ML20010H780
| ML20010H780 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 09/25/1981 |
| From: | Lentine F COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 2572N, NUDOCS 8109290287 | |
| Download: ML20010H780 (3) | |
Text
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C'N Commonwealth Edison
[ O 7 Addr;ss Reply tr Post Offica Box 767
) one First National Plata, Chicago, Ilknois C
(q/ Chicago lilinois 60690 September 25, 1981 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
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Subject:
Zion Station. Unit 1 9
Proposed Change to Facility D@(3' 9 Operating License No. DPR-39 2
C; l-1 d
NRC Docket No. 50-295-s -
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Dear Mr. Denton:
Commonwealth Edison hereby requests a temporary to~
Facility Operating License No. DPR-39.
A change is requested to Technicel ciecification Section 3.15.1.C to amend the requirement for Re.
AC Offsite Power for Unit 1 by the addition of the following acte:
"In lieu of 345 kv bus section 3, the Unit 2 system auxili-ary transformer (TR242), and the switchgear necessary to supply the Unit 1 4160 volt buses 147, 148 and 149 for the period of September 25, 1981, through October 2, 1981, the reserve access to offsite power for Unit I shall be operable and placed in operation within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> by removing the Unit 1 generator disconnect links and backfeeding power through the Unit 1 main transformers to the Unit 1 unit auxiliary transformer (TR141) and the Unit 1 4160 volt buses 147, 148 and 149."
i This variance is being requested to allow the Unit 2 system auxiliary transformer (TR242) to be removed from service and drained of oil for the purpose of intelaal inspectiun to determine the cause of hydrogen build-up in the transformer oil.
Hydrogen build-up is a very serious condition that could lead to catastrophic transformer failure.
Based on the results of the inspection and if extensive repairs are required, Commonwealth Edison may supplement this l
amendment within a week with a request to extend the provisions of j
the amended Section 3.15.1.C beyond the seven day time period.
During the time period of the transformer repairs, the status of the Units and their offsite po.?er supplies will be as follows:
Unit 1 Unit Status:
Operating
/
,9 Normal source of offsite power:
Unit 1 system auxiliary D
transformer (TR142)
.5 Reserve source of offsite power:
Backfeed through Unit 1
,f main transformers to
//O Unit 1 unit auxiliary transformer (TR141).
8109290287 810925 PDR ADOCK 05000295 P
s H.
R. Denton September 25, 1981 Unit 2 Unit status:
Cold Shutdown (Refueling outage)
Normal source of offsite power:
Backfeed through Unit 2 main transformer to Unit 2 unit auxiliary transformer (TR241)
Reserve source of offsite power:
Dedicated winding of the Unit 1 system auxiliary transformer (TR 142)
The justification for'the variance requested is that the multiple sources of offsite power that are a feature of the Zion design exceed the requirements of 10 CFR 50, Appendix A, Criterion 17.
The Unit 1 system auxiliary transformer (TR142) is the normal and immediate source of offsite power for Unit 1.
All essential and non-essential loads are automatically transferred to the system auxiliary transformer following a Unit 1 generator trip.
A second source of offsite power can be provided on a delayed basis by the Unit 1 unit auxiliary transformer (TR141).
As decribed in the Zion FSAR, this is accomplished by removal of Unit 1 generator disconnect links and backfeeding power through the Unit 1 main transformers to the Unit 1 unit auxiliary transformer.
This operation can be completed within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and will be initiated if and when the diesel generators are called upon to provide emergency power.
Station procedures exist for both the removal of the generator disconnect links and the transfer of loads to the unit auxiliary transformer.
In addition, this operation was recently performed on Unit 2, confirming its feasibility and providing operating experience.
The unit auxiliary transformer is capable of supplying all required Unit 1 loads.
The Unit 1 essential buses are also capable of being powered by a dedicated winding of the Unit 2 system auxiliary transformer (TR242).
This provides a third source of of fsite power in addition to the two sources of power described above.
The variance we havc requested will allow operation of Unit 1 without this additional source operaale.
During the period of variance, the Unit 1 system and unit auxiliary transformers will be operable to provide the two required sources of offsite power.
A review of the Zion Safety Evaluation Report and related correspondence has revealed no objections to the consideration of these two sources as acceptable sources of offsite power.
l During the time period of the transformer repairs, of fsite power will be supplied to Unit 2 by backfeeding through the Unit 2 main transformers to the Unit 2 unic auxiliary transformer (TR241).
l Transfer to this supply has already been performed, as previously described.
A second offsite power supply will be available to Unit 2 from a dedicated winding of the Unit 1 system auxiliary transformer I
(TR142).
Station procedures exist for the transfer of Unit 2 loads l
to this reserve source.
The Unit 1 system auxiliary transformer is
. m
H.
R. Denton September 25, 1981 capable of supplying all Unit 1 Joads that are automatically trans-ferred to it, plus the essential loads that may be required to be transferred from Unit 2.
No Technical Specification changes are required for operation of Unit 2 in the cold shutdown mode with these two sources of offsite power available.
The required fee for the requested amendment will be pro-vided at the earliest opportunity.
This amendment is requested on an emergency basis because of the urgency of the transformer hydrogen build-up problem, and because the existing Tachnical Specification would require shutdown of Unit 1 within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> af ter removal of Transformer 242 from service.
Pleese address any questions you may have concerning this matter to this office.
Very truly yours, 6*WNc F.
G. Lentine Nuclear Licensing Administrator cc:
Zion Resident Inspector 1m SUBSCRIBED AND SWOR to befoge;me this
~
day of d< znn/d 1981.
tla []
Notary Public 2572N