ML18090A003

Handout for the April 2, 2018 Public Meeting to Discuss NuScale Plans to Respond to the NRC Staff RAIs Related to Sections 3.7 and 3.8

ML18090A003
Person / Time
Site:	NuScale
Issue date:	04/02/2018
From:	Office of New Reactors
To:
Tabatabai O
References
Download: ML18090A003 (17)

Text

NuScale Closure Plan for Structural and Seismic FSAR Tier 2, Sections 3.7 and 3.8 RAIs The attached closure plan for the NuScale structural and seismic RAIs includes:

• eRAI number and RAI Question #

• RAI Question

• Plan - includes approach and actions to be performed for closing and completing each response, schedule for submitting the final responses and identification of FSAR markups

• Schedule - estimated date of RAI response and FSAR markup submittal

NuScale Closure Plan for FSAR Sections 3.7 and 3.8 RAIs eRAI Quest RAI Question Plan Sched ion# ule 1 8967 03.08. FSAR Section 3B.2.3.3 states Pilasters are 1) Clarify the failure mode and structural 3/2/20 04-4 added to the exterior walls of the RXB structure demand for which the corner pilasters 18 Commented [A1]:

to increase the capacity at the corners and provide additional capacity. Provide in The staff has already received the applicants response stiffness of the walls between the corners. The response and update FSAR Appendix to this RAI and therefore this item can be removed from the Closure Plan.

phrase to increase the capacity at the corners 3B.2.3.3 to clarify statements in question.

is unclear to the staff as to what kind of RXB pilasters strengthen the exterior walls capacity. Clarify the failure mode and structural by resisting axial tension and compression, demand for which the corner pilasters provide lateral shear loading in both north-south and additional capacity. Also, clarify whether the east-west direction, flexural bending about phrase, to increase ..stiffness of the walls the north-south and east- west axes of the between the corners, refers to additional wall pilasters. Failure modes of the concrete strength provided by the pilasters. Describe walls and pilasters due to the the failure mode and structural demand for aforementioned loads are described in ACI which the pilasters provide additional wall 349- 06.

strength, as applicable.

2) Clarify any FSAR phrase that discusses additional wall strength provided by the pilasters. First paragraph of 3B.2.3.3 will be restated as follows: Pilasters are used around the perimeter of the RXB exterior walls. They are also used at two locations inside the pool walls from Elevation 50' to Elevation 100' at grid line 3.

3) Describe the failure mode and structural demand for which the pilasters provide additional wall strength. Details regarding the pilasters will be provided in response to Question 03.08.04-6 2 8967 03.08. FSAR Section 3B.2.3.3 states In the finite 1) RAI response will clarify the process to 3/2/20 04-5 element model, the pilasters are modeled with establish the frame stiffness properties that 18 Commented [A2]:

frame elements with stiffness properties that represent the combined action of the walls The staff has already received the applicants response represent the combined action of the walls and the pilasters. SAP2000 and SASSI to this RAI and therefore this item can be removed from the Closure Plan.

(modeled with shell elements) and the 2010 model walls as shell elements and the pilasters. Describe the process to establish the pilasters as frame elements. The stiffness of frame stiffness properties that represent the the pilaster is increased in both models to combined action of the walls and the pilasters. account for the increased bending stiffness Describe what portion of the wall contributes to of the pilaster stem within the area of the the frame element stiffness properties. wall. The pilaster also mobilizes parts of the wall on either side of the pilaster. Calculation will be provided in response to show bending stiffness. Figures, from the reactor building structural analysis, will also be provided in the response to show wall dimensions of typical wall and pilaster areas

2) Clarify what portion of the wall contributes to the frame element stiffness properties. In SAP2000 and SASSI2010, the walls are modeled with shell elements and

the pilasters are modeled with frame elements (at the common central line or the neutral axis of the wall) interconnected with the wall.

3) Update FSAR 3B.2.3.3 to clarify that the pilasters are modeled with frame elements with transverse flexural stiffness properties that represent the combined action of the walls and the pilasters.

3 8967 03.08. FSAR Section 3B.2.3.3 states Bending about 1) Provide the magnitude of loadings 3/2/20 04-6 the weak axis does not need to be evaluated (bending moments in both strong and 18 Commented [A3]:

because the pilaster is an integral part of the weak axes, and axial and horizontal The staff has already received the applicants response wall and bending in that direction is not local forces) at the top of each pilaster. These to this RAI and therefore this item can be removed from behavior. It is part of the in- plane behavior of the Closure Plan.

loadings will be provided in a table for the the wall and the shell elements in this area corner and internal pilasters at the N-W, have adequate reinforcing. Further this section N-E, S-E, and S-W corners and the north, states If the 5 feet by 10 feet pilaster can resist south, east and west walls.

the resulting loads on its own, the pilaster is considered qualified. Provide the magnitude of These loads envelope the cracked and loadings (bending moments in both strong and uncracked concrete conditions, as well as week axes, and axial and horizontal forces) at the single and triple building models. The the top of each of the 5 by 10 pilasters and loads come from a load combination that the 4 corner pilasters.

is approximately equivalent to ACI 349-06 load combination 9-6. The load combination forming the basis for these top of pilaster loads is:

U = D + F + 0.8L + S + Ccr + H + Ess No FSAR updates will be provided with this response.

4 8967 03.08. FSAR Section 3B.2.3.3 states The shear in the 1) Clarify what the source of the minor 3/2/20 04-7 weak axis direction, parallel to the wall, does increase is and provide an explanation for 18 Commented [A4]:

not need to be evaluated because the in-plane how the design is adequate. The minor The staff has already received the applicants response capacity of the wall is capable of increase referred to in FSAR Section to this RAI and therefore this item can be removed from accommodating the minor increase. The the Closure Plan.

3B.2.3.3 pertains to the shear load in the phrase the minor increase in the above pilaster stems (the 5 foot horizontal sentence is unclear to the staff. Clarify what the concrete projections beyond the exterior source of the minor increase is and explain walls). At the top of each of the four why the shear in the pilaster does not need to exterior RXB walls, the total lateral pilaster be evaluated. stem load parallel to the wall is less than 1% of the total wall in-plane shear capacity. Therefore, this load does not need to be evaluated.

