ML18221A368

Summary of the July 10, 2018, Category 1 Public Teleconference with Nuscale Power, LLC Design Certification Application Section 3.7 Seismic Design, and 3.8, Design of Category I Structures

ML18221A368
Person / Time
Site:	NuScale
Issue date:	09/17/2018
From:	Amadiz Marieliz Vera NRC/NRO/DLSE/LB1
To:	Samson Lee NRC/NRO/DLSE/LB1
vera m/415-5861
References
Download: ML18221A368 (8)

Text

September 17, 2018 MEMORANDUM TO: Samuel S. Lee, Chief Licensing Branch 1 Division of Licensing, Sitting, and Environmental Analysis Office of New Reactors FROM: Marieliz Vera, Project Manager /RA/

Licensing Branch 1 Division of Licensing, Sitting, and Environmental Analysis Office of New Reactors

SUMMARY

OF THE JULY 10, 2018, CATEGORY 1 PUBLIC TELECONFERENCE WITH NUSCALE POWER, LLC DESIGN CERTIFICATION APPLICATION SECTION 3.7, "SEISMIC DESIGN," AND 3.8, "DESIGN OF CATEGORY I STRUCTURES" The U.S. Nuclear Regulatory Commission (NRC) held a Category 1 public teleconference on July 10, 2018, to discuss Final Safety Analysis Report (FSAR) Tier 2, Chapter 3, Design of Structures, Systems, Components and Equipment, and Sections 3.7, Seismic Design, and 3.8, Designs of Category I Structures, of the NuScale Power, LLC (NuScale) Design Certification. Participants included personnel from NuScale and members of the public.

The public meeting notice can be found in the Agencywide Documents Access and Management Systems under Accession No. ML18187A420. This meeting notice was also posted on the NRC public Website.

The meeting agenda and list of participants can be found in Enclosures 1 and 2, respectively.

The technical issues discussed are included in Enclosure 3.

CONTACT: Marieliz Vera, NRO/ DLSE 301-415-5861

S. Lee 2 Summary:

The purpose of this meeting was to discuss the responses for Requests for Additional Information RAI 8932, Question 03.07.02-4 (ML18120A261, ML18157A262) RAI 8932, Question 03.07.02-6 (ML18142C204) and RAI 8936 Question 03.07.02-7 (ML18031B204). NRC staffs feedback (Enclosure 3) was discussed and NuScale will address the feedback in a supplement to their response.

Docket No.52-048

Enclosures:

1. Meeting Agenda

2. List of Attendees cc w/encls.: DC NuScale Power, LLC Listserv

ML18221A368 *via email NRC-002 OFFICE NRO/DLSE/LB1: PM NRO/DLSE/LB1: LA NRO/DNRL/LB1: PM NAME MVera MMoore MVera DATE 07/31/2018 08/15/2018 09/17/2018 U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC TELECONFERENCE WITH NUSCALE POWER, LLC DESIGN CERTIFICATION APPLICATION SECTION 3.7, "SEISMIC DESIGN," AND 3.8, "DESIGN OF CATEGORY I STRUCTURES" July 10, 2018 10:30 p.m. - 12:00 p.m.

AGENDA Public Meeting 10:30-10:35 a.m. Welcome and Introductions 10:35-11:55 a.m. Discussion of the Request for Additional Information 11:55-12:00 p.m. Public - Questions and Comments Enclosure 1

U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC TELECONFERENCE WITH NUSCALE POWER, LLC DESIGN CERTIFICATION APPLICATION SECTION 3.7, "SEISMIC DESIGN," AND 3.8, "DESIGN OF CATEGORY I STRUCTURES" LIST OF ATTENDEES July 10, 2018 NAME AFFILIATION Marieliz Vera U.S. Nuclear regulatory Commission (NRC)

Manas Chakravorty NRC Pravin Patel NRC Sunwoo Park NRC John Ma NRC Maryam Khan NRC Ata Istar NRC Bhagwat Jain NRC Robert Roche-Rivera NRC Marty Bryan NuScale Power, LLC (NuScale)

Jenni Wike NuScale Josh Parker NuScale J.J. Arthur NuScale Hadi Razavi NuScale Tom Ryan NuScale Kirsten McKay NuScale Mohsin Kahn NuScale Evren Ulku NuScale Sarah Fields Public Enclosure 2

U.S. NUCLEAR REGULATORY COMMISSION CATEGORY 1 PUBLIC TELECONFERENCE WITH NUSCALE POWER, LLC DESIGN CERTIFICATION APPLICATION SECTION 3.7, "SEISMIC DESIGN," AND 3.8, "DESIGN OF CATEGORY I STRUCTURES" Staff Feedback on Request Additional for Information 8932 Question 03.07.02-4 In its April 30, 2018 and June 6, 2018, responses to Request for Additional Information (RAI) 8932, Question 03.07.02-4, the applicant provided a comparison of seismic responses between the direct method (DM) and extended subtraction method (ESM) for the Reactor Building and Control Building, including the transfer functions, ISRS, soil pressures, forces and moments, and relative displacements at key locations.

1. For ISRS, the applicant indicates that a maximum 15 percent difference is observed between the 7P ESM and DM models for both the RXB and CRB. The U.S. Nuclear Regulatory Commission (NRC) staffs concern is that when the 7P ESM underpredicts responses by 15 percent compared to the DM, such difference may not be negligible in establishing equipment seismic demands. Therefore, the applicant should justify how the observed differences in ISRS between the 7P ESM and DM are acceptable and would ensure conservative equipment seismic demands based on the 7P ESM model.

