Text

Subsequent License Renewal Application Response to Request for Additional Information and Request for Confirmation of Information - Set 1 Part 2
	ML23352A081
Person / Time
Site:	Monticello
Issue date:	12/18/2023
From:	Hafen S; Northern States Power Company, Minnesota, Xcel Energy
To:	; Office of Nuclear Reactor Regulation, Document Control Desk
References
	L-MT-23-056
	Download: ML23352A081 (1)
	v • d • e

(l Xcel Energy 2807 West County Road 75 Monticello, MN 55362 December 18, 2023 L-MT-23-056 10 CFR 54.17 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Monticello Nuclear Generating Plant Docket No. 50-263 Renewed Facility Operating License No. DPR-22 Subsequent License Renewal Application Response to Request for Additional Information and Request for Con"rmation of Information - Set 1 Part 2

References:

1) Letter from Northern States Power Company, a Minnesota corporation (NSPM), d/b/a Xcel Energy to Document Control Desk, Monticello Nuclear Generating Plant Docket No. 50-263, Renewal License Number DPR-22 Application for Subsequent Renewal Operating License dated January 9, 2023, ML23009A353

2) Email from the NRC to Northern States Power Company, a Minnesota corporation (NSPM), d/b/a Xcel Energy, Monticello, Unit 1, Subsequent License Renewal Application Requests for Confirmation of Information Environmental Review dated October 23, 2023, ML23291A109

3) Letter from Northern States Power Company, a Minnesota corporation (NSPM), d/b/a Xcel Energy to Document Control Desk, Monticello Nuclear Generating Plant, Subsequent License Renewal Application Response to Request for Additional Information and Request for Confirmation of Information - Set 1 dated November 21, 2023, ML23332A182 Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM") is submitting a response to a request for con"rmation of information (RCI) and request for additional information (RAI) to the Subsequent License Renewal Application, listed in Reference 1.

In an e-mail from the NRC to NSPM, listed in Reference 2, the NRC transmitted Environmental RCIs and RAIs. The responses to the RCIs and RAIs in Reference 2 were provided in Reference 3, except for RAI GW-5. This submittal provides the response to the RAI GW-5 in the enclosure to this letter.

Document Control Desk L-MT-23-056 Page 2 Summary of Commitments This letter makes no new commitments and no revisions to existing commitments.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on December f 7/ , 2023.

Site Vice esident, Monticello Nuclear Generating Plant Northern States Power Company - Minnesota cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC Minnesota Department of Commerce

Document Control Desk L-MT-23-056 Page 3 Enclosure Index Enclosure Subject No.

01 RAI GW-5 Groundwater Attachment Index Enclosure Attachment Subject No. No.

01 1 Figure 2 - Well Locations 01 2 Figure 3 - Detail View 01 3 Figure 4 - Sheetpile Wall and Gradient Control System 01 4 Table 1 - Monticello Nuclear Plant Tritium Monitoring 01 5 Table 2 - MW-9a Non-Tritium Isotopes 01 6 Table 3 - MNGP Environmental Well Information 01 7 Table 4 - MNGP 2022 Static Water Level Elevations 01 8 Table 5 - MNGP 2023 Static Water Level Elevation (Feet)

Table 6 - Monthly Summary of Pumping Withdrawal Volume 01 9 (gallons)

Enclosure 01 RAI GW-5 Groundwater

Monticello Nuclear Generating Plant Docket 50-263 L-MT-23-056 1 Page 1 of 6 Topic: Water Resources - Groundwater RAI GW-5:

REQUIREMENT: 10 CFR 51.45(c) and 51.53(c)(2) requires that the ER include a description of the affected environment.

ISSUE: On November 22, 2022, Xcel Energy notified the NRC and State officials that tritium concentrations above the offsite dose calculation manual and Nuclear Energy Initiative Groundwater Protection Initiative reporting levels had been detected in an onsite monitoring well. Section 3.6.4.2.1 of the ER discusses historical inadvertent releases of radionuclides to groundwater, but no discussion or assessment of the November 2022 leak of water containing tritium is provided.

REQUEST: Provide a narrative description of the detection and response to the inadvertent release(s) of tritium into groundwater (first reported in November 2022) through August 18, 2023. This description should include, but not be limited to, the following information:

(a) The source, volume, and activity of tritium and other radionuclides (if applicable) released, including how these values were estimated, (b) Monitoring data that indicated the release(s) had occurred, (c) The response taken to stop the release, including a timeline of events, (d) A description of and response to the second leak, reported on March 23, 2023, (e) A map showing the location of the holding tank that spilled on May 21, 2023, and estimates of the volume spilled and the tritium activity concentration of the holding tank at the time of the spill, (f) Maps showing locations of new monitoring wells and tritium recovery wells installed in response to the release(s),

(g) Maps showing the extent of tritium in groundwater since the occurrence of the release(s), and (h) New permits or permit changes required as a result of the response.

In addition to the narrative description and maps discussed above, include the following information:

(a) A well information table updated to include all the wells currently completed on the site.

Table to include Well ID, Date Installed, Coordinates of Well, Surface Elevation (ft),

Top of Riser ft, Bottom of Well ft, Screened Interval, Depth to Top of Screen ft mean sea level, Depth to Bottom of Screen ft, and Well Purpose.

(b) A table of hydraulic head measurements for all wells measured during 2022 and 2023.

Table to include Well ID, Date of Measurement, Measured Value (feet above mean sea level).

(c) A table of tritium concentrations for all groundwater samples measured during 2022 and 2023. Table to include Well ID, Date of Measurement, Measured Value (pCi/L).

Include data from monitoring wells and pumping (tritium recovery) wells.

Monticello Nuclear Generating Plant Docket 50-263 L-MT-23-056 1 Page 2 of 6 (d) Data that confirm the extent or absence of other radionuclides in groundwater following the November 2022 release.

(e) A table of pumping rate or withdrawal volume as a function of time during 2022 and 2023 for the wells being pumped in response to the tritium release. Table to include Well ID, Date, Pumping Rate or Cumulative Volume Pumped (gpm or gal).

(f) A table of tritium concentrations for all surface water samples measured during 2022 and 2023. Table to include Sample Location, Date of Measurement, Measured Value (pCi/L).

(g) A description of the current plan, subject to change, for remediation/mitigation of the groundwater tritium contamination, including:

- location of the cutoff wall,

- locations of hydraulic control pumping wells,

- estimated pumping rates of the hydraulic control pumping wells,

- disposition of the water pumped for hydraulic control,

- criteria to terminate pumping of tritium recovery wells and hydraulic control wells, and

- estimated time to remediate the tritium contamination.

Response to RAI GW-5:

Request (1a)

The source of the leak was 3-inch condensate to control rod drive (CRD) suction line pipe between the reactor building and the turbine building.

The estimated volume of water lost was 829,000 +/- 68,100 gallons and the estimated activity was 13.9 +/- 1.2 Curie (Ci) of tritium based on a water balance. The total activity from Iodine and Xenon species was 0.08 +/- 0.015 Ci, which when combined with the tritium results in a total activity of 14.0 +/- 1.2 Ci.

Request (1b)

On November 21, 2022, a sample was taken in Monitoring Well #9a (MW-9a), which had a measured tritium value of approximately 5.02E+6 pCi/l. MW-9a is also referred to as MW-9, and is located adjacent to the turbine and reactor building.

On November 22, 2022, a confirmation sample was taken from MW-9a which detected tritium concentrations above the Safe Drinking Water Act (SDWA) limit of 20,000 pCi/l, measured at approximately 5.02E+6 pCi/l as well as short-lived isotopes, and was reported to the NRC and State of Minnesota (Event Notification 56236). The initial tritium value was measured with an onsite instrument and a log of these measurements can be seen in Table 1 - Monticello Nuclear Plant Tritium Monitoring. In addition, other radionuclides were detected in MW-9a, as noted in Table 2 - MW-9a Non-Tritium Isotopes.

Monticello Nuclear Generating Plant Docket 50-263 L-MT-23-056 1 Page 3 of 6 Request (1c)

November 21, 2022: Initial sample of MW-9a was approximately 5.02E+6 pCi/l of tritium.

November 22, 2022: Confirmation sample confirmed MW-9a was approximately 5.02E+6 pCi/l of tritium.

November 22, 2022: Event Notification 56236 was sent to the NRC and State of Minnesota.

November 22, 2022: Site investigation efforts began to identify the source of the leak.

December 21, 2022: Leak location was identified and flow diversion started.

December 29, 2022: Removed additional grout on the turbine building to begin installing the catch basin and monitoring continued for tritium.

March 23, 2023: Sampling indicated that there was a step change and the leakage was being diverted from the catchment, as indicated by increasing levels.

March 24, 2023: Operations began to maneuver the plant to proper mode and equipment line-up to facilitate the permanent repair of the leaking CRD suction pipe.

March 25, 2023: The CRD suction pipe was removed, the piping defect was confirmed.

The original carbon steel piping was replaced with a stainless steel pipe.

Request (1d)

As stated in the answer to Request (1c), there was a step change and the leakage was being diverted from the catchment on March 23, 2023. On March 24, 2023, Operations began to maneuver the plant to proper mode and equipment line-up to facilitate the permanent repair of the leaking CRD suction pipe, and the pipe was replaced on March 25, 2023.

Request (1e)

Event Notification 56535 estimated that between 300-600 gallons overflowed a holding tank.

Figure 1 below shows a side view of the approximate location where this spill occurred on May 21, 2023. The estimated tritium activity concentration in the tank was 1.94E+5 pCi/l of tritium based on a sample from pumping well 12a.

Monticello Nuclear Generating Plant Docket 50-263 L-MT-23-056 1 Page 4 of 6 Figure 1 - Side View of the Approximate Spill Location on May 21, 2023.

Request (1f)

Figure 2 - Well Locations and Figure 3 - Detail View - show the location of the new monitoring wells and tritium recovery wells that have been installed as of August 18, 2023.

Request (1g)

Figure 3 provides a map of the estimated extent of tritium in groundwater as of August 18, 2023.

Request (1h)

As of August 18, 2023, there were three permits that were updated and/or changed because of the response to the ground water response.

1. The Minnesota Pollution Control Agency (MPCA) aboveground storage tanks permit was issued on May 19, 2023.

2. The retention pond National Pollutant Discharge Elimination System (NPDES) approval by the MPCA was issued August 11, 2023. No changes to the NPDES permit required.

3. The Monticello city grading approval for the pond was issued on June 2, 2023.

In addition to the narrative description and maps discussed above, the following information is provided:

Request (2a)

Table 3 - MNGP Environmental Well Information - has data dated August 31, 2023, and was created on October 31, 2023. The table includes the Well ID, Date Installed, Coordinates of Well, Surface Evaluation (ft), Top of Riser (ft), Bottom of Well (ft), Screened Interval, Depth to Top of Screen (ft), Depth to Bottom of Screen (ft), and Well Purpose.

Monticello Nuclear Generating Plant Docket 50-263 L-MT-23-056 1 Page 5 of 6 Request (2b)

Table 4 - MNGP 2022 Static Water Level Elevations - has the hydraulic head measurements for all wells measured during 2022.

Table 5 - MNGP 2023 Static Water Level Elevation (Feet) - has the hydraulic head measurements for all wells measured during 2023.

The tables include the Well ID, Date of Measurement, and Measured Value (feet above mean sea level).

Request (2c)

Table 1 shows the tritium concentrations for all groundwater samples measured during 2022 and 2023. This table includes Well ID, Date of Measurement, Measured Value (pCi/L). Table 1 has data through August 18, 2023.

Request (2d)

Table 2 lists the data that confirms there were indications of other radionuclides in the groundwater following the November 2022 release. Table 2 has data through September 18, 2023.

