ML24319A053

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Restart La Docs - Palisades Reauthorization of Power Operations Environmental Review- Request for Confirmatory Information 2
ML24319A053
Person / Time
Site: Palisades Entergy icon.png
Issue date: 11/14/2024
From:
NRC
To:
NRC/NMSS/DREFS
References
Download: ML24319A053 (17)
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Text

From:

Mary Richmond Sent:

Thursday, November 14, 2024 9:23 AM To:

PalisadesRestart-EnvDocsPUBLICem Resource

Subject:

Palisades Reauthorization of Power Operations Environmental Review-Request for Confirmatory Information 2 Attachments:

HDI PNP 2024-044 Environmental Audit RCI.pdf Mary C Richmond Environmental Project Manager U.S. Nuclear Regulatory Commission Office of Nuclear Materials Safety and Safeguards (NMSS)

Division of Rulemaking, Environmental, and Financial Support (REFS)

Environmental Project Management Branch 3 (EPMB3)

(301) 415-7218; T-4B18 mary.richmond@nrc.gov Please consider the environment before printing this email From: Johann Britting <j.britting@holtec.com>

Sent: Tuesday, November 12, 2024 11:52 AM To: Mary Richmond <Mary.Richmond@nrc.gov>

Cc: Daniel Barnhurst <Daniel.Barnhurst@nrc.gov>; Laura Willingham <laura.willingham@nrc.gov>

Subject:

[External_Sender] RE: Palisades Reauthorization of Power Operations Environmental Review-Request for Confirmatory Information 2

Mary, As requested, please see attached.pdf responses to each request for confirmatory information.

Thank you, Johann Britting Regulatory Assurance Compliance Specialist Holtec Palisades Office:269-764-2356 Cell:248-388-9479 j.britting@holtec.com

From: Mary Richmond <Mary.Richmond@nrc.gov>

Sent: Friday, November 1, 2024 3:03 PM To: Jean Fleming <J.Fleming@holtec.com>; James Miksa <j.miksa@holtec.com>

Cc: Daniel.Barnhurst <Daniel.Barnhurst@nrc.gov>; Laura Willingham (USNRC)

<Laura.Willingham@nrc.gov>; Johann Britting <j.britting@holtec.com>; PalisadesRestart-EnvDocsPUBLICem Resource <PalisadesRestart-EnvDocsPUBLICem.Resource@nrc.gov>

Subject:

Palisades Reauthorization of Power Operations Environmental Review-Request for Confirmatory Information 2 CAUTION: This email came from a source OUTSIDE of Holtec!!

Do not click any links or open any attachments unless you trust the sender and know the contents to be safe.

Clicking links or opening attachments could lead to infecting your computer or Holtecs servers with malicious viruses.

Holtec Decommissioning International, LLC (HDI), submitted a series of licensing and regulatory requests necessary to reauthorize power operations at the Palisades Nuclear Plant (Palisades) through March 24, 2031, the end of the current operating license term under Palisades Renewed Facility Operating License (RFOL) No. DPR-20.

Collectively, these requests define the proposed U.S. Nuclear Regulatory Commission (NRC) Federal actions. In a letter dated, June 18, 2024, the NRC stated it had accepted the last submittal for review (ADAMS Accession No. ML24169A434).

On June 27, 2024, the NRC provided HDI a notice of the upcoming environmental regulatory audit along with the environmental regulatory audit plan and a list of draft Requests for Additional Information (RAI) (ADAMS Accession No. ML24248A056). During the environmental audit, the NRC reviewed documents that were made available on the applicants electronic information portal in response to the NRC draft RAIs. The NRC also participated in site visits and breakout sessions for each resource area with applicant personnel to gather information that will likely be used in the Environmental Assessment (EA). As described in the June 27, 2024, correspondence, this information assisted the NRC staff in identifying either subsequent Requests for Confirmatory Information (RCI),

issued while the audit remained open or, finalizing draft RAIs (ML24248A056) and any newly identified RAIs that might be needed to allow the staff to conduct a complete review and to prepare the EA. As such, a number of the draft RAIs were either (1) closed, primarily due to clarification from the audit or availability of public information, (2) addressed in an RCI (ML24248A261), or (3) became a final RAI (ML24263A171). Responses to the RCIs (ML24260A354) and RAIs (ML24278A027) have been received by the NRC.

