L-PI-07-037, 10 CFR 50.55a Request 1-RR-4-6 for the Prairie Island, Unit 1, Fourth Ten-year Interval Inservice Inspection Program

10 CFR 50.55a Request 1-RR-4-6 for the Prairie Island, Unit 1, Fourth Ten-year Interval Inservice Inspection Program

ML071370392
Person / Time
Site:	Prairie Island
Issue date:	05/11/2007
From:	Wadley M Nuclear Management Co
To:	Document Control Desk, NRC/NRR/ADRO
References
L-PI-07-037, TAC MC5644, TAC MC5645
Download: ML071370392 (16)

Text

Prairie lsland Nuclear Generating Plant Committed to Nuclear Excellence Operated by Nuclear Management Company, LLC May 11,2007 L-P1-07-037 10 CFR 50.55a U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie lsland Nuclear Generating Plant Unit 1 Docket 50-282 License No. DPR-42 10 CFR 50.55a Request 1-RR-4-6 for the Prairie lsland Nuclear Generatincr Plant Unit 1 Fourth Ten-year Interval lnservice lnspection Proqram

Reference:

1. Letter from NRR to NMC, "Prairie lsland Nuclear Generating Plant, Units 1 and 2 - Issuance of Relief Request for the Risk-Informed lnservice lnspection Program (TAC NOS. MC5644 and MC5645)," ML053270079, dated January 5,2006.

Pursuant to 10 CFR 50.55a(g)(5)(iii), Nuclear Management Company, LLC (NMC) requests Nuclear Regulatory Commission (NRC) approval of the enclosed request for the Fourth Ten-Year lnservice lnspection (ISI) Interval. As an alternate to existing American Society of Mechanical Engineers (ASME)Section XI requirements for piping weld selection and examination volumes, NMC has implemented the alternative methods specified in Code Case N-578 and EPRl TR-112657B-A for Risk-Informed IS1 plans. Prairie lsland Nuclear Generating Plant (PINGP) implemented this alternative through 10 CFR 50.55a request number 1-RR-4-5, which was authorized by the NRC on January 5, 2006 (reference 1). Full examination coverage could not be obtained during a piping weld examination completed during the 2006 Unit 1 refueling outage.

The exam was limited based on piping design and limited accessibility. Relief for this examination is requested on the basis that compliance with the Code requirement is impractical. The details of the request, including the proposed alternative, are contained in enclosure 1.

1717 Wakonade Drive East a Welch, Minnesota 55089-9642 Telephone: 651.388.1 121

Document Control Desk Page 2 Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.

Michael D. Wadley I Site Vice president, Prairie lsland Nuclear Generating Plant Nuclear Management Company, LLC Enclosures (4) cc: Administrator, Region Ill, USNRC Project Manager, Prairie Island, USNRC Resident Inspector, Prairie Island, USNRC Chief Boiler Inspector, State of Minnesota

Enclosure I Prairie Island Nuclear Generating Plant Unit 1, 4th Interval IS1 10 CFR 50.55a Request No. I-RR-4-6, Rev. 0 Relief Request in Accordance with 10 CFR 50.55a(g)(5)(iii)

--Inservice Inspection Impracticality--

1 ASME Code Component Affected Code Class: Class 1 Examination Category: R-A ltem Number: R1.16-5

==

Description:==

Elements Subject to lntergranular Stress Corrosion Cracking, Risk Category 5 Component Numbers: Summary Number 300655-Rl, Weld W-17, Reducer to Valve Weld

2. Applicable Code Edition and Addenda The applicable Code Edition and Addenda for the Prairie Island Unit 1 Fourth Ten-Year lnspection Interval is the 1998 Edition with 2000 Addenda.

3. Applicable Code Requirement ASME Section XI (1998 Edition, 2000 addenda) Code requires full examination coverage of inservice inspection (ISI) components per Table IWB-2500-1. As an alternative to existing ASME Section XI requirements for piping weld selection and examination volumes, Prairie Island Nuclear Generating Plant (PINGP) has implemented the alternative methods as specified in Code Case N-578 and EPRl TR-112657B-A. Relief Request (RR) number 1-RR-4-5 "Risk Informed Examination of Class 1 and 2 Piping Welds (Code Case N-578 and EPRl TR-1 12657),11Revision 0, was submitted to the NRC on December 29, 2004 (reference 8.1) and supplemented by letter dated August 30, 2005 (reference 82) in a response to additional information. The NRC approved the use of 1-RR-4-5 on January 5, 2006 (reference 8.3).

