NLS2006038, Relief Request R1-06, Revision 3, for the Third Ten-Year ISI Interval
| ML061530274 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 05/30/2006 |
| From: | Edington R Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NLS2006038 | |
| Download: ML061530274 (10) | |
Text
N Nebraska Public Power District Always here when you need us 10 CFR 50.55a NLS2006038 May 30, 2006 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
Subject:
Relief Request RI-06, Revision 3, for the Third Ten-Year ISI Interval Cooper Nuclear Station, Docket No. 50-298, DPR-46 The purpose of this letter is to submit Revision 3 of Relief Request RI-06 for U.S. Nuclear Regulatory Commission (NRC) approval. This revision corrects data submitted to the NRC regarding weld HMC-BB-I for the third ten-year inservice inspection (ISI) interval. The attached relief request involves examination requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code.
RI-06, Revision 2, included examination coverage achieved for various welds in the third ten-year ISI interval. This request included weld HMC-BB-I, which had not yet been examined for the third interval. The 86% coverage referred to in RI-06, Revision 2, was actually the coverage obtained for HMC-BB-1 in the second ten-year interval. On November 30, 2001, the NRC approved the request with the understanding that they were approving examination coverage of 86% for weld HMC-BB-l for the third interval. When weld HMC-BB-1 was subsequently examined in the third interval using Performance Demonstration Initiative (PDI) qualified procedures, the actual coverage achieved was 75%. Therefore, proposed Relief Request RI-06, Revision 3, is a request to change the NRC approved examination coverage in lower reactor vessel circumferential weld HMC-BB- I from 86% total composite coverage to 75% coverage for the third interval.
The only weld affected by this relief request revision is HMC-BB- 1. All other welds listed in this request met the NRC allowable examination coverage for the third ten-year interval and are not affected by this revision. Changes to the relief request are indicated by revision bars.
This request is applicable to the third ten-year ISI interval, which ended on February 28, 2006.
NPPD requests approval of this request by December 4, 2006, in order for CNS to close out the third ten-year ISI interval. The applicable ASME Code for the CNS third ten-year interval was the 1989 Edition. However, the examination for HMC-BB- I was performed in accordance with ASME Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, due to implementation of the Performance Demonstration Initiative.
COOPER NUCLEAR STATION P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211
-AC)LP7 www.nppd .com
NLS2006038 Page 2 of 2 Should you have any questions concerning this matter, please contact Paul Fleming, Licensing Manager, at (402) 825-2774.
Sincerely, Randall K. Edington Vice President - Nuclear and Chief Nuclear Officer
/sl Attachment cc: Regional Administrator w/attachment USNRC - Region IV Cooper Project Manager w/attachment USNRC - NRR Project Directorate IV-1 Senior Resident Inspector w/attachment USNRC - CNS NPG Distribution w/attachment CNS Records w/attachment
NLS2006038 Attachment Page I of 7 RELIEF REQUEST NUMBER: RI-06, REVISION 3 COMPONENT IDENTIFICATION Code Class: I
References:
IWB-2500 Table IWB-2500-1 Examination Category: B-A Item Number: BI.11, Bl.12, B1.21, B1.22, B1.30
==
Description:==
Inspection of Reactor Vessel Circumferential and Longitudinal Welds, and Lower Head Circumferential and Meridional Welds Component Numbers: HMB-BB-I HMB-BB-2 HMB-BB-3 HMB-BB-4 HMB-BB-5 HMB-BB-6 HMC-BB-I HMD-BB-1 VLA-BA-1 VLA-BA-2 VLA-BA-3 VLB-BA-1 VLB-BA-2 VLB-BA-3 VLC-BB-l VCB-BA-2 VCB-BB-3 CODE REQUIREMENT Table IWB-2500- 1, Category B-A, Item B 1.11 and B 1.12 requires a volumetric examination of all beltline region shell circumferential and longitudinal welds.
Table IWB-2500- 1, Category B-A, Item B 1.21 and B 1.22 requires a volumetric examination of accessible lengths of all lower head circumferential and meridional welds.
Table IWB-2500-1, Category B-A, Item B1 .30 requires a volumetric examination of 100% of the length of the shell to flange weld.
BASIS FOR RELIEF:
The Cooper Nuclear Station construction permit was issued before the effective date of implementation for ASME Section XI and thus the plant was not designed to meet the requirements of inservice inspection; therefore, 100% compliance is not feasible or practicable.
The CRD and instrument penetrations prevent direct access to most of the bottom head.
