ML070600212
| ML070600212 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 02/12/2007 |
| From: | General Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| eDRF 0000-0061-6166, eDRF 0000-0064-4903 GE-NE-0000-0061-6180-R2-NP | |
| Download: ML070600212 (44) | |
Text
ATTACHMENT (3)
SHROUD REPAIR REPLACEMENT UPPER SUPPORT STRESS ANALYSIS REPORT Non - Proprietary Version Nine Mile Point Nuclear Station, LLC February 12, 2007
GE Energy - Nuclear General Electric Company Non-Proprietary Version 6705 Vallecitos Road Sunol, CA 94586 GE-NE-0000-0061-6180-R2-NP eDRF Section 0000-0064-4903 eDRF 0000-0061-6166 Class I February 2007 Nine Mile Point 1 Nuclear Plant Shroud Repair Replacement Upper Support Stress Analysis Report
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GE-NE-OOOO-0061-6180-R2-NP NON-PROPRIETARY VERSION IMPORTANT NOTICE REGARDING THE CONTENTS OF THIS REPORT Please Read Carefully A. Disclaimer The only undertakings of the General Electric Company (GE) respecting information in this document are contained in the contract between the company receiving this document and GE. Nothing contained in this document shall be construed as changing the applicable contract. The use of this information by anyone other than a customer authorized by GE to have this document, or for any purpose other than that for which it is intended, is not authorized. With respect to any unauthorized use, GE makes no representation or warranty, and assumes no liability as to the completeness, accuracy or usefulness of the information contained in this document, or that its use may not infringe privately owned rights B. Non-Proprietary Notice This is a non-proprietary version of the GE-NE-0000-0061-6180-R2-P, which has the proprietary information removed. Portions of the document that have been removed are indicated by an open and closed double brackets as shown here [
I].
ii
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION REVISION CONTROL SHEET Revision Date Description Rev. 0 (Draft) December 6, 2006 Draft Report for Customer Review Rev. 1 (Draft) February 02, 2007 Revised to include customer comment resolutions Rev. 1 February 08, 2007 Issued - Incorporates all Customer Comments Issued - Revised Table 4-1 to reflect the material change in the top support pins and spacer bolt Rev. 2 February 09, 2007 Administrative changes to create proprietary/non-proprietary versions consistent with 10CFR2.390.
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GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION TABLE OF CONTENTS Section Page 1.0 In tro d u c tio n...................................................................................................................................................
1 2.0 S c o p e................................................................................................................................................................
1 3.0 Replacement Hardware Design Features.................................................................................
2 4.0 Replacement Hardware Materials................................................................................................
3 5.0 Stru ctu ra l A n a lysis......................................................................................................................................
3 5.1 Design Basis Loads and Load Combinations....................................................................
4 5.2 Q ua lificatio n C riteria............................................................................................................................
4 5.3 A na lysis M etho d s..................................................................................................................................
6 6.0 A n a lysis R esu lts...........................................................................................................................................
9 6.1 Replacement Upper Support and Associated Assembly Components..................
9 6.2 Effect of Replacement Upper Support on Reactor Pressure Vessel.....................
13 6.3 Effect of Widening the EDM Pocket in the Shroud Head............................................
13 6.4 Effect of Replacement Upper Support on Flow-induced Vibration.......................
13 6.5 Effect of Replacement Upper Support on Shroud Deflections................................
14 7.0 C o n clusio n...................................................................................................................................................
14 8.0 R efe re n ce s..................................................................................................................................................
15 iv
GE-NE-O000-0061-6180-R2-NP NON-PROPRIETARY VERSION LIST OF FIGURES Figure 1. Replacement Upper Support and Tie Rod Nut....................................................................
17 Figure 2. Comparison of Physical Details in the Old and New Designs of Upper Support......... 18 Figure 3. Replacement Upper Support - Finite Element Model........................................................
19 Figure 4. Upper Support FEM Stress Linearization Paths.....................................................................
20 Figure 5. Normal (sustained) Operation Load, Upper Support, Top Portion, Maximum P rin c ip a l S tre ss........................................................................................................................................
2 1 Figure 6. Normal (sustained) Operation Load, Upper Support, Bottom Portion, Maximum P rin c ip a l Stre ss........................................................................................................................................
2 2 Figure 7. Normal (Sustained) Operating Condition, Replacement Tie Rod Nut Threads -
M axim um Principal Stress..................................................................................................................
23 Figure 8. Normal (Sustained) Operating Condition, Replacement Tie Rod Nut Threads -
M axim um Principal Stra in..................................................................................................................
24 Figure 9. Normal Operation, Upper Support, Top Portion, Stress Intensity................................
25 Figure 10. Normal Operation, Linearized Stress Intensity, Top Path...........................................
26 Figure 11. Normal Operation Load, Upper Support, Bottom Portion, Stress Intensity........... 27 Figure 12. Normal Operation Load, Linearized Stress Intensity, Bottom Path..........................
