ML25083A094
| ML25083A094 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 03/24/2025 |
| From: | Shaver M NuScale |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| Shared Package | |
| ML25083A093 | List: |
| References | |
| RAIO-180446 | |
| Download: ML25083A094 (1) | |
Text
RAIO-180446 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com March 24, 2025 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 Revised Response to NRC Request for Additional Information No. 033 (RAI-10298 R1) on the NuScale Standard Design Approval Application
REFERENCES:
- 1.
NRC Letter to NuScale, Request for Additional Information No.
033 (RAI-10298-R1), dated October 31, 2024
- 2.
NuScale Letter to NRC, NuScale Power, LLC Response to NRC Request for Additional Information No. 033 (RAI-10298 R1) on the NuScale Standard Design Approval Application, dated February 27, 2025 (ML25058A231)
The purpose of this letter is to provide the NuScale Power, LLC (NuScale) revised response to the referenced NRC Request for Additional Information (RAI).
The enclosure to this letter contains NuScale's revised response to the following RAI question from NRC RAI-10298 R1:
XPC.LTR-21 The enclosed RAI response addresses NRC feedback and supersedes the RAI response provided in Reference 2.
is the proprietary version of the NuScale response to NRC RAI No. 033 (RAI-10298 R1, Question XPC.LTR-21). 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 makes no regulatory commitments and no revisions to any existing regulatory commitments.
RAIO-180446 Page 2 of 2 03/24/2025 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com 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 March 24, 2025.
Sincerely, Mark W. Shaver Director, Regulatory Affairs NuScale Power, LLC Distribution:
Mahmoud Jardaneh, Chief New Reactor Licensing Branch, NRC Getachew Tesfaye, Senior Project Manager, NRC NuScale Revised Response to NRC Request for Additional Information RAI-10298 R1, Question XPC.LTR-21, Proprietary :
NuScale Revised Response to NRC Request for Additional Information RAI-10298 R1, Question XPC.LTR-21, Nonproprietary :
Affidavit of Mark W. Shaver, AF-180447
RAIO-180446 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com NuScale Revised Response to NRC Request for Additional Information RAI-10298 R1, Question XPC.LTR-21, Proprietary
RAIO-180446 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com NuScale Revised Response to NRC Request for Additional Information RAI-10298 R1, Question XPC.LTR-21, Nonproprietary
Response to Request for Additional Information Docket: 052000050 RAI No.: 10298 Date of RAI Issue: 10/31/2024 NRC Question No.: XPC.LTR-21 Issue During its audit (ML23067A300), the staff observed the following:
(( 2(a),(c) Information Requested Given the minimal margin to recriticality that appears to exist under certain XPC scenarios, please provide additional explanation and justification for how NuScale develops and applies (( }} 2(a),(c) NuScale Nonproprietary NuScale Nonproprietary
NuScale Response: The margin described in the request for information is the subcriticality analysis margin between the calculated results of a conservative boron transport model and the results of a conservative calculation of margin to subcriticality. This analysis margin is conservative compared to more realistic best-estimates of margin to subcriticality during extended passive cooling (XPC). The conservatisms in the XPC subcriticality analysis include:
Highest-worth control rod stuck out
No operator action credited
(( }}2(a),(c)
Supplemental boron mass in dissolvers biased low
(( }}2(a),(c) These conservatisms are reflected in the analysis margin described above. Explanation and justification for how NuScale treats sources of uncertainty, including SIMULATE5 code uncertainty through the development and application of an ((
}}2(a),(c) is provided below.
There are several different approaches for the overall treatment of uncertainties in analysis methodologies. These approaches range from applying conservative input and boundary conditions in lieu of specific application of model uncertainty (e.g., as is generally done in system analysis with NRELAP5) to applying a fully deterministic stack-up of code uncertainty (e.g., as NuScale does in rod ejection analyses), while also deterministically biasing input parameters conservatively. The approach used for the nuclear analysis component of the XPC methodology lies between these two extremes, which is a commonly used approach by NuScale and the nuclear industry. In this approach, a best-estimate code is compared to experimental data (and other codes previously compared to data) for each key calculated parameter of interest. For each parameter, the difference between code and benchmarks is quantified, and then for each application the uncertainty is appropriately propagated into the results of the calculation. Input uncertainty, such as operational configurations (e.g., initial NuScale Nonproprietary NuScale Nonproprietary
power, cycle exposure, axial offset) are deterministically biased in the most conservative combination or determined through parametric sampling of input combinations. The XPC boron transport analysis uses SIMULATE5 to perform reactivity calculations. NuScale performed code qualification (TR-0616-48793-P-A, Revision 1, Nuclear Analysis Codes and Methods Qualification) for the CMS5 code package, which includes SIMULATE5. The purpose of this effort was to justify the validity and applicability of these codes to the simulation of reactor core nuclear physics for pressurized water reactors generally, and the NuScale reactor design concept specifically. Critical characteristics evaluated in the code qualification include ((
}}2(a),(c)
NuScale Nonproprietary NuScale Nonproprietary
((
}}2(a),(c)
NuScale Nonproprietary NuScale Nonproprietary
(( }}2(a),(c) (( }}2(a),(c) NuScale Nonproprietary NuScale Nonproprietary
(( }}2(a),(c) ((
}}2(a),(c)
NuScale Nonproprietary NuScale Nonproprietary
((
}}2(a),(c) A markup to TR-124587 adds (( }}2(a),(c)
NuScale Nonproprietary NuScale Nonproprietary
(( }}2(a),(c) NuScale Nonproprietary NuScale Nonproprietary
(( }}2(a),(c) The XPC methodology uses SIMULATE5 to perform calculations of maximum core boron concentration that would result in a return to criticality. ((
}}2(a),(c)
Impact on Topical Report: Topical Report TR-124587, Extended Passive Cooling and Reactivity Control Methodology, has been revised as described in the response above and as shown in the markup provided in this response. Additional Information: Note this response references a proprietary version of the topical report that is marked as containing export controlled information (ECI). However, the extracted pages of the topical report that are attached to this response do not contain ECI as submitted herein. Notwithstanding, any proprietary information included in the response and the attachment hereto shall be withheld per 10 CFR 2.390. NuScale Nonproprietary NuScale Nonproprietary
Extended Passive Cooling and Reactivity Control Methodology TR-124587-NP Draft Revision 1 © Copyright 2024 by NuScale Power, LLC 274 RAI XPC.LTR-21 (( }}2(a),(c) 6.4 Assess Margin to Criticality The boron concentration results in the module determined from the boron transport calculations are compared to the appropriate SIMULATE5 calculated critical boron concentration results to demonstrate that the core boron concentration remains above the critical boron concentration for at least 72 hours after event initiation. Audit Question A-XPC.LTR-6 For analyses of events with reduced-power operating histories before the event, operational limits such as RCS boron concentration or power-maneuvering limits (e.g., power ascent rate limit) can be applied to the analysis. Figure 6-4 shows an example of limits on RCS boron concentration based on the time-integral power below full power. For a given integral down-power, initial RCS boron concentrations greater than the limit (i.e., above the limit curve), combined with power ascent rate limits, ensure core boron concentration results determined from the boron transport calculations remain above the critical boron concentration for at least 72 hours after event initiation.
RAIO-180446 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-180447
AF-180447 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 Revised Response to NRC Request for Additional Information (RAI No. 10298 R1, Question XPC.LTR-21) 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 revised response to NRC Request for Additional Information RAI No. 10298 R1, Question XPC.LTR-21. 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-180447 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 March 24, 2025. Mark W. Shaver}}