ML20248G359
| ML20248G359 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/04/1989 |
| From: | Michael Ray TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-61835, TAC-61836, TAC-R00385, TAC-R00479, TAC-R00480, NUDOCS 8910100212 | |
| Download: ML20248G359 (6) | |
Text
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5 TENNESSEE VALLEY AUTHORITY CH ATTANOOGA, TENNESSEE 37401 5N 1578 Lookout Place 00T 041989 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
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Docket No. 50-328 Tennessee Valley Authority SEQUOYAH NUCLEAR PLANT (SQN) UNIT 2 - REQUEST FOR RELIEF FROM AMERICAN SOCIETY 0F MECHANICAL ENGINEERS (ASME) BOILER AND PRESSURE VESSEL CODE, SECTION XI -
STROKE TIME TESTING FOR TH0 BORON INJECTION TANK (BIT) DISCHARGE VALVES
References:
1.
NRC letter to TVA dated October 23, 1987, " Request for Relief from ASME Boiler and Pressure Vessel Code,Section XI, Inservice Testing Program (TAC 61835, 61836)"
2.
NRC lett u to TVA dated January 19, 1988, " Request for Relief from ASME Boiler and Pressure Vessel Code,Section XI, Inservice Testing Program (TAC 61835, 61836)"
3.
NRC letter to TVA dated August 18, 1988, " Request for Relief from ASME Boiler and Pressure Vessel Code,Section XI, Inservice Testing Program - Four Hydrogen Analyzer Sampling Valves GAC R00385) - Sequoyah Nuclear Plant, Unit 1" 4.
NRC letter to TVA dated September 15,1988, " Request for Relief from ASME Boiler and Pressure Vessel Code,Section XI, Inservice Testing Program - Ultrasonic Flow Measurement (TAC 61835/61836) - Sequoyah Nuclear Plant, Units 1 and 2" 5.
NRC letter to TVA dated March 23, 1989, " Relief from ASME Boiler and Pressure Vessel Code,Section XI, Inservice Testing Program - Boric Acid Transfer Pump Flow Rate Measurement (TAC R00479/R00480) - Sequoyah Nuclear Plant, Units 1 and 2" By References 1 through 5, NRC transmitted to TVA safety evaluation reports (SERs) for SQN's in-service testing program (IST) for pumps and valves. These SERs granted relief from specific requirements of the ASME Section XI Code and provided regulatory approval of SQN's IST program.
Pursuant to 10 CFR 50.55a(a)(3), TVA is requesting relief from the requirements of ASME Section XI IWV-3411 as described in Enclosure 1.
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An Equal Opportunity Employer i
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' U.S. Nuclear Regulatory Commission 00T 04 W
" discusses the basis for this request for relief from the quarterly stroke test requirement for two parallel safety injection valves located on the Unit 2 BIT discharge line (FCV-63-25 and FCV-63-26).- Expertence has shown that exercising these valves results in an increase in the total leakage from the reactor coolant system and a reduction in the boric acid concentration within the BIT. TVA believes this.is caused by leakage through check valves between the reactor coolant system and the BIT.
Dilution of the BIT is undesirable in that the plant must enter a. limiting condition for operation (3.5.4.1) while in Modes 1, 2, or 3 and comply with a one-hour action for restoring BIT boron concentration. Failure to restore boron concentration within this timeframe requires a unit shutdown.
TVA is requesting that quarterly testing be suspended until the suspect check valves can be repaired. contains TVA's commitment for completing this repair prior to startup from the Unit 2 Cycle 4 refueling outage, which is projected to begin in October 1990.
The next scheduled stroke test for SQN's BIT outlet valves is October 4, 1989, with the 1.25 extension due date of October 27, 1989. TVA requests expedient NRC review of the proposed exemption to support the October 27.-1989, deadline.
Please direct questions concerning this issue to D. V. Goodin at (615) 843-7734.
