Information Notice 1986-73, Recent Emergency Diesel Generator Problems

Recent Emergency Diesel Generator Problems

ML031250129
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, 05003543, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
Issue date:	08/20/1986
From:	Jordan E NRC/IE
To:
References
IN-86-073, NUDOCS 8608180089
Download: ML031250129 (3)

SSINS No.: 6835 IN 86-73 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 August 20, 1986 IE INFORMATION NOTICE NO. 86-73: RECENT EMERGENCY DIESEL GENERATOR PROBLEMS

Addressees

All nuclear power reactor facilities holding an operating license or a

construction permit.

Purpose

This notice is to alert addressees to vibration-induced fuel line wear and of

a deficiency in the design of the field flash circuitry on nuclear plant emer- gency diesel generators. Recipients are expected to review the information for

applicability to their facilities and consider actions, if appropriate, to pre- clude similar problems occurring at their facilities. However, suggestions

contained in this information notice do not constitute NRC requirements; there- fore, no specific action or written response is required.

Description of Circumstances

Nine Mile Point Unit 2

While conducting diesel generator testing in early May 1986, it was discovered

that diesel fuel lines had experienced extensive wear and fuel leaks in the

area of the clamps that mount the fuel lines to the diesel engine. The diesels

are Cooper-Bessemer model KSV-16-T, 600 rpm, 4 stroke, 16 cylinder units with

low total operating hours.

Fuel line damage was caused by vibration from the diesel engine and fuel system

pulsation induced by rapid, repeated cycling of a fuel system relief valve.

This valve relieves from the low pressure fuel system via a cooler to the fuel

day tank to control low pressure fuel system pressure. The manufacturer proposes

to correct the problem by inserting plastic sleeves between the fuel line and

its hold down clamps and installing a dashpot on the relief valve to dampen its

operation.

Watts Bar Units 1 and 2

In April 1986 a deficiency was identified which affects all five standby diesel

generators (DGs) at Watts Bar Nuclear Plant and could prevent the OGs from

developing a voltage output when required in an emergency. The affected DGs are

tandem 16-645 E4 units supplied by Morrison-Knudson Co. The normal shutdown

cycle of the DG includes a 10-minute cooldown run at about 450 rpm. If during

8608180089

IN 86-73 August 20, 1986 this idle period an emergency start signal were received, the DG would accelerate

to the normal 900 rpm operating speed, but the generator field would not be

flashed and an output voltage therefore would not be developed.

This problem has also been determined to exist on the HPCS DG at Grand Gulf

Nuclear Station. This unit was supplied by General Motors Corporation.

The root cause of this deficiency has been found to be a design error by the

manufacturer. During a normal or emergency start, as the OG accelerates past

475 rpm, logic is completed to flash the generator field. When output voltage

has built up, the field flash circuitry is automatically disabled. The logic

design is such that engine speed must go below 200 rpm to re-enable the field

flash circuitry, thus no field flash will occur if an emergency start signal

is received during the 450 rpm cooldown period. Field flash would be needed

under these circumstances because the self-excitation path is interrupted early

in the shutdown sequence.

The corrective action proposed by the OG manufacturer is to modify the control

circuitry to eliminate the speed dependence of field flash reset.

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

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

l Administrator of the appropriate regional office or this office.

,r . Jordan, Director

Divisi /of Emergency Preparedness

and l ineering Response

Office of Inspection and Enforcement

Kevin Wolley, IE

(301) 492-8373 Attachment: List of Recently Issued IE Information Notices

'IL

Attachment 1 IN 86-73 August 20, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-72 Failure 17-7 PH Stainless 8/19/86 All power reactor

Steel Springs In Valcor facilities holding

Valves Due to Hydrogen an OL or CP

Embrittlement

86-71 Recent Identified Problems 8/19/86 All power reactor

With Limitorque Motor facilities holding

Operators an OL or CP

86-70 Spurious System Isolation 8/18/86 All GE BWR facilities

Caused By The Panalarm Model holding an OL or CP

86 Thermocouple Monitor

86-69 Scram Solenoid Pilot Valve 8/18/86 All BWR facilities

(SSPV) Rebuild Kit Problems holding an OL or CP

86-68 Stuck Control Rod 8/15/86 All BWR facilities

holding an OL or CP

86-67 Portable Moisture/Density 8/15/86 All NRC licensees

Gauges: Recent Incidents And authorized to possess, Common Violations Of Require- use, transport, and

ments For Use, Transportation, store sealed sources

And Storage

86-66 Potential For Failure Of 8/15/86 All power reactor

Replacement AC Coils Supplied facilities holding

By The Westinghouse Electric an OL or CP

Corporation For Use In Class

lE Motor Starters And

Contractors

86-65 Malfunctions Of ITT Barton 8/14/86 All power reactor

Model 580 Series Switches facilities holding

During Requalification Testing an OL or CP

86-64 Deficiencies In Upgrade 8/14/86 All power reactor

Programs For Plant Emergency facilities holding

Operating Procedures an OL or CP

OL = Operating License

CP = Construction Permit