ML19225A417

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Responds to IE Bulletin 79-07 Re Seismic Analysis of safety-related Piping.Forwards Sargent & Lundy 790518 Ltr Re Bulletin.Facility Seismic Analysis Programs Do Not Employ Algebraic Techniques Described in Bulletin
ML19225A417
Person / Time
Site: Zimmer
Issue date: 05/25/1979
From: Borgmann E
CINCINNATI GAS & ELECTRIC CO.
To: James Keppler
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 7907190151
Download: ML19225A417 (6)
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                                                                                           "- :        ~'T THE CINCINNATI GAS & ELECTRIC. C OM PANY CIN CIN N ATI. O H tO 4 5 201 May 25,1979 J,.^i.*o .7 " ^. " "

U.S. Regulatory Commire't Office of Inspection an< Enforcement Region III 7999 Roosevelt Road Glen Ellyn, Illinois 60137 ATTN: Mr. James G. Keppler Regional Director RE: WM. H. ZIMMER NUCLEAR POWER STATION - UNIT 1 IE BULLETIN 79-07, SEISMIC STRESS ANALYSIS OF SAFETY-RELATED PIPING, DOCKET 50-358, W.0. 57300, JOB E-5590, FILE # 91 Gentlemen: In response to your request please find the following information: Attachment (1) - S&L letter SLC-12855 dated May 18, 1979. We believe this information provides a complete response to the subject NRC IE Bulletin. Very truly yours, THE CINCINNATI GAS & ELECTRIC COMPANY g~ee - E.A. BORGMANN, SENIOR VICE PRESIDENT RWR/kjd ENCLOSURE cc: NRC Office of Inspection and Enforcement Division of Reactor Inspection Programs Washington, D.C. 20555 th J ' 

                                            ' 3 1 1979                    790719 e / b                    G

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  • 312 2 $ 9-2000 ana-aeo sero caeLE acomEss - r sacuw-cmcaso SLC-12855 May 18, 1979 The' Cincinnati Gas & Electric Company I ,7 : C 2 . _J
.1 . . . . . . _ .
                                                                                                   . i--

Reply to NRC IE Bulletin Number 79-07 IO.d. 41 ! - Mr . E . A. Borgmann 

                                                                              ...._. S. _t _h_ _D Senior Vice President                                            "'5                        i              i The Cincinnati Gas & Electric Cengany
                                                                      ~,e      't P. O. Box 960                                                                   '

Cincinnati, Ohio 45201  ! I

Dear Mr. Borgmann :

                                                                                                             ]

The attached enclosure is in response to NRC IE Bulletin 79 Seismic Stress Analysis of Safety-Related Piping and is a retransmittal of information sent on May 2, which apparently was not received. The enclosure is for your transmittal to the NRC. . Please contact us if there are any questions. Very truly yours, I V I C R) F. Scheibel Project Director RFS:klm In triplicate Enclosure Copies: R. J. Pruski (1/1) i ju, 

                                                                                                                  ------..w.

l - r' 

 .         .                                                     i g                                      lr PRELIMINAov orPLY TO NRC IE SULLETIN NO. 79-07 4

April 23, 1979 

                           .,   SEISMIC STRESS ANALYSIS OF (SAFETY-NELATED PIPING I

V In IE Bulletin No. 79-07, dated April 14, 1979 the NRC raised . questions concerning the methods of combination of earthcuake directional response used for piping analysis for safety 

                                                                                                                                ^

related piping systems in both operaring nuclear plants and plants under constructicn. As the result of an investigation of stress analysis performed by an. eastern based AE, the NRC ordered the shutdown of five nuclear stations when it was found that earthcuake directional response (X,Y,Z direction) in the piping analyses were added algebraically at the modal level i.e., mode by mode. This resulted in some cancelling effect for the signed todal responses for a given local component of load. In some cases the calculated piping stresses and restraint and support loacs were reportedly underestimated by as much as' 50%. The Dynapipe and PIPSYS programs that Sargent & Lundy used or currently uses for the seismic analysis of piping-systems were developed independently of programs used by other AE's and other programs that were and are commercially avcilable. Therefore, it is unlikely that any similar errors would be repeated in the Sargenr & Lundy oiping analysis. Turthermere, the Sargent & Lundy programs work first with each direction of response (x, Y or :) and combine modal responses for a given direction per applicable regulatcry guace r?quirements. The combined responses for each directica 

                         . - are then added by the SRSS method. Thus the cancelling effect experienced in the piping analysis : cr the plants the NRC shut d wn does not occur in the sargent & Lundy sciamic enclysis.               -

In Bulletin Mc. 79-07 the NRC recuests responses to four .. ' 

                             .cpecific ection items regarding the seismic analysis of safety related pipin,.                  Those action items along with appropriate responses are proviced in the following:                                                             -

(1) . t e+ .' T - t I 

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NRC, Item ,(1) Identify which, if any of the methods s'pecified h .r below were employed or were used in computer a codes for the seismic analysis of safety related piping in your plant and provide a list of safety f systers (or portions thereof) affected: Response Spectrum Model Analysis:

a. Algebraic (considering signs) summation of s the codirectional spatial components (i.e.,
                                                      ;                    algebraic summation of the maximum values of the codirectional responses caused by each L

of the components of earthquake motion at a particular point in the mathematical model).

b. Algebraic (considering signs) summation of the
                        ,                                                  codirectional inter model responsec (i.e.,

for the number of modes considered, the maximum values of resconse-for each mode su=ned algebraically). . Time History Analysis:

a. Algebraic summation of thu c c!rectional maximum responses or the time dependent a responses due to each of the com;cnents of
                      ,                                                    earthquake motion ar.cing simultanee . sly when the earthquake- directional motions are not statistica;1y independent.

