ML18260A374

LLC - Supplemental Response to NRC Request for Additional Information No. 420 (Erai No. 9459) on the NuScale Design Certification Application

ML18260A374
Person / Time
Site:	NuScale
Issue date:	09/17/2018
From:	Rad Z NuScale
To:	Document Control Desk, Office of New Reactors
Shared Package
ML18260A373	List: ML18260A374
References
AF-0918-61823, RAIO-0918-61822
Download: ML18260A374 (19)

Text

RAIO-0918-61822 September 17, 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. 420 (eRAI No. 9459) on the NuScale Design Certification Application

REFERENCES:

1. U.S. Nuclear Regulatory Commission, "Request for Additional Information No. 420 (eRAI No. 9459)," dated April 12, 2018

2. NuScale Power, LLC Response to NRC "Request for Additional Information No. 420 (eRAI No.9459)," dated May 31, 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 Enclosures to this letter contain NuScale's supplemental response to the following RAI Question from NRC eRAI No. 9459:

03.08.02-18 is the proprietary version of the NuScale Supplemental Response to NRC RAI No.

420 (eRAI No. 9459). NuScale requests that the proprietary version be withheld from public disclosure in accordance with the requirements of 10 CFR § 2.390. The enclosed affidavit (Enclosure 3) supports this request. Enclosure 2 is the nonproprietary version of the NuScale response.

This letter and the enclosed responses 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, Zackary W. Rad Director, Regulatory Affairs NuScale Power, LLC Distribution: Gregory Cranston, NRC, OWFN-8G9A Samuel Lee, NRC, OWFN-8G9A Marieliz Vera, NRC, OWFN-8G9A NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

RAIO-0918-61822 : NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9459, proprietary : NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9459, nonproprietary : Affidavit of Zackary W. Rad, AF-0918-61823 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

RAIO-0918-61822 :

NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9459, proprietary NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

RAIO-0918-61822 :

NuScale Supplemental Response to NRC Request for Additional Information eRAI No. 9459, nonproprietary NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

Response to Request for Additional Information Docket No.52-048 eRAI No.: 9459 Date of RAI Issue: 04/12/2018 NRC Question No.: 03.08.02-18 10 CFR 52.47 requires the design certification applicant to include a description and analysis of the structures, systems, and components with sufficient detail to permit understanding of the system designs. Regulatory Guide 1.216 C.1.k states the details of the analysis and results that should be submitted in report form.

For the CNV Middle Section Model, in Section 3.4 of TR-0917-56119-P, "CNV Ultimate Pressure Integrity," it states that the design was modified to add 7.5 inches of reinforcement around the pressurizer access port opening on the inside surface of the CNV. The report stated that the added reinforcement served to stiffen the CNV shell around the opening and produce less distortion of the access flange, however the addition of the 7.5 inches of reinforcement is not clearly indicated in the drawings of the technical report, nor are there any further details on the reinforcement and its effect on the analysis. Please clearly show the reinforcement on the drawings of the technical report.

It does not appear that the analysis of the CNV Middle Section was re-evaluated to include this 7.5 inches of reinforcement. Please explain why this analysis was not re-evaluated as the reinforcement could produce a different bounding ultimate pressure than is currently indicated in the FSAR.

The RPV support design and RPV lateral support design, which impart stress to the shell of the containment vessel, were both modified since the completion of the containment ultimate pressure analysis. Please include drawings within the technical report that clearly show the differences in design from the one used for the ultimate pressure analysis (for example Figure 3-3) and the current design, to support the statements made that these design changes do not affect the ultimate pressure capacity or buckling results.

NuScale Nonproprietary

NuScale Response:

During a July 18, 2018 NRC public call the staff requested more clarification be added in the Containment Vessel Ultimate Pressure Integrity technical report, TR-0917-56119, to the containment vessel (CNV) middle section model discussion (Section 3.4 Item #2). The statement requiring additional clarification which is underlined, follows:

• The model segment includes the RPV support on the CNV inside surface. The CNV middle section model was used to evaluate membrane strain due to pressure away from local effects per the guidance of Reference 6.1.1, Section C.1.f.4. The RPV support analyzed applies a load and moment to the wall that reasonably represents the support design.

