ML25132A129

Independent Spent Fuel Storage Installation - 2024 Annual Radiological Environmental Monitoring Program Report

ML25132A129
Person / Time
Site:	Prairie Island
Issue date:	05/09/2025
From:	Currier B Northern States Power Company, Minnesota, Xcel Energy
To:	Office of Nuclear Material Safety and Safeguards, Office of Nuclear Reactor Regulation, Document Control Desk
References
L-Pl-25-014
Download: ML25132A129 (1)

Text

fl Xcel Energy*

May 10, 2025 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant, Units 1 and 2 Docket Nos. 50-282 and 50-306 Renewed Facility Operating License Nos. DPR-42 and DPR-60 Prairie Island Independent Spent Fuel Storage Installation Docket No. 72-10 Renewed Materials License No. SNM-2506 1717 Wakonade Drive Welch, MN 55089 L-Pl-25-014 Tech Spec 5.6.2 ISFSI Tech Spec 5.2 2024 Annual Radiological Environmental Monitoring Program Report Pursuant to the requirements of Prairie Island Nuclear Generating Plant Technical Specifications, Section 5.6.2 and ISFSI Technical Specifications, Section 5.2, Northern States Power Company, a Minnesota corporation, doing business as Xcel Energy (hereafter "NSPM"), submits the enclosed Annual Radiological Environmental Monitoring Program Report for the period of January 1, 2024 through December 31, 2024.

Summary of Commitments Th r

ter ma c

commitments and no revisions to existing commitments.

Bryaner Plant Manager, Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure

Document Control Desk L-Pl-25-014 Page 2 cc:

Administrator, Region Ill, USNRC Project Manager, Prairie Island, USNRC Resident Inspector, Prairie Island, USNRC Director of NMSS, USNRC Department of Health, State of Minnesota Pl Dakota Community Environmental Coordinator

ENCLOSURE ANNUAL REPORT TO THE UNITED STATES NUCLEAR REGULATORY COMMISSION Radiological Environmental Monitoring Program JANUARY 1, 2024 - DECEMBER 31, 2024 74 pages to follow

@MICROBAC 700 Landwehr Road* Northbrook, IL 60062-2310 phone (847) 564-0700

• fax (847) 564-4517 Approved:

XCEL ENERGY CORPORATION PRAIRIE ISLAND NUCLEAR GENERATING PLANT ANNUAL REPORT to the UNITED STATES NUCLEAR REGULATORY COMMISSION Radiological Environmental Monitoring Program January 1 to December 31, 2024 Docket No. 50-282 Renewed Operating License No. DPR-42 Docket No. 50-306 Renewed Operating License No. DPR-60 ISFSI Docket No. 72-10 Renewed License No. SNM-2506 Prepared under Contract by Microbac Laboratories - Northbrook Ashok Banavali, Ph.D.

Laboratory Manager Project No. 8010

ii PREFACE The staff of Microbac Laboratories - Northbrook was responsible for the acquisition of data presented in this report. Samples were collected by members of the staff of the Prairie Island Nuclear Generating Plant, operated by Northern States Power Co. - Minnesota, for XCEL Energy Corporation.

The report was prepared by Microbac Laboratories - Northbrook.

iii TABLE OF CONTENTS Section Page Preface.................................................................................................................................................... ii List of Tables.......................................................................................................................................... iv List of Figures.......................................................................................................................................... v

1.0 INTRODUCTION

..................................................................................................................................... 1 2.0

SUMMARY

.............................................................................................................................................. 2 3.0 RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM (REMP)............................................ 3 3.1 Program Design and Data Interpretation....................................................................................... 3 3.2 Program Description...................................................................................................................... 4 3.3 Program Execution........................................................................................................................ 5 3.4 Laboratory Procedures.................................................................................................................. 5 3.5 Program Modifications................................................................................................................... 5 3.6 Land Use Census.......................................................................................................................... 6 4.0 RESULTS AND DISCUSSION................................................................................................................ 7 4.1 Atmospheric Nuclear Detonations and Nuclear Accidents............................................................ 7 4.2 Summary of Preoperational Data.................................................................................................. 7 4.3 Program Findings.......................................................................................................................... 8 5.0 FIGURES AND TABLES........................................................................................................................ 12

6.0 REFERENCES

CITED.......................................................................................................................... 24 APPENDICES A

Interlaboratory Comparison Program Results....................................................................................... A-1 Attachment A, Acceptance Criteria for "Spiked" Samples................................................................ A-2 B

Data Reporting Conventions................................................................................................................. B-1 C

Annual Average Effluent Concentration Limits of Radioactivity in Air and Water Above Background in Unrestricted Areas.......................................................................................... C-1 D

Sampling Location Maps..................................................................................................................... D-1 E

Special Well and Surface Water Samples........................................................................................... E-1

iv LIST OF TABLES No.

Title Page 5.1 Sample Collection and Analysis Program................................................................................................. 15 5.2 Sampling Locations................................................................................................................................... 16 5.3 Missed Collections and Analyses.............................................................................................................. 19 5.4 Radiological Environmental Monitoring Program Summary...................................................................... 20 In addition, the following tables can be found in the Appendices:

Appendix A A-1 Environmental Resources Associates, Crosscheck Program Results....................................................... A-3 A-2 Program Results; (TLDs)........................................................................................................................ A-4 A-3 In-house "Spiked" Samples.................................................................................................................... A-6 A-4 In-house Blank Samples......................................................................................................................... A-9 A-5 In-house "Duplicate" Samples.........................................................................................................................A-11 A-6 Department of Energy MAPEP comparison results................................................................................A-15 A-7 Environmental Resources Associates, Crosscheck Program Results (EML study replacement)............A-17 Appendix C C-1 Average Annual Effluent Concentration Limits of Radioactivity in Air and Water Above Natural Background in Unrestricted Areas................................................................................. C-2 Appendix E E-4.1 Sample collection and analysis program................................................................................................ E-5 E-4.2 Sampling locations................................................................................................................................. E-6 E-4.3 REMP Summary..................................................................................................................................... E-8 E-4.4 REMP Complete Data Tables................................................................................................................ E-9 E-4.5 Supplementary Data Tables.................................................................................................................. E-14

v LIST OF FIGURES No.

Title Page 5.1 Offsite Ambient Radiation (TLDs), average of inner and outer ring indicator locations versus control............................................................................................................................... 13 5.2 Airborne Particulates; analysis for gross beta, average mean of all indicator locations (P-2,3,4,6,7) versus control location (P-1).................................................................................... 14 MAPS Appendix D Title Page TLD locations within a one mile radius..................................................................................................... D-2 TLD locations, Controls.............................................................................................................................. D-3 TLD locations, surrounding the ISFSI Area................................................................................................ D-3 TLD locations within a five mile radius..................................................................................................... D-4 REMP sampling points within a one mile radius...................................................................................... D-5 REMP sampling points within a five mile radius....................................................................................... D-6 REMP sampling points, Control locations............................................................................................... D-7 Appendix E Groundwater Monitoring Well locations................................................................................................... E-15

1

1.0 INTRODUCTION

This report summarizes and interprets results of the Radiological Environmental Monitoring Program (REMP) conducted by Microbac Laboratories - Northbrook at the Prairie Island Nuclear Generating Plant, Red Wing, Minnesota, during the period January - December, 2024.

This program monitors the levels of radioactivity in the air, terrestrial, and aquatic environments in order to assess the impact of the plant on its surroundings.

Tabulations of the individual analyses made during the year are not included in this report.

These data are included in a reference document (Microbac Laboratories - Northbrook, 2024b) available at Prairie Island Nuclear Generating Plant.

Prairie Island Nuclear Generating Plant is located on the Mississippi River in Goodhue County, Minnesota, owned by Xcel Energy Corporation and operated by Northern States Power Co.- Minnesota. The plant has two 575 MWe pressurized water reactors. Unit 1 achieved initial criticality on 1 December 1973. Commercial operation at full power began on 16 December 1973. Unit 2 achieved initial criticality on 17 December 1974. Commercial operation at full power began on 21 December 1974.

2 2.0

SUMMARY

The Radiological Environmental Monitoring Program (REMP) required by the U.S. Nuclear Regulatory Commission (NRC) Offsite Dose Calculation Manual for the Prairie Island Nuclear Generating Plant and the Independent Spent Fuel Storage Installation (ISFSI) is described.

Results for 2024 are summarized and discussed.

Program findings show background levels of radioactivity in the environmental samples collected in the vicinity of the Prairie Island Nuclear Generating Plant.

3 3.0 RADIOLOGICAL ENVIRONMENTAL MONITORING PROGRAM (REMP) 3.1 Program Design and Data Interpretation The purpose of the Radiological Environmental Monitoring Program (REMP) at the Prairie Island Nuclear Generating Plant is to assess the impact of the plant on its environment. For this purpose, samples are collected from the air, terrestrial, and aquatic environments and analyzed for radioactive content. In addition, ambient gamma radiation levels are monitored by thermoluminescent dosimeters (TLDs).

Sources of environmental radiation include the following:

(1)

Natural background radiation arising from cosmic rays and primordial radionuclides; (2)

Fallout from atmospheric nuclear detonations; (3)

Releases from nuclear power plants; (4)

Industrial and medical radioactive waste; and (5)

Fallout from nuclear accidents.

In interpreting the data, effects due to the plant must be distinguished from those due to other sources.

A major interpretive aid in assessment of these effects is the design of the monitoring program at the Prairie Island Plant which is based on the indicator-control concept. Most types of samples are collected both at indicator locations (nearby, downwind, or downstream) and at control locations (distant, upwind, or upstream). A plant effect would be indicated if the radiation level at an indicator location was significantly larger than that at the control location. The difference would have to be greater than could be accounted for by typical fluctuations in radiation levels arising from other sources.

An additional interpretive technique involves analyses for specific radionuclides present in the environmental samples collected from the plant site. The plants monitoring program includes analyses for tritium and iodine-131. Most samples are analyzed for gamma-emitting isotopes with results for the following groups quantified: zirconium-95, cesium-137, cerium-144, beryllium-7, and potassium-40. The first three gamma-emitting isotopes were selected as radiological impact indicators because of the different characteristic proportions in which they appear in the fission product mix produced by a nuclear reactor and that produced by a nuclear detonation. Each of the three isotopes is produced in roughly equivalent amounts by a reactor: each constitutes about 10%

of the total activity of fission products 10 days after reactor shutdown. Alternatively, 10 days after a nuclear explosion, the contributions of zirconium-95, cerium-144, and cesium-137 to the activity of the resulting debris are in the approximate ratio 4:1:0.03 (Eisenbud, 1963). Beryllium-7 is of cosmogenic origin and potassium-40 is a naturally-occurring isotope. They were chosen as calibration monitors and should not be considered radiological impact indicators.

The other group quantified consists of niobium-95, ruthenium-103 and -106, cesium-134, barium-lanthanum-140, and cerium-141. These isotopes are released in small quantities by nuclear power plants, but to date their major source of injection into the general environment has been atmospheric nuclear testing. Nuclides of the final group, manganese-54, iron-59, cobalt-58 and - 60, and zinc-65, are activation products and arise from activation of corrosion products. They are typical components of a nuclear power plants effluents, but are not produced in significant quantities by nuclear detonations.

4 3.1 Program Design and Data Interpretation (continued)

Other means of distinguishing sources of environmental radiation are employed in interpreting the data. Current radiation levels are compared with previous levels, including those measured before the plant became operational. Results of the plants monitoring program can be related to those obtained in other parts of the world. Finally, results can be related to events known to cause elevated levels of radiation in the environment, e.g., atmospheric nuclear detonations.

3.2 Program Description The sampling and analysis schedule for the radiological environmental monitoring program at Prairie Island is summarized in Table 5.1 and briefly reviewed below. Table 5.2 defines the sampling location codes used in Table 5.1 and specifies for each location its type (indicator or control) and its distance, direction, and sector relative to the reactor site or ISFSI facility, as appropriate. To assure that sampling is carried out in a reproducible manner, detailed sampling procedures have been prescribed (Prairie Island Nuclear Generating Plant, 2024). Maps of fixed sampling locations are included in Appendix D.

To monitor the airborne environment, air is sampled by continuous pumping at six stations, four site boundary indicators (P-2, P-3, P-4 and P-7), located in the highest calculated D/Q sectors, one community indicator (P-6), and one control (P-1). The particulates are collected on membrane filters, airborne iodine is trapped by activated charcoal canisters. Particulate filters are analyzed for gross beta activity and charcoal canisters for iodine-131. Quarterly composites of particulate filters from each location are analyzed for gamma-emitting isotopes.

Offsite ambient gamma radiation is monitored at thirty-four locations, using CaSO4:Dy dosimeters with four sensitive areas at each location: ten in an inner ring in the general area of the site boundary, fifteen in the outer ring within a 4-5 mile radius, eight at special interest locations, and one control location, 11.1 miles distant from the plant. They are replaced and measured quarterly.

Ambient gamma radiation is monitored at the Independent Spent Fuel Storage Installation (ISFSI)

Facility by twenty CaSO4:Dy dosimeters. Twelve dosimeters are located inside of the earthen berm in direct line of sight from the storage casks and eight dosimeters are located outside of the earthen berm. They are replaced and measured quarterly.

To monitor the terrestrial environment, green leafy vegetables (cabbage) are collected annually from the highest D/Q garden and a control location (P-38), and analyzed for gamma-emitting isotopes, including iodine-131. Corn is collected annually only if fields are irrigated with river water and analyzed for gamma-emitting isotopes. Well water and ground water are collected quarterly from five locations near the plant and analyzed for tritium and gamma-emitting isotopes.

River water is collected weekly at two locations, one upstream of the plant (P-5) and one downstream (P-6, Lock and Dam No.3). Monthly composites are analyzed for gamma-emitting isotopes. Quarterly composites are analyzed for tritium.

Drinking water is collected weekly from the City of Red Wing well. Monthly composites are analyzed for gross beta, iodine-131, and gamma-emitting isotopes. Quarterly composites are analyzed for tritium.

5 3.2 Program Description (continued)

The aquatic environment is also monitored by semi-annual upstream and downstream collections of fish, periphyton or invertebrates, and bottom sediments. Shoreline sediment is collected semi-annually from one location. All samples are analyzed for gamma-emitting isotopes.

3.3 Program Execution The Program was executed as described in the preceding section in 2024 with the following exceptions:

TLDs exposed to external source while in-transit between Prairie Island Nuclear Generating Plant and the processing lab. (See section 4.3 for details).

3.4 Laboratory Procedures The iodine-131 analyses in drinking water were made using a sensitive radiochemical procedure which involves separation of the iodine using an ion-exchange method, solvent extraction and subsequent beta counting.

Gamma-spectroscopic analyses were performed using high-purity germanium (HPGe) detectors.

Levels of iodine-131 in cabbage and natural vegetation and concentrations of airborne iodine-131 in charcoal samples were determined by gamma spectroscopy.

Tritium concentrations were determined by liquid scintillation.

Analytical Procedures used by Microbac Laboratories - Northbrook are on file and are available for inspection. Procedures are based on those prescribed by the Health and Safety Laboratory of the U.S. Department of Energy, Edition 28, 1997, U.S. Environmental Protection Agency for Measurement of Radioactivity in Drinking Water, 1980, and the U.S. Environmental Protection Agency, EERF, Radiochemical Procedures Manual, 1984.

Microbac Laboratories - Northbrook has a comprehensive quality control/quality assurance program designed to assure the reliability of data obtained. Details of the QA Program are presented elsewhere (Microbac Laboratories - Northbrook, 2024). The QA Program includes participation in Interlaboratory Comparison (crosscheck) Programs. Results obtained in the crosscheck programs are presented in Appendix A.

3.5 Program Modifications None.

6 3.6 Land Use Census In accordance with the Prairie Island Nuclear Generating Plant Offsite Dose Calculation Manual, H4, (ODCM) a land use census is conducted in order to identify the location of the nearest residence, nearest milk animals, and the nearest garden of greater than 500 ft2 producing fresh leafy vegetables in each of the 16 meteorological sectors within a distance of 5 miles. This census is conducted at least once per 12 months between the dates of May 1 and September 30.

If new locations yield a calculated dose or dose equivalent (via the same exposure pathway) twenty percent greater than the required locations per the ODCM, then the new locations are added to the radiological environmental monitoring program within 30 days, and sampling locations having lower calculated doses or a lower dose commitment may be deleted from this monitoring program after September of the year in which the land use census was conducted.

This land use census ensures the updating of the radiological environmental monitoring program should sampling locations change within the 5-mile radius from the plant.

The Land Use Census was conducted during September 2024. The ranking of the highest D/Q garden remained the same for 2024 as 2023, 5016 Lock & Dam Rd., Welch, MN (SSE at 0.6 miles). The highest D/Q residence remained the same for 2024 as for 2023, 1860 Edoka St.,

Welch, MN (WNW at 0.7 miles).

The Minnesota and Wisconsin Departments of Natural Resources were both consulted and both confirmed that no irrigation permits had been issued the past year for crop fields within the file mile Mississippi River area downstream of the Prairie Island Plant. Plant biologists conducted visual surveys while electro-fishing and visual observations were taken while driving. No irrigating was observed. Therefore, no crop sampling was performed.

There are no dairy farms within a 5-mile radius of the plant therefore no milk samples were collected.

Vegetation samples were taken from one close garden in the vicinity of the plant this year plus a control site. An additional sample was taken in October, 2024.

There were no land use changes within five miles of the plant resulting in new special interest areas such as: new population centers, new residences, new schools or recreation centers.

7 4.0 RESULTS AND DISCUSSION All scheduled collections and analyses were made in 2024 except those listed in Table 5.3..

The results are summarized in Table 5.4 in a format recommended by the Nuclear Regulatory Commission in Regulatory Guide 4.8. For each type of analysis of each sampled medium, this table lists the mean and range for all indicator locations and for all control locations. The locations with the highest mean and range are also shown.

