ML061870062
| ML061870062 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 06/26/2006 |
| From: | Jamil D Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML061870062 (4) | |
Text
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Duke D.M. JAMIL President EnergyVice Catawba Nuclear Station 4800 Concord Rd. / CNOIVP York, SC 29745-9635 803 831 4251 803 831 3221 fax June 26, 2006 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555-0001
Subject:
Duke Power Company, LLC d/b/a Duke Energy Carolinas, LLC Catawba Nuclear Station, Unit 2 Docket No. 50-414 Special Report Duke Power Company, LLC (Duke) is submitting this report pursuant to the requirements of Catawba Nuclear Station Selected Licensee Commitment (SLC) 16.8-5, Remedial Action "B." This SLC, which concerns Diesel Generator Supplemental Testing Requirements, states that if the Cathodic Protection System is inoperable for greater than 10 days that a Special Report shall be prepared and submitted within 40 days of the initial inoperability. The report shall include the cause of the inoperability and plans for restoring the system to an operable status.
This Special report is being submitted due to an inoperability of the Cathodic Protection System protecting the Unit 2 Diesel Generator piping which exceeded 10 days as of June 4, 2006. The Special Report is included as an attachment.
There are no commitments contained in this letter. Any questions concerning this report may be directed to Anthony Jackson at 803-831-3742.
Sincerely, D. M. Jamil Attachment www. duke-energy. corn
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U.S. Nuclear Regulatory Commission June 26, 2006 Page 2 w/attachment xc: W. D. Travers, Regional Administrator, Region II U. S. Nuclear Regulatory Commission Atlanta Federal Center' 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 J. F. Stang, Jr., NRR Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 8 H4A 11555 Rockville Pike Rockville, MD 20852-2738 E. F. Guthrie, Senior Resident Inspector Catawba Nuclear Station
ATTACHMENT Special Report as required by Catawba Nuclear Station SLC 16.8-5, Remedial Action "B" Reporting Requirement:
Catawba Nuclear Station Selected Licensee Commitment (SLC) 16.8-5, "Diesel Generator Supplemental Testing Requirements," Remedial Action "B" requires that if the Cathodic Protection System cannot be restored to an operable status within 10 days that a Special Report shall be prepared and submitted. This report shall outline the cause of the inoperability and the plans for restoring the system to an operable status. This report will be submitted within 40 days of the initial inoperability.
Description of the Event:
On May 24, 2006, the bimonthly surveillance test acceptance criteria for anode well test stations 20, 37, 38, 39, and 40 associated with the Unit 2 diesel generator (D/G) piping was not met. On May 29, 2006, the bimonthly surveillance test was performed for the Unit 2 D/G piping test stations only using an alternate test method as described in the revised procedure and it met the acceptance criteria. On June 5, 2006, the Cathodic Protection system was declared "inoperable" after it was determined during a review by the system engineer that the test method used on May 29 for the Unit 2 D/G piping did not specify use of an adequate ground for the test station measurements, which resulted in erroneous readings and did not pass the bimonthly surveillance test acceptance criteria for anode well test stations 20, 37, 38, 39, and 40.
This test verifies that the test station pipe potential (voltage) is at least (-) 850mV below the test station reference electrode potential (voltage) with the Cathodic Protection energized. Determining that the pipe potential of at least (-) 850mV at each test station has been met provides for a rapid and reliable determination that an adequate level of protection has been attained. This potential is achieved by Cathodic Protection (CP) current flowing from energized anodes through the surrounding soil or water to the structure (pipe/tank). The buried anodes receive power from the associated rectifier.
Cause of Inoperability:
Troubleshooting efforts conducted on June 5 and 6 identified that anodes #8 and #9 are at their end of life and require replacing and that prepackaged anode wells (PPAW) #1 and
- 6 provided questionable results. It was determined that PPAW #6 had a damaged cable.
This cable was repaired and PPAW #6 is now in service. Work to determine the status of PPAW #1 is on-going.
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Interim Actions:
Test station 37, 38, 39, and 40 were restored to service by June 6, 2006, by the following actions:
- 1. The connections on anode #8 were cleaned;
- 2. The tap settings on rectifier #3 were adjusted to increase the output voltage and current to compensate for normal anode degradation; and
- 3. Previously abandoned and disconnected anodes at anode wells #8 and #9 were reconnected to the system at anode wells #8 and #9 shunt terminal boards which provided a boost to the system capacity;
- 4. Subsequent testing of test stations 20, 37, 38, 39, and 40 was performed and the preliminary results of these tests indicated that the corrective actions were successful with the exception of test station 20 which still did not show signs of improvement. PPAW #1 is in close proximity to test station 20.
Planned Actions:
- 1. Replace anodes #8 and #9 and, if required, PPAW #1.
The only portion of the D/G piping that does not meet the acceptance criteria of the surveillance procedure is that section located in the small area near test station 20 and PPAW #1. Even though this area is not presently meeting the acceptance criteria, some level of protection is provided by other anode wells powered by rectifier #3. Corrosion protection for the D/G piping is a long term process and poses no immediate concerns. The system is providing an acceptable level of protection to the Unit 2 D/G piping.
- 2. The site Corrective Action Program will track this issue per PIP C06-4350 until completion.
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