28 Figure 13, Faulted Load, Upper Support, Top Portion, Stress Intensity........................................
29 Figure 14. Faulted Load, Linearized Stress Intensity, Top Path.....................
30 Figure 15. Faulted Load, Upper Support, Bottom Portion, Stress Intensity.................................
31 Figure 16. Faulted Load, Linearized Stress Intensity, Bottom Path...............................................
32 V
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION LIST OF TABLES Table 4-1. Mechanical Properties for the Component Materials........................................................
3 Table 5-1. Tie Rod Lo ads (lbs.)..................................................................................................................................
4 Table 5-2. ASM E Code Stress Lim its.......................................................................................................................
5 Table 5-3. Associated Replacement Upper Support Components..................................................
8 Table 6-1. Maximum Tensile Principal Stress in X-750 Components Due to Sustained Normal Condition Loads for IGSCC Evaluation....................................................................
9 Table 6-2. Stress Intensities for the Upper Support - ASME Code Compliance........................
10 Table 6-3. Stress Intensities for Other Components in the Replacement Assembly - ASME C od e C o m p lia nce...................................................................................................................................
12 Table 6-4. Fatigue Usage Factors.......................................................................................................................
13 vi
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION 1.0 Introduction GE Energy, Nuclear (GE) has provided core shroud repairs using tie rods to several BWR plants including Nine Mile Point 1 Nuclear Plant (NMP1). In the spring of 2006, during an in-vessel visual inspection (IVVI) at a domestic plant, indications were observed in the shroud repair tie rod upper supports made of Alloy X-750 at two of the four shroud tie rod repair locations. The indications emanated from the close vicinity of the sharp corner between the horizontal and vertical legs of the upper support and ran outwardly, at approximately 300 to the horizontal. The cracking mechanism was determined to be Inter-granular stress corrosion cracking (IGSCC), confirmed by a metallurgical examination of a section of the upper support that included the cracked section. Alloy X-750 material is susceptible to IGSCC if subjected to sustained, large peak stress conditions.
GE opened an internal evaluation under 10CFR Part 21 (Reference 1) to determine if the potential for IGSCC exists in the Alloy X-750 shroud repair components (in the tie rod vertical load path) of other BWR shroud repairs designed by GE. GE used the criterion provided in the BWR Vessels & Internals Project (BWRVIP-84) for the IGSCC susceptibility assessment of the X-750 components. Based on this evaluation, GE determined that the peak stress in the tie rod upper support for NMP1 exceeded the BWRVIP-84 IGSCC criterion.
The follow-on evaluation (Reference 2) was performed to assess if a postulated cracking in the NMP1 shroud repair upper support could lead to a substantial safety hazard (SSH) during operation till the end of the current operating cycle.
Based on this evaluation GE determined that a SSH does not exist for the current operating cycle. However, as a long-term solution to mitigate the potential for IGSCC, it was decided that the upper supports of the shroud repair be replaced with a new replacement hardware that is more robust from the standpoint of IGSCC.
2.0 Scope The scope of this report is to address the structural integrity of the components in the shroud repair tie rod assembly that are being replaced. These components include the upper support, the tie rod nut, and the various components in the upper support assembly. These components are listed in Reference 3, with the respective drawing numbers.
The stress analysis summarized in this report demonstrates that the shroud repair replacement hardware listed in Reference 3 satisfy the IGSCC and ASME Code requirements of the design specification data sheet (Reference 4).
The design features of the shroud repair replacement hardware, criteria for qualification, analysis approach, results, and conclusions are presented in this report.
Page 1 of 32
GE-NE-OOOO-0061-6180-R2-NP NON-PROPRIETARY VERSION 3.o Replacement Hardware Design Features The geometry of the replacement hardware (Upper supports, their associated components and the tie rod nut) is shown in Reference 3 drawings.
The key components of the replacement hardware are shown in Figure 1.
The major load bearing Alloy X-750 components are the upper supports, the support block and the tie rod nut. The newly designed components incorporate features that improve their ability to resist IGSCC. These features are identified below as well as shown in Figure 2.
Generous fillet radius at the corner of the upper support. The original upper support design had no stress relief feature at the upper corner resulting in large peak stress. In the replacement upper support, a generous semi-elliptical stress-relief has been incorporated.
This provision reduces the peak stress.
Increased width of the upper support. The width of the vertical leg of the upper support (i.e.,
in the radial direction) is increased from the original value of 2.7 inch to 4.2 inch to compensate for the sacrificial reduction in the cross section due to the semi-elliptical stress relief.
Increased thickness of the support. The thickness of the replacement upper supports (Figure
- 2) is increased from the original size of 2.0 in. to 2.75 in., in the tangential direction. This increase was required to meet the new IGSCC mitigation criterion ((
))
Sharp edqes eliminated. A radius of 0.38 inch is specified at the bottom, U-grooved section of the upper supports for stress relief at the corners Figure 2.
