ML20108D229
| ML20108D229 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 04/30/1996 |
| From: | Hosmer J COMMONWEALTH EDISON CO. |
| To: | NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML19355D096 | List: |
| References | |
| NUDOCS 9605070341 | |
| Download: ML20108D229 (3) | |
Text
4 Commonwealth hiison Company 1400 Opus Place l
1 l
Downers Grove,1160515-5701 i
1 April 30,1996 Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn. Document Control Desk
Subject:
Byron and Braidwood Station Units 1 & 2 Application of Leak-Before-Break Methodology to the Primary Reactor Coolant System (RCS)
NRC Docket Numbers: 50 - 454. 455. 456 and 457 l
l l
Reference:
Nuclear Regulatory Commission Reply to R.E. Ginna Nuclear l
l Power Plant Application of Leak Before Break dated June 8,1993 l
\\
2 The Commonwealth Edison Company (Comed) is requesting the Nuclear Regulatory Commission (NRC) to review and approve the attached analysis associated with the justification for the elimination of large primary loop pipe rupture so that this may be excluded from the design basis, per General Design Criteria 4, " Environmental and Dynamic effects Design Bases, " for Byron and Braidwood Station Units 1 and 2. This analysis supports Comed's intent to eliminate dynamic effects as defined by the published broad scope of the final rule with respect to missile generation, pipe whipping, pipe break reaction forces, jet impingement forces, decompression waves within the ruptured pipe and dynamic or nonstatic pressurization in cavities, subcompartments and compartments. This analysis demonstrates that the probability of pipe rupture is extremely low under conditions consistent with the design of the piping. This request excludes application of leak before break (LBB) to: a) pipe rupture of the l
emergency core cooling system, b) cavities, subcompartments and compartments necessary to the containment function, and c) environmental qualification of electrical and mechanical equipment.
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NRC Document Control April 30,1996 Comed is requesting approval of the attached leak before break methodology analysis in its entirety. Previously, Byron and Braidwood applied the leak before break rnethodology for the specific application for the removal of the whip restraints and the jet impingement shields only.
At the time that Byron 1 appi,ed the methodology, General Design Criteria (GDC) 4 had been revised to allow the removal of the restraints and shields. The modification was performed via the 50.59 process.
For Byron 2, Braidwood 1 and Braidwood 2, an exemption was granted from a portion of the requirements of GDC-4.
l Comed also believes that the attached analysis supports Comed's intent to design the replacement steam generator internal components on the basis of reduced loads resulting from the application of LBB to postulated breaks in the primary reactor coolant loop piping. Specifically, the dynamic effects of primary side piping ruptures need not be included in the design basis of the primary side divider plate of the replacement steam generators. Leak before break considerations continues to be valid for the primary coolant loop piping after installation of the replacement steam generators. This approach was previously submitted by the Ginna Nuclear Power Station and approved in the Reference letter.
Additionally, please note that Comed has previously requested and received approval from the NRC to extend LBB, in accordance with revised GDC-4 according to the criteria in NUREG-1061, Vol.3, to stainless steel piping systems that include the reactor coolant bypass line and the safety injection accumulator line for all fours units. The design basis for these lines remains unchanged as a result of this current submittal.
Comed is requesting that the Staff review and approve the attached analysis.
Attachment A contains:
WCAP-14559 Revision 1, " Technical Justification for Eliminating Large Primary Loop Pipe Rupture as the Structural Design Basis for the Byron and Braidwood Units 1 and 2 Nuclear Power Plants"- Proprietary Version, and I
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4 NRC Document Control April 30,1996 4
Attachment B contains:
WCAP-14560 Revision 1, " Technical Justification for Eliminating Large i
Primary Loop Pipe and Rupture as the Structural Design Basis for the j
Byron and Braidwood Units 1 and 2 Nuclear Power Plants"- Non-l Proprietary Version.
Please note that WCAP-14559 Rev 1, " Technical Justification for Eliminating I
Large Primary Loop Pipe Rupture as the Structural Design Basis for the Byron
{:
and Braidwood Units 1 and 2 Nuclear Power Plants" contains information
. proprietary to Westinghouse Corporation and is supported by an affidavit signed L
by Westinghouse, the owner of the information. The affidavit sets forth the basis l
on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in Paragraph (b)(4) of Section 2.790 of the Commission's regulations. Accordingly, l
it is respectfully requested that the information which is proprietary to i
j-
_ Westinghouse be withheld from public disclosure in accordance with 10 CFR l
2.790 of the Commission's regulations.
Correspondence with respect to the proprietary aspects of the items should be addressed to N.J. Liparulo, Manager Nuclear Safety Regulatory and Licensing 1
Activities, Westinghouse Corporation.
i 3
Comed is requesting approval of this analysis by October 15,1996, to support design work relating to the steam generator replacement project.
If you have any questions concerning this correspondence, please contact Denitie Saccomando at (708) 663-7283.
Sinceraly, l John B. HosmerA E /\\b" Engineering Vice President Attachments cc:
G. Dick, Byron Project Manager-NRR R. Assa, Braidwood Project Manager-NRR C. Phillips, Senior Resident inspector-Braidwood Hc Peterson, Senior Resident inspector-Byron Office of Nuclear Safety-IDNS k.nletybwdiLBB4 doc:3
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