From Code Case N-578, Table 1, "Examination Category R-A, Risk-Informed Piping Examinations," ltem Number R1.16, "Elements Subject to lntergranular Stress Corrosion Cracking (IGSCC)" piping welds with risk category 5, medium are subject to be examined by volumetric examination method of essentially 100 percent of the examination volume identified in Figure IWB-2500-8(c). Per the Risk-Informed IS1 (RI-ISI) Program, this volume must be extended to %-inch beyond each side of the base material thickness transition or the counter bore. In addition, ultrasonic examinations for welds in piping must be performed using procedures, personnel, and equipment qualified to the requirements of Appendix Vlll of the ASME Code,Section XI, Page 1 of 4

Enclosure 1 Prairie Island Nuclear Generating Plant Unit I , 4th Interval IS1 10 CFR 50.55a Request No. I-RR-4-6, Rev. 0 1995 Edition with the 1996 Addenda, "Performance Demonstration for Ultrasonic Examinations Systems."

4. Impracticality of Compliance Relief is requested on the basis that compliance with the Code requirement is impractical due to limited accessibility for the exam due to piping design. The PlNGP construction permit was issued in 1968. The facility was designed and constructed with limited accessibility due to component configurations and/or physical barriers for which 100 percent examination coverage is not achievable on some IS1 components examined for the Fourth Ten-Year Interval.

The reducer to valve weld (W-17) is located in the safety injection system piping (see enclosure 2). The reducer and valve material are austenitic stainless steel. The reducer to valve weld (W-I 7) was subject to volumetric examination using personnel and procedures qualified in accordance with Appendix VIII, Supplement 2, during the 2006 Unit 1 refueling outage. The examination was conducted using 45 degree shear and 60 degree longitudinal transducers. The examination was limited to 50 percent in both the axial and circumferential directions from the reducer side of the weld due to the weld joint configuration connection to the valve. The credited volumetric examination of the Weld Required Volume (WRV) was limited to 50 percent and only a single-sided examination could be performed. It should be noted that the volumetric examination was performed through 92.8 percent of the Code WRV; however, the Performance Demonstration Initiative (PDI) Appendix Vlll procedure used is not qualified for the detection of flaws on the far side of single sided access examinations on austenitic stainless steel piping welds. The techniques employed for the examination provide for a best effort examination. The following supporting documentation has been provided: , IS1 Drawing ISI-24 , Examination Report Number 2006U047 , Examination Report Number 2006U055 Additionally, NMC looked at the remaining welds within this segment and risk group and determined no other welds would produce greater code coverage than that obtained on the weld examination performed on weld W-17. Due to the limited amount of welds within this segment and risk group, no other selection was possible.

5. Burden Caused by Compliance To comply with the code-required examination of the weld, the component would have to be redesigned.

Page 2 of 4

Enclosure I Prairie Island Nuclear Generating Plant Unit 1,4th Interval IS1 10 CFR 50.55a Request No. 1-RR-4-6, Rev. 0

6. Proposed Alternative and Basis for Use As an alternative to the code-required examination, NMC requests relief for a limited scan of 50 percent in lieu of the essentially 100 percent volumetric requirement for the reducer to valve weld (W-17). The exam was performed during the 2006 Unit 1 refueling outage and was described in Section 4 of this request. Additionally, the weld is included in the boundary examined by visual examination VT-2 during pressure testing. Pressure testing was completed June 2, 2006, with no evidence of leakage identified in the vicinity of the weld. The performance of the single-sided ultrasonic examination, in addition to the performance of the visual VT-2 examination, provides the best examination coverage possible within the limitations of the current design configuration.

In-service inspections at Prairie Island Unit 1 are completed to the greatest extent practical. When limitations to required inspections are encountered, procedure SWI NDE-LTS-1, "Limitations to NDE," is applied. The procedure requires a review of the procedures to obtain maximum coverage and documentation of the limitation. The procedure also examines whether an alternative method could be used to obtain better coverage as allowed by the Code. This procedure was used and the maximum inspection coverage was achieved. The limitation was noted on the IS1 examination reports and was included in the 2006 IS1 Outage Summary Report. In accordance with 10 CFR 50.55a(g)(5)(iv), NMC will continue to document these types of limitations.

Additionally, the previousSection XI (SXI) program did not select any of these risk category 5 reactor coolant system welds for inspection. The RI-IS1 program selected one of these category 5 welds for inspection. Therefore, there was a small decrease in risk by implementing the RI-IS1 inspection. If PlNGP were not to take credit for this exam, there would be no change in risk between the previous SXI and the current RI-IS1 programs for this risk category in the reactor coolant system and a zero impact on the change in risk from the SXI program.

