SOVIETNUCLEARPOWERPLANTDESIGNS

1、Soviet Plant Source Book - 1SOVIET NUCLEAR POWER PLANT DESIGNSKey Factsn Western-style plants employ the design principle of safety in depth,relying on a series of physical barriers including a massive reinforcedconcrete structure called the containment to prevent the release ofradioactive material

2、to the environment. With the exception of theVVER-1000 design, Soviet-designed reactors do not have such acontainment structure.n Soviet-designed reactors are essentially variations on two basic designs:the VVER or pressurized light water type, and the RBMK thegraphite moderated, channel reactor.n T

3、hree generations of Soviet-designed VVER reactors upgraded overtime are operating in Eastern Europe and the former Soviet Union. Thefirst generation the VVER-440 Model V230 operates at four plant sitesin three countries: Russia, Bulgaria and the Slovak Republic. The secondgeneration the VVER-440 Mod

4、el V213 operates at five plant sites infive countries: Russia, Ukraine, Hungary, the Czech Republic and theSlovak Republic. The third generation the VVER-1000 operates ateight plant sites in three countries: Russia, Ukraine and Bulgaria.n At the time of the collapse of the Soviet Union, two advanced

5、 versions ofthe VVER-1000 were under development. Russia has continued the development of an upgraded VVER-1000, and has developed a new design for a 640-megawatt reactor with enhanced safety features.n Three generations of RBMK reactors are operating in the former SovietUnion: 11 units in Russia, o

6、ne in Ukraine and two in Lithuania. Despite improvements to the RBMK design since the Chernobyl accident,concerns remain about these reactors, especially the first-generation ones. Major Difference Between Soviet-Designedand Other Nuclear Power PlantsSoviet Plant Source Book - 2Soviet-designed nucle

7、ar power plants differ from nuclear power plants ofother countries in many respects, including plant instrumentation andcontrols, safety systems and fire protection systems.While Soviet-designed plants like other plants employ the design principleknown in the West as “ defense in depth, ” only one r

8、eactor design includes acontainment structure as part of that principle.In the unlikely event that safety systems fail, plants designed on the “ din depth ” principle rely on a series of physical barriers to prevent the releaseof radioactive material to the environment. At U.S. plants:n The first ba

9、rrier is the nuclear fuel itself, which is in the form of solidceramic pellets. Most of the radioactive by-products of the fission processremain bound inside the fuel pellets.n These pellets are then sealed in rods, made of special steel, about 12 feetlong and half an inch in diameter.n The fuel rod

10、s are inside a large steel pressure vessel, which has wallsabout eight inches thick.n At most plants, this vessel is enclosed in a large, leak-tight shell of steelplate.n All this is contained inside a massive steel and/or concrete structure called the containment with walls several feet thick.Most

11、Soviet-designed reactors employ similar features, but only the VVER-1000 design has a containment structure like that of most nuclear powerplants elsewhere in the world. Without this protection, radioactive materialcould escape to the environment in the event of a serious accident.Plant Location and

12、 Design “ Families ”At present, more than 70 commercial nuclear reactors of Soviet design areoperating or under construction in Russia, Ukraine, Lithuania, Bulgaria, theCzech Republic, the Slovak Republic and Hungary.A two-unit Soviet-designed nuclear plant in Finland was built using theVVER-440 Mod

13、el 213 basic design, but was upgraded to include a Westerninstrumentation and control system and a containment structure.With the exception of small nuclear units used for district steam heating andseveral small fast-breeder reactors which produce fuel as they generateelectricity Soviet-designed com

14、mercial nuclear power plants are variationson two basic designs: the VVER or pressurized light water type, and theRBMK the graphite moderated, channel reactor. There are no RBMKplants operating outside the former Soviet Union.Soviet Plant Source Book - 3Like all nuclear units based on light water te

15、chnology, the Soviet VVER design uses water to generate steam and to cool the reactor. Water also actsas a “ moderator, ” slowing down the atomic particles (neutrons) in the nuclearreaction to increase the chances of fissioning, or splitting. Theeffect of the water adds safety, because a water loss

