ML20217A487

Proposed Tech Specs Revising Surveillance 4.4.6.2.2d & Bases Re Pressure Isolation Valves

ML20217A487
Person / Time
Site:	South Texas
Issue date:	11/15/1990
From:	HOUSTON LIGHTING & POWER CO.
To:
Shared Package
ML20217A485	List: ML20217A487 ST-HL-AE-3627, Application for Amends to Licenses NPF-76 & NPF-80,changing TS Surveillance 4.4.6.2.2d Re Pressure Isolation Valves
References
NUDOCS 9011210107
Download: ML20217A487 (3)

Text

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ATTACHMENT 2 PROPOSED CllANCE TO TECilNICAL SPECIFICATION SURVEILIANCE 4.4.6.2.2d and BASES f.k'i ^ nj i )

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REACTOR COOLANT SYSTEP 4

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/ OPERATIONAL LEAKAGE kVRVU L LANC E EQUEDIENT.1EmLi n.ueg).__.

4.4.6.2.1 Reactor Coolant System leakages shall be demonstrated to be within each of the above limits by: ,

a. Moriitoring the containment atmosphere gaseous radioactivity and par-ticulate radioactivity channels at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />;

b. Monitoring the containment normal sump inventory and discharge at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />;

c. Pertcemance of a Reactor Coolant System water inventory balance at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; and

d. Monitoring the Reactor Head Flange Leakoff System at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />,.

l 4.4.6.2.2 Each Reactor Coolant System Pressure Isolation Valve specified in Table 3.4-1 shall be demonstrated OPERABLE by verifying leakage to be within its *imit:

a. At least once per 18 months,

b. Prior to entering MODE 2 whenever the plant has been in COLD SHUTDOWN for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or more and if leakage testing has not been performed in the previous 9 months, i

c. Prior to returning the valve to service following maintenance, repair or replacement work on the valve, and

-d , Within-24-hours fol4owkg valve Oc4uatier it te automatic cr : nuel l Oc+i+n-w ficw 14nwgh the icive execpt for valva X5?OOOO A,0,0- and-XRH006-1 A,0,C=;=

d,/. As outlined in the ASME Code,Section XI, paragraph IW-3427(b). l The provisions of Sper.ification 4.0.4 are not applicable for entry into MODE 3 or 4.

I SOUTH TEXAS - UNITS 1 & 2 3/4 4-21 l

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_ REACTOR COOLANT SYSTEM 2 PAGE ._4L_0F (;

s BASES OPERATIONAL LEAKAGE (Continued) the presence of any PRESSURE BOUNDARY LEAKAGE requires the unit to be promptly placed in COLD SHUTDOWN.

Industry experience has shown that while a limited amount of leakage is expected from the RCS, the unidentified portion of this leakage can be reduced to a threshold value of less than 1 gpe. This threshold value is sufficiently low to ensure early detection of additional leakage.

The total steam generator tube leakage limit of I gpm for all steam '

generators not isolated from the RCS ensures that the dosage contribution from the tube leakage will be limited to a small fraction of 10 CFR Part 100 i

' dose guideline values in the event of either a steam generator tube rupture or steam line break. The I gpm limit is consistent with the assumptions used in the analysis of these accidents. The 500 gpd leakage limit per steam generator ensures that steam generator tube integrity is mahtained in the event of a main steam line rupture or under LOCA conditior . ,

The 10 gpm IDENTIFIED LEAKAGE limitation provides allowance for a limited '

amount of leakage from known sources whose presence will not interfere with the detection of UNIDENTIFIED LEAKAGE by the Leakage retectinn Systems. '

f '

l The specified allowed leakage from any RCS prest,ure isolation valve is

! sufficiently low to ensure early detection of possible in-series check valve failure, it is apparent that when pressure isolation is provided by two in-series check valves and when failure of one valve in the pair can go undetected for a substantial length of time, verification of valve integrity is required.

Since these valves are important in preventing overpressurization and rupture ,

of the ECCS low pressure piping which could result in a LOCA iMt bypr.re6-ant & ment ~, these valves should be tested periodically to ensure low probability of gross failure. '

The Surveillance Requirements for RCS pressure isolation valves provide added assurance of valve integrity thereby reducing the probability of gross valve failure and consequent intersystem LOCA. Leakage from the RCS pressure isolation valve is IDENTIFIED LEAKAGE and will be considered as a portion of the allowed limit.

L 3/4.4.7 CHEMISTRY The limitations on Reactor Coolant System chemistry ensure that corrosion of the Reactor Coolant System is minimized and reduces the potential for Reactor Coolant System leakage or failure due to stress corrosion. Maintaining SOUTH TEXAS - UNITS 1 & 2 B 3/4 4-4 -

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