ML083030220

Summary of October 14, 2008, Meeting with Tennessee Valley Authority Regarding Steam Dryer Portion of the Extended Power Uprate Review

ML083030220
Person / Time
Site:	Browns Ferry
Issue date:	12/02/2008
From:	Ellen Brown Plant Licensing Branch II
To:	Tennessee Valley Authority
Brown, E, NRR/DORL, 415-2315
Shared Package
ML083030525	List: ML082890206 ML083030220
References
TAC MD5262, TAC MD5263
Download: ML083030220 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 2, 2008 LICENSEE:

Tennessee Valley Authority FACILITIES: Browns Ferry Nuclear Plant, Units 1 and 2 SUB..IECT:

SUMMARY

OF OCTOBER 14, 2008, MEETING WITH TEI\\JNESSEE VALLEY AUTHORITY REGARDING STEAM DRYER PORTION OF THE EXTENDED POWER UPRATE REVIEW (TAC NOS. MD5262 AND MD5263)

On October 14, 2008, the U.S. Nuclear Regulatory Commission (I\\JRC) staff conducted a Category 1 public meeting with Tennessee Valley Authority (TVA, the licensee) at NRC Headquarters, 6003 Executive Boulevard, Executive Boulevard Building, Rockville, Maryland.

The purpose of the meeting was to discuss recent decisions by TVA regarding the steam dryers, as well as the NRC staff's concerns with the steam dryer analyses provided in support of the extended power uprate (EPU) amendment request for Browns Ferry Nuclear Plant. The enclosure contains a list of attendees. The licensee presented slides that may be accessed from the NRC Agencywide Documents Access and Management System, Accession No. ML082890206).

DISCUSSION In a letter dated October 3, 2008, TVA provided responses to some of the NRC staff's Rounds 20 and 21 Requests for Additional Information. The October 14 meeting was at TVA's request to discuss the licensee's decision to not install the acoustic side branch (ASB) modification. Additionally, the licensee intended to address additional NRC staff concerns regarding the means intended to mitigate the identiIied resonances, justify the application of substructure modeling in the manner proposed, and address the means proposed to address the identified noise.

Previously, the licensee had proposed the installation of an acoustic vibration suppressor and an ASB. The ASB modification was similar in design to that used by Quad Cities to address resonances. TVA indicated that the analyses using the 118 th scale model test (SMT) saw no real benefit to the installation of the ASBs due to physical limitations that prevented "tuning" the ASB to address resonance caused by the main steam safety relief valves. As a result TVA will have to revise the Units 1 and 2 stress reports provided in the summer. The licensee indicated tentative dates for submittal of the revised reports as October 31 for Unit 1 and November 14, 2008, for Unit 2.

Additionally, this decision results in a return to the use of a "bump-up" factor (BUF), as part of the stress analysis. The licensee intends to use the actual plant data, once the noise is subtracted out, and the SMT prediction at EPU conditions to create this frequency based BUF.

This BUF would then be applied to the unit specific strain gage data taken at current licensed thermal power (CLTP) to predict the EPU loading. The NRC staff questioned whether the BUF remained higher than ratio of velocity squared (v 2) at all frequencies. The licensee indicated that there were occasions where the BUF fell below v 2 ratio. The NRC staff commented that

- 2 they expected to have seen that the BUF was ratio of v 2 or higher at all frequencies. The licensee indicated that the BUF was intended to be used at each frequency.

During the discussion, TVA provided a proposal regarding changes in the method proposed for removal of the electrical noise component of the steam line signal. The NRC had indicated various concerns including the removal of the low power strain gage data from CLTP strain gage data across the whole frequency range. The licensee provided several graphs of the data taken from the Units 1 and 2 strain gages. As a result of a recent outage, the licensee has taken additional low power (5 percent) low frequency Unit 2 data to replace the composite 19 and 30 percent data provided previously. As all the strain gages on the Unit 2 main steam line (MSL)

'D' had failed, the licensee proposed substituting the 'A' MSL data for the 'D' MSL data. The NRC staff questioned how the 'A' MSL data intended to be used compared with past 'D' IV1SL data. The licensee indicated that the comparison had not been made.