Upon review of the response to the RCIs and RAIs, along with stakeholder outreach, the NRC has identified three additional RCIs listed below. The NRC is requesting a response no later than November 11, 2024.

In the interim, please contact me with any questions or comments.

RCI-HCR-7a Provide copies of existing historic and cultural resource procedures (e.g., environmental review, Archaeological, Cultural & Historic Resources procedures, excavation and trenching control procedures,

inadvertent discovery, stop work and notification procedures) for the Palisades site. Enclosure 2, "Environmental New and Significant Review Proposed Resumption of Power Operations Palisades Nuclear Plant," did not provide reference to, or copies of, cultural resource procedures for operations of Palisades. As identified in the 2006 License Renewal EIS Supplement, cultural resources procedures were in place at the site (see Section 4.4.5). These procedures were required by the Michigan State Historic Preservation Office as part of license renewal (see ML061920480). See also, 36 CFR 800.13. Further confirm that:

1. HDI is adopting and revising the former Entergy cultural resource procedures that existed for Palisades;
2. HDI submitted their cultural resource procedures to the Michigan State Historic Preservation Office (SHPO) for review on August 13, 2024;
3. The Michigan SHPO provided recommendations and comments back to HDI on their cultural resource procedures by letter dated October 23, 2024, and;
4. HDI has submitted the Michigan SHPO procedure recommendations into its corrective action process and are currently revising the procedures in accordance with SHPO recommendations. These revisions are expected to be completed and finalized by the end of the calendar year, 2024.

RCI-AE-4a, "Environmental New and Significant Review Proposed Resumption of Power Operations Palisades Nuclear Plant," did not provide a description of any monitoring plans to assess the numbers of fish or other aquatic organisms found on the intake or traveling screens and impacts were provided for license renewal (the license renewal impact determinations assumed a baseline of continued operations). Based on the response to RAI-AE-4, further confirm that:

Based on information in the May 16, 2024 Final Dive Report, which summarized the findings of Spring Cleaning, Intake Crib inspection, and Lake Buoy Installation which Ballard Marine Construction divers performed at Palisades starting April 8th, 2024, the NRC understands the following.

(1) The spring 2024 intake crib inspection and cleaning reported 100% coverage of the bars along the sides of the intake crib by zebra mussels roughly 1.5 thick. Divers also found and cleaned out debris, including zebra mussels, just west of the traveling screens.

(2) The inspection showed that sand, zebra mussels, and other debris had infiltrated the intake system (intake crib, mixing bay, etc.) but there was no visible damage to the mixing bay, trash racks, or traveling screens.

(3) The intake areas would need to be cleaned of sand and debris and some repairs made to the intake crib prior to restart.

(4) Holtec has not found any State-listed species in the intake or discharge systems during annual monitoring.

RCI-GW-2a

Further confirm the following information as provided in the HDIs Updated Hydrogeologic Investigation Report: Palisades Nuclear Power Plant Covert, Michigan, dated September 14, 2023.

  • Field studies conducted at the site report groundwater elevations range from 10 - 45 ft bgs. Groundwater velocity ranges from 816 - 1,274 ft/year in the upper Dune Sand and from 9 - 99 ft per year in the deeper, silty sand unit above the clay.

This area is a known area of previous inadvertent radiological releases. Seven hundred gamma isotopic analyses were performed. Nineteen samples contained detectable Co-60 and Cs-137. This material was disposed of as radioactive waste.

  • Between January 2009 - June 2024, Palisades reported experiencing 10 instances of elevated tritium detected in onsite groundwater (see Table 1 below for details).

Table 1: Summary of Elevated Tritium in Groundwater Events at Palisades Nuclear Power Plant, January 2009 - June 2024 Date Description of Release Corrective Actions and Outcome 2009 - 2013 Fluctuating tritium concentrations in well MW-3 (north of T-90 and T-91 tanks).

