ML20236B102

Safety Evaluation of 870630 Submittal Supplemented on 870821 & 0911 Re Deferral of Certain Insps of Tdi Div II Emergency Diesel Generators.Deferral of Certain Design Review & Quality Revalidation Baseline Insps Approved

ML20236B102
Person / Time
Site:	Grand Gulf
Issue date:	10/15/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20236B074	List: ML20236B071 ML20236B102
References
TAC-65683, NUDOCS 8710230340
Download: ML20236B102 (3)

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1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION DEFERRED INSPECTION OF DIVISION II EMERGENCY DIESEL GENERATOR SYSTEM ENERGY RESOURCES INC.

GRAND GULF NUCLEAR STATION, UNIT 1 DOCKET NO. 50-416

1.0 INTRODUCTION

The licensee (System Energy Resources, Inc. (SERI1, formerly Mississippi Power & Light Company) requested a delay in performing certain inspections on the Division II Emergency Diesel Generator IEDGi until the scheduled 5-year confirmatory inspection, which is currently planned for refueling outage no. 5.

(RF05). These inspections were required due to a concern about the reliability of the EDGs manufactured by Transamerica Delaval, Inc. (TDI) which are used at Grand Gulf and other nuclear power plant sites.

Concern over the reliability of 1erge-bore, medium-speed diesel generators manufactured by TDI for application at domestic nuclear plants was first prompted by a crankshaft failure at Shoreham in August 1983. In addition, a broad pattern of deficiencies in critical engine components was found at Shoreham and other facilities employing TDI diesel generators. These deficien-

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cies stem from inadequacies in design, manufacture, and quality assurance / quality control by TDI. To address these problems, plant specific review and recommen-

'. dations were developed for Grand Gulf by the TDI Diesel Generator Owners Group.

? They were documented in the licensee's lett-er to the staff dated November 28, 1984. This Grand Gulf Design Review / Quality Revalidation (DR/QR1 report t

requires DR/QR baseline inspections of both Division I and II EDGs during the plant's initial refueling outage.

Prior to Grand Gulf's first refueling outage, SERI requested deferral of certain DR/0R inspections for the Division II engine to the next refueling outage IRF02).

By. letter dated August 99, 1986, the staff provided its evaluation approving SERI's request. Principally, our evaluation was based on the planned inspection of approximately two-thirds of Division II engine and our contractor's IPNL) findings (SSER No. 6) that Grand Gulf Division I and II engine components are of comparable "as-manufactured" quality. Therefore, with the absence of significant adverse findings from the inspection of the Division I engine, it was inferred that incipient problems would not be present in the Division II engine.

8710230340 871015 PDR ADOCK 05000416 G PDR

2 2.0 EVALUATION l By letter dated June 30, 1987, SERI requested that certain remaining inspections l on the Division II EDG be deferred until the scheduled 5-year confirmatory  !

inspection. This inspection is an integral part of the overall DR/QR 1 program. Based on staff comments regarding this request, SERI responded by j providing additional clarification letters dated August 21 and September 11, '

1987. At present, all DR/QR baseline inspections have already been completed for the Division I engine and 87% of the inspections for the Division II engine l also have been completed. Based on favorable findings from these inspections 1 and various other aspects which will be discussed below, the licensee asserts .q that there is sufficient justification to defer the remaining Division II <

engine inspections. Also, the licensee plans to perform additional DR/QR l inspections of the Division II engine during the next refueling outage /RFO?), j thus raising the completion level to about 89%. Essentially, the main focus of this issue is to determine whether deferring these remaining inspections 1 from the next refueling outage (RF02 scheduled to begin November 6, 19871 until RF05 would compromise the reliability of the Division IT EDG in the interim. j As discussed above, the staff has evaluated a similar request by SERI to defer approximately one-third of the Division II EDG DR/QR inspections from l the initial refueling outage to the second outage. The staff's acceptability j of the previous request was based on the following considerations: both j Division I and Division II EDGs have favorable inspection histories; the demon-strated "as-manufactured" quality of Division II EDG is comparable to the j Division I EDG; both EDGs are operated at reduced design loads; the EDGs have '

high start reliabilities; and the TDI Diesel Generator Owners Group had concur-red with SERI's approach.

During the initial refueling outage, the focus of the Division II EDG DR/QR j inspections centered on cylinders no. 5 through no. 8 (left and right banks).

t By disassembling this section of the engine, the most highly stressed compo-

nents would be inspected (i.e., main journal saddles and main journal oil ,

holes). Any deficiencies revealed in the inspection of the planned engine sec- i tion would require SERI to extend its inspection to the remaining similar i components. In its June 30, 1987 submittal, SERI indicated this approach l was adhered to, which resulted in additional inspections in some cases. Also, there was a unique characteristic relating to the Grand Gulf TDI engine-type, particularly regarding the connecting rod bolt design, and, therefore, all ,

connecting rods were subject to the appropriate inspections. )

In its September 11, 1987 submittal, the licensee compared some of the Division I and Division II inspections, and verified the "as-manufactured" quality of the two engines by obtaining similar inspection results. In addi-tion, the licensee had conducted a survey in association with Duke Engineering.

Eleven nuclear utilities which utilize TDI EDGs were surveyed, seven of which have the same EDG model as Grand Gulf. The components surveyed were the com-ponents that would be affected by the proposed deferral. SERI reports that no new problems were identified. Minor deficiencies identified during the survey were evaluated and judged by SERI not to be detrimental to EDG opera-bility.

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l In summary, the following considerations are highlighted as part of SERI's

\ justification-for proposing to defer certain Division II EDG-DR/QR inspections:

Both Grand Gulf EDGs have favorable inspection histories. The Division I EDG and 87% of the Division II EDG DR/QR baseline inspections have been completed. By the end of the next refueling outage, about 89% of the inspections will be completed on the Division II EDG,

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The "as-manufactured" quality of the Division II EDG is comparable to the l Division I EDG. l A survey of other utilities which utilize TDI EDGs identify no operational problems for those components that would be affected by the proposed deferral.

The high start reliability of the Division II EDG.

The Grand Gulf EDGs will continue to be limited to 82% of rated load by the Technical Specifications.

Continued reliability will he ensured by adherance to the overall TDI main-tenance and surveillance program, which is a condition of the Operating

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License.

Currently, the Division II engine has significantly less accumulated run-time than Division I engine. Specifically, the licensee estimates that there will be less run-time at the 5-year inspection for the Division II EDG than the run-time for the Division I EDG experienced at the initial refueling outage when its DR/QR baseline inspection was perfonned.

By deferring these remaining inspections until the engine is disassembled for the 5-year inspection, the potential risk of disassembly is reduced because an additional tear-down inspection is eliminated.

Based on these considerations, the staff has determined that there is reasonable assurance that deferring the inspection of affected components will not have an adverse effect on the reliability of the Division II EDG.

3.0 CONCLUSION

The staff finds the licensee has provided sufficient justification for approval of the proposed deferral of the remaining DR/QR inspections for the Division II engine until the scheduled 5-year confirmatory inspection. Conse-quently, the staff concludes that the Division II EDG will provide a reliable standby source of onsite power in accordance with General Design Criterion 17.

Dated: October 15, 1987 Principal Contributor:

A. Notafrancesco, Plant Systems Branch, DEST

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