Generous root radius for the Tie Rod Nut threads. A generous root radius ((
is provided at the tie rod nut ACME thread roots.
Page 2 of 32
0 GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION 4.0 Replacement Hardware Materials The materials used in the shroud repair replacement hardware and their mechanical properties are provided below.
Table 4-1. Mechanical Properties for the Component Materials Component Material Properties @ 550"F (1)
(Reference 8)
Replacement Upper Support Tie Rod Nut Retainer Pin Spring Retainer Pin Sm= 53,300 psi LatchASTM B637 UNS Latch N07750 Type 3 Sy = 92,800 psi Soc Hd Cap Screw (Alloy X-750)
Su = 160,000 psi Stabilizer Bolt E = 28.85x10 6 psi Upper Support Block Top Support Pins Spacer Bolt Sm = 17,500 psi Dowel Pins SA 240, Type 316 Sy = 19,450 psi Or SA 479 Type 316 Su = 71,800 psi 121 (2)_
1 E = 25.55x10 6 psi (1) Sm = Allowable Stress Intensity, Sy = Yield Strength, Su = Ultimate Strength, E = Young's Modulus (2) The tie rod material used as part of the replacement tie rod nut analysis is SS316 5.0 Structural Analysis Structural analysis was performed for the replacement upper support and its components.
Details of the analysis models, loads, and loading are detailed in the following subsections.
The results of these analyses are presented in Section 6.0.
o Upper support in engagement with the shroud flange was analyzed using finite element method.
o Other associated components in the replacement upper support assembly were evaluated using hand calculations.
" Tie Rod Replacement Nut in engagement with existing tie rod, was analyzed using finite element method.
In addition, the following were also addressed.
O Effect of replacement upper support on seismic loads o Effect of replacement upper support on Reactor Pressure Vessel.
Page 3 of 32
GE-NE-OOOO-0061-6180-R2-NP
¶0 NON-PROPRIETARY VERSION O Effect of the widening the existing EDM pocket in the shroud head flange.
o Effect of replacement upper support on flow-induced vibration 5.1 Design Basis Loads and Load Combinations The applicable loads and load combinations consistent with the original design basis of the shroud repair were used. The effects of the introduction of GEl1 fuel with Debris Filter (Reference 6) were also considered. The bounding current design basis loads are as below.
Table 5-1. Tie Rod Loads (lbs.)
Normal U
Upset Cond.
Upset Cond.
Emergency Faulted (Sustained (Seismic)
(Thermal)
Cond.
Cond.
Loadsl S
5.1.1 Impact of Replacement Upper Support on Tie Rod Assembly Stiffness The replacement upper support stiffness increased compared to the original upper support.
The stiffness of the existing lower support assembly however, was recomputed to remove conservatism based on a finite element model, resulting in a reduction in stiffness compared to the original analysis. ((
1] Also, consequently the original tie rod loads remain bounding and valid.
5.1.2 Impact of Replacement Upper Support on Seismic Loads The very minimal change in the tie rod stiffness has practically no effect on the overall dynamic characteristics of the vessel and internals primary structure model. Hence, it is deemed that the seismic load remains unchanged.
5.2 Qualification Criteria 5.2.1 IGSCC Criteria Per the design specification data sheet (Reference 4), the maximum principal tensile stress (Pm + Pb + Q + F) in the sustained normal operating condition is compared to the IGSCC criterion ((
1] This criterion is more restrictive than the BWRVIP-84 criterion of O.8Sy.
Page 4 of 32
0 GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION 5.2.2 ASME Code Allowable Stress Limits Per the design specification data sheet (Reference 4), the Normal (Level A), Upset (Level B),
Emergency (Level C), and Faulted (Level D) condition allowable stress limits used in this stress analysis are in accordance with the ASME Code (Reference 8). The generic allowable stress limits of ASME Code are summarized in Table 5-2.
Table 5-2. ASME Code Stress Limits Service Level Stress Category.
Allowable Stress Limit Components Other Than Threaded Fasteners (Ref. 8, NG-3220)
Pm Sm Pm + Pb 1.5 Sm Pm+ Pb + Q 3.0 Sm Levels A & B Shear Stress 0.6 Sm Bearing Stress Sy 1.5 Sy (away from free edge) 2: Fatigue Usage 1.0 Normal Sustained Ssand Pmn + Pb + Q + F 0.6Sy Condition -
IGSCC Pm 1.5 Sm Pm + Pb 2.25 Sm Level C Shear Stress 0.9 Sm Bearing Stress 1.5 Sy 2.25 Sy (away from free edge)
PM (N 2.0 Sm (M Original design basis values used Pm + Pb
(*)3.0 Sm conservatively.
