ML16081A004

NRR E-mail Capture - South Texas Project Units 1 & 2, Draft Request for Additional Information for Thermal-hydraulic Review for GSI-191

ML16081A004
Person / Time
Site:	South Texas
Issue date:	03/18/2016
From:	Lisa Regner Plant Licensing Branch IV
To:	Harrison W South Texas
References
MF2400, MF2401
Download: ML16081A004 (3)

Text

NRR-PMDAPEm Resource From: Regner, Lisa Sent: Friday, March 18, 2016 4:43 PM To: Wayne Harrison

Subject:

DRAFT RAI: STP CLB BAP RAI Attachments: STP BAP RAI.docx

Wayne, In order to continue our review of your risk-informed resolution to GSI-191, the NRC staff needs additional information concerning the HLSO timing currently used in the STP Emergency Operating Procedures as it impacts the thermal-hydraulic analysis with the addition of debris.

Attached is a draft RAI question that, given an acceptable response, should close out the previous questions issued on this topic in 2009 and 2015. If you would like clarifications, we will be available to discuss at the March 31 and/or April 14 public conference calls. Alternately, we can set up a soon clarification call.

Thank you, Lisa Lisa M Regner, Sr. Project Manager, Branch LPLIV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Lisa.Regner@NRC.Gov Office: O8D08 Mail Stop: O8B01 (301) 415-1906 1

Hearing Identifier: NRR_PMDA Email Number: 2718 Mail Envelope Properties (fcc0c6ab467549e5a862b546d097990b)

Subject:

DRAFT RAI: STP CLB BAP RAI Sent Date: 3/18/2016 4:42:32 PM Received Date: 3/18/2016 4:42:33 PM From: Regner, Lisa Created By: Lisa.Regner@nrc.gov Recipients:

"Wayne Harrison" <awharrison@STPEGS.COM>

Tracking Status: None Post Office: HQPWMSMRS01.nrc.gov Files Size Date & Time MESSAGE 893 3/18/2016 4:42:33 PM STP BAP RAI.docx 20689 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

South Texas Project Risk-Informed GSI-191 Resolution RAI Regarding Boric Acid Precipitation Analysis In response to SNPB RAI 10 and SSIB RAI 66 (issued in ML14357A171), STPNOC stated (ML15246A128) that the current risk-over-deterministic (RoverD) analysis relies on the hot leg switchover (HLSO) timing of 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> as stated in STP UFSAR Section 15.6.5.2. As such, the NRC staff believes that changes to the HLSO timing would impact the RoverD analysis and thus the risk-informed resolution to GSI-191. In order to better understand the basis for the current HLSO timing, NRC staff have audited STPNOCs current boric acid precipitation (BAP) control analysis on two occasions, in March 2015 and February 2016.

During the February 2016 audit, NRC staff were presented with testing data supporting STPNOCs contention that the barrel-baffle region mixes with the core under certain conditions.

This region has not been previously credited in a BAP analysis. Given this, the NRC staff is not satisfied that a sufficient level of quantitative support has been provided for inclusion of any portion of the barrel-baffle region in the mixing volume. The NRC staff requests that STPNOC either:

a. Provide additional quantitative justification for the use of the barrel-baffle region in the mixing volume, including discussion of the applicability of test data to the STP plants (e.g., scaling of the tests used and the design of the test facilities relative to the design of STP). Or,

b. Perform a sensitivity analysis of the impact of omitting the barrel-baffle region from the mixing volume, to demonstrate that the current STP HLSO timing of 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> would be supported.

NRR-PMDAPEm Resource From: Regner, Lisa Sent: Friday, March 18, 2016 4:43 PM To: Wayne Harrison

Subject:

DRAFT RAI: STP CLB BAP RAI Attachments: STP BAP RAI.docx

Wayne, In order to continue our review of your risk-informed resolution to GSI-191, the NRC staff needs additional information concerning the HLSO timing currently used in the STP Emergency Operating Procedures as it impacts the thermal-hydraulic analysis with the addition of debris.

Attached is a draft RAI question that, given an acceptable response, should close out the previous questions issued on this topic in 2009 and 2015. If you would like clarifications, we will be available to discuss at the March 31 and/or April 14 public conference calls. Alternately, we can set up a soon clarification call.

Thank you, Lisa Lisa M Regner, Sr. Project Manager, Branch LPLIV-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Lisa.Regner@NRC.Gov Office: O8D08 Mail Stop: O8B01 (301) 415-1906 1

Hearing Identifier: NRR_PMDA Email Number: 2718 Mail Envelope Properties (fcc0c6ab467549e5a862b546d097990b)

Subject:

DRAFT RAI: STP CLB BAP RAI Sent Date: 3/18/2016 4:42:32 PM Received Date: 3/18/2016 4:42:33 PM From: Regner, Lisa Created By: Lisa.Regner@nrc.gov Recipients:

"Wayne Harrison" <awharrison@STPEGS.COM>

Tracking Status: None Post Office: HQPWMSMRS01.nrc.gov Files Size Date & Time MESSAGE 893 3/18/2016 4:42:33 PM STP BAP RAI.docx 20689 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received:

South Texas Project Risk-Informed GSI-191 Resolution RAI Regarding Boric Acid Precipitation Analysis In response to SNPB RAI 10 and SSIB RAI 66 (issued in ML14357A171), STPNOC stated (ML15246A128) that the current risk-over-deterministic (RoverD) analysis relies on the hot leg switchover (HLSO) timing of 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> as stated in STP UFSAR Section 15.6.5.2. As such, the NRC staff believes that changes to the HLSO timing would impact the RoverD analysis and thus the risk-informed resolution to GSI-191. In order to better understand the basis for the current HLSO timing, NRC staff have audited STPNOCs current boric acid precipitation (BAP) control analysis on two occasions, in March 2015 and February 2016.

During the February 2016 audit, NRC staff were presented with testing data supporting STPNOCs contention that the barrel-baffle region mixes with the core under certain conditions.

This region has not been previously credited in a BAP analysis. Given this, the NRC staff is not satisfied that a sufficient level of quantitative support has been provided for inclusion of any portion of the barrel-baffle region in the mixing volume. The NRC staff requests that STPNOC either:

a. Provide additional quantitative justification for the use of the barrel-baffle region in the mixing volume, including discussion of the applicability of test data to the STP plants (e.g., scaling of the tests used and the design of the test facilities relative to the design of STP). Or,

b. Perform a sensitivity analysis of the impact of omitting the barrel-baffle region from the mixing volume, to demonstrate that the current STP HLSO timing of 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> would be supported.