ML20236W959
| ML20236W959 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 12/02/1987 |
| From: | Johnson I COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| 3905K, NUDOCS 8712080340 | |
| Download: ML20236W959 (2) | |
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Ccmmenwrith Edlann r
3 One First National Plaza, Chicago. Illinois V
, Address Reply to: Post Office Box"T6F Chicago, Ilhnois 60690 0767 December 2, 1987 1
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Mr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
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Subject:
Quad Cities Station Units 1 and 2 Clarification to Appendix R Exemption Request 12.2 NRC Docket Nos. 50-254 and 50-265 Reference (a): October 1, 1987 letter from I.M. Johnson to T.E. Murley
Dear Mr. Murley:
It was stated in Exemption, Request 12.2 transmitted to you in reference (a) that removal of power from'the individual Reactor Relief Valve is accomplished by opening breakers or pulling fuses. What was not clearly stated and is being clarified by this letter is that removal of power to the Reactor Relief Valves involves removing power to the individual valves and to the logic for the Automatic Depressurization System (ADS). Power is removed to the individual valves by either opening breakers or removing fuses. Power to the ADS logic is removed by turning the ADS inhibit switch to the OFF position.
For a fire in the Control Room, the ADS inhibit switch ~
is turned to the OFF position before leaving the control Room and breakers that supply power to the logic circuit are subsequently openad in the 125v de distribution panel roors.
The ADS inhibit switch is a mechanical switch that opens two contacts. Once opened, two hot shorts must be.present on the circuit for ADS to be initiated. Thus, we feel that taking credit for this control Room action does not present a problem and actually enhances system safety since spurious operation is prevented between the time the inhibit switch is turned to the OFF position and the time the breakers are opened. The opening of the breakers is performed as an additional precautionary measure even though it is not required to prevent spurious initiation of ADS once the inhibit switch is in the OFF position.
8712080340 B71202 PDR ADOCK 0500 4
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=T.E. Murley
- - 2 December-2,-1987 yip:
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'This letter:is being provided as clarification to the Exemption
! Request' 12.2 in anticipation of.the upcoming Quad cities Station Appendix -R
I W compliance audit.
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. 'Please direct;any questions you may have regarding-this matter to
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- this office.
Very truly yours, 4 -
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I. M. Johnson Nuclear Licensing Administrator 3
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cc: ~ T. Ross - NRR
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[i QC Resident; Inspector
. A.B. Davis - RIII i
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