BYRON 2007-0006, Inservice Inspection Program Second Interval Relief Requests I2R-21, I2R-22, I2R-23, I2R-25 and I2R-53

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Inservice Inspection Program Second Interval Relief Requests I2R-21, I2R-22, I2R-23, I2R-25 and I2R-53
ML070120246
Person / Time
Site: Byron  Constellation icon.png
Issue date: 01/12/2007
From: Hoots D
Exelon Generation Co, Exelon Nuclear
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
1.10.0101, BYRON 2007-0006
Download: ML070120246 (34)
v • d • e


Text

Exeln.

Exelon Generation Company, LLC www.exeloncorpcom N Byron Station 4450 North German Church Road Byron, IL 61010~-9794 10 CFR 50.55a January 12, 2007 LTR: BYRON 2007-0006 File: 1.10.0101 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. 50-454 and 50-455

Subject:

Inservice Inspection Program Second Interval Relief Requests 12R-21, 12R-22, I2R-23, 12R-25 and 12R-53 In accordance with 10 CFR 50.55a, Codes and standards, paragraph (g)(5)(iv), Exelon Generation Company, LLC (EGC), is submitting five requests for relief due to impracticality of satisfying the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components. The relief requests are associated with the second interval, which ended January 15, 2006.

The relief requests are based on limitations that precluded full code examination requirements of ASME Class 1 and 2 welds during the second interval. Code examination of the welds is limited due to materials of construction and design configurations.

Shouldyou have any questions concerning this submittal, please contact William Grundmann at 815 406-2800.

Respectfully, David M. Hoots Site Vice President Byron Nuclear Generating Station DMH\JEL\rah ~

Enclosures:

1. Byron Station Second Interval Relief Request I2R-21
2. Byron Station Second Interval Relief Request 12R-22
3. Byron Station Second Interval Relief Request I2R-23 4, Byron Station Second Interval Relief Request 12R-25
5. Byron Station Second Interval Relief Request I2R-53

Enclosure 1 Byron Station Second Interval Relief Request 12R-21

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-21 Revision 0 (Page 1 of 7)

Request for Relief for Alternative Rules for the Inservice Inspection of Inaccessible Pressurizer Seismic Restraint Integral Attachment Welds In Accordance with 10 CFR 50.55a(g)(5)(iii)

1. ASME CODE COMPONENT(S) AFFECTED:

Code Class: 1

Reference:

IWB-2500- 1 Examination Category: B-K Item Number: B10.10

Description:

Alternate Rules for the Inservice Inspection of the Pressurizer Seismic Lug Welds.

Component Numbers: 1 RY-Ol -5, PSL-1, PSL-2, PSL-3, and PSL-4 2RY-01 -S, PSL-1, PSL-2, PSL-3, and PSL-4

2. APPLICABLE CODE EDITION AND ADDENDA:

The current Inservice Inspection program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 1989 Edition with no Addenda.

3. APPLICABLE CODE REQUIREMENTS:

Subsection IWB, Table IWB-2500-1, Examination Category B-K, Item B10.10 requires surface examination of Integrally Welded Attachments to the Pressurizer, Figure IWB-2500-15.

Component category and item number designations used in this request for relief are taken from Code Case N-509 that was approved for use by Regulatory Guide 1.147.

4. IMPRACTICALITY OF COMPLIANCE:

Pursuant to 10CFR5O.55a(g)(5)(iii), conformance with these code requirements is impractical.

Relief is requested from the surface examination coverage requirements of Figure IWC-2500-1 5.

10 CFR 50.55a(g)(4) states; 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 set forth in Section XI of editions of the ASME Boiler and Pressure Vessel Code and Addenda to the extent practical within the limitations of design, geometry and materials of construction of the components. The geometry and design of the piping penetration attachment welds result in limited access to the entire examination surface. The limiting factor in the examination is the minimum access to the entire surface around each of the seismic restraining tugs.

Byron Units 1 and 2 Pressurizer seismic lugs are welded to the Pressurizer shell. There are four seismic tugs per vessel, located 90°apart (see Figure 1). These restraints are designed to resist rotational and translational movements by providing lateral support during a seismic event (Byron/Braidwood UFSAR, Section 3.9.3.4.1.2). During normal operations, the seismic tugs are under no load.

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-21 Revision 0 (Page 2 of 7)

In order to perform examinations on the seismic lug welds, the outside surface of the tower vessel shell to lug area must be accessible. The entire exam surface is not accessible since it is covered by the seismic lug restraint and tower Pressurizer shell insulation. In addition, the configuration of the Pressurizer coffin limits access to the seismic lugs. The impact of removing the seismic lug restraint, altering the Pressurizer coffin, and removing the lower shell insulation is presented below.

The seismic lug restraint (see Figure 2), which surrounds the lug, prohibits access needed to perform a meaningful surface exam. There are four restraints located at about the 428 elevation, one for each lug, which were not designed for removal. The top of the concrete floor at this location is at the 428 elevation.

Insulation on the lower shell of the Pressurizer prohibits access needed to perform a meaningful surface examination of the seismic lug weld areas. The removal of the insulation covering the lower Pressurizer shell to seismic lug area will result in high radiation dose to plant personnel.

Access from below would require scaffolding from the 401 elevation grating to the 428 elevation of the seismic restraint. To remove the Pressurizer shell insulation, access would be required from both sides. As stated above, access to the top of three of the seismic tugs restraints is limited by the Pressurizer coffin configuration (see Figure 1) and the concrete floor will limit access from the bottom of all four lugs (see Figure 2). The current configuration of the seismic restraint also only allows limited access for surface examination. To provide suitable access for all four seismic lug restraints would require major modifications and significant resources.

Even if the insulation is removed, a full surface examination of the seismic lugs cannot be achieved. The Pressurizer coffin, concrete floor, and seismic restraint geometry would greatly limit access to all sides. The resulting coverage would only be a small percentage of the necessary weld surface. The limited data obtained from these examinations do not provide a compensatory increase in quality and safety to justify the hazards of personnel radiation exposure to obtain the data.

Full removal of the insulation would only be possible with the construction of a 20 scaffold 360° around the pressurizer. The ring of insulation at the level of the top surface of the 428 elevation concrete platform and below is overlapped by and riveted to the ring below. These two insulation rings would have to be removed before limited access to the lower surface of the lugs can be achieved. This access would be limited by the narrow distance between the pressurizer and the attachment plate and the bottom of the lug and the bottom of floor at 428 elevation (see Figure 2, View B-B). The floor, which is 2-6 thick, limits access and places the lug beyond reach from below.

