Framatome ANP - AREVA

FeaturesOskarshamn 1:Fit for Another 20 YearsOskarshamn 1Nuclear Power Station.At Sweden’s oldest nuclearpower plant, Oskarshamn 1(475 MWe), an extensive “MOD”modernization program wascompleted recently, enablingthe 30-year-old BWR unit tooperate economically for at leastanother 20 years.Concept Developedby Framatome ANPThe goals of the modernizationprogram originally defined in 1996 –namely, to extensively upgradeOskarshamn 1 and thereby enhanceplant safety – were implemented withgreat success. Framatome ANPdeveloped a modernization conceptwhose key features included strictphysical separation of redundantsubsystems, greater diversity ofequipment design, and independenceof safety systems from those used fornormal plant operation. Theseconcepts were accepted, withoutchanges, by the Swedish licenseauthority and the operator. The workincluded the design and installation ofa brand new two-train low-pressureemergency core cooling system(ECCS) and modifications to thehigh-pressure system for emergencycore cooling to ensure consistentseparation of the redundant trains aswell as independence from the nonsafetysystems. In the future, four newbypass valves installed in parallel withthe existing safety-relief valves willguarantee not only safe and reliabledepressurization of the reactor but alsodiversity of equipment design for thereactor pressure limitation function.Implementation of the new safetyconcept additionally requiredinstallation of new emergency powerswitchgear along with two newemergency diesel generators plus acompletely new four-channel reactorprotection system, provided by adifferent vendor based on FramatomeANP’s specifications.Large Scope of SupplyIn addition to the various systemupgrades, Framatome ANP’s scopeof supply also included design anderection of a new emergency controlbuilding to accommodate parts ofthe new ECCS, the new reactorprotection system, the new emergencypower switchgear and two newemergency diesels. The actual work onsite took around 13 months tocomplete. Despite the fact that anadditional order for backfitting a largepipe whip restraint – received shortlybefore the scheduled restart of theplant in November 2002 – led topostponement of the original restartdate, Framatome ANP’s on-sitepersonnel worked nights andweekends to ensure a return tocriticality by Christmas 2002,getting the plant back on line byJanuary 2, 2003.Framatome ANP’s successful planningand execution of the Oskarshamn 1modernization program furtherillustrates its extensive expertisefor complex backfitting andmodernization tasks. More than120 engineers from variousengineering disciplines were involvedin the project, with team and projectmanagers being supported bystate-of-the-art project managementtools and techniques.Oskarshamn 1: A MajorEnergy SupplierOskarshamn 1 plays a major rolein meeting the current high demandfor electricity in Sweden and theinterconnected Nordic power system.Extremely low temperatures in theregion this winter created ademand for power that could notbe met by hydropower plants dueto below-average precipitationin the summer and fall of 2002. ■Commissioning of new ECCS14 Advanced Nuclear Power N O 7 April 2003