Levels reported to be less than the U.S. Environmental Protection Agency (EPA) drinking water maximum contaminant level (MCL) of 20,000 pCi/L Investigations determined the source to be underground piping from the Auxiliary Building Addition 18 temporary wells installed in 2009 to further identify the source of the tritium Investigative and pipe repair/replacement activities February 26, 2015 Elevated tritium concentration in TW-7 Source identified to be the Turbine Building drain tank line Piping replaced Elevated tritium levels reduced by March 11, 2015 March 2015 Elevated tritium concentrations detected in MW-2 and MW-11 Source determined to be associated with the February 2015 leak from the Turbine Building drain tank line Elevated tritium levels reduced by September 2015 (MW-11) and February 2018 (MW-2)

Turbine Building drain system replaced a cautionary measure November 2, 2016 -

December 27, 2016 Elevated tritium concentrations detected at MW-11 Source identified to be originating from the T-91 Utility Water Storage tanks T-91 Utility Water Storage tank and associated piping replaced Tritium concentrations decreased, remaining below EPA MCL 2019 Tritium detected in MW-11 at a concentration of 46,268 pCi/L in November 2019 In 2020, tritium concentrations measured above the EPA MCL at MW-2, MW-3, MW-11, TW-4, TW-6, TW-7, TW-10, TW-14, TW-17 and were No action taken as no new significant dose pathway and release previously reported under a batch release process

elevated (e.g., at or just below EPA MCL) in MW-13 and TW-5 Source determined to be previously discharged effluents that migrated to a storm drain near to MW-11 that normally discharges to the mixing basin October 2019 -

January 2020 Increasing tritium concentrations observed in 7 monitoring wells Station preformed work to line the interior of the M-8 (plant heating boiler) and M-61 (evaporator heating boiler) boiler room sump and associated drain lines September 5, 2020 The T-2 (Condensate Storage Tank) level lowered unexpectedly Failure/leak identified in a buried condensate return pipe to the T-2 Tritium concentrations were measured at 19,588 and 36,869 pCi/L at nearest monitoring well (MW-11) to T-2 on September 9, 2020 and October 8, 2020, respectively Leaking pipe replaced with aboveground and indoor piping Isolated and drained the T-2 tank Tritium concentrations at MW-11 decreased below 700 pCi/L by November 2020.

Additional pipe repair planned as part of restart activities 2021 Tritium detected above EPA MCL in 6 wells at a maximum concentration of 49,197 pCi/L in TW-3 Station performed work to line the interior of the section of buried piping between the M-950 (service building boiler) room and the M-8/M-61 boiler room sump February 2022 Tritium detected above its MCL in two onsite wells, with a maximum detection of 32,254 pCi/L at MW-2 No action described 2023 levels not detected above minimum detectable activity May 2022 Elevated tritium detected in a water sample collected from the 1C switchgear sump within the protected area at a maximum concentration of 645,255 pCi/L Tritium was detected at 10,370 pCi/L in May 2022 at the nearest GPI monitoring location to the 1C switchgear sump (TW-

6)

Source determined to be a leak from a buried pipe, either the T-91 recirculation line or the T-87 to T-91 transfer line Leaking section flushed, drained, and taken out of service Tritium levels in the sump decreased to levels

<15,000 pCi/L A work request was generated to perform repairs to the system before it is put back in service. This involves capping the underground piping, installing aboveground piping, and rerouting radwaste through the aboveground pipes Pipe repair planned as part of restart activities

Mary C Richmond Environmental Project Manager U.S. Nuclear Regulatory Commission Office of Nuclear Materials Safety and Safeguards (NMSS)

Division of Rulemaking, Environmental, and Financial Support (REFS)

Environmental Project Management Branch 3 (EPMB3)

(301) 415-7218; T-4B18 mary.richmond@nrc.gov Please consider the environment before printing this email The information contained herein is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material from Holtec International.

