ML20045G799
| ML20045G799 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 05/07/1993 |
| From: | Hookway R EQE, INC. |
| To: | |
| Shared Package | |
| ML20045G695 | List: |
| References | |
| 42094-P-002, 42094-P-2, NUDOCS 9307160005 | |
| Download: ML20045G799 (14) | |
Text
{{#Wiki_filter:a ENGINEERING coxsu tcrA NTS Project Plan Connecticut Yankee Atomic Power Company Seismic Upgrade Program for Service Water System, Feedwater System and Main Steam System Outside Containment PROCEDURE NO.: 42094-P-002 REVISION NO. 1 DATE: May 7,1993 ) PREPARED BY/DATE: dl <kI[ 2,b
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5'7-f3 APPROVED BY/DATE: 5,_ 9307160005 930709 c*, PDR ADOCK 05000213 M P PDR F"fi LR EQE ENGINEERING CONSULTANTS A Division of EQE Intentational
s 42094-P-OO2 Revision 1 May 7,1993 i Page 2 of 14 TABLE OF REVISIONS Revision No. Descriotion of Revision Date Acoroved 0 Original Issue April 2,1993 1 Revised paragraphs 1.0 and May 7,1993 2.0. Also added paragraphs I 8 & 9 to decribe Project inter-face and QA requirements. A vertical bar in the right margin identifies all revised sections. I I I I I I L I I . I g lim ,-e rw
I* 42094-P-002 Revision 1 I May 7,1993 Page 3 of 14 TABLE OF CONTENTS Pace I 1.0 Purpose........ 4 2.0 S yst e m D e s c ription........................................................ 4 I 2.1 Se rvic e Wate r S yste m Piping................................. 4 2.2 Main S te a m S yste m Piping..................................... 5 2.3 Fe e d w a t e r Pi p i n g................................................... 6 3.0 G e n e r a l A p pr o a c h....................................................... 6 I 4.0 Background....... 7 5.0 Seismic Capability WaIkdown 8 f 6.0 Seismic Margin Analysis 9 7.0 A c ce p t a n c e Crite ria..................................................., 11 7.1 Piping System Acceptance Criteria 11 7.2 Piping Support Acceptance Criteria...................... 12 8.0 Project Organization and Interf aces................................. 13 9.0 Quafity Assurance 13 ' " " " ' ' ' " " " " " " " ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ " ~ ~ ~ ~ ~ ~ ~ ~ I I I I I l I y 4 s
42094-P-002 Revision 1 May 7.1993 Page 4 of 14 1.0 Purpose This document presents alternative methods to be used for the seismic evaluation of the Service Water System, Feedwater System and the Main Steam System piping outside containment at Connect. cut Yankee. The pur-pose is to assure, for the safety related portions of these systems (i.e. shut-down related), that sufficient seismic margin exists such that there is a high I confidence of a low probability of failure at an earthquake level equal to or greater than 1.33 times the safe shutdown earthquake peak ground accele-ration at the Connecticut Yankee site. Position retention will be assured for non-safety piping which is required for integrity of shutdown related piping.
2.0 System Description
2.1 Service Water System Pioina. The piping included in the scope of this effort includes the appropriate supply and discharge piping as described on the following drawings: 20231-SH-105-AG 20231-SH-105-AH 20231-SH-105-AJ 20231-SH-105-AK 20231-SH-105-AL 20231-SH-105-AM 20231-SH-105-AV 20231-SH-105-AW I 20231-SH-105-AX 20231-SH-105-AY 20231-SH-105-AZ 20231-SH-105-BA 20231-SH-105-BC 20231-SH-105-BD 20231-SH-105-BH 20231-SH-105-BJ 20231-SH-105-BK I 20231-SH-105-BM 20231-SH-105-BN
42094-P-002 Revision 1 . I May 7,1993 Page 5 of 14 I All of this piping is in the Primary Auxiliary Building and a large portion is supported from the roof at Elev. 53'-8". This piping consists of 16" & 18" header piping at Elevation 50*-0" in the Primary Auxiliary Building with numerous branch lines varying in size from 6" to 16" diameter. The branch connections consist primarily of unreinforced stub-in connections. Support for this piping consists of short rod hangers I from the ceiling, lateral supports on the headers and stanchion supports for piping near the floor elevations. 2.2 Main Steam System Picina. The piping included in the scope of this effort includes the appropriate piping from the Reactor Containment I penetration to the stop valves at Elev. 66'6". This piping is shown on drawings: 20231-SH-101 A 20231-SH-101 B I 20231-SH-101C 20231-SH-101 D I 20231-SH-101 E 20231-SH-101 F The 24" diameter Main Steam lines run from the containment penetration to the 35" diameter manifold header at Elevation 51'-6" in the Turbine building. Branch connections of 12",18", 24" and 30" diameter on the rnanifold made with reinforcing pads on stub-in connections lead to the stop valves at elevation 66'-6". This piping is supported primarily on spring hangers. Only the short portions of piping (= 21') between inc Reactor Containment and the Containment isolation Valves is safety related. Pressure boundary integrity must be assured for the safety related piping. The remainder of the piping is non-safety related and only failure and falling is of concern. I I I M
