L-MT-05-088, 10 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 Inservice Inspection Interval

10 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 Inservice Inspection Interval

ML052760169
Person / Time
Site:	Monticello
Issue date:	09/27/2005
From:	Conway J Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-MT-05-088
Download: ML052760169 (26)

Text

Monticello Nuclear Generating Plant NMC Operated by Nuclear Management Company, LLC Committed to Nulear Exeive September 27, 2005 L-MT-05-088 10 CFR 50.55a(g)(5)(iii)

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Monticello Nuclear Generating Plant Docket 50-263 License No. DPR-22 10 CFR 50.55a Request No. 13: Relief from Impractical Examination Coveraae Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii) for the Fourth Ten-Year Inservice Inspection Interval Pursuant to 10 CFR 50.55a(g)(5)(iii), the Nuclear Management Company, LLC requests relief from certain examination coverage requirements imposed by the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI, "Rules for Inservice 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 2005 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 specified requirements is impractical due to plant design.

MNGP is submitting this request for the Fourth Ten-Year Inservice Inspection Interval scheduled to end on May 31, 2012.

This letter contains no new commitments and makes no revisions to existing commitments.

hn T. onway Site Vice President, Monticello Nuclear Generating Plant Nuclear Management Company, LLC Enclosures (3) cc:

Administrator, Region ll, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC Minnesota Department of Commerce (Attn: L. Brandon) 2807 West County Road 75

• Monticello, Minnesota 55362-9637 Telephone: 763.295.5151

• Fax: 763.295.1454

ENCLOSURE I 10 CFR 50.55a REQUEST NO.13 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 Xl, Class 1, Reactor Vessel Nozzle-to-Vessel Shell welds specified below and in-detail in Table A:

Recirculation Suction Recirculation Inlet Recirculation Inlet Recirculation Inlet Main Steam Discharge Feedwater Inlet Core Spray Inlet Jet Pump Instrumentation Nozzle N-IA Nozzle N-2D Nozzle N-2E Nozzle N-2J Nozzle N-3A Nozzle N-4C Nozzle N-5B Nozzle N-8A Weld - N-IA NV Weld - N-2D NV Weld - N-2E NV Weld - N-2J NV Weld - N-3A NV Weld - N-4C NV Weld - N-5B NV Weld - N-8A NV

2.

Applicable ASME Section Xl Code Edition and Addenda The applicable ASME Section XI Code for the Monticello Nuclear Generating Plant (MNGP), Fourth Ten-Year Inservice Inspection (ISI) Interval is the 1995 Edition with the 1996 Addenda.

3.

Applicable Code Requirement

ASME Class 1 Nozzle-to-Vessel Shell welds are subject to the examination requirements of Subsection IWB Table IWB-2500-1, as shown below, and are required to be examined once within the Fourth Ten-Year Interval:

Code Class:

References:

Examination Category:

Item Number:

==

Description:==

Component Numbers:

System:

Examination Method:

I IWB-2500, Table IWB-2500-1 B-D B3.90 Nozzle-to-Vessel Shell Welds See Section 1 and Table A Reactor Vessel Volumetric - Ultrasonic Testing (UT)

In lieu of the examination volume depicted in Figure IWB-2500-7(b), the United States Nuclear Regulatory Commission (NRC) has authorized the NMC to use the alternative examination volume requirements of Code Case N-613-1 (Reference 1) for the Nozzle-to-Vessel Shell welds listed in this request.

Page 1 of 6

ENCLOSURE I 10 CFR 50.55a REQUEST NO. 13 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY The MNGP Fourth Ten-Year Interval Inservice Inspection Plan also implements Code Case N-460 (Reference 2), which is endorsed by the NRC in Regulatory Guide 1.147 (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 10 percent."

NRC Information Notice (IN) 98-42 (Reference 4) termed a reduction in coverage of less than 10 percent to be "essentially 100 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 Xl.'

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 Xl were formalized and published. Because this plant was not specifically designed to meet the requirements of ASME Section XI, full compliance is not feasible or practical within the limits of the current plant design.