4.1 Atmospheric Nuclear Detonations and Nuclear Accidents There were no reported accidents involving significant release to the environment at nuclear reactor facilities in 2024. The Fukushima Daiichi nuclear accident occurred March 11, 2011.

There were no reported atmospheric nuclear tests in 2024. The last reported test was conducted on October 16, 1980 by the Peoples Republic of China.

4.2 Summary of Preoperational Data The following constitutes a summary of preoperational studies conducted at the Prairie Island Nuclear Power Plant during the years 1970 to 1973, to determine background levels expected in the environment, and provided, where applicable, as a means for comparison with present day levels. Strict comparisons, however, are difficult, since background levels of radiation were much higher in these years due to radioactive fallout from the atmosphere. Gross beta measurements in fallout declined yearly from a level of 12,167 pCi/m3 to 1,020 pCi/m3, and these declining values are reflected throughout the various media tested.

In the air environment, ambient gamma radiation (TLDs) averaged 9.4 mR/4 weeks during pre-operational studies. Gross beta in air particulates declined from levels of 0.38 to 0.037 pCi/m3.

Average present day levels have stabilized at around 0.025 pCi/m3. Airborne radioiodine remained below detection levels.

In the terrestrial environment of 1970 to 1973, milk, agricultural crops, and soil were monitored.

In milk samples, low levels of Cs-137, I-131, and Sr-90 were detected. Cs-137 levels declined from 16.5 to 8.6 pCi/L. Present day measurements for both Cs-137 and I-131 are below detection levels. Agricultural crop measurements averaged 57.7 pCi/g for gross beta and 0.47 pCi/g for Cs-137. Gross beta measured in soil averaged 52 pCi/g.

The aqueous environment was monitored by testing of river, well and lake waters, bottom sediments, fish, aquatic vegetation and periphyton. Specific location comparison of drinking, river and well water concentrations for tritium and gross beta are not possible. However, tritium background levels, measured at eight separate locations, declined steadily from an average concentration of 1020 pCi/L to 490 pCi/L. Present day environmental levels of tritium measure below a detection limit of approximately 160 pCi/L. Values for gross beta, measured from 1970 to 1973, averaged 9.9 pCi/L in downstream Mississippi River water, 8.2 pCi/L for well water, and11.0 pCi/L for lake water. Gamma emitters were below the lower limit of detection (LLD). In bottom sediments, gross beta background levels were determined at 51.0 pCi/g. Cs-137 activity during preoperational studies in 1973 measured 0.25 pCi/g upstream and 0.21 pCi/g downstream.

The lower levels occasionally observed today can still be attributed to residual activity from atmospheric fallout. Gross beta in fish, measured in both flesh and skeletal samples, averaged 7.3 and 11.7 pCi/g, respectively. Gross beta background levels in aquatic vegetation, algae and periphyton samples measured 76.0 pCi/g, 46.0 pCi/g, and 13.6 pCi/g, respectively.

8 4.3 Program Findings Results obtained show background levels of radioactivity in the environmental samples collected in the vicinity of the Prairie Island Nuclear Generating Plant.

Ambient Radiation (TLDs)

Ambient radiation was measured in the general area of the site boundary, at the outer ring 4 - 5 mi. distant from the Plant, at special interest areas and at one control location. The means were from 15.5 mR/91 days at the inner ring and 15.3 mR/91 days at the outer ring locations. The mean at special interest locations was 16.1 mR/91 days and 16.6 mR/91 days at the control location. Dose rates measured at the inner and outer ring and the control locations were comparable to 2023 dose rates and consistent with results from previous years. The results are tabulated below.

Fourth quarter 2024 REMP TLDs were exposed to an external source in transit between Prairie Island Nuclear Generating Plant and the TLD processor. This exposure affected eight TLD results that were flagged by the ANSI/HPS N13.37-2014 methodology as exceeding detectable levels for the quarter. Additionally, one TLD result was high enough to cause the annual dose at one location to surpass the detectable level. All elevated doses were attributed to in-transit irradiation and not to operation at the Prairie Island Plant. All eight affected TLD results were treated as missed samples and replaced by the average of the second and third quarter results for those locations as directed by site procedure. No plant effect on ambient gamma radiation measurements was indicated (Figure 5-1).

Year Average (Inner and Outer Rings)

Control Year Average (Inner and Outer Rings)

Control 2001 16.8 17.2 2013 15.1 16.0 2002 17.4 16.9 2014 15.3 16.2 2003 16.2 16.0 2015 16.0 17.4 2004 17.6 17.6 2016 16.7 17.4 2005 16.8 16.3 2017 16.1 16.3 2006 16.6 16.6 2018 16.6 17.4 2007 17.5 17.7 2019 15.8 15.3 2008 16.9 17.1 2020 15.4 14.2 2009 15.9 16.3 2021 16.4 15.9 2010 16.0 16.0 2022 16.7 17.5 2011 15.7 15.7 2023 15.8 16.3 2012 16.5 16.5 2024 15.4 16.6 Ambient gamma radiation as measured by thermoluminescent dosimetry.

Average quarterly dose rates (mR/91 days).

ISFSI Facility Operations Monitoring Ambient radiation was measured inside the ISFSI earth berm, outside the ISFSI earth berm and at two special locations between the plant ISFSI and the Prairie Island Indian Community. The mean dose rates averaged 201.4 mR/91 days inside the ISFSI earth berm and 24.7 mR/91 days outside the ISFSI earth berm. Two additional casks were placed on the ISFSI pad in 2024, a total of fifty-two loaded casks remain. The higher levels inside the earth berm are expected, due to the loaded spent fuel casks being in direct line-of-sight of the TLDs.

Ambient radiation levels measured outside the earth berm show a slight increase as compared

9 to other offsite dose rates around the plant. The cumulative average of the two special Prairie Island Indian Community TLDs (Locations P-07S and P-08S) measured 14.7 and 14.9 mR/91 days. Although the skyshine neutron dose rates are not directly measured, the neutron levels measured next to the casks are below the levels predicted in the ISFSI SAR Report, Table 7A-4, TN-40 Dose Rates at Short Distances. Therefore, the skyshine dose rates at farther distances from the casks should be at or below the calculated dose rates. No spent fuel storage effect on offsite ambient gamma radiation was indicated (Fig. 5-1).

Airborne Particulates Typically, the highest averages for gross beta occur during the months of January and December, and the first and fourth quarters, as in 2001 through 2006, and also in 2008 through 2023. The elevated activity observed in 2007 was attributed to construction activity in the area, an increase in dust and consequent heavier particulate filter loading.

Average annual gross beta concentrations in airborne particulates were 0.029 pCi/m3 for the indicator location and 0.027 pCi/m3 for the control location and are similar to levels observed from 2001 through 2006 and 2008 to 2023. The results are tabulated below.

Year Average of Indicators Control Concentration (pCi/ m3) 2001 0.023 0.023 2002 0.028 0.023 2003 0.027 0.025 2004 0.025 0.026 2005 0.027 0.025 2006 0.026 0.025 2007 0.037 0.031 2008 0.028 0.027 2009 0.029 0.029 2010 0.025 0.025 2011 0.026 0.027 2012 0.031 0.032 2013 0.027 0.028 2014 0.026 0.026 2015 0.029 0.029 2016 0.027 0.027 2017 0.026 0.025 2018 0.027 0.027 2019 0.023 0.023 2020 0.027 0.025 2021 0.030 0.029 2022 0.030 0.031 2023 0.033 0.033 2024 0.029 0.027 Average annual gross beta concentrations in airborne particulates.

Gamma spectroscopic analysis of quarterly composites of air particulate filters yielded similar results for indicator and control locations. Beryllium-7, which is produced continuously in the upper atmosphere by cosmic radiation (Arnold and Al-Salih, 1955), was detected in all samples, with an average activity of 0.067 pCi/m3 for indicator locations and 0.063 pCi/m3 at the control location. All other isotopes were below the lower limit of detection.

10 There was no indication of a plant effect.

Airborne Iodine Weekly levels of airborne iodine-131 were below the lower limit of detection (LLD) of 0.03 pCi/m3 in all samples. There was no indication of a plant effect.

Drinking Water In drinking water from the City of Red Wing well, tritium activity measured below a detection limit of 183 pCi/L for all samples.

Gross beta concentrations averaged 10.5 pCi/L throughout the year, ranging from 7.2-14.0 pCi/L. These concentrations are consistent with the 2023 average of 9.8 pCi/L and with levels observed from 2000 through 2022. The most likely contribution is the relatively high levels of naturally-occurring radium. Gamma spectroscopy indicates the presence of lead and bismuth isotopes, which are daughters of the radium decay chain. There is no indication from the 2024 data of any effect of plant operation.

Year Gross Beta concentration (pCi/L) 2000 10.1 2001 8.3 2002 8.7 2003 9.9 2004 9.8 2005 11.5 2006 13.4 2007 11.6 2008 11.6 2009 11.4 2010 11.7 2011 12.4 2012 11.8 2013 12.2 2014 11.5 2015 11.4 2016 12.3 2017 10.1 2018 10.2 2019 9.7 2020 8.6 2021 9.2 2022 8.9 2023 9.8 2024 10.5 Average annual gross beta concentrations in drinking water.

11 River Water Analyses for H-3 in river water was below an LLD of 183 pCi/L for the four quarterly composites from the upstream location for 2024. H-3 was detected at the River Water Lock and Dam #3 location P-6 in the first quarter composite sample at a concentration of 347 +/- 98 pCi/L. Further analysis of the constituent monthly and weekly samples identified positive results for the February composite of (1167 +/- 142 pCi/L), and the weekly sample from 2/21/24 (4655 +/- 229 pCi/L). All other samples analyzed from location P-6 were below an LLD of 183 pCi/L. The positive H-3 results are attributed to river water sampling shortly following planned liquid discharges of radioactivity from the plant. Gamma-emitting isotopes were below detection limits in all samples.

Well Water Water samples tested from the control well, P-43 (Peterson Farm) and from four indicator wells (P-8, Community Center, P-6, Lock and Dam No. 3, P-9, Plant Well No. 2 and P-24, Suter Farm) showed no tritium detected above a detection limit of 183 pCi/L. Gamma-emitting isotopes were below detection limits in all samples.

In summary, well water data for 2024 show no radiological effects of the plant operation.

Broadleaf Vegetation and Crops Three samples of broadleaf vegetation, cabbage leaves, were collected in October 2024 and analyzed for gamma-emitting isotopes, including iodine-131. The I-131 level was below 0.007 pCi/g wet weight in all samples. With exceptions for naturally-occurring beryllium-7 and potassium-40, all other gamma-emitting isotopes were below their respective detection limits.

There was no indication of a plant effect.

Field sampling personnel conducted an annual land use survey and found no river water taken for irrigation into fields within five miles downstream from the Prairie Island Plant. The collection and analysis of corn samples was not required since the fields have not been irrigated.

Fish Fish were collected in May and September 2024 and analyzed for gamma-emitting isotopes.

Only naturally-occurring potassium-40 was detected, and there was no significant difference between upstream and downstream results. There was no indication of a plant effect.

Aquatic Insects or Periphyton Aquatic insects (invertebrates) or periphyton were collected in May and September/October 2024 and analyzed for gamma-emitting isotopes. All gamma-emitting isotopes measured below detection limits with the exception of naturally occurring potassium-40 which was detected in all four samples. There was no indication of any plant effect.

Bottom and Shoreline Sediments Upstream and downstream bottom sediments and downstream recreational area shoreline sediments were sampled May and September/October 2024. All gamma-emitting isotopes measured below detection limits with the exception of naturally occurring beryllium-7 and potassium-40.

Beryllium-7 was detected at the upstream bottom sediment sample taken from location P-20 in May and potassium-40 was detected in all four bottom sediment samples and both shoreline sediment samples. There was no indication of any plant effect.

12 5.0 FIGURES AND TABLES

13 111A-Figure 5.1 Offsite Ambient Radiation (TLDs); average of inner and outer ring indicator locations versus control location.

10 11 12 13 14 15 16 17 18 19 20 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 mR/91 days Indicators 10 11 12 13 14 15 16 17 18 19 20 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 mR/91 days Control

14 111A-Figure 5.2 Airborne Particulates; analysis for gross beta, average mean of all indicator locations versus control location.

0.015 0.017 0.019 0.021 0.023 0.025 0.027 0.029 0.031 0.033 0.035 0.037 0.039 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 pCi/m3 Indicators (P-2,3,4,6,7)

Elevated due to construction activity 0.015 0.017 0.019 0.021 0.023 0.025 0.027 0.029 0.031 0.033 0.035 0.037 0.039 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 pCi/m3 Control (P-1)

15 111A-Location Collection Type and Analysis Type and Medium No.

Codes (and Type)a Frequencyb Frequencyc Ambient radiation (TLD's) 54 P-01A - P-10A C/Q Ambient gamma P-01B - P-15B P-01S - P-08S P-01IA - P-08IA P-01IB - P-08IB P-01IX-P-04IX, P-01C Airborne Particulates 6

P-1(C), P-2, C/W GB, GS (QC of P-3, P-4, P-6, P-7 each location)

Airborne Iodine 6

P-1(C), P-2, P-3, P-4, P-6, P-7 C/W I-131 River water 2

P-5(C), P-6 G/W GS(MC), H-3(QC)

Drinking water 1

P-11 G/W GB(MC), I-131(MC)

GS (MC), H-3 (QC)

Well water 5

P-6, P-8, P-9, P-24, G/Q H-3, GS P-43 (C)

Edible cultivated crops 0

P-30(C)

G/A GS (I-131)

Leafy green vegetables 3

P-8, P-24, P-38(C)

G/A GS (I-131)

Fish (three species, edible portion) 2 P-19(C), P-13 G/SA GS Periphyton or invertebrates 2

P-40(C), P-6 G/SA GS Bottom sediment 2

P-20(C), P-6 G/SA GS Shoreline sediment 1

P-12 G/SA GS a Location codes are defined in Table 5.2. Control stations are indicated by (C). All other stations are indicators.

b Collection type is coded as follows: C/ = continuous, G/ = grab. Collection frequency is coded as follows:

W= weekly, M = monthly, Q = quarterly, SA = semiannually, A = annually.

c Analysis type is coded as follows: GB = gross beta, GS = gamma spectroscopy, H-3 = tritium, I-131 = iodine-131.

Analysis frequency is coded as follows: MC = monthly composite, QC = quarterly composite.

Table 5.1. Sample collection and analysis program, Prairie Island Nuclear Generating Plant.

16 111A-Table 5.2. Sampling locations, Prairie Island Nuclear Generating Plant.

Distance and Direction Code Typea Collection Site Sample Typeb from Reactor P-1 C

Air Station P-1 AP, AI 11.8 mi @ 316o/NNW P-2 Air Station P-2 AP, AI 0.5 mi @ 294o/WNW P-3 Air Station P-3 AP, AI 0.8 mi @ 313o/NW P-4 Air Station P-4 AP, AI 0.4 mi @ 359o/N P-5 C

Upstream of Plant RW 1.8 mi @ 11o/N P-6 Lock and Dam #3 & Air Station P-6 AP, AI, RW WW, BS, BOc 1.6 mi @ 129o/SE P-7 P-8 P-9 P-11 P-12 Air Station P-7 Community Center Plant Well #2 Red Wing Service Center Downstream of Plant AP, AI WW WW DW SS 0.5 mi @ 271o/W 1.0 mi @ 321o/WNW 0.3 mi @ 306o/NW 3.3 mi @ 158o/SSE 3.0 mi @ 116o/ESE P-13 Downstream of Plant Fc 3.5 mi @ 113o/ESE P-19 C

Upstream of Plant Fc 1.3 mi @ 0o/N P-20 C

Upstream of Plant BS 0.9 mi @ 45o/NE P-24 Suter Residence WW 0.6 mi @ 158o/SSE P-28 Allyn Residence VE 1.0 mi @ 152o/SSE P-38 C

Cain Residence VE 14.2 mi @ 359o/N P-40 C

Upstream of Plant BOc 0.4 mi @ 0o/N P-43 C

Peterson Farm WW 13.9 mi. @ 355o/N General Area of the Site Boundary P-01A Property Line TLD 0.4 mi @ 359o/N P-02A Property Line TLD 0.3 mi @ 10o/N P-03A Property Line TLD 0.5 mi @ 183o/S P-04A Property Line TLD 0.4 mi @ 204o/SSW P-05A Property Line TLD 0.4 mi @ 225o/SW P-06A Property Line TLD 0.4 mi @ 249o/WSW P-07A Property Line TLD 0.4 mi @ 268o/W P-08A Property Line TLD 0.4 mi @ 291o/WNW P-09A Property Line TLD 0.7 mi @ 317o/NW P-10A Property Line TLD 0.5 mi @ 333o/NNW

17 111A-Table 5.2. Sampling locations, Prairie Island Nuclear Generating Plant (continued).

Distance and Direction Code Typea Collection Site Sample Typeb from Reactor Approximately 4 to 5 miles Distant from the Plant P-01B Thomas Killian Residence TLD 4.7 mi @ 355o/N P-02B Roy Kinneman Residence TLD 4.8 mi @ 17o/NNE P-03B Wayne Anderson Farm TLD 4.9 mi @ 46o/NE P-04B Nelson Drive (Road)

TLD 4.2 mi @ 61o/ENE P-05B County Road E and Coulee TLD 4.2 mi @ 102o/ESE P-06B William Hauschildt Residence TLD 4.4 mi @ 112o/ESE P-07B Red Wing Public Works TLD 4.7 mi @ 140o/SE P-08B David Wnuk Residence TLD 4.1 mi @ 165o/SSE P-09B Highway 19 South TLD 4.2 mi @ 187o/S P-10B Cannondale Farm TLD 4.9 mi @ 200o/SSW P-11B Wallace Weberg Farm TLD 4.5 mi @ 221o/SW P-12B Ray Gergen Farm TLD 4.6 mi @ 251o/WSW P-13B Thomas O'Rourke Farm TLD 4.4 mi @ 270o/W P-14B David J. Anderson Farm TLD 4.9 mi @ 306o/NW P-15B Holst Farms TLD 3.8 mi @ 345o/NNW Special Interest Locations P-01S Federal Lock & Dam #3 TLD 1.6 mi @ 129o/SE P-02S Charles Suter Residence TLD 0.5 mi @ 155o/SSE P-03S Carl Gustafson Farm TLD 2.2 mi @ 173o/S P-04S Richard Burt Residence TLD 2.0 mi @ 202o/SSW P-05S Kinney Store TLD 2.0 mi @ 270o/W P-06S Earl Flynn Farm TLD 2.5 mi @ 299o/WNW P-07S Indian Community TLD 0.7 mi @ 271o/W P-08S Indian Community TLD 0.7 mi @ 287o/WNW P-01C C

Robert Kinneman Farm TLD 11.1 mi @ 331o/NNW

18 111A-Table 5.2. Sampling locations, Prairie Island Nuclear Generating Plant (continued).

