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Proposed Tech Specs,Revising Surveillance Requirement Tolerance for Low Level Isolation of Upper Head Injection Sys
	ML20214J967
Person / Time
Site:	Sequoyah
Issue date:	07/24/1986
From:	Watson M; TENNESSEE VALLEY AUTHORITY
To:	;
Shared Package
ML20214J962	List: ML20214J960; ML20214J967; ML20214J981;
References
	NUDOCS 8608150252
	Download: ML20214J967 (12)
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EMERGENCY CORE COOLING SYSTEMS (ECCS)

SURVEILLANCE REQUIREMENTS (Continued)

b. At least once per 31 days and within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months after each solution volume increase-of-greater than or equal to 1% of tank volume by verifying the baron concentration of the solution in thw water-filled accumulator. ,

c. At least once per 18 months by:

1. Verifying that each accumulator isolation salve closes automa-tically when the water level in the water-filled accumulator is 30 82.1 ih4r inches above the tank vendor working line. This corresponds to 87.1 +6Tfr inches when corrected for the mass of cover gas. - 2.0

2. Verifying that the total dissolved nitrogen and air in the water-f.illed accumulator is less than 80 SCF per 1800 cubic feet of water (equivalent to 5 x 10 -5 pounds nitrogen per pounds water). -

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d. At least once per 5 years by removihg the membrane installed between the water-filled and nitrogen bearing accumulators and verifying that the removed membrane bursts at a differential pressure of 40 f,10 psi.

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f l EMERGENCY CORE COOLING SYSTEMS (ECCS)

SURVEILLANCE REOUIREMENTS (Continued)

b. At least once per 31 days and within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months after each solution volume increase-of-greater than or equal to 1% of tank volurg by verifying the boron 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-when the water level in the water-filled accumulator is tically$$

82.1+d inches abo'y he tank vendor working line. This corresponds to 87.1 + 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 feet of water (equivalent to 5 x 10 -5 pounds nitrogen per pounds water).

d. At least once per 5 years by removing the sembrane installed between the water-filled and nitrogen bearing accumulators 'and verifying that the removed membrane bursts at a differential pressure of 40 + 10 psi.

3/4 5-4 SEQUOYAH - UNIT 2

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ENCLOSURE 2 Proposed Technical Specification Change SEQUOYAH NUCLEAR PLANT Docket Nos. 50-327. -328 (TVA SQN TS 74)

Description and Justification for Proposed Change to UNI Level Switch

, Setpoint Tolerance l

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Attcchment Page 1 of 3 Description of Change This proposed change for Sequoyah Nuclear Plant Technical Specifications Units 1 and 2 will decrease the tolerance for upper head injection (UNI) isolation valve closure in Surveillance Requirement 4.5.1.2.c.1 from i 5.6 inches to i 2.0 inches. (See attached marked up pages.)

Reason for Change In order to satisfy the actuation requirements currently required by technical specifications, valve closure must be verified by static timing of the valves. These valves must be verified to stroke close in 3.5 seconds 1 0.05 seconds. TVA has experienced difficulty in meeting this exacting tolerance for closure of these valves, strictly due to the magnitude of the numbers as compared with the size of the valves themselves. In response to these difficulties, TVA requested Westinghouse to perform an evaluation to provide a relaxed actuation timing band width, while maintaining the current technical specification limits for volume delivery.

Justification for Change The justification for this change is largely provided by the Westinghouse evaluation and Nuclear Safety Evaluation Checklist (reference 1). In this evaluation, Westinghouse has concluded that the tolerance for valve closure may be increased from 0.05 seconds to 0.14 seconds without impacting the amount of water delivered to the system during UHI system actuation.

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Att0chment Page 2 of 3 The change does affect the tolerance figures for valve actuation.

Recently the level switches (Barton 288A) for automatic isolation of UNI were replaced with Static "0" Ring" (SOR) switches in an effort to improve reliability of the system.

