ML20077Q125

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Boston Edison Requirements for Seismic Analysis for General Electric RPV Shroud Repair Project
ML20077Q125
Person / Time
Site: Pilgrim
Issue date: 11/01/1994
From: Dyckman J, Harizi P, Kline W
BOSTON EDISON CO.
To:
Shared Package
ML19311B648 List:
References
NUDOCS 9501190114
Download: ML20077Q125 (13)
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Text

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  • Rev. 1 Boston Edison Requirements for Seismic Analysis for i l

I General Electric RPV Shroud Repair Project l

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l i Prepared by: '

a . Date: 10/Slfi'i

! hn G. Dyckman'/ ~ ~

Principal Civil /Sfructural Engineer-Reviewed by: _h Philip Harizi Date: #/#/M Senior Mech,anica gi ear 1 fi Approved by: __ _

Date: '/Y, 7  ;

illiam R in l Civil /St l Division Manager i Approved by: dit/ _ Date: /////fd David Heard Project Manager Boston Edison Company 600 Rocky Hill Road Plymouth, MA 02360 5599 9501190114 950116 PDR ADOCK 05000293 p PDR u j

1.0 Purpose

The purpose of this document is to define Boston Edison's requirements for the seismic analysis work being performed by General Electric Company (GE) in support of

, the design of the repair for the Reactor Pressure Vessel (RPV) Core Shroud. This initiative is the result of project coordination meetings with GE project personnel,

pursuant to GE-NE Proposal No. 893-lE2AW-HKI, dated July 15, 1994. The design objective is to produce a pre-emptive core shroud repair to resolve the weld cracking issue. From a design perspective, the modification must be technically adequate, licensable and meet the intent of the BWR-VIP Repair Committee guidance. This document identifies requirements for the seismic analysis efforts.

2.0 Licensing Basis Seismic Design Requirements: The seismic ground motion requirements for the design of Pilgrim Station are shown in FSAR Figures 2.5-5 and 2.5-

6. The shapes of the response spectrum plots for the 0.08g Operating Basis Earthquake (OBE) and 0.15g Safe Shutdown Earthquake (SSE) follow the circa 1960's recommendations of expert G.W. Housner (i.e., the so-called Housner shape spectra). GE performed the original seismic analysis to qualify the Pilgrim Nuclear Steam Supply ,

System (NSSS) components supplied by GE. The results of these efforts for the RPV are l contained in GE Document No. 383HA494, entitled ' Pilgrim Seismic Analysis of Reactor", DAR 113, dated February,1971 (BECo SUDDS/RF 93-122). This analysis used for input motion to their mathematical model, an acceleration-time history record frora the 1952 Taft earthquake. This record conservatively enveloped the FSAR ground

, motion requirements. The Atomic Energy Commission't, (now Nuclear Regulatory Commission) Safety Evaluation for Pilgrim Station's operating license recognizes that seismic design implementation was based on response spectra developed from a Taft earthquake record. Thus, the Taft earthquake record is considered to be part of Pilgrim Station's licensing basis for seismic design.

3.0 Requirements

GE shall prepare a seismic analysis report. for Boston Edison's approval.

The report shall be in two parts: Pan I shall present the methods and procedures being used for the shroud repair project. Part 2 shall contain the detailed results of the seismic analysis. The GE seismic analysis report shall address the following topics as a minimum..

3.1 BuildinclRPV Model 1 1

3.1.1 Describe the mathematical model for the building and RPV being used to compute seismic inputs for the design of the shroud repair, its relationship to the model described in GE Documert No. 383HA494, and any changes )

or differences. Describe any additional parameters not contained in the 3 1971 GE report which are necessary for completeness of the model, and the source documentation for those parameters.  !

3.1.2 Identify the computer programs being used to perform dynamic analyses of the GE model, and their quality assurance qualification status.

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3.1.3 Describe the means used to verify and benchmark the current model frequency and mode shape outputs to the original results j i

3.1.4 Identify the different shroud cracking configurations represented in the  !

seismic analyses, provide the basis for selecting them as the bounding conditions, and furnish justification for modeling methods used to represent cracking.

