TMI-11-017, Submittal of Relief Request RR-11-01 and RR-11-02

Submittal of Relief Request RR-11-01 and RR-11-02

ML110410126
Person / Time
Site:	Three Mile Island
Issue date:	02/10/2011
From:	David Helker Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TMI-11-017
Download: ML110410126 (20)

Text

Exelon Nuclear www.exeloncorp.com 200 Exelon Way Nuclear Kennett Square, PA 19348 10 CFR 50.55a TMI-11-017 February 10, 2011 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 NRC Docket No. 50-289

Subject:

Submittal of Relief Request RR-11-01 and RR-11-02 Attached for your review are two (2) relief requests associated with the third Inservice Inspection (lSI) interval for Three Mile Island Nuclear Station (TMI), Unit 1. RR-11-01 concerns requirements for examination of steam generator welds that were replaced in the 2009 Refueling Outage (T1 R18). RR-11-02 concerns four (4) High Pressure Injection circumferential valve to safe-end welds installed in the 2009 Refueling Outage (T1 R18). The TMI, Unit 1 third lSI interval complies with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 1995 Edition, 1996 Addenda. We request your approval by February 10, 2012.

There are no regulatory commitments in this letter.

If you have any questions concerning this letter, please contact Tom Loomis at (610) 765-5510.

Respectfully, David P. Helker Manager - Licensing & Regulatory Affairs Exelon Generation Company, LLC Attachments: 1) Relief Request RR-11-01

2) Relief Request RR-11-02 cc: Regional Administrator, Region I, USNRC USNRC Senior Resident Inspector, TMI USNRC Project Manager, [TMI] USNRC

ATTACHMENT Relief Request RR-11-01

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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1. ASME Code Component's) Affected Code Class: 1 and 2

Reference:

IWB-2500, Table IWB-2500-1 IWC-2500, Table IWC-2500-1 Examination Category: B-D, C-B Item Number: B3.130, C2.21

Description:

Limited Examination Coverage Component Number: See Table 1

2. Applicable Code Edition and Addenda

The third Inservice Inspection (lSI) interval is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 1995 Edition, 1996 Addenda.

3. Applicable Code Requirements This relief request addresses the previous limited examination of seven (7) steam generator nozzle welds at the Three Mile Island Nuclear Station (TMI), Unit 1 (see Table 1).

These welds were replaced as part of the installation of the Enhanced Once Through Steam Generators (EOTSGs) during the 2009 Refueling Outage (T1 R18). The following are the ASME Code,Section XI, requirements for inspection of the steam generator nozzle welds:

Table IWB-2500-1, Examination Category B-D requires volumetric examination of Item B3.130 (steam generator nozzle-to-vessel welds).

Table IWC-2500-1, Examination Category C-B requires volumetric examination of Item C2.21 (vessel nozzle-to-shell welds).

Figure IWB-2500-7(a) depicts the required examination volume (A-B-C-D-E-F-G-H-I),

which includes the weld and adjacent base metal on either side of the weld extending to a distance of one-half the thickness of the wall from the extremities of the weld.

Figure IWC-2500-4(b) depicts the required examination volume (C-D-E-F), which includes the weld and adjacent base metal on either side of the weld extending to a distance of %" from the extremities of the weld.

ASME Section XI, Mandatory Appendix I, requires ultrasonic examination of vessel welds greater than 2" thick to be conducted in accordance with ASME Section V, Article 4 as supplemented by Table 1-2000-1.

ASME Section V, Article 4 requires:

T-441.1.3 Extent of Scanning: Wherever feasible, the scanning of the examination volume shall be carried out from both sides of the weld on the same surface. Where

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

(Page 2 of 9) configuration or adjacent parts of the component are such that scanning from both sides is not feasible, this fact shall be included in the report of the examination.

T-441.1.4 Angle Beam Scanning: Wherever feasible, each examination shall be performed in two directions, i.e., approaching the weld from the opposite directions and parallel to the weld from opposite directions.

T-441.1.5 Scanning for Reflectors Oriented Parallel to the Weld: The angle beam search units shall be aimed at right angles to the weld axis, with the search unit manipulated so that the ultrasonic beams pass through the entire volume of weld metal. The adjacent base metal in the examination volume must be completely scanned by two angle beams, but need not be completely scanned by both angle beams from both directions (any combination of two angle beams will satisfy the requirement).

