ML24057A058
| ML24057A058 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 02/27/2024 |
| From: | Kimberly Green Plant Licensing Branch II |
| To: | Tennessee Valley Authority |
| Green K | |
| References | |
| EPID L-2024-LRM-0014 | |
| Download: ML24057A058 (1) | |
Text
February 27, 2024 LICENSEE:
Tennessee Valley Authority FACILITY:
Watts Bar Nuclear Plant, Units 1 and 2
SUBJECT:
SUMMARY
OF FEBRUARY 15, 2024, PUBLIC MEETING WITH TENNESSEE VALLEY AUTHORITY REGARDING PROPOSED LICENSE AMENDMENT REQUEST FOR WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2 (EPID L-2024-LRM-0014)
On February 15, 2024, the U.S. Nuclear Regulatory Commission (NRC) staff held a public meeting with representatives of the Tennessee Valley Authority (TVA). The purpose of the meeting was to discuss a proposed license amendment request (LAR) for Watts Bar Nuclear Plant (Watts Bar), Units 1 and 2. The proposed LAR would modify required actions in Watts Bar, Units 1 and 2, Technical Specification (TS) 3.7.11, Control Room Emergency Air Temperature Control System (CREATCS), to allow up to a 96-hour delayed entry into Limiting Condition for Operation (LCO) 3.0.3 when two trains of CREATCS are inoperable.
The meeting notice and agenda, dated January 30, 2024, are available at Agencywide Documents Access and Management System (ADAMS) Accession No. ML24030A011. TVAs slides for the meeting are available at ADAMS Accession No. ML24044A087. A list of participants is provided as an enclosure to this summary.
TVA stated its intent to submit an LAR to revise TS 3.7.11 to modify the conditions, required actions, and completion times applicable when two CREATCS trains are inoperable. The proposed required actions would require immediate initiation of an action to implement mitigating actions to ensure control room temperature will not exceed 90 degrees Fahrenheit
(°F), and restoration of one train of CREATCS. If one CREATCS train is not restored to operable status within 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> or the control room temperature exceeds 90 °F, when in Mode 1, 2, 3, or 4, the unit must be in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 in 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, and when in Mode 5 or 6, or during movement of recently irradiated fuel assemblies, immediate suspension of movement of recently irradiated fuel assemblies would be required. The proposed changes would also include removal of two temporary footnotes.
TVA previously described the CREATCS in its initial LAR (ML20140A342) that requested one-time changes to actions to support the replacement of the CREATCS chillers. The CREATCS provides temperature control for the main control room (MCR) following isolation of the MCR.
The original LAR, which was approved by the NRC staff on May 5, 2021 (ML21078A484),
among other changes, requested a one-time change to add a footnote related to the Completion Time for Required Action E.1 to allow delayed entry into TS LCO 3.0.3 for up to 4 days (96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />) in the event that both CREATCS trains are inoperable during the planned modifications to the CREATCS chillers. During the planned modifications, a temporary, non-safety related chiller package would be used to supply temporary cooling when both CREATCS are inoperable. TVA stated that it plans to retain the non-safety related chiller for use during planned maintenance of the CREATCS trains. TVA noted that the safety evaluation for the original LAR evaluated the previous temporary chiller set up, including the pressure, deadweight, and seismic loading conditions of the piping system, chiller capacity, power supplies, diesel generator exhaust fumes, and ability to maintain MCR habitability. TVA stated that the non-safety related chiller will be procedurally controlled under a temporary modification.
During the discussion with TVA, the NRC staff asked several questions regarding the current CREATCS chillers and the temporary chiller. The staff asked TVA if it had a timeframe for replacement of the current CREATCS chillers. TVA replied that installation of the MCR chillers is on hold because of operational issues identified on the similarly designed shutdown board room chiller during post installation testing and does not have a firm date.
The NRC staff asked about the current storage location and pre-staging of the temporary chiller and how it is maintained. TVA said that they have secured two temporary chillersone is a rental, and one was purchased. TVA stated that it would pre-stage, but not connect, the temporary chiller prior to any scheduled maintenance on a CREATCS train. This is primarily because the heatup calculation that TVA has performed indicated that it would take approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for the MCR to heat up to 90 °F, and therefore, would need to have some cooling source connected or other mitigating actions in place within the 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to avoid exceeding 90 °F limit that is proposed in Required Action D.2. The NRC staff indicated that the inclusion of information regarding the heatup calculation, and pre-staging and connection of the temporary chiller in the LAR would aid the staff in its review of the proposed LAR. The NRC staff also asked if the permanent branch connections that are mentioned in expedited LAR (ML23058A447) that requested a change to the dates regarding installation of the replacement chillers have been installed. TVA affirmed that the permanent branch connections have been installed. The NRC staff also inquired about what assurance TVA has that the temporary chillers (rental and purchased) will work if needed. TVA stated that the temporary chiller(s) were recently used during the cleaning of shutdown boardroom chiller B.