To provide clarification, this sentence in the FSAR will be revised to state that the pilaster stem shear in the weak axis direction, parallel to the wall, does not need to be evaluated, because the in-plane capacity of the wall is capable of accommodating the minor increase in the

in-plane shear loading from the pilaster stems.

5 9254 03.07. The staff finds that the applicant has not 1) Provide additional information that 3/5/20 02-33 demonstrated that an eccentricity of 5% of provides the requested technical 18 Commented [A5]: The staff has already received the the building dimension is equivalent to a 5% justification to demonstrate the applicants response to this RAI and therefore this item increase in the elemental horizontal forces. equivalency to the DSRS methodology or can be removed from the Closure Plan.

Provide additional information that provides conservatism in the method used. A the requested technical justification to calculation has been performed and will demonstrate the equivalency to the DSRS be shown in the response that includes methodology or conservatism in the method additional information to show eccentricity used by the applicant. Compliance with the of 5% of the building dimension is DSRS is not a requirement; however, the equivalent to a 5% increase in the applicant should identify differences between elemental horizontal forces. The the analytical methods used for its design methodology chosen to account for and the DSRS acceptance criteria and accidental torsion is to increase the evaluate the technical acceptability of its maximum horizontal element forces by 5%

methods. The applicant may choose to use a and combine them with the maximum smaller model to illustrate the comparison of vertical forces by means of the square the results from the two approaches. root of the sum of the squares. This alternate methodology will show to be equivalent and meets the intent of DSRS 3.7.2, Acceptance Criteria 11.

No FSAR updates will be provided with this response.

6 9315 03.08. Per NuScale FSAR Tier 2, Section 6.3.2.3, 1) The ECCS valves (RVV and RVV) and 4/6/20 02-14 the emergency core cooling system (ECCS) actuators (identified as the RVV Trip, RRV 18 components (including valves, hydraulic Trip and Reset Valves in Table 3.2-1) are lines, and actuator assemblies) are Quality already identified and specified in Table Group A, Seismic Category I components 3.2-1 as Quality Group A, Seismic designed to ASME BPV Code,Section III, Category I. Hydraulic line are not Subsection NB. specified. FSAR Table 3.2-1 will be

1) For consistency, Table 3.2-1, modified to add the hydraulic lines and Classification of Structures, Systems, and valve names clarified.

Components, should be revised to clarify the specified ECCS valves are intended to 2) In service inspection of the ECCS include the valves, hydraulic lines, and trip/reset and reset valves (actuators) actuator assemblies being Quality Group A, nozzle to safe end and safe end to valve Seismic Category I components. weld are discussed in FSAR Table 6.2-3 Per FSAR Tier 2, Section 6.3.2.2, the body of (RVV and RRV trip/reset nozzle to safe the ECCS actuator assembly serves as both end weld) and Table 5.2-8 (RVV and RRV a containment vessel (CNV) pressure trip/reset safe end to valve weld) boundary and reactor coolant pressure respectively. The nozzle to safe end weld boundary (RCPB). General Design Criteria fall under Table IWB-2500-1 (B-F)

(GDCs) 14 and 16 require that: inspection requirements. The weld at this location is an NPS 4 or greater connection

• The reactor coolant pressure boundary so the weld should have a volumetric and shall be designed, fabricated, erected, and surface examination. Table 6.2-3 indicates tested so as to have an extremely low only a surface examination is required. So probability of abnormal leakage, of rapidly FSAR Table 6.2-3 will be revised for this propagating failure, and of gross rupture. weld to identify both a volumetric and

• Reactor containment and associated surface examinations are required. The systems shall be provided to establish an safe end to valve weld falls under Table essentially leak- tight barrier against the IWB-2500-1 (B-J) inspection

uncontrolled release of radioactivity to the requirements. The weld at this location is environment and to assure that the less than an NPS 4 so the weld should containment design conditions important to have a surface examination. Table 5.2-8 safety are not exceeded for as long as indicates no examination is required. So postulated accident conditions require. FSAR Table 5.2-8 will be revised for this The ECCS actuator assembly currently weld to identify a surface examination is protects both the CNV boundary and RCPB; required.

therefore it is crucial that the welds and actuator assembly itself be designed to 3) Table 6.6-1 defines the inspection ensure and extremely low probability of requirements for Class 2 and Class 3 leakage or failure in accordance with GDCs componentes. The RVV and RRV 14 and 16. trip/reset valves

2) The NRC staff requests the applicant to (actuators) are Class 1 components and clarify the inservice inspection (ISI) that will their inservice inspection requirements are be performed to provide assurance of the defined in Table 6.2-3 and Table 5.2-8 as structural integrity of the containment nozzle discussed in (2) above.

to safe end welds and safe end to ECCS actuator assembly welds, i.e. will they be full 4) The RVV and RRV trip/reset actuator volumetric? valve are a Class 1 valve and follow the

3) FSAR Tier 2, Table 6.6-1, Examination requirements of NB-2000. Per the Categories, should also be revised to include requirement of NB-2500 the materials this information. listed in Table 6.1-3 for RCPB valve body

4) Also, will the material the actuator and bonnets are to have volumetric assembly body is manufactured from be examination. So a volumetric exam is volumetrically examined as part of the valve performed on the actuator valve RCPB fabrication requirements? components.

5) And what are the fabrication NDE requirements for the entire RCPB portion for 5) See the response to (4).

this valve?

Also, Per FSAR 6.3.2.2, Equipment and 6) The o-ring seals are the body-to-bonnet Component Descriptions, valve bonnet seals seals for each ECCS trip and reset on each pilot valve establish the pressure actuator valve that are located on the boundaries internal to the valve assembly exterior of the body. And in TR-1116-51962-NP NuScale CNV. These seals form a containment and Containment Leakage Integrity Assurance reactor coolant pressure boundary. These Technical Report, Section 3.2 Containment seals will be Appendix J Type B as-found Penetrations, it describes a portion of the tested each refueling outage. A separate ECCS actuator pressure boundary that is as-left test will only be performed if (1) the accomplished by a bolted enclosure (body- as-found is unsatisfactory, or (2) an to-bonnet) with a dual metal o-ring seal. activity was performed during the outage In generic technical specifications (TS) that could have affected leakage integrity.

