JAFP-08-0131, James A. FitzPatrick Nuclear Power Plant - Submittal of the Stress Analysis Summary for the N2C-SE Weld Overlay
| ML083590338 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 12/17/2008 |
| From: | Eugene Dorman Entergy Nuclear Northeast, Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| JAFP-08-0131 | |
| Download: ML083590338 (7) | |
Text
='Entergy Entergy Nuclear Northeast Entergy Nuclear Operations, Inc.James A. Fitzpatrick NPP P.O. Box 110 Lycoming, NY 13093 Tel 315-342-3840 JAFP-08-0131 December 17, 2008 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
James A. FitzPatrick Nuclear Power Plant Docket No. 50-333 License No. DPR-59
REFERENCES:
Submittal of the Stress Analysis Summary for the N2C-SE Weld Overlay 1) Entergy Letter to NRC, JAFP-08-0102, "James A. FitzPatrick Request for Relief (RR-7 Revision 1) -Proposed Alternative to ASME Code Requirements for Weld Overlay Repairs", dated October 1, 2008 2) Entergy Letter to NRC, JAFP-08-0128, "Revised Submittal Date for the Stress Analysis Summary for the N2C-SE Weld Overlay", dated December 4, 2008
Dear Sir or Madam:
Enclosure 2 of reference 1 documented a commitment to submit to the NRC, within sixty days of the completion of Refueling Outage 18, a stress analysis summary demonstrating that the N-2C nozzle to safe-end dissimilar metal weld will perform its intended design function after weld overlay installation.
Reference 2 revised the committed submittal date to be no later than December 17, 2008.Enclosure 1 of this letter contains the summary of the stress analysis, enclosures 2, 3, and 4 contain the calculations supporting the summary.There are no new commitments made in this letter If you have any questions or require additional information, please contact Mr. Eugene Dorman, Acting Licensing Manager, at 315-349-6810.
Sincerely, Eugene Dorman Acting Licensing Manager ED/ed A, -b4l KI eA JAFP-08-0131 Page 2 of 2
Enclosures:
- 1) Stress Analysis Summary for the N2C-SE Weld Overlay 2) Structural Integrity Associates Calculation 0800769.311, Crack Growth Analysis For Recirculation Inlet Nozzle N-2C 3) Structural Integrity Associates Calculation 0800769.316, Reconciliation of Recirculation Inlet N2 Nozzle-to-Safe End Weld Overlay Repair with Nozzle Stress Report 4) Structural Integrity Associates Calculation 0800769.317, "C" Recirculation Riser N-2C-SE Weld Overlay Shrinkage Evaluation cc: Mr. Samuel J. Collins, Regional Administrator U.S. Nuclear Regulatory Commission, Region 475 Allendale Road King of Prussia, PA 19406-1415 Office of NRC Resident Inspector James A. Fitzpatrick Nuclear Power Plant P.O. Box 136 Lycoming, New York 13093 Mr. Paul Tonko, President New York State Energy Research and Development Authority 17 Columbia Circle Albany, New York 12203-6399 Mr. Bhalchandra Vaidya, Project Manager Plant Licensing Branch U.S. Nuclear Regulatory Commission Mail Stop O-8-C2A Washington, DC 20555 Mr. Charles Donaldson, Esquire Assistant Attorney General New York Department of Law 120 Broadway New York, New York 10271 Mr. Paul Eddy New York State Department of Public Services 3. Empire State Plaza Albany, New York 12223-1350 (I JAFP-08-0131 James A. Fitzpatrick Nuclear Power Station Docket No. 50-333 Enclosure 1 Stress Analysis Summary for the N2C-SE Weld Overlay Structural Integrity Associates, Inc.6855 S Havana St, Suite 350 Centennial, CO 80112 Phone: 303-792-0077 Fax: 303-792-2158 www.structint.com HLGustin@structnt.com December 10, 2008 SI Project #: 0800769 Mr. Richard Casella Entergy Nuclear Northeast James A. Fitzpatrick Nuclear Power Plant P. O. Box 110 Lycoming, NY 13093
SUBJECT:
Stress Analysis Summary for Weld Overlay of Recirculation Nozzle N-2C
References:
- 1. SI Calculation No. 0800769.316, Rev. 0, "Reconciliation of Recirculation Inlet N2 Nozzle-to-Safe End Weld Overlay Repair with Nozzle Stress Report." 2. Combustion Engineering, Inc., Report No. CENC-1 159, "Analytical Report for PASNY Reactor Vessel for Fitzpatrick Station", August 1971, SI File No. 0800769.2 10.3. SI Calculation No. 0800769.311, Rev. 1, "Crack Growth Analysis for Recirculation Inlet Nozzle N-2C." 4. ASME Boiler & Pressure Vessel Code,Section XI, 2001 Edition, with Addenda through 2003.5. SI Calculation No. 0800769.317, Rev. 1, "'C' Recirculation Riser N-2C-SE Weld Overlay Shrinkage Evaluation."