During the Unit 1 Bi R12 and the Unit 2 B2R12 outages, attempts were made to perform a surface examination of the seismic tugs. The extent of the coverage obtained is shown in Figure 3. The coverage achieved was limited by the restraint, floor, and the amount of insulation that could be removed.

5. BURDEN CAUSED BY COMPLIANCE:

Current examination techniques are not capable of achieving the required examination surface entirely around each seismic restraint lug. Access could only be gained by a complete redesign and modification of the embed plates, the surrounding floor, and the seismic lugs. All of the restraint plates, which are embedded in the concrete, would require major modification to the existing Pressurizer coffin to allow for removal and access. This modification would require the redesign of the seismic restraint and Pressurizer coffin to allow for periodic removal and access to

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-21 Revision 0 (Page 3 of 7) the seismic restraints. Implementation of this redesign would require significant engineering resources, construction resources, and significant dose to plant personnel. See Attachment 1 for the dose and work estimates.

To perform this modification to achieve the necessary access would be a prohibitive option. The limitation caused by the configuration is inherent in the design of the vessel lug and placement inside the containment building.

6. PROPOSED ALTERNATIVE AND BASIS FOR USE:

For the Second Inspection Interval, the following examinations were performed:

As a minimum, a surface (PT) examination of all accessible portions of the upper surface of the restraint lugs has been performed to the extent achievable. This examination was performed with the lower insulation panels in place.

This exam along with the periodic VT-2 examinations in accordance with the requirements of ASME Section XI, Table IWB-2500-1, Examination Category B-P, and applicable reactor coolant systems monitoring requirements specified in the Technical Specifications, has provided reasonable assurance of continued structural integrity of the Pressurizer shell and seismic tugs.

7. DURATION OF PROPOSED ALTERNATIVE:

Relief is requested for the Second Inspection Interval for Byron Units 1 and 2.

8. PRECEDENTS:

Braidwood; Approval of Relief Requests for 2nd 10-Year Interval, January 6, 2000 (ML003673725).

9. ATTACHMENTS:

Figure 1: Plan at Elevation 428 Figure 2: Pressurizer Seismic Restraint Details Figure 3: Surface Examination Coverage Obtained Attachment 1: Estimated Man Hours and Dose

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-21 Revision 0 (Page 4 of 7)

UNIT 1 AS SHOWN, UNIT 2 REVERSED

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-21 Revision 0 (Page 5 of 7)

Figure 2: Pressurizer Seismic Restraint Details 48 IA A~

VIEW A-A (Drawing not to scale)

Exeln.

Exelon Generation Company, LLC www.exeloncorpcom N Byron Station 4450 North German Church Road Byron, IL 61010~-9794 10 CFR 50.55a January 12, 2007 LTR: BYRON 2007-0006 File: 1.10.0101 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. 50-454 and 50-455

Subject:

Inservice Inspection Program Second Interval Relief Requests 12R-21, 12R-22, I2R-23, 12R-25 and 12R-53 In accordance with 10 CFR 50.55a, Codes and standards, paragraph (g)(5)(iv), Exelon Generation Company, LLC (EGC), is submitting five requests for relief due to impracticality of satisfying the requirements of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components. The relief requests are associated with the second interval, which ended January 15, 2006.

The relief requests are based on limitations that precluded full code examination requirements of ASME Class 1 and 2 welds during the second interval. Code examination of the welds is limited due to materials of construction and design configurations.

Shouldyou have any questions concerning this submittal, please contact William Grundmann at 815 406-2800.

Respectfully, David M. Hoots Site Vice President Byron Nuclear Generating Station DMH\JEL\rah ~

Enclosures:

1. Byron Station Second Interval Relief Request I2R-21
2. Byron Station Second Interval Relief Request 12R-22
3. Byron Station Second Interval Relief Request I2R-23 4, Byron Station Second Interval Relief Request 12R-25
5. Byron Station Second Interval Relief Request I2R-53

Enclosure 1 Byron Station Second Interval Relief Request 12R-21

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-21 Revision 0 (Page 1 of 7)

Request for Relief for Alternative Rules for the Inservice Inspection of Inaccessible Pressurizer Seismic Restraint Integral Attachment Welds In Accordance with 10 CFR 50.55a(g)(5)(iii)

1. ASME CODE COMPONENT(S) AFFECTED:

Code Class: 1

Reference:

IWB-2500- 1 Examination Category: B-K Item Number: B10.10

Description:

Alternate Rules for the Inservice Inspection of the Pressurizer Seismic Lug Welds.

Component Numbers: 1 RY-Ol -5, PSL-1, PSL-2, PSL-3, and PSL-4 2RY-01 -S, PSL-1, PSL-2, PSL-3, and PSL-4

2. APPLICABLE CODE EDITION AND ADDENDA:

The current Inservice Inspection program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 1989 Edition with no Addenda.

3. APPLICABLE CODE REQUIREMENTS:

Subsection IWB, Table IWB-2500-1, Examination Category B-K, Item B10.10 requires surface examination of Integrally Welded Attachments to the Pressurizer, Figure IWB-2500-15.

Component category and item number designations used in this request for relief are taken from Code Case N-509 that was approved for use by Regulatory Guide 1.147.

4. IMPRACTICALITY OF COMPLIANCE:

Pursuant to 10CFR5O.55a(g)(5)(iii), conformance with these code requirements is impractical.

Relief is requested from the surface examination coverage requirements of Figure IWC-2500-1 5.

10 CFR 50.55a(g)(4) states; 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 set forth in Section XI of editions of the ASME Boiler and Pressure Vessel Code and Addenda to the extent practical within the limitations of design, geometry and materials of construction of the components. The geometry and design of the piping penetration attachment welds result in limited access to the entire examination surface. The limiting factor in the examination is the minimum access to the entire surface around each of the seismic restraining tugs.

Byron Units 1 and 2 Pressurizer seismic lugs are welded to the Pressurizer shell. There are four seismic tugs per vessel, located 90°apart (see Figure 1). These restraints are designed to resist rotational and translational movements by providing lateral support during a seismic event (Byron/Braidwood UFSAR, Section 3.9.3.4.1.2). During normal operations, the seismic tugs are under no load.

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-21 Revision 0 (Page 2 of 7)

In order to perform examinations on the seismic lug welds, the outside surface of the tower vessel shell to lug area must be accessible. The entire exam surface is not accessible since it is covered by the seismic lug restraint and tower Pressurizer shell insulation. In addition, the configuration of the Pressurizer coffin limits access to the seismic lugs. The impact of removing the seismic lug restraint, altering the Pressurizer coffin, and removing the lower shell insulation is presented below.

