L-MT-13-089, 10 CFR 50.55a Request No. 21: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year Lnservice Inspection Interval

10 CFR 50.55a Request No. 21: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year Lnservice Inspection Interval

ML13241A236
Person / Time
Site:	Monticello
Issue date:	08/28/2013
From:	Schimmel M A Xcel Energy, Northern States Power Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
L-MT-13-089
Download: ML13241A236 (22)

Text

Xcel Energy@ August28,2013 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket 50-263 Renewed Facility Operating License No. DPR-22 Monticello Nuclear Generating Plant 2807 W County Road 75 Monticello, MN 55362 L-MT-13-089 10 CFR 50.55a(g)

Subject:

10 CFR 50.55a Request No. 21: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year lnservice Inspection Interval Pursuant to 10 CFR 50.55a, "Codes and standards," paragraph (g)(5)(iii), Northern States Power Company, a Minnesota corporation (NSPM), d/b/a Xcel Energy requests relief from examination coverage requirements imposed by the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," for the Monticello Nuclear Generating Plant (MNGP). This 10 CFR 50.55a request is for weld examinations performed during the 2011 refueling outage, where the required coverage of "essentially 100 percent" could not be obtained when examined to the extent practical.

The basis for the 10 CFR 50.55a request is that compliance with the examination coverage requirement is impractical due to plant design. The details of the 10 CFR 50.55a request are provided herein. MNGP is submitting this request for the Fourth Ten-Year lnservice Inspection Interval which ended August 31, 2012. If you have any questions or require additional information, please contact Mr. Randy Rippy at 612-330-6911.

• Document Control Desk L-MT-13-089 Page 2 of 2 Summary of Commitments This letter makes no new commitments and no revisions to existing commitments.

Mark A Schimmel Site Vice President, Monticello Nuclear Generating Plant Northern States Power Company-Minnesota Enclosures (4) cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC Minnesota Department of Commerce ENCLOSURE 1 10 CFR 50.55a REQUEST NO. 21 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY

1. ASME Code Component(s)

Affected Components affected are American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, Class 1, Reactor Pressure Vessel (RPV) Nozzle-to-Vessel welds and the Reactor Vessel Top Head-to-Flange weld specified below and in Table A of Enclosure 2, based on examinations performed during the 2011 refueling outage: Recirculation Suction Nozzle N-1 B Feedwater Inlet Nozzle N-40 RPV Top Head-to-Flange

2. Applicable ASME Section XI Code Edition and Addenda Weld-N-1 B NV Weld-N-40 NV Weld-W-8 The applicable ASME Section XI Code for the Monticello Nuclear Generating Plant (MNGP), Fourth Ten-Year lnservice Inspection (lSI) Interval is the 1995 Edition with the 1996 Addenda. ASME Section XI, Appendix VIII requirements are implemented as required by, and as modified by 10 CFR 50.55a. Ultrasonic procedures and personnel are qualified to the Performance Demonstration Initiative (POl). The POl Program document meets the requirements of 10 CFR 50.55a up through the 2001 Edition of Section XI. 3. Applicable Code Requirements ASME Class 1 Reactor Vessel welds are subject to the examination requirements of Subsection IWB, Table IWB-2500-1, as shown below, and by 10 CFR 50.55a(b)(2)(xv)(G).

The welds are required to be examined once within the Fourth Ten-Year Interval:

Code Class: 1

References:

IWB-2500, Table IWB-2500-1 Examination Categories:

B-A; B-D Item Numbers: 81.40; 83.90,

Description:

RPV Head-to-Flange Weld; Nozzle-to-Vessel Welds Component Numbers: See Section 1 and Enclosure 2 Table A System: Reactor Vessel Examination Method: Volumetric-Ultrasonic Testing (UT) Examination Volume: Figure IWB-2500-5; Figure IWB-2500-?(b)

Page 1 of 9 In July 2010, the Nuclear Regulatory Commission (NRC) issued Regulatory Guide (RG) 1.147, Revision 16, "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1" (Reference 1). In RG 1.147, the NRC identifies the ASME Code Cases they have determined to be acceptable alternatives to applicable parts of Section XI, and indicate that licensees may use these Code Cases without requesting authorization from the NRC, provided that they are used with any identified limitations or modifications.

