Text

Safety Evaluation Report Related to the Operability and Reliability of Emergency Diesel Generators Manufactured by Transamerica Delaval,Inc
	ML20209E343
Person / Time
Issue date:	08/31/1986
From:	Berlinger C, Murphy E; Office of Nuclear Reactor Regulation
To:	;
References
	NUREG-1216, TAC-61970, NUDOCS 8609100233
	Download: ML20209E343 (44)
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.i, NUREG-1216 l

Safety Evaluation Report Related to the Operability and Reliability of Emergency Diesel Generators Manufactured By Transamerica Delaval, Inc.

U.S. Nuclear Regulatory Commission l

C. Berlinger, E. Murphy i

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NUREG-1216 Safety Evaluation Reaort Related to the Opera aility and Reliability of Emergency Diesel Generators Manufactured By Transamerica Delaval, Inc.

i ate u sh d ugust 1 C. Berlinger, E. Murphy Office of Nuclear Reactor Regulation

.S Nuclear g ry Commission pf"%

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ABSTRACT Concerns regarding the reliability of large-bore, medium-speed diesel genera-tors manufactured by Transamerica Delaval, Inc. (TDI) for application at domes-tic nuclear plants were first prompted by a crankshaft failure at Shoreham Nuclear Power Station in August 1983. However, a broad pattern of deficiencies

! in critical engine components subsequently became evident at Shoreham and at l other nuclear and non-nuclear facilities employing TDI diesel generators. These daficiencies stemmed from inadequacies in design, manufacture, and quality assurance / quality control by TDI.

In response to these problems, 11 (now 13) U.S. nuclear utility owners formed a TDI Diesel Generator Owners Group to address operational and regulatory issues relative to diesel generator sets used for standby emergency power. The Owners Group performed extensive design reviews of all key engine components and devel-op:d recommendations to be implemented by the individual owners concerning needed component replacements and modifications, component inspections to validate the "as-manufactured" and "as-assembled" quality of key engine components, engine testing, and an enhanced engine maintenance and surveillance program.

The staff evaluation of the Owners Group program is documented in this report.

The staff concludes that implementation of the Owners Group recommendations plus additional actions as identified herein will establish the adequacy of the TDI diesel generators for nuclear standby service as required by General Design Criterion 17 of Appendix A to 10 CFR 50. The staff further concludes that these actions will ensure that the design and manufacturing quality of the TDI engines is within the range normally assumed for diesel engines designed and manufactured in accordance with 10 CFR 50, Appendix B. Continued reliability and operability of the TDI engines for the life of the facilities will be ensured by implemen-tation of the maintenance / surveillance program described herein.

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i CONTENTS Page ABSTRACT ........................................................... iii l 1 INTRODUCTION AND BACKGROUND ..................................... 1-1 l 2 EVALUATION ...................................................... 2-1 2.1 Technical Resolutions of Phase I ........................... 2-1 2.1.1 General ............................................. 2-1 2.1.2 Components That Warrant Special Emphasis ............ 2-3 2.1.3 Clarifications, Exceptions, and Licensing Considerations Pertaining to PNL Recommendations i n P N L- 5 6 0 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2.1.3.1 Engine Overhall Frequency .................. 2-4 2.1.3.2 Air Start Capscrews ........................ 2-4 2.1.3.3 Auxiliary Module Wiring and Terminations ... 2-5 2.1.3.4 Connecting Rod Bearing Shells .............. 2-5 2.1.3.5 DSR-48 Connecting Rods ..................... 2-6 2.1.3.6 DSRV Connecting Rods ....................... 2-6 2.1.3.7 Crankshafts .All TDI Models ............... 2-10 2.1.3.8 DSR-48 Crankshafts - Shoreham and River Bend 2-10 2.1.3.9 Other DSR-48 Crankshafts ................... 2-11 2.1.3.10 OSRV-16 Crankshafts ........................ 2-12 2.1.3.11 DSRV-20 Crankshafts ........................ 2-13 2.1.3.12 Engine Block ............................... 2-15 2.1.3.13 Cylinder Heads ............................. 2-16 2.1.3.14 Cylinder Head Studs ........................ 2-18 2.1.3.15 Engine Base - All Models ................... 2-18 2.1.3.16 Fuel Oil Injection Tubing .................. 2-19 2.1.3.17 Jacket Water Pump .......................... 2-19 2.1. 3.18 Pi s ton Ski rts - Type AE . . . . . . . . . . . . . . . . . . . . 2-19 2.1.3.19 Piston Skirts - Modified Type AF ........... 2-20 2.1.3.20 Piston Skirts - Types AH and AN ............ 2-20 2.1.3.21 Push Rods .................................. 2-20 2.1.3.22 Rocker Arm Capscrews ....................... 2-21 2.1.3.23 Turbochargers .............................. 2-21

2. 2 Technical Resolution of Phase II ........................... 2-22 2.3 Maintenance / Surveillance Program ........................... 2-23 3 CONCLUSIONS ..................................................... 3-1 APPENDIX A REFERENCES APPENDIX B SAMPLE LICENSE CONDITIONS NUREG-1216 v

i SAFETY EVALUATION REPORT RELATED TO THE OPERABILITY AND RELIABILITY OF EMERGENCY DIESEL GENERATORS MANUFACTURED BY TRANSAMERICA DELAVAL, INC.

1 INTRODUCTION AND BACKGROUND During the 1970s, many utilities ordered diesel generators from Transamerica Delaval, Inc. (TDI) for installation at nuclear plants in the United States.

The first of these engines to become operational at an operating plant were those at San Onofre Unit 1 in 1977. However, nuclear plant operating experience with TDI emergency diesel generators (EDGs) remained very limited until preoper-ational test programs were started at Shoreham and Grand Gulf Unit 1 in the early 1980s.

Concerns regarding the reliability of large-bore, medium-speed diesel genera-tors manufactured by TDI for application at domestic nuclear plants were first prompted by a crankshaft failure at Shoreham in August 1983. However, a broad pattern of deficiencies in critical engine components subsequently became evi-dent at Shoreham and at other nuclear and non-nuclear facilities employing TDI diesel generators. These deficiencies stemmed from inadequacies in design, manufacture, and quality assurance / quality control by TDI.

In response to these problems, 11 (now 13) U.S. nuclear utility owners formed a TDI Diesel Generator Owners Group to address operational and regulatory issues relative to diesel generator sets used for standby emergency power. On March 2, 1984, the Owners Group submitted a proposed program ("TDI Owners Group Program Plan") to the NRC that, through a combination of design reviews, quality revali-dations, engine tests, and component inspections, was intended to provide an in-depth assessment of the adequacy of the respective utilities' TDI engines to perform their safety-related function.

The Owners Group Program Plan consisted of the following major elements:

(1) Phase I: resolution of known generic problem areas intended by the Owners Group to serve as a basis for the licensing of plants during the period before completion of Phase II of the Owners Group program (2) Phase II: a design review / quality revalidation of a large set of important engine components to ensure that their design and manufacture, including specifications, quality control and quality assurance, and operational surveillance and maintenance, are adequate (3) Expanded engine tests and inspections as needed to support Phases I and II The NRC staff had previously concluded in a Safety Evaluation Report (SER) dated August 13, 1984, that the Owners Group Program Plan incorporates the essential elements needed to resolve the outstanding concerns relating to the reliability of the TDI EDGs for nuclear service.

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i The SER herein provides the staff's evaluation of the Owners Group findings and recommendations stemming from the program. Subject to the findings of this SER, the staff has concluded that a technical resolution of the generic TDI emergency diesel generator issue is available. This SER is also intended to provide guidance to NRC project managers and technical reviewers on what must be done to technically resolve the TDI issue at each individual plant.

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l 2 EVALUATION The Owners Group program and the Owners Group findings and recommendations stemming from this program have been reviewed by Pacific Northwest Laboratory (PNL) under contract to the NRC. PNL retained the services of several expert diesel engine consultants as part of its review staff and has documented its findings in the following Technical Evaluation Reports (TERs):

PNL-5600, " Review of Resolution of Known Problems in Engine Components for Transamerica Delaval Inc. Emergency Diesel Generators," December 1985.

PNL-5336, " Review of Design Review and Quality Revalidation Report for the Transamerica Delaval Diesel Generators at Shoreham Nuclear Power Station Unit 1," October 1985.

PNL-5444, " Review of Design Review and Quality Revalidation Report for the Transamerica Delaval Diesel Generators at Comanche Peak Steam Electric Station Unit 1," October 1985.

PNL-5718, " Review of Transamerica Delaval Inc. Diesel Generator Owners Group Engine Requalification Program - Final Report," December 1985.

The NRC staff worked closely with PNL in reviewing tne Owners Group program and findings therefrom and in preparing the above-mentioned PNL reports. Subject to a few clarifications as identified in this SER, the staff concurs with the PNL conclusions and recommendations presented in the PNL reports. The PNL reports are incorporated into this SER by reference.

2.1 Technical Resolution of Phase I 2.1.1 General Phase I of the Owners Group program consisted of identifying and resolving significant engine component problems that had potential generic implications.

Through an extensive review of TDI and other engine performance data in both j nuclear and non-nuclear applications, the Owners Group identified 16 compo- I nents with such problems:

air start valve capscrews -

engine base and bearing caps connecting rods -

engine mounted electrical cable connecting rod bearing shells -

high pressure fuel injection tubing crankshafts -

jacket water pump cylinder block -

piston skirts cylinder heads -

push rods cylinder head studs -

rocker arm capscrews cylinder liners * -

turbochargers DCombined with cylinder block in Owners Group evaluations.

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l The Owners Group recommended that problems with these components.be resolved before the TDI engines were placed into service to support full power nuclear plant operation. To resolve the known problems with these components, the Owners Group contracted with Failure Analysis Associates (FaAA), Palo Alto, California, and Stone and Webster Engineering Corporation (SWEC), Boston, Massachusetts, to perform extensive design reviews. Each component was addressed by these consul-tants in one or more design review documents. Each design review report in-cludes, as appropriate, materials evaluations, load and stress analyses,-fracture and fatigue analyses, and evaluations of required maintenance and surveillance.

On the basis of these reviews, the Owners Group arrived at conclusions regarding the basic adequacy of the 16 components with known problems and recommended actions that should be taken by the engine owners.

PNL's assessment of tne Owners Group findings stemming from Phase I is docu-mented in detail in PNL-5600. On the basis of its assessment, PNL concluded that the Owners Group has established a technical basis for the utilities to qualify all of the components with known problems (i.e., Phase I components) for nuclear service. PNL has generally endorsed all of the Owners Group recom-mendations pertaining to modifications and/or replacement, quality revalidation inspections, and maintenance / surveillance of Phase I components. However, PNL has recommended some additional actions in these areas beyond those the Owners Group has recommended. Details of PNL's findings and recommendations for each of the Phase I components can be found in the following sections of PNL-5600.

Component Section in PNL-5600 Air start valve capscrews 4.1.4.2 Auxiliary module wiring and terminations 4.2.4.3 DSR-4 connecting rods 4.3.4.3 DSRV-4 connecting rods 4.4.4.4 Connecting rod bearing shells 4.5.4.2 DSR-48 crankshafts Shoreham Unit 1 4.6.5.3 River Bend Unit 1 4.6.7.2 Other DSR-4 engines 4.6.8 DSRV-16-4 cylinder crankshafts 4.7.8.3 and 4.7.9 DSRV-20-4 cylinder crankshafts 4.8.5.6 Cylinder block 4.9.5.2 l

Cylinder heads 4.10.4.3 Cylinder head studs 4.11.4.3 DSR-4 engine base and bearing caps ~ 4.12.4.2 NUREG-1216 2-2

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Component Section in PNL-5600 OSRV-4 engine base and bearing caps 4.13.4.2 Fuel oil injection tubing 4.14.4.2 Jacket water pump 4.15.4.3 Piston skirts Type AE 4.16.3.3 Modified type AF 4.16.4.3 Type'AH 4.16.5.3 Type AN 4.16.6.3 Push rods 4.17.4.3 Rocker arm capscrews 4.18.4.3 Turbochargers 4.19.4.3 Subject to the clarifications and exceptions discussed in Section 2.1.3 of this SER, the NRC staff has concluded that the PNL findings and recommendations in the aforementioned sections of PNL-5600 should be implemented for TDI engines in nuclear service in addition to the Owners Group findings and recommendations.