Using the provisions described above as an alternative to the code requirement will continue to provide reasonable assurance of the structural integrity of this weld.

Therefore, pursuant to 10 CFR 50.55a(g)(5)(iii), NMC requests relief from the ASME Section XI examination requirements for performing a volumetric examination of this reducer to valve weld.

7. Duration of Proposed Alternative NMC requests approval of this proposed alternative for the duration of the PlNGP Unit 1 Fourth Ten-Year. Interval.

Page 3 of 4

Enclosure I Prairie Island Nuclear Generating Plant Unit 1,4th Interval IS1 10 CFR 50.55a Request No. I-RR-4-6, Rev. 0

8. References 8.1 Letter from NMC to NRC Document Control Desk, "Relief Request to Implement Risk-Informed lnservice lnspection (ISI) Scheduling for the Fourth 10-Year lnspection interval for Prairie Islands Units 1 and 2," dated December 29,2004 (ML043650201).

8.2 Letter from NMC to NRC Document Control Desk, "Response to Request for Additional Information Regarding the "Relief Request to Implement Risk-Informed lnservice lnspection (ISI) Scheduling for the Fourth 10-Year lnspection Interval for Prairie Island Units 1 and 2," dated August 30, 2005 (ML052430399).

8.3 Letter from NRR to NMC, "Prairie Island Nuclear Generating Plant, Units 1 and 2 - Issuance of Relief Request for the Risk-Informed lnservice lnspection Program (TAC NOS. MC5644 and MC5645)," dated January 5,2006 (ML053270079).

Page 4 of 4

Enclosure 2 Prairie Island Nuclear Generating Plant Unit 1, 4th Interval 10 CFR 50.55a Relief Request No. I-RR-4-6, Rev. 0 IS1 Drawing ISI-24

6 " & 2" S I S H I G H HEAD LOOP ' 8 '

Enclosure 3 Prairie Island Nuclear Generating Plant Unit 1, 4th Interval 10 CFR 50.55a Relief Request No. 1-RR-4-6, Rev. 0 Examination Report Number 2006U047

Procedure: SWI NDE-UT-16A Outage No.: PI1RF02006 Summary No.: 300655-Rl Procedure Rev.: 2 Report No.: '2006U047 Worksco pe: IS1 Work Order No.: 98273 -

Paae:

- of -

1 4 Code: 1998 Edition, 2000 Addenda Cat.1ltem: R-AIR1.I 6-5 Location: Containment

- - ..- - ......- ..-

Drawing No.: ISI-24

Description:

REDUCER VALVE -

System ID: RC Component ID: W-17 SizelLength: 1.0" 121.0" ThicknesslDiameter: .612" 16" Limitations: See attached limitation record Start Time: 1600 Finish Time: 1610 Serial No.:

Manufacturer:

Instrument Settings

-

040229207 Panametrics Serial No.:

Manufacturer:

Search Unit OIDHHB KBA 1,

P-~

Checks

, ! Time 454 I

I Date 51712006 1

II I

Calibration

. . a - . . . .

Signal

-

u r a l urlenrarea searcn unit I

....

l~ound Path I

~- Reflector Amplitude % Division 1 1

~ ~

Model: Eaoch 4 Size: 0.375"IRound Shaoe: Round Inter. Cal. 1600 5/7/2006 1.Ow Notch 85% 8.0 1.4OW Delay:

M'tl CalNel:

0.000

.I219

---

Range:

Pulser:

- .

1.751" SquarelMax Freq.:

Exam Angle:

1.5 MHz 45" Style: Comp G

1. of Elements:

1 1

Inter. Cal.

NIA

-

-

Damping: 400 R Reject: 0% Mode: Shear 11-IIIOIUCII.~ 1 1 . ~ 1 i I I I

Rep. Rate: Auto Freq.: 2.00 Measured Angle: 45" Couplant I I I Filter: .8-3.0 Mode: Fullwave Wedge Style: MSWQC Cal. Batch: #02243 Circumferential Orientated Search Unit 1

Voltage:

Ax. Gain (dB):

NIA 5.0 Circ. Gain (dB): 5.0 Search Unit Cable Type:

-

Mfa.:

Sonotrace 40 Sonotech Inc. 1 Calibration Signal I Amplitude % I Sweep Division IsoUnd Path

- lo Screen Div. = - 1-751 in. of Sound Path Type: RG-174 Exam Batch: #02243 NIA Linearity Report No.: 2006LN004 Length: 6' No. Conn.: 0 Type: - Sonotrace 40 - - - -

Scan Coverage - Mfa.: - - ..- - - - .. .Inc.