RG 1.147, Table 1 lists the following two Code Cases as acceptable to the NRC for use by a licensee with no identified limitations or modifications:

1) Code Case N-460 (Reference 2), 2) Code Case N-613-1 (Reference 3). Code Case N-460 states in part, " ... when the entire examination volume or area cannot be examined due to interference by another component or part geometry, a reduction in examination coverage on any Class 1 or Class 2 weld may be accepted provided the reduction in coverage for that weld is less than 1 0%." NRC Information Notice (IN) 98-42 (Reference

4) termed a reduction in coverage of less than 1 0 percent to be "essentially 1 00 percent." IN 98-42 states in part, "The NRC has adopted and further refined the definition of 'essentially 100 percent' to mean 'greater than 90 percent' ... has been applied to all examinations of welds or other areas required by ASME Section XI." Code Case N-613-1, as an alternative to Figure IWB-2500-7(b) required for RPV nozzle-to-vessel shell welds, permits an examination volume that includes the width of the weld plus one-half inch of adjacent base metal on each side of the widest part of the weld. In comparison, the examination volume required by the Figure IWB-2500-7(b) includes the width of the weld plus the adjacent base metal on each side of the widest part of the weld equal to one-half of the vessel shell wall thickness.

4. Impracticality of Compliance Construction Permit CPPR-31 was obtained for the MNGP in 1967. The MNGP systems and components were designed and fabricated before the examination requirements of ASME Section XI were formalized and published.

Therefore, MNGP was not specifically designed to meet the requirements of ASME Section XI and full compliance is not feasible or practical within the limits of the current plant design. 10 CFR 50.55a recognizes the limitations to inservice inspection of components in accordance with Section XI of the ASME Code imposed due to early plants' design and construction, as follows: Page 2 of 9 10 CFR 50.55a(g)(1

): For a boiling or pressurized water-cooled nuclear power facility whose construction permit was issued prior to January 1, 1971, components (including supports) must meet the requirements of paragraphs (g)(4) and (5) of this section to the extent practical.

10 CFR 50.55a(g)(4):

Throughout the service life of a boiling or pressurized water-cooled nuclear power facility, components (including supports) which are classified as ASME Code Class 1, Class 2, and Class 3 must meet the requirements, except design and access provisions and pre-service examination requirements, set forth in Section XI of editions of the ASME Boiler and Pressure Vessel Code ... to the extent practical within the limitations of design, geometry and materials of construction of the components.

10 CFR 50.55a(g)(5)(iii):

If the licensee has determined that conformance with certain code requirements is impractical for its facility, the licensee shall notify the Commission and submit, as specified in§ 50.4, information to support the determinations.

The inspection limitations on the subject components are due to inherent component design geometric contours and scanning interference (see Enclosure 2 Table A and Enclosure 3). A description of the examination methodology used to achieve the examination coverage is provided in Section 6 of this request. The methodology is based on ASME Section XI, Appendix VIII qualification and was applied to the extent practical within the design constraints of the components.

Enclosure 3 provides cross-sectional diagrams of the subject welds showing the geometric contour of the component design in relation to the welds and the coverage obtained within the examination volumes of Figure IWB-2500-5 for the RPV weld and the alternative examination volume requirements of Code Case N-613-1, Figure 2 for the RPV nozzle-to-vessel shell welds. 5. Burden Caused by Compliance Compliance with the examination coverage requirements of ASME Section XI would require modification, redesign, or replacement of components where geometry is inherent to the component design. 6. Proposed Alternative and Basis for Use Proposed Alternative In accordance with 10 CFR 50.55a(g)(5)(iii), relief is requested for the components listed in Table A of Enclosure 2 on the basis that the required examination coverage of "essentially 1 00 percent" is impractical due to physical Page 3 of 9 obstructions and the limitations imposed by design, geometry and materials of construction.

