ML23041A356

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February 15, 2023 Pre-submittal Meeting for Expedited License Amendment Request Main Control Room (MCR) Chiller Completion Time Extension (EPID L-2022-LRM-0098) (Slides)
ML23041A356
Person / Time
Site: Watts Bar  Tennessee Valley Authority icon.png
Issue date: 02/15/2023
From:
Tennessee Valley Authority
To: Kimberly Green
NRC/NRR/DORL/LPL2-2
Green K
References
EPID L-2022-LRM-0098
Download: ML23041A356 (1)
v • d • e


Text

Watts Bar Nuclear Plant February 15, 2023 Watts Bar Nuclear Plant (WBN)

Pre-submittal Meeting for Expedited License Amendment Request Main Control Room (MCR) Chiller Completion Time Extension

Agenda

  • Introduction
  • Background
  • Current Technical Specification (TS) Requirements
  • Reason for the Proposed Change
  • Revised MCR Chiller Replacement Schedule
  • Proposed Technical Specification Changes
  • Changes to MCR Temporary Chilled Water Equipment Description
  • Schedule Milestones
  • Closing Remarks 2

Introduction

  • The purpose of this meeting is to discuss a proposed expedited license amendment request (LAR) for WBN Units 1 and 2.

There are no technical changes or changes to the TS compensatory measures associated with the proposed amendment.

  • The proposed change is due to delays in the vendor delivery of the MCR CREATCS chillers, which were beyond the control of TVA.

l 3

=

Background===

  • 5/19/2020 - TVA submits the LAR to modify the WBN Units 1 and TS for MCR completion time extension (ML20140A342). LAR includes technical information on the MCR CREATCS replacement project including the temporary chilled water system to be utilized during the MCR CREATCS replacement project.

Current TS Requirements Units 1 and 2 - TS 3.7.11 Footnote for Action A.1 l 5

Current TS Requirements Units 1 and 2 - TS 3.7.11 Footnote for Action E.1 l 6

Reason for the Proposed Change

  • Due to unforeseen supplier chain issues, TVA is unable to meet the current TS date range of May 1, 2022, to May 1, 2023, for the MCR chiller replacement as required by the existing footnotes to the Completion Time for WBN Units 1 and 2 TS 3.7.11, Required Actions A.1 and E.1.
  • As shown in Table 1, the new MCR chillers have not yet been received and are not scheduled to commence installation until the third quarter 2023.
  • TVA has received confirmation from the supplier vendor that they can currently meet the delivery dates for the MCR chillers.

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Revised MCR Chiller Replacement Schedule l 8 Table 1 Revised WBN MCR Chiller Replacement Timeline Activity Date U1R18 Outage 4/14/2023-5/13/2023 Qualification of MCR Chillers 4/28/2023 New MCR B Chiller at WBN 5/3/2023 New MCR A Chiller at WBN 5/9/2023 Replace existing MCR B chiller 7/17/2023 - 8/24/2023 U2R5 Outage 11/03/2023 - 12/02/2023 Replace existing MCR A chiller 1/29/2024 - 3/24/2024 U1R19 Outage 11/1/2024-12/13/2024

Proposed TS Changes

  • Revise the current start and end dates in the footnotes to TS 3.7.11, Required Actions A.1 and E.1 to July 1, 2023, to December 31, 2024, respectively (provides a margin for any potential further schedule delays).

Reflects the current MCR replacement schedule (allowing for margin for any potential further schedule delays).

Requires expedited NRC review and approval of the LAR because NRC approval would be required no later than June 15, 2023 (allowing 15 days for implementation).

l 9

Proposed Technical Specification Change PLACE THE TITLE OF THE PRESENTATION HERE l 10 Units 1 and 2 - TS 3.7.11 Footnote for Action A.1

Proposed Technical Specification Change PLACE THE TITLE OF THE PRESENTATION HERE l 11 Units 1 and 2 - TS 3.7.11 Footnote for Action E.1

Changes to MCR Temporary Chilled Water Equipment Description There are no technical changes to the replacement planned MCR CREATCS chillers as described in the previous LAR (ML20140A342) and the NRC safety Evaluation (SE) (ML21078A484).

Differences between the currently planned MCR temporary chiller equipment description and the MCR temporary chiller equipment description in Section 3.1 to the previous LAR and the NRC Regulatory Audit Summary (ML21012A084) are provided in Tables 2 and 3, respectively. There are no changes to the MCR temporary chiller equipment description in the previous TVA RAI response (ML20351A424).

The compensatory measures listed in the previous LAR and the NRC SE remain unchanged.

l 12

l 13 Table 2 Item No.

Description in LAR Currently Planned Installation Reason for Change Significance 1

Page E6 of 24, paragraph 1 describes, The chilled water piping inlet and outlet to the AHUs is removed and replaced with temporary piping for the temporary chiller system.

The inlet and outlet piping will no longer be removed.

Permanent branch connections with isolation valves are being added via permanent modification to the inlet and outlet piping to the AHUs to allow connection of the temporary chiller without removal of piping.

To allow more efficient (less time) transition between the temporary and permanent chillers which will be advantageous during the post modification test (PMT) window and should reduce time in the TS Required Action Completion Time.