Level D Shear Stress 1.2 Sm Bearing Stress 2.0 Sy 3.0 Sy (away from free edge)
Page 5 of 32
0 GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION Service Level
_ Stress Category Threaded Structural Fasteners (Ref. 8, NG-3230)
Allowable Stress Limit Pm (Mechanical Loads)
Sm Levels A & B Pm (Installation Torque)
Min. (1.08 Sy, 0.8 SJ) at Installation Temperature Pm+ Qm Min. (0.9 Sy, 2/3 S.)
Pm + Pb + Qm+ Qb Min. (1.2 Sy, 8/9 S.)
Shear Stress (Primary) 0.6 Sm Threads Shear Stress(Primary+
06S Secondary) 0.6_S_
Under Bolt Head Bearing Stress 2.7 Sy Shank, Threads I Z Fatigue Usage 1.0 Same as for non-threaded components Pmo. and Pm+Pb Level C Same as Level A/B limits for threaded components (If Su >
100 ksi)
Shear Stress Same as for Level A/B limits for threaded components Pm Smaller of 2. 4Sm or 0.7 Su 2 Sm (If Su > 100 ksi)
Level D Smaller of 3.6 Sm or 1.05 Su Pmn + Pb 3Sm (If Su > 100 ksi)
Shear Stress Smaller of 0.42 Suand 0.6 Sy 5.3 Analysis Methods 5.3.1 Replacement Upper Support - Finite Element Analysis A finite element analysis (FEA) was performed for the replacement X-750 upper support using the ANSYS computer program (Reference 9). The upper support engages the shroud flange in bearing and is located within the EDM pocket in the shroud head. Only one of the two parallel upper support brackets is modeled (Figure 3) due to symmetry about vertical plane. The model was made up of SOLID 45 (8-node brick) elements. The final mesh size at the peak stress area was chosen based on a mesh sensitivity study performed to ensure that the element size and shape appropriately captures the peak stresses at the fillet radius/discontinuity. The boundary conditions and the loads as shown below were applied to the finite element model.
Page 6 of 32
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION Boundary Conditions:
" The bearing interface of the horizontal arm of the upper support with the shroud flange was modeled using contact elements. ((
))
" The nominal gap that exists in the shroud head EDM pocket above the top surface of the upper support was modeled [R
))
Use of original value of the gap is appropriate since the EDM operation for the introduction of the new replacement hardware does not change the height of the pocket.
" At the bottom of the upper support, radial and tangential translational boundary conditions were also included.
Load Application:
The upper support load (50% of the tie rod loads shown in Table 5-1, on one upper support bracket) was applied in the vertical (downward) direction at the bottom ledge of the upper support, corresponding to the seating area of the "Support" (Drawing 124D2933, Rev 0). The normal condition sustained load was used for the check against the IGSCC criterion. The Normal/Upset, Emergency, and Faulted condition loads were used for the ASME Code stress evaluation.
5.3.2 Replacement Tie Rod Nut FEA was performed of the replacement tie rod nut with ACME threads in engagement with the existing tie rod threads.
This analysis was performed using the ANSYS computer program (Reference 9). ((
1]
The axisymmetric FEA model of the Tie Rod Nut in engagement with the existing Tie Rod threads was made up of PLANE 82 elements (8-node axisymmetric element with mid side nodes). The final mesh size at the peak stress area was chosen based on a mesh sensitivity study performed to ensure that the element size and shape realistically capture the peak stresses at the root radius. The boundary conditions as described below, and the loads in Table 5-1 were applied appropriately to the finite element model.
Boundary Conditions:
- In order to represent the engagement of the internal and external threads, contact elements were provided at the interface of the threads of the tie rod nut and the tie rod, including contact friction.
Friction exists between the tie rod nut and the support block at their bearing interface. The bearing surface between the tie rod nut and the support block is modeled using vertical restraint across the bearing surface and a radial restraint at one node.
Page 7 of 32
UGE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION Material Property:
1[
11 The yield stress values used were 18,800 psi for the SS 316 tie rod and 92,800 psi for the X-750 tie rod nut.
Load Application and Analysis:
The normal condition sustained load specified in Table 5-1 was used for the check against the IGSCC criterion, and evaluated based on the elastic-plastic analysis.
The Normal/Upset, Emergency, and Faulted condition loads specified in Table 5-1 were used for the ASME Code stress evaluation, and evaluated based on classical elastic analysis methods.
5.3.3 Other Associated Replacement Upper Support Components The following associated replacement upper support components were evaluated for their susceptibility to IGSCC and ASME Code stresses by hand calculations. The results of the calculations are presented in Section 6.
Table 5-3. Associated Replacement Upper Support Components Component Name Drawing Number Dowel Pins 147C1073, Rev.0 Pin Retainer 252C5556, Rev.0 Retainer Pin 252C5551, Rev.0 Latch 252C5558, Rev.0 Top Support Pin 252C5563, Rev.0 Spacer Bolt 252C5564, Rev.0 Socket Head Cap Screw 252C5565, Rev.0 Stabilizer Bolt 252C5586, Rev.0 Support 124D2933, Rev.0 Page 8 of 32
£(I GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION 6.0 Analysis Results This section documents the stress results for the Replacement Upper Support and the associated components of the replacement assembly. It is noted that the use of allowable stresses based on certified material test reports (CMTRs) will result in higher stress margins than reported in this report.
