ML20214E423
| ML20214E423 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/19/1986 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20214D670 | List: |
| References | |
| FOIA-86-656 NUDOCS 8611240439 | |
| Download: ML20214E423 (6) | |
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- SAFETY EVALUATION REPORT (SER)
SAN ONOFRE NUCLEAR GENERATING STATION 1 RELIABILITY OF TDI DIESEL GENERATORS
1.0 INTRODUCTION
Following an extended outage of its San Onofre Nuclear Generating Station Unit 1 (SONGS-1), Southern California Edison Company (SCE) submitted a
- return-to-service plan to the U.S. Nuclear Regulatory Connission (NRC).
A problem area identified by NRC staff is the reliability of the Trans-america Delaval, Inc. (TDI) diesel engines used by SCE as emergency power sources for the SONGS-1. These engines' operability and reliability (0/R) have been brought into question by a major crankshaft failure in one TDI diesel (at the Shoreham Nuclear Power. Station in August 1983) and other problems reported by TDI diesel owners in nuclear and non-nuclear installations.
The San Onofre Nuclear Generating Station Unit 1 is served by two TDI Model No. DSRV-20-4 engines. Both are nameplate rated by TDI at 6000 kW, and operate at 450 rpm with a peak cylinder firing pressure of 1150 psig.
SCE has designated these engine-generators as DG #1 and DG #2. The most recent information provided by SCE specifies the emergency loads as a maximum of 4350 kW for DG #1 and 4443 kW for DG #2 under design basis accident conditions coincident with a simulated loss of offsite power (LOOP).
In response to the NRC concerns regarding the SONGS-1 TDI engines, SCE provided a comprehensive analysis of engine perfonnance history and actions taken to assure their 0/R. This analysis was described in 3 l
several documents and related meetings with the NRC staff and NRC's '
consultant, Pacific Northwest Laboratory (PNL).
The Pacific Northwest Laboratory was requested to assist in the review and evaluation of these documents and SCE's overall effort to assure their engines' operability and reliability. A technical evaluation report (TER) #PNL-5304 expressing PNL's conclusions and reconnendations
. regarding the capability of SCE's TDI standby emergency generators to
- serve their intended function at SONGS-1, is enclosed with this SER.
2.0 BACXGROUND Concerns regarding the reliability of large bore, medium speed diesel '
generators of the type supplied by TDI at SONGS-1 and at fifteen (15) other domestic nuclear plant: were first prompted by a crankshaft failure at Shoreham in August 1983. However, a broad pattern of deficiencies in critical engine components have since become evident at Shoreham, Grand Gulf Unit 1, SONGS-1, and at other nuclear and non-nuclear facilities employing TDI diesel generators. These deficiencies stem from inadequacies in design, manufacture and qualify assurance / quality control by TDI. ~
8611240439 PDR FOIA 861110 ELLI596-656 PDR , '
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In response to these problems, thirteen U.S. nuclear utility owners, including the licensee, fonred 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 program, which was initiated in October 1983, embodies three major efforts.
. A. Resolution of 16 known generic problems (Phase I progran). These i problems were ' identified by the Owners Group through a review of
- the operating histories of TDI engines in nuclear and non-nuclear service.
B. Design review of important engine components and quality revalida-tion of important attributes for selected e:.gine components (Phase II program). P C. Identification of any needed additional engine testing or inspec-tions, based on findings stemming from the Phase I and II procrams.
Although the total program has not yet been completed, most of the work leading to completion of Phase I has been performed.
This SER and PNL's TER precede completion of the Owners Group Program (OGP) and staff review of the Owners Group findings. The staff intends to issue an SER on each'of the 16 generic components that have been reviewed in Phase I of the OGP for determination of their reliability past the first refueling outage. Phase 2 of the OGP, a plant-specific design review / quality revalidation of all engine components necessary for engine operability, has not yet been submitted for SONGS-1. W The staff's conclusions regarding operability and reliability of SONGS-1 TDI diesel engines until the next reactor refueling, are included in this SER. The technical infonnation considered in preparing this SER is included in this SER's references.
l 3.0 EVALUATION
' " Review and Evaluation of Transamerica Delaval, Inc. Diesel Engine Reliability and Operability - San Onofre Nuclear Generating Station Unit
) 1, No. #5304, dated November 1984." This TER was prepared by Pacific t
I Northwest Laboratory (PNL) which is under contract to the NRC to perfonn technical evaluations relating to the reliability of TDI diesels. PNL has retained the services of several expert diesel consultants as part of each review staff. . .
