Text

(CPNPP) - 2024 Annual Radiological Environmental Operating Report
	ML25114A085
Person / Time
Site:	Comanche Peak
Issue date:	04/24/2025
From:	Hicks J; Vistra Operations Company
To:	; Office of Nuclear Reactor Regulation, Document Control Desk
References
	CP-202500114, TXX-25021
	Download: ML25114A085 (1)
	v • d • e

CP-202500114 TXX-25021 April 24, 2025 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Comanche Peak Nuclear Power Plant (CPNPP)

Docket Nos. 50-445 and 50-446 2024 Annual Radiological Environmental Operating Report

Dear Sir or Madam:

Comanche Peak Nuclear Power Plant Jack C. Hicks Senior Manager, Fleet Licensing P.O. Box 1002 6322 North FM 56 Glen Rose, TX 76043 Office: 254.897.6725 Ref CPNPP ODCM 6.9.13 TS 5.6.2 Vistra Operations Company LLC (Vistra OpCo) hereby submits the Comanche Peak Nuclear Power Plant (CPNPP) 2024 Annual Radioactive Environmental Operating Report. The enclosed report is provided pursuant to CPNPP Technical Specification 5.6.2 and the CPNPP Offsite Dose Calculation Manual. The report covers the period from January 1, 2024 to December 31, 2024.

This letter contains no new regulatory commitments for CPNPP Unit 1 and Unit 2.

If you have any questions regarding this submittal, please contact Kassie Mandrell at (254) 897-6987 or Kassie.Mandrell@luminant.com.

Sincerely,

Enclosure:

CPNPP 2024 Annual Radiological Environmental Operating Report cc (email):

John Monninger, Region IV Uohn.Monninger@nrc.gov]

Dennis Galvin, NRR [Dennis.Galvin@nrc.gov]

John Ellegood, Senior Resident Inspector, CPNPP Uohn.Ellegood@nrc.gov]

Henry Strittmatter, Resident Inspector, CPNPP [Henry.Strittmatter@nrc.gov]

6555 SllcRRA DRIVE IRVI NG. TEXAS 75039 o 214-812-4600 VISTRACORPCOM

Comanche Peak Nuclear Power Plant Annual Environmental Operating Report 2024 Document Number: TR-2024-001463 CREATED BY:

ToddEme 4 au fj-/{)-J<

I APPROVED BY:

Shane Howe ~

l-- Date:

Annual Environmental Operating Report I YEAR: 2024 I Page 1 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant TABLE OF CONTENTS 1.0 LIST OF ACRONYMS AND DEFINITIONS................................................................................. 3 2.0 EXECUTIVE

SUMMARY

............................................................................................................. 5 2.1 Summary Of

Conclusions:

............................................................................................... 5

3.0 INTRODUCTION

........................................................................................................................ 6 4.0 SITE DESCRIPTION AND SAMPLE LOCATIONS...................................................................... ?

5.0 MAPS OF COLLECTION SITES.................................................................................,............. 16 6.0 REPORTING LEVELS FOR RADIOACTIVITY CONCENTRATIONS IN ENVIRONMENTAL SAMPLES.................................................................................................. 19 7.0 SAMPLING PROGRAM, PROGRAM MODIFICATION AND INTEPRETATION OF RESULTS................................................................................................................................. 20 7.1 Environmental Direct Radiation Dosimetry Sample Results........................................... 20 7.2 Air Particulate and Radioiodine Sample Results............................................................ 21 7.3 Waterborne Sample Results.......................................................................................... 22 7.4 Ingestion Pathway Sample Results............................................................................... 26 8.0 LAND USE CENSUS EXPOSURE PATHWAY....................................................................... 278 9.0 SAMPLE DEVIATIONS, ANOMALIES AND UNAVAILABILITY................................................. 29 10.0 OTHER SUPPLEMENTAL INFORMATION............................................................................... 30 10.1 NEI 07-07 Onsite Radiological Groundwater Monitoring Program................................. 30 10.2 Independent Spent Fuel Storage Installation (ISFSI) Monitoring Program..................... 30 10.3 Corrections to Previous Reports.................................................................................... 31 11.0 BIBLIOGRAPHY....................................................................................................................... 32 TABLES Table 1, Radiological Environmental Sampling Program - Exposure Pathway - Direct Radiation......... 8 Table 2, Radiological Environmental Sampling Program - Exposure Pathway - Airborne...................... 9 Table 3, Radiological Environmental Sampling Program - Exposure Pathway - Waterborne............... 10 Table 4, Radiological Environmental Sampling Program - Exposure Pathway - Ingestion................... 11 Table 5, REMP Sampling Locations - Direct Radiation....................................................................... 13 Table 6, Reporting Levels for Radioactivity Concentrations in Environmental Samples....................... 19 Table 7, Maximum Values for the Limit of Detection............................................................................ 19 Table 8: Land Use Census - Nearest Residence within 5 miles.......................................................... 28 Table 9: Sample Deviation Summary................................................................................................... 29 Table 10. JSFSI Environmental Direct Radiation Results (Units of mR Dose)...................................... 31

Annual Environmental Operating Report I YEAR: 2024 I Page 2 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant FIGURES Figure 1, Potential exposure pathways to Members of the Public due to Plant Operations [7]............... 6 Figure 2, REMP Sample Locations (Near Field/Site Boundary)........................................................... 16 Figure 3; REMP Sample Locations (Far Field)......................................................... :***........................ 17 Figure 4, REMP Sample Locations (Onsite)..... :.................................................................................. 18 Figure 5: Air Particulate: Analysis for Gross Beta, Average Mean for All Indicator Vs. Control............. 21 Figure 6: Surface Water Tritium Results.............................................................................................. 23 Figure 7: REMP Groundwater Tritium Sample Results........................................................................ 24 Figure 8: Drinking Water Tritium Sample Results................................................................................ 25 Figure 9: Drinking Water Gross Beta Samples Control location vs. Indicator Comparison................... 25 Figure 10. Map of ISFSI Pad............................................................................................................... 31 ATTACHMENTS., Data Table Summary.................................... *................................................................. 34, Complete Data Table for All Analysis Results Obtained In 2023................................... 35, Cross Check lntercomparison Program...................................................................... 133, Environmental Direct Radiation Dosimetry Sample Results........................................ 137

Annual Environmental Operating Report I YEAR: 2024 I Page 3 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 1.0 LIST OF ACRONYMS AND DEFINITIONS

1.

Airborne Activity Sampling: Continuous sampling of air through the collection of particulates and radionuclides on filter media.

2.

ARERR: Annual Radioactive Effluent Release Report

3.

AREOR: Annual Radiological Environmental Operating Report

4. '.

Composite Sample: A series of single collected portions (aliquots) analyzed as one sample. The aliquots making up the sample are collected at time intervals that are very short compared to the composite period.

5.

Control: A sampling station in a location not likely to be affected by plant effluents due to its distance and/or direction from the station.

6.

. Curie (Ci): A measure of radioactivity; equal to 3. 7 x 1010 disintegrations per second, or 2.22 x 1012 disintegrations per minute.

7.

Direct Radiation Monitoring: The measurement of radiation dose at various distances from the plant is assessed using Thermoluminescent dosimeters, Optical Stimulated Luminance dosimeters and pressurized ionization chambers.

8.

Grab Sample: A single discrete sample drawn at one point in time.

9.

Indicator: A sampling location that is likely to be affected by plant effluents due to its proximity and/or direction from the plant.

10.

Ingestion Pathway: The ingestion pathway includes milk, fish, drinking water and garden produce. Also sampled (under special circumstances) are other media such as vegetation and animal products such as eggs and meat when additional information about particular radionuclides is needed.

11.

ISFSI: Independent Spent Fuel Storage Installation

12.

Lower Limit of Detection {LLD): The smallest concentration of radioactive material in a sample that will yield a net count (above system background) that will be detected with 95% probability with a 5% probability of a false conclusion that a blank observation represents "real" signal.

13.

MDA: Minimum Detectable Activity. For radiochemistry instruments, the MDA is the a posteriori minimum concentration that a counting system detects. The smallest concentration or activity of radioactive material in a sample that will yield a net count above instrument background and that is detected with 95%

probability, with only five % probability of falsely concluding that a blank observation represents a true signal.

14.

MDC: Minimum Detectable Concentration

15.

Mean: The average, i.e., the sum of results divided by the number of results.

Annual Environmental Operating Report I YEAR: 2024 I

Page 4 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant

16.

Microcurie: 3. 7 x 104 disintegrations per second, or 2.22 x106 disintegrations per minute.

17.

MWe: Megawatts Electric

18.

NA: Not Applicable

19.

NOA: No Detectable Activity

20.

NEI: Nuclear Energy Institute

21.

NIST: National Institute of Standards and Technology.

22.

NPDES: National Pollutant Discharge Elimination System.

23.

SPDES: State Pollution Discharge Elimination System

24.

NRC: Nuclear Regulatory Commission

25.

ODCM: Offsite Dose Calculation Manual

26.

pCi/L: picocuries / Liter

27.

Protected Area: An area encompassed by physical barriers and to which access is controlled.

28.

PWR: Pressurized Water Reactor

29.

REMP: Radiological Environmental Monitoring Program

30.

SLC: Selected Licensee Commitment

31.

SA: Sample Anomalies

32.

SD: Sample Deviation

33.

SPDES: State Pollutant Discharge Elimination System.

34.

SW: Surface Water

35.

TLD: Thermoluminescent Dosimeter

36.

TRM: Technical Requirement Manual

37.

TS: Technical Specification

38.

US: Unavailable Samples

Annual Environmental Operating Report I YEAR: 2024 I Page 5 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 2.0 EXECUTIVE

SUMMARY

2.1 Comanche Peak Nuclear Power Plant (CPNPP) Radiological Environmental Monitoring Program (REMP) was established prior to the station becoming operational to provide information on background radiation present in the area. The goal of CPNPP REMP is to evaluate the impact of the station on the environment.

Environmental samples from different media are monitored as part of the program in accordance with specifications detailed in the Offsite Dose Calculation Manual (QDCM) and CPNPP "Technical Specification "Technical Specifications for Comanche Peak Nuclear Power Plant Units 1 and 2". The program compares data from indicator locations near the plant, to control locations farther away from the site to assess operation impacts.

The Annual Radiological Environmental Operating Report (AREOR) provides data obtained through analyses of environmental samples collected at CPNPP for the reporting period of January 1st through December 31st, 2024. In assessing all the data gathered for this report and comparing these results with preoperational data and/or 10-year average values, it was concluded that the operation of CPNPP, did not result in detection of plant related radionuclides in the environment.

Summary Of

Conclusions:

No measurable activities above background levels were detected. All values were consistent with historical results which indicate no adverse radiological environmental impacts associated with the operation of CPNPP. Naturally occurring radionuclides are present in the Earth's crust and atmosphere and exists in detectable quantities throughout the world. It is common to detect natural occurring radionuclides in many of the samples collected for REMP. Some examples of naturally occurring radionuclides that are frequently seen in samples are potassium-AO, beryllium-?,

actinium-228 (present as a decay product of radium-228), and radium-226.

Additionally, some relatively long-lived anthropogenic radioisotopes, such as strontium-90 and cesium-137, are also seen in some REMP samples; these radionuclides exist in measurable quantities throughout the world as a result of fallout from historic atmospheric nuclear weapons testing. Detailed information on the exposure of the U.S. population to ionizing radiation can be found in NCRP Report No. 160 [1].

Annual Environmental Operating Report I

YEAR: 2024 I

Page 6 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant

3.0 INTRODUCTION

The Radiological Environmental Monitoring Program (REMP) provides data on measurable levels of radiation and radioactive materials in the environment. This program also evaluates the relationship between quantities of radioactive materials released from the plant and resultant doses to individuals from principal pathways of exposure. In this capacity, REMP provides a check on the effluent release program and dispersion modeling to ensure that concentrations in the environment due to radioactive effluents conform to the "As Low as Is Reasonably Achievable" (ALARA) design objectives of 1 O CFR 50, Appendix I [2], and implements the requirements of Section IV.B.2 and IV.B.3 of Appendix I. REMP is designed to conform to the Nuclear Regulatory Commission (NRC) Regulatory Guide 4.1 [3], NUREG 1301 /1302

[4] [5], and the 1979 NRC Branch Technical Position (6].

0.

Gaseous effiuents 0

~

i...

\\ Deposition

\\ /

o,...,..., __

Soil

\\ Inhalation Li,*estock products Ingestion 0 ~

Marine produc!s

Radiation O

Radionuclides

00 *

Behavior ofradionuclides Figure 1, Potential exposure pathways to Members of the Public due to Plant Operations [7]

Quality assurance aspects of the sampling program and TLD data colle.ction are conducted in accordance with Regulatory Guides 4.15 [8] and 4.13 [9]. REMP also adheres to the requirements of The State of Texas, CPNPP Technical Specifications, and Offsite Dose Calculation Manual (ODCM). These governing documents dictate the environmental sampling, sample analysis protocols, data reporting and quality assurance requirements for the environmental monitoring program.

Annual Environmental Operating Report 1 YEAR: 2024 I Page 7 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant The Annual Radiological Environmental Operating Report provides summaries of the environmental data from exposure pathways, interpretations of the data, and analyses of trends of the results. Routinely monitored pathways include ingestion, inhalation, and direct radiation. Routes of exposure are based on site specific information such as meteorology, receptor locations, and water usage around the plant.

4.0 SITE DESCRIPTION AND SAMPLE LOCATIONS CPNPP consists of two pressurized water reactor units, each designed to operate at a power level of about 1250 megawatts (electrical). The Station is located on Squaw Creek reservoir in Somervell and Hood counties, about forty miles southwest of Fort Worth, Texas. Unit 1 received a low power operating license February 8, 1990, and achieved initial criticality on April 3, 1990. A full power license for Unit 1 was issued on April 17, 1990, and commercial operation was declared on August 13, 1990. Unit 2 achieved initial criticality on March 24, 1993, and synchronized to the electrical grid on April 9, 1993. CPNPP sampling media are selected based on site specific information such as meteorology, receptor locations, and water usage around the plant. Sampling and analysis frequencies are documented in the Offsite Dose Calculation Manual and site procedures.

This report documents the 35th year of operational measurements and is submitted in accordance with the requirements of the CPSES Offsite Dose Calculation Manual, Part I, Administrative Control 6.9.1.3.

. Required sampling, analysis frequencies and location of sample collected are captured in the following tables and figures:

Table 1, Radiological Environmental Sampling Program - Exposure Pathway-Direct Radiation Table 2, Radiological Environmental Sampling Program - Exposure Pathway -

Airborne Table 3, Radiological Environmental Sampling Program - Exposure Pathway -

Waterborne Table 4, Radiological Environmental Sampling Program - Exposure Pathway -

Ingestion Table 5, REMP Sampling Locations - Direct Radiation Figure 2, REMP Sample Locations (Near Field/Site Boundary)

Figure 3, REMP Sample Locations (Far Field)

Figure 4, REMP Sample Locations (Onsite)

Annual Environmental Operating Report I YEAR: 2024 I Page 8 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant RADIOLOGICAL ENVIRONMENTAL SAMPLING PROGRAM REQUIREMENTS Table 1, Radiological Environmental Sampling Program - Exposure. Pathway-Direct' Radiation Requirement Sample Location Description, Sampling Collection/

Type and Frequency of Analyses Distance, and Direction Frequency Direct Radiation 40 Routine monitoring stations with two or more dosimeters placed as follows:

An inner ring of stations, one in each meteorological sector in the general area of the site boundary.

See Table 5 Quarterly and Annually Gamma Dose Quarterly and Annually An outer ring of stations, one in each meteorological sector at approximately 5 miles from the site; and Special interest areas, such as population centers, nearby recreation areas, and control stations.

Annual Environmental Operating Report I YEAR: 2024 I Page 9 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Table 2, Radiological Environmental Sampling Program - Exposure Pathway - Airborne Requirement Sample Location Description, Sampling Collection/

Type and Frequency of Analyses Distance, and Direction Frequency Airborne Radioiodine and Close to CPNPP:

Particulates A-8, NW-1.0 Samples from 8 locations:

A-7, SW/WSW-0.95 A-5, S/SSW-1.2 Particulate sampler: Analyze for gross beta 4 locations close to the site boundary A-1, N-1.45 in different sectors of the highest radioactivity 2: 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months following filter change/

calculated annual average ground Communities:

Weekly. Perform gamma isotopic analysis on level D/Q.

Continuous sampler each sample when gross beta activity is > 1 o A-4, SSE 4.5 operation with sample times the yearly mean of control samples.

2 samples from the vicinity of a A-3, E-3.5 collection weekly.

Perform gamma isotopic analysis on composite community having the highest sample Quarterly.

calculated annual average D/Q.

Controls:

A-6, SW-12.3 Radioiodine canister: 1-131 analysis Weekly.

2 samples from a Control Location, A-2, N-9.4 approximately 10 to 20 miles away in the least predominant wind direction.

Annual Environmental Operating _ _Report I YEAR: 2024 I Page 10 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Table 3, Radiological Environmental Sampling Program - Exposure Pathway - Waterborne Requirement Sample Location Description, Sampling Collection/

Type and Frequency of Distance, and Direction Frequency Analyses Surface Water SW-3, N-19.3-Control Composite sample over one-2 samples upstream (control)

SW-4, NE-7.4-Control month period; samples from and 2 of samples downstream SW-1, N-1.5-Downstream monthly composites are Gamma isotopic Monthly, (indicator)

SW-5, ESE 1.5-Downstream combined to form quarterly H-3 Quarterly composite samples to be analyzed for H-3.

Drinking Water 1 sample upstream (control) and SW-2, N-9.9-Control Composite sample over one 1 sample downstream (indicator)

SW-6, NNW-0.1-Downstream month period. Monthly Gross beta and gamma Monthly, composite samples.

H-3 Quarterly.

Groundwater GW-4, N-9.8-Control 1 control location upgradient GW-1, SW-1.2 Gamma isotopic and H-3 from the plant and 4 indicator GW-2, WSW-0.1 Grab samples quarterly Quarterly locations down gradient from the GW-3, SSE-4.6 plant, only if likely to be affected.

