ML20151U752
| ML20151U752 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/28/1986 |
| From: | Opeka J, Sears C NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | Charemagne Grimes Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20151U757 | List: |
| References | |
| B11922, NUDOCS 8602110100 | |
| Download: ML20151U752 (3) | |
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HARTFORD. CONNECTICUT 06141-0270 L
L J (("C"C (203) 665-5000 January 28,1986 Docket No. 50-245 Bil922 Office of Nuclear Reactor Regulation Attn: - Mr. Christopher 1. Grimes, Director Integrated Safety Assessment Project Directorate Division of PWR Licensing - B U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
Millstone Nuclear Power Station, Unit No.1 Proposed Revision to Technical Specifications Auxiliary Electrical System On February 17,1982, while switching to isolate the 383-345 kV bus at Millstone, circuit switcher 15G-2T-6 faulted causing a fire in the circuit switcher. The faulted switcher was cleared by operation of the Millstone Card Street 383 line protective relaying. This action de-energized incoming 345 kV to the Millstone Unit I reserve station service transformer (RSST).
Millstone Unit 1 Technical Specifications allow continued operation during this situation provided both emergency power sources are operating and the isolatiori condenser system is operable. The gas turbine and diesel generator were started and loaded during the repair period.
Subsequent review of Technical Specifications show they may be restrictive and create an unnecessary challenge to safety equipment.
Pursuant to 10CFR 50.90, Northeast Nuclear Energy Company (NNECO) hereby proposes to amend its Operating License, DPR-21, by incorporating the attached proposed revision into the Millstone Unit No.1 Technical Specifications.
Tne proposed Technical Specification revision is provided as Attachment 1.- The proposed revision <'eletes the requirement for isolation condenser openbility for continued power operation when no offsite 345 kV power is availab?e.
The proposed revision also changes the word " operating" to "operahle" in Specification 3.9.B.2. The Technical Specification definition of operating means component performance of its intended function. This means the gas turbine and diesel generator must be loaded, i.e., phased to operating buses.
NNECO has reviewed the attached proposed revision pursuant to 10CFR50.59 and has determined that it does not constitute an unreviewed safety question.
The probability of occurrence or the consequences of a previously analyzed accident have not been increased and the possibility of a new type of accident not previously evaluated has not been created. Deleting the requirement for isolation condenser operability with no offsite 345 kV power available will allow the main condenser to be used as a heat sink with the main generator supplying house loads while repairs are being conducted to restore the isolation condenser k
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1 l and offsite 345 kV power operability. With the existing Technical Specifications, loss of 345 kV offsite power in conjunction with loss of the isolation condenser would require an. immediate shutdown with the following undesirable consequences:
o The plant condenser would be lost as a heat sink.
Unnecessary challenges would result to the emergency diesel and gas o
turbine generators. The components would be required to power safe shutdown equipment since offsite power would be unavailable.
Thus, the existing technical specifications could lead to a forced shutdown in a loss of offsite power situation.
This is considered to be_ a less ' favorable condition than. continued power operation with the isolation condenser unavailable for' 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, in that more decay. heat removal options would be available.
NNECO has reviewed the proposed revision in accordance with 10CFR50.92, and
.has concl_uded that it does not involve a significant hazards consideration. The basis for this conclusion is that the criteria of 10CFR50.92(c) are not compromised, a conclusion ~which is supported by our determinations made pursuant to 10CFR50.59. The proposed change is not precisely enveloped by any of the examples in 48FR14870 of amendments that are considered not likely to involve a significant hazards consideration.
However, the change does not involve a significant hazards consideration in light of the following:
- 1) Since the' current evaluation for this accident does ' not credit the availability of the isolation condenser, the proposed changes do not significantly increase the probability of consequences of an accident previously evaluated.
- 2) The possibility of an accident of a new or different kind from those previously analyzed is not created. The proposed changes specify an improved plant response to a postulated set of failures which represent -
an improvement in overall plant safety.
- 3) Because this accident evaluation was performed without taking credit for an operating isolation condenser, no margin of safety is significantly reduced.
In conclusion, an enhancement in safety is achieved by eliminating unnecessary challenges to the emergency power sources.
The Millstone Unit No. I Nuclear Review Board has reviewed and approved the attached proposed revision and has concurred with the above determinations.
In accordance with 10CFR50.91(b), NNECO is providing the State of Connecticut with a copy of this proposed amendment.
. Pursuant to the requirements of 10CFR170.12(c), enclosed with 'this amendment request is the application fee of $150.00.
I
. We trust you find this information satisfactory.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY N b.D E
J. F. Opeka -
Senior Vice President By: C. F. Sears Vice President cc:
Mr. Kevin McCarthy Director, Radiation Control Unit Department of Environmental Protection
~ Hartford, Connecticut 06116 STATE'OF CONNECTICUT )
) ss. Berlin COUNTY OF HARTFORD
)
Then personally appeared before me C. F. Sears, who being duly sworn, did state that he is Vice President of Northeast Nuclear Energy Company, a Licensee herein, that he is authorized to execute and file the foregoing information in the name and on behalf of the Licensees herein and that the statements contained in said information are true and correct to the best of his knowledge and belief.
11 Tl Gr@L n_n 1 ry Pupic
.M Commission Expires March 31,1989