The staff, PNL and its consultants, reviewed the licensee's submittals listed in Section 2.0 above and have performed an onsite inspection of the l
crankshaft main bearing journals' oil holes of DG #2. The oil holes of the highest stress concentration journals of both diesels (DG #1 a
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3 and DG #2) were inspected by SCE at the staff's request (ref. 5) tn ascertain whether the engine crankshafts have been subjected to excessive torsional vibration stresses. The No. 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11 main journal oil holes of DG #1, and 9 and 10 of DG #2 were inspected by SCE, and cracks of various sizes were discovered in oil holes 8, 9,10, and 11 of DG #1 and oil hole 9 of DG #2. SCE has removed the cracks by increasing the bore of the holes and restored the crankshafts to an acceptable functional reliability and has consnitted to reinspect
" critical journal oil holes at the first refueling outage. The cracks are believed to have been caused by torsional vibration stresses applied to the shaft during an inordinate number of fast start tests imposed on the engines by the Technical Specifications. A more detailed discussion and justification for acceptance of these engines' reliability and operability for the first refueling outage is included in the PNL TER Sections 3.2.1 and 3.2.3. Furthermore, in order to enhance the reliability of the engines, the staff will require changing the Technical Specification requirements from periodic (monthly) fast starts 'to periodic slow starts and retaining fast start tests only during refueling outages.
The PNL TER in Section 3.0 provides an evaluation of all (16) generic
' components identified as Phase I. The majority of the evaluations are limited to the detemination that the operability and reliability of these components is adequate through the first refueling outage, at which time additional evaluations and inspection by the Owners Group and the staff would have been completed for detemining the long term
, reliability of these components.
Augmented Maintenance and Surveillance Program The SONGS-1 maintenance and surveillance program was augmented (ref. 7) at the request of the staff (ref. 5). PNL has further augmented this program in their TER. The program outlined in the PNL TER has been discussed with the licensee (telephone conversation) and the licensee has conunitted to implement the full program included in Section 4.0 of the PNL TER.
. Operatino Restrictions We have duermined that functional reliability of the SONGS-1 diesel engines until the next refueling outage will be assured when the following operating restrictions are adhered to by the licensee:
A. Periodic (monthly) fast start tests of the engines are eliminated, and replaced by slow start tests consistent with the torsional vibration stress limits of the engines.
B. Fast start tests be perfomed only during refueling outages.
C. Load tests should be limited to 4500 KW with a 5% error band, not to exceed the brake mean effective pressure (BMEP) of 114 psig during steady state operation at maximum load.
J l . c D. Provisions should be made in plant procedures to instruct operators to limit manual application of additional loads, to those deemed necessary, during plMt emergencies, for the safe shut-down of the plant, without exceeding the overall short term capability of the engines.
With regard to item (A) above, the licensee will be requested to submit a Technical Specification change for staff review, in order to replace the periodic fast start tests, with -periodic slow start tests.
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With regard to item (C), a Technical Specification change is also required by the licensee for limiting the load to 4500 KW and thus BMEP to 114 psig.
4.0 CONCLUSION
k The NRC staff concludes that the TDI diesel e ines at SONGS-1 M 118
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7 This conclusion is based on the NRC staff /PNL rev ew of l' he current status of the Owners Group Program in resolving the TDI diesel engine issues; (2) actions taken by the licensee to enhance the reliability of the engines; (3) the proposed Technical Specification changes to limit stresses on the engine components; and (4) the commit-ments we have received from the licensee to implement the restart considerations stated in subsection 6.4 cf the PNL TER and the timely submittal of confimatory documentation for these consnitments.
5.0 REFERENCES
- 1. A letter dated January 6,1984, from D. M. Crutchfield (NRC) to K. P. Baskin (SCE), " Request for Additional Infomation Regarding Transamerica Delaval Emergency Diesel Genera' tors - SONGS-1" - This document posed questions regarding the SONGS-1 TDI engines and requested SCE to respond within 30 days.
