ML041740754
| ML041740754 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 06/10/2004 |
| From: | Rosalyn Jones Duke Power Co |
| To: | Document Control Desk, NRC/RGN-II |
| References | |
| Download: ML041740754 (7) | |
Text
-Duke R.
A.
JONES (WPower, Vice President A Duke Energy Company Duke Power 29672 / Oconee Nuclear Site 7800 Rochester Highway Seneca, SC 29672 864 885 3158 864 885 3564 fax June 10, 2004 U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, DC 20555-0001
Subject:
Oconee Nuclear Station - Units 1, 2 and 3 Docket Nos. 50-269, 50-270, 50-287 Duke Energy Corporation Response to NRC Preliminary Greater Than Green Finding Letter Dated February 24, 2004 Duke Energy Corporation (Duke) is in receipt of the referenced NRC preliminary greater than green finding letter' and SDP Phase III Summary attachment, dated February 24, 2004.
The subject letter describes one apparent violation of 10 CFR 50 Appendix XVI, Corrective Action, concerning a failure to promptly identify and correct a condition adverse to quality associated with the Standby Shutdown Facility (SSF) Auxiliary Service Water Pump (ASWP).
The purpose of this letter is (1) to provide additional information supporting Duke's position that the SSF ASWP is past operable, as opposed to the NRC conclusion stated in the aforementioned February 24, 2004, letter, and (2) to notify the NRC that Duke does not request a regulatory conference to discuss this issue.
In NRC Inspection Report 05000269/2003004, 05000270/2003004, and 05000287/2003004 issued on October 24, 2003, a finding (Unresolved Item (URI) 05000269,270,287/2003004-01) was identified that involved inadequate corrective actions.
Specifically, the finding identified that inadequate corrective actions for increased pump seal leakage resulted in degradation of the SSF ASWP
'NRC letter to Duke Energy Corporation, (Attn: R A. Jones), "Oconee Nuclear Station - NRC Inspection Report 05000269/2004009,05000270/2004009, and 05000287/2004009; Preliminary Greater Than Green Finding" dated February 24,2004.
www. duke-energy. com
U. S. Nuclear Regulatory Commission June 10, 2004 / Page 2 inboard bearing and the associated lubricating oil.
The preliminary greater than green finding letter2 stated that the as-found conditions of the bearing and bearing lubricating oil indicated that the SSF ASWP may not have been capable of performing its safety function.
Subsequent to the October 24, 2003, Inspection Report which identified the URI, numerous discussions between Duke Energy (Duke) and the Nuclear Regulatory Commission (NRC) were held.
Significant research and analysis were conducted to determine if the SSF ASWP bearings would have performed in a manner supporting operability for the pump mission time.
Duke determined that the subject bearing was lightly loaded and through application of experienced engineering judgment, established a position that the SSF ASWP would have performed its intended safety function.
Additionally, the bearing manufacturer, SKF, was contacted to obtain their position on whether or not the SSF ASWP bearing would have been able to perform for the required mission time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The bearing was provided to SKF for examination.
Following visual inspection of the bearing, SKF concluded that the bearing was capable of operating for at least 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
A recognized industry lubrication expert rendered a similar position supporting past operability of the SSF ASWP bearing based on his many years of field experience. The results of the SKF evaluation, industry expert input and Duke's internal evaluations, were that the bearing would have run for its required mission time.
This information was promptly provided to the NRC.
In the aforementioned greater than green finding letter, the NRC acknowledged receipt of the information which evaluated the ability of the bearing to perform its safety mission, including information from the bearing vendor and a technical expert in lubrication.
However, the NRC 2 NRC letter to Duke Energy Corporation, (Attn:.R A. Jones), "Oconee Nuclear Station - NRC Inspection Report 05000269/2004009, 05000270/2004009, and 05000287/2004009; Preliminary Greater Than Green Finding" dated February 4, 2004.
U. S. Nuclear Regulatory Commission June 10, 2004 / Page 3 concluded that there was not reasonable assurance that the SSF ASWP would have been capable of operating for its 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> mission time specified in the Updated Final Safety Analysis Report (UFSAR) and the Technical Specification (TS) Bases.
This conclusion was based on the fact that the examination by the bearing vendor was limited, uncertainty regarding the method of water intrusion into the oil and heavy reliance, by the technical consultant, on light bearing loading and relatively short mission time.
Since the conclusions reached by Duke, the bearing vendor and a lubrication expert were in disagreement with the conclusion reached by the NRC, as a final alternative a decision was made, by Duke, to perform testing to validate the conclusions reached by Duke.