16、will slow the nuclear chain reaction.In the RBMK design, graphite is used in place of water as a moderator, surrounding vertical pressure tubes which hold the nuclear fuel and the water that will be boiled to steam. Unlike light water units, the RBMK nuclear chain reaction and power output increase

17、when cooling water is lost.This design flaw called a “ positive void coefficient ” caused theuncontrollable power surge that led to the Chernobyl accident. Thecorrections and modifications made to all of the RBMKs since the Chernobyl“ moderasaccident are generally considered to be adequate to preclu

18、de the type ofnuclear excursion a sudden, rapid rise in power level that occurred atChernobyl Unit 4 in April 1986.The Beloyarsk fast-breeder reactor in Russia is the second-largest such unitin the world, behind the French Super Phenix, and generates new fuel as itoperates. The major components of t

19、he Beloyarsk unit are submerged in alarge pool of liquid sodium, which acts as a moderator and transfers heataway from the reactor to boil water to make steam.The VVER: Three Generations of Light Water Reactors,Upgraded Over TimeAlthough it shares a basic engineering concept with its counterparts in

20、 the United States, France and Japan, the Soviet pressurized waterdesign is very different and does not meet Western safety standards. However, second- and third-generation plants of this designModel V213 and VVER-1000 are widely viewed as having a design safetybasis sufficiently comparable to that

21、used in the West to justify short-term and long-term safety and performance upgrades on both safety and economic grounds. However, regulatory requirements and the extent of plant upgrading differ from country to country and plant to plant, resulting in varying levels of safety, even for plants of th

22、e same model. or VVER the VVER-440First-Generation VVERsThe earliest pressurized water nuclear plants were developed by the Sovietsbetween 1956 and 1970. These plants include the following versions:VVER-210 (Prototype)VVER-365 (Prototype)Novovoronezh HYPERLINK l _bookmark1 1Russia (Shut down 1984)No

23、vovoronezh HYPERLINK l _bookmark2 2Russia (Shut down 1990)nSoviet Plant Source Book - 4VVER-440VVER-440 Model V230Novovoronezh 3 and 4(First standardized modelV230s)1) Kola 1 and 2, Russia2) Medzamor 1 and 2 (Shut down 1989; Unit 2 restarted November 1995)3) Kozloduy 1-4, Bulgaria4) Bohunice 1 and 2

24、, Slovak Republic5) Greifswald 1-4 in the former East Germany (Shut down 1990)Principal Strengths:Six primary coolant loops (providing multiple paths for cooling the reactor), each with a horizontal steam generator (for better heat transfer),nnwhich together provide a large volume of coolant. In som

25、e respects this design is more forgiving than Western plant designs with two, three or four large vertical steam generators.Isolation valves that allow plant operators to take one or more of the six coolant loops out of service for repair while continuing to operate the plant. This feature is found

26、in only a few Western plants.Ability to sustain a simultaneous loss of coolant and off-site power, due to coolant pumps and two internal power generators thatnna shutdown.Plant worker radiation levels reportedly lower than many Western plants, due to selection of materials, high-capacity primary coo

27、lant purification system, and water chemistry control.Ability to produce significant amounts of power despite design andinstrumentation and control deficiencies.Principal Deficiencies:n Accident Localization System which serves as a reactor confinementdesigned to handle only one four-inch pipe ruptu

28、re. If larger coolant pipes rupture, this system vents directly to the atmosphere through nine large vent valves. Western nuclear plants have containments designed for rupture of the largest pipes. In addition, the confinement has very small volume, very poor leak-tightness and poor hydrogen mitigat

29、ion.n No emergency core cooling systems or auxiliary feedwater systems similarto those required in Western nuclear plants.“ coast down ” afterSoviet Plant Source Book - 5n Major concern about embrittlement (gradual weakening) of the reactorpressure vessel surrounding nuclear fuel, due to lack of int

30、ernal stainless- steel cladding and use of low-alloy steel with high levels of impurities.n Plant instrumentation and controls, safety systems, fire protectionsystems, and protection for control room operators are below Westernstandards.n Quality of materials, construction, operating procedures and

31、personneltraining are below Western standards.Second-Generation VVERsThe VVER-440 Model V213 was designed between 1970 and 1980. Thedevelopment of this design coincided with the first uniform safetyrequirements drawn up by Soviet designers.VVER-440 Model V213 units in the former Soviet Union include

