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 Office of Nuclear Reactor Regulation
To:
References
IN-95-008, NUDOCS 9501240226
Download: ML031060366 (12)

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 January 30, 1995 NRC INFORMATION NOTICE 95-08: INACCURATE DATA OBTAINED WITH CLAMP-ON

ULTRASONIC FLOW MEASUREMENT INSTRUMENTS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

PurDose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information

notice to alert addressees to difficulties in accurately measuring flow rates

with clamp-on ultrasonic flow measurement instruments. It is expected that

recipients will review the information for applicability to their facilities

and 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 Circumstances

O October 14, 1993, while performing a high head safety injection (HHSI) flow

balance test, the licensee for North Anna Unit 2 determined that the as-found

safety injection cold leg branch line flow rates did not meet the technical

specification requirements. The as-found cold leg branch line flow rates had

also failed to meet the technical specification requirements during the

previous test in April 1992.

The North Anna Technical Specifications give limits related to both minimum

and maximum safety injection line flow rates. For North Anna, these two

technical specification limits resulted in an very narrow allowed operating

band, which required the use of highly accurate flow measurement instruments

for flow tests.

The licensee performed the flow balance using System 990 Uniflow Universal

Transit-Time Flowmeters manufactured by Controlotron of Hauppauge, New York.

The Uniflow flowmeter is a clamp-on non-intrusive portable flowmeter that uses

multi-pulse, transit-time ultrasonic technology to measure precisely the flow

rate. The flowmeter induces alternate upstream and downstream ultrasonic

signals and measures the difference in transit times. This information isthe

then used to determine the axial fluid velocity and the flow rate through

pipe. Inaccuracies associated with the use of these instruments at North Anna

combined with the narrow band of allowable flows caused problems which

contributed to the failure to meet technical specification requirements.

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v-' IN 95-08 January 30, 1995 Discussion

The licensee examined the 1993 North Anna Unit 2 flow balance test data and

observed that some of the data indicated that the instrument errors

significantly exceeded accuracies assumed for the tests. Numerous factors may

affect the accuracy of this flowmeter including pipe dimensions, fluid flow

effects, transducer mounting, and instrument setup and operation. After the

test, the licensee investigated and concluded that the instrument inaccuracy

most likely was caused by flow effects associated with the piping

configuration. The piping arrangement, which contained several out-of-plane

bends that forced the flow to change direction numerous times before entering

the straight section of pipe containing the ultrasonic transducers, may have

caused a stable swirl-type flow profile corkscrewing down the pipe. The

licensee postulated that the swirl flow added a radial flow error to the test

instruments. The flowmeter was calibrated assuming a primarily axial flow

profile. In subsequent testing at a national laboratory, Controlotron

ultrasonic flowmeter data varied up to 5% at different orientations around the

pipe at a position approximately 15 pipe diameters downstream of a single

bend. 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 in

the absence of out-of-plane bends, causing flow measurements with larger than

expected errors.

The licensee noted that the instrument output during the test did not give any

indication of measurement problems. The instruments displayed little noise

and only the expected small-magnitude random flow fluctuations. The lack of

erratic instrument readings could easily be interpreted as meaning the

readings were valid (i.e., within the stated accuracy). However, the licensee

tested the instrument and determined that it could register a stable reading

while a significant error was occurring. Therefore, the licensee concluded

that repeatability of the data does not prove that the flow has been measured

accurately.

After the test failure, the licensee found several inconsistencies in the test

data which indicated problems in data accuracy. As an example, when the

A HHSI pump replaced the C HHSI pump as the operating pump, without any other

changes in system resistance, the B cold leg flow rate increased by

8.4 percent while the A cold leg flow rate increased by 1.5 percent and the

C cold leg flow rate did not change. The licensee concluded that these values

corresponded to an implausible change in the highest cold leg flow path from

loop 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 I n-' IN 95-08 January 30, 1995 C HHSI pump; thus, the A HHSI pump would be expected to supply flow rates less

than the C HHSI pump for the same system resistance. However, the ultrasonic

instruments indicated that the A HHSI pump delivered 3.3 percent more flow

than the C HHSI pump. This was contrary to the previously measured pump head

curve data. At the same time, installed plant process instruments indicated

that the A HHSI pump delivered 3.4 percent less flow than the C HHSI pump, a

measurement consistent with the pump curves.

The licensee could not determine with certainty the factors that resulted in

the unanticipated measurement errors in this event. Conditions specific to an

application can cause deviations from the vendor-supplied instrument

accuracies. However, during the investigation the licensee developed methods

that could be used to determine when the ultrasonic flowmeter may not yield

the assumed accuracy. These methods include comparing ultrasonic flowmeter

data from several locations or different orientations at the same location or

by comparing the data from these instruments with data from permanently

installed instruments. Test results can also be compared with expected system

behavior.

The NRC staff has approved a request from the licensee of the North Anna plant

to modify the technical specification that specifies the acceptance criteria

for the HHSI pump flow rates. The change removes the specific fixed values

for the flow from the technical specifications and permits the licensee to

establish allowable values by analysis, providing greater operational

flexibility. The licensee is also planning to (1) install permanent flow

instrumentation that will supply highly accurate data for future flow balance

testing and (2)supply training concerning the accuracy of clamp-on ultrasonic

flowmeters to the personnel who use them.