Request (2e)

Table 6 - Monthly Summary of Pumping Withdrawal Volume (gallons) - provides the monthly summary of pumping withdrawal volume during 2023 for the wells being pumped in response to the tritium release. Table 6 includes the Well ID, Month, and Cumulative Volume Pumped in gallons and provides data through October 2023. Pumping withdrawals did not occur in 2022.

Request (2f)

Table 1 lists the tritium concentration for all surface water samples, upstream and downstream, measured during the 2022 and 2023 event response activities. Table 1 includes Sample Locations, Date of Measurement, Measured Value (pCi/L) and the data is through August 18, 2023.

Request (2g)

As of August 18, 2023, Figure 4 shows the approximate location of the sheetpile containment structure (cutoff wall) and the proposed approximate location for the gradient control wells and discharge piping.

The estimated pumping rates for the gradient control wells are 100-200 gallons per minute. The rates will adjust based on river level and hydraulic conditions at the station (i.e., drought versus flooding). The gradient control wells will be issued a water appropriation permit by Minnesota Department of Natural Resources. The gradient control wells will likely be discharged into the intake as shown in Figure 4.

NSPM remains dedicated to remediation of tritium in the groundwater and working with stakeholders to determine the appropriate steps that represents a successful completion of the

Monticello Nuclear Generating Plant Docket 50-263 L-MT-23-056 1 Page 6 of 6 remediation efforts. As the sheetpile containment structure and gradient control wells have not been finished, it is difficult to predict the time required to achieve the cleanup criteria.

References:

None.

Associated Attachments:

1. Figure 2 - Well Locations

2. Figure 3 - Detail View

3. Figure 4 - Sheetpile Wall and Gradient Control System

4. Table 1 - Monticello Nuclear Plant Tritium Monitoring

5. Table 2 - MW-9a Non-Tritium Isotopes

6. Table 3 - MNGP Environmental Well Information

7. Table 4 - MNGP 2022 Static Water Level Elevations

8. Table 5 - MNGP 2023 Static Water Level Elevation (Feet)

9. Table 6 - Monthly Summary of Pumping Withdrawal Volume (gallons)

Enclosure 01 Attachment 1 Figure 2 - Well Locations

Aerial Photograph Source: Sherburne County (2022)

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- XCEL ENERGY, INC.

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Enclosure 01 Attachment 2 Figure 3 - Detail View

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- Monticello Nuclear Generating Plant Feet Monticello, MN 55362 Monticello, Minnesota (08/18/2023)

Enclosure 01 Attachment 3 Figure 4 - Sheetpile Wall and Gradient Control System

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A XCEL ENERGY, INC. MONTICELLO NUCLEAR GENERATING FIGURE 4 0 140 PLANT WELL LOCATIONS SHEETPILE WALL 2807 West County Road 75 Feet - Monticello, MN 55362 Monticello Nuclear Generating Plant AND GRADIENT Monticello, Minnesota CONTROL SYSTEM

Enclosure 01 Attachment 4 Table 1 - Monticello Nuclear Plant Tritium Monitoring

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 1 of 28 Table 1: Monticello Nuclear Plant Tritium Monitoring Date of Data: 8/18/2023 Monday Tuesday Wednesday Thursday Friday Saturday Sunday Well Sample Frequency Element Activity 11/21/22 11/22/22 11/23/22 11/24/22 11/25/22 11/26/22 11/27/22 MW1 1x/week Tritium (pCi/L)

MW1B 1x/week Tritium (pCi/L)

MW2 Tritium (pCi/L)

MW3 Tritium (pCi/L)

PW4 (old MW4A) 1x/week Tritium (pCi/L)

MW4B Tritium (pCi/L)

MW9A 2x/week Tritium (pCi/L) 5.02E+06 5.02E+06 MW9B 2x/week Tritium (pCi/L) 2.54E+04 MW10A 1x/week Tritium (pCi/L)

MW10B 1x/week Tritium (pCi/L)

MW11 1x/week Tritium (pCi/L)

MW12A 1x/week Tritium (pCi/L) < Detect < Detect < Detect < Detect < Detect < Detect MW12B 1x/week Tritium (pCi/L) < Detect < Detect < Detect < Detect < Detect < Detect MW13A 2x/week Tritium (pCi/L) < Detect < Detect < Detect < Detect < Detect < Detect MW13B 1x/week Tritium (pCi/L) < Detect < Detect < Detect < Detect < Detect < Detect MW14 Tritium (pCi/L)

MW15A 1x/week Tritium (pCi/L) < Detect < Detect < Detect < Detect < Detect < Detect MW15B Tritium (pCi/L) < Detect < Detect < Detect < Detect < Detect < Detect MW16A 1x/week Tritium (pCi/L)

MW16B 1x/week Tritium (pCi/L)

PW16A 1x/week Tritium (pCi/L)

MW17A Tritium (pCi/L)

MW17B Tritium (pCi/L)

MW19A Tritium (pCi/L)

MW19B Tritium (pCi/L)

MW20A 1x/week Tritium (pCi/L)

MW23A 1x/week Tritium (pCi/L)

MW23B 1x/week Tritium (pCi/L)

MW24A 1x/week Tritium (pCi/L)

MW26A 1x/week Tritium (pCi/L)

MW26B Tritium (pCi/L)

MW27A 1x/week Tritium (pCi/L)

MW27B Tritium (pCi/L)

MW28A 1x/week Tritium (pCi/L)

MW28B Tritium (pCi/L)

MW29A 1x/week Tritium (pCi/L)

MW29B Tritium (pCi/L)

MW30A 1x/week Tritium (pCi/L)

MW30B 1x/week Tritium (pCi/L)

PW30 1x/week Tritium (pCi/L)

MW31A 1x/week Tritium (pCi/L)

MW31B 1x/week Tritium (pCi/L)

MW33A 1x/week Tritium (pCi/L)

MW33B Tritium (pCi/L)

MW37A 1x/week Tritium (pCi/L)

MW37B Tritium (pCi/L)

MW48A 1x/week Tritium (pCi/L)

MW48B Tritium (pCi/L)

MW50A 1x/week Tritium (pCi/L)

MW58A 1x/week Tritium (pCi/L)

River, Upstream* 1x/week Tritium (pCi/L)

River, Downstream* 2x per week Tritium (pCi/L)

Disclaimers Regarding Results:

1. All sample results are considered preliminary as the samples are being processed by the MNGP lab.

2. MNGP lab is not certified for the analysis therefore analytical results are considered indicative of actual tritium levels.

3. The minimum detectable level (MDL) typcially fall between 500700 pCi/L for the MNGP lab samples.

4. The offical results will be reported in the annual report for 2023.

5. Began recovering water from MW9A and MW9B on 1/10/2023 at a rate of 0.5 gpm total.

6. Began recovering water from MW12A on 1/17/2023 at a rate of 2 gpm.

7. Began weekly river sampling the week of 4/10/2023.

8. Red boxes cells are sample results processed at Environmental Isotope Laboratory, University of Waterloo. MDL 19 pCi/l. Error range +/ 13 pCi/l.

Sample taken at ODCM Monitoring Point downstream of plant discharge canal.

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 2 of 28 Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Well 11/28/22 11/29/22 11/30/22 12/1/22 12/2/22 12/3/22 12/4/22 12/5/22 12/6/22 12/7/22 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect < Detect < Detect MW4B MW9A 4.78E+06 4.92E+06 4.83E+06 4.82E+06 4.65E+06 4.86E+06 4.71E+06 4.80E+06 4.65E+06 4.70E+06 MW9B MW10A < Detect < Detect MW10B < Detect < Detect MW11 < Detect MW12A < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect MW12B < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect MW13A < Detect < Detect < Detect < Detect < Detect MW13B < Detect < Detect < Detect < Detect < Detect MW14 MW15A < Detect < Detect MW15B < Detect < Detect MW16A MW16B PW16A MW17A MW17B MW19A MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 3 of 28 Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Well 12/8/22 12/9/22 12/10/22 12/11/22 12/12/22 12/13/22 12/14/22 12/15/22 12/16/22 12/17/22 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect < Detect MW4B MW9A 4.55E+06 4.47E+06 4.43E+06 4.28E+06 4.14E+06 4.09E+06 4.30E+06 3.90E+06 3.90E+06 3.81E+06 MW9B 4.40E+06 MW10A < Detect MW10B < Detect MW11 MW12A < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect MW12B < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect MW13A < Detect < Detect < Detect < Detect MW13B < Detect < Detect < Detect < Detect MW14 MW15A < Detect MW15B < Detect MW16A MW16B PW16A MW17A MW17B MW19A MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 4 of 28 Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Well 12/18/22 12/19/22 12/20/22 12/21/22 12/22/22 12/23/22 12/24/22 12/25/22 12/26/22 12/27/22 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect MW4B MW9A 3.69E+06 3.67E+06 3.60E+06 3.62E+06 3.51E+06 3.46E+06 3.46E+06 3.44E+06 3.38E+06 2.97E+06 MW9B 4.81E+06 MW10A < Detect MW10B < Detect MW11 MW12A < Detect < Detect < Detect < Detect < Detect < Detect < Detect < Detect 1.29E+04 3.27E+04 MW12B < Detect < Detect < Detect < Detect < Detect < Detect MW13A < Detect MW13B < Detect MW14 MW15A < Detect MW15B < Detect MW16A MW16B PW16A MW17A MW17B MW19A MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 5 of 28 Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Well 12/28/22 12/29/22 12/30/22 12/31/22 1/1/23 1/2/23 1/3/23 1/4/23 1/5/23 1/6/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect MW4B MW9A 3.33E+06 3.28E+06 3.19E+06 3.10E+06 3.13E+06 3.08E+06 3.00E+06 2.73E+06 3.09E+06 3.08E+06 MW9B MW10A < Detect < Detect MW10B < Detect < Detect MW11 MW12A 6.82E+04 8.33E+04 8.42E+04 7.39E+04 6.73E+04 5.53E+04 4.49E+04 2.37E+04 2.87E+04 2.30E+04 MW12B < Detect < Detect < Detect MW13A < Detect < Detect MW13B < Detect < Detect MW14 MW15A < Detect < Detect MW15B < Detect < Detect MW16A < Detect MW16B < Detect PW16A MW17A < Detect MW17B < Detect MW19A MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 6 of 28 Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Well 1/7/23 1/8/23 1/9/23 1/10/23 1/11/23 1/12/23 1/13/23 1/14/23 1/15/23 1/16/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect MW4B MW9A 3.07E+06 3.05E+06 3.10E+06 3.09E+06 2.95E+06 3.11E+06 3.13E+06 3.11E+06 3.14E+06 3.18E+06 MW9B 4.11E+06 3.92E+06 3.83E+06 3.66E+06 MW10A < Detect MW10B < Detect MW11 MW12A 1.52E+04 1.09E+04 7.51E+03 1.05E+04 5.19E+04 1.82E+05 4.08E+05 5.97E+05 7.59E+05 8.95E+05 MW12B < Detect < Detect MW13A < Detect < Detect MW13B < Detect MW14 MW15A < Detect MW15B MW16A 6.37E+03 6.77E+03 8.71E+03 9.21E+03 MW16B < Detect PW16A MW17A MW17B MW19A MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 7 of 28 Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Well 1/17/23 1/18/23 1/19/23 1/20/23 1/21/23 1/22/23 1/23/23 1/24/23 1/25/23 1/26/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect MW4B MW9A 3.21E+06 3.27E+06 3.31E+06 3.27E+06 3.39E+06 3.49E+06 3.52E+06 3.46E+06 MW9B 3.52E+06 3.39E+06 3.38E+06 3.27E+06 3.34E+06 3.11E+06 3.05E+06 2.95E+06 MW10A < Detect < Detect MW10B < Detect < Detect MW11 MW12A 9.77E+05 1.17E+06 5.89E+05 5.20E+05 7.59E+05 7.03E+05 5.73E+05 5.01E+05 MW12B < Detect < Detect < Detect < Detect MW13A < Detect < Detect < Detect < Detect MW13B < Detect < Detect MW14 MW15A < Detect < Detect < Detect MW15B MW16A 9.89E+03 2.08E+04 3.06E+04 3.44E+04 7.69E+04 8.21E+04 8.34E+04 MW16B < Detect < Detect < Detect PW16A MW17A MW17B MW19A MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 8 of 28 Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Well 1/27/23 1/28/23 1/29/23 1/30/23 1/31/23 2/1/23 2/2/23 2/3/23 2/4/23 2/5/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect MW4B MW9A 3.50E+06 3.54E+06 3.53E+06 3.54E+06 3.51E+06 3.46E+06 MW9B 2.97E+06 2.67E+06 2.61E+06 2.48E+06 2.30E+06 2.14E+06 MW10A < Detect MW10B < Detect MW11 MW12A 5.41E+05 5.73E+05 5.69E+05 5.67E+05 5.51E+05 5.03E+05 MW12B < Detect < Detect MW13A < Detect < Detect MW13B < Detect MW14 MW15A < Detect < Detect MW15B MW16A 1.10E+05 1.42E+05 1.60E+05 1.68E+05 1.69E+05 MW16B < Detect < Detect PW16A MW17A MW17B MW19A < Detect < Detect MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 9 of 28 Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Well 2/6/23 2/7/23 2/8/23 2/9/23 2/10/23 2/11/23 2/12/23 2/13/23 2/14/23 2/15/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect MW4B MW9A 3.46E+06 3.47E+06 3.40E+06 3.47E+06 3.35E+06 3.50E+06 3.54E+06 3.75E+06 MW9B 1.97E+06 1.89E+06 1.66E+06 1.29E+06 1.13E+06 2.97E+06 3.09E+06 3.15E+06 MW10A < Detect MW10B < Detect MW11 MW12A 3.99E+05 1.42E+05 1.14E+05 4.37E+04 1.74E+05 3.31E+05 3.07E+05 MW12B < Detect < Detect MW13A < Detect < Detect MW13B < Detect MW14 MW15A < Detect < Detect MW15B MW16A 2.03E+05 2.35E+05 4.00E+05 3.80E+05 4.06E+05 5.04E+05 5.65E+05 6.26E+05 MW16B < Detect < Detect PW16A MW17A MW17B MW19A < Detect < Detect MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 10 of 28 Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Well 2/16/23 2/17/23 2/18/23 2/19/23 2/20/23 2/21/23 2/22/23 2/23/23 2/24/23 2/25/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect MW4B MW9A 3.76E+06 3.76E+06 3.62E+06 3.10E+06 2.97E+06 MW9B 3.20E+06 3.03E+06 3.09E+06 2.82E+06 MW10A < Detect MW10B < Detect MW11 MW12A 3.08E+05 2.89E+05 MW12B < Detect MW13A < Detect < Detect MW13B < Detect MW14 Weather prevented sampling due to personnel safety MW15A < Detect < Detect concerns.

