Information Notice 1993-13, Undetected Modification of Flow Characteristics in High Pressure Safety Injection System

Undetected Modification of Flow Characteristics in High Pressure Safety Injection System

ML031080148
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:	02/16/1993
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
IN-93-013, NUDOCS 9302100227
Download: ML031080148 (8)

4 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 February 16, 1993 NRC INFORMATION NOTICE 93-13: UNDETECTED MODIFICATION OF FLOW CHARACTERISTICS

IN THE HIGH PRESSURE SAFETY INJECTION SYSTEM

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

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

notice to alert addressees to the potential for changes of system flow

characteristics to go undetected as occurred at Arkansas Nuclear One (ANO)

Unit 2. 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.

Description of Circumstances

On September 23, 1992, with Unit 2 shut down, Entergy Operations, Inc. (the

licensee) evaluated flow imbalances that were found during testing of the high

pressure safety injection (HPSI) system. The licensee determined that the

flow rates through five of the system valves were less than required. Because

of the low flow rates, the licensee concluded that the sum of the flow rates

of the three injection paths with the lowest flow rates was less than that

assumed in the plant design basis calculations which support the plant safety

analysis.

The licensee investigated the event and determined that replacement stem disc

assemblies, supplied as "like for like' and installed as early as 1982, were

not identical to the original assemblies. Subsequent to the event, the

licensee had the vendor rework spare valve discs to meet the design

requirements and installed these in the five affected valves. The licensee

then conducted flow balance testing to ensure that all system flow

requirements were met.

9302100227 p D013 x ( )'tI/

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'19

IN 93-13 February 16, 1993 Discussion

The licensee reviewed documentation for the affected discs and determined

that, as a result of a vendor drawing error in 1978, certain design changes of

the stem disc assemblies had not been incorporated into drawings for

ANO Unit 2. The most significant of these was a 2 to 3 mm [1/10-inch] change

in diameter at one location on the replacement discs. This change was not

easily detected by visual examination. However, the as-found flow through the

affected injection paths was degraded an average of 23 percent.

The technical specifications for ANO Unit 2, require flow balance testing

after system modifications which could affect flow characteristics, but do not

require periodic flow balance testing. The licensee did not recognize that

the replacement stem disc assemblies were different from the original stem

disc assemblies and, therefore, did not test the system after changing the

components.

The licensee discovered the flow imbalances and degraded flow rates during a

full flow test performed in response to Generic Letter 89-04, 'Guidance on

Developing Acceptable Inservice Testing Programs." During this test, the

total indicated flow was found to be lower than the actual flow. After

investigation, the difference was found to have been caused by a flow orifice

that had been installed backwards. While investigating the problem, the

licensee determined the actual system flow by isolating the hot leg injection

paths and summing the indicated flows of the four cold leg injection paths.

From these measurements, the licensee found that the flows varied greatly.

The large variation in indicated flows of the cold leg injection paths led the

licensee to find the improper discs.

Although the individual loop flows varied greatly, the total flow of the

system met the acceptance criteria. Performing full flow testing alone would

not have caused the licensee to find the degraded flow in parts of the system.

Therefore, the flow imbalances might have remained undetected if the flow

orifice had been installed correctly and investigation of the flow orifice

problem not been required.

The licensee reviewed the technical specifications for similar surveillance

test requirements. The licensee then evaluated the similar tests to determine

whether they were adequate to fully test the system and were required to be

performed at appropriate times. Upon completing this review and another

review to find systems with similar valves, the licensee performed flow

balance testing on the low pressure safety injection system with satisfactory

results. The licensee revised the HPSI flow testing procedure to provide for

confirmation of satisfactory flow balance and capacity during each refueling

outage.

r -< J"~ IN 93-13 February 16, 1993 This information notice requires no specific action or written response. If

you have any questions 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: William Johnson, RIV

(817) 860-8148 Linda Smith, RIV

(501) 968-3290

Dennis Kelley, RIV

(817) 860-8289 Attachment: List of Recently Issued NRC Information Notices

I -

IN 93-13 February 16, 1993 This information notice requires no specific action or written response. If

you have any questions 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.Grimes

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: William Johnson, RIV

(817) 860-8148 Linda Smith, RIV

(501) 968-3290

Dennis Kelley, RIV

(817) 860-8289 Attachment: List of Recently Issued NRC Information Notices

Documet Name: 93-13. IN

• S(t~RF~YIt'US CONCUIRRENCES

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• C/SRXB:DSS:NRR*SRI/RIV *DRP:RIV D/DRP:RIV *DRS:RIV

RCJones LSmith WJohnson ABeach DKelley

02/04/93 01/21/93 01/21/93 01/ /93 01/26/93

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IN 93-XX

February xx, 1993 This information notice requires no specific action or written response. If

you have any questions 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: William Johnson, RIV