Sonotech ..-. k C.CIIIUI~LIUII DIOLK

+03b-C6 u

1 I I Cal. Block No.: 7536 Upstream rn Downstream&+Scan -

dB: 29.0 Reference

~- -. Block ReferencelSimulator Block 29.0

~

Thickness: 0.5 t o 2.0" Dia.: Flat cw CCW IiJ Scan dB: Serial No.: iin I I sweep LMT-032 Reflector ! ~ m p l i u d2, % D~vision Sound Path Cal. Blk. Temp.: 75 Temp. Tool: 4304 Exam Surface: OD -..me: -- ------ - P B Comp. Temp.:

- 82 Temp. Tool: 4304 Surface Condition: Ground Flush ss KUMPAS

- 1.02" Recordable Indication(s): Yes No (If Yes, Ref. Attached Ultrasonic Indication Report.)

-

-

Results: NAD IND GEO Comments: Single side exam-Best effort exam on far side weld volume. 50% coverage obtained. Reference Rpt#

Percent Of Coverage Obtained > 90%: 50% Reviewed Previous Data: NIA 2006U55 for 60" exam data.

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/

Examiner I Blechinger, Todd P.

Level 111 FP? A

/1 f.6 hv' n/$/vK-

5(

/I,/ ~ ~ 51712006 ~Date~Tirnm, Reviewer Jeremy 5-z r - 4 ~

Date J / 1- I I Examiner Level NIA Signature /I Date Site Review / ~

,/ginau trd . , ,*= Date I v I Wren, Jerry P.

o~l~~~

~Ak-bw 1

NIA Other Level N/A Signature Date I

/ AN11 Review L .

1 L

-

x I

S i mt ~ e S-LQ -& I Date I NIA Daly, Gerald HAY 2 9 2006 1

Supplemental Report Report No.: 200611047 Page:

- 2 of

- 4 Summary No.: 300655-Rl Examiner: Blechinger, Todd P. Level: Ill Reviewer: Timm, Jeremy Date: r.=y-06 Examiner: NIA Level: NIA Site Review: Wren, Jerry P. / Date: Sr- LC - 6 6 Other: NIA Level: NIA ANII Review: Daly, Gerald Date: ff AH 2 9 33%

I I Comments: W-17 profile and coverage plot taken @ 0" Sketch or photo: J:\ISIData\lSI\PII-06 1R24 outage\Exam Supporting Documentation - Scans-Pics-etc\2006U047-055 300655-Rl Suppl .bmp Additional - Supplemental Reports <edit from Setup>

Determination of Percent Coverage for UT Examinations Pipe -

Sitelunit: PI I PI1 Procedure: SWI NDE-UT-16A Outage No.: PI1RF02006 Summary No.: 300655Rl Procedure Rev.: 2 R e ~ o rNo.:

t 200611047 Workscope: IS1 Work Order No.: 98273 Page: 3 of 4 45 deg Scan I 100.000  % Length X 100.000 %volume of length I100 = 100.000  % total for Scan 1 Scan 2 0.000  % Length X 0.000  % volume of length I100 = 0.000  % total for Scan 2 Scan 3 100.000  % Length X 50.000  % volume of length I 100 = 50.000  % total for Scan 3 Scan 4 100.000  % Length X 50.000  % volume of length I100 = 50.000  % total for Scan 4 Add totals and divide by # scans = 50.000  % total for 45 deg Other deq - (to be used for supplemental scans)

The data to be listed below is for coverage that was not obtained with the 45 deg scans.

Scan 1  % Length X  % volume of length 1 100 =  % total for Scan 1 Scan 2  % Length X  % volume of length 1 100 =  % total for Scan 2 Scan 3  % Length X  % volume of length 1 100 =  % total for Scan 3 Scan 4  % Length X  % volume of length I100 =  % total for Scan 4 Percent complete coveracle Add totals for each scan required and divide by # of scans to determine; 50.000  % Total for complete exam Site Field Supervisor: ate: sm/&s-od

-

Additional Calculation Pipe <edit from Setup>

LirnitaQSonRecord Site!UnifV Pit i PI1 Procedum: SWl MDBUT-il&A Outage No.: -

PI1 RF02OB6 Summary No.: 300855R1 Procedure Rev : 2 Report No,: 2QOSUO4t Workscope:

--

IS8 Work Ordos No,: 98273 Pags,

- 4 of

- .4 Bescrlpfmn of 1. imitatrora:

-

No scans an vafve due to conflguratlttn, SOalgle $Ode exam Exam pstSormed through 92,8X OF code vrsfslnre, however, pracedure not qualified for detection on far side. Best effort exam on far side volume.

