Information Notice 1991-46, Degradation of Emergency Diesel Generator Fuel Oil Delivery Systems

Degradation of Emergency Diesel Generator Fuel Oil Delivery Systems

ML031190492
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:	07/18/1991
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-91-046, NUDOCS 9107110017
Download: ML031190492 (6)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 .

July 18, 1991 NRC INFORMATION NOTICE NO. 91-46: DEGRADATION OF EMERGENCY DIESEL

GENERATOR FUEL OIL DELIVERY SYSTEMS

Addressees

.

All holders of operating licenses or.construction permits for nclear -power

reactors..

Purpose

This information notice is intended to alert addressees to otential i

inoperability of multiple emergency diesel generators (EDGs resulting from

common cause degradations: (1) degraded fuel oil delivery systems and,

(2) failure to meet Technical Specification (TS) testing requirements intended

to detect potentially degraded quality of the fuel oil stored on site. 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

Over the past four years, several licensees have-submitted licensee event

reports (LERs) describing degradations in EDG operability or-other

safety-related equipment attributable to problems with the fuel oil system.

Descriptions of selected LERs are presented below to illustrate three classes

of problems.

I. Inappropriate painting of fuel injection assemblies

McGuire Unit 1: On June 25,.1990, while the unit was operating at full

power, the licensee, Duke Power,.declared'two EDGs inoperable on discovery

that paint had been inappropriately sprayed on the exciter commutator

rings and on.the back side of the fuel rack pivot.points...This condition

• .prevented the EDG output from attaining the TS-required 4160 volts in the

allotted time (11 seconds).. (LER,50-369/90-17-01)

Palo Verde Unit 3: On March 28, 1990, while the unit was operating at

full power, the licensee, Arizona Pubiic Service, discovered paint in the

ports for the EDG fuel pump fuel oil metering rods, making the. EDG inoper- able, because the paint would most likely have prevented operation.of the

fuel oil injection system. (LER 50-530/90-03)

9107110017 V tl 4

- lia tit't, 9 It-o0 9 to 910$ 1

IN 91-46 July 18, 1991 Byron Unit 1: On March 28, 1989, while the unit was

80 PeFiFof full power, the licensee, Commonwealth operating at

Edison, discovered

that an EDG failed to start during the monthly surveillance test because

inappropriately applied paint was binding the fuel oil metering rods

thus preventing the EDG from getting enough fuel and

oil to start.

(LER 50-327/89-25)

II. Fouling of fuel oil filters or strainers

Dresden Unit 2: On December 24, 1988, while the unit was shut down, all the reactor fuel removed from the reactor vessel, and with both with

reactor protection system (RPS) buses being powered from one EDG,

frequency decreased below the setpoint of the underfrequency relaysthe EDG

associated with the motor-generator sets. When the relays actuated, RPS buses were deenergized, resulting in a scram signal on both RPS the

channels. The standby gas treatment system was automatically initiated -

and the reactor building ventila-tion system was automatically isolated.

The licensee, Commonwealth Edison, determined the root cause to be-a'"

fouled fuel oil filter. (LER 50-237/88-20)

Turkey Point Unit 3: On September 20, 1988, while the unit w'as operating

at full power, the licensee, Florida Power and Light, declared its

inoperable due to high fuel oil pressure. At the time of the event,B.EDG

Unit 4 was shut down and the A EDG was out of service for maintenance.

The licensee'determined the root cause to be an'excessive interval'between

fuel oil filter replacements that allowed gradual accumulation of

late matter inthe filter. (LER 50-250/88-22) particu- Ginna: On February 20, 1987, while the unit was shut'down- and with

sfalton electrical power being supplied by the EDGs, the licensee, all

Rochester Gas and Electric, discovered low fuel oil levels-in both

day.

tanks because the fuel oil transfer pump suction strainers were partially

plugged. The particulate contamination was analyzed as weld flux

from

plant construction activities and fibrous material from either cleaning

rags or filter media. The licensee had to drain and flush the fuel

transfer pump suction piping several times to prevent plugging of

strainers when the fuel-oil from the storage tanks was recirculated. the

(LER 50-244/87-01)

III. Potential degradation-of fuel oil quality, as measured by licensees'

TS

Susquehanna Unit 1: OnJuly 26, 1990, with both units operating at

power, te Tcensee, Pennsylvania Power and Light, declared an EDG. full

able because a sample of fuel' oil from a storage tank exceeded its inoper- limit for the concentration of insoluble matter (2mg/100 ml, using TS

ASTM-D2274-70 oxygen accelerated stability test), indicating a loss the

stability of the stored'fuel oil. (LER 50-387/90-15) of

Perry Unit 1: On April 5, 1990 (LER 50-440/90-05-01), and on

January , 1989 (LER 50-440/89-01-01), the licensee, Cleveland Electric

Illumination, declared safety-related equipment inoperable

sample of fuel oil from a storage tank exceeded its TS limitbecause

for the

a

IN 91-46 July 18, 1991 concentration of insoluble matter (2 mg/100 ml, using the ASTM-D2274-70

test). In April 1990, the licensee declared its high-pressure core spray

system inoperable'while the unit was operating at full power and in :

January 1989, the licensee declared an EDG inoperable while the unit was.

operating at 70 percent of full power. In the April 1990 event, the

licensee attributed the degradation to a contaminant found in the biocide

additive and to-degradation of'the material coating the storage tank. In

January 1989, the licensee believed the fuel oil aging was accelerated by.

the addition of new fuel oil a few days before the.event. .

