ML20004E799
| ML20004E799 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 06/11/1981 |
| From: | Colbert W DETROIT EDISON CO. |
| To: | Kintner L Office of Nuclear Reactor Regulation |
| References | |
| EF2-53522, NUDOCS 8106150282 | |
| Download: ML20004E799 (3) | |
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/ w i" June 11, 1981 EF2-53522 Mr. L.L. Kintner U.S. Nuclear Regulatory Commission Division of Project Management Office of Nuclear Reactor Regulation 7920 Norfolk Avenue Bethesda, Maryland 20014
Reference:
Enrico Fermi Atomic Power Plant, Unit 2 NRC Docket No. 50-341
Subject:
Branch Technical Position PSB-1 Degraded Grid Protection
Dear Mr. Kintner:
Provided below is the Edison position regarding degraded grid relaying.
These items confirm a telephone conversa-tion of June 10, 1981 between Messrs. A. Syed and R. Fitz-patrick, NRC, and Messrs. M. Featham and J. Honkala, Detroit Edison.
The item numbers below reference appro-priate section numbers of the subject Branch Technical Position.
Section B.l.(a)
NRC guidance:
Provide calculations for degraded grid relay setpoints, time delays, and tolerances.
The logic used in the calculations should include the criteria of precluding damage to Class IE equipment.
Fermi 2 response:
Calculations will be furnished, under separate cover, showing the methodology and criteria used in selecting the setpoints, time delays, and tolerances.
Please note that the calculations have not as yet been verified by an independent checker as required by QA procedures.
B.1.(b)
NRC guidance:
Fermi 2 has the option to eliminate Item 1 the alarm requirement if the calculations show that the degraded grid relaying should take action with the minimum time delay.
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Mr. L.L. Kintner EF2-53522 page two B.1.(b)
Iten 1 (con't)
Fermi 2 response:
The above referenced calculations indicate that the time delay to actuation should be minimized, once the degraded grid voltage condition has occurred.
Fermi 2 has provided an alarm to give advance notice to the operator that a low grid vol-tage condition exists.
Thus, the alarm relay set-point is set above the degraded grid setpoint, eliminating any time delay asscciated with the alarm.
B.l.(c)
NRC guidance:
The degraded grid relay, and its Item 1 associated components, including the potential transformer feeding the relay, must all be quali-fied to Class IE requirements.
Fermi 2 response:
The relays will be qualified to Class IE requirements.
The relays will be located in, and connected to, the Class IE switchgear and fed from the bus potential transformers, which are also qualified to Class IE requirements.
B.l.(c)
NRC guidance:
A minimwn of two degraded grid re-Item 3 lays are required per division, and both must operate to indicate separation from the offsite power system.
Fermi 2 response:
Fermi 2 complies with this requirement.
Details of the design will be pro-vided 'n drawings as part of the NRC electrical audit, scheduled for June 23, 1981.
B.l.(c)
Fermi 2 response:
Fermi 2 does not have any auto-Item 6 matic bypasses of the degraded relaying.
B.2 NRC guidance:
The Fermi 2 position regarding this section is contained in the Fermi 2 response to Question 222.33 (FSAR Appendix E.5).
The NRC indicated that this position meets the require-ments of Section 2 and is acceptable.
B.3 NRC guidance:
The Fermi 2 commitment as described in FSAR Section 8.2.25 (revised April 1979) satis-fies the requirements of this section and is accept-able.
B.4 NRC guidance:
The Fermi 2 response to Question 222.32A meets the requirements. of this section and is acceptable.
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Mr. L.L. Kintner EF2-53522 page three As stated earlier, design calculations will be provided under separate cover.
Drawings (logic diagrams and sche-matic diagrams) will be available for NRC review at the Electrical Audit.
Please advise me immediately if any further information is required.
Sincerely yours, j/d/ w William F.
Colbert Technical Director Enrico Fermi 2 Project WFC/mle
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