ML060090142

Relaxation of First Revised Order on Reactor Vessel Nozzles

ML060090142
Person / Time
Site:	Indian Point
Issue date:	02/27/2006
From:	Catherine Haney Plant Licensing Branch III-2
To:	Kansler M Entergy Nuclear Operations
Boska J, NRR, 301-415-2901
References
TAC MC9230
Download: ML060090142 (13)

Text

February 27, 2006 Mr. Michael R. Kansler President Entergy Nuclear Operations, Inc.

440 Hamilton Avenue White Plains, NY 10601

SUBJECT:

RELAXATION OF FIRST REVISED ORDER ON REACTOR VESSEL NOZZLES, INDIAN POINT NUCLEAR GENERATING UNIT NO. 2 (TAC NO. MC9230)

Dear Mr. Kansler:

In a letter dated December 14, 2005, Entergy Nuclear Operations, Inc. (the licensee), submitted a request for relaxation regarding the inspection of reactor pressure vessel (RPV) head and penetration nozzles at Indian Point Nuclear Generating Unit No. 2 (IP2). The relaxation was requested from the interim inspection requirements in the Nuclear Regulatory Commissions (NRCs) First Revised Order Modifying Licenses, EA-03-009, dated February 20, 2004 (First Revised Order).

The NRC staff has reviewed the licensees requested relaxation to implement certain alternatives to the requirements of the First Revised Order at IP2. Specifically, the licensee proposed relaxation from the inspection coverage for the nondestructive examination, using ultrasonic testing techniques of RPV head penetration nozzles, that are limited by a threaded section that is less than the 1 inch lower boundary limit specified in Section IV, paragraph C.5.(b) of the First Revised Order. The results are provided in the enclosed safety evaluation (SE).

For the examination coverage regarding the RPV penetration nozzles, the NRC staff has concluded for IP2 that the proposed alternative examinations provide reasonable assurance of the structural integrity. Further inspections of these nozzles in accordance with Section IV, paragraph C.5(b) of the First Revised Order would result in hardship without a compensating increase in the level of quality and safety. Therefore, in accordance with Section IV, paragraph F, of the First Revised Order, the NRC staff authorizes the proposed relaxation and alternative inspection for the RPV penetration nozzles at IP2 for the life of the Order, subject to the condition specified in the SE.

M. Kansler If you should have any questions, please contact John Boska at 301-415-2901.

Sincerely,

/RA/

Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-247

Enclosure:

As stated cc w/encl: See next page

M. Kansler If you should have any questions, please contact John Boska at 301-415-2901.

Sincerely,

/RA/

Catherine Haney, Director Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-247

Enclosure:

As stated cc w/encl: See next page DISTRIBUTION:

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Accession Number: ML060090142 *See previous concurrence OFFICE LPD1-1/PM LPD1-1/LA CPNB/BC OGC LPD1-1/BC LPD1-1/D NAME JBoska SLittle TChan* SHamrick RLaufer CHaney DATE 1/30/06 1/30/06 1/19/06 2/21/06 2/22/06 2/27/06 OFFICIAL RECORD COPY

Indian Point Nuclear Generating Unit No. 2 cc:

Mr. Gary J. Taylor Ms. Charlene D. Faison Chief Executive Officer Manager, Licensing Entergy Operations, Inc. Entergy Nuclear Operations, Inc.

1340 Echelon Parkway 440 Hamilton Avenue Jackson, MS 39213 White Plains, NY 10601 Mr. John T. Herron Mr. Michael J. Columb Senior Vice President and Director of Oversight Chief Operating Officer Entergy Nuclear Operations, Inc.

Entergy Nuclear Operations, Inc. 440 Hamilton Avenue 440 Hamilton Avenue White Plains, NY 10601 White Plains, NY 10601 Mr. James Comiotes Mr. Fred R. Dacimo Director, Nuclear Safety Assurance Site Vice President Entergy Nuclear Operations, Inc.

Entergy Nuclear Operations, Inc. Indian Point Energy Center Indian Point Energy Center 295 Broadway, Suite 1 295 Broadway, Suite 1 P.O. Box 249 P.O. Box 249 Buchanan, NY 10511-0249 Buchanan, NY 10511-0249 Mr. Patric Conroy Mr. Paul Rubin Manager, Licensing General Manager, Plant Operations Entergy Nuclear Operations, Inc.

