ML17290A841
| ML17290A841 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 12/20/1993 |
| From: | WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | |
| Shared Package | |
| ML17290A840 | List: |
| References | |
| NUDOCS 9312290090 | |
| Download: ML17290A841 (11) | |
Text
CONTAINMENT SYSTEMS ORYWELL AND SUPPRESSION CHAMBER PURGE SYST M
LIMITING CONDITION FOR OPERATION 3.6. 1.8 The drywell and suppression chamber purge system may be in operation with the drywell and/or suppression chamber purge supply and exhaust butterfly isolation valves open for incr tin deinertin or ressure control rovs e
that eac u
err valve is bio ked so as not to o en more than 0
GING through the Standby Gas Treatme S st hall be r estricte o
ess than or equal to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per 365 days (SEE NOTE 1)
~g %1c APPLrCABILITY:
OPERATIONAL CONDITIONS 1, 2, and 3.
ACTION:
>el 4 SURVEILLANCE RE UIREMENTS a.
With a drywell and/or suppression chamber purge supply and/or exhaust butterfly isolation valve o en for other than inerting, deinertin or ressure control or not b to
~eQ
, close the butterfly valve(s) within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLO SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Qg L~
p LI hect')
(Ac 4 4p Allo
) f b.
With a drywell and suppr ssion chamber purge supply and/or exhaust isolation valve(s) with esilient material seals having a measured leakage rate exceeding restore the inoperable valve(s) to OPERABLE status wi hin 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within tne following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
4....
1 en-b, he-dr lmn~uppr~n-chamb~
n ust bu r fly i olation ves ll be ver'w e blocke o as anm
.-704 open, s-so-ver-f4ed-the s 3lda 4.6.1.8.2 At feast once per 6 months, on a STAGGERED TEST BASIS, each'4-and 30-inch drywell and suppression chamber purge supply and exhaust isolation val ve with res i 1 ient material shal 1
be demonstrated OPERABLE by veri fying that the measured leakage is:
a 0 b.
Less than or equal to 0.05 L
per valve test or, a
~ o.o<La ~,. va4a 0 d Greater than C.
re the leakage added to the previously determined total for all valves and penetrations subject to Type B and C tests per LCO 3/4.6. 1.2 shall be less than 0.6 L
In the event the valves are to be operated, and 4.6. 1.8.2.a.
has been
- exceeded, a leakage test must be performed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following oper ation, to ensure. compliance with 0. 6 L.
WASHINGTON NUCLEAR - UNIT 2 3/4 6"11.
AMENDMENT NO.
56 9312290090 931220 PDR ADOCK 05000397
'PDR
Insert to Action Statement 3.6.1.8.b and the leakage added to the previously determined total for all valves and penetrations subject to Type B and C tests per LCO 3/4.6.1.2 is less than 0.6 L secure the valves in the closed position and perform maintenance at the next plant cold shutdown to reduce leakage to within 4.6.1.8.1.a,
C0NTROLLED COPY
'CONTAINMENT SYSTEMS SURVEILLANCE RE UIREMENTS Continued
.8&
The cumulative time that the drywell and suppression chamber purge system as been in operation PURGING through the Standby Gas Treatment System shall be verified to be less than o
a to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per 365 days prior to use in this mode of operation
~ Ku.
g (,,f,Y.z NO 1:
r the peri d of time 1
s per s.
be WASHINGTON NUCLEAR - UNIT 2 3/4 6"12 AMENOMENT NO.
56
II t
I'
'i
CONTAINMENT SYSTEMS CONTROLLED COPY BASES MSIV LEAKAGE CONTROL SYSTEM (Continued)
Design specifications require the system to accommodate a leak rate of five times the Technical Specification leakage allowed for the MSIVs while maintaining a negative pressure downstream of the MSIVs.
The allowed leakage I
value per each valve is.ll.5 scfm, or a total of 230 scfh (3.8 scfm).
When corrected for worst case pressure, temperature and humidity expected to be see during surveillance testing conditions, the flow would never exceed an indi-cated value (uncorrected reading from local flow instrumentation) of 5 cfm.
The 30 cfm acceptance criterion provides significant margin to this design basis requirement and provides a benchmark for evaluating long term blower performance.
The Technical Specification limit for pressure of -17" H20 W.C.
was also established based on a benchmark of the installed system performance capability.
This -17" H20 W.C. provides assurance that the negative pressure criterion can be met.
3/4.6.1.5 PRIMARY CONTAINMENT STRUCTURAL INTEGRITY Th>s l>mitatson ensures that the structura sntegrity of the containment steel vessel will be maintained comparable to the original design standards for the life of the unit.
Structural integrity is required to ensure that the containment will withstand the maximum pressure of 34.7 psig in the event of a LOCA.
A visual inspection in conjunction with Type A leakage tests is sufficient to demonstrate this capability..
3/4.6.1.6 DRYWELL AND SUPPRESSION CHAMBER INTERNAL PRESSURE The 11m>tations on drywell and suppress)on chamber internal pressure ensure that the containment peak pressure of 34.7 psig does not exceed the design pressure of 45 psig during LOCA conditions or that the external pressure differential does not exceed the design maximum external pressure differential of 2 psid.
