Information Notice 1987-34, Single Failures in Auxiliary Feedwater Systems

Single Failures in Auxiliary Feedwater Systems

ML031130543
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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date:	07/24/1987
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-87-034, NUDOCS 8707210011
Download: ML031130543 (8)

C.-

SSINS No.: 6835 IN 87-34 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 July 24, 1987 NRC INFORMATION NOTICE NO. 87-34: SINGLE FAILURES IN AUXILIARY FEEDWATER

SYSTEMS

Addressees

All holders of an operating license or a construction permit for pressurized

water reactor facilities.

Purpose

This information notice is being provided to alert addressees to potential

single failures of auxiliary feedwater pump start and protective pump trip

circuitry that could cause partial or complete loss of capability to supply

auxiliary feedwater (AFW) in conflict with the design basis. It is expected

that recipients will review the information for applicability to their facili- ties and consider actions, if appropriate, to avoid similar problems. However, suggestions contained in this information notice do not constitute NRC require- ments; therefore, no specific action or written response is required.

Description of Circumstances

On April 30, 1987, the licensee for the Indian Point Unit 2 nuclear power plant

identified a potential single failure in a portion of the pump start circuitry

that is common to both motor-driven auxiliary feedwater pumps and that could

prevent both pumps from starting automatically in the event of either low-low

steam generator level or loss of main feedwater. Such a single failure is in

conflict with the design basis for the system.

This problem was discovered in the course of a review of the auxiliary

'feedwater system being conducted by the licensee as followup to a number

of operational events that occurred in the fall of 1986.

The pump start circuitry at Indian Point Unit 2 was designed so that the steam

generator level and loss of feedwater start'signals were routed through con- tacts of the safety injection inhibit relays. The purpose of these relays is

to delay pump starts under safety injection conditions until the safety injec- tion sequencer calls for the pumps to start at the appropriate tine. If the

contacts of either inhibit relay failed in the open position, neither the low

steam generator level nor the loss of feedwater start signals would cause the

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IN 87-34 July 24, 1987 motor-driven pumps to start automatically. Both inhibit relays are normally

deenergized and closed. Therefore, for the contact to fail in the

a failure in which the relay remains energized or in which the relayopen position, sticks open

following actuation would have to occur.

Discussion:

When the potential single failure was identified, the licensee entered a

72-hour action statement, as required by the Technical Specification Limiting

Conditions for Operation. Within the 72-hour period, the licensee completed a

design modification to provide independent inhibit relays for the two

motor-driven auxiliary feedwater pumps, which satisfied the single-failure

criterion.

Subsequent to the design deficiency determination at Unit 2, a review was

conducted at Indian Point Unit 3. The licensee at that unit determined that

although the pump start circuitry at Unit 3 was in fact different from that of

Unit 2, it also failed to satisfy the single-failure criterion. The

motor-driven auxiliary feedwater pump start logic circuitry at Indian Point

Unit 3 incorporates a pump start (delay) relay that responds to either a main

feedwater pump trip or low-low steam generator level signal. Processing of

either signal requires the operability of this relay, which is common

motor-driven auxiliary feedwater pump start logic circuits. Failure ofto this

both

relay could similarly prevent both pumps from starting automatically. Unit 3 is-currently shutdow--fdr refueTing and corrective actlons are still being

planned.

Previous Similar Occurrence

On March 7, 1985, the licensee for the Salem Generating Station Units 1 and 2 reported (LER 50-272/85-01) to the NRC that the auxiliary feedwater pump (AFP)

trip circu itry did not meet the single-failure criterion. The licensee discov- ered this iln an ongoing review of design changes in which the AFP circuitry

modified to provide protection of all three AFPs in the event of a loss of was

water supply resulting from tornado damage to the auxiliary feedwater storage

tank. The licensee's review of this trip circuitry revealed several potential

single failures that could stem from a single test switch circuit, a single

suction pressure instrument, and a single low suction pressure trip output

relay. Failure of any one of these protective features could have resulted in

tripping all three AFPs. The licensee immediately took interim corrective

actions to eliminate the potential single failure vulnerabilities.

the licensee modified the low suction pressure pump trip circuitry toSubsequently, provide

the protective feature without the potential for a single failure causing a

loss of all AFW.

These conditions serve to highlight the potentially generic aspects of single- failure vulnerabilities in the automatic start and pump protection logic

arrangements for auxiliary feedwater pumps.

IN 87-34 July 24, 1987. This information notice requires no specific action or written response. If

you have questions about this matter, please contact the Regional Administrator

of the appropriate NRC regional office or this office.

harles E. Rossi, Dtrecto

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: R. Gallo, RI

(215) 337-5225 Samuel D. MacKay, NRR

(301) 492-8394 Attachment: List of Recently Issued Information Notices

Attachrent 1

"'_IN 87-34 July 24, 1987 LIST OF RECENTLY ISSUED

I. INFORMATION NOTICES 1987 or

unte or

Information Date

Notice No. Subject Issuance Issued to

87-33 Applicability of 10 CFR 7/24/87 All NRClicensees.