Entergy Nuclear Operations, Inc. Indian Point Energy Center Indian Point Energy Center 295 Broadway, Suite 1 295 Broadway, Suite 2 P. O. Box 249 P.O. Box 249 Buchanan, NY 10511-0249 Buchanan, NY 10511-0249 Mr. Travis C. McCullough Mr. Oscar Limpias Assistant General Counsel Vice President Engineering Entergy Nuclear Operations, Inc.

Entergy Nuclear Operations, Inc. 440 Hamilton Avenue 440 Hamilton Avenue White Plains, NY 10601 White Plains, NY 10601 Ms. Stacey Lousteau Mr. Brian OGrady Treasury Department Vice President, Operations Support Entergy Services, Inc.

Entergy Nuclear Operations, Inc. 639 Loyola Avenue 440 Hamilton Avenue Mail Stop: L-ENT-15E White Plains, NY 10601 New Orleans, LA 70113 Mr. John F. McCann Regional Administrator, Region I Director, Licensing U.S. Nuclear Regulatory Commission Entergy Nuclear Operations, Inc. 475 Allendale Road 440 Hamilton Avenue King of Prussia, PA 19406 White Plains, NY 10601

Indian Point Nuclear Generating Unit No. 2 cc:

Senior Resident Inspectors Office Mr. William T. Russell Indian Point 2 PWR SRC Consultant U. S. Nuclear Regulatory Commission 400 Plantation Lane P.O. Box 59 Stevensville, MD 21666-3232 Buchanan, NY 10511 Mr. Jim Riccio Mr. Peter R. Smith, President Greenpeace New York State Energy, Research, and 702 H Street, NW Development Authority Suite 300 17 Columbia Circle Washington, DC 20001 Albany, NY 12203-6399 Mr. Phillip Musegaas Mr. Paul Eddy Riverkeeper, Inc.

Electric Division 828 South Broadway New York State Department Tarrytown, NY 10591 of Public Service 3 Empire State Plaza, 10th Floor Mr. Mark Jacobs Albany, NY 12223 IPSEC 46 Highland Drive Mr. Charles Donaldson, Esquire Garrison, NY 10524 Assistant Attorney General New York Department of Law 120 Broadway New York, NY 10271 Mayor, Village of Buchanan 236 Tate Avenue Buchanan, NY 10511 Mr. Ray Albanese Executive Chair Four County Nuclear Safety Committee Westchester County Fire Training Center 4 Dana Road Valhalla, NY 10592 Mr. William DiProfio PWR SRC Consultant 139 Depot Road East Kingston, NH 03827 Mr. Daniel C. Poole PWR SRC Consultant P.O. Box 579 Inglis, FL 34449

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELAXATION OF FIRST REVISED ORDER MODIFYING LICENSES, EA-03-009 EXAMINATION COVERAGE FOR REACTOR PRESSURE VESSEL HEAD AND PENETRATIONS NOZZLES INDIAN POINT NUCLEAR GENERATING UNIT NO. 2 ENTERGY NUCLEAR OPERATIONS, INC.

DOCKET NO. 50-247

1.0 INTRODUCTION

On February 20, 2004 (Agencywide Documents Access and Management System (ADAMS)

Accession No. ML040220181), the Nuclear Regulatory Commission (NRC) issued the First Revised NRC Order Modifying Licenses, EA-03-009 (First Revised Order), requiring specific examinations of the reactor pressure vessel (RPV) head and vessel head penetration (VHP) nozzles of all pressurized-water reactor (PWR) plants.Section IV, paragraph F, of the First Revised Order states that requests for relaxation of the Order associated with specific penetration nozzles will be evaluated by the NRC staff using the procedure for evaluating proposed alternatives to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) in accordance with Section 50.55a(a)(3) of Part 50 of Title 10 of the Code of Federal Regulations (10 CFR 50.55a(a)(3)).Section IV, paragraph F, of the Order states that a request for relaxation regarding inspection of specific nozzles shall address the following criteria: (1) the proposed alternative(s) for inspection of specific nozzles will provide an acceptable level of quality and safety, or (2) compliance with this Order for specific nozzles would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