The RPV support design has been revised slightly from that modeled in this analysis. The DCA-submitted RPV support design is shown in Figure 3-5(a) and the RPV support design modeled in the analysis is shown in Figure 3-5(b). The DCA-submitted support design is 2.532 inches below the analyzed support location. The attachment bolt in the DCA-submitted design is also moved away from the CNV wall by an additional 4.325 inches. Since this model is used only to evaluate membrane strain due to pressure away from local effects per the guidance of RG 1.216 Section C.1.f.4, the revised RPV support in the DCA-submitted design does not affect the CNV Ultimate Pressure Capacity results.

An assessment was used to evaluate the impact of the CNV reactor pressure vessel (RPV) support design submitted for the DCA to that analyzed in the CNV ultimate pressure integrity calculation. The assessment demonstrates that the moment on the CNV shell created by the DCA-submitted CNV RPV support design does increase and therefore the bending stress on the CNV shell increases, but not significantly. The assessment also shows that the bending stress does not contribute to the maximum shear stress on the CNV shell.

Maximum shear stress theory is used to access the stress on the CNV shell. The maximum shear stress is determined by the three principal stresses on the CNV shell. The pressure load on the CNV shell creates a circumferential (hoop) stress, longitudinal stress, and a radial stress on the shell. By superposition, the bending stress on the CNV shell, created by the CNV RPV support, is added to the longitudinal stress created by the pressure load. These three stresses (hoop, longitudinal, and radial) form the principal stresses on the CNV shell.

NuScale Nonproprietary

The maximum shear stress is half of the difference between the algebraically largest principal stress and algebraically smallest principal stresses. The hoop stress and radial stress produce the algebraically largest and smallest principal stress, respectively. The longitudinal stress is not a contributor to the calculated maximum shear stress. Therefore, the bending stress created by the CNV RPV support is not a contributor to the maximum shear stress on the CNV shell. The bending stress is not a contributor in determining the maximum shear stress until it is about two times larger than the bending stress determined in the assessment. As a result, a slightly increased bending stress does not contribute to the maximum shear stress on the CNV shell and the CNV RPV support analyzed is acceptable.

Additionally, the maximum shear stress on the CNV shell in the region of the CNV RPV support remains in the elastic region of the material at the reported CNV ultimate pressure. The CNV material in this region has not begun to reach its limit and is not the limiting location on the CNV.

The statement at the end of TR-0917-56119, Section 3.4, Item #2 has been modified and supplemented as follows:

The CNV RPV support analyzed applies a load force and moment to the CNV shell wall that reasonably represents the support design . The load applied to the CNV shell by the DCA-submitted design creates a larger bending stress than that produced by the design analyzed.

However, this load does not produce stress components which contribute to the maximum stress produced on the CNV shell and the CNV ultimate pressure does not need to be re-analyzed for the DCA-submitted design.

Supporting Assessment There are four CNV RPV supports around the circumference of the CNV. Each 90 degree segment of the CNV has identical geometry and loads. So a 90 degree CNV shell segment will be assessed. Both the DCA submitted design and the design in TR-0917-56119 will be assessed.

There are no specific hand equations available to analyze the configuration of the design. So an approximation is made by treating the CNV shell as a flat plate with fixed edges. The simplification of treating the CNV shell as a flat plate is reasonable since the curvature of the CNV shell is large. Treating the edges as fixed is also reasonable because this boundary condition simulates the symmetry plane between 90 degree segments of the CNV shell.

