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 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

is then used to determine

the axial fluid velocity and the flow rate through the 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.

P4 R I r p.# sCC 's 9501240226 UtjxW ¢ vv -31-15 lk 0 (t

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, Page I of 1 1995 LIST OF RECENTLY ISSUED NRC INFORMATION

NOTICES Information

Date of Notice No. Subject Issuance Issued to 95-07 Radiopharmaceutical

Vial Breakage during Preparation

01/27/95 All USNRC medical licensees authorized

to use byproduct material for diagnostic

procedures.

95-06 Potential

Blockage of Safety-Related

Strainers by Material Brought Inside Containment

01/25/95 All holders of OLs or CPs for nuclear power reactors.95-05 Undervoltage

Protection

Relay Settings Out of Tolerance

Due to Test Equipment

Harmonics 01/20/95 All holders Permits for reactors.of Construction

nuclear power 95-04 95-03 Excessive

Cooldown and Depressurization

of the Reactor Coolant System Following

a Loss of Offsite Power Loss of Reactor Coolant Inventory

and Potential Loss of Emergency

Mitiga-tion Functions

While in a Shutdown Condition Problems with General Electric CR2940 Contact Blocks in Medium-Voltage

Circuit Breakers DOT Safety Advisory: High Pressure Aluminum Seamless and Aluminum Composite

Hoop-Wrapped

Cylinders 01/19/95 01/18/95 01/17/95 01/04/95 All holders of OLs or CPs for nuclear power reactors.All holders of Ols or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All U.S. Nuclear Regulatory

Commission

licensees.

95-02 95-01 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 (703) 894-5421 Larry W. Garner, RII (404) 331-4663 Hukam C. Garg, NRR (301) 504-2929 Attachment:

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• 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*

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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, RI!(404) 331-4663 Hukam C. Garg, NRR (301) 504-2929 Attachment:

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Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Project Support Office of Nuclear Reactor Regulation

Technical

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'onald R. Taylor, RII (70 ) 894-5421 Lar y W. Garner, RII (40 ) 331-4663 Huk C. Garg, NRR (30 ) 504-2929 Attachment:

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• 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

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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:

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Phoncon *HICB:DRCH

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• D/DRCH NAME DMVerrelli

HCGarg JSWermiel

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

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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:

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• 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

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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 (404)W. Garner, RII 331-4663 Hukam (301)C. Garg, NRR 504-2929 Attachment:

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D/DRH_NAME DMVerrelli

HCGar ^ JSWermieltior

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

D/DORS NAME ELDoolittle

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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

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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