For Indian Point Nuclear Generating Unit No. 2 (IP2) and similar plants that were determined to have a moderate susceptibility to primary water stress-corrosion cracking (PWSCC) in accordance with Section IV, paragraphs A and B, of the First Revised Order, the following inspections shall be performed such that at least the requirements of paragraph Section IV, paragraphs C5(a) or C.5(b) are performed each refueling outage:

(a) Bare metal visual [BMV] examination of 100 percent of the RPV head surface (including 360E around each RPV head penetration nozzle). For RPV heads with the surface obscured by support structure interferences which are located at RPV head elevations downslope from the outermost RPV head penetration, a Enclosure

bare metal visual inspection of no less than 95 percent of the RPV head surface may be performed provided that the examination shall include those areas of the RPV head upslope and downslope from the support structure interference to identify any evidence of boron or corrosive product. Should any evidence of boron or corrosive product be identified, the licensee shall examine the RPV head surface under the support structure to ensure that the RPV head is not degraded.

(b) For each penetration, perform a nonvisual NDE [nondestructive examination] in accordance with either (i), (ii) or (iii):

(i) Ultrasonic testing of the RPV head penetration nozzle volume (i.e., nozzle base material) from 2 inches above the highest point of the root of the J-groove weld (on a horizontal plane perpendicular to the nozzle axis) to 2 inches below the lowest point at the toe of the J-groove weld on a horizontal plane perpendicular to the nozzle axis (or bottom of the nozzle if less than 2 inches [See Figure IV-1]); OR from 2 inches above the highest point of the root of the J-groove weld (on a horizontal plane perpendicular to the nozzle axis) to 1.0-inch below the lowest point at the toe of the J-groove weld (on a horizontal plane perpendicular to the nozzle axis) and including all RPV head penetration nozzle surfaces below the J-groove weld that have an operating stress level (including all residual and normal operation stresses) of 20 ksi tension and greater (see Figure IV-2). In addition, an assessment shall be made to determine if leakage has occurred into the annulus between the RPV head penetration nozzle and the RPV head low-alloy steel.

(ii) Eddy current testing or dye penetrant testing of the entire wetted surface of the J-groove weld and the wetted surface of the RPV head penetration nozzle base material from at least 2 inches above the highest point of the root of the J-groove weld (on a horizontal plane perpendicular to the nozzle axis) to 2 inches below the lowest point at the toe of the J-groove weld on a horizontal plane perpendicular to the nozzle axis (or the bottom of the nozzle if less than 2 inches [see Figure IV-3]); OR from 2 inches above the highest point of the root of the J-groove weld (on a horizontal plane perpendicular to the nozzle axis) to 1.0-inch below the lowest point at the toe of the J-groove weld (on a horizontal plane perpendicular to the nozzle axis) and including all RPV head penetration nozzle surfaces below the J-groove weld that have an operating stress level (including all residual and normal operation stresses) of 20 ksi tension and greater (see Figure IV-4).

(iii) A combination of (i) and (ii) to cover equivalent volumes, surfaces and leak paths of the RPV head penetration nozzle base material and J-groove weld as described in (i) and (ii). Substitution of a portion of a volumetric exam on a nozzle with a surface examination may be performed with the following requirements:

1. On nozzle material below the J-groove weld, both the outside diameter and inside diameter surfaces of the nozzle must be examined.

2. On nozzle material above the J-groove weld, surface examination of the inside diameter surface of the nozzle is permitted provided a surface examination of the J-groove weld is also performed.

In addition, for those plants in the Moderate category, the requirements of Section IV, paragraphs C.5(a) and C.5(b) shall each be performed at least once over the course of every 2 refueling outages.

By letter dated October 15, 2004 (ADAMS Accession No. ML042890389), the NRC authorized IP2 to perform a BMV examination of no less than 95 percent of the RPV head surface (versus the 100 percent specified in the Order) due to interference from the insulation support ring.

By letter dated December 14, 2005 (ADAMS Accession No. ML053570382), Entergy Nuclear Operations, Inc. (Entergy, or the licensee) requested relaxation to implement an alternative to the requirements of Section IV, Section C.5(b) of the First Revised Order for RPV head penetration nozzles at IP2. The specific relaxation requested is provided below.

