In-Service Inspection Program for the SRS Waste Tanks ... - SRS CAB

SRR-STI-2009-00532In-Service Inspection Program forthe SRS Waste Tanks: Update9/01/09Karthik SubramanianSRR, Office of the Chief Engineer1

Acronyms• SRR: Savannah RiverRemediation• SI: Structural Integrity• ISI: In-Service Inspection• Kgal: Thousands ofgallons• Mgal: Millions of gallons• SRNL: Savannah RiverNational Laboratory• SST: Single Shell Tank• DST: Double Shell Tank• VSC: Vapor SpaceCorrosion• GAO: GovernmentAccountability Office• DNFSB: Defense NuclearFacilities Safety Board• TSIP: Tank StructuralIntegrity Panel• SCC: Stress CorrosionCracking• AUT: AutomatedUltrasonic Inspection2

Safety/Security• SRR Committed toSafety and SecurityExcellence• Still THE priority• SRR will continue theSRS safety tradition• Security is like safety:SRR will keep it frontand center3

Outline• Calendar Year 2008 Inspection Results• Waste Tank Design• Structural Integrity (SI) Program• Corrosion Control Program• In-Service Inspection (ISI) Program• SRR Program Status4

CY2008 Inspection Results• WSRC-STI-2009-00352, “Annual RadioactiveWaste Tank Inspection Program – 2008”• 6782 photographs• 1633 visual/video inspections• Two new leaksites identified– Tank 5 (during final cleaning) and Tank 12(duringwaste removal)– Consistent with known degradation mechanisms innon-compliant, old-style Type I/II tanks with partialsecondary containment– Specific response/communication plans during wasteremoval and cleaning activities5

Waste TanksType I (12)Old Style750 kgal1951-1953Type II (4)Old Style1.0 Mgal1955-1956Type IV (8)Old Style1.3 Mgal1956-1960Type III (27)New Style1.3 Mgal1966-1981• (24) Old Style Tanks– Type I/II: partial secondary containment• Routine visual inspections of annulus• Monitor and visually inspect duringwaste removal activities– Type IV: single shell tanks (SST)• Routine internal visual inspections– Up to 50 years old– Do not have full secondarycontainment– (2) have been closed– No active leaksites today• (27) New-Style Tanks– Full secondary containment– No leakage history– Receive all new waste– Used for all processing activities– Comprehensive inspection program• Visual inspections• Volumetric inspection6

Complex-Wide Tank Farm StructuralIntegrity FocusHistory of Tank Farms SICorrosion TechnologyExchange (SRNL)TSIP CommissionedSRS SI Topical Report1s t TFA SI Wo rkshopDST ChemistryOptimization Wo rkshopDST Expert P anelCommissionedVSC Wo rkshop I3rd TFA SI Wo rkshopVSC Wo rkshop IIGAO Report o n HanfordSSTs1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010DOE Order 435.1TSIP ReportDNFSB 2001-1RecommendationHanford DST Liquid LevelWo rkshopTank SI Wo rkshopSST SI P anelCommissioned2nd TFA SI Wo rkshopHanford Life ExtensionPanel8

Corrosion Control Program• Maintain corrosioninhibitors– Envelope of nitrite,hydroxide, nitrateconcentrations• Maintaintemperatures– Concentrationdependenttemperature limitsAnnulus(secondary)Tank WallTYPE III TANKNO LEAKSITESAnnulus(Primary)Tank Wall10

Comprehensive InspectionProgram• Visual Surveillance– Still photography – ( ~5000 photos/year)– Wide Angle– Direct– Video Camera Inspections (over ~1000video/visual exams/year)• In-Service Inspection Program– NDE inspections included remote automatedultrasonic (AUT) inspection supplemented byremote visual inspection.11

• Type I/II tanks– No active leaksitesComprehensive InspectionProgram– Use of conductivity probes in annulus– Routine visual inspections of annulus– Monitor and visually inspect during wasteremoval activities• Type III/IIIA tanks– Comprehensive visual inspection program– Comprehensive volumetric inspectionprogram12

• Visual evidence of changesin tank componentappearance– Leak sites– Corrosion– Abnormal conditionsVisual Inspections13

Ultrasonic Inspections• Historical Volumetric WallMeasurements– Data collection initiated in 1967– Collected over 24,000 spotmeasurements thru 1985• NEW PROGRAM 1 st CYCLECOMPLETED• All 27 Type III tanks inspected withnew program• Examinations look for wall thinning,pitting, and Stress Corrosion Cracking• Type II Tank 15 inspected twice• Inspect primary and secondary walls• Formal methodology for disposition ofresults• Access thru small-diameterriser• On-board cameras14

Ultrasonic Inspection of a Tank1 1(4 Strips)234Probe travels over1 mile during atank inspection15

1 st Cycle Baseline Data• Consistent with understanding ofwaste chemistry and knownmechanisms• One-riser inspections as likely tofind pitting as four-riserinspections• No reportable, service inducedindications (i.e., wall thinning,pitting, or cracking) on the primarytank wall.• Revealed incipient pitting and nonreportableindications on theinterior of the few primary tankwalls.– Most are pre-service• Revealed reportable wallthickness and locally thin areas onthe secondary wall and floor.Inspection Year(FY) /Inspection Type Incipient PittingTank # *IndicationsOne 0.35” diameter25 2004 / A pit 0.036” deep.Four 0.5” diameterpits 0.019 – 0.065”29 2006 / FS deep31 2003 / A32 2003 / FS49 2005 / A* FS = Full Scope A= AugmentedCommentsIsolated, broad shallowpittingIsolated, broad shallowpittingOne ~0.37” diameter Isolated, broad shallowpit 0.046” deep pittingThree pits, max0.75” diameter and Isolated, broad shallow0.055” deep pitting.A band of pitting ~85to 114 inches tankelevation. Up to 0.75”diameter and 0.040”deep.Broad shallow pitting16

Baseline Data: Incipient PittingDefinition• Incipient pitting is a termused to describe smallpit-like indications prior tothem becomingreportable or actionable• The term describes ashallow indication• The term does notnecessarily imply that thepit has recentlydeveloped or that it is stillgrowing• Many incipient pits mayhave developed preserviceTank 49200417

2 nd Cycle ISI Plan• Revised SRS ISI Program for waste tanks inspects all 27Type III/IIIA tanks– Incipient interior tank wall indications– Wall thickness of secondary– Knuckle region in select tanks– High stress region: Tank 50• Frequency– All 27 type III/IIIA tanks shall be inspected every 6-10 years– Tank 15 shall be inspected seven years after the most recentinspection– A formal review of the ISI program shall be performed everythree years• Acceptance Criteria outlines actions in response toindications consistent with national “Tank StructuralIntegrity Panel” recommendations18

2009 Tank 29 Inspection• Special inspection performed on Tank 29to confirm assumption of circumferentialuniformity of service-induced pitting• One-strip inspection covers all historicalinterfaces (e.g., liquid-air) known to be thehighest risk areas for corrosion• Tank 29 inspected through all accessiblerisers (16) to provide the rigorous technicalbases prior to launching of the next cycleof inspections19

• Questions?21