Prior to assessing the bending stress on the CNV shell, created by the RPV deadweight on the CNV RPV support, the moment created on the CNV shell as a result of the load being offset from the CNV shell needs to be determined. To determine the moment acting on the CNV shell NuScale Nonproprietary

from the loaded CNV RPV support, the CNV RPV support is treated as a flat circular plate of constant thickness with the RPV load applied at the bolt circle (B.C.) of the support. The equation from Roark's Formulas for Stress and Strain, 6th edition, for a flat plate of constant thickness with the outer edge fixed and the inner edge free (Table 24, Case 1e) is used. This provides the maximum moment on the CNV shell produced by the RPV deadweight load on the CNV RPV support.

The attachment of the support to the CNV shell transmits the moment from the support to the shell by creating a couple. The bottom of the support will push outwards and the top of the support will pull inwards. The local effects of these loads are not considered. However, the longitudinal length of the CNV RPV support for the DCA submitted design is longer than the length of the design analyzed. The longer length will reduce the outward/inward load and produce a lower local load.

The bending stress on the CNV shell is assessed using the equation from Roark's Formulas for Stress and Strain, 6th edition, for a flat plate with constant thickness, straight edges, and all outer edges fixed. Loading on the plate is from a concentric circle of radius r0 (Table 26, Case 8b.)

The bending stress is then combined by superposition with the longitudinal stress components produced by the inside pressure on the CNV. The maximum shear stress is then determined based on the maximum difference between the algebraically largest principal stress and algebraically smallest principal stress.

The second principal stress is the combined bending and pressure stress, resulting from the support load and the longitudinal stress from the pressure load. The second principal stress is less than the first principal stress and greater than the third principal stress. So the component of stress containing the CNV RPV support bending stress is not contributing to the maximum shear stress. The allowable maximum shear stress, where the shear stress theory would remain applicable, is one half of the yield strength of the material. Using the yield strength of the SA-508 Grade 3, class 2 material at 550°F shows the CNV shell has not yet reached the yield strength of the material.

So the contribution of the bending stress does not contribute to the maximum shear stress on the CNV shell. Additionally, the maximum shear stress on the CNV shell is still within the elastic region of the material and has not begun to approach the limits of the material.

NuScale Nonproprietary

The following is the math supporting the assumption:

DCA submitted design The moment produced on the CNV shell by the RPV deadweight load on the CNV RPV support is assessed using the equation from Roark's Formulas for Stress and Strain, 6th edition, for a flat plate of constant thickness, outer edge fixed and inner edge free (Table 24, Case 1e).

Where:

NuScale Nonproprietary

Geometry parameters needed for the load area of the CNV RPV support on the CNV shell.

NuScale Nonproprietary

The equation from Roark's Formulas for Stress and Strain, 6th edition, for a flat plate with constant thickness, straight edges, and all outer edges fixed and loading from a small concentric circle of radius r0 (Table 26, Case 8b.) Where:

For a plate fixed on the edges and a small distributed load in the center of the plate the moment at the center will equal the moment at the fixed edge. This is equivalent to a beam with fixed ends and a concentrated load in the center of the beam. The moment for this beam case is equal to the load (W') times the length of the beam (ax) divided by 8. Rearranging the equation to get the load gives:

CNV shell stress due to pressure load plus bending of shell due to CNV RPV support NuScale Nonproprietary

Maximum shear stress is less than the allowable maximum shear stress based on the materials yield strength.

Design evaluated for CNV ultimate pressure The moment produced on the CNV shell by the RPV deadweight load on the CNV RPV support is assessed using the equation from Roark's Formulas for Stress and Strain, 6th edition, for a flat plate of constant thickness, outer edge fixed and inner edge free (Table 24, Case 1e).

Where:

NuScale Nonproprietary

Geometry parameters needed for the load area of the CNV RPV support on the CNV shell.

