ML20092C828

Partially Withheld,Rev 1 to Dresden Units 2 & 3 Top Ring Plate & Star Truss Stress Analysis Backup Calculations

ML20092C828
Person / Time
Site:	Dresden
Issue date:	05/11/1995
From:	Hower S, Karimpanahi K, Kaul M GENERAL ELECTRIC CO.
To:
Shared Package
ML20091F935	List: ML20092C737 ML20092C771 ML20092C780 ML20092C809 ML20092C828 ML20092C845 ML20092D229
References
FOIA-95-188 GENE-771-96-019, GENE-771-96-0195-R01, GENE-771-96-19, GENE-771-96-195-R1, NUDOCS 9509130152
Download: ML20092C828 (13)

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9 GENuclearEnergy GENE-771-96-0195

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REV1 DRF #B13-01749 1

i DRESDEN UNITS 2 & 3 TOP RING PLATE AND STAR TRUSS STRESS ANALYSIS BACKUP CALCULATIONS (GENE-771-95-0195)

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Prepared by:

d n r... he Date: 5/9/95 j

S. Hower Engineer i

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Verified by:

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M. K. Kaul, Principal Engineer I '

l Approved by:

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K. Karim-Panahi, Principal Engineer M

Date:

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R. P. Svarney, Project Manager 9509130152 950830 i

PDR FOIA IRWIN95-188 PDR

GENrclear Energy GENE 771-96-0195 GEPROPRIETARY DRFB13-01749 Rev.1 4

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2, PROPRIETARY INFORMATION NOTICE This document contains proprietary information of General Electric Nuclear Energy (GENE) and is fumished to Commonwealth Edison (Comed) in confidence solely for the purpose or purposes stated in the transmittal letter. No other use, direct or i

indirect of the document or the information it contains is authorized. The recipient shall not publish or otherwise disclose it or the information to others without written consent of GENE, and shall retum the document at the request of GENE.

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iMPORTANT NOTICE REGARDING THE CONTENTS OF THIS REPORT The only undertakings of GENE respecting information in this document are j

l contained in the contract between Comed and GENE, and nothing contained in this i

document shall be construed as changing the contract. The use of this information by anyone other than Comed, or for any purpose other than that for which it is intended, is not authorized; and with respect to any unauthorized use, GENE makes t

no representation or warranty and assumes no liability as to the completeness, accuracy, or usefulness of the information contained in this document.

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GE Nuclear E:ergy GENE 771-96-0195 GEPROPRIETARY DRFB13-01749 Rev.1 EXECUTIVE

SUMMARY

The installation of the proposed shroud modification in Dresden 2 & 3 will result in l

an increase in the seismic force transmitted to the reactor pressure vessel (RPV) and support i

structure. The members of the support structure, specifically the RPV stabilizer, top ring plate and star truss, are analyzed to determine if the design is sufficient to withstand the 4

increased load. This report presents the detailed stress analysis performed for the top ring i

plate, RPV stabilizer and star truss.

The results of the finite element analysis and hand calculation stress analysis show that the RPV stabilizer, top ring plate and star truss are capable of withstanding the increased loads resulting from the installation of the shroud modification hardware.

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GENuclest Energy GENE 77196 0195 GEPROPRIETARY DRFB13-01749 Rev.1 TABLE OF CONTENTS 1.0 TOP RING PLATE STRESS ANALYSIS AND RESULTS....

...1 1.1 A s s umpti ons............................................................................................................ 1 1.2 Fini te El ement M od el................................................................................................ 1 1.3 S tress Eval uation Methodology.................................................................................. 2 1.4 S tres s Eval uati on Results........................................................................................ 2 2.0 STAR TRUSS & RPV STABILIZER STRESS ANALYSIS AND RESULTS...

8 2.1 Assumpti ons............................................................................................................ 8

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2.2 S tress Calculations................................................................................................... 8 2.3 Stress Evaluation Methodology................................................................................ 9 2.4 S tress E val uation Resul ts....................................................................................... 9 2.5 Stress Evaluation Results for Other Components.....................................................I 0 1

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3.0 CONCLUSION

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17 4.0 REFEREN CES..

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GENrclear Exergy GENE 771-w0195 GEPROPRIETARY DRF B13-01749 Rev. I J

LIST OF FIGURES Figure 1-1:

Finite Element Model Loading and Boundary Conditions............................. 3 Figure 1-2:

Finite Element Model Node Numbers........................................................ 4 Figure 1-3:

Von-Mises Stress Distribution in Top Ring Plate.......................................... 5 7

LIST OF TABLES Table 1-1:

M aterial Properties................................................................................. 2 LIST OF CALCULATIONS Calculation 1-1:

Finite Element Analysis Model Loading.................................... 6 Calculation 1-2:

Average Stress Around Bracket Weld.................................. 7 i

Calculation 2-1:

Star Truss Stress Analysis............................................................... I 1 Calculation 2-2:

RPV Stabilizer Stress Analysis...

