ML20081C147

Rept on Div I,Ii & III Diesel Generators

ML20081C147
Person / Time
Site:	Grand Gulf
Issue date:	10/22/1983
From:	Duane Hardesty, Stalsberg D, Taylor J MISSISSIPPI POWER & LIGHT CO.
To:
Shared Package
ML20081C136	List: AECM-83-0689, Forwards Rept on Div I,Ii & III Diesel Generators, in Response to NRC Request & Generic Problems Identified in IE Info Notice 83-51 ML20081C147
References
REF-SSINS-6835 83-024, 83-24, NUDOCS 8310310130
Download: ML20081C147 (56)

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i J Enclosure to AECM-83/0689 GRAND GUIE NUCLIAR STATION UNIT 1 1

i REPORP ON THE DIVISION I, II and III

, DIESEL GENERA'IORS l.

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October, 1983 8310310130 831026 PDR ADOCK 05000416 G PDR

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NUCLEAR PIR7f ENGINEERI?E OPERATIOtmL ANALYSIS SECTION DIVISION I, II, AND III DIESEL GENERA'IOR OPERABILITY REPORT REEOlfr NO.: 83-024 DATE: October 22, 1983 I

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! PREPARED:AJ. Stalsberg W. Hardesty,4f.' Taylor ) / /s/2-v/p3 g v < DATs 7/,S. Kline,[D. Kaelber //o/2>/J3 REVIBED: / /0 22/A3 APPROVED: [//d/j

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/ DATE '

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e TABLE OF CONIHTIS PAGE

1. 0 ABSTIUCr . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.0 INTRODUCTION

.......................................... 2 3.0 DESIGN CRITERIA ....................................... 3

4. 0 PREOPERATIONAL HIS'IORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.0 OPERATIONAL HISIORY ................................... 11

6. 0 Ftr.TABILITY DEANCEMNTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

7. 0 INDUSTRY COMPARISON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 8 . 0 SUbNARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 9 . 0 COtCUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 10 . 0 mrtmNCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 ATTACIDD7IS ATr7CHMENT 1 - D/G DESIGN PARABETERS . . . . . . . . . . . . . . . . . . 28 ATTACIBE7r 2 - CLARIFICATION OF REQUIREMENTS 'IO HYDROSTATICALLY TEST HPCS DIESEL GENERA'IOR SKID-MOUNTED AND STANDBY DIESEL GENERA'IOR AUXILIARY SYSTal

[ FUEL OIL, COOLING WATER, AIR START, LUBE OIL] PIPING ....................... 29 ATTACINENT 3 - CLARIFICATION OF DESIGN STAh0ARDS FOR ENGINE-MOUNIED C01PONEtTIS (DIVISION I AND II DIESEL GENERA'IORS) .............. 30 ATrACIEENT 4 - DIESEL GENERA'IOR START TIbES . . . . . . . . . . . 32 ATTACIE D7f 5 - GGNS D/G OPERATING DATA ................ 36 i

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TABLE OF 00N1HTIS (CONTINUED)

ATTACHMENT 6 - IMPIINENTATION OF NFC I&E BULIETINS, CIBCUIARS AND INEORMATION NOTICES AND INPO REPORTS RELATED 'IO DIESEL GENERA'IOR PROBLENS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 ATTACHMENT 7 - DIESEL GENERA'IOR LERs SORTED INIO ROOT CAUSE CATEGORIES ....................... 45 ATTACHMENT 6 - DIESEL GENERA'IOR LERs IN THE PEOPLE REIATED CATEGORY . . . . . . . . . . . . . . . . . . . . . . . 46 ATTAONENT 9 - APPLICABILITY OF SHOREHAM DEIAVAL DIESEL GENEPA'IOR CRANKSFAFT FAIIERE 'IO GGNS . . . 47 ii

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49 1.0 ABSTRACT

' Itis report sumarizes the performance of the standby diesel generators installed at the Grand Gulf Nuclear Station (GGNS) . Unit 1 has three (3) diesel generators; two (2) were manufactured by Transamerica Delaval, Inc.

('IDI) and the third was manufactured by the Electro 410tive Division (HSD) of General Motors.

The TDI diesels are dedicated to providing power to loads required to operate during post-accident conditions. The 'IDI diesel engines and associated Portec generators were supplied under the Bechtel scope of supply. The D4D diesel and associated Portec generator is dedicated to powering the High Pressure Core Spray (HPCS) System and was supplied under the General Electric (GE) scope of supply.

The report contains a description of the design criteria and operational history of the diesel generators. The information presented in this report highlights problems that have occurred with diesel generators, both at GGNS and within the industry, and indicates how these problems have been addressed at Grand Gulf.

Also described are measures which are being taken to enhance the reliability of the diesel generators. The measures incorporate recmmendations made by NBC, INPO, and vendor documents, the GGNS Operational Analysis Section (OAS) of Nuclear Plant Engineering (NPE), the GGNS Safety Review Cm mittee and available industry sources.

A cmparison of the performance of the diesel generators with the industry is also sumarized. Included in this comparison is a sumary of the Shoreham diesel generator crankshaft failure and its applicability to the GGNS diesels. Overall, the performance of the GGNS diesel generators appears to be cmparable to industry performance in most categories.

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2.0 IMPODUCTION i MP&L's Grand Gulf Nuclear Station'is a 2-unit N R/6 plant with a Mark III containment. Each unit has a rated capacity of 3833 mt or 1306 me. Unit 1 is cmplete and was loaded with its initial core in June,1982. Power ascension and low power testing began on Unit 1 on Septerober 25, 1983.

The Engineering Safety Features (ESF) electric loads for each Grand Gulf unit are divided into three (3) divisions (Division I, II, and III) .

Correspondingly, there are three (3) independent sources of onsite

' energency power. Wree diesel generator sets serve each Grand Gulf unit.

'LNo of them supply power to ESF Division I and II, and are manufactured by Transamerica Delaval, Inc. , (TDI) . The third diesel generator is manufactured by the Electro-Bbtive Division (D1D) of General Motors, and is a dedicated onsite emergency power supply for the reactor vessel High Pressure Core Spray (HPCS) systen (ESF Division III) .

W e gene ators for all three diesels are manufactured by the Electric Products Division of Portec, Inc. They are designed with a 10%, twc>-hour overload capacity. The DeLaval diesels are model DSRV-16-4. E is is a V-type 16 cylinder machine rated at 9770 HP and 7000 Kw at 450 RPM. The Do diesels (HPCS dedicated) are nodel 12-645E4. 'IWo diesels are tied to one generator. These two V-type 12 cylinder machines have a cmbined rating of 4610 HP and a generator rated at 3474 Kw at 900 RPM. -

The main design parameters of the DeLaval and DO diesel / generators are

listed in Attachment 1.

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• i 3.0 DESIGN CRITERIA The onsite diesel generators (D/Gs) and their associated support systems

- and ammts have been designed to provide a reliable backup source of power to equignent required to operate should the preferred offsite power

supply fail or degrade to unacceptable levels. 'Ib provide sme level of assurance that the diesel generators can perform this function, they have been designed to meet or exceed the requirernents of various NBC regulations

, and industry standards.

As described in FSAR Section 8.3, the diesel generators meet the requirements of General Design Criteria (GDC) 17,18, and 21 of 10 CFR Part 50, Appendix A, Regulatory Guides (BGs) 1.6, 1.9, 1.29, 1.32. and 1.108, and T m Standards 308-1971 and 323-1971 or 1974, as appropriate. '1hese 2

requirements ensure that the diesel generators have sufficient irdependence, t redundancy, and capacity, permit periodic inspection and testing of all essential areas and features, can survive earthquakes, tornadoes, and pipe breaks, and can take a single failure.

. FSAR subsections 9.5.4, 9.5.5, 9.5.6, 9.5.7 and 9.5.8 provide additional i details of the design bases for the diesel generator fuel oil syst s ,

cooling water system, starting system, lubrication system and cm bustion air intake and exhaust system, respectively. 'Ihe diesel generators have 4 been designed to seismic Category I requirements, can take a single active i or passive failure, and have been protected fr m or qualified to the environment created by a pipe break. These syst e design bases are sunnarized in FSAR Table 3.2-1.

In addition to the requirements described above, the design of the diesel l

generators also meets the criteria of T N Standard 387-1977, the ASME Code i (1974 edition), ANSI Standards, ASIM Standard Specifications, DENA Standard j Practices, as well as other agolicable codes, standards, and regulations.

I The information provided in the above referenced FSAR sections has been j supplemented in various responses to NBC Power Systems Branch (PSB) concerns in the Safety Evaluation Report (SER) . Responses to concerns with the engine-mounted piping, fuel oil drip return system, cooling water

- system, starting air system, lubricating oil system, and ccmbustion air

! intake and exhaust system, have been provided in AE m-82/262, dated l June 10, 1982, AE m-82/459, dated August 9, 1982, and AE m-81/324, dated August 26,.1981. Based on these responses the NBC has found that the diesel generators and their associated support systems and cmponents meet the requirements of the appropriate GX's, Regulatory Guides, and Standard Review Plan (SRP) sections, perform their design function, and meet the

! reocmnendations of NUREG/CR-0660, "Enhancment of Onsite Dnergency Diesel

[ Generator Reliability," and appropriate industry codes and standards,

! except for the following.

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3.0 (Continued)

The NBC has requested in Supplement 4 to the SER (SSER 4) that prior to startup following the first refueling outage,1) the EMD diesel generator be provided with a heavy duty turbocharger gear drive assenbly, 2) confirmation that the HPCS diesel skid-mounted and standby diesel auxiliary systems piping has been hydraulically tested to at least 125% of design pressure be provided, and 3) upgrade of the standby diesel ccrobustion air intake and exhaust system to augmented Quality Group D requirements be performed. These requirements are reflected in License Conditions 2.C. (33) (a) (1) , (2), and (3), respectively.

A discussion of License Condition 2.C. (33) (a) (2) is provided in Attachment

2. This discussion clarifies the requirements used for leak testing the fuel oil, cooling water, air start, and lube oil piping.

Additional information regarding the design standards for the standby diesel generator engine-mounted canponents is provided in Attachment 3.

This information is intended to clarify statements made in SSER 4 and to reiterate the results of an audit of Transamerica DeLaval, Inc. ('IDI) performed to verify the adequacy of the engineering controls imposed on the design and fabrication of engine-mounted components. In addition to this audit, many checks of the quality of the standby diesels were made during procurenent and manufacture.

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4.0 PREDPERATIONAL HIS'IORY The pse of this section is to sumarize the history of the GGNS Unit 1 diesel generators (Divisions I, II, and III) frm the time of purchase to when the GGNS Operating Licensing (OL) was issued (June 16, 1982).

4.1 ~ Division I and II Diesel Generators The Division I and II D/Gs were purchased under Specification 9645-M-018.0. Operational and functional prototype testing for these D/Gs was performed on the Division.I D/G. The prototype diesel was tested for start and load reliability by conducting 300 successive starts and run to reach normal operating oil and water tenperatures.