Distance and Direction Code Typea Collection Site Sample Typeb from ISFSI Center.

ISFSI Area Inside Earth Berm ISFSI Area Outside Earth Berm P-01IB ISFSI Berm Area TLD 340' @ 3o/N P-02IB ISFSI Berm Area TLD 380' @ 28o/NNE P-03IB ISFSI Berm Area TLD 560' @ 85o/E P-04IB ISFSI Berm Area TLD 590' @ 165o/SSE P-05IB ISFSI Berm Area TLD 690' @ 186o/S P-06IB ISFSI Berm Area TLD 720' @ 201o/SSW P-07IB ISFSI Berm Area TLD 610' @ 271o/W P-08IB ISFSI Berm Area TLD 360' @ 332o/NNW a "C" type denotes control location. All other locations are indicators.

b Sample Codes:

AP Airborne particulates F

Fish AI Airborne Iodine SS Shoreline Sediments BS Bottom (river) sediments SW Surface Water BO Bottom organisms VE Vegetation/vegetables (periphyton or macroinvertebrates)

WW Well water DW Drinking water c Distance and direction data for fish and bottom organisms are approximate since availability of sample specimen may vary at any one location.

P-01IA ISFSI Nuisance Fence TLD 190' @ 45o/NE P-02IA ISFSI Nuisance Fence TLD 360' @ 82o/E P-03IA ISFSI Nuisance Fence TLD 370' @ 100o/E P-04IA ISFSI Nuisance Fence TLD 200' @ 134o/SE P-05IA ISFSI Nuisance Fence TLD 180' @ 219o/SW P-06IA ISFSI Nuisance Fence TLD 320' @ 258o/WSW P-07IA ISFSI Nuisance Fence TLD 320' @ 281o/WNW P-08IA ISFSI Nuisance Fence TLD 190' @ 318o/NW P-01IX ISFSI Nuisance Fence TLD 140' @ 180o/S P-02IX ISFSI Nuisance Fence TLD 310' @ 270o/W P-03IX ISFSI Nuisance Fence TLD 140' @ 0o/N P-04IX ISFSI Nuisance Fence TLD 360' @ 90o/E

19 111A-Table 5.3. Missed collections and analyses at the Prairie Island Nuclear Generating Plant.

All required samples were collected and analyzed with the following exceptions:

Sample Type Analysis Location Collection Date or Period Reason for not Conducting REMP as Required Plan for Preventing Recurrence TLD Ambient Gamma P-05A, P-03B, P-06B, P-08B, P-09B, P-02S, P-04S, P-05S 10/1/24-12/31/24 TLDs were irradiated by an external source while in transit between Prairie Island Nuclear Plant and the TLD processing laboratory. These eight locations were identified by the facility-related dose calculation as exceeding the detectable dose.

Continue to label TLD shipments Do Not X-Ray

20 111A-Table 5.4 Radiological Environmental Monitoring Program Summary Name of Facility Prairie Island Nuclear Power Station Docket No.

50-282, 50-306 Location of Facility Goodhue, Minnesota Reporting Period January-December, 2024

( County, State )

Sample Type (Units)

Type and Number of Analysesa LLDb Indicator Locations Mean (F)c Rangec Location with Highest Annual Mean Control Locations Mean (F)c Rangec Number Non-Routine Resultse Locationd Mean (F)c Rangec Direct Radiation TLD (Inner Ring, Area at Site Boundary) mR/91 days)

Gamma 40 3.0 15.5 (40/40)

P-07A Property Line 17.9 (4/4)

(See Control 0

(8.7-20.8) 0.4 mi @ 268°/W (16.4-20.8) below.)

TLD (Outer Ring, 4-5 mi. distant) mR/91 days)

Gamma 60 3.0 15.3 (60/60)

P-04B, Nelson Drive (Road) 20.0 (4/4)

(See Control 0

(13.1-22.3) 4.2 mi @ 61°/ENE (17.6-22.3) below.)

TLD (Special Interest Areas) mR/91 days)

Gamma 32 3.0 16.1 (32/32)

P-03S, Gustafson Farm, 19.0 (4/4)

(See Control 0

(12.6-21.0) 2.2 mi @ 173°/S (17.0-21.0) below.)

TLD (Control) mR/91 days)

Gamma 4

3.0 None P-01C, Robert Kinneman 11.1 mi @ 331° /NNW 16.6 (4/4)

(14.9-17.8) 16.6 (4/4)

(14.9-17.8) 0 Airborne Pathway Airborne GB 312 0.005 0.029 (260/260)

(0.013-0.055)

P-3, Air Station 0.8 mi @ 313° /NW P-4, Air Station 0.4 mi. @ 359° /N

& P-6, Air Station 1.6 mi. @ 129° /SE 0.029 (52 /52)

(0.013-0.053) /

0.029 (52/52)

(0.014-0.053) /

0.029 (52/52)

(0.013-0.055) 0.027 (52/52)

(0.012-0.052) 0 Particulates GS 24 Be-7 0.015 0.067 (20/20)

P-6, Air Station 0.069 (4/4) 0.063 (4/4) 0 (0.031-0.089) 1.6 mi @ 129° /SE (0.037-0.083)

)

(0.038-0.082)

Mn-54 0.0007

< LLD

< LLD 0

Co-58 0.0007

< LLD

< LLD 0

Co-60 0.0008

< LLD

< LLD 0

Zn-65 0.0016

< LLD

< LLD 0

Zr-Nb-95 0.0012

< LLD

< LLD 0

Ru-103 0.0010

< LLD

< LLD 0

Ru-106 0.0056

< LLD

< LLD 0

Cs-134 0.0007

< LLD

< LLD 0

Cs-137 0.0007

< LLD

< LLD 0

Ba-La-140 0.0046

< LLD

< LLD 0

Ce-141 0.0017

< LLD

< LLD 0

Ce-144 0.0041

< LLD

< LLD 0

Airborne Iodine (pCi/m3)

I-131 312 0.030

< LLD

< LLD 0

21 111A-Table 5.4 Radiological Environmental Monitoring Program Summary Name of Facility Prairie Island Nuclear Power Station Docket No.

50-282, 50-306 Location of Facility Goodhue, Minnesota Reporting Period January-December, 2024

( County, State )

Sample Type (Units)

Type and Number of Analysesa LLDb Indicator Locations Mean (F)c Rangec Location with Highest Annual Mean Control Locations Mean (F)c Rangec Number Non-Routine Resultse Locationd Mean (F)c Rangec Terrestrial Pathway Crops - Cabbage (pCi/gwet)

I-131 3

0.007

< LLD

< LLD 0

Well Water H-3 20 183

< LLD

< LLD 0

(pCi/L)

GS 20 Mn-54 10

< LLD

< LLD 0

Fe-59 30

< LLD

< LLD 0

Co-58 10

< LLD

< LLD 0

Co-60 10

< LLD

< LLD 0

Zn-65 30

< LLD

< LLD 0

Zr-Nb-95 15

< LLD

< LLD 0

Cs-134 10

< LLD

< LLD 0

Cs-137 10

< LLD

< LLD 0

Ba-La-140 15

< LLD

< LLD 0

Ce-144 42

< LLD

< LLD 0

22 111A-Table 5.4 Radiological Environmental Monitoring Program Summary Name of Facility Prairie Island Nuclear Power Station Docket No.

50-282, 50-306 Location of Facility Goodhue, Minnesota

( County, state )

Reporting Period January-December, 2024 Sample Type (Units)

Type and Number of Analyses a LLDb Indicator Locations Mean (F)c Rangec Location with Highest Annual Mean Control Locations Mean (F)c Rangec Number Non-Routine Resultse Locationd Mean (F)c Rangec Waterborne Pathway Drinking Water GB 12 1.0 10.5 (12/12)

(7.2-14.0)

P-11, Red Wing S.C.

3.3 mi @ 158° /SSE 10.5 (12/12)

(7.2-14.0)

None 0

(pCi/L)

I-131 12 1.0

< LLD None 0

H-3 4

183

< LLD None 0

GS 12 Mn-54 10

< LLD None 0

Fe-59 30

< LLD None 0

Co-58 10

< LLD None 0

Co-60 10

< LLD None 0

Zn-65 30

< LLD None 0

Zr-Nb-95 15

< LLD None 0

Cs-134 10

< LLD None 0

Cs-137 10

< LLD None 0

Ba-La-140 15

< LLD None 0

Ce-144 50

< LLD None 0

River Water H-3 8 183 347 (1/4)

P-6, Lock and Dam #3 1.6 mi @ 129° /SE 347 (1/4)

< LLD 0

(pCi/L)

GS 24 Mn-54 10

< LLD

< LLD 0

Fe-59 30

< LLD

< LLD 0

Co-58 10

< LLD

< LLD 0

Co-60 10

< LLD

< LLD 0

Zn-65 30

< LLD

< LLD 0

Zr-Nb-95 15

< LLD

< LLD 0

Cs-134 10

< LLD

< LLD 0

Cs-137 10

< LLD

< LLD 0

Ba-La-140 15

< LLD

< LLD 0

Ce-144 51

< LLD

< LLD 0

Fish GS 12 (pCi/g wet)

K-40 0.10 3.01 (6/6)

(2.54-3.47)

P-19, Upstream 1.3 mi @ 0° /N 3.21 (6/6)

(2.90-4.25) 3.21 (6/6)

(2.90-4.25) 0 Mn-54 0.023

< LLD

< LLD 0

Fe-59 0.074

< LLD

< LLD 0

Co-58 0.029

< LLD

< LLD 0

Co-60 0.020

< LLD

< LLD 0

Zn-65 0.040

< LLD

< LLD 0

Zr-Nb-95 0.050

< LLD

< LLD 0

Cs-134 0.021

< LLD

< LLD 0

Cs-137 0.023

< LLD

< LLD 0

Ba-La-140 0.215

< LLD

< LLD 0

23 111A-Table 5.4 Radiological Environmental Monitoring Program Summary Name of Facility Prairie Island Nuclear Power Station Docket No.

50-282, 50-306 Location of Facility Goodhue, Minnesota Reporting Period January-December 2024

( County, State )

Sample Type (Units)

Type and Number of Analysesa LLDb Indicator Locations Mean (F)c Rangec Location with Highest Annual Mean Control Locations Mean (F)c Rangec Number Non-Routine Resultse Locationd Mean (F)c Rangec Waterborne Pathway Invertebrates GS 4

(pCi/g wet)

Be-7 0.552

< LLD

< LLD 0

K-40 0.37 3.48 (2/2)

P-6, Lock & Dam #3 3.48 (2/2) 3.25 (2/2) 0 (3.42-3.54) 1.6 mi @ 129° /SE (3.42-3.54)

(1.92-4.58)

Mn-54 0.055

< LLD

< LLD 0

Co-58 0.062

< LLD

< LLD 0

Co-60 0.058

< LLD

< LLD 0

Zn-65 0.117

< LLD

< LLD 0

Zr-Nb-95 0.075

< LLD

< LLD 0

Ru-103 0.064

< LLD

< LLD 0

Ru-106 0.455

< LLD

< LLD 0

Cs-134 0.051

< LLD

< LLD 0

Cs-137 0.052

< LLD

< LLD 0

Ba-La-140 0.260

< LLD

< LLD 0

Ce-141 0.100

< LLD

< LLD 0

Ce-144 0.274

< LLD

< LLD 0

Bottom and GS 6

83(1/2)

Shoreline

< lld Sediments Be-7 0.191

< LLD P-20, Upstream of Plant 0.9 mi @ 45° /NE 0.40 (1/2) 0.40 (1/2) 0 (pCi/g dry)

K-40 8.76 (4/4)

P-20, Upstream of Plant 10.33 (2/2) 10.33 (2/2) 0 (7.43-9.76) 0.9 mi @ 45° /NE (8.99-11.66)

(8.99-11.66)

Mn-54 0.024

< LLD*

< LLD 0

Co-58 0.019

< LLD

< LLD 0

Co-60 0.015

< LLD

< LLD 0

Zn-65 0.041

< LLD

< LLD 0

Zr-Nb-95 0.027

< LLD

< LLD 0

Ru-103 0.025

< LLD

< LLD 0

Ru-106 0.154

< LLD

< LLD 0

Cs-134 0.018

< LLD

< LLD 0

Cs-137 0.020

< LLD

< LLD 0

Ba-La-140 0.097

< LLD

< LLD 0

Ce-141 0.052

< LLD

< LLD 0

Ce-144 0.130

< LLD

< LLD 0

a GB = gross beta, GS = gamma scan.

b LLD = nominal lower limit of detection based on a 4.66 sigma counting error for background sample.

c Mean and range are based on detectable measurements only. Fraction of detectable measurements at specified locations is indicated in parentheses (F).

d Locations are specified: (1) by name, and/or station code and (2) by distance (miles) and direction relative to reactor site.

e Non-routine results are those which exceed ten times the control station value. If no control station value is available, the result is considered non-routine if it exceeds ten times the typical preoperational value for the medium or location.

24 111A-

6.0 REFERENCES

CITED Arnold, J. R. and H. A. Al-Salih. 1955. Beryllium-7 Produced by Cosmic Rays. Science 121: 451-453.

Eisenbud, M. 1963. Environmental Radioactivity, McGraw-Hill, New York, New York, pp. 213, 275 and 276.

Environmental, Inc., Midwest Laboratory.

2001a through 2021a. Radiation Environmental Monitoring for Monticello Nuclear Generating Plant, Complete Analysis Data Tables, January-December, 2000 through 2019.

2001b through 2023b. Radiation Environmental Monitoring for Prairie Island Nuclear Generating Plant, Complete Analysis Data Tables, January - December, 2000 through 2023.

1984a to 2000a. (formerly Teledyne Brown Engineering Environmental Services, Midwest Laboratory)

Radiation Environmental Monitoring for Monticello Nuclear Generating Plant, Complete Analysis Data Tables, January - December, 1983 through 1999.

1984b to 2000b. (formerly Teledyne Brown Engineering Environmental Services, Midwest Laboratory)

Radiation Environmental Monitoring for Prairie Island Nuclear Generating Plant, Complete Analysis Data Tables, January - December, 1983 through 1999.

1979a to 1983a. (formerly Hazleton Environmental Sciences Corporation) Radiation Environmental Monitoring for Monticello Nuclear Generating Plant, Complete Analysis Data Tables, January - December, 1978 through 1982.

1979b to 1983b. (formerly Hazleton Environmental Sciences Corporation) Radiation Environmental Monitoring for Prairie Island Nuclear Generating Plant, Complete Analysis Data Tables, January -

December, 1978 through 1982.

2022.

Quality Manual, Rev. 8, 17 October 2022.

2012.

Quality Assurance Program Manual, Rev. 3, 14 November 2012.

2022.

Quality Control Procedures Manual, Rev. 5, 9 May 2022.

2009.

Quality Control Program, Rev. 2, 12 November 2009.

Microbac Laboratories - Northbrook (Before June 1, 2023 Environmental Inc.)

_________2024.

Quality Manual, Rev 10, 28 October 2024 Gold, S., H. W. Barkhau, B. Shlein, and B. Kahn, 1964. Measurement of Naturally Occurring Radionuclides in Air, in the Natural Environment, University of Chicago Press, Chicago, Illinois, 369-382.

Northern States Power Company.

1972 through 1974. Prairie Island Nuclear Generating Plant, Environmental Monitoring and Ecological Studies Program, January 1, 1971 to December 31, 1971, 1972, 1973. Minneapolis, Minnesota.

1979 to 2008. Prairie Island Nuclear Generating Plant, Annual Radiation Environmental Monitoring Report to the U.S. Nuclear Regulatory Commission, January 1 to December 31, 1978 through 2007. Minneapolis, Minnesota.

Prairie Island Nuclear Generating Plant, 2024. Radiological Environmental Monitoring for Prairie Island Nuclear Generating Plant, Radiation Protection Implementing Procedures, 4700 series.

U.S. Dep't of Energy 1997 HASL-300, Edition 28, Procedures Manual, Environmental Measurements Laboratory, New York, NY.

25 111A-

6.0 REFERENCES

CITED (continued)

U.S. Environmental Protection Agency.

1980. Prescribed Procedures for Measurement of Radioactivity in Drinking Water, Cincinnati, Ohio (EPA-600/4-80-032).

1984. Eastern Environmental Radiation Facility, Radiochemistry Procedures Manual, Montgomery, Alabama (EPA-520/5-84-006).

2012. RadNet, formerly Environmental Radiation Ambient Monitoring System, Gross Beta in Air, Gross Beta in Drinking Water (MN) 1981-2009.

Wilson, D. W., G. M. Ward and J. E. Johnson. 1969. In Environmental Contamination by Radioactive Materials, International Atomic Energy Agency. p.125.

Xcel Energy Corporation.

2009 to 2023. Monticello Nuclear Generating Plant, Annual Radiological Environmental Monitoring Report to the U.S. Nuclear Regulatory Commission, January 1 to December 31, 2008 through 2023. Minneapolis, Minnesota.