(817) 860-8148 Linda Smith, RIV

(501) 968-3290

Dennis Kelley, RIV

(817) 860-8289 Attachment: List of Recently Issued NRC Information Notices

Document Name: HPSI3.IN

• SEE PREVIOUS CONCURRENCES

D/DORS:NRR *C/OGCB:DORS:NRR*RPB:ADM *DRS:RIV *OGCB:DORS:NRR

BKGrimesL GMarcus TechEd TStetka JLBirmingham

02/ /93 WJ-101/29/93 01/07/93 01/26/93 01/26/93

• C/SRXB:DSS:NRR *SRI/RIV *DRP:RIV D/DRP:RIV *DRS:RIV

RCJones LSmith WJohnson ABeach DKelley

02/04/93 01/21/93 01/21/93 01/ /93 01/26/93

• per telecon

^- h

IN 93-XX

February xx, 1993 This information notice requires no specific action or written response. If

you have any questions 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: William Johnson, RIV

(817) 860-8148 Linda Smith, RIV

(501) 968-3290

Dennis Kelley, RIV

(817) 860-8289 Attachment: List of Recently Issued NRC Information Notices

Document Name: HPSI3.IN

• SEE PREVIOUS CONCURRENCES

C/OGCB:DORS:NRR* D/DORS:NRR RPB:ADM* DRS:RIV** OGCB:DORS:NRR*

GHMarcus BKGrimes TechEd TStetka JLBirmingham

01/29/93 01/ /93 01/07/93 01/26/93 01/ /93 C/S XSSA:NRR SRI/RIV** DRP:RIV** D/DRP:RIV** DRS:RIV**

RCJor)s LSmith WJohnson ABeach DKelley

02/ 'I93 01/21/93 01/21/93 01/26/93 01/21/93

• • p Ptelecon

IN 93-XX

January xx, 1993 This information notice requires no specific action or written response. If

you have any questions 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: William Johnson, RIV

(817) 860-8148 Linda Smith, RIV

(501) 968-3290

Dennis Kelley, RIV

(817) 860-8289 Attachment: List of Recently Issued NRC Information Notices

5 aL e- F~k I'6 Document Name: HPSI3.IN

• SEE PREVIOUS CONCURRENCES

D/DORS:NRR C/OGCB:DORS:NRR*RPB:ADM *DRS:RIV

BKGrimes GMarcuspi- TechEd TStetka

01/ /93 OI/z /9 01/07/93 01/26/93

• OGCB:DORS:NRR *SRI/RIV *DRP:RIV *H3/DRP:RJV *DRS:RIV

JLBirminghamG > LSmith WJohnson ABeacX DKelley

01/26/93 01/21/93 01/21/93 O1/a26/9364 01/26/93

• per telecon

4 Wtttachment

IN 93-13 February 16, 1993 Page 1 of I

LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

93-12 Off-Gassing in Auxiliary 02/11/93 All holders of OLs or CPs

Feedwater System Raw for nuclear power reactors.

Water Sources

93-11 Single Failure Vulner- 02/04/93 All holders of OLs or CPs

ability of Engineered for nuclear power reactors.

Safety Features

Actuation Systems

93-10 Dose Calibrator Quality 02/02/93 All Nuclear Regulatory Com- Control mission medical licensees.

93-09 Failure of Undervoltage 02/02/93 All holders of OLs or CPs

Trip Attachment on for nuclear power reactors.

Westinghouse Model DB-50

Reactor Trip Breaker

93-08 Failure of Residual 02/01/93 All holders of OLs or CPs

Heat Removal Pump for nuclear power reactors.

Bearings due to High

Thrust Loading

93-07 Classification of Trans- 02/01/93 All Licensees required to

portation Emergencies have an emergency plan.

93-06 Potential Bypass Leak- 01/22/93 All holders of OLs or CPs

age Paths Around Filters for nuclear power reactors.

Installed in Ventilation

Systems

93-05 Locking of Radiography 01/14/93 All Nuclear Regulatory

Exposure Devices Commission industrial

radiography licensees.

93-04 Investigation and Re- 01/07/93 All U.S. Nuclear Regulatory

porting of Misadministra- Commission medical

tions by the Radiation licensees.

Safety Officer

OL - Operating License

CP - Construction Permit