MW15B MW16A 9.20E+05 1.14E+06 1.62E+06 MW16B < Detect PW16A MW17A MW17B MW19A < Detect < Detect MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 11 of 28 Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Well 2/26/23 2/27/23 2/28/23 3/1/23 3/2/23 3/3/23 3/4/23 3/5/23 3/6/23 3/7/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect MW4B MW9A 2.44E+06 2.43E+06 3.40E+06 3.06E+06 MW9B 1.97E+06 1.69E+06 1.32E+06 9.78E+05 MW10A < Detect < Detect MW10B < Detect < Detect MW11 MW12A 3.05E+04 2.89E+04 5.65E+04 2.75E+04 MW12B < Detect < Detect < Detect MW13A < Detect < Detect 8.25E+02 8.74E+02 MW13B < Detect < Detect MW14 MW15A < Detect < Detect < Detect MW15B MW16A 2.58E+04 3.40E+03 6.26E+02 1.15E+03 1.60E+03 1.43E+03 2.24E+03 MW16B < Detect < Detect < Detect PW16A 5.77E+05 5.62E+05 4.62E+05 5.47E+05 MW17A MW17B MW19A < Detect < Detect < Detect MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 12 of 28 Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Well 3/8/23 3/9/23 3/10/23 3/11/23 3/12/23 3/13/23 3/14/23 3/15/23 3/16/23 3/17/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect MW4B MW9A 2.75E+06 2.74E+06 2.47E+06 MW9B 7.71E+05 6.58E+05 3.83E+05 MW10A < Detect MW10B < Detect MW11 MW12A 1.76E+04 1.85E+04 1.73E+04 1.83E+04 MW12B < Detect MW13A < Detect 9.88E+02 1.14E+03 1.93E+03 1.68E+03 3.54E+03 1.83E+03 1.71E+03 MW13B < Detect MW14 MW15A < Detect < Detect < Detect MW15B MW16A 1.20E+04 3.15E+04 5.90E+04 3.16E+04 2.40E+04 1.62E+04 5.01E+04 1.00E+05 MW16B < Detect PW16A 5.85E+05 5.61E+05 5.56E+05 5.10E+05 4.86E+05 4.83E+05 4.86E+05 4.89E+05 MW17A MW17B MW19A < Detect < Detect MW19B MW20A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 13 of 28 Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Well 3/18/23 3/19/23 3/20/23 3/21/23 3/22/23 3/23/23 3/24/23 3/25/23 3/26/23 3/27/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect MW4B MW9A 2.43E+06 2.45E+06 2.18E+06 2.11E+06 2.08E+06 1.85E+06 1.48E+06 MW9B 2.16E+05 1.47E+05 MW10A < Detect < Detect MW10B < Detect < Detect MW11 MW12A 4.47E+05 4.43E+05 4.50E+05 3.70E+05 MW12B < Detect < Detect MW13A 4.68E+03 3.72E+03 5.48E+03 4.87E+03 6.10E+03 1.97E+04 MW13B < Detect < Detect MW14 MW15A < Detect < Detect < Detect MW15B MW16A 1.39E+05 1.22E+05 1.21E+05 1.08E+05 8.99E+04 5.74E+04 MW16B < Detect < Detect PW16A 4.44E+05 4.29E+05 4.32E+05 4.16E+05 4.03E+05 4.23E+05 MW17A MW17B MW19A < Detect < Detect < Detect MW19B MW20A MW23A < Detect < Detect < Detect MW23B < Detect MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* 2.48E+01 River, Downstream* 5.34E+01

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 14 of 28 Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Well 3/28/23 3/29/23 3/30/23 3/31/23 4/1/23 4/2/23 4/3/23 4/4/23 4/5/23 4/6/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect MW4B MW9A 1.31E+06 1.23E+06 1.13E+06 1.07E+06 8.68E+05 9.88E+05 MW9B 9.47E+04 MW10A < Detect MW10B < Detect MW11 MW12A 1.08E+05 2.51E+04 1.70E+04 MW12B < Detect MW13A 1.11E+04 1.08E+04 1.36E+04 1.64E+04 3.41E+04 3.39E+04 MW13B < Detect MW14 MW15A < Detect < Detect < Detect MW15B MW16A 6.95E+04 5.42E+04 4.67E+04 3.36E+04 9.46E+03 3.49E+03 MW16B < Detect PW16A 4.06E+05 4.12E+05 3.77E+05 4.03E+05 3.87E+05 3.59E+05 MW17A MW17B MW19A < Detect < Detect < Detect MW19B MW20A MW23A < Detect < Detect < Detect MW23B < Detect < Detect MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* 3.74E+01 < Detect River, Downstream* 6.18E+01 2.74E+01

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 15 of 28 Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Well 4/7/23 4/8/23 4/9/23 4/10/23 4/11/23 4/12/23 4/13/23 4/14/23 4/15/23 4/16/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect MW4B MW9A 8.87E+05 7.92E+05 MW9B 5.16E+04 MW10A < Detect MW10B < Detect MW11 MW12A 2.36E+04 2.80E+04 MW12B < Detect MW13A 2.38E+05 1.01E+06 MW13B < Detect MW14 MW15A < Detect < Detect MW15B MW16A 1.10E+03 5.71E+02 MW16B < Detect PW16A 3.30E+05 2.23E+05 MW17A MW17B MW19A < Detect < Detect MW19B MW20A MW23A < Detect < Detect MW23B < Detect MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream*

River, Downstream*

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 16 of 28 Period of Groundwater Flow Reversal Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Well 4/17/23 4/18/23 4/19/23 4/20/23 4/21/23 4/22/23 4/23/23 4/24/23 4/25/23 4/26/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect < Detect MW4B MW9A 1.23E+06 1.38E+06 1.83E+06 1.87E+06 MW9B 3.54E+04 2.46E+04 MW10A 3.95E+04 4.98E+04 6.58E+04 4.88E+04 1.12E+06 MW10B < Detect < Detect MW11 < Detect MW12A 4.41E+04 2.66E+05 3.17E+05 1.37E+05 MW12B 7.61E+02 6.74E+02 1.11E+03 MW13A 8.76E+05 6.22E+05 5.64E+05 4.93E+05 MW13B < Detect < Detect MW14 MW15A < Detect < Detect < Detect < Detect MW15B MW16A 8.88E+04 1.78E+05 1.48E+05 1.51E+05 MW16B < Detect < Detect < Detect PW16A MW17A MW17B MW19A < Detect < Detect < Detect < Detect MW19B MW20A MW23A < Detect < Detect < Detect < Detect MW23B < Detect < Detect MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect < Detect River, Downstream* < Detect < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 17 of 28 Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Well 4/27/23 4/28/23 4/29/23 4/30/23 5/1/23 5/2/23 5/3/23 5/4/23 5/5/23 5/6/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect MW4B MW9A 1.68E+06 1.30E+06 MW9B 1.70E+04 MW10A 1.23E+06 1.32E+06 1.34E+06 MW10B < Detect MW11 MW12A 1.45E+05 1.57E+05 MW12B 6.90E+02 MW13A 4.72E+05 4.32E+05 MW13B < Detect MW14 MW15A < Detect < Detect MW15B MW16A 1.33E+05 5.26E+04 MW16B < Detect PW16A 1.71E+05 1.60E+05 MW17A MW17B MW19A < Detect < Detect MW19B MW20A MW23A < Detect < Detect MW23B < Detect MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect River, Downstream* < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 18 of 28 Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Well 5/7/23 5/8/23 5/9/23 5/10/23 5/11/23 5/12/23 5/13/23 5/14/23 5/15/23 5/16/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect < Detect MW4B MW9A 1.22E+06 1.25E+06 1.02E+06 MW9B 1.62E+05 1.53E+04 MW10A 1.35E+06 1.35E+06 1.30E+06 MW10B < Detect < Detect MW11 < Detect MW12A 2.13E+05 1.84E+05 1.94E+05 MW12B 9.82E+02 < Detect MW13A 4.26E+05 3.94E+05 3.61E+05 MW13B < Detect < Detect MW14 MW15A < Detect < Detect < Detect MW15B MW16A 4.28E+04 3.17E+04 5.99E+03 MW16B < Detect < Detect PW16A 1.73E+05 MW17A MW17B MW19A < Detect < Detect < Detect MW19B MW20A MW23A < Detect < Detect < Detect MW23B < Detect < Detect MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect River, Downstream* < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 19 of 28 Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Well 5/17/23 5/18/23 5/19/23 5/20/23 5/21/23 5/22/23 5/23/23 5/24/23 5/25/23 5/26/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect MW4B MW9A 1.10E+06 1.02E+06 1.06E+06 MW9B 1.19E+04 MW10A 1.22E+06 7.62E+05 MW10B < Detect MW11 < Detect MW12A 7.43E+04 MW12B < Detect MW13A 3.71E+05 6.39E+05 MW13B < Detect MW14 MW15A < Detect < Detect MW15B MW16A 5.34E+03 2.93E+03 MW16B PW16A MW17A MW17B MW19A < Detect MW19B MW20A MW23A < Detect MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect < Detect River, Downstream* < Detect < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 20 of 28 Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Well 5/27/23 5/28/23 5/29/23 5/30/23 5/31/23 6/1/23 6/2/23 6/3/23 6/4/23 6/5/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) < Detect < Detect MW4B MW9A 8.57E+05 7.38E+05 5.77E+05 MW9B 8.47E+03 2.61E+03 MW10A 8.62E+05 1.73E+05 MW10B < Detect MW11 MW12A 5.06E+04 5.34E+04 2.95E+04 MW12B < Detect MW13A 1.94E+06 MW13B < Detect MW14 MW15A < Detect < Detect MW15B MW16A 1.96E+03 8.48E+03 2.22E+05 MW16B < Detect PW16A 2.71E+05 2.78E+05 MW17A MW17B MW19A < Detect <Detect MW19B MW20A MW23A < Detect <Detect MW23B < Detect MW24A MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect River, Downstream* < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 21 of 28 Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Well 6/6/23 6/7/23 6/8/23 6/9/23 6/10/23 6/11/23 6/12/23 6/13/23 6/14/23 MW1 MW1B MW2 MW3 PW4 (old MW4A)