2.1.2 Components That Warrant Special Emphasis PNL also has concluded that its findings and recommendations pertaining to seven of the above components warrant special emphasis in terms of needed load restric-tions and/or maintenance / surveillance to ensure the components' satisfactory service. Table 2.1 provides a list of those components deemed by PNL as requir-ing special emphasis. Supporting details are provided in PNL-5600. Licensing considerations relative to any necessary load restrictions are discussed in Sec-tion 2.1.3. Special emphasis for the maintenance / surveillance actions referred to in Table 2.1 will be ensured by incorporating these actions as license con-ditions (see Section 2.1.3 of this SER) 2.1.3 Clarifications, Exceptions, and Licensing Considerations Pertaining to PNL Recommendations in PNL-5600 Sections 2.1.1 and 2.1.2 provide an overall perspective on the NRC staff posi-tion concerning the PNL findings and recommendations in PNL-5600.

This section clarifies and/or discusses some of the PNL findings and recommenda-tions where it was deemed necessary by the staff. In addition, this section discusses the licensing considerations that pertain to some of the PNL recommen-dations, namely, those that PNL finds merit special emphasis (see Section 2.1.2).

Subsequent to the issuance af PNL-5600 in December 1985, the Owners Group trans-mitted Revision 2 of the Design Review / Quality Revalidation (DR/QR) report to the NRC staff (letter from J. B. George dated May 1, 1986). Revision 2 is basi-cally a revision of Appendix II of the DR/QR report dealing with generic and NUREG-1216 2-3

site-specific maintenance matrices. The background for Revision 2 is discussed in additional detail in Section 2.3 of this SER. However, for purposes of this discussion, it should be noted that Revision 2 includes revisions to a number of earlier Owners Group technical positions that were endorsed and adopted as part of PNL's findings in PNL-5600. Furthermore, Revision 2 of the DR/QR re-port was prepared and issued after the Owners Group had received and reviewed PNL-5600. Accordingly, Revision 2 is, in part, the Owners Group response to PNL-5600. Additional Owners Group comments pertaining to PNL-5600 were provided to the NRC staff in a separate letter from the Owners Group (George, May 1, 1986a). The staff has reviewed Revision 2 of the DR/QR report and the Owners Group comments and, as discussed in this section, has revised certain findings relative to the PNL findings and recommendations in PNL-5600, as appropriate.

2.1.3.1 Engine Overhaul Frequency The Owners Group had recommended an engine overhaul inspection at approximate 5 year intervals in the original versions of the DR/QR Appendix II maintenance /

surveillance (M/S) program issued for most plants. This position was endorsed by PNL in PNL-5600. This recommendation was consistent with TDI's recommendation which assumes that the engines are in fairly continuous service during this period (about 7000 operating hours). However, since the diesel engines are relied on to provide only a standby source of power with periodic test require-ments of limited duration, actual engine service time will only be a small frac-tion of what it would be during continuous-duty service. For this reason, the Owners Group now proposes in Revision 2 of the DR/QR report that a complete engine overhaul be performed at approximate 10 year intervals, namely, that one engine / unit be disassembled and inspected at the refueling outage occurring before 10 years and the second engine at the refueling outage occurring after 10 years. For plants with three engines, the third engine would be disassembled and inspected during the second refueling outage after 10 years. In addition, the Owners Group now proposes a one-time inspection to be performed at about 5 years. The one-time 5 year inspection will generally involve the same compo-nents as the 10 year overhaul inspections; however, only a sample of some types of components (typically 25%) would be inspected.

The staff concurs that there is reasonable basis to conduct the major engine overhauls at 10 year intervals rather than 5 year intervals as originally pro-posed because (1) of the comprehensive DR/QR effort conducted for each of the engine components, (2) of the limited number of operating hours for engines in nuclear standby service, and (3) a sample inspection of major engine components will be performed on a one-time basis following 5 years of service. Therefore, the staff concludes that the engine overhaul frequency proposed in Revision 2 of the generic DR/QR Appendix II M/S program is acceptable in lieu of the 5 year frequency endorsed by PNL in PNL-5600.

2.1.3.2 Air Start Capscrews PNL has endorsed the Owners Group recommendations that capscrew length be veri-fied as part of the DR/QR process for each engine and that the capscrews be torqued in accordance with SWEC and TDI recommendations discussed in Sec-tion 4.1.3.2 of PNL-5600. The latter recommendation has been incorporated by the Owners Group as part of the DR/QR Appendix II M/S program, Revision 2.

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2.1.3.3 Auxiliary Module Wiring and Terminations PNL has endorsed and adopted the inspections, replacements, etc., recommended by the Owners Group, as discussed in Section 4.2.4.3 of PNL-5600.

l 2.1.3.4 Connecting Rod Bearing Shells l PNL has endorsed '(PNL-5600, Section 4.5.4.2) the original Owners Group recom-mendation that the connecting rods be inspected, visually and dimensionally, at the outage that precedes 500 hours0.00579 days 0.139 hours 8.267196e-4 weeks 1.9025e-4 months by at least the sum of hours in a loss-of-offsite power / loss-of-coolant-accident event plus the expected number of hours between outages. The Owners Group is now proposing (see Revision 2 of DR/QR Appendix II M/S program) that these inspections be conducted for all bear-ings at each 10 year overhaul and a one-time sample inspection be performed after approximately 5 years (see Section 2.1.3.1 regarding overhaul frequency).

As discussed in Section 4.5.4.2 of PNL-5600, the staff believes that a 10 year inspection interval and a one-time 5 year inspection of a sample of the bearings are consistent with accumulated operating experience; namely, the total number of operating hours between inspections will be about the same as what has been successfully demonstrateu at Shoreham and Catawba Unit 1. On this basis and subject to PNL's recommendation for a periodic oil contamination analysis, the staff concludes that the proposed inspection frequency revision of the DR/QR Appendix II M/S program is acceptable.

The staff has concluded that the DR/QR Appendix II M/S program, Revision 2, does not satisfactorily address the need for periodic oil contamination analyses.

The staff will require that this matter be addressed satisfactorily in the plant-specific maintenance programs.

PNL has suggested in Section 4.5.4.2 of PNL-5600 that consideration be given by Duke Power Company (licensee for Catawba) to increasing the engine oil pres-sure for the Catawba engines to the level employed at Grand Gulf (about a 10%

increase). This suggestion is offered by PNL as a possible means of prolonging bearing life. However, the staff concludes that the periodic inspections recom-mended by the Owners Group will provide for the timely detection of bearing wear before it could affect the operability of the engines. The staff, there-fore, concludes that the subject PNL recommendation for increasing engine oil pressure at Catawba should be implemented at Duke Power Company's discretion and is not a requirement.

PNL has also endorsed the Owners Group recommendation that the connecting rod bearing shells be inspected radiographically to the acceptance criteria adopted by the Owners Group as part of the DR/QR program for each plant. The staff concludes that this action should be implemented for all TDI units. PNL has also endorsed the Owners Group recommendation that such radiograph inspections be performed for all new replacement connecting rod bearing shells. The staff notes that this latter recommendation has been incorporated into the DR/QR Appendix II M/S program, Revision 2.

Finally, PNL has suggested that the critical zone of adiography for new 12-in.

bearings intended for use in TDI eight-cylinder engines be extended axially to the bearing ends (rather than beginning 1/4 in from each end as recommended NUREG-1216 2-5

by the Owners Group). The Owners Group has taken exception to this sugger. tion in its letter dated May 1, 1986a, providing comments. The Owners Group noted that design modifications made with the replacement 12-in. bearing shells and 1 the 12-in. crankshaft addressed each of the conditions contributing to cracking of the original 11-in. bearings as indicated below, thus reducing the stress range level by a factor of 2.

(1) The geometry of the connecting rods and the bearing shells was changed to provide complete support to the bearing shell ends.

(2) The increase in diameter to 12 in, reduced the peak oil film pressure.

(3) Although the edge loading was not affected, the two previous changes re-duced stresses caused by the edge loading to an acceptable level.

The staff agrees with the Owners Group that PNL's suggestion regarding the crit-ical zone for radiography should not be required; however, the staff continues to encourage utilities to follow PNL's suggestion.

2.1.3.5 DSR-48 Connecting Rods PNL has recommended a number of periodic maintenance inspections in Sec-tion 4.3.4.3 of PNL-5600. Except that the major engine disassemblies and in-spections will be performed at the intervals described in Section 2.1.3.1 of this SER (rather than at 5 year intervals as recommended by PNL), the PNL recom-l mendations have been incorporated as part of the generic DR/QR Appendix II M/S i

program, Revision 2. The staff considers these periodic maintenance proposals acceptable.

i l The staff concurs with PNL that any rod eye not previously examined in accor-dance with the acceptance criteria recommended by FaAA she,uld be examined using an appropriate nondestructive technique at the first major engine disassembly.

No indications deeper than 0.04 in. should be allowed.

t 2.1.3.6 DSRV Connecting Rods i

PNL has made a number of recommendations concerning needed preservice (i.e.,

quality revalidation) inspections and periodic maintenance inspections as identi-fied in Sections 4.4.4.4.1 and 4.4.4.4.2 of PNL-5600, respectively. Many of those recommendations are actually Owners Group recommendations endorsed by PNL. With respect to preservice inspections, the NRC staff concurs with PNL's recommendations in Section 4.4.4.4.1 of PNL-5600, and concludes that these recommendations should be fully implemented as part of the DR/QR program. Among i.

these PNL recommendations is a suggestion that the two pairs of bolts above the crankpin be measured ultrasonically before and after tensioning. In addition to the reasons cited by PNL, the staff considers that proper preload is critical i

to ensuring the long-term integrity of the DSRV connecting rods. For this rea-f son the staff concludes that baseline ultrasonic elongation measurements must be performed for all DSRV connecting rods either as part of the DR/QR (pre-service) inspection or, in the case of operating plants, at first availability.

j In the latter case, first availability would include the 25% sample inspection of the connecting rods after approximately 5 years and all connecting rods at the 10 year overhaul inspections (see Section 2.1.3.1).

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With regard to the PNL-recommended periodic maintenance inspections in Sec-tion 4.4.4.4.2 of PNL-5600, the staff has found that the PNL recommendations have generally been incorporated as part of Revision 2 of the DR/QR' Appendix II M/S program with certain modifications as discussed below.

(1) The DR/QR Appendix II M/S program, Revision 2, calls for major overhaul inspections at 10 year intervals and a one-time sample inspection after about 5 years in lieu of the 5 year interval for major engine overhauls originally proposed by the Owners Group and endorsed by PNL in PNL-5600 (see Section 2.1.3.1 of this SER).

(2) The DR/QR Appendix II M/S program, Revision 2, does not incorporate PNL's recommendation that if connecting rod bolt tension is found to be reduced to less than 93% of its initial value as measured during installation, then the cause should be determined, appropriate corrective action should be taken, and the interval between checks of bolt tension should be reevaluated.

(3) The DR/QR Appendix II M/S program, Revision 2, calls for a one-time inspec-tion rather than the periodic inspections recommended by PNL regarding the degree of surface contact at the serrated joint and the zero clearance condition between the link pin and link rod.

With respect to the first item above, the staff concludes that the proposed alternative inspection interval is acceptable. However, for DSRV connecting rods with 1-7/8 .in. bolts, this finding would be subject to certain engine load restrictions. (Note that the Grand Gulf engines are the only TDI engines em-ploying 1-7/8 in. bolts.) Alternatively, if the DSRV engines with connecting rods with 1-7/8 in bolts are to be operated at loads in excess of this load limitation, these DSRV connecting rods shall be subject to a complete teardown and inspection at 5 year intervals. The staff's finding and the basis thereof are discussed in Section 2.1.3.6.1 of this SER.

With respect to item (2) above, the staff concurs with the PNL recommendation in view of the critical importance of maintaining proper bolt tension and will require that this be incorporated as part of the M/S program for each plant.