Reply: The Dynapipe and PIPSYS programs used by Sargent & Lundy for the response spectra seismic analysis of safety :51sted piping do not employ algebraic summation routines for combining responses, either intermod al or for any other component of response. Sargent & Lundy does not use the time history method for the seismic analysis of piping. NRC Item (2) . provide complete computer program listings for the dynamic response analysis portions for the 

   , _ . . _ -                                    *:                   codes which employed the techniques identified:                         -
                                                                                                '               ~            '
                                                                                                                                         "~

in Item 1 above. Reply: 

 .                                                       .             None of the computer programs used by Sargent & Lundy for the seismic ana2ysis of safety related piping employ the algebra 2 c techniques described in

( . item (1), therefore we are not required to submit our computer progra.m listings. ..: 

                                                                                                                                  - a( ")

(2) .});b '" h ** ..e , ft W- ,g 

.                     1
  • g NRC Item (3) Verify that all piping computer programs were checked against either piping benchmark problems or cc= pared to other piping computer programs. You are recuested to identifj the benchmark problems and/or the computer programs that were used for such verifications or describ.

in detail how it was determined that these programs yielded appropriate results (i.e., gave results whien corresponded to the correct performance of their - intended methodology) . Reply: The S&L computer program DYNAPIPE {09.7.052) and PIPSYS (09.5.065) were used in piping seismic analyses. These procrams have a lone histore of use within S&L - e.g. DYNEPIPE since 1969'and PIPSYS since 1972. They have been validated several times during their long history (' of use. For the seismic portions of the program, this has been done by checking computer results by hand calculations, checking results against public domain programs, and by checking results from PIPSYS against DYNAPIPE. Each new version of the c. row ram is extensivelv . checked against the older version through a series of test problems. The following validation procedure was, followed in the initial valifation: A. Check Against DYNAL (1) (1969) 

                                                 . . A typical hot reheat oicing system was analv. ed on DYNAPIPZ anc DYNALt,
                                                                                   . The element forces for a specified response spectra were cc= pared and were found to be cc= parable.          The frecoencies of

, modes 1 through 6 were also in close acreement. - B. Check Against MIC-21 I2)(1969) In 1969, no public-domain seiscic analysis code had the car.abilitv of curved elements to model pipe elbows. To validate this feature of the S&L programs, the piping system given in example 

           . -                     ...             problen No. 2 or the MZC-21 cc=puter code was
                                    .               analyzed by the S&L program.           Seismic analysis was
                                    . .       A    performed using the respense spectrum nethed. . Member
     '                             '      e forces, joint displacements, and j oint inertia-forces were printed for each ccde. The same systen was then analy:ad using the MIC-21 code with a static load ecual to the =cdal inertra-free forces, and joint displacements eb ained frca the two codes were comphred and fotnd to be in good agreement.

(3) I.1 

                                                                                                -y          :,j i
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Mbee wm e 

                , / ..

ed g C. PIPSYS & DYNAPIPE Ccmparison (1972) 

    '                                                          In 1972, when the PIPSYS program was developed, it was extensively benchmarked against the DYNAPIPE program.               Typical piping systems were run on the two programs and found to yield the same
                                      .-                       responses on the two cofes.                                   -

D. PIPSYS & DYNAPIPE Check Anainst DYMAL(1) and I NASTRANtC (1972) In 1972 the todal periods and time history of response to pipe transients using the modal time history method on PIPSYS and DYNAPIPE were checked against those obtained from DYNAL and NASTRAN. Good agreement was cotained in responses from the four codes. b References

1. ICES DYNAL User's Manual, McDonnell-Douglas Automation
2. MEC-21, 7094, "A Piping Flexibility Analysis Progres for the IBM 7090 and 7094," Los Alamos Scientific Laboratory, University of California, 1964. '
3. NASTRAN User's Manual, NASA SP-221.

l In addition Sargent & Lundy would welcome a generic review of our piping program by the NRC Licensing 

      .                                         Staff.                   This review could most effectively be conducted in our offices where all do 2entation and key personnel would be available to the staff.;

i l NRC Item (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 techniques. I Also provide an estimate of the degree to which the capability of the plant to safaly withstand a seismic event in the interim is impacted. 

                     .                     .s
                                             ' Reply:                                           E-                     .

None of the computer programs used by Sargent & Lundy for seismic analysis of safety related piping employ the algebraic techniques described in item (1), ' therefore, no reanalysis of any safety related piping is necessary. 

              '                       o.        --

( . . // / U E. B. M Branch

r. A. K. Singh Associate, Head J Supervisor Engineering Mechanics Division Structural Analytical ,
                                                                                                                    -1 Division                              bl> b  JI'
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____ . . . _ . . _ _ _ _ . . _ _ . . . _ . . . '(4) (-}}

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