3.2 Design Basis Seismic Inout Motion .  ;

3.2.1 GE Document No. 383HA494 identifies the 1952 Taft Eanhquake normalized to a maximum acceleration of 0.08g, as the design basis for the '

lower of the two earthquake design levels. The 1971 GE work performed an analysis for the lower earthquake design level of 0.08g, and then multiplied the results by the ratio 1.875 to obtain responses for the 0.15g ,

earthquake level. Describe the procedures being used in the current work to produce results for the two earthquake levels.

Note: The nomenclature in GE Document No. 383HA494 for the two t earthquake levels is different from current nomenclature. It defines the DBE as having a peak ground acceleration (PGA) of 0.08g and the maximum earthquake PGA as 0.15g. Pilgrim's current licensing basis identifies the 0.08g level as the Operating Basis Earthquake (OBE), and the 0.15g level as the Safe Shutdown Earthquake (SSE).  ;

3.2.2 Implicit in the use of the Taft record is that it envelopes the Housner shape ground response spectra shown in FSAR Figures 2.5-5 and 2.5-6 at ,

frequencies ofinterest. Provide plots of the ground response spectra of j GE's time histories for the Taft and Housner load cases to be used for the Pilgrim shroud repair design, comparing them to the ground response spectra shown in FSAR Figures 2.5-5 and 2.5-6 at 0.5%, 2% and 5%-

damping.

3.2.3 For each time history input being used, identify the input time step, the total duration for the input, and the solution time interval. Describe how uncertainties are accounted for in structural modeling, similar to peak broadening in response spectrum analysis.

3.3 Enponse Calculations ,

3.3.1 GE Document No. 383HA494 identifies the time history method as the means used to determine seismic loads for the RPV and internal qualification. Confirm that this is the method intended for the current work. Identify and justify any differences in the implementation details from the 1971 work.

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3.3.2 Identify the methods to be used to combine seismic analysis results from different modes and directions. An acceptable approach for time history analysis is the modal superposition method with the response from each mode combined algebraically.

3.3.3 , Damping values shall be consistent with FSAR Table 12.2 3J Describe the damping values to be used for OBE and SSE analyses, and the bases and/or source documentation.' Describe the procedures to be used to account for damping effects. The modal damping coefficients applied.to the time history analysis may utilize a strain-weight d damping calculation method.

3.4 Seismic Load Cases -

GE Document No. 383HA494 furnishes excitation results for east-west and north-south model properties, and fo_r the condition of the biological shield wall filled with concrete which is the as-built condition, and 'ho concrete" case. The latter case is a sensitivity analysis which apparently. retains the concrete fill mass, but adjusts the shield properties to represent non-composite behavior of the steel

. plate / concrete structure. The current work ~should be performed as a minimum for whichever condition controls the design, i.e., the condition which produces the most conservative result, and provide justification if not performing the analyses for both conditions.

3.5 Reactor Vessel Resnonne Provide the results of analyses to assess the effect of repaired cracked shroud versus the shroud in its original design condition, in terms of the differences at points ofinterest representing the RPV anchorage to the pedestal, the stabilizer connection, and piping nozzles. This may be performed by generating response

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spectra curves at 5% damping at the RPV nodes, and furnishing an assessment of ,

the effects on the NSSS seismic qualification for points ofinterest.

3.6 Shroud Repair Modeling The seismic analysis for the shroud repair will produce seismic forces for design of the repair hardware assuming specified stiffness for the upper and lower springs.

The stress analysis for the hardware must consider all load cases for the degraded shroud condition, and demonstrate convergence between the computed spring stiffness and the stiffness used for seismic analysis.

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! 4.0 Beyond Design Basis Seismic Requirements: The GE shroud repair design assumes a l cracked shroud, and results in dynamic characteristics that are somewhat unusual for I typical nuclear power plant components. This design is most sensitive to seismic motions at frequencies below 2 Hz. The licensing basis seismic requirements may not necessarily provide the best estimate of the seismic demand m this range of response. A newer seismic analysis technology, called soil / structure interaction (SSI) analysis, better predicts low frequency seismic response of buildings founded on soil. BECo has used this -

technology in various seismic analysis studies for Pilgrim.