MW4B MW9A 5.86E+05 MW9B MW10A 5.46E+05 MW10B < Detect MW11 MW12A 3.66E+04 MW12B MW13A 1.64E+06 1.39E+06 MW13B < Detect < Detect MW14 MW15A <Detect < Detect MW15B MW16A 7.42E+04 MW16B < Detect PW16A 1.93E+05 MW17A MW17B MW19A < Detect < Detect MW19B MW20A MW23A < Detect < Detect MW23B < Detect MW24A < Detect MW26A MW26B MW27A MW27B MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect < Detect River, Downstream* < Detect < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 22 of 28 Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Well 6/15/23 6/16/23 6/17/23 6/18/23 6/19/23 6/20/23 6/21/23 6/22/23 6/23/23 6/24/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) 1.01E+03 1.03E+03 1.35E+03 1.46E+03 1.26E+03 2.25E+03 3.05E+03 2.37E+03 MW4B < Detect MW9A 3.53E+05 3.02E+05 3.14E+05 MW9B 1.65E+04 1.93E+04 2.27E+04 MW10A 5.59E+05 5.68E+05 5.52E+05 MW10B < Detect MW11 MW12A 1.62E+04 1.12E+04 1.08E+04 MW12B < Detect < Detect MW13A 1.36E+06 1.42E+06 1.32E+06 MW13B < Detect MW14 MW15A < Detect < Detect < Detect < Detect < Detect < Detect MW15B < Detect MW16A 1.20E+05 1.46E+05 1.70E+05 MW16B < Detect PW16A 1.71E+05 MW17A MW17B MW19A < Detect < Detect MW19B MW20A MW23A < Detect < Detect 1.90E+03 1.71E+03 3.11E+03 MW23B < Detect < Detect MW24A < Detect < Detect MW26A < Detect < Detect < Detect < Detect < Detect MW26B < Detect < Detect MW27A < Detect < Detect < Detect < Detect < Detect MW27B < Detect MW28A MW28B MW29A MW29B MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect < Detect River, Downstream* < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 23 of 28 Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Well 6/25/23 6/26/23 6/27/23 6/28/23 6/29/23 6/30/23 7/1/23 7/2/23 7/3/23 7/4/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) 2.96E+03 3.32E+03 3.17E+03 3.36E+03 4.65E+03 4.34E+03 5.04E+03 MW4B MW9A 3.19E+05 6.45E+05 MW9B 2.36E+04 3.80E+03 MW10A 4.86E+05 2.98E+05 MW10B < Detect MW11 MW12A 1.06E+04 1.27E+04 MW12B < Detect MW13A 1.19E+06 9.12E+05 MW13B < Detect MW14 MW15A < Detect < Detect < Detect < Detect < Detect < Detect MW15B < Detect MW16A 8.61E+04 3.33E+04 MW16B < Detect < Detect PW16A 1.40E+05 1.33E+05 MW17A MW17B MW19A < Detect MW19B MW20A MW23A 3.42E+03 2.43E+03 1.17E+04 2.49E+04 3.24E+04 5.05E+04 8.20E+04 MW23B < Detect < Detect MW24A < Detect < Detect MW26A < Detect < Detect < Detect < Detect < Detect MW26B < Detect < Detect MW27A < Detect < Detect < Detect < Detect < Detect MW27B MW28A MW28B MW29A < Detect MW29B < Detect MW30A MW30B PW30 MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect River, Downstream* < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 24 of 28 Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Well 7/5/23 7/6/23 7/7/23 7/8/23 7/9/23 7/10/23 7/11/23 7/12/23 7/13/23 7/14/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) MW4A Overdrilled and converted to PW4A 2.57E+03 2.73E+03 MW4B MW9A 6.36E+05 4.19E+05 2.40E+05 MW9B 5.62E+03 1.38E+04 9.56E+04 MW10A 2.74E+05 2.34E+05 2.10E+05 MW10B MW11 MW12A 8.18E+03 5.93E+03 4.35E+05 MW12B MW13A 8.64E+05 7.85E+05 6.66E+05 MW13B MW14 MW15A < Detect < Detect < Detect MW15B MW16A 1.95E+04 1.79E+04 2.21E+04 MW16B PW16A 1.27E+05 1.04E+05 MW17A MW17B MW19A MW19B MW20A MW23A 1.07E+04 1.14E+05 1.03E+05 MW23B MW24A MW26A < Detect < Detect < Detect MW26B MW27A < Detect < Detect < Detect MW27B MW28A < Detect MW28B MW29A 2.01E+03 2.32E+03 2.32E+03 2.62E+03 MW29B < Detect MW30A 4.53E+04 5.63E+04 MW30B <Detect < Detect PW30 MW31A < Detect < Detect < Detect MW31B < Detect MW33A MW33B MW37A MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect River, Downstream* < Detect < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 25 of 28 Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Monday Well 7/15/23 7/16/23 7/17/23 7/18/23 7/19/23 7/20/23 7/21/23 7/22/23 7/23/23 7/24/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) 8.82E+03 7.32E+03 1.44E+03 MW4B MW9A 2.52E+05 3.15E+05 MW9B 2.97E+04 9.82E+03 MW10A 1.98E+05 1.81E+05 MW10B MW11 MW12A 2.39E+05 2.54E+05 MW12B MW13A 6.27E+05 MW13B MW14 MW15A < Detect < Detect MW15B MW16A 2.80E+04 2.46E+05 MW16B PW16A MW17A MW17B MW19A MW19B MW20A MW23A 8.04E+04 7.31E+04 MW23B MW24A MW26A < Detect 1.42E+03 < Detect MW26B MW27A < Detect < Detect < Detect MW27B MW28A < Detect < Detect < Detect MW28B MW29A 3.12E+03 3.47E+03 MW29B MW30A MW30B PW30 MW31A < Detect < Detect < Detect MW31B MW33A New Well Installed MW33B New Well Installed MW37A New Well Installed MW37B New Well Installed MW48A New Well Installed MW48B New Well Installed MW50A New Well Installed MW58A New Well Installed River, Upstream* < Detect River, Downstream* < Detect < Detect < Detect < Detect < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 26 of 28 Tuesday Wednesday Thursday Friday Saturday Sunday Monday Tuesday Wednesday Thursday Well 7/25/23 7/26/23 7/27/23 7/28/23 7/29/23 7/30/23 7/31/23 8/1/23 8/2/23 8/3/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) 1.08E+03 8.43E+02 MW4B MW9A 3.95E+05 5.26E+05 9.87E+05 MW9B 4.89E+03 2.88E+03 1.64E+03 MW10A 1.64E+05 1.64E+05 1.56E+05 MW10B MW11 MW12A 1.37E+03 1.79E+03 1.55E+03 MW12B MW13A 6.23E+05 5.74E+05 5.42E+05 MW13B MW14 MW15A < Detect < Detect MW15B MW16A 1.99E+04 1.82E+04 1.56E+04 MW16B PW16A 5.84E+04 MW17A MW17B MW19A MW19B MW20A MW23A 7.74E+04 7.71E+04 7.17E+04 MW23B MW24A MW26A < Detect < Detect < Detect MW26B MW27A < Detect < Detect < Detect MW27B MW28A < Detect < Detect < Detect MW28B MW29A 1.04E+04 1.26E+04 1.36E+04 1.73E+04 MW29B MW30A MW30B PW30 5.36E+04 5.08E+04 4.34E+04 MW31A < Detect < Detect < Detect MW31B MW33A 3.02E+03 MW33B < Detect MW37A 3.50E+03 MW37B < Detect MW48A < Detect MW48B < Detect MW50A < Detect MW58A < Detect River, Upstream*

River, Downstream* <Detect <Detect <Detect <Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 27 of 28 Friday Saturday Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sunday Well 8/4/23 8/5/23 8/6/23 8/7/23 8/8/23 8/9/23 8/10/23 8/11/23 8/12/23 8/13/23 MW1 MW1B MW2 MW3 PW4 (old MW4A) 9.66E+02 8.56E+02 7.45E+02 MW4B MW9A 1.33E+06 8.72E+05 MW9B 1.36E+03 2.90E+03 2.41E+03 MW10A 1.41E+05 1.35E+05 1.19E+05 MW10B MW11 MW12A 1.67E+03 1.32E+03 1.38E+03 MW12B MW13A 4.85E+05 3.89E+05 3.39E+05 MW13B MW14 MW15A < Detect < Detect < Detect MW15B MW16A 4.20E+04 2.00E+04 2.94E+04 MW16B PW16A 4.66E+04 6.29E+04 5.75E+04 MW17A MW17B MW19A MW19B MW20A MW23A 5.81E+04 5.67E+04 MW23B MW24A MW26A < Detect < Detect MW26B MW27A < Detect < Detect MW27B MW28A < Detect < Detect MW28B MW29A 2.45E+04 2.81E+04 MW29B MW30A MW30B PW30 3.61E+04 3.37E+04 MW31A < Detect < Detect MW31B MW33A < Detect MW33B MW37A 1.05E+04 MW37B MW48A MW48B MW50A MW58A River, Upstream* < Detect River, Downstream* <Detect < Detect < Detect < Detect < Detect < Detect

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 4, Page 28 of 28 Monday Tuesday Wednesday Thursday Friday Well 8/14/23 8/15/23 8/16/23 8/17/23 8/18/23 MW1 < Detect MW1B < Detect MW2 MW3 PW4 (old MW4A) < Detect MW4B MW9A 4.40E+05 3.90E+05 MW9B 1.19E+04 1.65E+04 MW10A 1.20E+05 MW10B < Detect MW11 < Detect MW12A 1.56E+03 MW12B 2.17E+04 1.87E+04 MW13A 3.19E+05 2.97E+05 MW13B < Detect MW14 MW15A < Detect MW15B MW16A 2.41E+04 MW16B 1.48E+04 1.38E+04 PW16A 6.21E+04 MW17A MW17B MW19A MW19B MW20A < Detect MW23A 5.86E+04 MW23B < Detect MW24A < Detect MW26A < Detect MW26B MW27A < Detect MW27B MW28A < Detect MW28B MW29A 3.73E+04 MW29B MW30A 6.20E+03 MW30B < Detect PW30 2.05E+04 MW31A < Detect MW31B 2.60E+03 MW33A 8.33E+02 MW33B MW37A 1.81E+04 2.10E+04 MW37B MW48A 8.22E+02 MW48B MW50A < Detect MW58A < Detect River, Upstream* < Detect River, Downstream* < Detect < Detect < Detect