WNP Unit 2: On January 3, 1990, while the unit was operating at full '

power, the licensee, Washington Public Power Supply, declared all three of

its EDGs inoperable, because an EDG fuel oil test of samples drawn on

December 27, 1989, indicated that the fuel oil in all three storage tanks

did not meet the oxygen accelerated stability criterion, and entered the

limiting condition of operation (LCO) for TS 3.0.3. At the time'of this

report, the licensee's TS required that EDG fuel oil be tested.in aIccor- dance with the standard ASTM-D2274-70, with particulate contamination not

exceeding 2 mg/100 ml. The licensee reviewed past surveillance results, which were typically half the TS limit, found no discernible trends, and

consulted two fuel oil experts, who indicated that no reason existed forka

step increase in the stability measure.

The licensee believes the root cause of this event to be the fuel oil

analysis method. The licensee submitted an emergency amendment,.which

included the substitution of a filter cleanliness test based on the

standard ASTM-D2276-78, Method A, with particulate contamination not

exceeding 10 mg/l, for the oxygen accelerated stability test based on

ASTM-D2274-70. On March 30, 1990, the NRC temporarily approved-the.

amendment. On June 4, 1990, the NRC permanently approved a yrevision of

the amendment that-included changes in addition to this test substitution,,

The' filter cleanliness test is designed to measure particulate contamina-,'.:

tion existing in the fuel oil whereas the oxygen accelerated stability ..

test is designed to measure the potential of-the fuel oil for forming

gums, varnishes, and tars in the future. The filter cleanliness test

results for the samples of fuel oil drawn on December 27, 1989, were

acceptable. Results of both the-oxygen accelerated stability test and the

filter cleanliness test for samples drawn from both tank bottoms and

transfer pump discharges on-January 2, 1'990, and on January 3, 1990, were

acceptable. (LER 50-397/90-01)

Diablo Canyon Unit 1: On May 5, 1988, while the unit was shut down, the

licensee, Pacific Gas and Electric, observed the power output. of an EDG to

decrease below the licensee's acceptance criterion for a 24-hour load

test. The licensee determined that the primary fuel oil filter had.become.

clogged with a fungus growing in the day tank supplying that EDG. The

licensee also found fungus and spores in the other day tanks and in the

fuel oil storage tanks. The licensee added a.biocide and filtered the, fuel oil in the'day tanks until its acceptance criteria were met for.flash'

point, gravity, viscosity, and particulate contamination (10 mg/l, using

the ASTM-D2276-78 Method A, particulate contamination test).

(LER 50-275/88-145

IN 91-46 July 18, 1991 Discussion:

The lessons to be learned from the LERs that deal with inappropriate painting

incidents are'self-evident. Similarly, the LERs that deal with partially

plugged fuel'oil filters or strainers show that regular and careful maintenance

of these components is important to reliable EDG operation. In particular, these LERs show that the.-period of time between replacement of filters and

strainers should not be excessive and that cleanliness.of maintenance opera- tions performed on the fuel.deli'very system is important. The subject of

filter maintenance was previously discussed in NRC Information Notice

No. 87-04, "Diesel Generator Fails Test Because of Degraded Fuel." Some of the

LERs on TS testing problems are concerned with actual degradations of fuel

oil

quality but primarily address' the particular test used in the TS.

The main concern with- degraded EDG fuel oil (particulateicontamination) lies

its potential for clogging filters, strainers, and fuel injection equipment in

through which the fuel oil. must flow and thus..causing 'engine fai'lure. All-fuel

oil tends to degrade in.two general ways during extended storage. The first, way is oxidation and polymerization of the fuel oil to yieldsoluble and.'

insoluble gums. The second way is clustered microbiological growth of.bacte- ria, fungi, or yeasts.ot the interface of the fuel oi.l and water present

bottom of the storage tank. Through chemical processes, the bacteria'produce at the

solids and additional water. The bacterial solids may accumulate in the

of the fuel storage tank and not pose a problem for EDG operability until bottom

fuel transfer pump draws them into its suction pipe. All these solid mate-the

rials, the gums, the microbiological growth, and the bacterial sludge, as

as foreign debris, are collectively called particulate contamination. well

Focusing on the question of degraded fuel oil quality, note that several.

