ML20086C047

Clarifies Use of Methodologies Needed Primarily for Reanalysis of Main Steam Lines in Conjunction W/Steam Generator Replacement

ML20086C047
Person / Time
Site:	Mcguire, Catawba, McGuire
Issue date:	06/30/1995
From:	Tuckman M DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9507060253
Download: ML20086C047 (7)

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DukeIbwerCompany M S naus

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Senior Vice1+esident Quarlotte,NC2820M006 NudearGeneration (TN)3822200 Onice (TM)3824%0 Fax DUFG? POWER June 30,1995 i

U. S. Nuclear Regulatory Commission Attention: Document Control Desk j

Washington, DC 20555

Subject:

Catawba Nuclear Station, Units 1 & 2, Docket Nos. 50-413 and -414 McGuire Nuclear Station, Units 1 and 2, Docket Nos. 50-369 and 370 Request for Approval of Seismic Analysis Methodology l

By letter dated March 10,1995, Duke Power Company requested approval.

for use of alternative seismic methodologies that have been developed since the facility operating license reviews. As discussed in that letter, these l

methodologies are needed primarily for reanalysis of the main steam lines in j

conjunction with steam generator replacement. The purpose of this letter is to clarify our intended use of these methodologies.

i Since the March 16,1995 submittal, additional applications for the i

Independent Support Motion (ISM) and CREST methodologies have been identified. This includes analysis of the Nuclear Sampling piping which is being rerouted due to steam generator replacement. Other applications for i

the ISM and CREST methodologies are expected with future station modifications. Proposed updates to the McGuire and Catawba FSAR's are provided as Attachments 1 and 2.

It is therefore requested that the NRC's review and approval of the three seismic methodologies discussed in the March 16,1995 submittal not be limited to use for main stream line reanalysis, but be approved for use as described in the updated Final Safety Analysis Reports.

Please contact R. O. Sharpe at (704) 382-0956 if you have any questions.

Very truly yours, (TC A yu,.~-

M. S. Tuckman 9507060253 950630 PDR ADDCK 05000369 P

PDR an.s on es.-

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d. S. Nuclear Regulatory Commission June 30,1995 i

Page 2 Attachments i

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S. D. Ebneter Regional Administrator, Region II l

U. S. Nuclear Regulatory Commission i

101 Marietta Street, NW, Suite 2900 Atlanta, GA 30323 i

R. J. Frudenburger Senior Resident Inspector l

Catawba Nuclear Station G. F. Maxwell Senior Resident Inspector McGuire Nuclear Station f

R.E. Martin Project Manager, ONRR V. Nerses Project Manager, ONRR i

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i Duke Power Company Steam Generator Replacement Project McGuire Nuclear Station i

Proposed FSAR Update 3.7.2.1.3 Alternative Analysis Methodologies As an alternative to the method described in Section 3.7.2.1.2 of the McGuire

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FSAR, a coupled analysis or the independent support motion methodology l

may be used. A coupled methodology is a refined analysis which incorporates primary structures, typically the building structure but may also include the f

reactor coolant loop (RCL), with the secondary system, i.e. piping. Two different coupling methodologies may be used in the analysis of piping i

systems.

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3.7.2.1.3.1 Coupled Analysis of RCL Piping

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This seismic analysis methodology extends the primary RCL model which includes the building structure to include additional piping. Model r

boundaries are extended to other subsystems through the use of decoupling, i

overlapping, isolation or the use ofintermediate anchors. Modal combinations, damping and codirectional combinations associated with the RCL model (described in Section 3.9.1.5) are applied to the added piping.

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3.7.2.1.3.2 Coupled Analysis of Piping Using CREST Methodology l

l This seismic analysis methodology considers the coupling of two structural systems: a primary structure, e.g. that which includes the Reactor Interior i

Structure and the RCL piping / components and a secondary structure, e.g.

that which includes the connected piping. The seismic analysis is performed using the CREST computer program which was developed at the Center for Nuclear Power Plant Structures, Equipment and Piping, North Carolina State University. In the formulation of the program, the coupled primary-secondary system's equation of motion is linearly transformed using the mode shapes of the uncoupled systems. This transformation is exact. The coupled frequencies, damping ratios and mode shapes are evaluated using a

- modal synthesis procedure. A response spectrum analysis of the coupled iI

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shstems is performed. A detailed description of the CREST methodology is given in References 19,20, and 21.

The basic formulation for the modal coupled response, the development of the coupled modal properties, and the calculation of the coupled response is _

i provided in Reference 19, Articles G.1 - G.5. See also Section 4 of Reference -

21. Modal combinations are performed using a double-sum methodology as given in Chapter 5, Article 5.6 of Reference 19. Correlation coellicients associated with modal combinations are provided in Reference 20. The effects of residual rigid response are considered as described in Reference G.

The total seismic response is obtained by the SRSS of the X, Y and Z directional responses.

