ML052070193
| ML052070193 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 08/03/2005 |
| From: | Ellen Brown NRC/NRR/DLPM/LPD2 |
| To: | Singer K Tennessee Valley Authority |
| Brown Eva, NRR/DLPM, 415-2315 | |
| References | |
| TAC MC6314, TAC MC6386, TAC MC6387 | |
| Download: ML052070193 (9) | |
Text
August 3, 2005 Mr. Karl E. Singer Chief Nuclear Officer and Executive Vice President Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801
SUBJECT:
BROWNS FERRY NUCLEAR PLANT, UNIT 3 - REQUEST FOR ADDITIONAL INFORMATION REGARDING SECOND 10 YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN REQUESTS FOR RELIEF NO. 3-ISI-7, REVISION 1, NO. 3-ISI-12, AND NO. 3-ISI-19 (TAC NOS. MC6314, MC6386, AND MC6387)
Dear Mr. Singer:
By letter dated March 4, 2005, Tennessee Valley Authority (TVA) submitted Relief Requests No. 3-ISI-7, Revision 1, No. 3-ISI-12, and No. 3-ISI-19 for Browns Ferry, Unit 3, from the inservice inspection requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, for the volumetric ultrasonic examination of reactor pressure vessel (RPV) nozzle-to-vessel welds and inner radius sections, residual heat removal system and reactor water cleanup system piping welds, and RPV longitudinal shell welds.
Instead, TVA proposes to perform ultrasonic examination of the accessible areas, to the maximum extent practical, given the component design, and configuration of the subject welds.
Based on our review of your submittal, the U. S. Nuclear Regulatory Commission staff finds that a response to the enclosed request for additional information is needed before we can complete the review. A response is requested within 30 days of the issuance of this letter.
If you have any questions, feel free to contact me at 301-415-2315.
Sincerely,
/RA/
Eva A. Brown, Project Manager, Section 2 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-296
Enclosure:
Request for Additional Information cc w/encl: See next page
ML052070193 NRR-088 OFFICE PDII-2/PM PDII-2/LA EMCB/SC PDII-2/SC NAME EBrown BClayton MMitchell memo dated MMarshall DATE 07/ 25/ 05 07/ 27/ 05 05/ 12/ 05 08/ 03/ 05
SUBJECT:
BROWNS FERRY NUCLEAR PLANT, UNIT 3 - REQUEST FOR ADDITIONAL INFORMATION REGARDING SECOND 10 YEAR INTERVAL INSERVICE INSPECTION PROGRAM PLAN REQUESTS FOR RELIEF NO. 3-ISI-7, REVISION 1, NO. 3-ISI-12, AND NO. 3-ISI-19 (TAC NOS. MC6314, MC6386, AND MC6387)
Dated: August 3, 2005 Distribution:
PUBLIC PDII-2 R/F RidsNrrDlpmLpdii RidsNrrDlpmLpdii2 RidsNrrLABClayton RidsNrrPMEBrown RidsNrrPMMChernoff RidsOgcRp RidsAcrsAcnwMailCenter RidsRgn2MailCenter TChan TMcLellan PPatnaik MMitchell
Enclosure REQUEST FOR ADDITIONAL INFORMATION RELIEF REQUESTS 3-ISI-7, REVISION 1, 3-ISI-12, AND 3-ISI-19 TENNESSEE VALLEY AUTHORITY BROWNS FERRY PLANT, UNIT 3 DOCKET NO. 50-296 1.0 Request for Relief 3-ISI-7, Revision 1, Examination Category B-D, Full Penetration Welds of Nozzles in Vessels 1.1 Typically, there can be significant changes between the design drawings and the as-built conditions of plant components. Clarify whether the design drawings represent as-built configurations. State whether the actual as-built dimensions and curvatures that exist on the surfaces, such as the inner radius and outside weld crowns, are accurately depicted on the submitted drawings. Include whether the outside surface weld crowns are ground flush in the blend radius regions, and, if possible, provide a surface roughness finish value (in root mean square units), for the reactor pressure vessel (RPV) base metal and nozzle-to-vessel welds. How do the Browns Ferry Nuclear Plant (BFN), Unit 3, nozzle-to-vessel weld as-built configurations compare to conditions on the representative specimens used during the Electric Power Research Institution (EPRI) Performance Demonstration Initiative (PDI) qualification?
1.2 Describe the ultrasonic methods that were used, including wave propagation modes and angles of interrogation.
1.3 Submit cross-sectional sketches showing the completed ultrasonic examination volumes for each wave mode and angle used on the subject nozzles. Include in these sketches the required ASME Code examination volumes and state whether the sketches represent the entire circumferential length of the welds, or show limitations to these coverages for specific regions of the welds. Are there any as-built conditions that may impact the examination coverages? Using the sketches and coverages illustrated, describe how the coverage values shown in 3-ISI-7, Revision 1, Table 1 were generated.