6.1 Replacement Upper Support and Associated Assembly Components The replacement hardware components (upper support, tie rod nut and other associated upper support components) were evaluated for their susceptibility to IGSCC and ASME Code requirements, consistent with the acceptance criteria of the Reference 4 Design Specification data sheet as in Table 5-2.
The maximum Principal tensile stress (Pm + Pb + Q + F) for all Alloy X-750 components for the replacement upper support assembly and the replacement tie rod nut subjected to the normal sustained loading conditions satisfy the 0.6Sy requirement for IGSCC.
The calculated Pm and (Pm+Pb) stresses for all components meet the ASME Code (Reference
- 8) allowable stress limits for all operating levels.
The fatigue usage factor for the replacement components meet the 40 year component life specified in Reference 4.
The results of the structural integrity evaluation are provided in Table 6-1 through Table 6-4 below.
6.1.1 Results of IGSCC Evaluation The components in the Table 6-1 are made of X-750 material, and were evaluated for IGSCC criterion ((
1] under sustained loading conditions. Table 6-1 gives the maximum stress in comparison with the allowable. All components are within the IGSCC criterion.
Table 6-1. Maximum Tensile Principal Stress in X-750 Components Due to Sustained Normal Condition Loads for IGSCC Evaluation Max Tensile Principal Sy, psi SR = SI/Sy Component Stress S1, psi (Pm+Pb+Q+F)
Page 9 of 32
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION Component Max Tensile Principal Stress S1, psi (Pm+Pb+Q+F)
Sy, psi SR = Sl/Sy Tie Rod Nut at Root of the threads 92,800 Retainer Pin Spring 92,800 Retainer Pin 92,800 Soc Head Cap Screw 92,800 Stabilizer Bolt 92,800 Support 92,800 Spacer Bolt 92,800 Top Support Pin 1]
92,800 6.1.2 Results of Evaluation for ASME Code Allowable Stresses The Pm and (Pm+Pb) stress intensities for all the replacement components were evaluated at the various operating levels, using the loads in Table 5-1. The stress intensities satisfy the code allowable stress for the respective materials. The stress results are provided in Table 6-2 and Table 6-3 below.
Table 6-2. Stress Intensities for the Upper Support - ASME Code Compliance Component Name Governing Stress Intensity (psi)
(Material)S Level Type Max.
A Stress Strss ype Strss Allow. Stress Rao Stress Ratio placement Upper Pm
^rt(Y7O A+ tNormal1 Rel
,I
. W I.J Ifj -lU u fl upper end, at the large radius Pm+Pb Upset-Pm +Pb +Q thermal Upset Pmn Seismic Pm +Pb Pm Emergency Pm+Pb Faulted Pm o
Page 10 of 32
GE-NE-OOOO-0061-6180-R2-NP NON-PROPRIETARY VERSION Component Name (Material)
Level N
Normca Governing Stress Intensity (psi) max.
Stress Stre i Allow. Stress
- e Stress iRatio Stress Typ Pm+Pb 1Pm
__L Pm+Pb Replacement Upper Support (X-750), At the Lower end, at the ledge for 'Support (Drg 124D2911i Upset-.P+P+
Thermal Pm b+
Upset Pmn Seismic Pmn+Pb Pm Emergency Pm+Pb Pm Faulted Pm+Pb Normal Bearing Upset-Bearing Stress at the Thermal Bearing interface between Tie Upset Rod Nut and 'Support' Seismic block Emergency Bearing Faulted Bearing Normal Bearing Bearing Stress at the Upset-Bearing interface between the Thermal lower ledge of the Upper Upset Support and the 'Support' Seismic Bearing Block Emergency Bearing Faulted Bearing
]
Page 11 of 32
0 GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION Table 6-3. Stress Intensities for Other Components in the Replacement Assembly - ASME Code Compliance F
Component Name (Material)
Level.
Stress Type Governing Stress Intensity (psi)
Max.
Allow. Stress SStress Stress Ratio Pm Normal Shear Tie Rod NutThreads Upset Pm Seismic Shear Upset Pm Thermal Shear Pm Emergency Shear Pm Faulted Shear Normal Pm+Pb Upset-Pm+Pb thermal Upset-Pm+Pb Seismic Emergency Pm+Pb Support Block (X-750)
Faulted Other Pm+Pb Associated Components I]
Dowell Pins (SS316)
N Shear (-)
Pin Retainer Spring N
Pm+Pb (X-750)
RetainerPin (X-750)
N Shear (t)
Latch (X-750)
N/U Pm+Pb Top Support Pin (X-750)
N Pm Spacer Bolt (X-750)
N Pm Socket Hd Cap Screw (X-N Pm 750)
Stabilizer Bolt (X-750)
N Shear (-)
Page 12 of 32
GE-NE-OOOO-0061-6180-R2-NP NON-PROPRIETARY VERSION 6.1.3 Results of Fatigue Evaluation Fatigue usage factor was evaluated for in accordance with the provisions of the Code. The following are the results of the fatigue usage evaluation.