T-441.1.6 Scanning for Reflectors Oriented Transverse to the Weld: The angle beam search units shall be aimed parallel to the axis of the longitudinal and circumferential welds. The search unit shall be manipulated so that the ultrasonic beams pass through all of the examination volume. Scanning shall be done in two directions 180 degrees to each other to the extent possible. Areas blocked by geometric conditions shall be examined from at least one direction.

TMI, Unit 1 has invoked ASME Section XI Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1." Code Case N-460 states, in part, that when the entire examination volume or area cannot be examined a reduction in examination coverage may be accepted provided the reduction in coverage for that weld is less than 10% . NRC Information Notice 98-42, "Implementation of 10 CFR 50.55a(g) Inservice Inspection Requirements," termed the reduction in coverage of less than 10% to be "essentially 100 percent." Information Notice 98-42 states, in part, that the NRC has adopted and further refined the definition of "essentially 100 percent" to mean "greater than 90 percent," which has been applied to examination of welds or other areas required by ASME Section XI.

4. Impracticality of Compliance Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested on the basis that conformance with the specified Code requirement has been determined to be impractical.

Seven (7) steam generator nozzle welds were examined during the first and second period of the third lSI interval in accordance with ASME Section V, Article 4 requirements. The volumetric examination coverage for these nozzle welds was less than the required 90%

(see Table 1). However, the steam generators were replaced during the third period 2009 Refueling Outage (T1 R18) thereby removing and replacing these seven (7) nozzle welds.

In order to satisfy literal compliance with 10 CFR 50.55a and ASME code requirements, it was determined that a relief request should be submitted for these limited nozzle weld examinations which are no longer in the plant.

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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5. Burden Caused by Compliance The seven (7) steam generator nozzle welds were credited for volumetric examination during the first and second period of the third lSI interval even though the overall volumetric examination coverage was less than 90% (see Table 1). The steam generators were replaced, during the third period 2009 Refueling Outage (T1 R18), with newly designed steam generators and the original limited examination welds are no longer in service.

The welds listed in Table 1 were examined to the extent practical at the time of the examinations. Examination coverages are included in Table 1. The welds were subsequently replaced when the steam generators were replaced during the 2009 Refueling Outage (T1 R18). ASME Section XI examinations and tests of the new steam generators were completed prior to the plant returning to service. The new steam generators either eliminated the nozzle welds, or utilized a design that allows ASME Code examination coverage.

6. Proposed Alternative and Basis for Use No alternate provisions were practical for examination of the subject components. The examinations were performed to the maximum extent practical using the best available technology of the time. The new steam generators either eliminated the nozzle welds, or used a design that allows ASME Code examination coverage. The welds requiring pre-service examinations received the required examinations and achieve the coverage required by the ASME Code and no further actions are required.

7. Duration of Proposed Alternative Relief is requested for the third ten-year lSI interval for TMI, Unit 1. The third ten-year interval began on April 20, 2001 and is scheduled to end on April 19, 2012 for these examinations.

8. Precedents None

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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Table 1 Steam Generator Nozzle Welds Weld ID I Category Outage & Coverage Fabrication Section NDE Limitation Indications Description litem No. Date Attained Materials XI Exam Method Description Identified Figure I Angles RCH0001 ASG0002N I B-D I T1 R16, Fall 43.3% Ferritic Steel IWB- UT 10, Obstruction due to None Nozzle to Head Weld B3.130 2005 2500-7(a) 35,45, nozzle configuration (See Figure 2 and 5) 60 RCH0001 ASGOO03NI B-D I T1 R15, Fall 69.5% IWB- UT 10, Obstruction due to Nozzle to Head Weld B3.130 2003 Ferritic Steel 2500-7(a) 45,60 support skirt and None (See Figure 1 and 4) nozzle configuration RCH0001 ASG0004N I B-D I T1R15, Fall 69.5% IWB- UT 10, Obstruction due to Nozzle to Head Weld B3.130 2003 Ferritic Steel 2500-7(a) 45,60 support skirt and None (See Figure 1 and 4) nozzle configuration RCH0001 BSG0008N I B-D I T1 R16, Fall 47.1% IWB- UT 10, Obstruction due to Nozzle to Head Weld B3.130 2005 Ferritic Steel 2500-7(a) 35,45, support skirt and None (See Figure 1 and 4) 60 nozzle configuration RCH0001 BSG0009N I B-D I T1 R16, Fall 47.1% IWB- UT 10, Obstruction due to Nozzle to Head Weld B3.130 2005 Ferritic Steel 2500-7(a) 35,45, support skirt and None (See Figure 1 and 4) 60 nozzle configuration RCH0001 BSG001 ON I B-D I T1R16, Fall 43.3% IWB- UT 10, Obstruction due to Nozzle to Head Weld 83.130 2005 Ferritic Steel 2500-7(a) 35,45, nozzle configuration None (See Figure 2 and 5) 60 RCH0001 BSG0030N I C-B I C2.21 T1 R16, Fall 68.0% Ferritic Steel IWC- UT 10, Obstruction due to Nozzle to Shell Weld 2005 2500-4(b) 45, 60 nozzle configuration None (See Figure 3) and insulation support hardware