Testing was successfully coupleted by 'IDI in late 1976. Operability testing included the starting air system, sequential loading, load shedding, margin, endurance and load capability testing.

'IDI coordinated the seismic qualification of the D/Gs. SSER 4, reflects the emplete seismic qualification of these units.

Delivery of the Division I and II D/Gs and the associated auxiliary systerns comenced on March 24, 1977 and continued through August 1977.

Upon receipt, the equipnent was transported to appropriate storage facilities and laid up in accordance with manufacturer's reconmendations.

Following installation of the D/Gs and prior to issuance of the OL, several events occurred which could have had an inpact on the reliability of these D/Gs. A sumary of these early events is provided below.

4.1.1 Link Rod Assmbly A 'IDI letter, dated September 22, 1980, notified the NBC of a 10 CFR 21 potentially reportable condition in which the dowel counterbore in the link rod may be too shallow. Such a defect could lead to link rod bolt failure, thereby rendering the D/G unavailable. TDI similarly notified MP&L of the possible deficiency and outlined procedures for inspection of the link rod assa blies and criteria for determining acceptability.

Subsequent inspection revealed that critical dimensions were within specified tolerances.

4.1.2 Piston Separation The Division I and II D/Gs are provided with two piece pistons. 'Ihese pieces, the crown and skirt, are bolted together with four studs each.

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4.1.2 (Continued)

During preoperational testing of the Division I D/G, in Novenber,1981, the crown and skirt of one piston separated causing a discernable change in engine sound. The D/G was manually shut down and inspected. Examination of the piston revealed a failure of the hold down studs adjacent to the spherical washers used under the bottm stud nuts. 'IDI was contacted for information regarding similar failures.

'IDI transmitted Service Information Memo (SIM) 324, dated November 10, 1980, outlining corrective action to preclude the subject event. SIM-324 attributed the failure cause to the use of spherical washers and specified as replacement Belleville washers. All pistons in the Division I and II D/Gs were returned to 'IDI for rework. The reworked pistons were installed at GGNS per manufacturer recmmendations.

4.1.3 Lubrication of the Turbocharger Thrust Bearing The lubrication oil system does not supply lube oil to the turbocharger thrust bearing until the lube oil pump initiates upon engine startup. This condition, which causes accelerated bearing wear and could lead to premature failure, was reported to the NRC under the provisions of 10 CFR 21 via 'IDI letter dated Decmber 16, 1980. Redesign of the lube oil syst s to preclude this condition was provided by the vendor and implemented by MP&L. This redesign added a continuous drip lube oil subsysts.

4.1.4 Air Start Valve Capscrews Each air start valve arsembly (16 per engine) is mounted to the cylinder head with 2 3/4-10 X 3 inch steel bolts. A TDI letter, dated June 11, 1982, notified MP&L that the counting l capscrews may be bottating out in the cylinder head tapped holes. This could result in insufficient or unequal forces being applied to, and possibly eventual failure of, the air start valves, and hence, the engine itself. In accordance with 'IDI recamiendations, the existing bolts were reworked and reinstalled for all air start valves on Divisions I and II.

l This condition was determined to be reportable under the

! provisions of 10 CFR 21 and 10 CFR 50.55(e) . AECM-82/605, dated December 15, 1982, notified the tmC of this problem.

4.1.5 Flexible Drive Coupling

( Each of the diesel engines is provided with a flexible drive j element to couple the engine and governor. The drive element

! is made of an Isoprene material and is housed inside the governor drive coupling. TDI informed MP&L, via PMI-82/5825 of a potential proble concerning the capability of Isoprene to withstand the hot, oily environment encountered in the-engine gearcase.

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Isoprene is known to deteriorate rapidly in this environment and would eventually fail. Although the coupling is fail safe and would mechanically lock up if the drive element failed, sufficient frequency instability may be induced to trip the D/G off-line. A Neoprene material was recumsded as the replacement material. A corrective action tracking document was generated and the vendor's recumadations for change out of the drive element and female portion of the coupling were impleented.

TDI determined this condition to be reportable under 10 CFR 21 and notified the NBC via a 'IDI letter dated August 18, 1982.

4.1.6 Latching Relay (PRD-82/15)

During preoperational testing of the Division I D/G, an engine start was initiated by a simulated IOCA signal. The engine reached rated speed, but failed to reach rated voltage. The latching relay, which transfers voltage control frm the manual voltage regulator to the autmatic voltage regulator had failed and was inoperative. MP&L determined this condition to be reportable under the provisions of 10 CFR 50.55(e) and 10 CFR 21 and informed the NRC via AEW-82/340, dated August 9, 1982.

The failed relay was replaced with a J14 series ITE Gould control relay which was supplied and qualified with a similar Division III D/G panel. Subsequent precperational testing continued to cmpletion without further incident.

4.1.7 Air Start Pressure Sensing Line (PRD-82/04)

The air receiver tank has a 3/8 inch diameter sensing line attached directly to the sensing tank via a manual valve. The sensing line feeds directly back to the D/G starting air empressor. The starting air receiver tank is seismic Category I. However, the sensing line and air cmpressor are not seismically supported.

During a " Seismic Event", the following condition could occur.

A break anywhere in the sensing line, or pressure sensing device could cause the air receiver pressure to decrease below the minimun allowable (160 psig) in appronmately six (6) minutes. If the pressure is bled off, the air receiver tank would not be capable of performing the design safety function of providing starting air for the D/G. Since the same condition existed in the redundant system the same type of break could occur in the redundant system during a seismic event.

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(NOTE: Credit cannot be taken fo* operator action to close the manual valve located in the sensing line near the air receiver tank.) To preclude this event, the air start sensing line was relocated frcm the loadless start device to just upstream of the air receiver tank inlet check valve. Thus, integrity of the starting air sensing line cannot be violated by a seismic event.

MP&L detennined this condition to be reportable under the provisions of 10 CFR 50.55(e) and 10 CFR 21 and notified the ISC via AECM-82/85, dated March 8, 1982.

4.1.8 GE Type HFA Relays The concern for the HFA relays was initiated by IE Notice No.

82-13, " Failures of General Electric Type HFA Relays." This IE Notice deals with coil spools made of Lexan or nylon material which were furnished in certain HFA relays. A total of 4 HFA relays, GE model number 12HFA53K91 are furnished with the Grand Gulf diesel generator control panels. 'Ito relays are installed in each panel of Division I and II. As reccmnended by IEN 82-13 the correct replacement for these relays would have been the " century" series relays. For the 12HPA53K91, the " century" series replacement nodel is 12HFA153K2H. However, the 12HFA153K2H relay is not available frcm GE prequalified to Class 1E nuclear requirements. An inspection of the original relays did not reveal any defective coil spools. However, the relays were replaced as a ~

precautionary measure. GE nodel number 12HFA151AZF, which is prequalified for Class 1E nuclear service, was used for replacement.

4.1.9 Governor Lube Oil Cooler (PRD-82/01)

The elevation of the governor lube oil cooler on the D/Gs was above the oil level of the governor. This presents the possibility of air being trapped in the governor lube oil system when the oil level in the governor is low. If air is trapped, engine starting may be affected. To preclude this condition, the governor lube oil cooler was relocated to below the governor sump to maintain oil in the governor and prevent air entry.

MP&L determined this condition to be reportable under the provisions of 10 CFR 50.55(e) and 10 CFR 21. The NRC was notified via AE04-82/48, dated January 29, 1982.

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4.1.10 Pneumatic Iogic Problem (PRD-81/53)

The D/G pneumatic logic was such that the diesels may  ;

inadvertently shut down under certain conditions. The D/G pneumatic logic is to be designed such that the engines will automatically shut down on either low lube oil pressure with a 2-out-of-3 logic or high crankcase pressure with a 2-out-of-3 logic. However, due to the two logic lines being tied into a l camon line, it was possible that the engines could be shut down on a 2-out-of-6 logic.

It has been determined that this condition has no adverse affects to the safety of the power plant. For this condition to occur, 2 sensing devices would have to fail (1 low lube oil pressure and I high crankcase pressure). Therefore, this condition is not applicable to the single active failure criteria.

Although the condition could affect reliability, the overall affect on the generator required operability is insignificant and does not create a safety concern. The condition did not violate either design specification requirements or NRC regulations.

Corrective action was not required. However, as a matter of good engineering practice, the design was revised and implenented such that the two logics are no longer tied together in a camon line. The new design yields two 2-out-of-3 logics, thereby reducing the potential for inadvertent faults and enhancing reliability of the D/G. ,

MP&L determined that this condition was not reportable under the provisions of 10 CFR 50.55(e) or 10 CFR 21 and notified the NRC via AECM-82/104, dated March 23, 1982.

4.1.11 Nuclear Service Class lE Qualified Auxiliary Motors (PRD-81/23)

Division I and II are supplied with auxiliary jacket cooling water and auxiliary lube oil subsystems. The pumps used in each of these subsystems utilize a motor driver qualified for Class lE Nuclear Service.

'IDI furnished stock camercial grade AC motors as opposed to the Nuclear Grade Class lE motors required by our Architect / Engineer's contract with DeLaval. DeLaval retracted the original data utilized in establishing that the Grand Gulf motors are " equivalent" to Class lE motors. This

" equivalency" was to be used to qualify the notors supplied for the Grand Gulf Project. Due to the withdrawal of the

" equivalency" claim, the notors could no longer be considered qualified. To assure that qualified motors are used, replacement motors were purchased and installed prior to operation.

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MP&L determined that this condition was reportable under the provisions of 10 CFR 50.55(e) and notified the NRC via AEG-81/156, dated April 29, 1981.

4.2 Division III (HPCS) Diesel Generator The Division III D/G was purchased under MP&L Contract 9645-M-001.0 to General Electric. The diesel engine was manufactured by General Motors-DO and the generator by Electric Products. The Division III D/G assembly was supplied by Morris-Knudsen.

Operability and functional testing were undertaken by GE. This testing included start time tests, HPCS operation fran the normal power source, operation fran the D/G power source, and start and load reliability tests. Results of the prototype testing indicate that the Division III D/G satisfied design requirements und provided a 0.99 factor of reliability. A test report sunmary was provided to the tBC via AECM-82/152, dated April 14, 1982.

This report indicates that the prototype diesel was tested for start and load reliability by conducting 69 successive start and load tests.

Sixty-three of these tests were started with the engine in a warm standby condition. Six were started with the engine at hot equilibrium. There were no failures during these tests, which d monstrated the reliability of the diesel. These tests also demonstrated that the Technical Specification time requirements to reach rated speed, voltage and frequency were met.

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On June 2, 1982, MP&L and associated organizations met with the hE in Bethesda, Maryland to present qualification documents and rationale to denonstrate seismic qualification of the Division III D/G. Based on the results of that meeting, the NBC concluded that the criteria were satisfied and the seismic qualification of equipment in this system is acceptable. NRC acceptance was documented in the Grand Gulf SSER 2, Section 3.10.

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,t 5.0 OPERATIONAL HIS'IORY When the OL was issued, the GGNS Technical Specifications (TSs) became effective and testing of the diesel generator as required by the 'IT:s began.