Table 6-4. Fatigue Usage Factors No Component CUF 1
Tie Rod Nut 2
Upper Support 3
Support Block 4
Pin Retainer Spring 5
Latch
]
6.2 Effect of Replacement Upper Support on Reactor Pressure Vessel As a result of the upper support replacement, there is no change in the tie rod loads.
Consequently, there is no impact on the reactor pressure vessel due to this replacement.
6.3 Effect of Widening the EDM Pocket in the Shroud Head In the Reference 5b analysis, an assessment was made for the (Pm+Pb) stress in the shroud head flange at the location of the EDM pocket. The limiting condition was determined to be the lifting operation with four slings attached to the shroud head.
In order to evaluate the effect of widening the EDM pocket, as an approximation, it was conservatively assumed that the height of the shroud head flange is reduced over the entire circumference. [(
)) Thus there is no adverse structural effect of widening the EDM.
pocket.
6.4 Effect of Replacement Upper Support on Flow-induced Vibration Page 13 of 32
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION
]1 The flexural stiffness of the replacement upper support is larger than that of the original design and therefore the overall flexural stiffness of the assembly in the cross flow direction will be larger than the original. Based on a parametric assessment, taking into consideration the change in the mass and section properties of the upper support assembly, it was determined that the replacement upper support would result in a fundamental frequency equal to or greater than that of the original design. Therefore, the original conclusion regarding the adequacy against vortex shedding remains valid.
6.5 Effect of Replacement Upper Support on Shroud Deflections The seismic and horizontal loads are not affected by the upper support modification. Therefore, the calculated shroud horizontal deflections remain unchanged from the original tie rod design. The shroud weld vertical deflections are governed by the tie rod vertical loads. The revised emergency and faulted tie rod vertical loads considered the effects of the introduction of GEl1 fuel with Debris Filters which resulted in a small increase in the reactor internal pressure differences (RIPDs). The RIPD increase results in a small increase in the tie rod emergency and faulted tie rod loads as compared to the original tie rod loads R[
)) Since there is no increase in the shroud emergency/faulted vertical deflections, there is no additional strain imposed on shroud attached core spray piping as compared to the original analysis. The revised tie rod stiffness
[1 1] slightly reduces the weld separation under upset pressure conditions and assures that no separation occurs under normal operating pressure conditions.
7.0 Conclusion Based on the structural evaluation documented in the preceding sections, the shroud repair replacement hardware (upper support, their associated components and tie rod nut) as depicted in the referenced drawings are structurally qualified consistent with the requirements of the design specification data sheet for IGSCC and the ASMIE Code.
Page 14 of 32
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION 8.0 References
- 1. SCO6-07, 10CFR Part 21 Safety Communication, Core Shroud Repair Tie Rod Upper Support Cracking, dated May 12, 2006.
- 2. SC06-13, 10CFR Part 21 Safety Communication, Update to Core Shroud Repair Tie Rod Upper Support Cracking, dated October 9, 2006.
- 3. Replacement Hardware Drawings and Parts Lists:
105E4340, Rev. 0 Reactor 124D2897, Rev.0 Tie Rod Nut 124D2911, Rev. 0 Upper Support 124D2896, Rev.0 Upper Support 147C1073, Rev.0 Dowell Pins 252C5556, Rev.0 Pin Retainer 252C5551, Rev.O Retainer Pin 252C5558, Rev.0 Latch 252C5563, Rev.0 Top Support Pin 252C5564, Rev.O Spacer Bolt 252C5565, Rev.0 Soc Hd Cap Screw 252C5586, Rev.0 Stabilizer Bolt 124D2933, Rev.0 Support
- 4. Design Specification:
a) DS25A5583AA, Nine Mile Point 1, Shroud Repair Modification, Design Specification Data Sheet.
b) 25A5583, Nile Mile Point Shroud Repair Hardware, Design Specification, (Base Specification)
- 5. GE-NE-B13-01739-04, "Nine Mile Point Unit 1 - Shroud Repair Hardware Stress Analysis," Revision 0, January, 1995, DRF B13-01739 including:
a) Supplement 1, February 24, 1995 b) Supplement 2, April, 1995
- 6. GENE-0000-0007-7054-2, Rev 0, Nine Mile Point 1, Reactor Internals Structural Integrity Evaluation Phase-i, Due to the Incremental Load Change As a Result of Fuel Debris Filter Addition, March 2003.