If you are not the intended recipient, you must not keep, use, disclose, copy or distribute this email without the author's prior permission. Further, review, retransmission, dissemination, or other use of this information in whole or part for any other purpose by persons outside the recipient's organization is strictly prohibited unless explicit authorization to such effect has been issued by the sender of this message. Holtec International policies expressly prohibit employees from making defamatory or offensive statements and infringing any copyright or any other legal right by Email communication. Holtec International will not accept any liability in respect of such communications. Holtec International has taken precautions to minimize the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. Holtec International cannot accept liability for any loss or damage caused by software viruses. If you are the intended recipient and you do not wish to receive similar electronic messages from us in the future then please respond to the sender to this effect.

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Subject:

Palisades Reauthorization of Power Operations Environmental Review-Request for Confirmatory Information 2 Sent Date:

11/14/2024 9:23:03 AM Received Date:

11/14/2024 9:23:07 AM From:

Mary Richmond Created By:

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"PalisadesRestart-EnvDocsPUBLICem Resource"

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SJ0PR09MB10696.namprd09.prod.outlook.com Files Size Date & Time MESSAGE 15001 11/14/2024 9:23:07 AM image002.png 19156 image003.png 22857 HDI PNP 2024-044 Environmental Audit RCI.pdf 390981 Options Priority:

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A U.S. Nuclear Regulatory Commission (NRC) request for confirmation of information (RCI) regarding an environmental regulatory audit, was received by Holtec Decommissioning International, LLC (HDI) via electronic mail (email) dated November 1st, 2024.

The environmental regulatory audit was initiated from the series of licensing and regulatory requests HDI docketed to reauthorize power operations at the Palisades Nuclear Plant (PNP) through March 24, 2031, the end of the first license renewal period. Collectively, these requests define the proposed NRC Federal actions. HDIs response to the RCI is provided below.

Acronym list

1. bgs - below ground surface
2. EIS - Environmental Impact Statement
3. EPA - Environmental Protection Agency
4. ft - Feet
5. GPI - Groundwater Protection Initiative
6. HDI - Holtec Decommissioning International
7. MCL - maximum contaminant level
8. MW - monitoring well
9. NRC - Nuclear Regulatory Commission
10. pCi/L - picocuries per Liter
11. PNP - Palisades Nuclear Plant
12. RCI - request for confirmation of information
13. SHPO - State Historic Preservation Office
14. TW - temporary well
15. /yr - per year
16. - Inches NRC REQUEST A. RCI-HCR-7a Provide copies of existing historic and cultural resource procedures (e.g., environmental review, Archaeological, Cultural & Historic Resources procedures, excavation and trenching control procedures, inadvertent discovery, stop work and notification procedures) for the Palisades site. Enclosure 2, "Environmental New and Significant Review Proposed Resumption of Power Operations Palisades Nuclear Plant," did not provide reference to, or copies of, cultural resource procedures for operations of Palisades. As identified in the 2006 License Renewal EIS Supplement, cultural resources procedures were in place at the site (see Section 4.4.5). These procedures were required by the Michigan State Historic Preservation Office as part of license renewal (see ML061920480). See also, 36 CFR 800.13. Further confirm that:
1. HDI is adopting and revising the former Entergy cultural resource procedures that existed for Palisades;
2. HDI submitted their cultural resource procedures to the Michigan State Historic Preservation Office (SHPO) for review on August 13, 2024;
3. The Michigan SHPO provided recommendations and comments back to HDI on their cultural resource procedures by letter dated October 23, 2024, and;
4. HDI has submitted the Michigan SHPO procedure recommendations into its corrective action process and are currently revising the procedures in accordance with SHPO recommendations. These revisions are expected to be completed and finalized by the end of the calendar year, 2024.

HDI Response:

Copies of existing historic and cultural resource procedures (e.g., environmental review, Archaeological, Cultural & Historic Resources procedures, excavation and trenching control procedures, inadvertent discovery, stop work and notification procedures) for the Palisades site were provided to the NRC for review during the Environmental Audit on July 9th 2024 via the HDI-NRC SharePoint website (folder HCR-7). Additional correspondence (via email) with the NRC Environmental Audit project manager on 11/4/2024 confirmed that copies of these procedures are not needed to be provided with this RCI response.