10 CFR 50.55a recognizes the limitations to in-service inspection of components in accordance with Section Xl of the ASME Code, that are imposed due to early plants' design and construction, as follows:

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.

Page 2 of 6

ENCLOSURE I 10 CFR 50.55a REQUEST NO. 13 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY 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 primarily due to inherent nozzle design geometric contours with some additional, minor interference from nearby welded attachments (see Table A).

A description of the examination methodology used to provide the maximum obtainable coverage is provided in Section 6 of this request. This methodology is based on ASME Section Xl, Appendix Vill 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 volume requirements of Code Case N-613-1, Figure 2.

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 on the basis that the required examination coverage of "essentially 100 percent" is impractical due to physical obstructions and the limitations imposed by design, geometry and materials of construction.

NMC performed qualified examinations that achieved the maximum, practical amount of coverage obtainable within the limitations imposed by the design of the components. Additionally, as Class 1 examination Category B-P components, a VT-2 examination is performed on the subject components of the Reactor Coolant Pressure Boundary during system pressure tests each refueling outage. This was completed during the 2005 refueling outage and no evidence of leakage was identified for these components.

Page 3 of 6

ENCLOSURE I 10 CFR 50.55a REQUEST NO. 13 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY Therefore, pursuant to 10 CFR 50.55a(g)(5)(iii), NMC requests relief from the requirements of ASME Section Xl Table IWB-2500-1, Category B-D, Item B3.90 and associated Code Cases, and proposes to utilize these completed exams as an acceptable alternative that provides reasonable assurance of continued structural integrity.

Basis For Use The MNGP Nondestructive Examination (NDE) procedures incorporate improved inspection techniques qualified under Appendix VIII of the ASME Section Xl Code by the Performance Demonstration Initiative (PDI) for examination of the subject nozzle-to-shell welds.

Coverage was obtained by following the scan parameters defined by the MNGP specific Electric Power Research Institute (EPRI) computer modeling report (Reference 5) for each nozzle configuration and angle, and as designated within MNGP NDE procedures.

The examinations were performed using a manual contact method from the nozzle outside blend and vessel shell surfaces as discussed in the EPRI modeling report and as stated in MNGP procedures. The shear wave mode of propagation was used for each of the transducer and wedge combinations required for the inner 15 percent of the required parallel scan volume. The refracted longitudinal wave mode of propagation was used for the remaining outer 85 percent of the volume for parallel scans, and all of the perpendicular scans.

The subject components received the required examination(s) to the extent practical within the limited access of the component design. For the examinations conducted, satisfactory results were achieved, and no evidence of unacceptable flaws were detected with the improved inspection techniques.

Due to the design of these welds it was not feasible to effectively perform a volumetric examination of 100 percent of the volume as described in IWB-2500-7(b). The nozzle-to-vessel welds are accessible from the vessel shell side of the weld, but examinations cannot be performed from the nozzle side of the weld because of the forging curvature. In addition, due to component configuration, certain nozzle-to-vessel weld examinations are further limited by the reactor pressure vessel design obstructions (such as appurtenances).

Additional coverage for the limited areas was not achievable or practical, based on the latest qualified ultrasonic technology, nor by other considered examinations methods, such as radiography. MNGP has concluded that if Page 4 of 6

ENCLOSURE 1 10 CFR 50.55a REQUEST NO. 13 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY significant degradation existed in the subject welds, it should have been identified by the examinations performed.

Additionally, as Class 1 examination category B-P components, VT-2 examinations were performed on the subject components in association with the Reactor Coolant Pressure Boundary system pressure test performed during the 2005 refueling outage, and no evidence of leakage was identified.

The materials for the subject components are A533 Cl I nozzle forgings welded to A508 C III vessel shell plate. A review of operating experience within the nuclear industry did not reveal any instances of cracking in this location and type of weldment.