2009 to 2023. Prairie Island Nuclear Generating Plant, Annual Radiological Environmental Monitoring Report to the U.S. Nuclear Regulatory Commission, January 1 to December 31, 2008 through 2023.

Minneapolis, Minnesota

NOTE:

Appendix A is updated four times a year. The complete appendix is included in March, June, September and December monthly progress reports only.

January, 2024 through December, 2024 APPENDIX A INTERLABORATORY AND INTRALABORATORY COMPARISON PROGRAM RESULTS

A-1 Microbac Laboratories - Northbrook (previously Environmental Inc.) has participated in interlaboratory comparison (crosscheck) programs since the formulation of its quality program in December 1971.

These programs are operated by agencies and/or companies which supply environmental sample types containing concentrations of radionuclides known to the issuing entity but not to participant laboratories.

The purpose of such a program is to provide an independent check on a laboratory's analytical procedures and to alert it of any possible problems.

Participant laboratories measure the concentration of specified radionuclides and report them to the issuing agency. Several months later, the agency reports the known values to the participant laboratories and specifies control limits. Results consistently higher or lower than the known values or outside the control limits indicate a need to check the instruments or procedures used.

Results in Table A-1 were obtained through participation in the RAD PT Study Proficiency Testing Program administered by Environmental Resource Associates, serving as a replacement for studies conducted previously by the U.S. EPA Environmental Monitoring Systems Laboratory, Las Vegas, Nevada.

Table A-2 lists results for thermoluminescent dosimeters (TLDs), via irradiation and evaluation by the University of Wisconsin-Madison Radiation Calibration Laboratory at the University of Wisconsin Medical Radiation Research Center.

Table A-3 lists results of the analyses on intralaboratory spiked samples for the past twelve months. All samples are prepared using NIST traceable sources. Data for previous years available upon request.

Table A-4 lists results of the analyses on intralaboratory blank samples for the past twelve months. Data for previous years available upon request.

Table A-5 lists analytical results from the intralaboratory duplicate program for the past twelve months. Acceptance is based on each result being within 25% of the mean of the two results or the two sigma uncertainties of each result overlap.

The results in Table A-6 were obtained through participation in the Mixed Analyte Performance Evaluation Program.

Results in Table A-7 were obtained through participation in the MRAD PT Study Proficiency Testing Program administered by Environmental Resource Associates, serving as a replacement for studies conducted previously by the Environmental Measurement Laboratory Quality Assessment Program (EML).

Attachment A lists the laboratory acceptance criteria for various analyses.

Out-of-limit results are explained directly below the result.

Appendix A Interlaboratory/ Intralaboratory Comparison Program Results

A-2 Analysis Ratio of lab result to known value.

Gamma Emitters 0.8 to 1.2 Strontium-89, 0.8 to 1.2 Strontium-90 Potassium-40 0.8 to 1.2 Gross alpha 0.5 to 1.5 Gross beta 0.8 to 1.2 Tritium 0.8 to 1.2 Radium-226, 0.7 to 1.3 Radium-228 Plutonium 0.8 to 1.2 Iodine-129, 0.8 to 1.2 Iodine-131 Nickel-63, 0.7 to 1.3 Technetium-99, Uranium-238 Iron-55 0.8 to 1.2 Other Analyses 0.8 to 1.2 Attachment A ACCEPTANCE CRITERIA FOR INTRALABORATORY SPIKED SAMPLES

A-3 TABLE A-1. Interlaboratory Comparison Crosscheck program, Environmental Resource Associates (ERA)a.

RAD study Lab Code Date Analysis ERA Value Acceptance RAD-022724M (study dates 2/27/24 - 3/11/24)

ERDW-323 10/7/2022 Ba-133 67.3 +/- 4.1 79.4 62.3 - 97.0 Pass ERDW-323 10/7/2022 Cs-134 20.6 +/- 2.6 30.5 18.2 - 42.8 Pass ERDW-323 10/7/2022 Cs-137 221 +/- 7 212 172 - 252 Pass ERDW-323 10/7/2022 Co-60 48.8 +/- 4.2 51.4 37.1 - 65.7 Pass ERDW-323 10/7/2022 Zn-65 82.6 +/- 9 216 167 - 265 Fail b ERDW-325 10/7/2022 Gr. Alpha 15.4 +/- 1.6 16.9 11.1 - 22.7 Pass ERDW-325 10/7/2022 G. Beta 48.2 +/- 1.4 53.0 39.1 - 66.9 Pass ERDW-321 10/7/2022 Ra-226 15.9 +/- 0.9 19.0 16.2 - 21.8 Fail c ERDW-321 10/7/2022 Ra-228 3.81 +/- 1.04 2.33 1.04 - 3.60 Fail d ERDW-321 10/7/2022 Uranium 8.745 +/- 1.070 8.53 7.10 - 10.0 Pass ERDW-327 4/10/2023 H-3 12,740 +/- 366 12,700 10,500 - 14,900 Pass RAD-137 Study (study dates 4/08/24 - 5/23/24)

ERDW-715 4/8/2024 Ba-133 71.2 +/- 5.5 65.9 50.1 - 81.7 Pass ERDW-715 4/8/2024 Cs-134 70.4 +/- 9.5 57.8 42.8 - 72.8 Pass ERDW-715 4/8/2024 Cs-137 188 +/- 11 186 149 - 233 Pass ERDW-715 4/8/2024 Co-60 100 +/- 10 98.8 79.7 - 118 Pass ERDW-715 4/8/2024 Zn-65 231 +/- 15 240 188 - 292 Pass ERDW-713 4/8/2024 Gr. Alpha 39.4 +/- 1.9 52.6 39.6 - 65.8 Fail e ERDW-713 4/8/2024 G. Beta 45.5 +/- 1.4 46.5 33.9 - 59.1 Pass ERDW-711 4/8/2024 Ra-226 14.3 +/- 0.8 13.4 11.10 - 15.7 Pass ERDW-711 4/8/2024 Ra-228 6.01 +/- 1.19 6.24 4.2 - 8.3 Pass ERDW-711 4/8/2024 Uranium 63.5 +/- 2.4 59.3 52.8 - 65.8 Pass ERDW-717 4/8/2024 H-3 20,400 +/- 448 21,300 18,200 - 24,400 Pass RAD-138 Study (study dates 7/08/24 - 8/22/24)

ERDW-1546 7/8/2024 Ba-133 41.4 +/- 5.9 38.2 25.2 - 51.2 Pass ERDW-1546 7/8/2024 Cs-134 18.6 +/- 8.0 18.9 7.81 - 30.0 Pass ERDW-1546 7/8/2024 Cs-137 54.4 +/- 13.3 57.0 32.9 - 81.1 Pass ERDW-1546 7/8/2024 Co-60 82.8 +/- 7.1 76.8 59.9 - 93.7 Pass ERDW-1546 7/8/2024 Zn-65 348 +/- 30 312 253 - 371 Pass ERDW-1548 7/8/2024 Gr. Alpha 9.05 +/- 1.26 13.0 7.94 - 18.1 Pass ERDW-1548 7/8/2024 G. Beta 17.3 +/- 1.0 20.6 13.2 - 28.0 Pass ERDW-1552 7/8/2024 Ra-226 20.4 +/- 1.0 17.2 14.6 - 19.8 Fail f ERDW-1552 7/8/2024 Ra-228 3.72 +/- 0.96 4.63 2.88 - 6.38 Pass ERDW-1552 7/8/2024 Uranium 36.2 +/- 2.4 36.8 32.5 - 41.1 Pass ERDW-1554 7/8/2024 H-3 7,840 +/- 290 7,550 5,870 - 9,230 Pass ERDW-1550 7/8/2024 I-131 20.1 +/- 0.9 27.9 24.2 - 31.6 Fail g a Results obtained by Microbac Laboratories Inc. - Northbrook as a participant in the crosscheck program for proficiency testing in drinking water conducted by Environmental Resource Associates (ERA).

b An incorrect reference date was used in the calculation of the gamma emitters. If the correct date was used, all analytes would have passed ERA acceptance criteria. The Zn-65 result would have been 212 +/- 30 pCi/L.

c No obvious conclusion could be determined for the low result. It's possible that a small leak from the radon bubbler may have allowed radon gas to escape thereby leading to the low result. Subsequent ERA study RAD-137 passed for Ra-226.

d The batch recovery value as determined by the EPA method could have been biased artificially low thereby causing the result to have a high bias outside the upper acceptance limit. Subsequent ERA studies RAD-137,138 passed for Ra-228.

e Data was reviewed but no obvious issue could be determined. Subsequent ERA study RAD-138 passed for both Gross Alpha and Gross Beta.

f The lab continues to investigate the Ra-226 performance issues. The procedure has been revised to more closely follow the EPA method. Results are being compiled and a subsequent ERA study will be ordered to validate the revised procedure.

g ERA added stable iodine carrier to the PT sample at a concentration of 0.20 mg/L. The calculation of the results that were submitted for this study did not take this added iodine into account when calculating the chemical yield or recovery.

Incorporating the ERA added stable iodine into the calculattions; recoveries dropped from 88.32% and 90.52% to 64.56% and 66.17%. The adjusted results are: 29.42 pCi/L and 28.06 pCi/L which are both within the acceptance range.

Concentration (pCi/L)

Laboratory Acceptance Result Limits

A-4 TABLE A-2. Thermoluminescent Dosimetry, (TLD, CaSO4: Dy Cards).a Lab Code Irradiation Delivered Reportedb Date Description Dose Dose Environmental, Inc.

Group 1 2024-25-1 1/6/2025 Spike 1 92.0 91.8 0.00 2024-25-1 1/6/2025 Spike 2 92.0 89.7

-0.03 2024-25-1 1/6/2025 Spike 3 92.0 92.0 0.00 2024-25-1 1/6/2025 Spike 4 92.0 92.9 0.01 2024-25-1 1/6/2025 Spike 5 92.0 91.8 0.00 2024-25-1 1/6/2025 Spike 6 92.0 98.0 0.07 2024-25-1 1/6/2025 Spike 7 92.0 94.6 0.03 2024-25-1 1/6/2025 Spike 8 92.0 94.2 0.02 2024-25-1 1/6/2025 Spike 9 92.0 95.4 0.04 2024-25-1 1/6/2025 Spike 10 92.0 91.3

-0.01 2024-25-1 1/6/2025 Spike 11 92.0 89.4

-0.03 2024-25-1 1/6/2025 Spike 12 92.0 97.7 0.06 2024-25-1 1/6/2025 Spike 13 92.0 94.1 0.02 2024-25-1 1/6/2025 Spike 14 92.0 92.2 0.00 2024-25-1 1/6/2025 Spike 15 92.0 92.9 0.01 2024-25-1 1/6/2025 Spike 16 92.0 91.7 0.00 2024-25-1 1/6/2025 Spike 17 92.0 87.4

-0.05 2024-25-1 1/6/2025 Spike 18 92.0 94.7 0.03 2024-25-1 1/6/2025 Spike 19 92.0 91.0

-0.01 2024-25-1 1/6/2025 Spike 20 92.0 92.5 0.01 Mean (Spike 1-20) 92.8 0.01 Passd Standard Deviation (Spike 1-20) 2.6 0.03 Passd a TLD's were irradiated by the University of Wisconsin-Madison Radiation Calibration Laboratory following ANSI N13.37 protocol from a known air kerma rate. TLD's were read and the results were submitted by Microbac Laboratories - Northbrook to the University of Wisconsin-Madison Radiation Calibration Laboratory for comparison to the delivered dose.

b Reported dose was converted from exposure (R) to Air Kerma (cGy) using a conversion of 0.876. Conversion from air kerma to ambient dose equivalent for Cs-137 at the reference dose point H*(10)Ka = 1.20. mrem/cGy = 1000.

c Performance Quotient (P) is calculated as ((reported dose - conventionally true value) ÷ conventionally true value) where the conventionally true value is the delivered dose.

d Acceptance is achieved when neither the absolute value of the mean of the P values, nor the standard deviation of the P values exceed 0.15.

mrem Performancec Quotient (P)

A-5 TABLE A-2. Thermoluminescent Dosimetry, (TLD, CaSO4: Dy Cards).a Lab Code Irradiation Delivered Reportedb Date Description Dose Dose Environmental, Inc.

Group 2 2024-25-2 1/6/2025 Spike 21 74.0 77.5 0.05 2024-25-2 1/6/2025 Spike 22 74.0 77.6 0.05 2024-25-2 1/6/2025 Spike 23 74.0 73.2

-0.01 2024-25-2 1/6/2025 Spike 24 74.0 75.4 0.02 2024-25-2 1/6/2025 Spike 25 74.0 75.3 0.02 2024-25-2 1/6/2025 Spike 26 74.0 77.8 0.05 2024-25-2 1/6/2025 Spike 27 74.0 73.1

-0.01 2024-25-2 1/6/2025 Spike 28 74.0 74.0 0.00 2024-25-2 1/6/2025 Spike 29 74.0 75.8 0.02 2024-25-2 1/6/2025 Spike 30 74.0 76.5 0.03 2024-25-2 1/6/2025 Spike 31 74.0 73.5

-0.01 2024-25-2 1/6/2025 Spike 32 74.0 75.5 0.02 2024-25-2 1/6/2025 Spike 33 74.0 76.5 0.03 2024-25-2 1/6/2025 Spike 34 74.0 76.4 0.03 2024-25-2 1/6/2025 Spike 35 74.0 75.1 0.01 2024-25-2 1/6/2025 Spike 36 74.0 72.8

-0.02 2024-25-2 1/6/2025 Spike 37 74.0 76.0 0.03 2024-25-2 1/6/2025 Spike 38 74.0 74.9 0.01 2024-25-2 1/6/2025 Spike 39 74.0 75.4 0.02 2024-25-2 1/6/2025 Spike 40 74.0 70.8

-0.04 Mean (Spike 21-40) 75.2 0.02 Passd Standard Deviation (Spike 21-40) 1.8 0.02 Passd a TLD's were irradiated by the University of Wisconsin-Madison Radiation Calibration Laboratory following ANSI N13.37 protocol from a known air kerma rate. TLD's were read and the results were submitted by Microbac Laboratories - Northbrook to the University of Wisconsin-Madison Radiation Calibration Laboratory for comparison to the delivered dose.

b Reported dose was converted from exposure (R) to Air Kerma (cGy) using a conversion of 0.876. Conversion from air kerma to ambient dose equivalent for Cs-137 at the reference dose point H*(10)Ka = 1.20. mrem/cGy = 1000.

c Performance Quotient (P) is calculated as ((reported dose - conventionally true value) ÷ conventionally true value) where the conventionally true value is the delivered dose.

d Acceptance is achieved when neither the absolute value of the mean of the P values, nor the standard deviation of the P values exceed 0.15.

mrem Performancec Quotient (P)

A-6 TABLE A-3. Intralaboratory "Spiked" Samples Lab Codeb Reference Analysis Known Ratio Date Activity Acceptance Lab/Known SPDW-60025 1/12/2024 Gr. Alpha 43.3 +/- 2.4 47.9 24.0 - 57.5 Pass 0.90 SPDW-60025 1/12/2024 Gr. Beta 28.9 +/- 1.3 28.6 22.9 - 34.3 Pass 1.01 SPDW-60042 2/2/2024 H-3 21,225 459 22,100 17,680 - 26,520 Pass 0.96 SPDW-60059 2/14/2024 Gr. Alpha 37.6 +/- 2.8 32.2 16.1 - 38.6 Pass 1.17 SPDW-60059 2/14/2024 Gr. Beta 168 +/- 3 160 128.0 - 192.0 Pass 1.05 SPDW-60067 2/13/2024 H-3 20,925 451 22,100 17,680 - 26,520 Pass 0.95 SPDW-60097 2/28/2024 Gr. Alpha 27.7 +/- 2.1 32.2 16.1 - 38.6 Pass 0.86 SPDW-60097 2/28/2024 Gr. Beta 160 +/- 3 160 128.0 - 192.0 Pass 1.00 SPDW-60100 2/26/2024 H-3 21,582 +/- 462 22,100 17,680 - 26,520 Pass 0.98 SPDW-60016 3/7/2024 H-3 20,572 +/- 449 22,100 17,680 - 26,520 Pass 0.93 SPDW-60133 3/14/2024 Gr. Alpha 23.6 +/- 2.1 32.2 16.1 - 38.6 Pass 0.73 SPDW-60133 3/14/2024 Gr. Beta 171 +/- 3 160 128.0 - 192.0 Pass 1.07 SPDW-60150 3/22/2024 H-3 20,618 +/- 450 22,100 17,680 - 26,520 Pass 0.93 SPDW-60191 3/21/2024 Ra-226 13.2 +/- 0.4 12.3 8.6 - 16.0 Pass 1.07 SPDW-60154 3/25/2024 Ra-228 12.7 +/- 1.6 15.4 10.8 - 20.0 Pass 0.82 LCS-W-052924 4/8/2024 Ba-133 55.7 +/- 4.3 65.9 52.7 - 79.1 Pass 0.85 LCS-W-052924 4/8/2024 Cs-134 50.1 +/- 3.4 57.8 46.2 - 69.4 Pass 0.87 LCS-W-052924 4/8/2024 Cs-137 172 +/- 6 186 149 - 223 Pass 0.92 LCS-W-052924 4/8/2024 Co-60 95.3 +/- 4.0 99 79.0 - 119 Pass 0.96 LCS-W-052924 4/8/2024 Zn-65 224 +/- 12 240 192 - 288 Pass 0.93 SPDW-60184 4/9/2024 Gr. Alpha 21.0 +/- 2.0 32.2 16.1 - 38.6 Pass 0.65 SPDW-60184 4/9/2024 Gr. Beta 158 +/- 3 160 128.0 - 192.0 Pass 0.99 SPDW-60198 4/15/2024 H-3 20,822 +/- 453 22,100 17,680 - 26,520 Pass 0.94 SPDW-60213 4/25/2024 Ra-228 15.4 +/- 2.0 15.3 10.7 - 19.9 Pass 1.01 SPDW-60215 4/26/2024 H-3 20,400 +/- 447 22,100 17,680 - 26,520 Pass 0.92 SPDW-60267 4/11/2024 Ra-226 10.8 +/- 0.3 12.3 8.6 - 16.0 Pass 0.88 SPDW-60236 5/10/2024 H-3 20,415 +/- 448 22,100 17,680 - 26,520 Pass 0.92 SPDW-60253 5/16/2024 Ra-228 13.6 +/- 1.8 15.3 10.7 - 19.9 Pass 0.89 SPDW-60302 5/29/2024 Gr. Alpha 18.1 +/- 1.7 32.2 16.1 - 38.6 Pass 0.56 SPDW-60302 5/29/2024 Gr. Beta 163 +/- 3 160 128 - 192 Pass 1.02 SPDW-60307 5/23/2024 Ra-226 13.0 +/- 0.5 12.3 8.6 - 16.0 Pass 1.05 SPDW-60294 5/28/2024 H-3 20,840 +/- 463 22,100 17,680 - 26,520 Pass 0.94 SPDW-60314 6/6/2024 Ra-228 11.9 +/- 1.6 15.3 10.7 - 19.9 Pass 0.78 SPDW-60331 6/10/2024 H-3 20,602 +/- 459 22,100 17,680 - 26,520 Pass 0.93 SPDW-60357 5/30/2024 Ra-226 11.8 +/- 0.4 12.3 8.6 - 16.0 Pass 0.96 SPDW-60361 6/27/2024 Gr. Alpha 21.7 +/- 2.0 32.2 16.1 - 38.6 Pass 0.67 SPDW-60361 6/27/2024 Gr. Beta 151 +/- 2 160 128 +/- 192 Pass 0.94 SPDW-60425 6/24/2024 Ra-226 12.8 +/- 0.4 12.3 8.6 - 16.0 Pass 1.04 SPDW-60393 7/10/2024 H-3 20,368 +/- 454 22,100 17,680 - 26,520 Pass 0.92 a Liquid sample results are reported in pCi/Liter, air filters ( pCi/m3), charcoal (pCi/charcoal canister), and solid samples (pCi/kg).

b Laboratory codes : W & SPW (Water), MI (milk), AP (air filter), SO (soil), VE (vegetation), CH (charcoal canister), F (fish), U (urine).

c Results are based on single determinations.

d Acceptance criteria are listed in Attachment A of this report.