Northern States Power Company-Minnesota (NSPM) performed volumetric examinations that achieved the maximum, practical amount of coverage obtainable within the limitations imposed by the design of the components with no detected indications.

In addition to volumetric examinations, as Class 1 Examination Category B-P components, a VT-2 examination is performed on the subject components of the Reactor Coolant Pressure Boundary (RCPB) during system pressure tests each refueling outage. This was completed during the 2011 refueling outage and no evidence of leakage was identified for these components.

In accordance with the requirements of Table IWB-2500-1, Category B-A, Item B1.40, a surface exam was completed on the head-to-flange weld with no indications being detected.

Pursuant to 10 CFR 50.55a(g)(5)(iii), NSPM requests authorization of an alternative to the examination coverage requirements of ASME Section XI Table IWB-2500-1, Category B-A, Item B1.40 and Category B-D, Item B3.90, and proposes to utilize these completed exams as acceptable alternatives that provide reasonable assurance of continued structural integrity.

Basis for Use Nozzle-to-vessel shell welds (N-1 B NV and N-40 NV): The NSPM Nondestructive Examination (NDE) UT procedures incorporate inspection techniques qualified under Appendix VIII of the ASME Section XI Code by the POl. Examinations of the RPV nozzle-to-shell welds were performed from the Reactor Vessel exterior surface using a manual contact method from the nozzle blend radius, the nozzle-to-vessel shell weld, and vessel shell surface. Coverage using the alternative examination volume permitted by Code Case N-613-1 was obtained by following the scan parameters designated within NSPM NDE procedures for each nozzle configuration and angle, including those parameters defined by MNGP-specific Electric Power Research Institute (EPRI) computer modeling report (Reference 5). It should be noted that the scans defined by the EPRI report are only applicable to the inner 15 percent of the weld volume when scanning in the parallel (circumferential) direction.

The refracted longitudinal wave mode of propagation was applied for all radial (axial) scans of the exam volume. The refracted longitudinal wave mode of propagation was also applied to the outer 85 percent of the exam volume for parallel scans. As required by the NSPM NDE procedures and the EPRI computer modeling report, the shear wave mode of propagation was applied for each of the transducer and wedge combinations required for the remaining inner 15 percent of the parallel scan exam volume. Page 4 of 9 The subject nozzle-to-vessel welds received the required examination(s) to the extent practical within the limited access of the component design. One hundred percent coverage was obtained for the inner 15 percent of the examination volume for the radial and parallel scans. The examination limitations for the subject components were encountered within the outer 85 percent of the examination volume for the parallel and radial scans. For the examinations conducted, satisfactory results were achieved, and no flaw indications were detected.

Due to the design of these nozzle-to-shell welds, it was not feasible to effectively perform a volumetric examination of "essentially 1 00 percent" of the required volume. The nozzle-to-vessel welds are accessible from the vessel plate side of the weld and are examined to the extent practical with qualified techniques, however, the curvature of the nozzle forging and proximity to the weld precludes obtaining further coverage of the excluded areas within the outer 85 percent of the examination volume. RPV head-to-flange weld (W-8): MNGP applied performance-based ultrasonic techniques qualified to the requirements of ASME Section XI Appendix VIII Supplements 4 and 6, as modified by 10CFR50.55a(b)(2)(xv), using the provisions of IWA-2240 as a substitute for the amplitude-based examination techniques of ASME Section V, Article 4. As permitted by IWB-2500, alternative examination methods other than those specified in Table IWB-2500-1 may be used when they meet the requirements of IWA-2240.

Per IWA-2240, alternative examination methods, a combination of methods, or newly developed techniques may be substituted for the methods specified, provided the Inspector is satisfied that the results are demonstrated to be equivalent or superior to those of the specified method. Exams were performed using personnel and procedures qualified for single-sided examinations.