Part ?I to Nonlicensees

.87-32 Deficiencies In the Testing 7/10/87 All nuclear power

of Nuclear-Grade Activated reactor facilities

Charcoal; holding an OL or CP.

87-31 Rlocking, Bracing, and 7/10/87 All NRClicensees.

Securing of Radioactive

Materials Packages In

Transportation.

87-30 Cracking of Surge Ring 7/2/87 All nuclear power

Brackets In Large General reactor facilities

Electric Comoany Electric holding ar OL or CrP.

Motors.

87-29 Recent Safety-Related 6/26/87 All NRClicensees

Tncidents at Large authorized to possess

Irradiators. and use sealed sources

in large irradiators.

87-28 Air Systews Problems at 6/22/87 All nuclear power

U.S. Light Water Reactors. reactor facilities

holding an OL or CP.

87-27 Iranian Official Implies 6/10/87 All nuclear power

Vague Threat to U.S. reactor facilities

Resources. holding an OL or CP.

research and nonpower

reactor facilities.

and fuel fabrication

and processing

facilities using or

possessing formula

quantities of special

nuclear material.

87-26 Cracks In Stiffening Rings 6/11/87 All uranium fuel

o- -- ow-484nch Diametwer-Fg- - $ -- _ _ a m .- - __

Cylinders, conversion facilities.

OL

• Operating License

CP

• Construction Permit

UNITED STATES

NUCLEAR REGULATORY COMMISSION FIRST CLA SS MWAIL

WASHINGTON, D.C. 20555 POSTAGE

• FEES PAID

USNRC

WASH. O.C.

OFFICIAL BUSINESS PERMITNo. eG

PENALTY FOR PRIVATE USE. U300

J

IN 87-34 July 24, 1987 This information notice requires no specific action or written response. If

you have questions about this matter, please contact the Regional Administrator

of the appropriate NRC regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: R. Gallo, RI

(215) 337-5225 Samuel D. MacKay, NRR

(301) 492-8394 Attachment: List of Recently Issued Information Notices

• SEE PREVIOUS PAGE FOR CONCURRENCE

• C/OGCB:DOEA:NRR *PPMB:ARM *OGCB:DOEA:NRR

C/Rosssi CHBerlinger TechEd SMacKay

07f2//87 07/10/87 06/11/87 06/17/87

• RI *RI *RI *RI

Norrholm Gallo Collins Kane

07/10/87 07/10/87 07/10/87 07/10/87

IN 87-XX

July xx, 1987 This information notice requires no specific action or written response. If

you have questions about this matter, please contact the Regional Administrator

of the appropriate NRC regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: R. Gallo, RI

(215) 337-5225 Samuel D. MacKay, NRR

(301) 492-8394 Attachment: List of Recently Issued Information Notices

C/OGCB:DOEA:NRR *PPMB:ARM *OGCB:DOEA:NRR

CHBerlinger TechEd SMacKay

07/JO/87 06/11/87 06/g7/87 £

RI 3 g4n; RI y V )4 RI I

Gallo Collis 7 1 Kane

07//0/87 07//10/87 A 07//1/87 Lfix 07//0/87

IN 87-XX

June xx, 1987 No specific action or written response is required by this information notice.

If you have questions about this matter, please contact the Regional Adminis- trator of the appropriate NRC regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: R. Gallo, RI

(215) 337-5225 Samuel D. MacKay, NRR

(301) 492-8394 Attachment: List of Recently Issued Information Notices

D/DOEA:NRR C/OGCB:DOEA:NRR PPMBB:ARn OGCB:DOEA:NRR

CERossi

06/ /87 CHBerlinger

06/ /87 TechEd

06/11/87

4 SMacKay 153Fj14

06/8 /87 RI SEfv., RI RI RI

Norrholm Gallo Collins Kane

06/oS/87 06/ /87 06/ /87 06/ /87

-Br Ptle

If

IN 87-XX

June xx, 1987 This information notice requires no specific action or written response. If

you have questions about this matter, please contact the Regional Administrator

of the appropriate NRC regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: R. Gallo, RI

(215) 337-5225 Samuel D. MacKay, NRR

(301) 492-8394 Attachment: List of Recently Issued Information Notices

D/DOEA:NRR C/OGCB:DOEA:NRR PPMB:ARM * 0GCB:DOEA-NRR

CERossi CHBerlinger TechEd SMacKay -57N

06/ /87 06/ /87 06/1,V/87 06//17/87 RI RI RI RI

Norrholm Gallo Collins Kane

06/ /87 06/ /87 06/ /87 06/ /87