Concentrationa Laboratory results Control 2s, n=1c Limitsd

A-7 TABLE A-3. Intralaboratory "Spiked" Samples Lab Codeb Reference Analysis Known Ratio Date Activity Acceptance Lab/Known SPDW-60411 7/22/2024 Gr. Alpha 18.2 +/- 1.9 32.2 16.1 - 38.6 Pass 0.57 SPDW-60411 7/22/2024 Gr. Beta 155 +/- 3 160 128 - 192 Pass 0.97 SPDW-60417 7/23/2024 U (Natural) 8.14 +/- 0.92 7.36 5.15 - 9.57 Pass 1.11 SPDW-60452 7/31/2024 Ra-226 11.5 +/- 0.4 12.3 8.6 - 16.0 Pass 0.93 SPDW-60530 8/12/2024 Ra-226 12.3 +/- 0.4 12.3 8.6 - 16.0 Pass 1.00 LCS-08/26/24 7/8/2024 Ba-133 31.2 +/- 4.3 38.2 30.6 - 45.8 Pass 0.82 LCS-08/26/24 7/8/2024 Cs-134 22.0 +/- 3.0 18.9 15.1 - 22.7 Pass 1.16 LCS-08/26/24 7/8/2024 Cs-137 68.0 +/- 6.5 57.0 45.6 - 68.4 Pass 1.19 LCS-08/26/24 7/8/2024 Co-60 80.8 +/- 5.0 76.8 61.4 - 92.2 Pass 1.05 LCS-08/26/24 7/8/2024 Zn-65 337 +/- 15 312 250 - 374 Pass 1.08 LCS-S-09/04/24 3/19/2018 Ac-228 1,122 +/- 120 1,240 992 - 1,488 Pass 0.90 LCS-S-09/04/24 3/19/2018 Bi-212 1,105 +/- 293 1,240 992 - 1,488 Pass 0.89 LCS-S-09/04/24 3/19/2018 Bi-214 1,563 +/- 49 1,760 1,408 - 2,112 Pass 0.89 LCS-S-09/04/24 3/19/2018 Co-60 7,251 +/- 94 8,060 6,448 - 9,672 Pass 0.90 LCS-S-09/04/24 3/19/2018 Pb-214 1,489 +/- 54 1,850 1,480 - 2,220 Pass 0.80 SPDW-60527 9/10/2024 H-3 20,297 +/- 453 22,100 17,680 - 26,520 Pass 0.92 SPDW-60546 9/13/2024 S-90 15.9 +/- 1.0 15.4 12.3 - 18.5 Pass 1.03 SPDW-60559 9/25/2024 Gr. Alpha 7.5 +/- 1.1 13.0 6.5 - 15.6 Pass 0.58 SPDW-60559 9/25/2024 Gr. Beta 21.5 +/- 1.3 20.6 16.5 - 24.7 Pass 1.04 SPDW-60584 10/9/2024 H-3 20,016 +/- 452 22,100 17,680 - 26,520 Pass 0.91 LCS-W-090324 4/8/2024 Ba-133 65.5 +/- 5.8 65.9 53 - 79 Pass 0.99 LCS-W-090324 4/8/2024 Cs-134 54.5 +/- 5.1 57.8 46 - 69 Pass 0.94 LCS-W-090324 4/8/2024 Cs-137 189 +/- 12 186 149 - 223 Pass 1.02 LCS-W-090324 4/8/2024 Co-60 101 +/- 9 98.8 79 - 119 Pass 1.02 LCS-W-090324 4/8/2024 Zn-65 260 +/- 25 240 192 - 288 Pass 1.08 LCS-W-10/03/24 8/1/2023 Cs-134 288 +/- 5 305 244 - 366 Pass 0.94 LCS-W-10/03/24 8/1/2023 Cs-137 257 +/- 8 235 188 - 282 Pass 1.09 LCS-W-10/03/24 8/1/2023 Co-57 550 +/- 16 521 417 - 625 Pass 1.06 LCS-W-10/03/24 8/1/2023 Mn-54 364 +/- 16 343 274 - 412 Pass 1.06 LCS-W-10/03/24 8/1/2023 Zn-65 489 +/- 28 516 413 - 619 Pass 0.95 LCS-W-10/05/24 7/12/2021 Ba-133 42.5 +/- 3.5 45.5 36 - 55 Pass 0.93 LCS-W-10/05/24 7/12/2021 Cs-134 88.1 +/- 6.2 87.5 70 - 105 Pass 1.01 LCS-W-10/05/24 7/12/2021 Cs-137 219 +/- 6 208 166 - 250 Pass 1.05 LCS-W-10/05/24 7/12/2021 Co-60 88.8 +/- 5.1 87.1 70 - 105 Pass 1.02 LCS-AP-10/05/24 8/1/2022 Cs-137 52.1 +/- 2.0 47.5 38 - 57 Pass 1.10 LCS-AP-10/05/24 8/1/2022 Co-57 99.8 +/- 6.5 94.5 76 - 113 Pass 1.06 LCS-AP-10/05/24 8/1/2022 Co-60 59.9 +/- 2.1 57.0 46 - 68 Pass 1.05 LCS-AP-10/05/24 8/1/2022 Mn-54 61.2 +/- 7.7 58.9 47 - 71 Pass 1.04 LCS-AP-10/05/24 8/1/2022 Zn-65 43.1 +/- 13.5 49.4 40 - 59 Pass 0.87 a Liquid sample results are reported in pCi/Liter, air filters ( pCi/m3), charcoal (pCi/charcoal canister), and solid samples (pCi/kg).

b Laboratory codes : W & SPW (Water), MI (milk), AP (air filter), SO (soil), VE (vegetation), CH (charcoal canister), F (fish), U (urine).

c Results are based on single determinations.

d Acceptance criteria are listed in Attachment A of this report.

Concentrationa Laboratory results Control 2s, n=1c Limitsd

A-8 TABLE A-3. Intralaboratory "Spiked" Samples Lab Codeb Reference Analysis Known Ratio Date Activity Acceptance Lab/Known LCS-S-092424 3/19/2018 K-40 9,021 +/- 385 10,600 8,480 - 12720 Pass 0.85 LCS-S-092424 3/19/2018 Cs-134 4,450 +/- 235 5,330 4,264 - 6396 Pass 0.83 LCS-S-092424 3/19/2018 Cs-137 3,773 +/- 55 4,210 3,368 - 5052 Pass 0.90 LCS-S-092424 3/19/2018 Co-60 6,958 +/- 96 8,060 6,448 - 9672 Pass 0.86 LCS-S-092424 3/19/2018 Pb-214 1,638 +/- 59 1,850 1,480 - 2220 Pass 0.89 LCS-S-092424 3/19/2018 Bi-214 1,608 +/- 50 1,760 1,408 - 2112 Pass 0.91 LCS-S-092424 3/19/2018 Ac-228 1,105 +/- 117 1,240 992 - 1488 Pass 0.89 LCS-S-101424 2/1/2024 Co-60 15,340 +/- 87 17,820 14,256 - 21,384 Pass 0.86 LCS-S-101424 2/1/2024 Cs-134 8,700 +/- 62 8,694 6,955 - 10,433 Pass 1.00 LCS-S-101424 2/1/2024 Cs-137 37,330 +/- 26 41,850 33,480 - 50,220 Pass 0.89 LCS-S-101424 2/1/2024 K-40 11,550 +/- 411 13,095 10,476 - 15,714 Pass 0.88 LCS-S-101424 2/1/2024 Mn-54 8,080 +/- 125 8,964 7,171 - 10,757 Pass 0.90 LCS-S-101424 2/1/2024 Zn-65 16,260 +/- 273 18,981 15,185 - 22,777 Pass 0.86 LCS-W-1014224 2/1/2024 Co-57 544 +/- 24 554 443 - 664 Pass 0.98 LCS-W-1014224 2/1/2024 Cs-134 281 +/- 8 289 231 - 347 Pass 0.97 LCS-W-1014224 2/1/2024 Cs-137 254 +/- 11 257 205 - 308 Pass 0.99 LCS-W-1014224 2/1/2024 Mn-54 369 +/- 21 365 292 - 437 Pass 1.01 LCS-W-1014224 2/1/2024 Zn-65 501 +/- 38 489 391 - 586 Pass 1.03 LCS-VE-100524 2/1/2024 Co-57 544 +/- 5 521 417 - 625 Pass 1.04 LCS-VE-100524 2/1/2024 Cs-134 281 +/- 8 305 244 - 366 Pass 0.92 LCS-VE-100524 2/1/2024 Cs-137 254 +/- 11 235 188 - 282 Pass 1.08 LCS-VE-100524 2/1/2024 Zn-65 501 +/- 38 516 413 - 619 Pass 0.97 LCS-VE-100524 2/1/2024 Mn-54 369 +/- 21 343 274 - 411 Pass 1.08 SPDW-60583 10/9/2024 H-3 20,016 +/- 452 22,100 17,680 - 26,520 Pass 0.91 SPDW-60604 10/25/2024 H-3 19,814 +/- 447 22,100 17,680 - 26,520 Pass 0.90 SPDW-60622 11/14/2024 Gr. Alpha 12.5 +/- 2.9 13.0 6.5 - 15.6 Pass 0.96 SPDW-60622 11/14/2024 Gr. Beta 17.8 +/- 2.3 20.6 16.5 - 24.7 Pass 0.86 SPDW-60635 10/10/2024 Ra-226 14.9 +/- 0.5 12.3 8.6 - 16.0 Pass 1.21 SPDW-60631 12/2/2024 H-3 20,384 +/- 453 22,100 17,680 - 26,520 Pass 0.92 SPDW-60641 12/17/2024 H-3 21,520 +/- 468 22,100 17,680 - 26,520 Pass 0.97 a Liquid sample results are reported in pCi/Liter, air filters ( pCi/m3), charcoal (pCi/charcoal canister), and solid samples (pCi/kg).

vegetation (pCi/sample) b Laboratory codes : W & SPW (Water), MI (milk), AP (air filter), SO (soil), VE (vegetation), CH (charcoal canister), F (fish), U (urine).

c Results are based on single determinations.

d Acceptance criteria are listed in Attachment A of this report.

Concentrationa Laboratory results Control 2s, n=1c Limitsd

A-9 TABLE A-4. Intralaboratory "Blank" Samples Lab Codeb Sample Collection Analysisc Type Date LLD SPDW-60024 Water 1/12/2024 Gr. Alpha 0.70 0.14 +/- 0.50 2

SPDW-60024 Water 1/12/2024 Gr. Beta 0.83

-0.60 +/- 0.56 4

SPW-3913 Water 2/2/2024 Tc-99 11.8

-12.3 +/- 7.0 200 SPDW-60041 Water 2/2/2024 H-3 177 68 +/- 96 200 SPDW-60058 Water 2/14/2024 Gr. Alpha 0.51

-0.10 +/- 0.35 2

SPDW-60058 Water 2/14/2024 Gr. Beta 0.71 0.19 +/- 0.50 4

SPDW-60147 Water 2/21/2024 Ra-226 0.04 0.18 +/- 0.03 2

SPDW-60099 Water 2/26/2024 H-3 179

-89 +/- 84 200 SPDW-60097 Water 2/28/2024 Gr. Alpha 0.53 0.29 +/- 0.39 2

SPDW-60097 Water 2/28/2024 Gr. Beta 0.79

-0.42 +/- 0.54 4

SPDW-60141 Water 3/19/2024 I-131 0.18

-0.10 +/- 0.10 1

SPDW-60149 Water 3/22/2024 H-3 174

-2 +/- 86 200 SPDW-60115 Water 3/7/2024 H-3 175 20 +/- 85 200 SPDW-60129 Water 3/11/2024 Ra-228 0.74 0.07 +/- 0.35 2

SPDW-60132 Water 3/14/2024 Gr. Alpha 0.51

-0.20 +/- 0.34 2

SPDW-60132 Water 3/14/2024 Gr. Beta 0.75

-0.07 +/- 0.52 4

SPDW-60190 Water 3/21/2024 Ra-226 0.04

-0.14 +/- 0.03 2

SPDW-60155 Water 3/25/2024 Ra-228 1.46

-0.13 +/- 0.66 2

SPDW-60183 Water 4/9/2024 Gr. Alpha 0.66

-0.09 +/- 0.46 2

SPDW-60183 Water 4/9/2024 Gr. Beta 0.76 0.11 +/- 0.54 4

SPDW-60266 Water 4/11/2024 Ra-226 0.04

-0.15 +/- 0.03 2

SPDW-60197 Water 4/15/2024 H-3 174 53 +/- 84 200 SPDW-60212 Water 4/25/2024 Ra-228 0.90 0.03 +/- 0.42 2

SPDW-60214 Water 4/26/2024 H-3 170 27 +/- 80 200 SPDW-60235 Water 5/10/2024 H-3 174

-7 +/- 81 200 SPDW-60252 Water 5/16/2024 Ra-228 0.68 0.72 +/- 0.39 2

SPDW-60294 Water 5/28/2024 H-3 188

-43 +/- 88 200 SPDW-60295 Water 5/28/2024 Sr-89 0.62 0.16 +/- 0.44 5

SPDW-60295 Water 5/28/2024 Sr-90 0.66

-0.20 +/- 0.28 1

SPDW-60301 Water 5/29/2024 Gr. Alpha 0.49

-0.16 +/- 0.33 2

SPDW-60301 Water 5/29/2024 Gr. Beta 0.76 0.14 +/- 0.54 4

SPDW-60306 Water 5/23/2024 Ra-228 0.17

-0.30 +/- 0.38 2

SPDW-60356 Water 5/30/2024 Ra-226 0.04 0.12 +/- 0.03 2

SPDW-60313 Water 6/6/2024 Ra-228 0.76

-0.01 +/- 0.35 2

SPDW-60330 Water 6/10/2024 H-3 183 12 +/- 85 200 SPDW-60340 Water 6/17/2024 I-131 0.15

-0.04 +/- 0.08 1

SPDW-60360 Water 6/27/2024 Gr. Alpha 0.46

-0.12 +/- 0.31 2

SPDW-60360 Water 6/27/2024 Gr. Beta 0.75 0.10 +/- 0.53 4

SPDW-60424 Water 6/24/2024 Ra-226 0.04

-0.14 +/- 0.09 2

a Liquid sample results are reported in pCi/Liter, air filters ( pCi/m3), charcoal (pCi/charcoal canister), and solid samples (pCi/g).

b Laboratory codes : W & SPW (Water), MI (milk), AP (air filter), SO (soil), VE (vegetation), CH (charcoal canister), F (fish), U (urine).

c I-131(G); iodine-131 as analyzed by gamma spectroscopy.

d Activity reported is a net activity result.