An NDE procedure written to POl generic procedure PDI-UT-6, which has an applicable thickness range that envelops the nominal design thicknesses of the head-to-flange materials within the examination volume, was used to perform the examination.

This same procedure is used for examination of the RPV head meridional welds that intersect with the head-to-flange weld, and for examination of the aforementioned nozzle-to-vessel shell welds. The head-to-flange weld was examined from the exterior surface of the RPV head using a manual contact method. The refracted longitudinal wave mode of propagation was applied for all scans of the exam volume. Due to the design of the head-to-flange weld, "essentially 100 percent" of the required volume could not be obtained.

The weld is primarily accessible for scanning on the vessel head plate side of the weld. The combination of limited scanning surface on the flange side of the weld due to the flange blend radius curvature, and the thickness transition of the weld itself precludes obtaining further coverage of the excluded areas depicted in the sketches in Enclosure

3. These geometric configurations create areas where the transducer loses contact with the component surface which prevents adequate coupling necessary to transmit and Page 5 of 9 receive the ultrasonic sound energy. For the examination conducted, satisfactory results were achieved, and no flaw indications were detected.

In addition to the volumetric examination performed for the RPV head-to-flange weld (W-8), a surface examination was performed for the entire weld length, as specified by Table IWB-2500-1, Item 81.40, and no indications were detected.

Exam coverage determination:

As required by procedure, when limitations to lSI examinations are encountered that prevents obtaining full coverage of a required volume, the limitations are required to be quantified and recorded.

The method used to determine coverage is based on field measurements applied to a two dimensional plot. This allows an informed approximation to be made of the coverage achieved.

The methodology is appropriate to the application in that the limitations are physical and the methods applied to the examination are established by the qualified techniques.

The coverage drawings in Enclosure 3 give a representation of the examination volume and the weld interface line shown in Figure 2 of Code Case N-613-1 for the nozzle-to-vessel welds, and Figure IWB-2500-5 for the head-to-flange weld. The areas of examination volume coverage are identified by the cross-hatched areas on the drawings.

The remaining areas of the examination volume, with no cross-hatching, represent areas with no examination coverage.

The contour on the exterior surfaces of the nozzles and the flange weld transition causes transducer liftoff and inhibits the ability to maintain adequate coupling necessary to transmit and receive the ultrasonic sound energy. Additional coverage with meaningful results was not achievable or practical for the limited areas with implementation of performance based examination methods without redesigning and modifying the components to allow additional scanning surfaces.

NSPM has concluded that if significant service-induced degradation existed in the subject welds, it would have been identified by the examinations performed.

Per 10 CFR 50.55a(g)(1) and (4), each of the subject welds were examined to the extent practical.

For comparison with current results, Table B of Enclosure 4 provides examination results from Interval 3 for the subject welds, including coverage information and approved 10CFR50.55a Requests where applicable.

Materials, Aging Management, Similar Components:

The materials for the subject components are A508 Clll nozzle forgings and flange ring welded to A533 Cl I vessel shell plate. The weld filler material for the subject joints was E8018NM. Internal surface cladding materials are E309-15 for the base layer, and ER308L or E308L-15 for subsequent layers. Page 6 of 9 The MNGP reactor vessel water chemistry is controlled in accordance with the 2008 revision to the BWR Water Chemistry Guidelines (Reference 6). Also a hydrogen water chemistry system is used to reduce the oxidizing environment in the reactor coolant. These additional measures provide added assurance against the initiation of cracking or corrosion from the inside surface of the reactor vessel. An inerted primary containment environment during operation provides assurance of corrosion protection on the outside surface of the reactor vessel. Additionally, as Class 1 Examination Category B-P components, system pressure testing with VT-2 examinations are required every outage prior to startup. The VT-2 examinations were performed on the subject components in association with the RCPB system pressure test performed during the 2011 refueling outage. No evidence of pressure boundary leakage was identified during this system test. Twenty other nozzle-to-shell welds, as shown in Table C of Enclosure 4, have been examined during in the fourth Interval with limited coverage, and relief has been granted by the NRC pursuant to 10 CFR 50.55a(g)(6)(i).