GW-5, N-1.45 Sediment from Shoreline SS-2, N-9.9-Control 2 samples upstream (control)

SS-3, NE-7.4-Control Semiannual and 2 samples downstream SS-1, NNE-1.0-Downstream Gamma isotopic Semiannually (indicator)

SS-4, SE-5.3-Downstream Vegetation BL~3, SW13.5-Control 1 sample upstream (control) and BL-2, SW-1.0-Downstream Semiannual 2 samples downstream BL-1, N-1.45-Downstream Gamma isotopic Semiannually (indicator)

Annual Environmental Oper~ting Report I YEAR: 2024 I Page 11 of 138 Com_l!_any: Vistra Corp Comanche Peak Nuclear Power Plant Table 4, Radiological Environmental Sampling Program - Exposure Pathway-Ingestion Sample Location Sampling Collection/

Type and Frequency of Requirement Description, Distance, Frequency Analyses and Direction Milk:

Samples from milking animals in three locations within 5 km distance having the highest dose potential. If there are none, sample from milking Gamma isotopic and 1-131 animals in each of three areas between 5 to 8 km No milk sampling Semimonthly when animals are analysis Semimonthly when

.distant where doses are calculated to be greater locations (See Broadleaf on pasture; monthly at other animals are on pasture; than 1 mrem per yr.

Program).

times monthly at other times.

1 sample from milking animals at a control location 15 to 30 km distant and in the least prevalent wind direction.

Fish and Invertebrates:

1 sample of at least two recreationally important species in vicinity of plant discharge area.

F-1 ENE-2.0 Semiannually Gamma isotopic analysis on F-2 NNE-8.0 edible portions semiannually 1 sample of same species in areas not influenced by plant discharge.

Annual Environmental Operating Report L YEAR: 2024 I Page 12 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Table 4, Radiological Environmental Sampling Program - Exposure Pathway-Ingestion Sample Location Sampling Collection/

Type and Frequency of Requirement Description, Distance, and Direction Frequency Analyses Food Products:

At time of harvest Gamma isotopic analysis on One sample of each principal class of food products edible portion following sample from any area that is irrigated by water in which collection.

liquid plantwastes have been discharged.

A sample of broad leaf vegetation grown nearest Monthly, when available Gamma isotopic and 1-131 each of two different offsite locations of highest FP-1 ENE-9.0 analyses, Monthly, when predicted annual average ground level D/Q if milk FP-2 E-4.2 samples collected.

sampling is not performed at all required locations.

One sample of each of the similar broad leaf Monthly, when available Gamma isotopic and 1-131 vegetation grown 15 to 30 km distant in the least analyses, monthly, when prevalent wind direction if milk sampling is not samples are collected.

performed at all required locations.

Annual Environmental Operating Report I YEAR: 2024 I Pa~ge 13 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Table 5, REMP Sampling Locations - Direct Radiation Location#

Location

Sector

. Distance

Description Type.. *.

1 Inner 2 Mile N

1.45 Miles Squaw Creek Park Buffer 2

Outer Ring N

4.4 Miles Neri Road 3

Outer Ring N

6.5 Miles Total Equipment & Services 4

Outer Ring N

9.4 Miles Granbury 5

Inner 2 Mile NNE 1.1 Miles Squaw Creek Reservoir Buffer 6

Outer Ring NNE 5.65 Miles Contrary Creek Road 7

lnner2 Mile NE 1.7 Miles Squaw Creek Reservoir Buffer 8

Outer Ring NE 4.8 Miles Mitchell Bend Court 9

Outer Ring ENE 2.5 Miles Spillway 10 Outer Ring ENE 5 Miles Mitchell Bend Court 11 Inner 2 Mile E

0.5 Miles Meteorological Tower Buffer 12 Inner 2 Mile E

1.9 Miles Dam Buffer 13 Outer Ring E

3.5 Miles Happy Hill Farm 14 Outer Ring E

4.2 Miles Hornick Farm 15 lnner2 Mile ESE 1.4 Miles OCA Back Road Buffer

Annual Environmental Operating Report I YEAR: 2024 I Page 14 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant Table 5, REMP Sampling Locations - Direct Radiation Location#.

Location Sector.

Distance Description

Type 16 Outer Ring ESE 4.7 Miles Rainbow Baptist Church 17 Inner 2 Mile Buffer SE 1.3 Miles OCA Back Road 18 Inner 2 Mile SE 3.85 Miles County Road 302 Buffer 19 Outer Ring SE 4.6 Miles Longhorn Drive & HWY 67 20 Inner 2 Mile SSE 1.3 Miles OCA Back Road Buffer 21 Outer Ring SSE 4.4 Miles HWY 56 & HWY 67 22 Outer Ring SSE 4.5 Miles Glen Rose Hospital 23 lnner2 Mile s

1.5 Miles OCA Back Road Buffer 24 Outer Ring s

4.23 Miles EMU Farm 25 Inner 2 Mile SSW 1.2 Miles OCA Back Road Buffer 26 Outer Ring SSW 4.4 Miles Dinosaur State Park 27 Inner 2 Mile SW 0.9 Miles OCA Back Road Buffer 28 Outer Ring SW 4.8 Miles Cedar Brake Ranch 29 Outer Ring SW 12.3 Miles Chalk Mountain 30 Inner 2 Mile WSW 1 Mile OCA Back Road Buffer 31 Outer Ring WSW 5.35 Miles Three Rivers Ranch

Annual Environmental Operating Report I YEAR: 2024 I Page 15 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Table 5, REMP Sampling Locations - Direct Radiation Location#

Location Sector

Distance Description Type 32 Outer Ring WSW 7 Miles HWY 51 & Edwards Roads 33 lnner2 Mile w

1 Mile OCA Back Road Buffer 34 Outer Ring w

1 Mile Plant Entrance 35 Outer Ring w

5.5 Miles Wildcat Knob Road 36 lnner2 Mile WNW 1 Mile Across from the NOSF Buffer 37 Outer Ring WNW 5 Miles HWY 51 & HWY 56 38 Outer Ring WNW 6.7 Miles Texas Flag on Barn 39 Inner 2 Mile NW 1 Mile A-8 Air sample Station Buffer 40 Outer Ring NW 5.7 Miles Panther Branch Road 41 Outer Ring NW 9.9 Miles Meyer's Kwik Stop 42 Inner 2 Mile NNW 1.35 Miles Squaw Creek Reservoir Buffer 43 Outer Ring NNW 4.6 Miles Rocking Chair Ranch 44 lnner2 Mile SE 0.6 Miles ISFISI Pad (North)

Buffer 45 lnner2 Mile SE 0.6 Miles ISFISI Pad (East)

Buffer 46 lnner2 Mile SE 0.6 Miles ISFISI Pad (South)

Buffer 47 Inner 2 Mile SE 0.6 Miles ISFISI Pad (West)

Buffer

Annual Environmental Operating Report I YEAR: 2024 I Page 16 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 5.0 MAPS OF COLLECTION SITES R30

BL2 R2r A-7 R25

R23

Figure 2, REMP Sample Locations (Near Field/Site Boundary)

R12

Annual Environmental Operating Report I YEAR: 2024 I Page 17 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Figure 3, REMP Sample Locations (Far Field)

Annual Environmental Operating Report I YEAR: 2024 I Page 18 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant COMANCHE PEAK Comanche_Peak D 2 Mile Buffer D 20 Mile Buffer Figure 4, REMP Sample Locations (Onsite)

N

-dl 7

Annual Environmental Operating Report I YEAR: 2024 I Page 19 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 6.0 REPORTING LEVELS FOR RADIOACTIVITY CONCENTRATIONS IN ENVIRONMENTAL SAMPLES Table 6, Reporting Levels for Radioactivity Concentrations in Environmental Samples Air Particulates Fish (pCi/kg-Food Products Radionuclide Water (pCi/L) or Gases Milk (pCi/L)

(pCi/m3) wet)

(pCI/Kg-wet)

H-3 20,0001 NA NA NA NA Mn-54 1,000 NA 30,000 NA NA Fe-59 400 NA 10,000 NA NA Co-58 1,000 NA 30,000 NA NA Co-60 300 NA 10,000 NA NA Zn-65 300 NA 20,000 NA NA Zr-Nb-95 400 NA NA NA NA 1-131 22 0.9 NA 3

100 Cs-134 30 10 1,000 60 1,000 Cs-137 50 20 2,000 70 2,000 Ba-La-140 200 NA NA 300 NA Table 7, Maximum Values for the Limit of Detection Water Air Particulates Fish Milk Food Products Sediment Radionuclide (pCi/L) or Gases (pCi/kg-(pCi/L)

(pCi/Kg-wet)

(pCi/Kg-dry)

(pCi/m3) wet)

H-3 2,0003 NA NA NA NA NA Mn-54 15 NA 130 NA NA NA Fe-59 30 NA 260 NA NA NA Co-58, Co-60 15 NA 130 NA NA NA Zn-65 30 NA 260 NA NA NA Zr-Nb-95 15 NA NA, NA NA NA 1-131 14 0.07 NA 1

60 NA Cs-134 15 0.05 130 15 60 150 Cs-137 18 0.06 150 18 80 180 Ba-La-140 15 NA NA 15 NA NA 1 For drinking water samples: If no drinking water pathway exists, a value of 30,000 pCi/L may be used.

2 If no drinking water pathway exists, a value of 20 pCi/1 may be used.

3 If no drinking water pathway exists, a value of 3,000 pCi/L may be used. Some states may require a lower LLD for drinking water sources-per 40CFR141 Safe drinking water ACT.

4 If no drinking water pathway exists, a value of 15 pCi/1 may be used.

Annual Environmental Operating Report I YEAR: 2024 I Page 20 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 7.0 SAMPLING PROGRAM, PROGRAM MODIFICATION AND INTEPRETATION OF RESULTS 7.1 Data was collected prior to plant operation to determine background radioactivity levels in the environment. Annual data is routinely compared to preoperational and/or 10-year average values to determine if changes in the environs are present. Strict comparison is difficult to make due to fallout from historical nuclear weapon testing.

Cesium-137 can be routinely found in environmental samples as a result of above ground nuclear weapons testing. It is important to note, levels of Cs-137 in environment are observed to fluctuate, for example as silt distributions shift due to natural erosion and transport processes, Cs-137 may or may not be observed in sediment samples. Results from samples collected and analyzed during the year 2023, are described below.

In the following sections, results from direct radiation, air, water, and food products analyzed as part of REMP in 2024 will be discussed. Sampling program descriptions and deviations will also be discussed.

Environmental Direct Radiation Dosimetry Sample Results Dose is measured as net exposure (field reading less transit reading) normalized to 91-day quarters. Data is treated and analyzed consistent with ANSI/HPS N13.37-2014, which compares the measured dose for each location to the baseline background dose for that location. Environmental dose rates vary by location, depending on geological and land use considerations, and remain relatively constant for any given location (unless land use changes). Some facilities observe seasonal variation in environmental doses. Baseline Background Doses have been determined for both quarterly and annual measurements at each location using historical field measurements. Minimum Differential Doses for Annual and Quarterly periods have been determined based on 3-times the 90th percentile standard deviation for monitoring locations. Doses that exceed the Minimum Differential Dose value above the Baseline Background Dose are considered to indicate Facility-Related Dose; a quality assurance review is performed to verify that any results indicating Facility-Related Dose are accurate.

ANSI/HPS N13.37-2014 uses the concept of minimum differential dose (MOD), which is the minimum facility-related dose that can be detected above the baseline background. Due to natural background variations and measurement sensitivities and uncertainties, minimum differential dose is not zero. MOD is calculated based on performance of the dosimetry system in the environment and is about 5 mrem per quarter and 10 mrem per year. If a dosimeter indicates dose greater than background plus MOD, then the net dose (above background) is reported as Facility Related Dose.

During calendar year 2024, a total of 209 samples were collected and analyzed in accordance with the requirements in Table 1, Radiological Environmental Sampling Program - Exposure Pathway -

Direct Radiation. Attachment 4, Environmental Direct Radiation Dosimetry Sample Results, includes the annual direct radiation dosimetry sample results.

Annual Environmental Operating Report I YEAR: 2024 I Page 21 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 7.2 All TLD analysis results were below detection limit.

Air Particulate and Radioiodine Sample Results Air particulate filters and charcoal canisters were collected from locations specified in Table 2, Radiological Environmental Sampling Program - Exposure Pathway -

Airborne. During calendar year 2024, a total of 428 samples were collected and analyzed for gross beta, gamma emitters and iodine. Particulate samplers are used to analyze gross beta activity following filter change out which occurs weekly.

Gamma isotopic analysis is performed on composite samples collected at each location and is analyzed quarterly. Radioiodine (1-131) analysis is performed weekly on radioiodine sample cartridges.

All air particulate and radioiodine samples were below detection limit with the exception of naturally occurring radionuclides.

Typical of pre-operational and previous operational data results, the only radioactive nuclide identified in all the samples were naturally occurring radionuclides.

Refer to Figure 5: Air Particulate: Analysis for Gross Beta, Average Mean for All Indicator Vs. Control, for air particulate/ radioiodine sample trends.

Air Particulate: Analysis for Gross Beta Indicator vs. Control 6.00E-02 5.00E-02

- r 4.00E-02 1 3.00E-02 G

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2.00E-02 1.00E-02 0.OOE+00 s=>o {s s=>o 76' s=>o 7,.>

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Annual Environmental Operating Report I YEAR: 2024 I Page 22 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 7.3 Waterborne Sample Results 7.3.1 Surface Water (i.e., lake and stream)

Composite water samples are collected monthly at the upstream control location and at the downstream indicator locations. Monthly composite samples are analyzed for gamma emitters. Aliquots from the monthly composites are combined to form quarterly composites which is then analyzed for tritium. During calendar year 2024, a total of 48 surface water samples were collected and analyzed in accordance with the requirements in the ODCM and shown in Table 3, Radiological Environmental Sampling Program -

Exposure Pathway - Waterborne.

Discharge Pathway Surface water monitoring stations are found at four locations as detailed in Table 3 -Radiological Environmental Monitoring Program - Exposure Pathway - Waterborne. Location N-1.5 provides samples representative of Squaw Creek reservoir surface water at a location beyond significant influence of the plant discharge. Location ESE-1.4 provides samples representative of discharges from Squaw Creek reservoir downstream to Squaw Creek and to Lake Granbury via an installed return line. [NOTE: The installed return line to Lake Granbury has never been used to send water back to Lake Granbury.] Location NE-7.4 provides samples of Lake Granbury surface water downstream of the discharge from the return line from Squaw Creek reservoir. A control sample is obtained from the Brazos River, upstream of Lake Granbury at location N-19.3. Discharge Pathway Surface water samples from Squaw Creek reservoir locations were collected weekly and composited for monthly gamma isotopic analysis. Samples from Lake Granbury locations were collected monthly and analyzed by gamma spectrometry. All Discharge Pathway Surface Water samples were also composited quarterly by location for tritium analysis.

All Discharge Pathways Surface Water samples were collected as required. Forty-eight samples were analyzed by gamma spectrometry. All results for the required radionuclides were reported as less than the required LLDs. Sixteen quarterly composited samples were analyzed for tritium. The results of the reported tritium values for Squaw Creek reservoir were in line with expected concentrations. The tritium values ranged from a high of 1.37E+04 pCi/I to a low of 8.81 E+03 pCi/1. The results from Lake Granbury were all less than the required LLDs as expected. The tritium concentration reported in Squaw Creek is well below the action level of 3.00E+4 pCi/I and is following the expected concentration variations based on fuel cycles, power histories and reservoir makeup due to rain and pump transfers from Lake Granbury. Figure 6 -

Surface Water Tritium Results indicates the last ten years of tritium concentration in Squaw Creek reservoir, Squaw Creek spillway, and Brazos River {control location).

Squaw Creek reservoir tritium is a direct product from the operation of CPNPP.

There should not be any significant changes in the tritium concentrations in the near future and no action levels are anticipated. A review of pre-operational and operational data indicated the 2024 results were both expected and consistent with previous data and that no anomalies had occurred.

Annual Environmental Operating Report I YEAR: 2024 I Page 23 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant

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7.3.2 SURFACE WATER TRITIUM DATA 2.50E+04 2.00E+04 1.50E+04 1.00E+04 5.00E+03 0.00E+OO 11-

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Monthly/Composite Sample Dates Figure 6: Surface Water Tritium Results REMP Groundwater (Offsite Impact Monitoring)

---Indicator 1

....... Indicator 2 Control Groundwater samples were collected from control location upgradient from the plant and indicator location down gradient from the plant. During calendar year 2024, a total of 20 groundwater water samples were collected from five different monitoring locations and analyzed in accordance with the requirements in the ODCM and shown in Table 3: Radiological Environmental Sampling Program - Exposure Pathway -

Waterborne. A total of four control samples and a total of 16 indicator samples were collected. These samples were analyzed for tritium and gamma quarterly.

Groundwater supplies in the site area are not affected by plant effluents and are sampled only to provide confirmation that groundwater is not affected by plant discharges.

There were no radionuclides identified in any of the samples. All required LLDs were met for each required gamma emitting radionuclide. Tritium analysis was performed on twenty samples, all indicated less than the required LLD. Indicator and control results are illustrated in Figure 7. The results confirm that plant discharges are having no effect on groundwater in the area surrounding Comanche Peak.

Annual Environmental Operating Report I YEAR: 2024 j Page 24 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 2.5-0E+04 2.00E+04 0 a.

Z: 1.5-0E+04

s;

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1-5.00E+03 O.OOE+OO 2024 REMP Groundwater Tritium Sample Results March control June

* ** *

Average Indicator September EPA Limit December Figure 7: REMP Groundwater Tritium Sample Results 7.3.3 Drinking Water A total of 24 drinking water samples were obtained in 2024. These samples were analyzed for gross beta, and gamma analysis monthly and tritium quarterly, in accordance with requirements in the ODCM and shown in Table 3, Radiological Environmental Sampling Program - Exposure Pathway - Waterborne.

