10 CFR 50.71(e) - Maritime Administration - U.S. Department of ...

U p da te d Fi na lS af et yA n al ys is Re po rt (S T S- 0 x)Updated Final Safety Analysis Report – (STS-004-002)On January 19, 2008, the NSS was placed onto the Titan Drydock at BAE Systems Norfolk ShipRepair. The NSS remained there until March 3. In addition to the routine need to inspect and repairthe ship's underwater hull, MARAD used this maintenance availability to perform a comprehensiveassessment of the physical condition of the ship's primary structure and exterior envelope.As part of the assessment, MARAD entered into an agreement with the American Bureau ofShipping (ABS) to return the ship to hull classification. The ABS will provide independentmonitoring and review of the ship's structural condition.At the previous drydocking availability in 1994, extensive repairs were made to the underwater hullby clad-welding deep pits; renewal of several hundred linear feet of welded butts and seams; andinstallation of steel doubler plates over four areas of generalized erosion and pitting at the "wind andwater" interface.These repairs were subjected to intense survey and inspection by ABS and STS during the 2008drydocking. All of the repairs were found to be in satisfactory condition. Three of the doubler plateswere removed, and several of the underlying locations were inserted with new steel plates. Thefourth doubler plate is located adjacent to the Cold Chemistry Laboratory, and was thus not removedbecause of the need to dismantle the laboratory equipment (with requisite radiological controls) toprovide access for the required hot work in that area.No record of ballast tank or other innerbottom tank inspections was found for the 1994 or thepreceding 1975 drydocking availabilities. Consequently, planning for the 2008 drydockingavailability included inspection and survey of all innerbottom and ballast tanks. All tank surveys andinspections were completed, except for ballast and innerbottom tanks within the ReactorCompartment and the number 4 centerline ballast tank 2 . Ultrasonic thickness gaugings were taken ofthe cargo hold tank tops (a principal structural member of the ship), and the ship's exterior hullstructure. Additional gaugings were taken adjacent to each cargo hatch opening in the main deck; onthe cargo hatch covers themselves, and at selected areas of structural concern and interest. Theresults were satisfactory.The entire exterior surface of the ship was prepared by waterjetting. The underwater hull, freeboardand main deck areas were prepared to bare steel, with all previous and original coating materialsremoved. A new high performance epoxy coating system was applied, with high gloss acrylicurethane topcoat. The underwater hull received one coat of conventional anti-fouling coating. Otherareas of the topside exterior were prepared to a slightly lesser standard, with some original coatingmaterials left intact. All previously existing hydraulic oils and similar materials were removed fromnon-functioning deck equipment, to minimize the risk of discharge of such materials into theenvironment.The exterior envelope of the ship forms the perimeter boundary for licensed activities. Maintenanceof the envelope ensures that the nuclear facilities housed inside the ship are protected. Based on thereview of available records, it is surmised that the 2008 drydocking was the first comprehensiveexamination of the ship's structural fabric since 1967, when the ship underwent "Special Survey No.I" for the ABS.2 The No. 4 centerline ballast tank is filled with water containing chemical compounds of indeterminate origin. Thetank will be inspected at a future date after the water is processed and discharged. Structural inspections werecompleted of the exterior of the tank boundaries and found satisfactory.Rev. VI 15