32、:RussiaUkraineKola 3 and 4Rovno 1 and 2VVER-440 Model V213 units in Central and Eastern Europe include:HungaryCzech RepublicSlovak RepublicFormer East GermanyFinlandPaks 1-4Dukovany 1-4Bohunice 3 and 4Greifswald 5 (Shut down)Loviisa 1, 2 (includes WesternI&C system and containment)Construction of a

33、version of the Model V213 intended for export began inCuba in 1983 but was suspended in 1992.Principal Strengths:n Upgraded Accident Localization System vastly improved over the earlierVVER-440 Model V230 design, comparable to several Western plants, andusing a vapor-suppression confinement structur

34、e called a “ bubbler-condenser ” tower.n Addition of emergency core cooling and auxiliary feedwater systems.Soviet Plant Source Book - 6n Reactor pressure vessel with stainless-steel internal lining to alleviatemuch concern about the vessel embrittlement associated with the earlierVVER-440 Model V23

35、0 design.n Improved coolant pump, and continued use of six coolant loops (providingmultiple paths for cooling the reactor) and horizontal steam generators(for better heat transfer) with large coolant volume.nStandardization of plant components, providing extensive operatingexperience for many parts

36、and making possible incremental improvementsand backfits of components.Principal Deficiencies:nPlant instrumentation and controls for example, reactor protectionsystems and diagnostics behind Western standards. Significantvariations exist among countries with VVER-440 Model V213 plants.nnnSeparation

37、 of plant safety systems (to help assure that an event in onesystem will not interfere with the operation of others), fire protection, andprotection for control room operators improved over Model V230 plants,but generally below Western standards.Poor leak-tightness of confinement.Unknown quality of

38、plant equipment and construction, due to lack ofdocumentation on design, manufacturing and construction, and reportedinstances of poor-quality materials being re-worked at plant sites.n Major variations in operating and emergency procedures, operatortraining, and operational safety (for example, use

39、 of control-roomsimulators) among plants. These aspects of plant operations dependprimarily on the organization or country operating Model V213 plantsrather than on the plant supplier. Some countries have added safetyfeatures to their Model V213 plants.Third-Generation VVERsThe VVER-1000 design was

40、developed between 1975 and 1985 based on therequirements of a new Soviet nuclear standard that incorporated some international practices, particularly in the area of plant safety. The VVER- 1000 design was intended to be used for many plants, and 18 units now operate in two former Soviet republics.

41、Of these, twoSouth Ukraine 1 are prototypes; three are Model V338s Novovoronezh 5 and Kalinin 1 and 2and South Ukraine 2; and all the rest 1, South Ukraine 3 and Zaporozhye 1-6 Balakovo 1-4, Rovno 3, Khmelnitskiy are Model V320s.Soviet Plant Source Book - 7RussiaUkraineBalakovo 1-4Kalinin 1-2Novovor

42、onezh 5Rovno 3Khmelnitskiy 1South Ukraine 1-3Zaporozhye 1-6Two VVER-1000 units were built outside the former Soviet Union:Bulgaria Kozloduy 5 and 6Work was stopped on two other VVER-1000 units in Bulgaria (Belene 1 and2) after public protests over claims of unsuitable soil and seismic conditions.The

43、 Hungarian government canceled Paks 5 and 6 in 1989.Construction of two VVER-1000 units at Stendal, in the former EastGermany, was halted following reunification with West Germany.Two VVER-1000 units under construction at Temelin in the Czech Republicare being upgraded with Western instrumentation a

44、nd control equipmentand fuel.A total of 25 VVER-1000 units are at some stage of construction in the formerSoviet Union 15 in Russia and 10 in Ukraine. But work on 12 of these unitsin Russia, and six in Ukraine, has reportedly been canceled or deferredindefinitely.Of the VVER-1000 units earmarked for

45、 completion under the 1992 Russianplan, Kalinin 3 originally scheduled to come on line in 1995 is expected tobe operational by 2000, according to a Ministry of Atomic Energy official.Other units expected to come on line by 2000 are Balakovo 5, a VVER-1000,and Rostov 1, a VVER-1000 that is reportedly

