RS-09-044, Request for Alternative to Nozzle-to-Vessel Weld and Inner Radius Examinations

Request for Alternative to Nozzle-to-Vessel Weld and Inner Radius Examinations

ML090721084
Person / Time
Site:	Dresden
Issue date:	03/13/2009
From:	Hansen J Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-09-044
Download: ML090721084 (10)

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Exelon Generation wwwexeloncorp.cow Nuclear 4300 WSnfield Road Warrernvdle, IL 60555 10 CFR 50.55a March 13, 2009 RS-09-044 U. S . Nuclear Regulatory Commission ATTN : Document Control Desk Washington, D.C . 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating Licenses Nos. DPR-19 and DPR-25 NRC Docket Nos . 50-23 7and 50-249

Subject:

Request for Alternative to Nozzle-to-Vessel Weld and Inner Radius Examinations In accordance with 10 CFR 50.55a, "Codes and standards," paragraph (a)(3)(i), Exelon Generation Company, LLC (EGC) is requesting relief from the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," (ASME Section XI).

Specifically, EGC requests NRC approval to implement an alternative from ASME Section XI, Table IWB-2500-1, "Examination Category B-D, Full Penetration Welded Nozzle in Vessels -

Inspection Program B," to allow reduced percentage requirements for Nozzle-to-Vessel Weld and Inner Radius Examinations at Dresden Nuclear Power Station (DNPS), Units 2 and 3.

This requested relief is consistent with ASME Code Case N-702, "Alternative Requirements for Boiling Water Reactor Nozzle Inner Radius and Nozzle-to-Shell Welds." EGC is requesting this relief for the remainder of the fourth ten-year interval of the DNPS Inservice Inspection Program, which began on January 20, 2003.

The NRC has recently approved a similar request to adopt an alternative to ASME Section XI, Table IWB-2500-1 to allow reduced percentage requirements for Nozzle-to-Vessel Weld and Inner Radius Examinations for the Duane Arnold Energy Center. This approval is documented in ADAMS Accession Number ML082040046 .

March 13, 2009 U . S. Nuclear Regulatory Commission Page 2 The request is described in the attachment to this letter . EGC requests approval of this request by March 13, 2010 .

There are no regulatory commitments contained within this letter . If there are any questions or comments, please contact Ms. Michelle Yun at (630) 657-2818 .

ctfully, j

eif'My N . Hansen Manager - Licensing Attachment : Dresden Nuclear Power Station, Units 2 and 3, Relief Request 14R-16  : Relief Request 14R-16, Applicable Nozzles : Relief Request 14R-16, Plant Specific Applicability

Attachment Dresden Nuclear Power Station, Units 2 & 3 Relief Request 14R-16

Attachment Relief Request Number: 14R-16 Proposed Alternative In Accordance with 10 CFR 50.55a(a)(3)(1)

Which Provides an Acceptable Level of Quality or Safety 1 .0 ASME Code Component(s) Affected Code Class: 1 Component Numbers : N2, N3, N8, N18, N19 and N20 Nozzles (See Enclosure 1 for complete list of nozzle identifications)

Examination Category: B-D (Inspection Program B)

Item Number: B3.90 and B3 .100

Description:

Alternative to ASME Section XI, Table IWB-2500-1 2.0 Applicable Code Edition and Addenda Dresden Nuclear Power Station (DNPS) is currently in the fourth 10-year Inservice Inspection (ISI) Program interval and is committed to American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components," (ASME Section XI),

1995 Edition through 1996 Addenda. Additionally, for ultrasonic examinations, ASME Section XI, Appendix VIII, "Performance Demonstration for Ultrasonic Examination Systems," of the 1995 Edition through 1996 Addenda is implemented, as required and modified by 10 CFR 50.55a(b)(2)(xv) .

3.0 Applicable Code Requirement Table IWB-2500-1, "Examination Category B-D, Full Penetration Welded Nozzle in Vessels - Inspection Program B" Class 1 nozzle-to-vessel weld and nozzle inner radii examination requirements are delineated in Item Number B3.90, "Nozzle-to-Vessel Welds," and B3 .100, "Nozzle Inside Radius Section ." The required method of examination is volumetric . All nozzles with full penetration welds to the vessel shell (or head) and integrally cast nozzles are examined each interval .

All of the nozzle assemblies identified in Enclosure 1 are full penetration welds.

4.0 Reason for Request Enclosure 1 provides a complete listing of the applicable Reactor Pressure Vessel (RPV) nozzles.

The proposed alternative provides an acceptable level of quality and safety, and the reduction in scope could provide a dose savings of as much as 7 Person-Rem for Unit 2 and 8 Person-Rem for Unit 3 over the remainder of the interval .