The limit of 1.75 psig for initial positive contain" ment pressure will limit the total pressure to 34.7 psig which is less than the design pressure and is consistent with the safety analysis.
3/4.6. 1.7 DRYWELL AVERAGE AIR TEMPERATURE The limitation on drywell average air temperature ensures that the containment peak air temperature does not exceed the design temperature of 340 F during LOCA conditions and is consistent with the safety analysis.
3/4.6. 1.8 DRYWELL AND SUPPRESSION CHAMBER PURGE SYSTEM 24-inch and 38 ell an ppresslon chamber purge pgy-and exhaust 1
valves are re o be sealed closed duri lant ope ion since th e
es ave not b n demonstrat capa e of clos' uring ea reak accident.
ning these va s sealed clio ing plant operations nsure at excessive antit of radio-active mater>a ill n the purge s
To provide assurance that the
-inch and 30-inch val ca be inadve ently opened, y are os
'ccordanc~e
'W-S view Plan 6.
which inclu m chanical devices t r lock the valve c or prevent power fro eing pp~ to the valve operator.
g,)4~
f,l4cu~g y~C, (a)
Letter, G02-75-238, dated August 18, 1975, NO Strand (SS) to OD Parr (NRC), "Response to Request for Information Main Steam Isolation Valve Leakage Control System" WASHINGTON NUCLEAR - UNIT 2 B '3/4 6-2 Amendment No.
lOO
Proposed BASES change for Drywell and Suppression Chamber Purge System (replaces first paragraph of 3/4.6.1.8 on page B 3/4 6-2) 4 1 8 DRYWELLAND S PPRESSION HAMBER P E
YSTEM The 24-inch and 30-inch drywell and suppression chamber purge supply and exhaust isolation valves are required to be closed during plant operation except as required for inerting, de-inerting and pressure control.
Until all the drywell and suppression chamber valves have been qualified as capable of closing within the times assumed in the safety analysis, they shall not be open more than 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> in any consecutive 365 days.
Valves not capable of closing from a fullopen position during a LOCA or steam line break accident shall be blocked so as not to open more than 70'.
IP a
CONTAINMENT SYSTEMS
~k BASES CONTROLLED COPY DRYWELL AND SUPPRESSION CHAMBER PURGE SYSTEM (Continued) lc e use o
e drywell and suppression chamber purge lines isArestricted
~4i~ ~~""h
~ the 2-inch purge supply and exhaust isolation valves since, PpVke-4he.
the 2-inch valves will close during a LOCA or steam line break accident and therefore the SITE BOUNDARY dose guidelines of 10 CFR Part 100 would not be exceeded in the event of an accident during PURGING operations.
The design of the 2-ihch purge supply and exhaust isolation valves meets the requirements of Branch Technical Position CSB 6-4, "Containment Purging During Normal Plant Operations."
Leakage integrity tests with a maximum allowable leakage rate for purge supply and exhaust isolation valves will provide early indication of resilient material seal degradation and will allow the opportunity for repair before gross leakage failure develops.
The 0.60 L
'leakage limit shall not be a
exceeded when the leakage rates etermined by the leakage integrity tests of those valves are added to the pr viously determined total for all valves and penetrations subject to Type B a d
C tests.
V l ec.
i$h ~41 4
cga s J, lit 3/4.6.2.
DEPRESSURIZATION SYSTEMS Tq p 0
sh A.
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'4l
~
r< 'll e
Q, (p, t,2, Q fo 4.s5u,rc ctllowAtoic f'c4$+Q, I'AUc 414 iwt The specifications of this section ensure that the primary containment pressure will not exceed the design pressure of 45 psig during primary system blowdown from full operating pressure.
The suppression chamber water provides the heat sink for the reactor coolant system energy release following a postulated rupture of the system.
The suppression chamber water volume must absorb the associated decay and structural sensible heat released during reactor coolant system blowdown from 1020 psig.
Since all of the gases in the drywell are purged into the suppres-sion chamber air space during a loss-of-coolant accident, the pressure of the liquid must not exceed 45 psig, the suppression chamber maximum pressure.
The design volume of the suppression
- chamber, water and air, was obtained by con-sidering that the total volume of reactor coolant and to be considered is discharged to the suppression chamber and that the drywell volume is purged to the suppression chamber.
Using the minimum or maximum water volumes given in this specification,-
containment pressure during the design basis accident is approximately 34.7 psig which is below the design pressure of 45 psig.
Maximum water volume of 128,827 ft~ results in a downcomer submergence of 12 ft and the minimum volume of 127,197 ft results in a submergence approximately 4 inches less.
The majority of the Bodega tests were run with a submerged. length of 4 feet and" with complete condensation.
Thus, with respect to the downcomer submergence; this specification is adequate.
The maximum temperature at the end of the blowdown tested during the Humboldt Bay and Bodega Bay tests was 170'F and this is conservatively taken to be the limit for complete condensation of the reactor coolant, although condensation would occur for temperatures above 170'F.
WASHINGTON NUCLEAR - UNIT 2 B 3/4 6-3 Amendment No. 100
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