Dear Mr. Casella:
An axially oriented, surface-connected indication was found in the recirculation inlet nozzle-to-safe end, N-2C-SE, dissimilar metal weld (DMW) during the September 2008 refueling outage at J.A. Fitzpatrick Nuclear Power Plant (JAF). This indication is elliptical and is located in the weld and weld butter. A full structural weld overlay repair was applied on the affected weld. The design basis of this repair was that the underlying flaw was assumed to be entirely through the original component wall, and extended entirely around the component circumference.
For the single observed part-wall axially-oriented flaw, this design basis assumption is very conservative.
Design was performed taking guidance from ASME Section XI Code Case N-504-3, which was conditionally approved in Regulatory Guide 1.147 Revision 15, and Code Case N-740, which has been approved by ASME but has not yet been approved by NRC.Code Cases N-504-3 and N-740 include several requirements for evaluating and validating the weld overlay design. These include: Annapolis, MO Austin, TX Cerritos, CA Charlotte, NC Chattanooga, TN Oakville, Ontario, Canada San Jose, CA South Jordon, UT Stonington, CT Uniontown, OH 410-571-0861 512-533-9191 562-402-3076 704-597-5554 423-553-1180 905-829-9817 408-978-8200 801-676-0216 860-536-3982 330-899-9753 Mr. Richard Casella, Energy Nuclear Northeast December 10, 2008 SI Project #: 0800769 Page 2 of 4 la. N-504-3 (f)(1): "The axial length and end slope of the reinforcement shall be sufficient to provide for load redistribution from the pipe into the deposited weld metal and back into the pipe without violating applicable stress limits of Section III for primary local and bending stresses and secondary peak stresses." lb. N-740 (2)(b)(1): "The axial length and end slope of the weld overlay shall cover the weld and heat affected zones on each side of the weld and provide for load redistribution from the item into the overlay and back into the item without violating applicable stress limits of NB-3200." 2a. N-504-3 (g)(2)): "For repaired welds the evaluation shall consider residual stresses produced by the weld overlay with other applied loads on the system... .The evaluation shall demionstrate that the requirements of IWB-3640.
.. .are satisfied for the design life of the repair, considering potential flaw growth due to fatigue and the mechanism believed to have caused the flaw." 2b. IN-740 (2)(a): "Crack growth, including both stress corrosion and fatigue crack growth, shall be evaluated in the materials in accordance with IWB-3640." 3a. N-504-3 (g)(3): "The evaluation of other welds and components in the system shall consider potential increases in loading, including shrinkage effects, due to all overlays in the system, and shall identify and record the magnitude and location of the maximum shrinkage stress developed." 3b. N-740 (2)(b)(1): "The effects of any changes in applied loads, as a result of weld shrinkage from the entire overlay, on other items in the piping system ... shall be evaluated." The purpose of this letter and the referenced calculations is to document the results of analyses that demonstrate meeting those requirements.
- 1. Code Reconciliation/Stress Analysis Summary Structural Integrity Associates calculation 0800769.316
[1] was prepared to address requirements l a and lb above. The objective of this calculation reconciles the effects of the weld overlay repair of nozzle N2 at the J.A. Fitzpatrick Nuclear Power Generating Station to the nozzle's ASME Section III Stress Report [2].The Reference
[1] calculation evaluates the N2 recirculation inlet nozzle with and without the weld overlay repair under operating conditions using finite element analysis.Multiple analyses consistent with the nozzle Stress Report [2] were performed with and without the applied weld overlay. The sudden start transient was used for the thermal transient analyses, since this transient provides the bounding stresses and fatigue usage as documented in Reference[2]. Internal pressure and piping loads were used for the static structural analyses.