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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Figure 1 NDE Data Report Coverage Plot for Welds RCH0001 ASG0003N and RCH0001 ASG0004N.

Note that welds RCH0001 BSG0008N and RCH0001 BSG0009N are identical in design.

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

(Page 6 of 9)

Figure 2 NDE Data Report Coverage Plot for Welds RCH0001 ASG0002N and RCH0001 BSG001 ON

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

(Page 7 of 9)

Figure 3 Typical Main Steam Outlet Nozzle on TM I Steam Generator (representative of weld RCH0001 BSG0030N).

Photo of Actual TMI Steam Generator During 2009 Outage Removal Location is at Main Steam Outlet Nozzles

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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Figure 4 Examination limited due to nozzle design and proximity of head to support skirt attachment.

Typical RCS Outlet Nozzles on TM I Steam Generator (representative of welds RCH0001 ASG0003N RCH0001 ASG0004N RCH0001 BSG0008N RCH0001 BSG0009N)

Photo of Actual TMI Steam Generator During 2009 Outage Removal Location is at Lower Head Region

Relief Request RR-11-01 for Steam Generator Welds Replaced in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a{g){5){iii)

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Figure 5 Typical RCS Inlet Nozzle (representative of welds RCH0001 ASG0002N and RCH0001 BSG001 ON)

Photo of Actual TMI Steam Generator During 2009 Outage Removal Location is at Upper Head Region

ATTACHMENT Relief Request RR-11-02

Relief Request RR-11-02 for High Pressure Injection Valve to Safe-End Welds Installed in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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1. ASME Code Component(s) Affected Code Class: 1

References:

Code Case N-578-1, Table 1 EPRI TR-112657, Rev. B-A, Table 4-1 Examination Category: R-A Item Number: R1.11

Description:

Limited Examination Coverage Component Number: See Table 2

2. Applicable Code Edition and Addenda

The third interval Inservice Inspection (lSI) program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 1995 Edition, 1996 Addenda.

3. Applicable Code Requirement

Four (4) High Pressure Injection circumferential valve to safe-end welds were installed during the 2009 Refueling Outage (T1 R18) at Three Mile Island Nuclear Station (TMI), Unit 1 (see Table 2). The following are the ASME Code,Section XI, requirements for the inspection of valve to safe-end welds:

IWA-4530(a) requires that "when portions of items requiring preservice or inservice inspection are affected by repair/replacement activities, or for items being installed, including welded joints made for installation of items, preservice inspections shall be performed in accordance with IWB-2200, IWC-2200, IWD-2200, IWE-2200, IWF-2200, or IWL-2200 prior to return of the system to service. The preservice inspection may be performed either prior to or follOWing the pressure test required by IWA-4540."

Figure 4-1 of EPRI TR-112657, Revision B-A ("Revised Risk-Informed Inservice Inspection Evaluation Procedure, December 1999) provides the required coverage II locations for these welds. Figure 4-1 of EPRI TR-112657, Revision B-A depicts the required examination volume (A-B-C-D), which includes the lower 1/3 thickness of the circumferential weld and 1/2" on each side of the weld toes used to define the required examination volume.

As required by 10 CFR 50.55a, ASME Section XI 1995 Edition, 1996 Addenda, Appendix VIII, "Performance Demonstration for Ultrasonic Examination System," is required for examination procedures, equipment, and personnel.

