of repairwork, automation of variousmethods for equipment control. Continuity in technology ofmanufacture of equipmentand systems with respect tooperating WWER-1000 NPPsas well as to NPPs commissionedin China and underconstruction in India.Technological innovationsIn addition to the innovative featuresassociated with its reinforcedlevel of safety, the design of theAES-2006 RP benefits from manytechnological innovations. The internal diameter of the reactorvessel is increased by 100mm in the core area to reduceneutron flux on the reactor vessel. The reactor core is compactand practically free from xenonvibrations and has asmooth distribution of neutronflux. Thermal intensity of the reactorcore is low, that providesfor a significant DNBR of fuelrod heat exchange under varioustransients, including accidents. The new design of the steamgenerator with increased vesseldiameter and corridor layoutof tubes in the heat exchangingbundles is applied. The radial-axial bearing withwater lubricant is used in thereactor coolant pump.45

The AES-2006 reactor plant,a strategic choiceWWER-1200 reactorfeaturesSteam generator features in theAES-2006 designThe WWER-1200 reactor design versionis evolutionary in comparisonto WWER-1000 reactors. The maindistinctions, aimed at extension ofdesign service life of the reactorvessel up to 60 years consideringincrease of reactor thermal powerup to 3200 MW, consist in the following: The internal diameter of the reactorvessel is increased by 100mm in the core area to reduceneutron flux on the reactor vessel; The number of CPS control rodsis increased up to 121 pcs.; A new programme for surveillancespecimens is envisaged(arrangement of irradiated surveillancespecimens directlyon the reactor vessel wall); Core cooling conditions in lossof-coolantaccidents are improved(due to increase in thereactor coolant inventory); Radiation doses of personnelare reduced due to applicationof structural materials withthe minimum cobalt content; Nickel content in reactor vesselshrouds is reduced.To enhance operating reliability ofsteam generators a new design ofthe steam generator is used withthe following basic design features: Spaced out corridor lay-outof tubes is applied to heat exchangingbundles; Sealing of all joints of the primaryand secondary side isprovided by expanded graphitegaskets; Easy access to piping from belowis ensured by means of speciallyprovided nozzles. Thus,the SG design is adapted tothe maximum for applicationof automatic means of inspectionand maintenance, bothfrom the primary and secondaryside. Presence of specialnozzles at the SG vessel lowergeneratrix allows a row of processprocedures for examinationand washing of the tubebundle without the personnelinside SG; Except for pipe sleeves of blowdownfrom the “pockets”, onthe coolant collector reducerthere are pipe sleeves availablefor installation of washingdevices to ensure cleanness of“pocket” space due to period-ic washings within preventivemaintenance. Simultaneously,the form of collector-to-vesselwelding joint is optimized to decreasethe level of operationalstresses.Features of the WWER-1200 reactorcore and fuel cycle The reactor core design ensuresoperation in flexible fuelcycles lengths from 12 up to 24months; The core provides possibility forextension of a fuel cycle due touse of temperature and powereffects of reactivity for a termup to 60 days; The core provides RP enhancedsafety by absorber overlappingthe fuel after reactor scram; The core provides increasedfuel burn-up at the level of 70MW day/kgU, on average, atthe maximum burnt out FA; The FA structure is repairableand provides possibility of remotewithdrawal and replacementof a defective fuel rod usingsimple repair tools; Uranium fuel UO 2is used, applicationof uranium-gadoliniumfuel UO 2-Gd 2O 3is also possible; Temperature of recriticality isless than 100°C; The mass of fuel, loaded intothe reactor, is increased due toimprovement of fuel rods.Features of the reactor coolant pumpset in the AES-2006 RP designGCNA-1391, used in the design, is areactor coolant pump with the followingfeatures: The torsion bar with a plateclutch, instead of the gearclutch, is used; The main radial-axial bearingwith water lubricant is used; Under a standby mode heatremoval from the lower radialbearing is provided by naturalcirculation;The motor has the following advantages: Individual system of lubrication; Start-up of the motor up to 750rpm is provided at the beginning,and then changing overto rated speed of rotation 1000rpm is ensured; Oil cooling system due to firerisk is replaced by water cooling.6 The spherical form of weldedstampedvessel is used;7