The MNGP reactor vessel water chemistry is controlled in accordance with the 2004 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 for the subject components listed in this request. An inerted primary containment environment during operation provides assurance of corrosion protection on the outside surface of the reactor vessel.

Based on the above, with due consideration of the earlier plant design, the underlying objectives of the Code required volumetric examinations have been met. The examinations were completed to the extent practical and evidenced no unacceptable flaws present. 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.

7.

Duration of Proposed Alternative NMC requests the granting of this relief for the Fourth Ten-Year Inservice Inspection Interval of the Inservice Inspection Program for the MNGP that is scheduled to end on May 31, 2012.

8.

Precedents The NRC has granted relief for the MNGP for previous ten-year inservice inspection intervals, most recently the Third Ten-Year Inservice Inspection Interval (Reference 7). Also, the NRC has granted relief for the Quad Cities Nuclear Power Station, Units 1 and 2 (Reference 8), the Dresden Nuclear Power Page 5 of 6

ENCLOSURE I 10 CFR 50.55a REQUEST NO.13 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY Station, Units 2 and 3 (Reference 9), and the Prairie Island Nuclear Generating Plant, Unit 2 (Reference 10).

REFERENCES

1.

ASME Section Xi Code Case N-613-1, "Ultrasonic Examination of Full Penetration Nozzles in Vessels, Examination Category B-D, Item No's. B3.10 and B3.90, Reactor Nozzle-To-Vessel Welds, Figures IWB-2500-7(a), (b),

and (c)."

2 ASME Section Xl Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds."

3.

Regulatory Guide 1.147, "Inservice Inspection Code Case Acceptability, ASME Section Xl, Division 1," Revision 13, January 2004.

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."

6.

BWRVIP-130, "BWR Water Chemistry Guidelines - 2004 Revision" (EPRI Topical Report TR-1 008192).

7.

NRC letter to NMC, "Monticello Nuclear Generating Plant Third 10-Year Interval Inservice Inspection Relief Request No. 16, Parts A, B and C (TAC No.

MB5487)," dated May 19, 2003.

8.

Letter from NRC to Commonwealth Edison Company, "Quad Cities, Units I and 2 - Relief Request CR-32 for Third 10-Year Inservice Inspection Interval," dated September 6, 2000.

9.

Letter from NRC to Exelon Generation Company, LLC, "Dresden Nuclear Power Station, Units 2 and 3 - Relief Request CR-24 For Third 10-Year Inservice Inspection Interval," dated January 8, 2003.

10.

NRC letter to NMC, 'Prairie Island Nuclear Generating Plant, Unit 2 - Evaluation of Relief Request No. 16 for the Unit 2 3rd 10-year Interval Inservice Inspection Program (TAC No. MC1775)," dated October 18, 2004.

Page 6 of 6

ENCLOSURE 2 10 CFR 50.55a REQUEST NO. 13 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY TABLE A - Category B-D, "Full Penetration Welds of Nozzles in Vessels," Item No. B3.90 Percent Coverage and Limitations for Nozzles N-1A, N-2D, N-2E, N-2J, N-3A, N-4C, N-5B, and N-8A Code System Code Component Category and Component and Percent Exam and Component ID Examination Volume Coverage Report Item No.

Description Required Obtained Limitations Number Limited due to nozzle Reactor Vessel, Nozet-eslWlconfiguration.

Also, small B-D Recirculation Nz-A NV to-Vessel We, 8reduction due to interference 2005UT041 83.90 Suction Fiue2from welded thermocouple Nozzle N-1A attachments.

Limited due to nozzle B-D configuration. Also, small B3.90 Reactor Vessel, Nozzle-to-Vessel Weld, reduction due to interference Recirculation Inlet N-2D NV Code Case N-613-1 82%

from welded thermocouple 2005UT0 Nozzle N-20 Figure 2 attachment.

Reactor Vessel, Nozzle-to-Vessel Weld, Limited due to nozzle B-D Recirculation Inlet N-2E NV Code Case N-613-1 78%

configuration.