TMI, Unit 1 has invoked ASME Section XI, Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1." Code Case N-460 states, in part, that when the entire examination volume or area cannot be examined, a reduction in examination coverage may be accepted provided the reduction in coverage for that weld is less than 10%

• NRC Information Notice 98-42,

Relief Request RR-11-02 for High Pressure Injection Valve to Safe-End Welds Installed in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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"Implementation of 10 CFR 50,55a(g) Inservice Inspection Requirement," termed the reduction in coverage of less than 10% to be "essentially 100 percent." Information Notice 98-42 states, in part, that the NRC has adopted and further refined the definition of "essentially 100 percent" to mean "greater than 90 percent," which has been applied to examination of welds or other areas required by ASME Section XI.

4. Impracticality of Compliance Pursuant to 10 CFR 50.55a(g)(5)(iii), relief is requested on the basis that conformance with the specified Code requirement has been determined to be impractical.

Due to the original design, cast valve material, physical obstructions, and geometric interferences associated with these welds, it is not feasible to effectively perform examinations of 100% of the volume of these welds as required for preservice examination.

Therefore, relief is requested on the basis that the Code requirements to examine essentially 100% of the welds' volume are impractical. Attaining the geometry required to achieve the Code required examination coverage would require major modifications to components (replacement of existing cast stainless steel valve with a valve of different design and material) without providing a corresponding increase in the level of quality and safety.

5. Burden Caused by Compliance Four (4) High Pressure Injection circumferential valve to safe-end welds were installed in the fall 2009 Refueling Outage (T1 R18) and pre-service examinations were required. Due to geometric limitations and fabrication materials, only 50% of each weld could be examined.

The safe-ends and associated welds were changed from Alloy 600/82/182 material to stainless steel material as a part of the Alloy 600 pre-emptive mitigation program. The original valve remained installed to the original stainless steel piping on the side of the valve that was opposite the safe-end. The valve is comprised of Cast Austenitic Stainless Steel (CASS) material. There are currently no Performance Demonstration Initiative (POI) qualified ultrasonic examination (UT) techniques for CASS materials. In addition, there are no stainless steel piping POI qualified UT examination techniques qualified for 100%

examination coverage when the weld configuration allows access from one side of the weld only. Replacement of the previously installed valve would have required additional installation welds and additional engineering analysis. A typical valve to safe-end configuration (prior to replacement) for TMI, Unit 1 is provided in Figure 5.

These austenitic stainless steel valve to safe-end welds and associated base materials are 2 1/2" Nominal Pipe Size (NPS) with a nominal wall thickness of 0.422" (based on safe-end minimum wall thickness). Pre-service UT examinations were performed on these welds in order to examine the welds with methods and techniques that were expected to be used for inservice examination should future examination be required. Under the TMI, Unit 1 risk-informed lSI program, the welds associated with this particular piping segment are classified Category R-A, Item R1.11 which are assigned thermal fatigue as an applicable

Relief Request RR-11-02 for High Pressure Injection Valve to Safe-End Welds Installed in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a{g){5){iii)

(Page 3 of 8) degradation mechanism. These pre-service examinations were performed using examination procedures and personnel qualified under the Performance Demonstration Initiative (POI) program administered through the EPRI NOE Center, specifically POI-UT-2, which is qualified to detect and length size flaws in the required examination volume of wrought austenitic piping welds. However, the POI procedure is not qualified for the detection of flaws on the far side of austenitic stainless steel piping welds when examination access is limited to one side of the weld. The valve geometry tapers away from the weld resulting in limited available scanning surface on the valve side thus limiting the code coverage to 50%. In addition, the valve body is comprised of A351-CF8M (CASS) for which there are no qualified POI UT examination techniques. Figures 1 through 4 provide plots of the credited examination volume.

The four new welds were examined in accordance with ASME Section III, Article NB-5000 requirements prior to plant heat-up. These welds received radiographic and liquid penetrant examinations prior to the applicable UT pre-service examination. The welds also received a system leakage examination per ASME Section XI prior to exiting the fall 2009 refueling outage.

6. Proposed Alternative and Basis for Use No alternate provisions are practical for the subject components. The examinations were performed to the maximum extent practical using the best available technology of the time.

The examinations are limited because there is no approved qualified method to perform the examination from one side of the weld.

The four (4) High Pressure Injection circumferential valve to safe-end welds were examined in accordance with the ASME Code,Section III, Article NB-5000 examination requirements.

These examinations (radiography and liquid penetrant) were satisfactorily completed and were acceptable to the Article NB-5000 acceptance criteria thereby confirming that the welds were acceptable for service. The preservice UT examinations provided additional assurance that the fabrication condition was acceptable and provided a baseline examination should UT examination be required on these welds in the future.

