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FeaturesPlatform Designedto Shorten OutageBy being able to perform refueling simultaneously with in-vessel inspection, approximately60 hours of critical path time was saved at Browns Ferry.Following on the heels of theTennessee Valley Authority’s (TVA)Browns Ferry, Unit 3 US recordbreaking14 day outage in 2002, TVAwanted a shorter outage durationfor Browns Ferry 2. In preparing fortheir upcoming spring 2003 outage,Framatome ANP determined thatbeing able to perform refueling atthe same time as in-vessel inspectionswould save time. The companydesigned and built a platform toallow simultaneous performanceof both activities.The project began in late spring 2002when a group of Framatome ANPfield service personnel developed aconcept for a platform to sit underthe refueling bridge. They performeda feasibility study based upon designspecifications to test the conceptbefore developing a cost estimate.In the fall of 2002, Browns Ferryaccepted the proposed solution andconstruction began. Two monthslater, it was delivered to the site andinstalled for the spring outage.In-Vessel InspectionPlatformDesigned to clear all floor interferencesand the refueling bridge, the stainlesssteel platform is supported from therefueling floor by pads attached to eightsupport legs. Measuring approximatelythree feet wide (.91 meters) and40 inches (1.02 meters) tall, the platformsits about 78 inches (1.98 meters)below the refueling bridge and issubmerged approximately 20 inches(.50 meter) at high flood-up level,allowing inspection of reactor internalcomponents by remote camera andultrasonic systems. The sturdy platform,accessed by a ramp, can be installedin a single lift with the inspectionand maintenance equipment loaded.Rather than being a full circle, theplatform forms an arc of approximately330 degrees so that the refuel platformcan traverse freely between the core andspent fuel pool at the same time thatinspections and maintenance are beingperformed. Upon completion of work,the platform is removed for storage.ResultsIt was calculated that the platformshaved approximately 60 hours off criticalpath time. Based upon the BrownsFerry performance, Framatome ANPhas applied for a patent for thein-vessel inspection platform. To satisfythe multi-unit customer, the platformunit is being re-engineered so that asingle platform can be used on multiplereactors with differing dimensions.Framatome ANP believes that thisplatform will assist numerous plants toreduce their refueling floor criticalpath durations. ■16 Advanced Nuclear Power N O 9 November 2003