responds to ie bulletin 79-07 re seismic stress analyses

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April 24, 1979

Docket No. 50-336

Mr. Boyce H. GrierDirector, Region IOffice of Inspection and EnforcementU. S. Nuclear Regulatory CommissionKing of Prussia, PA 19406

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2IE Bulletin 79-07

In response to IE Bulletin No. 79-07 regarding seismic stress analysesof safety-related piping, the attached information is hereby submitted.

Very truly yours,

NORTHEAST NUCLEAR ENERGY COMPANY/

* '

W. G. Counsil'

Vice President

Attachment

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DOCKET No. 50-336

MILLSTONE NUCLEAR POWER STATION, UNIT No. 2

RESPONSES TO I&E BULLETIN 79-07

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Seismic analyses of safety-related piping for the original plant design wereperformed by three organizations. Combustion Engineering performed seismicanalyses of the Reactor Coolant System loop piping and pressurizer surge linepiping. Teledyne Engineering Services perf ormed seismic analyses of allother ASME Section III Class 1 piping systems. Bechtel Corporation performedseismic analyses of ASME Section III Class 2 and 3 and all other Seismic Category Ipiping. IE Bulletin 79-07 requests information intended to allow the NRC todetermine whether algebraic summation techniques were used in the design of safety-related piping. The information requested is paraphrased below in the form offour questions:

Question (1)

Identify which, if any, of the methods specified were employed for the seismicanalysis of safety-related piping in your plant and provide a list ofsafety systems affected.

Question (2)

Provide complete computer program listings for the dynamic response analysisportions for the codes which employed the techniques identified in Item 1 above.

Question (3)

Verify that all piping computer programs were checked against either pipingbenchmark problems or compared to other piping computer programs. You arerequested to identify the benchmark problems and/or the computer programs thatwere used for such verifications or describe in detall how it was determined thatthese programs yielded appropriate results (i.e., gave results which correspondedto the correct performance of their intended methodology).

Question (4)

If any of the methods listed in Item 1 are identified, submit a plan of actionand an estimated schedule for the re-evaluation of the safety-related piping,supports, and equipment affected by these analysis tcchniques. Also providean estimate of the degree to which the capability of the plant to saf ely with-stand a seismic event in the interim is impacted.

Responses to the questions raised by the IE Bulletin follow, categorized byresponsible organization:

Work Performed by Combustion Engineering

Response to Question (1)

CE has never used algebraic summation for combining the ef fects of horizontaland vertical seismic excitations.


Since CE has not employed these techniques, this question does not apply.

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Time histories of the six components of force or moment (F , F , F , Mx, M , Mz)x y 2 yat various sections of the reactor coolant system main loop piping were computedseparately for each of two horizontal and the vertical directions of seismicexcitation. Each component of force or moment from one horizontal directionof excitation was combined by absolute summation on a time basis with thecorresponding codirectional component of force or moment from the verticaldirection of excitation. The maximum combined value over all time of each ofthe six components of force or moment were chosen to define the seismic loadingcondition at the particular piping location for one horizontal and the verticalexcitations. A second seismic loading condition was also defined by repeatingthe absolute sum combination for the other horizontal and the vertical excitations.Each load set was compared to, and shown to be less governing than, the seismicloadings specified for design of the piping. Since the combination of loads wasperformed af ter the completion of the dynamic analysis portion of the computation,the appropriateness of the results of the combination was verified by direct observa-tion of the uncombined inputs and the combined output.

The six components of force or moment (Fx, F , Fz, Mx, My, Mz) at the supportsyand various sections of the pressurizer surge line piping were computed separatelyfor each of two horizontal and the vertical directions of seismic excitation byresponse spectrum dynamic analysis. The codirectional components of force ormoment from one horizontal and the vertical directions of excitation were com-bined by absolute summation to define the seismic loading condition at theparticular piping location for one horizontal and the vertical excitatio~. ..

A second seismic loading condition was also defined by repeating the ab,tolutesum combination for the other horizontal and the vertical excitations.Each load set was compared to, and shown to be less governing than, the seismicloadinga specified for design of the piping. The load combinations were calculatedand verified by l'7d.


Since CE does not use any of these techniques, this question is not applicable.

Work Performed by Bechtel Corporation


Bechtel did not employ algebraic summation methods in the seismic analysis ofsafety-related piping for Millstone Unit No. 2.


Since Bechtel has not employed these techniques, this question does not apply.


The computer code used by the Caithersburg Power Division in the seismicstress analysis of safety-related piping for Millstone Unit No. 2 was ME 632" Seismic Analysis of Piping Systems", Bechtel Power Corporation program. ME 632has been verified using PISOL, PIPESD, and TPIPE. PISOL is the EDS MuclearIncorporated, program. PIPESD is the John Blume of San Francisco program.

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TPIPE is PMB Systems Engineering, Incorporated, program. All of these programshave been verified by at least one, and in most cases, more than one, othercomputer program to verify that these programs yield appropriate results.


Since Bechtel did not employ any of these techniques, this question is not ,

applicable.

