ML19282A008
| 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
Opening Remarks
Background
Correct Instrument Values Proposed Technical Specification (TS) Change Corrective Actions Schedule Milestones Closing Remarks Agenda 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 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 Function 5 Parameter Value as Approved by NRC Correct Value 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
Proposed Technical Specification Change l 6 WBN Unit 1
Proposed Technical Specification Change l 7 WBN Unit 2
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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