ML20135H678
| ML20135H678 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 09/20/1985 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML20135H677 | List: |
| References | |
| NUDOCS 8509240125 | |
| Download: ML20135H678 (4) | |
Text
- _.
PLANT SYSTEMS 3/4.7.7 AUXILIARY BUILDING FILTERED VENTILATION EXHAUST SYSTEM
['
g LIMITING CONDITION FOR OPERATION 3.7.7 The Auxiliary Building Filtered Ventilation Exhaust System shall be OPERA 8LE.
' APPLICABILITY:
MODES 1, 2, 3, and 4.
ACTION:
4 With the Auxiliary Building Filtered Ventilation Exhaust System inoperable, restore the inoperable system to OPERABLE status within 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 STAN08Y 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 COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.*"
l f
SURVEILLANCE REQUIREMENTS 4.7.7 The Auxiliary Building Filtered Ventilation Exhaust System shall be
(
demonstrated OPERABLE:
At least once per 31 days, by initiating, from the control room, flow a.
j through the HEPA filters and charcoal adsorbers and verifying that the system operates for at least 15 minutes;-
b.
At least once per 18 months, or (1) after any structural maintenance on the.HEPA filter or charcoal adsorber housings, or (2) following painting, fire, or chemical release in any ventilation zone communicating with the system, by:
1 1)
Verifying that the cleanup system satisfies the in place pene-tration and bypass leakage testing acceptance criteria of less?
than 1% and uses the test procedure guidance of Regulatory Positions C.S.a. C.S.c and C.5.d of Regulatory Guide 1.52,
' Revision 2, March 1978, and the system flow rate is 54,000 cfm 2 10% (both fans operating - Unit 1) or 43,000 cfm + 10% (both fans operating.- Unit 2);.
T
- Until 11:59 p.m. September 7, 1983, HOT STANDBY conditions may be maintained on d
Unit I without proceeding to COLD SHUTDOWN.
If the system is not restored to
}
OPERABLE status by that time, be in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
l >
%~rou 1:ce An. 3tnsnisex 17,t9er,otrou;roaaos unor u on parts og oa y u s twent, worn y'
)
ross u~rr r n uv"'m 84***!"& FourEAu Ewsr s >3 % o I5 offMut). or rus svirrr. ns uor nesruto ro off4Mt smrus nr rmr ron& st~or a ""sr ItC !"
eor t usn8 07 AfhMsSY Wo!H/W Tkl Nipr 6 nos,xs 4po ou can ;
Y
,4y ow,4 i
McGUIRE - UNITS I and 2 3/4 7-16 Amendment No.-
(Unit 1) 8509240125 850920 Amendment No.
(Unt 2)
DR ADOCK O PDR
Justification and Safety Analysis The proposed amendment would allow maintaining McGuire Nuclear Station Unit 1 in operation until 7:00 a.m. September 27, 1985, with the Auxiliary Building Filtered Ventilation Exhaust System (VA) inoperable. The carbon filter in the l
VA system for Unit 1 failed to pass the routine 18 month surveillance testing requirement 4.7.7.b.1 at 7:00 a.m.,
Friday, September 20, 1985. Thus, the existing Technical Specification 3.7.7 action requires initiation of unit shutdown 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after declaring the system inoperable. The Unit 1 VA system was immediately declared inoperable and prepration to replace and test the carbon beds of the VA system filter have been initiated. This process takes about 5 to 7 days. Current Technical Specification (3.7.7) does not permit sufficient time to replace and test VA system carbon filter; therefore it has become necessary.to submit a request for emergency amendment of the Technical Specifications. The proposed amendment requests that McGuire Unit 1 be granted a temporary relief from the action requirements of Technical Specification 3.7.7 and be permitted to continue operation while the carbon filter bed is being replaced. A submittal to increase the time allowed to restore an inoperable VA system to operablility from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 7 days is already under consideration with the NRC (Ref. Mr. H. B. Tucker's, Duke Power, letter to Mr. H. R. Denton, NRC/0NRR, dated September 16, 1985).
The sole function of the VA system is to filter the airborne radioactivety released from the coolant leakages associated with the ECCS equipment in the Auxiliary Building, following a LOCA involving severe fuel damage.
The off-site doses associated with ECCS leakages post LOCA have been evaluated in the McGuire FSAR (Section 15.6.4.3 and Table 15.6.4-11).
