Information Notice 1995-08, Inaccurate Data Obtained with Clamp-On Ultrasonic Flow Measurement Instruments

Inaccurate Data Obtained with Clamp-On Ultrasonic Flow Measurement Instruments

ML031060366
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	01/30/1995
From:	Grimes B K Office of Nuclear Reactor Regulation
To:
References
IN-95-008, NUDOCS 9501240226
Download: ML031060366 (12)

X '..UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555January 30, 1995NRC INFORMATION NOTICE 95-08: INACCURATE DATA OBTAINED WITH CLAMP-ONULTRASONIC FLOW MEASUREMENT INSTRUMENTS

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.PurDoseThe U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert addressees to difficulties in accurately measuring flow rateswith clamp-on ultrasonic flow measurement instruments. It is expected thatrecipients will review the information for applicability to their facilitiesand consider actions, as appropriate, to avoid similar problems. However,suggestions contained in this information notice are not NRC requirements;therefore, no specific action or written response is required.DescriDtion of CircumstancesO October 14, 1993, while performing a high head safety injection (HHSI) flowbalance test, the licensee for North Anna Unit 2 determined that the as-foundsafety injection cold leg branch line flow rates did not meet the technicalspecification requirements. The as-found cold leg branch line flow rates hadalso failed to meet the technical specification requirements during theprevious test in April 1992.The North Anna Technical Specifications give limits related to both minimumand maximum safety injection line flow rates. For North Anna, these twotechnical specification limits resulted in an very narrow allowed operatingband, which required the use of highly accurate flow measurement instrumentsfor flow tests.The licensee performed the flow balance using System 990 Uniflow UniversalTransit-Time Flowmeters manufactured by Controlotron of Hauppauge, New York.The Uniflow flowmeter is a clamp-on non-intrusive portable flowmeter that usesmulti-pulse, transit-time ultrasonic technology to measure precisely the flowrate. The flowmeter induces alternate upstream and downstream ultrasonicsignals and measures the difference in transit times. This information isthen used to determine the axial fluid velocity and the flow rate through thepipe. Inaccuracies associated with the use of these instruments at North Annacombined with the narrow band of allowable flows caused problems whichcontributed to the failure to meet technical specification requirements.P4 R I r p.# sCC 's9501240226UtjxW ¢ vv -31-15 lk 0 (t v-' IN 95-08January 30, 1995 DiscussionThe licensee examined the 1993 North Anna Unit 2 flow balance test data andobserved that some of the data indicated that the instrument errorssignificantly exceeded accuracies assumed for the tests. Numerous factors mayaffect the accuracy of this flowmeter including pipe dimensions, fluid floweffects, transducer mounting, and instrument setup and operation. After thetest, the licensee investigated and concluded that the instrument inaccuracymost likely was caused by flow effects associated with the pipingconfiguration. The piping arrangement, which contained several out-of-planebends that forced the flow to change direction numerous times before enteringthe straight section of pipe containing the ultrasonic transducers, may havecaused a stable swirl-type flow profile corkscrewing down the pipe. Thelicensee postulated that the swirl flow added a radial flow error to the testinstruments. The flowmeter was calibrated assuming a primarily axial flowprofile. In subsequent testing at a national laboratory, Controlotronultrasonic flowmeter data varied up to 5% at different orientations around thepipe at a position approximately 15 pipe diameters downstream of a singlebend. The test configuration did not include any out-of-plane bends,indicating that it is also possible for a non-uniform flow profile to exist inthe absence of out-of-plane bends, causing flow measurements with larger thanexpected errors.The licensee noted that the instrument output during the test did not give anyindication of measurement problems. The instruments displayed little noiseand only the expected small-magnitude random flow fluctuations. The lack oferratic instrument readings could easily be interpreted as meaning thereadings were valid (i.e., within the stated accuracy). However, the licenseetested the instrument and determined that it could register a stable readingwhile a significant error was occurring. Therefore, the licensee concludedthat repeatability of the data does not prove that the flow has been measuredaccurately.After the test failure, the licensee found several inconsistencies in the testdata which indicated problems in data accuracy. As an example, when theA HHSI pump replaced the C HHSI pump as the operating pump, without any otherchanges in system resistance, the B cold leg flow rate increased by8.4 percent while the A cold leg flow rate increased by 1.5 percent and theC cold leg flow rate did not change. The licensee concluded that these valuescorresponded to an implausible change in the highest cold leg flow path fromloop A to loop B when the sole change was which injection pump was operating.In addition, the head curve for the A HHSI pump was lower than that for the I In-' IN 95-08January 30, 1995 C HHSI pump; thus, the A HHSI pump would be expected to supply flow rates lessthan the C HHSI pump for the same system resistance. However, the ultrasonicinstruments indicated that the A HHSI pump delivered 3.3 percent more flowthan the C HHSI pump. This was contrary to the previously measured pump headcurve data. At the same time, installed plant process instruments indicatedthat the A HHSI pump delivered 3.4 percent less flow than the C HHSI pump, ameasurement consistent with the pump curves.The licensee could not determine with certainty the factors that resulted inthe unanticipated measurement errors in this event. Conditions specific to anapplication can cause deviations from the vendor-supplied instrumentaccuracies. However, during the investigation the licensee developed methodsthat could be used to determine when the ultrasonic flowmeter may not yieldthe assumed accuracy. These methods include comparing ultrasonic flowmeterdata from several locations or different orientations at the same location orby comparing the data from these instruments with data from permanentlyinstalled instruments. Test results can also be compared with expected systembehavior.The NRC staff has approved a request from the licensee of the North Anna plantto modify the technical specification that specifies the acceptance criteriafor the HHSI pump flow rates. The change removes the specific fixed valuesfor the flow from the technical specifications and permits the licensee toestablish allowable values by analysis, providing greater operationalflexibility. The licensee is also planning to (1) install permanent flowinstrumentation that will supply highly accurate data for future flow balancetesting and (2) supply training concerning the accuracy of clamp-on ultrasonicflowmeters to the personnel who use them.Licensees frequently use flow measurements to demonstrate that safety-relatedcomponent performance is adequate to meet the demands indicated by theaccident or transient analyses. Therefore, obtaining accurate flowmeasurements is important to safety. When balancing the flow of HHSIinjection paths, flow rates need to be accurately measured to demonstrate thatthe unit complies with the assumptions in safety analyses and is operated inan analyzed condition. At North Anna the licensee initially failed to detectinaccurate flow data because of a failure to verify the consistency,repeatability and reasonableness of the data from the ultrasonic flowmeasurement instruments. Although technical specification requirements werenot met at North Anna, the licensee later analyzed the issue and concludedthat the HHSI system would have performed its design safety functio s '-' IN 95-08January 30, 1995 This information notice requires no specific action or written response. Ifyou have any question about the information in this notice, please contact oneof the technical contacts listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.ran K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts: Donald R. Taylor, RII Larry W. Garner, RII(703) 894-5421 (404) 331-4663Hukam C. Garg, NRR(301) 504-2929