4.1 fioil Structure Interaction / Safe Shutdown Earthquake Load Case 4.1.1 An 'SSUSSE' load case shall be evaluated using the GE RPV model, coupled with the Reactor Building model developed by EQE Engineering Consultants (EQE) under Purchase Order LBR 107049. EQE shall prepare the new coupled model and compute seismic loading on the GE shroud repair design for the contro!!ing shroud conditions determined by GE. The results of this work shall be documented in a report.

4.1.2 GE shall compute stresses in the RPV core shroud and repair design for the SSUSSE load case and combine them with stresses computed for other loading conditions.

l l 4.2 Load Combinations l

l The SSUSSE loading shall be treated as a faulted condition and combined with other design loadings as follows:

SSUSSE + Nonnal P + W

! SSUSSE + RR LOCA + W SSUSSE + MS LOCA + W 5.0 Attachments 5.1 FSAR Figure 2.5-5, Operating Basis Earthquake Response Spectra for Pilgrim 5.2 FSAR Figure 2.5-6, Safe Shutdown Earthquake Response Spectra for Pilgrim l

5.3 FS AR Table 12.2-3, Damping Factors l

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OPERATING BASIS EARTHQUAKE PILGRIM NUCLEAR POWER STATION FINAL SAF ETY ANALY SIS R E PORT

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FABLE 12.2-3 ,

I DAMPING TACTORS Percent of Critical Damping i

Maximum Design Credible i Earthquake Earthe,uake Item Reinforced Concrete Building 5.0 7.5 l i

I. l Internal Concrete Structures 2.0 3.0 j and Equipment Supports 2.0 3.0  !

Component and Equipment )

g 2.0 5 .'O l Bolted Steel Assemblies /

Structures 4.0 7.0 l Concrete Blockwall-1.0 2.0  ;

Neldsd Assemblies / Structures Class I Piping Systems (See Note 4) l 1.0 2.0 12 in and smaller 2.0 3.0 Larger than 12 in

-- _ wu Tray and Conduit Supports 4.0 7.0 NOTES:

1. OBE is the Operating Basis Earthquake which is equivalent to the Design Earthquake.
2. SSE is the Safe Shutdown Earthquake which is equivalent to the Maximum Credible Earthquake.
3. The percent of critical damping values used are derived from and associated with the lower stress values developed and recommended l by Newmark and Hall in NUREG/CR-0098.

For all piping systems, damping values of 5% for frequencies of zero to 10 Hz and decreasing linearly to 2% at 20 Hz may be alternately used for seismic analysis. Per ASME Code Case N-411, this applies to both Design -Earthquake and Maximum Credible e mee d L- hAb.

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-- 1 of 1 Revision 5 - July 1935

s 0228-78003 e (' ) GE Nudear Energy "'"*-

v C REVISION Field Disposition Instruction Su,Er 1 o, 5 DATE OF ISSUE PROJECT Pilurim UNIT EQUIPMENT P S ECN/lR/DDR/F DDR B11-D001 MPL NO.

DESCRIPTION oF TASK I. Purpose This FDI documents the design, requirements and material required to install the stabilizers for the shroud horizontal welds.

II. Required Documents (Supplied by Engineering)

Document Number Revision Description A. 107E5471 B " Reactor Modification Drawing B. PL107E5471 A "Rer.ctor Modification Drawing Parts Lists" C. 25A5605 A "Irstallation Specification D. 21 A2040 1 " Cleaning and Cleanliness control" E. 25A5598 A " Shroud Stabilizers, Design Specification F. 25A5599 A " Shroud Stabilizers, Certified Design Specification G. GENE B11-0067-03 1 " Safety Evaluation for Pilgrim Shroud Repair" l H. 25A5685 B " Shroud Stabilizer Vessel" Stress Report I. GENE 771-79-1194 2 " Shroud Repair Hardware Stress Analysis" J. GENE 771-65-1094 1 " Seismic Design Report of Shroud Repair for Pilgrim K. QAM-001 4 "GE Quality Assurance Manual" I. GENE-523-A192-1294 0 " Inspection Recommendations For Vertical Welds" III. Material Required (per Paragraph II.a and II.b)