Licensees frequently use flow measurements to demonstrate that safety-related

component performance is adequate to meet the demands indicated by the

accident or transient analyses. Therefore, obtaining accurate flow

measurements is important to safety. When balancing the flow of HHSI

injection paths, flow rates need to be accurately measured to demonstrate that

the unit complies with the assumptions in safety analyses and is operated in

an analyzed condition. At North Anna the licensee initially failed to detect

inaccurate flow data because of a failure to verify the consistency, repeatability and reasonableness of the data from the ultrasonic flow

measurement instruments. Although technical specification requirements were

not met at North Anna, the licensee later analyzed the issue and concluded

that the HHSI system would have performed its design safety function.

s'-' IN 95-08 January 30, 1995 This information notice requires no specific action or written response. If

you have any question about the information in this notice, please contact one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

ran K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Donald R. Taylor, RII Larry W. Garner, RII

(703) 894-5421 (404) 331-4663 Hukam C. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued Information Notices

Re-ttachment

.

IN 95-08 January 30, 1995 Page I of 1 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

95-07 Radiopharmaceutical Vial 01/27/95 All USNRC medical licensees

Breakage during Preparation authorized to use byproduct

material for diagnostic

procedures.

95-06 Potential Blockage of 01/25/95 All holders of OLs or CPs

Safety-Related Strainers for nuclear power reactors.

by Material Brought Inside

Containment

95-05 Undervoltage Protection 01/20/95 All holders of Construction

Relay Settings Out of Permits for nuclear power

Tolerance Due to Test reactors.

Equipment Harmonics

95-04 Excessive Cooldown and 01/19/95 All holders of OLs or CPs

Depressurization of the for nuclear power reactors.

Reactor Coolant System

Following a Loss of

Offsite Power

95-03 Loss of Reactor Coolant 01/18/95 All holders of Ols or CPs

Inventory and Potential for nuclear power reactors.

Loss of Emergency Mitiga- tion Functions While in

a Shutdown Condition

95-02 Problems with General 01/17/95 All holders of OLs or CPs

Electric CR2940 Contact for nuclear power reactors.

Blocks in Medium-Voltage

Circuit Breakers

95-01 DOT Safety Advisory: 01/04/95 All U.S. Nuclear Regulatory

High Pressure Aluminum Commission licensees.

Seamless and Aluminum

Composite Hoop-Wrapped

Cylinders

OL - Operating License

CP = Construction Permit

> S 95-08 January 30, 1995 This information notice requires no specific action or written response. If

you have any question about the information in this notice, please contact one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Original signed by

Brian K. Grime!

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Donald R. Taylor, RII Larry W. Garner, RII

(703) 894-5421 (404) 331-4663 Hukam C. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued Information Notices

DOCUMENT NAME: 95-08.IN

NOTE: VENDOR COMMENTS RECEIVED, NO SIGNIFICANT CHANGES WERE MADE

OFFICE *RPB:ADM by Email *OGCB:DORS *RIIby Phoncon *DRP:RIIby Phoncon

,AME TechEd AJKugler DRTaylor LWGarner

DATE 09/07/94 09/13/94 09/22/94 09/22/94 OFFICE *DRP:RI Iby Phoncon *HICB:DRCH *C/HICB:DRCH *D/DRCH

NAME DMVerrelli HCGarg JSWermiel BABoger

DATE 09/27/94 09/,W94 / 09/22/94 09/22/94 OFFICE C/OECB:DOPS OP /

NAME AEChaffee* Arxi es

DATE 11 /22/94 01&1y 95 T

OFFICIAL RECORD COPY

-

IN 95-XX

January XX, 1995 This information notice requires no specific action or written response. If

you have any question about the information in this notice, please contact one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Donald R. Taylor, RII Larry W. Garner, RI!

(703) 894-5421 (404) 331-4663 Hukam C. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued Information Notices

DOCUMENT NAME: S:\DOPS_SEC\CLAMP-ON.INR

mnTE- VENDOR COMMENTS RFCFTVFD NO SIGNIFICANT CHANGES WERE MADE

OFFICE *RPB:ADM by Emai t *OGCB:DORS *RIIby Phoncon *DRP:RIIby Phoncon

NAME TechEd AJKugler DRTaylor LWGarner

DATE 09/07/94 09/13/94 09/22/94 09/22/94 OFFICE *DRP: RIIby Phoncon *HICB:DRCH *C/HICB:DRCH *D/DRCH

KANE DMVerrelli HCGarg JSWermiel BABoger

DATE 09/27/94 09/19/94 09/22/94 09/22/94 OFFICE C/OECB:DOPS D/DOPS

NAME AEChaffee* BKGrimes

DATE 11/22/94 11/ /94 _ _ _ _=

OFFICIAL RECORD COPY

<-/

IN 94-XX

November XX, 1994 This information notice requires no specific action or written response. If

you have any question about the information in this notice, please contact one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: 'onald R. Taylor, RII

