ML20206F271
| ML20206F271 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 11/16/1988 |
| From: | Johnson I COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| References | |
| 5341K, NUDOCS 8811210072 | |
| Download: ML20206F271 (3) | |
Text
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g~) One First National Plata, Chicago, Illinois Commonwealth Edison
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j Chicago, Illinois 60690 November 16, 1988 Mr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Quad Cities Station Units 1&2 Detailed Control Room Design Review (DCRDR) Human Engineering Discrepancy (HED) No. 1.1.A/VL-1, V-21 Index 410, 427, Clarlfication of RCIC Trip Throttle Valve Modification NRC_Roclel._Hg. 50-254_& 265 References (a) Letter from J.R. Wojnarowski (CECO) to J.A. Zwolinski (NRC) dated December 29, 1985.
(b) Letter from I.M. Johnson (CECO) to T.E. Murley (NRC), "DCRDR Schedule", dated June 17, 1988.
Dear Mr. Murley,
The purpose of this letter is to clarify the subject HED (reference a) as requested by members of your staff during an August 9, 1988 teleconference. The purpose of the teleconference was to discuss the reference (b) letter which provided clarification of Ceco's response to this HED finding. During the NRC teleconference, it became evident that the HED finding also required clarification. As a result, CECO agreed to rewrite the subject HED which can be found in Attachment A to this letter.
Commonwealth Edison considers this HED to be closed and no modifications are required for compliance with this HED.
Please direct any questions regarding this matter to this office.
Ve y t r
I.M. Johnson Nuclear Licen ng Administrator rf Attachmer.t. A cc A. B. Davis - NRC Region III Administrator T. Ross - NRR QC Resident Inspector
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"Attachm2nt A" Quadj:lties Station l{EILgarI_getive Actions Index: 0410, 0427 04 HED No.: 1.1.1.A/VL-1, 1.1.1.A/V-21 Category: 1 Level: A EIMD1HS (a)
In the case of HED 410 it was determined that resetting the RCIC turbine after a trip would be a time critical operation, when RCIC was being used to restore / control reactor pressure vessel pressure or level. This would have to be done locally by an equipment attendant.
(b)
Als", in the case of HED 410 it was determined that the ten years of operating history (i.e. prior to 1986) of the RCIC system had shown it to be subject to frequent spurioun overspeed trips.
(c)
In the case of HED 427 test valv-position indication was felt to be necessary to provide the operator with some feedback mechanism to enable him (her) to prevent RCIC turbine trips resulting from overspeed during a RCIC system surveillance.
Etaponse (a) The RCIC trip throttle valve currently requires local manual reset subsequent to a trip. This ensures that an operator is despatched locally to assess the RCIC system condition and reset the trip throttle valve. This would be a time critical operation, if the RCIC system was being utilized. However, the RCIC system is not safety related and has a backup system (e.g.
HPCI System.
In CECO's efforts to Improve RCIC System reliability, Ceco has initiated a modification to close the fast acting trip throttle valve (rather than the steam supply valve) on a RCIC pump low suction pressure turbine trip and the RCIC turbine high exhaust pressure trip. The closure of the trip throttle valve on these two trips as well as the RCIC turbine mechanical overspeed trip provide the required protection for the RCIC pump and turbine.
As a result, CECO believes that remote reset of the trip throttle valve is not prudent and local reset provides for local inspection of the turbine subsequent to these trouble trips.
(b) Quad Cities Station has completed corrective actions which have eliminated spurious overspeed trips. These actions include removal of the RCIC turbine electrical overspeed trip and changes to the governor valve hydraulle oil piping. No spurious overspeed problems have occurred since implementation of these corrective actions.
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(c) The RCic test valve is utilised during system testing to provide the necessary pressure drop to operate RCIC at rated flow.
During the test mode of operation the RCIC pump is discharging Into the condensate storage tank which is at a low pressure.
I RCIC delivers rated flow at approximately a 1250 psig discharge pressure. As a result, the test val a must provide for a pressure drop of over 1200 psig during testing. The test valve must be nearly closed to achieve this pressure drop and small changes is position will cause substantlal changes in RCIC turbine speed. When operating the test valve from the control room overspeed trips have been experienced.
Quad Cities Station has revised the RCIC surveillance procedure to simulate auto initiation more closely which has eliminated overspeed trips during the surveillance. This includes fast start of the RCIC turbine and local raanual presetting of the test valve. As a result Test valve position Indication will not be needed.
The above corrective actions have eliminated spurious overspeed problems and the need for test valve position indicution. No overspeed problems have occurred since implementation of these corrective actions.
In addition, remote reset capability is not considered prudent for the RCIC trip throttle valve. Commonwealth Edison Co. believes that sufficient corrective action has been expended on this HED.
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