HDI concurs with the information in the request, A. 1. through A. 4., with a minor correction to statement A. 3. summarized below. Corrections are noted in red text (additions) and blue strikethrough text (deletions).

Request A. 3. - The Michigan SHPO provided recommendations and comments back to NRC HDI on Palisades their cultural resource procedures by letter dated October 23, 2024, and; NRC REQUEST B. RCI-AE-4a, "Environmental New and Significant Review Proposed Resumption of Power Operations Palisades Nuclear Plant," did not provide a description of any monitoring plans to assess the numbers of fish or other aquatic organisms found on the intake or traveling screens and impacts were provided for license renewal (the license renewal impact determinations assumed a baseline of continued operations). Based on the response to RAI-AE-4, further confirm that:

Based on information in the May 16, 2024 Final Dive Report, which summarized the findings of Spring Cleaning, Intake Crib inspection, and Lake Buoy Installation which Ballard Marine Construction divers performed at Palisades starting April 8th, 2024, the NRC understands the following.

1. The spring 2024 intake crib inspection and cleaning reported 100% coverage of the bars along the sides of the intake crib by zebra mussels roughly 1.5 thick.

Divers also found and cleaned out debris, including zebra mussels, just west of the traveling screens.

2. The inspection showed that sand, zebra mussels, and other debris had infiltrated the intake system (intake crib, mixing bay, etc.) but there was no visible damage to the mixing bay, trash racks, or traveling screens.
3. The intake areas would need to be cleaned of sand and debris and some repairs made to the intake crib prior to restart.
4. Holtec has not found any State-listed species in the intake or discharge systems during annual monitoring.

HDI Response:

HDI concurs with the information in the request, B. 1. through B. 4., with minor corrections to statement B. 3. and B. 4. summarized below. Corrections are noted in red text (additions) and blue strikethrough text (deletions).

Request B. 3. - The intake areas are planned would need to be cleaned of sand and debris and some repairs are planned to be made to the intake crib prior to restart.

Request B. 4. - Holtec has not identified found any State-listed species in the intake or discharge systems during annual monitoring.

NRC REQUEST C. RCI-GW-2a Further confirm the following information as provided in the HDIs Updated Hydrogeologic Investigation Report: Palisades Nuclear Power Plant Covert, Michigan, dated September 14, 2023.

1. Field studies conducted at the site report groundwater elevations range from 10 -

45 ft bgs. Groundwater velocity ranges from 816 - 1,274 ft/year in the upper Dune Sand and from 9 - 99 ft per year in the deeper, silty sand unit above the clay.

2. Between April and September 2018, the P-8D Auxiliary Feed Water Pump was installed. This area is a known area of previous inadvertent radiological releases.

Seven hundred gamma isotopic analyses were performed. Nineteen samples contained detectable Co-60 and Cs-137. This material was disposed of as radioactive waste.

3. Between January 2009 - June 2024, Palisades reported experiencing 10 instances of elevated tritium detected in onsite groundwater (see Table 1 below for details).

Table 1: Summary of Elevated Tritium in Groundwater Events at Palisades Nuclear Power Plant, January 2009 - June 2024 Date Description of Release Corrective Actions and Outcome 2009 -

2013 Fluctuating tritium concentrations in well MW-3 (north of T-90 and T-91 tanks). Levels reported to be less than the U.S. Environmental Protection Agency (EPA) drinking water maximum contaminant level (MCL) of 20,000 pCi/L 18 temporary wells installed in 2009 to further identify the source of the tritium Investigative and pipe repair/replacement activities

Investigations determined the source to be underground piping from the Auxiliary Building Addition February 26, 2015 Elevated tritium concentration in TW-7 Source identified to be the Turbine Building drain tank line Piping replaced Elevated tritium levels reduced by March 11, 2015 March 2015 Elevated tritium concentrations detected in MW-2 and MW-11 Source determined to be associated with the February 2015 leak from the Turbine Building drain tank line Elevated tritium levels reduced by September 2015 (MW-11) and February 2018 (MW-2)