Although PNL has recommended that the 93% criterion should apply to bolt tension as determined from either torque measurements or ultrasonic measurements of bolt stretch, the staff believes that only ultrasonic measurements are suffi-ciently reliable to compare with this criterion. The staff notes that Revision 2 of the DR/QR Appendix II M/S program calls for ultrasonic measurements before each bolt is disassembled. However, utilities should verify that their plant-specific programs also require that baseline ultrasonic measurements be taken following each assembly of the bolts.

Regarding item (3) above, the staff concludes that the proposed one-time inspec-tions are acceptable in lieu of the periodic inspections recommended by PNL.

Regarding the link rod to link pin clearances, this check is intended to verify sufficient counterbore depth and thus periodic checks are unnecessary. Simi-larly, a one-time inspection of the degree of surface contact at the serrated joint will be sufficient to verify dimensional adequacy. However, licensees should consider future checks of surface contact if periodic inspections should reveal excessive detensioning of the connecting rod bolts, f,retting of the serrated surfaces, or other evidence of connecting rod distress.

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l In Sections 4.4.4.4.2 and 4.4.4.4.3 of PNL-5600, PNL has recommended that an

" appropriate nondestructive method" be employed for preservice and periodic inservice inspection of the bolt holes in the link rod box. The NRC staff con-cludes that the inspection method shall consist of either (1) the eddy current inspection method developed by FaAA for threaded carbon steel bolt holes (i.e.,

FaAA Procedure NDE 11.9, Revision 1) or (2) an alternative method shown to be equivalent to the FaAA eddy current procedure for detecting small cracks in the threads.

PNL could not reach a conclusion regarding the ability of the FaAA eddy current procedure to detect flaws as small as the 1/8-in. rejectable limit recommended by FaAA. Indeed, staff discussions with the PNL consultants indicate that there is little assurance that flaws of this size can be detected reliably. The staff concurs with PNL, however, that this element of uncertainty does not add signif-icantly to the risk of a connecting rod failure. In addition to an eddy current inspection, numerous other inspections of critical connecting rod assembly attri-butes will be performed at periodic intervals in accordance with the CR/QR Appen-dix II, Revision 2, schedule. The staff believes that these inspections should provide timely evidence of a connecting rod assembly anomaly (e.g., inadequate bolt torques (or stretch), cracks, or fretting of the serrated joint) before a connecting rod fails.

As noted in Table 2.1 of this SER and as discussed in detail in Section 2.2.1 of PNL-5600, PNL has concluded that periodic M/S actions pertaining to DSRV connecting rods warrant special emphasis in view of tha mixed results of known non-nuclear service experience, the unknown level of cwaservatism in the Owners Group stress analysis of the connecting rods, and the difficulties inherent in inspecting threaded bolt holes. Accordingly, the staff will incorporate key M/S actions as license conditions for TDI facilities with DSRV connecting rods.

Sample license conditions are provided in Appendix B to this SER.

2.1.3.6.1 Justification for Revised Inspection Interval for DSRV Connecting Rods As noted in Section 2.1.3.6, the TDI Owners Group has proposed a modification to the DR/QR Appendix II inspection matrix for the DSRV connecting rods. Re-vision 2 calls for connecting rod inspections during major overhauls at 10 year intervals and a one-time-only 25% sample inspection after about 5 years. This inspection schedule is in lieu of the 5 year interval for major overhauls originally proposed by the Owners Group and endorsed by PNL in PNL-5600.

The DSRV connecting rods in nuclear service include two basic designs that uti-lize either 1-1/2- or 1-7/8-in.-diameter upper connecting rod bolts, which thread into blind holes in the rod box just above the crankpin. In general, many DSRV connecting rods have accumulated up to 50,000 hours0 days 0 hours 0 weeks 0 months of trouble-free operation at loads up to 80% to 85% of rated load. The reported failures in non-nuclear service of DSRV connecting rods, which involved both the 1-1/2- and 1-7/8-in.

upper connecting rod bolt designs, have typically occurred after many thousands of hours of operation. The random nature of these failures suggests that these failures may be attributable to non-design-related causes as discussed in Sec-tion 4.4.2 of PNL-5600, namely, inadequate bolt preload and/or insufficient locating dowel counterbore depth in the link rod or link pin.

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Conservative two-dimensional stress analyses of the rod box were performed by the Owners Group's consultant, FaAA, for both the 1-1/2- and 1-7/8-in. bolt designs. The 1-1/2-in. bolt design was found acceptable for service at rated engine loads with calculated stress levels below the fatigue endurance limit.

However, the stress levels calculated for the 1-7/3-in bolt design were slightly above the fatigue endurance limit. Also, FaAA Report No. FaAA-84-3-14 recom-mended that periodic inspection of the 1-7/8-in. bolt holes be performed at intervals of 280 operating hours (approximately every 5 years) to ensure the timely detection of flaws before they propagate excessively.

In the staff's judgment, based on the FaAA analysis and the relative shortness of the proposed inspection interval compared with the extended periods during which the DSRV connecting rods have been operated without problems, the proposed 10 year inspection interval with a one-time sample inspection after 5 years is acceptable for the DSRV connecting rods with 1-1/2-in. bolts. The staff cannot

support a similar inspection schedule for the connecting rods having 1-7/8-in.

bolts unless they are operated at loads below those for which the preponderance of operating experience is positive. Therefore, since many of these connecting rods have accumulated up to 50,000 hours0 days 0 hours 0 weeks 0 months at loads of up to 80% to 85% of rated load and since the proposed inspection intervals are very short compared with the extended periods over which the DSRV connecting rods have been operated without problems, the staff will require that operation of DSRV engines with connecting rods employing 1-7/8-in. bolts (only Grand Gulf has engines falling into this category) be limited to 82% of rated engine load to ensure that the connecting rods are operated within the envelop of successful operating exper-ience, if the inspection interval proposed in Revision 2 is used. Alternatively, if all connecting rods of this type (1-7/8-in. bolts) are disassembled and in-spected at 5 year intervals as originally proposed by the Owners Group and en-dorsed by PNL in PNL-5600 rather than as specified in Revision 2 of the DR/QR Appendix II M/S program, the staff will not require a similar load restriction.

In summary, the staff finds that the preservice inspections recommended by PNL in Section 4.4.4.4.1 (PNL-5600) and the periodic maintenance inspections pro-posed in Revision 2 of the DR/QR Appendix II M/S program are acceptable for the DSRV connecting rods with 1-1/2-in.-diameter upper connecting rod bolts. In addition, for connecting rods with 1-7/8-in. bolts, if they are limited to op-eration at or below 82% of rated load, the same M/S program is also acceptable.

! However, if these engines are to be operated at loads greater than 82% of rated load, the proposed modification to the DR/QR Appendix II M/S program is unaccept-able, and the staff will require that all connecting rods of this type be dis-assembled and inspected at 5 year intervals. Implementation of these require-ments will provide timely identification of a connecting rod assembly anomaly (e.g., inadequate bolt torques (or stretch), cracks, or fretting of the serrated joint) before a connecting rod fails.

l The staff notes that the Grand Gulf Technical Specifications already limit engine operation to 82% of rated load because of earlier staff concerns regarding the 1 load capacity of the DSRV crankshafts and AE piston skirts. As noted in Sec-tions 2.1.3.10 and 2.1.3.18 of this SER, the staff has concluded that this in-terim load limitation is no longer necessary and may be removed. If in accord-ance with the above discussion, the licensee for Grand Gulf (Mississippi Power and Light) chooses to implement the proposed Revision 2 M/S program and schedule, it must retain the 82% load limitation, and, in adr'ition, the staf f will require NUREG-1216 2-9

that the licensee revise.its engine operating procedures and training as neces-sary to provide appropriate guidance and instruction to operators against operat-ing the engines in excess of 82% of rated load. Specific issues to be addressed are described in Section 2.1.3.9 of this SER. Finally, the staff will require that requirements for a contingency inspection of the connecting rods be incor-porated as a license condition if the engines are loaded beyond 82%.

2.1.3.7 Crankshafts - All TDI Models The staff notes that PNL-5600 does not address the subject of- engine imbalance relative to the Shoreham DSR-48 crankshafts, although this subject is addressed for the River Bend DSR-48 crankshafts, the DSRV-16 crankshafts, and the DSRV-20 crankshafts. As a matter of clarification, the staff believes that appropriate precautions should be taken for all engine models to prevent sustained engine operation in an unbalanced condition.

a Except for DSR-48 engines, the site-specific DR/QR Appendix II programs, Revi-sion 2, call for monitoring cylinder exhaust temperatures and pressures for engine imbalance at each refueling. The staff believes this should also be applied for Shoreham. The staff notes that cylinder exhaust temperatures will also be monitored on an hourly basis (while the engine is running) per Table 1 i of the generic DR/QR Appendix II program, Revision 2. It is implied in the table that only maximum cylinder exhaust temperature is of interest (i.e., not to exceed 1050*F). The staff concludes that plant-specific procedures should clarify that the hourly cylinder exhaust temperatures should also be monitored for engine imbalance.

2.1.3.8 DSR-48 Crankshafts - Shoreham and River Bend Sections 4.6.5.3 and 4.6.7.2 of PNL-5600 provide PNL's findings and recommenda-

tions relative to the DSR-48 crankshafts at Shoreham and River Bend, respec-tively. These findings and recommendations have been fully addressed in NUREG-0420, Supplement 9, for Shoreham and NUREG-0989, Supplement 3, for River Bend.

DSR-48 crankshafts are among those components that the staff has concluded war-

rant special emphasis in terms of maintenance and surveillance. Key maintenance inspections recommended by PNL have been incorporated as license conditions for Shoreham and River Bend. These include an inspection of the crankpin fillets and oil holes at each refueling outage. The site-specific section of the DR/QR i Appendix II M/S program, Revision 2, for River Bend now proposes that the crank-shaft be inspected at each refueling, consistent with PNL's recommendation, through the third refueling. Assuming positive inspection findings, these in-i spections would thereafter be performed at 5 year intervals. The staff considers

, this proposal acceptable and consistent with PNL's recommendation that a reduced frequency of inspection could be considered after several refueling outages.

However, it will be necessary to modify the existing license condition

accordingly.

The site-specific section of the DR/QR Appendix II M/S program, Revision 2, for River Bend appears to only call for a one-time inspection of the main journals

}

after 5 years rather than a periodic 5 year inspection as recommended by PNL.

In contrast, the corresponding site-specific program for Rancho Seco does appear NUREG-1216 2-10

l l to call for a periodic 5 year inspection. The staff will continue to require that the River Bend main journal inspections be performed at 5 year intervals.

2.1.3.9 Other DSR-48 Crankshafts The staff concurs with PNL's recommendations in Section 4.6.8 of PNL-5600 con-cerning actions that should be followed to show that conclusions reached for Shoreham and River Bend are applicable to Rancho Seco and any other future DSR-48 engines. PNL has recommended, in part, that torsiograph test results and torsional stresses calculated from these results should be compared with similar data from Shoreham and River Bend. The staff notes that the crankshaft material properties as obtained from the material certification reports and fabrication history should also be compared with the Shoreham and River Bend data. All of the above data and data comparisons should be submitted for NRC staff review before the engines are placed in nuclear standby service. Depend-ing on the outcome of these comparisons, further testing and analysis may be required by the staff to establish a " qualified" load capacity for the subject engines.

Once a qualified load capability for the subject engines nas been established satisfactorily, PNL's findings and recommendations for the Shoreham and River Bend crankshaf ts (i.e. , Sections 4.6.5.3 and 4.6.7.2 of PNL-5600) are applicable.

The findings and recommendations as they apply to other plants will be addressed by the staff in a manner similar to that for Shoreham and River Bend (see NUREG-0420, Supplement 9, and NUREG-0989, Supplement 3). Issues to be addressed by the staff include the following:

(1) Load restrictions must be incorporated into the plant Technical Specifica-tions to limit surveillance testing to loads not to exceed the engine's

" qualified" load.

(2) Engine operating procedures and training should provide proper guidance and instructions to operators against overloading the TDI diesel genera-tors above the qualified load. Specific issues include:

(a) No single operator error should cause the loading of more than one TDI engine in excess of its qualified load rating.

(b) Procedures and training in place should preclude operator action that would cause the TDI EDG load to exceed the qualified load.

(c) The training program should adequately address the technical concerns associated with the qualified load limit on the TDI EDGs.

(d) If a situation were to occur that would, for some unspecified reason, cause the EDG to exceed the qualified load, the procedures and training should provide the necessary guidance to reduce the load below the qualified load within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months .

(e) Distinctive and unique instrumentation and alarms should be installed to warn operators when the engines are loaded above the qualified load.

(3) Requirements for contingency inspection of the crankshaft if a diesel generator is overloaded above qualified load for some unspecified reason NUREG-1216 2-11

- - ._ - -.,..e -,.__s.-.

will be specified as a license condition. A sample license condition is provided in Appendix B to this SER and was taken from NUREG-0989, Supplement 3.

(4) The periodic inspections specified in the site-specific section of the DR/QR Appendix II M/S program, Revision 2, are the same as those for River Bend (see Section 2.1.3.8 of this SER). The staff finds this program acceptable subject to the clarification discussed in Section 2.1.3.8 of this SER that the main journal inspections will be performed at 5 year intervals rather than on a one-time basis. License conditions incorporat-ing key inspection items will be necessary. Sample license conditions are provided in Appendix B to this SER. These sample license conditions are similar to those established for River Bend.

Additional operating and maintenance practices as described in Section 4.6.6.4.1 of PNL-5600 may be necessary depending on how close the harmonic speeds arc ,to the nominal engine speed of 450 rpm. At River Bend, for example, even though the normal response to the 5th order harmonic (which is in resonance at 455 rpm) was found to be small, there was a concern regarding thE potential for excita-tion of the 5th order under conditions of cylinder imbalance and slight over-speed. The staff finds that this issue should also be evaluated for Rancho Seco and any other future DSR-48 crankshafts.

2.1.3.10 DSRV-16 Crankshafts As discussed in Section 4.7.8.3 of PNL-5600, PNL has concluded that DSRV-16 crankshafts at Catawba, Comanche Peak, Grand Gulf, and Perry are adequate for loads of up to the full-rated load of 7000 kW assigned by the manufacturer, and to 110% of rated load for the percentage of operating time allowed by the manufacturer. This conclusion may also extend to other DSRV-16 crankshafts subject to certain specified confirmations.

Certain plants with DSRV-16 crankshafts (e.g., Grand Gulf and Catawba Unit 1) are currently restricted against operating beyord an engine load corresponding to a break mean effective pressure of 185 psi (about 5755 kW). These load limi-tations were discussed in supporting plant-specific SERs (NUREG-0831, Supple-ment 6, and NUREG-0954, Supplement 4) and were based in part on preliminary PNL estimates concerning the load capabilities of these crankshafts. However, on the basis of PNL's final conclusions as given in PNL-5000, the staff concludes that these load limitations are no longer necessary based on crankshaft con-siderations alone. The staff will consider licensee proposals to delete these restrictions where applicable.

Site-specific sections of DR/QR Appendix II M/S programs, Revision 2, incorpo-rate the periodic crankshaft inspections recommended by PNL in Section 4.7.8.3 except that the crankpin and main journals would apparently be inspected only once after 5 years rather than at 5 year Intervals. The staff believes that the crankpin and main journals should be inspected periodically to ensure that.

they are free of abnormal cracking or wear. However, because the DSRV-16 crank-shafts exhibit somewhat smaller stresses than the DSR-48 crankshafts, the staff

, concludes that an inspection frequency corresponding to the 10 year major engine

! overhaul schedule would be acceptable for the DSRV-16 crankshafts in lieu of the 5 year interval to be implemented for the DSR-48 crankshafts. The staff NUREG-1216 2-12 l

i

l l

i will require that such periodic inspections be incorporated as part of plant-specific M/S programs.

Finally, the staff concurs with PNL's recommendations in Section 4.7.9 of PNL-5600 regarding the actions that should be taken, including torsiograph test-ing, checking of material certification reports, and preservice crankshaft in-spections, before operational service to ensure that DSRV-16 crankshafts are i adequate for each site.

2.1.3.11 DSRV-20 Crankshafts A major benefit of the attention focused on the TDI diesel engines by the NRC staff and by the Owners Group as a result of the Shoreham crankshaft failure

! was the discovery of cracks in the San Onofre crankshafts stemming from large transient stresses during engine startups and shutdowns. The staff believes that this finding prevented a major crankshaft failure that otherwise might have occurred in the future.

The various operational restrictions recommended by the Owners Group and PNL are not Considered sufficient to ensure that the transient stress levels have been reduced sufficiently to preclude initiation of additional cracks and ultimately the potential failure of these crankshafts. For this reason, PNL has recommended that prompt action be taken to modify the engines as necessary to alleviate the transient torsional stresses. Pending completion of this effort, PNL has concluded that the crankshafts should be inspected at each refueling outage to ensure the timely detection and repair of any new cracks. >

m The staff concurs with these recommendations. The staff believes that the de-sign margins against fatigue for the San Onofre crankshafts fall short of what is normally assumed to be the case for crankshafts in general; namely, crank-shaf ts are adequate for infinite fatigue life for their intended service.

1 Apart from the San Onofre crankshafts, the DSR-48 crankshafts at Shoreham and River Bend are the most highly stressed TDI crankshafts from a fatigue stand-point in nuclear service. However, with the load restrictions that have been '

imposed on these engines, the staff has concluded that the Shoreham and River Bend crankshafts have infinite fatigue life for their intended service. Peri-odic inspections of these crankshafts, which are required by the staff, are of a strictly confirmatory nature and provide added assurance that the crankshafts will not be subject to fatigue failure.

The staf f and PNL concur with the reasonableness of the fracture mechanics anal-l ysis performed by FaAA and the conclusions drawn from the analysis; namely,

cracks would not be expected to propagate sufficiently to cause a crankshaft

- fracture before crankshaft inspections to be performed at each refueling out-

, age. The staff believes that this constitutes an adequate basis for continued 1 use of the crankshafts for an interim period pending replacement or modifica-tion of the crankshafts to provide adequate fatigue resistance. The staff does not consider it appropriate, however, to rely indefinitely on an acceler-ated inspection schedule to compensate for a deficiency in design that makes these crankshaf ts prone to fatigue crack initiation and propagation contrary

to normal industry practice and expectation. The staff concurs with PNL that

! the root cause of the cracking should be corrected to ensure the long-term l

i reliability of these engines.

1 NUREG-1216 2-13

The staff has requested (letter from Dudley dated May 27, 1986) that Southern California Edison Company (licensee for San Onofre Unit 1) commit to a program l to correct the root cause of the cracking problem and will negotiate a suitable I schedule for completing this effort. l Pending appropriate modifications to correct the crankshaft cracking problem, the following issues must be addressed:

(1) The periodic inspections recommended by PNL in Section 4.8.5.6.2 of PNL-5600 have been incorporated into the site-specific section of the )

DR/QR Appendix II M/S program, Revision 2. Key periodic inspection items will be incorporated as license conditions. Sample license conditions are provided in Appendix B to this SER. These license conditions include pro-vision for prompt NRC notification if cracks are found during these inspec-tions. The staff concurs with PNL recommendations in Section 4.8.5.6.2 of PNL-5600 concerning the repairs and additional analyses that should be performed if cracks are found during future inspections. Depending on the outcome of this evaluation, the staff may require that actions to correct the cracking problem be completed before plant restart.

(2) The plant Technical Specifications should be revised to limit diesel gen-erator surveillance testing to 4500 kW i 5%.

(3) Engine operating procedures and training should be revised as necessary to provide appropriate guidance and Instruction to operators against over-loading the diesel engines beyond 4500 kW i 5%. Specific issues to be addressed are described in Section 2.1.3.9 of this SER.

(4) Requirements for contingency inspection of the crankshaft if the crankshaft is loaded beyond 4500 kW i 5% for some unspecified reason will be specified as a license condition. A sample license condition specifically applicable to the DSRV-20 crankshaft at San Onofre Unit 1 has not been included in Appendix B to this SER, but should be developed in a manner similar to that for River Bend. The license condition for contingency crankshaft inspections at River Bend is provided in Appendix B to this SER.

(5) The licensee for San Onofre Unit I has proposed a change to the plant Tech-nical Specifications to limit " fast" starts of the engines to once each refueling outage as recommended by PNL. Monthly surveillance tests are to be " slow" starts. PNL's understanding of what constitutes a slow start appears to be a least a 24-sec start to rated speed (see Section 5.8.4.3 of PNL-5600). However, the proposed plant Technical Specification would permit any start duration exceeding 10 sec to be considered a slow start.

The staff concludes that the licensee should submit appropriate clarifica-tion to the staff that the monthly slow starts will be at least 24 sec in duration. The plant Technical Specification should be revised accordingly as soon as practicable.

i (6) PNL recommendations in Sections 4.8.5.6.3 of PNL-5600 concerning precau-tions against operating the engine in an unbalanced condition and avoiding operation more than a few revolutions per minute (rpm) above 450 rpm need not be incorporated as a license condition. However, these recommendations should be incorporated into appropriate plant operating and surveillance testing procedures.

NUREG-1216 2-14

2.1.3.12 Engine Block Although not specifically stated in Section 4.9.5.2 of PNL-5600, PNL and the NRC staff endorse the recommendatior, of the Owners Group consultant, Failure Analysis Associates, concerning periddic inspection of the engine block for

" ligament" cracks, " stud-to-stud" cracks, and " stud-to-end" cracks as identified in Failure Analysis Associates Report No. FaAA-84-9-11.1, dated December 1984.

With the exception of Rancho Seco, the site-specific sections of the DR/QR Appendix II M/S program, Revision 2, reference Section 02-315A of the DR/QR report, which in turn references FaAA-84-9-11.1. The staff understands that the omission of Rancho Seco from Appendix II was inadvertent, and the site-specific section should be the same as that for River Bend.

As noted in Table 2.1, the cylinder blocks are among those components that the NRC staff and PNL have concluded warrant special emphasis from a maintenance /

surveillance standpoint. Accordingly, the staff has concluded that the following periodic inspections of the cylinder blocks should be required as conditions of the license (see Appendix B to this SER):

(1) Cylinder blocks should be inspected for " ligament" cracks, " stud-to-stud" cracks, and " stud-to-end" cracks as identified in FaAA-84-9-11.1. The inspection intervals should not exceed the intervals calculated using the cumulative damage index model in the subject FaAA report. In addition, inspection pethods and procedures should be consistent with or equivalent to those it.entified in the subject FaAA report.

(2) In addition to inspections specified in the aforementioned FaAA report, blocks with 'known" or " assumed" ligament cracks should be inspected at each refueling outage in accordance with PNL's recommendations in Sec-1 tion 4.9.5.2 of PNL-5600 to determine whether or not cracks have initiated on the top surface, which was exposed by the removal of two or more cylin-der heads.

In addition to the above inspection items to be incorporated as license condi-tions, PNL has also recommended that (1) visual inspections of the block be conducted under intense light, (2) inspections for cracks be conducted in the liner bore and cam gallery, and (3) magnetic particle and eddy current inspec-tions be conducted according to the specifications cited by PNL. Regarding item (1), the staff believes that these inspections are redundant to inspections that will be performed at periodic intervals as specified in the above-mentioned FaAA report and to visual inspections that will be performed for leaks on an hourly basis while the engine is running (see Table 1, DR/QR Appendix II, Revision 2). Thus, the staff will not require inclusion of such inspections in plant-specific M/S programs. l l

Regarding item (2), PNL and the staff have concurred with the Owners Group that such cracks would not be likely to propagate sufficiently to degrade the integrity of the block. The staff nonetheless believes that it is prudent to monitor these cracks at available opportunities should such cracks be known i to exist. The staff concludes that plant-specific programs should reflect this point.

Regarding item (3), the staff has not evaluated the specific merits of the PNL recommendation. However, licensees are already required, pursuant to NRC NUREG-1216 2-15

regulations and applicable industry standards, to meet certain minimum standards for nondestructive examination (NDE) inspections of safety-related components.

The staff concludes that licensees should consider PNL's recommendations on this matter and incorporate these recommendations into their program if and as deemed appropriate.

Regarding the block inspections to be performed in accordance with FaAA-84-9-11.1, the Owners Group has proposed a clarification that (1) for blocks with known or assumed ligament cracks, inspections will be performed for stud-to-stud cracks after any operation above 50% of rated load, (2) these inspections may be per-formed using an eddy current probe or a borescope with heads in place, and (3) the inspections are to be performed within 48 hours5.555556e-4 days 0.0133 hours 7.936508e-5 weeks 1.8264e-5 months after engine shutdown (letter from J. B. George dated May 1, 1986a).

The staff believes that the first clarification item above is consistent with FaAA's recommendation, which has been endorsed by PNL and which is acceptable to the staff. Regarding the second item, the NRC staff and its PNL consul-tants have previously found borescope inspections an acceptable alternative to eddy current testing for the application indicated (PNL-5600, Section 4.9.5.2).

The staf f also finds the third clarification item acceptable.

PNL and the NRC staff concur with FaAA's conclusion that there currently exists no analytical basis for operation in cases where stud-to-stud or stud-to-end cracks exceed 1.5 in. in depth. In addition, the staff will require as a condition of the license that it be promptly informed of any such cracks, re-gardless of depth. Further, the engine should not be considered operable for nuclear standby service until the proposed disposition and/or corrective actions have been approved by the NRC Staff (see Appendix B to this SER).

The NRC staff concurs with PNL's recommendation that any block with degraded microstructure (e.g., Widmanstaetten graphite) should not be placed in nuclear standby service without thorough justification by the engine owner and review by the NRC staff.

2.1.3.13 Cylinder Heads PNL has endorsed the recommendation of the Owners Group consultant, FaAA, that all cylinder heads be inspected as part of the quality revalidation inspection.

However, the Owners Group recommendation as expressed in plant-specific DR/QR reports is that a 25% sample inspection is sufficient for Gr.up III heads (i.e.,

heads cast after September 1980). In the letter to the NRC staff dated May 1, 1986a from J. B. George, the Owners Group has stated that Group III heads are much less prone to manufacturing defects than Group I or Group II heads. The Owners Group has further stated that Group III head castings have been subjected to magnetic partial inspections in accordance with TDI procedures commencing April 1984. In addition, the machined surface of the fire deck was subjected to magnetic particle inspection during this same period. The staff notes that Group III heads cast between September 1980 and April 1984 appear not to have received these inspections. However, on the basis of good operating experience

, to date with Group III heads and subject to continued implementation of air-l roll tests as described below, the staff finds the proposed 25% sample inspec-

! tion for Group III heads acceptable, l As noted in Table 2.1, cylinder heads are one of the components that PNL has concluded warrant special emphasis in the area of maintenance and surveillance.

NUREG-1216 2-16 l

l l

l l The key item in this area is PNL's recommendation in Section 4.10.4.3 of PNL-5600 l for periodic air-rolling of the engine with the cylinder cocks open to check for the presence of water in the cylinders. Except as noted for Group III heads below, this item will be incorporated as a license condition for all TDI engines (see Appendix 8 to this SER).

The Owners Group has proposed that the postoperational air-roll tests recom-mended by PNL be discontinued af ter the first operating cycle provided all heads are Group III heads and the heads demonstrated leak-free performance up to that time. The staff finds this proposal acceptable subject to the following conditions:

(1) Quality revalidation inspections have been completed for all cylinder heads.

(2) Group III heads continue to demonstrate leak-free performance. This should be confirmed with TDI before air-roll tests are discontinued.

In its letter dated May 1,1986a, the Owners Group noted that the engine can be air-rolled only if it is placed in a maintenance mode and is not available to accept a start signal. The Owners Group stated its opinion that performing an

, air roll on an engine should not be considered as a limiting condition for operation (LCO) for the plant. The staff does not agree with the Owners Group's opinion. It is the staff's position that if the engine is rot available to accept a start signal, it is technically inoperable and, therefore, the Action statement of Technical Specification 3/4.8.1 should apply. However, the subject Action statement allows I hour before the other diesel engine (s) and other re-maining ac sources must be demonstrated operable. Because the air-roll test can be performed in less than 1/2 hour, the staff believes that the subject engine can be returned to operable status, thus terminating the applicability of the measures required by the Action statement, before it is necessary to demonstrate the operability of the other diesel engine (s) and other AC sources.

Finally, as a point of clarification, the staff finds that the PNL-recommended air-roll tests should be performed except when the plant is already in the Action statement of Technical Specification 3/4.8.1. In other words, it is not the staff's intent that an engine should intentionally be put into a condition where it cannot receive a start signal if the other diesel engine (s) or other ac sources are already inoperable.

PNL has recommended in Section 4.10.4.3 of PNL-5600 that cylinder heads with any throughwall weld repair of the fire deck should not be placed in nuclear standby service if the repair is performed from one side only (i.e., a " plug weld"). The staff concurs with this recommendation and concludes that it should be incorporated into appropriate plant M/S procedures, but need not be incor-parated as a license condition.

However, as documented in Supplement 5 to the staff's SER for Catawba Unit 2 (NUREG-0954, Supplement 5), the staff has approved a weld repair procedure fur an injector bore as shown on TDI Drawing 102718, Revision 0. This weld, repair consists of welding a plug into the head, stress relieving the welds, and machin-ing the injector port back side of the plug out so that the weld is a full pene-tration weld. The full penetration weld eliminates the crack starter found in partial penetration welds of repaired heads.

NUREG-1216 2-17

Regarding PNL's recommendations for alternative procedures and acceptance criteria in future cylinder head inspections, the staff has not specifically reviewed the merits of these recommendations. The staff assumes that licensees will follow appropriate regulatory and industry standards in performing NDE inspections. The staff concludes that licensees should consider PNL's recom-mendations on this matter and incorporate them into their programs if and as appropriate.

2.1.3.14 Cylinder Head Studs PNL has endorsed findings of the Owners Group consultant, Stune and Webster Engineering Corporation, regarding the adequacy of the cylinder head studs for nuclear service subject to installation of the studs in accordance with proce-dures identified in a letter from C. Ray, Chairman, TDI Owners Group, to the individual utility owners, dated September 24, 1984. The staff notes that DR/QR Appendix II, Revision 2, does not specifically address this point. The staff will require that utilities confirm that this point is addressed in plant-specific programs.

2.1.3.15 Engine Base - All Models The DR/QR Appendix II M/S program, Revision 2, incorporates PNL's recommendations in Section 4.17.4.2 of PNL-5600, except as discussed below. First, the Owners Group is now proposing a visual inspection of the base to take place at each 10 year overhaul rather than at each refueling outage as originally proposed by the Owners Group and endorsed by PNL. In addition, the Owners Group is now proposing that the base be inspected at each of the first three refueling out-ages except in cases where the licensee has confirmed that the base material microstructure conforms to that of normal Class 40 grey iron. There have been relatively few instances of cracks in the engine base, and those that have oc-curred have been generally attributable to inadequate bolt preloads and instal-lation procedures; only one case resulted from inferior quality of the casting.

These instances do not involve inadequate design. For this reason and because the engine bases will have received a quality revalidation inspection, the staff concurs with the proposed inspection interval in cases where previous inspec-tions have shown the blocks to be crack free. In cases where cracks have been found to exist (e.g., certain bearing saddles of the EDG 102 and EDG 103 en-gines at Shoreham), the staff believes that these cracks should be monitored for growth by magnetic particle or liquid penetrant inspection at alternate refueling outages as recommended by PNL. If no growth is evident after 10 years, these inspections need only be performed at subsequent major engine overhauls.

Finally, the staff believes that all the TOI Owner utilities should check each engine base for degenerate Widmanstaetten graphite. The basis for this finding is that several TDI engine blocks (which are also fabricated from Class 40 grey iron) have been found to exhibit this degenerate microstructure, which substan-tially increases the potential for developing cracks. Should any engine base be found to contain this degenerate microstructure, this should be reported to the NRC together with a detailed assessment of the adequacy of the affected engine base for nuclear standby service. The staff will evaluate the need for licensing action to address the degenerate microstructure on a case-by-case basis.

1 NUREG-1216 2-18 1 1

2.1.3.16 Fuel Oil Injection Tubing In Section 4.14.4.2 of PNL-5600, PNL recommended in part that (1) replacement fuel oil injection tubing be fabricated from SAE-1010 steel rather than SAE-1008 steel and (2) the fuel lines be shrouded (note that these were also Stone and Webster recommendations to the utility owners). The staff encourages utili-ties to follow these recommendations, but concludes that implementation should nonetheless be optional. The staff's findings on this issue are based on the fact that although implementation of these items would provide added assurance of satisfactory performance, both the Owners Group and PNL have found that the fuel lines have adequate fatigue resistance. This finding of adequate fatigue

! resistance is, of course, subject to implementation of the Owners Group recom-

, mendations for preservice inspections, acceptance criteria, and maintenance /

surveillance as documented in the plant DR/QR reports and the generic Appen-l< dix II, Revision 2, of the DR/QR reports. In addition, plant maintenance pro-grams should include the manufacturer's instructions concerning the installa-tion and inspection of the fuel line fittings if this has not already been done (see Section 4.14.4.2 of PNL-5600).

Finally, PNL has recommended that newly installed tubing and fittings be in-spected for leakage following engine operation after the engine is shut down, and that the inspector look for wet fittings or other signs of leakage. PNL has noted that inspection of the tubes during engine operation may be hazard-ous to operating personnel because of the high pressure of the fuel in the line.

This recommendation is not considered by the NRC staff to be an engine reli-ability or nuclear plant safety issue, and, therefore, licensees may implement this recommendation at their discretion. However, the staff urges licensees to give due consideration to this recommendation because it reflects the con-siderable and distinguished experience of diesel engine expert consultants under contract to PNL.

2.1.3.17 Jacket Water Pump f PNL has endorsed the findings of the Owners Group and its consultant, Stone and Webster Engineering Corporation (SWEC), as discussed in Section 4.15.4.3

of PNL-5600. This represents an endorsement of design changes for the DSR-48 engines and of the jacket water pump periodic maintenance items that are recom-mended by the Owners Group and are contained in the generic DR/QR Appendix II M/S program, Revision 2. However, the staff notes that the Appendix II M/S program, Revision 2, does not fully address additions to the pump assembly recommended by SWEC for the DSRV-20 engine pumps at San Onofre Unit 1 and iden-tified in Section 4.15.3.3.3 of PNL-5600. The licensee for San Onofre Unit 1 will be required to confirm that the items have been fully implemented and/or have been incorporated as part of the plant maintenance procedures as appropriate.

2.1.3.18 Pi, ton Skirts - Type AE PNL has concluded in Section 4.16.3.3 of PNL-5600 that the type AE piston skirts are adequate for service at their rated load and overload conditions.

This finding updates and supersedes earlier PNL findings of an interim nature that the AE piston skirts are adequate for loads ranging to 185 psi brake mean effective pressure. Accordingly, the staff concludes that loading restrictions on AE piston skirts that were imposed for a few plants (e.g., Catawba Unit 1 and Grand Gulf) are no longer necessary. The staff will consider any licensee NUREG-1216 2-19 l

proposals to delete this restriction assuming there are no other components subject to load restrictions.

PNL has endorsed the quality revalidation inspections recommended by the Owners Group in the plant DR/QR reports. As recommended by PNL, however, the staff will require that these quality revalidation inspections be completed on all AE piston skirts before initial plant operation. The staff will require that AE piston skirts at operating plants that did not receive these preservice inspec-tions be inspected at the first 10 year overhaul.

2.1.3.19 Piston Skirts - Modified Type AF PNL and the staff have concluded that modified type AF piston skirts, like the DSRV crankshafts, are adequate for engine loads ranging to 4500 kW (15%). Ac- l cordingly, the discussion in Section 2.1.3.6 of this SER concerning the load )

limitation for the DSRV-20 crankshaft applies also to the type AF piston i skirts installed at San Onofre Unit 1. The load limitations discussed ir. Sec- i tion 2.1.3.11 will remain in place for the type AF piston skirts even after the crankshafts have been modified to eliminate the cause of previously observed cracks in the crankshaft.

As noted in Table 2.1, the modified type AF piston skirts are among those components that PNL has concluded warrant special emphasis from a maintenance /

surveillance standpoint. Accordingly, the periodic inspections recommended in Section 5.16.4.3 of PNL-5600 will be incorporated as license conditions (see Appendix B to this SER). Consistent with PNL's recommendation, the license condition need only be in force until a total of 750 hours0.00868 days 0.208 hours 0.00124 weeks 2.85375e-4 months has been accumulated on the pistons and a subsequent inspection of all of the pistons has been successfully performed.

2.1.3.20 Piston Skirts - Types AH and AN The staff concurs with PNL's findings in Section 4.16.5.3 of PNL-5600 concern-ing the necessary actions to qualify type AH piston skirts for nuclear service.

The staff concludes that AH piston skirts should not be placed into nuclear service without NRC staff approval.

The staff concurs with PNL's finding in Section 4.16.6.3 of PNL-5600 that j type AN piston skirts should not be used in nuclear service.

2.1.3.21 Push Rods The NRC staf f concurs with PNL's findings in Section 4.17.4.3 of PNL-5600 that ,

the forged head and friction-welded push rod designs are acceptable for nuclear l service and that the ball-end desig'1 is not acceptable.

The generic DR/QR Appendix II M/S program, Revision 2, incorporates PNL's recom-mendations fur preservice and periodic inservice inspection of push rods. Be-cause each push rod of the friction-welded design will be liquid penetrant in-spected before it is placed in service, the staff considers PNL's suggestion concerning radiograph inspections an optional item to be implemented at the l' utility's discretion.

Finally, the generic DR/QR Appendix II M/S program, Revision 2, does not provide for a destructive examination of friction-welded push rods on random samples NUREG-1216 2-20 l l

I from each future manufacturing lot. This was an initial recommendation of the Owners Group and was endorsed by PNL. However, again because each push rod

will be initially inspected by liquid penetrant, the staff concludes that the subject destructive examination should be the utility's option.

2.1.3.22 Rocker Arm Capscrews The NRC staff concurs with PNL's findings in Section 4.18.4.3 of PNL-5600 re-garding the acceptability of the rocker arm capscrews for nuclear service assuming they are properly torqued. The staff notes that the generic DR/QR Appendix II M/S program, Revision 2, addresses the need for verifying proper torquing.

2.1.3.23 Turbochargers As discussed in Section 4.19.4.3 of PNL-5600, PNL has endorsed the Owners Group recommendations for installation and implementation of the drip and full-flow prelubrication system, quality revalidation inspections, and periodic M/S ac-tions. In addition, PNL has identified some additional recommendations in Sec-tion 4.19.4.3 of PNL-5600 that relate to periodic maintenance and surveillance.

Except as noted below, the staff finds that these recommendations are generally included either in the plant-specific DR/QR reports or in Revision 2 of the generic Appendix II of the DR/QR reports dealing with the M/S program.

PNL recommended that turbine inlet temperature be directly monitored with appro-

, priate instrumentation to ensure that it does not exceed the 1200*F maximum spe-t cified by the turbocharger manufacturer. This would require installation of j additional instrumentation for most engines. However, the Owners Group has proposed in Revision 2 of the generic DR/QR Appendix II M/S program that cylinder exhaust temperatures be monitored with existing instrumentation. Data provided by TDI indicate that limiting the maximum cylinder exhaust temperature to 1050'F ensures that the turbine inlet temperature will not exceed the manufacturer's specified limit. Thus, the staff finds the proposed alternative action acceptable.

PNL recommended that full-flow lubrication be implemented during engine coast-down. Although the Owners Group has indicated such capability exists; it was not actually included among the list of Owners Group recommendations. The NRC staff finds that periodic bearing inspections and float measurements called for by the generic DR/QR Appendix II M/S program, Revision 2, ensure that degra-dation rates for the turbocharger thrust bearings will be adequately monitored.

The staff finds, therefore, that full-flow lubrication during coastdown should be implemented at the licensee's discretion.

PNL recommended that the spectrochemical and ferregraphic oil analyses recom-mended by the Owners Group consultant, FaAA, be performed quarterly to provide early evidence of bearing degradation. The staff concurs with this recommenda-tion; however, it is not clear that it has been incorporated into the generic DR/QR Appendix II M/S program, Revision 2. The staff will require that each utility verify that this recommendation has been incorporated into the respec-tive plant-specific program.

In view of previous problems with nozzle ring components and inlet guide vanes, PNL recommended inspection of these items.'at each refueling outage. Recognizing NUREG-1216 2-21 b

,~ r- , - - . - - - - - - -

l l

i that many of the problems with nozzle ring components have occurred very early in the life of these components, the Owners Group has proposed in the DR/QR Appendix II M/S program, Revision 2, that each turbocharger be inspected after approximately 100 hours0.00116 days 0.0278 hours 1.653439e-4 weeks 3.805e-5 months of preoperational testing or, alternatively, at the first refueling. Subsequently, turbocharger nozzle ring components would be inspected at each nuclear unit on a one-turbocharger per-refueling-outage basis, and all would be inspected at each turbocharger overhaul, which is performed at 5 year intervals. Notwithstanding PNL's concern regarding the potential for broken nozzle ring components (particularly the vanes) to cause damage to the turbine, the staff notes that none of the nozzle ring problems to date have caused a turbocharger or engine failure. The staff concludes that the frequency of inspection proposed by the Owners Group is acceptable. However, the staff will require that plant-specific programs specify that any turbocharger in which nozzle ring anomalies are found be reinspected at the next refueling outage.

The DR/QR Appendix II M/S program, Revision 2, also specifies that the nozzle ring inspections may be discontinued after nozzle rings of an appropriate re-design have been installed. The staff interprets this provision as applying to the inspection of one-turbocharger per-refueling-outage item and not to the turbocharger inspections to be performed at 5 year intervals. The staff will require that this point be clarified in plant-specific programs. On this basis, the staff finds the proposed provision "to delete" to be acceptable.

As noted in Table 2.1, the turbochargers are among those components that PNL has concluded warrant special emphasis from a maintenance / surveillance standpoint.

Accordingly, the major maintenance / surveillance recommendations of the Owners Group and PNL will be incorporated as license conditions (see Appendix B to this SER).

2.2 Technical Resolution of Phase II Phase II of the Owners Group Program proceeded beyond known problem areas to systematically consider all components (approximately 150 to 170 component types per engine) important to the operability and reliability of the engines. Phase II was intended primarily to ensure that significant new problem areas do not develop in the future because of deficiencies in design or quality of manufac-ture. The Owners Group performed the Phase II design reviews and, as was the case for Phase I, recommended needed component upgrades and modifications and component inspections to validate quality of manufacture and/or assembly. A major element of the Phase 17 program was the preparation of a comprehensive engine M/S program to be impleme ted by the individual owners.

These Phase II efforts were documented by the Owners Group in OR/QR reports. In general, a DR/QR report was issued for one nuclear unit at each station, but not for the second nuclear unit at a two-unit station. The staff does expect, how-ever, that a Unit 1 DR/QR program will be fully implemented for the Unit 2 en-gines at the same station.

Design reviews performed by the Owners Group for engine components at one plant were generally applicable to similar components at other plants. Similarly, l quality revalidation inspections recommended by the Owners Group for engine com-ponents at one plant were generally applicable to similar engine components at ;

other plants, although the actual ir.spections were generally performed by the !

individual owners. The DR/QR reports for the Shoreham DSR-48 engines and j l

i NUREG-1216 2-22 i

l

the Comanche Peak DSRV-16-4 engines generally constituted the lead-engine reviews.

These reports were extensively referenced in DR/QR reports prepared for other (follow-engine) plants.

The staff's contractor, PNL, performed a detailed audit review of the DR/QR reports for the Shoreham DSR-48 engines and for the Comanche Peak DSRV-16-4 engines. These PNL reviews are documented in PNL Reports PNL-5336 and PNL-5444, respectively. PNL found that the DR/QR efforts fully met the intent of the Owners Group Program Plan, which was to establish " reasonable assurance of the ability of the TDI engines to provide reliable backup power supplies for nuclear power plant service."

PNL found that the Owners Group had adequately addressed the design and/or quality aspects of all the components included in the audit-type reviews for both plants. From the PNL review of the adequacy of the Owners Group mainte-nance recommendations for the audited components, PNL concluded that the main-tenance plan as proposed was acceptable. During their review of the Owners Group M/S recommendations for the audited components, the PNL consultants did identify additional areas that, in their engineering judgment, would repre-sent improvements for a total of 7 components of the 150 reviewed for both plants (see Section 4.0 of PNL-5336 and Section 4.0 of PNL-5444). Failure to accomplish these additional items would not seriously affect engine operability; however, PNL feels that, on the basis of good engineering practice, the engine owners should incorporate these recommendations into their M/S plans as they apply to the DSR-48, DSRV-16-4, and DSRV-20-4 engines. On the basis of the above, the staff concludes that these items should not be required by the NRC staff and that they should be implemented at the discretion of the individual utilities.

On the basis of the audit reviews of the comprehensive Owners Group Phase II reports for the two selected plants, PNL concludes that no further detailed reviews of Phase II reports by the NRC staff or its contractors need be done.

This conclusion is based on the favorable results of the two reviews and a cursory examination of other Owners Group Phase II reports. This latter exami-nation confirmed the continued quality of the Owners Group quality revalidation effort and verified that a high degree of overlap exists between the Owners Group Phase II design review conclusions pertaining to similar engine models, rendering a detailed review unnecessary and overly redundant.

The staff and its PNL consultants have concluded that implementation of the Owners Group recommendations in the Phase II reports will be effective in improving and ensuring the design adequacy and quality of the engine components and, hence, the reliability and operability of the TDI engines at the various Owners Group nuclear plants. The staff and PNL have, therefore, concluded that each individual owner should implement all Owners Group recommendations stem-ming from the plant-specific Phase II evaluations.

2.3 Maintenance / Surveillance Program The staff and its PNL consultants view the implementation of a comprehensive ;

M/S plan to be a key element of the overall effort to establish and maintain TDI diesel engine reliability and operability. Such a plan contributes to con-tinued satisfactory engine performance and facilitates the timely identification of potential engine problems.

NUREG-1216 2-23

This section expands on earlier discussions in this SER of the M/S program for TDI engines in nuclear service to explain the background of the M/S program developed by the Owners Group, general findings regarding the M/S program reached by PNL, subsequent revisions to the M/S program by the Owners Group, and, finally, the staff's conclusions pertaining to M/S programs for TDI engines in nuclear service.

As a result of its generic Phase I and Phase Il component reviews, the Owners Group developed an M/S plan applicable to each member utility's engines. This plan for each plant, which supplements the existing TDI Instruction Manual, was developed by the Owners Group from (1) its detailed review of each component's service history, (2) TDI Service Information Memoranda and correspondence on specific components, and (3) the Owners Group technical reviews done during the Phase II DR/QR reviews. The Owners Group recommendations are documented in Appendix II of the DR/QR report for each plant.

In connection with its review of the Owners Group Phase I program for the resolution of known problem areas, PNL performed detailed evaluations of the M/S requirements for Phase I components (PNL-5600). In addition, PNL evaluated the Owners Group Appendix II M/S plans for representative engine models, namely, two DSR-48 engines (Shoreham and River Bend) and one DSRV-16-4 engine (Comanche Peak) (PNL-5336, -5485, and -5444). PNL also examined the Appendix II plans for other engines to determine overall content and coverage.

On the basis of its findings in each of the above-referenced reports, PNL con-cluded in PNL-5718 that a satisfactory M/S program for nuclear standby appli-cations of TDI DSR-48 and DSRV-16-4 series engines should consist of the follow-ing elements:

(1) The recommendations concerning operation, testing, inspection, maintenance, adjustment, overhaul, and repair of the engine as incorporated in the TDI Instruction Manual, Service Information Memoranda (SIM), and TDI correspon-dence on specific M/S issues.

(2) The M/S recommendations developed by the Owners Group in Appendix II of the DR/QR reports.

