ML20212H283
| ML20212H283 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/26/1987 |
| From: | Allen C COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20212H288 | List: |
| References | |
| 2779K, NUDOCS 8703060065 | |
| Download: ML20212H283 (4) | |
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, Commonwealth Edison
, Ono First National Plaza, Chicago, Illinois e
s
' Address Reply to: Post Offce Box 767 N-Chicago, Illinois 60690 0767 February 26, 1987 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
LaSalle County Station Unit 2 Proposed Amendment to Technical Specification for Facility Operating License NPF-18 Low and Degraded Grid Voltage NRC Docket No. 50-374 References (1): Facility Operating License NPF-18 (Unit 2), Condition 2.c.(ll).
(2):
E.G. Adensam letter to D.L. Farrar dated May 9, 1986 transmitting Amendment 41 to NPF-ll and Amend.nent 22 to NPF-18.
(3): FSAR Question 40.102.
(4): Safety Evaluation Report, NUREG-0519, Section 8.2.2.2.
Dear Mr. Sir:
pursuant to 10 CFR 50.90, Commonwealth Edison proposes to amend Appendix A, Technical Specification, to Facility Operating License NPF-18.
This amendment change is being submitted for your staff's review and approval and is in accordance with Reference (1).
This proposed amendment revises the Technical Specifications to include modifications that will be installed on Division I in Unit 2 during the first refueling outage in accordance with Reference (1). The changes proposed in this submittal are the same as those approved in reference (2) for Divisions I, II and III of NPF-ll and Divisions II and III of NPF-18.
The installation of this modification to Unit 2 Division I will make the protection the same for all divisions and this proposed amendment will reflect this in the Unit 2 Technical Specifications, NPF-18.
Approval of the attached proposed amendment is requested prior to startup for Unit 2 - Cycle 2.
This is currently scheduled for May, 1987.
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US NRC February 26, 1987 Attachment A provides background and discussion. The proposed Technical Specification changes are enclosed in Attachment B.
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 this office.
Very truly yours, C. M. Allen Nuclear Licensing Administrator Im Attachments A: Background and Discussion B: Technical Specification Change to NPF-18 C: Evaluation of Significant Hazards Consideration cc: Regional Administrator Region III Inspector - LSCS Dr. A. Bournia - NRR M. C. Parker - State of Illinois SULSCRlBED and S N to of _ f melhnAd _ j day befor this
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ATTAQWENT A R
TECHNICAL SpBCIPICATION CHANGE RBOURST LASALLE COUNTY STATION UNITS 1 AND 2 BACKGROUND AND DISCUSSION SACKGROUND As indicated in reference (2) 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-18 license conditions (references 1), 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 ESP bus will automatically disconnect from the offsite power 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 i
' 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 i
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,
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'! DISCUSSION The' attached proposed Technical Specification revision (Attachment A) contains the limiting conditions for operation and the surveillance requirements, for the second level of undervoltage protection sensors and associated time delay devices as required by reference 4, item 1(f), for the Unit 2, Division 1 ESP Bus. The same changes to the Technical Specifications, for Unit 1, Divisions 1, 2 and 3 and Unit 2, Division 2 and 3 ESP Buses were approved by the NRC in reference (2). This submittal will make the changes already approved in Amendment 22 to the LaSalle County Unit 2 Operating License NPP-18 applicable to the Unit 2, Division 1 ESP Bus.
The proposed changes are as follows:
(Refer to Attachment B) 1)
Table 3.3.3-1, Section D Delete the reference to Division 2 and 3 thus making the Technical Specification applicable to all three ESP Divisions.
2)
Table 3.3.3-2, Section D.2.a.1 - Change the Technical Specification to read " Divisions 1, 2 and 3".
3)
Table 4.3.3-1, Section D.2 - Delete the reference to Division 2 and 3 thus making the Technical Specification applicable to all three ESF Divisions.
The modifications to the Unit 2, Division 1 ESF Bus had not been installed prior to this refuel outage. The modifications are scheduled to be completed during the first Unit 2 refuel outage, as required in the Unit 2 License Conditions (see reference (1)). Therefore, this amendment to the Unit 2 Technical Specifications must not become effective until startup following the first refuel outage.
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