Turbine Building drain system replaced a cautionary measure November 2, 2016 -

December 27, 2016 Elevated tritium concentrations detected at MW-11 Source identified to be originating from the T-91 Utility Water Storage tanks T-91 Utility Water Storage tank and associated piping replaced Tritium concentrations decreased, remaining below EPA MCL 2019 Tritium detected in MW-11 at a concentration of 46,268 pCi/L in November 2019 In 2020, tritium concentrations measured above the EPA MCL at MW-2, MW-3, MW-11, TW-4, TW-6, TW-7, TW-10, TW-14, TW-17 and were elevated (e.g., at or just below EPA MCL) in MW-13 and TW-5 Source determined to be previously discharged effluents that migrated to a storm drain near to MW-11 that normally discharges to the mixing basin No action taken as no new significant dose pathway and release previously reported under a batch release process October 2019 -

January 2020 Increasing tritium concentrations observed in 7 monitoring wells Station preformed work to line the interior of the M-8 (plant heating boiler) and M-61 (evaporator heating boiler) boiler room sump and associated drain lines September 5, 2020 The T-2 (Condensate Storage Tank) level lowered unexpectedly Failure/leak identified in a buried condensate return pipe to the T-2 Tritium concentrations were measured at 19,588 and 36,869 pCi/L at nearest monitoring well (MW-11) to T-2 on September 9, Leaking pipe replaced with aboveground and indoor piping Isolated and drained the T-2 tank Tritium concentrations at MW-11 decreased below 700 pCi/L by November 2020.

2020 and October 8, 2020, respectively Additional pipe repair planned as part of restart activities 2021 Tritium detected above EPA MCL in 6 wells at a maximum concentration of 49,197 pCi/L in TW-3 Station performed work to line the interior of the section of buried piping between the M-950 (service building boiler) room and the M-8/M-61 boiler room sump February 2022 Tritium detected above its MCL in two onsite wells, with a maximum detection of 32,254 pCi/L at MW-2 No action described 2023 levels not detected above minimum detectable activity May 2022 Elevated tritium detected in a water sample collected from the 1C switchgear sump within the protected area at a maximum concentration of 645,255 pCi/L Tritium was detected at 10,370 pCi/L in May 2022 at the nearest GPI monitoring location to the 1C switchgear sump (TW-6)

Source determined to be a leak from a buried pipe, either the T-91 recirculation line or the T-87 to T-91 transfer line Leaking section flushed, drained, and taken out of service Tritium levels in the sump decreased to levels

<15,000 pCi/L A work request was generated to perform repairs to the system before it is put back in service. This involves capping the underground piping, installing aboveground piping, and rerouting radwaste through the aboveground pipes Pipe repair planned as part of restart activities HDI Response:

HDI concurs with the information in the request, C. 1. through C. 3., with the following minor corrections. Corrections are noted in red text (additions) and blue strikethrough text (deletions).

Request C. 1. - Field studies conducted at the site report groundwater elevations range from 7 - 110 10 - 45 ft bgs. Groundwater velocity ranges from 816 - 1,274 ft/year in the upper Dune Sand and from 9 - 99 ft per year in the deeper, silty sand unit above the clay.

Request C. 2. - Between April and September 2018, the P-8D Auxiliary Feed Water Pump and associated piping was installed. This area is a known area of previous inadvertent radiological releases. Almost seven Seven hundred gamma isotopic analyses were performed. Nineteen samples contained detectable Co-60 and/or Cs-137.

This material was disposed of as radioactive waste.

Request C. 3. - Between January 2009 - June 2024, Palisades reported experiencing 10 instances of elevated tritium detected in onsite groundwater (see Table 1 below for details).