Summary: The provisions described above, as an alternative to the code requirement for examination coverage, will continue to provide reasonable assurance of the structural integrity of the subject welds. The volumetric examinations were completed to the extent practical and no unacceptable flaws were identified.

The required surface exam was completed on the RPV head-to-flange weld with no indications detected.

VT-2 examinations performed on the subject components during system pressure testing each refueling outage in accordance with Examination Category B-P provide continued assurance that the structural integrity of the subject components is maintained.

Additionally, the MNGP Water Chemistry Program and inerted primary containment environment provide added measures of protection for the component materials.

Twenty other nozzle-to-shell welds, as shown in Table C of Enclosure 4, have been examined during in the fourth Interval with limited coverage, and relief has been granted by the NRC pursuant to 10 CFR 50.55a(g)(6)(i).

Therefore, pursuant to 10 CFR 50.55a(g)(5)(iii), NSPM requests that the NRC grant relief from the ASME Section XI examination requirements for the subject nozzle-to-vessel welds. 7. Duration of Proposed Alternative NSPM requests the granting of this relief for the Fourth Ten-Year lnservice Inspection Interval of the lnservice Inspection Program for the MNGP which concluded August 31, 2012. Page 7 of 9

8. Precedents The NRC has granted relief for other nozzle-to-vessel shell welds at the MNGP during the fourth Interval for the same type of limited examination coverage (References 7, 8, and 9). The NRC has granted relief for Grand Gulf Station Unit 1 (Reference 1 0) and Duane Arnold Energy Center (Reference

11) for limited examination coverage on RPV head-to-flange welds. REFERENCESFORENCLOSURE1

1. Regulatory Guide 1.147, "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1," Revision 16, July 2010. 2. ASME Section XI Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds." 3. ASME Section XI Code Case N-613-1, "Ultrasonic Examination of Full Penetration Nozzles in Vessels, Examination Category 8-D, Item No's. 83.10 and 83.90, Reactor Nozzle-To-Vessel Welds, Figures IW8-2500-7(a), (b), and (c)." 4. NRC Information Notice 98-42, "Implementation of 10 CFR 50.55a(g)

In-service Inspection Requirements." 5. EPRI Internal Report IR-2004-63, "Monticello Nozzle Inner Radius and Nozzle-to-Shell Weld Examinations," dated December 2004. 6. "8WRVIP-190:

8WR Vessel and Internals Project, 8WR Water Chemistry Guidelines-2008 Revision," EPRI Technical Report, TR-1016579, October 2008. 7. NRC letter to NMC, "Monticello Nuclear Generating Plant (MNGP)-Fourth 1 0-Year lntervallnservice Inspection (lSI) Program Plan Relief Request No. 13 (TAG No. MC8882)," dated July 18, 2006 (ADAMS Accession No. ML061780172).

8. NRC letter to NMC, "Monticello Nuclear Generating Plant (MNGP)-Granting of Relief Regarding Limited Ultrasonic Examination Coverage of Five Welds (TAG No. MD6854)," dated May 19, 2008 (ADAMS Accession No. ML081 050678). 9. NRC letter to MNGP, "Monticello Nuclear Generating Plant (MNGP)-Request for Relief No. 19 Concerning Examination Coverage of Certain Reactor Vessel Nozzle-to-Vessel Welds (TAG No. ME3937)," dated December 21, 2010 (ADAMS Accession No. ML 103400651).

Page 8 of 9

10. NRC letter to Grand Gulf Nuclear Station, "Grand Gulf Nuclear Station, Unit 1-Relief Requests GG-ISI-005 Through GG-ISI-012 for Second 10-Year lnservice Inspection Interval (TAG Nos. ME1376, ME1377, ME1378, ME1379, ME1380, ME1381, ME1382, and ME1383)," dated May 25, 2010 (ADAMS Accession No. ML 101410002).

