RAIO-0818-61213, LLC Supplemental Response to NRC Request for Additional Information No. 151 (Erai No. 8974) on the NuScale Design Certification Application
| ML18214A832 | |
| Person / Time | |
|---|---|
| Site: | NuScale |
| Issue date: | 08/02/2018 |
| From: | Wike J NuScale |
| To: | Document Control Desk, Office of New Reactors |
| References | |
| RAIO-0818-61213 | |
| Download: ML18214A832 (11) | |
Text
RAIO-0818-61213 August 02, 2018 Docket No.52-048 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738
SUBJECT:
NuScale Power, LLC Supplemental Response to NRC Request for Additional Information No. 151 (eRAI No. 8974) on the NuScale Design Certification Application
REFERENCES:
- 1. U.S. Nuclear Regulatory Commission, "Request for Additional Information No. 151 (eRAI No. 8974)," dated August 05, 2017
NuScale Power, LLC Response to NRC "Request for AdditionalInformation No. 151 (eRAI No.8974)," dated October 03, 2017
NuScale Power, LLC Supplemental Response to NRC "Request for
Additional Information No. 151 (eRAI No.8974)," dated December 29,2017
NuScale Power, LLC Supplemental Response to NRC "Request for
Additional Information No. 151 (eRAI No.8974)," dated March 22, 2018 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) supplemental
response to the referenced NRC Request for Additional Information (RAI).
The Enclosure to this letter contains NuScale's supplemental response to the following RAI
Question from NRC eRAI No. 8974:
v 03.08.04-21 This letter and the enclosed response make no new regulatory commitments and no revisions to
any existing regulatory commitments.
If you have any questions on this response, please contact Marty Bryan at 541-452-7172 or at
mbryan@nuscalepower.com.
Sincerely, Jennie Wike Manager, Licensing NuScale Power, LLC NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com ennie Wike
RAIO-0818-61213 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com Distribution:
Gregory Cranston, NRC, OWFN-8G9A Samuel Lee, NRC, OWFN-8G9A Marieliz Vera, NRC, OWFN-8G9A : NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 8974
RAIO-0818-61213 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com :
NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 8974
Response to Request for Additional Information Docket No.52-048 eRAI No.: 8974 Date of RAI Issue: 08/05/2017 NRC Question No.: 03.08.04-21S3 10 CFR 50, Appendix A, GDC 1, 2, and 4, provide requirements to be met by SSC important to safety. In accordance with these requirements, DSRS Section 3.8.4 provides review guidance pertaining to the design of seismic Category I structures, other than the containment. Consistent with DSRS Section 3.8.4, the staff reviews, in part, loads and loading combinations.
Section 3B.2.7.4, Nuclear Power Module Lug Restraint, states that a separate local SAP2000 model is used to analyze the support system for increased demand. Further, this section states that the load is distributed as point loads to one of the lugs. Figures 3B-58 and 3B-59 show the distribution of the point loads. Section 3B.2.7.4 also describes that the load used to evaluate the lug components is 3500 kip (which is consistent with the distributed loads shown in Figures 3B-58 and 3B-59). Clarify whether the aforementioned increased demand refers to the 3500 kip load. If not, define the increased demand. Additionally, provide the basis for the 3500 kips including a description of the analysis cases from which this demand is obtained.
In addition to the above, FSAR Table 3B-27 provides the SASSI maximum lug reactions for RXB cracked model using Soil Type 7 (CSDRS) and Soil Type 9 (CSDRS-HF). Further, as stated in Section 3B.2.7.4.2, since these maximum lug reactions are below the lug support design capacity of 3,500 kips, the design is acceptable. Justify the use of the aforementioned SASSI cases only and not the envelope of all SASSI cases, in comparing with the design capacity of 3,500 kips.
NuScale Response:
As discussed in an NRC Public meeting on 6/12/2018, the NRC provided supplemental questions to eRAI 8974 Question 03.08.04-21 as follows:
In its response and proposed FSAR markups the applicant indicated that the most controlling mode of failure is bearing against concrete with a D/C = 0.777. However, FSAR Section 3B.2.7.4.1 states that the D/C ratio for the concrete bearing strength is 0.40. The staff request the applicant to describe the differences between the aforementioned D/C ratios and or correct the apparent inconsistency, as applicable.
NuScale Nonproprietary
Further, the response and proposed FSAR markups indicate that because the shear lugs transfer the shear loads from the bumper to concrete, the through bolts are considered to be under tension only. However, FSAR Section 3B.2.7.4.1 provides the shear capacity of the trough bolts and respective D/C ratio for the bolts but no D/C ratio with respect to shear failure of the shear lugs. The staff request the applicant to provide the D/C ratio with respect to shear failure of the shear lugs, clarify whether the through bolts are considered to be under tension only as indicated above or both shear and tension as may be implied by the D/C ratio for the bolts with respect to shear describe in the FSAR, and provide FSAR markups accordingly.
