ML20126J794
| ML20126J794 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 01/04/1992 |
| From: | Robert Schaaf Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9301060300 | |
| Download: ML20126J794 (6) | |
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UNITED ST ATEs 4
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January 4, 1992
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Docket No. 50-446 LICENSEE: Texas Utilities Electric Company (TV Electric)
FACILITY:
Comanche Peak Steam Electric Station, Unit 2 (CPSES)
SUBJECT:
SUKMARY OF MEETING ON PRESSURIZER SURGE LINE LEAK-BEFORE-BREAK ANALYSIS BACKGROUND TV Electric has proposed the use of the leak-before-break (LBB) methodology to justify elimination of pipe rupture is the design basis for a number of piping runs within the reactor coolant pressure boundary, including the pressurizer surge line (PSL). The requirement to postulate pipe rupture as the design basis of the PSL results in the need for additional plant hardware (i.e., pipe whip restraints, jet shields) to mitigate the consequences of postulated pipe breaks. Demonstrating that the PSL meets LBB criteria would allow the applicant to eliminate the requirement for this additional hardeare.
The use of LBB methodology was allowed by a revision to the general design criteria contained in 10 CFR 50 Appendix A.
Proposed LBB evaluation criteria were published in draft Standard Review Plan (SRP) Section 3.6.3.
The LBB analysis requires determination of the limiting location of the piping run in question, followed by demonstration that there is adequate margin between the leakage size flaw and the critical size flaw to ensure detection of the postulated flaw prior to rupture of the line.
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Following the applicant's submittal of their LBB analysis for the PSL (WCAP-13100 (proprietary) and WCAP-13101 (non-proprietary)), the staff performed independent flaw size calculations which resulted in a significantly larger leakage size flaw than was calculated by the applicant's contractor (Westinghouse). When this greater size leakage flaw was factored into the applicant's LBB analysis, it resulted in a reduction of margin which was not considered acceptable by the staff.
DISCUSSION The applicant requested a meeting to discuss the differences in the calculated leakage size flaws and to present justification for acceptance of the applicant's calculated flaw size. The meeting was held on November 4,1992, t
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Westinghouse representatives summari.'ed the analysis, emphasizing the extensive conservatism used in deteruining the leakage flaw size and the very low probability of occurrence of the limiting load case.
The staff acknowledged these points; but maintained that these conservative assumptions are important in determining the acceptability of LBB analysis.
The Westinghouse representatives also provided a comparison of the proprietary code used in the applicant's LBB analysis with the industry standard code (PICEP) used by the staff to determine the leakage flaw size.
The results of both codes were compared to limit ~' experimental data.
The staff questioned the data chosen for the comparison, particularly the limited number of points in the data set.
In general, the staff expressed the opinion that the Westinghouse leakage flaw code required additional benchmarking against experimental data.
The staf f noted that the method used by Westinghouse to calculate the critical flaw size (a limit-load approach) was highly conservative for this case. The use of more advanced methods acceptable to the NRC for calculating the critical flaw size was discussed as an alternative means of obtaining the required margin for acceptance of the leak-before-break analysis for the pressurizer surge line.
in order to perform an independent calculation of the critical flaw size using a more advanced elastic-plastic fracture mechanics code (NRCPIPE), the staff requested that the applicant provide material property data (in the form of J-resistance (J-R) curves) for the weld material and the pipe base material at the critical location (node 1020).
The staff also requested Ramberg-Osgood data (i.e., stress-strain data) for the weld and pipe base materials.
If actual data are not available, the staff requested that the applicant supply representative data, with justification for its selection. The NRC will review this issue further following additional applicant analysis of flaw size calculations.
A list of meeting attendees is providea as an enclosure to this meeting summary. Material distributed at the meeting contained proprietary information and is not enclosed with this meeting summary. A non-propri
~y version will be provided by the applicant and placed in the Public Docun Rooms.
