ML20072K348
| ML20072K348 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 03/22/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072K338 | List: |
| References | |
| TAC-49705, NUDOCS 8303300516 | |
| Download: ML20072K348 (3) | |
Text
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UNITED' STATES
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g NUCLEArt REGULATORY COMMISSION t;
%l EASHINGTcN, C. C. 20555
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SAFETY EVAlt/ATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT Nc.9 5 TO 4ACILI~Y OPERATING LICENSE NO. DPR-57 GEORGIA POWER COPPANY
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OGLETHORPE POWER COR DIRTION 5
f10NICIPAL ELECTRIC AUTliORIYY OF GEORGIA.
CITY OF DALTON, GE0dGIA EDWIN I. HATCH NUCLEAR PLANT, UNIT l',
DOCKET NO. 50-321 Introduction By application dated February 22, 1983, as confirmed on March 2,1983, Georgia Power Company requested changes to the Technical Specifications (TSs) appended to Facility Operating License No. DPR-57. The pmposed change would permit an extension in time interval, from 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, befom the oxygen concent7ation in the drywell shall be reduced to 4%, after the reactor is p'. aced in the Run Mode. This change was requested.on an expedited basis; oral authorization'was' issued February 22, 1983, and was confirmed by letter dated February 23,
- 1983.
j Discussion Technical Specification 3.7.A.5.b requires "within the 24-hour period subsequent to placing the reactor in the RUN mode following a shutdown, the containment atmosphere oxygen concentration shall be reduced to less than 4% by volume and maintained in this condition". However, during the return to operation of February 22, 1983, it.becane apparent
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that this Limiting Condition for Operation (LCO) could not be' net.
Inability to meet the 24-houriC0 was due to time limits ~1mposed on the s
use of the 18-inch containment, purge and vent valves.
This necessitated i
the use of 2-inch lines (bypass lines for the 18-inch valves) for containment purge and vent functions.
These %-inch lines do not permit timely inerting of the containment. No other lines are
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available for containment purge and vent functions.
Inerting commenced at about 7:00 p.m. (CST) on February 20, 1983, followfng last personnel entry into primary contai.. ment.~ The licer.see, therefore, requested a one-time extension of the 24-heur LCO to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The 24-hour'LCO interval began at about 9:00 a.m. (CST) on February 22, 1983.
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'I 8303300516 830322 PDR ADOCK 05000321 P
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E.I.H. '
s Eval uation i
The basis for the present 24-hour requirement on attaining a 4%
oxygen concentration following entry into the RUN mode is to minimize the possibility of hydrogen combustion following a loss 'of-coolant i
accident (LOCA). The 24-hour period was established, M stated in the bases for Specification 3.7. A.5, as being suf ficient to perform necessary drywell,l' inspections and establish the required oxygen cone':ntration.
The contro
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is administrative and supplements the Containment Atmosphere Dilution (CAD) system, which can be used to control oxygen concentrations.
l The CAD system provides the basis for assurina containinent integrity post At the time Unit 1 was licensed, the CAD systen'was installed
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LOCA.
to heet the applicabid reDulatjons cddressing hydrogen evolution.
I Because the 24-hour limit is an administrative control, as opposed to l
providing a safety function, margins of safety, as defined in the Technical Specifications, are not reduced by allowing a longer period of time to complete drywell inerting.
The safety margin is provided by-the CAD system.
Additionally, due to plant factors, maximum' thermal power sil'1 no't exceed fifty percent-(50:;) while oxygen concentrations exceed 4%.
Extens ton of the drywell inert'ing LCO alsp necessitates an ext'e'sion of _
n the LC3 for Technical Specification 3.7.A.7.(1), Drywell-Suppression Chac.%r Differential Pressure, for a ifke time period.
Required differential i
pressure cannot be established until inerting is completed as the contain-ment vents are open during inerting.
. Hatch Unit 1 has previously used the 18" purge and vent lines for inerting purposes while starting up.
Due to the NRC's requirements to limit i
operation of large purge systems with unqualified purge valves to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> a year, Hatch Unit 1 is now attempting to inert by using the 2"
purge bypass valve, which does not have a time restriction.
This is the first plant startup using only the smaller purge line.
Currently contain-cent atmospheric rionitors measure the oxygen concentration at approximately 65 f~
The licensee Ms, determined that permanent Technical Specification changes
. are necessary because 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> do not allow sufficient time for inerting.
This is because the licensee has decided not to use the 18" purgt.
system for the purpose of iner ting, thus preserving the 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> of use f$r other situations. W will pur; sue perraanent Technical Specification change with the licensee in the future.
However, for the present plant startup situatien, we will address the licensee's proposed one-time only change.
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k'e believe that'a basis exi'sts to permit acceptance of the proposed changes.
They are as follows:
- 1. lThe containinent atmosphere is presently at 6% oxygen conlentration.
This in itself greatly reduces the probability of hydrogen combustion in the event of a postulated LOCA and subsequent hydrogen generation.
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- 3' 2.
The maximum thermal power wil,1 not exceed 50% during the 72-hour interval. This will limit fission product and decay heat buildup. Thus, the worst case scenario ~will be less tihn the design basis event.
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There is a very inw likelihood cf an hccident involii'ng large amounts of hydrogen genention ir/ the 72-hour intervalf 4.
The proposed change for Unit l'is nearlyioentical to the 72 LCO @hich-has previously been found acceptable for; Hatch Unit 2.
x Environmental Corsideration
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We have determityed that,the amendment does not authorize a change in effluent types or total amounts nor an increase in power level and will not.ren ~.t in any significant envirotanental' impact. Having made this determination, we have further concluded that the amendt:ent involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 551.6(d)(4). that an-environma-c.31 imesct= statement, or negative. declaration and environ-mental _ impact ap'p'raisal liee'd not be. prepared in connection with the issuance of this ~ amendment.
Conclusion We have concluced, based on the considerations discussed'above, that:
(1) because the amendment does not involve a significant increa's'e in the probability or consequences of an accident previously evaluated, does not create thel possibility of:an accident of a type different from any evaluated previously, and.does not involve afsignificant
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reduction in a margin of safety ^, the amendment doesnot involve a
. significant hazards cosiderationt (2) ~there is reasonable' assurance tnat the health and sdfetyscf the public will;not be endangered by~ '
operation in the proposed rmnner, and'(3)^such-activities will be conducted in compliance with the Comission's regulations and the 7
issuance c' this amendment will!not be inimiciil: to7the common defense and security or to _the, health and' safety of' the public.
e Dated:
MAR 221983 l
The following NRC.' personnel have contributed to this SER:
D. Pickett and G. Rivenbark.
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