Subsection 3.4.5, "RCS Operational These seals are subject to the leakage LEAKAGE," LCO 3.4.5 states that RCS criteria of LCO 3.4.5 and part of the operational LEAKAGE shall be limited to: a) reactor coolant pressure boundary no pressure boundary LEAKAGE, b) 0.5 gpm leakage verification performed via SR unidentified LEAKAGE, c) 2 gpm identified 3.4.5.1.

LEAKAGE from the RCS, and d) 150 gallons per day primary to secondary LEAKAGE. 7) Any leakage past the trip and reset (6) The NRC staff requests that the applicant valve seals would be both unidentified clarify the periodic testing and inspection RCS leakage (LCO 3.4.5.b) and provisions it will implement to ensure no containment leakage leakage past the O-ring seals of the ECCS (Appendix J Type B). Any leakage from actuator pressure boundary during normal the ECCS main valves would be operating conditions. unidentified RCS leakage (LCO 3.4.5.b).

RCS leakage is

(7) Also, explain how LCO 3.4.5 limits a), b), verified periodically by SR 3.4.5.1.

and c) would apply to leakage past the ECCS actuator O-ring seals or through the valve 8) SR 3.4.5.1 verifies RCS operational body. leakage is within limits by performance of (8) Explain how such RCS leakage outside of a RCS water inventory balance. This containment would be detected, identified, inventory and quantified during operation." includes leakage both inside and outside (9) Were such leakage to occur without being containment. This result can be compared identified but within the limit of LCO 3.4.5, with containment evacuation system what would the possible consequences be at leakage to the onset of an event? determine the source of the leakage (inside/outside containment).

9) SR 3.4.5.1 is performed every 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Any leakage inside the containment vessel will be catagorized as unidentified.

Any leakage through the trip or reset valve o-rings would also be unidentified and enter the ultimate heat sink. This leakage would be 0.5 gpm (unidentified leakage limit). However, this amount of leakage would likely fail the Appendix J Type B leakage test. The Type B test is performed at peak containment accident pressue (Pa

= 951 psia), which is less that RCS operating pressure; however, this test is satifactory to ensure this seal will perform as designed, because (1) these valves form the smallest Type B seals in the owner's Appendix J program and will have the most restrictive leakage limits, (2) the test medium is gas (air or nitrogen), and (3) the acceptance leakage criteria of the Type B test for these seals is more rigorous than the RCS operational leakage check prior to plant startup. This pressure boundary will still be tested periodically as part of SR 3.4.5.1. "

7 8936 03.07. On Page 3A-1 of the DCD, the staff noted NuScale will provide, in a RAI response, a 4/20/2 02-10 that a detailed dynamic Analysis Models of comparison of seismic demand forces at 018 the NPM subsystem is performed using a the NPM upper support and the bottom more detailed NPM model and the input time support skirt interface between the SSI histories obtained from the SSI Analysis analysis model using the simplified NPM Models of the reactor building which included beam model and the 3D detailed ANSYS a simplified NPM to account for the coupling model of the NPM bay. Significant of NPMs and the reactor building. The differences between the two models will applicant is requested to provide, at the NPM be identified and the design upper support and the bottom support skirt demand/capacity ratios will be presented interface locations with the RXB, a to show the NPM support design is comparison of the seismic demand (forces conservative.

and moments) obtained from the SSI Analysis Models of the RXB and the detailed To support the response, the following NPM 3D Analysis Models. The applicant technical approach will be taken:

should also explain any significant 1. Run a set of parametric analyses using

differences and confirm that the loads used three case conditions (cracked, uncracked for the NPM support design is conservative. and reduced stiffness), at two NPM locations (module 1 and 6) to provide a sampling of results for load conditions which generally bound the design demands.

2. Prepare a summary report which provides a comparison of the reaction forces at the NPM upper support and bottom support skirt between the SSI NPM beam model and the detailed NPM 3D model.

. Clarify any significant differences between simplified beam model used in SSI analyses and the 3D detailed model.

. Provide design demand/capacity ratios from results to show NPM support design is conservative in RAI response.

The results of the parametric studies will be added to the technical report, TR-0916-51502, referenced in FSAR Appendix 3A. Commented [A6]: Provide a summary markups in the FSAR 3.7.2 followed by a reference to the TR.

8 8932 03.07. To discuss the adequacy of 7P Extended 7P vs. 9P comparison 4/30/2 02-4 Subtraction Method (ESM) model, the The comparison between the results of 018 applicant provided 7P versus 9P ISRS the 7P and 9P models will be extended to comparisons for the Capitola time histories in include Transfer functions (TF) at the Commented [A7]: The applicant is requested to Figures 3.7.2-8 to10. However, the FSAR three selected locations and out-of-plane confirm if the TF mentioned hereinafter refers to the does not provide a comparison of transfer bending moments along the shell acceleration TF; if not, please provide specific functions for the 7P and 9P models. The elements at the middle of the roof, which qualifier before the word TF.

review of transfer functions is essential to is the area that exhibits the highest ISRS.

ensure that the numerical implementation of For this comparison, the RXB model with the SSI analysis methods is acceptable and cracked concrete and 4% material damping consistent with the guidance in DSRS is analyzed with Soil Types 7 and 11. Also, Section 3.7.2. The staff believes that 7P vs ISRS and Out-of-plane bending moments 9P ESM comparison captures only an are the average of five CSDRS-compatible incremental enhancement between the two input motion results.

models. The adequacy of an ESM model TF will be reviewed and spurious spikes should be established against the direct identified. The use of the ESM would method (DM). Therefore, in addition to a normally shift the frequencies of the comparison of the 7P and 9P ESM models, spurious spikes to the high frequency the applicant is requested to provide a range. The frequency range that is comparison of the transfer functions for the minimally affected by the spurious spikes 7P ESM and the DM models at selected will be identified. In agreement with DSRS nodes of the critical sections or, provide Section 3.7.2, it will be verified that the justification for why a 7P vs 9P comparison is frequency content of the input motion that sufficient and acceptable. is important to the SSI analysis lies within this range. Any differences in TF between the 7P and 9P models will ultimately be evaluated by comparing the results used for design; that is, by comparing the ISRS and bending moments at the locations mentioned above. If the differences in result quantities are below 10%, then the 7P results are considered adequate.