2.0 FIRST REVISED NRC ORDER EA-03-009 RELAXATION REQUEST FOR EXAMINATION COVERAGE FOR REACTOR PRESSURE VESSEL HEAD AND PENETRATION NOZZLES 2.1 First Revised NRC Order Requirements for Which Relaxation is Requested The licensee has requested relaxation from Section IV, paragraph C.5(b) of the First Revised NRC Order. The specific relaxation is identified below.

2.2 Licensees Proposed Alternative The licensee seeks relaxation from the Order where inspection coverage is limited by a threaded section which is less than the 1 inch lower boundary limit specified in Section IV, paragraph C.5(b) of the First Revised NRC Order for RPV head penetration nozzles at IP2, with respect to non-destructive examination (NDE). The licensee stated that relaxation is requested from Section IV, paragraph C.5(b) of the Order from 1.0 inch below the lowest point at the toe of the J-groove weld (on a horizontal plane perpendicular to the nozzle axis) and including all RPV head penetration nozzle surfaces below the J-groove weld that have an operating stress level (including all residual and normal operation stresses) of 20 ksi tension and greater (see Figure IV-2 of the First Revised Order).

The licensee proposes to perform ultrasonic testing (UT) from the inside surface of each RPV head penetration nozzle (i.e. nozzle base material) from 2 inches above the J-grove weld and extending down the nozzle to at least the top of the threaded region or further down the threaded region to the extent allowed by technology and geometry, but in all cases achieving the minimum requirements specified in Table 1. Although not presently planned, the licensee states that they may choose to perform eddy current testing (ECT) in lieu of UT of the wetted surface excluding any threaded surfaces and the chamfer region in selected nozzles. If ECT is

performed, the minimum requirements of Table 1 will still apply. The 2R17 refueling outage is currently scheduled for April 2006. The licensee has stated that IP2 is expected to remain in the moderate susceptibility category past the 2R18 refueling outage, currently planned for spring 2008. The next non-visual NDE inspection of the RPV head is currently planned for the spring of 2010 during the 2R19 refueling outage.

2.3 Reason for Relaxation Request The licensee stated that the proposed alternative provides an acceptable level of quality and safety.

2.4 Licensees Basis for Proposed Alternative The licensee stated that the design of the RPV head penetration nozzles at IP2 includes a threaded section, approximately 3/4-inch long, at the bottom of the nozzles. The dimensional configuration at some nozzles is such that the distance from the lowest point at the toe of the J-groove weld to the bottom of the scanned region is less than the 1 inch lower boundary limit specified in Section IV, paragraph C.5(b) of the First Revised NRC Order. Review of the previous NDE data showed that in some cases, 1 inch coverage cannot be achieved. However, the licensee will attempt to maximize coverage to comply with the First Revised NRC Order.

UT from the inside surface of the threaded region of the nozzle is partially achievable by new scanning techniques, previously not available in IP2 refueling outage 2R15. ECT probes are not capable of examining the threaded surfaces. The licensee has stated that dye penetrant testing (PT) of the threaded surfaces is possible. However, it would require personnel to be located under the RPV head for surface cleaning and penetrant testing operations and would result in significant personnel radiation exposure. During 2R15, a PT of a weld was performed under the RPV head on an indication at a person-rem exposure of 1.7 rem. Hence, the licensee has proposed UT from the inside surface of the threaded region of the nozzle to remotely inspect the portion of the nozzle below the J-groove weld to minimize radiation exposure to the inspection personnel.

The licensee performed stress analysis and crack growth evaluations for postulated through-wall axial flaws extending upwards from the nozzle towards the lower J-groove weld. The time to reach the lowest point at the toe of the J-groove weld is greater than 4 effective full power years (EFPY) based on a minimum inspection coverage below the J-groove weld for all the penetration nozzles as indicated in Table 1. The stress analysis consisted of a three-dimensional elastic-plastic finite element analysis that considered all the pertinent loadings on the penetrations. The three-dimensional finite element model used to obtain the stresses was comprised of iso-parametric brick and wedge elements. The penetration nozzle, weld metal, cladding, and vessel head were modeled in accordance with the relevant material properties.

The most important loading conditions were found to be those which normally exist on the penetration nozzle in the majority of the cases. These loadings included pressure and temperature loadings associated with the steady state operation condition. In addition, the residual stresses from the weld fabrication process were also considered.

