ML20058A270
| ML20058A270 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 11/15/1993 |
| From: | Rehn D DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9312010014 | |
| Download: ML20058A270 (6) | |
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Dielhw Company DLRnn Catawba Kuclear Generation Depertment Hre14esident 4800 ConcordRoad (80318313205 OMce t
Yorie, SC24745 (803)331306 Far i
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DUKEPOWER November 15,1993 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C.
20555
Subject:
Catawba Nuclear Station, Unit 1 Docket No. 50-413 Supplement to Technical Specification Amendment Renewal Of Steam Generator Tube Interim Plugging Criteria for Unit 1 Cycle 8 On October 5,1993, Catawba Nuclear Station submitted a proposed Technical Specification Amendment requesting renewal of the voltage-based steam generator tube interim plugging.
i criteria for Unit 1 for Cycle 8. This submittal was discussed with the NRC staff during a teleconference which was held on October 28,1993. During this discussion, the NRC staff requested that Catawba provide the bases for excluding data points in Table 4-1 of WCAP-13854 from the burst correlation of Figure 4-1.
Please find attached the information requested.
This attachment does not include any information which is proprietary to EPRI or Westinghouse.
The attachment references the EPRI 3/4 inch data report, NP-7480-L, Volume 2, for additional detail on the evaluations performed to exclude data from the correlations. It was expected that this report would be submitted by EPRI to the NRC during the week of November 8,1993. However, the attachment to this letter adequately justifies deletion of.
the data from the correlation.
Pursuant'to 10 CFR 50.91 (b)(1), the appropriate South Carolina officialis being provided a copy of this letter.
. Very truly yours, M /1
/VJ A[/
- D. L. Rehn
- RKS/.
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Attachment 03120106i4 931115 g
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Nuclear Regulatory F mmission November 15,1r Page 2 P
xc: Mr. S. D. Ebneter l
Regional Administrator, Region II U. S. Nuclear Regulatory Commission 101 Marietta Street, NW, Suite 2900 Atlanta, GA 30323 7
Mr. Heyward Shealy, Chief Bureau of Radiological Health South Carolina Department of Health &
Environmental Control 2600 Bull Street Columbia, SC '29201 Mr. R. J. Freudenberger NRC Resident Inspector Catawba Nuclear Statien Mr. Robert E. Martin, Project Manager ONRR Mr. William T. Russell,. Associate Director
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Inspection & Technical Assessment ONRR American Nuclear Insurers c/o Dottie Sherman, ANI Library l
The Exchange, Suite 245 270 Farmington Avenue Farmington, CT 06032 M & M Nuclear Consultants 1166 Avenue'of the Americas I
New York, NY - 10036-2774 INPO Records Center Suite 1500 1100 Circle 75 Parkway Atlanta, Georgia 30339 j
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U. S. Nuclear Regulatory Commission Page 3 D. L. Rehn, being duly sworn, states that he is Site Vice-President, Catawba Nuclear Station; that he is authorized on the part of said company to sign and file with the Nuclear Regulatory Commission this revision to the Catawba Nuclear Station Technicel Specifications, Appendix A to License No. NPF-35; and that all statements and matters set forth therein are true and correct to the best of his knowledge.
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D. L. Rehn
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Subscribed and sworn to before me this /5 4 day of A/n v.
,1993.
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AA%w On Nothy Public
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My Commission Expires:
Nov 2/,c2000 l
1
Bases for Excluding Indications from Burst Correlation The bases for excluding pulled tube and model boiler test results.- m the data base used to support alternate repair criteria are described in EPRI Repon NP-7480-L, Volumes 1 and 2. These reports describe the ARC data base with Volumes 1 and 2 providing the 7/8 inch and 3/4 inch tube diameter data, respecdvely.
