View source for U-601311, Forwards Rev 0 to QUAD-1-87-004, Nonsafety-Related Control Sys Failure Analysis & Proprietary EAS-18-0388, Special Transient Event Analysis to Support Control Sys Failure Analysis for Clinton.... Proprietary Rept Withheld

{{Adams
| number = ML20206G067
| issue date = 11/18/1988
| title = Forwards Rev 0 to QUAD-1-87-004, Nonsafety-Related Control Sys Failure Analysis & Proprietary EAS-18-0388, Special Transient Event Analysis to Support Control Sys Failure Analysis for Clinton.... Proprietary Rept Withheld
| author name = Holtzscher D
| author affiliation = ILLINOIS POWER CO.
| addressee name = 
| addressee affiliation = NRC OFFICE OF ADMINISTRATION &amp; RESOURCES MANAGEMENT (ARM)
| docket = 05000461
| license number = 
| contact person = 
| document report number = U-601311, NUDOCS 8811220035
| package number = ML19295G693
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC
| page count = 3
}}

=Text=
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U-601311 L47-(11-18)-LP 8E.100c llLINDIS POWER OOMPANY CLINTON PontR STATION. P.o. BCx 678. CliNTCN, ILLINCrS 61727 November 18. 1988 10CFR50.36 Docket No. 50-461 Document Control Desk Nuclear Regulatory Ccemission Washington, D. C. 20555

==Subject:==
Clinton Power Station License Condition 4, Control System Failures

==Dear Sir:==

The Clinton Safety Evaluation Report (SER) Outstanding Issue number 15 deals with multiple non-safety control system failures resulting from high energy line breaks, common power source failures or sensor / sensor line malfunctions. The NRC staff's concern was that these causes could lead to combinations of non-safety control system failures that would result in consequences more severe than those analyzed in FSAR Chapter 15.
Illinois Power Company (IP) provided the results of a review of the control system failures issue in letter U-0580, dated December 9, 1982. This assessment indicated that the effects of control system failures would be bounded by the existing FSAR Chapter 15 analyses.        As a result of an NRC request for additional information in March of 1986, it was determined that a reanalysis would be required to resolve this irsue. (The original analysis did not appropriately consider the effects of all non-safety control system failures on the FSAR chapter 15 events.) The requirement for reanalysis became License Condition 4      The scope of this reanalysis was defined in IP letters U-600536 dated April 17, 1986 U-600571 dated May 15, 1986 and U-600634 dated July 16. 1986. The purpose of this letter is to transmit the results of this reanalysis which was conducted by Quadrex Energy Services Corporation (see attachea Quadrex report).
The approach taken in the reanalysis was to identify those non-safety control systems that could affect reactor parameters. The failure modes of these systems were identified. Dif ferent combinations of these failures were applied to the existing Chapter 15 events and the results were qualitatively assessed to identify event sequences that may not be bounded by the existing FSAR Chapter 15 analysis. Event sequences that were identified as not being bounded by the existing analyses were included in a new transient analysis by General Electric.
8811220035 891118 FDR       ADOCK 05000461 P                      PDC                 ,   !
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i U-601311 L47-(11-18)-LP 8E.100c The worst-case event identified in this report is a loss of feedwater heating with turbine trip event. General Electric has performed a transient analysis of this worst-case event and has shown that fuel dismage would not occur and radfological consequences would be limited to the activity released to the cuppression pool as a result of safety / relief valve actuation. It should be noted that the General Electric analysis a6sumed a 100'F loss of feedwater temperature which is consistent with USAR Section 15.1.1. Actual experie'1ce at Clinton Power Station (CPS) (see LER 88-25) has shown that the current design of the feedwater controls at CPS will allow a greater than 100'T drop in feedwater temperature to occur. The CPS operstions staff has b=en provided procedural guidance hat directs them to scram the reactor if a loss of feedvster heating in excess of 100'F occurs. This is an interim solution and IP is investigating various opticas to permanently resolve this issue. However, because of the procedural guidance provided to the operators, tha General Electtic analysis for this event is valid.
In accordance with 10CFR2.790, IP has identified the General Electric Analysis EAS-18-0388 contained in this letter as proprietary, therefore it is exempt from disclosure.
IP concludes that CPS would be able to withstand the effects of the worst-case non-safety control system failure. IP believes that this report satisfias the requirements of License Condition C.(4) and that consideration should therefore be given to deleting this item f rom the Clinton Operating License. If you have any questions, contact ce at (217) 935-8821 extension 3400.
Sincerely yours,
                                                               ,D. L. Holtzscher f
Acting Manager - Licensing and Safety AJH/pgc Attachment ect NRC Resident Office NRC Region III, Regional Administrator l                            NRC Clinton Licensing Project Manager Illinois Department of Nuclear Safety

i i Illinois Power Company Corrections to Quadrex Report 1-87-004
: 1)               Page 2-5 section dealing with feedwater failure modes. The feedvater pump discharge vafves to the condenser open upon loss of instrument air.
Air is not required for them to open.
: 2)               Page 3-8 second paragraph. The reference listed should be FSAR table 15.2.1-1 rather than FSAR table 15.3.2-2

==Reference:==
1elephone conversation record dated October 31. 1988 VP-88-029. Phone conversation between Illinois Power and Quadrex Energy Services Corporation.
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