Circumferential weld HMD-BB-1 is located inside the skirt and is inaccessible for examination. Portions of the Bottom Head Meridional welds, HMB-BB-1, HMB-BB-2, HMB-BB-3, HMB-BB-4, HMB-BB-5, HMB-BB-6 are located inside the vessel skirt and are inaccessible for examination. Access to weld HMC-BB-! is limited due to the proximity of the vessel skirt. The configuration limits scanning with the 60 degree probe. The total composite coverage achieved for HMC-BB-I in the third ISI inspection interval was 75%
with no recordable indications.
NLS2006038 Attachment Page 2 of 7 RELIEF REQUEST NUMBER: RI-06, REVISION 3, CONTINUED BASIS FOR RELIEF (Continued):
Access to the reactor vessel shell welds from the exterior is limited. Below the top of the biological shield, most of the reactor vessel is insulated with permanent reflective insulation and surrounded by a concrete biological shield. Penetrations through the biological shield provide limited access to some welds. The annular space between the inside diameter of the insulation and the outside diameter of the reactor vessel is a nominal 2 inches. There is no working space to remove the insulation panels from the vessel, which precludes both direct and remote examination of the outside surface.
In accordance with 10 CFR 50.55a(g)(6)(ii)(A), an examination of the Reactor Vessel shell welds was performed during RFO- 18 using PDI qualified procedures (see Relief Request RI-
- 04) and the GERIS 2000 ID Scanner. Supplemental manual examinations were performed to the extent practical. Weld coverage is identified in the attached table.
Proposed Relief Request RI-06, Revision 3, is a request to change the NRC allowable examination coverage in lower reactor vessel circumferential weld HMC-BB- 1 from 86%
total composite coverage to 75% coverage. The only weld affected by this relief request revision is HMC-BB-l. All other welds listed in this request met the NRC allowable examination coverage for the third ten-year interval and are not affected by this revision.
In addition to the physical limitation due to the proximity of the weld to the vessel skirt, the reduction in total composite coverage (i.e., 75% as opposed to previous 86%) is believed to be due to differences in procedure and equipment qualifications through the Performance Demonstration Initiative (PDI) as compared to previous requirements. Limitations of qualified transducer sizes through PD1 contributed to the reduction of coverage compared to the previous examination of HMC-BB-1. This weld was examined in 1993 and again in 1995 using 0-, 45-, and 60-degree transducers. In 2001, the examination for the third interval was performed in accordance with ASME Section XI, 1995 Edition, 1996 Addenda, Appendix VIII, using only a 60-degree transducer. This examination achieved 75% total composite coverage. (See Figure RI-06, "HMC-BB-1 Scan Area.") However, based on the demonstrated qualification of the examiners, a more reliable examination was performed even though less coverage was achieved.
Since 10 CFR 50.55a requires the use of ASME XI Appendix VIII in detecting flaws in the welds at CNS, only qualified PDI procedures and specific qualified transducers may be used for the examinations. Previous examinations on the weld may have reported additional coverage, but since the previous examiners and equipment were not qualified by PDI, the 86% coverage reported during the second interval cannot be considered as reliable as the 75% achieved in the third interval. The PDI examination methods maximize the coverage that can be "reliably" obtained, even though PDI-qualified transducers and associated procedures limit how much coverage an examiner is able to achieve.
NLS2006038 Attachment Page 3 of 7 RELIEF REQUEST NUMBER: RI-06, REVISION 3, CONTINUED PROPOSED ALTERNATE EXAMINATION In accordance with 10 CFR 50.55a(g)(5)(iii), CNS proposes to examine the accessible portions of the reactor vessel welds in lieu of the impractical code-required examinations.
Using the provisions of this relief request as an alternative to the specific requirements of ASME Table IWB-2500-1, identified above, will continue to provide reasonable assurance of structural integrity since the percent of examination coverage already obtained would have identified any pattern of degradation should one develop. Therefore, pursuant to 10 CFR 50.55a, "Codes and Standards," Paragraph (a)(3), NPPD requests relief from the specific IWB requirements identified in this request. Based on the above, the proposed alternative inspection will continue to provide an acceptable level of quality and safety.
APPLICABLE TIME PERIOD RI-06, Revision I was denied by the NRC on October 23, 1997 (TAC No. M94000).
Revision 1 acknowledged that the vessel inspection had not been performed yet.
RI-06, Revision 2 was approved on November 30, 2001 (TAC No. MB2003).
RI-06, Revision 3 is requested for the third ten-year interval of the Inservice Inspection Program for CNS, which started on March 1, 1996, and ended on February 28, 2006.
REFERENCES
- 1. NPPD Letter NLS950157 to USNRC, "Third Ten-Year Interval Inservice Inspection Program," dated October 18, 1995.