Work Performed by Teledyne Engineering Services


TES did not use algebraic summation for combining :ne effects of orthogonalcomponents of earthquake motion. The actual methodology used is delineated inthe response to Question (3).


TES did not employ algebraic summation techniques, therefore, this questiondoes not apply.


The computer program used by TES for seismic analyses of piping at MillstoneUnit No. 2 was ADLPIPE. TES has used a technique of running esrthquake,directions separately and combining resultant effects (forces, moments,deflections) outside the computer program as follows:

The representative maximum value of the three moments Mx, M , and Mz atyany point in the piping system subjected to each of the three independentspatial component response spectra was obtained by taking an SRSS summa-tion of the modal responses for all significant modes of the system.Mathematically, this is expressed as follows:

N 1/2M =[I M

3 3] (1)k=1 k

where Mj is the representative maximuu value of moment, j is the momentcomponent digetion x, y, or z. Mj k is the peak value of moment componentdue to the k mode, and N is the number of significant modes.

The combined effect of the three spatial components of earthquake wasdetermined subsequently by the folJowing procedure. The representativemaximum values of the codirectional moments (either Mx, My, and Mz) fromthe two horizontal components of earthquake were combined by the SRSSmethod and this SRSS value then added absolutely to the representativemaximum value of the codirection moment for the vertical component ofearthquake . Mathematically, this is expressed as

M = (:(M ) + 01 ) ] + 01 )Yj j 3 3

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where M is the total seismic moment component Mx, M , or Mz, (Mj )X ,Y ,Zj yare the representative maximum values of codirectional moments (SRSSvalues) for each of the X, Y, Z carthquake directions, respectively.Since all terms are SRSS values, they all possess a positive sign.

Important steps in the verification of ADLPIPE, as supplied by A. D. LittleCompany, are as follows:

Verification of ADLPIPE was undertaken in a series of fundamental checks.In important modifications, a supporting document was prepared asnan ADLPIPEreference. The verification procedure was as follows.

The thermal and deadweight loadings were checked by a Hovgaard Bend and handcalculated systems given in " Design of Piping Systems", M. W. Kellogg,Second Edition,1956, and " Formulas of Stress and Strain", R. J. Roark,McGraw-Hill .

The dynamic analyses were checked by " Response of Structural Systems toGround Shock", Shock and Structural Response, ASME,1960, in "ADLPIPE

- Results of Model Given by Young (ADLPIPE Reference 4), and " DynamicBehavior of a Foundation-Like Structure", Mechanical Independence Methods,ASME,1958, in " Experimental Verification of ADLPIPE Mod 1" (ADLPIPEReference 3).

The time history analysis was checked by a separate analytical solution ofthe problem given in " Analytical Methods of Vibrations" Page 395, LeonardMeinovitch, "ADLPIPE Time History Response Compared with a Known Solution fora Heavily Damped System (ADLPIPE Reference 14). A second check was made using" Pressure Vessel and Piping 1972 Computer Progress Verification", ASME,1972(Problem 5).

The thermal transient analysis was verified by a separate analysis, " TransientThermal Gradient Stresses", E. B. Branch, Heating, Piping, and Air Conditioning,Volume 43,1971, Pages 132 - 136, "ADLPIPE Thermal Transient Analysis" (Reference 15) .

The computation of intra and inter modal moment component summation has beenverified by a separate computer program for that purpose. A report "ADLPIPEModal Response Combination for Closely Spaced Modes", is available as ADLPIPEReference 24.

Various calculation procedures required by ASME Section III were verified inADLPIPE References 10,11, and 18 entitled "ADLPIPE Computation of Bending Stressin Tees and Branch Connections, ASME Section III, Class 1 Piping", "ADLPIPEComputation of Resultant Moments for Section III Class 2 and 3 Stresses", and"ADLPIPE Stress Computation of Piping Components: A Comparison with HandCalculations for ANSI B31 and ASME Section III".

In 1978, an independent C.ird party review of ADLPIPE (Section III, Class 1)was performed " Verification of ADLPIPE, ASME Section III, Class 1 Piping StressProgram", Teledyne Engineering Services, Report No TE-2884-1, August 11, 1978.

It is NNECO's understanding that further information on this subject has beensupplied by A. D. Little to the NRC Staff in a memorandum, dated April 19, 1979,and, therefore, this information has not been included within. TES has alsocoapared results of problems analyzed using IMRSAP and ADLPIPE. TMRSAP is

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a TES proprietaty version of SAP IV, in which pre- and post-processingopcions were added by TES. No changes were made to the basic SAP IV program.IMRSAP has been completely verified and a verification report is on file inthe TES QA Document Control files. A sample of the results from a comparisonanalysis by TES follows:

Comparison of ADLPIPE and THRSAP Seismic Stresses for PIPDYNManual example problem that is also used in SAP IV Manual.

