ML20216J010
| ML20216J010 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 03/17/1998 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20216J007 | List: |
| References | |
| NUDOCS 9803230275 | |
| Download: ML20216J010 (7) | |
Text
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p UNITED STATES g
j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30seH001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
ON THE THIRD 10-YEAR INSERVICE INSPECTION INTERVAL RELIEF REQUEST RR-1-18 WISCONSIN ELECTRIC POWER COMPANY POINT BEACH NUCI FAR POWER PLANT. UNIT 1 DOCKET NO. 50-266
1.0 INTRODUCTION
The Technical Specifications (TS) for Point Beach Nuclear Power Plant (PBNPP), Unit 1, state that the inservice inspection and testing of the American Society of Mechanical Engineers
-j (ASME) Boiler and Pressure Vessel Code (Code) Class 1,2, and 3 components shall be performed in accordance with Section XI of the ASME Code and applicable addenda as required by 10 CFR 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).10 CFR 50.55a(a)(3) states that attematives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed attematives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4), ASME Code Class 1,2, and 3 components (including supports) shall meet the requirements, except the design and access provisions and the i
presenrice examination requirements, set forth in the ASME Code,Section XI, " Rules for Inservice Inspection of Nuclear Power Plant Components," to the extent practical within the limitations of design, geometry, and materials of construction of the components. The regulations require that inservice examination of components and system pressure tests conducted during the first 10-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) on the date 12 months prior to the start of the.120-month interval, subject to the limitations and modifications listed therein. The applicable edition of Section XI of the ASME Code for Point Beach, Unit 1, for the third inservice inspection (ISI) interval is the 1986 Edition, no addenda. The components (including supports) may meet the requirements set forth in subsequent editions and addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein and subject to Commission approval.
ENCLOSURE l
9803230275 980317 PDR ADOCK 05000266 G
. i*
i Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASME Code is not practical for its facility, information shall be submitted to the Commission in support of that determination and a request l
made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to 10 CFR 50.55a(g)(6)(i), the Commission may grant relief and may impose attemative requirements that are determined to be authorized by law, will not endanger life, property, or the common defense and security, and are otherwise in the public interest, giving l
due consideration to the burden upon the licensee that could result if the requirements were imposed.
By letter dated March 12,1998, the Wisconsin Electric Power Company (the licensee) requested to use the Performance Demonstration Initiative (PDI) Program based on the criteria l
of Appendix Vill,Section XI of the ASME Code,1992 Edition, including the 1993 Addenda as l
an alternative to the requirement of the 1986 Edition of ASME Code,Section XI, for ultrasonic examination of reactor vessel welds in PBNPP, Unit 1.
The staff has reviewed and evaluated the licensee's request and supporting information on the proposed alternative to the Code requirements for PBNPP, Unit 1, pursuant to the provisions of 10 CFR 50.55a(a)(3)(i).
2.0 DISCUSSION Component identification:
Reactor Pressure Vessel Unit 1 The PDI technique will be used to ultrasonically examine the following welds.
Circumferential Welds a.
RPV-15-683 Upper Shell to Middle Shell b.
RPV-16-683 Middle Shell to Lower Shell c.
RPV-17-683 Lower Shell to Lower Head Ring d.
RPV-18-683 Lower Head Ring to Lower Head Lonoitudinal Welds e.
RPV-MK-2 Middle Shell Long Seam at 15 degrees f.
RPV-MK-3 Lower Shell Long Seam at 195 degrees A combination of PDI and the ASME Code techniques will be used to examine the following welds.
Reactor Vessel-ta-Flanoe Weld g.
RPV-14-683-A Shell to Flange (Azimuth 1-180) h.
RPV-14-683-8 Shell to Flange (Azimuth 180-360)
3
(
)
Nonle-to-Shell Welds i.
RPV-2-686-A Shell to Outlet Nonle at 28.5 degrees j.
RPV-2-686-B Inlet Nonle to Shell at 148.5 degrees k.
RPV-2-686-C Shell to Outlet Nonle at 208.5 degrees l.
RPV-2-686-D Inlet Nonle to Shell at 328.5 degrees m.
RPV-687-01-A Safety injection Nonle to Shell at 288.5 degrees n.
RPV-687-01-B Safety injection Nonle to Shell at 108.5 degrees EXAM AREAS IWB-2500-1, 2, 3, 4, 7 ASME SECTION XI CATEGORY B-A - welds (a) through (h) above B-D - welds (i) through (n) above ASME SEC MON XI ITEM NUMBER B1.11 - welds (a) and (b) above B1.12 - welds (e) and (f) above B1.21 - welds (c) and (d) above B1.30 - welds (g) and (h) above B3.90 - welds (i) through (n) above.
Code Requirement:
ASME Section XI,1986 Edition, no Addenda, Table IWB-2500-1 requires volumetric examination for these welds. The requirements for volumetric examinations are stated in Article IWA-2232, which states that examinations be conducted in accordance with Article 4 of ASME Code,Section V, as amended by ASME Code,Section XI.
Proposed Alternative: (As stated)
Examination procedures, equipment, and personnel qualified by performance demonstration will be utilized in accordance with the PDI Program, in combination with ASME Code,Section V, Article 4 techniques. The followirig techniques will be utilized for the proposed welds:
)
1)
Welds (a) through (f) above will be examined with PDI techniques only.
