ML061360247
| ML061360247 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/04/2006 |
| From: | Crouch W Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MC6314, TAC MC6386, TAC MC6387 | |
| Download: ML061360247 (22) | |
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Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabarna 35609-2000 May 4, 2006 10 CFR 50.55a U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop: OWFN P1-35 Washington, D.C. 20555-0001 Gentlemen:
In the Matter of ) Docket No. 50-296 Tennessee Valley Authority BROWNS FERRY NUCLEAR PLANT (BFN) - UNIT 3 - AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) SECTION XI, INSERVICE INSPECTION (ISI) PROGRAM, SECOND TEN-YEAR INSPECTION INTERVAL
- REQUEST FOR RELIEF 3-ISI-7, REVISION 1 - RESPONSE TO NRC INFORMAL REQUEST FOR ADDITIONAL INFORMATION (TAC NOS. MC6314, MC6386, AND MC6387)
This letter provides TVA's response to an informal NRC request for additional information regarding BFN Unit 3, ASME Section XI Inservice Inspection (ISI) Program, request for relief 3-ISI-7, Revision 1. This request for relief was submitted, with requests for relief 3-ISI-12, and 3-ISI-19, by TVA letter dated March 4, 2005, for NRC review and approval.
During its review of the BFN requests for relief the NRC staff identified questions by letter dated August 3, 2005.
TVA provided its response to the NRC request for additional information by letter dated September 26, 2005. Subsequently, the NRC identified additional questions regarding request for relief 3-ISI-7, Revision 1. These questions were transmitted by NRC informally to TVA and discussed in a teleconference on January 25, 2006.
Request for relief 3-ISI-7, Revision 1, addressed ten (10)
Reactor Pressure Vessel (RPV) nozzle-to-vessel full penetration welds and one (1) nozzle inner radius. The
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U.S. Nuclear Regulatory Commission Page 2 May 4, 2006 design configuration of the RPV nozzle-to-vessel weld and inner-radius precluded a 100 percent ultrasonic (UT) examination of the required volume for the full penetration welds of the nozzles.
The enclosure to this letter contains the specific NRC questions and the corresponding TVA response.
There are no new regulatory commitments in this letter. If you have any questions, please contact me at (256) 729-2636.
Sincerely, William D. Crouch Manager of Licensing and Industry Affairs cc: See Page 3
U.S. Nuclear Regulatory Commission Page 3 May 4, 2006 Enclosure cc (Enclosure):
(Via NRC Electronic Distribution)
Mr. Malcolm T. Widmann, Branch Chief U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, Georgia 30303-8931 NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611-6970 Ms. Margaret Chernoff, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North (MS 08G9) 11555 Rockville Pike Rockville, Maryland 20852-2739 Ms. Eva A. Brown, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North (MS 08G9) 11555 Rockville Pike Rockville, Maryland 20852-2739
ENCLOSURE TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNIT 3 AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) SECTION XI, INSERVICE INSPECTION (ISI) PROGRAM (SECOND TEN-YEAR INSPECTION INTERVAL)
REQUEST FOR RELIEF 3-ISI-7, REVISION 1 RESPONSE TO NRC INFORMAL REQUEST FOR ADDITIONAL INFORMATION This enclosure provides TVA's response to an informal NRC request for additional information regarding BFN Unit 3, ASME Section XI Inservice Inspection (ISI) Program, request for relief 3-ISI-7, Revision 1. This request for relief was submitted, along with requests for relief 3-ISI-12, and 3-ISI-19, by TVA letter dated March 4, 2005, for NRC review and approval.
During its review of the BFN requests for relief the NRC staff identified questions by letter dated August 3, 2005.
TVA provided its response to the NRC request for additional information by letter dated September 26, 2005.
Subsequently, the NRC identified additional questions regarding request for relief 3-ISI-7, Revision 1. These questions were transmitted by NRC informally to TVA and discussed in a teleconference on January 25, 2006.
Request for relief 3-ISI-7, Revision 1, addressed ten (10)
Reactor Pressure Vessel (RPV) nozzle-to-vessel full penetration welds and one (1) nozzle inner radius. The design configuration of the RPV nozzle-to-vessel weld and inner-radius precluded a 100 percent ultrasonic (UT) examination of the required volume for the full penetration welds of the nozzles.
Listed below are the specific NRC questions and the corresponding TVA response.
