ML20203K615
| ML20203K615 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 02/24/1998 |
| From: | Stanley G COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9803050157 | |
| Download: ML20203K615 (3) | |
Text
_ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ - _ _ -
t omm<>nw chh i a~,n meany
,J-
!) owners Grove, H. 605;5 5'01 February 24,1998 U. S. Nuclear Regulatory Commission Washington, DC 20555 Attention:
Document Control Desk
Subject:
Byron Station Unit I and Braidwood Station Unit 1 NRC Docket Number: 50-454 and 50-06 Commonwealth Edison's Response to NRC letter dated November 13,1997, regarding 10 CFR 50.72 Notification that Byron 1 and Braidwood I are Outside their Design Basis
References:
1)
M. D. Lynch letter to the Commonwealth Edison Company dated November 13,1997 2)
J. Hosmer letter to NRC Document Control Desk dated January 31,1997, requesting Amendment to the Byron Unit 1 Technical Specifications 3)
- 11. Stanley letter to NRC Document Control Desk dated September 2,1997, requesting Amendment to the Braidwood Unit 1 Technical Specifications 4)
D. Wozniak letter to NRC Document Control Desk dated
[
July 30,1997, transmitting Byron Unit i Operability D
Assessment 97-044 5)
J. Hosmer letter to NRC Document Control Desk dated October 1,1997, transmitting revised Ofr-Site Dose Calculations for Byron L nit I and Braidwood Unit 1 6)
M. David Lynch letter to the Commonwealth Edison
/
Company dated March 28,1997, Extension of the Byron Unit 1, Operating Cycle between Steam Generator Tube Eddy Current inspection l
In the reference 1 letter, the Nuclear Regulatory Commission asked the Commomvealth Edison Company (Comed) to provide information pertaining to 10 CFR 50.72 notifications that Byron Unit I and Braidwood Unit I were outside their design basis. The StafTis concerned that the 10 CFR 50.72 notifications appear to contradict our prior finding that the qualitative measures, Comed
.,-4nn 9803000157 900224 PDR ADOCK 05000454 P
PDR.
l llllllllll K:nla\\bybwd\\stmgen\\circrresp. doc A Unicom Company
a NRC Document Control Desk February 24,1998 implemented at Byron Unit 1 and Braidwood Unit I reduced to a very low value, the probability of throughwall freespan leakage from circumferential cracks.
Therefore, the NRC asked:
I. Whether Coi.?Ed has changed its position on ", the probability of throughwall, free span leakage from circumferential cracks."
/
- 2. Whether Comed has obtained additionalinformation or performed other analyses that could aFeet the NRC's evaluation or understanding of CemEd's pricr proposal to operate Byron Station Unit I and Braidwood Station Unit I without midcycle eddy current inspections for circumferential crack indications.
- 3. Whether Comed has conducted a re-redew of Co.nEd's eddy current data from prior inspections that might afTect Comed's pr:or position that circumferential cracks found in Byron Unit 1 steam generators had taken several cycles to develop.
Comed's Response i
- 1. Comed has not changed its position on leakage as a result of ciraumferential cracks. Comed concurs with the NRC's conclusion that as a result of the detailed inspections conducted during the most recent outages at Byron Unit I and Braidwood Unit 1, the probab' "throughwall, free span leakage due to circumferential cracks in an unlike>y event of MSLB is very low.
2 Comed has not obtained additional mformation or performed additional analyses that would affect Comed's evaluation or understanding of a basis for full cycle operation for Byron Unit I and Braidwood Unit i due to circumferential cracks.
- 3. Comed has not performed any additional re-review of pnor inspection circumferential crack indication:, at Byron Unit I since reviews assessed in your Reference 6 letter.
Comed included an estimate for circumferential crack leakage during a MSI.B, for end of cycle leakage projections performed prior to Fall 1997, as a conservative measure in determining a dose equivalent iodine (DEI) ievel. This assured compliance with the Technical Specifications for Byron Unit I and Braidwood Unit 1,10 CFR Part 100 and GDC 19. These assessments were submitted to the NRC in References 2 through 5.
K:nla\\bybwd\\stmgen\\circrresp. doc
--s
NRC Document Control Desk February 24,1998 it is Comed's current understanding that it is inappropriate to include any J
~
quantitative assessment ofleakage due to circumferential cracks in any essessments related to steam generator tube integrity for steam generators in which detailed inspections have been performed, such as those performed on Byron Unit I and Braidwood Unit 1. Therefore, Comed will no longer include the circumferential crack leakage assessment as part of steam generator tube condition monitorint or operational assessment for these units. These conclusions will continue to be evaluated by in-situ testing ofindications which meet the selection criteria of the EPRI In-Situ Testing Guidelii.e.
If you have any questions concerning this correrpondence please contact this office.
Sincerely, 7
ri Gene Stanley PWR Vice President Cc.
Byron Project Manager, NRR Braidwood Project Manager, NRR Senior Resident inspector, Byron Senior Resident inspector, Braidwood Regional Administrator-R1!i OtTice of Nuclear Safety-iDN K:nla\\bybwd\\stmgen\\circrresp. doc
..