ML20247K673
| ML20247K673 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 05/04/1998 |
| From: | Thomas S HOUSTON LIGHTING & POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| ST-NOC-AE-00015, ST-NOC-AE-15, NUDOCS 9805220171 | |
| Download: ML20247K673 (3) | |
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.m May 4,1998 ST-NOC-AE-000155 STI 30612120 File No.: G20.02 G21.02 10CFR50.36 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Response to NRC Request for Additional Information re Fuel Handline Exhaust Booster Fan Replacements Refen:nce: STP Nuclear Operating Company letter to the NRC Document Control Desk dated l
May 1,1998, Request for Enforcement Discretion for Technical Specification 3.0.3 as It Applies to Operability Requirements for the Fuel Handling Building HVAC (ST-NOC-AE-000154)
STP Nuclear Op,; rating Company (STPNOC) submitted the referenced letter to request enforcement discretion to be able to replace a failed Unit 1 Fuel Handling Building (FHB) exhaust booster fan. The requested discretion was very similar to a request made and approved by the NRC in August 1992 to replace a Unit 2 FHB exhaust booster fan. The NRC approved the referenced request and requested that STPNOC provide additional information on the actions
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taken in response to the 1992 failure and the actions planned for the current failure. This letter responds to that request.
As noted in the request approved by the NRC, the current failure did not exhibit the same [2>
symptoms as the 1992 failure. In 1992, there were some precurscr indications of potential failure whereas in this case no similar precursors were observed. However, in both cases the work required to access and replace the failed fan motor required compensatory action and regulatory relief. From the standpoints of compliance and good operating practice, STPNOC recognizes the need to eliminate or minimize this vulnerability.
9805220171 980504~
PDR ADOCK 05000498 S
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May 4,1998 ST-NOC-AE-000155 Page 2 of 2 The August 1992 failure of the 21C exhaust booster fan was preceded by a ground r
indication in the Fuel Handing Building 480 VAC power system that was traced to the 21C l
exhaust booster fan motor. The station planned to replace or repair the fan motor at the next opportunity; however, the motor failed before these plans could be implemented. Because of the extensive damage to the 21C motor, the root cause of the failure could not be determined.
Because these motors and fans are housed in the exhaust duct and are not normally in operation, routine performance monitoring or periodic checks, such as thermography, are not practical. The original preventive maintenance plan for these fans included vibration monitoring, lubrication and meggar checking of the motors. Following the 1992 exhaust booster fan failure, l
vibration monitoring frequency was increased. More recently, meggar testing has been discontinued based on very high readings, no detectable deterioration or trends, and industry experience. The FHB HVAC, which includes the exhaust booster fans, is a Maintenance Rule scoped system that is in a normal monitoring (a)(2) status.
In response to the 1992 failure and the difficulty in replacing the component, STP management considered system modifications. However, a change was not pursued because of the extensive redesign and physical rearrangement that would be needed.
With respect to the current failure, STPNOC will take the following acdons:
- 1. Perform a root cause evaluation of the 1IB exhaust fan failure.
- 2. Evaluate physical plant modifications that would enhance the ability to isolate the individual components or trains.
- 3. Review the design basis for the three-train system to determine if adequate design margin can be maintained with one train inoperable.
- 4. Review the applicable Technical Specifications to determine if there might be changes that would facilitate the ability to work on these components in the future.
- 5. Review periodic and preventive maintenance to identify actions that could be taken to preclude failures.
These issues will be addressed as part of the STP Corrective Action Program.
Please call Mr. A. W. Harrison at 512-972-7298 or me at 512-972-7162 if you have any questions.
~
Steve Thomas Manager Design Engineering AWH/
W E
$ Q NOC-AE-000155 File No.: G20.02 l
G21.02
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Page 3 Ellis W. Merschoff Jon C. Wood
' Regional Administrator, Region IV Matthews & Branscomb U. S. Nuclear Regulatory Commission One Alamo Center 611 Ryan Plaza Drive, Suite 400 106 S. St. Mary's Street, Suite 700 Arlington, TX 76011-8064-San Antonio,TX 78205-3692 Thomas W. Alexion Institute of Nuclear Power Project Manager, Mail Code 13H3 Operations - Records Center U. S. Nuclear Regulatory Commission 700 Galleria Parkway Washington, DC 20555-0001 Atlanta, GA 30339-5957
-David P. Loveless Richard A. Ratliff Sr. Resident Inspector Bureau of Radiation Control c/o U. S. Nuclear Regulatory Commission Texas Depanment of Health P. O. Box 910 1100 West 49th Street Bay City, TX 77404-0910 Austin, TX 78756-3189 J. R. Newman, Esquire D. G. Tees /R. L. Balcom j
Morgan, Lewis & Bockius Houston Lighting & Power Co.
1800 M. Street, N.W.
P. O. Box 1700 Washington, DC 20036-5869 Houston,TX 77251 M. T. Hardt/W. C Gunst Central Power and Light Company City Public Service ATTN: G. E. Vaughn/C. A. Johnson f
P. O. Box 1771 P. O. Box 289, Mail Code: N5012 1
San Antonio,TX 78296 Wadsworth,TX 77483 A. Ramirez/C. M. Canady l
City of Austin l
Electric Utility Department l
721 Barton Springs Road i
Austin,TX 78704 i
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