1.0, Request for Relief 3-ISI-7, Revision 1 NRC Request 1.1 When discussing surface finish, describe how the arithmetical average (AA) relates to the root mean square (RMS) average.
TVA Response to NRC Request 1.1 Surface roughness values are typically expressed in microinch units. A microinch is one-millionth of an inch (0.000001). Surface roughness measurements expressed as an
arithmetic average (AA) deviation from the mean surface are somewhat less than the root mean square (RMS) average deviation. AA roughness is obtained by adding all measurements in the "y" direction without regard to sign and dividing the sum by the number of measurements added. RMS roughness is obtained by adding the square of all of the measurements in the "y" direction, taking the square root of the sum and then dividing by the number of measurements.
Roughness measuring instruments calibrated to give RMS values will read approximately 11 percent higher for a surface than instruments calibrated for AA values. The conclusion is a RMS reading of the same value as an AA reading would represent a smoother surface. For example, a 250 AA finish equates to a 277 RMS finish.
NRC Request 1.2 Provide the EPRI modeling report for the BFN Unit 3 reactor pressure vessel nozzle N10-1R.
TVA Response to NRC Request 1.2 The EPRI modeling report for BFN Unit 3 RPV nozzle N10-1R is provided in attachment A of this enclosure.
NRC Request 1.3 For the nozzles in request for relief 3-ISI-7, Revision 1, please address how the zero-degree L-waves affects the ultrasonic scan coverage results.
TVA Response to NRC Request 1.3 Within the documentation provided in BFN request for relief 3-ISI-7, examination data was provided for the following RPV Nozzle to Vessel (NV) and nozzle Inner Radius (IR) welds:
NlB-NV, N2A-NV, N2C-NV, N2E-NV, N3A-NV, N4A-NV, N4F-NV, N5B-NV, N7-NV, N9-NV, and N-10 IR These weld examinations, with the exception of nozzle N-10 IR, were performed prior to the PDI Program implementation date of November 22, 2002, for RPV Nozzles and Dissimilar Metal welds. The Code examination criteria defined in ASME Section XI 1995 Edition, 1996 Addenda, Appendix I, paragraph I-2400 applied to those RPV Nozzle welds (i.e., the use of ASME Section V, Article 4). The scanning requirements of Section V, Article 4 required a straight beam (zero-degree) scan for planar reflectors as defined in paragraph T441.1.2(a). As a result of this requirement, the zero-degree examination was factored into the code coverage calculation.
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RPV Nozzle weld N-10 IR examination was performed after the implementation the PDI Program for RPV Nozzles and Dissimilar Metal Welds. The qualified examination technique does not include a zero-degree scan and was not factored into the calculation for code coverage.
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ATTACHMENT A EPRI Modeling Report for BFN Nozzle N10-IR E-4
Browns Ferry Standby Liquid Control Nozzle (N10)
Inner Radius Examination Douglas E. MacDonald EPRI NDE Center Introduction This report describes the work performed by the EPRI NDE Center to assist Browns Ferry in developing outside surface examination techniques for the standby liquid control nozzle inner corner radius region. The inspection is to be performed by Framatome. The necessary geometric inputs to the EPRI spreadsheet model [1] are listed for the nozzle and cross sectional plots are provided. The technique design curves developed by the model are given together with the techniques chosen for the nozzle. Tabular and graphical information on the technique maximum and minimum probe radial position and metal path are provided. The combined coverage or minimum misorientation angle achieved by the chosen techniques is given, as well as, the associated metal path and beam angle at the flaw. This report addresses Browns Ferry request to limit the radial extent of the vessel shell exminations.
Detection Table 1 gives the necessary geometric inputs to the NDE Center spreadsheet model for the Browns Ferry standby liquid control nozzle [2]. Figure 1 shows the geometric parameters, which define the nozzle. The ASME Section Xl Class I examination volume is also indicated in Figure 1.
Table 1. Browns Ferry Standby Liquid Control Nozzle (N10)
Geometry Inputs to Spreadsheet Model Inside Surface (degrees)/ Outside Surface (degrees)/
Dimensions (inches) Dimensions (inches)
Rbore 1.1719 Rnozzle 1.5625 Rbi 0.75 Rbo 0.75 Rvi 125.6875 Rvo 131.9375 E-5
Z 132 13D0b 128 120 zta Venad 4 6 'a 10 12 16 1is 20 R
Figure 1. Cross Section of Nozzle Defining Class I Examination Volume.