Attachment Relief Request Number: 14R-16 5.0 Proposed Alternative and Basis for Use In accordance with 10 CFR 50.55a(a)(3)(i), relief is requested from performing the required examinations on 100 percent of the nozzle assemblies identified in Tables 5-1 and 5-2 below (see Enclosure 1 for complete list of RPV Nozzles) . As an alternative for all welds and inner radii identified in Tables 5-1 and 5-2, EGC proposes to examine a minimum of 25 percent of the DNPS, Unit 2 and Unit 3, nozzle-to-vessel welds and inner radius sections, including at least one nozzle from each system and nominal pipe size, in accordance with Code Case N-702 . For the nozzle assemblies identified in Enclosure 1, this would mean one from each of the groups identified below:

Table 5-1 DNPS, Unit 2 Summary Group Total Number Minimum Number to Comments be Examined Recirculation 10 3 Five completed : three in 2003 Inlet (N2) during D2R18, two in 2007 during D2R20.

Main Steam 4 1 None completed .

N3 Core Spray 2 1 Two completed: one in 2003 (N19) during D2R18 and one in 2007 during D2R20.

Nozzles on 3 1 None completed.

Vessel Top Head (N8, N18 Jet Pump 2 1 One completed during 2005 (N20) during D2R19.

Therefore, two nozzles remain to be inspected for the remainder of the interval for DNPS, Unit 2: one Nozzle on Vessel Top Head (N8, N18) nozzle and one Main Steam (N3) nozzle .

Attachment Relief Request Number: 14R-16 Table 5-2 DNPS, Unit 3 Summary Group Total Minimum Number Comments Number to be Examined Recirculation 10 3 Four completed: two in 2004 during Inlet (N2) D3R18, Two in 2008 during D3R20.

Main Steam 4 1 Two completed: one in 2004 during (N3) D3R18 and one in 2006 during D3R19.

Core Spray 2 1 Two completed: one in 2004 during (N19) D3R18 and one in 2008 during D3R20.

Nozzles on 3 1 Three completed in 2006 and 2008.

Vessel Top Head (N8, N18 Jet Pump mp ~2 ~1 I None completed .

Therefore, one nozzle remains to be inspected for the remainder of the interval for DNPS, Unit 3: one Jet Pump (N20) nozzle .

Code Case N-702 stipulates that a VT-1 examination may be used in lieu of the volumetric examination for the inner radii (i .e ., Item No. B3.100, "Nozzle Inside Radius Section"). EGC is not currently using Code Case N-648-1 at DNPS for the identified components on enhanced magnification visual examination and has no plans of using Code Case N-648-1 on those components in the future . Volumetric examinations of all nozzle inside radius section will be completed.

Electric Power Research Institute (EPRI) Technical Report 1003557, "BWRVIP-108:

Boiling Water Reactor Vessel and Internals Project Technical Basis for the Reduction of Inspection Requirements for the Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Blend Radii," provides the basis for Code Case N-702. The evaluation found that failure probabilities at the nozzle blend radius region and nozzle-to-vessel shell weld due to a Low Temperature Overpressure event are very low (i .e., <1 x 10-6 for 40 years) with or without inservice inspection. The report concludes that inspection of 25 percent of each nozzle type is technically justified.

This EPRI report was approved by the NRC in a safety evaluation (SE)dated December 19, 2007 (i .e., ADAMS Accession No. ML073600374) . Section 5.0, "Plant Specific Applicability," of the SE indicates that each licensee who plans to request relief from the ASME Code,Section XI requirements for RPV nozzle-to-vessel shell welds and nozzle inner radius sections may reference the BWRVIP-108 report as the technical basis for the use of ASME Code Case N-702 as an alternative. However, each licensee should demonstrate the plant specific applicability criteria from the

Attachment Relief Request Number: 14R-16 BWRVIP-108 report to its units in the relief request by showing that all the general and nozzle-specific criteria addressed below are satisfied (i .e., as described in Enclosure 2).

The maximum RPV heatup/cooldown rate is limited to less than 115 °F per hour.

DNPS Technical Specification (TS) 3.4.9,"RCS Pressure and Temperature (P/r) Limits," provides a limiting condition for operation (LCO) . The heatup/cooldown rate is referenced in the DNPS operating procedures where applicable such as scrams and start-ups. This heatup/cooldown rate is also described in the DNPS Updated Final Safety Analysis Report (UFSAR),

Section 5.3.2, "Pressure-Temperature Limits," and UFSAR Table 5 .1-1, "Reactor Coolant System Data."