2005UT016 B3.90 Nozzle N-2E Figure 2 B-0 Reactor Vessel, Nozzle-to-Vessel Weld, Limited due to nozle BRecirculation Inlet N-2J NV Code Case N-613-1 78%

configuration.

2005UT005 Nozzle N-2J Figure 2 Reactor Vessel, Nozzle-to-Vessel Weld, Limited due to nozzle B-D Main Steam N-3A NV Code Case N-613-1 83%

configuration.

2005UT023 B3.90 Discharge Fgr Nozzle N-3A Fgr BD Reactor Vessel, Nozzle-to-Vessel Weld, Limited due to nozzle BD Feedwater Inlet N-4C NV Code Case N-613-1 79%

configuration.

2005UT025 83.90 Nozzle N-4C Figure 2 Page 1 of 2

ENCLOSURE 2 10 CFR 50.55a REQUEST NO. 13 IN ACCORDANCE WITH 10 CFR 50.55a(g)(5)(iii)

INSERVICE INSPECTION IMPRACTICALITY Code System Code Component Category and Component and Percent*

Exam and Component ID Examination Volume Coverage Report Item No.

Description Required Obtained Limitations Number Limited due to nozzle B-D Reco esl ozet-eslWlconfiguration.

Also, small B3.90 RCtorVe Ssel, Nz N-5z NV lCode Case Nl13-1 Wd1%

reduction due to interference 2005UT018 Corze Spray Inet N-BNV Coe rae N21-8%

from welded thermocouple Nozzl N-5 Figre 2attachments.

Limited due to nozzle B-D Reator Vessel, Nozzle-to-Vessel Weld, configuration.

B3.90 Jet Pump N-8A NV Code Case N-613-1 83%

2005UT037

.nstrmentation Figure 2 Nozzle N-8A.

Due to the nozzle design it was not feasible to effectively examine essentially 100 percent of the required examination volume as defined in Figure 2 of Code Case N-613-1. Percentages are conservatively rounded down to the nearest whole number. It should be noted that 100 percent of the inner 15 percent was examined in the parallel scans for all components listed above.

Page 2 of 2

ENCLOSURE 3 10 CFR 50.55a REQUEST NO. 13 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 ISI 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.

Also included is a sketch of a typical nozzle contour and the resulting affect that causes the UT transducer to lose coupling contact when it reaches the nozzle blend radius.

COMPONENT REPORT N-1A NV N-2D NV N-2E NV N-2J NV N-3A NV N-4C NV N-5B NV N-8A NV 2005UT041 2005UT028 2005UT016 2005UT005 2005UT023 2005UT025 2005UT018 2005UT037 PAGE(S)

Pages 1-3 Pages 4-5 Pages 6-7 Pages 8-9 Page 10 Pages 11-12 Pages 13-14 Page 15 Typical Nozzle Contour Affecting Transducer Contact Page 16 16 Pages Follow

Coverage drawings excerpted from applicable reports Component-N-IA NV Report# 2005UT041 Supplemental Report Report No.:

2005UT041 Summary No.: 102652 Comments: Parallel scan limitation due to radius area, no contact Axial scan limitation duo to transducer size and radius area, no contact PR5.25 in in Page 1 of 16

Component - N-IA NV Report # 2005UT041 Limitation Record Summary No.:

102652 Report No.:

2005UT041 Description of Umita'onr 4 Limitation due to thermocouple.

Monticello NI Coverage Plot Axial scan direction Page 2 of 16

Component-N-IA NV Report# 2005UT041 Supplemental Report Report No.:

2005UT041 S. ma N.. 125 Summary No.: 102652 Comments: 4' UmitatIon due to thermocouple at 18 12 counter clockwise.

467-z1k ta

¶tr!'~L EX Page 3 of 16

Component - N-2D NV Report # 2005UT028 A. -NM9

~

Supplemental Report Report No-,

2005UT028 Summary No.: 102662 Comments: Monticello #42D Coverage plots.

