ML18120A365

SMR DC RAI - Request for Additional Information No. 442 Erai No. 9479 (15.06.05)

ML18120A365
Person / Time
Site:	NuScale
Issue date:	04/30/2018
From:	NRC
To:	NRC/NRO/DNRL/LB1
References
Download: ML18120A365 (3)

Text

NuScaleDCRaisPEm Resource From: Chowdhury, Prosanta Sent: Monday, April 30, 2018 3:31 PM To: Request for Additional Information Cc: Lee, Samuel; Cranston, Gregory; Franovich, Rani; Karas, Rebecca; Thurston, Carl; NuScaleDCRaisPEm Resource

Subject:

Request for Additional Information No. 442 eRAI No. 9479 (15.06.05)

Attachments: Request for Additional Information No. 442 (eRAI No. 9479).pdf Attached please find NRC staffs request for additional information (RAI) concerning review of the NuScale Design Certification Application.

The NRC Staff recognizes that NuScale has preliminarily identified that the response to one or more questions in this RAI is likely to require greater than 60 days. NuScale is expected to provide a schedule for the RAI response by email within 14 days.

If you have any questions, please contact me.

Thank you.

Prosanta Chowdhury, Project Manager Licensing Branch 1 (NuScale)

Division of New Reactor Licensing Office of New Reactors U.S. Nuclear Regulatory Commission 301-415-1647 1

Hearing Identifier: NuScale_SMR_DC_RAI_Public Email Number: 471 Mail Envelope Properties (BN7PR09MB2609F1E2A5EAE7F77C9EBCE29E820)

Subject:

Request for Additional Information No. 442 eRAI No. 9479 (15.06.05)

Sent Date: 4/30/2018 3:31:23 PM Received Date: 4/30/2018 3:31:27 PM From: Chowdhury, Prosanta Created By: Prosanta.Chowdhury@nrc.gov Recipients:

"Lee, Samuel" <Samuel.Lee@nrc.gov>

Tracking Status: None "Cranston, Gregory" <Gregory.Cranston@nrc.gov>

Tracking Status: None "Franovich, Rani" <Rani.Franovich@nrc.gov>

Tracking Status: None "Karas, Rebecca" <Rebecca.Karas@nrc.gov>

Tracking Status: None "Thurston, Carl" <Carl.Thurston@nrc.gov>

Tracking Status: None "NuScaleDCRaisPEm Resource" <NuScaleDCRaisPEm.Resource@nrc.gov>

Tracking Status: None "Request for Additional Information" <RAI@nuscalepower.com>

Tracking Status: None Post Office: BN7PR09MB2609.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 675 4/30/2018 3:31:27 PM Request for Additional Information No. 442 (eRAI No. 9479).pdf 12713 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Request for Additional Information No. 442 (eRAI No. 9479)

Issue Date: 04/30/2018 Application

Title:

NuScale Standard Design Certification 048 Operating Company: NuScale Power, LLC Docket No.52-048 Review Section: 15.06.05 - Loss of Coolant Accidents Resulting From Spectrum of Postulated Piping Breaks Within the Reactor Coolant Pressure Boundary Application Section:

QUESTIONS 15.06.05-5 Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Appendix A, General Design Criterion (GDC) 35, "Emergency Core Cooling," requires that a system to provide abundant emergency core cooling shall be provided. The system safety function shall be to transfer heat from the reactor core following any loss of reactor coolant at a rate such that (1) fuel and clad damage that could interfere with continued effective core cooling is prevented and (2) clad metal-water reaction is limited to negligible amounts. DSRS Section 15.6.5 provides guidance for complying with GDC 35. It requires that evaluation models meet the requirements of 10 CFR 50.46, which states that the evaluation model must include sufficient supporting justification to show that the analytical technique realistically describes the behavior of the reactor system during a loss-of-coolant accident.

Section 5.3.2 of the Long-Term Cooling Methodology (LTC) technical report, TR-0916-51299-P, Rev. 0, a technical report referenced in the DCD Chapter 15 analyses, describes input model changes where it was necessary to isolate heat transfer to the secondary side (SG tubes and DHRS) in order to facilitate code convergence. The applicant admits that this modeling is not consistent with biasing for needed maximum cooldown, and indicated that the effect was negligible based on sensitivity calculations. Based on review of EC-A010-4270 (a calculation supporting the DCD Chapter 15 analyses), staff noted that DHRS was being isolated upon ECCS actuation but did not find any sensitivity analysisor discussions or discussions to justify these changes as being appropriate for the maximum cooldown LTC cases.

Please revise the methodology to include DHRS cooling or provide an analysis justification for DHRS isolation that is appropriate for post-LOCA long-term cooling, and provide markups of any necessary changes to the technical report.