Since the date of the OL, the TS requirements for the D/G monthly test have been changed. N requirements at the time of the. receipt of the OL were that the D/G should reach a'specified RPM in 10 seconds and a specific voltage and frequency in less than 13 sewuds and then be run at 50% load for longer than one hour. The present TSs are more restrictive. They now require the D/Gs to reach a specified RPM, voltage-and frequency in 10 scumds and be loaded to 100% capacity for longer than 1 hcur. Eighteen nonth functional testing of the D/Gs was recently conpleted satisfactorily.

This testing checked the autcnatic starts of the D/Gs, D/G interlocks, starting air recovery capacity, D/G protective trips and included a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run of which 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> was at 110% load and 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> at 100% load.

Diesel generator start times were obtained frcm empleted surveillance test data sheets or chart recordings and are tabulated in Attachment 4. .The data from the-earlier surveillances indicates some inconsistency in the obtaining and recording of start times, but the times were determined to be within TS limits. The surveillance procedures were later revised as a result of.an extensive review of all surveillance procedures. As can be seen in Attachment 4 the revisions resulted in a marked inprovement in the obtaining and recording of times. Procedure 06-OP-lP75-V-0011, " Diesel Generator Start Iog" was also written and issued to ensure that the data required by Regulatory Guide 1.108 is obtained and doc a:uited properly.

A tabulation of the tests run to date indicates that 233 attempts were made to start the diesels, 103 valid tests have been run, and there have been 3 valid failures; two on the Division III D/G and one on the Division I D/G.

Because of the three valid failure criteria in Regulatory Guide 1.108,

tests are currently being conducted every 7 days. Since the receipt of the operating license the Division I D/G has been run for 558 hours0.00646 days <br />0.155 hours <br />9.22619e-4 weeks <br />2.12319e-4 months <br />, Division II for 108 hours0.00125 days <br />0.03 hours <br />1.785714e-4 weeks <br />4.1094e-5 months <br /> and Division III for 75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br />. Start attspts and total run times are included in Attachment 5.

During the testing performed since the OL was issued, failures of D/G components have occurred. A sunmary of the significant failures and actions taken to correct them is provided below.

5.1 Division II D/G Failed Capscrews (LER 82-080, PRD-82/14)

During the performance of a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> run test on March 15, 1982, the Division II D/G tripped on a " Generator Differential" which was accmpanied by an observed electrical arcing flash inside the generator. In a subsequent inspection of the generator.it was found that the stator insulation had been damaged and that a 15/16 inch bolt head from a 5/8 UNC X 1-3/4 inch long bolt was inbedded in the stator.

'Ihe degraded stator insulation resulted in a phase-to-phase short in the stator that damaged the generator. It was determined that the bolt head was frcn a bolt on the diesel's rear crankcase cover that had sheared off and entered the generator through the air gap on the end of the generator.

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5.1 (Continued)

= 'Ihe generator was replaced with a generator from Unit 2 and all rear crankcase cover bolts on the Unit 1, Division I and II diesels, were replaced with new replacement bolts. An indeperaht lab performed an analysis of the 42 bolts removed frm the Unit 1, Division I and II

• diesel generators (Reference 4).

A review of the analysis prrv1wwl the conclusion that the failure mode was due to a low-stress fatigue front expanding fr m an initial small crack. The initial crack appeared to have been initiated by overtorquing or undertorquing the capscrews. It was also noted that the failed capscrews had a decarburized skin which may have contributed to the failure.

A maintenance work order (IWO) was initiated on October 4,1982 to check the rear crankcase cover capscrews for the correct tightness (60 ft-lbs) . 'Ihree of the capscrews on the Division II diesel i generator were found to be less than 60 ft-lbs (20, 23, and 35

) ft-lbs). The work order instructed that any capscrew not within 2 ft-lbs of the 60 ft-lbs be torqued to within the acceptable range.

When the capscrew that was found at 20 ft-lbs was tightened, it sheared off approximately one inch frm the bottm side of the head before reaching 60 ft-lbs. The capscrews on the Division II D/G were removed and replaced with new replacement capscrews and torqued to 60 ft-lbs. A check of the torque on the Division I D/G capscrews revealed no problems.

The Division II D/G was instrumented by Nutech and data was obtained during an operational test run. 'Ihe test run was performed with the original capscrews installed. New capscrews of a higher strength material (SA-540, B24 SY=150,000) and lock tab washers were installed.

The test data indicated that the highest vibration amplitude occurred i during the startup and shutdown of the diesel ( 450 RPM) with capscrew stresses at 6000 PSI. The vibration amplitude was much less during steady state operation at 450 RPM with the capscrew stresses at 3000 PSI. However, the test results were inconclusive as to the root causes of the vibration source. As further corrective action, l protective screens were installed to prevent entry of foreign objects I

in the generator air gap.

The present information indicates that the capscrews failed by a cmbination of netallurgical and transient vibration factors and that the failures are unique to the Division II D/G. The protective measures taken on both Division I and II, i.e. , increased bolt strength, installation of capscrew lock tab washers, protective screens and increased surveillance, should prevent similar generator I

failures.

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5.2 Ioad Shed & Seouence Panels (BNCR 658-83)

During performance of the 18 month surveillance testing of the diesel generators, it was discovered that the Division I and II Ioad Shed and Sequence System (LSSS) Panels, lH22-P331 and P332, manufactured by VITRO Laboratories, did not always respond as designed to a IOCA signal while the panels were in the Auto Test Mode.

We LSSS Auto Test Mode, which is on-line for normal system operation, inputs high frequency signals and decodes output signals to determine if the panel logic is capable of functioning. The deficiency involves a situation where the high frequency auto test signal does not get blocked upon receipt of the IOCA signal, and the LSSS panel responds to the accident at a speed determined by the high frequency clock.

'Ihus the shed and sequence output relays do not have time to energize and the Division I and II DOCS pumps would not auto start as designed and other loads would not shed or sequence at the right time. This incorrect operation only occurs when the LOCA signal is input to the system coincident and synchronous with the test pulse and does not occur on the receipt of a loss of power signal or when the Auto Test Mode is off.

A design modification (DCP-83/0348) was provided and installed by VITRO as a field change to the Unit 1 LSSS panels. Retests of the panels were satisfactory.

MP&L determined this condition to be reportable under the provisions of 10 CFR 21 and notified the NBC via AEW-83/0609, dated September 21, 1983.

5.3 Auto Voltage Reculator Failure (LER 83-140)

As part of a 18 month IOCA/IOP Division I Diesel Generator test on Septenber 2,1983, a loss of power to the Division I ESF bus was manually initiated. The D/G auto-started and loaded onto the bus, but did not regulate the bus voltage during the load-shedding sequence.

The voltage dipped below 70% at least twice, resulting in three auto-starts of the LPCS pump and two auto-starts of the RER "A" pump.

The D/G was loaded to 3000 kw (43% load) and run for 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. A successful 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> test run had been cacpleted just prior to the IOCA/IOP test.

The initial investigation found a SCR burned out in the auto-voltage regulator circuit. The spare SCR bank in the D/G control panel was used to replace the failed SCR bank. The D/G was loaded to 3500 kw (50% load) for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and 20 minutes. The D/G was manually shutdown when a fuel oil fire started during the troubleshooting.

Page 13

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5.3 (Continued)

Subsequent to the fire, the regulator was removed and subjected to a thorough testing and troubleshooting procedure. A SCR, two integrated circuit chips, a potentiometer, and a rmote gate firing module were found to have failed. The regulator was cleaned and the defective parts were replaced.

The IOCA/IDP test was reperformed successfully on Septaber 21, 1983.

No similar problems with the voltage regulator have occurred to date.

The umpnt which failed first and its failure mechanism is unknown.

i 5.4 Automatic Voltage Regulator Failure (MNCR 670-83)

The non-conformance described in MNCR 670-83 involves the paralleling transformer (T4) in a replacement automatic voltage regulator. When the aut m atic voltage regulator was installed and tested it was discovered that the transformer was apparently wound backwards. This caused a trip of the Division I D/G when an atternpt was made to parallel the D/G to ESF bus 15AA. '1he transformer only affects paralleling operations and would not have prevented operation of the j

diesel as designed during a IOCA or loss of power.

The transformer leads P1 and P2 on the autcmatic voltage regulator were reversed and relabeled. The D/G was then retested satisfactorily.

5.5 High Pressure Fuel Injection Line Failure (LER 83-114)

A potential deficiency identified by TDI involves a possible draw seam on the inside of high pressure fuel injection lines supplied on the Division I and II D/Gs. TWo tubing failures at Shoreham occurred and were attributed to the draw seam which acted as a stress riser and failed when subjected to approximately 1,000,000 operating cycles.

On August 2, 1983, a high pressure fuel injection line on the GGNS, Unit 1 Division I D/G similarly failed. An analysis of the failed tubing attributed the failure to a tubing manufacturing flaw (Reference-3).

A Transamerica DeLaval letter dated July 20, 1983 indicated that the failures occur at approximately 1,000,000 operating cycles and that fuel lines that have in excess of 10,000,000 operating cycles without failure are satisfactory. All the original lines on the Division I and II diesels were considered free of internal flaws of this type.

One line on the Division I diesel and one line on the Division II diesel were not original lines and were considered suspect.

Replacment lines were ordered and installed in place of the two suspect lines.

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' 5.6 Broken Fuel Oil Line and Failure of Deluge Valve (LER 83-126)

On Septenter 4,1983, at 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br />, the Division I D/G was started for maintenance operation. h e engine was manually stopped at 1436 hours0.0166 days <br />0.399 hours <br />0.00237 weeks <br />5.46398e-4 months <br /> and the outside fresh air fans were secured when a fire was insvded at the engine. Approximately 8 personnel were inside the J- rom when the fire occurred. The rom was evacuated and the fire brigade'was-ass a bled. % e fire brigade responded to the scene with

! water hoses and other necessary equipnent. It was noted.that the 1

automatic fire water deluge valve had not opened. % e manual release ,

j was pulled to no avail. A mechanic was able.to open the valve by 4 remwing the actuator enclosure box cover and striking the top of the weight. The fire was repuded to be extinguished at 1501 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.711305e-4 months <br />. An unusual event was declared and reained in effect frm 1447 hours0.0167 days <br />0.402 hours <br />0.00239 weeks <br />5.505835e-4 months <br /> until.1559 hours0.018 days <br />0.433 hours <br />0.00258 weeks <br />5.931995e-4 months <br />.

5.6.1 Iow Pressure Fuel Oil Line Failed ,

W e cause of the fire was ignited fuel oil in the vicinity of l-

the left bank turbocharger. An investigation revealed that the main fuel supply tubing which delivers fuel oil frm the engine driven Fuel Oil Booster Punp to the left and right bank fuel headers had separated at a swagelock fitting at a tee connection. The part is Delaval number CE-010-055. The i failure would have rendered the engine inoperable due to a loss of fuel pressure even if the fire had not occurred. MP&L has received a metallurgical failure analysis report 4 (Reference 1) on the fuel tube which concluded that the crack initiation, propagation and ultimate failure were due to high cycle (fretting) fatigue. This was postulated to be caused

frm excessive turbocharger vibration. MP&L is evaluating and coordinating with DeLaval on the installation of a tubing support which will limit the chances for reoccurrence of this type of failure.