Attachment:

List of Recently Issued Information Notices

.Re-ttachmentIN 95-08January 30,Page I of 11995LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to95-07Radiopharmaceutical VialBreakage during Preparation01/27/95All USNRC medical licenseesauthorized to use byproductmaterial for diagnosticprocedures.95-06Potential Blockage ofSafety-Related Strainersby Material Brought InsideContainment01/25/95All holders of OLs or CPsfor nuclear power reactors.95-05Undervoltage ProtectionRelay Settings Out ofTolerance Due to TestEquipment Harmonics01/20/95All holdersPermits forreactors.of Constructionnuclear power95-0495-03Excessive Cooldown andDepressurization of theReactor Coolant SystemFollowing a Loss ofOffsite PowerLoss of Reactor CoolantInventory and PotentialLoss of Emergency Mitiga-tion Functions While ina Shutdown ConditionProblems with GeneralElectric CR2940 ContactBlocks in Medium-VoltageCircuit BreakersDOT Safety Advisory:High Pressure AluminumSeamless and AluminumComposite Hoop-WrappedCylinders01/19/9501/18/9501/17/9501/04/95All holders of OLs or CPsfor nuclear power reactors.All holders of Ols or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All U.S. Nuclear RegulatoryCommission licensees.95-0295-01OL -Operating LicenseCP = Construction Permit