...........................................14 i

Calculation 2-3:

RPV Stabilizer Bracket Welds Stress Analysis.............................15 1

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GE Nxclear Exergy GENE 77196-0193 GE PROPRIETARY DRF B13-01749 Rev.1 1.0 TOP RING PLATE STRESS ANALYSIS AND RESULTS Stress analysis of the Dresden 2 & 3 reactor pressure vessel (RPV) support structure was performed to evaluate the effects of the increased seismic loads on the RPV stabilizer, top ring plate and star truss. The details and results of the stress analysis for the top ring plate are presented in this section.

1.1 Assumptions In the top ring plate stress analysis it was assumed that the RPV stabilizers behave like tmss members. This assumption is conservative because the stablizers actually behave like beams. A beam structure increases the stiffness and resistance of the stmeture more than a truss.

1.2 Finite Element Model The purpose of this model was to perfonn a stress analysis of the top ring plate when subjected to increased seismic loads due to the addition of the shroud modification hardware.

Dimensions for the model were obtained from the drawings specified in Ref. [1]. The complete finite element model is shown in Fig.1-1. The node numbering scheme is depicted in Fig.1-2.

The finite element model of the Dresden 2 & 3 top ring plate stmeture was developed using the COSMOS /M, version 1.70 finite element program [2]. COSMOS /M is verified for accuracy by using sample problems and comparing the results with alternate calculations.

I The sample problems included static analysis problems with similar elements.

A finite element analysis was perfonned on the top ring plate to evaluate the local effects of the axial and bending loads induced by the RPV stabilizer connection. The model consisted of a quarter section of the structure because of the symmetry of the geometry and loading. The top ring plate was modeled with shell elements. An equivalent moment was distributed among nodes representing the stabilizer bracket. Forces representing the axial load were also applied. The long edges of the plate were fixed and vertical motion was i

constrained at the locations where the biological shield concrete would act to inhibit the downward vertical motion.

The maximum SSE global forces in the RPV stabilizers were determined in Ref. [3].

These loads for the faulted condition were used to produce the maximt.m, and therefore most

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GEN: clear Energy GENE 771-9M195 GEPROPRIETARY DRFB13-01749 Rev. I conservative, stress results for the top ring plate. Thejet force from a main steam line break (MSLB) was shown to yield a greater resultant force than a reactor recirculation line break (RRLB) at the location of the support structure [6). Thus, the MSLBjet force was applied to the support structure to yield the most conservative results. The axial load in the RPV stabilizer was taken as half of the faulted condition global force given for the RPV stabilizer, 1120 kips, in addition to half of the MSLB jet force of I84 kips [6], resulting in a load of 652 kips. The stabilizer pretension load of 260 kips was subtracted as this load is taken by the sleeve. This result,392 kips,is detailed in Calculation 1-1. To determine the effects of the stabilizer eccentric loading, the maximum stabilizer load acting on each stabilizer bracket, 392 kips, was converted into an equivalent moment by using the appropriate lever length, 7 inches. The equivalent moment was effectively represented by distributing vertical forces among nodes representing the stabilizer bracket. The eccentric loading calculations are presented in Calculation 1-1.

Constant material properties evaluated at an operating temperature of 150 F, as shown in Table 1-1, [5), were utilized in the stress analysis.

Table 1-1 Material Properties Symbol Description

-Top Ring Plate

-SA 36 p

Density 0.283 lb/in' E

Modulus of Elasticity 29.65 x10' psi v

Poisson's Ratio 0.326 a

Mean Coefficient of 6.57x104 in/in-F Thermal Expansion 1.3 Stress Evaluation Methodology The loads described in Section 1.2 were applied as spe cified. The stress in the top ring plate was obtained by taking the maximum average stres ; of the elements in the area of the stabilizer bracket. The stress calculation is presented in Calculation 1-2.

1.4 Stress Evaluation Results The primary finite element analysis indicated the maximum average stress in the top ring plate for the SSE + JET loading condition is 16,052 psi. This stress is below the seismic allowable stress,0.95*F,, of 34,200 psi with a safety factor of 2.13. The stress distribution is seen in Figure 1-3. This result is presented in Calculation 1-2.