Representatives from Middle South Services and Plant Staff 3 performed a thorough examination of the area affected by the fire to delineate the fire affected areas. The examination revealed the three fire affected areas were:

i

1) Under the left bank turbocharger,

2) The top of the lube oil tank under the left bank turbocharger,

. 3) Under the lube oil cooler, approximately in the middle of the cooler.

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5.6.1 (Continued)

The metal parts of the engine and pressure vessels exposed to the highest heat were visually examined. No areas of discolored metal, indicating excessive heat, were found.

Based on this finding, it was determined that the pressure vessels and engine parts exposed to the highest heat were acceptable for further service. The engine and skid-mounted equipnent located in the fire areas received varying amounts of damage, depending on the amount of exposure to heat, smoke, and water. The wiring, instruments and tubing located on the front of the engine also experienced heat, smoke and water damage, in varying amounts.

Cmponents which were located in the fire area were replaced, since the ability to carry out their design function was in question. Other ccrnponents which may have been subjected to heat or water damage were inspected and either replaced or reworked, depending on the "as found" condition. Any item whose condition could not be accurately evaluated was replaced. The following is a partial list of equiptent replaced due to fire damage: Intercooler, tubrochargers, conduit, wiring, instrument tubing, supports and instruments on the front of the engine, governor, lighting, high pressure fuel lines, fuel injector punps, starting air intake manifold elbow, and numerous miscellaneous small cmponents.

When rework or replacement of the affected items was empleted, the diesel generator was subjected to a maintenance run to verify all cmponents were functioning nomally. This type of engine operation allowed tronitoring of engine operating parameters at different power levels, and uncovered items which warranted further attention. During the maintenance run, the engine was instrumented for vibratory analysis. The preliminary results of the vibratory analysis revealed that the engine exhibited vibrations which were well within the acceptable limits for this type of machinery. No additional vibratian related failures are anticipated.

After the successful ccr:pletion of the maintenance run, the unit was turned over to Operations for operational retesting.

Following the operational retesting, the unit successfully empleted a seven day reliability run. It may be concluded frcm the testing performed, subsequent to the engine rework, that the unit has been returned to a satisfactory operating condition.

I Page 16

5.6.2 Fire Water Deluge Valve Failure The failed fire water deluge valve was a 6 inch Model C, serial number S10774, manufactured by Autamatic Sprinkler Corporation of America. Although a trip signal was received frca the local control panel, the valve failed to open. The valve and the release mechanism were tested and cuents were removed and examined. No significant abnormal conditions were noted. Scne excessive friction was noted between the weight and weight guide rod, however, the valve operated properly.

The examination revealed the following:

1) Buckling was discovered in the weight guide rod, maximum deflection was 0.005 inches.

2)' Evidence of scoring was found on the rod surface in two distinct locations.

3) The weight's upper guide collar had an inside diameter of 0.637 inches rather than the 0.640 inch minimum recmmended by the manufacturer.

4) Scoring was noted on the enclosure box along the path the weight guide bushing traces during actuation.

Corrective actions taken were:

1) The guide rod was trued and sanded.

2)' 'Ihe weight's upper collar guide was reworked to an inside diameter of 0.640 inches + .005 inches.

3) The rod, latch hinge pin, and clapper hinge pins were lubricated.

The enclosure box along the path of the weight guide bushings was also lubricated.

Although no conclusive cause for the failure of the deluge valve to operate was reached, it is believed that the weight dropped fully until it came into contact with the latch arm.

l For further corrective action, the surveillance procedure has been revised to visually verify that the clapper has lifted and locked open following the test under normal system pressure. An increase in testing frequency is under consideration.

5.7 Cracked Connecting Push Rod Weld (MNCR 742-83)

During performance of a MO to check the air start valves on August 11, 1983, the connecting push rod on the #8 left bank cylinder of the Division I D/G was found to have separated into two pieces. Tre push l red is designed as a piece of 1% inch thick wall tubing with a i hardened steel ball bearing welded onto each end. One end of the rod had broken at the tube / weld interface. This failure was discovered when the mechanic pulled the rod in order to reach the air start valve.

l Page 17 t

5.7 (Ccntinued)

A metallurgical evaluation (Reference 2) determined that the basic ,

cause of the failure was poor material selection. However, a review

! .of the failure has shown that the D/G would have run satisfactorily with the rod broken. In fact, the fracture surfaces showed indications that the D/G had been run for sme period of time while the push rod was broken. W is could occur because a spring cm pression load on the push rod keeps it in place even when it is broken.

l MP&L is working with DeLaval to determine the best way to correct the weld failure problem.

5.8 Cracked Jacket Water Welds (MNCR 709-83) and Turbocharger Mounting Bolt Failures (lWCR 713-83)

- These two MNCRs +v'wnted the first problems that occurred, that r indicated that the Division I D/G turbocharger was causing high vibration related problems. Other problems also occurred during this time period; broken stay-rods in the intercooler, cracked base matal on the intercooler, cracked welds on the turbocharger jacket water piping, and cracked metal on an air header flange. These problems were repaired as they occurred. The D/G is equipped with vibration sensors which are designed to trip the diesel if vibration exceeds preselected values. No trips or alarms had been reported however.

While no quantitative data (vibration measurements) were taken during this time period, several engineers and mechanics involved with the work on the D/G have stated that there is a discernable improvement in the vibration levels since the turbocharger was replaced. Vibration measurements were taken at several locations on the diesel and generator after a new turbocharger was installed. These measurements

, show reasonable vibration levels for a D/G of this size. A 7 day run

, of the D/G was also successfully cm pleted following installation of the new turbocharger. A final report is in preparation by TBC on the vibration measurements taken.

To determine the cause of the turbocharger probl e s, it is being returned to the manufacturer for evaluation. m is problem is l

considered closed pending the results of this evaluation.

5.9 overspeed Trip on the Division III Diesel Generator (LER 82-033)

On August 14, 1982, at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, the HPCS system initiated on a low

~

water level signal while troubleshooting was underway on a reactor pressure vessel water level transmitter. The Division III diesel autmatically initiated (as designed) with no cmplications. The diesel was then shutdown at 1310 hours0.0152 days <br />0.364 hours <br />0.00217 weeks <br />4.98455e-4 months <br /> on August 14.

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5.9 (Continued)

On August 14, 1982 at 2030 hours0.0235 days <br />0.564 hours <br />0.00336 weeks <br />7.72415e-4 months <br /> the Division III D/G again started on a lw reactor pressure vessel water level and tripped on overspeed.

Division I, II, and III diesels were placed in the maintenance mode at 2120 hours0.0245 days <br />0.589 hours <br />0.00351 weeks <br />8.0666e-4 months <br /> to prevent inadvertent starts while level transmitters were revented and reference legs filled (during investigation of the incident). A maintenance work order was initiated to investigate the cause of the diesel start and failure.

On August 15, 1982, while troubleshooting, it was noticed that the governor oil appeared to be dirty. The oil was drained and refilled.

On August 16, 1982, the Division III D/G was again started for troubleshooting and tripped again on overspeed. Upon investigation, the governor hydraulic oil system level was found to be low.

Apparently during the fill on the previous day the system was not fully vented. Also on August 16, 1982, it was noticed that the D/G was intermittently giving false indications. The tachmeter relay (P81-SY-K001) in panel 1H22-R118 was found faulty and replaced. The relay is a Dynalco Corporation Part No. RT 2450A. The governor oil system was properly vented on August 17, 1982. On August 18, 1982, at 0245 hours0.00284 days <br />0.0681 hours <br />4.050926e-4 weeks <br />9.32225e-5 months <br />, surveillance test 06-OP-1P81-+1-0002 was conducted and successfully cmpleted.

5.10 Air Start Valve Failures Division I (LER 83-082)

On July 17, 1983, while performing a Division I D/G 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> test run, the starting air valve for the #8 right bank cylinder failed. The valve leaked, allowing exhaust air to enter the air start header, overheating the header. The diesel was secured and the air start valve was replaced. At the time, Division II and Division III diesels were operable.

On July 24, 1983, a similar event occurred, this time on the Division I #1 left bank cylinder starting air valve. The valve began leaking approximately six (6) hours into the test. The load on the diesel generator was reduced to approximately 5.7 megawatts. At this point the load could no longer be reduced due to loss of governor control.

The generator output breaker was tripped which caused the diesel to trip on overspeed.

Although the exact root cause could not be determined, an inspection revealed the following:

1) The atmospheric vent lines on the starting air header were cmpletely blocked by carbon particles. This would cause abnormal pressure to the valves.

2) The starting air distributors were contaminated with carbon particles.

3) The right bank starting air distributor was found to have sme internal assemblies malfunctioning or broken. The left bank starting air distributor was contaminated but still functional.

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5.10 (Continued)

4) The #1 right bank starting air valve was found corroded and frozen such that it would not open. It was discovered that the starting air supply line was blocked, which caused the valve to renain closed. ,

5) The #7 left bank starting air valve had begun to burn.

6) 'Ihe filters which are just upstream from the starting air distributors, were found to have a significant buildup of carbon particles.

7) The #8 right bank starting air valve face and seating surfaces ,

showed signs of pitting.

8) The #1 left bank starting air valve was observed to be slightly open and could not be seated. No signs of pitting were evident other than the actual burned area.

Corrective actions taken were:

1) The left bank vent line was cleaned and the right bank vent line was replaced.

2) Air start valves #1 left bank, #1 right bank, #3 left bank,

1. 6 left bank, #7 left bank and #8 right bank were replaced.

3) The right bank starting air distributor was replaced.

4) All air distributor lines were cleaned and filters replaced.

5) A Preventive Maintenance program has been established to periodically check / replace the starting air distributor filters.

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6.0 RELIABILITY ENHANCDENTS Extensive engineering studies have been performed in an effort to increase the reliability of the D/Gs. A cmprehensive D/G reliability report was prepared by the Operational Analysis Section of Nuclear Plant Engineering which highlighted several problem areas and provided recumerilations to enhance the operability of the D/Gs (References 8 & 9) . These studies included a review of Grand Gulf Systen Operating Instructions and Maintenance Instructions, vendor recm mendations, regulatory requirements, and Grand Gulf operating experience. A sunmary of diesel generator concerns raised by NFC I&E Bulletins, Circulars and Information Notices and INPO reports and the Grand Gulf resolution of these concerns is also provided in Attachment 6. This review resulted in two basic findings:

1) The Grand Gulf D/Gs are being operated and maintained in accordance with current industry practices and as close to the vendor recmmendations as possible.

2) The reliability of the D/Gs can be inproved.

Efforts to inprove the reliability of the D/Gs, in addition to the current operation and maintenance programs, include both temporary and long-tenn augmented activities (References 5 and 6) such as:

1) Increasing surveillance testing run time fran one (1) hour to four (4) hours. 'Ihis increase in fully loaded run time will allow the engine and generator to reach a steady-stat.e temperature condition.

