ML24215A022

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LLC, Response to Sdaa Audit Question Number A-3.5.3-7
ML24215A022
Person / Time
Site: 05200050
Issue date: 08/02/2024
From:
NuScale
To:
Office of Nuclear Reactor Regulation
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ML24215A000 List: ... further results
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LO-169995
Download: ML24215A022 (1)
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{{#Wiki_filter:Response to SDAA Audit Question Question Number: A-3.5.3-7 Receipt Date: 11/20/2023 Question: Related to audit question A-3.5.3-1: The NuScale revised the FSAR Section 3.5.3.1.1 to .missiles are calculated for the Reactor Building and Control Building external walls and roof, RW-IIa interior barriers, and 100 elevation slab of the Radioactive Waste Building using the equations below. Three rooms 225, 226 and 227 in Figure 1.2-24 are above 100 elevation and designated as RW-IIa, partial walls of rooms 226 and 227 are exterior walls above the ground. The staff has the following questions:

1) Confirm to change Control Building to SC-I portions of the Control Building in Section 3.5.3.1.1 based on the NuScales responses to A-3.5.3-3; and 2). Explain how RW-IIa portions of RWB above the ground are protected from the design-basis hurricane and tornado missile protection.

Response

1) The change that was made pertaining to A-3.5.3-3 for the concrete thickness calculations states Concrete thicknesses to preclude penetration, perforation, spalling, or scabbing from the design-basis hurricane and tornado pipe and sphere missiles are calculated for the Reactor Building and Control Building external walls and roof, RW-IIa interior barriers, and 100 foot elevation slab of the Radioactive Waste Building using the equations below. The identified portions of the Control Building discussed in this section are the SC-I portions of the Control Building. FSAR markups are attached to this response.

NuScale Nonproprietary NuScale Nonproprietary

2) As identified in the US460 Standard Design Approval Application (SDAA) Section 3.5, The RW-IIa portions of the RWB meet design criteria for missiles specified in Table 2 of Regulatory Guide (RG) 1.143, Design Guidance for Radioactive Waste Management Systems, Structures, and Components Installed in Light-Water-Cooled Nuclear Power Plants.

SDAA Section 3.5.1.4 states Hurricane and Tornado-generated missiles are evaluated in the design of safety-related structures and risk-significant SSC outside those structures, which is consistent with SRP 3.5.1.4. Additionally, SDAA Section 3.5.3.1.1 states Interior walls within the RWB identified as missile barriers to protect RW-IIa SSC have been evaluated to provide protection against extreme wind missiles. Markups of the affected changes, as described in the response, are provided below: NuScale Nonproprietary NuScale Nonproprietary

NuScale Final Safety Analysis Report Missile Protection NuScale US460 SDAA 3.5-10 Draft Revision 2 Audit Question A-3.5.3-7 3.5.1.4 Missiles Generated by Tornadoes and Extreme Winds Hurricane and tornado-generated missiles are evaluated in the design of safety-related structures and risk-significant SSC outside those structures. Missiles used in the evaluation are assumed to: be capable of striking from various directions and conform to the Region I missile spectrum in Table 2 of RG 1.76, Design-Basis Tornado and Tornado Missiles for Nuclear Power Plants, for tornado missiles; and to Table 1 and Table 2 of RG 1.221, Design-Basis Hurricane and Hurricane Missiles for Nuclear Power Plants, for hurricane missiles. These spectra are based on the design-basis tornado and hurricane defined in Section 3.3.1 and represent a probability of exceedance events of 1 x 10-7 per year for many potential sites. The selected missiles are a massive high-kinetic-energy missile that deforms on impact, such as an automobile. Audit Question A-3.5.3-7 For SC-I structures, Tthe automobile missile is 16.4 feet by 6.6 feet by 4.3 feet with a weight of 4000 lb and a CDA/m (drag coefficient x projected area/mass) of 0.0343 ft2/lb. This missile has a horizontal velocity of 135 ft/s and a vertical velocity of 91 ft/s in a tornado; and corresponding velocities of 307 ft/s and 85 ft/s, respectively, in a hurricane. The automobile missile is considered capable of impact at altitudes less than 30 ft above grade levels within 1/2 mile of the plant structures. Audit Question A-3.5.3-7 For RW-IIa structures, the automobile missile is 4000 lb with a frontal area of 20.0 sq. ft traveling at 0.2 times maximum wind speed horizontally and 0.14 times maximum wind speed vertically up to a height of 35 ft above grade. a rigid missile that tests penetration resistance, such as a 6-inch diameter Schedule 40 pipe. Audit Question A-3.5.3-7 TFor SC-I structures, the pipe missile is 6.625 inches in diameter by 15 feet long with a weight of 287 lb and a CDA/m of 0.0212 ft2/lb. This missile has a horizontal velocity of 135 ft/s and a vertical velocity of 91 ft/s in a tornado; and corresponding velocities of 251 ft/s and 85 ft/s, respectively, in a hurricane.