> S 95-08January 30, 1995 This information notice requires no specific action or written response. Ifyou have any question about the information in this notice, please contact oneof the technical contacts listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Original signed byBrian K. Grime!Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts:Donald R. Taylor, RII(703) 894-5421Larry W. Garner, RII(404) 331-4663Hukam C. Garg, NRR(301) 504-2929

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List of Recently Issued Information NoticesDOCUMENT NAME: 95-08.INNOTE: VENDOR COMMENTS RECEIVED, NO SIGNIFICANT CHANGES WERE MADEOFFICE *RPB:ADM by Email *OGCB:DORS *RIIby Phoncon *DRP:RIIby Phoncon,AME TechEd AJKugler DRTaylor LWGarnerDATE 09/07/94 09/13/94 09/22/94 09/22/94OFFICE *DRP:RI Iby Phoncon *HICB:DRCH *C/HICB:DRCH *D/DRCHNAME DMVerrelli HCGarg JSWermiel BABogerDATE 09/27/94 09/, W94 / 09/22/94 09/22/94OFFICE C/OECB:DOPS OP /NAME AEChaffee* Arxi esDATE 11 /22/94 01&1y 95 TOFFICIAL RECORD COPY

-IN 95-XXJanuary XX, 1995 This information notice requires no specific action or written response. Ifyou have any question about the information in this notice, please contact oneof the technical contacts listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts: Donald R. Taylor, RII(703) 894-5421Larry W. Garner, RI!(404) 331-4663Hukam C. Garg, NRR(301) 504-2929

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List of Recently Issued Information NoticesDOCUMENT NAME:S:\DOPS_SEC\CLAMP-ON.INRmnTE- VENDOR COMMENTS RFCFTVFD NO SIGNIFICANT CHANGES WERE MADEOFFICE *RPB:ADM by Emai t *OGCB:DORS *RIIby Phoncon *DRP:RIIby PhonconNAME TechEd AJKugler DRTaylor LWGarnerDATE 09/07/94 09/13/94 09/22/94 09/22/94OFFICE *DRP: RIIby Phoncon *HICB:DRCH *C/HICB:DRCH *D/DRCHKANE DMVerrelli HCGarg JSWermiel BABogerDATE 09/27/94 09/19/94 09/22/94 09/22/94OFFICE C/OECB:DOPS D/DOPSNAME AEChaffee* BKGrimesDATE 11/22/94 11/ /94 _ _ _ _=OFFICIAL RECORD COPY

<-/IN 94-XXNovember XX, 1994 This information notice requires no specific action or written response. Ifyou have any question about the information in this notice, please contact oneof the technical contacts listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts: 'onald R. Taylor, RII(70 ) 894-5421Lar y W. Garner, RII(40 ) 331-4663Huk C. Garg, NRR(30 ) 504-2929

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List of Recently Issued Information NoticesDOCUMENT NAME:S:\DOPSSEC\CLAMP-ON.INRMnTr- vrTnnn rnMMFNTq RFCFIVFED NO SIGNIFICANT CHANGES WERE MADEOFFICE *RPB:ADM by EmaiL *OGCB:DORS *RI Iby Phoncon *DRP:RI Iby PhonconNAME TechEd AJKugler DRTaylor LWGarnerDATE 09/07/94 09/13/94 09/22/94 09/22/94OFFICE *DRP:RI Iby Phomon *HICB:DRCH *C/HICB:DRCH *D/DRCHOMWE DMVerrelli HCGarg JSWermiel BABogerDATE 09/27/94 09/19/94 09/22/94 09/22/94OFFICE C/OECB:DOPS D/DOPSNAME AEChaffee* BKGrimes _ _,11/22/94 11/ /94OFFICIAL RECORD COPY IN 94-XXNovember XX, 1994 This information notice requires no specific action or written response. Ifyou have any question about the information in this notice, please contact oneof the technical contacts listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts:Donald R. Taylor, RII(703) 894-5421Larry W. Garner, RII(404) 331-4663Hukam C. Garg, NRR(301) 504-2929

