ML20086P455

Clarifies Responses to NRC Bulletin 88-011, Pressurizer Surge Line Thermal Stratification. Westinghouse Analyses Concluded That Vertical Support on Surge Line Must Be Removed from All Four Units Prior to End of 1993

ML20086P455
Person / Time
Site:	Byron, Braidwood
Issue date:	12/19/1991
From:	Chrzanowski D COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
IEB-88-011, IEB-88-11, NUDOCS 9112270028
Download: ML20086P455 (2)

Text

Ccmmonwealth Edisen 1

v 1400 opus Place oowners orovo. Illinois 60515 December 19,1991 Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attn: Document Control Desk

Subject:

- Clarification of Response to NRC Bulletin 8811. Pressurizer Surge Line Thermal Stratification, for Byron and Braldwood Station.

Dyron Station Units 1 and 2 Braidwood Station Units 1 and 2 e NRC Docket Nos. 50 454/455, and 50 45G/457

References:

(a) NRC Bulletin 8811, dated December 20,1988 (b) M.H. Richter letter to U.S. NRC dated March 7,1989.

(c) L.N. Olshan (NRC) letter to T.J. Kovach (CECO) dated May 18,1989.

(d) M.H. Richter (CECO) letter to U.S. NRC dated May 31,1989.

(e) D.L. Taylor (CECO) letter to U.S. NRC dated January 8,1991.

(f) " L. Taylor (CEC 9) letter to U.S. NRC dated April 12,1991.

(g) A.H. Hsla (NRC) letter to T.J. Kovach (CECO) dated June 7,1991.

Reference (a) roquested a!! addressees to establish and implement a program to ensure pressurizer surge line integrity with respect to thermal stratification

. anc striping, and design basis loads. References (b) and (d) arovided the .

Commonwealth Edison Company (CECO) initial response to t11s Bulletin Additionally, Reference (d) indicated that CECO would notify the NRC upon completion of the remaining commitments associated w!th the Bulletin. Reference (e) transmitted the Westinghouse analysis of the Byron and Braidwood Units 1 and 2 Pressurizer Surge considered the effects L. thermal Lines. This of stratification analysis the surge(WCAP 12743/12744)is lines. The analys concluded that a vertical support on the surge line must be removed from all four units prior to the end of 1993.

Also included in the Reference (e) transmittal was the Westinghouse analysic WCAP 12739/12740. This report, also known as the leak before break (LBB) analysis, corcludes that pressurizer surge line breaks should not be considered in the structural design basis of Byron Units 1 and 2 and Braldwood Units 1 and 2 and therefore plant hardware such as whip restraints are not required. Reference (g) arovid 'd the NRC's evaluation and approval of CECO's Bulletin 8811 program, as wel as listing a schedule D for the Byron and Brcidwood pressurizer surge line support removal modifi ation. .

m atoo4: r.,n O

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Office of Nuclear Reactor Regulation 2- Decembe- 19,1991 i

This letter is providing updated information on the pressurizer surge line su) port modification and is also requesting the NRC's review of the previously su amitted pressurizer surge line leak before break analysis.

The schedule in Reference (g) listed a modification date of Spring 1992 for Byron Unit 2 and Fall 1991 for Braldwood Unit 2. As discussed with NRC staff in a December 2,1991 telephone call, the modifications for these two units will not be installed during these stated outages but will be delayed one refueling outage. Thi9 deferral to each unit's subsequent outage does not present any challenge to the original analysis since the target date for the removal of the surge line support is the end of 1993. The new dates for the modification are now Fall 1993 for Byron 2 and Spring 1933 for Brald.sood Unit 2.

The schedule for the other units remains as listed in Reference (g); Spring 1993 for Byron Unit 1 and Fall 1992 for Braidwood Unit 1. The slip in modification schedule is due to the f act that post modification acceptance criteria and final pipo gap clearanca analyces were not finalized in the time necessary to support the modi"ication schedule.

Also discussed in the above listed call to the NRC was CECO's request to have the NRC review the analysis to eliminate the 3ressurizer surge line rupture as the structural design bases for Byron and Braidwood slations. Ac explained in the phone ca!I and Reference (f), the approval of this analysis is not mandatory to su 3 port the surge line modifications; however, it is now apparent that the approval of t 10 surge line leak before break will facilitate this modification. The approval of LBB analysis prior to support modification will allow removal of whip restraint shimming since these restraints would no longer be required. This would preclude any thermal Interference during heat up. ThermalInterference with these whip restraints would require costly re analysis or remodification thereby extending the outage. Also without the LBB appmval, post mod monitoring of line during heat up would result in unnecessary radiation usse to inspection personnel.

For these reasons CECO is requesting NRC approval of the Leak before Break analysis of the Byron /Braidwood pressurizer surge line prior to the Braldwood

( Unit 1 outage currently scheduled for September 1992. Please Inform us if this is i achievabic. I can be contacted at 708/515 7292.

b3 b _[4 David J. Chrzanowski Nuclear Licensing Administrator Generic issues cc: A, B. Davis, Regional Administrator-Rill R. Pulsifer, Project Manager NRR/PDlll 2 A. Hsia, Project Manager NRR/PDill 2 R. Elliott, Project Engineer NRR/PDill 2 S. DuPont, Senior Resident Inspector (Braldwood)

W. Kropp, Senior Resident inspector (Byron)  !

ZNLD/1090/12

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