ESM vs. DM comparison

a) RXB The adequacy of the ESM will also be established by a direct comparison between the results obtained using the 7P ESM and those obtained using the direct method (DM). Because the number of interaction nodes of the RXB model required for the DM exceeds the capability of SASSI2010, a reduced-size model is used, as allowed by guidance in DSRS Section 3.7.2. This reduced-size model corresponds to the north (+Y) half of the RXB, analyzed for:

Soil Type 7, which is the controlling case for the majority of structural responses Cracked concrete condition with 4%

damping Because the RXB is not 100% symmetric along the X (north-south) axis, for direct comparison, a new 7P ESM model is created for the north half of the building.

The following responses are compared:

1. TF and ISRS at multiple critical locations including: basemat, RXM lug supports, exterior walls, pool walls, and slabs at different elevations including the center of roof. Commented [A8]: Please add Reactor Building Crane

. 2. Soil pressure on north wall at different (RBC) support locations to the list here.

elevations

. 3. Forces and moments in different structural elements including: exterior walls, basemat, north pool wall, roof, and pilasters.

. 4. Relative displacement at multiple locations including floor at different elevations, exterior walls, pool walls, and roof.

b) CRB For the CRB, the interaction nodes are within the limits of SASSI2010, therefore, the full model is used for the DM. The CRB DM model will be analyzed for Soil Type 7, cracked concrete with 4% damping, and five CSDRS-compatible input motions. The responses to compare against the 7P model are: TF and ISRS at multiple critical locations including: basemat, exterior walls, and roof.

TF will be reviewed and spurious spikes identified. Any differences in TF between the 7P ESM and DM models will ultimately be evaluated by comparing the results used for design; that is, ISR, forces, and/or moments.

If the differences in result quantities are below 10%, then the 7P results are considered adequate.

FSAR Section 3.7.2.1.1.3, Benchmarking, will be expanded to include a summary of these studies 9 8971 03.08. FSAR Section 3.8.4.3.3 describes lateral soil A note will be added to FSAR Section 4/30/2 04-14 pressures, including dynamic soil pressures 3.8.4.3.3 to clarify that seismic soil 018 corresponding to SSI and SSSI analyses, pressures on the embedded exterior walls applicable to the embedded exterior walls of of the RXB and CRB are the envelope of the buildings. The staff request the applicant to all SSI and SSSI analysis cases. The clarify whether these pressures are based on process is described in FSAR Section the envelope of all SSI and SSSI analysis 3.7.2.4.1, for combining SASSI results for cases. Also the staff notes that while FSAR design. These seismic pressures produce Section 3.8.4.3.3 describes the consideration of forces and moments on the shell elements the aforementioned lateral soil pressures as comprising the exterior walls of the part of the design loads for the embedded buildings which are used in their design. Commented [A9]: Clarify whether the static soil exterior walls, the magnitude of such loads was pressures (including hydrostatic, effective, and not provided in the FSAR. The applicant is FSAR Section 3.8.4.3.3 will be updated to surcharge) are similarly addressed in the design requested to provide in the FSAR the pressure demands obtained from SAP2000 and provide the include plots showing pressure distributions description in the FSAR for both the static and dynamic distributions with depth of the bounding of the bounding dynamic soil pressures on soil pressures.

dynamic soil pressures considered in the design the embedded walls for both RXB and CRB.

of the embedded exterior walls of the buildings. Commented [A10]:

The response to RAI, 9049, Question 2.5.4-3 provided markups to FSAR Section 3.8.4 to address the static 10 8932 03.07. a. DSRS 3.7.2 provides guidance that a. A basis for the 25 ft of separation depth 5/31/2 and total soil pressures and overturning moment on the 02-6 effects of potential separation or loss of will be provided along with clarification 018 below grade walls for the RXB. The applicant is requested to update the total soil pressures and contact between the structure and the soil regarding the modulus reduction factor. overturning moment as necessary to include the during the earthquake should be considered b. Consistent with ASCE 4-16, Section dynamic soil pressures. Also, provide the static and in SSI analysis. On Page 3.7-23 of the 5.1.9, soil separation is considered by total soil pressures and overturning moments for the FSAR, in the second paragraph from the neglecting the soil along the upper 25ft of CRB.

bottom, the applicant states, To model the the RXB embedment (i.e., the Young's soil separation, the Young's modulus of the modulus of the backfill was factored by backfill elements down to a depth of 25 (the 1/100). SSI analysis is performed to the top four layers of backfill elements) was RXB for Soil Type 7 with cracked concrete decreased by a factor of 100. The applicant properties and 7% concrete material is requested to provide a basis for 25 ft of damping. Soil Type 7 is used because it is Commented [A11]: Since the development of design separation depth. Also, please clarify if the the case that produced the highest ISRS basis ISRS is based on 4% structural damping (FSAR modulus reduction by a factor of 100 applies and forces and moments at the majority of 3.7.2.5), it is not clear how would the ISRS comparison locations. The following responses are be performed when the SSI analysis for the soil only to the backfill elements interfacing with separation case used a damping level of 7% structural the exterior walls or to all the backfill compared between the intact and soil- damping. The plan should reflect the action plan for elements outside the exterior walls. separated cases: addressing this issue. In addition, a comparison of

1. Forces at the RXM lug supports Seismic demand at the Reactor Building Crane (RBC)

2. ISRS at several locations including support locations should be included in the plan.

b. On Page 3.7-23 of the FSAR, in the bottom paragraph, the applicant states, Soil basemat edges, roof, pool floor and separation has negligible effect on the exterior walls.

response of the structure. The primary point of 3. Transfer functions at the same ISRS comparison is at the NPM. The study showed locations that the maximum reaction force at the base of 4. Maximum shears and moments in all the NPMs decreased by approximately 5 four exterior walls percent, and the maximum reaction force at the 5. Soil pressures in all four exterior walls NPM lug restraints decreased by more than 15 percent. The applicant is requested to provide Five CSDRS-compatible input motions are information on soil separation effect on used to obtain structural responses, computed transfer functions and seismic whereas Capitola CSDRS-compatible input demands (forces, ISRS) at critical section motion is used for ISRS. Results show that locations and external walls. Please provide demand forces and moments due to soil comparison plots for results between the intact separation effects investigated above are and soil-separated cases. When soil- within the design force and moment

separation results in increased seismic capacities.

demands, such increased demands should be taken into account in establishing the design c. Additional analyses on soil separation for basis seismic demands. the CRB will be conducted as described above. Similar results will be obtained.

c.The staff notes that a soil-separation study was conducted for the RXB but not for the FSAR Section 3.7.2.1.1.3, Soil Separation, CRB. The applicant is requested to provide a will be expanded to include a summary of technical justification for not conducting a these studies and representative plots similar study for the CRB. comparing results.

