ML20136G328

Application for Amend to Licenses NPF-11 & NPF-18,revising Tech Specs to Include Low & Degraded Grid Voltage Mods That Will Be Installed on Divs I,Ii & III Trip Sys During First Refueling Outage.Fee Paid

ML20136G328
Person / Time
Site:	LaSalle
Issue date:	11/13/1985
From:	Massin H COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
Shared Package
ML20136G333	List: ML20136G328 ML20136G346
References
0881K, 881K, NUDOCS 8511220319
Download: ML20136G328 (4)

Text

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h /Commonwealth Edison One First National Plua, Chictgo, Ithnois T Address Reply to: Post Office Box 767 N Chicago, Illinois 60690 November 13, 1985 l

Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

LaSalle County Station Units 1 & 2 Proposed Amendments to Technical Specification for Facility Operating License W F-ll and W F-18 Low and Degraded Grid Voltage NRC Docket Ne.3. 50-373 and 50-374

Reference:

(1) Facility Operating License NPF-ll l

(Unit 1), Condition 2.c (20)

(2) Facility. Operating License NPF-18 l (Unit 2), Condition 2.c.(ll)

(3) UFSAR Section 8.2.3.3 Undervoltage Relays (4) SER (NUREG 0519) Section 8.2.2.2 (5) FSAR Question 40.102

Dear Mr. Denton:

Pursuant to 10 CFR 50.59, Commonwealth Edison proposes to amend l Appendix A, Technical Specification, to Facility Operation License NPF-ll'and NPF-18. This amendment change is being suomitted for your staff's review and

{ approval and is in accordance with References (1) and (2).

This proposed amendment revises the Technical Specifications to include modifications that will be installed on Divisions I, II, and III in Unit 1 during the first refueling outage in accordance with Reference (1).

The Technical Specification change request also adds the Unit 2 completed modification of Divisions II and III. The modification of Unit 2 Division I will be completed prior to startup after the first refueling outage for Unit 2 in accordance with Reference (2).- The Tech Spec change supporting Unit 2 Division I will be submitted closer to the Unit 2 first refueling outage.

Approval of the attached proposed amendment is requested prior to startup for Unit 1 - Cycle 2. This is currently scheduled for March, 1986.

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12%d e g /

H. R. Denton November 13, 1985 Attachment A provides background and discussion. The proposed change

.is enclosed in Attachment 8. The attached change has received both On-Site and Off-Site review and approval. We have reviewed this amendment request and find that no significant hazards consideration exists. Our review is documented in Attachment C.

Commonwealth Edison is notifying the State of Illinois of our request for this amendment by transmitting a copy of this letter and its attachments'to the designated State Official.

In accordance with the requirements of 10 CFR 50.170, a fee remittance' in the amount of $150.00 is enclosed.-

Please direct any questions you may have concerning this matter to l

this office.

Three (3) signed originals and thirty-seven (37) copies of this

~ transmittal and its attachments are provided for your use.

Very truly yours, e

H. L. assin Nuclear Licensing Administrator bs Attachments A: Background and Discussion B: Technical Specification Change to NPF-ll and NPF-18 C: Evaluation of Significant Hazarus Consideration cc: Region III Inspector- LSCS A. Bournia - NRR M. Parker - State of Illinois

.SUBSC BED and SWOR to befo meth}s /$___ day of _ ht pfw /ua , 1985 11 l .-

ADD Notary Public 0881K

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ATTACHNENT A TECHNICAL SPECIFICATION CHANGE REQUEST LASALLE COUNIY-STATION UNIlS 1 ano-2

SUBJECT:

LaSalle County Station Units 1 and 2 Low and Degraded Grid Voltage BACKGROLND As indicated in reference (5) an analysis of degraded voltage conditions was done and it was determined that operation in the degraded voltage condition described was an extremely unlikely event for the Commonwealth Edison System. System voltage at a level low enough to cause a degraded (90% bus voltage) condition would also cause a complete collapse of the system (no-voltage condition). However, to comply with NPF-11 and NPF-8 license conditions (references 1 and 2), LaSalle County has or will install modifications to prevent a potential common mode failure of safety-related equipment caused by sustained operation at low grid voltage. Class 1E equipment is designed and qualified to operate only within 10% of rated voltage. The original design provided no protection against a degraded voltage condition between the trip setpoint-of the normal (first level) of undervoltage relays (60 to 69% of rated voltage) and 90% of rated voltage.

With this revised design, the ESF bus will automatically disconnect from the offsite oower sources shed loads, and transfer to the diesel generator if a degraded voltage condition exists for more than 5 minutes during normal plant conditions or immediately upon receipt of an ECCS initiation signal (neither time including the 10 second instrument time delay). The required emergency loads are then automatically energized through load sequencing logic if an initiation signal is present. The additional degraded voltage logic adds two undervoltage relays and a time delay relay to each 4.16KV bus. The undervoltage relays are connected in a two-out-of-two logic arrangement to prevent spurious trips. The undervoltage relays are set to trip at approximately 92% of bus voltage and have a built in 10 second time delay to prevent momentary voltage drops (eg. motor starts) from actuating the system.

The five minute time delay will allow the operator time to initiate corrective action during non-accident conditions.

DISCUSSION The attached proposed Technical Specification revision (Attachment A) contains limiting conditions for operation, survellience requirements, trip setpoints with minimum and maximum limits and allowable values and allowable t

values for the second level of undervoltage protection sensors and associated time delay devices as required by reference 4, item 1(f).

The setpoints included herein are'not as indicated in references (3) and (4) but are those provided for Division III in license NPF-18. This trip setpoint is approximately 91.7 3,1.8% of nominal bus voltage.

'This setpoint ensures that the trip point will remain within a range which will preclude operation outside the qualified voltage range.

' Since the logic for both the " loss of voltage" and " degraded voltage" is two-out-of-two instruments, action 37 is revised and new action 39 is written to allow an. instrument to be placed in the tripped condition (which still provides the trip function capability) with operation allowed to continue.

Since the likelihood of a degraded voltage condition is very unlikely (reference 5) and the " loss of voltage" undervoltage trip channels provide the primary function of shedding loads and starting the diesel generator, upon a total loss of power, a longer time with this portion unavailable should be allowed. Therefore action 39 allows 7 days without an automatic degraded voltage function for one ESF division provided the other two divisions' degraded voltage protection is operable. The offsite power feed to the emergency bus could still be tripped manually if required.

Table 3.3.3-1 is also clarified in this request such that it specifies that there are two undervoltage relays (instruments) both of which are required to trip to cause the trip function to occur. Footnote (a) is revised to reflect this distinction.

Reference (3) will be revised at the next annual update.

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