ML20072J694
| ML20072J694 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/28/1983 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20072J688 | List: |
| References | |
| TVA-SQN-TS-42, NUDOCS 8303300131 | |
| Download: ML20072J694 (4) | |
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!!NCLOSURE 1 PROPOSED TECHNICAL SPECIFICATIONS FOR SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 TVA-SQN-TS-42 UHI Accumulator Water Level Setpoint and Tolerances 8303300131 830328 PDR ADOCK 05000327 P
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EMERGENCY CORE COOLING SYSTEMS (ECCS) l SURVEILLANCE REQUIREMENTS (Continued) b.
At least once per 31 days and within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after each solution volume increase-of-greater than or equal to 1% of tank volume by verifying the baron concentration of the solution in the water-filled accumulator.
c.
At least once per 18 months by:
1.
Verifying that each accumulator isolation valve closes automa-tically when the water level in the water-filled accumulator is 82.1 15.6 inches above the tank vendor working line.
This corresponds to 87.1 15.6 inches when corrected for the mass of cover gas.
2.
Verifying that the total dissolved nitrogen and air in the water-filled accumulator is less than 80 SCF per 1800 cubic
-5 feet of water (equivalent to 5 x 10 pounds nitrogen per pounds water).
d.
At least once per 5 years by removing the me' brane installed between m
the wa.ter-filled and nitrogen bearing accumulators and verifying that the removed membrane bursts at a differential pressure of 40 + 10 psi.
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l 3/4 5-4 SEQUOYAH - UNIT 1
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EMERGENCYCORECOOLINGSYhTEMS(ECCS)
SURVEILLANCE REQUIREMENTS (Continued) b.
At least once per 31 days and within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after each solution volume increase-of-greatem than or equal to 1% of tank volume by verifying the boron concentration of the solution in the water-filled accumulator.
c.
At least once per 18 months by:
l.
Verifying that each accdnulator isolation valve closes automa-tically when the water level in the water-filled accumulator is 82.1 15.6 inches above the tank vendor working line.
This corresponds to 87.1 15.6 inches wher. corrected for the mass of cover gas.
2.
Verifying that the total dissolved nitrogen and air in the water-filled accumulator is less than 80 SCF per 1800 cubic
-5 feet of water (equivalent to 5 x 10 pounds nitrogen per pounds water).
d.
At least once per 5 years by removing the membrane installed between the wa.ter-filled and nitrogen bearing accumulators and verifying that the removed membrane bursts at a differential pressure of 40 + 10 psi.
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ENCLOSURE 2 JUSTIFICATION FOR PROPOSED 'IECHNICAL SPECIFICATION SEQUOYAH NUE EAR PLANT UNITS 1 AND 2
'1VA-SQN-TS-42 Westinghouse was requested to investigate the possibility of expanding the volumetric delivery. limits required of the upper head inj ection (UHI) system. Westinghouse subsequently reviewed the Sequoyah PSAR ECCS performance analysis and performed a sensitivity study to evaluate a widened set of limits on the allowable UHI water volume delivered for both units (refer to attachment 1).
Based on the review of the ECCS performance analyses and the sensitivity study, Westinghouse has provided documentation that an additional 50 cubic feet was calculated as acceptable to be included in the upper limit of the required Sequoyah UHI volumetric delivery envelop (from 1055 cubic feet to 1105 cubic f eet).
As a result. Westinghouse has stated that the setpoint on the UHI accumu-lator diff erential pressure level switch can be revised, to achieve opt imiz a t ion, to 82.1 inches above the tank vendor working line (87.1 inches when corrected for the mass of cover gas). The corresponding maximum allowable level switch tolerance will be f 5.6 inches of water c ol umn.
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ATTACHIEINT 1 WESTINGHOUSE NUCLEAR SAFETY EVALUATION J
The limiting case break in the 1978 URI Evaluation Model ECCS analysis
.6 reak with imperfect presented la the Sequoyah FSAR is the C
=
D mixing of UHI water assumed in the vessel upper head. Compliance with regulatory limits were achieved for this case by reducing the allowable core peaking f actor (FQ) to 2.237; no margin exists for this case.
Minimizing the volume of UHI water delivered is conservative for imperf ect mixing UHI LOCA cases. Since no margin exists, the lower bound value for UHI water volume delivery must remain at 900 cubic feet, the value employed in the FSAR C = 0.6 DECLG imperfect mixing case.
D A complete spectrum of perfect mixing cases was analyzed for the Sequoyah FSAR. The limiting case with perfect mixing of UHI water assumed in the vessel upper head was the C = 0.6 DECLG. The calculated peak clad tempera-p ture (PCT) for this case is 2111 F at an FQ of 2.32 with a UHI delivered water volume of 1053 cubic feet. Using sensitivities appropriate to UHI plant perfect mixing cases, tradeoffa can be made among various input assumptions to justify increasing the maximum allowable UHI delivered water volume. Maximizing the value of UHI water delivered is conservative for perf ect mixing UHI LOCA analyses. Consider the net PCI impact of the following changes to C = 0.6 DECLG perfect mixing case:
D I.
Increase UHI delivered water volume from 1053 to 1105 cubic feet:
I 52 cf 2.1 F PCT l
cf UHI water if 110*F PCT increase i
II.
Reduce FQ value to 2.237:
(2.32 - 2.237) 11*F PCT
.01 AFQ 1 90*F PCT decrease III. Remove 65 *F in pellet temperature uncertainty, as approved by NRC:
8 (65 F pellet T) 52 F PCT Of 0*F PCI decrease 165*F pellet T 2
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~1 By putting tbo liciting parfoot cizias ecss from ths Scqtoyah FSAR en ths same core input basis as the g =ivered water volume to 1105 cubic feet is 0.6 DECLG imperf ect mixing case, the PCI impact of increasing the UHI del offset, and the net PCT effect becomes nearly zero. Therefore, significant PCT margin remains to the regulatory ifnit of 2200*F for the CD = 0.6 0.6 imperfect mixing case remains perfect mixing case, and the C
=
limiting. Given that a Techni!al Specification PQ value of 2.237 is in force UBI delivered water volume limits of 900 cubic feet (minimum) and 1105 cubic feet (maximum) may be applied to the Sequoyah units in defining the UHI level switch repeatability criterion.
The FSAR ECCS performance analysis was extended when several cases were analyzed for Sequoyah Unit 1, Cycle 2 during 1982 using the 1981 UHI evaluation modes.
Imperf ect mixing cases therein were again based on the UHI water delivered volume of 900 cubic feet while the C per' ect mixing case analyzed amployed a UHI delivered waker vo.8 DECLG 0
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f lume of 1049 cubic feet, and gave a calculated PCT of 1982*F.
It is clear f rom the sensitivity of PCT to delivered UHI water volume that increasing the UHI water delivery upper bound to 1105 cubic feet is acceptable fer the perfect mixing case analyzed because a large PCT margin remains.
It is believed that the 1105 cubic f eet water delivery upper limit can be accommodated by all perfect mixing DECLG break cases under the 1981 UHI evaluation model without exceeding the 2200*F regulatory limit on PCT at FQ = 2.237.
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