ML12307A111
| ML12307A111 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/26/2012 |
| From: | James Shea Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML12307A111 (3) | |
Text
Tennessee Valley Authority, 1101 Market Street, Chattanooga, Tennessee 37402 October 26, 2012 10 CFR 50.4 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Units 1 and 2 Facility Operating License Nos. DPR-77 and DPR-79 NRC Docket Nos. 50-327 and 50-328
Subject:
Status Update of Planned Actions to Facilitate Maintenance of 6.9 Kilovolt and 480 Volt Shutdown Boards at Sequoyah Nuclear Plant, Units I and 2
Reference:
Letter from TVA to NRC, "Planned Actions to Facilitate Planned Maintenance of 6.9 Kilovolt and 480 Volt Shutdown Boards at Sequoyah Nuclear Plant, Units 1 and 2," dated July 17, 2012 [ML12202A011]
In the Reference letter, the Tennessee Valley Authority (TVA) committed to provide an update to the Nuclear Regulatory Commission (NRC) of the status of the efforts to permit the scheduling of preventive maintenance on the Sequoyah Nuclear Plant (SQN) 6.9 Kilovolt (kV) and 480 Volt (V) Shutdown Boards for Units 1 and 2 with one unit in Mode 5 or 6 or defueled and the other unit in Mode 1, 2, 3, or 4. The update is to include a projection of the submittal of the SQN Improved Technical Specifications (ITS) application and the status of associated modification design efforts. TVA committed to provide the status update by October 26, 2012.
This letter addresses the Reference commitment.
TVA's development of the SQN ITS conversion application is continuing. The planned ITS application includes provisions in Section 3.8.1, "AC Sources - Operating," and Section 3.8.9, "Distribution Systems - Operating," such that, with the associated (operating) unit in Mode 1, 2, 3, or 4 and the opposite (shutdown) unit in Mode 5 or 6 or defueled, one of the shutdown unit's 6.9 kV Shutdown Boards and the associated normally connected 480 V Shutdown Boards may be taken out of service for up to seven (7) days. The proposed ITS Completion Time of 7 days to restore operability of the affected shutdown boards is sufficient to facilitate planned preventive maintenance on the individual shutdown boards provided that compliance with the applicable ITS Conditions and Required Actions does not impose more restrictive Completion Time(s). In certain cases, plant design changes will be required to avoid entry into Conditions with more restrictive Completion Times. The planned ITS application is being developed to allow for NRC review and approval, and subsequent plant implementation without completing the design changes for the 7-day Completion Time. TVA's current projection for ITS submittal is by May 30, 2013.
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U.S. Nuclear Regulatory Commission Page 2 October 26, 2012 TVA has determined that the required design changes will include physical modifications of the SQN Auxiliary Control Air (ACA) and 125 Volt Vital Direct Current (DC) systems, and revision of certain Ultimate Heat Sink (UHS) and Essential Raw Cooling Water (ERCW) analyses.
As previously discussed, plant design changes are needed to achieve the 7-Day Completion Time as proposed in ITS Sections 3.8.1 and 3.8.9 for restoration of a shutdown unit's shutdown boards to facilitate planned preventive maintenance on the shutdown boards.
Based on preliminary evaluations, these design changes will involve physical modifications of the ACA and 125 Volt Vital DC systems, and revision of UHS and ERCW analyses.
Implementation of the changes to the UHS and ERCW analyses will require a change to Current Technical Specification (CTS) Section 3.7.5, "Ultimate Heat Sink." As such, it is TVA's intention to pursue a near term license amendment request (LAR), with submittal projected for March 31, 2013, that will provide for a relaxation of the requirements associated with the ERCW supply header water temperature of CTS 3.7.5 with one unit shutdown, and will be applicable to both SQN units.
Implementation of the other design and licensing basis changes needed to support the shutdown board preventive maintenance effort, including the ACA and Vital DC system modifications and various associated subordinate facility changes, are intended to be implemented under the provisions of 10 CFR 50.59 or as part of the ITS conversion project, as previously described. The process for developing of the ACA and Vital DC system design change projects has been initiated.
A further update of the status of the planned SQN ITS conversion application and UHS LAR submittals and associated Engineering activities to support the shutdown board preventive maintenance effort will be included in the planned SQN UHS LAR submittal letter or provided in a separate letter no later than March 31, 2013.
There is one regulatory commitment contained in this letter as described in the enclosure.
Please address any questions regarding this letter to Clyde Mackaman at (423) 751-2834.
Respe
- Ily, 7.Shea V Vce President, Nuclear Licensing Enclosure Regulatory Commitment cc (Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Sequoyah Nuclear Plant
Enclosure Sequoyah Nuclear Plant, Units I and 2 Regulatory Commitment Update Letter Regarding Shutdown Board Preventive Maintenance Effort An update of the status of the planned Sequoyah Nuclear Plant (SQN) Improved Technical Specification (ITS) conversion application and Ultimate Heat Sink (UHS) license amendment request (LAR) submittals and associated Engineering activities to support the shutdown board preventive maintenance effort will be included in the planned SQN UHS LAR submittal letter or provided in a separate letter by March 31, 2013. This letter will provide an update of the information previously provided in the letter regarding this subject dated October 26, 2012.