ML16342A035
| ML16342A035 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 03/29/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16342A034 | List: |
| References | |
| NUDOCS 9304020032 | |
| Download: ML16342A035 (8) | |
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UNITED STATES NUCLEAR REGULATORY COIVIMISSION WASHINGTON, D.C. 20555.0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING PREOPERATIONAL ENDURANCE TESTING OF THE SIXTH EMERGENCY DIESEL GENERATOR EDG PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON POWER PLANT DCPP UNIT 2 DOCKET NO. 50-323
1.0 INTRODUCTION
The engine for the sixth emergency diesel generator (EDG), currently undergoing final installation at DCPP Unit 2 was purchased from a commercial-grade supplier (GE-L of Montreal,
- Canada, formerly known as ALCO).
This commercial grade purchase was necessitated because GE-L did not want to undertake a
10 CFR Part 50, Appendix B, quality assurance (gA) program for only a single diesel engine purchase.
As a result, it was necessary to implement a dedication program to ensure the quality and reliability of the engine.
The commercial-grade dedication program was formulated using NRC and industry guidance.
This guidance consisted of NCIG-07 (Reference 1) and Generic Letter 89-02, "Actions to Improve the Detection of Counterfeit and Fraudulently Marketed Products."
To facilitate resolution of NRC concerns regarding the commercial grade dedication of the
- EDG, and to provide additional bases for resolution of generator manufacturer gA program issues, endurance testing of the engine generator unit was identified for inclusion in the basis for engine dedication.
The testing, the associated equipment monitoring, and the post-test inspections that were conducted are discussed in the licensee's submittal of February 12, 1993 (Reference 2).
2.0 DISCUSSION The preoperational endurance testing consisted of 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> of EDG operation.
During each 8-hour segment of the test, the engine generator was run at 100 percent of rated load (2600 kw) for 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> with a step reduction in load to 2000 kw for the last hour of the 8-hour segment.
At the end of the 25 8-hour
- segments, a 2-hour run at 110 percent of rated load was performed.
Testing of the unit at 100 percent of the rated load generates the greatest stress on the unit while simulating required emergency operation.
The step reduction in load simulates
'the most severe load change expected during emergency operation.
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The endurance test provided for operation of the engine generator unit in excess of 10 million stress cycles.
At this number of cycles, premature cycle fatigue failure would likely occur if defects were present.
An additional run with a duration of 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> was conducted subsequent to completion of the endurance test and associated inspections to verify performance of the assembled engine.
Equipment monitoring was performed during these runs in accordance with the Standard 1EEE 387-1984, Section 6.2. 1(2)(b).
In addition, vibration monitoring was conducted to allow trending of vibration data.
Engine analyzer data were also taken during 100 percent power runs to trend performance of the engine on a cylinder-by-cylinder basis.
These data were collected within the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of operation at rated load, once during the middle of the 200-hour run, and again toward the end of the 200-hour run.
Electrical data (i.e., voltage, frequency,
- current, and power factor) for the generator were monitored during these runs.
Lube oil samples were taken for analysis prior to start of the endurance
- test, every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of engine run time during the
- test, and after completion of the endurance test.
Acceptance criteria used for equipment monitoring instrumentation were as prescribed in the EDG operating/maintenance vendor manual.
Fuel oil consumption at the beginning and end of the endurance test was evaluated.
Fuel oil and lube oil filter differential pressures were also. monitored, as was lube oil level (via crankcase dipstick) to monitor oil consumption.
The criteria contained in Reg Guide 1. 108, Rev.
1, Section C.2.e, for valid tests and failures were used to evaluate test failures or malfunctions.
Malfunctions during performance of the endurance testing, including problems with temporary load bank and the fuel oil booster pump discharge line, were evaluated and documented in Revision 2 to RPE M-6602 and its Minor Change (MC)
No.
1.
These were determined by the licensee and the staff to have no impact on the qualification of the EDG.
In addition, a number of minor component failures which need repairs occurred during the test.
These are also discussed below.
Based on staff evaluation, it was determined that these component failures did not affect qualification of the EDG.