Parts Document Document Parts List Number Revision Description Qg Revision A. I12D5239G001 B Lower Mid support Assembly 4 B l B. I12D6362G001 B Upper Stabilizer Assembly 4 A APPR ALS DATE APPROVALS DATE Tms toUIPMENT IS SAFETY RELATED F fE3 Q NO SAFETY FUNCTION es AFFECTED [ yEs O No

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a o[o..oiNav o n FIELD WORK ORDER NO. 7," 0,"y ",Ej"O QUALa T v DISTRIBUTION CODE 7DI TASK COMPLETED DATE ENcao maNacEn INTERNAL EXTERNAL mE5pON$tBLE ENGR St TE QUAL 47Y CON 1 ROL

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'~~ 0228-78003 I N) GE Alacles Enugy

, .( C REVISloN Field Disposition Instn/ction gn,,, 2 o, 5

DESCRIPTION OF TASK Parts j Document Document Parts List i Number Revision Description Qt.y Revision C. Il2D6363G001 B Stabilizer Support Assembly 4 B D. I12D6364G001 A Tie Rod Assembly 4 A E. I12D6365G001 D Tie Rod / Spring Assembly 4 D F. I12D6366G001 B Core Plate Wedge Assembly 4 A G. I12D6367G001 B Upper Mid Support Assembly 4 B H. Il2D6368G001 A Lower, Stabilizer Assembly 4 A I. I12D5233P001 A Bolt, Shroud Lug 8 N/A

1. 112D5234P001 B Stop, Bottom Spring 4 N/A J. Il2D5235P001 B Bolt, Stop 4 N/A K. I12D5240P001 A Arm, Torsion 4 N/A L. I12D5240P002 A Arm, Torsion 4 N/A M. I12D5241P001 A Bolt, Torsion Arm 4 N/A N. I12D5245P001 B Extension, Lower Spring 4 N/A O. I12D5246P001 B Extension, Upper Support 4 N/A P. I12D5251P001 B Wedge, Core Plate 4 N/A Q. I12D5252P001 B Clip, Core Plate 4 N/A R. I12D5253P001 A Bolt, Wedge 4 N/A S. I12D5255P001 A Bolt, Lower Spring Extension 4 N/A T. I12D5265P001 A Lock, Latch 8 N/A U. I12D6369P001 C Rod Tie 4 N/A V. I12D6370P001 C Nut, Tie Rod 4 N/A W. I12D6371P001 C Spring, Lower 4 N/A X. I12D6450P001 B Spring, Upper 4 N/A Y. I12D6451P001 A Bracket, Upper Spring 4 N/A Z. I12D6452P001 b Support, Upper 4 N/A  ;

AA. I12D6452P002 B Support, Upper 4 N/A i BB. I12D6453P001 B Support 4 N/A l CC. I12D6454P001 A Contact, Lower 4 N/A DD. I12D6455P001 A Pin, Clevis 4 N/A EE. I12D6456P001 B Nut, Top Support & Pin Det 32 N/A FF. I12D6456P002 B Nut, Top Support & Pin Det 68 N/A l GG. I12D6456P003 B Nut, Top Support & Pin Det 8 N/A HH. 112D6456P004 B Nut, Top Support & Pin Det 12 N/A II. I12D6456P005 B Nut, Top Support & Pin Det 4 N/A ,

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revision Field Disposition Instruction ,,,,, 3 o, 5 DESCRIPTION oF TASK Parts Document Document Parts List Number Revision Descriotion Oty Revision JJ. I12D6456P006 B Nut, Top Support & Pin Det 4 N/A KK. I12D6456P009 B Nut, Top Support & Pin Det'. 4 N/A LL. Il2D6457P001 A Bolt, Top Support 16 N/A MM. I12D6458P001 A Nut, Top Support 8 N//A NN. Il2D6459P001 A Retainer 4 N/A