The seismic lug restraint (see Figure 2), which surrounds the lug, prohibits access needed to perform a meaningful surface exam. There are four restraints located at about the 428 elevation, one for each lug, which were not designed for removal. The top of the concrete floor at this location is at the 428 elevation.

Insulation on the lower shell of the Pressurizer prohibits access needed to perform a meaningful surface examination of the seismic lug weld areas. The removal of the insulation covering the lower Pressurizer shell to seismic lug area will result in high radiation dose to plant personnel.

Access from below would require scaffolding from the 401 elevation grating to the 428 elevation of the seismic restraint. To remove the Pressurizer shell insulation, access would be required from both sides. As stated above, access to the top of three of the seismic tugs restraints is limited by the Pressurizer coffin configuration (see Figure 1) and the concrete floor will limit access from the bottom of all four lugs (see Figure 2). The current configuration of the seismic restraint also only allows limited access for surface examination. To provide suitable access for all four seismic lug restraints would require major modifications and significant resources.

Even if the insulation is removed, a full surface examination of the seismic lugs cannot be achieved. The Pressurizer coffin, concrete floor, and seismic restraint geometry would greatly limit access to all sides. The resulting coverage would only be a small percentage of the necessary weld surface. The limited data obtained from these examinations do not provide a compensatory increase in quality and safety to justify the hazards of personnel radiation exposure to obtain the data.

Full removal of the insulation would only be possible with the construction of a 20 scaffold 360° around the pressurizer. The ring of insulation at the level of the top surface of the 428 elevation concrete platform and below is overlapped by and riveted to the ring below. These two insulation rings would have to be removed before limited access to the lower surface of the lugs can be achieved. This access would be limited by the narrow distance between the pressurizer and the attachment plate and the bottom of the lug and the bottom of floor at 428 elevation (see Figure 2, View B-B). The floor, which is 2-6 thick, limits access and places the lug beyond reach from below.

During the Unit 1 Bi R12 and the Unit 2 B2R12 outages, attempts were made to perform a surface examination of the seismic tugs. The extent of the coverage obtained is shown in Figure 3. The coverage achieved was limited by the restraint, floor, and the amount of insulation that could be removed.

5. BURDEN CAUSED BY COMPLIANCE:

Current examination techniques are not capable of achieving the required examination surface entirely around each seismic restraint lug. Access could only be gained by a complete redesign and modification of the embed plates, the surrounding floor, and the seismic lugs. All of the restraint plates, which are embedded in the concrete, would require major modification to the existing Pressurizer coffin to allow for removal and access. This modification would require the redesign of the seismic restraint and Pressurizer coffin to allow for periodic removal and access to

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-21 Revision 0 (Page 3 of 7) the seismic restraints. Implementation of this redesign would require significant engineering resources, construction resources, and significant dose to plant personnel. See Attachment 1 for the dose and work estimates.

To perform this modification to achieve the necessary access would be a prohibitive option. The limitation caused by the configuration is inherent in the design of the vessel lug and placement inside the containment building.

6. PROPOSED ALTERNATIVE AND BASIS FOR USE:

For the Second Inspection Interval, the following examinations were performed:

As a minimum, a surface (PT) examination of all accessible portions of the upper surface of the restraint lugs has been performed to the extent achievable. This examination was performed with the lower insulation panels in place.

This exam along with the periodic VT-2 examinations in accordance with the requirements of ASME Section XI, Table IWB-2500-1, Examination Category B-P, and applicable reactor coolant systems monitoring requirements specified in the Technical Specifications, has provided reasonable assurance of continued structural integrity of the Pressurizer shell and seismic tugs.

7. DURATION OF PROPOSED ALTERNATIVE:

Relief is requested for the Second Inspection Interval for Byron Units 1 and 2.

8. PRECEDENTS:

Braidwood; Approval of Relief Requests for 2nd 10-Year Interval, January 6, 2000 (ML003673725).

9. ATTACHMENTS:

Figure 1: Plan at Elevation 428 Figure 2: Pressurizer Seismic Restraint Details Figure 3: Surface Examination Coverage Obtained Attachment 1: Estimated Man Hours and Dose

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-21 Revision 0 (Page 4 of 7)

UNIT 1 AS SHOWN, UNIT 2 REVERSED

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-21 Revision 0 (Page 5 of 7)

Figure 2: Pressurizer Seismic Restraint Details 48 IA A~

VIEW A-A (Drawing not to scale)

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-21 Revision 0 (Page 6 of 7)

Figure 3: Surface Examination Coverage Obtained 1/2 Base Metal 1/2 Weld.

6 Bi Ri 2 Examination Coverage Obtained B2R12 Examination Coverage Obtained Total Required per Lug: 28 Perimeter (112 total for 4 lugs)

(Drawing not to scale)

B1R12 B2R12 Support Luri Perimeter Length Percentage Perimeter Length Percentage

~ Examined Examined Examined Examined PSL-1 6 21 4% 7 25 0%

PSL-2 12 42 9% 0 0 0%

PSL-3 6 21 4% 12 42 9%

PSL-4 0 0.0% 12 42.9%

Total Achieved { 24 21.4% 31 27.7%

Report # L 2003-379 B2R12-PT-006

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-21 Revision 0 (Page 7 of 7)

Attachment 1: Estimated Man Hours and Dose Estimates provided by the support organizations.

Dose rates established by RP survey #96-3105 on Dose Rate 9/11/96 15 mRH TASK PERSON-HOURS Carpenters 160 Labors 120 Insulation Insulators 280 Panels Inspectors 10 TOTAL Dose Rate 570 3mRH r-~R~uiNEL DOSE TOTAL RATE DOSE 428EL Carpenters 5 mRH 800 mR Labors 3mRH 360mR Insulators 3mRH 840mR Dose Rate Inspectors 3mRH 3OmR 3mRH TOTAL 2030 mR Dose Rate 5mRH

Enclosure 2 Byron Station Second Interval Relief Request I2R-22

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-22 Revision 0 (Page 1 of 6)

Request for Relief for Alternative Rules for the Inservice Inspection of Inaccessible Welds on Welded Penetration Integral Attachments In Accordance with 10 CFR 50.55a(g)(5)(iii)

1. ASME CODE COMPONENT(S) AFFECTED:

Code Class: 2

Reference:

IWC-2500- 1 Examination Category: C-C Item Numbers: C3.20

Description:

Alternative Rules for the Inservice Inspection of Inaccessible Welds on Welded Penetration Integral Attachments Component Number(s): See Table 1 for component listings.

Component Drawings: Mechanical Drawing M-i97 Series for Containment Penetrations Mechanical Drawing M-521 Series for Auxiliary Building Penetrations

2. APPLICABLE CODE EDITION AND ADDENDA:

The current Inservice Inspection program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 1989 Edition with no Addenda.

3. APPLICABLE CODE REQUIREMENTS:

Subsection IWC, Table IWC-2500-1, Examination Category C-C, Item C3.20 requires surface examination of the Integrally Welded Attachments to Piping.

4. IMPRACTICALITY OF COMPLIANCE:

Pursuant to 10CFR5O.55a(g)(5)(iii), conformance with these code requirements is impractical.

Relief is requested from the surface examination coverage requirements of Figure IWC-2500-5(a).

10 CFR 50.55a(g)(4) states; 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 set forth in Section Xl of editions of the ASME Boiler and Pressure Vessel Code and Addenda to the extent practical within the limitations of design, geometry and materials of construction of the components. The geometry and design of the piping penetration attachment welds result in limited access to the entire examination surface.

The two limiting factors in the examination of the inner portion of the attachment welds are as follows:

a) The minimum access to the inside surface of an assembled penetration (component geometry), and b) Attachment welds or closure plate configuration (component design).

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-22 Revision 0 (Page 2 of 6)

Some penetrations at Byron were originally designed where one of the integral attachment welds is inside the penetration assembly, thus making the welds inaccessible for inservice inspection.

Access from outside of the closed end of the penetration assembly for examination is prohibited by the integral attachment. Access from the open end of the penetration is severely restrained due to the penetration geometry. See Figures 1 and 2 for penetration details. The integral attachment weld is set back some distance inside the penetration assembly and the clearance between the pipe and penetration sleeve is small. See Table 1 for these dimensions.

To satisfy the Code requirement to perform a surface examination of this weld, modification to the penetration assembly and/or piping to allow access would be required. Byron would incur significant engineering and installation costs to perform such a modification without a compensating increase in the level of quality and safety to justify such modifications.

The limited access to these welds, as described in this relief request, was later acknowledged in later editions of the ASME Code. Subarticle IWC-1200 exempts from examination welds or portions of welds that are located inside a penetration.

5. BURDEN CAUSED BY COMPLIANCE:

Current examination techniques available for field use are not capable of achieving the required examination surface on the inside of the various penetrations. To replace all the existing penetration assemblies to achieve access to the inside surface would be a prohibitive option. The limitation caused by the configuration is inherent in the design of piping penetrations.

6. PROPOSED ALTERNATIVE AND BASIS FOR USE:

When a weld was scheduled for inspection, a surface examination of the accessible weld on the exposed outside surface of the penetration was performed. In conjunction with the surface examination, the periodic VT-2 examinations in accordance with the requirements of ASME Section Xl, Table IWC-2500-1, Examination Category C-H will provide reasonable assurance of continued structural integrity of the piping systems.

7. DURATION OF PROPOSED ALTERNATIVE:

Relief is requested for the Second Inspection Interval for Byron Units 1 and 2.

8. PRECEDENTS:

Similar relief requests have been granted to:

Salem, Unit 1, Relief, ASME Code Requirements Related to the Salem Inservice Inspection Program, Relief Request S1-RR-B01 and S1-RR-C01 January 16, 2003 (ML030160750).

Dresden, Units 2 & 3, Relief Request CR-24 for Third 10-Year Inservice Inspection Interval, January 8, 2003 (ML023610374)

H. B. Robinson Steam Electric Plant, Unit 2, Third 10-Year Interval Inservice Inspection Program Plan Request for Relief No. 34 September 29, 2004 (ML042740082)

Surry Unit 1, Relief Request, re: ASME Section Xl ISI on Partial Examination September 28, 2005 (ML052690317)

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-22 Revision 0 (Page 3 of 6)

9. ATTACHMENTS:

Table 1: Unit 1 & Unit 2 Penetrations Subject to Examination during 2nd Inspection Interval Figure 1: Typical Containment Penetrations Figure 2: Typical Auxiliary Building Penetrations

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-22 Revision 0 (Page 4 of 6)

TABLE 1: Unit 1 & 2 Penetrations Subject to Examination during ~ Inspection Interval 1St IDENTIFICATION PIPE AU. WALL PEN.

PEN. PEN. DRAWING PEN. SELECTED TYPE NUMBER THICK THICK THICK SIZE CLEAR. FOR EXAM LINE WELD NUMBER A 1PC-7 1SXO6BB-16 C1OA 1SX-04 0.375 2 3- 6 300 6.5 X A 1PC-9 1SXO7FB-16 C12A 1SX-07 0.375 2 3- 6 300 6.5 A 1PC-14 1SXO7FA-16 C11A 1SX-10 0.375 2 3- 6 300 6.5 X A 1PC-15 1SXO6BA-16 COlA 1SX-01 0.375 2 3-6 300 6.5 A 1PC-66 1SIO4B-12 C15 lSl-12 1.125 2 3-6 240 4.9 A 1 PC-68 1 RHO1 BA-i 2 C03 1 RH-04 0.375 2 3 6 - 240 4.9 X A 1PC-75 1RHO1BB-12 C03 1RH-08 0.375 2 3- 6 24O 4.9 B lAB-ill 1 RHO3AA-8 C33 1 RH-03 0.322 1 3 0- 180 4.3 B 1 AB-1 15 1 RHO3AB-8 C52 1 RH-07 0.322 1 3 0- 180 4.3 B 1PC-50 1SIO5BA-8 COlA 1SI-04 0.906 2 3- 6 240 7.0 X B 1PC-51 1SI05BB-8 COlA lSl-26 0.906 2 3- 6 240 7.0 C 1AB-64 1RHO2AA-8 C20 1RH-05 0.322 1 3- 0 280 5.0 X C 1 AB-74 1 RHO2AB-8 C25 1 RH-09 0.322 1 3 0- 260 5.0 A 2PC-7 2SXO6BB-16 COlA 2SX-O4 0.375 2 3- 6 300 65 X A 2PC-9 2SXO7FB-16 C12A 2SX-07 0.375 2 3 6- 300 6.5 A 2PC-14 2SXO7FA-16 C1OA 2SX-10 0.375 2 3 -6 300 6.5 X A 2PC-15 2SXO6BA-16 COlA 2SX-0i 0.375 2 3 6- 300 6.5 A 2PC-66 2S104B-12 C02 2S1-12 1.125 2 3- 6 240 4.9 X A 2PC-68 2RHO1BA-12 C03 2RH-12 0.375 2 3- 6 240 4.9 A 2PC-75 2RHO1BB-12 C03 2RH-i1 0.375 2 3- 6 240 4.9 B 2AB-128 2RHO3AA-8 C49 2RH-10 0.322 11/4 3- 0 180 4.3 X B 2AB-133 2RHO3AB-8 C51 2RH-07 0.322 1% 3- 0 180 4.3 B 2PC-50 2SIO5BA-8 C02 2Sl-04 0.906 2 3 6

- 240 7.0 X B 2PC-51 2SIO5BB-8 C02 2Sl-26 0.906 2 3 6

- 240 7.0 B 2PC-99 2FW87CD-6 C04 2FW-12 0.432 2 4 6

- 160 3.8 B 2PC-1 00 2FW87CA-6 C04 2FW-i 1 0.432 2 4 6

- 160 3.8 X B 2PC-10l 2FW87CB-6 C04 2FW-06 0.432 2 4 6

- 160 3.8 B 2PC-102 2FW87CC-6 C04 2FW-10 0.432 2 4 6

- 160 3.8 C 2AB-36 2RHO2AA-8 C47 2RH-05 0.322 1 3 0

- 290 5.0 X C 2AB-68 2RHO2AB-8 C53 2RH-09 0.322 1 3 0

- 260 5.0 Note: See Figures 1 and 2 for drawings of the penetration configurations.

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-22 Revision 0 (Page 5 of 6)

FIGURE 1: Typical_Containment Penetrations Accessible Weld Pressure Retaining Pipe Type A

~ Inaccessible Weld Pc Penetration 4 Anchor 1

4 Plate

.4 4 ..l__..,__ ~

4, 4 44 8 4 13 Ic

- 8 ~

Containment Wall 44 0 ______________

4 4

4 44

~~cssftle Weld 4 04 8 4 4 44 4

tPc Pressure Retaining Pipe

~ Inaccessible Weld Type B F

Penetration a a a

4 04 4 0 4

Note: See Table 1 for dimensions as applied to each penetration. (Drawing not to scale)

BYRON STATION UNIT 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-22 Revision 0 (Page 6 of 6)

FIGURE 2: Typical Auxiliary Building Penetrations a

Accessible Weld 0 1 I Non Exempt Pressure Retaining Pipe

~ Inaccessible Weld

___________ Exempt Pressure Retaining Pipe Type C Anchor PIate~~

Penetration <I_______________________________

Concrete~WaIr ~

Tc Note: See Table 1 for dimensions as applied to each penetration. (Drawing

Enclosure 3 Byron Station Second Interval Relief Request 12R-23

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISl PROGRAM PLAN 10 CFR 50~55aRELIEF REQUEST I2R-23 Revision 0 (Page 1 of 5)

Request for Relief from ASME Section XI Requirements for Limited Volumetric Examination of Pressurizer Nozzle to Vessel Welds In Accordance with 10 CFR 50.55a(g)(5)(iii)

1. ASME CODE COMPONENT(S) AFFECTED:

Code Class: 1

Reference:

IWB-2500-l Examination Category: B-D Item Number: B3.ll0

Description:

Limited Examinations on Pressurizer Spray, Safety, and Relief Nozzle-to-Vessel Welds Component Numbers: 1 RY-0-l 5, PN-02, PN-03, PN-O4, PN-05, and PN-06 2RY-O-1S, PN-02, PN-03, PN-04, PN-05, and PN-06 Drawing Numbers: 1PZR-l-ISI, Sheet 1 (Unit 1) 2PZR-l-ISI, Sheet 1 (Unit 2)

2. APPLICABLE CODE EDITION AND ADDENDA:

The current Inservice Inspection program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code, Section Xl, 1989 Edition with no Addenda.

3. APPLICABLE CODE REQUIREMENTS:

ASME Section XI, 1989 Edition, Subsection IWB, Table IWB-2500-l, Examination Category B-D, Item B3. 110 requires volumetric examination of full penetration nozzle-to-vessel welds (Figure IWB-2500-7(b)). ASME Section V, 1989 Edition, Article 4, has the following requirements for the examination of these components:

A. T-44l .3.2.4 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 the 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.

B. T-441 .3.2.5 Angle Beam Scanning: . . . Wherever feasible, each examination shall be performed in two directions, i.e., approaching the weld from opposite directions and parallel to the weld from opposite directions.

C. T-44l .3.2.6 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 scanned by both angle beams from both directions D. T-441 .3.2.7 Scanning for Reflectors Oriented Transverse to the Weld: The angle beam search units shall he aimed parallel to the axis of the longitudinal and circumferential welds.

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-23 Revision 0 (Page 2 of 5)

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°to each other to the extent possible. Areas blocked by geometric conditions shall be examined from at least one direction.

4. IMPRACTICALITY OF COMPLIANCE:

Relief is requested from the examination coverage requirements of Figure IWB-2500-7(b).

10 CFR 50.55a(g)(4) states; 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 set forth in Section Xl of editions of the ASME Boiler and Pressure Vessel Code and Addenda to the extent practical within the limitations of design, geometry and materials of construction of the components. The geometry and materials of construction of the subject pressurizer nozzles results in limited access to the entire examination volume. See Figures 1 and 2 for the nozzle configurations.

The two limiting factors in the scanning of these nozzles are as follows:

A. The minimum scanning surface available on the nozzle side of the weld (component geometry) and B. The inability of the ultrasonic beam to reach beyond a 1/2V distance (due to the materials of construction).

The propagation for the ultrasonic beam was in the shear mode. Normally this mode would allow the ultrasonic beam to reflect off the inside surface and create two axis equivalent to two beams from opposite directions. This technique is not possible due to the stainless steel cladding on the inside of the vessel. The ultrasonic beam would not be completely reflected from the shell/clad interface. Most of the sound energy would be refracted through this layer and would be scattered as it reflected from the as welded clad inside surface. What sound energy reflected from the shell/clad interface would be of such low amplitude that it would be useless for examination purposes.

The current transducer sizes and designs available do not allow a significant portion of the examination volume to be scanned from the nozzle side. See Table 1 for the determination of actual coverage percentages achieved for each examination during the interval.

For Bl R08, the coverage obtained from the examinations was calculated using methods developed by CornEd Corporate Systems, Materials Analysis Division (pre-Exelon organization).

The required examination volume was divided into zones of base and weld material for the determination of coverage. These zones were assigned a percentage of coverage for each of nine scans for different angles and directions as required by ASME Section V. See Figure 3 for the examination volume required by ASME Section XI. The coverage obtained by each scan for each zone was averaged. Each zone received a weighting factor based on its total volume in relationship to the entire examination volume. This weighting factor is finally used to establish a single percentage of coverage for the nozzle as a whole, For later outages, the calculation method was simplified using vendor procedures and the scanning requirements for the weld zone were applied to the entire weld/base material volume. This later method resulted in a slightly lower coverage percentage than the more complicated initial method.

