ML24348A113
| ML24348A113 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 12/13/2024 |
| From: | Shaver M NuScale |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| Shared Package | |
| ML24348A112 | List: |
| References | |
| RAIO-176219 | |
| Download: ML24348A113 (1) | |
Text
RAIO-176219 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com December 13, 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. 037 (RAI-10357 R1) on the NuScale Standard Design Approval Application
REFERENCE:
NRC Letter to NuScale, Request for Additional Information No. 037 (RAI-10357 R1), dated October 17, 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-10357 R1:
15.0.5-1 is the proprietary version of the NuScale Response to NRC RAI No. 037 (RAI-10357 R1, Question 15.0.5-1). 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.
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 13, 2024.
Sincerely, Mark W. Shaver Director, Regulatory Affairs NuScale Power, LLC
RAIO-176219 Page 2 of 2 12/13/2024 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 Stacy Joseph, Senior Project Manager, NRC
- NuScale Response to NRC Request for Additional Information RAI-10357 R1, Question 15.0.5-1, Proprietary Version : NuScale Response to NRC Request for Additional Information RAI-10357 R1, Question 15.0.5-1, Nonproprietary Version : Affidavit of Mark W. Shaver, AF-176220
RAIO-176219 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-10357 R1, Question 15.0.5-1, Proprietary Version
RAIO-176219 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-10357 R1, Question 15.0.5-1, Nonproprietary Version
Response to Request for Additional Information Docket: 052000050 RAI No.: 10357 Date of RAI Issue: 10/17/2024 NRC Question No.: 15.0.5-1 Issue FSAR Section 15.0.5 is missing details of the design that are used in the SDA analyses when applying the Extended Passive Cooling and Reactivity Control topical report (XPC LTR). The design of the ECCS Supplemental Boron (ESB) system needs to be sufficiently complete to resolve all safety issues, and the application needs to include system descriptions sufficient to permit understanding of the system designs and their relationship to the safety evaluations. It is noted that during the audit, NuScale documentation stated that (( 2(a),(c) NuScale also stated that (( }} 2(a),(c) Information Requested The following information is missing from the FSAR and needs to be provided in FSAR markups:
- 1. The size, location, orientation, key dimensions, and resistances used in the analyses for the boron dissolver basket, containment mixing pipes and respective collector rail(s).
To address this request during the audit, NuScale provided FSAR markups that include the ESB dissolver basket and mixing tube minimum collection area, nominal dissolver basket diameter, nominal mixing tube size, and dissolver basket and mixing tube minimum condensate channel flow capacity. In an effort to make a risk informed safety-finding, as an alternative to providing the specific information requested above, the ESB FSAR markups provided during the audit are sufficient provided NuScale includes a test in their initial test program to confirm the as-built ESB design adequately reflects the analysis response, as requested in RAI Question 6.3-7.
- 2. The flow area and corresponding losses used in the analyses for the riser holes.
NuScale Nonproprietary NuScale Nonproprietary
- 3. The description of the application of the XPC methodology (Section 5.2.3 in the XPC LTR) regarding the assessment of lower riser hole flow to justify the use of the rates in SDA boron transport analysis needs to be included in the SDA. In addition, the results as requested in Question 15.0.5-6 below, need to be incorporated into this description.
NuScale Response: The design of the emergency core cooling system supplemental boron function is described in Final Safety Analysis Report (FSAR) Section 6.3, Emergency Core Cooling System. FSAR Section 15.0.5.1, Decay and Residual Heat Removal Scenarios, references Section 6.3 for description of the emergency core cooling system supplemental boron function. The analyses in FSAR Section 15.0.5, Extended Passive Cooling for Decay and Residual Heat Removal, use the applicable design information from Section 6.3 as input. FSAR Section 15.0.5 describes key conservatisms or modeling choices applied to the design information in Section 6.3. The information requested by this question is addressed as follows. 1. The response to request for additional information (RAI) question 6.3-7 addresses this request and includes a first of a kind test in the initial test program as described in this RAI. 2. FSAR Section 15.0.5 is revised to include the riser hole flow area and corresponding losses used in the analyses for the riser holes. 3. FSAR Section 15.0.5 is revised to include a description of the application of the methodology described in Section 5.2.3, Assessment of Lower Riser Hole Flow During ECCS Cooling, of Extended Passive Cooling and Reactivity Control Methodology, TR-124587, Revision 0. This revision to FSAR Section 15.0.5 includes the results of the lower riser hole flow assessment that was performed to justify that the lower riser hole flow rates used in the boron transport analysis are conservative, as requested in RAI question 15.0.5-6. Impact on US460 SDAA: FSAR Section 15.0 has been revised as described in the response above and as shown in the markup provided in this response. NuScale Nonproprietary NuScale Nonproprietary