2)
Welds (g) and (h) above will be examined from the seal surface using ASME Code i
techniques for detection of flaws parallel to the weld plane. Examination for transverse i
(
and parallel flaws will be conducted from the vessel inside surface using PDI I
techniques.
4 3)
Welds (i) through (n) above will be examined with PDI techniques from the vessel wall l
for detection of transverse reflectors. For detection of flaws that are parallel to the weld, l
examinations will be conducted from the nozzle bore using ASME Code techniques.
I A comparison of the proposed PDI technique for PBNPP and the standard Article 4,Section V and Regulatory Guide 1.150 pre,cedures are given in the Table attached to this SE.
I As a minimum, all Code requirements of the 1986 Edition of Section XI will be implemented, except where specific differences have been identified in this submittal. In addition, as mentioned above, it is our intention to satisfy the 10 CFR 50.55a(g)(6)(ii)(A), " Augmented," RPV inspection requirements.
REASON FOR PROPOSED ALTERNATIVE REQUIREMENT:
Wisconsin Electric Power Ccmpany has contracted with Southwest Research Institute (SwRI) to perform the third 10-year RPV examination using a combination of the PDI qualified techniques and ASME,Section V, Article 4 techniques. SwRI's procedures were qualified in accordance with the PDI program covering Supplements 4, " Qualification Requirements for the Clad / Base Metal Interface of Reactor Vessel," and 6, " Qualification Requirements for Reactor Vessel Welds Other than C. lad / Base Metal Interface," of Appendix Vlli,Section XI, ASME Code.
Both double and single-sided approaches were qualified for Supplement 4 applications and for
)
Supplement 6 applications up through 12-inch wall thicknesses. (Southwest Research Institute's PDI certification is on file at the Electric Power Research Institute Non-Destructive Examination Center in Charlotte, NC.)
1 Southwest Research Insf.itute's PDI detection procedure utilizes two types of search units (55-degrees, multibeam) when scanning can be accomplished from two sides of the weld, and three types of search units (45,55, and multibeam) when scanning can be accomplished from one side of the weld. The multibeam search unit is used to examine the inner 25-percent thickness.
3 The 45 and 55 degree shear-wave search units are used to examine the outer 75 percent. A 0-degree search unit may also be used to detect laminar reflectors and determine component thickness. (NOTE: Wisconsin Electric Power Company has instructed SwRI to scan from two sides of each weld whenever it is possible.) Scanning is performed: (1) perpendicular to the weld for flaws oriented parallel to the weld; and (2) parallel to the weld for flaws oriented perpendicular (transverse) to the weld. Flaw discrimination methods are independent of signal amplitude. Scanning sensitivities are determined based on the actual material noise.
Analysis and sizing c,f indications are performed by qualified Level lli Data Analysts using SwRI procedures. Regard.less of whether the detection examinations are being performed per ASME Code or PDI procedures, SwRI's sizing procedures utilize tip-diffraction methods qualified in accordance with the PDI guidelines.
3.0 EVALUATION, The PDI program based on the criteria of Appendix Vill,Section XI of the ASME Code,1992 Edition,1993 Addenda, requires that ultrasonic equipment, procedures, and examiners be tested on flawed and notched materials and configurations similar to those found in actual plant
conditions. Hence, performance-based ultrasonic examination techniques provide a higher degree of reliability for detection and characterization of flaw when compared to the conventional amp'itude-based ultrasonic techniques required by the current Code. The staff has assessed the PDi program activities and has approved the use of PDI techniques at other sites.
Based on the information provided by Wisconsin Electric Power Company, the staff has evaluated the PDI program proposed for ultrasonic examination of reactor pressure vessel welds for Point Beach, Unit 1, during the third 10-year inspection interval. The staff compared the licensee's proposed examination technique based on the PDI with that of the current Code and the Regulatory Guide 1.150 and determined that the PDI technique would provide better sensitivity to flaw detection than that of the currently applicable standards. Furthermore, the sizing and evaluation of a flaw is more accurate using multibeam tip-diffraction technique under the licensee's proposed PDI program than the amplitude based flaw sizing allowed by the current Code. Additionally, whenever feasible Wisconsin Electric will scan the examination volume from both sides of the weld on the same surface. However, when configuration or adjacent parts of the component are such that scanning from both sides is not feasible, this fact shall be included in the report of examination. Therefore, the staff has determined that the proposed alternative to implement the PDI program for the reactor vessel examination provides an equivalent or a better examination than that of the current standards and will provide assurance of structuralintegrity.
4.0 CONCLUSION
The staff has reviewed and evaluated the licensee's proposed attemative to implement the PDI program for the reactor vessel examination for both units at Point Beach during the third 10-year inspection interval. A comparison of the ultrasonic testing technique used in the PDI with that of the current Code and Regulatory Guide 1.150, indicates that the PDI technique provides an equivalent or a better examination of the reactor vessel than that of the goveming standards.
Scanning of the examination volume will be carried out from both sides of the weld on the same surface wherever feasible. Hence, the staff has determined that the proposed attemative provides an acceptable level of quality and safety. Therefore, the proposed attemative may be authorized, pursuant to 10 CFR 50.55a(a)(3)(i) for the reactor vessel examination during the third 10-year interval at Point Beacn, Unit 1.
Attachment:
Taole Principal Contributors: P. Patnaik L. Gundrum Dated: March 17, 1998 I
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