11 8838 03.08. Describe the method/mechanism for restraining 1) The analysis to determine whether 7/10/2 04-1 a bioshield mounted on an adjacent bioshield bioshield failure under SSE conditions could 018 Commented [A12]: The plan for items 2 and 3 in and restraining the upper CNV on the module impair the integrity of seismic Category I question 3.8.4-1 is missing. Please provide plan.

inspection rack during the refueling operations. SSCs, or result in incapacitating injury to Further, provide analysis and design criteria control room occupants will be evaluated in (consistent with DSRS Section 3.7.2.II.8) to accordance with DSRS Section 3.7.2.II.8. Commented [A13]:

ensure no adverse interactions occur between 2) The method/mechanism for restraining Describe in the FSAR the static and dynamic analysis the seismic Category II bioshields and a bioshield mounted on an adjacent methods used for the bioshield. Describe the applicable inspection racks with adjacent seismic design codes and standards. Describe the applicable bioshield and restraining the upper CNV design loads for the bioshield. Provide the magnitude Category I SSCs, during refueling operations on the module inspection rack during the of the applicable static, seismic, pressure, and (and during the transport of new modules, as refueling operations will be clarified. temperature loads. Provide D/C ratios for the structural applicable). ) FSAR Section 3.8.4 will be updated in components of the bioshield.

accordance with DSRS Section 3.7.2.II.8.

Commented [A14]: Provide FSAR markups and

) figures addressing design descriptions (e.g.

12 9309 03.08. In its response to RAI 8971, Question 03.08.04- 1) Provide the technical basis that 8/24/2 dimensions, material properties, reinforcement details, 04-37 12, the applicant indicated that the jet demonstrates the adequacy of the RXB to 018 anchors, welds, etc.).

impingement, pipe break reaction, and missile withstand the demands from Load impact loads are to be addressed by the COL Combinations 13 and 17 applicant as per COL items 3.6- 2 and COL 2) Provide clarification regarding the item 3.6-3. Based on the applicants response, locations in the RXB where respective it is not clear to the staff what provisions have loads are expected to occur and address been incorporated in the current design to the comparison of the site-specific accommodate the aforementioned loads that loadings with the standard design loadings will be established by the COL applicant and as in the existing COL item 3.8-2.

are to be combined with other loads as per Load Combinations 13 and 17 in FSAR Tables The following approach will be taken to 3.8.4-1 and 3.8.4-2, respectively. Therefore, the address the above information:

staff request the applicant to provide the Describe preliminary locations of high energy technical basis that demonstrate the adequacy pipe locations in the building of the RXB to withstand the demands from Load Evaluate pipe break and describe mass and Combinations 13 and 17.

energy ventilation strategy Commented [A15]: Provide the magnitude of the Additionally, the staff requests the applicant to Show that for representative areas that resulting or assumed (with description of technical clarify the locations in the RXB where these the structural elements are adequate. basis for assumption) for jet impingement, pipe break loads are expected to occur and address the reaction, and missile impact loads.

comparison of the site-specific loadings (as per Possible changes to DCA sections Commented [A16]: Provide D/C ratios for the load combinations 13 and 17) with the standard representative areas.

3.8.4.3.18,19 and 20.

design loadings in the existing COL item 3.8-2 or a new COL item. Further, the staff request Commented [A17]: Also address changes in FSAR Section 3.6, 3.8.4.8 (and other 3.8.4 subsections as the applicant to update the FSAR markups applicable), Appendix 3B, and other chapter 3 sections proposed in its response to RAI 8971, Question as applicable.

03.08.04-12, as applicable.

Commented [A18]: The staff understands that 13 8935 03.07. DSRS Section 3.7.2 provides guidance that, Kinematic interaction does not apply to SSI 8/30/2 kinematic interaction is an important phenomenon to consider in SSI analysis, particularly for deeply 02-23 for soil-structure interaction (SSI) analysis for analysis with SASSI. Sidewall impedance is 018 embedded structures. The applicant is requested to clarify what this statement means or signifies.

deeply embedded structures, proper included in the impedance matrix of the consideration should be given to excavated soil calculated by SASSI. Gaps uncertainties associated with kinematic between the soil and structure are covered interaction, non-vertically propagating shear under the Soil Separation studies performed waves, sidewall impedance calculation, and and included in the FSAR Section other effects such as the development of 3.7.2.1.1.3.

gaps between the soil and structure Regarding non-vertically propagating specifically for strong-motion earthquakes. shear waves, the following approach will For non-vertically propagating shear waves, be taken:

a sensitivity evaluation can be performed to a. The angle incidence for the study will be determine whether this is an important effect determined based on the apparent wave to be included in the SSI analysis. Staff has velocity commonly used in practice. ASCE not been able to identify how the applicant 4-16 Section 7.1 and its commentary has considered these uncertainties provide the information for typical range of associated with SSI of deeply embedded apparent wave velocity. Representative structures in the seismic analysis of NuScale range of apparent wave velocity are Category I SSCs. Provide an explanation for identified from 2 km/sec to 5 km/sec. In what analyses the applicant has performed Section 7.1, a conservative value of 2 km/sec (6,600 ft/sec) is recommended for and how these uncertainties have been seismic analysis underground pipes and considered.

conduits.

b. For the purpose of sensitivity analysis, we plan to perform additional SSI analysis of the 3D F.E. model of RXB for three apparent wave velocity values of 2 km/sec, 3 km/sec and 5 km/sec. In SASSI formulation, apparent wave velocity can be used to determine the angel of incidence using the velocity of the half space soil layer in the site profile. The angle of incidence is defined from vertical axis in the half space. The angle of incidence changes as the wave propagates upward in the upper layers (Snells law).

c. For the proposed study, soil profile type 7 will be used. The reason for this choice is that the velocity of the soil layers and the half space are close and the change in the angle of incidence due to upward wave propagation will be small.

d. The results of analysis for the three cases will be compared with the results for the vertically propagating waves in terms of ISRS at multiple locations on the exterior and interior walls to assess the impact of inclined waves on the response.

