ML24353A252
| ML24353A252 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 12/18/2024 |
| From: | Shaver M NuScale |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| Shared Package | |
| ML24353A251 | List: |
| References | |
| RAIO-177354 | |
| Download: ML24353A252 (1) | |
Text
RAIO-177354 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com December 18, 2024 Docket No.52-050 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738
SUBJECT:
NuScale Power, LLC Response to NRC Request for Additional Information No. 031 (RAI-10296 R1) on the NuScale Standard Design Approval Application
REFERENCE:
NRC Letter to NuScale, Request for Additional Information No. 031 (RAI-10296 R1), dated October 30, 2024 The purpose of this letter is to provide the NuScale Power, LLC (NuScale) response to the referenced NRC Request for Additional Information (RAI).
The enclosure to this letter contains the NuScale response to the following RAI question from NRC RAI-10296 R1:
LOCA.LTR-2 is the proprietary version of the NuScale Response to NRC RAI No. 031 (RAI-10296 R1, Question LOCA.LTR-2). 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 1 has also been determined to contain Export Controlled Information. This information must be protected from disclosure per the requirement of 10 CFR § 810. Enclosure 2 is the nonproprietary version of the NuScale response.
This letter makes no regulatory commitments and no revisions to any existing regulatory commitments.
If you have any questions, please contact Amanda Bode at 541-452-7971 or at abode@nuscalepower.com.
I declare under penalty of perjury that the foregoing is true and correct. Executed on December 18, 2024.
Sincerely, Mark W. Shaver Director, Regulatory Affairs NuScale Power, LLC
RAIO-177354 Page 2 of 2 12/18/2024 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com Distribution:
Mahmoud Jardaneh, Chief New Reactor Licensing Branch, NRC Getachew Tesfaye, Senior Project Manager, NRC Ricky Vivanco, Project Manager, NRC
- NuScale Response to NRC Request for Additional Information RAI-10296 R1, Question LOCA.LTR-2, Proprietary Version : NuScale Response to NRC Request for Additional Information RAI-10296 R1, Question LOCA.LTR-2, Nonproprietary Version : Affidavit of Mark W. Shaver, AF-177355
RAIO-177354 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com NuScale Response to NRC Request for Additional Information RAI-10296 R1, Question LOCA.LTR-2, Proprietary Version
RAIO-177354 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com NuScale Response to NRC Request for Additional Information RAI-10296 R1, Question LOCA.LTR-2, Nonproprietary Version
Response to Request for Additional Information Docket: 052000050 RAI No.: 10296 Date of RAI Issue: 10/30/2024 NRC Question No.: LOCA.LTR-2 Issue The LOCA methodology does not provide an adequate basis for model validation vs. test data
(( 2(a),(c) Riser holes have an impact on thermal hydraulic conditions, for example but not limited to, initial conditions, natural circulation and RCS response; these impacts and any others need to be addressed. Information Requested a) Provide justification via sensitivity studies demonstrating that NRELAP5 can adequately calculate the actual expected NPM response with respect to the integrated topical report model. (( }} 2(a),(c) The potential impact on the RCS response and conditions for the integrated model on the figures of merit calculated by the topical report model and downstream activities should be shown analytically as described below:
- i. Provide sensitivities and evaluations of the impact of riser holes on the integral effects tests responses used for Evaluation Model validation for the LOCA topical report. The various impacts of riser holes on the integral test validation response should be captured in the impacts on the integrated NRELAP5 evaluation model results for LOCA analyses.
ii. Provide sensitivities and evaluations for the impact of riser holes on the total integral response of the LTR models (LOCA, non-LOCA and XPC) to various design basis events and NuScale Nonproprietary NuScale Nonproprietary
conditions that show that the test validation response to riser holes is captured. The impact on the RCS response and conditions for the integrated model on the figures of merit calculated by the LOCA, non-LOCA and XPC topical report models should be shown analytically. b) Revise the LTRs to include the above information. NuScale Response: NuScale evaluated the impact of riser hole flow in the NuScale Power Module (NPM) on the loss of coolant accident (LOCA) figures of merit (FOM) using the integrated NRELAP5 LOCA evaluation model (EM). Nominal riser hole geometry and loss factors are utilized in the LOCA EM as design inputs. For the riser hole sensitivity studies, ((
}}2(a),(c) detailed results of the sensitivity studies, are discussed in the response to request for additional information (RAI) 10297 question NonLOCA.LTR-1.
As detailed in the response to RAI 10297 question NonLOCA.LTR-1, the riser hole area ((
}}2(a),(c)
The LOCA figures of merit of particular interest are minimum critical heat flux ratio (MCHFR), minimum collapsed liquid level (CLL), and peak containment (CNV) pressure. ((
}}2(a),(c)
NuScale Nonproprietary NuScale Nonproprietary
((
}}2(a),(c) Additional information about riser hole modeling during extended ECCS long-term cooling is provided in response to RAI 10298, question XPC.LTR-2.