2. The NRC staff notes that the 7P ESM model underpredicts ISRS by 9.9 percent compared to DM at the NPMs North Lug Support (Figures 53 and 56 in April 30, 2018 response; Table 8 in June 6, 2018 response). The NRC staff believes that ISRS at the NPM supports are particularly important because they may represent the input for NPM seismic analysis discussed in NuScale TR-0916-51502 (NPM Seismic Analysis). Please address any potential impact of the underestimated ISRS by the 7P ESM on the NPM design and the resulting equipment seismic demands for the SSCs within the NPM.

3. The applicant proposed a markup that will augment FSAR Section 3.7.2.1.1.3 by including a new subsection entitled, 7P vs Direct Method Comparison. It is noted that, in final safety analysis report (FSAR) Section 3.7.2.1.1.3, an existing subsection entitled, Benchmarking, discusses benchmarking of the 7P model against the 9P model. The NRC staff views that a benchmarking of the 7P model against the DM is more essential than against the 9P model. Therefore, the applicant should consider rearranging and streamlining these affected subsections as appropriate. Comparison between 7P and 9P models may have values and be included in the FSAR; however, 7P versus DM comparison should be emphasized.

4. In the last paragraph of the proposed FSAR markup (Page 3.7-113, Draft Revision 2),

the applicant states, These comparisons show that the 7P and DM differs, at most, 20 percent from each other. Please identify the response quantities that represent 20 percent difference and justify the acceptance of this level of difference (and expand the FSAR markup to include this justification as appropriate).

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5. In the NuScale Closure Plan, the applicant indicated that 4 percent structural damping would be used for ESM-DM benchmarking studies for the RXB and CRB. However, in its RAI response, the applicant indicates that 7 percent damping was used for CRB ISRS generation for a reason given in the RAI response. Please clarify if 7 percent damping was also used for RXB ISRS generation for the ESM-DM benchmarking study. Also confirm that 7 percent damping was used in computing forces and moments for the RXB and CRB.

6. The NRC staff notes certain differences in the applicants responses to RAI 8932, Questions 03.07.02-4 and 03.07.02-6 with respect to the seismic demands shown for the Pilaster finite elements (for the cases of 7P ESM and no soil separation). Explain the reason for the differences or update either or both RAI responses as necessary.

Question 03.07.02-6 In its May 22, 2018 response to RAI 8932, Question 03.07.02-6, the applicant described a sensitivity study and provided an evaluation of soil separation effect on seismic demands for the RXB and CRB.

1. The sensitivity study indicates enhanced ISRS due to soil separation at several locations; e.g. Figure 3.7.2-138 in the proposed FSAR markup (vertical ISRS for a CRB slab) indicates approximately 15 percent increase at the peak due to soil separation; however, no specific discussion of such exceedance is included in the markup. The applicant should discuss this exceedance and potential impact on equipment qualification for the affected floor in the FSAR markup as appropriate.

2. The applicant indicates that increases in seismic structural demands are within the design margins of the building components, leaving the building design unaltered.

Please clarify/confirm whether this finding is applicable when all other concurrent loads are considered together with the increased seismic demands.

3. In the RAI, the NRC staff indicated that when soil separation results in increased seismic demands, such increased demands should be taken into account in establishing the design basis seismic demands. The applicant is requested to evaluate whether the ISRS from the cases of soil separation in the sensitivity study are bounded by the design-basis ISRS envelope (described in FSAR Section 3.7.2.5). In such bounding evaluation, the applicant should make sure that a consistent structural damping value (4 percent or 7 percent) is used. If the increased ISRS due to soil separation are not bounded by the design-basis ISRS envelope, the applicant should provide a method that will ensure conservative equipment seismic demands.

4. It is noted that the sensitivity study was performed using cracked concrete and 7 percent structural damping (FSAR Section 3.7.2.1.1.3, Soil Separation, subsection). Please clarify if the ISRS from the sensitivity study are generated using 7 percent structural damping.

5. The NRC staff notes that no evaluation is included in the RAI response for a reactor building crane support. The NRC staff believes the crane support is a key location and should be included in the list.

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RAI 8936, Question 03.07.02-7 In the RAI response, the applicant is expected to provide information regarding the verification and validation (V&V) of SASSI2010 to the extent it is applied to the NuScale seismic analysis.

Specifically, the applicant should demonstrate that the parameters used in NuScale design-basis seismic demand calculations are within the range of applicability of the SASSI2010 computer program. Parameters to be tested may include the following:

• Mesh sensitivity - evaluation of solutions for different mesh sizes of finite elements

• Aspect ratio - evaluation of solutions for maximum finite element aspect ratio used

• Poissons ratio - evaluation of solutions for maximum Poissons ratio used

• Frequencies of analysis - demonstration that the frequencies of analysis used are adequate

• Impedance functions - validation of impedance (or transfer) functions against the benchmark solutions for frequencies up to 50 Hz for embedded structures.

• Extended subtraction method (ESM) - adequacy of ESM as compared to the direct method (DM)

• Non-vertically propagating shear waves - evaluation of solutions for non-vertically propagating shear waves and determination of whether this is an important effect to be included in the NuScale seismic analysis

• Number of soil layers - confirmation that the number of soil layers used in NuScale analysis is within the maximum soil layers validated for SASSI2010

• Number of interaction nodes - confirmation that the number of interaction nodes used in NuScale analysis is within the maximum interaction nodes validated for SASSI2010

• Interpolated transfer functions - validation of the interpolation methodology used in SASSI2010

• Any other important parameters used in NuScale seismic analysis Validation of certain parameters identified above may have been captured in separate RAI questions and, in such cases, the applicant may provide appropriate references to these RAIs to take credit. Also, if certain aspects of SASSI2010 V&V for NuScale specific application are encompassed by vendor-provided generic SASSI2010 V&V documentations, the applicant may provide appropriate references to these documentations to take credit.

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