. 2. A letter dated February 7,1984, from R. W. Krieger (SCE) to
- D. M. Crutchfield (NRC), " Docket No. 50-206, NRC's Request for Additional Information, Transamerica Delaval Emergency Diesel Generators, SONGS-1" - This letter requested additional time to respond to the cuestions posed in NRC's letter of January 6,1984
- 3. A letter dated February 29, 1984, from M. O. Medford (SCE) to D. M. Crutchfield (NRC), " Docket No. 50-206, NRC's Request for Additional Information, Transamerica Delaval Emergency Diesel Generators, SONGS-1" - This letter provided NRC with the responses to many of the questions raised in NRC's January 6,1984 letter.
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- 4. A letter dated June 29, 1984, from M. O. Medford (SCE) to D. M.
Crutchfield (NRC), " Docket No. 50-206, NRC's Request for Additional Infonnation. Transamerica Delaval Emergency Diesel Generators, SONGS-1" - The 36 attachments to this letter provided information to support the SCE contention that the SONGS-1 TDI engines are a reliable source of onsite power.
- 5. A letter dated July 26, 1984, from D. M. Crutchfield (NRC) to K. P.
Baskin (SCE), "Transamerica Delaval Diesel Inspection Requirements for Restart of San Onofre Unit 1" - This letter provided the results of NRC's review of the infonnation submitted by SCE in their June 29, 1984 letter. It iden'tified items of inspection, maintenance and surveillance, and preoperational testing that SCE must complete prior to the SONGS-1 restart. 4t
- 6. A memorandum dated August 20, 1984, from C. H. Berlinger (NRC) to C. I. Grimes (NRC), " Diesel Generator Inspection Requirements -
San Onofre 1" - The enclosure to this memorandum provided the bases -
for conclusions reached by NRC staff regarding measures to be taken prior to the SONGS-1. restart.
- 7. A letter dated August 28, 1984, from M. O. Medford (SCE) to W. A.
Paulson (NRC), " Docket No. 50-206, Return to Service Requirements Regarding TDI Emergency Diesel Generators, SONGS-1" - This letter .
prcvided additional information regarding planned TDI inspection, tests, and maintenance and surveillance in response to NRC's letter dated July 26, 1984.
- 8. A letter dated September 18, 1984, from D. M. Crutchfield (NRC) to K.- P. Baskin (SCE), " Request for Additional Information Regarding TDI Diesel Generators - SONGS-1" - This letter requested information concerning cracks found by SCE in the inspection of the oil holes in the crankshaft of DG fl.
. 9. A letter dated September 20, 1984, from C. H. Berlinger (NRC) to
- C. Ray (OG), " Request for Additional Infonnation Regarding Trans-america Delaval (TDI) Emergency Diesel Generating Units" - This
- letter requested the OG to examine their member utilities' records to detennine the occurrence of electrical transients and to evaluate the generic and plant-specific effects these transients may have had on the diesel units.
- 10. San Onofre Nuclear Generating Station Maintenance Order No. 84092733000, dated September 25, 1984, describing the torsiograph and pressure test procedure for the DG #1 crankshaft.
- 11. ~ A letter dated October 10, 1984, from M. O. Medford (SCE) to W. A.
Paulson (NRC), " Docket No. 50-206, Diesel Generator Stress Analyses Reports, San Onofre Nuclear Generating Station Unit 1" - The enclosure to this letter sunnarized the results of stress analyses performed by Failure Analysu Associates on five major componen'ts of the SONGS-1 EDGs.
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- 12. The minutes of the October 22, 1984, Owners' Group meeting held in Bethesda, Maryland.
- 13. A letter dated October 26, 1984, from M. O. Medford (SCE) to J. A.
Zwolinski (NRC), " Docket No. 50-206, Return to Service Requirements Regarding Transamerica Delaval Dnergency Diesel Generator, San Onofre o
Nuclear Genera. ting Station Unit 1" - This letter and its enclosures provided SCE's response to NRC's request (letter, September 18,1984) for information related .to the results of an NRC-raquested (letter, July 26, 1984) inspection of.the SONGS-1 EDGs.
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