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i 3.7.2.1.3.3 Independent Support Motion Methodology j

A piping subsystem which is supported in more than one building structure and / or is supported at varying elevations within a single structure may be analyzed using the independent support motion (ISM) methodology. Inertial response as well as relative anchor motion effects are combined to determine the total response of the piping. For the inertial response, the ISM methodology allows the specific input of response spectra at the support locations. Supports are classified into groups or levels based on structure and elevation. X, Y and Z direction spectra are correlated to each group and input in the analysis as applied loadings. For each direction, the response is calculated based on the absolute sum of the group responses and a SRSS modal combination methed induding missing mass effects. The totalinertial response is determined by the SRSS of the directional responses. For the relative anchor motion effects, a static analysis is performed. The inertial i

and anchor motion responses are developed by the SRSS combination. This methodology conforms to that described in NUREG-1061 (Reference 22).

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t References l

i 19.

Gupta, A. K., Response Spectrum Method, Blackwell,1990, CRC Press, 1992; Chapter 5: Article 5.G; Chapter 6: Articles G.1 - G.5 4

l 20.

Gupta, A. and Gupla, A. K., Recent Improvements in the CREST-IRS l

Program, Center for Nuclear Power Plant Structures, Equipment and Piping, December,1993; Sections 2,3 and 4.

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- Gupla, A. and Gupta, A. K., Coupled Analysis of Piping Systems Including the Effect of High Frequency Modes, Center for Nuclear Power Plant Structures, Equipment and Piping,1994.

22.

NUREG-1061, Volume 4, Report of the U. S. Nuclear Regulatory Commission Piping Review Committee, Evaluation of Other Dynamic Loads and Load Combinations, Section 2.4.1.

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a Duke Power Company Steam Generator Replacement Project Catawba Nuclear Station Proposed FSAR Update 3.7.3.1.1 Alternative Analysis Methodologies As an alternative to the method described in Section 3.7.3.8 of the Catawba FSAR, a coupled analysis or the independent support motion methodology may be used. A coupled methodology is a refined analysis which incorporates primary structures, typically the building structure but may also include the reactor coolant loop (RCL), with the secondary system, i.e. piping. Two different coupling methodologies may be used in the analysis of piping systems.

3.7.3.1.1.1 Coupled Analysis of RCL Piping This seismic analysis methodology extends the primary RCL model which includes the building structure to include additional piping. Model i

boundaries are extended to other subsystems through the use of decoupling, overlapping, isolation or the use ofintermediate anchors. Modal i

combinations, damping and codirectional combinations associated with the RCL model (described in Section 3.9.1.4.4) are applied to the added piping.

3.7.3.1.1.2 Coupled Analysis of Piping Using CREST Methodology This seismic analysis methodology considers the coupling of two structural systems: a primary structure, e.g. that which includes the Reactor Interior l

Structure and the RCL piping / components' and a secondary structure, e.g.

l that which includes the connected piping. The seismic analysis is performed using the CREST computer program which was developed at the Center for Nuclear Power Plant Structures, Equipment and Piping, North Carolina

- State University. In the formulation of the program, the coupled primary-i i

secondary system's equation of motion is linearly transformed using the mode shapes of the uncoupled systems. This transformation is exact. The coupled frequencies, damping ratios and mode shapes are evaluated using a modal synthesis procedure. A response spectrum analysis of the coupled

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~s'ystems is performed. 'A detailed description of the CREST methodology is given in References 34,35, and 36.

l The basic formulation for the modal coupled response, the development of the coupled modal properties, and the calculation of the coupled response is provided in Reference 34, Articles 6.1 - 6.5. See also Section 4 of Reference

35. Modal combinations are performed using a double-sum methodology as i

given in Chapter 5, Article 5.6 of Reference 34. Correlation coefficients

. associated with modal combinations are provided in Reference 35. The effects of residual rigid response are considered as described in Reference 36.

j The total seismic response is obtained by the SRSS of the X, Y and Z directional responses.

3.7.3.1.1.3 Independent Support Motion Methodology A piping subsystem which is supported in more than one building structure and / or is supported at varying elevations within a single structure may be

. analyzed using the independent support motion (ISM) methodology. Inertial response as well as relative anchor motion effects are combined to determine the total response of the piping. For the inertial response, the ISM methodology allows the specific input of response spectra at the support i

locations. Supports are classified into groups or levels based on structure and elevation. X, Y and Z direction spectra are correlated to each group and input in the analysis as applied loadings. For each direction, the response is calculated based on the absolute sum of the group responses and a SRSS modal combination method including missing mass effects. The total inertial response is determined by the SRSS of the directional responses. For the relative anchor motion effects, a static analysis is pdormed. The inertial and anchor motion responses are developed by the SRSS combination. This methodology conforms to that described in NUREG-1061 (Reference 37).

References 34.

Gupta, A. K., Response Spectrum Method, Blackwell,1990, CRC Press, 1992; Chapter 5: Article 5.6; Chapter 6: Articles 6.1 - 6.5 35.

Gupta, A. and Gupta, A. K., Recent Improvements in the CREST-IRS Program, Center for Nuclear Power Plant Structures, Equipment and Piping, December,1993; Sections 2,3 and 4.

i

'iG.

Gupla, A. and Gupla, A. K., Coupled Analysis of Piping Systems Including the Effect of High Frequency Modes, Center for Nuclear Power Plant Structures, Equipment and Piping,1994.

37.

NUREG-1061, Volume 4, Report of the U. S. Nuclear Regulatory i

Commission Piping Review Committee, Evaluation of Other Dynamic Loads and Load Combinations, Section 2.4.1.

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