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GENE 771-96-0195 4

GEN cle:r Ecergy DRF B13-01749 GE PROPRIETARY Rev.1 2.0 STAR TRUSS AND RPV STABILIZER STRESS ANALYSIS AND RESULTS i

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Stress analysis of the Dresden 2 & 3 reactor pressure vessel (RPV) support strue:are l

l was performed to evaluate the effects of the increased seismic loads on the RPV stabilizer, top ring plate and star truss. The details and results of the stress analysis for the star truss l

members, RPV stabilizer and RPV stabilizer bracket welds are presented it this section.

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i' In the star truss, RPV stabilizer and RPV stabilizer bracket weld stress analysis it was assumed that the RPV stabilizers and star truss members behave like truss eleme assumption is conservative.

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I 2.2 Stress Calculations The purpose of this calculation was to perform a stress analysis of the star truss, RPV!

l stabilizer and RPV stabilizer bracket welds when subjected to increased seismic loads due to the addition of the shroud modification hardware. Member properties for the analysis were l

obtained from drawings specified in Ref. [1].

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The maximum SSE global force in the star truss was determined in Ref. [3]. This 4

SSE load was distributed according to Ref. [6] to determine the most severely loaded l

member. This member was analyzed to produce the maximum, and therefore most i

conservative, stress results for the star truss members. The globM 'orce for the star truss was l

taken as the global force for the faulted condition given in Ref. [3],1610 kips, in addition to the MSLB jet force of 229 kips [6] resulting in a load of 1839 kips. This load was then l

distributed in accordance with Ref. [6] to obtain the maximum star truss memb of 382.6 kips as shown in Calculation 2-1.

i The maximum SSE global forces in the RPV stabilizer were determined in Ref. [3].

These SSE loads were used to produce the maximum, and therefore most conservative, stress 2

results for the stabilizer. The maximum axial load in the RPV stabilizer w the global force given for the RPV stabilizer,1120 kips, in addition to half of the MSL I

force of 184 kips [6], resulting in a load of 652 kips. The pretension load of 260 kips was subtracted from the seismic + jet load to yield a total stabilizer load of 392 kips. This result i

is detailed in Calculation 2-2.

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The maximum SSE global forces in the RPV stabilizer brackets were determined in Ref. [3). These SSE loads were used to produce the maximum, and therefore most conservative, stress resuhs for the bracket welds. The maximum axial load in one RPV 8) t

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stabilizer bracket was 392 kips. The moment induced by the eccentric axial load was i

calculated by using the appropriate lever length,7 inches, resulting in a moment of 2744 l

kips-in. These loads are calculated in Calculation 2-3.

2.3 Stress Evaluation Methodology d

'Ihe loaJ tescribed in Section 2.2 were applied as specified. The stress in the star truss was evaluated by dividing the maximum axial load by the area of the member as seen in Calculation 2-1.

i The stress in the stabilizer was conservatively calculated by dividing the maximum I

force in the stabilizer by the area of the tension rod. This is demonstrated in Calculation 2-2.

The stress transmitted to the bracket plate and weld was determined from the bending e

moment, axial load, and the section properties of the plate and weld. The maximum stress in the weld was then calculated from the resulting shear and bending stresses as detailed in Calculation 2-3.

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2.4 Stress Evaluation Results 1

The stress analysis indicated the maximum stress in the star truss for the SSE + JET 4

loading condition is 12,491 psi as demonstrated in Calculation 2-1. This stress is belol seismic allowable tensile stress of 34,200 psi with a safety factor of 2.74. This stress is below the seismic allowable compressive stress of 33,954 psi with a safety factor of 2.72.

4 The stress analysis indicated the maximum stress in the RPV stabilizer for the SSE +

JET loading condition is 47.2 ksi as demonstrated in Calculation 2-2. This stress is bel i

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AISC seismic allowable stress of 90.0 ksi with a safety factor of 1.91.

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l The stress analysis indicated the maximum stress in the stabilizer bracket plate for th l-SSE + JET loading condition is 15,7% psi. This stress is below the seismic allowable stressj of 34,200 psi with a safety factor of 2.17. The raress analysis indicated the maximum str in the stabilizer bracket weld for the SSE + JET loading condition is 13,816 psi. This stre is below the AISC seismic allowable stress of 28,800 psi with a safety factor of 2.08. Thes results are detailed in Calculation 2-3.

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GE Nuclext Exergy GENE 77196-OI95 GE PROPRIETARY DRF B13-01749 Rev.1

3.0 CONCLUSION

S The results of the stress analysis show that the RPV stabilizer, top ring plate and star truss are capable of withstanding the increased loads resulting from the installation of the shroud modification hardware.

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. 5 GENE-523-A181-1294, Revision 0 Commonwealth Edison Company Dresden Units 2 & 3 Nuclear Power Station Primary Structure Seismic Models J

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