11. NRC letter to Duane Arnold Energy Center, "Duane Arnold Energy Safety Evaluation for Request for Relief from Certain Requirements of the ASME Code to Allow Performance of Limited Examinations of Selected Welds (TAG No. ME1821)" dated July 6, 2010 (ADAMS Accession No. ML 101680600).

Page 9 of 9 ENCLOSURE 2 10 CFR 50.55a REQUEST NO. 21 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY TA8LEA 2011 Refueling Outage, Percent Coverage and Limitations Category 8-A, "Pressure Retaining Welds in Reactor Vessel," Item No. 81.40, Weld W-8 Category 8-D, "Full Penetration Welds of Nozzles in Vessels," Item No. 83.90, Nozzles N-1 8 and N-40 Code Code Component Category System and Percent and and Component Examination Volume Coverage Indications Exam Report Item No. Component Description ID Required Obtained Limitations Reported Number Reactor Vessel, Head-to-Flange Weld, Limited due 8-A Top Head W-8 Table IW8-2500-1, Cat 8-A 79% to flange None 2011UT049 81.40 Head-to-Flange Figure IW8-2500-5 configuration Reactor Vessel, Nozzle-to-Vessel Weld, Limited due 8-D to nozzle 2011 UT078 83.90 Recirculation Inlet N-18 NV Code Case N-613-1 83% configuration None 2011UT076 Nozzle N-18 Figure 2 Reactor Vessel, Nozzle-to-Vessel Weld, Limited due 8-D to nozzle 2011UT051 83.90 Feedwater Inlet N-48 NV Code Case N-613-1 83% configuration None 2011UT052 Nozzle N-48 Figure 2 -------Page 1 of 1 ENCLOSURE 3 10 CFR 50.55a REQUEST NO. 21 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY EXAM LIMITATIONS IMPOSED BY COMPONENT DESIGN AND CONSTRUCTION This enclosure contains a series of excerpts from the lSI Ultrasonic Testing (UT) reports applicable to the subject components.

These excerpts contain sketches depicting the component configuration with physical limitations imposed by the design, e.g., geometrical contour, weld position, interferences, and a cross sectional view depicting the UT coverage and limitations in relation to the required examination volume. Detail is also provided to describe the various assembly components including reference to the internal and external reactor vessel surfaces.

COMPONENT ID N-1 B NV N-4B NV W-8 REPORT 2011 UT078 2011UT051 2011UT049 Page 1 of 7 PAGE(S) Pages 2-3 Pages 4-5 Pages 6-7 Coverage drawings excerpted from applicable reports Component N-1 8 NV Axial (Radial) Scan Plot Report# 2011 UT078 XceiEnergr Nozzle on left side of weld; RPV shell on right side of weld Exterior of vessel at the top; Interior of vessel at the bottom Supplemental Report Report No.: 2011UT078 Monticello NIB Coverage Plot in Axial scan direction in 60 deg. Page 2 of 7 Component N-1 B NV Parallel (Circ) Scan Plot Report# 2011 UT078 XceiEnerg; Nozzle on left side of weld; RPV shell on right side of weld Exterior of vessel at the top; Interior of vessel at the bottom Report No. 2011 UT076 applicable to Inner 15% for eire scan Supplemental Report Report No.: 2011UT078 R5.25 in Monticello NIB Coverage Plot Parallel scan direction 5.25 in of coverage i -r 0.78 in H G F E Page 3 of7 Component N-40 NV Axial (Radial) Scan Plot Report# 2011 UT051 XceiEnergr Nozzle on left side of weld; RPV shell on right side of weld Exterior of vessel at the top; Interior of vessel at the bottom Supplemental Report Report No.: 2011lJT051 Monticello N4D Coverage PJ,ot Ax. I d. . -. 1a scan

• trectaon H G F E Page 4 of 7 Component N-40 NV Parallel (Circ) Scan Plot Report# 2011 UT051 XcaiEnergy-Nozzle on left side of weld; RPV shell on right side of weld Exterior of vessel at the top; Interior of vessel at the bottom Report No. 2011 UT052 applicable to Inner 15% for eire scan Supplemental Report Report No.: 2011UT051 R3.00ia Monticello N4D Coverage Plot Parallel scan direction rea of ex>veragc n o Page 5 of 7 Component W-8 Axial (Radial) Scan Plot Report# 2011 UT049 Head flange on left side of weld; RPV head plate on right side of weld Exterior surface of vessel head at the top; Interior surface of vessel head at the bottom XceiEnergy' Supplemental Report ReponNo..

