ML19270G086
| ML19270G086 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/24/1979 |
| From: | Counsil W NORTHEAST UTILITIES |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| TAC-46174, NUDOCS 7906020210 | |
| Download: ML19270G086 (9) | |
Text
.
7 r
rygg NOltTHI!A!iT UFII.ITII!!i r;;e;ti
]
'd 2 7.-i$ $ E $: *E I A FORD. CONNECTICUT 06101
"' :::::lL';.';;l;"::**
am) wen L
c A
';*r'7;;:l ':::::::
April 24, 1979 Docket No. 50-336 Mr. Boyce H. Grier Director, Region I Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission King of Prussia, PA 19406 Gentlemen:
Millstone Nuclear Power Station, Unit No. 2 IE Bulletin 79-07 In response to IE Bulletin No. 79-07 regarding seismic stress analyses of safety-related piping, the attached information is hereby submitted.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY
/
W. G. Counsil Vice President Attachment 2268 3
7906020%\\o
e.
e.
DOCKET No. 50-336 MILLSTONE NUCLEAR POWER STATION, UNIT No. 2 RESPONSES TO I&E BULLETIN 79-07 2268 218 APRIL, 1979
Seismic analyses of safety-related piping for the original plant design were performed by three organizations. Combustion Engineering performed seismic analyses of the Reactor Coolant System loop piping and pressurizer surge line piping. Teledyne Engineering Services perf ormed seismic analyses of all other ASME Section III Class 1 piping systems.
Bechtel Corporation performed seismic analyses of ASME Section III Class 2 and 3 and all other Seismic Category I piping.
IE Bulletin 79-07 requests information intended to allow the NRC to determine whether algebraic summation techniques were used in the design of safety-related piping. The information requested is paraphrased below in the form of four questions:
Question (1)
Identify which, if any, of the methods specified were employed for the seismic analysis of safety-related piping in your plant and provide a list of safety systems affected.
Question (2)
Provide complete computer program listings for the dynamic response analysis portions for the codes which employed the techniques identified in Item 1 above.
Question (3)
Verify that all piping computer programs were checked against either piping benchmark problems or compared to other piping computer programs.
You are requested to identify the benchmark problems and/or the computer programs that were used for such verifications or describe in detall how it was determined that these programs yielded appropriate results (i.e., gave results which corresponded to the correct performance of their intended methodology).
Question (4)
If any of the methods listed in Item 1 are identified, submit a plan of action and an estimated schedule for the re-evaluation of the safety-related piping, supports, and equipment affected by these analysis tcchniques. Also provide an 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 by responsible organization:
Work Performed by Combustion Engineering Response to Question (1)
CE has never used algebraic summation for combining the ef fects of horizontal and vertical seismic excitations.
Response to Question (2)
Since CE has not employed these techniques, this question does not apply.
??G3 i9
. Response to Question (3)
Time histories of the six components of force or moment (F, F, F, Mx, M, Mz) x y
2 y
at various sections of the reactor coolant system main loop piping were computed separately for each of two horizontal and the vertical directions of seismic excitation.
Each component of force or moment from one horizontal direction of excitation was combined by absolute summation on a time basis with the corresponding codirectional component of force or moment from the vertical direction of excitation. The maximum combined value over all time of each of the six components of force or moment were chosen to define the seismic loading condition at the particular piping location for one horizontal and the vertical excitations. A second seismic loading condition was also defined by repeating the 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 seismic loadings specified for design of the piping.
Since the combination of loads was performed 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 supports y
and various sections of the pressurizer surge line piping were computed separately for each of two horizontal and the vertical directions of seismic excitation by response spectrum dynamic analysis. The codirectional components of force or moment from one horizontal and the vertical directions of excitation were com-bined by absolute summation to define the seismic loading condition at the particular piping location for one horizontal and the vertical excitatio~...
A second seismic loading condition was also defined by repeating the ab,tolute sum combination for the other horizontal and the vertical excitations.
Each load set was compared to, and shown to be less governing than, the seismic loadinga specified for design of the piping.