In addition, seismic loads and seismic soil pressure or selected out of plane forces of the exterior walls at few key locations will be obtained and compared.

A summary of this study will be included at the end of FSAR Section 3.7.2.1.1.3, under the title Non-vertically Propagating Shear Waves.

14 8964 03.08. In FSAR Tier 2, Section 3.8.5.6.7, Basemat 1) Provide information on associated 8/30/2 05-2 Soil Pressures along Basemat Edges (Toe settlements due to soft soil stiffnesses along 018 the edges of the seismic Category 1 Pressures), the applicant performed analyses structure to determine the edge bearing pressures (or toe pressures) along the edges of the seismic The triple building model report will be Category I structure basemats (RXB and CRB). revised to include toe settlements and toe In FSAR Tier 2, Section 3.8.5.5.5 Settlement bearing pressures determined from the Approach, the applicant considered a condition combined results of the SASSI2010 and of the soil stiffnesses that are further reduced SAP2000 models. The soil stiffness is by 50 percent to amplify the effect of reduced by 50% to amplify the settlements.

settlements. FSAR Tier 2, Section 3.8.5.6.7, The results envelope cracked and Basemat Soil Pressures along Basemat Edges uncracked concrete conditions. Forces and (Toe Pressures), the applicant performed moments in the basemat due to toe bearing analyses to determine the edge bearing pressures will be determined and compared pressures (or toe pressures) along the edges of with ACI 349 allowables. Settlement values the seismic Category I structure basemats will be compared with NuScale-defined (RXB and CRB). In FSAR Tier 2, Section limits.

3.8.5.5.5 Settlement Approach, the applicant considered a condition of the soil stiffnesses FSAR Section 3.8.5 will be updated, as that are further reduced by 50 percent to necessary to incorporate information from amplify the effect of settlements. Therefore, the revised report.

provide information on associated settlements due to soft soil stiffnesses along the edges of the seismic Category I structure.

15 8971 03.08. 10 CFR 50, Appendix A, GDC 1, 2, and 4, 1) Provide the magnitude of the bounding 8/30/2 04-13 provide requirements to be met by SSC forces and moments profiles for walls and 018 important to safety. In accordance with these basemat requirements, DSRS Section 3.8.4 provides 2) Describe how load combination 10 was review guidance pertaining to the design of determined to be the controlling load seismic Category I structures, other than the combination instead of load combination 13 containment. Consistent with DSRS Section 3.8.4, the staff reviews loads and loading The following approach will be taken to combinations. address the above information:

FSAR Section 3.8.4.4.1 indicates that an - The magnitude of the thermal forces and moments will be extracted from the finite ANSYS model was created to evaluate the element models.

effects of thermal loads on the structure.

- Clarify from this extracted information Further, FSAR Section 3.8.4.5 indicates that consideration in the load combinations the load combination 10 from Table 3.8.4-1 has magnitude of the bounding forces and been determined to be the controlling load moments profiles combination. The staff request the applicant for walls and basemat resulting from to provide the following information.

thermal loads.

a) Magnitude of the bounding forces and - Review the determination of the controlling moments profiles for walls and basemat load combination, including an example of resulting from thermal loads, To and Ta. Clarify how the loads were combined. Commented [A19]: Describe in the FSAR the whether such values were used in the load - Revise FSAR Section 3.8.4 text and determination of the controlling load combination and combinations 10 and 13 in Tables 3.8.4-1. tables 3.8.4-1. provide an example of how the loads were combined.

b) Describe how load combination 10 was determined to be the controlling load combination instead of load combination 13, and provide an example of how the loads were combined.

16 8933 03.07. In FSAR Section 3.7.2.1.2.1, the staff noted NuScale will provide, in a RAI response, 10/31/

02-16 that the dry dock is assumed to be full of water further clarification of the operating band 2018 and part of the UHS in the seismic analysis. level for the RXB pool water. In addition, a The nominal water level is at EL. 94 ft. In FSAR description of the dry dock gate analysis and Section 9.1.3, the staff also noted that the dry design criteria will be provided to ensure that dock can be drained partially or completely to no adverse seismic interaction occurs support plant operations. In FSAR Section between the dry dock gate and adjacent 9.1.3.3.5, the staff further noted that a failure of SSCs. The maximum design loads for the the dry dock gate while the dry dock is empty dry dock gate occur when the pool is full.

could result in a decrease in water level at the Technical justification will be provided UHS pool by about 12 ft. Since the dry dock through a parametric study comparing contains a large body of water, draining of a design forces with an empty dry dock for large mass of water could affect the dynamic confirmation to show that the dry dock gate characteristics of the SASSI and ANSYS has been designed to the bounding load models thereby potentially affecting the seismic case and will not fail under a safe shutdown demand based on full dry dock assumption. earthquake (SSE). With this, NuScale does Commented [A20]: Please confirm that the action plan Provide a technical basis for not considering not believe it is necessary to account for a includes the following elements:

different water level conditions for the dry dock 12 foot drop in the UHS pool water level in 1. Description of the SSI analysis with the empty dry in the seismic analysis. In addition, the the dynamic analyses. To support the dock including the parameters (e.g., cracked and/or uncracked model, structural damping values and the applicant should address the effect of potential response: soil properties, as well as the input spectra (CSDRS, variation in water level of the UHS on the CSDRS-HF)) selected for the study and their basis.

seismic analysis of the RXB and NPM including 1. Develop SAP2000 and SASSI model with 2. In addition to the foundation and walls, description the analyses conducted in FSAR 3.7.2.9.1 to of the other key locations where the seismic and the dry dock empty of its water, and show address the effect of operation with less than equipment demand including the ISRS are compared that the results on the foundation and walls to ensure that the seismic demand used for the the full complements of NPMs. are bounded by the full pool. Discuss in an design bounds the demand obtained from the full RAI response by ratio of mass that would be pool analysis with the dry dock empty.

reduced that the overall dynamic 3. Comparison of the transfer functions at the characteristics of the building would not be selected locations

4. Markup of Appropriate FSAR Sections (e.g., 3.7, significantly different 3.8, 9.1.3, etc.)

2. Clarify with the NRC that we only have a 1 foot operating band of water level, and not the 12 feet noted in Chapter 9, and thus there really is no effect of the variation of water level

3. Provide the details of the dry dock gate calculation - that its designed to the full safe shutdown earthquake with water on one side, and empty on the other and is adequate. Commented [A21]:

Describe in the FSAR the applicable design codes and The information will be provided in an RAI standards and the applicable design loads (including FSI effects amongst other as applicable) and response and FSAR Tier 2 Section 3.7.2 will respective magnitudes. Provide D/C ratios.

be updated.