The resulting stresses were compared to Section III Code allowable stresses to reconcile the repair with Reference
[2] stress results and calculated fatigue usage.The evaluation considered primary and secondary stress intensities, fatigue usage and applicable Code Case requirements (above). This evaluation concludes that the impact of the overlay is minor and generally produces a more favorable stress condition.
In those cases where stresses SStructural Integrity Associates, Inc.
Mr. Richard Casella, Energy Nuclear Northeast Decemberl0, 2008 SI Project #: 0800769 Page 3 of 4 were higher in the post-overlay condition, the revised stresses are still within Code allowable values, and incremental fatigue usage is not significant for the balance of plant life. Therefore, the original Stress Report [2] which demonstrated Code compliance remains valid for the nozzle with weld overlay repair.2. Crack Growth Evaluation Structural Integrity Associates calculation 0800769.311
[3] was prepared to address requirement 2 above. Linear elastic fracture mechanics (LEFM) analyses were performed to calculate crack growth in the nozzle-to-safe end dissimilar metal weld (DMW) for the reactor pressure vessel (RPV) recirculation inlet nozzle N-2C at JAF. Loads considered were internal pressure and weld overlay (WOL) repair residual stresses.
Both fatigue crack growth (FCG)and Intergranular Stress Corrosion Cracking (IGSCC) are considered.
This evaluation shows that the indication found during 2008 inspection of the JAF N-2C nozzle-to-safe end weld is acceptable and meets the requirements of ASME Code,Section XI, Appendix C and Table IWB-3641-3
[4]., The WOL residual stresses provide a significant benefit to the mitigation of crack growth, especially for IGSCC growth. Taking credit for these residual stresses produces a negative stress intensity factor, resulting in no additional crack growth at this location.3. Weld Overlay Shrinkage Structural Integrity Associates calculation 0800769.317
[5] was prepared to address requirement 3 above. The objective of this calculation is to evaluate the impact of the weld overlay repair of weld N-2C-SE on other locations in the "C" recirculation riser at the J. A. Fitzpatrick Nuclear Power Plant. The shrinkage of the weld overlay on the nozzle to safe end weld produces bending on the riser piping which may produce an increased stress on the "C" recirculation riser piping.This calculation evaluates the limiting stress on the "C" recirculation riser and demonstrates that the stress is acceptable.
The stress caused by the weld shrinkage was added to the initial primary membrane plus bending stress. The shrinkage stresses resulting due to previous weld overlays applied to this recirculation system loop were also included.The resulting total stress on the "C" recirculation riser was compared to the allowable stress intensity (Sm) for the piping material.
The resulting total stress remains below the allowable stress intensity value, and therefore well below the material yield stress. Therefore, the shrinkage stress does not produce any plastic deformation and the system remains elastic. The ASME Code does not provide any allowable values or acceptance criteria for weld shrinkage stress.V Structural Integrity Associates, Inc.
Mr. Richard Casella, Energy Nuclear Northeast Decemberl0, 2008 SI Project #: 0800769 Page 4 of 4 The conservatively calculated maximum stress due to weld overlay shrinkage is approximately an order of magnitude lower than the primary stress intensity at the limiting location.
Weld overlay shrinkage stress is a steady state secondary stress and is not limited by the Code.Furthermore, the displacement of the "C" riser due to weld overlay shrinkage is toward the reactor vessel. When the vessel expands upon heat-up, any stress due to weld overlay shrinkage will tend to self relieve.Should future flaws be identified at other locations in the recirculation system, shrinkage stresses will be included in any flaw growth analyses performed to demonstrate acceptability of flaws without repair.Conclusion The above referenced calculations demonstrate that the post overlay evaluation requirements of Code Case N-504-3 and N-740 have been met for the as-applied weld overlay repair to the N2C nozzle to safe end weld at J. A. Fitzpatrick.
Very truly yours, Hal L. Gustin Associate Reviewed by: Terry J. Herrmann Associate cc: M. Alvi E. Dorman T. Moskalyk SI File No. 0800769.102Structural Integrity Associates, Inc.