The load combinations were calculated and verified by l'7d.
Response to Question (4)
Since CE does not use any of these techniques, this question is not applicable.
Work Performed by Bechtel Corporation Response to Question (1)
Bechtel did not employ algebraic summation methods in the seismic analysis of safety-related piping for Millstone Unit No. 2.
Response to Question (2)
Since Bechtel has not employed these techniques, this question does not apply.
Response to Question (3)
The computer code used by the Caithersburg Power Division in the seismic stress analysis of safety-related piping for Millstone Unit No. 2 was ME 632
" Seismic Analysis of Piping Systems", Bechtel Power Corporation program. ME 632 has been verified using PISOL, PIPESD, and TPIPE. PISOL is the EDS Muclear Incorporated, program. PIPESD is the John Blume of San Francisco program.
2268 320
. TPIPE is PMB Systems Engineering, Incorporated, program. All of these programs have been verified by at least one, and in most cases, more than one, other computer program to verify that these programs yield appropriate results.
Response to Question (4)
Since Bechtel did not employ any of these techniques, this question is not applicable.
Work Performed by Teledyne Engineering Services Response to Question (1)
TES did not use algebraic summation for combining :ne effects of orthogonal components of earthquake motion. The actual methodology used is delineated in the response to Question (3).
Response to Question (2)
TES did not employ algebraic summation techniques, therefore, this question does not apply.
Response to Question (3)
The computer program used by TES for seismic analyses of piping at Millstone Unit 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 at y
any point in the piping system subjected to each of the three independent spatial 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 1/2 M =[I M 3
3]
(1) k=1 k
where Mj is the representative maximuu value of moment, j is the moment component digetion x, y, or z.
Mj k is the peak value of moment component due to the k mode, and N is the number of significant modes.
The combined effect of the three spatial components of earthquake was determined subsequently by the folJowing procedure. The representative maximum values of the codirectional moments (either Mx, My, and Mz) from the two horizontal components of earthquake were combined by the SRSS method and this SRSS value then added absolutely to the representative maximum value of the codirection moment for the vertical component of earthquake. Mathematically, this is expressed as M = (:(M ) + 01 ) ]
+ 01 )Y j
j 3
3 2263 21
. where M is the total seismic moment component Mx, M, or Mz, (Mj )X,Y,Z j
y are the representative maximum values of codirectional moments (SRSS values) 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. Little Company, are as follows:
Verification of ADLPIPE was undertaken in a series of fundamental checks.
In important modifications, a supporting document was prepared asnan ADLPIPE reference. The verification procedure was as follows.
The thermal and deadweight loadings were checked by a Hovgaard Bend and hand calculated 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 to Ground Shock", Shock and Structural Response, ASME,1960, in "ADLPIPE Results of Model Given by Young (ADLPIPE Reference 4), and " Dynamic Behavior of a Foundation-Like Structure", Mechanical Independence Methods, ASME,1958, in " Experimental Verification of ADLPIPE Mod 1" (ADLPIPE Reference 3).
The time history analysis was checked by a separate analytical solution of the problem given in " Analytical Methods of Vibrations" Page 395, Leonard Meinovitch, "ADLPIPE Time History Response Compared with a Known Solution for a 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, " Transient Thermal 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 been verified by a separate computer program for that purpose. A report "ADLPIPE Modal Response Combination for Closely Spaced Modes", is available as ADLPIPE Reference 24.
Various calculation procedures required by ASME Section III were verified in ADLPIPE References 10,11, and 18 entitled "ADLPIPE Computation of Bending Stress in Tees and Branch Connections, ASME Section III, Class 1 Piping", "ADLPIPE Computation of Resultant Moments for Section III Class 2 and 3 Stresses", and "ADLPIPE Stress Computation of Piping Components: A Comparison with Hand Calculations 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 Stress Program", Teledyne Engineering Services, Report No TE-2884-1, August 11, 1978.