• Axial scan limitation due to transducer size and radius area, no contact.

I Parallel scan limitation due to radius area, no contact.

I<r' Monticello N2D Coverage Plot Axial scan direction

.1 j ;_ 6s &

R3.50 in Monticello N2D Coverage Plot Parallel scan direction BS n~

Q in Page 4 of 16

S.

Summary No.: 102B62 Component - N-2D NV Report # 2005UT028 Supplemental Report Report No.:

200SUTO28 Comments:

3" U.mitatlon due to thermocouple at 79" clockwise.

C I-i :".

Page 5 of 16

Component - N-2E NV Report # 2005UT016 Supplemental Report Repoit No.:

2005UT016 Summary No.: 102664 Comments:

Limitation due to radius area, no contact R3.50 in Monticello NT2 Coverage Plot I\\

Parallel scan direction in Page 6 of 16

Component - N-2E NV Report # 2005UT016 iii
.IF -

-
'.

r... -:

' -WMQ

. -.
l

Supplemental Report Report No.:

2005UTD16 Summary No.: 102664 Comments' Unitation due to transducer shzo and radius area, no contact Page 7 of 16

Component - N-2J NV Report # 2005UT005 Su-mr N:

1--I1;

'SummarjNo.:

102672 Supplemental Report Report No:

2005UT005 Comments:

Limtation due to radius area, no contact.

R3.50 in Monticello N2 Coverage Plot Parallel scan direction in Page 8 of 16

Component - N-2J NV Report # 2005UT005 M

,,F.,.. -9 Supplemental Report Report No-2005UT005 Summary No.: 102672 Comments:

UrnitatIon due to transducer size and radius area, no contact.

Monticello N2 Coverage Plot Axial scan direction

_ A an A Un Page 9 of 16

Component - N-3A NV Report # 2005UT023 NMC Supplemental Report Report No:

200SUT023 Summary No: 102675 Comments:

Monticello N3 Coverage Plot "Axial scan lImitation duo to transducer size and radius area, no contact

• Parallel scan limitation duo to radius area, no contact I

Monticello N3 Coverage Plof Parallel scan direction SI iin Page 10 of 16

Component - N-4C NV Report # 2005UT025

'.N

. I Supplemental Report Report No.:

21005UT025 SumrnaryNo.: 102688 Comments: Lrnitation due to radius area, no contact

)nticello N4 Coverage Plot Parallel scan direction Page 11 of 16

Component-N4C NV Report # 2005UT025 I.I

I 1

Supplemental Report Report No_

L2005UT2.5 Summary No; 102688 Comments: Limifation due to transducer size and radius arca. no contact i

Monticello N4 Cove.

Axial scan direction A

60deg.

X B D

rage Plot

'NO L of coveragC 60 deg.

y'r1 IF II Page 12 of 16

Component-N-5B NV Report# 2005UT018

[

i.

,J.-

+;

Supplemental Report Report No.:

2005UTO1B -

Summary No.: 102694 Comments: Monticello N5B Coverage Plot

• Axial-scan limitation duo to transducer size and radius area, no contact

' Parallel scan limitation due to radius area, no contact.

Page 13 of 16

Component-N-5B NV Report# 2005UT018 Supplemental Report Report No.:

2005UT018 NI}

-9, Summary No.: 102694 Comments: 7' Umitatlon due to thermocouple top dead center of nozle.

N-B Nomle to Vessel Weld r-1, -

Page 14 of 16

. I Component - N-8A NV Report # 2005UT037 I

rim

! a'-,,

I Supplemental Report Report No.:

2005UT037 Summary No.: 102696 Comments: Monticello NS Coverage Plots.

• Axlal scan limitation due to transducer sizo and radius area, no contact

• Parallel scan limitation due to radius area, no contact.

\\, 'Monticello N8 Coverage Plot Parallel scan direction Page 15 of 16

Typical for Nozzle Limitations Coverage affected by liftoff dueto radius

.N2 Nozzle sh1w0 as-xample Page 16 of 16