Is Imply Defer To:

5055. 0-2

W0329, 50-3W0 50-M91 50-5" 50-567

tNW STATIS INCLEM -- I ULATORY Comm1

mINAo. "CC& O

AN2 S g

Tennssee Valley Auhort~y Attn: 3. G. Farris

Manager of powr 50m C*Stm: Street lowr 11 Oiarttmoap. Thinses.. 37401

Ginstlmfsa:

The enclosed 1E Circular Uc. 79,-1:. is forwarded to you f or Information. go written response Is required. Should you have aY questions related to your uinderstanding of this natttf, pleas contact this office.

Sincerely.

Director

Inc losures: 1. 1E Circular No. 79ý-12 2. List of IE Circular s

issued in Last 1 Months

347 u S790718 0 LP13

"Oým

iml8 -

Somet voefy AhuIity

"Stimm amosr of "atf 18K Chntint Street iswer 11

.ttamep. Imernes 3740)

&. 1. mulls

best OMact In. 2w0 voUlwsm". Aubbe. 35h

V. 3. Nkte, F,.:t bessel Post 0ff ac. N am 2

J~w. Y .CO eBem 5

400 C"efc. Street VI1K31 C

IS. . kfillt ensi 70

Chattabowe I)ma

3. 6. *,w~e" Post Offh. kml 2w0 ftcatul. alabaS 3402

81. It. Ws"~l Project £etiamIe 460 CMeetet Stret lever 2

.mtteeo*ge -?wo 3740)

3. 1. vatbcgt* Project Nblser Feet off ae lsn 300 lorteoille. To s 370)4

J. 3. wills* Project £.gseer 400 Chetaot Street 7ror 11

V. P. 31e 'Pr 'oject lbseg* best 01 tace son2000

gwrg*ise*vlI. ees se 37673#

6.6. stocks Pro Oct Nol jr Feet offic ba 0 Sawy. trewomef377 347 0

UsW6 bSIle btborltl-1ii

3. N. valleaust

rmt office In 2w Daisy* ?.inessff P31

w Cntmt street Tong 11

3. 7. Or4"15. niet siverist*SdIt ftst off fi'e anz am $prim city, ?eomoss" "3618

1. a. m.rtberswit Jr. ?ceject Usavlr pest office &ea am0 SPVWa City, ?enmeseff 3738)

a. N. price. " W.e~ ba.W ftst office 3ns 2w0

34/ Y

WIlED STATES RICIIAM UWIMATV CO3ISJ

Orrici OF 1SIunCTIo ANDU- CM WSKINGTC5. D.C. 20555

Jew n., 1979

lIt Circular ISO. 79-12 I0

POTENTIAL DIESEL GEIERATOR 11-0OCRARGEN PROSLEN

Description of Circumstances:

?be Electro-Ilotive Division (V2)) of General Mfotors Corporation has recently identified a potential failure mode of turbochargers used en EM diesels in nuclear plant standby service.

When an e"gine is is the normal standby mode, the lubricating oil temperature is maintained at. about 115 degrees &and the circulating oil pum supjszes ware oil to the turbocharger bearings at a f low rate of about 2 gm. Since the total oil pum flow rate is 6 gpm, I. gm is also circulated. via a 30 psi relief valve. through the lube oil filter sand cooler which serves to keep the sntire accessory lubricating oil system primed to support a ivst start. If a power outage occurs, the oil circulating pum may stop 5 to 10 seconds before the engine receives a start signal; but the wain bearing and piston cooling somp will immediately receive oil f rem the primed lube oil filter-cooler s)stem thus providing a rapid buildup of engine lube oil pressure throughout the engine bearing and turbocharger systems.

A potential problem occurs. however, if the diesel engine receives a repeat rapid start within a minimum of 15 minutes and a maximum of 3 hours after a shutdown from a previous run is which the engine has reached full operating temperature. 1f, for example. the engine had been oiperst.-d for about I hour at full load, the lube oil temperature would be at ebout 20!) degrees F at time of shutdown. Under these circumstances, the full 6 go output of the circulating pump will flow only to the turbocharger bearings because of the lower viscosity of the hot lubricant. At this temperature, the circulating puny pressure will sot reach 30 psi. Until the lube oil cools to about 160 degrees F. me oil will be supplied via the relief valve to the equipment rack for the first 2 to 3 hours after engine shutdown During this cooling period sowe of the *il contained an the cooler and filter will drain back to the engine sur; via the lube oil scavenging pump. and some of the oil from the strainer box will he drawn into the cooler by the system vacuum that develops. The result is that when a repeat fast start occurs within the above 15i minute to 3 hour time frame after a hot shutdown, lack of prime oil system pressure can cause engine damage. In the worst case of a repeat fast start, the engine may actually reach operating speed, 900 W.i before the required oil pressure is ,etablished at the turbocharger thrust bearing. this may cause sow smearing of the bearing metal so that eumulative damage from several similar starts would result in a torbeeharger failure.

