ML19282A008

TVA Slides for Pre-Submittal Meeting for License Amendment Request to Correct Unbalanced Voltage Relay Instrumentation Values

ML19282A008
Person / Time
Site:	Watts Bar
Issue date:	10/09/2019
From:	Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation
References
Download: ML19282A008 (11)

Text

Watts Bar Nuclear Plant (WBN)

Pre-Submittal Meeting for Non-Voluntary License Amendment Request (LAR) to Correct Unbalanced Voltage Relay Instrumentation Values October 10, 2019

Agenda

• Opening Remarks

• Background

• Correct Instrument Values

• Proposed Technical Specification (TS) Change

• Corrective Actions

• Schedule Milestones

• Closing Remarks l 2

Opening Remarks

• On 8/27/19, NRC approved a TVA fleet license amendment (ML18277A110) to add a new level of protection regarding "unbalanced voltage" to the Browns Ferry, Sequoyah, and WBN TS for the loss of power instrumentation. This license amendment has a required implementation date of no later than 12/25/19.

• Following issuance of this license amendment, as part of the implementation phase, TVA discovered three incorrect instrument values on WBN Units 1 and 2 TS Table 3.3.5-1, Function 5, associated with the 6.9 kV Emergency Bus Undervoltage (Unbalanced Voltage).

• Implementation of the license amendments for WBN (i.e., Amendments 128/31) with the incorrect values would result in a non-conservative TS.

• TVA is requesting an expedited non-voluntary LAR to revise the incorrect instrument values and to avoid delaying implementation of Amendments 128/31.

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Background

• TVA submitted a fleet LAR to add a new level of protection regarding "unbalanced voltage" on 11/17/2017 (ML17324A349) and a revision to the LAR on 11/19/2018 (ML18324A609)

• NRC approved the LAR on 8/27/19 (ML18277A110) (WBN License Amendments 128/31) with a 120-day implementation date (no later than 12/25/19).

• Following receipt of the license amendments, during the implementation process, TVA determined that the following instrument values in WBN Units 1 and 2 TS Table 3.3.5-1, Function 5, were incorrect:

- Time for the High Trip Setpoint

- Voltage for the Lo Allowable Value

- Time for the High Allowable Value l 4

Correct Instrument Values Value as Function 5 Correct Approved by Parameter Value NRC Trip Setpoint (High) 3.95 second (sec) 3.45 sec Allowable Value (AV) Lo YROWV 9 9 AV High 4.0 sec 3.50 sec

• The correct values are supported by the TVA undervoltage relay (UVR) calculation that was in effect at the time the LAR was submitted.

• The LAR will contain information to demonstrate how the correct values were obtained.

• If the license amendment was implemented as approved by NRC, the trip setpoint (High) would exceed the actual AV (High).

- This would make the channel immediately inoperable l 5

Proposed Technical Specification Change WBN Unit 1 l 6

Proposed Technical Specification Change WBN Unit 2 l 7

Corrective Actions

• TVA has entered this issue into our corrective action program (CAP) .

• Initial investigation appears to be that the incorrect values were due to transcription errors.

• TVA reviewed the other instrument values in the LAR for all three sites and determined they are correct as approved by the NRC.

• Corrective Actions to prevent recurrence will be evaluated as part of the CAP.

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Schedule Milestones

• October 10, 2019 - LAR Pre-Submittal Telecon with NRC

• October 18, 2019 - LAR Submittal with a requested NRC expedited approval date

• December 13, 2019 - NRC Approval of LAR (Requested)

• December 25, 2019 - End date for implementation of the LAR l 9

Closing Remarks

• The proposed expedited LAR will avoid the implementation of a nonconservative TS

• The proposed LAR will allow the WBN proposed TS changes to be implemented concurrent with WBN License Amendments 128/31.

• TVA has performed an extent of condition review and determined that the other instrument setpoint values are correct.

• TVA is requesting an expedited LAR license amendment to revise the incorrect instrument values.

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