2) A blowdown of the starting air systems on each D/G once per week. This will insure that all support cmponents for the i air-start systsas are functioning properly.

, 3) Improved housekeeping requirements for the D/G rocms and l equipnent. This will lessen the accumulation of particulates

! in the air systen since the air supply for the diesel air l intake and starting air systems is taken fran inside the room.

Also under consideration is the establishment of an inspection team, consisting of a maintenance engineer, an operator, and a mechanic, to perfonn a detailed inspection of the D/Gs at specified intervals. These inspections would spot potential trouble that could lead to future D/G failures, as well as existing damage to the engine or its caponents.

l As part of the overall surveillence procedure review effort, the l surveillance procedures for the D/Gs have been reviewed to ensure that regulatory requirements and camitm2nts have been incorporated. In i addition, reviews of various offsite and onsite documents for applicability to Grand Gulf are performed on a continuing basis.

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< -I 6.0 (Continued) . I Additionally, at the request of the Chairman of the Safety Review Comittee (SRC), the Special 9*mernittee for Review of Plant Operational Readiness has investigated diesel generator reliability. The Special Si*m=nittee l j made the following ret.um.iudations to the SRC Chaiman on methods to inprove long term D/G reliability (Reference 7) . I i

1) Perform 7 day functional testing,on the Division II D/G. This test has been successfully conpleted on the Division I D/G.-

Develop a short- and long-term vibration monitoring program for 2) the Division I and II D/G to identify any existing problems and to inprove detection of couponent or primary equipment degradation before failures occur.

3) Establish a preventive maintenance program based on a conprehensive review of root causes of previous failures at GGNS and throughout the industry. In particular, the problems with i DeLaval D/Gs at the Shoreham Nuclear Station should be reviewed and measures taken as necessary to assure that these problems are not present or are corrected at GGNS. In view of the cracking of crankshafts of the Shoreham diesel engines, a careful review of design differences and fabrication and operational histories of the Shoreham and GGNS engines should be made to determine whether similar flaws might be present in the GGNS engines. (A sumary of this review has been provided in Section 7.0 of this report) .

For long-term assurance of the integrity of the GGNS crankshafts, consideration should be given to performing dye penetrant, ultrasonic, or other nondestructive inspections of the crankshafts at sme time before the start of the second fuel cycle.

i 4) Develop a closer working relationship with DeLaval and consult with th e with respect to modifications to prevent recurrence of equipnent problems experienced at GGNS and throughout the industry. One of the areas that should receive special attention

- is a long term program for upgrading DeLaval supplied, engine-associated piping, tubing, fittings, and welding to a higher level of quality, in view of the safety importance of the D/Gs.

5) To reduce the possibility of personnel error, increased emphasis

on pre-action planning sessions for the persons involved are recomended for planned operational and maintenance activities.

The trend of personnel error should be closely monitored and additional training be provided as indicated by the trend and analysis of events.

Recently there have been several meetings and conversations between DeLaval and MP&L personnel to inprove ccrmunication between the two organizations and resolve design and manufacturing related problems.

4 Page 22

6.0 (Continued)

In the area of training, both DeLaval and H4D personnel have been on-site in the past to conduct training on maintenance P M operation of the D/Gs. The Training Department is presently planning to conduct further classes early next year on operation and maintenance of the D/G and is negotiating with DeLaval and DO as to scheduling of such classes.

The performance of the D/Gs has been closely monitored since receipt of the OL. Two cmprehensive reports have been published by the Operational Analysis Section of Nuclear Plant Engineering (References

• 8 & 9). These reports sunmarize data on D/G failures to start, time-to-start, and significant syst s failure / malfunction events and provide reuwuendations to management staff for improving D/G reliability. Several of these reemnendations have been or are in the process of being inplemented.

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-7.0 INDUSTIE CINPARISCN A ccuparison of Grand Gulf diesel generator related Licensee Event Reports (LERs) to similar LERs generated by industry has been performed. Grand Gulf has generated 39 LERs related to diesel generator problems. These '

were ccupared to 1300 industry LERs generated frcm 1969 thru 1981.

Information for cmparison was extracted from a draft report prepared by MPR Associates for the Nuclear Safety Analysis Center (NSAC) . This

cm parison categorized the LERs by the root cause of failure. These categories were 1) mechanical, 2) electrical, instrumentation and control,

3) people-related, and 4) miscellaneous. failures. .

l Attachment 7 cmpares the percentage of failures in each category at Grand  !

Gulf to the industry percentages. This caparison shows that the failure percentage in each category at Grand Gulf is similar to the industry percentages of failure.

?

A further breakdown of the people-related category has also been performed.

The people-related failures were broken into four subcategories. 'Ihese subcategories were 1) design deficient, 2) manufacturing / fabrication /

installation error, 3) procedure deficient, and 4) failure to follow!

procedures. ' Attachment 8 cmpares the percentage of failures in each i subcategory at Grand Gulf to the industry percentages. Significant

] differences between Grand Gulf and industry were noted in the design F deficient and manufacturing / fabrication / installation subcategories.- An explanation for these' differences cannot be made at this time. It should f be noted that the LERs for Grand Gulf were generated prior to power ascension testing, while most of the industry data was frcm ccrmercially operating plants. However, if the two subcategories are cmbined, the Grand Gulf. percentage (45%) cmpares favorably to the industry percentage (42%).

A significant failure which has been evaluated for its inpact on Grand Gulf I is the Shoreham crankshaft failure. A sunmary of this evaluation was transmitted to the NRC via AE04-83/0653, dated October 14, 1983 (Attachment 9). The evaluation concluded that, pending the results of the analysis underway at Shoreham to determine the root cause of the crankshaft

-failure, there is reasonable assurance, due to design differences, that the Grand Gulf Division I and II D/G crankshafts will not fail in a node similar to Shoreham.

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8.0 Sunmary The GGNS, Unit 1 diesel generators have experienced various problems during their preoperational and operational history. Several of these problems were described in Sections 4.0 and 5.0 of this report. These problems involved failures of capscrews, mounting bolts, welds, air start valves, autmatic voltage regulators, fuel lines and a piston. In addition to these failures, various deficiencies were described. These reported deficiencies detailed potential problems with the link rod assemblies, turbocharger thrust bearing lubrication, air start valve capscrews, air start sensing lines, engine / generator drive couplings, relays, lube oil coolers, auxiliary motors, pneumatic logic and load shed and sequence panels.

Corrective action taken to resolve these failures and deficiencies is also provided in Sections 4.0 and 5.0. These actions demonstrated that MP&L has responsibly and appropriately corrected these problems.

In addition to correcting the above problems and deficiencies, MP&L has performed several studies in an effort to identify diesel generator problems occurring at other units that could affect Grand Gulf, to trend problms occurring at Grand Gulf, and to evaluate various operating and surveillance procedures, vendor rc w w ndations and industry practices.

These studies are part of an effort to enhance plant reliability by evaluating potential problems and instituting corrective action to prevent them at Grand Gulf. Other measures being considered / implemented include increased surveillances on diesel generator components, institution of a vibration monitoring program, develegnent of closer working ties with the diesel manufacturers, and increased enphasis on preplanning of operation and maintenance activities.

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9.0 CONC E SICN The Grand Gulf Division I, II, and III diesel generators have been designed in accordance with applicable regulations and industry standards. The manufacturing process was monitored to assure that the diesels were manufactured as designed. Extensive prototype testing was performed on the DeLaval and DD diesel generators prior to the issuance of the Operating License. Problems and failures encountered with the diesel generators during the preoperational and operational phases of the plant have been identified and their resolution addressed. Surveillance testing and regular maintenance helps to ensure that the diesel generators are operable as needed. Continuous review of Grand Gulf and industry problems with diesel generators assures that potential problems are evaluated and possible trends are noted.

Therefore, adequate neasures have been and will continue to be taken to ensure that the onsite diesel generators provide a reliable backup source of power to equiptent required to operate following a loss or degradation of offsite power.

Page 26

10.0 REFERDCES The following references were used in the preparation of this report.

1) J. S. Brihmadesam, Nuclear Engineering Department, Middle South Services, Inc., New Orleans, IA, " Metallurgical Evaluation of Die'sel Engine Fuel Oil Line Failure frcm Dnergency Diesel Generator -

Division I Grand Gulf Nuclear Station - Unit 1," October, 1983.

2) J. S. Brihmadesam, Nuclear Engineering Department, Middle South Services, Inc., New Orleans, IA, " Metallurgical Evaluation of Diesel Engine Push Rod Weld frcm Grand Gulf Nuclear Station - Unit 1, Dnergency Diesel Generator (Division I)".

3) J. S. Brihmadesam, Nuclear Engineering Department, Middle South Services, Inc., New Orleans, IA, " Metallurgical Evaluation of Diesel Engine Fuel Injection Tube from Grand Gulf Nuclear Station - Unit 1, Dnergency Diesel Generator".

4) Law Engineering Testing Co., IEltD Job Nurrber G-8847, " Engineering Investigation of the Failure of Rear Crankcase Cover Capscrews for the Delaval Standby Diesel Generators, Mississippi Power and Light Carpany" .

5) IPC-83/6295, Msto from C.R. Hutchinson to A.S. McCurdy and F.H. Walsh,

" Diesel Generator Reliability".

6) IPC-83/6562, Meno from F.H. Walsh to C.R. Hutchinson, " Status Report on Diesel Generator Reliability."

7) PMI-83/11532, "Special Subccanittee Report on GGNS Diesel Generator Reliability," Septenber 15, 1983.

8) NPE-OAS Report No.83-017, "GGNS D/G Systens Reliability,"

July 15, 1983.

9) NPE-OAS Report No. 82-017-1, "GGNS D/G Systens Reliability, Supplement No. 1," August 24, 1983.

Page 27

. Attachment 1 9

. D/G DESIGN PARAMETTERS DIESEL DELAVAL DO Model DSRV-16-4 12-645E4 Horsepower 9770 4610 (Total for 2 i ,

diesels)

Bore 17" 9-1/16" Stroke 21" 10" Crankshaft Iength 20'-7" 9'-6" Crankshaft Diameter 13" 7.5" Crankpin Diameter 13" 6.5" No. of Cylinders V-16 V-12 Canpression Ratio 11.6:1 14.5:1 RPM 450 900 Ntmber of Bearings 10 Main 7 (Last 2 in one journal)

GENERA'IOR KVA 8750 4343 KW 7000 3474 NC7FE 1: Source of Information - DeLaval and Do Technical Manuals Page 28

• Attachment 2 Clarification of Requirements to Hydrostatically Test HPCS Diesel Generator Skid-Mounted and Standby Diesel Generator Auxiliary System [ Fuel Oil, Cooling Water, Air Start, Lube Oil} Piping A review of Supplement 4 to the Grand Gulf Nuclear Station Safety Evaluation Report (SSER4), dated May,1983, by MP&L has indicated the need to clarify statements regarding hydrostatic testing of HPCS diesel generator skid-mounted and standby diesel generator auxiliary syst s piping. Section 9.6.3 of SSER4 states, in part, that:

"ASME requires a hydrostatic test to 125% of the design pressure.