Preparations for conducting this specialized test received a high priority and consumed hundreds of resource hours in the ensuing months.
On May 29, 2004, Duke and SKF conducted testing to determine if the SSF ASWP bearing would have been capable of operating for its 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> mission time.
The bearing was subjected to test conditions, commensurate with as-found oil conditions and bearing loading, in order to determine if the conclusions reached by Duke and SKF were accurate.
Results of this testing have confirmed that the SSF ASWP would have been capable of operating for its 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> mission time as specified in the UFSAR and TS Bases.
Preliminary details of this testing are provided in.
In conclusion, Duke disagrees with the preliminary characterization of this finding as greater than green.
SSF ASWP bearing testing confirms the conclusions reached by Duke, SKF and a lubrication expert that this pump would have performed its safety function for the required mission time.
U. S. Nuclear Regulatory Commission June 10, 2004 / Page 4 If you have any questions or require additional information, please contact Noel Clarkson, Oconee Regulatory Compliance Group at 864-885-3077.
Very/ yuly yours, Jones Site Vice President Oconee Nuclear Site
U. S. Nuclear Regulatory Commission June 10, 2004 / Page 5 Cc:
W. D. Travers, Regional Administrator Region II M. C. Shannon, Senior Resident Inspector Oconee Nuclear Site L. N. Olshan, Senior Project Manager NRR F. J. Congel, Director, Office of Enforcement Testing Results The SSF ASWP bearing testing was conducted at the SKF North American Technical Facility located in Plymouth, Michigan, using a machine designed by SKF.
For use in the testing, Duke manufactured a test shaft which duplicated the SSF ASWP pump shaft dimensions for bearing fits and bearing housing clearances.
This manufactured shaft and a spare bearing housing assembly for the Oconee SSF ASWP were used in performing the test.
In order to duplicate the loading conditions of the pump, a "load bearing" and load cells were used-to apply load to the shaft.
The test machine was driven at approximately the same speed of the SSF ASWP (3560 RPM) using an electric motor connected to the test machine by a belt drive assembly.
Bearing cooling water was supplied at approximately 100 Deg F to 110 Deg F throughout the test, which is consistent with accident scenarios that require operation of the SSF.
Testing was performed in two phases.
The purpose of the first test phase was to determine if water would enter the bearing housing with the test assembly running.
This test used the basic assembly described above with a new SKF 6216 bearing and new Regal R & 0 32 oil.
This new oil was analyzed and the water content was determined to be 205 PPM of water in the oil.
The deflector disc (a part of the bearing housing assembly) was set to 0.065 inches clearance from the bearing housing cover, which corresponded to the as found condition from August 2003.
The machine was started and water was sprayed onto the bearing housing cover.
The spray was provided in a mist form to replicate the conditions of the observed packing leakage on the SSF ASWP.
The machine ran for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> in this configuration with water spraying onto the bearing housing cover.
At the end of the 5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> run, the machine was stopped, and the oil was drained from the bearing housing and sampled.
The sample analysis indicated a water content of 233 PPM in the oil which correlates to an increase of 5.6 PPM of water per hour during this test.
This demonstrated that water in-leakage into the bearing housing, with the pump running, is minimal.
This increase of water in the lubricant was accounted for in the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> endurance test as described below.
The purpose of the second phase of testing was to demonstrate the SSF ASWP would have performed for its 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> mission time in the as found condition from August 2003.
This test was performed using the same basic machine assembly described above.
The bearing used for this I
Testing Results testing phase was the same radial bearing that was removed from the Oconee SSF ASWP in August 2003.. The lubricant used for this test was the same water and oil combination that was drained from the SSF ASWP in August 2003.
However, the water in-leakage from the first phase of testing was extrapolated to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of run time and this additional volume of water was added to the lubricant. The test period began on May 26, 2004, and ended on May 29, 2004.
The test rig was stopped once during the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> test run to tighten the adapter sleeve for the "load" bearing (not the test bearing).
This resulted in approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> of shutdown time and approximately 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> of bearing temperature stabilization time following the re-start of the test machine.
This time was not counted toward the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> hours of operation (see time detail at the end of this description).
No adverse trends or abnormalities in bearing temperature or bearing vibration were observed during the test.
Bearing temperatures remained below 125 Deg F for the entire test.
Vibration levels remained below 0.3 inches
/second through out the test.
Visual inspection of the bearing following completion of the test did not identify any significant degradation from testing.
Internal bearing clearance measured before and after the test were within the SKF tolerances for a new SKF 6216 bearing.
The radial bearing performed acceptably for the entire 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> test.
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