Limitations ram~walrequ~remenb" None RadiationfidQ: 150 mR f hr Examiner Level 111 Examiner Level ~jg,,

Nlr4 Other N/A Signatti%

MbA

-

Addrffanal L~mr!i.trranzeci~tfrum Setup>

Enclosure 4 Prairie Island Nuclear Generating Plant Unit 1, 4th Interval 10 CFR 50.55a Relief Request No. 1-RR-4-6, Rev. 0 Examination Report Number 2006U055

UT CalibrationlExamination Sitelunit: PI I PI1 Procedure: SWI NDE-UT-16A Outage NO.: PIlRF02006 Summary No.: 300655-Rl Procedure Rev.: 2 Report No.: 2006U055 Workscope: IS1 Work Order No.: 98273 Page:

- 1 of

- 2 Code: 1998 Edition, 2000 Addenda Cat.lltem: R-AIR1.16-5 Location: Containment Drawing No.: ISI-24 -

-

Description:

REDUCER VALVE System ID: RC Component ID: W-17 SizelLength: 1.0" 121.0" ThicknesslDiameter: .612" 16" Limitations: See attached limitation record Start Time: 1611 Finish Time: 1617 Instrument Settings Search Unit I Axial Orientated Search Unit I Serial No.:

Manufacturer:

00XK65 Krautkramer Serial No.:

Manufacturer:

J1043 Megasonics Calibration Reflector I Signal Amplitude  %

I I

Sweep I ~ o u n d Division I Path Model: USN 52L Size: .25"~.50"IRect Shape: Rectangle 1.0" Notch I 80% I 8.0 1 2.31" Delay: 0.000 Range: .750" Freq.: 2.25 MHz Style: CGD M'tl CalNel:

Damping:

.2289 1000 C l Pulser:

Reject:

Single 0%

Exam Angle:

Mode:

60" # of Elements:

Ref. Long.

- 2 Rep. Rate: High Freq.: 2-8 MHz Measured Angle: 60" Couplant

--

Filter:

Voltage:

NIA NIA Mode: Full Wave Wedge Style: Integral Cal. Batch:

Type:

- #02243 Sonotrace 40 Circumferential Oriontated Search Unit Ax. Gain (dB): 62.0 Circ. Gain (dB): NIA Search Unit Cable Mfg.: Sonotec h Inc.

-10 Screen Div. = 2.841 - in. of Sound Path Type: RG-174 Exam Batch: #02243 NIA Linearity Report No.: 2006LN003 Length: 6' No. Conn.: 0 Type: Sonotrace 40 Scan Coverage Mfg.: Sonotech Inc.

Calibration Block

-

- -

Cal. Block No.: 7536 Upstream Downstream Scan dB: 68.0 Reference Block ReferencelSimulator Block Thickness: 0.5 t o 2.0" Dia.: 0 CW CCWO Scan d ~- :NIA Signal Sweep Serial NO.: LMT-032 Reflector Amplitude % Division Sound Path Cal. Blk. Temp.:

- 75 Temp. Tool: 4304 Exam Surface: OD Type: SS ROMPAS 50.0 I .7" SDH I 65% 1 5.5 1 1.59" Surface Condition: Ground Flush Como. Tem~.: - 82 Terno. Tool: 4304 I I I I Recordable Indication(s): Yes No p J (If Yes, Ref. Attached Ultrasonic Indication Report.)

Results: IND GEO Comments: Reference report #2006U047 for 45O exam.

60" exam performed t o interrogate far side volume.

Percent Of Coverage Obtained > 90%: 0% ReviewedBeyious Data: NIA

Supplemental Report Report No.: 200611055 Page:

- -2 of 2 Summary No.: 300655-Rl Examiner: Blechinger, Todd P. Level: Ill Reviewer: Timm, Jeremy Date: g - ~ sc- ~

--

- --

/

Examiner: NIA Level: NIA Site Review: Wren, Jerry P.  % Date: S- 2& - B &

Other: NIA Level: NIA ANII Review: Daly, Gerald tmo Date:my 7 9 Comments: W-17 profile and coverage plot taken @ 0" Sketch or photo: J:\ISIDala\lSI\PIl-06 1R24 outage\Exam Supporting Documentation - Scans-Pics-etc\2006U047-055 300655-Rl Suppl .bmp