Figure 2 is a plot of the probe beam angle versus the probe skew angle for all values of surface distance, S at the fixed azimuth, 0 = 00 (the standby liquid control nozzle is axi-symmetric). The curve in Figure 2 gives the information regarding the probe angles and probe skews needed to obtain a 50° corner trap response everywhere in the inner radius examination zone of the standby liquid control nozzle, the technique design curve.
Browns Ferry Standby Liquid Control Nozzle (N10);
Probe Angle vs Probe Skew, 50 deg Corner Trap 90 P 85-s5o i- - _ _ ____
65 Cb55 g40 jO45 0
1 2
as -
4 6 8 10 12 Probe Skew 14 16 18 20 22 24 Figure 2. Browns Ferry Standby Liquid Control Nozzle (N1O):
Probe Angle vs. Probe Skew; 500 Corner Trap, Technique Design Curve.
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The convention adopted here for probe skew angles has 00 aligned with the nozzle axis with the beam pointed toward the nozzle; 900, pointed circumferentially around the nozzle; and 1800, again aligned with the nozzle axis but pointed toward the vessel (see Figure 3).
~:f' A5~. .. .-......
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i . .' . . -, . - . . . ' . .' . . . .' . . ._. ..
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- --;s.:"A :- ..... . 9..--
a)Probe Skew=+00
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...... S.. . . . S.... 5. ... ' . . .S.:...: .. ... .,..I ...... . . . . . . . . . .. .. .. .. ...... .. . ... . .........
- ,X'^
. .. .. gX e ..... ig;gg. x.. .....
F.igu e 3 AA b) Probe Skew +9Q0
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. Skeml: =-8°d rb kw=-0 c) ProbeI 2
tJ.
.'-pt l &'-X r .....
Probe Skew 1800 d) Probe Skew -90' c)
Figure 3. Definition of Probe Skew Angle.
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The EPRI spreadsheet model detection techniques to examine the Browns Ferry standby liquid control nozzle involve scanning from the outer vessel shell. Table 2 gives the probe beam and skew angles, scan surface, and the mode of propagation.
Table 2. Spreadsheet Model Detection Techniques for Browns Ferry Standby Liquid Control Nozzle (NIO).
Probe Angle Probe Skew Scan Surface Mode of Propagation 70 +/-(2 to 23) Vessel Shear Wave 65 +(I to 10) Vessel Shear Wave Figure 2 shows these detection techniques in relation to the probe angle versus probe skew curve.
These EPRI spreadsheet examination detection techniques are summarized again in Table 3 together with the corresponding scan surfaces, minimum and maximum probe radial positions, minimum and maximum metal paths, and maximum nisorientation angle.
Table 3. Spreadsheet Model Detection Techniques for Browns Ferry Standby Liquid Control Nozzle (Nl0).
Probe Probe Scan Min R Max R Min MP Max MP Max Angle Skew Surface Misorientation 70 +/-(2 to 23) Vessel 2.94 15.54 2.30 16.07 18 65 +/-(I to 10) Vessel 13.85 15.54 14.14 16.07 14 Figure 4 shows the minimum and maximum probe radial positions and the portion of the examination volume covered by the vessel shell detection technique, 70/(2 to 23)v, for probes scanned at the azimuth angle of 00.
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Browns Ferry Standby Liquid Control Nozzle (Nib);
701(2 to 23)vs z
0 2 4 6 8 10 12 14 16 R
Figure 4. Browns Ferry Standby Liquid Control Nozzle (N1O): Probe Scan Limits and Examination Coverage for Vessel Shell Detection Technique, 70/(2 to 23)v.
Figure 5 shows the minimum and maximum probe radial positions and the portion of the examination volume covered by the vessel shell detection technique, 65/(1 to 10)v, for probes scanned at the azimuth angle of 00.
Browns Ferry Standby Liquid Control Nozzle (N10);
651(1 to 10)vs 134 z
0 2 4 6 8 10 12 14 16 R
Figure 5. Browns Ferry Standby Liquid Control Nozzle (N1O): Probe Scan Limits and Examination Coverage for Vessel Shell Detection Technique, 65/(1 to 10)v.
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In viewing Figures 4 and 5, each of these probe/skew angle combinations is effective within some subset of the examination volume and ineffective in other areas. The vessel shell detection technique, 70/(2 to 23)v is effective for flaws on the bore, the vessel shell detection technique, 65/(1 to IO)v is effective for flaws on the inner blend radius.