J 42004-P-002 Revision 1 -{ I May 7,1993 Page 6 of 14 2.3 Feedwater Pioino The piping included in the scope of this effort includes the appropriate piping from the Reactor Containment penetration to the outermost Valve in the Turbine Building which is required to ensure Auxiliary Feedwater Flow. The piping downstream of this Valve is considered non-safety related. This piping is chown on drawings: 20231-SH-102 A 20231-SH-102G 20231-SH-102B 20231-SH-102H 20231-SH-102C 20231-SH-102J 20231-SH-102D 20231-SH-102K 20231-SH-102E 20231-SH-102L 20231-SH-102F 20231-SH-102M I The 12" diameter Feedwater line numbers 7,8,9, and 10 run from the - containment penetration to an 18" header pipe at Elevation 47'-13/8" in the Turbine Building. Branch connections of 12" and 18" diameter on the manifold made with reinforcing pads on stub-in connections provide a by-pass to the 12" Main Feedwater line and lead to the Feedwater Heaters. Support for this piping is provided primarily by spring hangers and sliding supports in addition to an intermediate pipe anchor between the Reactor Containment and the Turbine Building. 3.0 General Approach I Reference 1 presents the criteria used for the Connecticut Yankee safety related piping seismic qualification program. The criteria presented herein can be used in lieu of those of Reference 1 as an alternative approach. The portions of piping systems where function is required will be upgraded to a seismic margin level consistent with safety related equipment which is being upgraded under the USl A-46 program. That is, factors of safety for seismic demand and capacity for the piping and supports will be consistent with those iniplicit in USI A-46 acceptabce criteria I g 22
~ 42094-P-002 Revision 1 g May 7,1993 ~5 Page 7 of 14 The seismic qualification process will consist of a seismic walkdown of the systems by qualified engineers followed by a seismic margin analysis. The walkdown will be performed to identify design attributes that seismic I experience data have shown to present potential seismic hazards. These include features such as unanchored equipment, inadequate branch line flexibility, mechanical couplings, excessive support spans, brittle support details, and potential seismic interaction hazards. A representative portion of the Service Water system will be selected by the seismic review team for analysis. The portion will be selected considering I outliers and other attributes identified by the walkdown screening. A seismic margin analysis using the conservative deterministic failure margin (CDFM) approach as described in Reference 7 will be performed. This approach is summarized in Table 6-1. An additional check will be made for I-the service water piping to verify the piping will be capable of delivering required flow. Analyses will be performed as required to resolve all outhers identified for the Main Steam and Feedwater systems. I
4.0 Background
in recent years a great deal of field data has been collected on the per-formance of piping in earthquakes. The strength of the experience data is in the number and variety of ground motions and piping configurations. The variety of the data is described in Reference 4. The data show that large bore, welded steel piping has performed exceptionally wellin past strong-motion earthquakes. The piping covered in the experience database is representative of the Service Water, Main Steam, and Feedwater systems at I Connecticut Yankee. This data is supported by the results of full scale seismic testing of piping typical of nuclear power plants. As shown in Reference 5, ductile piping I systems retain pressure and structuralintegrity at many times the earthquake levels allowed by current design procedures and acceptance criteria. M I
42094-P-002 Revision 1 I' May 7,1993 Page 8 of 14 Based on the earthquake experience data and the results of the seismic testing programs, welded steel piping has been recognized as having a nigh degree of seismic ruggedness. In Reference 7, which has been approved b'r NRC for seismic margin assessment of nuclear plants under Generic Letter .g 88-20, Supplement 4, piping is considered to be rugged to earthquake levels 5 up to about 0.5g peak ground acceleration given that certain caveats are satisfied during a seismic capability walkdown. The attributes requiring evaluation are described in Reference 7. Reference 7 also provides criteria for quantitatively assessing the HCLPF I (high confidence of low probability of failure) peak ground acceleration earthquake level for piping systems using the conservative deterministic failure margin methodology. I 5.0 Seismic Capability Walkdown Walkdown screening of the systems will be performed in accordance with Reference 3. The screening criteria consist of piping system and pipe support attributes that may lead to failure as evidenced by past experience. The walkdown will also identify potential structural failure and falling interaction hazards. The walkdown procedure (42094-P-001) expands upon the direction provided in Reference '7. A key element in the criteria is the experience and qualifications of the seismic review team members. Reference 7 gives qualifications for seismic review team members. In summary, these are-I Y u Knowledge of earthquake experience data Knowledge of nuclear design standards and practice a Ability to perform fragility / margins type evaluations a a General knowledge of plant systems Minimum of five years applicable experience u a Professional Engineer registration (at least one member of the seismic review team must be a registered professional engineer)