Enclosure 01 Attachment 5 Table 2 - MW-9a Non-Tritium Isotopes

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 5, Page 1 of 3 Table 2: MW9a NonTritium Isotopes Sample Date MT 1 Monitoring Well #9 I131 {uci/ml} MT 1 Monitoring Well #9 I133 {uci/ml} MT 1 Monitoring Well #9 I135 {uci/ml} MT 1 Monitoring Well #9 Xe133 {uci/ml} MT 1 Monitoring Well #9 Xe135 {uci/ml}

11/21/2022 1.38E08 3.93E08 0.000000102 3.81E08 11/22/2022 1.51E08 5.03E08 0.000000126 5.89E08 11/28/2022 9.04E09 3.09E08 0.00000014 0.000000112 11/29/2022 1.43E08 4.43E08 0.000000133 0.00000017 11/30/2022 0.000000016 4.89E08 0.00000014 0.000000208 12/1/2022 0.000000015 5.52E08 0.000000172 0.000000247 12/2/2022 2.01E08 6.96E08 0.000000032 0.000000228 0.000000402 12/3/2022 2.16E08 0.00000007 2.72E08 0.000000226 0.000000379 12/4/2022 2.23E08 7.87E08 2.94E08 0.000000225 0.000000404 12/5/2022 2.74E08 8.68E08 3.86E08 0.000000304 0.000000567 12/6/2022 2.31E08 8.65E08 4.08E08 0.00000029 0.000000537 12/7/2022 2.37E08 8.43E08 3.34E08 0.000000217 0.000000402 12/8/2022 2.75E08 9.64E08 3.75E08 0.000000244 0.000000473 12/9/2022 0.000000028 8.83E08 3.92E08 0.000000279 0.000000562 12/10/2022 3.33E08 8.97E08 4.13E08 0.000000301 0.00000058 12/10/2022 2.93E08 8.48E08 2.95E08 0.0000003 0.000000636 12/11/2022 3.37E08 0.000000091 4.02E08 0.000000238 0.000000504 12/12/2022 3.08E08 9.73E08 4.27E08 0.000000332 0.000000718 12/13/2022 4.23E08 0.000000111 5.41E08 0.000000381 0.000000804 12/14/2022 4.34E08 0.000000127 5.61E08 0.00000045 0.000000961 12/15/2022 0.000000045 0.000000126 5.41E08 0.000000434 0.000000979 12/15/2022 3.82E08 0.000000123 4.45E08 0.000000441 0.00000103 12/16/2022 0.000000045 0.000000134 4.37E08 0.000000502 0.00000113 12/16/2022 4.96E08 0.000000133 6.03E08 0.000000528 0.00000118 12/17/2022 4.87E08 0.000000136 4.02E08 0.000000414 0.000000965 12/17/2022 5.11E08 0.000000147 5.36E08 0.000000455 0.00000107 12/18/2022 5.14E08 0.000000143 0.000000053 0.00000046 0.00000104 12/19/2022 5.76E08 0.000000145 6.88E08 0.000000526 0.00000108 12/20/2022 6.16E08 0.000000139 4.89E08 0.0000005 0.00000107 12/21/2022 5.74E08 0.000000118 4.32E08 0.000000546 0.000000994 12/22/2022 0.000000053 0.000000105 3.59E08 0.000000535 0.000000961 12/23/2022 5.25E08 8.39E08 2.72E08 0.000000461 0.000000677 12/24/2022 0.000000054 6.71E08 0.000000027 0.000000413 0.000000621 12/25/2022 0.00000004 4.92E08 0 0.000000424 0.000000432 12/26/2022 4.31E08 4.22E08 0 0.000000398 0.000000313 12/27/2022 3.38E08 2.58E08 0 0.000000312 0.000000226 12/28/2022 3.24E08 2.42E08 0 0.00000023 0.0000002 12/29/2022 3.05E08 1.83E08 0 0.000000277 0.000000178 12/30/2022 2.87E08 1.98E08 0 0.000000263 0.000000129 12/31/2022 2.51E08 1.05E08 0 0.000000215 0.000000058 1/1/2023 2.47E08 0 0 0.000000181 3.65E08 1/2/2023 2.11E08 0 0 0.000000181 3.27E08 1/3/2023 1.84E08 0 0 0.000000154 4.26E08 1/4/2023 1.32E08 0 0 0.000000205 6.35E08 1/5/2023 1.45E08 0 0 0.000000218 6.57E08 1/6/2023 1.27E08 0 0 0.000000205 3.22E08 1/7/2023 9.14E09 0 0 0.000000177 0 1/8/2023 1.41E08 0 0 0.00000015 0 1/9/2023 0.000000012 0 0 0.00000017 0 1/10/2023 1.81E08 0 0 0.000000154 0 1/11/2023 1.56E08 0 0 0.000000108 0 1/12/2023 1.63E08 0 0 8.82E08 0 1/13/2023 1.08E08 0 0 5.23E08 0 Data through 9/18/2023

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 5, Page 2 of 3 Sample Date MT 1 Monitoring Well #9 I131 {uci/ml} MT 1 Monitoring Well #9 I133 {uci/ml} MT 1 Monitoring Well #9 I135 {uci/ml} MT 1 Monitoring Well #9 Xe133 {uci/ml} MT 1 Monitoring Well #9 Xe135 {uci/ml}

1/14/2023 1.18E08 0 0 5.38E08 0 1/15/2023 0.000000014 0 0 0.000000025 0 1/16/2023 1.01E08 0 0 3.16E08 0 1/17/2023 0 0 0 3.29E08 0 1/18/2023 0 0 0 0 0 1/19/2023 8.48E09 0 0 0 0 1/20/2023 0 0 0 0 0 1/23/2023 0 0 0 0 0 1/24/2023 0 0 0 0 0 1/25/2023 0 0 0 0 0 1/26/2023 0 0 0 0 0 1/27/2023 0 0 0 0 0 1/30/2023 0 0 0 0 0 1/31/2023 0 0 0 0 0 2/1/2023 0 0 0 0 0 2/2/2023 0 0 0 0 0 2/3/2023 0 0 0 0 0 2/6/2023 0 0 0 0 0 2/7/2023 0 0 0 0 0 2/8/2023 0 0 0 0 0 2/9/2023 0 0 0 0 0 2/10/2023 0 0 0 0 0 2/13/2023 0 0 0 0 0 2/14/2023 0 0 0 0 0 2/15/2023 0 0 0 0 0 2/16/2023 0 0 0 0 0 2/17/2023 0 0 0 0 0 2/20/2023 0 0 0 0 0 2/22/2023 0 0 0 0 0 2/24/2023 0 0 0 0 0 2/27/2023 0 0 0 0 0 3/1/2023 0 0 0 0 0 3/3/2023 0 0 0 0 0 3/8/2023 0 0 0 0 0 3/10/2023 0 0 0 0 0 3/14/2023 0 0 0 0 0 3/21/2023 0 0 0 0 3.29E09 3/22/2023 0 1.55E08 0 0 3.72E08 3/22/2023 6.93E09 1.37E08 0 0 4.58E08 3/22/2023 0 1.24E08 0 2.17E08 4.24E08 3/23/2023 5.13E09 1.67E08 0 0 5.19E08 3/24/2023 0 1.66E08 0 0.000000037 4.88E08 3/25/2023 5.84E09 1.71E08 0 3.95E08 5.49E08 3/26/2023 0 6.86E09 0 0.000000028 0.000000021 3/27/2023 0 0 0 1.89E08 0

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 5, Page 3 of 3 Sample Date MT 1 Monitoring Well #9 I131 {uci/ml} MT 1 Monitoring Well #9 I133 {uci/ml} MT 1 Monitoring Well #9 I135 {uci/ml} MT 1 Monitoring Well #9 Xe133 {uci/ml} MT 1 Monitoring Well #9 Xe135 {uci/ml}

3/28/2023 0 0 0 0 0 3/29/2023 0 0 0 0 0 3/30/2023 0 0 0 0 0 3/31/2023 0 0 0 0 0 4/3/2023 0 0 0 0 0 4/6/2023 0 0 0 0 0 4/9/2023 0 0 0 0 0 4/12/2023 0 0 0 0 0 4/17/2023 0 0 0 0 0 4/19/2023 0 0 0 0 0 4/23/2023 0 0 0 0 0 4/26/2023 0 0 0 0 0 4/30/2023 0 0 0 0 0 5/3/2023 0 0 0 0 0 5/7/2023 0 0 0 0 0 5/10/2023 0 0 0 0 0 5/14/2023 0 0 0 0 0 5/18/2023 0 0 0 0 0 5/23/2023 0 0 0 0 0 5/24/2023 0 0 0 0 0 5/29/2023 0 0 0 0 0 6/1/2023 0 0 0 0 0 6/5/2023 0 0 0 0 0 6/6/2023 0 0 0 0 0 6/12/2023 0 0 0 0 0 6/15/2023 0 0 0 0 0 6/19/2023 0 0 0 0 0 6/21/2023 0 0 0 0 0 6/25/2023 0 0 0 0 0 7/4/2023 0 0 0 0 0 7/18/2023 0 0 0 0 0 8/22/2023 0 0 0 0 0 9/18/2023 0 0 0 0 0

Enclosure 01 Attachment 6 Table 3 - MNGP Environmental Well Information

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Table 3 MNGP Environmental Well Information Attachment 6, Page 1 of 1 Unique Plant Data, feet UTM Zone 15, meters Surface Top of Riser Bottom of Well Screen Interval Depth to Top of Depth to Bottom of Well ID Date Installed Number Easting Northing Easting Northing Elevation (ft) Elevation (ft) Elevation (ft) Elev - Elev Screen (ft) Screen (ft)

