ML20206H381
| ML20206H381 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 05/05/1999 |
| From: | Alexion T NRC (Affiliation Not Assigned) |
| To: | Cottle W HOUSTON LIGHTING & POWER CO. |
| References | |
| TAC-MA4900, TAC-MA4901, NUDOCS 9905110189 | |
| Download: ML20206H381 (3) | |
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May 5, 1999-3 Mr. William T. Cottle President and Chief Executive Officer STP Nuclear Operating Company South Texas Project Electric.
Generating Station '
P. O. Box 289 Wadsworth,'TX 77483
SUBJECT:
SOUTH TEXAS PROJECT, UNITS 1 AND 2 (STP)'- REVISION TO TECHNICAL SPECIFICATION BASES PAGE B 3/4 2-6 (TAC NOS. MA4900 AND MA4901)
Dear Mr. Cottle:
We are responding to STP Nuclear Operating Company's February 24,1999, letter, which provided an update to Technical Specification (TS) Bases page B 3/4 2-6. The change affects Bases section 3/4.2.5 and clarifies that only three channels are required to be averaged when performing surveillances of T.,, and Pressurizer Pressure Departure from Nucleate Boiling Parameters.
The NRC staff agrees with the proposed change because there is no significant difference between averaging three or four channels for surveillances of T,,, and Pressurizer Pressure for evaluating Departure from Nucleate Boiling Parameters as long as all four channels are within the plant's acceptable limit of tolerance and the averaged three channels represent the j
monitored parameter evenly and fairly.
We are enclosing the revised TS Bases page B 3/4 2-6 that the NRC staff will use to update its copy of the STP Bases. If you have any additional questions regarding this issue, please contact me at (301) 415-1326.
Sincerely, ORIGINAL SIGNED BY Thomas W. Alexion, Project Manager, Section 1 Project Directorate IV & Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation 1
Docket Nos. 50-498 and 50-499
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Enclosure:
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South Texas, Units 1 & 2 cc:
Mr. Cornelius F. O'Keefe Jack R. Newman, Esq.
Senior Resident inspector Morgan, Lewis & Bockius U.S. Nuclear Regulatory Commission 1800 M Street, N.W.
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P. O. Box 910 Washington, DC 20036 5869
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Bay City, TX 77414 '
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Mr. T. H. Cloninger j
i A. Ramirez/C. M. Canady Vice President City of Austin '
Engineering & Technical Services Electric Utility Department STP Nuclear Operating Company 721 Barton Springs Road P. O. Box 289 Austin,TX 78704 Wadsworth,TX 77483 Mr. M. T. Hardt Office of the Governor Mr. W. C. Gunst ATTN: John Howard, Director City Public Service Board Environmental and Natural P. O. Box 1771 Resources Policy San Antonio,TX 78296 P. O. Box 12428 Austin,TX 78711
- Mr. G. E. Vaughn/C. A. Johnson Central Power and Light Company Jon C. Wood P. O. Box 289 Matthews & Branscomb Mail Code: N5012 One Alamo Center Wadsworth,TX 74483 106 S. St. Mary's Street, Suite 700 San Antonio,TX 78205-3692 INPO Records Center Arthur C. Tate, Director 700 Galleria Parkway Division of Compliance & Inspection Atlanta, GA 30339-3064 Bureau of Radiation Control Texas Department of Health Regional Administrator, Region IV 1100 West 49th Street U.S. Nuclear Regulatory Commission Austin,TX 78756 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 -
Jim Calloway Public Utility Commission of Texas D. G.Tecs/R. L. Balcom Electric Industry Analysis Houston Lighting & Power Co.
P. O. Box 13326 P. O. Box 1700 Austin, TX 78711-3326 Houston,TX 77251 Judge, Matagorda County Matagorda County Courthouse i
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.1700 Seventh Street L
Bay City, TX 77414 L
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POWER DISTRIBUTION LIMITS BASES 3/4.2.5 DNB PARAMETERS (Continued) initial FSAR assumptions and have been analytically demonstrated adequate to maintain a minimum DNBR of greater than or equal to the design limit throughout each analyzed transient.
The T., value of 598'F and the pressurizer pressure value of 2189 psig are analytical values.
The readings from at least three channels will be averaged and then adjusted to account for i
measurement uncertainties before comparing with the required limit. The flow requirement (392,300 gpm) includes a measurement uncertainty of 2.8%.
Technical Specification 3.2.5 provides for an attemate minimum measured Reactor Coolant System flow limit consistent with plugging up to 10% of steam generator tubes and Departure from Nucleate Boiling requirements. - When using the attemate minimum flow limit, the T., limit is reduced to 595'F for Reactor Coolant System flow no less than 380,500 gpm.
Setpoint and constant values for OPAT and OTAT are also revised accordingly when this alternate mode of operation is entered.
The RCS flow measurement uncertainty of 2.8% bounds the precision heat balance and the elbow tap Ap measurement methods. The elbow tap Ap measurement uncertainty presumes that elbow tap Ap measurements are obtained from either ODPS or the plant process computer. Based on instrument uncertainty assumptions, RCS flow measurements using either the precision heat balance or the elbow tap Ap measurement methods are to be performed at greater than or equal to 90% RTP at the beginning of a new fuel cycle. The elbow
. tap Ap RCS flow measurement methodology is described in ST-HL-AE 5707, " Proposed Amendment to Technical Specification Table 2.2-1 and 3/4.2.5 for Reactor Coolant System Flow Monitoring - Revised," dated August 6,1997, and in ST-HL-AE-5752, " Amended Response to Request for Additional information on the Proposed Elbow Tap Technical Specification Change (Table 2.2-1 and Section 3/4.2.5)," dated September 18,1997.
The 12-hour periodic surveillance of these parameters through instrument readout is sufficient to ensure that the parameters are restored within their limits following load changes and other expected transient operation.
i SOUTH TEXAS - UNITS 1 & 2 B 3/4 2-6 Unit 1 - Amendment No. 64r97,108 Unit 2 - Amendment No. Ser84,95 Revised by NRC letter dated May 5,1999 i