2011UT04'&

4.30" D :Monticello Spring 2011 Upper Head to Flange Weld Weld:W-8 4.21" 3.94n 3.84" 9-Total Examination Area 22.08 Sq. Inches Area ofNo Coverage 3.32 Sq. Inches Area of Axial Coverage Achieved 18.76 Sqlncbes Page 6 of 7 3.72n Head c Component W-8 Parallel (Circ) Scan Plot Report# 2011 UT049 Head flange on left side of weld; RPV head plate on right side of weld Exterior surface of vessel head at the top; Interior surface of vessel head at the bottom XceiEnergr 4.30" Flange D Supplemental Report Monticello Spring2011 Upper Head to Flange Weld Weld:W-8 4.21 8 3.94" 3.84n 3.72n Area ofNo Coverage Total Examination Area 22.08 Sq. Inches c Area ofNo Coverage 5.94 Sq. Inches Area ofCirc Coverage Achieved 16.14 Sq.Inches Page 7 of 7 Report No.: 2011 UT049 Head Weld N-18 NV N-4D NV W-8 Weld N-1A NV N-2A NV N-28 NV N-2D NV N-2E NV N-2G NV N-2J NV N-3A NV N-3C NV N-4A NV N-48 NV N-4C NV ENCLOSURE 4 10 CFR 50.55a REQUEST NO. 21 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY Table B -Historical 3ra Interval Examination Information For 10 CFR 50.55a Request No. 21 Components Exam Exam Year Coverage Exam Results 10CFR50.55a Request NRC Approval Date 2001 62% No flaw indications 3rd, lSI RR-16 (Ref. 12) May 19, 2003 (Ref. 13) (Note 1) 2000 61% No flaw indications 3rd, lSI RR-11 (Ref. 14) Oct. 25, 2000 (Ref. 15) (Note 1) 2001 93% No flaw indications N/A N/A (Note 2) Table C:-Summary of 4m Interval Nozzle-to-Vessel Welds With Previously Approved NRC Relief for Exam Limitations Exam Exam Year Coverage Exam Results 10CFR50.55a Request NRC Approval Date 2005 83% No flaw indications RR-13 (Ref. 16) July 18, 2006 (Ref. 17) 2009 83% No flaw indications RR-19 (Ref. 18) Dec. 21,2010 (Ref. 19) 2007 78% No flaw indications RR-15 (Ref. 20) May 19, 2008 (Ref. 21) 2005 82% No flaw indications RR-13 (Ref. 16) July 18, 2006 (Ref. 17) 2005 78% No flaw indications RR-13 (Ref. 16) July 18, 2006 (Ref. 17) 2007 78% No flaw indications RR-15 (Ref. 20) May 19, 2008 (Ref. 21) 2005 78% No flaw indications RR-13 (Ref. 16) July 18, 2006 (Ref. 17) 2005 83% No flaw indications RR-13 (Ref. 16) July 18, 2006 (Ref. 17) 2009 83% 1 acceptable RR-19 (Ref. 18) Dec. 21, 2010 (Ref. 19) indication (Note 3) 2007 79% No flaw indications RR-15 (Ref. 20) May 19, 2008 (Ref. 21) 2009 83% No flaw indications RR-19 (Ref. 18) Dec. 21,2010 (Ref.19) 2005 79% No flaw indications RR-13 (Ref. 16) July 18, 2006 (Ref. 17) Note 1: Code coverage values when using Weld plus Y:! T per Figure IWB-2500-?(c), ASME Section XI, 1986 Edition Note 2: Relief was not required, exam coverage was essentially 100% (greater than 90%) Note 3: Sub-surface indication recorded in 1998 reconfirmed in 2009, no change (acceptable, IWB-3512-1).