MW1 8/10/1994 547747 4847.19 10248.69 433407.38 5020424.14 930.4 930.19 902.4 902.4 912.4 18 28 MW1B 1/26/2023 870184 4857.61 10247.41 433410.44 5020425.10 930.2 929.96 873.2 973.2 878.2 52 57 PW1** 2/21/2023 870167 5081.98 10055.39 433496.59 5020399.96 927.9 930.41 898.7 898.7 903.7 24 29 MW2 8/10/1994 547748 4843.43 10326.78 433396.55 5020445.36 921.8 923.82 897.5 897.5 907.5 14 24 MW3 8/10/1994 547749 4889.37 10319.18 433410.26 5020449.01 919.9 921.91 901.2 901.2 911.2 9 19 MW4 10/8/2007 747055 5281.42 10320.84 433518.94 5020498.60 925.4 927.86 898.7 898.7 908.7 17 27 PW4A 7/5/2023 872329 5283.08 10327.81 433518.53 5020500.75 925.1 926.45 895.1 895.1910.1 15 30 MW4B 1/24/2023 870185 5289.29 10321.02 433521.10 5020499.64 925.8 928.26 877.8 877.8 882.8 43 48 MW5 9/6/2007 747056 4549.88 9757.05 433386.42 5020250.34 943.0 942.75 901.7 901.7 911.7 31 41 MW6 9/7/2007 747057 5035.29 9563.03 433545.55 5020257.29 930.7 933.24 899.9 899.9 909.9 21 31 MW7 9/5/2007 747058 6205.26 9609.17 433864.70 5020416.73 920.0 922.49 898.1 898.1 908.1 12 22 MW8 9/5/2007 747059 5393.93 8251.55 433809.51 5019938.00 931.5 934.00 900.1 900.1 910.1 21 31 MW9A 9/4/2009 725274 5074.19 10064.31 433493.53 5020401.38 927.9 927.58 901.2 901.2 911.2 17 27 MW9B 11/17/2009 772326 5075.65 10054.35 433495.19 5020398.80 927.9 927.75 883.5 883.5 888.5 39 44 PW9** 2/6/2023 870166 5074.80 10059.10 433494.36 5020400.01 927.9 928.08 892.4 892.4 897.4 31 36 MW10 9/2/2009 725272 4885.05 10045.62 433443.35 5020372.49 935.0 934.69 899.8 899.8 909.8 25 35 PW10A*** 5/30/2023 725272 4885.31 10045.19 433443.47 5020372.40 934.9 936.36* 895.9 895.9910.9 24 39 MW10B 12/29/2022 870161 4887.86 10037.95 433445.13 5020370.70 934.9 934.41 875.9 875.9 880.9 54 59 MW11 9/2/2009 725273 4886.97 9931.96 433458.12 5020341.16 934.9 934.51 899.7 899.7 909.7 25 35 MW12A 10/29/2009 772328 5191.46 10105.31 433520.96 5020427.47 932.4 932.14 898.7 898.7 908.7 24 34 MW12B 11/2/2009 772329 5195.51 10106.27 433521.97 5020428.24 932.4 932.13 884.4 884.4 889.4 43 48 MW13 10/29/2009 772330 5059.49 10210.48 433471.13 5020440.14 934.1 933.82 897.9 897.9 907.9 26 36 PW13A*** 5/31/2023 772330 5059.49 10210.49 433471.13 5020440.14 931.3 932.95* 891.3 891.3906.3 25 40 MW13B 11/1/2009 772331 5062.00 10212.53 433471.57 5020441.02 931.2 933.71 873.4 873.4 878.4 56 61 MW14 9/13/2010 778176 4829.02 10402.98 433383.00 5020464.72 908.7 912.42 902.1 902.1 905.1 4 7 MW15A 6/25/2012 789990 5126.35 10352.88 433471.86 5020488.07 919.0 918.67 903.0 903.0 913.0 6 16 MW15B 6/26/2012 789991 5131.93 10352.93 433473.40 5020488.78 919.1 918.79 869.5 869.5 874.5 45 50 MW16A 12/28/2022 870162 5191.47 10214.97 433507.22 5020457.91 930.6 930.07 899.6 899.6 909.6 21 31 MW16B 12/28/2022 870163 5188.29 10223.72 433505.24 5020459.96 930.7 930.34 877.7 877.7 882.7 48 53 PW16A 2/20/2023 870218 5188.48 10213.12 433506.63 5020457.04 930.5 932.85 892.5 892.5 902.5 28 38 MW17A 12/21/2022 870164 5146.25 9802.99 433546.33 5020337.79 933.6 935.37 900.6 900.6 910.6 23 33 MW17B 12/20/2022 870165 5141.41 9803.31 433544.90 5020337.36 933.5 934.90 858.5 858.5 863.5 70 75 MW19A 1/11/2023 870186 5368.46 10141.08 433565.64 5020459.58 930.5 930.31 900.5 900.5 910.5 20 30 MW19B 1/11/2023 870187 5378.46 10141.03 433568.42 5020460.82 930.5 930.24 880.5 880.5 885.5 45 50 MW20A 1/27/2023 870188 5561.85 10201.21 433611.82 5020500.52 921.7 923.36 897.7 897.7 907.7 14 24 MW21A 1/27/2023 870189 5701.37 9721.49 433710.68 5020384.77 923.6 926.28 897.6 897.6 907.6 16 26 PW22A 1/25/2023 870190 5223.69 10132.39 433526.52 5020439.03 931.6 933.47 892.6 892.6 902.6 29 39 MW23A 3/17/2023 870250 5225.01 10332.11 433501.86 5020494.66 921.6 923.25 898.6 898.6 908.6 13 23 MW23B 3/17/2023 870251 5225.56 10338.94 433501.16 5020496.63 921.3 923.86 876.3 876.3 881.3 40 45 MW24A 6/8/2023 872351 4804.67 10025.59 433423.53 5020356.85 934.8 936.54 901.8 901.8 911.8 23 33 MW26A 6/15/2023 872374 5150.93 10419.40 433470.35 5020509.62 917.5 919.27 899.5 899.5909.5 8 18 MW26B 6/15/2023 872375 5160.96 10420.68 433472.97 5020511.23 917.4 919.56 869.4 869.4874.4 43 48 MW27A 6/15/2023 872372 5253.84 10424.64 433498.27 5020523.97 917.5 919.78 899.5 899.5909.5 8 18 MW27B 6/15/2023 872373 5262.43 10424.86 433500.63 5020525.11 917.6 919.91 871.6 871.6876.6 41 46 MW28A 7/5/2023 872321 5324.84 10423.67 433518.11 5020532.60 918.4 920.51 898.4 898.4908.4 10 20 MW28B 7/5/2023 872322 5332.78 10423.44 433520.34 5020533.53 918.8 920.64 878.8 878.8883.8 35 40 MW29A 6/30/2023 872323 5391.03 10387.72 433541.00 5020530.91 920.6 922.79 898.6 898.6908.6 13 23 MW29B 6/29/2023 872324 5398.64 10384.23 433543.55 5020530.90 920.6 922.73 877.6 877.6882.6 38 43 MW30A 7/6/2023 872325 5465.99 10360.20 433565.27 5020532.66 920.0 921.33 899.0 899.0909.0 11 21 MW30B 7/6/2023 872326 5473.21 10357.95 433567.55 5020532.94 919.9 921.78 880.9 880.9885.9 34 39 PW30A 7/18/2023 872301 5471.21 10365.18 433566.09 5020534.70 919.0 920.87 888.0 888.0903.0 16 31 MW31A 7/6/2023 872328 5320.18 10236.12 433540.32 5020479.93 929.0 930.86 894.0 894.0909.0 20 35 MW31B 7/6/2023 872327 5328.12 10236.47 433542.48 5020481.02 928.8 930.63 878.8 878.8883.8 45 50 MW33A 7/19/2023 872414 5456.44 10424.99 433554.49 5020549.46 919.0 920.87 897.0 897.0907.0 12 22 MW33B 7/18/2023 872415 5464.23 10422.71 433556.94 5020549.80 919.1 920.39 879.1 879.1884.1 35 40 MW37A 7/21/2023 872416 5562.59 10450.69 433580.75 5020569.90 913.0 914.96 896.0 896.0906.0 7 17 MW37B 7/21/2023 872417 5571.69 10450.91 433583.26 5020571.10 913.9 916.20 875.9 875.9880.9 33 38 MW48A 7/26/2023 872437 5711.40 10444.22 433622.90 5020586.75 919.6 921.62 897.6 897.6907.6 12 22 MW48B 7/26/2023 872438 5703.61 10444.65 433620.68 5020585.90 920.8 922.59 868.8 868.8873.8 47 52 MW50A 7/24/2023 872439 5700.59 10313.03 433636.33 5020548.96 919.4 921.70 897.4 897.4907.4 12 22 MW58A 7/25/2023 872440 5836.28 10432.11 433659.10 5020599.04 920.1 922.87 899.1 899.1909.1 11 21 MW101A 7/27/2023 872427 6222.89 7498.06 434134.17 5019832.62 928.2 929.85 901.2 901.2911.2 17 27 MW102A 7/28/2023 872428 6713.15 7546.16 434264.30 5019907.42 926.4 928.59 989.4 989.4999.4 18 28 MW103A 7/28/2023 872429 6606.53 7219.23 434275.66 5019803.26 935.2 937.55 903.3 903.3913.3 22 32 GC1 8/30/2023 872477 5897.97 9657.87 433773.26 5020391.74 923.4 925.83 881.4 881.4901.4 22 42 GC2 8/28/2023 872478 5463.82 9505.47 433671.78 5020295.01 930.7 932.71 881.7 881.7901.7 29 49 GC3 8/28/2023 872479 5198.76 9425.67 433608.16 5020239.63 931.2 933.50 881.2 881.2901.2 30 50 GC4 8/24/2023 872480 4878.27 9391.58 433523.43 5020189.99 932.4 934.51 877.4 877.4897.4 35 55 GC5 8/23/2023 872481 4523.98 9841.89 433368.60 5020270.66 942.1 944.54 892.1 892.1912.1 30 50 Notes:

Measuring point is top of well cover with pump installed.

- Location data for PW1 and PW9 is approximate, these wells are located inside the former Site Administration Building.

- - Monitoring wells MW10 and MW13 were overdrilled and replaced with recovery wells PW10A and PW13A, respectively.

MW = stands for Monitoring Well PW = stands for Pumping Well GC = stands for Gradient Control Carlson McCain, Inc. Table Updated 11/16/2023

Enclosure 01 Attachment 7 Table 4 - MNGP 2022 Static Water Level Elevations

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Table 4 MNGP 2022 Static Water Level Elevations Docket 50-263 Attachment 7, Page 1 of 1 Date MW1 MW2 MW3 MW4 MW5 MW6 MW7 MW8 MW9A MW9B MW10 MW11 MW12A MW12B MW13A MW13B MW14 MW15A MW15B River 1/18/2022 906.74 906.65 906.74 906.13 907.25 906.76 905.68 907.21 906.63 906.59 906.63 906.80 906.40 906.42 906.44 906.46 905.02 906.04 906.16 905.90 2/21/2022 906.76 906.77 906.76 906.14 907.25 906.70 905.65 907.14 906.56 906.47 906.59 906.41 906.34 906.36 906.36 906.46 906.01 906.05 906.16 906.23 3/21/2022 906.99 907.14 906.98 906.47 907.33 906.85 905.89 910.45 906.67 906.72 906.80 906.85 906.49 906.55 906.53 906.67 905.81 906.37 906.56 906.74 4/20/2022 909.51 909.82 909.78 909.61 908.06 908.93 908.64 909.04 909.14 909.20 909.12 908.73 909.34 909.41 909.47 909.46 908.76 909.47 909.44 909.68 5/23/2022 911.68 911.92 911.99 911.60 909.61 911.63 910.83 911.74 911.52 911.52 911.39 910.98 911.59 911.60 911.67 911.60 910.76 911.47 911.46 911.49 6/21/2022 909.89 909.52 909.71 908.60 910.67 910.80 908.54 911.45 910.03 909.91 910.05 910.45 909.54 909.43 909.45 909.36 907.26 908.47 908.69 908.27 7/19/2022 909.12 908.66 908.93 907.70 910.75 909.86 907.68 910.69 909.21 909.09 909.35 909.85 908.65 908.53 908.62 908.52 906.25 907.56 907.84 907.15 8/22/2022 907.97 907.66 907.83 906.81 909.85 908.62 906.65 909.58 907.93 907.93 908.19 906.69 906.76 907.43 907.42 907.45 905.35 906.57 906.81 906.27 9/20/2022 907.31 906.85 907.07 905.89 909.44 908.14 906.01 908.96 907.38 907.30 907.63 908.19 906.84 906.72 906.77 906.73 904.58 905.71 906.03 905.16 10/19/2022 906.88 906.51 906.67 905.63 908.91 907.47 905.65 908.32 906.90 906.84 907.08 907.59 906.39 906.33 906.36 906.40 904.27 905.47 905.77 905.07 11/22/2022 907.20 906.97 907.10 906.19 908.45 907.63 906.04 908.26 907.41 907.20 907.37 907.66 906.81 906.77 906.81 906.82 904.98 906.00 906.24 905.80 12/19/2022 906.78 906.44 906.62 905.61 908.25 907.24 905.60 907.93 907.06 906.82 907.01 907.32 906.36 906.30 906.32 906.31 904.36 905.46 905.69 905.05 Notes:

All elevations given in feet, NGVD Carlson McCain, Inc. Table Updated 11/16/2023

Enclosure 01 Attachment 8 Table 5 - MNGP 2023 Static Water Level Elevation (Feet)

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 8, Page 1 of 5 Table 5 - MNGP 2023 Static Water Level Elevation (Feet)