The licensee stated the piping and caponents would be hydrostatically tested to the requirements of ANSI B31.1, which requires that piping be leak tested at operating pressure during engine operation. The staff finds this partially acceptable. In addition, the staff requires that all HPCS diesel engine skid and standby diesel engine auxiliary system piping be hydrostatically tested to a minimum of 125% of design pressure..."

ANSI B31.1 (1973) requires that, for hydrostatic tests, the minimum test pressure be 1.5 times the design pressure, provided the test pressure does not exceed the maximum test pressure of any cmponent such as vessels, pumps, or valves in the system. Section 9.6.3 incorrectly states that ANSI B31.1 requires hydrostatic testing at operating pressures. ANSI B31.1 permits substitution of pneumatic tests for hydrostatic tests when piping systems are so designed and/or supported that they cannot be safely filled with water or when the piping systems, which are not readily dried, are to be used in services where traces of the testing medium cannot be tolerated.

Such pneumatic tests are conducted at 1.25 times the desian pressure.

In sumary, piping designated as ASME Section III, Class 3 was either pneumatically tested or hydrostatically tested in accordance with the applicable codes. All Quality Group D piping that is required for the safe operation of the diesel generators has been hydrostatically tested, as previously ccmitted by MP&L, and is in cmpliance with ANSI B31.1 Page 29

. Attachment 3 Clarification of Design Standards for Engine - Mounted Cmponents (Division I and II Diesel Generators)

A review of Supplement 4 to the Grand Gulf Nuclear Station Safety Evaluation Peport (SSER4), dated May,1983, by MP&L has indicated the need to clarify statements regarding the design standards applied to engine-mounted cmponents on the Division I and II diesel generators. Section 9.6.3 of SSER4 states, in part, that:

... engine-mounted auxiliary systems and the fuel oil drip system piping and associated cmponents. ..are designed, manufactured, and inspected in accordance with the guidelines and requirements of American National Standards Institute (ANSI) Standard B31.1...The design of the engine-mounted auxiliary system and fuel oil drip system piping and cmponents to the cited design philosophy and standards is considered equivalent to a systm designed to ASME Section III, Class 3, requirements with regard to system functional operability and inservice reliability."

MP&L agrees with the above stated SSER4 conclusion that the standards used in the design of engine-mounted, manufacturer supplied cmponents, will assure overall system functional operability and inservice reliability ca mensurate with that which is inherent to ASME Section III, Class 3, requirements. Our conclusion is based on an assessment of the engine manufacturer's actual design practices, which were sumarized in our letter of August 9,1982 (AECM-82/459);

however, these design practices do not specifically require the impimentation of ANSI B31.1 in the design and fabrication of engine-mounted cmponents.

The following sumarizes our prior statements regarding standby diesel engine-mounted cm ponents. In our letter of August 26, 1981 (AECM-81/324),

MP&L stated that on-engine hardware was designed to the diesel manufacturer's in-house standards, not necessarily national standards. Our letter of June 10, 1983 (AECM-82/262) clarified our response in AECM-81/324 and indicated that engine-mounted camponents conform to the guidelines of the Diesel Engine Manufacturer's Association (DD1A) standards, the requirements of IEEE 387-1977,

" Standard Criteria for Diesel Generator Units Applied as Standby Power Supplies

for Nuclear Power Generating Station," and the guidelines of Regulatory Guide l 1.9, " Selection, Design, and Qualification of Diesel Generator Units Used as l Onsite Electric Power Systms at Nuclear Plants."

i To further define the criteria which were imposed on the design and fabrication of engine-mounted cm.ponents and to verify the adequacy of these engineering l controls, MP&L and Bechtel performed an infomal audit of the standby diesel generator manufacturer, Transamerica DeLaval, Inc. The results of this audit were provided 'to the NRC in our letter of August 9,1982 (AE01-82/459) and are l reiterated below:

a. On-engine cmponents were designed to manufacturer's standard procedures.

b. AS'IM materials, which are acceptable by ANSI B31.1 guidelines, were used.

Page 30

4

c. Welding was performed in accordance with ASME Section IX.

d. Engine-nounted cmponents were conservatively designed in consideration of service pressure, tenperature, flow, stress levels, etc.

e. The jacket cooling water manifold was hydrostatically tested at 1.5 times the design pressure, and remaining cmponents, as appropriate, were tested at operating temperatures and pressures.

f. A OA program was imposed in accordance with Appendix B of 10 CFR 50.

g. The diesel generator, including engine-mounted cmponents, was designed for and excited / analyzed at frequencies greater then 35 Hz.

In sumary, based on the above audit results, MP&L has concluded that the design and fabrication of engine-mounted cmponents provide reasonable assurance that these cmponents will reliably perform their design safety function. MP&L will revise FSAR Table 3.2-1 to document the design criteria applicable to engine-mounted cmponents.

i 1

Page 31

. Attactnent 4 1 ,

DIESEL GENERA'IOR STARP TIMES SDG 11 (DeLaval - Division I)

Spec: Achieve 441 RPM in 10 seconds Achieve 4160 416 Volts and 60 i 1.2 Hz in 13 seconds Start Date Time to RPM / RPM Time to Ready to load Time to Volts /Hz 7-19-82 10 sec/460 Not Required 6 sec 8-8-82 10 sec/455 Not Required 10 sec 9-16-82 10 sec/450 Not Required 9.07 see 10-2-82 10 sec/452 tbt Required 9.0 sec 11-18-82 6.5 sec/452 12 sec Not Required 1-9-83 5.4 sec/441 4.5 sec Not Required 2-15-83 7.0 sec/460 5.7 sec Not Required 3-9-83 7.1 sec/460 6.0 sec Not Required 5-7-83 5.36 sec/450 6.26 sec Not Required 6-7-83 6.1 sec/461 6.0 sec Not Required Amendment 7 to Technical Specifications Spec: Achieve 441 RPM in 10 seconds Achieve 4160 416 Volts and 60 1.2 Hz in 10 seconds 7-8-83 7.0 sec/450 6.0 sec Not Required 9-16-83 9.07 sec/441 Not Required 9.07 9-22-83 5.56 sec/441 Not Required 5.3/5.8 9-23-83 5.4 sec/441 Not Required 4.6/5.5 10-4-83 5.95 sec/441 Not Required 5.0/8.0 Page 32

SDG 12 (DeLaval - Division II)

Spec: Achieve 441 RPM in 10 seconds Achieve 4160 416 volts and 60 1.2 Hz in 13 seconds Start Date Time to RPM / RPM Time to Ready to Ioad Time to Volts /Hz 6-22-82 10 sec/451 Not Required 6.0 sec 7-23-82 10 sec/460 Not Required 3.9 sec 8-24-82 10 sec/450 Not Required 6.0 sec 8-28-82 6.5 sec/448 3.0 sec Not Required 10-10-82 6.0 sec/450 6.0 sec Not Required 12-4-82 6.7 sec/450 5.5 sec Not Required 12-28-82 8.0 sec/* 5.7 sec Not Required 1-30-82 5.7 sec/450 5.8 sec Not Required 3-27-83 5.4 sec/450 3.3 sec Not Paquired 5-4-83 7.1 sec/450** 7.4 sec Not Required 5-31-83 7.6 sec/445 7.8 sec Not Required Amendment 7 to Technical Specifications Spec: Achieve 441 RPM in 10 seconds Achieve 41d0 416 Volts and 60 1.2 Hz in 10 seconds 7-3-83 7.23 sec/441 7.28 sec Not Required 8-5-83 6.0 sec/441 Not Required 5.5/5.5 8-11-83 6.0 sec/441 Not Required 5.8/6/7 8-18-83 6.6 sec/441 Not Required 5.8.5.6 8-25-83 6.8 sec/441 Not Required 5.6/6.1 9-9-83 6.8 sec/441 Not Required 5.5/5.75 9-23-83 5.9 sec/441 Not Required 5.4/8.6 10-3-83 6.2 sec/441 Not Required 5.5/8.7

• RPM was not logged, however time to reach required RPM was derived frcm strip chart and logged on data sheet at the time of the test.

• • 'Ihis data was obtained frcm chart recording of the test.

Page 33

1 .

SDG 13 (D0 - Division III)

Spec: Achieve 882 RPM in 10 seconds Achieve 4160 416 Volts and 60 i 1.2 Hz in 13 seconds Start Date Time to RPM / RPM Time to Volts /Hz 6-10-82 9.0 sec/890 9.0 sec 8-18-82 10 sec/882 9.6 sec 9-16-82 13.5 sec/900* 10 see 10-19-82 8.4 sec/900 10 sec Volts, 8.6 sec Hz 12-24-82 9.0 sec/882 12.5 see 12-23-82 10.0 sec/890** 12.5 sec 2-27-83 7.6 sec/882 9.7 sec 1

3-27-83 7.8 sec/882 7.8 sec 3-21-83 8.0 sec/882 10.4 sec***

6-18-83 7.6 sec/882 9.7 sec 6-20-83 8.2 sec/882 8.1/8.2 Amendment 7 to Technical Specifications Spec: Achieve 882 RPM in 10 seconds Achieve 4160 t 416 Volts and 60 i 1.2 Hz in 10 seconds 7-18-83 8.0 sec/882 9.0/8.5 i

8.7/7.0 7-27-83 9.5 sec/882 7-30-83 7.7 sec/882 8.2/7.7 l

8-2-83 7.8 sec/882 8.2/7.8 8-11-83 9.0 sec/882 9.0/9.0 8-26-83 7.3 sec/882 7.6/7.3 l 9-9-83 7.5 sec/882 8.0/7.5 l

I Page 34

SDG'13 (EMD - Division III) (Continued)

Spec: Achieve 882 RPM in 10 seconds Achieve 4160 416 Volts and 60 1.2 Hz in 10 seconds Start Date Time to RPM / RPM Time to Volts /Hz 9-23-83 8.5 sec/882 8.5/8.2 10-4-83 8.0 sec/882' 8.0/7.6 10-10-83 8.0 sec/882 8.1/7.8

• Time of 13.5 seconds to reach RPM was due to a sticky tachemeter.

Time of 10 seconds to reach required frequency verifies that requirment for RPM was met.

• • RPM of 890 was obtained at 10 seconds thus verifying that required RPM was obtained in 10 seconds.

• • • The recorded time of-10.4 seconds meets the previous TS limit of 13 seconds. However, it would not have met the present TS limit of 10 seconds (Amendment 7 to TS) .

{

Page 35

• Attachment 5 GGNS D/G OPERATING DATA III (As of 10/11/83)

Division I Division II Division III Shop and Pre-Oper. Run Time (Hrs) 535 252 298 Since Date of OL Run Time (Hrs) 558 108 75

'Ibtal Run Time (Hrs) 1093 360 373 Total No. of Starts DeLaval/D4D Shop Runs 310(2) 5 30 Pre-Operational Runs 60 60 80 Since Date of OL Runs 112 60 61 Total Starts 482 125 171 i

N MES: 1. Source of Inforraation - DeLaval and END Technical Manuals ,

l

2. Division I engine had 300 prototype runs for reliability testing.

l 3. Per R. G.1.108 (As of 10/17/83):

No. of valid tests: 103 No. of valid failures: 3 l

l' l

l Page 36 l

[

Attachment 6 Inplementation of NRC I&E Bulletins, Circulars and Information Notices and INPO Reports Related to Diesel Generator Problems IEB 74-16, "Inproper Machining of Pistons in Colt Industries (Fairbanks - Morse)

Diesel Generators" Action Determined not applicable, however TDI wa's requested to take precaations to prevent similar problems.