(2) For the Recirculation Inlet Nozzles, the following criteria must be met:

a. (pr/t)/CRPV<1 .15; The calculation for the DNPS N2 Nozzle results in 1 .065, which is less than 1 .15

b. [p(r 2 +r ; 2)/(r 2- r; 2 )]/CNOZZLE<1 .15; The calculation for the DNPS N2 Nozzle results in 0.972, which is less than 1 .15.

For the Recirculation Outlet Nozzles, the following criteria must be met:

a. (pr/t)/CRPv< 1 .15; The calculation for the DNPS N1 Nozzle results in 1 .273, which is higher than 1 .15 .

b. [p(r2+r, 2 )/(r2-r2 )]/CNO,zLE<1 .15; The calculation for the DNPS N1 Nozzle results in 0.840, which is less than 1 .15.

Based upon the above information, all DNPS RPV nozzle-to-vessel shell full penetration welds and nozzle inner radii sections, with the exception of the Recirculation Outlet Nozzles, meet the general and nozzle-specific criteria in BWRVIP-108 . Therefore, Code Case N-702 is applicable.

Therefore, use of Code Case N-702 provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(a)(3)(i) for all RPV nozzle-to-vessel shell full penetration welds and nozzle inner radii sections, with the exception of the Recirculation Outlet Nozzles.

6.0 Duration of Proposed Alternative The proposed alternative will be used for the remainder of the fourth 10-year interval of the DNPS ISI Program .

7.0 Precedents The NRC has recently approved a similar request for the Duane Arnold Energy Center . This approval is documented in ADAMS Accession Number ML082040046.

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Enclosure 1 Relief Request Number 1413-16 Applicable Nozzles Unit 2 Applicable Nozzles Component ID Category Item System Nominal Comments Number Number Pie Size N2A Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2007 N2A IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2007 N2B Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2007 N2B IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2007 N2C Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2003 N2C IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2003 N2D Nozzle B-D B3 .90 Recirc Inlet 12" N2D IRS B-D B3 .100 Recirc Inlet 12" N2E Nozzle B-D B&90 Recirc Inlet 12" N2E IRS B-D B3 .100 Recirc Inlet 12" N2F Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2003 N2F IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2003 N2G Nozzle B-D B3 .90 Recirc Inlet 12" N2G IRS B-D B3 .100 Recirc Inlet 12" N2H Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2003 N2H IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2003 N2J Nozzle B-D B3 .90 Recirc Inlet 12" N2J IRS B-D B3 .100 Recirc Inlet 12" N2K Nozzle B-D B3 .90 Recirc Inlet 12" N2K IRS B-D B3.100 Recirc Inlet 12" N2L Nozzle B-D B3 .90 Recirc Inlet 12" N2L IRS B-D B3 .100 Recirc Inlet 12" N3A Nozzle B-D B3 .90 Main Steam 20" N3A IRS B-D B3 .100 Main Steam 20" N3B Nozzle B-D B3 .90 Main Steam 20" N3B IRS B-D B3 .100 Main Steam 20" N3C Nozzle B-D B3 .90 Main Steam 20" N3C IRS B-D B3 .100 Main Steam 20" N3D Nozzle B-D B3 .90 Main Steam 20" N3D IRS B-D B3 .100 Main Steam 20" N8 Nozzle B-D B3 .90 Head Vent 4" N8 IRS B-D B3 .100 Head Vent 4" N18A Nozzle B-D B3 .90 Head Spray 6" N18A IRS B-D B3 .100 Head Spray 6' N18B Nozzle B-D B3 .90 Head Spray 6-Spare N18B IRS B-D B3 .100 Head Spray 6" Spare N19A Nozzle B-D B3 .90 Core Spray 10" PDI Exam 2007 N19A IRS B-D B3 .100 Core Spray 10" PDI Exam 2007 N19B Nozzle B-D B3 .90 Core Spray 10" PDI Exam 2003 N19B IRS B-D B3 .100 Core Spray 10" PDI Exam 2003 N20A Nozzle B-D B3 .90 Jet Pump 4" PDI Exam 2005 Instrumentation N20A IRS B-D B3 .100 Jet Pump 4" PDI Exam 2005 Instrumentation N20B Nozzle B-D B3 .90 Jet Pump 4" Instrumentation N20B IRS- - I B-D B3 .100 Jet Pump 4~