This new configuration is functionally equivalent to the configuration described in the LAR and is expected to benefit the project by reducing the time in the TS Required Action Completion Time.

2 Page E6 of 24, Section 3.2 describes major equipment and includes Chilled water Pump.

The temporary chiller installation may have as many as three pumps. Additionally, one major equipment item that was not included in the LAR description is a transfer switch, to allow transfer between plant power and the diesel generator (DG) for the temporary chiller.

The temporary chiller installation includes multiple pumps to meet necessary hydraulic conditions. The temporary chiller installation includes a transfer switch.

These items were included for completeness of information.

l 14 Table 2 Item No.

Description in LAR Currently Planned Installation Reason for Change Significance 3

Page E6 of 24, Section 3.2.1 refers to a 320kW DG. Section 3.2.4 also refers to the 320kW DG.

The DG referred to in the LAR (a rented Aggreko chiller) is rated at 320kW at 50Hz. The rating of this DG is 300kW at 60Hz, which is adequate for the temporary/rented Aggreko chiller equipment. A Caterpillar (CAT) generator and Carrier chiller have also been purchased by the site to reduce reliance on rented equipment. The ratings (tons and kW) of the CAT/Carrier equipment exceed the ratings of the rented Aggreko equipment.

Clarification on the rating of the Aggreko DG and to include reference to the CAT generator which the site has purchased, along with a Carrier chiller.

Both the rented Aggreko equipment and the Carrier/CAT equipment have adequate electrical and cooling capacity to meet the requirements for the temporary chiller system.

4 Page E6 of 24, Section 3.2.1, second paragraph states, Connection to the AHU coils will be made by isolating the chilled water piping, removing the flex hoses between the AHU coils and the chilled water piping and then reconnecting the temporary chilled water supply and return hoses to the AHU coils using existing flange connections.

Permanent branch connections have been added to the AHU piping, Therefore, it is more accurate to state "Connection to the AHU coils is made via permanent flanged branch connections with an isolation valve, which were added as part of the chiller replacement project subsequent to the submittal of the LAR."

To allow more efficient (less time) transition between the temporary and permanent chillers which will be advantageous during the PMT window and should reduce time in the TS Required Action Completion Time.

This new configuration is functionally equivalent to the configuration described in the LAR and is expected to benefit the project by reducing the time in the TS Required Action Completion Time.

l 15 Table 2 Item No.

Description in LAR Currently Planned Installation Reason for Change Significance 5

Page E7 of 24, Section 3.2.2 refers to 2.5 inch() diameter supply and return hoses.

Hose sizes used in the temporary chilled water system are of various sizes (3, 4 and 6)

Final configuration to meet hydraulic requirements.

Larger hose sizes meet hydraulic requirements and offer less resistance compared to smaller hose sizes.

6 Page E7 of 24, Section 3.2.3 states, The equipment associated with the temporary chiller system will be located in the yard west of the Auxiliary Building and in the Control Building (Elevation 729.0 feet).

As noted in the NRC audit summary, "The two potential locations with respect to assumed plant north are (a) due west of the Auxiliary Building or (b) northwest of the Unit 1 Containment."

Provide flexibility in chiller locations.

Both locations are a similar distance (hose run). Both locations are also sufficiently distant from the plant air intakes.

l 16 Table 2 Item No.

Description in LAR Currently Planned Installation Reason for Change Significance 7

Page E7 of 24, Section 3.2.3 states, the temporary chiller system will be protected from freezing.

This statement is intended to mean as required. The design package states that if the chiller is deployed during winter months, steps should be taken to avoid freezing (e.g.,

draining lines when not in use, use of heat tape and insulation).

Clarification.

Clarification.

l 17 Table 3 Item No.

Description in NRC Audit Report Currently Planned Installation Reason for Change Significance 1

Page 4 of 7 of the Audit Report states, Connection to the AHU coils will be made by isolating the chilled water piping, removing the flex hoses between the AHU coils and the chilled water piping and then reconnecting the temporary chilled water supply and return hoses to the AHU coils using existing flange connections.

Permanent branch connections have been added to the AHU piping; therefore, a current statement would be, "Connection to the AHU coils is made via permanent flanged branch connections with an isolation valve, which were added as part of the chiller replacement project subsequent to the submittal of the LAR."

To allow more efficient (less time) transition between the temporary and permanent chillers which will be advantageous during the PMT window and should reduce time in the TS Required Action Completion Time.

This new configuration is functionally equivalent to the configuration described in the LAR and is expected to benefit the project by reducing the time in the TS Required Action Completion Time.

2 Page 5 of 7 of the Audit Report states, The temporary chiller skid DG fuel oil tanks capacity provides a 12-hour run time for the chiller skid without fuel oil replenishment, which allows the licensee time for replenishing measures.

The CAT DG has a 300 gallon tank, which provides a 24-hour run time which is conservative compared to the value cited here.

To reflect the capacity of the CAT DG which would be used with the Carrier chiller.

The run time for the CAT DG is longer than the run time for the Aggreko DG, which is conservative to what is described in the Audit Report.

Schedule Milestones l 18

  • TVA to submit LAR to NRC by February 28, 2023.
  • Request expedited NRC approval by June 15, 2023.
  • 15-day implementation following NRC approval.
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