Additionally, the staff request the applicant to clarify in the FSAR the ultimate strength value provided for the shear lugs in Sections 3B.2.7.4 and 3B.2.7.4.1.
Response
Table below lists D/C ratios for structural components of the lug supports.
Structural Component Stress Check Demand Capacity D/C Shear Lug Plates Concrete Bearing 3.29 ksi 4.23 ksi 77.8%
Shear Lug Plates Plate Bending 41.1 in-k 67.5 in-k 60.9%
Shear Lug Plates Plate Shear (Steel Plate Check) 16.5 kips 90 kips 18.3%
Shear Lug Plates Plate Shear (Concrete Check-Single) 790 kips 2523 kips 31.3%
Shear Lug Plates Plate Shear (Concrete Check-Group) 3500 kips 5573 kips 62.8%
Shear Lug Plates Shear Friction (At the tip of the lugs) 3500 kips 6966 kips 50.2%
Through Bolts Tensile Stress 804 kips 1576 kips 51.0%
RXM Support Wall Punching Shear 888 kips 3394 kips 26.1%
Pool Wall Punching Shear 888 kips 4412 kips 20.1%
2" Liner Plate Bearing Stress 804 kips 1989 kips 40.4%
2" Liner Plate Bending Stress 11.6 ksi 100.8 ksi 11.5%
There are two different bearing stresses; one is the shear lugs against concrete and the other is the 2 steel liner against concrete. They are both shown in the above table. FSAR Section 3B has been revised to reflect the difference.
The through bolts are only designed for tension, while shear is resisted by the shear lugs. The through bolts shear capacity will be removed from the FSAR.
NuScale Nonproprietary
The maximum reaction forces at the NPM1 and NPM6 locations in the 3D ANSYS model, and at all twelve NPM locations in the SASSI model, are bounded by 4500 kips as shown in Table 1 of RAI 8936 Question 03.07.02-10.
Impact on DCA:
FSAR Tier 2, Section 3B has been revised as described in the response above and as shown in the markup provided in this response.
NuScale Nonproprietary
NuScale Final Safety Analysis Report Design Reports and Critical Section Details Tier 2 3B-29 Draft Revision 2 RAI 03.07.02-10, RAI 03.07.02-20 The D/C ratio of the bolts in shear and tension is 0.680.92.
RAI 03.07.02-10, RAI 03.07.02-20, RAI 03.08.04-31 The maximum D/C ratio for concrete bearing due to lateral load transferred from the bearing plate is 0.710.83.
3B.2.7.4 Nuscale Power Module Lug Restraint The NPM lug restraint design consists of a stainless steel bumper comprised of 2 thick plates with 2 thick stiffener plates. The bumpers are welded to 2 thick stainless steel liner plates. On the inside of the liner plate there are 3 thick, 5 wide (48 depth) steel shear lugs to transfer the lateral shear loads into the wall. Finally, the two bumpers on either side of the lug on the pool walls are bolted together with through-bolts to withstand tensile loads due to moments from the eccentric lateral shear loads. The design layout for the support system for the NPM lug restraints is shown in Figure 3B-51.
The bumpers are Stainless Steel Type 630 - H1150, with a yield strength of 100.8 ksi, and an ultimate strength of 135 ksi. The shear lugs are carbon steel ASTM A572 GR 50, with a yield strength of 50 ksi, and an ultimate strength of 65 ksi. The through-bolts are ASTM A193 GR B7, with a yield strength of 105 ksi, and an ultimate strength of 125 ksi.
RAI 03.08.04-21S2 A separate SAP2000 model is created for the local analysis of the RXB lug support system. This lug restraint model is a comprehensive, finite-element model of half of a single NPM wing wall. Therefore, 2.5' of the wall thickness, with two lugs on one face of the wall, are included in the model. The load is distributed as point loads to one of the lugs. The wing wall is modeled with solid elements. The liner plate, the stainless steel lug, and the bumper built-up section are modeled with shell elements. The through bolts are not modeled explicitly; however, the axial tension of the shear lugs is used to determine the tension force in the through bolts.
Because the shear lugs transfer the shear loads from the bumper to concrete, the through bolts are considered to be under tension only. All welds along the load path are CJP welds. This includes the bumper built-up section, the bumper to the liner plate, and liner plate to the shear lugs.