Figure 6 shows the combined coverage (misorientation angle) for nozzle inner radius examination volume for the vessel shell detection techniques, 70/(2 to 23)v and 65/(1 to 10)v.
Figure 6. Browns Ferry Standby Liquid Control Nozzle: Coverage Plot, Vessel Shell Detection Techniques; 70/(2 to 23)v and 65/(1 to 1O)vs.
Figure 7 shows the plot of the metal path to the points on the examination volume for the I coverage shown in Figure 6.
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Browns Ferry Standby Liquid Control Nozzle (N10): Metal Path; 701(2 to 23)vs, 651(1 to 1o)vs 17- t h 5 1 --- -
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 85s 7 5 (Inches)
Figure 7. Browns Ferry Standby Liquid Control Nozzle (N10): Metal Path Plot; Union of Vessel Shell Detection Techniques; 70/(2 to 23)v, and 65/(1 to IO)v.
Figure 8 shows the plot of the beam angle at the flaw (nominal inspection angle) for the points on the examination volume for the coverage shown in Figure 6.
Figure 8. Browns Ferry Standby Liquid Control Nozzle: Beam Angle at Flaw Plot; Union of Vessel Shell Detection Techniques; 70/(2 to 23)v, and 651(1 to IO)v.
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Sizing The EPRI spreadsheet model sizing techniques to examine the Browns Ferry standby liquid control nozzle involve scanning from the outer vessel shell. Table 4 gives the probe beam and skew angles, scan surface, and the mode of propagation.
Table 4. Spreadsheet Model Sizing Techniques for Browns Ferry Standby Liquid Control Nozzle (N1I).
Probe Angle Probe Skew Scan Surface Mode of Propagation 70 +/-(2 to 21) Vessel Shear Wave 65 +/-(I to 7) Vessel Shear Wave 45 +/-(6 to 20) Vessel Shear Wave Figure 9 shows these sizing techniques in relation to the probe angle versus probe skew curve.
These EPRI spreadsheet examination sizing techniques are summarized again in Table 5 together with the corresponding scan surfaces, minimum and maximum probe radial positions, minimum and maximum metal paths, and maximum misorientation angle.
Browns Ferry Standby Liquid Control Nozzle (N110);
Probe Angle vs Probe Skew, 60 deg Comer Trap P
r 0
b e
A n
e 0 2 4 6 8 10 12 14 16 18 20 22 24 Probe Skew Figure 9. Browns Ferry Standby Liquid Control Nozzle (N1O):
Probe Angle vs. Probe Skew; 500 Corner Trap, Technique Design Curve.
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Table 5. Spreadsheet Model Sizing Techniques for Browns Ferry Standby Liquid Control Nozzle (NiO).
Probe Probe Scan Min R MaxR MinMP MaxMP Max Angle Skew Surface Misorientation 70 +/-(2 to 21) Vessel 3.00 15.52 2.25 15.35 20 65 +/-(1 to 7) Vessel 13.86 15.50 14.14 15.45 20 45 +/-(6 to 20) Vessel 6.43 7.99 8.64 9.12 0 Figure 10 shows the minimum and intermediate probe radial positions and the portion of the examination volume covered by the vessel shell sizing technique, 70/(2 to 21)v, for probes scanned at the azimuth angle of 00.
Browns Ferry Standby Liquid Control Nozzle (N10);
701(2 to 21)vs 132 130 z
128 128 124 0 2 4 6 8 10 12 14 16 R
Figure 10. Browns Ferry Standby Liquid Control Nozzle (N1O): Probe Scans and Examination Coverage for Vessel Shell Sizing Technique, 70/(2 to 21)v.
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Figure 11 shows the minimum and intermediate probe radial positions and the portion of the examination volume covered by the vessel shell sizing technique, 65/(1 to 7)v, for probes scanned at the azimuth angle of 0°.
Figure 11. Browns Ferry Standby Liquid Control Nozzle (Ni 0): Probe Scan Limits and Examination Coverage for Vessel Shell Sizing Technique, 65/(1 to 7)v.
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Figure 12 shows the minimum and maximum probe radial positions and the portion of the examination volume covered by the vessel shell sizing technique, 45/(6 to 20)v, for probes scanned at the azimuth angle of 00.
