ML20082M550

Proposed Tech Spec 3.7.1.3, Auxiliary Feedwater Storage Tank, Changing Min Vol Requirement from 518,000 to 485,000 Gallons

ML20082M550
Person / Time
Site:	South Texas
Issue date:	08/26/1991
From:	HOUSTON LIGHTING & POWER CO.
To:
Shared Package
ML20082M537	List: ML20082M550 ST-HL-AE-3861, Application for Amends to Licenses NPF-76 & NPF-80,revising Min Vol Requirement for Tech Spec 3.7.1.3, Auxiliary Feedwater Storage Tank, from 518,000 to 485,000 Gallons
References
NUDOCS 9109050250
Download: ML20082M550 (5)

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Qgestion.440.30N With regard to the information in Appendix 5.4.A " Cold Shutdown capabilitya identify the most limitin6 single failure with regard to cooldown capability and verify that the statement of Table 5.4. A 1 that the auxiliary feedwater storage tank (AFST) " capacity of 500,000 gallons is adequate to support 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> at hot standby conditions followed by 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> cooldown to PJiR cut in condition with a margin for contingencies" coni.iders this failure.

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l eThe~tnost 11miYliiig~Tdilutrregardinfso16wn time is the loss of "A"-triin AC

- i power, which results lu the loss of two stearn generator p0$Vw-Tfic AFST l

usable capacity of $25,000 gallons is adequate to support'4 hourn at hot

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standby, a 14 bour cooldovn, followed by depresyurtfation to RHR conditions i

with a margin for contingencies, A maximtyn-of 377,000 gallons of water would i

I eneratT6s dering this period, I

be added to the effective steam g /

TheAFSTsizingconsiderspossiblelevelinstrumenterror,vaterdeliveredto a faulted steam generator 7 water lost through the turbine lube oil cooler, j

various small s flange or pump seal leakage), and a (inargin agajust'yyteti water losses (i.e.,

vortex formation.

The minimum usable volume in the AFST above

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(thesucetonnozzlesis443,000 gallons, j

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The most limiting failure regarding cooldown time is a 14ain Feedwater

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Line Break (MFLB) with a failure of an Auxiliary Feedwater flow control valve.

T The flow control valve failure in the open position maximj tes the water added to the steam generator with the MFl.B.

The amount of water t o ded for energy removal and cooldown would bc <376,000 gallons with a total time to RllR cut in 1

of <21 hours. A cooldown of 25'F/hr can be accomplished with the remaining three steam generators.

The corresponding miscellaneous lossen at 21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br /> is 95,000 gallons to define a total AFST water volume of <471,000 gallons. The AFST usable capacity of 525,000 is adequate to support this limiting condition.

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ATTACitMENT 4 l

t PROPOSED CllANCE TO TECIINICA1. SPECIFICATION 3,7.1.3

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3. 7.1. 3 lhe auxiliary feedwater storage tank (AFST) shall be OPERABLE with a contained water volume of at least 4167{$0 galions of water.

j APPt}CABlllTY:

MODES 1, 2, and 3. q g g O i

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With the AFS1 inoperable, within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> restore the AFST to OPERABLE status or be in at least H01 STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in H01 SHUTOOWN within the following ) hours.

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4.7.1.3 The AFS1 shall be demonstrated OPERABLE at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> by verifying the contained water volume is within its limits.

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SOUTH TEXA5 - UN115 1 & 2 3/4 7-f>

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ATTACliME5i 7 PLANT $151 EMS ST HL AE M4 /

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f 3/4.7.1.2 AUX 1tl ARY FEEDWA1ER SYS1EH The-0PERABILITY of the Auxiliary feedwater System ensures that the Reactor l'oolant System can be cooled down to less than 350*F from normal operating i

conditions in the event of 'a total loss-of-offsite power.

Each auxiliary feedwater pump is capable of delivering a total feedwater I

flow of $40 gpm at a pressure of 1324 psig to the entrance of the steam genera-tors.

This capacity is sufficient to ensure that adequate feedwater flow is-

- available to remove decay heat and reduce the Reactor Coolant System tempera-ture to less than 350*F when the Residual Heat Removal System may be placed into operation. The ATV pumps are tested usit g the test line back to the ATST and the AfW isolation valves closed to prevent injection of cold water into i

the steam generators..The 51 PEGS isolation valves are active valves required to open on an AfW actuation signal.

Specification 4.7.1.2.1 requires,these valves to be verified in the correct position.

3/4.7.1.3 AllXILI ARY FEE 0 WATER STORAGE TANK (AFST) l

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The OPERABILITY of the auxiliary feedsater storage tank with the minimum j

9ater volume ensures that sufficient water is available to maintain the RCS at i

HOT STANDBY conditions for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> with steam discharge to_ the atmosphere

. concurrent with total loss-of-of fsite power followed by a cooldown to 350'T at

.25'F per hour.

The contained water volume limit includes an allowance for water not usable because of tank discharg line location or other physical l

characteristics, j

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g SPECIIlibACflVI Y gg 3/4.7.1.4 The limitations on Secondary Coolant System specific activity ensure that the resultant offsite radiation dose will be limited to a small fraction of 10 CFR Part 100 dose guidelis values in the event of a steam line rupture.

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This dose also includes the ef fects of a coincident 1 gpm primary-to-secondary tube leak in the steam generator of the affected steam line. These values are consistent with the assumptions used in the safety analyses.

3/4.7.1.5 MAIN STEAM LINE_ ISOLATION VALVES j

The OPERABILITY of the main steam line isolation valves ensures that'no l

more than one steam generator will blow down in the' event of a steam line

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rupture.

This restriction is required to:

(1) minimize the positive reac--

tivity effects of the Reactor Coolant System cooldown associated with the l

_ blowdown, and (2) limit the pressure rise within containment in the event the steam line rupture occurs within containment.

The OPERABIllTY of the main L

steam isolation valves within the closure times of the Surveillance Require-

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ments are consistent with the assumptions used in the safety analyses, j

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