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-23 Revision 0 (Page 3 of 5)

5. BURDEN CAUSED BY COMPLIANCE:

Pursuant to 100FR5O.55a(g)(5)(iii), conformance with these Code requirements is impractical, as conformance would require extensive structural modifications to the pressurizer vessel.

6. PROPOSED ALTERNATIVE AND BASIS FOR USE:

The Code required VT-2 examination during system pressure testing per Category B-P is performed on the Pressurizer each refueling outage to verify the continued structural integrity of these nozzle areas. The obstructed volumetric examination along with the VT-2 examinations will provide reasonable assurance of the continued structural integrity of the welds. Byron Station will perform the Code required volumetric examination of the Pressurizer nozzle welds to the maximum extent possible for current techniques.

7. DURATION OF PROPOSED ALTERNATIVE:

Relief is requested for the second inspection interval for Byron Units 1 and 2.

8. PRECEDENTS:

Second 10-Year Interval Inservice Inspection Program Plan Requests for Relief Nos. 2IR-l, 2lR-2, 2IR-4, 21R-6, 2IR-10, 21-11, and 2IR-12 For Seabrook Station, Unit No. 1 authorized March 21, 2001 (ML010540162)

Calvert Cliffs Nuclear Power Plant, Units 1 and 2 Evaluation of Request for Relief No. ISI-6 authorized July 7, 2001 (MLO1 1860464).

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-23 Revision 0 (Page 4 of 5)

Figure 1: Pressurizer 84 Series Model D 4O Spray Nozzle Pressurizer Nozzle: PN-02 Unit 1 Bl RO8 Obtained Coverage 68.6%

Unit 2 B2R1 1 Obtained Coverage 62.3%

2.9O~

Required Examination Area Cladding

~-O.

19 Ref: Westinghouse Drawing EDSK379445 B (Drawing not to scale)

Figure 2: Pressurizer 84 Series Model D 6O Safety and Relief Nozzles Pressurizer Nozzles:

PN-03, PN-04, PN-05, PN-06 Unit 1 61 RO8 Obtained Coverage: PN-O3 69.4%

PN-05 69.4%

PN-O6 69.4%

2.90 Unit 1 61 Ri 1 Obtained Coverage: PN-O4 66.3%

Required Examination Unit 2 B2R09 Obtained Coverage: PN-O3 66.3%

Area PNO5 66.3%

PN-O6 66.3%

Unit 2 B2R1 1 Obtained Coverage: PN-04 62.3%

Claddin4 Ref: Westinghouse Drawing EDSK379558 B (Drawing not to scale)

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-23 Revision 0 (Page 5 of 5)

Figure 3: Required Examination Volume Minimum Scanning Requirements Examination Volume: (From ASME Section V, 1989 Edition)

A-B-C-D-E-F-G-H Ref: ASME Section XI, Figure JWB-2500-7(b) C Weld: B-C-F-G Two beam angles from two directions in both the perpendicular and parallel axis to the weld.

Base Material: A-B-G-H and C-D-E-F Two beam angles from one direction in both the perpendicular and parallel axis to the weld.

Where these requirements cannot be met due to component configuration, this shall be documented on the report.

(Drawing not to scale)

Table 1: Examination Coverage Obtained for Each Angle and Direction OUTAGE UNIT1 UNIT2 B1RO8 B1R11 B2R09 B2R11 PN-03 PN-03 NOZZLE PN-02 PN-05 PN-04 PN-05 PN 02 PNO4 PN-06 PN-06 SCAN TYPE & BASE WELD BASE WELD BASE+WELD BASE+WELD BASE+WELD DIRECTION MATERIAL MATERIAL MATERIAL MATERIAL MATERIAL MATERIAL MATERIAL 0° 53.9% 100.0% 55.8% 100.0% 72.8% 72.8% 64.2%

45°Perpendicular Up 903% - 100.0/0 886%

~

450 Perpendicular Down

  • 0.0% 0.0% 33.7% 33.7% 92.0%

45°C!ockwise 53.9% 100.0% 55.8% 10000/ -  %

450 Counter-Clockwise 642%

53.9% 100.0% 55.8% 100.0% 72.8% 72.8%

  • 60°Perpendicular Up 91.1% 100.0% 96.3% 26.5%

89.1% 96:~°~

60°Perpendicular Down 0.0% 0.0% 19.0% 19.0% 95.0%

60°Clockwise 53.9% 100.0% 55.8% 100.5% 72.8/s 72.8,5 64.2%

60°Counter-Clockwise 53.9% 100.0% 55.8% 100.0% 72.8% 72.8%

\VERAGE COVERAGE 64.4% 77.8% 65.2% 77.8% 66.3% 66.3% 62.3%

WEIGHING FACTOR* 0.682 0.318 0.667 0.333 - - -

EOTAL COVERAGE 68.7% 69.4% 66.3% 66.3% 62.3%

  • The weighing factor is the total volume of each area (weld and base material) in relationship to the entire examination volume.

Enclosure 4 Byron Station Second Interval Relief Request 12R-25

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-25 Revision 0 (Page 1 of 5)

Request for Relief from ASME Section XI Requirements for Limited Volumetric Examination of Reactor Pressure Vessel Head-to-Flange Weld In Accordance with 10 CFR 50.55a(g)(5)(iii)

1. ASME CODE COMPONENT(S) AFFECTED:

Code Class: 1

References:

IWB-2500, Table IWB-2500-1 Examination Category: B-A Item Number: Bi .40 Component Numbers: 1RC-O1R, RVHC-Ol (Unit 1) 2RC-O1R, RVHC-0l (Unit 2)

Drawing Numbers: 1 RPV-1-ISI Sheet 3 (Unit 1) 2RPV-1 -ISI Sheet 3 (Unit 2)

2. APPLICABLE CODE EDITION AND ADDENDA:

The current lnservice Inspection program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code, Section Xl, 1989 Edition with no Addenda.

3. APPLICABLE CODE REQUIREMENTS:

ASME Section XI, 1989 Edition, Table IWB-2500-1, Examination Category B-A, Item Bl.40, requires a surface and volumetric examination of essentially 100% of reactor vessel head-to-flange weld once each ten-year inspection interval (Figure IWB-2500-5). ASME Section V, 1989 Edition, Article 4, has the following requirements for the volumetric examination of these components:

A. T-441 .3.2.4 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 the 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.