g._ 42094-P-002 Revision 1. I May 7,1993 Page 9 of 14 6.0 Seismic Margin Analysis A representative portion of the Service Water system will be selected for a seismic margin analysis. The analysis will determine the system HCLPF (high confidence of low probability of failure) using the conservative deterministic failure margin (CDFM) method of Reference 7. The HCLPF must exceed 1.33 times the Connecticut Yankee Safe Shutdown Earthquake peak ground acceleration. This factor will give an approximate equivalency of margin between the CDFM method and the GIP method for USl A-46. For this project, the seismic margin earthquake (SME) will be taken as the NUREG/CR-0098 84% NEP shape response spectrum for rock sites anchored at 0.23g. The ground response spectrum will be reduced to account for horizontal spatial variations and incoherence of input motion per Reference in-structure response spectra will be obtained by scaling the existing con-servative design floor response spectra. Structural frequency variation may be accounted for using broadened response spectra. The piping will be linearly analyzed in accordance with Reference 2 using 5% damping per Reference 7. The analysis will use the in-structure response spectra in the vertical and two horizontal directions with stresses combined by SRSS. I Resulting stresses in ductile piping will be multiplied by 0.8 to account for inelastic energy absorption and compared to allowables equivalent to ASME Section lil, Subsection NC, for Service Level D. I I 1 I I I M I
i 42094-P-OO2 Revision 1 I May 7,1993' Page 10 of 14 .g 5 TABLE 6-1 I
SUMMARY
OF CONSERVATIVE DETERMINISTIC FAILURE MARGIN APPROACH I Load Combination: Normal + SME I Ground Response Spectrum: Conservatively specified (84% Non-Exceedance Probability) Damping: Conservative estimate of median damping Structural Model: Best Estimate (Median) + Uncertainty Variation in Frequency Soil-Structure-interaction: Best Estimate (Median) + Part. meter Variation I, Material Strength: Code specified minimum strength or 95% exceed-ance actual strength if test data are available. Static Capacity Equations: Code ultimate strength (ACl), maximum strength I (AISC), Service Level D (ASME), or functional limits if test data are available to demonstrate. excessive conservatism of code equations, then use 84% exceedance of test data for capacity equation. Inelastic Energy Absorption: For non-brittle failure modes and linear analysi.=, use I 80% of computed seismic stress in cer?::i, evaluation to account for ductility benefits, or per-form nonlinear ar.alysis and go to 95% exceedance ductility levels. In-Structure (Floor) Spectra Use frequency shifting rather than peak broadening Generation: to account for uncertainty plus use median damping Source: (2) I I I I is
42094-P-002 Revision 1 I May 7,1993 Page 11 of 14 7.0 Acceptance Criteria 7.1 Pioino System Acceotance Criteria (Safety Related) I Piping system analysis calculations for determination of seismic response will I consider 5% damping for floor response spectra. The analyses may consider the realistic effects of nonlinear behavior as appropriate including proximity / impact with other systems, interference and small clearances to stiff structures, geometric restoring forces, and wall penetration sealants. Acceptable pipe stresses for the safety related piping induced by SME inertial loads, seismic anchor movements, and dead load (including pressure I and temperature load, if significant) will satisfy the following: i l-Pr + DW + ML < 1.0 Sh 11-Th<S a 111-Pr + DW + K (SME(112 + SME(SAM)2)1/2 < 3.0 Sh Where: ~ I Pr Pressure Stress = I DW Stress due to dead weight = ML Stress due to mechanical loads (as defined in the = design specification) Th Thermal expansion stress (with appropriate SIF) = SME(1) SME inertia stress = SME(SAM) = SME seismic anchor motion stress S Yield stress = y Sh Allowable stress = SA f(1.25 Sc + 0.25 S ) = h K = 0.8 (ductility reduction factor) I I jigg g
