статья (VVER)

ROSATOMWater Water Energetic Reactor (VVER)Rosatom subsidiary OKB Gidropress is the designer ofa class of Russian Pressurized Water Reactor calledVVERs. The plants housing the VVER reactors are createdby the design organizations within ROSATOM: MoscowAtom-energoproekt, Saint-Petersburg Atomenergoproekt,and Nizhniy Novgorod Atomenergoproekt. Over 60 VVERunits have been constructed by Russian companiesacross the globe since the mid-1960s, exporting a nucleartechnology that has been domestically tested and proven.Modern VVER units are designed to face the currentchallenges of the nuclear industry by reducing capital costs,shortening construction periods, increasing efficiencyand load factors, as well as implementing load-followingcapabilities.

Furthermore the designers try to implementthe effective use of VVERs in closed fuel cycles. Currentlyavailable large, PWR type models of the VVERs includethe 1000 MWe AES-92 and the 1200 MWe AES-2006.Each reactor model can be fitted with components specificto regulatory or utility needs.Main Design FeaturesA number of unique concepts and construction materials areincorporated in the VVER designs. Plants containing VVERreactors employ horizontal steam generators with relatively thickwalled steam generator tubes made of stainless steel. Steamgenerators in Russian plants have been successfully operatingfor over 40 years without the need for replacement. In addition,these type reactors utilize hexagonal fuel assemblies with afuel rod cladding of zirconium-niobium alloy.

During the designof some large components, efforts have been made to ensuretransportability of the main equipment by rail. VVER reactorvessels lack penetrations in the reactor lower head, increasingtheir integrity in situations where severe core degradation or coremelt is envisioned. The shells of the vessel are forged withoutlongitudinal welds, thus enabling in less frequent maintenanceand surveillance tests on the RPV.VVER-1000 (AES-91 & AES-92)Artist’s version of Novovoronezh NPP II,Russia, housing a VVER-1200 unit.(Courtesy of Rosatom)14LWRCapacityCoolantModeratorLight Water Light WaterFuelTemperature1060 MWe305 °CLEUCapacityPressureEnrichment3000 MWt15.7 Mpa4.55 %Design LifeEfficiencyFuel Cycle60 Yrs33.7 %18 MosV-412Kudankulam 1, 2V-428MTianwan 3, 4VVER-1200 / AES-2006Schematic view of VVER1000 Primary(Courtesy of Rosatom)Main Safety FeaturesVVER units are designed in various sizes and models, but generallythey can be distinguished by their electric output and safety systems,that are tailored to national regulation.

The VVERs use multiplebarriers and defence-in-depth concepts to minimize the risk ofharmful radiological releases to the environment. The distinctivedesign features that were part of earlier VVER reactor designs arebeing adopted today across the entire nuclear industry as inherentreactor protection mechanisms. Today’s VVERs depend on largecoolant volumes with increased secondary feedwater volumesto aid the cooling capability of the core via natural circulationmechanisms. Design features such as the large coolant volumeabove the core and increased primary inventory act as a dampingmechanism for operational transients.

These features slow theinitiation, progression and releases of fission products in accidentscenarios.The early VVER-1000 is a 1000MWe PWR design producedduring the 1980’s. It was one of the first designs to utilize naturalforces for passive safety systems and reactor protection. TheVVER1000 type reactors were based on the older VVER440designs, drawing from years of operating history. Provendesign features from the smaller plants were scaled up to fit thelarger requirements associated with the higher thermal output.The primary systems of these big reactors were based on aconventional 4-loop design with improved horizontal steamgenerator designs.

The use of new cobalt-free materials withlower neutron activation led to significant reduction of exposurerates for radiation workers. Modern VVER1000s are equippedwith passive ECCS and HRS for reactor protection.The VVER1000 reactor is designed to operate at 33.7%efficiency with a 90% availability factor with a design life of50 years. There are three VVER1000 reactors currently beingconstructed around the world at two different sites. The firstmodel called the AES91 (VVER-1000/V-428M) complies withthe European Safety Standards, as it was originally designedfor construction in Finland. Two units are currently underconstruction in Tianwan, China. The other model is called theAES92 (VVER-1000/V412) was designed for India. Currentlythere is one AES92 unit in operation in Kudankulam, India andone unit still under construction.Construction of VVER1200Novovoronezh NPP II, Russia [2]In 2006 Rosatom finalized the designs for the VVER1200/AES2006, their most advanced deployable PWR design.