The contribution of ECCS leakages to the off-site doses, post LOCA, is not significant with or without (VA) filtration before release to the environment. Furthermore, during the period of Unit 1 VA system inoperability while replacing the charcoal, the Unit i VA system will be isolated to prevent any possibility of unfiltered leakage from the ECCS pump areas. The ECCS pumps for both units are located in the same general (open) area. Since the Unit 2 VA system intakes are also located in the same corridor for the Unit i and 2 ECCS pumps, and the Unit 2 VA system starts automatically in the event of a LOCA on either unit, this will ensure that any exhaust from the Auxiliary Building is filtered by the operable Unit 2 VA system prior to being released to the Unit stack. (Ref the previously mentioned September 16, 1985 submittal for further details on VA system operation and safety consequences - this submittal indicates that the McGuire Unit I and 2 VA systems are essentially redundant.)
The duration of operation without Unit I having its VA system operabic would be small (<7 days). The probability of occurance of a LOCA during this time is extremely small. For example, the LOCA frequency for a large break with potential for core heatup in 4.7xE-5 per reactor year (see Sequoyah RSSMAP-NUREG/CR-1659). The probability of a large break LOCA during a 7 day period is 9.0xE-7.
The probability of excessive ECCS icakages subsequent to a LOCA is even smaller. Therefore, granting of this emergency request would not pose undue risk to the health and safety of the public. An equally important reason for granting the proposed change is that one thermal cycle would be avoided. This has real benefits in terms of availability, component lifetime and safety.
4 1
E l
Pursuant to the criterion 10 CFR 51.22 (9'. the request for an amendment
)
to allow 7. days to replace a carbon filter located in the restricted area qualifies for a catagorical exclusion from environmental assessment since:
i
.e the amendment does not involve any significant hazards consideration (reference attacment no. 3);
4 e the amendment would not result in significant increase in the amount j
of effluent which may be released offsite. The offsite releases to t
offsite do not occur via VA system except after a LOCA accident involving severe fuel damage and subsequent excessive ECCS leakages.
}j The Unit 2 VA system would automatically serve as a backup when Unit 1 filter is being replaced. No chsnges in the offsite release j
routine or otherwise are expected; e the amendment does not increase individual or occupational exposure.
j If the request for-amendment is denied McGuire Unit I would be required to temporarily shutdown. This involves generation of extra radwaste.as well as I
thermal cycling of power plant components both of which can have negative impact on the environment.
I t
i l
?
l i
1 1
4 i
A i
l
Analysis of Significant Hazards Consideration As required by 10 CFR 50.91, this analysis is provided concerning whether the proposed amendments involve significant hazards considerations, as defined by 10 CFR 50.92.
Standards for determination that a proposed amendment involves no significant hazards considerations are if operation of the facility in accordance with the proposed amendment would not:
- 1) involve a significant increase in the probability or consequences of an accident previously evalutated; 2) create the possibility of a new or different kind of accident from any accident previously evaluated; or
- 3) involve a significant reduction in a margin of safety.
The proposed amendment would allow maintaining McGuire Nuclear Station Unit 1 in operation until.7:00 a.m. September 27, 1985 with the Unit 1 Auxiliary Building Filtered Ventilation Exhaust System (VA) inoperable.
Since the VA system serves only to reduce the consequences of excessive ECCS leakages following a LOCA, the probabilities of LOCA or the postulated subsequent degradation of the ECCS are not affected by the proposed amendment. The consequences of an accident are not significantly increased by the inoperability of one VA system train (for 7 days) since the operable VA system of the other unit provides backup filtration capability and is located in the same general area. Also, the probability of a LOCA during a 7 day period is extremely small (9X10-7). The probability of a LOCA and subsequent excessive ECCS leakage is even smaller.
No new or different accident is created by the proposed change because the VA system only serves to mitigate accidents.
The safety margins contained in the LOCA analyses described in the FSAR are unaffected. The consequences of a LOCA without VA system have already been evaluated in the FSAR (Section 15.6.4) and have been found acceptable.
The consequences of a LOCA with only one VA system operational are less.
Accordingly, the proposed amendment would not involve a significant decrease in a safety margin.
Based upon the preceding analyses, Duke' Power Company concludes that the proposed amendments do not involve a significant hazards consideration.