Information Notice 1990-80, Sand Intrusion Resulting in Two Diesel Generators Becoming Inoperable

Sand Intrusion Resulting in Two Diesel Generators Becoming Inoperable

ML031210444
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:	12/21/1990
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-90-080, NUDOCS 9012170262
Download: ML031210444 (3)

1/41~

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 December 21, 1990

NRC INFORMATION NOTICE NO. 90-80: SAND INTRUSION RESULTING IN TWO DIESEL

GENERATORS BECOMING INOPERABLE

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is intended to alert addressees to the potential damage

that may occur to emergency diesel generator (EDG) equipment as the result of

the use of abrasive material during maintenance operations. This information

notice is based on an event in which sand (aluminum oxide) intruded into the

cylinders of two diesel engines at the Susquehanna Steam Electric Station as a

result of maintenance related cleaning of the diesel engine intercoolers. The

affected diesel generators were subsequently declared inoperable because of

damage to the cylinder liners and piston rings caused by the abrasive action of

the aluminum oxide Particles. 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 do not constitute NRC requirements; therefore, no specific

action or written response is required.

Description of Circumstances

On August 30, 1990, with both Units 1 and 2 operating at 100-percent power, the

'B' EDG at the Susquehanna Steam Electric Station was declared inoperable when

plant personnel, performing periodic chemical analysis of EDG lubricating oil

samples, found a high concentration of chromium in the 'B EDG oil samples.

Boroscopic examination of the EDG cylinders revealed significant scoring of

numerous cylinder liners and piston rings. The licensee concluded that the

source of chromium in the lubricating oil was from the scored cylinder liners.

Previously the licensee had found similar scoring of the cylinder liners and

piston rings on the 'DI EDG. Further inspection by plant personnel identified

the presence of abrasive material (sand) in the intake air manifolds of both

the 'B' and 'D' diesel engines.

A root cause analysis concluded that the sand had entered the EDGs during

recent maintenance operations involving the cleaning and coating of the inner

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90-80

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gecember 21, 1990 surface of the tubes in the intercoolers (heat exchangers). The intercoolers

are located between the turbocharger air compressor discharge and the intake

air manifolds. The intercoolers consist of a shell side through which intake

air passes and a tube side through which cooling water passes. As part of

normal maintenance, the intercoolers are periodically cleaned and treated with

a corrosion-preventive agent. Maintenance personnel clean the inner surface of

the intercooler tubes by airblasting with fine particles of aluminum oxide.

Prior to performing the cleaning, maintenance personnel had removed the

intercoolers from the EDGs and prepared them for sandblasting by covering the

shell side with plywood and taping the edges. Four bolts were used to secure

the plywood cover to the intercooler. Apparently, the plywood cover warped and

dislodged the tape allowing the aluminum oxide particles to enter the shell

side of the intercoolers. After the intercoolers were reinstalled, combustion

intake air picked up the residual sand and carried it inside the engine. Once

inside the engine, the sand settled between the piston rings and cylinder

liners, resulting in the heavy scoring.

Other occurrences of abrasive material intrusion include a 1985 event at

Catawba in which metallic particles were found embedded in the bearing shells

and in the lubricating oil system of one EDG. The metallic particles were

analyzed and found to be identical to shotblasting material used during piping

modifications and repairs to the lubricating oil system.

Discussion of Safety Significance:

These events reveal thevulnerability of the-EDGs to-damage-from-foreign

materila, such as the aluminum oxide particles, which may. enter the engine

through the combustion air, lubricating oil, fuel oil, or jacket coolant water

systems. In addition, these events underscore the importance of implementing

strict cleanliness specifications when performing maintenance activities on

these subsystems. The application of generally accepted industry practices for

maintaining equipment cleanliness levels through the incorporation of cleanli- ness requirements into maintenance procedures and the training of work crews in

the methods for meeting those requirements are considered effective. The fact

that the licensee detected the degradation of the cylinder liners as a conse- quence of required periodic chemical analysis of the lubricating oil is evi- dence of the value of performing regular lubricating oil analyses.

Other options for cleaning heat exchanger tubes are available in the industry.

For example, cleaning the tubes with a mild acidic solution is an accepted and

widely used technique especially with EDG intercoolers where the consequences

of contamination can have major safety significance. It is noteable that, because of the manufacturers recommendations, the intercooler of EDG 'E'was

not cleaned by sandblasting and the engine was not affected by the above

condition.

\I-

_,>IN 90-80

December 21, 1990 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate NRR project manager.

r

I-V

Charles E. Rossi, Dirkctor

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

J. Rajan, NRR

(301) 492-0788 Attachment: List of Recently Issued NRC Information Notices

Attachment 1 IN 90-80

December 21. 1990

Page I of I

LIST OF RECENTLY ISSUED

NRCINFORMATION POTICES

Information Date of

Notice No. Subject Issuance Issued to

90-79 Failures of Main Steam 12/20/90 All holders of OLs or

Isolation Check Valves CPs for nuclear power

Resulting inDisc Separation reactors.

90-78 Previously Unidentified 12/18/90 All holders of OLs or

Release Path from Boiling CPs for boiling water

Water Reactor Control Rod reactors (BWRs)

Hydraulic Units

90-77 Inadvertent Removal of Fuel 12/12/SC A11 holders of OLs or

Assemblies from the Reactor CPs for pressurized- Core water reactors (PWRS).

88-23, Potential for Gas Binding of 12/10/90 All holders of CLs or

Supp. 3 High-Pressure Safety Injection CPs for pressurized- Pumps During A Loss-Of-Coolant water reactors (PWRs).

Accident

90-76 Failure Of Turbine Overspeed 12/7/90 All holders of OLs or

Trip Mechanism Because Of CPs for nuclear power

Inadequate Spring Tension reactors.

90-75 Denial Of Access To Current 12/5/90 All Michigar holders

Low-Level Radicactive Waste of NRC licerses.

Disposal Facilities

90-74 Information orPrecursors To 12/4/90 All holders of OLs or

Severe Accidents CPs for nuclear power

reactors.

90-73 Corrosion Of Valve-To- 11/29/90 All holders of OLs or

Torque Tube Keys In CPs for nuclear power

Spray Pond Cross Connect reactors.

Valves

90-72 Testing of Parallel Disc 11/28/90 All holders of OLs or

Gate Valves InEurope CPs for nuclear power

reactors.

90-71 Effective Use of Radi- 11/6/90 All NRC licensees

ation Safety Committees authorized to use by- to Exercise Control Over product material for

Medical Use Programs medical purposes.

OL : Operating License

CP

• Constructior. Permit