Samples of water from Squaw Creek Reservoir were collected at the monitoring location NNW-0.1. There is not a surface water drinking source within a mile of CPNPP. Monitoring location N-9.9 is used as a surface drinking water location based on the proximity of the City of Granbury intake to the Granbury potable water system.

All samples were analyzed for gamma emitting radionuclides. There were no gamma emitting radionuclides positively identified in any of the twenty-four composite samples. Two samples from SW-2 and one sample from SW-6 indicated gamma emitters above background, but were determined to be false positives (e.g., high peak width, low abundance or no valid peak).

Tritium reported in Squaw Creek reservoir ranged from 1.02E+04 pCi/1 to 1.42E+04 pCi/1 and averaged 1.22E+04 pCi/1. Tritium reported from all Lake Granbury water samples indicated less than the required LLD as expected.

Tritium results for location SW-2 and SW-6 are illustrated in Figure 8. SW-2 is the sample location near the intake to the City of Granbury potable water system.

SW-6 is from Squaw Creek Reservoir. Squaw Creek Reservoir is not a source of drinking water but is included to identify the highest source of tritium concentration due to CPNPP Operation.

Annual Environmental Operating Report I YEAR: 2024 I Page 25 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Gross beta results for location SW-2 and SW-6 are illustrated in Figure 9.

Environmental Squaw Creek and Lake Granbury Surface Water Tritium Results 1.60E+04 1.40E+04 1.20E+04 1.00E+04 8.00E+03

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1.60E+01 1.40E+01 1.20E+01

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6.00E+00 4.00E+00 2.00E+00 0.00E+00 +----.---"""T""----r----,---..-----~---.-----r------i

-2o 0 Year sw-2

---sw-<:J Figure 9: Drinking Water Gross Beta Samples Control location vs. Indicator Comparison

Annual Environmental Operating Report I YEAR: 2024 I Page 26 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 7.3.4 Sediment from Shoreline Shoreline sediment collections were made in January and July 2024 and analyzed for gamma-emitting isotopes. Control locations are sampled in addition to indicator locations. A total of four shoreline samples were analyzed in accordance with requirements in the ODCM and shown in Table 3, Radiological Environmental Sampling Program - Exposure Pathway - Waterborne.

One sample location is along the shore of Squaw Creek Reservoir, one sample location is on Squaw Creek downstream of the dam discharge and two locations are along Lake Granbury's shores.

The process of shoreline sedimentation is a complex evolution whereby potential radionuclides and stable elements may concentrate in the bottom sediment of particular bodies of water. The concentrations are affected by such things as colloidal particles combining with chelating agents and biological action of bacteria and other benthic organisms. Monitoring of the area shorelines provides one of the first and best indicators of radionuclide deposition.

The shoreline sediment samples were analyzed with no positive results from plant-related radionuclides. There was one sample in 2024 that detected Cs-134 above the minimum detectable activity. The sample analysis concluded that it was a false positive due to low abundance.

7.4 Ingestion Pathway Sample Results 7.4.1 Milk Currently there are no milk sample locations within ten miles of the CPNPP site.

CPNPP samples extra broadleaf locations as required due to no milk locations within the ten-mile radius therefore, no changes to the program are necessary. Milk sampling will be resumed if any future annual land use census determines a dairy has been established within the specified area.

7.4.2 Fish A total of three fish samples were collected in 2024. Two samples were analyzed for gamma emitting radionuclides in edible portions, in accordance with requirements of the ODCM and summarized in Table 4, Radiological Environmental Sampling Program - Exposure Pathway - Ingestion. One fish sample collected from Squaw Creek Reservoir was analyzed for tritium Two sample locations are collected from the indicator and control areas as required by the ODCM, while the other fish analysis is not required by the ODCM.

The fish from ENE-2.0 and NNE-8.0 were analyzed with no positive results from plant-related radionuclides. One sample detected Cs-137 above the minimum detectable activity, but the analysis concluded that it was a false positive due to no valid peak.

Annual Environmental Operating Report I YEAR: 2024 I Page 27 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Tritium analysis is performed annually on Squaw Creek fish (CR-2014-013335).

The analysis of the (cooked} fish sample collected on December 10, 2024, from Squaw Creek indicates a positive Tritium concentration of 8.07 pCi/g. This is consistent with tritium concentration of fish from previous years: 2023 cooked fish was 6.81 pCi/g, 2022 cooked fish was 3.45 pCi/g. This is not an ODCM required sample/analysis, and there is NO reporting level. The sample/analysis of cooked fish from Squaw Creek was a recommendation during an audit.

7.4.3 Food Products A total of one (pecans), sample was analyzed in 2024, for gamma emitting radionuclides in accordance with requirements of the ODCM, as summarized in Table 4, Radiological Environmental Sampling Program - Exposure Pathway-Ingestion.

Results of all required radionuclide results were reported as less than the required minimum detectable activity.

7.4.4 Grass and Leafy Vegetation In accordance with the ODCM and as described in Table 4, Radiological Environmental Sampling Program - Exposure Pathway-Ingestion, 36 broad leaf vegetation samples were collected from growing locations nearest site boundary in areas of highest predicted annual average ground level D/Q. Samples are collected and analyzed for gamma isotopic and 1-131 from the indicator and control locations monthly during growing season. It is common to detect Cs-137 in broadleaf samples at both indicator and control locations. Cs-137 can be attributed to offsite sources such as weapons testing, Chernobyl, and Fukushima events. While Cs-137 is periodically found in vegetation samples, the historical relationship between the indicator and control locations demonstrates that the plant is not the source of activity detected.

The grass and leafy vegetation samples were analyzed with no positive results from plant-related radionuclides. There was one sample in 2024 that detected Cs-137, 1-131, Ba-140 above the minimum detectable activity. The sample analyses concluded that those radionuclides were a false positives due to high counting uncertainty, no valid peak and low abundance, respectively.

Annual Environmental Operating Report I YEAR: 2024 I Page 28 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 8.0 LAND USE CENSUS EXPOSURE PATHWAY Annual Land Use Census required by the Offsite Dose Calculation Manual is performed to ensure that changes in the use of areas at or beyond the site boundary are identified and modifications to REMP are made if required by changes in land use. Land use census satisfies the requirements of Section IV.B.3 of Appendix I to 10 CFR 50 [2]. NUREG-1301/1302 Control 3.12.2 specifies that "a land use census shall be conducted and shall identify within a distance of 8 km (5 mi.) the location in each of the 16 meteorological sectors of the nearest milk animal, the nearest residence and the nearest garden of greater than 50 m2 (500 ft2) producing broad leaf vegetation." Note, per NUREG-1301/1302, Broad leaf vegetation sampling of at least three different kinds of vegetation may be performed at the SITE BOUNDARY in each of two different direction sectors with the highest predicted D/Qs in lieu of the garden census.

A Land Use Census was conducted during calendar year, 2024, within the growing season to identify changes in land use, receptor locations, and new exposure pathways. The results for the 2024 Land Use Census are listed in Table 8: Land Use Census - Nearest Residence within 5 miles. The highest D/Q location for nearest garden and nearest milk animal did not change following the 2024 census.

Table 8: Land Use Census - Nearest Residence within 5 miles Nearest Distance Nearest Distance Distance Sector Direction Residence (Miles)

Milk (Miles)

Garden (Miles)

Animal 1

N Structure 2.6 NA NA NA NA 2

NNE Structure 2.5 NA NA NA NA 3

NE Structure 2.5 NA NA NA NA 4

ENE Structure 2.6 NA NA NA NA 5

E Structure 2.5 NA NA Tomatoes 4.2 6

ESE Structure 2.2 NA NA NA NA 7

SE Structure 2.0 NA NA NA NA 8

SSE Structure 1.5 NA NA NA NA 9

s Structure 1.5 NA NA NA NA 10 SSW Structure 1.8 NA NA NA NA 11 SW Structure 0.8 NA NA NA NA 12 WSW Structure 0.8 NA NA NA NA 13 w

Structure 1.6 NA NA NA NA 14 WNW Structure 2.5 NA NA NA NA 15 NW Structure 2.9 NA NA NA NA 16 NNW Structure 2.2 NA NA NA NA

Annual Environmental Operating Report I YEAR: 2024 I Page 29 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 9.0 SAMPLE DEVIATIONS, ANOMALIES AND UNAVAILABILITY Sampling and analysis are performed for media types addressed in the Offsite Dose Calculation Manual. Sampling and analysis challenges may be experienced due to a multitude of reasons including environmental factors, loss of TLDs, contamination of samples etc. To aid classification of sampling and analysis challenges experienced in 2024, the following three terms are used to describe the issues: Sample Anomalies (SA), Sample Deviation (SD), and Unavailable Samples (US).

Media that experienced downtime (i.e., air samplers or water samplers) during a surveillance period are classified as "Sample Deviation". "Sample Anomalies" are defined as errors that were introduced to a sample once it arrived in the laboratory, errors that prevents the sample from being analyzed as it normally would or may have altered the outcome of the analysis (i.e., cross contamination, human error).

"Sample Unavailability" is defined as sample collection with no available sample (i.e.,

food crop, TLD).

All required samples were collected and analyzed as scheduled except for the following:

Table 9: Sample Deviation Summary Sample Location Collection Reason for not conducting Plans for preventing Type and Date or REMP sampling as required reoccurrence Analysis Period byODCM Air (SD) Air Sample Station Particulate A-1 3/5/2024 Pump stopped running due to Replaced fuse blown fuse. Run time of 59.5 and Charcoal hours.

Fish F-1 and F-2 1st Half of (US} Sample not collected No action necessary as sample 2024 due to no available sample could not be taken.

Air (SD) Air Sample Station A-1 Interrupter was reset which Particulate A-1 10/1/2024 only ran for 33 hours3.819444e-4 days 0.00917 hours 5.456349e-5 weeks 1.25565e-5 months as allowed air sampler to resume and Charcoal thunderstorm tripped GFCI operation.

Air (SD} Air Sample Station A-1 Interrupter was reset which Particulate A-7 4/16/2024 only ran for 19.5 hours5.787037e-5 days 0.00139 hours 8.267196e-6 weeks 1.9025e-6 months as allowed air sampler to resume and Charcoal thunderstorm tripped GFCI operation.

Direct R37 3/28/2024 (US} Dosimeter was missing Dosimeters replaced at usual Radiation from fence.

changeout.

(US} Both annual and Contacted Vendor to make Direct quarterly dosimeters more obvious labeling between Radiation R1 3/28/2024 mistakenly sent back to dosimeters of different year and vendor instead of installation at exposure location.

quarter.

(US} Broad Leaf Sample Broad Leaf BL-2 10/29/2024 Counted with higher LLD than Contract laboratory is taking required (64.3 pCl/kg instead steps to prevent reoccurrence.

of 60 pCi/kg}.

Annual Environmental Operating Report I YEAR: 2024 I Page 30 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Table 9: Sample Deviation Summary Sample Location Collection Reason for not conducting Plans for preventing Type and Date or REMP sampling as required reoccurrence Analysis Period byODCM Air Interrupter was reset which (SD) Air Sample Station A-1 o Particulate A-1 1/7/2025 tripped GFCI allowed air sampler to resume and Charcoal operation.

Air (SD) Air Sample Station A-80 Air sample station resumed Particulate A-8 9/10/2024 run time loss due to operation after transformer and Charcoal transformer failure.

repair.

Direct (US) Both annual and Dosimeters replaced at usual R32 1/7/2025 quarterly dosimeter missing Radiation from fence.

changeout.

Q1: R3, R21, R30 02: R20, (SD) Combination of quarterly Direct R21, R26 and annual dosimeters Seeking clarification with Q3:R5, 2024 indicating false readings.

Radiation R19, R26, These values were excluded dosimetry vendor.

10.0 10.1 10.2 R33, R41, from analysis R43 Annual: R40 OTHER SUPPLEMENTAL INFORMATION NEI 07-07 Onsite Radiological Groundwater Monitoring Program Comanche Peak Nuclear Power Plant has developed a Groundwater Protection Initiative (GPI) program in accordance with NEI 07-07, Industry Ground Water Protection Initiative - Final Guidance Document. The purpose of the GPI is to ensure timely detection and an effective response to situations involving inadvertent radiological releases to groundwater in order to prevent migration of licensed radioactive material off-site and to quantify impacts on decommissioning. It is important to note, samples and results taken in support of NEI 07-07 groundwater monitoring program are not part of the Radiological Environmental Monitoring Program (REMP). Results of NEI 07-07 Radiological Groundwater Monitoring Program for onsite Wells are communicated in the ARERR.

Independent Spent Fuel Storage Installation {ISFSI) Monitoring Program The total number of fuel dry casks located at the CPNPP ISFSI pad by the end of2024 was sixty (60).

The ISFSI PAD is located within the same CPNPP owner-controlled area as the Unit 1 and 2 Protected Area. Prior to 2019 Direct Radiation monitoring was accomplished and reported with the established owner-controlled area Direct Radiation monitoring programs. Four (4) TLDs were added on each side of the PAD' s fence for radiation monitoring, trending, and reporting within the Annual Environmental Report (locations 44, 45, 46, and 47).

Annual Environmental Operating Report I YEAR: 2024 I Page 31 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant

-~~::J

.. ---.. ----------- --- ------ -------*----~ --.. --...

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~--- ----------------------------- ~ -- --- ----- - -----------------------------------

Figure 10. Map of ISFSI Pad Table 10. ISFSI Environmental Direct Radiation Results (Units of mR Dose)

AVG 1STQTR Average 2ND QTR Average 3RDQTR Average 4TH QTR Average QTR TLD Location Total mR/Day Total mR/Day Total mRJDay Total mR/Day Total SE-0.6 58 0.642 85 0,934 104 1.144 77 0.846 81 R44 SE-0.6 219 2.411 262 2.879 254 2.792 263 2.890 249.5 R45 SE-0.6 183 2.016 225 2.473 233 2.561 183 2.011 206 R46 SE-0.6 236 2.598 244 2.682 206 2.265 227 2.495 228.25 R47 AVERAGES 174 1.917 204 2.242 199 2.190 188 2.060

191 10.3 Corrections to Previous Reports No corrections noted for prior CPNPP Annual Radiological Environmental Operating Reports.

Qtly TLD Average mRJDay 0.892 2.743 2.265 2.510 2.102

Annual Environmental Operating Report I YEAR: 2024 I Page 32 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant 11.0 BIBLIOGRAPHY

[1] NCRP, "Report No. 160, Ionizing Radiation Exposure of the Population of the United States,"

National Council on Radiation Protection, Bethesda, 2009.

[2] "10 CFR 50, "Domestic Licensing of Production and Utilization Facilities"," US Nuclear Regulatory Commission, Washington, DC.

[3] "Regulatory Guide 4.1, "Radiological Environmental Monitoring for Nuclear Power Plants",

Revision 2," Nuclear Regulatory Commission, 2009.

[4] "NUREG-1301, "Offsite Dose Calculation Manual Guidance: Standard Radiological Effluent Controls for Pressurized Water Reactors,".," Nuclear Regulatory Commission, April 1991.

[5] "NUREG-1302, "Offsite Dose Calculation Manual Guidance: Standard Radiological Effluent Controls for Boiling Water Reactors,"," Nuclear Regulatory Commission, April 1991.

[6] "Branch Technical Position, Revision 1," NRC000096, Submitted March 30, 2012, November 1979.

[7] "Japan Atomic Energy Agency," 06 November 2020. [Online]. Available:

https://www.jaea.go.jp/english/04/ntokai/houkan/houkan_02.html.

[8] "Regulatory Guide 4.15, Quality Assurance for Radiological Monitoring Programs (Inception through Normal Operations to License Termination) -- Effluent Streams and the Environment,"

Nuclear Regulatory Commission, July, 2007.

[9] "Regulatory Guide 4.13, Performance, Testing, and Procedural Specifications for Thermoluminescence Dosimetry: Environmental Applications, Revision 2," Nuclear Regulatory Commision, June, 2019.

[10] "NUREG/CR-2919, "XOQDOQ Computer Program for the Meteorological Evaluation of Routine Effluent Releases at Nuclear Power Stations,"," Nuclear Regulatory Commission, September, 1982.

[11] "Measurements of Radionuclides in the environment Sampling and Analysis of plutonium in soil,"

Nuclear Regulatory Commission, 197 4.

{12] "Ionizing Radiation Exposure of the Population of the United States," Bethesda, MD, 2009.

[13] Nuclear Regulatory Commission, 30 June 2015. [OnlineJ. Available: http://www.nrc.gov/reading-rm/basic-ref/students/animated-pwr.html. [Accessed October 2020].

[14] "ICRP Publication 60, "ICRP Publication 60: 1990 Recommendations of the International Commission on Radiological Protection, 60," Annals of the ICRP Volume 21/1-3,," International Commission on Radiation Protection, October, 1991.

[15] "NRC Resource Page," [Online]. Available: http://www.nrc.gov/about-nrc/radiation.html. [Accessed 10 November 2020].

[16] "NUREG-0133, Preparation of Effluent Technical Specifications for Nuclear Power Plants,"

Nuclear Regulatory Commission, 1987.

[17] "Regulatory Guide 1.109, "Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Demonstrating Compliance with 1 O CFR Part 50, Appendix I,,"

Nuclear Regulatory Commission, Ocotober, 1977.

[18] [Online]. Available: http://hps.org/hpspublications/radiationfactsheets.html. [Accessed 2020].

[19] "NEI 07-07, "Industry Ground Water Protection Initiative-Final Guidance Document,"," Nuclear Energy Institute, Washington, D.C..

Annual Environmental Operating Report I YEAR: 2024 I Page 33 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant

[20] "ANSI 13.37, Environmental Dosimetry-Criteria for System Design and Implementation," Health Physics Society (HPS), May, 2019.

[21] "40 CFR Part 141, "National Primary Drinking Water Regulations,"," US Environmental Protection Agency, Washington, DC..

