ML25063A183
| ML25063A183 | |
| Person / Time | |
|---|---|
| Site: | 05200050 |
| Issue date: | 03/04/2025 |
| From: | Shaver M NuScale |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RAIO-167621, RAI-10105-R1 | |
| Download: ML25063A183 (1) | |
Text
RAIO-167621 NuScale Power, LLC 1100 NE Circle Blvd., Suite 200 Corvallis, Oregon 97330 Office 541.360.0500 Fax 541.207.3928 www.nuscalepower.com March 04, 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 Response to NRC Request for Additional Information No. 010 (RAI-10105-R1) on the NuScale Standard Design Approval Application
REFERENCES:
- 1. NRC Letter to NuScale, Request for Additional Information No. 010 (RAI-10105-R1), dated November 18, 2023 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-10105 R1:
9.1.5-3 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 March 04, 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 Greg Cranston, Project Manager, NRC
RAIO-167621 Page 2 of 2 03/04/2025 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-10105, Question 9.1.5-3, Nonproprietary
RAIO-167621 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-10105, Question 9.1.5-3, Nonproprietary
NuScale Nonproprietary NuScale Nonproprietary Response to Request for Additional Information Docket: 052000050 RAI No.: 10105 Date of RAI Issue:11/18/2023 NRC Question No.: 9.1.5-3 REGULATORY BASIS GDC 1, 2 and 4 of Appendix A to 10 CFR Part 50 apply to the design, fabrication, and testing of SSCs important to safety to maintain quality standards, to the ability of structures, equipment, and mechanisms to withstand the effects of earthquakes, and to the protection of safety-related equipment from the effects of internally generated missiles (i.e., dropped loads), respectively.
ISSUES SDAA FSAR Table 9.1.5-1, "Heavy Load Handling Equipment Design Data," Note 1 for the reactor building crane main hoist and lower block assembly lists the following two items:
- Item 4332: Use of 1.11 for the design factor in plate buckling for extreme environmental loads.
The basis is not clear justifying the use of the 1.11 design factor for plate buckling under extreme environmental loads.
- Item 4334: Alternate methodology for spacing of transverse stiffeners. No alternate methodology was described for determining the spacing of transverse stiffeners.
INFORMATION REQUESTED For Item 4332, provide and justify the basis for the design factor of 1.11 for plate buckling under extreme environmental loads. The basis for this design factor can borrow from the justification used in the ASME Code change, but for clarity should be submitted for review.
For Item 4334, describe the alternate methodology for the spacing of transverse stiffeners. If required, update Section 9.1.5 accordingly.
NuScale Nonproprietary NuScale Nonproprietary NuScale Response:
Exception to ASME NOG-1-2020 Paragraph 4332 In the American Society of Mechanical Engineers (ASME) NOG-1-2020 paragraph 4332, the design factor for the base allowable compression stress within a structural member for the extreme environmental loading condition is inconsistent with the required design factor for buckling (DFB) stability. This inconsistency does not exist for the other three loading conditions (operating, construction, and severe environmental).
NOG-1-2020 Table 4311-1 shows the maximum allowable stresses in structural members and paragraph 4332.1 defines design factors against buckling for structural members.
Table 1 shows the values where beta is one (uniform compression) for the equations in NOG 2020 Table 4332.1-1. Table 1 also provides the reciprocal of these values that can be related to the values in NOG-1-2020 Table 4311-1.
Table 1 Design Factors for Crane Loading Conditions Loading Condition Beta = 1 Reciprocal Operating 2.0 0.5 Construction 2.0 0.5 Severe Environmental 1.5 0.67 Extreme Environmental 1.35 0.74 The reciprocal values in Table 1 correlate very well with NOG-1-2020 Table 4311-1 for compression, with notable exception for the extreme environmental category. To provide consistent design factors for the different crane loading conditions, the DFB in paragraph 4332.1 for extreme environmental loading condition is replaced with a value of 1.11. The DFB reciprocal of 1.11 equates to the 0.9 value found in Table 4311-1 for extreme environmental loading conditions. For the exception to NOG-1-2020 Paragraph 4332, a non-varying value for the DFB is selected to avoid differential design margins.
Exception to ASME NOG-1-2020 Paragraph 4334 Paragraph 4334 of NOG-1-2020 provides guidance on the spacing of transverse stiffeners and diaphragms within fabricated box girders. Paragraph 4334 in NOG-1-2020 does not contain
NuScale Nonproprietary NuScale Nonproprietary guidance on where or how the equations are to be applied. Interpretation of the actual meaning of the requirement and which sections require stiffeners is unclear.
As part of developing the exception to paragraph 4334, the guidance in the section was compared against CMAA-70-2020, another widely used crane design standard that is referenced in NOG-1-2020. The equation in paragraph 4334 of NOG-1-2020 is inconsistently used compared to how the CMAA document applies it. In CMAA-70, the equation in paragraph 4334 of NOG-1-2020 is found in Section 3.5.4. The coefficients are different because of the different units of measurement, but the equation is otherwise identical. In CMAA-70, this equation is only applied to stiffeners at the girder ends and near large web penetrations.
Additionally, a review of the CMAA document revealed that NOG-1-2020 was missing a limiting equation present in CMAA-70 which allows sections with smaller web height to thickness ratios to forgo transverse stiffeners. The exception taken to ASME NOG-1-2020 Paragraph 4334 resolves the inconsistencies described.
Impact on US460 SDAA:
There are no impacts to US460 SDAA as a result of this response.