ML19340E964

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Informs That 800827 Ltr Responding to IE Bulletin 80-04 Requires Mod.Main Feedwater Sys Will Be Modified to Close Valves HCV-1103 & HCV-1104 on Containment High Pressure Signal,Not Containment Isolation Actuation Signal
ML19340E964
Person / Time
Site: Fort Calhoun Omaha Public Power District icon.png
Issue date: 11/13/1980
From: William Jones
OMAHA PUBLIC POWER DISTRICT
To: Seyfrit K
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
IEB-80-04, IEB-80-4, NUDOCS 8101160403
Download: ML19340E964 (1)


Text

, CENTRAL FILES PDR:HQ

, LPDR y TIC p- AC a Omaha Public Power District .;..

SMTE 1623 MARNEY OMAMA, NESRASKA 60102 TELEPHONE S36 4000 AR ODE 4 2 November 13, 1980 g ,, c. .

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Mr. K. V. Seyfrit, Director U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

Reference:

Docket No. 50-285

Dear Mr. Seyfrit:

Omaha Public Power District's letter to the Commission dated August 27, 1980, requires modification. The letter was our response to IE Bulletin 80-04 detailing the results of the District's analysis of the Main Steam Line Break (MSLB) event with automatic Auxiliary Feed-water (AFW) actuation. In that response, the District stated that the Main Feedwater (MFW) system for Fort Calhoun would be modified to close valves HCV-1103 and HCV-1104 on a Containment Isolation Actuation Signal j (CIAS), to provide dual isolation of MFW for a MSLB event. This state-ment was an error. The District's intent has always been to close these valves on a Containment Pressure High Signal (CPHS), not CIAS as stated in our letter. MFW is presently isolated by closing valves HCV-1385 and HCV-1386 on CIAS, while future plans are to isolate MFW only on CPHS and this apparently lead to tne error in our letter of August 27, 1980.

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! CIAS results from either a low pressurizer pressure signal or CPHS.

. However, for a small break LOCA or small steam line break, the avail-l ability of the steam generators for heat removal is important for re-covery from these events. The modification of the MFW isolaticn from CIAS to CPHS will maximize heat removal capability for small breaks and assure isolation for MSLB or large break LOCA.

Sincerely,

- /,'-. ,

W. C. Jones Division Manager Production Operations

. WCJ/KJM/TLP:Jmm cc: LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.

Washington, D.C. 20036 81911608fD3