ML20009E445
| ML20009E445 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 07/22/1981 |
| From: | Gallagher J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8107280213 | |
| Download: ML20009E445 (2) | |
Text
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PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8609 PHILADELPHI A. PA.19101
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JOSEPH W. GALLAGHER
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hL a ri July 22, 1981
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Docket Nos. 50-277 J
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l Mr. John F.
Stolz, Chief l
Operating Reactors Branch #4 f
Division of Licensing US Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Stolz:
Your letter of June 19, 1981, requested additional information with regard to our proposed degraded grid voltage protection for Peach Bottom Atomic Power Station Units 2 and 3.
The information requested in your letter and our response are listed sequentially below:
NRC REQUEST
REFERENCES:
(1) NRC Letter to all power reactor licenses, dated June 2, 1977
_.1 Reference (1), Enclosure 1, page 2, Position 1,c,(1) requests that the..." time delay, including margin, shall not exceed the maximum tir.e delay that is assumed in the FSAR accident analyses..."
The degraded voltage logic scheme for Peach Bottom Units 2 and 3 traasfers the Class 1E buses to a second off-site source should the first off-site source be degraded.
The licensees should show that for all possible voltage levels and logic schemes, the time delay would not exceed or add to the time assumed in the FSAR accilent analyses due to insufficient voltage for Class 1E equipm.ent to start or operate.
Since it appears, the proposed 2nd level undervoltage protection logic does not 8107280213 810722 0
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Mr. J.
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Stolz Page 2 meet this requirement, enclosed :Ls a recently revised Power 4
Systems Branch Technical Position (PSB 1) which outlines an alternate approach acceptable to the NRC.
I
Response
We propose to meet the alternate approach detailed in your Power Systems Branch Technical Position (PSB 1) Part 1, b, (1) by adding a second TR electronic timing relay to the output of our proposed second level undervoltage logic scheme.
The output of the relay will initiate an alarm in the control room and set-up a permissive circuit where the occurrence of a subsequent accident signal will separate the emergency buses from the offsite power system being used.
The timing relay will have a time delay of six seconds, which will prevent separation of the emergency buses from the offsite source for motor starting transients.
If you have any questions or require additional information, please don't hesitate to call.
t Very truly yours, y 08 A~
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