~ . E 42094-P-002 Revision 1 I May 7,1993 Page 12 of 14 7.2 Picino Succort Acceotance Criteria Piping supports identified as outliers will be evaluated and accepted based on stress allowables or test data as follows: Acceptable flexural and tensile stresses are the lessor of 0.7 Su and 1.2 S.y Acceptable shear stresses are the lesser of 0.42 Su and 0.72 Sy. I Acceptable bolt stresses are the lesser of 0.75 Su and the minimum specified Sy. Acceptance compressive loads for conditions that may lead to instability if buckling occurs are 0.9 Pcr. In general, buckling due to I loading in the upward vertical direction, such as hanger rod buckling, is not considered as unstable. I, In-plant considerations regarding other consequences of support failure such as falling and other excessive deflection shall be made when using this provision. For expansion anchors, a minimum factor of safety of 3.0 is used when a complete inspection of the anchorage and surrounding concrete condition is performed. For welded anchorage, the allowable shear stress, based on the I throat area, will be compared to the appropriate allowable from AISC Part 111. Acceptance criteria for active valves will be based on Reference 6 and include the following: The valves will be representative of equipment in the seismic experience data base. The valve body will not be constructed of cast iron and the valve yoke I will not be constructed of cast iron in motor-and piston-operated valves, or spring-operated pressure relief valves. I The valve will be mounted on a pipe of 1-inch diameter or greater,if it is not otherwise supported. I I I gg2 g
P 42094-P-002 Revision 1 May 7,1993 Page 13 of 14 For lightweight air-operated diaphragm valves, piston-coerated valves, and spring-operated pressure relief valves, the distance from the centerline of the pipe to the top of the operator or cylinder will not exceed the distance indicated in Reference 3 corresponding to the diameter of the pipe. This chart is only applicable when the 5% damped floor response spectrum is enveloped by the 1.5 x Bounding Spectrum. When higher floor spectra are encountered, the limits of this I chart must be scaled down as appropriate. If these limits cannot be satisfied, a stress analysis may be performed applying the appropriate load at the center of gravity of the operator in the yoke's weakest I direction. The appropriate seismic load is limited to 3 g's assuming requirements of Reference 3 are satisfied. Otherwise, the seismic load will be determined considering the frequency of the piping and the in-I structure response spectrum. For motor-and piston-operated valves, which are of substantial weight, the distance from the centerline of the pipe to the top of the operator or cylinder and the weight of the operator will not exceed the values indicated in Reference 3 corresponding to the diameter of the pipe. As discussed above for air-operated values, these values must be scaled down as appropriate when floor spectra exceed 1.5 x Bounding Spectrum. In addition, a stress analysis may be performed as described above, if necessary. The actuator and yoke will be supported by the pipe and will not be I independently braced to the structure or supported by the structure, unless the pipe is also braced to a common structure immediately adjacent to the valve. This rule precludes excessive loads from being transmitted through the yoke which may lead to structural failure and falling. I, Sufficient slack and flexibility will be present in the tubing, conduit, or piping that supplies the air or power needed to operate the valve, to accommodate piping movements. 8.0 Project Organizations and Interfaces The EQE Project Manager is Paul Baughman or Robert Hookway. Other engineers may be assigned to the project on an as-needed basis. The client contact is Mr. Keith Sickles of Northeast Utilities Service Company (203-665-3785). I I prs
42cg4.p.co2 Revision 1 I May 7,1993 Page 14 of 14 All correspondence shall be addressed as follows: Mr. Keith Sickles Northeast Utilities Service Company 107 Selden Street Berlin, CT 06037 9.0 Quality Assurance This work shall be performed in accordance with tae EQE Quality Assurance l Manual (QAM) Revision 2. Project audits shall br performed on a periodic basis as determined by the corporate QA manager. 10.0 References 1. Connecticut Yankee Atomic Power Company, " Safety Related Piping Seismic Qualification Program, Criteria Document" Revision 2, April 28,1983. 2. " Piping Stress Analysis Guidelines for Seismic Qualification of Safety Related Piping at Connecticut Yankee", April 29,1983. 3. Connecticut Yankee Atomic Power Company, " Seismic Capability Walkdown Procedure for the Service Water Main Steam and Feedwater Piping and Supports", November,1992. 4. EQE, Inc., " Recommended Piping Seismic - Adequacy Criteria Based on Performance During and After Earthquakes", Palo Alto, CA., Electric Power Research Institute, January,1988. EPRI NP-5617, 5. GE Nuclear Energy, " Piping and Fitting Dynamic Reliability Program", I San Jose, CA., Electric Power Research Institute, November,1989. Draft. Report for Contract RP 1543-15, Volume 15. I Seismic Qualification Utility Group, " Generic Implementation Procedure G. (GIP) for Seismic Verification of Nuclear Plant Equipment", Revision 2, February,1992. 7. EPRI NP-6041-SL, "A Methodology for Assessment of Nuclear Power Plant Seismic Margin", Revision 1,1991. t I M I -}}