Very truly yours, TENNESSEE VALLEY AUTHORITY L
1 Ma ger, N 1 r Licensing and Regula ory Affairs Enclosures cc: See page 3
I
- . I U.S. Nuclear Regulatory Commission 00T 04 289
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cc (Enclosures):
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-Ms. S. C. Black, Assistant Director for. Projects.
'TVA Projects Division U.S. Nuclear Regulatory Commission One White Flint,. North 11555 Rockville Pike.
'Rockville, Maryltnd ~20852 Mr. B. A.' Wilson, Assistant Director for Inspection Programs TVA Projects Division F
U.S.' Nuclear Regulatory Commission Region II-101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NRC Resident' Inspector
- Sequoyah Nuclear Plant 2600 Igou Ferry. Road Soddy Daisy, Tennessee 37379 i
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i-ENCLOSURE 1 Unit:
2.
1 System:
Safety Injection Valves:
FCV-63-25, FCV-63-26 Class:
2 Function:
Open to allow safety injection flow through the boron injection tank (BIT) to the reactor coolant system (RCS)
Con Requirement: Paragraph IWV-3411 of the 1977 Edition through Winter 1978 Addenda of Section XI of the American Society of Mechanical Engineers (ASME).Boller and Pressure Vessel Code states:
'" Category A and B valves shall be exercised at least once every three months."
)
I Basis for Relief:
Following the last two operations of these valves, the boric acid concentration in the BIT decreased below that required by plant technical specifications (TSs), and the total leakage rate from the RCS increased from 0.9 to 1.4 gallons per minute.
Based upon these indications, TVA believes a leakage path exists through two of the primary cold leg safety injection check valves and the BIT discharge secondary check valve (63-581).
When either of the BIT discharge valves is exercised, a leakage path is established through the valve to the BIT. The BIT discharge valves allow sufficient leakage, when exposed to the pressure created by the leaking check valves, to permit RCS water to dilute the BIT concentration and provide a detectable RCS leak. Over about a two-week period, these BIT discharge valves appear to seat sufficiently to stop this leakage.
The necessary corrective action for this situation is to repair the leaking check valves between the RCS and the BIT. This repair will require bringing the unit to cold shutdown, depressurizing the RCS, and draining the RCS to mid-loop operation.
To allow the unit to continue operation until the next scheduled refueling outage, TVA proposes to discontinue the quarterly testing of the BIT discharge valves until the check valve repair is completed. The BIT discharge valves have been full-stroke exercised and stroke-time tested on a quarterly basis for approximately eight years.
Past test data shows that these valves are very reliable and that no failures have been recorded for these valves.
Based upon their past test performance, TVA feels confident that these valves would perform properly when called upon.
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.-Alternate H' #
Testing:
- None..- Suspend valve exercising and stroke-time testing of the BIT discharge' valves unt11' repair of the primary and secondary.
- cold' leg safety injection check valves has'been completed.
Frequency.for
. Alternate:
Testing:
The. repair of'the cold leg safety-injection check valves will be completed no later than the next. refueling outage scheduled-to begin in October 1990.
The BIT. discharge; valves'will be full-stroke exercised and. stroke-time tested prior.to the-return of the unit to service following' the: repair of' the' RCS safety injection cold leg check valves. Quarterly-valve testing will.
be resumed at this time.
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ENCLOSURE 2 TVA Commitments 1.
TVA will-repair suspect check valves (63-581,63-588, and 63-589) within the boron _ injection flow path in order to eliminate leakage from the RCS
>into the safety injection system.
This rep'ir will_ occur prior to startup a
from the Unit 2 Cycle 4 refueling outage.
2.
TVA will resume quarterly. stroke-time testing of the BIT discharge' valves (FCV-63-25 and FCV-63-26).following the Unit 2 Cycle 4 refueling outage in-accordance with the scheduled performance of Surveillance Instruction 166.1, " Full Stroking of Category 'A' and 'B' Valves During Operation."
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