[22] Nuclear Regulatory Commission, 25 June 2015. [Online]. Available: http://www.nrc.gov/reading-rm/basic-ref/students/animated-bwr.html. [Accessed October 2020].

[23] "NEI 07-07, "Industry Ground Water Protection Initiative-Final Guidance Document," Rev. 1,"

Nuclear Energy Institute, Washington, D.C., 2019.

[24] Nuclear Regulatory Commission, 25 June 2015. [Online]. Available: http://www.nrc.gov/reading-rm/basic-ref/students/animated-bwr.html. [Accessed October 2020].

[25] [Online]. Available: http://hps.org/hpspublications/radiationfactsheets.html. [Accessed 2020].

[26] "Japan Atomic Energy Agency," 06 November 2020. [Online]. Available:

https://www.jaea.go.jp/english/04/ntokai/houkan/houkan_02.html.

[27] "NRC Resource Page," [OnlineJ. Available: http://www.nrc.gov/about-nrc/radiation.html. [Accessed 1 O November 2020].

[28] "NUREG-0133, Preparation of Effluent Technical Specifications for Nuclear Power Plants,"

Nuclear Regulatory Commission, 1987.

[29] Nuclear Regulatory Commission, 30 June 2015. [Online}. Available: http://www.nrc.gov/reading-rm/basic-ref/students/animated-pwr.html. [Accessed October 2020].

[30] "Regulatory Guide 4.13, Performance, Testing, and Procedural Specifications for Thermoluminescence Dosimetry: Environmental Applications, Revision 2," Nuclear Regulatory Commision, June, 2019.

[31] "Regulatory Guide 4.15, Quality Assurance for Radiological Monitoring Programs (Inception through Normal Operations to License Termination) -- Effluent Streams and the Environment,"

Nuclear Regulatory Commission, July, 2007.

[32] "10 CFR 50 - Domestic Licensing of Production and Utilization Facilities," US Nuclear Regulatory Commission, Washington, DC.

[33J "40 CFR 190 ~ Environmental Radiation Protection Standards for Nuclear Power Operation," US Environmental Protection Agency, Washington, DC.

[34J "NUREG-0324 - XOQDOQ, Program for the Meteorological Evaluation of Routine Effluent Releases at Nuclear Power Stations," Nuclear Regulatory Commission, September, 1977.

[35] "NCRP Report No. 160 - Ionizing Radiation Exposure of the Population of the United States,"

National Council on Radiation Protection and Measurements, Bethesda, MD, 2009.

[36] "Regulatory Guide 1.109 - Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Demonstrating Compliance with 1 O CFR Part 50, Appendix I," Nuclear Regulatory Commission, Ocotober, 1977.

[37] "40 CFR 141 - National Primary Drinking Water Regulations," US Environmental Protection Agency, Washington, DC..

[38] "10 CFR 20- Standards for Protection Against Radiation," US Nuclear Regulatory Commission, Washington, DC.

Annual Environmental Operating Report I YEAR: 2024 I Page 34 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant, Data Table Summary Location with Highest Annual Type, Total Number Indicator Mean Medium or of Analyses Lower Limit of Mean5 ;

Control Number of Pathway performed Detection Mean1 Mean1 (f2}.

Non routine (f6).

Name Sampled (Units)

(LLD)

Range1 Reported (e.g., 1-131, 400)

Range1 Distance and

{t2)

Measurements Direction Range1 Air Particulates Beta, 428 0.01 4.20E-02 (pCi/m3)

NW-1.0 (A-8) 4.91E-02 4.05E-02 0

Airborne Radioiodirie 1-131, 428 0.07 9.75E-03 (pCi/m3)

SSW-1.2 (A-5) 1.24E-02 7.61 E-03 0

Air Particulates, Range (0.05 to Composite Gamma Spectrum, 32 Background*

NA NA NA 0

(pCi/m3) 0.06)

Direct Radiation Gamma Spectrum, 43 N/A

Background

NA NA NA 0

(mR/Qtr.)

Vegetation Gamma Spectrum/

Range (60 to

Background

NA NA NA 0

(pCi/kg-wet) 1-131, 36

80)

Gamma Gamma Range

Background

Surface Water (15 to 30),

(pCi/L)

Spectrum/Tritium/I-Tritium (2000),

(gamma, NA NA NA 0

131, 48 1-131 (1)

Tritium, 1-131)

Fish (pCi/kg-wet)

Gamma Spectrum, 2 Range (130 to

Background

NA NA NA 0

260)

Sediment (pCi/kg-Gamma Spectrum, 4 Range (150 to

Background

NA NA NA 0

dry) 180) 5 Mean and range are based on detectable measurements only.

6 Fraction of detectable measurements at specified locations is indicated in parentheses.

Annual Environmental Operating Report I YEAR: 2024 I Page 35 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant, Complete Data Table for All Analysis Results Obtained In 2023 Air Sample Location A-1 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 650472015 1/2/2024 lodine-131 2.64E-02 1.48E-02 2.24E-02 pCi/m3 Air Charcoal 651480015 1/9/2024 lodine-131 1.83E-03 3.94E-03 1.34E-02 pCi/m3 Air Charcoal 652168015 1/16/2024 lodine-131

-3.56E-03 3.17E-03 9.54E-03 pCi/m3 Air Charcoal 652769015 1/23/2024 lodine-131

-5.62E-03 3.19E-03 7.85E-03 pCi/m3 Air Charcoal 653673015 1/30/2024 lodine-131 6.89E-03 2.92E-03 1.15E-02 pCi/m3 Air Charcoal 654638015 2/6/2024 lodine-131

-1.57E-03 2.88E-03 9.31E-03 pCi/m3 Air Charcoal 655415015 2/13/2024 lodine-131 1.78E-03 3.81E-03 1.20E-02 pCi/m3 Air Charcoal 656171015 2/20/2024 lodine-131 1.25E-03 5.53E-03 1.89E-02 pCi/m3 Air Charcoal 657034015 2/27/2024 lodine-131 6.48E-03 5.46E-03 2.03E-02 pCi/m3 Air Charcoal 659140015 3/12/2024 lodine-131 2.61E-02 1.74E-02 3.06E-02 pCi/m3 Air Charcoal 659692015 3/19/2024 lodine-131 8.68E-03 7.37E-03 2.72E-02 pCi/m3 Air Charcoal 660512015 3/26/2024 lodine-131

-1.36E-03 5.72E-03 1.70E-02 pCi/m3 Air Charcoal 662103015 4/2/2024 Jodine-131 1.03E-03 5.36E-03 1.79E-02 pCi/m3 Air Charcoal 662643015 4/9/2024 lodine-131 1.42E-02 6.41E-03 2.51E-02 pCi/m3 Air Charcoal 663750015 4/16/2024 lodine-131 2.85E-03 8.66E-03 2.91E-02 pCi/m3 Air Charcoal 664746015 4/23/2024 Jodine-131

-8.88E-03 9.24E-03 2.90E-02 pCi/m3 Air Charcoal 665753015 4/30/2024 lodine-131

-2.56E-02 1.14E-02 3.18E-02 pCi/m3 Air Charcoal 667499015 5/7/2024 -

lodine-131

-4.94E-03 8.99E-03 2.39E-02 pCi/m3 Air Charcoal 667922015 5/14/2024 lodine-131 4.21E-03 6.38E-03 2.llE-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 36 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-1 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 668704015 5/21/2024 lodine-131 2.52E-03 5.22E-03 1.73E-02 pCi/m3 Air Charcoal 669507015 5/28/2024 lodine-131 1.09E-02 1.01E-02 3.75E-02 pCi/m3 Air Charcoal 670356015 6/4/2024 lodine-131 3.13E-03 8.57E-03 2.92E-02 pCi/m3 Air Charcoal 671436015 6/11/2024 lodine-131

-1.99E-02 1.31E-02 3.72E-02 pCi/m3 Air Charcoal 672520015 6/18/2024 lodine-131 5.56E-03 1.09E-02 3.86E-02 pCi/m3 Air Charcoal 673285015 6/25/2024 lodine-131

-6.48E-03 1.36E-02 4.26E-02 pCi/m3 Air Charcoal 674236015.

7/2/2024 lodine-131 1.20E-02 1.03E-02 4.04E-02 pCi/m3 Air Charcoal 675355015 7/9/2024 lodine-131 1.11E-02 1.00E-02 4.12E-02 pCi/m3 Air Charcoal 676443015 7/16/2024 lodine-131

-1.06E-02 1.35E-02 4.07E-02 pCi/m3 Air Charcoal 677643015 7/23/2024 lodine-131 8.19E-02 1.66E-01 6.00E-01 pCi/m3 Air Charcoal 678791015 7/30/2024 lodine-131 2.23E-03 1.71E-02 5.66E-02 pCi/m3 Air Charcoal 679919015 8/6/2024 lodine-131 3.05E-03 1.56E-02 5.33E002 pCi/m3 Air Charcoal 681151015 8/13/2024 lodine-131

-4.58E-03 1.38E-02 4.26E-02 pCi/m3 Air Charcoal 682299015 8/20/2024 lodine-131

-5.22E-03 4.86E-03 1.22E-02 pCi/m3 Air Charcoal 683273015 8/27/2024 lodine-131

-2.46E-03 9.25E-03 2.93E-02 pCi/m3 Air Charcoal 684114015 9/3/2024 lodine-131

-5.12E-03 8.98E-03 2.80E-02 pCi/m3 Air Charcoal 685520013 9/10/2024 lodine-131 2.75E-02 1.88E-02 4.0SE-02 pCi/m3 Air Charcoal 686609015 9/17/2024 lodine-131

-3.41E-03 4.55E-03 1.28E-02 pCi/m3 Air Charcoal 687551015 9/24/2024 lodine-131

-3.82E-03 1.44E-02 4.42E-02 pCi/m3 Air Charcoal 690029015 10/8/2024 lodine-131 2.21E-02 1.04E-02 4.84E-02 pCi/m3

Annual Environmental Operating Report I Y~AR: 2024 I Page 37 of 138 Company: Vistra Corp J Comanche Peak Nuclear Power Plant Air Sample Location A-1 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 690778015 10/15/2024 lodine-131

-5.85E-03 1.06E-02 3.22E-02 pCi/m3 Air Charcoal 691848015 10/22/2024 lodine-131

-3.56E-03 6.25E-03 1.94E-02 pCi/m3 Air Charcoal 693027015 10/29/2024 lodine-131 1.92E-03 8.SlE-03 2.98E-02 pCi/m3 Air Charcoal 694334015 11/5/2024 lodine-131

-1.llE-02 7.26E-03 1.81E-02 pCi/m3 Air Charcoal 695643015 11/12/2024 lodine-131

-1.03E-02 9.64E-03 2.65E-02 pCi/m3 Air Charcoal 696957015 11/19/2024 lodine-131

-1.41E-02 1.0SE-02 2.55E-02 pCi/m3 Air Charcoal 698137015 11/26/2024 lodine-131 7.93E-03 8.08E-03 2.98E-02 pCi/m3 Air Charcoal 699161015 12/3/2024 lodine-131

-2.S0E-02 1.66E-02 4.43E-02 pCi/m3 Air Charcoal 700156015 12/10/2024 lodine-131

-3.98E-03 1.37E-02 4.47E-02 pCi/m3 Air Charcoal 701439015 12/17/2024 Iodine-131

-2.58E-04 7.97E-03 2.68E-02 pCi/m3 Air Charcoal 702177015 12/23/2024 lodine-131 1.02E-02 1.16E-02 4.35E-02 pCi/m3 Air Charcoal 703336015 12/31/2024 lodine-131

-1.16E-02 2.65E-02 7.52E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 J Page 38 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-1 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 650472007 1/2/2024 BETA 4.58E-02 2.76E-03 3.06E-03 pCi/m3 Air Particulate 651480007 1/9/2024 BETA 5.41E-02 2.77E-03 2.55E-03 pCi/m3 Air Particulate 652168007 1/16/2024 BETA 5.38E-02 2.74E-03 2.48E-03 pCi/m3 Air Particulate 652769007 1/23/2024 BETA 5.16E-02 2.65E-03 2.46E-03 pCi/m3.

Air Particulate 653673007 1/30/2024 BETA 4.36E-02 2.47E-03 2.47E-03 pCi/m3 Air Particulate 654638007 2/6/2024 BETA 4.39E-02 2.S0E-03 2.47E-03 pCi/m3 Air Particulate 655415007 2/13/2024 BETA 3.46E-02 2.20E-03 2.35E-03 pCi/m3 Air Particulate 656171007 2/20/2024 BETA 4.83E-02 2.63E-03 2.45E-03 pCi/m3 Air Particulate 657034007 2/27/2024 BETA 4.48E-02 2.52E-03 2.51E-03 pCi/m3 Air Particulate 659140007 3/12/2024 BETA 5.04E-02 2.78E-03 2.52E-03 pCi/m3 Air Particulate 659692007 3/19/2024 BETA 3.91E-02 2.36E-03 2.43E-03 pCi/m3 Air Particulate 660512007 3/26/2024 BETA 3.48E-02 2.21E-03 2.33E-03 pCi/m3 Air Particulate 662103007 4/2/2024 BETA 4.27E-02 2.41E-03 2.20E-03 pCi/m3 Air Particulate 662643007 4/9/2024 BETA 3.38E-02 2.20E-03.

2.45E-03 pCi/m3 Air Particulate 663750007 4/16/2024 BETA 3.27E-02 2.13E-03 2.28E-03 pCi/m3 Air Particulate 664746007 4/23/2024 BETA 3.99E-02 2.41E-03 2.44E-03 pCi/m3 Air Particulate 665753007 4/30/2024 BETA 3.29E-02 2.16E-03 2.27E-03 pCi/m3 Air Particulate 667499007 5/7/2024 BETA 2.84E-02 2.03E-03 2.35E-03 pCi/m3 Air Particulate 667922007 5/14/2024 BETA 4.47E-02 2.46E-03 2.30E-03 pCi/m3 Air Particulate 668704007 5/21/2024 BETA 4.35E-02 2.45E-03 2.25E-03 pCi/m3 Air Particulate 669507007 5/28/2024 BETA 3.78E-02 2.29E-03 2.28E-03 pCi/m3 Air Particulate 670356007 6/4/2024 BETA 3.88E-02 2;32E-03 2.38E-03 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 39 of 138

- - - - - - - - ~

Company: Vistra Corp Comanche Peak Nuclear Power Plant

Air Sample Location A-1 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 671436007 6/11/2024 BETA 3.37E-02 2.20E-03 2.35E-03 pCi/m3 Air Particulate 672520007 6/18/2024 BETA 3.44E-02 2.19E-03 2.30E-03 pCi/m3 Air Particulate 673285007 6/21/2024 BETA 2.45E-02 3.72E-03 2.25E-03 pCi/m3 Air Particulate 674236007 7/2/2024 BETA 2.61E-02 1.99E-03 2.47E-03 pCi/m3 Air Particulate 675355007 7/9/2024 BETA 2.94E-02 2.09E-03 2.33E-03 pCi/m3 Air Particulate 676443007 7/16/2024 BETA 3.47E-02 2.22E-03 2.30E-03 pCi/m3 Air Particulate 677643007 7/23/2024 BETA 7.62E-03 7.99E-04 1.24E-03 pCi/m3 Air Particulate 678791007 7/30/2024 BETA 2.56E-02 1.95E-03 2.26E-03 pCi/m3 Air Particulate 679919007 8/2/2024 BETA 4.19E-02 2.45E-03 2.40E-03 pCi/m3 Air Particulate 681151007 8/13/2024 BETA 5.22E-02 2.73E-03 2.53E-03 pCi/m3 Air Particulate 682299007 8/20/2024 BETA 2.58E-02 1.93E-03 2.39E-03 pCi/m3 Air Particulate 683273007 8/27/2024 BETA 3.56E-02 2.25E-03 2.50E-03 pCi/m3 Air Particulate 684114007 9/3/2024 BETA 2.32E-02 1.87E-03 2.44E-03 pCi/m3 Air Particulate 685520006 9/3/2024 BETA 3.84E-02 2.36E-03 2.46E-03 pCi/m3 Air Particulate 686609007 9/17/2024 BETA 2.77E-02 2.03E-03 2.39E-03 pCi/m3 Air Particulate 687551007 9/24/2024 BETA 3.14E-02 2.38E-03 2.96E-03 pCi/m3 Air Particulate 690029007 10/8/2024 BETA 4.68E-02 2.59E-03 2.49E-03 pCi/m3 Air Particulate 690778007 10/15/2024 BETA 4.81E-02 2.58E-03 2.39E-03 pCi/m3 Air Particulate 691848007 10/22/2024 BETA 3.40E-02 2.19E-03 2.28E-03 pCi/m3 Air Particulate 693027007 10/29/2024 BETA 4.24E-02 4.85E-03 2.36E-03 pCi/m3 Air Particulate 694334007 11/5/2024 BETA 3.0lE-02 2.07E-03 2.32E-03 pCi/m3 Air Particulate 695643007 11/1/2024 BETA 3.49E-02 2.23E-03 2.38E-03 pCi/rri3

Annual Environmental Operating_ Report J

YEAR: 2024 J

Page 40 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant Air Sample Location A-1 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 696957007 11/12/2024 BETA 3.80E-02 2.36E-03 2.40E-03 pCi/m3 Air Particulate 698137007 11/26/2024 BETA 3.62E-02 2.23E-03 2.30E-03 pCi/m3 Air Particulate 699161007 12/3/2024 BETA 4.53E-02 2.65E-03 2.84E-03 pCi/m3 Air Particulate 700156007 12/10/2024 BETA 8.34E-02 3.31E-03 2.44E-03 pCi/m3 Air Particulate 701439007 12/17/2024 BETA 2.53E-02 1.92E-03 2.41E-03 pCi/m3 Air Particulate 702177007 12/23/2024 BETA 6.04E-02 3.20E-03 3.20E-03 pCi/m3 Air Particulate 703336007 12/31/2024 BETA 7.69E-02 5.l0E-03 6.04E-03 pCi/m3 Air Sample Location A-1 Air Quarterly Composite Gamma Spectroscopy Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 665488007 3/26/2024 Cesium-134