The licensee has stated that based on the results of the stress analysis, the service life required for any of the upper crack tips to reach the lowest point of the toe of the J-groove weld for all the penetration nozzles exceeded 4 EFPY. The time duration between the inspection cycles is

4 years in accordance with the NRC First Revised Order for moderate category plants. IP2 is expected to remain as a moderate category plant past refueling outage 2R18, currently planned for spring 2008. Therefore, as a screening rule, if the inspection coverage of Table 1 is achieved below the J-groove weld on the downhill side of the head penetration nozzles in 2R17, the upper crack tip of any undetected axial through-wall flaw in the region not being inspected is not expected to reach the lowest point of the toe of the J-groove weld in less than 4 EFPY, or before the subsequent 2R19 inspection. The licensee has stated that the intent of the requirements in the NRC First Revised Order will be met.

The licensee has further clarified that for those penetrations where information on the inspection is not available, it has been assumed that the inspection coverage for those penetrations are comparable to those obtained for nozzles in the same vicinity. There are a total of 5 penetrations with penetration numbers 1, 6, 7, 9, and 77 that were not examined in 2R15 refueling outage.

2.5 Evaluation The NRC staffs review of this request was based on criterion (2) of paragraph F of Section IV of the Order which states:

Compliance with this Order for specific nozzles would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

Within the context of the licensees proposed alternative examination of the RPV head penetration nozzles, the licensee has demonstrated the hardship that would result from implementing examinations to the bottom end of these nozzles. The licensee identified the hardship by stating the design of the RPV head penetration nozzles includes a threaded section, approximately 3/4-inch long, at the bottom of the nozzles. The dimensional configuration at some of the nozzles is such that the distance from the lowest point at the toe of the J-groove weld to the bottom of the scanned region (essentially the start of the threaded region) is less than the 1 inch lower boundary limit specified in Section IV, paragraph C.5(b) of the First Revised Order. ECT would not provide meaningful results in the threaded region. PT of the threaded surfaces is possible, but results in very high doses to inspection personnel. UT from the inside surface of the threaded region using new vendor scanning techniques may provide meaningful results. In all cases, the minimum UT coverage specified in Table 1 will be achieved.

The phenomenon of concern is primary water stress-corrosion cracking (PWSCC), which typically initiates in the areas of highest stress. The area of RPV head penetration nozzles that has the highest residual stress is the area adjacent to the J-groove attachment weld.

Therefore, it is most likely that PWSCC will initiate in an area adjacent to the J-groove attachment weld.

The licensee proposed to examine the minimum distance of the nozzle base material below the J-groove attachment weld to the top of essentially the start of the threaded region, which varies for each nozzle as is identified in Table 1. The licensee has stated that based on the results of the stress analysis, the service life required for any of the upper crack tips to reach the lowest point of the toe of the J-groove weld for all the penetration nozzles exceeded 4 EFPY. The time duration between the inspection cycles is 4 years in accordance with the NRC First Revised

Order for moderate category plants. IP2 is expected to remain as a moderate category plant past 2R18. Therefore, as a screening rule, if the inspection coverage of Table 1 is achieved below the J-groove weld on the downhill side of the head penetration nozzles in 2R17, the upper crack tip of any undetected axial through-wall flaw in the region not being inspected is not expected to reach the lowest point of the toe of the J-groove weld in less than 4 EFPY, or before the subsequent 2R19 inspection. Hence, the intent of the requirements in the NRC First Revised Order is met.

The licensees analysis used the crack growth formula in Electric Power Research Institute (EPRI) Report Material Reliability Program (MRP) Report MRP-55, Material Reliability Program Crack Growth Rates for Evaluating Primary Water Stress Corrosion Cracking of Thick Wall Alloy 600 Material (MRP-55), Revision 1. Should the NRC staff determine the crack growth formula used by the licensee to be unacceptable, the licensee has committed to revise its analysis to incorporate an acceptable crack growth formula as described below.