Theseplants are designed to utilize previously proven technologiesfrom the VVER1000 series to lower capital and constructioncosts, while maintaining high safety standards using active andpassive safety systems. The AES2006 is designed according tothe Russian Regulatory Standards and is also in compliance withthe European Utility Requirements.

It is predicted to have a CDFof 10-6 /RY. Primary systems are very similar to the VVER1000series, consisting of a 4 loop design. The 1170 MWe VVER1200reactors are expected to have an efficiency of 34%, an availabilityfactor of over 90% and an expected service life of 60 years.Refuelling outages can be set between 12-18 months with anaverage BU of 60-70 GWd/t. Modular construction techniqueshave optimized predicted construction times to around 54months.

In addition to the safety feature of the AES91/92 theAES-2006 has passive HRS for the containment and steamgenerators in the unlikely case of BDBA allowing independenceand safe cooling for 72 hours without external power supply.There are two families of AES-2006 designs which are tailoredto different national regulatory standards. The VVER1200/V392M version was developed by Moscow Atomenergoproekton the basis of the AES-92 design.

The reactors are beingbuilt at Novovoronezh II, Russia. The other family of AES-2006(VVER-1200/491) designs was developed by Saint-PetersburgAtomenergoproekt on the basis of the AES-91 originallydeveloped for Tianwan, China. VVER-1200/491 plants are underconstruction in Russia at Leningrad II and Baltic.LWRCoolantModeratorLight Water Light WaterCapacityTemperatureFuel1170 MWe313.5 °CLEUCapacityPressureEnrichment3200 MWt16.2 MpaDesign LifeEfficiencyFuel Cycle60 Yrs33.9 %18 Mos4.79 %V-392MNovovoronezh II 1, 2V-491Leningrad II 1, 2Baltic 115ROSATOMVVER1500Rosatom’s most recent design has benefited greatly fromthe worldwide successful construction of their VVER1000and VVER1200 series.

In anticipation of the increasing trendof electricity consumption around the world and the benefitsfrom the economics of scale, a large PWR was designed withan electric output of 1560MWe. The new design complieswith modern safety regulation, codes and standards as wellas with the Russian and Euroatom regulatory standards.Main aspects of the design are high competitive ability onthe global energy markets while maintaining high safety andoperational reliability through the operational feedback fromearlier projects. Major design features include extensiveuse of passive safety systems, tolerance to human errors,design lifetime of 50-60 years and large operational flexibility.Maximum fuel burnup is 70 GWd/t with a fuel cycle durationranging between 12 and 24 months.Kudankulam 1, 2 - IndiaAES92 (VVER-1000/V412)16VVERFuelLWRCoolantModeratorLight Water Light WaterCapacityTemperatureFuel1560 MWe316 °CLEUCapacityPressureEnrichment4250 MWt15.7 Mpa4.92 %Design LifeEfficiencyFuel Cycle50 Yrs35.7 %24 MosNovovoronezh II 1 - RussiaAES-2006 (VVER1200/V392M) [2]Tianwan 3, 4 - ChinaAES91 (VVER-1000/V-428M) [3]VVER1000VVER1200VVER1500Thermal Output (MWt)300032004250Electric Output (MWe)107012001560Design Life (yrs)506050Plant Efficiency33.7%33.9%35.7%Availability Factor>90%>92%>93%Construction Time (mos)465454Operator Action Time6 hrs6 hrs>6 hrsLoad FollowingYesYesYesOccupational RadiationExposure (Sv/RY)0.50.39TBDCDF (/RY)0.6×10<10<10-6-6-6VVER fuel is produced by the Rosatom subsidiary TVEL.