ML18292A582

SMR TR RAIs - Request for Additional Information Letter No. 9579 (Erai No. 9579) Topical Report Thermal Hydraulic Stability 15.9, Srsb

ML18292A582
Person / Time
Site:	PROJ0769
Issue date:	10/19/2018
From:	NRC
To:	NRC/NRO/DLSE/LB1
References
Download: ML18292A582 (3)

Text

NuScaleTRRaisPEm Resource From: Cranston, Gregory Sent: Friday, October 19, 2018 7:49 AM To: Request for Additional Information Cc: Lee, Samuel; Karas, Rebecca; Skarda, Raymond; Bavol, Bruce; Chowdhury, Prosanta; NuScaleTRRaisPEm Resource

Subject:

Request for Additional Information Letter No. 9579 (eRAI No. 9579) Topical Report Thermal Hydraulic Stability 15.9, SRSB Attachments: Request for Additional Information No. 9579 (eRAI No. 9579).pdf Attached please find NRC staffs request for additional information (RAI) concerning review of the NuScale Topical Report.

Please submit your technically correct and complete response within 60 days of the date of this RAI to the NRC Document Control Desk.

If you have any questions, please contact me.

Thank you.

1

Hearing Identifier: NuScale_SMR_DC_TR_Public Email Number: 103 Mail Envelope Properties (BN1PR09MB0258ECC2AE7261D5CF31B7DA90F90)

Subject:

Request for Additional Information Letter No. 9579 (eRAI No. 9579) Topical Report Thermal Hydraulic Stability 15.9, SRSB Sent Date: 10/19/2018 7:49:27 AM Received Date: 10/19/2018 7:49:33 AM From: Cranston, Gregory Created By: Gregory.Cranston@nrc.gov Recipients:

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

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

Tracking Status: None "Skarda, Raymond" <Raymond.Skarda@nrc.gov>

Tracking Status: None "Bavol, Bruce" <Bruce.Bavol@nrc.gov>

Tracking Status: None "Chowdhury, Prosanta" <Prosanta.Chowdhury@nrc.gov>

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

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

Tracking Status: None Post Office: BN1PR09MB0258.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 345 10/19/2018 7:49:33 AM Request for Additional Information No. 9579 (eRAI No. 9579).pdf 65702 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

Request for Additional Information No. 9579 (eRAI No. 9579)

Issue Date: 10/18/2018 Application

Title:

NuScale Topical Report Operating Company: NuScale Docket No. PROJ0769 Review Section: 15.09 - A.DSRS NuScale Thermal Hydraulic Stability Application Section: 15.9 QUESTIONS 15.09-12 Title 10 of the Code of Federal Regulations (10CFR), Part 50, Appendix A, General Design Criterion (GDC) for Nuclear Power Plants - Criterion 12, "Suppression of reactor power oscillations," requires that oscillations be either not possible or reliably detected and suppressed. The Standard Review Plan (SRP) 15.0.2 acceptance criteria with respect to evaluation models specifies that the chosen mathematical models and the numerical solution of those models must be able to predict the important physical phenomena reasonably well from both qualitative and quantitative points of view.

In Section 10.2, "General Stability Characteristics," of the topical report (TR), TR-0516-49417-P, Figure 10-1 provides an illustration of allowable and forbidden NPM operation, in terms of the decay ratio (DR) band versus riser subcooling, and including a proposed region of safety margin. Bullet 2 in section 10.2 of the TR addresses the decay ratio acceptance criterion of 0.8 (or less). The DR acceptance criterion must be defined with sufficient margin to account for biases, including those introduced by numerical diffusion and uncertainty.

In order to make an affirmative finding, in RAI 9107, the NRC staff requested NuScale to provide an uncertainty analysis for PIM. The RAI 9107 response did not provide such an analysis, rather, argued that the uncertainty is likely less than 0.2 based on a combination of qualitative and quantitative arguments. In terms of quantitative results, there are time traces provided for a flow sensitivity study, but the applicant did not provide the DR values for the sensitivity calculations.

Therefore the staff requests NuScale to:

1. Provide the DR values from the flow sensitivity study,

2. Provide the flow range for each analyzed power level and explain how this flow range is sufficient to cover the uncertainty in the hydraulic modeling, and

3. Provide a thorough, detailed, quantitative uncertainty analysis of the PIM DR, or adjust the PIM DR acceptance criterion from 0.8 above 5 percent rated power to 0.7 above 5 percent rated power.