NuScale Nonproprietary

The equation from Roark's Formulas for Stress and Strain, 6th edition, for a flat plate with constant thickness, straight edges, and all outer edges fixed and loading from a small concentric circle of radius r0 (Table 26, Case 8b.) Where:

For a plate fixed on the edges and a small distributed load in the center of the plate the moment at the center will equal the moment at the fixed edge. This is equivalent to a beam with fixed ends and a concentrated load in the center of the beam. The moment for this beam case is equal to the load (W) times the length of the beam (ax) divided by 8. Rearranging the equation to get the load gives:

CNV shell stress due to pressure load plus bending of shell due to CNV RPV support NuScale Nonproprietary

This assessment is an estimate of the expected stress produced by the CNV RPV support with an internal pressure applied. The impact of the bending stress created on the CNV shell is a minor component that gets added to the longitudinal pressure stress. As long as the longitudinal stress does not become larger than the hoop stress or smaller than the radial stress the stress intensity of the CNV shell is not impacted. The calculated bending stress created by the CNV RPV support would have to double before it would begin to impact the CNV shell maximum shear stress.

Impact on DCA:

Technical Report TR-0917-56119, CNV Ultimate Pressure Integrity, has been revised as described in the response above and as shown in the markup provided in this response.

NuScale Nonproprietary

CNV Ultimate Pressure Integrity TR-0917-56119-NP Draft Rev. 10 Technical Report cover due to a higher pressure is therefore needed to reach the failure criteria specified in Section 3.1. Therefore, the resultant calculated CNV ultimate pressure produces a lower, bounding ultimate pressure from that expected with the added reinforcement.

• The model segment includes the RPV support on the CNV inside surface.

The CNV middle section model was used to evaluate membrane strain due to pressure away from local effects per the guidance of Reference 6.1.1, Section C.1.f.4. The CNV RPV support analyzed applies a loadforce and moment to the CNV shell. The load applied to the CNV shell by the DCA-submitted design creates a larger bending stress than that produced by the design analyzed. However, this load does not produce stress components which contribute to the maximum stress produced on the CNV shell and the CNV ultimate pressure analysis does not need to be re-analyzed for the DCA-submitted design.wall that reasonably represents the support design.

The RPV support design has been revised slightly from that modeled in this analysis. The DCA-submitted RPV support design is shown in Figure 3-5(a) and the RPV support design modeled in the analysis is shown in Figure 3-5(b). The DCA-submitted support design is 2.532 inches below the analyzed support location. The attachment bolt in the DCA-submitted design is also moved away from the CNV wall by an additional 4.325 inches. Since this model is used only to evaluate membrane strain due to pressure away from local effects per the guidance of RG 1.216 Section C.1.f.4, the revised RPV support in the DCA-submitted design does not affect the CNV Ultimate Pressure Capacity results.

• Parent material, cladding and threaded inserts were modeled as separate material properties with shared boundaries. Other bolting components were modeled as separate parts.

• Fasteners were modeled using minimum minor (thread root) bolt diameters.

3. CNV Bottom Section Model

• A 1/96 slice of the total CNV bottom section was modeled. The model includes the refueling flanges and a closure bolt. One slice plane is through the centerline of the CNV and passes through the centerline of the closure bolt on the 0-degree axis. The second slice plane passes mid-way between closure studs. The blue segment in Figure 3-6 Figure 3 4 shows the segment modeled and alignment with the closure studs.

• Parent material and cladding were modeled as separate material properties with shared boundaries. Other bolting components were modeled as separate parts.

• Fasteners were modeled using minimum minor (thread root) bolt diameters.

© Copyright 20187 by NuScale Power, LLC 15

RAIO-0918-61822 :

Affidavit of Zackary W. Rad, AF-0918-61823 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvalis, Oregon 97330, Office: 541.360.0500, Fax: 541.207.3928 www.nuscalepower.com

NuScale Power, LLC AFFIDAVIT of Zackary W. Rad I, Zackary W. Rad, state as follows:

1. I am the Director, Regulatory Affairs of NuScale Power, LLC (NuScale), and as such, I have been specifically delegated the function of reviewing the information described in this Affidavit that NuScale seeks to have withheld from public disclosure, and am authorized to apply for its withholding on behalf of NuScale.

