ML14160A781

Part 21 - Defect Identified in Single Loop Operation Minimum Critical Power Ratio

ML14160A781
Person / Time
Site:	Browns Ferry
Issue date:	06/04/2014
From:	Meginnis A B AREVA
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML14160A781 (4)

Text

0610412014 U.S. Nuclear Reru torv Commission Overations Center Event ReDortPpoo IPart 21 (PAR) Event# 50172Rep Org: AREVA INC Notification Date / Time: 06/04/2014 15:22 (EDT)Supplier:

AREVA INC Event Date I Time: 06/04/2014 (PDT)Last Modification:

06/04/2014 Region: 4 Docket #:City: RICHLAND Agreement State: YesCounty: License #:State: WANRC Notified by: ALAN B MEGINNIS Notifications:

DEBORAH SEYMOUR R2DOHQ Ops Officer:

CHARLES TEAL NICK TAYLOR R4DOEmergency Class: NON EMERGENCY PART 21 GROUP EMAIL10 CFR Section:21.21(d)(3)(i)

DEFECTS AND NONCOMPLIANCE PART 21 -DEFECT IDENTIFIED IN SINGLE LOOP OPERATION MINIMUM CRITICAL POWER RATIOThe following is a synopsis of information received via facsimile from AREVA:AREVA identified a defect is in the calculation of the single loop operation (SLO) minimum critical power ratio(MCPR) operating limits for Browns Ferry Units 1, 2, and 3. Specifically, the defect is associated with the usage ofnon-conservative inputs in the SLO pump seizure analyses for the three plants, which results in non-conservative limits for SLO.Individual informing the Commission:

Alan B. Meginnis, AREVA Inc., 2101 Horn Rapids Road, Richland, WA 99354.

-AREVA6/4/2014 3:22:25 PM PAGE1/003 Fax ServerAREVAREVAAREVA Inc.FAXTo: NRC Operations CenterCompany:

U.S. NRCDate: 6/4/2014 Time in: 3:22 PMPages to follow: 2From: Alan B. MeginnisTelephone:

509-375-8266 MB: 36E] Original to be mailed [ Via fax onlyReceiving fax: 301-816-5151 Telephone:

301-816-5100 Extra Distribution to:Sending fax: 434-382-5541 Fax verification:

509-375-8266 Message:Please see attached defect noticeAREVA Inc.2101 Horn Rapids RoadRichland, WA 99354-5102 Telephone:

(509) 375-8100Operator:

Log No.:Ti me Sent:

AREVA 6/4/2014 3:22:25 PM PAGE 2/003 Fax ServerReportable Defect(i) Name and address of the individual or individuals informing the Commission.

Alan B. Meginnis, AREVA Inc., 2101 Horn Rapids Road, Richland, WA99354.(ii) Identification of the facility, the activity, or the basic component supplied for such facility orsuch activity within the United States which fails to comply or contains a defect.The defect is in the calculation of the single loop operation (SLO) minimum critical power ratio(MCPR) operating limits for Browns Ferry Units 1, 2, and 3. Specifically, the defect is associated with the usage of non-conservative inputs in the SLO pump seizure analyses for the threeplants, which resulted in non-conservative limits for SLO.(iii) Identification of the firm constructing the facility or supplying the basic component whichfails to comply or contains a defect.AREVA Inc.(iv) Nature of the defect or failure to comply and the safety hazard which is created or could becreated by such defect or failure to comply.This issue is a defect as defined in 10 CFR 21.3. The calculated MCPR is used to confirm that thecore is operated within the required Operating Limit MCPR (OLMCPR).

The OLMCPR isestablished to ensure that the Technical Specification Safety Limit MCPR (SLMCPR) is notviolated during anticipated operational occurrences (AOOs). The defect in the SLO pump seizureanalyses produced a non-conservative prediction of MCPR. If a SLO pump seizure occurred inany of the three Browns Ferry Units, and that reactor was operating on the specified OLMCPR,the technical specification MCPR safety limit could have been violated.

Therefore, the issue isconsidered a defect.(v) The date on which the information of such defect or failure to comply was obtained.

The issue was first documented in the AREVA Inc. Corrective Action Program on April 15, 2014.Page 1 of 2

-AREVA6/4/2014 3:22:25 PM PAGE3/003 Fax Server(vi) In the case of a basic component which contains a defect or fails to comply, the number andlocation of these components in use at, supplied for, being supplied for, or may be supplied for,manufactured, or being manufactured for one or more facilities or activities subject to theregulations in this part.The defect exists in the calculation of SLO MCPR for the following reactors:

Browns Ferry Unit 1Browns Ferry Unit 2Browns Ferry Unit 3(vii) The corrective action which has been, is being, or will be taken; the name of the individual or organization responsible for the action; and the length of time that has been or will be takento complete the action.As the responsible organization, AREVA Inc. has provided recommended compensatory actionsto all affected plants. The compensatory actions involve restricting the range of core power,core flow, and margin to thermal limits during single loop operation to compensate for the non-conservative prediction of SLO OLMCPR. The operability analyses used as a basis for thecompensatory operating restrictions will be formally reviewed per AREVA's approved qualityassurance process which complies with the criteria set forth in 10 CFR 50 Appendix B. AREVAInc. will provide TVA the formal operating restrictions on core power, core flow, and margin tothermal limits applicable to Browns Ferry Unit 1 Cycle 10, Browns Ferry Unit 2 Cycle 18 andBrowns Ferry Unit 3 Cycle 17. The schedule for completion of the formal documentation is July31, 2014. Analyses and documentation for future operating cycles for the three units which arelicensed by AREVA Inc. will occur on the normal reload schedules for cycle specific milestones.

(viii) Any advice related to the defect or failure to comply about the facility,

activity, or basiccomponent that has been, is being, or will be given to purchasers or licensees.

This defect only had the potential to violate the SLMCPR during SLO. The Browns Ferry plantsnever operated in SLO while they were supported by the supplied limits. Therefore, the plantsnever operated where SLMCPR could have been violated.

Additionally, the current licensing methodology used by AREVA Inc. is believed to be overly conservative in determining thermalmargins specific to the SLO pump seizure event. AREVA Inc. currently has a new high fidelitytransient methodology under review by the USNRC referred to as AURORA-B.

Scoping andpreliminary SLO pump seizure analyses with this new method have demonstrated that thermallimits would not have had the potential to be violated if AURORA-B had been used for thelicensing calculation.

AURORA-B is not yet approved for licensing calculations, but does providesupport that the current method is overly conservative.

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