B. T-441 .3.2.5 Angle Beam Scanning: ... Wherever feasible, each examination shall be performed in two directions, i.e., approaching the weld from opposite directions and parallel to the weld from opposite directions.

C. T-441 .3.2.6 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 scanned by both angle beams from both directions

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-25 Revision 0 (Page 2 of 5)

4. IMPRACTICALITY OF COMPLIANCE:

Pursuant to 10CFR5O.55a(g)(5)(iii), conformance with these code requirements is impractical.

Relief is requested from the volumetric examination coverage requirements of Figure IWB-2500-5.

10 CFR 50.55a(g)(4) states; 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 set forth in Section Xl of editions of the ASME Boiler and Pressure Vessel Code and Addenda to the extent practical within the limitations of design, geometry and materials of construction of the components. The geometry and materials of construction of the reactor vessel head-to-flange weld results in limited access to the entire examination volume. See Figures 1 and 2 for the scanning obstructions.

The three limiting factors in the scanning of the head to flange weld are as follows:

A. The minimum scanning surface available on the flange side of the weld (component geometry),

B. The inability of the ultrasonic beam to reach beyond a 1/2V distance (component materials of construction), and C. Obstructions on the head side of weld (component design).

The Reactor Vessel flange physically obstructs the ultrasonic transducer movement that is needed to examine the Code required volume from the flange side. Figure 1 shows the position of the weld and flange. The propagation for the ultrasonic beam was in the shear mode.

Normally this mode would allow the ultrasonic beam to reflect off the inside surface and create two-beam axis at right angles to each other. This technique is not possible due to the stainless steel cladding on the inside of the vessel. The ultrasonic beam would not be completely reflected from the shell/clad interface. Most of the sound energy would be refracted through this layer and would be scattered as it reflected from the as welded clad inside surface. What sound energy reflected from the shell/clad interface would be of such low amplitude that it would be useless for examination purposes.

In addition to the flange, parts of the three large head lifting lugs also fall in the required scan area. A diagram of the transducer position for actual and required coverage is shown in Figure 2 illustrating the obstructed areas.

During Bi Ri 1 outage in the Spring of 2002, the Unit 1 head-to-flange weld was examined using volumetric and surface techniques. Calculations of the examination data estimated that 73.0% of the required Code volume was examined. The code required surface exam was also performed on the accessible areas and 100% of the code surface was achieved. The same examination results were obtained for the Unit 2 examination performed during B2R1O in the Fall of 2002.

5. BURDEN CAUSED BY COMPLIANCE:

Current ultrasonic examination techniques available for field use are not capable of achieving the required examination volume. To replace the reactor vessel head because of the unachieved volume would be a prohibitive option. The limitation caused by the configuration is inherent in the design of the reactor head.

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-25 Revision 0 (Page 3 of 5)

6. PROPOSED ALTERNATIVE AND BASIS FOR USE:

The obstructed volumetric examination, along with the surface examination, and the visual (VT-2) examinations that are performed every refuel outage will provide reasonable assurance of the continued structural integrity of the weld. Furthermore, past Preservice and First Interval examinations have revealed no recordable indications. Byron Station performed the Code required volumetric examination of the Reactor Vessel Head-to-Flange weld to the maximum extent possible for current techniques.

7. DURATION OF PROPOSED ALTERNATIVE:

Relief is requested for the Second Ten-Year Inspection Interval.

8. PRECEDENTS:

Similar relief requests have been granted to:

Braidwood; Approval of Relief Requests for 2nd 10-Year Interval, January 6, 2000 (ML003673725).

Second 10-Year Interval Inservice Inspection Program Plan Requests for Relief Nos. 2lR-1, 21R-2, 2lR-4, 21R-6, 2IR-1 0, 2lR-l 1, and 21R-12 For Seabrook Station, Unit No. 1, March 21, 2001 (MLO1 0540162).

Prairie Island, Unit 2, Relief, Evaluation of Relief Request No. 8 for the Third 10-Year Interval lnservice Inspection Program Plan, Limited Examination, August 8, 2000 (ML003738379).

9. ATTACHMENTS: ,

Figure 1: Reactor Vessel Head Configuration Figure 2: Scan Obstructions

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST l2R-25 Revision 0 (Page 4 of 5)

Figure 1: Reactor Vessel Head Configuration Cladding 3/16 Nominal 6 3/4 Lifting Lug 7

RVHC-OO1 Detail CLOSURE HEAD DUTCHMAN ID CLADDING FLANGI B

EXAM VOLUME A-B-C-D (Figure IWB-2500-5)

NOTTO SCALE DIMENSIONS FOR INFORMATION ONLY

BYRON STATION UNITS 1 & 2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-25 Revision 0 (Page 5 of 5)

Figure 2: Scan Obstructions NOT TO SCALE LIFTING LUG DIMENSIONS FOR OBSTRUCTION INFORMATION ONLY SURFACE QRVHC-02

14. z 0<

(ow 0<

w 14.

OBSTRUCTION

Enclosure 5 Byron Station Second Interval Relief Request I2R-53

BYRON STATION UNITS 1&2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-53 Revision 0 (Page 1 of 5)

Request for Relief from ASME Section XI Requirements for Limited Volumetric Examination of Residual Heat Removal Heat Exchanger Vessel Shell-to-Flange Weld In Accordance with 10 CFR 50~55a(g)(5)(iii)

1. ASME CODE COMPONENT(S) AFFECTED:

Code Class: 2

References:

IWC-2500, Table IWB-2500-1 Examination Category: C-A Item Number: C1.10 Component Numbers: 1RH-02-AB, RHEC-Ol (Unit 1) 2RH-02-AA, RHEC-Ol (Unit 2)

Drawing Numbers: 1RHX-1-ISl (Unit 1) 2RHX-1-ISI (Unit 2)

2. APPLICABLE CODE EDITION AND ADDENDA:

The current Inservice Inspection program is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code,Section XI, 1989 Edition with no Addenda.

3. APPLICABLE CODE REQUIREMENTS:

ASME Section Xl, 1989 Edition, Table IWC-2500-1, Examination Category C-A, Item Cl.lO, requires a volumetric examination of essentially 100% of Residual Heat Removal Heat Exchanger (RHRHX) shell-to-flange weld once each ten-year inspection interval (Figure IWC-2500-l). ASME Section Xl, 1989 Edition, Article Ill, has the following requirements for the volumetric examination of these components:

A. 111-3230 Angle Beam Calibration: (a) Obtain the angle beam paths required ... Variables such as weld preparation, weld crown width, or physical interference may preclude obtaining two-beam path direction coverage of the complete examination volume with half-V examination from two sides as shown in Fig. 111-3230-1. If this interference with examination coverage occurs, the beam path shall be increased as required to obtain full coverage of the examination volume from two directions.

B. 111-4420 Reflectors Parallel to the Weld Seam: The examination shall be performed using a sufficiently long examination beam path to provide coverage of the required examination volume in two-beam path directions. The examination shall be performed from two sides of the weld, where practicable, or from one side of the weld, as a minimum.

C. Supplement 4 Austénitic and Dissimilar Metal Welds: Paragraph b(2) 111-4430 Reflectors Transverse to the Weld Seam Substitute: The angle beam examination for reflectors transverse to the weld shall be performed in two directions covering the minimum area from 1/2 in. from one side of the weld crown to 1/2 in. from the other side of the weld crown including the crown.

BYRON STATION UNITS 1&2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-53 Revision 0 (Page 2 of 5)

4. IMPRACTICALITY OF COMPLIANCE:

Pursuant to 1 OCFR5O.55a(g)(5)(iii), conformance with these code requirements is impractical.

Relief is requested from the volumetric examination coverage requirements of Figure IWC-2500-1.

10 CFR 50.55a(g)(4) states; 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 set forth in Section Xl of editions of the ASME Boiler and Pressure Vessel Code and Addenda to the extent practical within the limitations of design, geometry and materials of construction of the components. The geometry and materials of construction of the RHRHX shell-to-flange weld results in limited access to the entire examination volume. The limiting factor in the scanning of the flange weld is the minimum scanni~1gsurface available on the flange side of the weld (component geometry). See Figure 1 for the scanning obstruction.

The RHRHX flange physically obstructs the ultrasonic transducer movement that is needed to examine the Code required volume from the flange side. Figure 1 shows the position of the weld and flange. The propagation for the ultrasonic beam was in the refracted longitudinal (RL) mode for 60°1/2 V scanning and in the shear (5) mode for 45°full-V scanning. The 60°RL was needed to increase the obtained range on the flange side ID portion. The 45°Sfull-V was needed to increase the obtained range on the flange side OD portion.

Calculations for the final coverage achieved during the Second Inspection Interval resulted in 71.75% obtained. See Table 1 for the coverage calculations.

5. BURDEN CAUSED BY COMPLIANCE:

Current ultrasonic examination techniques available for field use are not capable of achieving the required examination volume. Removal of the studs and nuts on the flange will not significantly increase the examination volume achieved. To replace or redesign the RHRHX vessel flange because of the unachieved volume would be a prohibitive option. The limitation caused by the configuration is inherent in the design of the vessel.

6. PROPOSED ALTERNATIVE AND BASIS FOR USE:

The volumetric examination along with the visual (VT-2) examinations that are performed once per Inspection Period under Examination Category C-H will provide reasonable assurance of the continued structural integrity of the weld. Byron Station will perform the Code required volumetric examination of the Residual Heat Removal Heat Exchanger Vessel Shell-to-Flange Weld to the maximum extent possible with current ultrasonic techniques.

7. DURATION OF PROPOSED ALTERNATIVE:

Relief is requested for the Second Ten-Year Inspection Interval.

BYRON STATION UNITS 1&2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST I2R-53 Revision 0 (Page 3 of 5)

8. PRECEDENTS:

Similar relief requests have been granted to:

Salem, Unit 1, Relief, ASME Code Requirements Related to the Salem Inservice Inspection Program, Relief Request Sl-RR-BO1 and Sl-RR-CO1, January 16, 2003 (ML030160750)

Davis-Besse, Unit 1, Relief, Third 10-Year Interval Inservice Inspection Program Plan, September 30, 2002 (MLO22700279)

9. ATTACHMENTS:

Calculation of Volumetric Examination Coverage

BYRON STATION UNITS 1&2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-53 Revision 0 (Page 4 of 5)

Calculation of Volumetric Examination Coverage The volumetric examination of the shell-to-flange weld is obstructed on the flange-side due to the proximity of the flange. Scanning perpendicular (axial) to the weld was restricted to the shell-side only. The 45°Shear wave examination was supplemented with scanning from the shell-side with a 60°Refracted Longitudinal beam. Additionally, the transducers were obstructed from scanning forward of the points shown by the transducer lift-off at the toe of the weld resulting in loss of signal.

There are no additional obstructions for the entire length of the weld.

Scanning requirements At least one angle from two directions in both the perpendicular and parallel axis to the weld.

Single side access limitations shall be noted in the examination data record.

Figure 1: Comr~onentConficiuration. Reauired Area. and Beam Anales Used

Reference:

Examination Figure IWC-2500-1 Required Examination: Volume A-B-C-D Calculation Method

1. The minimum distance for the transducer exit point was determined by the UT report.
2. The maximum coverage obtained was determined using a scaled drawing in a CAD program based on measurements in the UT report and Joseph Oat Corporation drawing #5624, Vertical Residual Heat Exchanger Details.
3. The cross section of the weld is 1.872 square inches (A-B-C-D). This consists of the 2 by 0.9 weld and base material thickness with 0.072 square inches added for the weld crown.
4. The beam locations were plotted and the area achieved was measured. See Figure 2.
5. The coverage achieved for each of the four scan directions was averaged.

BYRON STATION UNITS 1&2 SECOND INTERVAL ISI PROGRAM PLAN 10 CFR 50.55a RELIEF REQUEST 12R-53 Revision 0 (Page 5 of 5)

Figure 2: Area Achieved for Each Beam Angle Circumferential Scan Direction: L For the 45°Shear,the area obtaine d was from the flange-side fl .

of the weld to a distance of 1/2 inch beyond the weld toe on the  !

shell side (B-C).  !

Axial Scan Direction #1:

Shell side beam direction using 1/2 V path.

For the 6O°RL,the area obtained was the from the maximum exit point to the required area on the shell side (B-C).

24 Axial Scan Direction #2:

Equivalent to a flange side beam direction using Full-V path.

For the 45°Shear,the area obtained was the from the 2nd leg maximum exit point to the required area on the shell side (B-C).

Table 1: Coverage Obtained Using 45°SFull V Path and 60°RLFrom Shell-Side Only SCAN DIRECTION REQUIRED AREA ACHIEVED AREA PERCENTAGE Circumferential Clock-Wise 1.422* 75.96%

45°S Counter Clock-Wise 1.422* 75.96%

872*

, Direction#l 6O°RL 1 .061 56.68%

Axial ---------- -.,,.,..,,,,,,..--,.--.....-.-.------..-.-

Direction#2 45°S 1.467* 78.37%

AVERAGE PERCENTAGE ACHIEVED: 71 .75%

  • Includes 0.072 for weld crown.
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