Concentrationa Laboratory results (4.66s)

Acceptance Activityd Criteria (4.66 s)

A-10 TABLE A-4. Intralaboratory "Blank" Samples Lab Codeb Sample Collection Analysisc Type Date LLD SPDW-60392 Water 7/10/2024 H-3 183

-28 +/- 83 200 SPDW-60411 Water 7/22/2024 Gr. Alpha 0.42

-0.06 +/- 0.29 2

SPDW-60411 Water 7/22/2024 Gr. Beta 0.71 0.40 +/- 0.51 4

SPDW-60416 Water 7/23/2024 U (Natural) 0.56

-0.16 +/- 0.66 1

SPDW-60418 Water 7/24/2024 Ra-228 0.65 0.93 +/- 0.40 2

SPDW-60451 Water 7/31/2024 Ra-226 0.07 0.02 +/- 0.06 2

SPW-1901 Water 8/6/2024 Ni-63 87

-144 +/- 51 200 SPDW-60462 Water 8/16/2024 Ra-228 0.58 0.08 +/- 0.28 2

SPDW-60529 Water 8/12/2024 Ra-226 0.04

-0.07 +/- 0.03 2

SPDW-60522 Water 9/5/2024 I-131 0.11

-0.09 +/- 0.07 1

SPDW-60526 Water 9/10/2024 H-3 183 9 +/- 86 200 SPDW-60592 Water 9/11/2024 Ra-226 0.06

-0.11 +/- 0.05 2

SPDW-60545 Water 9/13/2024 Sr-89 0.56

-0.06 +/- 0.43 5

SPDW-60545 Water 9/13/2024 Sr-90 0.52 0.06 +/- 0.25 1

SPDW-60560 Water 9/26/2024 H-3 180 88 +/- 89 200 SPDW-60594 Water 10/16/2024 Ra-228 0.73 0.43 +/- 0.39 2

SPDW-60634 Water 10/10/2024 Ra-226 0.05

-0.07 +/- 0.04 2

MB-102124 Water 10/21/2024 Co-57 4.76 0.87 +/- 2.53 10 MB-102124 Water 10/21/2024 Cs-134 3.88

-3.36 +/- 2.68 10 MB-102124 Water 10/21/2024 Cs-137 5.73 1.08 +/- 2.64 10 MB-102124 Water 10/21/2024 Mn-54 5.17 0.03 +/- 2.65 10 MB-102124 Water 10/21/2024 Zn-65 6.83

-1.76 +/- 5.61 10 SPDW-60614 Water 11/8/2024 H-3 185

-29 +/- 84 200 SPDW-60630 Water 12/2/2024 H-3 184

-12 +/- 86 200 MB-120924 Water 12/9/2024 Co-57 1.08 0.04 +/- 0.66 10 MB-120924 Water 12/9/2024 Cs-134 1.06 0.22 +/- 0.61 10 MB-120924 Water 12/9/2024 Cs-137 1.39 0.65 +/- 0.68 10 MB-120924 Water 12/9/2024 Mn-54 0.93 0.07 +/- 0.55 10 MB-120924 Water 12/9/2024 Zn-65 2.28 0.33 +/- 1.12 10 MB-121224 Water 12/12/2024 Co-57 1.56

-1.64 +/- 1.28 10 MB-121224 Water 12/12/2024 Cs-134 1.85

-2.84 +/- 1.36 10 MB-121224 Water 12/12/2024 Cs-137 1.39

-0.10 +/- 1.44 10 MB-121224 Water 12/12/2024 Mn-54 2.56 1.81 +/- 1.30 10 MB-121224 Water 12/12/2024 Zn-65 3.05

-6.22 +/- 2.99 10 SPDW-60638 Water 12/12/2024 I-131 0.17

-0.19 +/- 0.08 1

SPDW-60641 Water 12/17/2024 H-3 182 3 +/- 85 200 a Liquid sample results are reported in pCi/Liter, air filters ( pCi/m3), charcoal (pCi/charcoal canister), and solid samples (pCi/g).

b Laboratory codes : W & SPW (Water), MI (milk), AP (air filter), SO (soil), VE (vegetation), CH (charcoal canister), F (fish), U (urine).

c I-131(G); iodine-131 as analyzed by gamma spectroscopy.

d Activity reported is a net activity result.

Concentrationa Laboratory results (4.66s)

Acceptance Activityd Criteria (4.66 s)

A-11 TABLE A-5. Intralaboratory "Duplicate" Samples Collection Lab Codeb Date Analysis Acceptance DW-60006 1/5/2024 Gr. Alpha 2.03 +/- 0.83 1.59 +/- 0.83 1.81 +/- 0.59 Pass DW-60006 1/5/2024 Gr. Beta 1.36 +/- 0.58 1.22 +/- 0.62 1.29 +/- 0.42 Pass W-41 1/5/2024 Ra-226 1.67 +/- 0.35 1.03 +/- 0.35 1.35 +/- 0.25 Pass W-41 1/5/2024 Ra-228 4.19 +/- 0.85 3.45 +/- 0.83 3.82 +/- 0.59 Pass W-62 1/8/2024 Ra-226 0.54 +/- 0.30 0.12 +/- 0.41 0.33 +/- 0.25 Pass DW-60018 1/16/2024 Gr. Alpha 1.75 +/- 0.74 0.98 +/- 0.80 1.37 +/- 0.54 Pass W-125,126 1/16/2024 Ra-226 0.37 +/- 0.18 0.66 +/- 0.27 0.52 +/- 0.16 Pass DW-60034,60035 1/29/2024 Gr. Alpha 2.10 +/- 0.74 1.41 +/- 0.79 1.76 +/- 0.54 Pass DW-60034,60035 1/29/2024 Gr. Beta 1.13 +/- 0.57 0.57 +/- 0.57 0.85 +/- 0.40 Pass DW-60049,60050 2/5/2024 Gr. Alpha 0.61 +/- 1.02 1.20 +/- 0.87 0.90 +/- 0.67 Pass DW-60049,60050 2/5/2024 Gr. Beta 0.99 +/- 0.64 1.19 +/- 0.07 1.09 +/- 0.32 Pass DW-60054,60055 2/8/2024 Gr. Beta 0.25 +/- 0.53 0.62 +/- 0.61 0.44 +/- 0.40 Pass DW-60071,60072 2/16/2024 Ra-226 2.33 +/- 0.21 1.73 +/- 0.17 2.03 +/- 0.14 Pass DW-60071,60072 2/16/2024 Ra-228 0.48 +/- 0.42 0.60 +/- 0.45 0.54 +/- 0.31 Pass DW-60107,60108 3/2/2024 Gr. Alpha 1.26 +/- 0.98 1.59 +/- 0.99 1.42 +/- 0.70 Pass DW-60107,60108 3/2/2024 Gr. Beta 0.63 +/- 0.57 0.14 +/- 0.59 0.38 +/- 0.41 Pass DW-60120,60121 3/8/2024 Gr. Beta 1.15 +/- 0.56 1.04 +/- 0.58 1.10 +/- 0.40 Pass LW-582,583 3/19/2024 Be-7 3.80 +/- 0.70 1.76 +/- 0.60 2.78 +/- 0.46 Pass SWT-708,709 3/26/2024 H-3 186 +/- 90 136 +/- 87 161 +/- 62 Pass SW-624,625 4/2/2024 H-3 1,174 +/- 133 1,302 +/- 138 1,238 +/- 96 Pass AP-865,866 4/3/2024 Be-7 0.040 +/- 0.007 0.053 +/- 0.008 0.047 +/- 0.005 Pass DW-60180,60181 4/5/2024 Ra-226 0.97 +/- 0.25 1.30 +/- 0.21 1.135 +/- 0.16 Pass DW-60180,60181 4/5/2024 Ra-228 0.85 +/- 0.48 1.34 +/- 0.54 1.095 +/- 0.36 Pass WW-949,950 4/16/2024 H-3 229 +/- 94 136 +/- 90 183 +/- 65 Pass S-886,887 4/18/2024 Pb-214 0.93 +/- 0.04 0.94 +/- 0.04 0.93 +/- 0.03 Pass S-886,887 4/18/2024 Ac-228 0.82 +/- 0.08 0.83 +/- 0.06 0.82 +/- 0.05 Pass DW-60206,60207 4/19/2024 Ra-226 2.35 +/- 0.27 3.49 +/- 0.25 2.92 +/- 0.18 Pass DW-60203,60204 4/19/2024 Gr. Alpha 2.12 +/- 0.64 1.74 +/- 0.73 1.93 +/- 0.49 Pass DW-60206,60207 4/19/2024 Ra-228 0.50 +/- 0.59

-0.21 +/- 0.53 0.15 +/- 0.40 Pass WW-1075,1076 4/30/2024 H-3 278 +/- 107 311 +/- 109 294 +/- 76 Pass SG-1017,1018 5/1/2024 Gr. Alpha 27.2 +/- 4.00 32.0 +/- 4.00 29.6 +/- 2.83 Pass SG-1017,1018 5/1/2024 Gr. Beta 25.7 +/- 1.80 24.5 +/- 1.90 25.1 +/- 1.31 Pass SG-1017,1018 5/1/2024 Pb-214 3.28 +/- 0.14 4.61 +/- 0.11 3.95 +/- 0.09 Pass SG-1017,1018 5/1/2024 Ac-228 4.86 +/- 0.18 4.98 +/- 0.37 4.92 +/- 0.21 Pass DW-60273,60274 5/21/2024 Ra-228 2.12 +/- 0.63 1.33 +/- 0.45 1.73 +/- 0.39 Pass XW-1138,1139 5/31/2024 H-3 732 +/- 124 688 +/- 122 710 +/- 87 Pass Concentrationa Averaged First Result Second Result Result

A-12 TABLE A-5. Intralaboratory "Duplicate" Samples Collection Lab Codeb Date Analysis Acceptance AP-060324A,B 6/3/2024 Gr. Beta 0.021 +/- 0.005 0.018 +/- 0.005 0.020 +/- 0.003 Pass AP-061224A,B 6/12/2024 Gr. Beta 0.009 +/- 0.003 0.011 +/- 0.003 0.010 +/- 0.002 Pass AP-061724A,B 6/17/2024 Gr. Beta 0.031 +/- 0.005 0.023 +/- 0.005 0.027 +/- 0.004 Pass AP-062524A,B 6/25/2024 Gr. Beta 0.033 +/- 0.003 0.034 +/- 0.003 0.034 +/- 0.002 Pass SG-1432,1433 6/24/2024 Ra-226 2.36 +/- 0.09 2.36 +/- 0.08 2.36 +/- 0.06 Pass SG-1432,1433 6/24/2024 Ra-228 1.67 +/- 0.14 1.69 +/- 0.15 1.68 +/- 0.10 Pass SG-1472,1473 7/1/2024 Gr. Alpha 36.0 +/- 4.5 36.8 +/- 4.5 36.4 +/- 3.2 Pass SG-1472,1473 7/1/2024 Gr. Beta 30.4 +/- 2.1 31.2 +/- 2.2 30.8 +/- 1.5 Pass SG-1472,1473 7/1/2024 Pb-214 2.64 +/- 0.11 3.11 +/- 0.09 2.88 +/- 0.07 Pass SG-1472,1473 7/1/2024 Ac-228 5.55 +/- 0.21 5.79 +/- 0.25 5.67 +/- 0.16 Pass SG-1474,1475 7/1/2024 Gr. Alpha 43.6 +/- 5.7 37.5 +/- 5.4 40.6 +/- 3.9 Pass SG-1474,1475 7/1/2024 Gr. Beta 40.6 +/- 2.8 34.2 +/- 2.7 37.4 +/- 1.9 Pass SG-1474,1475 7/1/2024 Pb-214 3.58 +/- 0.10 3.93 +/- 0.10 3.76 +/- 0.07 Pass SG-1474,1475 7/1/2024 Ac-228 4.21 +/- 0.15 4.13 +/- 0.16 4.17 +/- 0.11 Pass AP-070324A,B 7/3/2024 Gr. Beta 0.013 +/- 0.003 0.014 +/- 0.003 0.013 +/- 0.002 Pass W-1592,1593 7/9/2024 Gr. Alpha 1.23 +/- 0.67 0.36 +/- 0.54 0.80 +/- 0.43 Pass W-1592,1593 7/9/2024 Gr. Beta 1.45 +/- 0.60 0.60 +/- 0.53 1.03 +/- 0.40 Pass AP-071024A,B 7/10/2024 Gr. Beta 0.024 +/- 0.003 0.025 +/- 0.003 0.024 +/- 0.002 Pass S-1613,1614 7/11/2024 Pb-214 197 +/- 1 200 +/- 1 199 +/- 1 Pass S-1613,1614 7/11/2024 Ac-228 134 +/- 1 143 +/- 1 139 +/- 1 Pass AP-071724A,B 7/17/2024 Gr. Beta 0.038 +/- 0.001 0.032 +/- 0.003 0.035 +/- 0.001 Pass SG-1722,1723 7/22/2024 Gr. Beta 16.4 +/- 3.4 17.5 +/- 3.4 16.9 +/- 2.4 Pass SG-1722,1723 7/22/2024 Gr. Alpha 25.5 +/- 6.9 17.5 +/- 6.0 21.5 +/- 4.6 Pass SG-1722,1723 7/22/2024 K-40 6.99 +/- 1.04 5.75 +/- 0.86 6.37 +/- 0.67 Pass SG-1722,1723 7/22/2024 Pb-214 7.62 +/- 0.18 8.10 +/- 0.25 7.86 +/- 0.15 Pass SG-1722,1723 7/22/2024 Ac-228 4.72 +/- 0.34 4.76 +/- 0.36 4.74 +/- 0.24 Pass DW-60413,60414 7/22/2024 Gr. Alpha 1.71 +/- 0.79 0.93 +/- 0.81 1.32 +/- 0.56 Pass DW-60413,60414 7/22/2024 Gr. Beta 1.18 +/- 0.58 1.26 +/- 0.59 1.22 +/- 0.41 Pass AP-080524A,B 8/5/2024 Gr. Beta 0.025 +/- 0.003 0.025 +/- 0.003 0.025 +/- 0.002 Pass AP-081324A,B 8/13/2024 Gr. Beta 0.030 +/- 0.004 0.028 +/- 0.004 0.029 +/- 0.003 Pass AP-082124A,B 8/21/2024 Gr. Beta 0.034 +/- 0.003 0.030 +/- 0.003 0.032 +/- 0.002 Pass AP-082824A,B 8/28/2024 Gr. Beta 0.033 +/- 0.003 0.034 +/- 0.003 0.033 +/- 0.002 Pass AP-090924A,B 9/9/2024 Gr. Beta 0.025 +/- 0.005 0.026 +/- 0.005 0.026 +/- 0.003 Pass SO-2132,2133 9/9/2024 Be-7 0.39 +/- 0.11 0.53 +/- 0.22 0.46 +/- 0.12 Pass SO-2132,2133 9/9/2024 K-40 14.78 +/- 0.27 14.52 +/- 0.52 14.65 +/- 0.29 Pass SO-2132,2133 9/9/2024 Cs-137 0.10 +/- 0.01 0.08 +/- 0.02 0.09 +/- 0.01 Pass SO-2132,2133 9/9/2024 Tl-208 0.44 +/- 0.03 0.43 +/- 0.02 0.44 +/- 0.02 Pass SO-2132,2133 9/9/2024 Bi-212 1.40 +/- 0.34 1.25 +/- 0.15 1.32 +/- 0.19 Pass SO-2132,2133 9/9/2024 Bi-214 1.01 +/- 0.03 0.90 +/- 0.04 0.95 +/- 0.02 Pass SO-2132,2133 9/9/2024 Pb-212 1.29 +/- 0.02 1.18 +/- 0.03 1.24 +/- 0.02 Pass SO-2132,2133 9/9/2024 Pb-214 0.88 +/- 0.03 1.07 +/- 0.03 0.98 +/- 0.02 Pass Concentrationa Averaged First Result Second Result Result