Tier 2 Section 3.7.2.1.2.1 of the FSAR will Provide FSAR markups and figures addressing design be supplemented with a technical descriptions (e.g. dimensions, material properties, justification summary for the design anchorage, welds, etc.).

assumption of a pool full of water being the bounding design condition for the dry dock gate. Potential variations of the UHS pool will not be considered as a design condition for the NuScale Power Plant.

17 8932 03.07. 10 CFR 50 Appendix S requires that the safety NuScale will provide, through the RAI 11/29/

02-5 functions of structures, systems, and response, additional transfer function plots 2018 components (SSCs) must be assured during at key nodes in critical sections within the and after the vibratory ground motion RXB and CRB. The plots will be associated with the Safe Shutdown Earthquake supplemented with a discussion of potential

(SSE) through design, testing, or qualification effects of spurious spikes where applicable.

methods. On Page 3.7-22 of the FSAR, in the The transfer functions will be extracted from fourth paragraph, the applicant states, a sampling of the SSI analyses that have However due to the size and complexity of been used for design of the plant:

these models it is not practical to review transfer functions at all the nodes in the 1. Revise CRB and RXB SSI ISRS models. The staff views that the applicant may calculations to include additional transfer not need to review transfer functions (TFs) at function data at critical node locations.

all nodes; however, the staff views that TFs at 2. TFs at those key locations will be key locations should be reviewed to ensure the reviewed to ensure the adequacy of the SSI adequacy of the SSI models and models and methodologies implemented in methodologies implemented in the seismic the seismic analyses.

analyses. Therefore, the applicant is requested 3. The new plots will be inspected whether to provide information on TFs (in plots) at spurious spikes in the TFs are present within selected nodes of the critical sections and other the frequency range of interest to the SSI important locations in the RXB and CRB. The analysis; and, if spikes are present, their plots should be inspected whether spurious potential effects on computed seismic spikes in the TFs are present within the demands will be investigated. Commented [A22]: The applicant is requested to be frequency range of interest to the SSI analysis; more specific in its approach to addressing any and, if spikes are present, the applicant Tier 2 Section 3.7.2.1.1.3 of the FSAR will spurious spikes identified in the TFs.

should discuss their potential effects on be updated to include additional descriptions computed seismic demands. of the transfer functions at critical locations and provide TF plots are critical locations.

Any spikes observed in the frequency range of interest will be further explained.

18 8935 03.07. a.In FSAR Subsection 3.7.2.5.2, the applicant 1) The ISRS from the triple building model 11/29/

02-26 indicates that the ISRS from the triple building for the design of SSCs in the CRB will be 2018 model were considered for the design of SSCs provided. ISRS will be developed in in the RXB but not for the CRB. It is expected accordance with RG. 1.1.2.2 "Development that the structure-soil-structure interaction of Floor Design Response Spectra for (SSSI) effect would be more pronounced on a Seismic Design of Floor-Supported lighter building (CRB) than a neighboring Equipment or Components" and the heavier building (RXB). The applicant is NuScale Seismic Design Criteria. FSAR requested to provide justification for not Section 3.7.2 will be updated to include considering the ISRS from the triple building details on the ISRS.

model for the design of SSCs in the CRB.

2) The approach to be used is the same

b. Figures 3.7.2-106 and 107 in the FSAR process used for the RXB.

present the Reactor Building ISRS for floor at EL 24 and EL 25, respectively, which indicates ) 3) A discussion of the factors contributing to noticeable difference in ISRS (both in shape the difference in the RXB ISRS will be and amplitude) for an elevation difference of provided.

only 1 foot. The applicant is requested to discuss the factors contributing to this observed difference.

19 8933 03.07- b. On Page 3.7-25 of the FSAR, in the sixth NuScale will povide, through the RAI 12/20/

02-17 paragraph, the applicant states, The rigid response, a sensitivity study with 2018 Commented [A23]: Missing the plan for items a and c springs have a zero length and have a stiffness summarized results to support the in question 3.7.2-17. Please provide plan.

value large enough to simulate rigid selection of the large 10e10 lbs/inch connection. The large stiffness used is stiffness value used for the rigid springs.

arbitrarily chosen to be ten billion lbs per inch, An alternate sensitivity study will be or 1010 lbs/inch, in the three global directions. presented to justify the use of the rigid For the spring to be modeled as a rigid spring, springs in the analyses. The goal of these the value of its spring constant should be rigid springs is to connect the soil nodes to

sufficiently larger than the stiffness of the the structural element nodes without structural element (basemat) to which it is compromising the soil- structure attached. The applicant is requested to confirm interaction and building response.

the adequacy of the number (1010 lbs/inch) Therefore, to demonstrate the validity of chosen for the spring constant by comparing it the element stiffness, a comparison of to the stiffness of the adjacent basemat relative displacements will be provided element or through an appropriate sensitivity between the two nodes of the spring run using a number at least an order of element (I and J) to demonstrate the rigid magnitude different. behavior using the 10e10 lbs/inch stiffness:

. 1. Using a sampling of SSI analysis cases, extract the relative displacements between the I and J nodes of the rigid spring elements.

2. Clarify that the differential displacement at I and j nodes of rigid link is very small (10-5 in), demonstrating rigid behavior.

. 3. Include results of relative displacements and justification of stiffness in the seismic SSI calculations.

Section 3.7.2.1.2.1 will be supplemented to summarize the conclusions of the study and provide technical justification confirming the 10e10 lbs/inch stiffness property simulates a rigid connection.

20 8935 03.07. 10 CFR 50 Appendix S requires that the safety 1) Provide the design-basis seismic 12/20/

02-25 functions of structures, systems, and demands, at all applicable critical section 2018 components (SSCs) must be assured during locations of the RXB and CRB. The forces, and after the vibratory ground motion displacements, soil pressures, and ISRS will associated with the Safe Shutdown Earthquake be computed according to NRC RG's, SRP's (SSE) through design, testing, or qualification and DSRS (using the approaches outlined in methods. FSAR Section 3.8.4 and 3.8.5). ACI 349-06 provides acceptance criteria for Tables 3.7.2-23, 24 and 25 in the FSAR displacements in concrete structures.

respectively provide SSI analysis results for one particular example shell, beam, and solid element, respectively. However, analysis 2) Tables 3.7.2-23, 24 and 25 will be results at other key locations are not provided. revised or a new table will be provided.