It is NNECO's understanding that further information on this subject has been supplied 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 also coapared results of problems analyzed using IMRSAP and ADLPIPE. TMRSAP is 2268 22
. a TES proprietaty version of SAP IV, in which pre-and post-processing opcions 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 in the TES QA Document Control files. A sample of the results from a comparison analysis by TES follows:
Comparison of ADLPIPE and THRSAP Seismic Stresses for PIPDYN Manual example problem that is also used in SAP IV Manual.
X - Direction Seismic Spectral Loading, B31.1 Stress Summary Mode Intensification ADLPIPE THRSAP Number Component Factor Stress, psi Stress, psi 3
Run 1.00 411 409 3
Elbow 2.80 1122 1146 4
Elbow 2.80 1105 1108 4
Run 1.00 397 395 8
Branch 1.00 896 894 9
Run 1.00 537 537 9
Elbow 2.71 1448 1452 Note that ef fects of orthogonal components of earthquake motion were combined outside the computer programs for both the verification cases and the original analyses performed by TES. The methodology used internally by the computer program for combining effects of orthogonal components of earthquake motion is, therefore, irrelevant for these cases.
Response to Question (4)
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 piping were investigated to determine applicability of the subject I&E Bulletin.
Six instances of seismic analyses of safety related piping performed by Northeast Utilities Service Company were identified.
Work Performed by Northeast Utilities Service Company Response to Question (1)
The six analyses performed by Northeast Utilities Service Company were done using the computer program ADLPIPE. The method of combining responses of orthogonal components of earthquake excitation using algebraic summation techniques has been used in these cases.
Response to Question (2)
A computer program listing for the dynamic response portions of ADLPIPE have not been included as a portion of this response.
Ibrtheast Utilities Service Company has been in contact with A. D. Little (owners of ADLPIPE) and have recently received permission from them to provide this re-quested information.
2268
'23
. However, transmittal of this information is not provided at this time in order to respond to your request in a timely fashion. Transmittal of this informa-tion would involve an affidavit pursuant to 10CFR2.790, and is considered superfluous as it is NNECO's understanding that the intent of your request has been fulfilled by representatives of A. D. Little during meetings with the NRC Staff.
Response to Question (3)
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 ADLPIPE reference. The verification procedure was as follows.
The thermal and deadweight loadings were checked by a Hovgaard Bend and hand calculated systems given in " Design of Piping Systems", H. 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 to Ground Shock", Shock and Structural Response, ASME,1960, in "ADLPIPE Results of Model Given by Young (ADLPIPE Reference 4), and " Dynamic Behavior of a Foundation-Like Structure", 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 the problem given in " Analytical Methods of Vibrations", Page 395, Leonard Meinovitch, "ADLPIPE Time History Response Compared with a Known Solution for a Heavily Damped System (ADLPIPE Reference 14). A second check was made using " Pressure Vessel and Piping 1972 Computer Progress Verification", ASME,1972 (Problem 3).
The thermal transient analysis was verified by a separate analysis, " Transient Thermal 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 been verified by a separate computer program for that purpose. A report "ADLPIPE Modal Response Combination for Closely Spaced Modes", is available as ADLPIPE Ref erence 24.
Various calculation procedures required by ASME Section III were verified in ADLPIPE References 10,11, and 18 entitled, "ADLPIPE Computation of Bending Stress 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 Hand Calculations for ANSI B31 and ASME Section III".
In 1978, an independent third party review of ADLPIPE (Section III, Class 1) was performed " 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 verification and methodology have been presented by A. D. Little to the NRC Staf f during an April 16, 1979 meeting and in a memorandum dated April 19, 1979. Therefore, we lave not included this additional information as a part of this response.
2268 224
. Response to Question (4)
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. A preliminary analysis of the piping system using the SRSS technique of combining responses of orthogonal earthquake motion in ADLPIPE has indicated resultant stress levels in the piping are within allowable limits.
NNECO is presently reviewing effects of the revised analyses on piping restraints and equipment at tachments. The evolution with be completed and a supplement to this response will be submitted prior to the start of Cycle 3 operation.
2268 ;25