The replacement of these switches was a result of excessive drift problems the plant experienced with the switches installed at the time (Barton 288A). TVA performed a special test, STEAR-INST-83-13 (reference 2), to determine the reliability of a prototype SOR model 103 dp switch. This test consisted of installing a SOR switch on unit 2, which was originally calibrated in August 1983. The switch calibration was checked monthly for a period of 7 months. During this period, the switch setpoint was never adjusted and did not drift outside the desired tolerance (see Table 1). As a result of this STEAR, the Director of Nuclear Services for TVA Nuclear Power recommended to the Sequoyah Site Director the replacement of the Barton 288A switches with the SOR switches for the UNI system (reference 3).

TVA is aware of the problems identified recently with the SOR switches by IE Bulletin 86-002. Sequoyah is currently preparing a response to the bullotin for safety-related applications of these SOR 102 and 103 dp switches. TVA will monitor nuclear industry efforts to alleviate the concerns with the SOR sw'.tches and will implement the appropriate

! corrective actions as they are identified.

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Att:chment Page 3 of 3 It is also of note that Sequoyah presently is in the process of pursuing analysis from Westinghouse to justify removal of the UHI system from the plant. This analysis and removal has been accomplished by a similar Westinghouse faellity (Duke Power McGuire Nuclear Station). Watts Bar, a sister TVA plant, is considering actively pursuing the removal of this sytem by obtaining similar analysis from Westinghouse.

References

1. Letter from Westinghouse to TVA " Hydraulic Isolation Valve Static Timing Tolerance Increase"

2. Sequoyah Nuclear Plant, Special Test, SQ-STEAR-INST-83-13

" Reliability Test of Static-0-Ring (SOR) Level Switch for UHI Water Accumulator" Revision 0 approved August 23, 1983.

3. TVA memorandum from H. L. Abercrombie to C. C. Mason dated June 29, 1984, "Sequoyah Nuclear Plant - Special Test Procedure SQ-STEAR-INST-83 Reliability Test of Static-0-Ring (SOR) Level Switch for UNI Water Accumulator" (L28 840527 808)

FCM:SFH 7/24/86 0194h t

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Table 1 Susumary of As Found As lef t Data From STEAR-INST-83-13 Desired Setpoint As Found As Left Date (in W.C.) (in W.C.) (in W.C.)

8/24/83 141.4 1 2.0 Original calibration 141.4 9/22/83 141.12 141.12

10/31/83 141.59 141.59 11/28/83 141.97 141.97 12/28/83 141.65 141.65 01/23/84 140.2 140.2 02/21/84 142.3 142.3 03/20/84 141.40 141.40

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SlJL 25 '86 13:42 SEC MNC P.2

, SECL-86-291 Customer Reference No(s)..

Westinghouse Reference No(s),

i (Change control or RFQ As Applicable i

! WESTINGHOUSE NUCLEAR SAFETY EVALUATION CHECK LIST i

1) NUCLEAR PIANT(8) Samuevah Units i and 2 (TVA/ TEN)

. 2) CHECK LIST APPLICABLE TO: Taeh Snac Reduction in tDtf Laval I (subject of Change) Switch Talaranea for sacruovah Units 1&2

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3) The written safety evaluation of the revised procedura, design change j . or modification required by 10CFR50.59 has been prepared to the extent required and is attached. If a safety evaluation is not required or is incomplete for any reason, explain on Page 2.

l Parts A and B of this Safety Evaluation Check List are to be completed only on the basis of the safety evaluation performed.

CHECK LIST = pART A l (3.1) Yes No.l., A change to the plant as described in the FSAR?

l (3.2) Y6s No_X_ A change to procedures as described in the FSAR7

! (3.3) Yes No X_ A test or experiment not described in the FSAR?

(3.4) Yes_X_ No A change to the plant technical specifications (Appendix A to the Operating License)?

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JUL 25 '86 13:42 WEC T1NC P.3 l

SECL-86-291

4) CHECK LIST - Part B (Justification for Part B Answers must be included on Page 2.) - -

(4.1) Yes No_X Will the probability of an accident previously evaluated in the FSAR be increased?