IEB 79-23, " Potential Failure of Dnergency Diesel Generator Field Exciter Transformers" Concern Design error in wiring a transformer primary neutral on DD D/G.

Corrective action was to allow transformer primary neutral to float.

Action Investigation revealed that the HPCS D/G was designed and supplied with a floating primary neutral, therefore, this problem is not considered applicable to Grand Gulf.

IEB 83-03, " Check Valve Failures in Raw Water Cooling Systems of Diesel Generators" Concern Numerous check valve failures in D/G raw water cooling systems.

Action GGNS D/G cooling water systems were reviewed. IEB 83-03 was determined to be applicable to three SSW check valves. These valves l were included in the ISI program for inspection at the first

! refueling outage and every five years thereafter. A report is to be l made to NBC after the first inspection.

l

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l Page 37

IEC 77-15, " Degradation of Fuel Oil Fiw to the Emergency Diesel Generators" Concern Fuel oil flow from the storage tank to the day tank could be less than the flow needed to support full load fuel consumption by the D/G.

Action Procedure 09-S-09-5 provides for chemical addition (Biocide) to the fuel oil storage tanks. The Technical Specifications require sanpling every three months, water drained frcm the day tanks every 31 days or when the D/G is run greater than 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, and that the storage tanks be cleaned every 10 years.

IEC 77-16, " Emergency Diesel Generator Electrical Trip Iockout Features" Concern A field voltage trip interlock with the D/G output breaker was not bypassed during an emergency start of the D/G due to a design error.

Action A review of preoperational and 18 month surveillance tests determined that all trip functions designed to be bypassed during emergency starts are in fact bypassed.

IEC 79-12, " Potential Diesel Generator Turbocharger Problem" Concern On fast repeat starts of END diesels, the engine may reach actual operating speed before required oil pressure is established at the turbocharger thrust bearing. This may cause sane smearing of the bearing metal so that the cumulative damage frm several similar starts would result in a turbocharger failure.

Action IEC 79-12 was determined to be applicable to the Division III D/G.

The recatriendations of the vendor and IEC 79-12 were incorporated into the Division III D/G cperating procedures. In addition, the existing turbocharger will be replaced by a heavy duty turbocharger prior to startup after the first refueling outage.

Page 38

IEC 80-05, " Emergency Diesel Generator Inbricating Oil Addition and Onsite Supply" Concern -

IEC 80-05 concerns an incident in which lube oil was pumped into the D/G air box through a mismarked drain connection. An additional concern was the minimum anount of lube oil to be kept on site.

Action Lube oil addition points were identified for all three D/Gs. Oil consumption of the D/Gs was calculated and a 7 day supply is onsite for the HPCS D/G. The Division I and II D/Gs have sufficient reserve capacity for 7 days.

IEC 80-11, " Emergency Diesel Generator Lube Oil Cooler Failure" Concern Lube oil cooler failures caused by severe corrosion of solder that sealed tubes to tube sheets. These failures were attributed to incmpatible corrosion inhibitor in the coolant.

Action IEC 80-11 was evaluated and determined to be applicable to the Division III D1D D/G. The soldered tube ends in the lube oil coolers were inspected and found acceptable. The sampling procedure was revised to provide for monthly sanpling of the D/G coolant and corrosion inhibitors were added per the manufacturer's reemnendations.

IEC 80-23, " Potential Defects in Beloit Power Systems Dnergency Generators" Concern Ioss of field due to frayed insulation en leads between collector i

rings and field coils.

l l Action i

j IEC 80-23 was evaluated and determined to be not applicable to GGNS.

l The deficiency was only applicable to generators built by Beloit l Power Systers. GGNS uses Protec Inc. generators.

l l

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Page 39

IEN 83-17, "anergency D/G Control Icgic" Concern D/G did not respond to Auto Start Signal upon testing its shutdown relay.

Action Evaluation in progress.

IEN 83-51, " Diesel Generator Events" Concern Cracked cylinder heads have been observed at the Shoreham Nuclear Station, as well as other facilities which use diesel generators manufactured by Transamerica DeLaval, Inc.

Action This problem has not been observed at Grand Gulf. A chemical analysis sanpling program is in effect for the jacket water (weekly) and lube oil system which would indicate cracks if they should occur.

IEN 83-58, "Transamerica DeLaval Diesel Generator Crankshaft Failure" Concern Crankshaft failures in DSR-48 D/G at Shoreham.

Action An evaluation is in progress, however, it has been preliminarily

. determined to be unique to Shoreham due to crankpin size and l differences in crankshaft design.

l l SOER 80-1, "Ioss of Redundant Emergency Diesel Generator Starting Air System" j Concern Using an approved surveillance procedure, a failure of one starting air system could go undetected until both systems failed to start j

the diesel.

Action Review of SOER 80-1 determined that the HPCS air start system was similar to that described. The nonthly surveillance for the HPCS l

D/G was revised to test the air start systens independently and

simultaneously on an alternating basis as per the recm mendations in l SOER 80-1.

I Page 40

SOER 83-6, " Unavailability of Emergency Pcuer Caused by Diesel and Breaker Control Circuitry Design" Concern Design oversight in diesel generator starting circuitry and in breaker control circuitry preventing D/G restart and restoration of de-energized bus.

Action SOER 83-6 and the control circuitry for the D/G start circuit and breaker control circuits were reviewed. It was determined that the concerns described in SOER 83-6 do not exist at GGNS.

SER 13-80, " Diesel Generator Failure to Accept Full Icad" Concern A D/G failed to accept full load during a test due to undersized exciter leads to the exciter field.

Action Inspection and calculations by MP&L deternuned that exciter leads on the three Unit 1 D/Gs are adequately sized for full load.

SER 45-80, " Potential Diesel Generator Overload Conditions" Concern .

Non-safeguard loads on ESF busses not included in degraded bus and/or accident load calculations may create overload conditions.

Action '

l l Review of GGNS D/G systems determined that the concerns described in l SER 45-80 are precluded by the GGNS D/G system design.

I SER 2-81, "RHR/ Diesel Generator Cooling Pump Pocm Flooding" Concern Leakage exceeded the capacity of the D/G cooling water pump rocxn sunp thus ficoding the rocm.

Action A review of the D/G cooling system design determined that the concern of SER 2-81 was not applicable to GGNS.

1 Page 41 l

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- SER 16-81, " Failure of D/G Speed Control Coupling" Concern Defective coupling in DD D/G due to exposure of elastaner spider to an oil vapor environment.

Action Review of DO D/G design at GGNS determined that SER 16-81 was not applicable to the HPCS D/G.

SER 36-81, "D/G Fire Hazard" Concern D/G oil fire due to oil carryover into the D/G exhaust caused by running the D/G at no-load canditions.

Action A review of D/G procedures has determined that adequate precautions and instructions to preclude the concern described in SER 35-81 are in place. These procedures require loading of the diesels within a specified time period.

SER 55-81, " Fire in Diesel Generator Rocm" Concern A fire occurred in the D/G roan when a lube oil pressure indicator ,

failed and the lube oil ignited on contact with the turbocharger.

The fire suppression system was out of service, however, the required fire watch and equignent was available and the fire was extinguished in eight minutes.

Action Included SER 55-81 as required reading for operations and maintenance personnel to alert personnel to potential failure Inodes of peripheral equipnent.

SER 67-82, "D/G Bearing Failure due to Inadequate Prelubrication" Concern Bearing failure on a Fairbanks-Morse D/G due to inadequate prelubrication.

Action

~

Review of the D/G systems determined that continuous prelube is used on Division I and II D/Gs. Specifications and instructions are in place for the Division III D/G to ensure adequate prelube for manual starts only. Prelubing is required once a week when the Division III D/G has not been run.

Page 42

SER 70-82, " Diesel Generator Fire frm Iraking Lube Oil" Concern Fire caused by lube oil spraying frm the lube oil filter 0-Ring on to the exhaust manifold.

Action SER 70-82 was routed to operations, maintenance and training for information to alert personnel to potential failure nodes of peripheral equiptent.

SER 78-82, "Ioss of All D/Gs" Concern One D/G was out of service when the other D/G started on a loss of power and subsequently tripped on loss of excitation. 'Ihe D/G trip occurred due to an design error in a previous modification.

Action SER 78-82 was routed to the appropriate design and maintenance organization for information to alert personnel to potential failure modes of peripheral equipment.

SER 21-83, " Inoperable D/G due to Inadvertent Fire Actuation Signal" Concern ,

A fuel oil transfer pump tripped on an inadvertent fire signal causing a clean fuel oil tank to overflow. The fuel oil was secured to the diesel to stop the overflow thus rendering the D/G inoperable.

Action Review of the GGNS D/G systems determined that SER 21-83 was not applicable to GGJS.

SER 25-83, "D/G Restart 11alfunction" Concern Design review of a D/G control circuit disclosed that under certain conditions a restart of the D/G would fail.

Action Evaluation in progress.

Page 43

9 SER 48-83, " Emergency D/G Roan Ventilation" Concern D/G heat load was greater than that originally specified by vendor and caused the ventilation system capacity to be exceeded.

Action Evaluation in progress.

A review of the doctments listed below has detemined that the concerns were either not cpplicable to GGNS or were addressed in one or more of the above documents.

IEN 79-23 SER 55-80 IIN 82-08 SER 57-80 SOER 80-4 SER 8-81 SOER 83-1 SER 80-81 SER 1-80 SER 102-81 SER 71-80 t

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E2is2aE= GRAND GULF

- m = REPORT ON D/G ~

NOTE: Values in parentheses are in percent of total 100-k 90-U 80 -

g 70 -

h 60 -

i b 50-3 (3

m 11 0 -

30 - (28)

( 6L i

20 (20.5) (21$

10 - (9) 2 o _ .. _ ._ _ _ I_(M .6) _

MECllANICAL ELECTRICAL PEOPLE RELATED MISCELLANE0US DIESEL GEllERATOR LERs SORTED IllTO ROOT CAUSE CATAGORIES .

g U

- W J = GRAND GULF S 8

' a = REPORT ON D/G ,

NOTE: Values in parentheses are in percent of total y 100 -

g 90 -

80 -

$ 70 -

E

$ 60 -

M 50 -

40 - (35) (q0)

(34)

I 30 - (25) b 3 20 - l, (13) !l g Q,0) (g) l,i p 10 -

U El o

i. b O --- L. ._. _ _

DESIGN f1ANU/ FAB / PROCEDURE FAILURE TO

.DEFICIEtlT INSTAL. LOOSE DEFI.CIENT FOLLO!/ PROCEDURE DIESEL GENERATOR LERs IN THE PEOPLE RELATED CATAGORY l

f

P . .

MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi P. O. B O X 184 0. J A C K S O N, MIS SIS SIP PI 3 9 2 05 Attachment 9 October 19, 1983 NUCLE AR PRODUCTION DEPARTMENT U. S. Nuclear Regulatory Commission ~

Office of Nuclear Reactor Regulation Washington, D. C. 20555 Attention: Mr. Harold R. Denton, Director

SUBJECT:

Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416 and 50-417 License No. NPF-13 .

File: 0260/L-860.0 Applicability of Shoreham Diesel /

Generator Crankshaft Failure to GGNS AECM-83/0653 IE Information Notice No. 83-58, "Transamerica Delaval Diesel Generator Crankshaft Failure," dated August 30, 1983, addressed the recent failure of a diesel engine crankshaft at Shoreham Nuclear Station. The attached report is provided by Mississippi Power & Light (MP&L), as informally requested by the NRC, to compare the Shoreham and Grand Gulf Nuclear Station (GGNS) designs, to discuss the applicability of that failure to GGNS, and to substantiate MP&L's conclusion that continued operation of the GGNS standby diesel generators is justified.

While the attached report identifies certain similarities between the Shoreham and GGNS crankshaft design and manufacture, there exists significant differences in some critical paraceters. The GGNS design exhibits lower crankshaft torsional stresses, greater overlap between the crankpin and crankshaft cross-sections, a circular crankarm, and a counterweighted crankshaft. Overall, MP&L considers that these differences contribute to a smoother running engine with a more favorable level and distribution of crankshaft component stresses, in comparison to the Shoreham design.

The attached report and conclusions presented here are based on MP&L's evaluation of the GGNS diesel engine design, information provided by Transamerica Delaval, Inc., and discussions with Long Island Lighting Company.

Overall, MP&L concludes that there exists reasonable assurance that a failure will not occur at GGNS similar to that which occurred at Shoreham Nuclear Station. MP&L will continue to closely monitor the evaluations of the Shoreham crankshaft failure and will apply that information to the justification presented here for continued operation of the GGNS diesel generators and to Page 47 Member Middle South Utilities System

as%c-WJV&*e9)

MISSIO2IPPI POWER Q Ll2HT COMPANY #E' Attechment 9 (Cont'd)

. , - the development of an inspection program, as appropriate. MP&L will keep the NRC advised of any development that alters the position presented here.

Yours truly, L. . Dale ~

nager of Nuclear Services JHS/JGC:rg Attachments cc: Mr. J. B. Richard (w/a)

Mr. R. B. McGehee (w/o)

Mr. T. B. Conner (w/o)

Mr. G. B. Taylor (w/o)

Mr. Richard C. DeYoung, Director (w/a)

Office of Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Mr. J. P. O'Reilly, Regional Administrator (w/a)

U.S. Nuclear Regulatory Commission Region II a a Georgia bb3 Page 48

p -

. Attachment to

, AECM-83/0653 Attachment 9 (Cont'd) Paga 1 of 5

., APPLICABILITY OF SHOREHAM DELAVAL DIESEL / GENERATOR CRANKSHAFT FAILURE TO GGNS ,

IE Information Notice No. 83-58, "Transamerica Delaval Diesel Generator Crankshaf t Failure" concerns the failure of a Transamerica Delaval Inc. DSR-48 diesel / generator (D/G) installed at the Shoreham Nuclear Station. The diesel failed dur'ing post modification testing when its crankshaft assembly fractured at the crankpin and crankarm on the generator side of the cylinder No. 7 crankthrow. The fracture occurred in a transverse plane across the crankarm as reported by Transamerica Delaval, Inc. (see attached figure). Subsequent to the failure, the crankshafts of the two other Shoreham diesel generators were examined. Cracks were also discovered in the crankshafts of these two diesels in the same general location.

The DSR-48 diesel utilized at Shoreham is an eight cylinder in-line engine with a bore of 17 inches and stroke of 21 inches. The engine is rated at 4889 horsepower and 3500 kw at 450 rpm. The crankshaft is an eight throw crank-shaft approximately 20' long with a crankpin diameter of 11 inches and a main journal diameter of 13 inches. Present information indicates that the crank-

shaft was not counterweighted.

! The DSRV-16-4 diesel utilized at Grand Gulf Nuclear Station is a 16 cylinder V-type engine with a bore of 17 inches and a stroke of 21 inches. The engine

( is rated at 9770 horsepower and 7000 kw at 450 rpm. The crankshaft is an i eight throw crankshaft approximately 20'7" long with a crankpin diameter of 13 l inches and main journal diameter of 13 inches. Four (4) counterweights are used on crankthrows 3, 4, 5 and 6.

DESIGN DIFFERENCES Review of the present information for the DSR-48 diesel at Shoreham and,the DSRV-16-4 diesel at GGNS indicates that several similarities and several major differences exist between the two types of diesel engines. These differences are as follows:

1. The DSR-48 is an eight cylinder in-line engine and the DSRV-16-4 is a sixteen cylinder V-engine. Each crankthrow on an eight cylinder engine has force from the power stroke applied to it every two revolutions of the crankshaft while a crankthrow on a sixteen cylinder has force from the power stroke applied every revolution of the crankshaft. This results in a more evenly applied force to the i

crankshaft and a potentially smoother running engine.

2. Crankshaft torsional stresses at synchronous speed (450 rpm) are 2500 PSI for the Shoreham DSR-48 and 1800 PSI for the GGNS DSRV-16-4 The torsional stresses are therefore approximately 28% less for the GGNS diesel engine crankshaft at operating speed as reported by Delaval, Inc.

3. The GGNS DSRV-16-4 has a 13 inch crankpin diameter versus a 11 inch

diameter crankpin on the Shoreham DSR-48 crankshaft. In the Grand Gulf design the larger crankpin diameter provides a greater overlap between the crankpin and shaft cross-sections at the crankarm.

1 Page 49 l P25rgl

.' , Attachment to AECM-83/0653 Attachment 9 (Cont'd) Peg 2 2 of 5 The shape of the GGNS crankarm is also circular, rather than elliptical, giving added crankarm cross-sectional area at the most probable fracture plane (see attached figure.)

4. The GGNS DSRV-16-4 utilizes four (4) counterweights on crankthrows 3, 4, 5 and 6 while the Shoreham DSR-48 uses none. Though specific vibrational data is not available for the Shoreham engine, this should result in less vibration in the DSRV-16-4 and a smoother running engine.

Due to the differences listed above, the manner of distribution and trans-mission of stresses on the DSRV-16-4 crankshaft is substantially different from the DSR-48. In addition, in a letter from Delaval to GGNS, Delaval has indicated that the Shoreham engine crankshafts were unique to those engines in that they were the only crankshafts having 11 inch diameter crankpins and 138 inch diameter journal supplied in DSR-48 in-line engines rated at 225 lb/in j BMEP (Brake Mean Effective Pressure).

DESIGN SIMILARITIES As indicated in the earlier discussion, the GGNS and Shoreham diesel engine crankshafts are similar in several parameters, including the following:

1. Bore and stroke

2. Number of crankthrows

3. Main journal diameter In addition, present information indicates the crankshaft material and manufacturing process are the same for the DSR-48 and:DSRV-16-4 diesels.

However, there is no substantive evidence available to MP&L at the present time that deficiencies in the materials or fabrication process existed in the Shoreham crankshaft.

l The following manufacturing data was obtained via telecon with Transamerica l Delaval Inc.:

DIESEL MANUFACTURING CO. MANUFACT'JRING DATE GGNS Crank #1 Elwood City 6/26/75 (D/G 11) Forge, Penn.

Crank #2 National Forge 6/28/76 (D/G 12) Penn.

Crank #3 National Forge 7/1/77

! (D/G 21) Penn.

Crank #4 Elwood City 6/27/77 (D/G 22) Forge, Penn.

i I

Page 50 P25rg2

' ~

• Attechnent to

• AECM-83/0653 Attachment 9 (Cont'd)

Shoreham Crank #1 Mitsubishi 6/29/72 i (Cracked) Japan

Crank #2 - Elwood City 2/27/?5 (Fractured) Forge, Penn. _

Crank #3 Elwood City 6/10/70 (Cracked) Forge, Penn.

INSPECTION DATA Although the.c.rankshafts in both Division I and II GGNS Diesel Generators have not specifically been examined for the problem described in IEN 83-58, they have been visually examined on two separate occasions while performing required modifications and preventive maintenance. (It should be noted that examinations of the crankshaft discussed here were not formal code visual

. examinations). The first maintenance effort took place during the piston modification in November, 1981. At this time the engine run hours stood at approximately 331 hours0.00383 days <br />0.0919 hours <br />5.472884e-4 weeks <br />1.259455e-4 months <br /> for Division I and 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br /> for Division II. During this modification which required the removal of the connecting rods, the crankshaft was lightly polished prior to reassembly of the engine. No cracks or other obvious deficiencies were noted by either craft or supervisory personnel.

The second maintenance offort took place in January and March of 1983 during

. the Crankshaft Deflection and Thrust Clearance Checks being performed as part of an 18-month Preventive Maintenance program. The run time during this P.M.

stood at approximately 600 hours0.00694 days <br />0.167 hours <br />9.920635e-4 weeks <br />2.283e-4 months <br /> for Division I and approximately 280 hours0.00324 days <br />0.0778 hours <br />4.62963e-4 weeks <br />1.0654e-4 months <br /> for Division II. During these checks the pistons and connecting rods remained in place; however, no obvious deficiencies were noted in the crankshaft by craft or supervisory personnel.

VIBRATION MEASUREMENTS l

As of 10/6/83, the Division I D/G has approximately 1090 hours0.0126 days <br />0.303 hours <br />0.0018 weeks <br />4.14745e-4 months <br /> run time and the Division II 360 hours0.00417 days <br />0.1 hours <br />5.952381e-4 weeks <br />1.3698e-4 months <br />. The Division I and II D/G's recently underwent operating tests in which vibration measurements were made. One of the tests for the Division I D/G included a seven day test run at approximately 60%

load. The engine performed satisfactorily during the test. A preliminary conclusion of the vibration measurements is that both GGNS D/G's exhibit vibrations which are typical of large internal combustion engines.

CONCLUSIONS The failure analysis at Shoreham is incomplete at the time, so the root cause of the failures is not known; however, it is considered to be a problem unique to that facility for reasons discussed above. The Shoreham and Grand Gulf l diesel engine crankshaft designs differ in several critical parameters, including the utilizatior. of couaterweights and larger crankpins in the GGNS design. In addition, crankshaft torsional stresses are lower in the Grand l

Gulf design. Therefore, there is reasonable assurance that the GGNS l Division I and II Emergency Diesel Generator crankshafts will not fail in a mode similar to that experienced by Shoreham and that the engines will Page 51 P25rg3

. 0- -

Attcchment to

. AECM-83/0653 I

.ttachment 9 (Cont'd)

,,, continue to operate as designed. The need and schedule for inspection of the GGNS D/G crankshaf ts will be evaluated when the results nf the analysis of the Shoreham crankshaft failure is available.

i Page 52 P25rg4

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