As discussed further in the response to nonLOCA.LTR-1, riser hole sensitivity studies ((
}}2(a),(c)
NuScale Nonproprietary NuScale Nonproprietary
((
}}2(a),(c) is appropriate for validation of the NRELAP5 code against the measured test data.
Additional details of the ((
}}2(a),(c) detailed results of the sensitivity studies, is discussed in the response RAI 10297 question NonLOCA.LTR-1. The RAI response to NonLOCA.LTR-1 also discusses the impact of changes to the riser hole area for the non-LOCA FOM using the non-LOCA evaluation model.
TR-0516-49422-P, Revision 4, Loss-of-Coolant Accident Evaluation Model, is revised to include discussion of the LOCA riser hole sensitivity studies. Impact on Topical Report: Topical Report TR-0516-49422, Loss-of-Coolant Accident Evaluation Model, has been revised as described in the response above and as shown in the markup provided in this response. NuScale Nonproprietary NuScale Nonproprietary
Loss-of-Coolant Accident Evaluation Model TR-0516-49422-NP Draft Revision 4 © Copyright 2024 by NuScale Power, LLC 80 (( RAI LOCA.LTR-2, 4, 45, 47 RAI LOCA.LTR-2 }}2(a),(c) 5.1.2.4 Downcomer (( }}2(a),(c)
Loss-of-Coolant Accident Evaluation Model TR-0516-49422-NP Draft Revision 4 © Copyright 2024 by NuScale Power, LLC 278 (( }}2(a),(b),(c),ECI 7.5.1.1.2 Hot Leg Riser RAI LOCA.LTR-2 After leaving the core, the flow enters the chimney of the hot leg riser. The hot leg riser extends from above the core shroud to the upper plenum, creating a riser and downcomer configuration to enable natural circulation. The hot leg riser consists of a lower shell, a conical transition, a middle shell containing the flowmeter for the primary circuit, and an upper shell. Flow exits the riser into the upper plenum, which is the space between the hot leg riser outlet and the bottom of the pressurizer baffle plate. (( }}2(a),(c) 7.5.1.1.3 Upper Plenum After leaving the top of the hot leg riser, the flow enters the upper plenum and is directed radially outward to flow down in the annulus between the riser and the RPV shell. The pressurizer baffle plate separates the upper plenum from the pressurizer. Hydraulic communication between the pressurizer and the RPV occurs via holes located in the pressurizer baffle plate. 7.5.1.1.4 Pressurizer The pressurizer is located above the upper plenum and is in thermal-hydraulic communication with the upper plenum via the pressurizer baffle plate holes. The pressurizer maintains primary system pressure during normal steady-state and transient conditions through the use of three heater elements. Each element has ((
}}2(a),(b),(c),ECI of power and is modulated by the facility control system to maintain system pressure.
7.5.1.1.5 Cold Leg Downcomer After leaving the upper plenum, the flow continues downward through the SG section and into the cold leg downcomer region. The cold leg downcomer is the annular space bounded by the RPV shell ID and the hot leg riser outer diameter. When fluid reaches the hot leg riser conical transition shell, the flow area is reduced. Flow exits the cold leg downcomer into the LP before it recirculates back into the core.
Loss-of-Coolant Accident Evaluation Model TR-0516-49422-NP Draft Revision 4 © Copyright 2024 by NuScale Power, LLC 281 are installed in the RVV and RRV lines to model the number of valves that are to open when ECCS actuates. Because the NIST facility has a nominal operating pressure of (( }}2(a),(b),(c),ECI that is less than the NPM pressure of 1,850 psia (12.76 MPa), the test in the NIST facility simulates the NPM transient in progress. Specifically, the RPV and CNV fluid masses in NIST are scaled such that they are (( }}2(a),(b),(c),ECI that of the RPV and CNV fluid masses in the NPM at a corresponding pressure of (( }}2(a),(b),(c),ECI Thus the initial RCS mass inventory and pressure are preserved on a scaled basis and fluid property similitude is maintained throughout the transient. As part of the NIST LOCA tests, (( }}2(a),(b),(c),ECI 7.5.2 Facility NRELAP5 Model RAI LOCA.LTR-2 The NRELAP5 model of the NIST facility is constructed to (( }}2(a),(c)
Loss-of-Coolant Accident Evaluation Model TR-0516-49422-NP Draft Revision 4 © Copyright 2024 by NuScale Power, LLC 282 (( }}2(a),(c) These model features are shown in the NRELAP5 nodalization shown in Figure 7-75. (( }}2(a),(c) Characterization testing under forced flow conditions was also used to characterize the NIST primary loop flow losses. 7.5.3 Facility Test Matrix The NIST facility is used to perform design certification IETs and SETs for the purpose of validating NuScale computer codes, model development and assessment, correlation development, verifying compliance with design requirements, demonstrating design features and capabilities, and addressing regulatory concerns. This section briefly describes the test matrix for the NIST facility. Descriptions of tests used for NRELAP5 code validation are provided in Table 7-6. These are the NIST tests that are the essential subset of tests required to validate NRELAP5 for NPM LOCA calculations. Each of the tests indicate whether they were performed under the NIST-1 or NIST-2 configuration. DHRS was not initiated for any of the testing. Table 7-6 Facility High Priority Tests for NRELAP5 Code Validation (( }}2(a),(b),(c),ECI