Page 1 of 3 Table C: -Summary of 4m Interval Nozzle-to-Vessel Welds With Previously Approved NRC Relief for Exam Limitations Exam Exam Weld Year Coverage Exam Results 10CFR50.55a Request NRC Approval Date N-58 NV 2005 81% No flaw indications RR-13 (Ref. 16) July 18, 2006 (Ref. 17) N-6A NV 2007 86% No flaw indications RR-15 (Ref. 20) May 19, 2008 (Ref. 21) N-68 NV 2009 87% No flaw indications RR-19 (Ref. 18) Dec. 21, 2010 (Ref. 19) N-7NV 2009 87% No flaw indications RR-19 (Ref. 18) Dec. 21, 2010 (Ref. 19) N-8A NV 2005 83% No flaw indications RR-13 (Ref. 16) July 18, 2006 (Ref. 17) N-88 NV 2009 83% No flaw indications RR-19 (Ref. 18) Dec. 21, 2010 (Ref. 19) N-9 NV 2007 85% No flaw indications RR-15 (Ref. 20) May 19, 2008 (Ref. 21) N-10 NV 2009 85% No flaw indications RR-19 (Ref. 18) Dec. 21, 2010 (Ref. 19) REFERENCES FOR ENCLOSURE 4 12. MNGP letter to NRC, "Request for Review and Approval of Relief Request Nos. 15 and 16 for the Monticello 3rd 1 0-Year lntervallnservice Inspection Examination Plan," dated May 30, 2002 (ADAMS Accession No. ML021680035).

13. NRC letter to MNGP, "Monticello Nuclear Generating Plant-Third 10-Year lntervallnservice Inspection Relief Request No. 16, Parts A, B, and C (TAC No. MB5487)," dated May 19, 2003 (ADAMS Accession No. ML031400119).

14. MNGP letter to NRC, "Request for Relief No. 11 for the Monticello 3rd 10-Year lntervallnservice Inspection Program," dated May 25, 2000 (ADAMS Accession No. ML003720899).

15. NRC letter to MNGP, "Monticello Nuclear Generating Plant-Evaluation of Relief Request Number 11 for the Third 1 0-Year lntervallnservice Inspection Program Plan (TAC No. MA9114)," dated October 25, 2000 (ADAMS Accession No. ML003763033).

16. MNGP letter to NRC, "1 0 CFR 50.55a Request No. 13: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year lnservice Inspection Interval," dated September 27, 2005 (ADAMS Accession No. ML052760169).

17. NRC letter to MNGP, "Monticello Nuclear Generating Plant (MNGP)-Fourth 1 0-Year lntervallnservice Inspection (lSI) Program Plan Relief Request No. 13 (TAC No. MC8882)," dated July 18, 2006 (ADAMS Accession No. ML061780172).

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18. MNGP letter to NRC, "1 0 CFR 50.55a Request No. 19: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year lnservice Inspection Interval," dated May 6, 2010 (ADAMS Accession No. ML 1 01300050).

19. NRC letter to MNGP, "Monticello Nuclear Generating Plant (MNGP)-Request for Relief No. 19 Concerning Examination Coverage of Certain Reactor Vessel Nozzle-to-Vessel Welds (TAG No. ME3937)," dated December 21, 2010 (ADAMS Accession No. ML 103400651).

20. MNGP letter to NRC, "1 0 CFR 50.55a Request No. 15: Relief from Impractical Examination Coverage Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year lnservice Inspection Interval," dated September 26, 2007 (ADAMS Accession No. ML07271 0119). 21. NRC letter to MNGP, "Monticello Nuclear Generating Plant (MNGP)-Granting of Relief Regarding Limited Ultrasonic Examination Coverage of Five Welds (TAG No. MD6854)," dated May 19, 2008 (ADAMS Accession No. ML081050678).

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