Statistical analyses of the data were performed to identify data points with potential outlier behavior for further review. The test results for these potential outliers were reviewed for measurement errors with regard to the bobbin voltage, burst pressure and leak rate measurements. In addition, crack morphologies for the potential outliers were compared with the remaining data. This review led to identification of some specimens with bad data that were then excluded from the data base. In'some cases, the crack morphologies were found to be atypical of the data base and if the associated data point was conservative (high burst pressure or low leak rate), the data point was excluded from the data case.
For some potential outliers, no justifications were found to exclude the data from the data base. These evaluations of the potential outliers were reviewed by the EPRI ARC Committee and are described in NP-7480-L, Volume 1, Revision 1 and Volume
- 2. These reports provide thejustification for excluding data from the ARC correlations as requested in draft NUREG-1477.
The NRC has requested the basis for excluding data given in Table 4.1 of WCAP-13854 from the Catawba-1 burst correlation. These bases are summarized in Table 1.
Table 1 includes the sections of EPRI Report NP-7480-L, Volume 2 which describe the associated data and potential outlier evaluations. Burst tests performed for the indication within a TSP are not included in the ARC correlation which is based on free span burst tests. The presence of the TSP provides constraint against bur'st and results in a much higher burst pressure than a free span burst. Plant S, R28C41 was an unacceptable burst test as a burst is defined as a fish-mouth type opening with tearing at the crack tips. ' This burst test resulted in no tearing and the test did not even open over the full corrosion macrocrack length. Plant R-1 (Catawba-1),
Specimen R7C71 had a recorder malfunction during the burst test such that the pressure at burst was erroneously recorded as reported by the experimentalist.
Specimen 591-3 was unacceptably prepared in the model boilers as the cracking Page 1 of 3
extended to within a Teflon spacer used to support the TSP in addition to the desired
' cracking within the TSP. The six model boiler specimens noted at the bottom of Table 1 were deleted from the 3/4 inch data base by the experimentalist and are not discussed in the EPRI report.
Model boiler specimen 598-1 is the only data point excluded on the basis of crack -
morphology as this specimen had three large parallel throughwall cracks with a very large bobbin voltage atypical (over 40 volts higher than any other data point) of the remaining data base. The remaining specimens were excluded as having unacceptable measurements.
It was also requested by the NRC that an additional burst correlation be provided that adds questionable exclusions back into the correlation data base. The only excluded data point that involves significant judgment for excluding from the data base is model boiler specimen 598-1. This specimen was added to the burst correlation data and an additional regression analysis performed. It was found that the addition of specimen 598-1 had insignificant influence on the burst correlation and resulted in a negligible change (~0.2%) in the voltage at the lower 95% confidence level for a burst pressure of 3 x APyo.
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i Table 1.
Basis for Excluding Data out of Table 4.1 from the Catawba-1 Burst Correlations Basis for Excluding Indications EPRI m Tube TSP from Tube Burst Correlation Report Status Plant E-4 R19C35 2
Burst inside TSP. Yields much higher 4.4 burst pressure than free span burst tests of ARC data base.
R45C54 2
Burst inside TSP R47C66 2
Burst inside TSP Plant S R28C41 1
Incomplete burst test - burst opening 2.5,4.5 length less than macrocrack length (no tearing)
Plant R-1 R7C71 3
Test recorder malfunction 2.2,4.3 Model Boiler Specimens 591-3 Unacceptable specimen preparation due 5.6 to bobbin voltage influenced by cracks in model boiler Teflon spacer below TS_P as well as cracking within TSP.
This results in two bands of cracks.
598-1 Bobbin voltage (64.93 volts) and three 5.6 large throughwall~ indications not prototypic of field indications and single data point >20 volts unduly influences burst correlation 593-4, 595-4, These bobbin NDD specimens all burst 596-1, 597-4, at a welded joint made to extend the 603-4, 604-4 specimen length for burst testing and are not valid tests. These data have been excluded from the 3/4 inch data base discussed in the EPRI report.
Note 1. EPRI Report NP-7480-L, Vol. 2 Page 3 of 3