MW1A MW1B MW2 MW3 MW4A MW4B PW4A MW5 MW6 MW7 MW8 MW9A MW9B MW10A PW10A 2/6/2023 906.84 906.56 906.77 906.80 906.01 906.11 907.98 906.98 905.63 907.60 906.66 906.65 906.87 2/13/2023 906.76 906.46 906.67 906.72 905.93 906.03 907.90 906.93 905.55 907.56 905.97 906.23 906.78 2/20/2023 906.91 906.86 906.90 906.05 906.17 907.87 907.05 905.68 907.69 906.54 906.40 906.95 2/27/2023 906.81 906.52 906.73 906.79 906.02 906.13 907.82 906.99 905.68 907.61 906.00 906.30 906.82 3/6/2023 906.75 906.37 906.73 906.74 905.90 905.99 907.77 906.92 905.60 907.56 905.49 905.95 906.77 3/14/2023 906.74 906.44 906.74 906.71 905.89 906.01 907.74 906.93 905.65 907.53 905.67 906.06 906.77 3/20/2023 906.70 906.30 906.61 906.67 905.88 905.99 907.69 906.91 905.62 907.52 905.92 906.20 906.78 3/26/2023 906.76 906.45 906.68 906.72 906.03 906.11 907.66 906.95 905.68 907.56 905.76 906.12 906.67 4/2/2023 906.21 906.51 906.65 906.84 4/3/2023 906.90 906.58 906.83 906.92 906.18 906.26 907.62 907.15 905.94 907.78 906.51 906.61 906.84 4/10/2023 907.22 906.98 907.33 907.31 906.72 906.74 907.71 907.45 906.35 908.13 906.09 906.57 907.10 4/17/2023 910.82 911.07 912.24 911.93 912.89 912.24 908.01 908.94 910.95 909.50 908.56 909.41 909.61 4/24/2023 912.14 912.09 912.91 912.85 913.06 912.88 908.64 911.19 911.62 911.35 910.98 911.28 911.42 4/26/2023 912.17 912.05 912.76 913.77 912.76 912.64 908.97 911.58 911.62 911.69 910.92 911.37 5/1/2023 912.08 911.85 912.38 912.42 912.11 912.09 909.56 912.00 911.28 912.17 911.04 911.43 5/8/2023 911.57 911.26 911.61 911.68 910.98 911.09 910.18 911.93 910.45 911.39 910.72 911.04 5/15/2023 911.31 910.99 911.25 911.32 910.60 910.70 910.80 911.74 910.24 912.37 910.55 910.78 5/22/2023 910.81 910.41 910.53 910.70 909.65 909.85 910.85 911.57 909.59 912.33 910.23 910.44 5/30/2023 909.98 909.46 909.45 909.80 908.25 908.55 910.38 911.15 908.60 912.09 909.40 909.65 910.14 6/5/2023 909.20 908.64 908.53 908.93 907.23 907.58 911.42 910.68 907.76 911.73 908.79 909.00 909.61 6/12/2023 908.60 908.03 907.94 908.30 906.62 906.88 911.35 910.11 907.22 911.33 908.18 908.35 898.40 6/19/2023 908.03 907.48 907.34 907.65 905.92 906.21 911.15 909.60 906.66 910.92 907.76 907.84 899.07 6/26/2023 907.70 907.19 907.09 907.30 905.31 905.95 910.96 909.16 906.43 910.52 907.72 907.65 898.58 7/5/2023 907.45 906.96 906.85 907.10 905.18 905.78 910.68 908.75 906.23 910.19 907.53 907.41 902.09 7/10/2023 907.23 906.75 906.61 906.89 905.15 905.53 904.93 910.59 908.55 906.00 909.87 907.09 906.97 902.55 7/19/2023 906.94 906.48 906.36 906.57 904.90 905.21 904.90 910.35 908.16 905.69 909.48 906.98 906.86 902.52 7/24/2023 906.75 906.28 906.18 906.41 904.76 905.16 904.76 910.16 908.00 906.07 909.29 906.67 906.64 902.76 7/31/2023 906.79 906.12 906.04 906.30 904.62 904.94 904.63 909.97 907.86 905.46 909.09 906.59 906.54 902.97 8/7/2023 906.50 906.05 905.91 906.18 904.58 904.91 899.59 909.77 907.65 905.30 908.85 906.41 906.30 902.09 8/14/2023 906.52 906.09 906.10 906.32 904.84 905.14 904.84 909.54 907.64 905.42 909.00 905.98 906.12 902.92 8/21/2023 906.44 906.00 905.97 906.18 904.69 905.00 904.97 909.48 907.77 905.32 908.83 906.06 906.16 899.89 8/28/2023 906.26 905.79 905.74 905.96 904.48 904.78 904.51 909.32 907.48 905.10 908.59 906.05 906.10 899.10 9/5/2023 906.04 905.59 905.51 905.74 904.28 904.56 904.30 909.12 907.23 904.92 908.35 905.81 905.87 899.15 9/11/2023 906.06 905.66 905.61 905.77 904.52 904.77 903.51 909.03 907.03 904.95 908.17 905.45 904.85 900.03 9/18/2023 905.84 905.44 905.32 905.56 904.33 904.51 904.35 908.83 906.84 904.73 907.98 905.71 905.71 899.48 9/25/2023 905.95 905.51 905.46 905.65 904.51 904.69 903.09 908.65 906.74 904.80 907.20 905.75 905.72 899.43 10/2/2023 906.33 905.99 906.08 906.18 905.18 905.32 905.20 908.52 906.83 905.16 907.77 906.09 906.13 902.83 10/9/2023 906.43 906.08 906.19 906.30 905.33 905.48 905.35 908.45 906.88 905.30 907.75 903.58 10/16/2023 906.58 906.23 906.39 906.52 905.59 905.69 905.62 908.48 907.09 905.50 907.92 903.87 10/23/2023 906.60 906.17 906.36 906.48 905.50 905.66 905.53 908.38 907.14 905.45 907.91 906.74 10/30/2023 906.64 906.25 906.34 906.51 905.63 905.73 905.66 908.32 907.17 905.45 907.94 906.81 11/10/2023 906.53 906.16 906.26 906.37 905.53 905.65 908.27 907.07 905.44 907.86 906.47 906.42 906.63

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 8, Page 2 of 5 Table 5 - MNGP 2023 Static Water Level Elevation (Feet)

MW10B MW11 MW12A MW12B MW13A PW13A MW13B MW13Br MW14 MW15A MW15B PW16A MW16A MW16B MW17A 2/6/2023 906.77 907.09 906.33 906.42 906.47 905.83 905.98 906.24 906.28 906.90 2/13/2023 906.67 907.02 906.27 906.31 906.26 905.80 905.96 906.16 906.20 906.86 2/20/2023 906.81 907.11 906.42 906.46 906.51 905.95 906.09 906.30 907.00 2/27/2023 906.72 907.07 906.33 906.33 906.37 906.43 905.86 906.05 905.90 906.28 906.91 3/6/2023 906.65 907.00 906.18 906.13 906.23 906.32 905.77 905.87 905.77 906.14 906.84 3/14/2023 906.61 906.96 906.15 906.10 906.17 906.29 905.75 906.00 905.77 906.14 906.82 3/20/2023 906.61 906.96 906.22 906.15 906.17 906.30 905.81 905.75 905.85 905.79 906.12 906.86 3/26/2023 906.61 906.95 906.21 906.17 906.21 906.35 905.89 905.98 905.82 906.20 906.87 4/2/2023 906.76 906.29 906.30 906.34 906.46 906.07 905.95 906.34 4/3/2023 906.76 907.05 906.22 906.43 906.42 906.50 906.03 906.18 906.01 906.36 907.03 4/10/2023 907.09 907.26 906.66 906.74 905.01 906.90 906.61 906.74 906.32 906.76 907.31 4/17/2023 910.43 908.61 910.12 909.62 907.62 911.25 912.97 912.30 910.64 911.41 908.87 4/24/2023 911.83 910.44 912.11 912.26 909.89 912.35 912.99 912.73 912.45 912.56 911.15 4/26/2023 911.87 910.76 912.15 912.26 911.06 912.28 912.68 912.50 912.30 912.37 912.44 911.53 5/1/2023 911.83 911.18 911.97 911.99 911.28 911.98 912.01 911.96 911.98 912.05 912.05 911.93 5/8/2023 911.38 911.25 911.35 911.29 909.10 911.29 910.86 910.98 911.23 911.27 911.22 911.82 5/15/2023 911.14 911.18 910.93 910.91 909.06 910.93 910.49 910.62 910.35 910.66 910.83 911.59 5/22/2023 910.71 911.12 910.43 910.34 907.81 910.31 909.50 909.75 910.00 910.88 910.13 911.42 5/30/2023 909.90 910.77 909.49 909.35 909.39 909.24 908.07 908.42 908.39 908.91 908.99 910.94 6/5/2023 909.19 910.37 908.71 908.52 908.42 907.02 907.48 907.93 908.18 908.09 910.47 6/12/2023 908.56 909.91 907.68 907.75 907.74 906.40 906.83 905.87 906.92 907.34 909.86 6/19/2023 908.01 909.46 907.23 907.12 900.50 907.14 905.43 905.71 906.18 905.04 906.24 906.70 909.37 6/26/2023 907.68 909.06 906.80 906.75 896.98 906.83 905.40 905.51 905.98 904.74 905.36 906.38 908.89 7/5/2023 907.44 908.73 906.57 906.51 897.57 906.62 905.27 905.36 906.15 904.85 905.74 906.18 908.49 7/10/2023 907.25 908.57 906.39 906.33 900.46 906.41 905.06 905.54 904.37 905.44 905.95 908.32 7/19/2023 906.92 908.26 906.02 905.86 898.99 906.10 904.77 905.18 903.96 905.04 905.61 907.96 7/24/2023 906.74 908.07 905.85 905.80 899.50 905.93 904.81 904.61 905.09 903.82 904.89 905.46 907.76 7/31/2023 906.58 907.90 905.73 905.67 900.91 905.80 904.80 904.47 904.96 903.68 904.77 905.31 907.61 8/7/2023 906.53 907.75 905.78 905.62 898.07 905.76 904.86 904.42 904.82 904.74 905.20 905.34 907.44 8/14/2023 906.51 907.59 905.74 905.76 898.87 905.87 905.53 904.74 905.17 904.77 905.23 905.44 907.37 8/21/2023 906.45 907.68 905.82 905.72 898.51 905.77 904.53 904.98 904.83 905.24 905.39 907.52 8/28/2023 906.25 907.49 905.61 905.50 898.45 905.57 905.22 904.31 904.77 904.60 905.04 905.18 907.26 9/5/2023 906.04 907.27 905.40 905.31 897.57 905.36 904.85 904.13 904.58 904.39 904.83 904.97 907.01 9/11/2023 906.04 907.11 905.45 905.29 899.16 905.42 904.71 904.36 904.52 904.88 905.03 906.85 9/18/2023 905.84 906.95 905.20 905.15 901.73 905.21 904.57 904.11 904.47 904.32 904.73 904.84 906.63 9/25/2023 905.88 906.83 905.24 905.20 902.09 905.34 904.72 904.32 904.64 904.34 904.77 904.96 906.55 10/2/2023 906.27 906.96 905.60 905.62 899.65 905.85 905.09 905.04 905.34 904.82 905.22 905.49 906.70 10/9/2023 906.39 907.03 905.82 905.81 905.97 905.24 905.19 905.46 905.45 905.66 906.77 10/16/2023 906.51 907.13 906.02 906.01 906.13 905.52 905.41 891.21 905.66 905.87 906.94 10/23/2023 906.56 907.20 906.08 906.05 906.14 905.45 905.32 905.59 905.70 905.87 907.04 10/30/2023 906.54 907.23 906.17 905.38 905.42 905.63 906.04 905.97 907.06 11/10/2023 906.47 907.09 906.03 906.01 904.43 906.12 905.37 905.34 905.58 905.52 905.83 905.85 906.93

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 8, Page 3 of 5 Table 5 - MNGP 2023 Static Water Level Elevation (Feet)