2.0 Request for Relief 3-ISI-12, ASME Code Case -577, Examination Category R-A, Risk-Informed Piping Examinations 2.1 Clearly state the base material type(s) and fabrication forms for each of the subject piping welds. For example, for Weld TRHR-3-191, clarify whether this is a statically cast austenitic valve welded to a statically cast austenitic elbow, or a statically cast valve welded to a wrought elbow.
2.2 Describe the ultrasonic methods that were used, including wave propagation modes and angles of interrogation.
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2.3 Submit cross-sectional sketches showing the completed ultrasonic examination volumes for each wave mode and angle used on the subject piping welds. Include in these sketches the required ASME Code examination volume zones and state whether the sketches represent the entire circumferential length of the welds, or show limitations to these coverages for specific regions of the welds. Are there any as-built conditions that may impact the examination coverages, including outside surface weld crowns and surface finishes? If possible, provide a surface roughness finish value (in root mean square units) of the subject piping welds. How do the subject BFN Unit 3 piping weld as-built configurations compare to conditions on the representative specimens used during the EPRI PDI qualification?
2.4 The licensee has implemented a Risk-Informed Inservice Inspection (RI-ISI) program at BFN Unit 3. As such, only a limited number of Class 1 piping welds are being inspected, as opposed to the ASME Code requirement of 25 percent of all Class 1 piping welds.
Discuss why the partial examinations performed on the subject welds provide an adequate basis to conclude that the targeted degradation mechanisms (intergranular stress corrosion cracking and thermal fatigue) would have been detected, if present, in these welds. Discuss other piping weld examinations in these systems that are also subject to the same degradation mechanisms, and why the limited examinations on the subject welds do not impair or undermine the intent of the RI-ISI program. State whether BFN Unit 3 will inspect additional piping welds (not presently being examined) to account for the limited examination volumes of the subject welds and ensure that an adequate level of susceptible material, as required by the RI-ISI program, is being examined.
3.0 Request for Relief 3-ISI-19, Examination Category B-A, Pressure Retaining Welds in the Reactor Vessel 3.1 It has been proposed by industry (the Boiling-Water Reactor (BWR) Vessel and Internals Project), and approved by the U.S. Nuclear Regulatory Commission, that only the longitudinal welds are required to be volumetrically examined to maintain structural integrity of the RPV in a BWR. Relief was requested for 3 of the 15 longitudinal shell welds at BFN Unit 3. Request for Relief 3-ISI-19 states, twelve of the fifteen welds received essentially (i.e., greater than 90 percent) 100 percent coverage. In addition, the actual examination coverage for the three welds included in 3-ISI-19 were listed as 90, 86, and 89 percent, respectively. For comparison purposes, please summarize the actual coverage(s) obtained on the remaining 12 longitudinal shell welds.
3.2 Clearly state what the exact limitations encountered due to the obstructions on the vessel inner surface were. For instance, does insufficient clearance exist to accommodate the inspection tool? Describe the constraints that must be considered to perform an effective examination, and show (through sketches and descriptions) how the interferences preclude a full ASME Code examination. Also, describe if it is possible to deal with these limitations by altering the inspection device.
Mr. Karl W. Singer BROWNS FERRY NUCLEAR PLANT Tennessee Valley Authority cc:
Mr. Ashok S. Bhatnagar, Senior Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Larry S. Bryant, General Manager Nuclear Engineering Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Brian OGrady, Site Vice President Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609 Mr. Robert J. Beecken, Vice President Nuclear Operations Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 General Counsel Tennessee Valley Authority ET 11A 400 West Summit Hill Drive Knoxville, TN 37902 Mr. John C. Fornicola, Manager Nuclear Assurance and Licensing Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Mr. Bruce Aukland, Plant Manager Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609 Mr. Glenn W. Morris, Manager Corporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority 4X Blue Ridge 1101 Market Street Chattanooga, TN 37402-2801 Mr. William D. Crouch, Manager Licensing and Industry Affairs Browns Ferry Nuclear Plant Tennessee Valley Authority P.O. Box 2000 Decatur, AL 35609 Senior Resident Inspector U.S. Nuclear Regulatory Commission Browns Ferry Nuclear Plant 10833 Shaw Road Athens, AL 35611-6970 State Health Officer Alabama Dept. of Public Health RSA Tower - Administration Suite 1552 P.O. Box 303017 Montgomery, AL 36130-3017 Chairman Limestone County Commission 310 West Washington Street Athens, AL 35611