X - Direction Seismic Spectral Loading, B31.1 Stress Summary

Mode Intensification ADLPIPE THRSAPNumber Component Factor Stress, psi Stress, psi

3 Run 1.00 411 4093 Elbow 2.80 1122 11464 Elbow 2.80 1105 11084 Run 1.00 397 3958 Branch 1.00 896 8949 Run 1.00 537 5379 Elbow 2.71 1448 1452

Note that ef fects of orthogonal components of earthquake motion were combinedoutside the computer programs for both the verification cases and the originalanalyses performed by TES. The methodology used internally by the computerprogram for combining effects of orthogonal components of earthquake motion is,therefore, irrelevant for these cases.


Since TES has not employed these techniques, this question does not apply.

Backfit Proj ects Involving Safety-Related Piping

Backfit projects involving modifications to or additions of safety-related pipingwere investigated to determine applicability of the subject I&E Bulletin. Sixinstances of seismic analyses of safety related piping performed by NortheastUtilities Service Company were identified.

Work Performed by Northeast Utilities Service Company


The six analyses performed by Northeast Utilities Service Company were done usingthe computer program ADLPIPE. The method of combining responses of orthogonalcomponents of earthquake excitation using algebraic summation techniques hasbeen used in these cases.


A computer program listing for the dynamic response portions of ADLPIPE have notbeen included as a portion of this response.

Ibrtheast Utilities Service Company has been in contact with A. D. Little (ownersof ADLPIPE) and have recently received permission from them to provide this re-quested information.

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However, transmittal of this information is not provided at this time in orderto respond to your request in a timely fashion. Transmittal of this informa-tion would involve an affidavit pursuant to 10CFR2.790, and is consideredsuperfluous as it is NNECO's understanding that the intent of your requesthas been fulfilled by representatives of A. D. Little during meetings withthe NRC Staff.

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Important steps in the verification of ADLPIPE are as follows:

Verification of ADLPIPE was undertaken in a series of fundamental checks. In

important modifications, a supporting document was prepared as an ADLPIPEreference. The verification procedure was as follows.

The thermal and deadweight loadings were checked by a Hovgaard Bend and handcalculated systems given in " Design of Piping Systems", H. W. Kellogg, SecondEdition,1956, and " Formulas of Stress and Strain", R. J. Roark, McGraw-Hill.

The dynamic analyses were checked by " Response of Structural Systems to GroundShock", Shock and Structural Response, ASME,1960, in "ADLPIPE Results of ModelGiven by Young (ADLPIPE Reference 4), and " Dynamic Behavior of a Foundation-LikeStructure", Mechanical Independence Methods, ASME,1958, in " Experimental Verifica-tion of ADLPIPE Mod 1" (ADLPIPE Reference 3).

The time history analysis was checked by a separate analytical solution of theproblem given in " Analytical Methods of Vibrations", Page 395, Leonard Meinovitch,"ADLPIPE Time History Response Compared with a Known Solution for a HeavilyDamped System (ADLPIPE Reference 14). A second check was made using " PressureVessel and Piping 1972 Computer Progress Verification", ASME,1972 (Problem 3).

The thermal transient analysis was verified by a separate analysis, " TransientThermal Gradient Stresses", E. B. Branch, Heating, Piping, and Air Conditioning,Volume 43, 1971, Pages 132 - 136, "ADLPIPE Thermal Transient Analysis" (Reference 15).

The computation of intra and inter modal moment component au=mation has beenverified by a separate computer program for that purpose. A report "ADLPIPE ModalResponse Combination for Closely Spaced Modes", is available as ADLPIPE Ref erence 24.

Various calculation procedures required by ASME Section III were verified inADLPIPE References 10,11, and 18 entitled , "ADLPIPE Computation of BendingStress in Tees and Branch Connections, ASME Section XII, Class 1 Piping","ADLPIPE Computation of Resultant Moments for Section III C. ass 2 and 3 Stresses",and "ADLPIPE Stress Computation of Piping Components" A Comparison with HandCalculations for ANSI B31 and ASME Section III".

In 1978, an independent third party review of ADLPIPE (Section III, Class 1) wasperformed " Verification of ADLPIPE, ASME Section III, Class 1 Piping Stress Program",Teledyne Engineering Services, Report No. TE-2884-1, August 11, 1978.

It is NNECO's understanding that further information regarding ADLPIPE verificationand methodology have been presented by A. D. Little to the NRC Staf f during anApril 16, 1979 meeting and in a memorandum dated April 19, 1979. Therefore, welave not included this additional information as a part of this response.

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The piping systems which were seismically analyzed using the technique identi-fled in Response 1 are:

(1) Volume Control Tank Charging Bypass Lines

(2) Nitrogen Addition System(3) Charging System(4) Diesel Generator Exhaust Piping(5) Reactor Coolant Pump Tap Root Valve Instretentation Lines

(6) Safety Injection and Containment Spray Test Line

NNECO is currently assessing the adequacy of the existing installations. Apreliminary analysis of the piping system using the SRSS technique of combiningresponses of orthogonal earthquake motion in ADLPIPE has indicated resultantstress levels in the piping are within allowable limits. NNECO is presentlyreviewing effects of the revised analyses on piping restraints and equipmentat tachments. The evolution with be completed and a supplement to this responsewill be submitted prior to the start of Cycle 3 operation.

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responds to ie bulletin 79-07 re seismic stress analyses

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