-2.llE-04 1.77E-04 4.79E-04 pCi/m3 Air Particulate 665488007 3/26/2024 cesium-137

-1.36E-04 1.50E-04 4.35E-04 pCi/m3 Air Particulate 678485007 5/10/2024 Cesium-134 2.09E-04 2.23E-04 6.0SE-04 pCi/m3 Air Particulate 678485007 5/10/2024 Cesium-137 1.32E-04 1.46E-04 4.99E-04 pCi/m3 Air Particulate 693204007 9/24/2024 Cesium-134 6.56E-06 1.42E-04 4.61E-04 pCi/m3 Air Particulate 693204007 9/24/2024 Cesium-137 0.00E+00 1.38E-04 4.54E-04 pCi/m3 Air Particulate 706294007 12/23/2024 Cesium-134 2.78E-04 1.69E-04 6.39E-04 pCi/m3 Air Particulate 706294007 12/23/2024 Cesium-137 5.54E-05 1.37E-04 4.67E-04 pCi/m3

Annual Environmental Operating Report J

YEAR: 2024 J

Page 41 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant Air Sample Location A-2 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 650472016 1/2/2024 lodine-131 2.59E-03 7.22E-03 2.48E-02 pCi/m3 Air Charcoal 651480016 1/9/2024 lodine-131

-6.19E-04 4.24E-03 1.41E-02 pCi/m3 Air Charcoal 652168016 1/16/2024 lodine-131 7.02E-03 3.35E-03 1.32E-02 pCi/m3 Air Charcoal 652769016 1/23/2024 lodine-131

-2.42E-03 2.78E-03 8.16E-03 pCi/m3 Air Charcoal 653673016 1/30/2024 lodine-131

-1.76E-03 2.44E-03 6.63E-03 pCi/m3 Air Charcoal 654638016 2/6/2024 lodine-131

-2.51E-03 3.84E-03 1.24E-02 pCi/m3 Air Charcoal 655415016 2/13/2024 lodine-131

-1.68E-03 3.46E-03 1.llE-02 pCi/m3 Air Charcoal 656171016 2/20/2024 Jodine-131 8.47E-03 4.69E-03 1.87E-02 pCi/m3 Air Charcoal 657034016 2/27/2024 lodine-131

-6.93E-03 4.99E-03 1.44E-02 pCi/m3 Air Charcoal 657989016 3/5/2024 lodine-131 2.72E-03 7.73E-03 2.65E-02 pCi/m3 Air Charcoal 659140016 3/12/2024 lodine-131 1.81E-03 5.28E-03 1.88E-02 pCi/m3 Air Charcoal 659692016 3/19/2024 lodine-131

-6.14E-03 7.52E-03 2.37E-02 pCi/m3 Air Charcoal 660512016 3/26/2024 lodine-131

-6.71E-03 7.37E-03 2.28E-02 pCi/m3 Air Charcoal 662103016 4/2/2024 lodine-131 5.46E-03 3.08E-03 1.25E-02 pCi/m3 Air Charcoal 662643016 4/9/2024 lodine-131 1.59E-02 5.lBE-03 2.00E-02 pCi/m3 Air Charcoal 663750016 4/16/2024 lodine-131 2.0lE-02 1.41E-02 5.26E-02 pCi/m3 Air Charcoal 664746016 4/23/2024 lodine-131.

5.0lE-03 7.llE-03 2.56E-02 pCi/m3 Air Charcoal 665753016 4/30/2024 lodine-131 1.47E-02 1.18E-02 4.27E-02 pCi/m3 Air Charcoal 667499016 5/7/2024 lodine-131

-7.87E-03 8.08E-03 2.53E-02 pCi/m3 Air Charcoal 667922016 5/14/2024 lodine-131 5.44E-03 6.17E-03 2.30E-02 pCi/m3 Air Charcoal 668704016 5/21/2024 lodine-131 2.70E-03 7.69E-03 2.59E-02 pCi/m3 Air Charcoal 669507016 5/28/2024 lodine-131 3.90E-03 9.05E-03 3.12E-02 pCi/m3 Air Charcoal 670356016 6/4/2024 lodine-131 5.SOE-04 6.93E-03 2.35E-02 pCi/m3 Air Charcoal 671436016 6/11/2024 lodine-131 4.03E-03 1.12E-02 3.69E-02 pCi/m3 Air Charcoal 672520016 6/18/2024 lodine-131 1.32E-02 1.09E-02 2.24E-02 pCi/m3 Air Charcoal 673285016 6/25/2024 lodine-131 2.30E-02 1.31E-02 5.37E-02 pCi/m3 Air Charcoal 674236016 7/2/2024 lodine-131 2.15E-02 1.44E-02 5.72E-02 pCi/m3 Air Charcoal 675355016 7/9/2024 lodine-131 3.69E-03 1.09E-02 3.99E-02 pCi/m3

--~~-v--*,-*-***-..,.~*-**~*- *-*~

Annual Environmental Operating Report I YEAR: 2024 I Page 42 of 138 Company: Vistra Corp

-7 Comanche Peak Nuclear Power Plant Air Sample Location A-2 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 676443016 7/16/2024 lodine-131 2.18E-02 1.62E-02 6.29E-02 pCi/m3 Air Charcoal 677643016 7/23/2024 lodine-131

-5.0lE-03 1.SlE-02 4.89E-02 pCi/m3 Air Charcoal 678791016 7/30/2024 lodine-131

-2.73E-02 1.89E-02 4.58E-02 pCi/m3 Air Charcoal 679919016 8/6/2024 lodine-131 9.87E-03 1.60E-02 5.82E-02 pCi/m3 Air Charcoal 681151016 8/13/2024 lodine-131 2.76E-03 6.70E-03 2.44E-02 pCi/m3 Air Charcoal 682299016 8/20/2024 lodine-131 4.54E-03 6.45E-03 2.25E-02 pCi/m3 Air Charcoal 683273016 8/27/2024 lodine-131 5.44E-03 1.06E-02 3.75E-02 pCi/m3 Air Charcoal 684114016 9/3/2024 lodine-131

-2.46E-03 9.79E-03 3.13E-02 pCi/m3 Air Charcoal 685520014 9/10/2024 lodine-131

-2.23E-03 1.03E-02 3.39E-02 pCi/m3 Air Charcoal 686609016 9/17/2024 lodine-131

-1.35E-02 8.52E-03 2.0SE-02 pCi/m3 Air Charcoal 687551016 9/24/2024 lodine-131 2.11E-03 1.34E-02 4.64E-02 pCi/m3 Air Charcoal 688665016 10/1/2024 lodine-131

-2.44E-02 1.14E-02 2.45E-02 pCi/m3 Air Charcoal 690029016 10/8/2024 lodine-131 4.23E-03 1.75E-02 5.83E-02 pCi/m3 Air Charcoal 690778016 10/15/2024 lodine-131

-2.0lE-02 1.24E-02 3.60E-02 pCi/m3 Air Charcoal 691848016 10/22/2024 lodine-131

-1.43E-02 9.20E-03 2.18E-02 pCi/m3 Air Charcoal 693027016 10/29/2024 lodine-131

-5.58E-03 7.52E-03 2.12E-02 pCi/m3 Air Charcoal 694334016 11/5/2024 lodine-131

-7.90E-03 7.56E-03 1.90E-02 pCi/m3 Air Charcoal 695643016 11/12/2024 Iodine-131 1.88E-02 1.S0E-02 5.65E-02 pCi/m3 Air Charcoal 696957016 11/19/2024 lodine-131 1.25E-02 1.37E-02 5.17E-02 pCi/m3 Air Charcoal 698137016 11/26/2024 Iodine-131 3.95E-03 7.12E-03 2.S0E-02 pCi/m3 Air Charcoal 699161016 12/3/2024 Iodine-131

-5.40E-03 1.llE-02 3.42E-02 pCi/m3 Air Charcoal 700156016 12/10/2024 lodine-131 9.43E-03 1.73E-02 6.19E-02 pCi/m3 Air Charcoal 701439016 12/17/2024 lodine-131

-3.85E-03 1.07E-02 3.34E-02 pCi/m3 Air Charcoal 702177016 12/23/2024 lodine-131

-1.55E-02 1.94E-02 5.97E-02 pCi/m3 Air Charcoal 703336016 12/31/2024 lodine-131 1.42E-02 2.SlE-02 6.76E-02 pCi/m3 Air Charcoal 703311016 1/7/2025 lodine-131 4.37E-03 1.96E-02 5.36E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Pa_g_e 43 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-2 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 650472008 1/2/2024 BETA 6.06E-02 3.14E-03 2.97E-03 pCi/m3 Air Particulate 651480008 1/9/2024 BETA 6.21E-02 2.91E-03 2.61E-03 pCi/m3 Air Particulate 652168008 1/16/2024 BETA 6.13E-02 2.88E-03 2.58E-03 pCi/m3 Air Particulate 652769008 1/23/2024 BETA 4.66E-02

2.58E-03 2.58E-03 pCi/m3 Air Particulate 653673008 1/30/2024 BETA 4.41E-02 2.51E-03 2.56E-03 pCi/m3 Air Particulate 654638008 2/6/2024 BETA 4.12E-02 2.39E-03 2.39E-03 pCi/m3 Air Particulate 655415008 2/13/2024 BETA 3.79E-02 2.34E-03 2.57E-03 pCi/m3 Air Particulate 656171008 2/20/2024 BETA 4.53E-02 2.50E-03 2.38E-03 pCi/m3 Air Particulate 657034008 2/27/2024 BETA 4.95E-02 2.62E-03 2.39E-03 pCi/m3 Air Particulate 657989008 3/5/2024 BETA 4.34E-02 2.45E-03 2.28E-03 pCi/m3 Air Particulate 659140008 3/12/2024 BETA 3.95E-02 2.34E-03 2.37E-03 pCi/m3 Air Particulate 659692008 3/19/2024 BETA 4.21E-02 2.48E-03 2.59E-03 pCi/m3 Air Particulate 660512008 3/26/2024 BETA 3.90E-02 2.33E-03 2.24E-03 pCi/m3 Air Particulate 662103008 4/2/2024 BETA 3.63E-02 2.28E-03*

2.41E-03 pCi/m3 Air Particulate 662643008 4/9/2024 BETA 3.39E-02 2.20E-03 2.25E-03 pCi/m3 Air Particulate 663750008 4/16/2024 BETA 3.67E-02 2.25E-03 2.28E-03 pCi/m3 Air Particulate 664746008 4/23/2024 BETA 3.93E-02 2.37E-03 2.31E-03 pCi/m3 Air Particulate 665753008 4/30/2024 BETA 2.91E-02 2.03E-03 2.39E-03 pCi/m3 Air Particulate 667499008 5/7/2024 BETA 2.84E-02 2.04E-03 2.29E-03 pCi/m3 Air Particulate 667922008 5/14/2024 BETA 3.76E-02 2.28E-03 2.23E-03 pCi/m3 Air Particulate 668704008 5/21/2024 BETA 4.20E-02 2.45E-03 2.46E-03 pCi/m3 Air Particulate 669507008 5/28/2024 BETA 4.04E-02 2.39E-03 2.45E-03 pCi/m3 Air Particulate 670356008 6/4/2024 BETA 2.47E-02 1.93E-03 2.35E-03 pCi/m3 Air Particulate 671436008 6/11/2024 BETA 5.90E-02 2.88E-03 2.49E-03 pCi/m3 Air Particulate 672520008 6/18/2024 BETA 3.43E-02 2.22E-03 2.44E-03 pCi/m3 Air Particulate 673285008 6/25/2024 BETA 2.79E-02 3.90E-03 2.35E-03 pCi/m3 Air Particulate 674236008 7/2/2024 BETA 2.57E-02 1.98E-03 2.45E-03 pCi/m3 n***--

~ ** -

HO' *-*---

Annual Environmental OperatinaB.eport I YEAR: 2024 I Page 44 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant Air Sample Location A-2 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 675355008 7/9/2024 BETA 3.18E-02 2.14E-03 2.45E-03 pCi/m3 Air Particulate 676443008 7/16/2024 BETA 3.37E-02 2.23E-03 2.49E-03 pCi/m3 Air Particulate 677643008 7/23/2024 BETA 3.81E-02 2.31E-03 2.33E-03 pCi/m3 Air Particulate 678791008 7/30/2024 BETA 2.15E-02 1.80E-03 2.39E-03 pCi/m3 Air Particulate 679919008 8/6/2024 BETA 4.13E-02 2.42E-03 2.35E-03 pCi/m3 Air Particulate 681151008 8/13/2024 BETA 5.17E-02 2.69E-03 2.37E-03 pCi/m3 Air Particulate 682299008 8/20/2024 BETA 3.21E-02 2.l0E-03 2.13E-03 pCi/m3 Air Particulate 683273008 8/27/2024 BETA 4.13E-02 2.42E-03 2.46E-03 pCi/m3 Air Particulate 684114008 9/3/2024 BETA 2.27E-02 1.88E-03 2.53E-03 pCi/m3 Air Particulate 685520007 9/10/2024 BETA 4.38E-02 2.48E-03 2.35E-03 pCi/m3 Air Particulate 686609008 9/17/2024 BETA 2.95E-02 2.07E-03 2.35E-03 pCi/m3 Air Particulate 687551008 9/24/2024 BETA 2.89E-02 2.00E-03 2.31E-03 pCi/m3 Air Particulate 688665008 10/1/2024 BETA 4.42E-02 2.49E-03 2.42E-03 pCi/m3 Air Particulate 690029008 10/8/2024 BETA 5.lSE-02 2.67E-03 2.31E-03 pCi/m3 Air Particulate 690778008 10/15/2024 BETA 5.65E-02 2.75E-03 2.41E-03 pCi/m3 Air Particulate 691848008 10/22/2024 BETA 3.42E-02 2.23E-03 2.39E-03 pCi/m3 Air Particulate 693027008 10/29/2024 BETA 4.33E-02 4.85E-03 2.43E-03 pCi/m3 Air Particulate 694334008 11/5/2024 BETA 3.18E-02 2.15E-03 2.43E-03 pCi/m3 Air Particulate 695643008 11/12/2024 BETA 4.03E-02 2.35E-03 2.45E-03 pCi/m3 Air Particulate 696957008 11/19/2024 BETA 3.87E-02 2.37E-03 2.36E-03 pCi/m3 Air Particulate 698137008 11/26/2024 BETA 4.26E-02 2.44E-03 2.41E-03 pCi/m3 Air Particulate 699161008 12/3/2024

BETA 5.89E-02 2.85E-03 2.56E-03 pCi/m3 Air Particulate 700156008 12/10/2024 BETA 4.83E-02 2.59E-03 2.55E-03 pCi/m3 Air Particulate 701439008 12/17/2024 BETA 2.99E-02 2.09E-03 2.53E-03 pCi/m3 Air Particulate 702177008 12/23/2024 BETA 7.21E-02 3.45E-03 2.91E-03 pCi/m3 Air Particulate 703336008 12/31/2024 BETA 5.25E-02 2.47E-03 2.l0E-03 pCi/ m3 Air Particulate 703311008 1/7/2025 BETA 4.02E-02 2.38E-03 2.46E-03 pCi/m3

Annual Environmental O~perating Report I YEAR: 2024 I Page 45 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air S

-- - le Location A-2 Air Quarterly G J

iteG s :;pectrosco ov Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 665488008 3/26/2024 Cesium-134 1.13E-04 1.48E-04 5.11E-04 pCi/m3 Air Particulate 665488008 3/26/2024 Cesium-137 1.48E-04 1.46E-04 5.02E-04 pCi/m3 Air Particulate 678485008 5/10/2024 Cesium-134

-8.36E-06 1.62E-04 5.llE-04 pCi/m3 Air Particulate 678485008 5/10/2024 Cesium-137 7.88E-06 1.31E-04 4.24E-04 pCi/m3 Air Particulate 693204008 9/24/2024 Cesium-134 1.81E-04 2.24E-04 8.15E-04 pCi/m3 Air Particulate 693204008 9/24/2024 Cesium-137 1.52E-04 1.63E-04 5.84E-04 pCi/m3 Air Particulate 706294008 12/23/2024 Cesium-134 3.93E-04 1.71E-04 4.70E-04 pCi/m3 Air Particulate 706294008 12/23/2024 Cesium-137 1.67E-04 1.65E-04 5.88E-04 pCi/m3 Air Sample Location A-3 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 650472014 1/2/2024 lodine-131 7.30E-03 1.05E-02 3.68E-02 pCi/m3 Air Charcoal 651480014 1/9/2024 lodine-131

-3.78E-03 4.62E-03 1.42E-02 pCi/m3 Air Charcoal 652168014 1/16/2024 lodine-131 3.67E-03 3.17E-03 1.20E-02 pCi/m3 Air Charcoal 652769014 1/23/2024 lodine-131 4.79E-04 3.85E-03 1.28E-02 pCi/m3 Air Charcoal 653673014 1/30/2024 lodine-131 2.98E-03 2.51E-03 9.18E-03 pCi/m3 Air Charcoal 654638014 2/6/2024 Iodine-131

-5.94E-03 4.29E-03 1.22E-02 pCi/m3 Air Charcoal 655415014 2/13/2024 lodine-131 5.03E-03 4.S0E-03 1.63E-02 pCi/m3 Air Charcoal 656171014 2/20/2024 lodine-131

-1.61E-03 6.00E-03 1.92E-02 pCi/m3 Air Charcoal 657034014 2/27/2024 lodine-131 5.26E-03 5.47E-03 1.88E-02 pCi/m3 Air Charcoal 657989014 3/5/2024 lodine-131 2.49E-03 6.39E-03 2.17E-02 pCi/m3 Air Charcoal 659140014 3/12/2024 lodine-131

