ML20010E458
| ML20010E458 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 08/13/1981 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| 736, NUDOCS 8109040145 | |
| Download: ML20010E458 (3) | |
Text
TOLEDO
%me EDISON Docket No. 50-346 RCHMO P. Croust O
License No. NPF-3 i4isi23S32ai Serial No. 736 t-August 31, 1981
'g R [ W* Q.
Attention:
Mr. John F. Stolz, Chief 44 d'II g.
SEP 03 ygg Director of Nuclear Reactor Regulation Operating Peactor Branch No. 4 V
w Division of Operating Reactors p
United State-Nuclear Regulatory Commission Washington,
.C.
20555 tul
.e
Dear Mr. Stolz:
This letter is in regard to the proposed technical specification change request for the installation of undervoltage relay bypass pushbuttons at the Davis-Besse Nuclear Power Station Unit 1.
The original request was submitted as Attachment III to Toledo Edison, letter dated March 23, 1979 (Serial No. 487).
These pushbuttons aru to be used during reactor coolant pump or circulating water pump starting The accelerating times of these motors exceed the time delay of the ur.dervoltage relays. The resulting voltage dip duririg motor starting woulo erroneously indicate a condition of a degraded power source. This would start the emergency diesel generators and transfer the essential power system to this emergency source. The bypass pushbuttons will prec1r le the unnecessary electric power source shift for these large motor starts.
This letter is to clarify several aspects of this modification.
Item 1 Circuit Quality This represents a modification to a safety related circuit and therefore is consistent with the standards of the original design including IEEE 279-1971. This is reflected in the designation of "Q" on the attached Drawing Change Notice (page 1 of 2, DCN E-34B-10)'.
Item 2 Pushbutton Effects on Circuitry The Drawing Change Notice (DCN) attached reflects the modified undervoltage sensing scheme for degraded electrical power sources. This does not affect the loss power sensing function in any way (relays performing this function are set at 59%).
OI THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OHIO 43652
[I l 9109040145 810813 PDR ADOCK 05000346 A
P,DR
1 The 90*4 undervoltage relay contacts (27A1, 2, 3 and 4) are normally open. Upon sensing a degraded voltage condition, anxiliary relay contacts 27A1, 2, 3 and 4 are closed, thus energizing relay coils 27X-4 and 5.
In turn this will lead to starting of the emergency diesel genera-
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tors and transfer the essential buses to these diesel generators.
As indicated by the DCN, the pushbuttons when depressed simply prevent circuit completion such that relay coils j
27X-4 and 5 would see no change of condition during the voltage r i,> associated with pump starting. When the pushbutton; are released, the circuit is mechanically restored to its original condi';lon. The pushbuttons themselves do not activate or deactivate any circuitry.
Pushbutton Type Item 3 The pushbuttons are:
Cutler Hammer type E30, operator catalog No. E30AA for momentary operation and contact block type KLA3.
It is expected that this information is enough to clarify the intended use and function of this modification to authorine the proposed technical specification as requested.
Very truly yours,
/. /Cas su -
RPC/TKR Jh a/1-2 cc:
NRC Resident Inspector 3
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