NLS2006038 Attachment Page 4 of 7 RELIEF REQUEST NUMBER: RI-06, REVISION 3, CONTINUED
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Figure RI-06 HMC-BB-1 Scan Area (Cross Hatching Represents Scan Limitation Areas)
NLS2006038 Attachment Page 5 of 7 RELIEF REQUEST NUMBER: RI-06, REVISION 3, CONTINUED TABLE RI-06 RPV Shell Weld Coverage Limitations Percent Coverage Weld Number GERIS Manual Total Restrictions VLA-BA-1, 0 59.5 59.5 Core Spray downcomer and guide rod to Shell Ring 1, shroud support bracket (ID). N IA&N2A Longitudinal nozzles, insulation support rings, and biological shield (GD).
VLA-BA-2, 74.9 5.7 80.6 Jet pump diffuser and shroud support Shell Ring I, gussets (ID). Insulation support and Longitudinal biological shield (0D).
VLA-BA-3, 74.9 5.7 80.6 Jet pump diffuser and shroud support Shell Ring I, gussets (ID). Insulation support and Longitudinal biological shield (GD).
VLB-BA-I, 80.8 0 80.8 Jet pump riser braces (ID). Insulation Shell Ring 2, support and biological shield (GD).
Longitudinal VLB-BA-2, 0 0 0 Guide rods and core spray downcomers Shell Ring 2, (ID). Biological shield (GD).
Longitudinal VLB-BA-3, 49.6 0 49.6 Surveillance specimen brackets and jet Shell Ring 2, pump riser braces (ID). Biological shield Longitudinal (GD).
VLC-BB-1, 0 0 0 Guide rods, Feedwater Spargers, and core Shell Ring 3, spray downcomers (ID). Biological shield Longitudinal (GD).
VLC-BB-2*, 73.8 25.0 98.8 Core Spray piping, Feedwater Spargers Shell Ring 3, (ID).
Longitudinal VLC-BB-3*, 73.8 21.2 95.0 Core Spray piping, Feedwater Spargers Shell Ring 3, (ID). Biological shield (GD).
Longitudinal
NLS2006038 Attachment Page 6 of 7 RELIEF REQUEST NUMBER: RI-06, REVISION 3, CONTINUED TABLE RI-06 RPV Shell Weld Coverage Limitations Percent Coverage Weld Number GERIS Manual Total Restrictions VLD-BB-l *, 89.6 9.9 99.5 Steam dryer support lug (ID).
Shell Ring 4, Longitudinal VLD-BB-2*, 86.3 13.1 99.4 Steam dryer support lug (ID).
Shell Ring 4, Longitudinal VLD-BB-3*, 98.2 0 98.2 Temporary lighting (ID).
Shell Ring 4, Longitudinal VCB-BB-1 *, **, 0 94.0 94.0 Shroud support plate and gussets (ID).
Lower Head to Biological shield (OD).
Shell Ring I Circumferential VCB-BA-2, 66.3 0 66.3 Guide rods, core spray downcomers, Shell Ring 1 to 2, surveillance specimen brackets, and weld Circumferential contour (ID). Biological shield (OD).
VCB-BB-3, 81.8 0 81.8 Guide rods, core spray downcomers, Shell Ring 2 to 3, surveillance specimen brackets, CRD Circumferential Return Nozzle, and weld contour (ID).
Biological shield (OD).
VCB-BB-4*, 94.4 0 94.4 Guide rods (ID). Biological shield (OD).
Shell Ring 3 to 4, Circumferential VCB-BC-5*, 72.9 20.4 93.3 Guide rods and MS nozzle plugs (ID).
NLS2006038 Attachment Page 7 of 7 RELIEF REQUEST NUMBER: RI-06, REVISION 3, CONTINUED TABLE RI-06 RPV Shell Weld Coverage Limitations
- Based on Code Case N-460, relief is not required when at least 90% of the required volume has been examined. No relief is requested for these welds. However the extent of coverage for these welds is provided as supporting information for evaluation of this request.
- The lower head to shell ring I circumferential weld is a Code Item B 1.21 weld and is provided for information only. The percentage of coverage obtained for the subject weld is not included in the cumulative coverage estimate.
- The shell ring 4 to flange circumferential weld is a Code Item B13.30 weld and is provided for information only. The percentage of coverage obtained for the subject weld is not included in the cumulative coverage estimate.
I ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© Correspondence Number: NLS2006038 The following table identifies those actions committed to by Nebraska Public Power District (NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actiont by NPPD. They are described for information only and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
COMMITMENT COMMITTED DATE COMMITMENT NUMBER OR OUTAGE None 4 4 4 4 4 +
a 4-a t 4 4.
4 1 PROCEDURE 0.42 REVISION 19 1 PAGE 20 OF 27 j