Following completion of endurance
- testing, visual inspections were performed using existing plant maintenance procedures, including 18, 36, 54, 72, 90, and 108-month surveillance test procedures as a basis.
A fiberscope inspection of the cylinders for all power assemblies was performed.
In-situ inspection of main bearing clearance for all main bearings per manufacturer recommendations was also performed.
In addition, two main bearing lower shells were removed for visual inspection and dimensional checks.
Disassembly and inspection of four power assemblies, including cylinder head,
- piston, connecting
- rod, and connecting rod bearing, were performed.
The testing and inspection activities described above were completed and have been documented in RPEs M-6602 (for the engine) and E-7505 (for the generator).
Based on staff evaluation, it was concluded that inspection results are in conformance with the acceptance criteria discussed above.
As stated earlier, during the endurance test the licensee encountered a number of problems which needed evaluation and corrective actions.
- However,
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i' these problems did not impact the final outcome of the endurance test.
Discussed below is a summary of the problems encountered during the endurance testing and the remedial actions undertaken.
On December 23,
- 1992, a diesel fuel oil leak was discovered in the EDG fuel oil booster pump discharge line fitting.
The EDG was secured to contain the fuel leak and the fitting was replaced.
The problem recurred on January 13,
- 1993, and it was observed that there were excessive vibrations in the fuel oil booster pump.
The corrective action was determined to be the installation of a flexible hose assembly instead of the hard piping configuration.
In
- addition, supports were added to limit vibrations.
On January 21, some metallic debris was identified in the EDG crankcase during an inspection.
Analysis by the licensee indicated that the debris particles came from machining operations on engine components that apparently had not been cleaned prior to shipment of the engines.
Since this debris was not circulating, it did not affect any moving parts of the EDG or have any impact on engine perfor'mance.
During an inspection of the cylinder heads on the EDG prior to the final 8-hour test run, chromate residue, apparently from the coolant, was found on one of the removed cylinder heads.
The affected plug was cleaned and reworked.
Sealing capability of the plug was observed during the final 8-hour test run.
Based on the removal and inspection of five additional heads, it was concluded that no further inspections of the cylinder heads and plugs were necessary.
On February 3, 1993, it was observed during a post-maintenance test inspection that approximately 24 teeth on the ring gear-flywheel assembly had either chipped or were showing signs of wear.
The damage was confined to the teeth corners on the engine side and appeared to be the result of improper engagement.
The licensee reviewed the previous test reports on the engine and determined that the damage is related to an electrical control malfunction during testing at GEC-Alsthom in Toronto, Canada.
Failure of a control relay
'aused the flywheel ring gear and starter gear to engage improperly and damage the teeth.
The gear teeth were repaired by removal of burrs, since replacement of gear assembly was not considered necessary.
As a result of this observation, periodic inspection and maintenance procedures for the ring gear and starter drive gear have been included.
On February 24, 1993, during post-maintenance test inspection of the pistons, it was discovered that the second and third compression rings on several pistons were installed upside down.
Further investigation by the licensee and manufacturer's representative indicated that the faulty installation was traced to an error in the manufacturer's identification markings on some rings.
The reversed configuration of the oil rings on some pistons did not have any measurable effect on engine performance or lubrication characteristics.
These rings were inspected on all pistons and replaced if incorrectly oriented.
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3.0 CONCLUSION
Based on the staff's evaluation of the endurance testing and subsequent inspection results, which included visual and fiberscope inspections, as well as disassembly and inspection of four power assemblies of the sixth EDG at DCPP Unit 2, it is concluded that the endurance testing and associated post-test inspections have been completed in a satisfactory manner.
The staff has also evaluated the malfunctions which occurred during performance of the endurance testing and has determined that these malfunctions did not affect qualification of the EDG.
4.0 REFERENCES
l.
EPRI Guideline NCIG-07, "Guideline for Utilization of Commericial Grade Items in Nuclear Safety-Related Applications."
2.
PGE E Letter No. DCL-93-037 dated February 12, 1993, related to the completion of endurance testing of the EDG at DCPP Unit 2, and'iscussion of the basis for resolution of open items.
Principal Contributor: J.
Rajan Date:
March 29, 1993