Loss-of-Coolant Accident Evaluation Model TR-0516-49422-NP Draft Revision 4 © Copyright 2024 by NuScale Power, LLC 299 through the downcomer, entering the LP where another 180 degree turn (upward) is made into the entrance of the electrically heated core. Various instruments measure differential pressures, flow, temperatures, pressures, and heater power to assess the loop flowrate and pressure losses. 7.5.5.2 Phenomenon Addressed The pertinent phenomena addressed with the HP-05 assessment case are ((
}}2(a),(c) 7.5.5.3 Experimental Procedure The HP-05 experiment consists of inducing a core power ramp at a constant RPV pressure of approximately ((
}}2(a),(b),(c),ECI and a secondary-side pressure of approximately (( }}2(a),(b),(c),ECI Differential pressures around the primary loop were measured to characterize the pressure drops due to form and friction losses. The mass flow rate in the riser and fluid temperatures around the loop are measured. To facilitate comparing to code predictions the core power and temperature rise across the core are used to calculate a theoretical flowrate based on an energy balance. Test HP-05 initiates from a power of (( }}2(a),(b),(c),ECI, at a pressure of (( }}2(a),(b),(c),ECI, and the steady-state natural circulation flow condition. Once steady-state conditions are achieved, (( }}2(a),(b),(c),ECI 7.5.5.4 Special Analysis Techniques RAI LOCA.LTR-2 (( }}2(a),(c) The global response was then confirmed by
Loss-of-Coolant Accident Evaluation Model TR-0516-49422-NP Draft Revision 4 © Copyright 2024 by NuScale Power, LLC 300 comparing the HP-05 experimental loop flow rate and temperature distribution to that predicted by NRELAP5. (( }}2(a),(c) 7.5.5.5 Parameter Ranges Assessed (( }}2(a),(b),(c) 7.5.5.6 Assessment Results (( }}2(a),(b),(c) The NRELAP5 mass flow signal is taken from the same location. The NRELAP5 prediction is closely aligned with the data and shows excellent agreement, with the exception of the behavior demonstrated including at the lowest core power level, where reasonable agreement is obtained. At the lower power level, facility constraints on the secondary side made it difficult to obtain steady state conditions. ((
}}2(a),(c)
Loss-of-Coolant Accident Evaluation Model TR-0516-49422-NP Draft Revision 4 © Copyright 2024 by NuScale Power, LLC 370 7.5.10.5 Special Analysis Techniques This assessment contains analysis techniques and sensitivities relevant to transient simulation for code-to-data comparisons with primary focus on the (( RAI LOCA.LTR-2 }}2(a),(c),ECI 7.5.10.6 Assessment Results: CVCS Discharge Line Break Run 1 is a liquid space break utilizing the CVCS discharge line. Table 7-11 provides the sequence of events for Run 1. Overall, sequence timings between the data and the simulation match well. For this run, (( }}2(a),(c),ECI Table 7-11 LOCA Run 1 Sequence of Events (( }}2(a),(c),ECI
RAIO-177354 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com Affidavit of Mark W. Shaver, AF-177355
AF-177355 Page 1 of 2
NuScale Power, LLC AFFIDAVIT of Mark W. Shaver I, Mark W. Shaver, state as follows: (1) I am the Director of 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 competitors 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 NuScales competitive position and foreclose or reduce the availability of profit-making opportunities. The accompanying Request for Additional Information response reveals distinguishing aspects about the response by which NuScale develops its NuScale Power, LLC Response to NRC Request for Additional Information (RAI No. 10296 R1, Question LOCA.LTR-2) on the NuScale Standard Design Approval Application. NuScale has performed significant research and evaluation to develop a basis for this response 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, NuScales 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 NuScales intellectual property, and would deprive NuScale of the opportunity to exercise its competitive advantage to seek an adequate return on its investment. (4) The information sought to be withheld is in the enclosed response to NRC Request for Additional Information RAI No. 10296 R1, Question LOCA.LTR-2. 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.
AF-177355 Page 2 of 2 (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 NuScales 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 December 18, 2024. Mark W. Shaver}}