MW17B MW19A MW19B MW20A MW21A PW22A MW23A MW23B MW24A MW26A MW26B MW27A MW27B MW28A MW28B 2/6/2023 906.60 906.27 906.23 906.08 906.34 2/13/2023 906.49 906.16 906.10 906.00 906.26 2/20/2023 906.30 906.20 906.40 2/27/2023 906.52 906.26 906.27 906.20 906.40 3/6/2023 906.46 906.11 906.08 906.08 906.31 3/14/2023 906.43 906.10 906.07 906.10 906.37 3/20/2023 906.44 906.11 906.09 906.13 906.36 3/26/2023 906.46 906.18 906.16 906.17 906.39 906.06 906.17 4/2/2023 906.31 906.22 906.28 4/3/2023 906.63 906.36 906.33 906.38 906.64 906.20 906.30 4/10/2023 906.91 906.67 906.59 906.74 907.02 906.77 906.82 4/17/2023 910.13 910.64 910.95 911.30 910.92 910.22 912.97 912.32 4/24/2023 911.97 912.55 912.36 912.72 912.12 912.19 913.12 912.89 4/26/2023 912.05 912.47 912.46 912.55 912.04 912.19 912.82 910.47 5/1/2023 911.88 912.10 912.07 912.06 911.84 911.94 912.15 912.13 5/8/2023 911.36 911.30 911.21 911.13 911.18 911.25 911.03 911.14 5/15/2023 911.04 910.83 910.78 910.74 910.98 910.79 910.65 910.75 5/22/2023 910.63 910.26 910.19 910.04 910.46 910.28 909.69 909.91 5/30/2023 909.77 909.20 909.05 908.94 909.69 909.07 908.29 908.60 6/5/2023 909.01 908.30 908.15 907.94 908.85 908.46 907.26 907.62 6/12/2023 908.34 907.51 907.39 907.25 908.32 907.60 906.66 906.94 909.56 6/19/2023 907.76 906.84 906.70 906.55 907.77 906.96 905.95 906.28 909.13 905.57 906.06 905.64 905.99 6/26/2023 907.37 906.42 906.34 906.24 907.49 906.54 905.40 906.02 908.71 905.50 905.62 905.53 905.86 7/5/2023 907.12 906.22 906.15 906.06 907.24 905.10 906.36 908.38 905.41 905.78 905.41 905.71 7/10/2023 906.93 906.04 905.95 905.84 907.03 906.12 904.83 905.59 908.21 905.13 905.47 905.05 905.40 905.07 905.31 7/19/2023 906.57 905.66 905.60 905.49 906.72 905.77 904.16 905.29 907.90 904.92 905.23 904.83 905.13 904.83 905.09 7/24/2023 906.40 905.49 905.40 905.34 906.57 905.58 903.96 905.13 907.70 904.86 905.07 904.68 904.98 904.69 904.94 7/31/2023 906.27 905.38 905.30 905.22 906.46 905.46 903.78 905.00 907.54 904.83 904.92 904.55 904.82 904.53 904.79 8/7/2023 906.24 905.40 905.31 905.18 906.34 905.54 903.74 905.02 907.43 904.71 904.85 904.44 904.78 904.44 904.72 8/14/2023 906.19 905.42 905.37 905.32 906.36 905.49 904.02 905.21 907.27 905.09 905.23 904.91 905.14 904.91 905.14 8/21/2023 906.20 905.45 905.35 905.27 906.34 905.58 904.17 905.06 907.33 905.04 904.92 904.57 904.84 904.54 904.81 8/28/2023 906.02 905.26 905.16 905.06 906.11 905.38 903.93 904.83 907.18 904.87 904.68 904.35 904.62 904.31 904.59 9/5/2023 905.80 905.04 904.96 904.85 905.90 903.73 904.64 906.95 904.93 904.51 904.16 904.43 904.15 904.40 9/11/2023 905.78 905.05 904.99 904.91 905.86 905.18 904.01 904.81 906.81 905.00 904.71 904.40 904.63 904.41 904.61 9/18/2023 905.58 904.88 904.81 904.74 905.66 903.92 904.55 906.66 904.80 904.40 903.95 904.35 903.95 904.31 9/25/2023 905.63 904.95 904.89 904.82 905.71 905.06 904.10 904.76 906.57 904.98 904.63 904.30 904.58 904.30 904.54 10/2/2023 906.01 905.37 905.36 905.31 905.97 905.42 904.81 905.39 906.75 905.47 905.35 905.17 905.28 905.18 905.26 10/9/2023 906.17 905.63 905.60 905.54 906.10 905.66 905.51 906.85 905.51 905.44 905.22 905.39 905.21 905.37 10/16/2023 906.31 905.85 905.82 905.78 906.30 905.71 906.95 905.71 905.63 905.38 905.59 905.39 905.56 10/23/2023 906.38 905.91 905.84 905.79 906.27 905.68 907.03 905.57 905.55 905.28 905.52 905.28 905.50 10/30/2023 906.44 905.99 905.91 905.83 906.27 905.76 907.06 905.55 905.56 905.23 905.55 905.23 905.51 11/10/2023 906.26 905.84 905.81 905.79 906.26 905.54 905.69 906.91 905.58 905.61 905.30 905.61 905.33 905.54

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 8, Page 4 of 5 Table 5 - MNGP 2023 Static Water Level Elevation (Feet)

MW29A MW29B PW30A MW30A MW30B MW31A MW31B MW33A MW33B MW37A MW37B MW48A MW48B MW50A 2/6/2023 2/13/2023 2/20/2023 2/27/2023 3/6/2023 3/14/2023 3/20/2023 3/26/2023 4/2/2023 4/3/2023 4/10/2023 4/17/2023 4/24/2023 4/26/2023 5/1/2023 5/8/2023 5/15/2023 5/22/2023 5/30/2023 6/5/2023 6/12/2023 6/19/2023 6/26/2023 7/5/2023 7/10/2023 905.17 905.36 905.25 905.40 905.80 905.65 7/19/2023 904.82 905.07 904.30 904.73 905.09 905.42 905.33 904.80 905.04 7/24/2023 904.69 904.93 904.18 904.60 904.94 905.26 905.16 904.66 904.90 7/31/2023 904.54 904.79 904.04 904.45 904.80 905.17 905.03 904.52 904.75 904.58 904.69 904.59 905.62 904.92 8/7/2023 904.51 904.74 904.26 904.53 904.77 905.20 905.05 904.46 904.68 904.49 904.60 904.55 905.50 904.81 8/14/2023 904.89 905.08 904.61 904.89 905.08 905.27 905.20 904.90 905.06 904.90 905.03 904.95 905.99 905.15 8/21/2023 904.60 904.82 904.38 904.63 904.84 905.28 905.12 904.55 904.75 904.36 904.65 904.51 905.56 904.88 8/28/2023 904.39 904.61 904.24 904.41 904.62 905.07 904.92 904.33 904.52 904.15 900.33 904.31 905.34 904.67 9/5/2023 904.18 904.41 904.04 904.22 904.43 904.87 904.72 904.14 904.34 903.97 904.27 904.12 905.17 904.49 9/11/2023 904.46 904.63 904.28 904.44 904.64 904.90 904.81 904.42 904.59 904.25 904.53 904.45 905.48 904.72 9/18/2023 904.19 904.32 904.10 904.18 904.33 904.76 904.63 904.09 904.27 903.98 904.21 904.04 905.12 904.44 9/25/2023 904.43 904.55 904.34 904.44 904.56 904.82 904.75 904.39 904.51 904.26 904.44 904.36 905.38 904.66 10/2/2023 905.18 905.25 905.16 905.21 905.26 905.33 905.30 904.90 905.24 905.18 905.22 905.16 906.18 905.33 10/9/2023 905.29 905.37 905.71 904.79 905.37 905.55 905.49 905.34 905.27 905.31 905.22 906.25 905.43 10/16/2023 905.50 905.56 905.47 905.54 905.57 905.78 905.72 905.53 905.43 905.49 905.38 906.42 905.63 10/23/2023 905.43 905.51 905.38 905.46 905.53 905.79 905.71 905.47 905.34 905.40 905.27 906.30 905.54 10/30/2023 905.46 905.54 905.47 905.55 905.91 905.82 905.46 905.33 905.39 905.23 906.28 905.54 11/10/2023 905.52 905.55 906.44 905.47 905.62 905.76 905.68 905.39 905.53 905.36 905.42 905.32 906.39 905.55

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 8, Page 5 of 5 Table 5 - MNGP 2023 Static Water Level Elevation (Feet)

MW58A MW66A MW67A MW67B MW68A MW101 MW102 MW103 River 2/6/2023 905.82 2/13/2023 905.98 2/20/2023 905.72 2/27/2023 905.68 3/6/2023 905.85 3/14/2023 905.88 3/20/2023 905.94 3/26/2023 905.99 4/2/2023 905.94 4/3/2023 906.83 4/10/2023 913.51 4/17/2023 913.00 4/24/2023 912.88 4/26/2023 912.29 5/1/2023 911.15 5/8/2023 910.50 5/15/2023 909.28 5/22/2023 907.55 5/30/2023 906.40 6/5/2023 905.81 6/12/2023 905.12 6/19/2023 905.19 6/26/2023 905.05 7/5/2023 904.61 7/10/2023 904.40 7/19/2023 904.29 7/24/2023 904.04 7/31/2023 905.56 908.97 908.94 910.49 903.88 8/7/2023 905.42 908.66 908.67 910.00 904.74 8/14/2023 905.97 908.57 908.45 909.74 904.06 8/21/2023 905.49 908.60 908.45 909.66 903.78 8/28/2023 905.26 908.53 908.36 909.65 903.57 9/5/2023 905.10 904.03 9/11/2023 905.44 903.44 9/18/2023 905.04 903.95 9/25/2023 905.33 905.07 10/2/2023 906.16 904.97 10/9/2023 906.22 905.13 10/16/2023 906.37 904.93 10/23/2023 906.25 904.95 10/30/2023 906.20 905.89 905.97 905.98 907.19 904.95 11/10/2023 906.29 905.82 905.82 905.80 907.07 905.06

Enclosure 01 Attachment 9 Table 6 - Monthly Summary of Pumping Withdrawal Volume (gallons)

Monticello Nuclear Generating Plant L-MT-23-056, Enclosure 01 Docket 50-263 Attachment 9, Page 1 of 1 Table 6: Monthly Summary of Pumping Withdrawal Volume (gallons) 2023 MW-12A MW-23A MW-33A MW-37A MW-4A MW-9A MW-9B PW-1 PW-10A PW-13A PW-16A PW-22A PW-30A PW-4A PW-9 Total (Gallons)

January 26,191 0 0 0 0 3,465 3,465 0 0 0 0 0 0 0 0 33,121 February 35,690 0 0 0 0 7,776 5,007 0 0 0 74,503 0 0 0 41,500 164,476 March 3,674 0 0 0 0 4,081 395 21,126 0 0 334,705 0 0 0 89,477 453,458 April 49,879 0 0 0 0 14,922 597 21,004 4,911 42,924 176,624 0 0 0 67,746 378,607 May 119,266 0 0 0 0 18,466 0 36,932 20,597 68,334 120,074 0 0 0 75,829 459,498 June 9,454 38,113 0 0 38,865 5,990 0 20,751 76,227 77,005 532,155 0 0 0 50,274 848,834 July 0 285,016 0 0 39,453 0 0 10,654 69,682 91,600 698,870 0 208,606 107,919 31,962 1,543,762 August 0 291,610 0 69,947 0 0 0 16,065 67,459 110,640 260,120 0 384,017 1 48,196 1,248,055 September 0 178,301 22,212 106,716 0 0 0 46 56,758 78,190 292,330 0 176,913 0 47,351 958,817 October 0 112,621 98,831 0 0 0 0 1,125 20,542 49,829 190,107 0 0 108 72,708 545,871 Total 244,154 905,661 121,043 176,663 78,318 54,700 9,464 127,703 316,176 518,522 2,679,488 0 769,536 108,028 525,043 6,634,499

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