ML20206E155

Application for Amends to Licenses DPR-77 & DPR-79, Consisting of TS Change 99-04, Auxiliary Feedwater Suction Pressure Low Surveillance Frequency Rev. Change Deletes Surveillance

ML20206E155
Person / Time
Site:	Sequoyah
Issue date:	04/29/1999
From:	Salas P TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20206E158	List: ML20206E155 ML20206E161
References
NUDOCS 9905050035
Download: ML20206E155 (7)

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Tennessee VaHoy Authonty. Post Office Box 2000. Soddy-Daisy. Tennessee 37379 l

April 29, 1999 TVA-SQN-TS-99-04 10 CFR 50.90 U.S. Nuclear Regulatory Cominission ATTN: Document Control Desk Washington, D. C. 20555 Gentlemen:

In the Matter of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 SEQUOYAH NUCLEAR PLANT (SQN) - UNITS 1 AND 2 - TECHNICAL SPECIFICATION (TS) CHANGE NO. 99-04, " AUXILIARY FEEDWATER

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(AFW) SUCTION PRESSURE LOW SURVEILLANCE FREQUENCY REVISION" J i

In accordance with the provisions of 10 CFR 50.4 and 50.90, TVA is submitting a request for an amendment to SQN's ]

1 licenses DPR-77 and 79 to change the TSs for Units 1 and 2.

The proposed change will delete the AFW suction pressure low channel functional test surveillance.

TVA has determined that there are no significant hazards considerations associated with the proposed change and that i the change is exempt from environmental review pursuant to j the provisions of 10 CFR 51.22 (c) (9) . The SON Plant i Operations Review Committee and the SQN Nuclear Safety Review l Board have reviewed this proposed change and determined that operation of SON Units 1 and 2, in accordance with the ,

l proposed change, will not endanger the health and safety of l the public. Additionally, in accordance with j 10 CFR 50. 91 (c) (1) , TVA is sending a copy of this letter to the Tennessee State Department of Public Health. })Ogo s ' ', '50 Enclosure'l'to this letter provides the description and evaluation of the proposed change. This includes TVA's determination that the proposed change does not involve a significant hazards consideration, and is exempt from environmental review. Enclosure 2 contains copies of the 9905050035 990429 PDR ADOCK 05000327; P. PDR j n .

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l-l U.S. Nuclear Regulatory Commission

!- 'Page 2 April 29, 1999 appropriate TS pages from Units 1 and 2 marked-up to show the proposed change. Enclosure 3 forwards the revised TS pages ,

for Units 1 and 2 which incorporate the proposed change. ]

TVA requests.that

this TS change be considered a cost beneficial licensing action. Deletion of the monthly AFW suction pressure. low channel functional surveillance is j

j estimated to save TThi $440,000 in operating and maintenance i (O&M) cost over the remaining life of the plant. This O&M savings includes manpower requirements. In addition, the l unavailability of the AFW system will decrease by approximately 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> per month per unit by this proposed change. Note that in terms of regulatory precedence,.

standard TSs (NUREG-1431) show a 92-day surveillance {

frequency as a' matter of plant specific basis. Further, both {

McGuire and Catawba _ Nuclear Stations, which are peers to SQN, I have TSs'that. require only an 18-month calibration frequency for the AFW~ system suction pressure low function.

.TVA requests that the revised TS be made effective within 45_ days of NRC approval. If you have any questions about this change, please telephone me at (423) 843-7170 or J. D. I Smith at (423) 843-6672.

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! Sincerely,

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-Licensi.g and Industry Affairs Manager i 1 t

' i' Subscribed'pd sworn to fore ge thisd[he day of '

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My Commission Expires October 9, 2002 l

l Enclosures cc: See page 3 1

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.. Nuclear Regulatory Commission E ;U.S.

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A,pril 29, 1999-l'

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'cc. (Enclosures) :

Mr. R. W. Hernan,. Project Manager

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, Nuclear Regulatory Commission One White Flint, North-I 11555lRockville Pike l Rockville, Maryland. 20852-2739 Mr.; Michael H. Mobley, Director (w/o Enclosures)

Division'of Radiological Health Third Floor L&C Annex i' 401 Church Street ,

Nashville, Tennessee.37243-1532 l .NRC Resident

'Sequoyah Nuclear Plant 2600:Igou Ferry Road Soddy-Daisy, Tennessee 37384-3624 Regional Administrator E U'S. Nuclear Regulatory Commission

Region II l

Atlanta Federal Center

! 61 Forsyth St.,1SW,' Suite 23T85 Atlanta, Georgia 30303-3415 L

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r ENCLOSURE 1 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT (SQN)

UNITS 1 AND 2 DOCKET NOS. 327 AND 328 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE TS-99-04 DESCRIPTION AND EVALUATION OF THE PROPOSED CHANGE  !

I. DESCRIPTION OF THE PROPOSED CHANGE TVA proposes to modify the SQN Units 1 and 2 TSs by deleting the monthly surveillance requirement (SR) for the auxiliary feedwater (AFW) suction pressure low channel functional test in Table 4.3-2 (SR 4.3.2.1.1.6.g).

II. REASON FOR THE PROPOSED CHANGE This change improves the availability of the AFW system.

Performance of the AFW pressure switch channel functional test at the present interval decreases the availability of the AFW system approximately 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> per month per unit. '

During performance of the surveillance, the essential raw cooling water (ERCW) valves are rendered inoperable, power to the valves is removed to ensure that raw water will not inadvertently be injected into the steam generators. This requires the system to be declared inoperable. Our analysis of the performance history revealed that the monthly functional test does not provide an increased assurance of operability that justifies the system unavailability it creates. Additionally the TS surveillance revision is estimated to save SQN approximately $440,000 over the remaining life of the plant.

