ML17174B014
| ML17174B014 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, LaSalle  |
| Issue date: | 11/26/1991 |
| From: | Olshan L Office of Nuclear Reactor Regulation |
| To: | Kovach T COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 9112090429 | |
| Download: ML17174B014 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 Docket Nos. 50-237, 50-249 50-254, 50-265 and 50-373, 50-374 Mr. Thomas J. Kovach Nuclear Licensing Manager Commonwealth Edison Company-Suite 300 OPUS West II I 1400 OPUS Place Downers Grove, Illinois 60515
Dear Mr. Kovach:
November 26, 1991
SUBJECT:
REVIEW OF RESOLUTION TO ALTERNATE ROD INJECTION DIVERSITY ISSUE AT DRESDEN, QUAD CITIES, AND LASALLE In-a letter dated June 6, 1989, the staff concluded that the Rosemount trip units and the actuation relays in the Alternate Rod Injection (ARI) system for Dresden 1 Quad Cities, and LaSalle are not diverse from the reactor protection system lRPS) and requested that you provide a schedule for resolution of the diversity issues.
By letters dated March 15 and August 15, 1991, you submitted a response to address the resolution to the ARI system diversity issues.
You committed to replace the Rose.mount trip units at all six units during the first refueling outage after June 1, 1992.
We find this resolution and schedule acceptable.
With respect to the actuation relays at Dresden and Quad Cities, you proposed an alternative to the staff position requiring the replacement of the actuation relays. The basis is as follows:
(a) The Agastat relays installed in the AR' and RPS systems are simple devices compared to the Rosemount triµ units and the failure modes of these relays are more understood. The RPS relays are normally energized and must be de-energized to insert control rods, while the ARI relays are normally de-energized and must be energized to insert control rods. This type of functional diversity based on opposite energization states for actuation of relays provides no evidence of (b) a credible common mode failure which will prevent both relays from changing contact position to prevent insertion of control rods.
Based on the relay failure data available to date (NPRDS data base),
no applicable common mode failure of these relays with opposite
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energization states has been evidenced by the failure data.
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- Mr. Thomas November 26, 1991 You concluded that a conunon mode failure either due to manufacturer fault or power failure would actuate* either an ARI or RPS trip function. Therefore, the existing relays, by their design to actuate in opposite energization*
states, meet the.underlying purpose of the ATWS Rule and r~placement of these relays is not necessary. The cost of the significant design change needed to replace the relays is not justified based on the extremely low probability of an unknown conunon mode relay failure.
We have evaluated your justification and conclude that the diversity provided for system actuation relays adequately minimizes the likelihood of conunon mode failure between the ARI and RPS and meets the provisions of 10 CFR 50.62 and, therefore, is acceptable.
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Sincerely, Origtnaf Signed By:.
Leonard N. Olshan, Project Manager Project Directorate LII-2 Division of Reactor Projects - III/IV/V Office of Nuclea~ Reactor Regulation
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Mr. Thomas J. Kovach Corrmonwealth Edison Company cc:
Michael I. Miller, Esq.
Sidley and Austin One First National Plaza Chicago, Illinois 60690 Mr. J. Eenigenburg Pl~nt Superintendent Dresden Nuclear Power Station Rural Route 11 Morris, Illinois 60450 U. S. Nuclear Regulatory Corrmission Resident Inspectors Office Dresden Station Rural Route #1 Morris, Illinois 60450 Chairman Board of Supervisors of Grundy County Grundy County Courthouse Morris, Illinois 60450 Regional Administrator Nuclear Regulatory Commission, Region III 799 Roosevelt Road, Bldg. #4 Glen Ellyn, I"llinois 60137 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Robert Neumann Office of Public Counsel State of Illinois Center 100 W. Randolph Suite 11-300 Chicago, Illinois 60601 Dresden Nuclear Power Station Unit Nos. 2 and 3
Mr. Thomas J. Kovach ColTITlonwealth Edison Company cc:
Mr. Stephen E. Shelton Vice President Iowa-Illinois Gas and Electric Company P. 0. Box 4350 Davenport, Iowa 52808 Michael I. Miller, Esq.
Sidley and Austin One First National Plaza Chicago, Illinois 60690 Mr. Richard Bax Station Manager Quad Cities Nuclear Power Station 22710 206th Avenue North Cordova, Illinois 61242 Resident Inspector U. S. Nuclear Regulatory Commission 22712 206th Avenue North Cordova, Illinois 61242 Chairman Rock Island County Board of Supervisors 1504 3rd Avenue Rock Island County Office Bldg.
Rock Island, Illinois 61201 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Regional Administrator, Region III U. S. Nuclear Regulatory Conunission 799 Roosevelt Road, Bldg. #4 Glen Ellyn, Illinois 60137 Robert Neumann Office of Public Counsel State of Illinois Center 100 W. Randolph Suite 11-300 Chicago, Illinois 60601 Quad Cities Nuclear Power Station Unit Nos. 1 and 2
- Mr. Thomas J. Kovach Conunonwealth Edison Company cc:
Phillip P. Steptoe, Esquire Sidley and Austin One First National Plaza Chicago, Illinois 60603 Assistant Attorney General 100 West Randolph Street Suite 12 Chicago, Illinois 60601 Resident Inspector/LaSalle, NPS U.S. Nuclear Regulatory Commission Rural Route No. 1 P. O. Box 224 Marseilles, Illinois 61341 Chairman LaSalle County Board of Supervisors LaSalle County Courthouse Ottawa, Illinois 61350 Attorney General 500 South 2nd Street Springfield, Illinois 62701 Chairman Illinois Conunerce Conunission Leland Building 527 East Capitol Avenue Springfield, Illinois 62706 Illinois Department of Nuclear Safety Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Regional Administrator, Region III U. s. Nuclear Regulatory Commission 799 Roosevelt Road, Bldg. #4 Glen Ellyn, Illinois 60137 Robert Neumann Office of Public Counsel State of Illinois Center 100 W. Randolph Suite 11-300 Chicago, Illinois 60601 LaSalle County Station Unit Nos. 1 and 2 Robert Cushing Chief, Public Utilities Division Illinois Attorney General's Office 100 West Randolph Street Chicago, Illinois 60601 Michael I. Miller, Esq.
Sidley and Austin One First National Plaza Chicago, Illinois 60690 Mr. G. Diederich LaSalle Station Manager LaSalle County Station Rural Route 1 P. O. Box 220 Marseilles, IL 61341