NuScale Final Safety Analysis Report Missile Protection NuScale US460 SDAA 3.5-11 Draft Revision 2 Audit Question A-3.5.3-7 For RW-IIa structures, the pipe missile is a 3-inch nominal diameter Schedule 40 pipe with a weight of 75 lb. This missile has a maximum velocity of 0.4 times maximum wind speed horizontally and 0.28 times maximum wind speed vertically. a 1-inch diameter solid steel sphere to test the configuration of openings in protective barriers. Audit Question A-3.5.3-7 TFor SC-I structures, the sphere missile is 1 inch in diameter and weighs 0.147 lb and has a CDA/m of 0.0166 ft2/lb. This missile has a horizontal velocity of 26 ft/s and a vertical velocity of 18 ft/s in a tornado; and corresponding velocities of 224 ft/s and 85 ft/s, respectively, in a hurricane. Audit Question A-3.5.3-7 For RW-IIa structures, there is no postulated solid sphere impact. These missile parameters are key site parameters and are provided in Table 2.0-1. COL Item 3.5-2: An applicant that references the NuScale Power Plant US460 standard design will confirm the design-basis automobile missile parameters for the reference plant of velocity and maximum altitude of impact will not be exceeded as a result of extreme wind conditions that may occur in the vicinity of the site. 3.5.1.5 Site Proximity Missiles (Except Aircraft) As described in Section 2.2, the design does not postulate hazards from nearby industrial, transportation, or military facilities. Therefore, there are no proximity missiles. COL Item 3.5-3: An applicant that references the NuScale Power Plant US460 standard design will evaluate site-specific hazards due to external events, such as turbine failures that can occur at nearby or co-located facilities, which may produce more energetic missiles than the design-basis missiles defined in Section 3.5.1. 3.5.1.6 Aircraft Hazards As described in Section 2.2, the design does not postulate hazards from nearby industrial, transportation, or military facilities. Therefore, there are no design-basis aircraft hazards. Discussion of the beyond-design-basis aircraft impact assessment is in Section 19.5.

NuScale Final Safety Analysis Report Missile Protection NuScale US460 SDAA 3.5-13 Draft Revision 2 Audit Question A-3.5.3-1, Audit Question A-3.5.3-7 Concrete thicknesses to preclude perforationpenetration, perforation, spalling, or scabbing from the design-basis hurricane and tornado pipe and sphere missiles are calculated for the Reactor Building, and Control Building external walls and roof, RW-IIa interior barriers, and 100 foot elevation slab of the Radioactive Waste Building, and RW-IIa portion of the Radioactive Waste Building external walls and roof using the equations below. The identified portions of the Control Building discussed in this section are the SC-I portions of the Control Building. Interior walls within the RWB identified as missile barriers to protect RW-IIa SSC have been evaluated and provide protection against extreme wind missiles. Audit Question A-3.5.3-1 Additional design characteristics of the RXB and the CRB, including concrete wall thickness, are in Appendix 3B.2. 3.5.3.1.1.1 Penetration and Spalling Equations The depth of missile penetration, x, is calculated using the following formulas:

where, x = penetration depth, in.,

W = missile weight, lb, d = effective missile diameter, in., N = missile shape factor: flat nosed bodies = 0.72, blunt nosed bodies = 0.84, average bullet nose (spherical end) = 1.00, very sharp nosed bodies = 1.14, V = velocity, ft/sec, x 4KNWd V 1000d

1.8 0.5 for x d--- 2.0

= x KNW V 1000d

1.8 d for x d--- 2.0

+ =}}

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