ML20101N406
| ML20101N406 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/28/1996 |
| From: | Shell R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9604080368 | |
| Download: ML20101N406 (5) | |
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Tennessee Valley Authonty Post Othce Box 2000. Soddy-Daisy Tennessee 37379 i
l March 28,1996 i
U.S. Nuclear Regulatory Commission ATTN: Document Control Desk l
Washington, D.C. 20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SON) - SUPPLEMENTAL INFORMATION FOR TECHNICAL SPECIFICATION (TS1 CHANGE 92-07 The enclosure to this submittal provides information requested by NRC during a telephone conversation held between TVA and NRC personnel on February 20,1996.
l This information is related to TS Change Request 92-07 and provides the SON methodology for determining the reactor coolant system loss-of-flow reactor trip setpoint. The associated flow correlation constants for the SON elbow tap flow transmitters are also included.
Please direct questions concerning this issue to Keith Weller at (423) 843-7527.
Sincerely, e
l R. H. Shell Manager SON Site Licensing Enclosure cc: See page 2 N
N 9604080368 960328
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PDR ADOCK 05000327 P
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0 U.S. Nuclear Regulatory Commission Page 2 March 28,1996 i
l cc (Enclosure):
Mr. D. E. LaBargo, Project Manager Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 i
NRC Resident inspector Sequoyah Nuclear Plant 1
2600 Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator U.S. Nuclear Regulatory Commission Region 11 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711 1
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SEQUOYAH NUCLEAR PLANT (SON)
REACTOR COOLANT SYSTEM (RCS) FLOW MEASUREMENT NRC Question Describe the SON methodology for setting the RCS flow transmitter / indication and the RCS low flow reactor trip setpoint, if any "K" factors are involved, determine what the "K" values are and state how they were determined.
l TVA SON Resoonse The effects of a low leakage core pattern, elimination of bypass resistance temperature detectors, and hot leg streaming results in hot leg measurement difficulties in a precision calorimetric. Therefore, SON utilizes a method of comparing RCS !oop flow element elbow tap differential pressures to determine RCS flow rate, as recommended by j
Westinghouse Electric Corporation. Westinghouse data of elbow taps indicated that the differential pressures were repeatable and were not significantly impacted by corrosion or chemical buildup from cycle to cycle (Reference 1).
The methodology consists of:
- 1. The initial baseline Cycle 1 calorimetric from the start-up test program is used to j
determine a "K" value where K = O/(DP)". These "K" values are listed in 1 and 2-SI-SXX-068-155.0and are attached.
- 2. This "K" value is used to determine the full scale span of the 0-110% flow instrument loop where 100% flow is the Technical Specification (TS) Table 3.2.1 required flow (378,400 gallons per minute [gpm] / 4 loops = 94,600 gpm per loop). This TS Table 3.2.1 flow contains a 3.5% measumment uncertainty.
- 3. WCAP-11239, Revision 6 provides uncettainties and allowable values for the loss of flow reactor trip setpoint based on RCS elbow tap differential pressure comparisons.
The safety analysis limit is 86.9% of the 91,400 gpm design flow, the TS allowable value is 89.4% of design flow and the nominal setpoint is 90% of design flow. TS Change 92-07 changes the allowable value to 89.6% of design flow. The flow measurement uncertainty of 3.5% is not included in these TS Table 2.2.1 requirements.
- 4. Paragraph 2 above indicates that 100% indicated flow is 94,600 gpm or 3.5% above the design flow of 91,400 gpm. This allows the reactor trip to occur at 90%
indicated flow or 85,140 gpm. This results in a conservative high setting of the trip l
setpoint since the 100% indicated flow is 3.5% above design flow. The TS required trip setpoint is 90% of 91,400 gpm or 82,260 gpm.
- 5. The allowable value for reactor trip (including the more restrictive TS Change 92-07 requirements)is 89.6% of 91,400 gpm or 81,894 gpm.
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References
- 1. Westinghouse letter TVA-91-349 to TVA dated November 6,1991 (B25 911114 251)
- 2. TS Tables 3.2.1 and 2.2.1
- 3. WCAP-11239," Westinghouse Setpoint Methodology for Protection Systems, Sequoyah Units 1 and 2, Egale-21 Version", Revision 6, dated December 1991 4.1 and 2-SI-SXX-068-155.0, Appendix A, Data Sheet A-4 5.10 CFR 50.59 Safety Assessment for SON Unit 2 channel calibration procedures for the following:
2-SI-ICC-068-06 A.1, R1 2-SI-ICC-068-48 A.1, R1 2-SI-ICC-068-06B.2, R1 2-SI-ICC-068-48B.2, R1 2-SI-ICC-068-06D.3, R1 2-SI-lCC-068-48D.3, R1 2-SI-ICC-068-29A.1, R1 2-SI-ICC-068-71 A.1, R1 2-SI-lCC-068 298.2, R1 2-SI-ICC-068-71 B.2, R1 2-SI-ICC-068-29D.3, R1.
2-SI-ICC-068-71 D.3, R1 i
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UNIT 1 ELBOW TAP FULL SCALE AP SPAN MMI -
FLOW 1 FT TEST POINT COEFFICIENT FULL SCALE AP (K)
DESCRIPTION
("H O) 2 6A
_ F-414 5679.10 Loop 1 RCS Flow 335.74 6B F-415 5590.30 Loop 1 RCS Flow 346.50 6D F-416 5545.83 Loop 1 RCS Flow 352.07 29A F-424 5626.24 Loop 2 RCS Flow 342.08 298 F-425 -
5505.13 Loop 2 RCS Flow 357.30 29D F-426 5333.06 Loop 2 RCS Flow 380.73 48A F-434 5493.91 Loop 3 RCS Flow 358.76 48B F-435 5493.04 Loop 3 RCS Flow 358.87 48D F 436 5459.96 Loop 3 RCS Flow 363.24 71A F-444 5117.16 Loop 4 RCS Flow 413.53 71B F-445 5668.62 Loop 4 RCS Flow 336.99 71D F-446 5582.65-Loop 4 RCS Flow 347.45 UNIT 2 ELBOW TAP FULL SCALE AP SPAN MMI FLOW 2 FT TEST POINT COEFFICIENT FULL SCALE AP (K)
DESCRIPTION
("H O) 2 6A F-414 5486.41 Loop 1 RCS Flow 359.74 6B F-415 5564.43 Loop 1 RCS Flow 349.73 6D F-416 5424.51 Loop 1 RCS Flow 368.00 29A F-424 5317.59 Loop 2 RCS Flow 382.95 29B F-425 5201.25 Loop 2 RCS Flow 400.27 29D F-426 5409.51 Loop 2 RCS Flow 370.04 48A F-434 5623.24 Loop 3 RCS Flow 342.45 48B F-435 5422.28 Loop 3 RCS Flow 368.30 48D F-436 5236.38 Loop 3 RCS Flow 394.92 71A F-444 5417.06 Loop 4 RCS Flow 369.01
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71B F-445 5421.93 Loop 4 RCS Flow 368.35 71D F-446 5591.30 Loop 4 RCS Flow 346.37 u