347 It! I

IS Cifrials" So. 79-12 JUMP 25. 1979 Fage 2 of 2

IND is Carmetly developing a modification to improve the lobe oil systemý It is pleassed that this modal acatzon waill be available for imstallatioe to @logo imattly 4 months. In the iater&*. the following actioms are reromeode for those having [ND diesel engines:

I. bpeated fast hot starts Within a minimu 15 minute to 3 hour tawn framw after shutdown should be avoided. Allow the engame to cool at least 3 hours after it has been operated in the "loaded" made. or othervise a retart should be performed within 1$ minutes of shutdown.

2. After chianging oil filter elements or drainang the accessory oil system for any reason, and upon refilling of the system make sure that the circulating oil pump is in operation for at least 30 minutes and that the strainer box as fell before starting engine. The engine should then be brought to an idling condition to assure comlete filling of accessories before any subsequent fast start is made.

3. Any small leak at the top of Lhe oil cooler should be corrected. A leak at this location allows air to be drawn into the cooler during shutdown. which wall cause the drain back to be more rapid.

4, Avoid testing of the redundant diesel engines concurrently. Were at is necessary to run the redundant diesels concurrently. maintain one diesel in the running mode for a minimu of 3 hours following the shutdown of the other.

No written response to this Circular is required. If you require additional information regarding this subject, contact the Director of the appropriate NRC Regional Office.

341 Al1

act Crcular so. 9- 12 ima U. 1979

Enc losure Page I of 3

LISTING OF It CIRCUIARS ISSUED 15 LAST MIV1 MNWIT

Subject

15-32

75-13

78-15

78-16

78-17

78-18

71-19

circlar so.

Issued ToDate of I ssue

6/30 f'78

7/10/78

7/12/78

7/20/78

7126178

10113/78

11/6/79

12/28/78

341 0 4 3

VCl Turbine Control Valve Lift Rod lending

InoWerability of Multiple Service Vater Pumps

NPC1 Turbyat Reversing Chamber Bold Dawn bolting

Cbeckvalves Fail to Close In Vertical pos it ion

Limitorque Valve Actu.ators

Inadequate Guard Traoiang/ Qualification and Falsifa.+i Training Records

UlL Fire Test

Manual Override (bypass) of Safety Actuation Signals

All Solders of WA OLs or CPs, for plants vitlt NPCI Terry Turbine

All Nolders of Reactor OLs and Cli except for plants located in: AL. AU. EA, nt. GA, LA. Ms. SC

All Solders of P8R OLs or CIPs for plants with a DCI Terry Turbine except ing ova"e Arnold and Monticello

All Solders of Reactor OLs or Cps

All Holders of Reactor OLs or Cps

All Molders of and applicants for Reactor OLs

All Holders of Reactor OLs or CPs

All Solders of CPS

LISTING OF If CIRCULARS ISStXD IN IAST TWiV-E MOPTHS

Date of Issue

Enc loasre Page 2 of 3

Issued to

"-01

79-02

79-03

79-04

79-05

79-06

79-07

1/12/79

2/16/79

2/23/79

3/16/79

3/20/79

4/19/79

5/2/179

Administration of Usautborized Byproduct Material to Houans

Failure of 120 Volt Vital AC Power Supplies

Inadequate Guard TrainingQualification and Falsified Training Records

Loose Locking Nut On, Limitorque Valve Operators,

Moisture Leakage In Stranded Wire Conductors

Failure to Us Syringe and Rattle Shields ina Nuclear Medicine

Unexpected Speed Increase of Reactor Recirculation NG Set Resulted in Reactor Power Increase

Atteereted .;utort ion - Lou torich4 Uýranium,

Occurrence& of Split or Punctured Regulator Diaphragms Is Certain Self Ceutainwd Dreatbing Apparatus

All Holders of Licensees exept Teletberapy Medical Licensees and each Rads opiarmareut acal Suppliers

'All Holders of Reactor OLs sand CPS

All Holders of and applicants for Special Nuclear Material Licenses to Safeguards Group I

All Solders of Reactor OLs or CPs

All Holders of Reactor OLs or CPs

All Holders of Medical Licensees except teletberapý licensee

All Holders of MR OL's or CP's

All Fuel Facil-tzir Licensed by Wi

All Materials Priority I. fuel Cycle sod Operating Reactor Licensees

347 C. 414

KI Circular No. 79-12 Jam n, 1979

Circular U1. .

Subject

6/22/79

It Circular go. 79-12 June 2S8, 1979

Circular U..-

Enclosure Page 3 of 3

LISTING OF 1K CIRCULARS ISSUED IN IAST IWVELIP HOKTR

Subject D6te of Issued

Pipefittings Manufactured from Unacceptable Mlaterial

Des agnlConstructiou Interface Problem

6/26/79

6/27/79

79-10

79-11

All Power Reactor Licensees with a CP and/or 01.

All Applicants for. and Nolders of Power Reactor cps

J4 ~

Issued to