III. SAFETY ANALYSIS The AFW system supplies, in the event of a loss of the main feedwater supply, sufficient feedwater to the steam generators to remove primary system stored and residual core energy.

Engineered Safety Feature (ESP) standards are met for the AFW system except for the condensate water supply, which is backed up by the ERCW system. The ESF grade portion of the system is designed for seismic conditions and single failure requirements, including consideration that the rupture of a feedwater line could be the initiating event.

AFW will provide the required flow to two or more steam El-1

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generators regardless of any single active or passive L failure in the long term.

l The preferred source of water for the AFW pumps are the nonseismic condensate storage tank (CSTs), one for each unit. As an unlimited backup (Seismic Category I) water supply, a separate trained ERCW system header feeds each electric pump. The turbine-driven AFW pump receives backup (Seismic Category I) water from both Train A and B ERCW headers. The ERCW supply can be remote-manually aligned based on CST level or automatically on a two-out-of-three low-pressure signal in the condensate suction line.

The pressure signal is generated from pressure switches on the suction of the AFW pumps. The manufacturer and model number for the motor-driven AFW pump suction pressure switches are ASCO Tripoint/SB31AKR/TD30A32R. The manufacturer and model number for the turbine-driven AFW pump suction pressure switches are Static-O-Ring /

12N6-BB45-NX-C1A-JJTTX12. There are three switches per pump or nine per unit.

In accordance with the TSs, the pressure switches for the AFW pumps are functionally tested every month and a

! channel calibration is performed once every 18 months. By l analysis, the calculation and the setpoint and scaling i

documents support a calibration frequency of 18 months plus an allowable 25 percent extension or 22.5 months for each of the AFW pressure switches.

A review of the monthly channel functional test data (since 1991) of the motor-driven AEW pump ASCO pressure switches reveals the switches actuated upon demand with no failures. Additionally, a review of the 18-month channel calibration test data (since 1991) was performed on the Units 1 and 2. motor-driven AFW pump pressure switches.

Two test deficiencies occurred during a channel calibration performance in 1995 when two different switches drifted out of tolerance low. The switches were recalibrated and returned to service. The pressure switches would have performed their safety function within the safety-limits even with the out of tolerance condition. Performances since that time have been satisfactory, with no additional deficiencies.

A review of the monthly channel functional test data (since 1991) of the turbine-driven AFW pump pressure switches shows that the pressure. switches responded upon ,

demand without any failures. Additionally, a review of the turbine-driven AFW pump suction pressure switches channel calibrations (since 1991) identified two test l

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deficiencies involving two different switches. One switch drifted out of tolerance low in 1992 and another in 1994.

• ' ' The switches were recalibrated and returned to service with no subsequent deficiencies. The pressure switches l

would have performed their safety function within the l safety limits even with the out of tolerance conditions.

Performances since that time have been satisfactory, with no additional deficiencies.

The above information illustrates that the monthly channel

functional surveillances are routinely met and that the 18-month channel calibration surveillances infrequently result in an out of tolerance condition. However, due to i the potential to inject untreated coolant water (ERCW) into the steam generators, the ERCW supply valves are rendered inoperable during the monthly surveillance test.

As previously described, this action results in an increase of approximately 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> per month per unit in the unavailability of the AEW system. Given the reliability of the pressure switches and the low probability of a seismic event occurring while relying on AFW, we believe the overall safety of SON is improved by eliminating the monthly AFW pressure switch channel functional test and relying on the 18-month channel calibration to ensure safety system performance. It should also be pointed out that these switches are in the scope of the Maintenance Rule Program and as such, any degraded performance will be evaluated and corrective actions established as appropriate.

IV. NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION TVA has concluded that operation of SON Units 1 and 2, in accordance with the proposed change to the technical specifications does not involve a significant hazards ,

consideration. TVA's conclusion is based on its l evaluation, in accordance with 10 CFR 50. 91(a) (1) , of the three standards set forth in 10 CFR 50.92(c).

A. The proposed amendment dosa not involve a significant  ;

increase in the probability or consequences of an I accident previously evaluated.

The probability of occurrence or the consequences for

an accident is not increased by this request. The l proposal to delete the monthly channel functional test l for the auxiliary feedwater (AFW) suction pressure low functions does not alter the way any structure, system or component functions, does not modify the manner in which the plant is operated, and reduces equipment out-of-service time. This request does not degrade the ability of AFW to perform its intended function.

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I 0 Therefore, the pressure switches will be available to F perform their intended function.

B. The proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.

l A possibility for an accident or malfunction of a i different type than any evaluated previously in SON's FSAR is not created. The proposal does not alter the way any structure, system or component functions and does not modify the manner in which the plant is operated. Therefore, the possibility of a new or different kind of accident previously evaluated is not created by the proposed change to delete the monthly functional test of the AFW pressure switches.

C. The proposed amendment does not involve a significant reduction in a margin of safety.

The' margin of safety has not been reduced since the test methodologies are not being changed. Increasing the surveillance interval does not change the results of accident analysis by this request. The proposed change to delete the AFW system pressure low channel functional test does not involve a significant reduction in the margin of safety. The new frequency will not reduce the reliability of the system and increases overall system availability. Therefore, changing the frequency of the surveillance does not reduce the margin of safety.

V. ENVIRONMENTAL IMPACT CONSIDERATION The proposed change does not involve a significant hazards consideration, a significant change in the types of or significant increase in the amounts of any L effluents that may be released offsite, or a significant increase in individual or cumulative occupational radiation exposure. Therefore, the proposed change meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22 (c) (9) . l Therefore, pursuant to 10 CFR 51.22 (b), an environmental assessment of the proposed change is not l required.

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