-1.15E-02 7.05E-03 1.91E-02 pCi/m3 Air Charcoal 659692014 3/19/2024 lodine-131

-2.13E-03 4.55E-03 1.47E-02 pCi/m3 Air Charcoal 660512014 3/26/2024 lodine-131

-4.02E-03 4.0SE-03 1.23E-02 pCi/m3 Air Charcoal 662103014 4/2/2024 lodine-131 6.31E-03 4.37E-03 1.62E-02 pCi/m3 Air Charcoal 662643014 4/9/2024 lodine-131

-9.93E-03 6.72E-03 1.86E-02 pCi/m3 Air Charcoal 663750014 4/16/2024 lodine-131 1.85E-02 1.65E-02 3.B0E-02 pCi/m3

Annual Environmental Operating Report J

YEAR: 2024 J

Page 46 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-3 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 664746014 4/23/2024 lodine-131 4.51E-03 1.02E-02 3.41E-02 pCi/m3 Air Charcoal 665753014 4/30/2024 lodine-131 5.90E-03 1.03E-02 3.45E-02 pCi/m3 Air Charcoal 667499014 5/7/2024 lodine-131 1.14E-02 7.71E-03 2.91E-02 pCi/m3 Air Charcoal 667922014 5/14/2024 lodine-131 0.00E+00 6.65E-03 2.24E-02 pCi/m3 Air Charcoal 668704014 5/21/2024 lodine-131 9.S0E-04 6.58E-03 2.28E-02 pCi/m3 Air Charcoal 669507014 5/28/2024 lodine-131

-1.08E-02 1.07E-02 3.39E-02 pCi/m3 Air Charcoal 670356014 6/4/2024 lodine-131

-2.51E-02 6.02E-03 2.03E-02 pCi/m3 Air Charcoal 671436014 6/11/2024 lodine-131 4.79E-03 1.26E-02 4.31E-02 pCi/m3 Air Charcoal 672520014 6/18/2024 lodine-131

-1.02E-02 8.90E-03 2.63E-02 pCi/m3 Air Charcoal 673285014 6/25/2024 lodine-131

-2.48E-02 1.41E-02 3.66E-02 pCi/m3 Air Charcoal 674236014 7/2/2024 lodine-131

-1.67E-02 1.45E-02 3.97E-02 pCi/m3 Air Charcoal 675355014 7/9/2024 lodine-131 2.45E-02 1.30E-02 5.59E-02 pCi/m3 Air Charcoal 676443014 7/16/2024 lodine-131

-4.94E-03 1.50E-02 4.72E-02 pCi/m3 Air Charcoal 677643014 7/23/2024 lodine-131

-3.09E-02 1.56E-02 2.64E-02 pCi/m3 Air Charcoal 678791014 7/30/2024 lodine-131 1.47E-02 1.63E-02 6.24E-02 pCi/m3 Air Charcoal 679919014 8/6/2024 lodine-131

-3.35E-02 1.44E-02 2.28E-02 pCi/m3 Air Charcoal 681151014 8/13/2024 lodine-131 1.27E-02 9.45E-03 3.77E-02 pCi/m3 Air Charcoal 682299014 8/20/2024 lodine-131

-7.44E-03 5.20E-03 1.36E-02 pCi/m3 Air Charcoal 683273014 8/27/2024 Iodine-131 7.06E-03 7.21E-03 2.63E-02 pCi/m3 Air Charcoal 684114014 9/3/2024 lodine-131 2.06E-03 8.69E-03 2.99E-02 pCi/m3 Air Charcoal 685520012 9/10/2024 lodine-131

-3.65E-04 1.08E-02 3.58E-02 pCi/m3 Air Charcoal 686609014 9/17/2024 lodine-131

-2.72E-03 8.70E-03 2.72E-02 pCi/m3 Air Charcoal 687551014 9/24/2024 lodine-131

-9.40E-03 9.57E-03 2.69E-02 pCi/m3 Air Charcoal 688665014 10/1/2024 lodine-131 4.10E-03 1.64E-02 5.72E-02 pCi/m3 Air Charcoal 690029014 10/8/2024 lodine-131 7.57E-03 1.25E-02 4.64E-02 pCi/m3 Air Charcoal 690778014 10/15/2024 lodine-131 7.37E-03 1.13E-02 4.14E-02 pCi/m3 Air Charcoal 691848014 10/22/2024 lodine-131 8.38E-03 1.00E-02 3.58E-02 pCi/m3 Air Charcoal 693027014 10/29/2024 lodine-131

-5.50E-03 5.42E-03 1.52E-02

pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 47 of 138 Company: Vistra Corp

~

Comanche Peak Nuclear Power Plant Air Sample Location A-3 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 694334014 11/5/2024 lodine-131

-1.99E-03 1.15E-02 3.81E-02 pCi/m3 Air Charcoal 695643014 11/12/2024 lodine-131 7.56E-03 1.73E-02 5.59E-02 pCi/m3 Air Charcoal 696957014 11/19/2024 Iodine-131

-6.59E-03 1.59E-02 5.08E-02 pCi/m3 Air Charcoal 698137014 11/26/2024 lodine-131 6.49E-03 7.77E-03 2.95E-02 pCi/m3 Air Charcoal 699161014 12/3/2024 lodine-131 8.87E-03 1.57E-02 5.79E-02 pCi/m3 Air Charcoal 700156014 12/10/2024 lodine-131 1.06E-02 1.72E-02 6.14E-02 pCi/m3 Air Charcoal 701439014 12/17/2024 lodine-131

-1.0BE-02 1.0lE-02 2.46E-02 pCi/m3 Air Charcoal 702177014 12/23/2024 lodine-131

-6.0lE-03 1.37E-02 4.25E-02 pCi/m3 Air Charcoal 703336014 12/31/2024 lodine-131 2.02E-02 2.61E-02 7.00E-02 pCi/m3 Air Charcoal 703311014 1/7/2025 lodine-131 5.87E-03 2.70E-02 6.76E-02 pCi/m3 Air Sample Location A-3 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 650472006 1/2/2024 BETA 4.39E-02 2.73E-03 2.96E-03 pCi/m3 Air Particulate 651480006 1/9/2024 BETA 4.09E-02 2.44E-03 2.54E-03 pCi/m3 Air Particulate 652168006 1/16/2024 BETA 4.13E-02 2.43E-03 2.55E-03 pCi/m3 Air Particulate 652769006 1/23/2024 BETA 4.58E-02 2.SOE-03 2.36E-03 pCi/m3 Air Particulate 653673006 1/30/2024 BETA 4.57E-02 2.SOE-03 2.37E-03 pCi/m3 Air Particulate 654638006 2/6/2024 BETA 5.22E-02 2.72E-03 2.58E-03 pCi/m3 Air Particulate 655415006 2/13/2024 BETA 3.74E-02 2.29E-03 2.58E-03 pCi/m3 Air Particulate 656171006 2/20/2024 BETA 4.85E-02 2.65E-03 2.64E-03 pCi/m3 Air Particulate 657034006 2/27/2024 BETA 4.90E-02 2.58E-03 2.26E-03 pCi/m3 Air Particulate 657989006 3/5/2024 BETA 4.65E-02 2.56E-03 2.35E-03 pCi/m3 Air Particulate 659140006 3/12/2024 BETA 4.06E-02 2.42E-03 2.57E-03 pCi/m3 Air Particulate 659692006 3/19/2024 BETA 3.SOE-02 2.32E-03 2.43E-03 pCi/m3 Air Particulate 660512006 3/26/2024 BETA 3.49E-02 2.25E-03 2.33E-03 pCi/m3 Air Particulate 662103006 4/2/2024 BETA 3.91E-02 2.32E-03 2.39E-03 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 48 of 138 Company: Vistra Corp

~7 Comanche Peak Nuclear Power Plant Air Sample Location A-3 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 662643006 4/9/2024 BETA 3.60E-02 2.30E-03 2.41E-03 pCi/m3 Air Particulate 663750006 4/16/2024 BETA 3.97E-02 2.37E-03 2.38E-03 pCi/m3 Air Particulate 664746006 4/23/2024 BETA 3.70E-02 2.28E-03 2.22E-03 pCi/m3 Air Particulate 665753006 4/30/2024 BETA 3.96E-02 2.37E-03 2.43E-03 pCi/m3

Air Particulate 667499006 5/7/2024 BETA 3.26E-02 2.17E-03 2.34E-03 pCi/m3 Air Particulate 667922006 5/14/2024 BETA 3.48E-02 2.22E-03 2.31E-03 pCi/m3 Air Particulate 668704006 5/21/2024 BETA 3.96E-02 2.34E-03 2.29E-03 pCi/m3 Air Particulate 669507006 5/28/2024 BETA 3.87E-02 2.32E-03 2.37E-03 pCi/m3 Air Particulate 670356006 6/4/2024 BETA 2.77E-02 2.02E-03 2.32E-03 pCi/m3 Air Particulate 671436006 6/11/2024 BETA 3.52E-02 2.25E-03 2.53E-03 pCi/m3 Air Particulate 672520006 6/18/2024 BETA 3.72E-02 2.28E-03 2.48E-03 pCi/m3 Air Particulate 673285006 6/25/2024 BETA 3.07E-02 4.15E-03 2.40E-03 pCi/m3 Air Particulate 674236006 7/2/2024 BETA 2.65E-02 1.97E-03 2.35E-03 pCi/m3 Air Particulate 675355006 7/9/2024 BETA 3.16E-02 2.17E-03 2.50E-03 pCi/m3 Air Particulate 676443006 7/16/2024 BETA 4.20E-02 2.41E-03 2.34E-03 pCi/m3 Air Particulate 677643006 7/23/2024 BETA 4.13E-02 2.38E-03 2.27E-03 pCi/m3 Air Particulate 678791006 7/30/2024 BETA 2.85E-02 2.07E-03 2.47E-03 pCi/m3 Air Particulate 679919006 8/6/2024 BETA 4.65E-02 2.54E-03 2.48E-03 pCi/m3 Air Particulate 681151006 8/13/2024 BETA 6.61E-02 2.98E-03 2.21E-03 pCi/m3 Air Particulate 682299006 8/20/2024 BETA 4.lOE-02 2.40E-03 2.33E-03 pCi/m3 Air Particulate 683273006 8/27/2024 BETA 5.04E-02 2.64E-03 2.37E-03 pCi/m3 Air Particulate 684114006 9/3/2024 BETA 2.72E-02 2.00E-03 2.49E-03 pCi/m3 Air Particulate 685520005 9/10/2024 BETA 4.66E-02 2.55E-03 2.39E-03 pCi/m3 Air Particulate 686609006 9/17/2024 BETA 3.73E-02 2.33E-03 2.52E-03 pCi/m3 Air Particulate 687551006 9/24/2024 BETA 3.55E-02 2.24E-03 2.36E-03 pCi/m3 Air Particulate 688665006 10/1/2024 BETA 4.94E-02 2.65E-03 2.35E-03 pCi/ m3 Air Particulate 690029006 10/8/2024 BETA 6.35E-02 2.93E-03 2.40E-03 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 49 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant Air Sample Location A-3 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 690778006 10/15/2024 BETA 6.67E-02 3.00E-03 2.32E-03 pCi/m3 Air Particulate 691848006 10/22/2024 BETA 3.21E-02 2.15E-03 2.40E-03 pCi/m3 Air Particulate 693027006 10/29/2024 BETA 5.34E-02 5.39E-03 2.43E-03 pCi/m3 Air Particulate 694334006 11/5/2024 BETA 3.41E-02 2.20E-03 2.51E-03 pCi/m3 Air Particulate 695643006 11/12/2024 BETA 4.05E-02 2.41E-03 2.55E-03 pCi/m3 Air Particulate 696957006 11/19/2024 BETA 4.56E-02 2.53E-03 2.37E-03 pCi/m3 Air Particulate 698137006 11/26/2024 BETA 4.10E-02 2.36E-03 2.41E-03 pCi/m3 Air Particulate 699161006 12/3/2024 BETA 6.51E-02 3.04E-03 2.68E-03 pCi/m3 Air Particulate 700156006 12/10/2024 BETA 5.47E-02 2.76E-03 2.51E-03 pCi/m3 Air Particulate 701439006 12/17/2024 BETA 3.33E-02 2.18E-03 2.47E-03 pCi/m3 Air Particulate 702177006 12/23/2024 BETA 6.38E-02 3.23E-03 2.94E-03 pCi/m3 Air Particulate 703336006 12/31/2024 BETA 5.42E-02 2.56E-03 2.22E-03 pCi/m3 Air Particulate 703311006 1/7/2025 BETA 4.06E-02 2.43E-03 2.58E-03 pCi/m3

- - - --*~*tJ'*- ----~*-**

......... _____ rosco1 DV AirS le L1 A-3 Air Quarterly 0

. G Spect1 Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 665488006 3/26/2024 Cesium-134 2.87E-04 1.39E-04 5.73E-04 pCi/m3 Air Particulate 665488006 3/26/2024 Cesium-137 8.38E-05 1.48E-04 5.0lE-04 pCi/m3 Air Particulate 678485006 5/10/2024 Cesium-134

-2.03E-05 1.83E-04 6.14E-04 pCi/m3 Air Particulate 678485006 5/10/2024 Cesium-137 3.53E-05 1.41E-04 4.61E-04 pCi/m3 Air Particulate 693204006 9/24/2024 Cesium-134 1.50E-04 1.64E-04 5.99E-04 pCi/m3 Air Particulate 693204006 9/24/2024 Cesium-137

-3.78E-04 1.S0E-04 3.73E-04 pCi/m3 Air Particulate 706294006 12/23/2024 Cesium-134 1.98E-05 1.66E-04 5.41E-04 pCi/m3 Air Particulate 706294006 12/23/2024 Cesium-137 2.lOE-05 1.59E-04 5.26E-04 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 50 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-4 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 650472013 1/2/2024 lodine-131 3.58E-03 6.60E-03 2.36E-02 pCi/m3 Air Charcoal 651480013 1/9/2024 lodine-131

-2.86E-04 3.69E-03 1.25E-02 pCi/m3 Air Charcoal 652168013 1/16/2024 lodine-131 1.66E-04 2.86E-03 8.93E-03 pCi/m3 Air Charcoal 652769013 1/23/2024 lodine-131

-5.25E-03 2.52E-03 6.50E-03 pCi/m3 Air Charcoal 653673013 1/30/2024 lodine-131 7.63E-03 3.32E-03 8.79E-03 pCi/m3 Air Charcoal 654638013 2/6/2024 lodine-131

-1.20E-03 4.43E-03 1.38E-02 pCi/m3 Air Charcoal 655415013 2/13/2024 lodine-131

-2.56E-03 5.0lE-03 1.64E-02 pCi/m3 Air Charcoal 656171013 2/20/2024 lodine-131

-9.45E-04 4.25E-03 1.38E-02 pCi/m3 Air Charcoal 657034013 2/27/2024 lodine-131

-1.35E-04 6.87E-03 2.29E-02 pCi/m3 Air Charcoal 657989013 3/5/2024 lodine-131

-3.34E-03 7.95E-03 2.39E-02 pCi/m3 Air Charcoal 659140013 3/12/2024 lodine-131

-1.19E-02 8.74E-03 2.72E-02 pCi/m3 Air Charcoal 659692013 3/19/2024 lodine-131 1.0lE-02 6.32E-03 2.38E-02 pCi/m3 Air Charcoal 660512013 3/26/2024 lodine-131 1.09E-03 5.75E-03 1.92E-02 pCi/m3 Air Charcoal 662103013 4/2/2024 lodine-131

-5.46E-03 4.00E-03 1.16E-02 pCi/m3 Air Charcoal 662643013 4/9/2024 lodine-131

-4.51E-04 6.09E-03 2.04E-02 pCi/m3 Air Charcoal 663750013 4/16/2024 lodine-131 2.41E-02 1.21E-02 4.77E-02 pCi/m3 Air Charcoal 664746013 4/23/2024 lodine-131 6.38E-03 8.90E-03 3.l0E-02 pCi/m3 Air Charcoal 665753013 4/30/2024 lodinc-131 7.l0E-03 1.44E-02 4.96E-02 pCi/m3 Air Charcoal 667499013 5/7/2024 Jodine-131 2.41E-02 1.65E-02 6.06E-02 pCi/m3 Air Charcoal 667922013 5/14/2024 lodine-131

-3.20E-03 7.80E-03 2.S0E-02 pCi/m3 Air Charcoal 668704013 5/21/2024 lodine-131 6.53E-03 6.70E-03 2.44E-02 pCi/m3 Air Charcoal 669507013 5/28/2024 lodine-131 2.59E-02 1.30E-02 2.82E-02 pCi/m3 Air Charcoal 670356013 6/4/2024 lodine-131

-8.49E-03 7.39E-03 1.88E-02 pCi/m3 Air Charcoal 671436013 6/11/2024 lodine-131

-6.07E-03 1.07E-02 3.40E-02 pCi/m3 Air Charcoal 672520013 6/18/2024 lodine-131

-3.16E-02 2.18E-02 4.83E-02 pCi/m3 Air Charcoal 673285013 6/25/2024 lodine-131 1.59E-03 1.18E-02 3.83E-02 pCi/m3 Air Charcoal 674236013 7/2/2024 lodine-131 3.77E-03 1.46E-02 5.0lE-02 pCi/m3 Air Charcoal 675355013 7/9/2024 lodine-131

-9.61E-03 1.00E-02 2.77E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 51 of 138 Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant Air Sample Location A-4 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 676443013 7/16/2024 lodine-131

-5.08E-03 1.87E-02 6.08E-02 pCi/m3 Air Charcoal 677643013 7/23/2024 lodine-131

-1.79E-02 1.75E-02 5.21E-02 pCi/m3 Air Charcoal 678791013 7/30/2024 lodine-131

-2.29E-02 1.79E-02 5.05E-02 pCi/m3 Air Charcoal 679919013 8/6/2024 lodine-131

-1.36E-02 1.26E-02 3.22E-02 pCi/m3 Air Charcoal 681151013 8/13/2024 lodine-131

-1.08E-03 6.49E-03 2.11E-02 pCi/m3 Air Charcoal 682299013 8/20/2024 lodine-131

-9.58E-04 5.SOE-03 1.81E-02 pCi/m3 Air Charcoal 683273013 8/27/2024 lodine-131

-6.65E-04 1.16E-02 3.35E-02 pCi/m3 Air Charcoal 684114013 9/3/2024 lodine-131 8.87E-03 8.05E-03 3.0lE-02 pCi/m3 Air Charcoal 685520011 9/10/2024 lodine-131