(70 ) 894-5421 Lar y W. Garner, RII

(40 ) 331-4663 Huk C. Garg, NRR

(30 ) 504-2929 Attachment: List of Recently Issued Information Notices

DOCUMENT NAME: S:\DOPSSEC\CLAMP-ON.INR

MnTr- vrTnnn rnMMFNTq RFCFIVFED NO SIGNIFICANT CHANGES WERE MADE

OFFICE *RPB:ADM by EmaiL *OGCB:DORS *RI Iby Phoncon *DRP:RI Iby Phoncon

NAME TechEd AJKugler DRTaylor LWGarner

DATE 09/07/94 09/13/94 09/22/94 09/22/94 OFFICE *DRP:RI Iby Phomon *HICB:DRCH *C/HICB:DRCH *D/DRCH

OMWE DMVerrelli HCGarg JSWermiel BABoger

DATE 09/27/94 09/19/94 09/22/94 09/22/94 OFFICE C/OECB:DOPS D/DOPS

NAME AEChaffee* BKGrimes _ _,

11/22/94 11/ /94 OFFICIAL RECORD COPY

IN 94-XX

November XX, 1994 This information notice requires no specific action or written response. If

you have any question about the information in this notice, please contact one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Donald R. Taylor, RII

(703) 894-5421 Larry W. Garner, RII

(404) 331-4663 Hukam C. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued Information Notices

NOTF VFNDOR COMMENTS RECEIVED. NO SIGNIFICANT CHANGES WERE MADE

OFFICE *RPB:ADM by Email *OGCB:DORS *RIIby Phoncon *DRP:RIIby Phoncon

NAME TechEd AJKugler DRTaylor LWGarner

DATE 09/07/94 09/13/94 09/22/94 09/22/94 OFFICE *DRP:RIIby Phoncon *HICB:DRCH *C/HICB:DRCH *D/DRCH

NAME DMVerrelli HCGarg JSWermiel BABoger

DATE 09/27/94 09/19/94 09/22/94 09/22/94 OFFICE C/OECB:DOPS D/DOPS

NAME AEf ffeBKGrimes

DATE 11/2494 Af 11/ /94 __I

DOCUMENT NAME: G:\IN\CLAMP-0N.INK

IN 94-XX

November XX, 1994 This information notice requires no specific action or written response. If

you have any question about the information in this notice, please contact one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Donald R. Taylor, RII

(703) 894-5421 Larry W. Garner, RII

(404) 331-4663 Hukam C. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued NRC Information Notices

NOTE: VENDOR COMMENTS RECEIVED, NO SIGNIFICANT CHANGES WERE MADE

OFFICE *RPB:ADM by Email *OGCB:DORS *RIIby Phoncon *DRP:RIIby Phoncon

NAME TechEd AJKugler DRTaylor LWGarner

DATE 09/07/94 09/13/94 09/22/94 09/22/94 OFFICE *DRP:RIIby Phocon *HICB:DRCH *C/HICB:DRCH *D/DRCH

NAME DMVerrelli HCGarg JSWermiel BABoger

DATE09/27/94 09/19/94 09/22/94 09/22/94 OFFICE C/OECB:DOPS D/DOPS

NAME AEChaffee BKGrimes

DATE . 11/ /94 DOCUMENT NAME: t:\IN\CLAMP-ON.IN

IN 94-XX

September XX, 1994 This information notice requires no specific action or written response. If

you have any question about the information in this notice, please contact one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: Donald R. Taylor, RII

(703) 894-5421 Larry W. Garner, RII

(404) 331-4663 Hukam C. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued Information Notices

OFFICE *RPB:ADM by Emal OGCB:DORS RII DRP:RII

NAME TechEd jAJKugler j DRTaylor LWGarner

DATE 09/07/94 09/13/94 09/ /94 09/ /94 OFFICE DRP:RII HICB: C/HICB:DRCH D/DRH_ tt1 /2.

NAME DMVerrelli HCGar ^ JSWermieltior

DATE 09/ /94 09///94 _J09/22/94 O9/il/94 OFFICE C/OGCB:DORS D/DORS

NAME ELDoolittle BKGrimes

DATE 09/ /94 09/ /94

IN 94-XX

September XX, 1994 This information notice requires no specific action or written response. If

you have any question about the information in this notice, please contact one

of the technical contacts listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: Uonald R. Taylor, RII

(703) 894-5421 Larry W. Garner, RII

(404) 331-46E3 Hukam C. Garg, NRR

(301) 504-2929 Attachment: List of Recently Issued Information Notices

OFFICE *RPB:ADM EMA)L OGCB:DORS RII DRP:RII

NAME TechEd AJKu ler DRTaylor LWGarner

DATE 09/07/94 09/13/94 09/ /94 09/ /94 OFFICE DRP:RII HICB:DRCH C/HICB:DRCH D/DRCH

NAME DMVerrelli HCGarg JSWermiel BABoger

DATE 09/ /94 09/ /94 09/ /94 09/ /94 OFFICE C/OGCB:DORS D/DORS

NAME ELDoolittle BKGrimes II

DATE 09/ /94 09/ /394