- 7. GE-NE-0000-0023-1725-1, Revision 0, Nine Mile Point Unit 1 Reactor Internals Structural Integrity Evaluation in Support of GEll Fuel Debris Filter Addition (Phase 2).
Page 1S of 32
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION
- 8.
ASME Boiler and Pressure Vessel Code, Section Ill, Division I, Nuclear Power Plant Components.
a) Subsection NG, Core Support Structure, 2001 Edition through and Including the 2003 Addenda.
b) Code Case N-60-5, Material for Core Support Structures,Section III, Division 1.
c) Appendices
- 9.
ANSYS Finite Element Computer Code, Version 10.0, ANSYS Incorporated, 2004.
Page 16 of 32
GE-NE-O000-0061-6180-R2-NP NON-PROPRIETARY VERSION Tie Rod Nut Figure 1. Replacement Upper Support and Tie Rod Nut
GE-NE-O000-0061-6180-R2-NP NON-PROPRIETARY VERSION Figure 2. Comparison of Physical Details in the Old and New Designs of Upper Support
((
J]
0 GE-NE-OOOO-0061-6180-R2-NP
.NON-PROPRIETARY VERSION
[1
))
Figure 3. Replacement Upper Support - Finite Element Model Page 19 of 32
GE-NE-OOOO-0061-6180-R2-NP NON-PROPRIETARY VERSION 11 Figure 4. Upper Support FEM Stress Linearization Paths Page 20 of 32
0 GE-NE-O000-061-6180-R2-NP NON-PROPRIETARY VERSION I]
Figure 5. Normal (sustained) Operation Load, Upper Support, Top Portion, Maximum Principal Stress Page 21 of 32
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))
Figure 6. Normal (sustained) Operation Load, Upper Support, Bottom Portion, Maximum Principal Stress Page 22 of 32
0 GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION Figure 7. Normal (Sustained) Operating Condition, Replacement Tie Rod Nut Threads -
Maximum Principal Stress Page 23 of 32
GE-NE-OOOO-0061-6180-R2-NP NON-PROPRIETARY VERSION Figure 8. Normal (Sustained) Operating Condition, Replacement Tie Rod Nut Threads -
Maximum Principal Strain Page 24 of 32
GE-NE-OOOO-0061-6180-R2-NP NON-PROPRIETARY VERSION F]
Figure 9. Normal Operation, Upper Support, Top Portion, Stress Intensity Page 25 of 32
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[1 1]
Figure 10. Normal Operation, Linearized Stress Intensity, Top Path Page 26 of 32
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[I Figure 11. Normal Operation Load, Upper Support, Bottom Portion, Stress Intensity Page 27 of 32
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Figure 12. Normal Operation Load, Linearized Stress Intensity, Bottom Path Page 28 of 32
0 GE-NE-OOOO-0061-6180-R2-NP NON-PROPRIETARY VERSION 11 Figure 13. Faulted Load, Upper Support, Top Portion, Stress Intensity Page 29 of 32
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Figure 14. Faulted Load, Linearized Stress Intensity, Top Path Page 30 of 32
GE-NE-0000-0061-6180-R2-NP NON-PROPRIETARY VERSION 11 Fr Figure 15. Faulted Load, Upper Support, Bottom Portion, Stress Intensity Page 31 of 32
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Figure 16. Faulted Load, Linearized Stress Intensity, Bottom Path Page 32 of 32
ATTACHMENT (4)
AFFIDAVIT BY THE GENERAL ELECTRIC COMPANY Nine Mile Point Nuclear Station, LLC February 12, 2007
General Electric Company AFFIDAVIT I, George B. Stramback, state as follows:
(1) I am Manager, Regulatory Services, General Electric Company ("GE") and have been delegated the function of reviewing the information described in paragraph (2) which is sought to be withheld, and have been authorized to apply for its withholding.
(2) The information sought to be withheld is contained in the GE proprietary report GE-NE-0000-0061-6180-R2-P, Nine Mile Point 1 Nuclear Plant Shroud Repair Replacement Upper Support Stress Analysis Report, Class III (GE Proprietary Information), dated February 2007. The proprietary information is delineated by a double underline inside double square brackets. Figures and large equation objects are identified with double square brackets before and after the object. In each case, the superscript notation( 3) refers to Paragraph (3) of this affidavit, which provides the basis for the proprietary determination.
(3) In making this application for withholding of proprietary information of which it is the owner, GE relies upon the exemption from disclosure set forth in the Freedom of Information Act ("FOIA"), 5 USC Sec. 552(b)(4), and the Trade Secrets Act, 18 USC Sec. 1905, and NRC regulations 10 CFR 9.17(a)(4), and 2.390(a)(4) for "trade secrets" (Exemption 4). The material for which exemption from disclosure is here sought also qualify under the narrower definition of "trade secret", within the meanings assigned to those terms for purposes of FOIA Exemption 4 in, respectively, Critical Mass Energy Project v. Nuclear Regulatory Commission, 975F2d871 (DC Cir. 1992), and Public Citizen Health Research Group v. FDA 704F2d1280 (DC Cir. 1983).