Table 1: Summary of Elevated Tritium in Groundwater Events at Palisades Nuclear Power Plant, January 2009 - June 2024 Date Description of Release Corrective Actions and Outcome 2009 -

2013 Fluctuating tritium concentrations in well MW-3 (north of T-90 and T-91 tanks). Levels reported to be less than the U.S. Environmental Protection Agency (EPA) drinking water maximum contaminant level (MCL) of 20,000 pCi/L from the latest monitoring event in the 2008 Hydrogeologic Report Results indicated Investigations determined the source to be underground piping from the Auxiliary Building Addition however the Auxiliary Building Addition could not have been ruled out by the results alone 18 temporary wells installed in 2009 to further identify the source of the tritium Investigative and pipe repair/replacement activities February 26, 2015 Elevated tritium concentration in TW-7 Source identified to be the Turbine Building drain tank line Piping replaced Elevated tritium levels reduced by March 11, 2015 March 2015 Elevated tritium concentrations detected in MW-2 and MW-11 Source determined to be associated with the February 2015 leak from the Turbine Building drain tank line Elevated tritium levels reduced by September 2015 (MW-11) and February 2016 2018 (MW-

2)

Turbine Building drain system replaced a cautionary measure November 2, 2016 -

December 27, 2016 Elevated tritium concentrations detected at MW-11 Source identified to be originating from the T-91 Utility Water Storage tanks T-91 Utility Water Storage tank and associated piping repaired replaced Tritium concentrations decreased, remaining below EPA MCL

2019 Tritium detected in MW-11 at a concentration of 45,268 46,268 pCi/L in November 2019 In 2020, tritium concentrations measured above the EPA MCL at MW-2, MW-3, MW-11, TW-2, TW-4, TW-6, TW-7, TW-10, TW-14, TW-17 and were elevated (e.g., at or just below EPA MCL) in MW-13 and TW-5 Source determined to be previously discharged effluents that migrated to a storm drain near to MW-11 that normally discharges to the mixing basin No action taken as no new significant dose pathway and release previously reported under a batch release process October 2019 -

January 2020 Increasing tritium concentrations observed in 7 monitoring wells Station preformed work to line the interior of the M-8 (plant heating boiler) and M-61 (evaporator heating boiler) boiler room sump and associated drain lines September 5, 2020 The T-2 (Condensate Storage Tank) level lowered unexpectedly Failure/leak identified in a buried condensate return pipe to the T-2 Tritium concentrations were measured at 19,588 and 36,869 pCi/L at nearest monitoring well (MW-11) to T-2 on September 9, 2020 and October 8, 2020, respectively Leaking pipe replaced with aboveground and indoor piping Isolated and drained the T-2 tank Tritium concentrations at MW-11 decreased below 800 700 pCi/L by November 2020.

Additional pipe repair planned as part of restart activities 2021 Tritium detected above EPA MCL in 6 wells at a maximum concentration of 49,197 pCi/L in TW-3 Station performed work to line the interior of the section of buried piping between the M-950 (service building boiler) room and the M-8/M-61 boiler room sump February 2022 Tritium detected above its MCL in two onsite wells, with a maximum detection of 32,254 pCi/L at MW-2 No action described in the hydrogeologic report.

Trend entered into site corrective action process

(CR-PLP-2022-00256) and site located and isolated leak which occurred between Condensate Receiver Tanks (T-20, T-38, T-927) and Condensate Receiver Tank T-2.

2023 levels not detected above minimum detectable activity May 2022 Elevated tritium detected in a water sample collected from the 1C switchgear sump within the protected area at a maximum concentration of 645,255 pCi/L Tritium was detected at 10,370 pCi/L in May 2022 at the nearest GPI monitoring location to the 1C switchgear sump (TW-6)

Source determined to be a leak from a buried pipe, either the T-91 recirculation line or the T-87 to T-91 transfer line Leaking section flushed, drained, and taken out of service Tritium levels in the sump decreased to levels

<15,000 pCi/L A work request was generated to perform repairs to the system before it is put back in service. This involves capping the underground piping, installing aboveground piping, and rerouting radwaste through the aboveground pipes Pipe repair planned as part of restart activities

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