RAI 03.08.04-21S2, RAI 03.08.04-21S3 In this local model, an assumed horizontal load of 3500 kips is applied to determine the stresses in components of the support. Modes of failure for lug components are checked, including tensile capacity of through bolts, punching shear and concrete bearing, and bending stresses on the liner plate. The most controlling mode of failure is bearing against concrete with a D/C=0.777. Refer to Table 3B-56 for details. Because this D/C occurs for an applied load of 3500 kips, the true capacity of the lug assembly, where D/C would reach a value of 1.0, occurs for a load of 3500 kips/0.777=4500 kips.
RAI 03.07.02-10, RAI 03.08.04-21S2
NuScale Final Safety Analysis Report Design Reports and Critical Section Details Tier 2 3B-30 Draft Revision 2 To check the adequacy of the lugs, the maximum seismic reaction on a lug from the NPM Seismic Analysis model is compared against the lug capacity calculated from the local lug model. The maximum demand reactions in the global RXB model are based on three Soil Type 7 (CSDRS) analysis cases:
RAI 03.07.02-10 Case 1: Soil Type 7, cracked concrete, 4% concrete damping, no frequency shifting of NPM, Capitola input.
RAI 03.07.02-10 Case 2: Soil Type 7, uncracked concrete, 4% concrete damping, no frequency shifting of NPM, Capitola input.
RAI 03.07.02-10 Case 3: Soil Type 7, cracked concrete, 4% concrete damping, frequency of NPM reduced 15%, Capitola input.
RAI 03.07.02-10, RAI 03.08.04-21S2 The maximum lug reaction from the NPM Seismic Analysis model is provided in TR-0916-51502, NuScale Power Module Seismic Analysis (Reference 3B-6), and is less than the lug capacity of 4500 kips. This shows that the lugs are structurally qualified.
RAI 03.08.04-21, A separate local SAP2000 model is used to analyze the support system for an assumed demand of 3500 kips. The NPM lug restraint model is a comprehensive finite element model of half of a single NPM wing wall. The wall is 2.5 thick and has one support lug for analysis. The load is distributed as point loads to one of the lugs. The wing wall is modeled with solid elements, the liner plate and the stainless steel lug are modeled with shell elements. The stiffeners are also modeled with shell elements.
The NPM bay walls and location of the NPM lugs is shown in Figure 3B-52. The NPM lug restraint model is shown in Figure 3B-53 and Figure 3B-54. The liner plate and shear lugs are modeled as shell elements and are shown in Figure 3B-55 and Figure 3B-56. In Figure 3B-57, the outside of the bumper is removed in order to display the stiffener plates inside.
RAI 03.08.04-21, RAI 03.08.04-21S1, RAI 03.08.04-21S2 The demand reactions are based on two cases of Soil Type 7 (CSDRS) and Soil Type 9 (CSDRS-HF). These two cases, in general, provide the highest structural responses.
The capacity is based on the assumed value of 3500 kips, that the lugs are designed for, however, due to the extra margin in the design, the actual strength is 4500 kips which is higher than the maximum demand of 3726 kips. The demand to capacity ratios in calculations for the lug components are derived and shown to be less than one, which shows the lugs are qualified.
RAI 03.08.04-021S3 Section cuts were used to extract forces and moments for design of the NPM lug support. Table 3B-26 displays the forces and moments for the two 3500 kip load
NuScale Final Safety Analysis Report Design Reports and Critical Section Details Tier 2 3B-31 Draft Revision 2 cases: W-Lug-PY+ (shown in Figure 3B-58) and W-Lug-PY+- (shown in Figure 3B-59). Figure 3B-60 shows the liner plate section cuts at the intersection of the inside face of the bumper to the liner plate. These cuts are used to find the design moment (M1) due to design loading. Figure 3B-61 shows the shear lug section cuts (fins) that occur between the liner plate and shear lugs. The shear (F2) from these cuts is summed to verify that the total 3500 kip load is being transferred to the wall as shown in Table 3B-26. Finally, maximum tension load of 804 kips occurs on the shear lug directly below the 2 plate and the maximum shear of 790 kips occurs in the shear lug at X=88.20 inches. The sign of the F1 force for the fin at X=16.25" is negative but the deflected shape of the lug support system clearly shows this is a tension force (Figure 3B-62). These values are utilized in the shear lug evaluation.
3B.2.7.4.1 Shear Lug Evaluation RAI 03.08.04-21S3 Shear lugs comprising of (steel bar fins) are used for the transfer of the NPM lug restraint l loads to the concrete walls viaby shear. The shear lugs are rectangular shaped fins having dimensions 3 wide x 5 bar and 4 feet long embedded in the concrete.
RAI 03.08.04-21S3 The shear lugs are made of carbon steel (ASTM A572 Gr. 50) having a yield strength of 50 ksi and ultimate strength of 6570 ksi. The 28 day strength of concrete in the walls is 5000 psi.