Original Signed By Robert G. Schaaf, Project Engineer Project Directorate IV-2 Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
Enclosure:
Meeting Attendees List cc w/ enclosure:
See next page
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Westinghouse representatives summarized the analysis, emphasizing the extensive conservatism used in determining the leakage flaw size and the very low probability of occurrence of the limiting load case. The staff acknowledged these points; but maintained that these conservative assumptions are important in determining the acceptability of LBB analysis.
The Westinghouse representatives also provided a comparison of the proprietary code used in the applicant's LBB analysis with the industry standard code (PICEP) used by the staff to determine the leakage flaw size.
The results of both codes were compared to limited experimental data.
The staff questioned the data chosen for the comparison, particularly the limited number of points in the data set.
In general, the staff expressed the opinion that the Westinghouse leakage flaw code required additional benchmarking against experimental data.
The staff noted that the method used by Westinghouse to calculate the critical flaw size (a limit-load approach) wa3 highly conservative for this case. The se of more aovanced methods acceptable to the NRC for calculating the critical flaw size was discussed as an alternative means of obtaining the required margin for acceptance of the leak-before-break analysis for the pressurizer surge line.
pg In order to perfor:n an independent calculation of the critiga[ flaw size using a more advanced elastic-plastic fracture mechanics cme (6Q&W), the staff requested that the applicant provide material proper +y data (in the form of J-resistance (J-R) curves) for the weld material and the pipe base material at the critical location (node 1020).
The staff also requested Ramberg-Osgood data (i.e., stress-strain data) for the weld and pipe base materials.
If actual data are not available, the staff requested that the applicant supply representative data, with justification for its selection. The NRC will review this issue further following additional applicant analysis of flaw size calculations.
A-list of meeting attendees is provided as an enclosure to this meeting-summary. M;terial distributed at the meeting contained proprietary information and is not enclosed with this meeting summary. A non-proprietary version will be provided by the applicant and placed in the Public Document Rooms.
Robert G. Schaaf, Project Engineer Project Directorate IV-2 Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
Enclosure:
Meeting Attendees List cc w/ enclosure:
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cc w/ enclosure:
Senior Resident Inspector Jack R. Newman, Esq.
U.S. Nuclear Regulatory Commission Newman & Holtzinger P. O. Box 1029 1615 L Street, N.W.
Granbury, Texas 76048 Suite 1000 Washington, D. C.
20036 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Chief, Texas Bureau of Radiation Control 611 Ryan Plaza Drive, Suite 1000 Texas Department of Health Arlington, Texas 76011 1100 West 49th Street Austin, Texas 78756 Mrs. Juanita Ellis, President Citizens Association for Sound Energy Jonorable Dale McPherson 1426 South Polk County Judge Dallas, Texas 75224 P. O. Box 851 Glen Rose, Texas 76043 Owen L. Thero, President Quality Technology Company Mr. William J. Cahill, Jr.
Lakeview Mobile Home Park, Lot 35 Grcsp Vice President 4733 East Loop 820 South TU Electric Fort Worth, Texas 76119 400 North Olive Street, L.B. 81 Dallas, Texas 75201 Mr. Roger D. Walker, Manager Regulatory Affairs for Nuclear Engineering Organization Texas Utilities Electric Company 400 North Olive Street, L.B. 81 Dallas, Texas 75201 Texas Utilities Electric Company c/o Bethesda Licensing 3 Metro Center, Suite 610 Bethesda, Maryland 20814 William A. Burchette, Esq.
Counsel for Tex-La Electric Cooperative of Texas Jorden, Schulte, & Burchette 1025 Thomas Jefferson Street, N.W.
Washington, D.C.
20007 GDS Associates, Inc.
Suite 720 1850 Parkway Place Marietta, Georgia 30067-8237
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a ENCLOSURE 1 HEETING ATTENDEES HEETING W2TH TU ELECTRIC NOVEMBER 4, 1992 TV ELECTRIC D. Woodlan C. Corbin D. iiencher WESTINGHOUSE D. Roarty B. Maurer C. Benton J. Schmertz lE R. Schaaf J. Strosnider S. Sheng K. Wichman A. Hiser T. Bergman
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