The applicant is requested to provide the design-basis seismic demands (e.g., forces, moments, soil pressures, accelerations, displacements, ISRS), at all applicable critical section locations of the RXB and CRB, that are used in structural design evaluations in FSAR Sections 3.8.4 and 3.8.5.

21 8963 03.08. Section 3.8.4.1, the basemat reinforcement NuScale will provide, through the RAI 12/20/

05-6 pattern of the foundation of RXB. However, the response, additional information to 2018 applicant did not provide sufficient information supplement the design of the RXB basemat.

for the design assessments, boundary The information will be tabulated to support conditions for each foundation model, design assessments, and will include design settlement evaluation and associated figures. capacity, forces and moments at critical Provide for the RXB basemat: sections. In addition, a full description of

- design assessments-should include: the analysis and boundary conditions will be

capacity of sections, design checks, etc. provided for each model to demonstrate

- boundary conditions for each foundation compliance with DSRS Section 3.8.5.II.4.N.

model -should include: stiffness types and To support the response:

parameter throughout the embedded portion of the RXB for each type of model (standalone 1. Triple Building Differential Settlement and combined) - SASSI2010, SAP2000, and calculation will be revised to include the ANSYS -- capacity of sections, forces & moments at

- settlement evaluations and figures showing critical locations, settlement evaluation, and reinforcement patters for (a) the entire RXB additional boundary conditions.

basemat, (b) intersections between walls & the 2. The additional information will be RXB basemat, and (c) intersections between reviewed, organized and tabulated to support pilasters & the RXB basemat. Settlement design assessments.

evaluation should include following types of settlements: (1) Maximum vertical settlements, Tier 2 Section 3.8.5.4.1 of the FSAR will be (2) tilt settlement, (3) differential settlement supplemented with additional descriptions of between structures and (4) angular distortion. the basemat foundation analyses including boundary conditions and settlement evaluations. The additional information provided in tabular format for the design assessments of the foundations will be added to Appendix 3B of the FSAR.

22 8971 03.08. While the magnitude of bounding demand Critical sections are defined as parts of the 12/20/

04-11 forces and moments were provided for some structure that: (1) perform a safety-critical 2018 critical sections (e.g. FSAR Tables 3B-36 to function, (2) are subjected to large stress 3B-38), the FSAR did not provide the demands, (3) are considered difficult to magnitudes of bounding demand forces and design or construct, or (4) are considered to moments for all critical sections identified for be representative of the structural design.

the RXB and CRB. Provide in the FSAR the These critical sections are listed in Appendix magnitude of bounding demand forces and 3B of the FSAR. Static and dynamic moments for all critical sections, with a structural responses obtained from breakdown of seismic and static forces and SAP2000 and SASSI2010 analyses will be moments. utilized to develop demand forces and moments such as static compression (negative) or tension (positive) membrane Additionally, provide a numerical example that forces for walls and slabs. Results of the Commented [A24]: Clarify whether this process has demonstrates how the direction of dynamic SASSI2010 soil-structure interaction already been performed in support of the design results forces and moments is addressed in the load analysis which is used to analyze seismic presented in FSAR Appendix 3B.

combinations as to ensure that the direction loads will contain dynamic force and that is most adverse in a load combination has moments which are dependent of the been considered as indicated in FSAR Section direction of the seismic load applied to the 3B.1.1.2.

structure. The direction resulting in most adverse load combination is considered for structural design. This information will be used to revise the calculations and present the magnitudes of bounding demand forces and moments for all critical sections. Commented [A25]: Clarify whether the current To show how the effect of the direction of calculation is based on the bounding demand forces the seismic loads is considered in the and moments for all critical sections. If not, describe what are they based on as applicable.

design, an example will be provided that demonstrates that the most adverse direction in a load combination has been considered. In addition, a breakdown of static and seismic forces will be prepared and presented. Finally, FSAR Section 3.8.4 and Appendix 3B will be revised to

include the details of the above research. Commented [A26]: Clarify whether the determination of design demands has already been performed in support of the design results presented in FSAR In summary, Appendix 3B.

) Revise the calculations to include the magnitudes of bounding demand forces and moments for all critical sections; Commented [A27]: Clarify whether the current

) Include a breakdown of seismic and static calculation is based on the bounding demand forces forces and moments; and moments for all critical sections. If not, describe what are they based on as applicable.

) Develop an example to demonstrate that the most adverse direction in a load Commented [A28]: As per the plan for question combination has been considered; and 03.07.02-25, the seismic demands will be provided in

) Update the FSAR Section 3.8.4 and new or revised tables in FSAR section 3.7.2. Therefore those do not have to be repeated in FSAR section Appendix 3B and include the results of the 3.8.4. Please provide in FSAR Section 3.8.4 the static above research. and total demands and a reference to the FSAR Section 3.7 tables containing the seismic demands.

23 8974 03.08. 10 CFR 50, Appendix A, GDC 1, 2, and 4 1) The magnitude of bounding seismic 12/20/ Commented [A29]: Clarify whether the determination 04-20 provides requirements to be met by SSC design forces of the roof in the three 2018 of design demands has already been performed in important to safety. In accordance with these orthogonal directions will be provided, support of the design results presented in FSAR requirements, DSRS Section 3.8.4 provides consistent with DSRS Section 3.8.4. Appendix 3B.

review guidance pertaining to the design of important to safety seismic Category I The following approach will be taken to structures, other than the containment. address the response:

Consistent with DSRS Section 3.8.4, the staff reviews, in part, loads and loading - Revise calculations for RXB SSI and CRB combinations. SSI to add the magnitude of bounding Provide the magnitude of bounding seismic seismic design forces of the roof in the three design forces of the roof in the three orthogonal orthogonal directions. Commented [A30]:

directions (North-South, East-West, and A table, showing the bounding forces, will Clarify whether the current calculation is based on the Vertical). be added to FSAR Section 3.8.4 bounding seismic demands. If not, describe what are they based on as applicable