ML24215A010

LLC, Response to Sdaa Audit Question Number A-3.4.1-2

ML24215A010
Person / Time
Site:	05200050
Issue date:	08/02/2024
From:	NuScale
To:	Office of Nuclear Reactor Regulation
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Download: ML24215A010 (1)

Text

Response to SDAA Audit Question Question Number: A-3.4.1-2 Receipt Date: 12/18/2023 Question:

SDAA Table 3.4-1 contains limiting flood sources and indicates break type were evaluated as Circumferential Break and majority of the limiting sources are FP failures. In Table 3.4-1, its not clear how the Max Flood Height (ft) column values were derived for the RXB and CRB. The staff request the following information related to Table 3.4-1:

a.

Define acronyms FP 8 and UW 1.25 and clarify in SDAA.

b.

Define Max Flood Height (ft) and how values were derived.

c.

Provide description of Flood Barrier to C306 and how the circumferential break was used to evaluate barrier source in RXB d.

Provide discussion on parameters used to define Fire Suppression flood height within the CRB.

e.

How were max flood height derived.

Response

A. FP is an acronym for the fire protection system (FPS) and UW is an acronym for the utility water system (UWS). These should be FPS and UWS in the SDAA as shown in Table 1.1-1:

Acronyms and Abbreviations. The change to the acronyms is shown in the attached changes. The numbers indicate the size of pipe.

B. For each flood zone, the limiting steady-state flood height is found based on the source in the zone with the largest total release. Flood heights are calculated for both a circumferential break (for non-seismic piping) and a leakage crack (for seismically qualified piping). The flood height is calculated using Equation 2 below.

The total release from a flood source is determined based on the release flow rate and the time to detect and isolate the release.

NuScale Nonproprietary NuScale Nonproprietary

Equation 1: Source Release Volume

=

Where:

V = Source release volume (ft3)

Q = Source release rate (ft3/s) t = Isolation time (s)

Source detection and isolation time (t) is identified in Audit Response A-3.4.1-7. Steady-state flood levels are calculated using the total source release and the available floor area.

Equation 2: Flood Height H =

Where:

H = Flood height (ft)

V = Source release volume (ft3)

A = Floodable area (ft2)

C.

((2(a),(c) D. Flood height from fire suppression is evaluated using the same method as described in Part B of this question. For the total source release, the fire suppression system is assumed to be isolated after 60 minutes. In addition to the sprinklers from a fire suppression release, it is assumed there is an additional 250 gallons per minute (gpm) of flow from a manually operated fire hose for one hour and is used as the bounding value for the fire hose contribution to a fire suppression release.

Flow Demand from Fire Suppression - 300 gpm

Fire hose flow rate - 250 gpm

Sprinkler actuation time - 1 hr E. See response to Part B. Markups of the affected changes, as described in the response, are provided below: NuScale Nonproprietary NuScale Nonproprietary

NuScale Final Safety Analysis Report Water Level (Flood) Design NuScale US460 SDAA 3.4-10 Draft Revision 2 Audit Question A-3.4.1-2 Table 3.4-1: Limiting Flooding Sources and Maximum Steady-State Flood Heights Building Zone Limiting Sources Break Type Max Flood Height (ft) RXB (( Withheld - See Part 9 }} Fire Protection System (FPS) 8 (Stairwell Flow) Circumferential Break 4.1 (( Withheld - See Part 9 }} FPS 8 (Drain Backflow) Circumferential Break 15.0 (( Withheld - See Part 9 }} FPS 8 Circumferential Break 15.0 (( Withheld - See Part 9 }} FPS 8 Circumferential Break 12.8 (( Withheld - See Part 9 }} FPS 8 (Stairwell Flow) Circumferential Break 8.4 (( Withheld - See Part 9 }} FPS 8 Circumferential Break 3.8 (( Withheld - See Part 9 }} FPS 8 (Stairwell Flow) Circumferential Break 12.8 (( Withheld - See Part 9 }} FPS 8 Circumferential Break 6.6 (( Withheld - See Part 9 }} Flood Barrier to C306 Circumferential Break (( Withheld - See Part 9 }} Flood Barrier to C319 Circumferential Break (( Withheld - See Part 9 }} FPS 8 Circumferential Break 4.3 (( Withheld - See Part 9 }} FPS 4 Circumferential Break 3.1 (( Withheld - See Part 9 }} FPS 4 Circumferential Break 2.7 (( Withheld - See Part 9 }} Utility Water System (UWS) 1.25 Circumferential Break 0.7 (( Withheld - See Part 9 }} FPS 4 Circumferential Break 5.3 (( Withheld - See Part 9 }} FPS 4 Circumferential Break 5.4 CRB (( Withheld - See Part 9 }} Utility Water Circumferential Break 0.6 (( Withheld - See Part 9 }} Fire Suppression 1.0 (( Withheld - See Part 9 }} Fire Suppression 0.6 (( Withheld - See Part 9 }} Fire Suppression 1.9 (( Withheld - See Part 9 }} There are no flood sources in the MCR (( Withheld - See Part 9 }} Potable Water Leakage Crack 0.2}}