ML060330447
| ML060330447 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 02/27/2006 |
| From: | Pickett D Plant Licensing Branch III-2 |
| To: | Singer K Tennessee Valley Authority |
| Pickett , NRR/DLPM, 415-1364 | |
| References | |
| TAC MC4586 | |
| Download: ML060330447 (5) | |
Text
February 27, 2006 Mr. Karl W. Singer Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801
SUBJECT:
WATTS BAR NUCLEAR PLANT, UNIT 1 REQUEST FOR ADDITIONAL INFORMATION REGARDING TECHNICAL SPECIFICATION CHANGE TO MODIFY AUXILIARY FEEDWATER START SIGNAL UPON TRIP OF MAIN FEEDWATER PUMPS (TAC NO. MC4586)
Dear Mr. Singer:
By letter dated September 23, 2004, Tennessee Valley Authority (TVA), the licensee for the Watts Bar Nuclear Plant, Unit 1, submitted a proposed change to Technical Specification Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, that would restrict the applicability of item 6.e to those conditions when one or more turbine-driven main feedwater pumps are operating (WBN-TS-04-013).
In order for the Nuclear Regulatory Commission staff to complete its review of the proposal, we request that TVA respond to the enclosed request for additional information (RAI). Based on discussions with your staff, we understand that you plan to respond to the enclosed RAI within 60 days of receipt of this letter.
Sincerely,
/RA/
Douglas V. Pickett, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-390
Enclosure:
Request for Additional Information cc w/enclosure: See next page
ML060330447 NRR-088 OFFICE LPL2-2/PM LPL2-2/LA BC:SBPB LPL2-2/BC NAME DPickett CSola DSolario MMarshall DATE 02/07/06 02/07/06 02/15/06 02/27/06
REQUEST FOR ADDITIONAL INFORMATION OFFICE OF NUCLEAR REACTOR REGULATION WATTS BAR NUCLEAR PLANT, UNIT 1 DOCKET NO. 50-390 The operability requirement that is specified by Technical Specification (TS) Table 3.3.2-1, Engineered Safety Feature Actuation System Instrumentation, Item 6.e, Trip of All Turbine Driven Main Feedwater Pumps, provides defense-in-depth for the low-low steam generator water level setpoint that is relied upon by the accident analyses for actuating the auxiliary feedwater system. This circuitry is required to be operable in Modes 1 and 2 because, as explained in the Basis for this Technical Specification requirement: In MODES 3, 4, and 5, the RCPs and MFW pumps may be normally shut down, and thus neither pump trip is indicative of a condition requiring automatic AFW initiation. Note that the TS Basis indicates that a loss of all main feedwater while operating in Modes 1 and 2 will automatically initiate AFW flow to the steam generators for decay heat and sensible heat removal without the need to rely upon operator actions. The practice of using the standby main feedwater pump until the plant is operating at around 18 percent power before starting a turbine driven main feedwater pump renders this AFW initiation circuitry incapable of performing its function in Mode 2 (as well as in Mode 1 below 18 percent power) and does not appear to satisfy the intent of the TS requirement that was established. In order to satisfy the intent of the TS requirement, the AFW automatic initiation circuitry would also have to apply to the standby main feedwater pump when it is being used in Modes 1 and 2 for providing steam generator makeup water. The fact that the turbine driven main feedwater pumps are not normally started until the plant reaches 18 percent power does not justify the proposed change; the intent of the existing TS requirement must be considered and addressed. Therefore, the following additional information is required:
- 1. Please explain why the existing TS requirement should not be applicable to operation of the standby main feedwater pump when it is being used in lieu of a turbine driven main feedwater pump when the plant is operating in Modes 1 or 2 (up to about 18 percent power) so that a loss of the standby main feedwater pump will automatically actuate the AFW system, consistent with the discussion that is provided in the TS Basis.
- 2. Please explain why the defense-in-depth capability that is intended by the existing TS requirement is not considered to be necessary for decay heat and sensible heat removal below a power level of 18 percent, considering the maximum heat load that can exist following full power operation. Note that the NRC typically does not allow automatic safety features to be replaced by manual operator actions and therefore, any credit that is taken for manual operator actions in lieu of automatic protective features must be fully explained and justified.
- 3. Please revise the proposed TS and/or TS Basis (as appropriate) to establish requirements that are consistent with the responses to Questions 1 and 2, above.
Enclosure
Mr. Karl W. Singer Tennessee Valley Authority WATTS BAR NUCLEAR PLANT cc:
Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Larry S. Bryant, Vice President Nuclear Engineering & Technical Services Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Robert J. Beecken, Vice President Nuclear Support Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Michael D. Skaggs Site Vice President Watts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381 General Counsel Tennessee Valley Authority ET 11A 400 West Summit Hill Drive Knoxville, TN 37902 Mr. John C. Fornicola, Manager Nuclear Assurance and Licensing Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Glenn W. Morris, Manager Corporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. Paul L. Pace, Manager Licensing and Industry Affairs Watts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381 Mr. Jay Laughlin, Plant Manager Watts Bar Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Spring City, TN 37381 Senior Resident Inspector Watts Bar Nuclear Plant U.S. Nuclear Regulatory Commission 1260 Nuclear Plant Road Spring City, TN 37381 County Executive 375 Church Street Suite 215 Dayton, TN 37321 County Mayor P. O. Box 156 Decatur, TN 37322 Mr. Lawrence E. Nanney, Director Division of Radiological Health Dept. of Environment & Conservation Third Floor, L and C Annex 401 Church Street Nashville, TN 37243-1532 Ms. Ann P. Harris 341 Swing Loop Road Rockwood, Tennessee 37854