(3) PNL M/S recommendations stemming from its generic Phase I review (i.e.,

PN L-5600) .

(4) PNL recommendations pertaining to surveillance monitoring while the engine is in the standy condition and during operations. These recommendations were specifically identified in PNL-5304, which was incorporated as part of the staff's supplement to the Safety Evaluation Report for River Bend (NUREG-0989, Supplement 3).

Subsequent to issuance of the above reports by PNL, the Owners Group issued Revision 2 of the Appendix II M/S program (transmitted to the NRC staff by letter dated May 1, 1986, from J. B. George). Revision 2 was issued following the Owners Group consideration of a number of exceptions taken by individual utilities to initial versions of Appendix II. The Owners Group also considered the aforementioned PNL reports in developing Revision 2 of Appendix II. Revi-sion 2 of Appendix II consists of a generic maintenance matrix applicable to all TDI engines and 12 site-specific sections that address particular items for each utility that are not covered by the generic document.

NUREG-1216 2-24

The staff has reviewed Revision 2 of Appendix II and determined that a number of differences exist between that document and M/S items endorsed and/or re-commended by PNL in the above-mentioned PNL reports. The staff has examined in detail those differences that exist for M/S items relating to Phase I com-ponents. The staff's findings in this regard have been documented in detail in Section 2.1.3 of this SER. The staff will require that plant M/S programs address these findings as appropriate.

Table 1 of Revision 2 of Appendix II basically incorporates PNL's recommenda-tions in Tables 6.2 and 6.3 of PNL-5304 concerning surveillance of key engine parameters while the engine is in either a standby or operating mode. Although a few differences exist, these are considered to be relatively minor by the staff (and are therefore acceptable) except as specifically noted in Sec-tion 2.1.3 of this SER.

The staff does not plan to perform a detailed review of Appendix II revisions affecting Phase II components. The staff believes, on the basis of the staff /

PNL review of the Owners Group program, that the Owners Group has demonstrated a high level of commitment to identifying those actions that are necessary to ensure engine operability and reliability. In addition, the Owners Group has demonstrated strong leadership toward this goal as evidenced by the very com-prehensive nature of the requalification program that it has recommended to the individual utilities.

In summary, on the basis of its review of the above-mentioned PNL Technical Evaluation Reports and of the Appendix II, Revision 2 program proposed by the Owners Group, the staff concludes that a plant M/S program incorporating the

, following elements will constitute an acceptable program:

(1) the recommendations concerning operation, testing, inspection, maintenance, adjustment, overhaul, and repair of the engine as incorporated in the TDI Instruction Manual, SIM, and TDI corraspondence on specific MS issues (2) the M/S recommendations developed by the Owners Group in Appendix II, Revision 2, of the DR/QR reports (3) additional items required by the staff as identified in Section 2.1.3 of this SER The staff will require that the owners for each plant commit to an acceptable M/S program as identified above before the staff issues final plant-specific

- SERs addressing the final resolution of the TDI engine issue.

Typically, detailed steps of preventative M/S programs for important safety-related systems such as diesel generators are not incorporated as part of the plant license or the plant Technical Specifications. Accordingly, changes to these programs are not normally subject to NRC. staff review and approval. How-ever, the staff believes that any future revisions to the M/S program (subsequent to issuance of final plant-specific SERs) should be subject to the provisions of 10 CFR 50.59 (Code of Federal Regulations) in view of the importance of the M/S program in ensuring the operability and reliability of the engines over the long term. Furthermore, in keeping with PNL's recommendation that certain com-ponents (see Table 2.1) warrant special emphasis in terms of M/S actions to ensure their adequate service, tha staff will include key M/S actions for these NUREG-1216 2-25

components as_ license conditions (see Appendix B to this SER). This ensures that any changes relative to the maintenance actions for these components recom-mended by the Owners Group and PNL will be subject to NRC staff approval.

Table 2.1 Components requiring engine load limits and/or special routine maintenance and surveillance Special maintenance Engine and load surveillance Component limited required Crankshaft DSR-48 Yes Yes DSRV-20 Yes* Yes

, Cylinder block DSR-48 (Shoreham) No Yes DSRV-16 (Comanche Peak) No Yes Cylinder heads No Yes i

Connecting rods DSRV engines, 1-7/8-in. bolts Yes Yes DSRV engines, 1-1/2-in. bolts No Yes Piston skirts j Type AF Yes Yes Turbocharger No Yes

Limitations on engine testing have been established to minimize crankshaft torsional stresses during startup ;

transients. '

l 1

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NUREG-1216 2-26 l i

i 1

.. -. .. - - - _ . ~ -- . . .-- -. _ . _ - - -

L l

i 3 CONCLUSIONS l

The NRC staff and its PNL consultants have completed their evaluation of the Owners Group program to validate and upgrade, as necessary, the design and l manufacturing qualityLof the TDI diesel generators for nuclear standby service.

The staff has concluded that implementation of the Owners Group and PNL recom-mendations concerning quality revalidation inspections, component modifications s and replacement, load restrictions, operating precautions, etc., will establish j the adequacy of the TDI diesel generators for nuclear standby service as re-quired by General Design Criterion 17 of Appendix A to 10 CFR 50. The staff further concludes that these actions will ensure that the design and manufactur-ing quality of the TDI engines is within the range normally assumed for diesel engines designed and manufactured in accordance with 10 CFR 50, Appendix B.

4 Continued reliability and operability of the TDI engines for the life of the facilities will be ensured by implementation of the maintenance / surveillance program discussed in Section 2.3 of this SER.

Accordingly, the staff has concluded that a technical resolution is available to address the so-called TDI diesel generator issues (namely, the concerns that were raised regarding the reliability of the TDI diesel-generators fol-lowing the crankshaft failure at Shoreham in August 1983). Technical resolu-tion will involve implementation of an acceptable Phase I program as identi-fied in Section 2.1 of this SER,-an acceptable Phase II program as identified in Section 2.2 of this SER, and implementation of an acceptable maintenance /

, surveillance program as identified in Section 2.3 of this SER. These' actions are supplemental.to requirements that-must normally be satisfied (e.g , Regu-l latory Guide 1.108) as a prerequisite for obtaining an operating license-

(NUREG-0800).

Generic Phase I issues, problem areas of a plant-specific nature, and maintenance / surveillance programs must be fully' addressed as a condition for

issuance of an operating license. Where other issues remain to be closed out (e.g., Phase II issues) in accordance with this SER, a license condition should

! be imposed requiring such closeout by the first refueling outage.

With regard to Phase I components, the NRC staff and PNL have concluded that several of these components merit special emphasis ~in the areas of load restric-tions and/or maintenance and surveillance. These components include the DSRV i i

connecting rods, DSR-48 crankshafts, DSRV-20-4 crankshafts, cylinder blocks, cylinder heads, type AF piston skirts, and turbochargers. Engine load restric-tions must be addressed in the-plant Technical Specifications, license condi-tions, engine operating procedures, and operator training, as appropriate. The

, most critical periodic maintenance / surveillance actions.for these components will be incorporated as license conditions.

1

-NUREG-1216 1 i

APPENDIX A REFERENCES

l Code of Federal Regulations, Title 10, " Energy" (10 CFR), U.S. Government Printing Office, Washington, D.C. (contains General Design Criteria).

Dudley, R. , NRC, letter to K. Buskin, Southern California Edison Company, "Transamerica Delaval Diesel Engine Reliability and Operability," May 27, 1986.

Failure Analysis Associates, Inc., Report No. FaAA-84-3-14, " Design Review of Connecting Rods for Transamerica Delaval DSRV-4 Series Diesel Generators,"

August 1984.

-- , Report No. FaAA-84-9-11.1, " Design Review of TDI R-4 and RV-4 Series Emergency Diesel Generator Cylinder Blocks," December 1984.

G:orge, J. B. , Chairman, TDI Owners Group, letter to H. R. Denton, NRC, "Revi-sion 2 of Final DR/QR Reports for TDI Diesel Generators," May 1, 1986.

-- , letter to H. R. Denton, NRC, "NRC Draft Ser for Technical Resolution of G3neric TDI Diesel Generator Issue," May 1, 1986a.

Pacific Northwest Laboratory, PNL-5304, " Review and Evaluation of Transamerica Dalaval, Inc., Diesel Engine Reliability and Operability - San Onofre Nuclear Generating Station Unit 1," Novemben 1984.

-- , PNL-5336, " Review of Design Review and Quality Revalidation Report for the Transamerica Delaval Diesel Generators at Shoreham Nuclear Power Station Unit 1,"

October 1985.

-- , PNL-5444, " Review of Design Review and Quality Revalidation Report for the Transamerica Delaval Diesel Generators at Comanche Peak Steam Electric Station Unit 1," October 1985.

-- , PNL-5485, " Review and Evaluation of Transamerica Delaval, Inc. , Diesel Engine Reliability and Operability - River Bend Station Unit 1," July 1985.

-- , PNL-5600, " Review of Resolution of Known Problems in Engine Components for Transamerica Delaval Inc. Emergency Diesel Generators," December 1985.

-- , PNL-5718, " Review of Transamerica Delaval Inc. Diesel Generator Owners Group Engine Requalification Program - Final Report," December 1985.

" Availability of all material cited is described on the inside front cover of this report.

NUREG-1216 A-1

Ray, C., Chairman, TDI Owners Gruup, letter to individual utility owners trans-mitting an Owners Group recommendation for rework of cylinder head studs, September 24, 1984.

TDI uwners Group, "TDI Owners Group Program Plan," March 2, 1984.

U.S. Nuclear Regulatory Commission, NUREG-0420, " Safety Evaluation Report Re-lated to the Operation of Shoreham Nuclear Power Station," Docket No. 50-322, Supplement 9, December 1985.

-- , NUREG-0800, " Standard Review Plan for the Review of Safety Analysis Reports i

for Nuclear Power Plants," July 1981.

-- , NUREG-0831, " Safety Evaluation Report Related to the Operation of Grand Gulf Nuclear Station, Units 1 and 2," Docket Nos. 50-416 and 50-417, Supple-ment 6, August 1984.

-- , NUREG-0954, " Safety Evaluation Report Related to the Operation of Catawba l, Nuclear Station Units 1 and 2," Docket Nos. 50-413 and 50-414, Supplement 4, December 1984; Supplement 5, February 1986.

-- , NUREG-0989, " Safety Evaluation Report Related to the Operation of River Bend Station," Docket No. 50-548, Supplement 3, August 1985.

l -- , " Safety Evaluation Report, fransamerica Delaval, Inc., Emergency Diesel l Generator Owners Group Program Plan," August 13, 1984.

l NUREG-1216 A-2

(

l l

APPENDIX B SAMPLE LICENSE CONDITIONS (1) General (applicable to all TDI engines)

Changes to the maintenance / surveillance program for the TDI diesel engines, as identified in [ ]*, shall be subject to the provisions of 10 CFR 50.59.

The frequency of the major engine overhauls referred to in the license conditions below shall be consistent with Section IV.1, " Overhaul Frequency," in Revision 2 of Appendix II of the Design Review / Quality Revalidation Report that was transmitted by letter dated May 1, 1986, from J. B. George, Owners Group, to H. R. Denton, NRC.

(2) Connecting Rods (applicable to TDI DSRV-16-4 and DSRV-20-4 engines only)

Connecting rod assemblies shall be subjected to the following inspections at each major engine overhaul:

The surfaces of the rack teeth should be inspected for signs of fretting. If fretting has occurred, it should be subject to an engineering evaluation for appropriate corrective action All connecting rod bolts should be lubricated in accordance with the

engine manufacturer's instructions and torqued to the specifications of the manufacturer. The lengths of the two pairs of bolts above the crankpin should be measured ultrasonically before and after tensioning.

The lengths of the two pairs of bolts above the crankpin should be measured ultrasonically before detensioning and disassembly of the bolts. If bolt tension is less than 93% of the value at installa-tion, the cause should be determined, appropriate corrective action should be taken, and the interval between checks of bolt tension should be reevaluated.