-1.39E-04 8.77E-03 2.95E-02 pCi/m3 Air Charcoal 686609013 9/17/2024 lodine-131 4.99E-03 7.54E-03 2.77E-02 pCi/m3 Air Charcoal 687551013 9/24/2024 lodine-131 5.99E-03 1.53E-02 5.43E-02 pCi/m3 Air Charcoal 688665013 10/1/2024 lodine-131 2.21E-03 8.46E-03 2.74E-02 pCi/m3 Air Charcoal 690029013 10/8/2024 lodine-131

-1.07E-02 1.38E-02 4.21E-02 pCi/m3 Air Charcoal 690778013 10/15/2024 lodine-131

-1.0lE-02 1.30E-02 3.94E-02 pCi/m3 Air Charcoal 691848013 10/22/2024 lodine-131

-3.37E-03 7.35E-03 2.32E-02 pCi/m3 Air Charcoal 693027013 10/29/2024 lodine-131

-9.04E-03 6.79E-03 1.60E-02 pCi/m3 Air Charcoal 694334013 11/5/2024 lodine-131

-2.54E-03 8.42E-03 2.70E-02 pCi/m3 Air Charcoal 695643013 11/12/2024

- lodine-131 1.47E-02 1.40E-02 5.22E-02 pCi/m3 Air Charcoal 696957013 11/19/2024 lodine-131 1.40E-02 1.17E-02 4.71E-02 pCi/m3 Air Charcoal 698137013 11/26/2024 lodine-131 2.18E-02 8.23E-03 3.69E-02 pCi/m3 Air Charcoal 699161013 12/3/2024 lodine-131

-1.27E-02 1.55E-02 4.60E-02 pCi/m3 Air Charcoal 700156013 12/10/2024 lodine-131 3.64E-02 2.69E-02 4.67E-02 pCi/m3 Air Charcoal 701439013 12/17/2024 lodine-131

-6.17E-03 4.98E-03 1.30E-02 pCi/m3 Air Charcoal 702177013 12/23/2024 Jodine-131 1.65E-02 1.44E-02 5.52E-02 pCi/m3 Air Charcoal 703336013 12/31/2024 lodine-131

-3.45E-03 2.51E-02 6.94E-02 pCi/m3 Air Charcoal 703311013 1/7/2025 lodine-131 2.92E-02 1.96E-02 6.51E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Pa~ge 52 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Air Sample Location A-4 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 650472005 1/2/2024 BETA 3.89E-02 2.59E-03 2.93E-03 pCi/m3 Air Particulate 651480005 1/9/2024 BETA 4.66E-02 2.56E-03 2.55E-03 pCi/m3 Air Particulate 652168005 1/16/2024 BETA 4.51E-02 2.50E-03 2.49E-03 pCi/m3 Air Particulate 652769005 1/23/2024 BETA 5.43E-02 2.74E-03 2.44E-03 pCi/m3 Air Particulate 653673005 1/30/2024 BETA 4.71E-02 2.58E-03 2.47E-03 pCi/m3 Air Particulate 654638005 2/6/2024 BETA 3.95E-02 2.37E-03 2.48E-03 pCi/m3 Air Particulate 655415005 2/13/2024 BETA 4.64E-02 2.54E-03 2.39E-03 pCi/m3 Air Particulate 656171005 2/20/2024 BETA 5.77E-02 2.81E-03 2.36E-03 pCi/m3 Air Particulate 657034005 2/27/2024 BETA 5.22E-02 2.65E-03 2.36E-03 pCi/m3 Air Particulate 657989005 3/5/2024 BETA 5.44E-02 2.78E-03 2.54E-03 pCi/m3 Air Particulate 659140005 3/12/2024 BETA 5.09E-02 2.64E-03 2.32E-03 pCi/m3 Air Particulate 659692005 3/19/2024 BETA 4.44E-02 2.51E-03 2.31E-03 pCi/m3 Air Particulate 660512005 3/26/2024 BETA 4.36E-02 2.51E-03 2.57E-03 pCi/m3 Air Particulate 662103005 4/2/2024 BETA 4.18E-02 2.42E-03 2.35E-03 pCi/m3 Air Particulate 662643005 4/9/2024 BETA 4.16E-02 2.46E-03 2.48E-03 pCi/m3 Air Particulate 663750005 4/16/2024 BETA 3.65E-02 2.29E-03 2.47E-03 pCi/m3 Air Particulate 664746005 4/23/2024 BETA 3.69E-02 2.27E-03 2.33E-03 pCi/m3 Air Particulate 665753005 4/30/2024 BETA 4.09E-02 2.36E-03 2.23E-03 pCi/m3 Air Particulate 667499005 5/7/2024 BETA 3.55E-02 2.92E-03 3.74E-03 pCi/m3 Air Particulate 667922005 5/14/2024 BETA 4.lOE-02 2.41E-03 2.38E-03 pCi/m3 Air Particulate 668704005 5/21/2024 BETA 4.0lE-02 2.39E-03 2.34E-03 pCi/m3 Air Particulate 669507005 5/28/2024 BETA 4.59E-02 2.54E-03 2.31E-03 pCi/m3 Air Particulate 670356005 6/4/2024 BETA 2.74E-02 2.04E-03 2.51E-03 pCi/m3 Air Particulate 671436005 6/11/2024 BETA 3.69E-02 2.31E-03 2.41E-03 pCi/m3 Air Particulate 672520005 6/18/2024 BETA 4.03E-02 2.38E-03 2.37E-03 pCi/m3 Air Particulate 673285005 6/25/2024 BETA 2.93E-02 4.00E-03 2.30E-03 pCi/m3 Air Particulate 674236005 7/2/2024 BETA 1.93E-02 1.72E-03 2.45E-03 pCi/m3

Annual Environmental Operating Report YEAR: 2024 Page 53 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-4 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 675355005 7/9/2024 BETA 3.51E-02 2.23E-03 2.35E-03 pCi/m3 Air Particulate 676443005 7/16/2024 BETA 3.76E-02 2.32E-03 2.37E-03 pCi/m3 Air Particulate 677643005 7/23/2024 BETA 3.72E-02 2.27E-03 2.31E-03 pCi/m3 Air Particulate 678791005 7/30/2024 BETA 2.88E-02 2.04E-03 2.34E-03 pCi/m3 Air Particulate 679919005 8/6/2024 BETA 4.40E-02 2.53E-03 3.09E-03 pCi/m3 Air Particulate 681151005 8/13/2024 BETA 5.54E-02 2.75E-03 2.45E-03 pCi/m3 Air Particulate 682299005 8/20/2024 BETA 3.59E-02 2.28E-03 2.48E-03 pCi/m3 Air Particulate 683273005 8/27/2024 BETA 4.44E-02 2.51E-03 2.50E-03 pCi/m3 Air Particulate 684114005 9/3/2024 BETA 2.82E-02 2.04E-03 2.39E-03 pCi/m3 Air Particulate 685520004 9/10/2024 BETA 4.20E-02 2.42E-03 2.39E-03 pCl/m3 Air Particulate 686609005 9/17/2024 BETA 3.59E-02 2.26E-03 2.42E-03 pCi/m3 Air Particulate 687551005 9/24/2024 BETA 3.64E-02 2.23E-03 2.26E-03 pCi/m3 Air Particulate 688665005 10/1/2024 BETA 4.88E-02 2.65E-03 2.49E-03 pCi/m3 Air Particulate 690029005 10/8/2024 BETA 5.51E-02 2.73E-03 2.45E-03 pCi/m3 Air Particulate 690778005 10/15/2024 BETA 5.97E-02 2.81E-03 2.38E-03 pCi/m3 Air Particulate 691848005 10/22/2024 BETA 3.85E-02 2.35E-03 2.34E-03 pCi/m3 Air Particulate 693027005 10/29/2024 BETA 4.88E-02 5.08E-03 2.30E-03 pCi/m3 Air Particulate 694334005 11/5/2024 BETA 3.59E-02 2.27E-03 2.43E-03 pCi/m3 Air Particulate 695643005 11/12/2024 BETA 7.74E-02 3.19E-03 2.35E-03 pCi/m3 Air Particulate 696957005 11/19/2024 BETA 4.21E-02 2.44E-03 2.53E-03 pCl/m3 Air Particulate 698137005 11/26/2024 BETA 5.llE-02 2.64E-03 2.27E-03 pCi/m3 Air Particulate 699161005 12/3/2024 BETA 6.61E-02 3.02E-03 2.67E-03 pCi/m3 Air Particulate 700156005 12/10/2024 BETA 5.17E-02 2.69E-03 2.45E-03 pCi/m3 Air Particulate 701439005 12/17/2024 BETA 3.78E-02 2.31E-03 2.40E-03 pCi/m3 Air Particulate 702177005 12/23/2024 BETA 5.97E-02 3.20E-03 3.19E-03 pCi/m3 Air Particulate 703336005 12/31/2024 BETA 4.38E-02 2.31E-03 2.35E-03 pCi/m3 Air Particulate 703311005 1/7/2025 BETA 4.07E-02 2.42E-03 2.71E-03 pCi/m3

Annual Environmental Operating Report J

YEAR: 2024 J

Page 54 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant

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_rosco PY Airs 1le Location A-4 Air Quarterly G ite G Spect1 Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 620386005 3/28/2023 Cesium-134

-6.66E-05 1.64E-04 5.34E-04 pCi/m3 Air Particulate 620386005 3/28/2023 Cesium-137

-1.17E-05 1.43E-04 4.SlE-04 pCi/m3 Air Particulate 634123005 6/20/2023 Cesium-134 1.69E-04 1.62E-04 5.99E-04 pCi/m3 Air Particulate 634123005 6/20/2023 Cesium-137 5.21E-04 2.21E-04 4.59E-04 pCi/m3 Air Particulate 643405005 9/26/2023 Cesium-134 3.lOE-04 1.68E-04 6.19E-04 pCi/m3 Air Particulate 643405005 9/26/2023 Cesium-137

-4.42E-05 1.65E-04 5.35E-04 pCi/m3 Air Particulate 653604005 12/27/2023 Cesium-134 2.02E-04 1.30E-04 4.97E-04 pCi/m3 Air Particulate 653604005 12/27/2023 Cesium-137 4.42E-05 l.12E-04 3.83E-04 pCi/m3 Air Sample Location A-5 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 650472011 1/2/2024 lodine-131

-7.70E-03 6.51E-03 1.89E-02 pCi/m3 Air Charcoal 651480011 1/9/2024 lodine-131

-5.91E-03 4.0lE-03 1.llE-02 pCi/m3 Air Charcoal 652168011 1/16/2024 lodine-131

-1.16E-03 3.73E-03 1.23E-02 pCi/m3 Air Charcoal 652769011 1/23/2024 lodine-131 2.61E-03 3.65E-03 9.25E-03 pCi/m3 Air Charcoal 653673011 1/30/2024 lodine-131 1.97E-03 1.80E-03 6.92E-03 pCi/m3 Air Charcoal 654638011 2/6/2024 lodine-131 1.89E-03 3.43E-03 1.23E-02 pCi/m3 Air Charcoal 655415011 2/13/2024 lodine-131

-3.28E-03 4.89E-03 1.SOE-02 pCi/m3 Air Charcoal 656171011 2/20/2024 lodine-131 1.29E-02 1.45E-02 2.18E-02 pCi/m3 Air Charcoal 657034011 2/27/2024 lodine-131 2.90E-03 6.14E-03 2.16E-02 pCi/m3 Air Charcoal 657989011 3/5/2024 lodine-131 6.16E-03 5.42E-03 2.00E-02 pCi/m3 Air Charcoal 659140011 3/12/2024 lodine-131

-1.68E-03 8.55E-03 2.75E-02 pCi/m3 Air Charcoal 659692011 3/19/2024 lodine-131

-1.26E-02 6.0lE-03 1.59E-02 pCi/m3 Air Charcoal 660512011 3/26/2024 lodine-131 2.69E-03 5.42E-03 1.90E-02 pCi/m3 Air Charcoal 662103011 4/2/2024 lodine-131 4.98E-04 2.93E-03 1.02E-02 pCi/m3 Air Charcoal 662643011 4/9/2024 lodine-131 1.52E-03 4.84E-03 1.66E-02 pCi/m3 Air Charcoal 663750011 4/16/2024 lodine-131

-4.49E-03 9.54E-03 2.96E-02 pCi/m3 Air Charcoal 664746011 4/23/2024 lodine-131 1.37E-02 8.77E-03 2.44E-02 pCi/m3

Annual Environmental Operatii-19 Report I YEAR: 2024 I Page 55 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-5 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 665753011 4/30/2024 lodine-131 6.98E-02 1.88E-02 3.12E-02 pCi/m3 Air Charcoal 667499011 5n12024 lodine-131 4.63E-03 1.11E-02 3.92E-02 pCi/m3 Air Charcoal 667922011 5/14/2024 lodine-131 1.12E-06 6.65E-03 2.12E-02 pCi/m3 Air Charcoal 668704011 5/21/2024 lodine-131 1.88E-02 1.08E-02 1.69E-02 pCi/m3 Air Charcoal 669507011 5/28/2024 lodine-131 2.62E-02 1.14E-02 4.52E-02 pCi/m3 Air Charcoal 670356011 6/4/2024 lodine-131

-5.46E-03 4.83E-03 1.45E-02 pCi/m3 Air Charcoal 671436011 6/11/2024 lodine-131

-1.31E-02 1.23E-02 3.58E-02 pCi/m3 Air Charcoal 672520011 6/18/2024 lodine-131

-1.33E-02 1.44E-02 3.58E-02 pCi/m3 Air Charcoal 673285011 6/25/2024 lodine-131 5.62E-03 1.64E-02 5.78E-02 pCi/m3 Air Charcoal 674236011 7/2/2024 lodine-131

-9.80E-03 1.45E-02 4.42E-02 pCi/ri13 Air Charcoal 675355011 7/9/2024 lodine-131

-3.87E-03 5.35E-03 1.66E-02 pCi/m3 Air Charcoal 676443011 7/16/2024 lodine-131 9.52E-03 1.91E-02 6.74E-02 pCi/m3 Air Charcoal 677643011 7/23/2024 lodine-131 5.77E-02 2.51E-02 4.63E-02 pCi/m3 Air Charcoal 678791011 7/30/2024 lodine-131 2.58E-02 1.73E-02 6.25E-02 pCi/m3 Air Charcoal 679919011 8/6/2024 lodine-131

-2.33E-02 1.36E-02 2.86E-02 pCi/m3 Air Charcoal 681151011 8/13/2024 lodine-131

-3.24E-04 7.66E-03 2.55E-02 pCi/m3 Air Charcoal 682299011 8/20/2024 lodine-131

-2.31E-03 4.47E-03 1.42E-02 pCi/m3 Air Charcoal 683273011 8/27/2024 lodine-131 1.22E-02 6.92E-03 2.84E-02 pCi/m3 Air Charcoal 684114011 9/3/2024 lodine-131 1.56E-03 6.59E-03 2.27E-02 pCi/m3 Air Charcoal 685520009 9/10/2024 lodine-131 1.45E-03 1.08E-02 3.71E-02 pCi/m3 Air Charcoal 686609011 9/17/2024 lodine-131

-4.77E-03 7.58E-03 2.24E-02 pCi/m3 Air Charcoal 687551011 9/24/2024 lodine-131

-6.23E-03 1.40E-02 4.42E-02 pCi/m3 Air Charcoal 688665011 10/1/2024 lodine-131

-1.91E-02 1.51E-02 4.12E-02 pCi/m3 Air Charcoal 690029011 10/8/2024 lodine-131

-5.17E-03 1.32E-02 4.15E-02 pCi/m3 Air Charcoal 690778011 10/15/2024 lodine-131 3.lOE-03 1.27E-02 4.43E-02 pCi/m3 Air Charcoal 691848011 10/22/2024 lodine-131

-5.34E-03 7.30E-03 2.20E-02 pCi/m3 Air Charcoal 693027011 10/29/2024 lodine-131

-3.27E-03 1.l0E-02 3.44E-02 pCi/m3 Air Charcoal 694334011 11/5/2024 lodine-131 3.69E-03 1.18E-02 4.15E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 56 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Air Sample Location A-5 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 695643011 11/12/2024 lodine-131

-1.01E-02 1.20E-02 3.29E-02 pCi/m3 Air Charcoal 696957011 11/19/2024 lodine-131

-1.59E-03 1.59E-02 5.27E-02 pCi/m3 Air Charcoal 698137011 11/26/2024 lodine-131

-6.74E-03 6.85E-03 1.96E-02 pCi/m3 Air Charcoal 699161011 12/3/2024 lodine-131

-1.99E-02 1.39E-02 3.59E-02 pCi/m3 Air Charcoal 700156011 12/10/2024 lodine-131 2.46E-02 1.64E-02 6.19E-02 pCi/m3 Air Charcoal 701439011 12/17/2024 lodine-131

