Information Notice 1986-09, Failure of Check & Stop Check Valves Subjected to Low Flow Conditions

Failure of Check & Stop Check Valves Subjected to Low Flow Conditions

ML031220568
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:	02/03/1986
From:	Jordan E NRC/IE
To:
References
IN-86-009, NUDOCS 8601290305
Download: ML031220568 (4)

SSINS No.: 6835 IN 86-09 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 February 3, 1986 IE INFORMATION NOTICE NO. 86-09: FAILURE OF CHECK AND STOP CHECK VALVES

SUBJECTED TO LOW FLOW CONDITIONS

Addressees

All nuclear power reactor facilities holding an operating license (OL) or a

construction permit (CP).

Purpose

This notice is provided to alert recipients of a potentially significant safety

problem pertaining to check and stop check valves failing under low flow

conditions. It is expected that recipients will review the information for

applicability to their facilities and consider actions, if appropriate, to

preclude a similar problem occurring at their facilities. However, suggestions

contained in this notice do not constitute NRC requirements; therefore, no

specific action or written response is required.

Description of Circumstances

Between late November 1985 and early January 1986, Florida Power and Light's

Turkey Point facility experienced numerous failures of the 12 stop check valves

in the steam supply system to the auxiliary feedwater pumps. The stop check

valves are located upstream and downstream of a motor-operated valve (MOV) that

opens when required to initiate auxiliary feedwater flow. The stop check

valves are normally open and thus allow steam flow to the pumps while at the

same time preventing backflow through the steam line in the event of a steam

line break.

The mode of failure of the valve was degradation of the disc and disc nut

assembly (see attached sketch) due to low steam flow conditions caused by

slight leakage past the normally closed MOV. The low steam flow rate was not

sufficient to keep the disc open and the disc assembly then vibrated and

chattered causing excessive wear and damage to the valve internals, in parLicu- lar,-the disc assembly. In many cases (three in November and four in January),

the disc guide stud had broken off from the disc. This allowed the disc to

become cocked in the valve ana prevented full closure (thus defeating both the

check and stop features of the valve) and full opening (thus restricting steam

flow). In addition. the broken disc guide stud was free to travel downstream

with steam flow and could have caused damage to equipment and components in the

flow path.

8601290305

IN 86-09 February 3, 1986 The licensee performed a failure analysis of the disc assembly to verify the

acceptability of a higher strength material being used in a redesigned disc

guide. In addition, the licensee committed to a program of regular radiogra- phic examination of the valves on Unit 3 for the remainder of the refueling

cycle. However, the licensee considers this to be an interim repair pending

the completion of the study underway by its AFW Enhancement Task Force.

A related series of events was discussed in IE Information Notice 82-26, "RCIC

and HPCI Turbine Exhaust Check Valve Failures." In this case the low steam

flow rates were the result of testing the RCIC and HPCI turbines at less than

rated load. The corrective actions consisted of changes to test procedures, changes to the exhaust system design, and changing to a different check valve

style.

The information herein is being provided as an early notification of a possibly

significant matter that is still under review by the NRC staff. Recipients

should review the information for possible applicability to their facilities.

If NRC evaluation so indicates, further licensee actions may be requested.

No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the Regional

Admini5strator of the appropriate regional office or this office.

Edwa4 ordan, Director

Divisi of Emergency Preparedness

and Etsgineering Response

Office of Inspection and Enforcement

Technical Contacts: George A. Schnebli, RII

(404)331-4875 Richard J. Kiessel, IE

(301)492-8119 Attachments:

1. Sketch of Stop Check Globe Valve

2. List of Recently Issued IE Information Notices

Attachment 1 IN 86-09 February 3, 1986 SET It:

SLDf M Gn S-__

EOLBT i) X AtQ8L

EYEBT WT \TOMOM

DLMFLANE (

DDIE GUS STUD

BONE ,'} ZAV

ozc 8t W [ T - _POWtT AT WHIC14 l t V t LDISC GOIDE STIJI

WEAT 0G @> F

Disc 'DISC. GUIDE STUD

I9OOY

STOP CHECK GLOBE VALVE

Attachment 2 IN 86-09 February 3, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-08 Licensee Event Report (LER) 2/3/86 All power reactor

Format Modification facilities holding

an OL or CP

86-07 Lack Of Detailed Instruction 2/3/86 All power reactor

And Inadequate Observance Of facilities holding

Precautions During Maintenance an OL or CP

And Testing Of Diesel Generator

Woodward Governors

86-06 Failure Of Lifting Rig 2/3/86 All power reactor

Attachment While Lifting The facilities holding

Upper Guide Structure At an OL or CP

St. Lucie Unit 1

86-05 Main Steam Safety Valve Test 1/31/86 All PWR facilities

Failures And Ring Setting holding an OL or

Adjustments CP

86-04 Transient Due To Loss Of 1/31/86 All power reactor

Power To Integrated Control facilities holding

System At A Pressurized Water an OL or CP

Reactor Designed By Babcock

& Wilcox

86-03 Potential Deficiencies In 1/14/86 All power reactor

Environmental Qualification facilities holding

Of Limitorque Motor Valve an OL or CP

Operator Wiring

86-02 Failure Of Valve Operator 1/6/86 All power reactor

Motor During Environmental facilities holding

Qualification Testing an OL or CP

86-01 Failure Of Main Feedwater 1/6/86 All power reactor

Check Valve Causes Loss Of facilities holding

Feedwater System Integrity an OL or CP

And Water-Hammer Damage

OL = Operating License

CP = Construction Permit