All connecting rod bolts should be visually inspected for thread damage (e.g. , galling), and the two pairs of connecting rod bolts above the crankpin should be inspected by magnetic particle testing to verify the continued absence of cracking. All washers used with the bolts should be examined visually for signs of galling or crack-ing, and replaced if damaged.

Identify SER and section number that identify the reference (baseline) TDI engine maintenance / surveillance program.

NUREG-1216 B-1

A visual inspection should be performed of all external surfaces of the link rod box to verify the absence of any signs of service-induced stress.

All of the bolt holes in the link rod box should be inspected for thread damage (e.g. , galling) or other signs of abnormalities. In addition, the bolt holes st'iect to the highest stresses (i.e., the pair immediately above the ci.1kpin) should be examined with an appro-priate nondestructive method to verify the continued absence of crack-ing. Any indications should be recorded for engineering evaluation and appropriate corrective action.

l The following item applies only to DSVR engines with connecting rods employing 1-7/8-in.-diameter bolts:

The following actions should be performed if the engines are operated in excess of 5740 kW:

(Specific actions have not yet been developed.)

(3) Crankshafts (applicable to TDI DSR-48 engines at Rancho Seco)*

During the first refueling outage, inspect the fillets and oil holes of the three most heavily loaded crankpin journals (Nos. 5, 6, and 7) in each crankshaft, using liquid penetrant. Indications found should also be evaluated with eddy current methods as appropriate.

During the second and third refueling outages, inspect the fillets and oil holes of two of the three most heavily loaded crankpin journals in each crankshaft, using liquid penetrant. Indications found should also be evaluated with eddy current methods as appropriate.

During each major engine overhaul, inspect the fillets and oil holes of the (a) three most heavily loaded crankpin journals (Nos. 5, 6, and 7) and (b) the main journals located between crankpin journals 5, 6, and 7.

The following actions shall be performed if the engines are operated in excess of an indicated load of [3130 kW]:**,***

Appropriate license conditions have already been incorporated into the operating license for River Bend and into the forthcoming operating license for Shoreham (see Section 2.1.3.8 of this SER).

! ** Momentary transients (not exceeding 5 sec) that result from changing bus loads need not be considered as an overload.

- - The figures shown in brackets are for River Bend, which has a qualified load capacity of 3130 kW. For Rancho Seco, different values may be appropriate depending on the value of the qualified load _ established for the Rancho Seco TDI engine crankshafts.

NUREG-1216 B-2

(a) For indicated engine loads in the range of [3130 kW) to [3200 kW]

for a period of less than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months ,* no additional action shall be required.

(b) For indicated engine loads in the range of [3130 kW) to [3200 kW]

for a period equal to or exceeding 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months ,* a crankshaft inspec-tion pursuant to item d (below) shall be performed at the next refueling outage.

(c) For indicated engine loads in the range of [3200 kW] to [3500 kW) l for a period less than 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months ,* a crankshaft inspection _ pursuant i to item d (below) shall be performed for the affected engine at the next refueling outage.

(d) For indicated engine loads in the range of [3200 kW] to [3500 kW]

for periods equal to or exceeding 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months ,* and for engine loads l exceeding [3500 kW] for any period of time, (1) the engine shall be removed from service as soon as safely possible, (ii) the engine shall be declared inoperable, and (iii)-the crankshaft shall be inspected. The crankshaft inspection shall include

crankpin journals 5, 6, and 7 (the most heavily loaded) and thel

two main journals in between, using liquid penetrant. Indications l found should be evaluated with eddy current testing as appropriate.

i If cracks are found during_ inspections of crankshafts, this condition j shall be reported promptly to the NRC staff and the affected engine j shall be considered inoperable. . The engine shall not be restored to

{ " operable status" until the proposed disposition and/or corrective j actions have been approved by the NRC staff.

~

l (4) Crankshafts (applicable only to DSRV-20-4 crankshafts at San Onofre Unit 1) i

) Oil hole locations in the five most heavily loaded main journals (i.e.,

] journals 8 through 12) for each crankshaft shall be. inspected at each refueling outage with liquid penetrant. Indications found shall be evaluated with eddy current testing as appropriate.

] During each major engine overhaul, the fillets of the most highly loaded main journals (Nos. 4 through 12) should be inspected together with-the oil holes, using liquid penetrant. Indications found shall

, be evaluated with eddy current testing as-appropriate. In addition, these inspections should be performed for the oil. holes and fillets in at least three of the crankpin journals at each major _ engine 4

overhaul.

The following actions shall be performed if the engines are operated

, in excess of 4500 kW (+5%):

1 1

i RIf there are multiple overload events within a given load range since the pre-

, vious crankshaft inspection, then the time criterion applies to the total accumulated time in that load range.

NUREG-1216 B-3 i

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(NOTE: Specific actions applicable to San Onofre Unit 1 nave not yet been developed. These actions should be specified in a manner similar to that used for River Bend.)

If cracks are found during inspections of crankshafts, this condition shall be reported promptly to the NRC staff and the affected engine shall be considered inoperable. The engine shall not be restored to

" operable status" until the proposed disposition and/or corrective actions have been approved by the NRC staff.

(5) Cylinder Blocks (applicable to all TDI engines)

Cylinder blocks shall be inspected for " ligament" cracks, " stud-to-stud" cracks and " stud-to-end" cracks as defined in a report

by Failure Analysis Associates, Inc. (FaAA) entitled " Design Review of TDI R-4 and RV-4 Series Emergency Diesel Generator Cylinder Blocks" (FaAA Report No. FaAA-84-9-11.1) and dated December 1984. (Note that the FaAA report specifies additional inspections to be performed for blocks with "known" or " assumed" ligament cracks.) The inspection intervals (i.e., frequency) shall not exceed the intervals calculated using the cumulative damage index model in the subject FaAA report.

In addition, inspection methods shall be consistent with or equivalent to those identified in the subject FaAA report.

In addition to inspections specified in the aforementioned FaAA report, blocks with "known" or " assumed" ligament cracks (as defined in the FaAA report) should be inspected at each refueling outage to determine whether or not cracks have initiated on the top surface, which was exposed because of the removal of two or more cylinder heads.

This process should be repeated over several refueling outages until the entire block has been inspected. Liquid penetrant testing or a similarly sensitive nondestructive testing technique should be used to detect cracking, and eddy current testing should be used as appro-priate to determine the depth of any cracks discovered.

If inspection reveals cracks in the cylinder blocks between stud holes of adjacent cylinders (" stud-to-stud" cracks) or " stud-to-end" cracks, this condition shall be reported promptly to the NRC staff and the affected engine shall be considered inoperable. The engine shall not be restored to " operable status" until the proposed disposition and/or corrective actions have been approved by the NRC staff.

(6) Cylinder Heads (applicable to all TDI engines)

The following air-roll test shall be performed as specified below, except when the plant is already in an Action statement of Technical Specifica-tion 3/4.8.1, " Electric Power Systems, A.C. Sources":

This report was transmitted to H. R. Denton, NRC, from C. L. Ray, Jr. , TDI Owners Group, by letter dated December 11, 1984.

NUREG-1216 B-4

l The engine shall be rolled over with the airstart system and with the cyl-l inder stopcocks open before each planned start, unless that start occurs within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months of a shutdown. The engines shall also be rolled over with

! the airstart system and with the cylinder stopcocks open after 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months , but no more than 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months , after engine shutdown and then rolled over once again approximately 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months after each shutdown. (If an engine is removed from service for any reason other than the rolling-over procedure before expiration of the 8-hour or 24-hour periods noted above, that engine need not be rolled over while it is out of service. The licensee shall air-roll the engine over with the stopcocks open at the time it is returned to ser-vice.) The origin of any water detected in the cylinder must be determined, and any cylinder head that leaks because of a crack shall be replaced.

The above air-roll test may be discontinued following the first refueling outage subject to the following conditions:

All cylinder heads are Group III heads (i.e., cast after September 1980).

Quality revalidation inspections, as identified in the Design Review / Quality Revalidation report, have been completed for all cylinder heads.

Group III heads continue to demonstrate leak-free performance. This should be confirmed with TDI before air-roll tests are discontinued.

(7) Piston Skirts (applicable to modified type AF piston skirts only)

The stud boss attachments of the modified type AF piston skirts shall be inspected with liquid penetrant at each major engine overhaul.

Indications found should also be inspected with eddy current methods as appropriate. (This license condition may be deleted for individual piston skirts after they have completed 750 hours0.00868 days 0.208 hours 0.00124 weeks 2.85375e-4 months of service at engine loads equaling 4500 kW (15%)):

The following actions shall be performed if the engines are operated in excess of 4500 kW (15%):

(Specific actions have not yet been developed.)

(8) Turbochargers (applicable to Elliot Model 65G and 90G turbochargers for all TDI engines) l l

Periodic inspections o# the turbochargers shall include the following: '

The turbocharger thrust bearings should be visually inspected for excessive wear after 40 nonprelubed starts since the previous visual inspection.

Turbocharger rotor axial clearance should be measured at each refuel-ing outage to verify compliance with TDI/Elliott specifications. In addition, thrust bearing measurements should be compared with measure-ments taken previously to determine a need for further inspection or corrective act. ion.

NUREG-1216 B-5

i Spectrographic and ferrographic engine oil analysis shall be performed quarterly to provide aarly evidence of bearing degradation. Particu-lar attention should be paid to copper level and particulate size, which could signify thrust bearing degradation.

The nozzle ring cor.ponents and inlet guide vanes should be visually inspected at each refueling outage for missing parts or parts showing distress on a one-turbocharger per-refueling-outage basis. In addi-tion, these inspections should be performed for all turbochargers at each turbocharger overhaul (i.e. , at approximately 5 year intervals).

If any missing parts or distress is noted, the entire ring assembly should be replaced and the subject turbocharger should be reinspected at the next refueling outage.

i i

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l NUREG-1216 B-6 l

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Mg,Ou na M*"3E BIBLIOGRAPHIC DATA SHEET NUREG-1216 SEE IN$TRUCTIONS ON THE REVERSE

2. TsTLt AND 5V5 TITLE J LE AVE SLANK Safety Evaluation Report Related to the Operability and Reliability of Emergency Diesel Generators Manufactured by Trans erica Delaval, Inc.

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. AuT ORis, Juf 1986 C. Berlinger, . Murphy I * "" " " ""'

fgusT'" I 19'd8" 7 *EMORMING ORfaANIZ AT:ON NA NQ MAILING ADDRESS fracende te Cears spoJECTIT ASKtWORK UNIT NuYSER Office of Nuclear actor Regulation fN/A U.S. Nuclear Regula y Commission Washington, D.C. 20 f "~ oa 6a^~' ~u"*'a N/A 10 $NN50 RING ORGANi2 ATION NAME ANO MAILING ' DR ESS ffactede l@ Coder lle TYPE OF REPORT See Item 7 Regulatory

6. PERIOD COVEREO ttactunove doNel N/A 12 SuPFLEMENT ARY NOTES N/A f 13 A85 TRACT (100 woras or 'enf A broad pattern of design, manufacturing, nd ality-related deficiencies with emergency diesel generators manufactured b T nsamerica Delaval, Inc. (TDI) became evident following a crankshaft failure at th horeham Power Station in August 1983.

In response to these problems, U.S. nuclear ity owners of these engines formed an Owners Group to address operational and gu ory issues relative to diesel generator sets used for standby emergency wer. 'he Owners Group performed extensive design reviews of all key engine component and d loped recommendations to be implemented by the individual owners conc ning nee component replacements and modifications, component inspections to v idate the s-manufactured" and "as-assembled" quality of key engine compone s, engine te ing, and an enhanced maintenance and surveillance program.

The staff evaluation of the Owners Gro program is docume ed in this report. The staff concludes that implementation of he Owners Group rec pendations plus additional actions as identified herei will establish the ach uacy of the TDI diesel generators for nuclear standby ervice as required by A 'endices A and B of 10 CFR 50.

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to DOCUMENT ANALYSIS -e KEYWORDS DESCRIPTORS 16Ava AS LIT Y Safety Evaluation Report g Transmaerica Delaval, Inc. L Unlimited Emergency Diesel Generators j 16 SECURITY CLASSIFICATION (The peret e IDENT6FIER$ OPEN ENDED TERV$

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