46、 97 percent complete. A secondunit at Rostov is said to be 95 percent complete, but there is local oppositionto both projects. Russia s new energy law requires the approval of localauthorities for plant construction.Ukraine is seeking funding to complete the construction of two VVER-1000units Khmeln

47、itskiy 2 and Rovno 4.Principal Strengths:n Steel-lined, pre-stressed, large-volume concrete containment structure,similar in function to Western nuclear plants.n“Evolutionary ” design incorporating safety improvements over VVER-440Model V213 plants. The Soviet approach to standardization was based o

48、ncontinued use of components that had performed well in earlier plants.Soviet Plant Source Book - 8nUse of four coolant loops and horizontal steam generators bothconsidered improvements by Soviet designers.n Redesigned fuel assemblies that allow better flow of coolant, and improvedcontrol rods.n Pla

49、nt worker radiation levels reportedly lower than in many Westernplants, apparently due to selection of materials, high-capacity system for purifying primary coolant, and water chemistry control.Principal Deficiencies:n Substandard plant instrumentation and controls. Wiring of emergencyelectrical sys

50、tem and reactor protection system does not meet Westernstandards for separation control and safety functions are interconnectedin ways that may allow failure of a control system to prevent operation of a safety system.n Fire protection systems that do not appear to differ substantially fromearlier V

51、VER models, which do not meet Western standards.n Quality control, design and construction significantly deficient by U.S.standards.n Protection measures for control-room operators essentially unchangedfrom earlier VVER-440 Model V213 design, which does not meet U.S. standards. Unlike all U.S. nucle

52、ar plants, and most in Western countries,VVER-1000s have no on-site “ technical support center ” to serve as acommand post for stabilizing the plant in an emergency. Technicalsupport centers were incorporated in U.S. and many Western nuclearplants following the accident at Three Mile Island Unit 2 i

53、n 1979.n Operating and emergency procedures that fall far short of Westernstandards and vary greatly among operators of VVER-1000 plants.n Higher power densities and the smaller volume of primary and secondarysystems result in a somewhat less forgiving and stable reactor.VVER-1000 DerivativesEven be

54、fore the breakup of the Soviet Union, derivative versions of theVVER-1000 were under development.In 1987, design work was begun on the VVER-1800, a VVER-1000 upgraded for greater safety and economy. The VVER-1800 design incorporated a lower-power reactor core, annual refueling, and more reliable con

55、trol and protection systems.In 1989, Finland and the Soviet Union jointly announced the start of development work on the VVER-91, a VVER-1000 version that would meet stringent Finnish nuclear plant design requirements. On paper, the SovietSoviet Plant Source Book - 9VVER-91 design is among the world

56、 s most advanced light water nuclearpower plants.Development of a new VVER-1000 design, the VVER-92, was expected to becarried out with Western assistance. The VVER-92 incorporated what oneFinnish nuclear expert called “ radically simplified ” plant systems thatincluded active safety systems, a redu

57、ced-power reactor core, and a doublecontainment structure surrounding the nuclear reactor. However, theMinistry of Atomic Energy has reportedly diverted some funding for VVER-92 development to a pilot project for building a smaller advanced VVER, theVVER-640 or Model V407.The RBMK: The Chernobyl-Typ

58、e Soviet Nuclear Power PlantThe former Soviet Union built 17 nuclear units based on the RBMK designused at the Chernobyl nuclear power plant, the site of the world s worstcommercial nuclear accident. There are currently 14 RBMK reactors inoperation: 11 units in Russia, one in Ukraine and two in Lith

59、uania. Theseunits were connected to the grid between 1973 (Leningrad 1) and 1990(Smolensk 3). During these 17 years, the design evolved significantly. Inaddition, following the Chernobyl accident in 1986, some major safetyupgrades were implemented. Today it is generally recognized that there arethre

60、e generations of RBMK nuclear power plants, although even within agiven generation the units can differ substantially.RBMKs in the former Soviet republics include:Russia Leningrad (Sosnovyy Bor) 1-4Smolensk 1-3Kursk 1-4Ukraine Chernobyl 1-4(Unit 4 was destroyed in the 1986 accident; Unit 2 was shut