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List of Recently Issued Information NoticesNOTF VFNDOR COMMENTS RECEIVED. NO SIGNIFICANT CHANGES WERE MADEOFFICE *RPB:ADM by Email *OGCB:DORS *RIIby Phoncon *DRP:RIIby PhonconNAME TechEd AJKugler DRTaylor LWGarnerDATE 09/07/94 09/13/94 09/22/94 09/22/94OFFICE *DRP:RIIby Phoncon *HICB:DRCH *C/HICB:DRCH *D/DRCHNAME DMVerrelli HCGarg JSWermiel BABogerDATE 09/27/94 09/19/94 09/22/94 09/22/94OFFICE C/OECB:DOPS D/DOPSNAME AEf ffeBKGrimesDATE 11/2494 Af 11/ /94 __IDOCUMENT NAME:G:\IN\CLAMP-0N.INK IN 94-XXNovember XX, 1994 This information notice requires no specific action or written response. Ifyou have any question about the information in this notice, please contact oneof the technical contacts listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Project SupportOffice of Nuclear Reactor RegulationTechnical contacts:Donald R. Taylor, RII(703) 894-5421Larry W. Garner, RII(404) 331-4663Hukam C. Garg, NRR(301) 504-2929

Attachment:

List of Recently Issued NRC Information NoticesNOTE: VENDOR COMMENTS RECEIVED, NO SIGNIFICANT CHANGES WERE MADEOFFICE *RPB:ADM by Email *OGCB:DORS *RIIby Phoncon *DRP:RIIby PhonconNAME TechEd AJKugler DRTaylor LWGarnerDATE 09/07/94 09/13/94 09/22/94 09/22/94OFFICE *DRP:RII by Phocon *HICB:DRCH *C/HICB:DRCH *D/DRCHNAME DMVerrelli HCGarg JSWermiel BABogerDATE09/27/94 09/19/94 09/22/94 09/22/94OFFICE C/OECB:DOPS D/DOPSNAME AEChaffee BKGrimesDATE .11/ /94DOCUMENT NAME: t:\IN\CLAMP-ON.IN IN 94-XXSeptember XX, 994This information notice requires no specific action or written response. Ifyou have any question about the information in this notice, please contact oneof the technical contacts listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts:Donald R. Taylor, RII(703) 894-5421Larry(404)W. Garner, RII331-4663Hukam(301)C. Garg, NRR504-2929

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List of Recently Issued Information NoticesOFFICE *RPB:ADM by Emal OGCB:DORS RII DRP:RIINAME TechEd jAJKugler j DRTaylor LWGarnerDATE 09/07/94 09/13/94 09/ /94 09/ /94OFFICE DRP:RII HICB: C/HICB:DRCH D/DRH_NAME DMVerrelli HCGar ^ JSWermieltiorDATE 09/ /94 09///94 _J09/22/94 O9/il/94OFFICE C/OGCB:DORS D/DORSNAME ELDoolittle BKGrimesDATE 09/ /94 09/ /94tt1 / IN 94-XXSeptember XX, 994This information notice requires no specific action or written response. Ifyou have any question about the information in this notice, please contact oneof the technical contacts listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts:Uonald R. Taylor, RII(703) 894-5421Larry W. Garner, RII(404) 331-46E3Hukam C. Garg, NRR(301) 504-2929

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List of Recently Issued Information NoticesOFFICE *RPB:ADM EMA)L OGCB:DORS RII DRP:RIINAME TechEd AJKu ler DRTaylor LWGarnerDATE 09/07/94 09/13/94 09/ /94 09/ /94OFFICE DRP:RII HICB:DRCH C/HICB:DRCH D/DRCHNAME DMVerrelli HCGarg JSWermiel BABogerDATE 09/ /94 09/ /94 09/ /94 09/ /94OFFICE C/OGCB:DORS D/DORSNAME ELDoolittle BKGrimes IIDATE 09/ /94 09/ /394