ML20074A756

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Clarifies Proposed Changes in Undervoltage Protection & Reiterates Schedule for Implementation of Design Changes & Mods.Existing non-Class IE Undervoltage Relays Will Be Retained as Protection for 4,160-volt Buses
ML20074A756
Person / Time
Site: Fort Saint Vrain Xcel Energy icon.png
Issue date: 04/27/1983
From: Brey H
PUBLIC SERVICE CO. OF COLORADO
To: Jay Collins
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
P-83161, TAC-5908, TAC-59801, NUDOCS 8305160048
Download: ML20074A756 (2)


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Public Service Comixmy cf Cinh 2420 W. 26th Avenue, Suite 1000 Denver, Colorado 80211 April 27, 1983 Fort St. Vrain 'h(

Unit No. 1 P-83161 Mr. John T. Collins, Regional Administrator Region IV

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Suite 1000 Arlington, Texas 76011 "*

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SUBJECT:

Electric Power Systems

REFERENCES:

G-83138 from Madsen to Lee dtd 3/30/83; G-82338 from Clark to Lee dtd 10/12/82

Dear Mr. Collins:

The intent of this letter is (1) to clarify certain information pertaining to the proposed changes in Fort St. Vrain's undervol tage protection and, (2) to reiterate our schedule for implementation of design changes and modifications previously outlined.

At present the undervoltage protection at Fort St. Vrain utilizes two non-class 1E relays which monitor the 4160V output of the Reserve Auxiliary Transformer. In the event that one or both of these relays should actuate or fail, certain class IE functions will be initiated, i.e. diesel generator starting, 480 volt bus breaker tripping and load shedding on the 480 volt class IE buses. It is our intent that no class 1E functions be initiated by these non-class 1E relays. For this reason, these safety functions have been assigned to the proposed class IE protective relay system to be installed on the 480 volt class 1E buses.

The existing non-class 1E undervoltage relays will be retained as protection for the 4160 volt non-class 1E buses.

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,a P-83161 Page 2 As indicated in previous correspondence P-82399 (Warembourg to Kuzmycz dated 9/16/82) we have requested deferring submittal of a finalized Technical Specification concerning the proposed undervoltage relaying modifications until those modifications are undertaken. As stated in letter P-82169 (Brey to Kuzmycz dated 5/28/82) we feel that the most expedient method of executing design changes and modifications relating to the proposed degraded grid voltage protection would be to implement these changes concurrent with the upgrading and change out of the 480 volt class 1E essential buses. The replacement of the 480 volt class 1E buses is an operational decision made by Public Service Company of Colorado and is not an NRC connitment. The change out of the 480 volt class 1E buses will coincide with the 3rd refueling outage at Fort St. Vrain presently scheduled for late 1983.

If you have any questions concerning this matter do not nesitate to call.

Very truly yours, m9 p hhW CA H. L. Brey, Manager Nuclear Engineering Division HLB /bs:pa

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