00. 112D6460P001 A Spring, Retainer 16 N/A PP. I12D6461P001 B Bolt, Jack Bolt 4 N/A QQ. I12D6462P001 B Sleeve, Jack Bolt - 4 N/A RR. I12D6463P001 A Washer, Jack Bolt 4 N/A SS. I12D6464P001 A Spring, Retainer 4 N/A TT. I12D6465P001 B Suppon, Upper 4 N/A UU. I12D6465P002 B Support, Lower 4 N/A VV. I12D6466P001 A Ring, Mid Support 8 N/A WW. I12D6467P001 A Screw, Mid Support 8 N/A XX. I12D6473P001 A Latch 4 N/A YY. I12D6473P002 A Latch 12 N/A ZZ. I12D6475P001 B Contact, Upper 4 N/A IV. Repair Procedure All of the stabilizer installation shall be performed under water. All work shall be performed in accordance with Paragraph II.A and II.C.

1.0 The examinations to be performed should include those that are in GENE-523-A192-1294,

" Inspection Recommendations for Vertical Welds" The recommended examination are Enhanced VT should include:

a. Accessible areas of the welds between the four gussets to be used for the stabilizers and both the RPV wall and shroud suppon plate.
b. Accessible portions of the shroud suppon plate to RPV circumferential weld (designated HI1).
c. Vertical welds intersecting H4 (ID and OD), it is suggested that the minimum length examined be 4" along each vertical weld,
d. Radial welds in top guide support ring OD.

.(C'^') GE Nacleu Energy '""' 0228-78003 D

REVISloN C MI SHEET 4 oF 5 DESCRIPTION oF TASK 1.0 Perform a VT-1 examination of the accessible areas of the welds between the four gussets to be used for the stabilizers and both the RPV wall and shroud support plate.

2.0 Shroud Head and Gusset Machine the required holes in the shroud head and shroud sup' port gussets, per II.A.

3.0 Repair Clamp Installation Install the four stabilizers in accordance with the requirements in Paragraph II. A. and C.

4.0 Repair Examination A visual examination of the completed repair shall be performed. The television camera shall be capable of resolving a .001 inch diameter wire on a neutral gray background.

a. Examine each clevis pin to assure that it is properly located and in corTect with the bottom cf the slot in the lower spring.
b. Examine the core plate wedge assemblies to assure that they are properly seated
c. Examine the stabilizer assembly for contact between the RPV wall and the upper contact, mid support, and lower contacts.
d. Examine the stabilizer assembly for contact between the shroud and the upper support and lower spring.

V. Quality Requirements 1.0 GE Site Quality Control Representatives shall provide QC surveillance and document the field work performed, to insure that the requirements of this FDI hav: been met. All work is to be performed in accordance with GE Quality Assurance Manual QAM-001.

2.0 The following shall be the minimum Quality Control Documentation Requirements

a. Video tape of the completed repair
b. Process documentation and inspection deta sheets as applicable.
c. As-built dimensions per II.A.

F31 NO. 0228-78003

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REVIStoN b Field Disposition Instmetion ,,,,, 5 o, 5 DESCRIPTION oF TASK 3.0 The following procedures and supporting documentation shall be submitted to GE Site QA and Plant Owner (as applicable) for review, and approval obtained prior to use. Previously l approved GENE procedures may be used in satisfying the requirements of this paragraph provided they are approved by the Plant Owner.  ;

I r mstallation procedures, travelers, or sequence data sheets, measurement data sheets, l drawings, sketches, instructions, etc. These procedures or travelers shallinclude cleaning and cleanliness, tool control, machining processes, and visual inspection methods.

b. Hardware certifications.

VI Safety / Reliability Safety and reliability have been considered in the issue of the design documents for this project. The requirements for this design are contained in the Design Specifications 25A5598 and 25A5599. The seismic analysis of the repair is documented in GENE-771-65-1094. The structural analysis of the repair are documented in GENE-771-79-1194 and 25A5685. The safety evaluatica for repair is contained GENE-B11-00617-03. No new safety requirements, reviews or technical specifications are required by this FDI.

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