7. Duration of Proposed Alternative Relief is requested for the third ten-year lSI interval for TMI, Unit 1. The third ten-year interval began on April 20, 2001 and is scheduled to end on April 19, 2012 for these examinations.

8. Precedence There are no qualified POI procedures for the detection of flaws on the far side of single sided access examinations. Accordingly, there are numerous relief requests associated with the issue. Below are a few similar relief requests:

1) Palo Verde Nuclear Generating Station, Unit 3 second inspection interval RR-43, Part B, was approved in an NRC Safety Evaluation Report dated November 4,2009 (ML092870544). This relief request concerned limited pipe-to-valve welds due to no

Relief Request RR-11-02 for High Pressure Injection Valve to Safe-End Welds Installed in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

(Page 4 of 8) qualified POI procedures for the detection of flaws on the far side of single sided access examinations.

2) Palo Verde Nuclear Generating Station, Unit 2 second inspection interval RR-38, Part 0 and F, was approved in an NRC Safety Evaluation Report dated March 26, 2009 (ML090690154). These relief requests included limited pipe-to-valve welds due to no qualified POI procedures for the detection of flaws on the far side of single-sided access examinations.

3) Limerick Generating Station, Units 1 and 2 second inspection interval Relief Request 35 was approved in an NRC Safety Evaluation Report dated January 27,2009 (ML090060218). This relief request included limited pipe-to-valve welds due to no qualified POI procedures for the detection of flaws on the far side of single-sided access examinations.

Relief Request RR-11-02 for High Pressure Injection Valve to Safe-End Welds Installed in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a{g){5){iii)

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Table 2 Piping Weld Pre-service Limited Examinations Weld ID I Description Category Outage & Coverage Fabrication Section NDE Limitation Indications litem No. Date Attained Materials XI Exam Method Description Identified Figure I Angles MU0901 BM I Valve to R-A I R1.11 T1 R18, 50% Valve - A351- EPRI TR- UTI Valve to safe-end None Safe-End Weld Fall 2009 CF8M (CASS), 112657, 45 and weld configuration.

Safe-End - SA- Rev. B-A, 70 One sided stainless 182 Type Figure 4-1 steel exam. CASS 316/316L, Weld- stainless steel exam ER316/316L technique not qualified.

MU0903BM I Valve to R-A I R1.11 T1 R18, 50% Valve - A351- EPRI TR- UTI Valve to safe-end None Safe-End Weld Fall 2009 CF8M (CASS), 112657, 45 and weld configuration.

Safe-End - SA- Rev. B-A, 70 One sided stainless 182 Type Figure 4-1 steel exam. CASS 316/316L, Weld- stainless steel exam ER316/316L technique not qualified.

MU0907BM I Valve to R-A I R1.11 T1R18, 50% Valve - A351- EPRI TR- UTI Valve to safe-end None Safe-End Weld Fall 2009 CF8M (CASS), 112657, 45 and weld configuration.

Safe-End - SA- Rev. B-A, 70 One sided stainless 182 Type Figure 4-1 steel exam. CASS 316/316L, Weld- stainless steel exam ER316/316L technique not qualified.

MU0952BM I Valve to R-A I R1.11 T1 R18, 50% Valve - A351- EPRI TR- UTI Valve to safe-end None Safe-End Weld Fall 2009 CF8M (CASS), 112657, 45 and weld configuration.

Safe-End - SA- Rev. B-A, 70 One sided stainless 182 Type Figure 4-1 steel exam. CASS 316/316L, Weld- stainless steel exam ER316/316L technique not qualified.

Relief Request RR-11-02 for High Pressure Injection Valve to Safe-End Welds Installed in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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Figure 1 Weld MU0901 BM Coverage Plot Figure 2 Weld MU0903BM Coverage Plot

Relief Request RR-11-02 for High Pressure Injection Valve to Safe-End Welds Installed in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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Figure 3 Weld MU0907BM Coverage Plot VALVE Figure 4 Weld MU0952BM Coverage Plot VALVE

Relief Request RR-11-02 for High Pressure Injection Valve to Safe-End Welds Installed in Fall 2009 Refueling Outage in Accordance with 10 CFR 50.55a(g)(5)(iii)

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Figure 5 Typical Valve to Safe-End Configuration (Prior to Replacement)