RAI 03.08.04-21S3 In addition to the shear, there will be tensile load on the fins. This is because the NPM lug load is applied with an eccentricity, causing moment that results in a tensile load on some of the fins. The tensile loads are designed to be resisted by 2.5" diameter through -bolts made of ASTM A193 Gr B7 material having a yield strength of 105 ksi and an ultimate strength of 125 ksi.
RAI 03.08.04-21S3 Figure 3B-51 shows a layout of the shear lugs and the through -bolts. There are 32 through-bolts that correspond to each lug of the NPM as shown in Figure 3B-51. The through-bolt is 2.5 in diameter and fabricated from ASTM A193 GR B7 Steel, Fy=105 ksi. The total shear capacity of the through-bolts is 5573 kips. This results in a D/C ratio (assuming a design load of 3500 kips) of 0.63.
The tensile capacity of the through bolts is the smaller of the bolt steel strength and the concrete strength.
RAI 03.08.04-21S3 The through-bolt is 2.5 in diameter and fabricated from ASTM A193 GR B7 Steel. The through-bolt tensile D/C ratio (assuming a design load of 3500 kips)
NuScale Final Safety Analysis Report Design Reports and Critical Section Details Tier 2 3B-32 Draft Revision 2 is 0.51. This D/C ratio is from the most highly stressed fin in tension. Therefore the through-bolts are acceptable and will exhibit ductile behavior.
RAI 03.08.04-21S3 The D/C ratio for punching shear on the wing wall has been determined to be 0.26. For the pool wall, this ratio is 0.20. The D/C ratio for the concrete bearing strength is 0.40.
The bending stress in the 2" thick liner plate can be bounded by considering the moment at the base of highest loaded shear lug as an upper bound moment in the liner plate.
RAI 03.08.04-21S3, RAI 03.08.04-36 From Table 3B-26, the maximum moment on the plate occurs at the shear lug at Y = 88.2" for lug load in the +Y direction. Please see Table 3B-56, which provides D/C ratios for the various lug component stress checks. The D/C ratios listed in Table 3B-56 are for the individual modes of failure for components of the lug assembly. In this table, the demand is the load that is resisted by each component, due to an applied total load of 3500 kips in the SAP2000 model.This moment produces a bending stress in the liner of 23.12 ksi. This is much less than the 100.8 ksi yield strength of the liner. The resulting D/C is 0.23.
RAI 03.08.04-21S3 The highest D/C ratio is for concrete bearing against the shear lugs at 0.777.
Since this maximum ratio is due to the 3500 kips load, the maximum capacity of the lug assembly is 3500 kips/0.777=4500 kips.
3B.2.7.4.2 Overall Lug Restraint Reaction RAI 03.07.02-10, RAI 03.08.04-36 Table 3B-27 presents the maximumSASSI envelope lug reactions for all twelve bays using the three analysis cases with Soil Type 7 for Capitola input motionCSDRS and Soil Type 9 for CSDRS-HF using the cracked RXB model with 4 percent structural damping in the RXB model. Since these maximum lug reactions are below the lug support design capacity of 3,5004,500 kips, the design is acceptable.
3B.3 Control Building 3B.3.1 Design Report Structural Description and Geometry The CRB is a Seismic Category I concrete structure at elevation 120'-0" and below, except as noted in Section 1.2.2.2. Above EL 120'-0" the CRB is a Seismic Category II steel structure. For a detailed description of the CRB, see Section 3.8.4.1.2. The CRB geometry and floor layout are shown in Figure 1.2-21 through Figure 1.2-27.
NuScale Final Safety Analysis Report Design Reports and Critical Section Details Tier 2 3B-109 Draft Revision 2 RAI 03.08.04-21S3 Table 3B-56: D/C Ratios for Structural Components of the Lug Supports Structural Component Stress Check Demand Capacity D/C Shear Lug Plates Concrete Bearing 3.29 ksi 4.23 ksi 77.8%
Shear Lug Plates Plate Bending 41.1 in-k 67.5 in-k 60.9%
Shear Lug Plates Plate Shear (Steel Plate Check) 16.5 kips 90 kips 18.3%
Shear Lug Plates Plate Shear (Concrete Check-Single) 790 kips 2523 kips 31.3%
Shear Lug Plates Plate Shear (Concrete Check-Group) 3500 kips 5573 kips 62.8%
Shear Lug Plates Shear Friction (At the tip of the lugs) 3500 kips 6966 kips 50.2%
Through Bolts Tensile Stress 804 kips 1576 kips 51.0%
RXM Support Wall Punching Shear 888 kips 3394 kips 26.1%
Pool Wall Punching Shear 888 kips 4412 kips 20.1%
2" Liner Plate Bearing Stress 804 kips 1989 kips 40.4%
2" Liner Plate Bending Stress 11.6 ksi 100.8 ksi 11.5%