Instrumentation

Enclosure 1 Relief Request Number 14R-16 Applicable Nozzles Unit 3 Applicable Nozzles Component ID Category Item System Nominal Comments Number Number Pipe Size N2A Nozzle B-D B3.90 Recirc Inlet 12" N2A IRS B-D B3 .100 Recirc Inlet 12" N2B Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2008 N2B IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2008 N2C Nozzle B-D B3 .90 Recirc Inlet 12" N2C IRS B-D B3 .100 Recirc Inlet 12" N2D Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2004 N2D IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2004 N2E Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2004 N2E IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2004 N2F Nozzle B-D B3 .90 Recirc Inlet 12" N2F IRS B-D B3 .100 Recirc Inlet 12" N2G Nozzle B-D B3 .90 Recirc Inlet 12" PDI Exam 2008 N2G IRS B-D B3 .100 Recirc Inlet 12" PDI Exam 2008 N2H Nozzle B-D B3 .90 Recirc Inlet 12" N2H IRS B-D B3 .100 Recirc Inlet 12" N2J Nozzle B-D B3 .90 Recirc Inlet 12" N2J IRS B-D B3 .100 Recirc Inlet 12" N2K Nozzle B-D B3 .90 Recirc Inlet 12" N2K IRS B-D B3 .100 Recirc Inlet 12" N2L Nozzle B-D B3 .90 Recirc Inlet 12" N2L IRS B-D B3 .100 Recirc Inlet 12" N3A Nozzle B-D B3 .90 Main Steam 20" N3A IRS B-D B3 .100 Main Steam 20" N3B Nozzle B-D B3 .90 Main Steam 20" N3B IRS B-D B3 .100 Main Steam 20" N3C Nozzle B-D B3 .90 Main Steam 20" PDI Exam 2004 N3C IRS B-D B3 .100 Main Steam 20" PDI Exam 2004 N3D Nozzle B-D B3 .90 Main Steam 20" PDI Exam 2006 N3D IRS B-D B3 .100 Main Steam 20" PDI Exam 2006 N8 Nozzle B-D B3 .90 Head Vent 4" PDI Exam 2006 N8 IRS B-D B3 .100 Head Vent 4" PDI Exam 2008 N18A Nozzle B-D B3 .90 Head Spray 6" PDI Exam 2006 N18A IRS B-D B3 .100 Head S ra 6" PDI Exam 2008 N18B Nozzle B-D B3 .90 Head Spray 6" PDI Exam 2006 Spare N18B IRS B-D B3 .100 Head Spray 6" PDI Exam 2008 Spare N19A Nozzle B-D B3 .90 Core Spray 10" PDI Exam 2008 N19A IRS B-D B3.100 Core Spray 10" PDI Exam 2008 N19B Nozzle B-D B3 .90 Core Spray 10" PDI Exam 2004 N19B IRS B-D B3 .100 Core Spray 10" PDI Exam 2004 N20A Nozzle B-D B3 .90 Jet Pump 4" Instrumentation N20A IRS B-D B3 .100 Jet Pump 4" Instrumentation N20B Nozzle B-D B3 .90 Jet Pump 4" Instrumentation N20B IRS B-D B3 .100 Jet Pump 4" Instrumentation

Enclosure 2 Relief Request Number 14R-16 Plant Specific Applicability (1) The maximum Reactor Pressure Vessel (RPV) heatup/cooldown rate is limited to less than 115 °F/hour .

Response : DNPS Technical Specification (TS) 3 .4.9,"RCS Pressure and Temperature (P/T) Limits," provides a limiting condition for operation (LCO) . The heatup/cooldown rate is referenced in the Dresden operating procedures where applicable such as scrams and start-ups .

This heatup/cooldown rate is also described in the DNPS Updated Final Safety Analysis Report (UFSAR) Section 5.3 .2, "Pressure-Temperature Limits," and UFSAR Table 5.1-1, "Reactor Coolant System Data."

For Recirculation Inlet Nozzles (2) (pr/t)/CRPV< 1 .15 p=RPV Normal Operating Pressure 1005 r=RPV inner radius 125 .5 t=RPV wall thickness 6.125 CPv= 19332 (pr/t)/C RPV = 1 .065 <1 .15 2 o 2-

[p(r +r 2)/(r ri2)]/CNOZZLE< 1 .15 p=RPV Normal Operating Pressure 1005 ro=nozzle outer radius 12 .5 ri=nozzle inner radius 5.941 CNll=i F 1637

[p(r2 +rig )/(r2-rl2)KNOZZLE 0.972 <1 .15 For Recirculation Outlet Nozzles (4) (pr/t)/CRPv< 1 .15 p=RPV Normal Operating Pressure 1005 r=RPV inner radius 125 .5 t=RPV wall thickness 6.125

= 16171 (pr/t)/CRPV = 1 .273 >1 .15 (5) [p(r2 +r 2 )/(r 2- ri2)l/CNOZZLE< 1 .15 p=RPV Normal Operating Pressure 1005 ro=nozzle outer radius 26.5 ri=nozzle inner radius 13.1375 CNr177tF 1977

[p(r2 +r,2 )/(r 2-rI )YCNOZZLE = 0.840 <1 .15