One of the proposed changes to TS 3.7.11 (revised Condition D) would be for operators to verify that the MCR temperature is at or below 90 °F when two trains of CREATCS are inoperable immediately and once per hour thereafter. The NRC staff inquired about how the temperature is detected and displayed in the MCR. TVA stated that there are auto temperature sensors in the MCR and the temperature display is mounted on walls and is visible to the operators. The NRC staff encouraged TVA to include this information in the LAR. The NRC staff noted that proposed TS Bases for Actions D.1, D.2, and D.3 states that temperature monitoring in multiple locations in the affected areas may be required in order to ensure that the temperature limit is not exceeded. The staff suggested that TVA may want to clarify what is meant by this statement in the proposed LAR.
The NRC staff questioned the need for a 96-hour delay before shutting down the unit and referred to the amendment and the LAR that were cited by TVA as precedence (ML18054B436 and ML23170A015). The amendment issued for Byron and Braidwood Stations and the current LAR for Catawba requested a 24-hour Completion Time for restoring one train of control room chilling to operable status. TVA stated that 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> is reasonable given the mitigating actions and the low probability of an accident that would require operation of the CREATCS.
Additionally, based on experience, 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> provides a reasonable time to diagnose, plan, repair, and test most problems with the CREATCS, while minimizing the time that control room occupants might have to respond to an event while utilizing the mitigating actions. The NRC staff indicated that the basis for the 96-hour Completion Time should be included in the LAR.
The staff asked if the Watts Bar units have entered LCO 3.0.3 due to two trains of CREATCS being inoperable. TVA affirmed that the Watts Bar units have had to enter LCO 3.0.3 on several occasions and that it will include this information in the LAR.
The NRC staff asked about some of the compensatory measures that were previously included by reference in the initial amendments (ML21078A484) and whether they would be included in the proposed TS change. TVA replied that mitigating actions are described in the proposed Bases for Actions D.1, D.2, and D.3, but are not planned to be included in the TS. The NRC staff asked if opening of the MCR doors would impact the control room envelop. TVA stated that the doors associated with the control room envelop are outside of the MCR doors. The staff then asked if there are any events that would require isolation of the MCR. TVA responded that there are certain scenarios that would require isolation of the MCR. The NRC staff suggested that TVA include any changes to compensatory measures previously relied upon in the initial LAR in the proposed LAR.
TVA stated that it plans to submit the LAR by April 15, 2024, and will request approval within one year from the submittal.
No regulatory decisions were made at this meeting.
No comments or public meeting feedback were received.
Please direct any inquiries to me at 301-415-1627, or Kimberly.Green@nrc.gov.
/RA/
Kimberly J. Green, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-390, and 50-391
Enclosure:
List of Attendees cc: Listserv
Enclosure LIST OF PARTICIPANTS FEBRUARY 15, 2024, PUBLIC MEETING TENNESSEE VALLEY AUTHORITY REGARDING PROPOSED LICENSE AMENDMENT REQUEST WATTS BAR NUCLEAR PLANT, UNITS 1 AND 2 Name Organization Kim Green U.S. Nuclear Regulatory Commission (NRC)
Brian Wittick NRC Gordon Curran NRC Rao Karipineni NRC Samir Darbali NRC Shiattin Makor NRC Jay Robinson NRC Josh Wilson NRC DaBin Ki NRC Russell Wells Tennessee Valley Authority (TVA)
Jerry Thompson TVA John Grant TVA Chris Kerlin TVA Shawna Hughes TVA John Johnson TVA Dustin Martin TVA Ryan Nessell TVA Paul Schoepf Enercon Joshua Klabunde Enercon
Meeting Package ML24058A132 Meeting Summary ML24057A058 Meeting Notice ML24030A011 Meeting Slides ML24044A087 OFFICE NRR/DORL/LPL2-2/PM NRR/DORL/LPL2-2/LA NRR/DORL/LPL2-2/BC NRR/DORL/LPL2-2/PM NAME KGreen ABaxter DWrona KGreen DATE 02/26/24 02/27/24 02/27/24 02/27/24