The NRC staff discussed concerns regarding the large magnitude of the noise swings for the Unit 2 graphs. As discussed previously, it is understood that the Unit 2 data is being influenced by the recirculation pump variable frequency drive (VFD) cable that is routed through another proximate penetration. Also, the results presented for one of the Unit 2 graphs had differences between the upper 'A' MSL signal and lower. There were also differences between the 'A' and

'B' MSL data. TVA indicated that they have not determined why the upper and lower signals differed. The NRC staff expressed concerns that differentiating a signal that should be between 0.00001 and 0.001 pounds per square inch squared per hertz, from a signal with induced noise from the VFD on the magnitude of 0.00001 to greater than 0.1 seems to add additional uncertainty to a methodology with a great deal of uncertainty already introduced.

To more accurately address the local geometry and weld configuration for areas on the dryer the licensee is applying substructure modeling. In a previous meeting and conference call, the NRC staff had multiple questions regarding the establishment of appropriate boundary conditions.

Additionally, the !\\IRC staff questioned the validity of the loading type used and the establishment of the reduction factor based on unit dynamic loading. One question asked in the past by the NRC staff was whether a different analyst could independently come up with the same solution.

The licensee indicated that although the submodel attributes were not unique, the stress reduction factor is unique and accurate, which should allow a different analyst to come up with the same results. The !\\IRC staff indicated that this approach appeared reasonable, but the accuracy of the approach needed to be validated against an existing standard methodology presented in the ANSYS User Manual.

The licensee provided a proposed schedule and license condition that would allow completion of the EPU review for all three units by January 2009 without providing all the information requested on Unit 3. As information needed to support that the acoustic response for Unit 3 is similar to either of the other units, the NRC staff indicated the intent to remain focused on the units for which the requested information had been provided and did not commit to the license condition or the schedule proposed.

- 3 Members of the public were in attendance; however no feedback forms were received. No commitments or regulatory decisions were made by the NRC staff during the meeting.

~A'~Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-259 and 50-260

Enclosure:

List of Attendees cc w/encl: Distribution via Listserv

Nuclear Regulatory Commission Public Meeting with Tennessee Valley Authority Regarding Browns Ferry Power Uprate October 14, 2008 List of Attendees U. S. NUCLEAR REGULATORY COMMISSION ARGONNE NATIONAL LABORATORY David Skeen Vik Shah Kamal Manoly Samir Ziada Tom Boyce Chakrapani Basavaraju Bernie Grenier PENN STATE UNIVERSITY Eva Brown Steve Hambric (by phone)

TENNESSEE VALLEY AUTHORITY STRUCTURAL INTERGRITY ASSOCIATES Robert Marks Sao Bee Kok Kenneth Spates James Emens J.D. Wolcott Denzel Housley CONTINUUM DYNAMICS INCORPORATED Alex Boschitsch Milton Tesche CONSTELLATION ENERGY CORPORATION NUCLEAR MANAG EMENT CORPORATION Gary Pavis Steven Hammer

- 3 Members of the public were in attendance; however no feedback forms were received. No commitments or regulatory decisions were made by the NRC staff during the meeting.

IRA!

Eva A. Brown, Senior Project Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-259 and 50-260

Enclosure:

List of Attendees cc w/encl: Distribution via Listserv DISTRIBUTION:

PUBLIC RidsNrrPMEBrown Resource Lp12-2 R/F RidsAcrsAcnw_MailCenter Resource RidsNrrDorlLpl2-2 Resource RidsOgcRp Resource RidsNrrLABClayton Resource RidsNrrDe Resource Ridsl'JrrDeEmcb Resource RidsNrrPMTOrf Resource RidsRgn2MailCenter CBasavaraju, NRR TScarbrough, NRO DSkeen, NRR BGrenier, NRR CTucci, NRR TFarnholtz, EDO EXTERNAL DISTRIBUTION JWilcox(jdwolcott@tva.qov)

KSpate(krspates@tva.qov)

SZiada(ziadas@mcmaster.ca)

DHousley(dahousley@tva.qov)

VShah(vnshah@anl.gov)

MTesche(milton@continuum-dynamics.com)

SHambric(sah19@only.arl.psu.edu)

RMarks(rfmarks@tva.qov)

SKok(skok@ structint.com)

GPavis(qarv.pavis@constellation.com)

SHammer(hammer.steven@xenuclear.com)ABoschitsch(alexa@continuum-dynamics.com)

Package No: ML083030525 ADAMS Accession No.: ML083030220 TVA Slides No.: ML082890206 NRC-001 OFFICE LPLlI-2/PM LPLlI-2/LA EMCB/BC LPLlI-2 NAME EBrown BClavton KManolv TBovce DATE 12/01/08 12/01/08 10/31/08 12102/08 OFFICIAL RECORD COpy