If the NRC staff finds that the crack-growth formula in industry report MRP-55 is unacceptable, the licensee shall revise its analysis that justifies relaxation of the First Revised NRC Order dated February 20, 2004, within 30 days after the NRC informs the licensee of an NRC-approved crack growth formula. If the licensees revised analysis shows that the crack growth acceptance criteria are exceeded prior to the end of the then current operating cycle, this relaxation is rescinded and the licensee shall, within 72 hours3 days <br />0.429 weeks <br />0.0986 months <br />, submit to the NRC written justification for continued operation. If the revised analysis shows that the crack growth acceptance criteria are exceeded during the subsequent operating cycle, the licensee shall, within 30 days, submit the revised analysis for NRC review. If the revised analysis shows that the crack growth acceptance criteria are not exceeded during either the current operating cycle or the subsequent operating cycle, the licensee shall, within 30 days, submit a letter to the NRC confirming that its analysis has been revised. Any future crack-growth analyses performed for this and future cycles for RPV head penetrations must be based on an acceptable crack growth formula.

The licensee committed to the above requirement in the application.

Based on the information above, the NRC staff concludes that performance of UT from the inside surface of each RPV head penetration nozzle (i.e. nozzle base material) from 2 inches above the J-grove weld and extending down to the threaded region or further down the threaded region to the extent allowed by technology and geometry, but in all cases achieving the minimum requirements specified in Table 1, is acceptable. ECT of the wetted surface excluding any threaded surfaces and the chamfer region in lieu of UT is also acceptable, as long as the minimum requirements of Table 1 are met.

3.0 CONCLUSION

The NRC staff concludes that the licensees proposed alternative examination of the RPV penetration nozzles from the minimum distance (specified by Table 1 for each individual nozzle penetration) below the lowest point at the toe of the J-groove weld, which is the top of the threaded region, provides reasonable assurance of the structural integrity of the RPV head, RPV penetration nozzles, and welds, since the licensees crack growth analysis indicates that it will take more than 4 EFPY for a crack to propagate to the point of allowing reactor coolant system pressure boundary leakage from the RPV head nozzles. Subsequent NDE inspections will be accomplished within 4 EFPY. Further inspections of these RPV penetration nozzles in accordance with Section IV, paragraph C.5(b), of the First Revised NRC Order EA-03-009, dated February 20, 2004, would result in hardship and excessive personnel radiation exposure without a compensating increase in the level of quality and safety. Therefore, pursuant to Section IV, paragraph F, of the First Revised NRC Order EA-03-009, dated February 20, 2004, the NRC staff authorizes the proposed alternative inspection for the RPV penetration nozzles listed in Table 1 at IP2 for the life of the Order, subject to the following condition:

If the NRC staff finds that the crack-growth formula in industry report MRP-55 is unacceptable, the licensee shall revise its analysis that justifies relaxation of the First Revised Order dated February 20, 2004, within 30 days after the NRC informs the licensee of an NRC-approved crack growth formula. If the licensees revised analysis shows that the crack growth acceptance criteria are exceeded prior to the end of the then current operating cycle, this relaxation is rescinded and the licensee shall, within 72 hours3 days <br />0.429 weeks <br />0.0986 months <br />, submit to the NRC written justification for continued operation. If the revised analysis shows that the crack growth acceptance criteria are exceeded during the subsequent operating cycle, the licensee shall, within 30 days, submit the revised analysis for NRC review. If the revised analysis shows that the crack growth acceptance criteria are not exceeded during either the current operating cycle or the subsequent operating cycle, the licensee shall, within 30 days submit a letter to the NRC confirming that its analysis has been revised. Any future crack-growth analyses performed for this and future cycles for RPV head penetration nozzles must be based on an acceptable crack growth rate formula.

Principal Contributor: B. K. Singal Date: February 27, 2006

TABLE 1 IP2 RPV Head Penetrations - Minimum Coverage Requirements Below J-Groove Weld (1)

Nozzle Angle of Incidence Minimum Required UT Time (EFPY) to Penetration No. (Degrees) Coverage Below J-Groove Reach the Lowest Weld with >4 EFPY by point of the Toe of Crack Growth Evaluation the J-Groove Weld (Inches) 1 through 25 0 to 23.3 0.55 4.6 26 through 69 24.8 to 38.6 0.45 4.4 70 through 81 44.3 0.25 8.4 82 through 89 45.4 0.25 6.8 90 through 97 48.7 0.18 5 Note:

(1) Length below the lowest point at the toe of the J-Groove weld (downhill side) that has an operating stress level of 20 ksi: 0.86 inches at nozzles 1 through 25; 0.40 inches at nozzles 26 through 69; 0.32 inches at nozzles 70 through 81; 0.34 inches at nozzles 82 through 89 and 0.32 inches at nozzles 90 through 97.