A-13 TABLE A-5. Intralaboratory "Duplicate" Samples Collection Lab Codeb Date Analysis Acceptance SO-2132,2133 9/9/2024 Ra-226 2.38 +/- 0.36 2.31 +/- 0.16 2.34 +/- 0.20 Pass SO-2132,2133 9/9/2024 Ac-228 1.33 +/- 0.10 1.33 +/- 0.06 1.33 +/- 0.06 Pass SS-2206,2207 9/17/2024 Be-7 0.29 +/- 0.06 0.23 +/- 0.10 0.26 +/- 0.06 Pass SS-2206,2207 9/17/2024 K-40 6.54 +/- 0.29 6.19 +/- 0.20 6.37 +/- 0.18 Pass SS-2206,2207 9/17/2024 Tl-208 0.20 +/- 0.02 0.22 +/- 0.02 0.21 +/- 0.01 Pass SS-2206,2207 9/17/2024 Bi-212 0.65 +/- 0.14 0.69 +/- 0.19 0.67 +/- 0.12 Pass SS-2206,2207 9/17/2024 Bi-214 0.68 +/- 0.02 0.61 +/- 0.02 0.65 +/- 0.02 Pass SS-2206,2207 9/17/2024 Pb-212 0.51 +/- 0.02 0.59 +/- 0.02 0.55 +/- 0.01 Pass SS-2206,2207 9/17/2024 Pb-214 0.73 +/- 0.03 0.63 +/- 0.02 0.68 +/- 0.02 Pass SS-2206,2207 9/17/2024 Ra-226 1.12 +/- 0.12 1.25 +/- 0.19 1.18 +/- 0.11 Pass SS-2206,2207 9/17/2024 Ac-228 0.66 +/- 0.05 0.65 +/- 0.06 0.66 +/- 0.04 Pass VE-2111,2112 9/10/2024 Be-7 0.56 +/- 0.17 0.59 +/- 0.18 0.58 +/- 0.12 Pass VE-2111,2112 9/10/2024 K-40 4.62 +/- 0.40 5.21 +/- 0.41 4.91 +/- 0.29 Pass AP-091624A,B 9/16/2024 Gr. Beta 0.044 +/- 0.004 0.043 +/- 0.004 0.044 +/- 0.002 Pass SS-2206,2207 9/17/2024 Be-7 0.29 +/- 0.06 0.23 +/- 0.10 0.26 +/- 0.06 Pass SS-2206,2207 9/17/2024 K-40 6.54 +/- 0.29 6.19 +/- 0.20 6.37 +/- 0.18 Pass SS-2206,2207 9/17/2024 Tl-208 0.20 +/- 0.02 0.22 +/- 0.02 0.21 +/- 0.01 Pass SS-2206,2207 9/17/2024 Bi-212 0.65 +/- 0.14 0.69 +/- 0.19 0.67 +/- 0.12 Pass SS-2206,2207 9/17/2024 Bi-214 0.68 +/- 0.02 0.61 +/- 0.02 0.65 +/- 0.02 Pass SS-2206,2207 9/17/2024 Pb-212 0.51 +/- 0.02 0.59 +/- 0.02 0.55 +/- 0.01 Pass SS-2206,2207 9/17/2024 Pb-214 0.73 +/- 0.03 0.63 +/- 0.02 0.68 +/- 0.02 Pass SS-2206,2207 9/17/2024 Ra-226 1.12 +/- 0.12 1.25 +/- 0.19 1.18 +/- 0.11 Pass SS-2206,2207 9/17/2024 Ac-228 0.66 +/- 0.05 0.65 +/- 0.06 0.66 +/- 0.04 Pass VE-2111,2112 9/10/2024 Be-7 0.56 +/- 0.17 0.59 +/- 0.18 0.58 +/- 0.12 Pass VE-2111,2112 9/10/2024 K-40 4.62 +/- 0.40 5.21 +/- 0.41 4.91 +/- 0.29 Pass AP-092524A,B 9/25/2024 Gr. Beta 0.036 +/- 0.003 0.033 +/- 0.003 0.035 +/- 0.002 Pass AP-2773,2774 9/30/2024 Be-7 0.067 +/- 0.008 0.075 +/- 0.066 0.071 +/- 0.033 Pass SG-2353,2354 10/3/2024 K-40 3.68 +/- 0.34 2.79 +/- 0.59 3.24 +/- 0.34 Pass SG-2353,2354 10/3/2024 Tl-208 0.13 +/- 0.01 0.14 +/- 0.03 0.13 +/- 0.01 Pass SG-2353,2354 10/3/2024 Pb-212 0.36 +/- 0.02 0.27 +/- 0.03 0.32 +/- 0.02 Pass SG-2353,2354 10/3/2024 Pb-214 1.64 +/- 0.05 1.21 +/- 0.08 1.43 +/- 0.05 Pass SG-2353,2354 10/3/2024 Bi-214 1.56 +/- 0.05 1.32 +/- 0.10 1.44 +/- 0.06 Pass SG-2353,2354 10/3/2024 Ac-228 2.62 +/- 0.09 2.20 +/- 0.19 2.41 +/- 0.11 Pass SG-2362,2363 10/4/2024 Gr. Alpha 31.50 +/- 3.70 23.00 +/- 3.30 27.25 +/- 2.48 Pass SG-2362,2363 10/4/2024 Gr. Beta 24.70 +/- 1.70 19.60 +/- 1.60 22.15 +/- 1.17 Pass SG-2362,2363 10/4/2024 Ra-226 4.08 +/- 0.23 4.03 +/- 0.18 4.06 +/- 0.15 Pass SG-2362,2363 10/4/2024 Ra-228 5.90 +/- 0.41 5.85 +/- 0.34 5.88 +/- 0.27 Pass S-2541,2542 10/11/2024 K-40 14.20 +/- 0.44 14.82 +/- 0.44 14.51 +/- 0.31 Pass S-2541,2542 10/11/2024 Cs-137 0.08 +/- 0.01 0.10 +/- 0.01 0.09 +/- 0.01 Pass S-2541,2542 10/11/2024 Tl-208 0.26 +/- 0.02 0.27 +/- 0.02 0.27 +/- 0.01 Pass S-2541,2542 10/11/2024 Pb-212 0.75 +/- 0.03 0.54 +/- 0.03 0.64 +/- 0.02 Pass Concentrationa Averaged First Result Second Result Result

A-14 TABLE A-5. Intralaboratory "Duplicate" Samples Collection Lab Codeb Date Analysis Acceptance S-2541,2542 10/11/2024 Bi-212 1.17 +/- 0.29 0.83 +/- 0.16 1.00 +/- 0.16 Pass S-2541,2542 10/11/2024 Pb-214 1.28 +/- 0.05 1.07 +/- 0.05 1.17 +/- 0.04 Pass S-2541,2542 10/11/2024 Ac-228 0.88 +/- 0.08 0.85 +/- 0.08 0.86 +/- 0.06 Pass S-2752,2753 10/24/2024 K-40 15.24 +/- 0.33 15.54 +/- 0.31 15.39 +/- 0.22 Pass S-2752,2753 10/24/2024 Cs-137 0.09 +/- 0.09 0.10 +/- 0.09 0.09 +/- 0.06 Pass S-2752,2753 10/24/2024 Tl-208 0.33 +/- 0.01 0.34 +/- 0.01 0.34 +/- 0.01 Pass S-2752,2753 10/24/2024 Pb-212 0.93 +/- 0.02 0.98 +/- 0.02 0.96 +/- 0.01 Pass S-2752,2753 10/24/2024 Bi-212 1.15 +/- 0.12 1.13 +/- 0.12 1.14 +/- 0.08 Pass S-2752,2753 10/24/2024 Pb-214 1.33 +/- 0.03 1.19 +/- 0.03 1.26 +/- 0.02 Pass S-2752,2753 10/24/2024 Bi-214 1.37 +/- 0.04 1.19 +/- 0.03 1.28 +/- 0.03 Pass S-2752,2753 10/24/2024 Ra-226 2.61 +/- 0.36 2.28 +/- 0.15 2.45 +/- 0.20 Pass S-2752,2753 10/24/2024 Ac-228 1.10 +/- 0.07 1.10 +/- 0.04 1.10 +/- 0.04 Pass F-2899,2900 11/6/2024 K-40 2.38 +/- 0.35 3.06 +/- 0.13 2.72 +/- 0.18 Pass SW-2815,2816 11/5/2024 H-3 265 +/- 100 214 +/- 97 240 +/- 70 Pass SW-3046,3047 12/4/2024 H-3 109 +/- 91 178 +/- 94 144 +/- 65 Pass W-3067,3068 12/3/2024 H-3 206 +/- 96 329 +/- 102 268 +/- 70 Pass AP-3335,3336 12/30/2024 Be-7 0.034 +/- 0.005 0.050 +/- 0.005 0.042 +/- 0.003 Pass Note: Duplicate analyses are performed on every twentieth sample received. Results are not listed for those analyses with activities that measure below the LLD.

a Results are reported in units of pCi/L, except for air filters (pCi/Filter or pCi/m3), food products, vegetation, soil and sediment (pCi/g).

b AP (Air Particulate), AV (Aquatic Vegetation), BS (Bottom Sediment), CF (Cattle Feed), CH (Charcoal Canister),

DW (Drinking Water), E (Egg), F (Fish), G (Grass), LW (Lake Water), MI (Milk), P (Precipitation), PM (Powdered Milk),

S (Solid), SG (Sludge), SO (Soil), SS (Shoreline Sediment), SW (Surface Water), SWT (Surface Water Treated),

SWU (Surface Water Untreated), U (Urine), VE (Vegetation), W (Water), WW (Well Water).

Concentrationa Averaged First Result Second Result Result

A-15 TABLE A-6. Department of Energy's Mixed Analyte Performance Evaluation Program (MAPEP).

Reference Known Lab Code b Date Analysis Activity Acceptance MADW-429 2/1/2024 Gross Alpha 0.641 +/- 0.048 1.01 0.30 - 1.72 Pass MADW-429 2/1/2024 Gross Beta 4.71 +/- 0.08 5.6 2.79 - 8.36 Pass MADW-457 2/1/2024 Cs-134 0.09 +/- 0.19 0

NA c Pass MADW-457 2/1/2024 Cs-137 11.1 +/- 0.4 9.7 6.8 - 12.6 Pass MADW-457 2/1/2024 Co-57 26.4 +/- 0.4 25.4 17.8 - 33.0 Pass MADW-457 2/1/2024 Co-60 11.2 +/- 0.3 10.27 7.19 - 13.35 Pass MADW-457 2/1/2024 Mn-54 8.23 +/- 0.39 7.36 5.15 - 9.57 Pass MADW-457 2/1/2024 Zn-65 0.10 +/- 0.30 0

NA c Pass MADW-457 2/1/2024 K-40 3.16 +/- 2.49 0

NA c Pass MADW-457 2/1/2024 Ra-226 0.46 +/- 0.07 0.310 0.217 - 0.403 Fail d MAAP-459 2/1/2024 Cs-134 0.03 +/- 0.03 0

NA c Pass MAAP-459 2/1/2024 Cs-137 1.30 +/- 0.07 1.48 1.04 - 1.92 Pass MAAP-459 2/1/2024 Co-57 0.58 +/- 0.03 0.819 0.573 - 1.065 Pass MAAP-459 2/1/2024 Co-60 1.30 +/- 0.06 1.64 1.15 - 2.13 Pass MAAP-459 2/1/2024 Mn-54 0.51 +/- 0.05 0.555 0.389 - 0.722 Pass MAAP-459 2/1/2024 Zn-65 0.27 +/- 0.07 0.332 NA e Pass MASO-461 2/1/2024 Cs-134 345 +/- 2 404 283 - 525 Pass MASO-461 2/1/2024 Cs-137 1539 +/- 7 1550 1085 - 2015 Pass MASO-461 2/1/2024 Co-57 355 +/- 4 401 281 - 521 Pass MASO-461 2/1/2024 Co-60 619 +/- 4 660 462 - 858 Pass MASO-461 2/1/2024 Mn-54 332 +/- 13 332 232 - 432 Pass MASO-461 2/1/2024 Zn-65 543 +/- 9 703 492 - 914 Pass MASO-461 2/1/2024 K-40 510 +/- 20 485 340 - 631 Pass MAVE-464 2/1/2024 Cs-134 2.97 +/- 0.08 3.67 2.57 - 4.77 Pass MAVE-464 2/1/2024 Cs-137 2.36 +/- 0.15 2.57 1.80 - 3.34 Pass MAVE-464 2/1/2024 Co-57 1.78 +/- 0.09 2.53 1.77 - 3.29 Pass MAVE-464 2/1/2024 Co-60 2.61 +/- 0.13 2.96 2.07 - 3.85 Pass MAVE-464 2/1/2024 Mn-54 0.03 +/- 0.07 0

NA c Pass MAVE-464 2/1/2024 Zn-65 6.41 +/- 0.30 8.02 5.61 - 10.43 Pass Concentrationa Acceptance Laboratory result Range c

A-16 TABLE A-6. Department of Energy's Mixed Analyte Performance Evaluation Program (MAPEP).

Reference Known Lab Code b Date Analysis Activity Acceptance MADW-2185 8/1/2024 Gross Alpha 0.88 +/- 0.01 1.29 0.39 - 2.19 Pass MADW-2185 8/1/2024 Gross Beta 4.35 +/- 0.01 5.09 2.55 - 7.64 Pass MASO-2187 8/1/2024 Cs-134 330 +/- 4 417 292 - 542 Pass MASO-2187 8/1/2024 Cs-137 1650 +/- 11 1650 1155 - 2145 Pass MASO-2187 8/1/2024 Co-57 311 +/- 5 330 231 - 429 Pass MASO-2187 8/1/2024 Co-60 669 +/- 7 700 490 - 910 Pass MASO-2187 8/1/2024 Mn-54 116 +/- 5 113 79 - 147 Pass MASO-2187 8/1/2024 Zn-65 330 +/- 8 415 291 - 540 Pass MASO-2187 8/1/2024 K-40 531 +/- 31 525 368 - 683 Pass MADW-2183 8/1/2024 Cs-134 19.9 +/- 0.3 22.3 15.6 - 29.0 Pass MADW-2183 8/1/2024 Cs-137 0.99 +/- 0.29 0

NA c, e Fail MADW-2183 8/1/2024 Co-57 25.3 +/- 0.4 26.4 18.5 - 34.3 Pass MADW-2183 8/1/2024 Co-60 14.7 +/- 0.4 15.0 10.5 - 19.5 Pass MADW-2183 8/1/2024 Mn-54 0.12 +/- 0.16 0

NA c Pass MADW-2183 8/1/2024 Zn-65 20.6 +/- 1.0 22.8 16.00 - 29.60 Pass MADW-2183 8/1/2024 K-40 8.92 +/- 1.23 0

NA c, e Fail MAAP-2191 8/1/2024 Cs-134 0.254 +/- 0.030 0.334 0.234 - 0.434 Pass MAAP-2191 8/1/2024 Cs-137 0.260 +/- 0.046 0.269 0.188 - 0.350 Pass MAAP-2191 8/1/2024 Co-57

-0.0003 +/- 0.0126 0

NA c Pass MAAP-2191 8/1/2024 Co-60 0.333 +/- 0.045 0.361 0.253 - 0.469 Pass MAAP-2191 8/1/2024 Mn-54

-0.003 +/- 0.022 0

NA c Pass MAAP-2191 8/1/2024 Zn-65

-0.002 +/- 0.054 0

NA c Pass MAVE-2189 8/1/2024 Cs-134 2.10 +/- 0.07 2.89 2.02 - 3.76 Pass MAVE-2189 8/1/2024 Cs-137 1.53 +/- 0.11 1.91 1.34 - 2.48 Pass MAVE-2189 8/1/2024 Co-57 0.003 +/- 0.023 0

NA c Pass MAVE-2189 8/1/2024 Co-60 1.54 +/- 0.08 2.01 1.41 - 2.61 Pass MAVE-2189 8/1/2024 Mn-54 2.89 +/- 0.15 3.53 2.47 - 4.59 Pass MAVE-2189 8/1/2024 Zn-65 7.14 +/- 0.29 9.13 6.39 - 11.87 Pass a Results are reported in units of Bq/kg (soil), Bq/L (water) or Bq/total sample (filters, vegetation).

b Laboratory codes as follows: MAW (water), MADW (water), MAAP (air filter), MASO (soil) and MAVE (vegetation).

c MAPEP results are presented as the known values and expected laboratory precision (1 sigma, 1 determination) and control limits as defined by the MAPEP. A known value of "zero" indicates an analysis was included in the testing series as a "false positive". MAPEP does not provide an acceptance range.

d No conclusive reason for the failure could be determined. The uncertainty overlapped the known activity (reference value).

e False positive detections could have occurred due to a combination of an inadequate background subtraction for this sample geometry compounded by a very long analysis time.

Concentrationa Acceptance Laboratory result Range c

A-17 TABLE A-7. Interlaboratory Comparison Crosscheck Program, Environmental Resource Associates (ERA)a.

MRAD-40 Study Lab Code b Date Analysis ERA Value c Acceptance ERAP-574 3/18/2024 Cs-134 291 +/- 4 273 177 - 335 Pass ERAP-574 3/18/2024 Cs-137 131 +/- 6 106 87 - 139 Pass ERAP-574 3/18/2024 Co-60 1240 +/- 8 1120 952 - 1420 Pass ERAP-574 3/18/2024 Mn-54

< 3.1

< 35.0 0.00 - 35.0 Pass ERAP-574 3/18/2024 Zn-65 102 +/- 9 77.2 63.3 - 118 Pass ERAP-574 3/18/2024 Sr-90 173 +/- 5 158 99.9 - 215 Pass ERAP-600 3/18/2024 Gross Alpha 110 +/- 3 95.9 50.1 - 158 Pass ERAP-600 3/18/2024 Gross Beta 31.7 +/- 1.6 22.2 13.5 - 33.5 Pass a Results obtained by Microbac Laboratories - Northbrook as a participant in the crosscheck program for proficiency testing administered by Environmental Resource Associates, serving as a replacement for studies conducted previously by the Environmental Measurements Laboratory Quality Assessment Program (EML).

b Laboratory code ERAP (air filter). Results are reported in units of (pCi/Filter).

c The ERA Assigned values for the air filter standards are equal to 100% of the parameter present in the standard as determined by the gravimetric and/or volumetric measurements made during standard preparation as applicable.

d The acceptance limits are established per the guidelines contained in the Department of Energy (DOE) report EML-564, Analysis of Environmental Measurements Laboratory (EML) Quality Assessment Program (QAP)

Data Determination of Operational Criteria and Control Limits for Performance Evaluation Purposes or ERA's SOP for the generation of Performance Acceptance Limits.

Concentration a Laboratory Acceptance Result Limits d

Appendix B Data Reporting Conventions

APPENDIX B. DATA REPORTING CONVENTIONS Data Reporting Conventions 1.0. All activities, except gross alpha and gross beta, are decay corrected to collection time or the end of the collection period.

2.0. Single Measurements Each single measurement is reported as follows:

x +/- s where:

x = value of the measurement; s = 2 counting uncertainty (corresponding to the 95% confidence level).

In cases where the activity is less than the lower limit of detection L, it is reported as: < L, where L = the lower limit of detection based on 4.66 uncertainty for a background sample.

3.0. Duplicate analyses If duplicate analyses are reported, the convention is as follows. :

3.1 Individual results: For two analysis results; x1 +/- s1 and x2 +/- s2 Reported result: x +/- s; where x = (1/2) (x1 + x2) and s = (1/2) 2 2

2 1

s s

3.2.

Individual results:

< L1, < L2 Reported result: < L, where L = lower of L1 and L2 3.3.

Individual results:

x +/- s, < L Reported result:

x +/- s if x L; < L otherwise.

4.0. Computation of Averages and Standard Deviations 4.1 Averages and standard deviations listed in the tables are computed from all of the individual measurements over the period averaged; for example, an annual standard deviation would not be the average of quarterly standard deviations. The average x and standard deviation s of a set of n numbers x1, x2... xn are defined as follows:

x = 1 n x s =

(x-x )2 n-1 4.2 Values below the highest lower limit of detection are not included in the average.

4.3 If all values in the averaging group are less than the highest LLD, the highest LLD is reported.

4.4 If all but one of the values are less than the highest LLD, the single value x and associated two sigma error is reported.

4.5 In rounding off, the following rules are followed:

4.5.1. If the number following those to be retained is less than 5, the number is dropped, and the retained numbers are kept unchanged. As an example, 11.443 is rounded off to 11.44.

4.5.2. If the number following those to be retained is equal to or greater than 5, the number is dropped and the last retained number is raised by 1. As an example, 11.445 is rounded off to 11.45.

