ML20002C986
| ML20002C986 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 02/27/1970 |
| From: | Haueter R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Morris P, Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101150660 | |
| Download: ML20002C986 (4) | |
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D February 27, 1970 u
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Dr. P. A. Morris, Director Division of Reactor Licensing Re: Big Rock Point United States Atomic Energy Commission DPR-6 Washington, DC 20545 Docket 50-155
Dear Dr. Morris:
Attention:
Mr. D. J. Skovholt Transmitted herewith are three (3) executed and thirty-seven (37) confomed copies of a Request for a Change to the Technical Speci-fications of License DPR-6, Docket No 50-155, issued to Consumers Power Company on May 1,1964, for the Big Rock Point Nuclear Plant.
This proposed change (No 20) will enable the Big Rock Point Plant to utilize the 1-Y bus, fed from a 460/120 V a-c station power source, as the normal supply of power to the control rod drive position indicating system and associated interlocks and relays. The 125 V d-c operated motor generator set (formerly used as the normal power source) will be used for a standby source of power. Upon loss of power to the 1-Y bus, a throwover device to the motor generator set would operate automatically furnishing a backup power supply for the control rod position indicating system.
This new " normal power supply" vill provide for a more con-sistent power source, a reduction in routine maintenance time and an improved system reliability.
We would like to make this change during our present refueling outage (February-March 1970). Therefore, we vould appreciate an expedi-tious handling of this Request for a Technical Specifications Change so that we might receive approval before March 27, 1970.
i Yours very truly,
(
ERC/ map Robert L. Haueter l
Electric Production l
CC: GFiorelli Superintendent - Nuclear EJBrunner
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CONSUbERS POWER C0b'PA?H i
Docket No 50-155 a
l Request for Change to the Technical Specifications Licence No DPR-6 t
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For the reasons hereinafter set forth, it is requested that l
i the Technical Specifications of License DPR-6, Docket 50-155, issued to Consumers Power Company on May 1,1964, for the Big Rock Point Plant be i
j changed as follows:
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Section 4 In Section 4.2.l(a), second paragraph, line 8, change to read:
"The fourth bus is supp'ied from a different 480 volt system I
through a 480/120 volt (.-c transformer and power panel, which supp' tes power to the contro'. rod position indi-cating system. Standby power shall be supplied from the 125 volt d-c system using a motor generator set.... "
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II.
Discussion
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The present 125 volt d-c operated motor generator unit was t
installed a number of years ago to supply 120 volt a-c power for the j
control rod drive position indicating system, associated interlocks and relays for the reactar crane. This unit has not performed to our satis-i faction since initial installation due to the following considerations:
1.
Poor voltage regulation re' alting in voltage swings in the system, complicated further by the trenthly overcharge placed on the battery.
2.
Dccessive maintenance to the motor generator unit, espe-cially due to heavy wear on slip rings and commutator.
3 High load requirements (30% of the normal load now supplied by the station d-c battery).
In the present system, the 1-Y bus furnishes only standby power to the 120 volt reactor protection system buses 1, 2 and 3 Power is supplied to the 1-Y bus from the 120 volt o-c instrument and control i
transfomer 2B, fed from a 480 volt a-c power source. The 1-Y bus has shown good reliability when needed during the past years and does not experience the voltage swings characteristic of the motor generator unit.
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l' The proposed system, utilizing the 1-Y bus, would farnish
. power to the control. rod drive position indicating system, associated interlocks and relays. Reactor protection buses 1, 2 and 3 would not j
be affected by this change and would still have the 1-Y bus as backup if failure occurred to their respective power sources. The 125 volt d-c operated motor generator unit would be used as a standby source of power l
l-(automatically placed in service at full voltage in approximately fivc
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seconds) to the control rod drive position indicating system, associated I
interlocks and relays if power should fail tc. the 1-Y bus. This condi-i
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tion is unlikely, however, because the emergency diesel generator pro-f vides a second source of power for instrument and control transformer 2B f
furnishing the 1-Y bus.
1 III. Conclusion We feel that the proposed change will provide for a more constant l
source of power, reduce future maintenance requirements and improve system f
f reliability.
l In our opinion, the proposed change does not involve an unreviewed or significant change in the hazards considerations described or implicit in the Final Hazards Summary Report.
CONSUMERS POWER COMPANY j
4 By Senior Vice President l
l Date: February 27, 1970 Sworn and subscribed to before me this 27th day of February 1970.
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a s mch I Notary Public, Jackson County, Michigan My Commission Expires January 15, 1972 i
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NO.s DATE CECIIVED TAT 3 CF DOCUMENT iI M M*N N"N RO Jackson, Michiama 49201 Omta.
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RECEtVED BY DATE DATE PtEFERR ED TO DEsc lFTION; (Must ble UncJassified) a,5 tL ras the followingt wf for action DI9fRIBUTION:
Regulatory file d
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- DC PDR Request, notarised 2-27-70, for Ccarpliance(2)
Chang 3toTechSpecs(ProposedChange BOC (Rm P S06 Ai, h.20) g, ppge, g gg,p; Dubs /Levine (3 *i.. we4a3roo eare. 4)
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