Browns Ferry Standby Liquid Control Nozzle (N 10);
45/(6 to 20)vs z
0 2 4 6 8 10 12 14 16 R
Figure 12. Browns Ferry Standby Liquid Control Nozzle (N10): Probe Scan Limits and Examination Coverage for Vessel Shell Sizing Technique, 45/(6 to 20)v.
In viewing Figures 10 through 12, each of these probe/skew angle combinations is effective within some subset of the examination volume and ineffective in other areas. The vessel shell sizing technique, 70/(2 to 21)v is effective for flaws on most of the bore, the vessel technique, 65/(1 to 7)v is effective for flaws and the lower part of the bore and the upper part of inner blend radius, and the vessel technique, 45/(6 to 20)v is effective for flaws on the remainder of the inner blend radius. Figure 13 shows the combined coverage (inisorientation angle) for nozzle inner radius examination volume for the vessel shell sizing techniques; 70/(2 to 21)v, 65/(1 to 7)v, and 45/(6 to 20)v.
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Browns Feny Standby Liquid Control Nozzle (NIO): Combined Coverage; 701(2 to 21)vs, 651(1 to 7)vs, 451(6 to 20)vs 21 M
0 15 - _ _ _ _ _ _ _ _
r 1 12 _ _ _____
e t 6 n
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 S Inches)
Figure 13. Browns Ferry Standby Liquid Control Nozzle (NI 0): Coverage Plot; Vessel Shell Sizing Techniques, 70/(2 to 21)v, 65/(1 to 7)v, and 45/(6 to 20)v.
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Figure 14 shows the plot of the metal path to the points on the examination volume for the coverage shown in Figure 13.
Browns Ferry Standby Liquid Control Nozzle (NIO): Metal Path; 701(2 to 21 )vs, 651(1 to 7)vs, 451(6 to 20)vs M 13 _ __ _
e 12 - -V-t 11 - ______
a1 0 - I - -
I - _ ___ __
a 7 - __ - _- -
h5 - -
4 ;?- -
2- - -
0 0.5 1 1.5 2 2.5 3 3.5 4 45 5 5.5 6 6.5 7 S (nches)
Figure 14. Browns Ferry Standby Liquid Control Nozzle (N1O): Metal Path Plot; Union of Vessel Shell Sizing Techniques, 70/(2 to 21)v, 65/(1 to 7)v, and 45/(6 to 20)v.
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Figure 15 shows the plot of the beam angle at the flaw (nominal inspection angle) for the points on the examination volume for the coverage shown in Figure 13.
Browns Ferry Standby Liquid Control Nozzle (N10): Beam Angle at Flaw; 701(2 to 21)vs, 651(1 to 7)vs, 451(6 to 20)vs 60-E 56=
54 -
aM 52 __
A 50 n4 8 e44 ____ _____
42 40 -- -
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 S (Inches)
Figure 15. Browns Ferry Standby Liquid Control Nozzle: Beam Angle at Flaw; Union of Vessel Shell Sizing Techniques, 70/(2 to 21)v, 65/(1 to 7)v, and 45/(6 to 20)v.
Summary of Browns Ferry Standby Liquid Control Nozzle Inner Radius Modeling Parameters Table 6 lists the summary of the modeling parameters for the Browns Ferry standby liquid control nozzle inner radius detection examination.
Table 6. Browns Ferry Standby Liquid Control (SLC) Nozzle (N1O)
Inner Corner Region Detection Examination Modeling Parameters.
Nozzle ID Metal Path Beam Angle at Flaw Maximum Percent Minimum Maximum Minimum Maximum Misorientation Coverage Angle SLC (N1O) 2.30 16.07 40 90 18 90 E-18
Table 7 lists the summary of the modeling parameters for the Browns Ferry standby liquid control nozzle inner radius sizing examination.
Table 7. Browns Ferry Standby Liquid Control (SLC) Nozzle (N1O)
Inner Corner Region Sizing Examination Modeling Parameters.
Nozzle ID Metal Path Beam Angle at Flaw Maximum Percent Minimum Maximum Minimum Maximum Misorientation Coverage Angle SLC (N1O) 2.25 15.45 40 60 20 90 References
- 1. UltrasonicExamination of Nozzle Inner Radius Regions. Charlotte, North Carolina: EPRI NDE Center, December 1997. TR-107493
- 2. Cylinder-Sphere Tapered NIR Model Class 1 V1.OBO.xls (4/18/2003 8:03 AM)
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