B-1

Appendix C Maximum permissible concentrations of radioactivity in air and water above natural background in unrestricted areas

APPENDIX C Table C-1.

Maximum permissible concentrations of radioactivity in air and water above natural background in unrestricted areas

a.

Air (pCi/m

3)

Water (pCi/L)

Gross alpha 1 x 10

-3 Strontium-89 8,000 Gross beta 1

Strontium-90 500 Iodine-131 b

2.8 x 10

-1 Cesium-137 1,000 Barium-140 8,000 Iodine-131 1,000 Potassium-40 c

4,000 Gross alpha 2

Gross beta 10 Tritium 1 x 10 6

a Taken from Table 2 of Appendix B to Code of Federal Regulations Title 10, Part 20, and appropriate footnotes.

Concentrations may be averaged over a period not greater than one year.

b Value adjusted by a factor of 700 to reduce the dose resulting from the air-grass-cow-milk-child pathway.

c A natural radionuclide.

C-1

D-1 APPENDIX D Sample Collection and Analysis Program

D-2

D-3

D-4

D-5

D-6

D-7

E-1 APPENDIX E Special Well and Surface Water Samples

1.0 INTRODUCTION

This appendix to the Radiological Environmental Monitoring Program Annual Report to the United States Nuclear Regulatory Commission summarizes and interprets results of the special well and surface water samples taken at the Prairie Island Nuclear Generating Plant, Red Wing, Minnesota, during the period January - December, 2024. This supplemental special sampling program was established in December of 1989 when higher than expected levels of tritium were detected in a nearby residence well sample.

Tabulations of the special sampling program individual analyses made during the year are included in this appendix. A summary table of tritium analyses is also included in this appendix.

2.0

SUMMARY

This special sampling program was established following the detection of tritium in a residence well water sample south of the PINGP during 1989. This program is described and the results for 2024 are summarized and discussed.

Program findings for 2024 detected low levels of tritium in nearby residence wells, ground water, surface samples, and storage tanks at or near the expected natural background levels with the exception of ground water sample wells MW-8 and P-10, and the septic system. The 2024 sample results (except for MW-8 and P-10, and the septic system) ranged from <19 pCi/L to 175 pCi/L. Sample well MW-8 ranged from 346 pCi/L to 779 pCi/L. Sample well P-10 ranged from 79 to 413 pCi/L. The septic system ranged from 68 to 5995 pCi/L. All tritium results are far below the Environmental Protection Agencys drinking water standard of 20,000 pCi/L and present no harm to any members of the public.

None of the water samples monitored for gamma-emitting isotopes showed any activity greater than the LLD (lower limit of detection).

E-2

E-3 3.0 Special Tritium Sampling Program 3.1 Program Design and Data Interpretation The purpose of this sampling program is to assess the impact of any tritium leaching into the environment (ground water system) from the PINGP. For this purpose, special water samples are collected and analyzed for tritium content.

3.2 Program Description The sampling and analysis schedule for the special water sampling program is summarized in Table E-4.1 and briefly reviewed below. Table E-4.2 defines the additional sample locations and codes for the special water sampling program.

Special well, tank, and surface water samples were collected quarterly (spring, summer, fall) at seven locations, quarterly at one location, monthly at six locations, semi-annually at five locations, and annually at thirty-nine locations. The Peterson (P-43) and Hanson (SW-1) farm wells are used as control locations for these special samples.

To detect low levels of tritium at or below natural background levels, analyses of the samples have been contracted to a laboratory (University of Waterloo Laboratories) capable of detecting tritium concentrations down to 19 pCi/L. Waterloo Laboratories report tritium analyses results in Tritium Units (1 TU = 3.2 pCi/L). The tritium results in this report are indicated in pCi/L.

3.3 Program Execution The special water sampling was executed as described in the preceding section.

3.4 Program Modifications Changes to the program in 2024 include:

Samples taken from monitoring wells P-10 and MW-8 were sent to Microbac Laboratories, Inc. for hard-to-detect nuclide analysis in accordance with American Nuclear Insurers recommendation No samples were taken from the D5 or D6 Fuel Oil Storage Tank vaults because these areas were dry in 2024

E-4 3.5 Results and Discussion Results show tritium in well water and ground water samples at or near expected natural background levels except MW-8 and P-10 ground water sample well. Table E-4.4 provides the complete data table of results for each period and sampling location.

The tritium level annual averages have shown a downward trend since the special sampling began in 1989.

Except for MW-8, P-10, and the septic system, the 2024 sample results are within the range of expected background tritium levels in shallow ground water and surface water due to tritium concentrations measured in precipitation. Sampling points in North America have shown tritium concentrations in precipitation ranging from 5 pCi/L to 157 pCi/L (Environmental Isotope Data No.

10; World Survey of Isotope Concentration in Precipitation (1988-1991)).

The higher-level results at the Suter residence and Birch Lake in 1989 were possibly due to seepage from the PINGP discharge canal water into the ground water. This is thought to occur due to the elevation difference between the Vermillion River and the discharge canal. The Suter residence is located between the discharge canal and Birch Lake, which connects to the Vermillion River. The PINGP discharge canal piping was lengthened during 1991, so that liquid discharges from the plant are released near the end of the discharge canal, diffused and discharged to the Mississippi River. In 1992, the underground liquid discharge pipe from the plant to the discharge canal piping was replaced with a double walled leak detectable piping system. This years sample results continue to indicate that these modifications have eliminated the suspected radioactive effluent flow into the local ground water.

The elevated tritium levels in sample wells MW-8 and P-10 in 2024 may be due to prior leakage from the PINGP liquid radwaste discharge pipe, discharge of turbine building sump water into the landlocked area, or discharge of heating steam condensate from the main warehouse in 1978/1979. The liquid radwaste discharge pipe was replaced in 1992 and the discharge to the landlocked area has been terminated, the last discharge took place on 11/14/09. The main warehouse heating system was repaired in 1979. The heating steam system has not been used in the outer plant buildings since the 2011 - 2012 heating season. The levels found in the septic system have returned to background levels.

None of the water samples monitored for gamma-emitting isotopes showed any activity greater than the LLD.

E-5 Table E-4.1. Sample collection and analysis program for special well, storage tank, and surface water samples, Prairie Island Nuclear Generating Plant, 2024.

Medium No.

Location codes and type a Collection type and frequency b Analysis type c Well water Annual 25 P-8 post-treat, P-8 pre-treat, REMP P-6, REMP P-11, PIIC-22, PIIC-26, PIIC-28, PIIC-29, P-7, P-9, P-11, PZ-1, PZ-2, PZ-4, PZ-5, PZ-7, MW-6, P-26, P-30, SW-3, SW-4, SW-5, SW-7, SW-8, SW-9 G/A H-3 Well water quarterly 1

P-24D G/Q H-3 Well water quarterly 7

P-2, P-3, P-5, P-6, PZ-8, MW-4, MW-5 G/Q H-3 Well water monthly 5

P-43(C), SW-1(C),

MW-7, MW-8, P-10 G/M H-3 Surface water 9

S-1, S-2, S-3, S-4, S-5, S-6, S-7, S-10, P-31 G/Ad H-3 Storage Tank 5

11 CST, 21 CST, 22 CST, U1/2 Demin Hdr G/S H-3 Storage Tank 1

Septic System G/M H-3 Snow 5

S-6, S-7, S-8, S-9, P-43(C)

G/A H-3 a Location codes are defined in table E-4.2. Control Stations are indicated by (C). All other stations are indicators.

b Collection type is codes as follows: G/ = grab. Collection frequency is coded as follows: M = monthly; Q = quarterly; Q = quarterly (spring, summer, and fall); S= semiannually; A = annually.

c Analysis type is coded as follows: H-3 = tritium.

d Location S-6, S-7, and S-10 are sampled semi-annually, P-31 is sampled three times a year

E-6 Table E-4.2. Sampling locations for special well, storage tank, and surface water samples, Prairie Island Nuclear Generating Plant, 2024.

Code Collection site Type of sample a Distance and direction from reactor P-8 PI Community well post treat DW 1.0 mi. @ 321°/WNW P-8 PI Community well pre treat DW 1.0 mi. @ 321°/WNW REMP P-6 Lock & Dam #3 well DW 1.6 mi. @ 129°/SE REMP P-11 Red Wing Service Center DW 3.3 mi @ 158°/SSE PIIC-22 1773 Buffalo Slough Rd DW 1 mi. @ 315°/NW PIIC-26 1771 Buffalo Slough Rd DW 1 mi. @ 315°/NW PIIC-28 1960 Larson Lane DW 1.5 mi. @ 287°/WNW PIIC-29 Buffalo Project DW 4.3 mi @ 302°/WNW P-24D Suter residence DW 0.6 mi. @ 158°/SSE P-43 Peterson Farm (Control)

DW 13.9 mi. @ 355°/N SW-1 Hanson Farm (Control)

DW 2.2 mi. @ 315°/NW P-2 Sample well WW See map P-3 Sample well WW See map P-5 Sample well WW See map P-6 Sample well WW See map P-7 Sample well WW See map P-10 Sample well WW See map P-11 Sample well WW See map PZ-1 Sample well WW See map PZ-2 Sample well WW See map PZ-4 Sample well WW See map PZ-5 Sample well WW See map PZ-7 Sample well WW See map PZ-8 Sample well WW See map MW-4 Sample well WW See map MW-5 Sample well WW See map MW-6 Sample well WW See map MW-7 Sample well WW See map MW-8 Sample well WW See map P-26 PITC well DW 0.4 mi. @ 258°/WSW P-30 Environ lab well DW 0.2 mi. @ 32°/NNE

E-7 Table E-4.2. Sampling locations for special well, storage tank, and surface water samples, Prairie Island Nuclear Generating Plant, 2024 (continued).

Code Collection site Type of sample a Distance and direction from reactor SW-3 Cooling Tower pump WW See map SW-4 New Admin Bldg DW 0.05 mi. @ 315/NW SW-5 Plant Screenhouse well WW 0.05 mi. @ 0/N SW-6 SGR Building DW 0.2 mi @ 310/NW SW-7 Distribution Center DW 0.35 mi @ 271/W SW-8 Site Admin Building well WW 0.2 mi @ 310/NW SW-9 FLEX Building WW 0.2 mi @ 238°/WSW P-9 Plant well # 2 DW 0.3 mi. @ 306°/NW S-1 Upstream Miss. River SW See map S-2 Recirc/Intake canal SW See map S-3 Cooling water canal SW See map S-4 Discharge Canal (end)

SW See map S-5 Mid Discharge Canal SW See map S-6 Roof Stormwater Runoff (also snow)

SW 0.05 mi. @ 0/N S-7 Parking Lot Stormwater (also snow)

SW 0.3 mi @ 306/NW S-8 P-10 area snow SW See map S-9 MW-7/8 area snow SW See map S-10 Barrel yard SW Storm Water Drain SW Outside Barrel yard P-31 Birch Lake Seepage SW 0.69 mi. @ 172°/S 11 CST Storage Tank ST Turbine Building 21 CST Storage Tank ST Turbine Building 22 CST Storage Tank ST Turbine Building Unit 1/2 demin hdr Storage Tank ST Turbine Building Septic System Storage Tank ST Outside #1 Warehouse D5 Vault Concrete Vault ST Outside Turbine Bldg D6 Vault Concrete Vault ST Outside Turbine Bldg a Sample codes: DW = Drinking Water: WW = Well Water; SW = Surface Water: ST = Storage Tank.

Table E-4.3 Radiation Environmental Monitoring Program Summary: Special well, storage tank, and surface water samples.

Name of Facility Prairie Island Nuclear Power Station Docket No.

50-282, 50-306 Location of Facility Goodhue, Minnesota Reporting Period January - December, 2024 (County, State)

Sample Type (Units)

Type and Number of Analyses a LLD b Indicator Locations Location with Highest Annual Mean Control Locations Number Non-Routine Results e Mean (F) c Range c Location d Mean (F) c Range c Mean (F) c Range c Offsite Well Water (pCi/L)

H-3 13 19 31 (4/13)

(27-41)

Lock & Dam 3

41 (1/1)

(41)

(See Control Below) 0 Onsite Well Water (pCi/L)

H-3 74 19 177 (62/74)

(20-779)

MW-8 500 (12/12)

(346-779)

(See Control Below) 14 Onsite Surface Water (pCi/L)

H-3 18 19 63 (10/18)

(21-175)

S-6 162 (1/1)

(162)

(See Offsite Snow Control Below) 0 Onsite Storage Tank (pCi/L)

H-3 23 19 1118 (14/22)

(55-5995)

Plant Septic 1293 (12/12)

(68-5995)

(See Control Below) 5 Control (offsite well water)

H-3 24 19 none SW-1 35 (2/12)

(34-36) 31 (4/24)

(20-36) 0 Control (offsite snow)

H-3 1

19 none P-43 51 (1/1)

(51) 51 (1/1)

(51) 0 a H-3 = tritium b LLD = Nominal lower limit of detection based on 4.66 sigma error for background sample. Value shown is lowest for the period.

c Mean and range are based on detectable measurements only. Fraction of detectable measurements at specified locations is indicated in parentheses (F).

d Locations are specified by code.

e Non-routine results are those which exceed ten times the control station mean value.

E-8

E-9 Table E-4.4 Radiological Environmental Monitoring Program, Complete Data Table, 2024.

SAMPLE DATES JAN 2024 FEB 2024 MAR 2024 APR 2024 MAY 2024 JUN 2024 JUL 2024 AUG 2024 SEP 2024 OCT 2024 NOV 2024 DEC 2024 CODE SAMPLE LOCATIONS pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L OFFSITE WELLS P-8 Post-treat PI Comm. Well

<19 P-8 Pre-treat PI Comm. Well

<19 REMP P-6 Lock & Dam #3 well 41 REMP P-11 Red Wing Service Center

<19 PIIC-22 1773 Buffalo Slough Rd

<19 PIIC-26 1771 Buffalo Slough Rd 30 PIIC-28 1960 Larson Lane

<19 PIIC-29 Buffalo Project

<19 P-24D Suter residence

<19 27

<19

<19 27 P-43 Peterson Farm (Control

<19/51*

• snow

<19

<19

<19 20

<19

<19

<19 32

<19

<19

<19 SW-1 Hanson Farm (Control)

<19

<19 36

<19

<19 34

<19

<19

<19

<19

<19

<19

E-10 Table E-4.4 Radiological Environmental Monitoring Program, Complete Data Table, 2024 (continued).

SAMPLE DATES JAN 2024 FEB 2024 MAR 2024 APR 2024 MAY 2024 JUN 2024 JUL 2024 AUG 2024 SEP 2024 OCT 2024 NOV 2024 DEC 2024 CODE SAMPLE LOCATIONS pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L ONSITE WELLS P-2 Sample well 79 63 120 P-3 Sample well

<19 30 38 P-5 Sample well 68 148 105 P-6 Sample well

<19 37

<19 P-7 Sample well 40 P-10 Sample well 79 97 145 206 80 123 131 212 413 339 301 120 P-11 Sample well 43 PZ-1 Sample well 20 PZ-2 Sample well 49 PZ-4 Sample well

<19 PZ-5 Sample well

<19 PZ-7 Sample well 40 PZ-8 Sample well 20 24 35 MW-4 Sample well 61 62 41 MW-5 Sample well

<19 45 131 MW-6 Sample well 156 MW-7 Sample well 72 161 87 37 147 145 131 100 95 86 78 33 MW-8 Sample well 539 348 438 346 383 371 376 738 779 630 548 501 P-26 PITC well

<19 P-30 Env. lab well 22 SW-3 CT pump

<19 P-9 Plant well # 2 29 SW-4 New Admin

<19 SW-5 Plnt Scrnhs 32 SW-7 Dist Center

<19

E-11 Table E-4.4 Radiological Environmental Monitoring Program, Complete Data Table, 2024 (continued).

SAMPLE DATES JAN 2024 FEB 2024 MAR 2024 APR 2024 MAY 2024 JUN 2024 JUL 2024 AUG 2024 SEP 2024 OCT 2024 NOV 2024 DEC 2024 CODE SAMPLE LOCATIONS pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L ONSITE WELLS SW-8 Site Admin Bldg

<19 SW-9 FLEX Bldg

<19

E-12 Table E-4.4 Radiological Environmental Monitoring Program, Complete Data Table, 2024 (continued).

SAMPLE DATES JAN 2024 FEB 2024 MAR 2024 APR 2024 MAY 2024 JUN 2024 JUL 2024 AUG 2024 SEP 2024 OCT 2024 NOV 2024 DEC 2024 CODE SAMPLE LOCATIONS pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L ONSITE SURFACE WATER S-1 Mississippi River upstream

<19 S-2 Recirculation/Intake canal 25 S-3 Cooling water canal

<19 S-4 Discharge Canal (end) 21 S-5 Discharge Canal (midway)

<19 S-6 Stormwater runoff 162*

52

<19 S-7 Parking Lot runoff

<19*

<19

<19 S-8 P-10 area snow 60*

S-9 MW-7/8 area snow 52*

S-10 Barrel yard SW Storm Water Drain 175 24 P-31 Birch Lake Seepage

<19 23 37

• snow samples

E-13 Table E-4.4 Radiological Environmental Monitoring Program, Complete Data Table, 2024 (continued).

SAMPLE DATES JAN 2024 FEB 2024 MAR 2024 APR 2024 MAY 2024 JUN 2024 JUL 2024 AUG 2024 SEP 2024 OCT 2024 NOV 2024 DEC 2024 CODE SAMPLE LOCATIONS pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L pCi/L ONSITE STORAGE TANKS 11 CST Storage tank

<19

<19 21 CST Storage tank

<19

<19 22 CST Storage tank

<19

<19 U1/U2 Demin Header Storage tank

<19/<19 72/55 Septic System Storage tank 702 301 175 68 108 124 245 118 1054 5995 5413 1215

E-14 Table E-4.5 Supplemental Data Table, results of the analyses for Ni-63 and Sr-90 on two samples.

E-15