(4)
Some examples of categories of information which fit into the definition of proprietary information are:
- a.
Information that discloses a process, method, or apparatus, including supporting data and analyses, where prevention of its use by General Electric's competitors without license from General Electric constitutes a competitive economic advantage over other companies;
- b.
Information which, if used by a competitor, would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product;
- c.
Information which reveals aspects of past, present, or future General Electric customer-funded development plans and programs, resulting in potential products to General Electric; GBS-07-0 1 -af NMPt-1 Shroud Repair Replacement Stress Rpt GE-NE-0061-6180-R2-P.doc Affidavit Page I
- d.
Information which discloses patentable subject matter for which it may be desirable to obtain patent protection.
The information sought to be withheld is considered to be proprietary for the reasons set forth in paragraphs (4)a., and (4)b, above.
(5) To address 10 CFR 2.390 (b) (4), the information sought to be withheld is being submitted to NRC in confidence. The information is of a sort customarily held in confidence by GE, and is in fact so held. The information sought to be withheld has, to the best of my knowledge and belief, consistently been held in confidence by GE, no public disclosure has been made, and it is not available in public sources. All disclosures to third parties including any required transmittals to NRC, have been made, or must be made, pursuant to regulatory provisions or proprietary agreements which provide for maintenance of the information in confidence.
Its initial designation as proprietary information, and the subsequent steps taken to prevent its unauthorized disclosure, are as set forth in paragraphs (6) and (7) following.
(6) Initial approval of proprietary treatment of a document is made by the manager of the originating component, the person most likely to be acquainted with the value and sensitivity of the information in relation to industry knowledge. Access to such documents within GE is limited on a "need to know" basis.
(7) The procedure for approval of external release of such a document typically requires review by the staff manager, project manager, principal scientist or other equivalent authority, by the manager of the cognizant marketing function (or his delegate), and by the Legal Operation, for technical content, competitive effect, and determination of the accuracy of the proprietary designation. Disclosures outside GE are limited to regulatory bodies, customers, and potential customers, and their agents, suppliers, and licensees, and others with a legitimate need for the information, and then only in accordance with appropriate regulatory provisions or proprietary agreements.
(8) The information identified in paragraph (2), above, is classified as proprietary because it contains detailed results of analytical models, methods and processes, including computer codes for a hardware repair replacement design modification, for the stabilizers for the shroud horizontal welds, installed in a reactor to resolve the reactor pressure vessel core shroud weld cracking concern. The development and approval of this hardware repair replacement design modification utilized systems, components, and models and computer codes that were developed at a significant cost to GE, on the order of several hundred thousand dollars..
The development of the evaluation process along with the interpretation and application of the analytical results is derived from the extensive experience database that constitutes a major GE asset.
GBS-07-01-af NMIPt-1 Shroud Repair Replacement Stress Rpt GE-NE-0061-6180-RO-P.doc Affidavit Page 2
(9) Public disclosure of the information sought to be withheld is likely to cause substantial harm to GE's competitive position and foreclose or reduce the availability of profit-making opportunities.
The information is part of GE's comprehensive BWR safety and technology base, and its commercial value extends beyond the original development cost. The value of the technology base goes beyond the extensive physical database and analytical methodology and includes development of the expertise to determine and apply the appropriate evaluation process. In addition, the technology base includes the value derived from providing analyses done with NRC-approved methods.
The research, development, engineering, analytical and NRC review costs comprise a substantial investment of time and money by GE.
The precise value of the expertise to devise an evaluation process and apply the correct analytical methodology is difficult to quantify, but it clearly is substantial.
GE's competitive advantage will be lost if its competitors are able to use the results of the GE experience to normalize or verify their own process or if they are able to claim an equivalent understanding by demonstrating that they can arrive at the same or similar conclusions.
The value of this information to GE would be lost if the information were disclosed to the public.
Making such information available to competitors without their having been required to undertake a similar expenditure of resources would unfairly provide competitors with a windfall, and deprive GE of the opportunity to exercise its competitive advantage to seek an adequate return on its large investment in developing these very valuable analytical tools.
I declare under penalty of perjuy that the foregoing affidavit and the matters stated therein are true and correct to the best of my knowledge, information, and belief.
Executed on this
'7 day of /'4U44 2007.
(3/~
eorge 3.B'Stramback General Electric Company GBS-07-01-afNMPt-I Shroud Repair Replacement Stress Rpt GE-NE-0061-6180-RO-P.doc Affidavit Page 3
Proprietary (Trade Secret)
ATTACHMENT (5)
SHROUD REPAIR REPLACEMENT UPPER SUPPORT STRESS ANALYSIS REPORT Proprietary Version Nine Mile Point Nuclear Station, LLC February 12, 2007