2. I am knowledgeable of the criteria and procedures used by NuScale in designating information as a trade secret, privileged, or as confidential commercial or financial information. This request to withhold information from public disclosure is driven by one or more of the following:

a. The information requested to be withheld reveals distinguishing aspects of a process (or component, structure, tool, method, etc.) whose use by NuScale competitors, without a license from NuScale, would constitute a competitive economic disadvantage to NuScale.

b. The information requested to be withheld consists of supporting data, including test data, relative to a process (or component, structure, tool, method, etc.), and the application of the data secures a competitive economic advantage, as described more fully in paragraph 3 of this Affidavit.

c. Use by a competitor of the information requested to be withheld would reduce the competitor's expenditure of resources, or improve its competitive position, in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product.

d. The information requested to be withheld reveals cost or price information, production capabilities, budget levels, or commercial strategies of NuScale.

e. The information requested to be withheld consists of patentable ideas.

3. Public disclosure of the information sought to be withheld is likely to cause substantial harm to NuScale's competitive position and foreclose or reduce the availability of profit-making opportunities. The accompanying Request for Additional Information response reveals distinguishing aspects about the method by which NuScale develops its components in the NuScale design.

NuScale has performed significant research and evaluation to develop a basis for this method and has invested significant resources, including the expenditure of a considerable sum of money.

The precise financial value of the information is difficult to quantify, but it is a key element of the design basis for a NuScale plant and, therefore, has substantial value to NuScale.

If the information were disclosed to the public, NuScale's competitors would have access to the information without purchasing the right to use it or having been required to undertake a similar expenditure of resources. Such disclosure would constitute a misappropriation of NuScale's intellectual property, and would deprive NuScale of the opportunity to exercise its competitive advantage to seek an adequate return on its investment.

AF-0918-61823

4. The information sought to be withheld is in the enclosed response to NRC Request for Additional Information No. 420, eRAI 9459. The enclosure contains the designation "Proprietary" at the top of each page containing proprietary information. The information considered by NuScale to be proprietary is identified within double braces, "((" in the document.

5. The basis for proposing that the information be withheld is that NuScale treats the information as a trade secret, privileged, or as confidential commercial or financial information. NuScale relies upon the exemption from disclosure set forth in the Freedom of Information Act ("FOIA"), 5 USC § 552(b)(4), as well as exemptions applicable to the NRC under 10 CFR §§ 2.390(a)(4) and 9.17(a)(4).

6. Pursuant to the provisions set forth in 10 CFR § 2.390(b)(4), the following is provided for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld:

a. The information sought to be withheld is owned and has been held in confidence by NuScale.

b. The information is of a sort customarily held in confidence by NuScale and, to the best of my knowledge and belief, consistently has been held in confidence by NuScale.

The procedure for approval of external release of such information typically requires review by the staff manager, project manager, chief technology officer or other equivalent authority, or the manager of the cognizant marketing function (or his delegate), for technical content, competitive effect, and determination of the accuracy of the proprietary designation. Disclosures outside NuScale are limited to regulatory bodies, customers and potential customers and their agents, suppliers, licensees, and others with a legitimate need for the information, and then only in accordance with appropriate regulatory provisions or contractual agreements to maintain confidentiality.

c. The information is being transmitted to and received by the NRC in confidence.

d. No public disclosure of the information has been made, and it is not available in public sources. All disclosures to third parties, including any required transmittals to NRC, have been made, or must be made, pursuant to regulatory provisions or contractual agreements that provide for maintenance of the information in confidence.

e. Public disclosure of the information is likely to cause substantial harm to the competitive position of NuScale, taking into account the value of the information to NuScale, the amount of effort and money expended by NuScale in developing the information, and the difficulty others would have in acquiring or duplicating the information. The information sought to be withheld is part of NuScale's technology that provides NuScale with a competitive advantage over other firms in the industry.

NuScale has invested significant human and financial capital in developing this technology and NuScale believes it would be difficult for others to duplicate the technology without access to the information sought to be withheld. I declare under penalty of perjury that the foregoing is true and correct. Executed on September 17, 2018. Zackary Z k W. R W Radd AF-0918-61823}}