ML14155A254

NRR E-mail Capture - South Texas Project (STP) Risk-Informed Approach to Resolution of Generic Safety Issue (GSI)-191 - Request for Additional Information (RAI) - TACs MF2400 and MF2401

ML14155A254
Person / Time
Site:	South Texas
Issue date:	06/02/2014
From:	Balwant Singal Division of Operating Reactor Licensing
To:	Harrison A South Texas
References
MF2400, MF2401
Download: ML14155A254 (2)

Text

NRR-PMDAPEm Resource From: Singal, Balwant Sent: Monday, June 02, 2014 4:20 PM To: Harrison, Albon (awharrison@STPEGS.COM)

Cc: Stang, John

Subject:

South Texas Project (STP) Risk-Informed Approach to Resolution of Generic Safety Issue (GSI)-191 - Request for Additional Information (RAI) - TACs MF2400 and MF2401

Wayne, By letter dated December 23, 2013 (Agencywide Documents Access and management System (ADAMS)

Accession No. ML14015A312, STP Nuclear Operating Company (STPNOC) provided response to the U.S.

Nuclear Regulatory Commission (NRC) question STP-GSI-191-EMCB RAI-1. In response to the NRC staff question, STPNOC provided interaction ratios (IRs) for various components of the strainer assembly for two load cases. All of the IRs were below one, indicating all applicable design code requirements were satisfied, by maintaining actual stresses and loads less than the allowable values. However, it is unclear to the NRC staff what differential pressures the analyzed load cases represent and how they relate to the 5.71 feet (ft.) and 9.35 ft. of equivalent head loss discussed in submittal dated November 13, 2013 ((ADAMS Accession No. ML13323A183). In addition, the risk-informed submittal noted that strainer structural failure was a possible failure mode. This appears to indicate that there are loading conditions where the IR values would be greater than 1 and the strainer could fail. However, Section 6.2.2.2.3 of Attachment 2 to Enclosure 3 of submittal dated November 13, 2013 states, The sump structures are designed to withstand the maximum expected differential pressure imposed by the accumulation of debris.

Please identify the differential pressure or equivalent head loss associated with the two load cases provided in letter dated December 23, 2013, in response to the RAI question. Please explain if there are conditions which could load the strainers beyond the maximum differential pressure for which they are qualified. Revise the above statement from Section 6.2.2.2.3, as necessary, based on your response.

Please treat this e-mail as formal transmittal of RAI. You are requested to provide your response within 30 days from the date of this e-mail.

Balwant K. Singal Senior Project Manager (Comanche Peak and STP)

Nuclear Regulatory Commission Division of Operating Reactor Licensing Balwant.Singal@nrc.gov Tel: (301) 415-3016 Fax: (301) 415-1222 1

Hearing Identifier: NRR_PMDA Email Number: 1337 Mail Envelope Properties (Balwant.Singal@nrc.gov20140602162000)

Subject:

South Texas Project (STP) Risk-Informed Approach to Resolution of Generic Safety Issue (GSI)-191 - Request for Additional Information (RAI) - TACs MF2400 and MF2401 Sent Date: 6/2/2014 4:20:26 PM Received Date: 6/2/2014 4:20:00 PM From: Singal, Balwant Created By: Balwant.Singal@nrc.gov Recipients:

"Stang, John" <John.Stang@nrc.gov>

Tracking Status: None "Harrison, Albon (awharrison@STPEGS.COM)" <awharrison@STPEGS.COM>

Tracking Status: None Post Office:

Files Size Date & Time MESSAGE 2155 6/2/2014 4:20:00 PM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

Recipients Received: