ML24215A067

LLC, Response to Sdaa Audit Question Number A-3.9.4-6

ML24215A067
Person / Time
Site:	05200050
Issue date:	08/02/2024
From:	NuScale
To:	Office of Nuclear Reactor Regulation
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Download: ML24215A067 (1)

Text

Response to SDAA Audit Question Question Number: A-3.9.4-6 Receipt Date: 09/18/2023 Question:

Follow-up to A-3.9.4-4: The testing conducted in Erlangen for the Design Certification Application used the seismic displacements derived from calculations associated with the Design Certification Application. Please provide a comparison of the seismic displacement values between the DCA and SDAA and confirm that the displacements used for the DCA testing bound the SDAA displacement values.

Response

The original response submitted on October 13, 2023 is revised to address Staffs feedback.

With regards to seismic loading, the NuScale Power Plant US460 standard design control rod drive system (CRDS) design configuration is similar to the US600 DCA design used during testing. For the US460, the lowest Intermediate CRDS Support near the CRDS Alignment Cone was removed and the diametric gap size between the drive shaft outer diameter (OD) and the supports inner diameter (ID) was increased. Both of these modifications result in positive changes in regards to control rod assembly (CRA) insertion.

Calculations for the relative seismic displacements at the control rod driveline support locations are complete and show the US600 DCA Erlangen test data bounds the US460 design.

The physical test set up from the Erlangen CRA insertion test implemented ((2(a),(c) NuScale Nonproprietary NuScale Nonproprietary

(( }}2(a),(c) By comparison, the calculated US460 standard design maximum deflection from vertical is (( }}2(a),(c) The US460 standard design seismic displacements are bounded by the physical testing performed at Erlangen. The US460 standard design calculation set up corresponds to the test set up. The seismic displacement values are relative to the control rod drive mechanism bolted flange on top of the Reactor Pressure Vessel (RPV), which was a fixed boundary condition during testing. ((

}}2(a),(c) This analysis setup allows for direct comparison with the test results and the estimated displacements of the US460 standard design approval application (SDAA) CRDS to ensure the estimated displacements are bound by the Erlangen test data.

Control Rod Drive Shaft (CRDS) Support Relative Movement Calculations for the relative seismic displacements at the US460 control rod driveline support are provided. (( }}2(a),(c) NuScale Nonproprietary NuScale Nonproprietary

(( }}2(a),(c), ECI NuScale Nonproprietary NuScale Nonproprietary

(( }}2(a),(c), ECI NuScale Nonproprietary NuScale Nonproprietary

(( }}2(a),(c), ECI NuScale Nonproprietary NuScale Nonproprietary

(( }}2(a),(c), ECI NuScale Nonproprietary NuScale Nonproprietary

(( }}2(a),(c), ECI No changes to the SDAA are necessary. NuScale Nonproprietary NuScale Nonproprietary}}