NuScale Final Safety Analysis Report Transient and Accident Analyses NuScale US460 SDAA 15.0-38 Draft Revision 2 Audit Item A-15.0.5-1, Audit Item A-15.0.5-2 ESB parameters used in the boron transport analysis are selected to provide conservative calculations. These parameters include: high-biased mixing tube minor form losses, and nominal inner surface roughness mixing tube length conservatively modeled longer than actual design length mixing tube inlet elevation conservatively modeled lower than actual design elevation mixing tube outlet elevation conservatively modeled higher than actual design elevation Audit Item A-15.0.5-1 boron oxide pellets conservatively modeled as equilateral cylinders with 3/8 in. diameter, which is larger than the actual design diameter, for cases with slow-biased boron dissolution from the ESB Audit Item A-15.0.5-1, Audit Item A-15.0.5-2 The condensate flow into the ESB dissolvers and containment mixing tubes, which is generated by the effective minimum CNV wall condensation area, is modeled in the boron transport and precipitation analyses as described in Reference 15.0-8. The temperature of the ESB condensate is modeled at the saturation temperature of the CNV vapor pressure. Audit Item A-15.0.5-1, Audit Item A-15.0.5-2 RAI 15.0.5-1, RAI 15.0.5-6 Lower riser hole flow rates calculated by NRELAP5 are assessed as described in Reference 15.0-8 and. RAI 15.0.5-1, RAI 15.0.5-6 Results from low RPV pressure cases show that NRELAP5 calculates lower values of riser hole flow and is therefore more conservative than the alternate assessment calculation. NRELAP5 calculates a wide range of flow values, ranging from 0.1 kg/s to 6 kg/s. In contrast, the alternate assessment calculation range is relatively small, from 7 kg/s to 10.6 kg/s. Generally at lower pressures the long term cooling NRELAP5 model shows flow oscillations in the liquid space which tends to distribute the core thermal energy in both the forward and reverse directions as opposed to the alternate assessment calculation solution which assumes a forward flow heat balance energy solution. RAI 15.0.5-1, RAI 15.0.5-6 Results from high RPV pressure cases, with nominal loss coefficients, show that the alternate assessment calculation value is equal to or higher than the NRELAP5 value, implying that the NRELAP5 value is conservative. The NRELAP5 cases apply the nominal loss coefficient.
NuScale Final Safety Analysis Report Transient and Accident Analyses NuScale US460 SDAA 15.0-39 Draft Revision 2 Audit Item A-15.0.5-1, Audit Item A-15.0.5-2 RAI 15.0.5-1, RAI 15.0.5-6 The lower riser hole flow rates calculated by NRELAP5 are determined to be acceptable for use in the boron transport and precipitation analyses because the use of the average riser hole flow from NRELAP5 increases the difference between the calculated core and downcomer boron concentrations during ECCS cooling. With this conservatively biased riser hole flow, the limiting boron transport analysis results demonstrate that the boron concentration in the RPV remains above the critical concentration. The parameters used for modeling riser holes in the extended passive cooling analyses include: RAI 15.0.5-1, RAI 15.0.5-6 total lower riser hole flow area of 7.07 sq in. with forward loss coefficient of 2.8 and reverse loss coefficient of 2.8. RAI 15.0.5-1, RAI 15.0.5-6 grouped upper riser hole flow area of 12 sq in. at each of the four upper riser hole elevations with forward loss coefficient of 5.75 and reverse loss coefficient of 4.75. elevation of riser holes groups are distributed to match the design within constraints of model nodalization forward and reverse losses are considered Audit Item A-15.0.5-1, Audit Item A-15.0.5-2 The result for the limiting cases for the boron transport analysis are given in Table 15.0-18. Results for beginning of cycle (BOC) and middle of cycle (MOC) are also given for the injection line break for comparison. Figures 15.0-5 through Figure 15.0-10 show the boron concentrations and boron masses in the RPV and CNV for the limiting cases. The methodology for calculating boron transport is presented in Reference 15.0-8; calculation of the critical boron concentration accounts for the highest-worth control rod assembly remaining stuck out of the core. Audit Item A-15.0.5-1, Audit Item A-15.0.5-2 The margin to boron precipitation limits is evaluated. Key input parameters and initial conditions used in the limiting boron precipitation case are provided in Table 15.0-22. Audit Item A-15.0.5-1, Audit Item A-15.0.5-2 The minimum difference between core or downcomer concentration and the precipitation limit is recorded along with the time of the minimum in Table 15.0-19. The limiting event is the 100 percent high point vent line outside the CNV. Figure 15.0-11 and Figure 15.0-12 show the boron concentrations and boron masses in the RPV and CNV for the limiting case. The break outside the CNV reduces RCS inventory available for ECCS cooldown, however, margin to boron precipitation is maintained. The lower riser holes maintain mixing during ECCS operation and boron precipitation is
RAIO-176219 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-176220
AF-176220 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. 10357 R1, Question 15.0.5-1) 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 10357 R1, Question 15.0.5-1. 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-176220 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 13, 2024. Mark W. Shaver}}