(4.2) Yes > No X Will the consequences of an accident previously evaluated in the FSAR be increased?

(4.4) Yes No_L, May the possibility of an accident which is different than any already evaluated in the FSAR be created?

l (4.5) Yes No X Will the consequences of a malfunction of

, equipment important to safety previously evaluated l . in the FSAR be increased?

(4.6) Yes No_1 May the possibility of a malfunction of equipment important to safety different than any already evaluated in the FSAR be created?

(4.7) Yes _ No_X , Will the margin of safety as defined in the bases to any technical specifications be reduced?

1 If the answers to any of the above questions are unknown, indicate under 5) REMARKS and explain below.

If the answers to any of the above questions in 4) cannot be answered in the negative, based on the written safety evaluation, the change cannot be approved without an application for license amendment submitted to NRC pursuant to 10CFR50.90.

5) REMARKS: -

page 2 of 3

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JUL 25 '86 13:43 WEC MNC P.4 l

. l SECL-86-291 J

Thefollowing)summarisesthejustificationuponthewrittensafety evaluation,( for answers given in Part 3 of the Safety Evaluation check Lists see Attached Evaluation.

! 1) Reference to Documents containing written safety evaluation Calculation Note SEC-SA-2207-C0 FOR FSAR UPDATE Section: Page(s): Table (s) : Figure (s)I j Reason for/ Description of Changet Prepared By (Nuclear Safety) ry .

urA+1 Date: 7!26!8[s

, i coordinated With Engineer (s): Dates Coordinating Group Manager (s): Dates Nuclear Safety Group Managers # Date Page 3 of 3 h

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I JUL 25 ass 244 &Ec mc P5 l

SAFETY EVALUATION '

IbcA CONSEQUENCES OF A REDUCTION IN UNI LEVEL SWITCH TOLERANCE FOR SEQUOYAH UNITS 1 AND 2 (TVA/ TEN)* j PURPOSE - An evaluation was performed to assess the impact of a

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reduction in the Upper Need Inject $on (UNI) accumulator level switch

, toleraness (a Tech Spec value) on a postulated Loss-of-Coolant accident (LOCA) for Sequoyah Units 1 and 2 (TVA/ TEN) nuclear power station.

SCOPE OF EVAIMATION - This evaluation considered the impact of reduced level awitch tolerances for the UNI accumulator on the large and small break I4CA analyses performed to demonstrate r:ompliance of the emergency core cooling system (ECCS) with the requirements of l 10CFR50.46 and Appendix K.

l l BRIEF STATEMENT OF._ PROBLEM - On July 24, 1986 Safeguards Analysis l was requested to evaluate the impact of a Technical specification l change which reduces the tolerance on the level switch setpoint for the UNI accumulator. The level setpoint itself did not change. For large and small break LOCA analyses ths nominal water volume is modeled as well as the minimum pressure for actuation. This change would not impact either of those parameters.

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JUL 25 '86 13:44 WEC ttC ,

P.6 ggf1LLANCE REQUIREMOffS (Continued)

b. At least once per 31 days and within 5 hosts after each salution '

volume increase-of-greataa then er equal to 12 of tank volume by i

> -" . verifying the heren concentration of the seinien in the water-filled accumulater. '

c. At least once per la months by: .

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1. Verifying that each ecedmulater isolation valve closes automa-tica11 the water level in the water-filled accumulator is

82.1 above the aank. vender westr.tas lias. This oorrgepends to 47.1 1535 inahes when corrested for che mass R32 of eever gen. L.O *

2. Verifying that the "tatal disselved nitrogen and air in the water-filled accumulator is less than 80 SCF per 1800 cubic

' feet of water (equivalent to S x 10-5 pounds aftrogen per l pounds water). . .

d. At least once per 5 years by removing the mainbrane installed between the we.ter-filled and nitrogen bearing accumulators and verifying that the removed membrane bursts at a differential pressure of i 40 t,10 psf. ...._....._......:. . . . . . . . . . . . . . . . . . .

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, May 3,1983 - .

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ML20214J967

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