standards are used in individual plant.TS requiriements for testing EDG fuel

oil. Most plants use the American Society for Testing and Materials (ASTM)

"Standard Specification for Diesel Fuel Oils," ASTM-D975-XX, where XX-rrepre- sentsthe year of the modification used, for testing the quality qf fuel oil, both freshly delivered and stored. It includes tests for a number of fuel

properties, including flash point, cloud'point, distillation temperature, water

and sediment content, carbon, residue, ash content, sulfur content, viscos.ity, corrosive potential, and Cetane number (ignition quality). Some plants' TS,

only require the water, sediment, and viscosity tests.. Some plants' TS contain

a requirement for:-the oxygen accelerated'stability test described in "Standard

Test Method for Oxidation Stability of Distillate Fuel Oil (Accelerated Method),"

ASTM-D2274-XX, and some plants' TS contain a requirement for the particulate

contamination test described in "Standard Test Methods for Particulate Contam- inant ian Aviation Turbine Fuels," ASTM-D2276-XX. The American Nuclear Society

(ANS) in its standard approved bythe American National Standards Institute

(ANSIS, "Fuel Oil Systems for Emergency Diesel Generators," ANS.I/ANS-59.51-1989, recommends in AppendixtC the ASTM-D2276-XX particulate contamination test.

The ASTM-D975 standard is intended as a statement of permissible, limits of

significant fuel properties used for specifying the' wide variety of commercially

available diesel fuel' oils. As such, it most readily applies to determination

of the quality of new fuel oil, but does not readily apply to the question

of

IN 91-46 July 18, 1991 particulate contamination in stored fuel oil. The oxygen accelerated stability

test of the ASTM-D2274 standard .predicts the potential for future degradation

of fuel oil but does not show the existing st-Ne of degradation. On the other

hand, the particulate contamination test of the ASTM-D2276 standard readily

applies to the question of particulate contamination in stored fuel oil.

Revision 4A of the Westinghouse Standard TS (STS) contains comprehensive oil, in

requirements on testing and monitoring the condition of stored EDG fuel

which the salient features are (1)use of the ASTM-D2276 particulate power contami- nation test and (2) testing for and removal of water. Some nuclear

plants, such as McGuire Units 1 and.2, Wolf Creek, Limerick Units 1 and individ- 2, and

WNP Unit 2, have voluntarily adopted this revision of the STS in their

ual plant TS. In the LER for WNP 2 (above), the licensee determined that

incorporation of this total program in its plant TS was an effective corrective oil. The

action for its problems in determining the quality of its stored fuel guidance on

Electric Power Research Institute (EPRI) has provided additional

this point in "Storage and Handling of Fuel Oil for Standby Diesel Generator

Systems," EPRI NP-63140, August 1988.

This information notice requires no specific action or writtenplease response. If

you have any questions about the information in this notice, call one of

the technical contacts listed below or the appropriate NRR project manager.

harles~E.Ross Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical Contacts: Vern Hodge, NRR Frank Witt, NRR

(301) 492-1861 (301) 492-0767 Ed Tomlinson, NRR Pete Prescott, NRR

(301) 492-3150 (301) 492-1011 Attachment: List of Recently Issued NRC Information Notices

Attachment 1 IN 91-46 -

July 18, 1991 Page 1-of 1 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

91-45 Possible Malfunction of 07/05/91 All holders of OLs or CPs

Westinghouse ARD, BFD, and for nuclear power reactors.

NBFD Relays, and A200 DC

and DPC 250 Magnetic Con- tactors

91-44 Improper Control of 07/08/91 All nuclear fuel facilities.

Chemicals in Nuclear Fuel

Fabrication

91-43 Recent Incidents Involving 07/05/91 All holders of OLs or CPs

Rapid Increases in Primary- for pressurized-water

to-Secondary Leak Rate reactors (PWRs).

91-42 Plant Outage Events 06/27/91 All holders of OLs or CPs

Involving Poor Coordina- for nuclear power reactors.

tion Between Operations

and Maintenance Personnel

During Valve Testing and

Manipulations

91-41 Potential Problems with 06/27/91 All holders of OLs or CPs

The Use of Freeze Seals for nuclear power reactors.

88-63, High Radiation Hazards 06/25/91 All holders of OLs or CPs

Supp. 2 from Irradiated Incore for nuclear power reactors, Detectors and Cables research reactors, and

test reactors.

91-40 Contamination of Non- 06/19/91 All holders of OLs or CPs

radioactive System and for nuclear power reactors.

Resulting Possibility for

Unmonitored, Uncontrolled

Release to the Environment

91-39 Compliance with 10 CFR 06/17/91 All Nuclear Regulatory

Part 21, "Reporting of Commission (NRC) material

Defects and Noncompliance" licensees.

91-38 Thermal Stratification in 06/13/91 All holders of OLs or CPs

Feedwater System Piping for nuclear power reactors.

OL = Operating License

CP = Construction Permit