-2.50E-04 5.95E-03 1.77E-02 pCi/m3 Air Charcoal 702177011 12/23/2024 lodine-131

-1.l0E-02 1.56E-02 4.79E-02 pCi/m3 Air Charcoal 703336011 12/31/2024 Iodine-131 1.84E-02 2.l0E-02 6.41E-02 pCi/m3 Air Charcoal 703311011 1n1202s lodine-131 5.19E-03 2.37E-02 6.69E-02 pCi/m3 Air Sample Location A-5 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 650472003 1/2/2024 BETA 4.82E-02 2.80E-03 3.02E-03 pCi/m3 Air Particulate 651480003 1/9/2024 BETA 5.84E-02 2.87E-03 2.55E-03 pCi/m3 Air Particulate 652168003 1/16/2024 BETA 4.97E-02 2.64E-03 2.48E-03 pCi/m3 Air Particulate 652769003 1/23/2024 BETA 4.85E-02 2.59E-03 2.47E-03 pCi/m3 Air Particulate 653673003 1/30/2024 BETA 4.55E-02 2.52E-03 2.48E-03 pCi/m3 Air Particulate 654638003 2/6/2024 BETA 4.08E-02 2.42E-03 2.47E-03 pCi/m3 Air Particulate 655415003 2/13/2024 BETA 3.91E-02 2.33E-03 2.35E-03 pCi/m3 Air Particulate 656171003 2/20/2024 BETA 4.88E-02 2.63E-03 2.41E-03 pCi/m3 Air Particulate 657034003 2/27/2024 BETA 5.36E-02 2.73E-03 2.51E-03 pCi/m3 Air Particulate 657989003 3/5/2024 BETA 4.06E-02 2.38E-03 2.44E-03 pCi/m3 Air Particulate 659140003 3/12/2024 BETA 4.52E-02 2.53E-03 2.31E-03 pCi/m3 Air Particulate 659692003 3/19/2024 BETA 4.74E-02 2.56E-03 2.40E-03 pCi/m3 Air Particulate 660512003 3/26/2024 BETA 3.66E-02 2.26E-03 2.33E-03 pCi/m3 Air Particulate 662103003 4/2/2024 BETA 3.83E-02 2.29E-03 2.19E-03 pCi/m3 Air Particulate 662643003 4/9/2024 BETA 3.56E-02 2.25E-03 2.45E-03 pCi/m3 Air Particulate 663750003 4/16/2024 BETA 2.96E-02 2.04E-03 2.28E-03 pCi/m3

Annual Environmental Operating Report

! YEAR: 2024 I Page 57 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-5 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 664746003 4/23/2024 BETA 3.91E-02 2.38E-03 2.43E-03 pCi/m3 Air Particulate 665753003 4/30/2024 BETA 3.80E-02 2.32E-03 2.30E-03 pCi/m3 Air Particulate 667499003 sn12024 BETA 3.39E-02 2.78E-03 3.56E-03 pCi/m3 Air Particulate 667922003 5/14/2024 BETA 3.83E-02 2.49E-03 2.67E-03 pCi/m3 Air Particulate 668704003 5/21/2024 BETA 4.59E-02 2.51E-03 2.25E-03 pCi/m3 Air Particulate 669507003 5/28/2024 BETA 4.34E-02 2.46E-03 2.32E-03 pCi/m3 Air Particulate 670356003 6/4/2024 BETA 2.79E-02 1.99E-03 2.35E-03 pCi/m3 Air Particulate 671436003 6/11/2024 BETA 4.0lE-02 2.38E-03 2.36E-03 pCi/m3 Air Particulate 672520003 6/18/2024 BETA 3.73E-02 2.27E-03 2.30E-03 pCi/m3 Air Particulate 673285003 6/25/2024 BETA 3.77E-02 4.50E-03 2.25E-03 pCi/m3 Air Particulate 674236003 7/2/2024 BETA 2.79E-02 2.03E-03 2.45E-03 pCi/m3 Air Particulate 675355003 7/9/2024 BETA 3.76E-02 2.33E-03 2.34E-03 pCi/m3 Air Particulate 676443003 7/16/2024 BETA 4.14E-02 2.40E-03 2.29E-03 pCi/m3 Air Particulate 677643003 7/23/2024 BETA 4.26E-02 2.47E-03 2.47E-03 pCi/m3 Air Particulate 678791003 7/30/2024 BETA 3.03E-02 2.09E-03 2.24E-03 pCi/m3 Air Particulate 679919003 8/2/2024 BETA 5.35E-02 2.74E-03 2.40E-03 pCi/ m3 Air Particulate 681151003 8/13/2024 BETA 7.0SE-02 3.14E-03 2.53E-03 pCi/m3 Air Particulate 682299003 8/20/2024 BETA 3.76E-02 2.29E-03 2.41E-03 pCi/m3 Air Particulate 683273003 8/27/2024 BETA 5.15E-02 2.64E-03 2.47E-03 pCi/ m3 Air Particulate 684114003 9/3/2024 BETA 2.71E-02 2.00E-03 2.44E-03 pCi/m3 Air Particulate 685520002 9/10/2024 BETA 5.05E-02 2.68E-03 2.47E-03 pCi/m3 Air Particulate 686609003 9/17/2024 BETA 3.79E-02 2.33E-03 2.38E-03 pCi/m3 Air Particulate 687551003 9/24/2024 BETA 2.95E-02 2.07E-03 2.42E-03 pCi/m3 Air Particulate 688665003 10/1/2024 BETA 4.79E-02 2.57E-03 2.40E-03 pCi/m3 Air Particulate 690029003 10/8/2024 BETA 5.72E-02 2.82E-03 2.46E-03 pCi/m3 Air Particulate 690778003 10/15/2024 BETA 7.03E-02 3.09E-03 2.41E-03 pCi/m3 Air Particulate 691848003 10/22/2024 BETA 4.14E-02 2.38E-03 2.26E-03 pCi/m3

Annual Environmental Operating Report f YEAR: 2024 I Page 58 of 138 Company: Vistra Com Comanche Peak Nuclear Power Plant Air Sample Location A-5 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 693027003 10/29/2024 BETA 5.33E-02 5.33E-03 2.32E-03 pCi/m3 Air Particulate 694334003 11/5/2024 BETA 3.48E-02 2.23E-03 2.35E-03 pCi/m3 Air Particulate 695643003 11/12/2024 BETA 4.38E-02 2.47E-03 2.38E-03 pCi/m3 Air Particulate 696957003 11/19/2024 BETA 4.96E-02 2.66E-03 2.40E-03 pCi/m3 Air Particulate 698137003 11/26/2024 BETA 4.35E-02 2.43E-03 2.31E-03 pCi/m3 Air Particulate 699161003 12/3/2024 BETA 7.16E-02 3.17E-03 2.67E-03 pCi/m3 Air Particulate 700156003 12/10/2024 BETA 5.97E-02 2.83E-03 2.44E-03 pCi/m3 Air Particulate 701439003 12/17/2024 BETA 3.28E-02 2.15E-03 2.44E-03 pCi/m3 Air Particulate 702177003 12/23/2024 BETA 6.50E-02 3.25E-03 3.l0E-03 pCi/m3 Air Particulate 703336003 12/31/2024 BETA 4.56E-02 2.37E-03 2.32E-03 pCi/m3 Air Particulate 703311003 1/7/2025 BETA 4.02E-02 2.41E-03 2.63E-03 pCi/m3 AirS le L1

.. lt,J.

.,,._,.. *lvO iteG s ;pectroscoov Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 665488003 3/26/2024 Cesium-134 1.50E-04 1.29E-04 4.79E-04 pCi/m3 Air Particulate 665488003 3/26/2024 Cesium-137 4.52E-05 1.34E-04 4.48E-04 pCi/m3 Air Particulate 678485003 5/10/2024 Cesium-134

-2.02E-04 1.76E-04 5.49E-04 pCi/m3 Air Particulate 678485003 5/10/2024 Cesium-137 7.18E-05 1.30E-04 4.38E-04 pCi/m3 Air Particulate 693204003 9/24/2024 Cesium-134 1.54E-05 1.47E-04 4.81E-04 pCi/m3 Air Particulate 693204003 9/24/2024 Cesium-137 5.93E-05 1.11E-04 3.87E-04 pCi/m3 Air Particulate 706294003 12/23/2024 Cesium-134 3.46E-05 2.04E-04 6.63E-04 pCi/m3*

Air Particulate 706294003 12/23/2024 Cesium-137

-1.13E-04 1.43E-04 4.08E-04 pCi/m3 Air Sample Location A-6 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 650472012 1/2/2024 lodine-131 1.27E-02 7.31E-03 2.76E-02 pCi/m3 Air Charcoal 651480012 1/9/2024 lodine-131

-1.93E-03 4.42E-03 1.38E-02 pCi/ m3 Air Charcoal 652168012 1/16/2024 lodine-131

-4.16E-04 3.93E-03 1.32E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 59 of 138 Com~any: Vistra Corp I Comanche Peak Nuclear Power Plant Air Sample Location A-6 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 652769012 1/23/2024 lodine-131 1.44E-03 3.06E-03 1.08E-02 pCi/m3 Air Charcoal 653673012 1/30/2024 lodine-131 1.69E-03 2.85E-03 9.52E-03 pCi/m3 Air Charcoal 654638012 2/6/2024 lodine-131

-2.89E-04 4.06E-03 1.33E-02 pCi/m3 Air Charco.al 655415012 2/13/2024 lodine-131 2.40E-03 3.91E-03 1.34E-02 pCi/m3 Air Charcoal 656171012 2/20/2024 lodine-131

-7.23E-04 5.45E-03 1.82E-02 pCi/m3 Air Charcoal 657034012 2/27/2024 lodine-131

-3.07E-03 4.43E-03 1.41E-02 pCi/m3 Air Charcoal 657989012 3/5/2024 lodine-131

-5.13E-03 5.19E-03 1.59E-02 pCi/m3 Air Charcoal 659140012 3/12/2024 lodine-131 1.00E-03 7.40E-03 2.39E-02 pCi/m3 Air Charcoal 659692012 3/19/2024 lodine-131 3.65E-03 4.91E-03 1.69E-02 pCi/m3 Air Charcoal 660512012 3/26/2024 lodine-131

-1.84E-04 6.44E-03 2.0SE-02 pCi/m3 Air Charcoal 662103012 4/2/2024 lodine-131 8.30E-04 4.78E-03 1.63E-02 pCi/m3 Air Charcoal 662643012 4/9/2024 lodine-131

-4.70E-03 5.07E-03 1.56E-02 pCi/m3 Air Charcoal 663750012 4/16/2024 lodine-131

-3.95E-03 1.30E-02 4.23E-02 pCi/m3 Air Charcoal 664746012 4/23/2024 lodine-131

-1.30E-02 7.58E-03 1.88E-02 pCi/m3 Air Charcoal 665753012 4/30/2024 lodine-131

-2.56E-03 9.89E-03 3.23E-02 pCi/m3 Air Charcoal 667499012 5/7/2024 Iodine-131 3.27E-03 8.04E-03 2.BOE-02 pCi/m3 Air Charcoal 667922012 5/14/2024 lodine-131 9.00E-03 7.05E-03 2.71E-02 pCi/m3 Air Charcoal 668704012 5/21/2024 lodine-131 5.58E-03 5.38E-03 2.0SE-02 pCi/m3 Air Charcoal 669507012 5/28/2024 lodine-131

-2.25E-03 1.04E-02 3.38E-02 pCi/m3 Air Charcoal 670356012 6/4/2024 lodine-131 6.lOE-03 7.00E-03 2.44E-02 pCi/m3 Air Charcoal 671436012 6/11/2024 lodine~131

-5.94E-03 6.92E-03 2.09E-02 pCi/m3 Air Charcoal 672520012 6/18/2024 lodine-131 3.26E-03 1.20E-02 4.11E-02 pCi/m3 Air Charcoal 673285012 6/25/2024 lodine-131 O.OOE+OO 1.42E-02 4.76E-02 pCi/m3 Air Charcoal 674236012 7/2/2024 Iodine-131

-6.97E-03 1.27E-02 3.82E-02 pCi/m3 Air Charcoal 675355012 7/9/2024 lodine-131 1.16E-02 1.39E-02 5.11E-02 pCi/m3 Air Charcoal 676443012 7/16/2024 lodine-131 4.04E-03 2.02E-02 6.83E-02 pCi/m3 Air Charcoal 677643012 7/23/2024 lodine-131

-1.94E-02 1.34E-02 2.61E-02 pCi/m3 Air Charcoal 678791012 7/30/2024 lodine-131

-1.89E-02 1.69E-02 4.79E-02 pCi/m3

Annual Environmental Operating Reeort I YEAR: 2024 I Page 60 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sa_111ple Location A-6 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 679919012 8/6/2024 lodine-131

-4.73E-02 2.26E-02 5.16E-02 pCi/m3 Air Charcoal 681151012 8/13/2024 lodine-131 6.17E-04 1.llE-02 3.74E-02 pCi/m3 Air Charcoal 682299012 8/20/2024 lodine-131

-2.36E-03 3.76E-03 1.13E-02 pCi/m3 Air Charcoal 683273012 8/27/2024 lodine-131 2.96E-03 7.24E-03 2.61E-02 pCi/m3 Air Charcoal 684114012 9/3/2024 lodine-131 9.43E-03 9.30E-03 3.20E-02 pCi/m3 Air Charcoal 685520010 9/10/2024 lodine-131 2.07E-02 1.08E-02 4.54E-02 pCi/m3 Air Charcoal 686609012 9/17/2024 lodine-131 1.76E-03 8.77E-03 3.12E-02 pCi/m3 Air Charcoal 687551012 9/24/2024 lodine-131 4.44E-04 1.07E-02 3.43E-02 pCi/m3 Air Charcoal 688665012 10/1/2024 lodine-131 5.64E-04 1.66E-02 5.62E-02 pCi/m3 Air Charcoal 690029012 10/8/2024 Jodine-131

-2.20E-03 1.46E-02 4.79E-02 pCi/m3 Air Charcoal 690778012 10/15/2024 lodine-131

-5.17E-03 9.47E-03 2.76E-02 pCi/m3 Air Charcoal 691848012 10/22/2024 lodine-131

-2.99E-03 9.74E-03 3.16E-02 pCi/m3 Air Charcoal 693027012 10/29/2024 lodine-131

-3.36E-03 9.11E-03 2.96E-02 pCi/m3 Air Charcoal 694334012 11/5/2024 lodine-131

-3.36E-03 8.25E-03 2.58E-02 pCi/m3 Air Charcoal 695643012 11/12/2024 lodine-131 2.29E-02 1.24E-02 5.14E-02 pCi/m3 Air Charcoal 696957012 11/19/2024 lodine-131 9.40E-03 9.99E-03 3.67E-02 pCi/m3 Air Charcoal 698137012 11/26/2024 lodine-131

-2.48E-03 9.07E-03 2.82E-02 pCi/m3 Air Charcoal 699161012 12/3/2024 lodine-131 3.19E-03 1.12E-02 3.83E-02 pCi/m3 Air Charcoal 700156012 12/10/2024 lodine-131 8.57E-03 1.93E-02 6.83E-02 pCi/m3 Air Charcoal 701439012 12/17/2024 lodine-131

-5.79E-03 6.21E-03 1.80E-02 pCi/m3 Air Charcoal 702177012 12/23/2024 lodine-131

-5.82E-03 1.08E-02 3.39E-02 pCi/m3 Air Charcoal 703336012 12/31/2024 lodine-131 1.75E-02 2.54E-02 6.91E-02 pCi/m3 Air Charcoal 703311012 1/7/2025 lodine-131

-5.98E-03 1.45E-02 3.S0E-02 pCi/m3 Air Sample Location A-6 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MOC Units Air Particulate 650472004 1/2/2024 BETA 5.42E-02 2.97E-03 2.93E-03 pCi/m3 Air Particulate 651480004 1/9/2024 BETA 4.84E-02 2.60E-03 2.63E-03 pCi/m3

Annual Environmental Operating Report i=i:EAR: 2024 I Page 61 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Air Sample Location A-6 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 652168004 1/16/2024 BETA 5.00E-02 2.61E-03 2.56E-03 pCi/m3 Air Particulate 652769004 1/23/2024 BETA 4.85E-02 2.62E-03 2.55E-03 pCi/m3 Air Particulate 653673004 1/30/2024 BETA 3.69E-02 2.33E-03 2.58E-03 pCi/m3 Air Particulate 654638004 2/6/2024 BETA 4.48E-02 2.48E-03 2.37E-03 pCi/m3 Air Particulate 655415004 2/13/2024 BETA 3.63E-02 2.30E-03 2.57E-03 pCi/m3 Air Particulate 656171004 2/20/2024 BETA 4.57E-02 2.51E-03 2.38E-03 pCi/m3 Air Particulate 657034004 2/27/2024 BETA 4.60E-02 2.54E-03 2.39E-03 pCi/m3 Air Particulate 657989004 3/5/2024 BETA 4.llE-02 2.39E-03 2.27E-03 pCi/m3 Air Particulate 659140004 3/12/2024 BETA 4.05E-02 2.37E-03 2.37E-03 pCi/m3 Air Particulate 659692004 3/19/2024 BETA 3.79E-02 2.36E-03 2.58E-03 pCi/m3 Air Particulate 660512004 3/26/2024 BETA 3.77E-02 2.30E-03 2.25E-03 pCi/m3 Air Particulate 662103004 4/2/2024 BETA 3.24E-02 2.17E-03 2.41E-03 pCi/m3 Air Particulate 662643004 4/9/2024 BETA 3.50E-02 2.23E-03 2.25E-03 pCi/m3 Air Particulate 663750004 4/16/2024 BETA 3.84E-02 2.30E-03 2.28E-03 pCi/m3 Air Particulate 664746004 4/23/2024 BETA 4.13E-02 2.42E-03 2.30E-03 pCi/m3 Air Particulate 665753004 4/30/2024 BETA 3.lOE-02 2.09E-03 2.41E-03 pCi/m3 Air Particulate 667499004 517/2024 BETA 2.55E-02 1.93E-03 2.27E-03 pCi/m3 Air Particulate 667922004 5/14/2024 BETA 3.59E-02 2.23E-03 2.23E-03 pCi/m3 Air Particulate 668704004 5/21/2024 BETA 4.03E-02 2.41E-03 2.46E-03 pCi/m3 Air Particulate 669507004 5/28/2024 BETA 4.0lE-02 2.41E-03 2.51E-03 pCi/m3 Air Particulate 670356004 6/4/2024 BETA 2.86E-02 2.04E-03 2.31E-03 pCi/m3 Air Particulate 671436004 6/11/2024 BETA 3.46E-02 2.26E-03 2.49E-03 pCi/m3 Air Particulate 672520004 6/18/2024 BETA 3.68E-02 2.30E-03 2.44E-03 pCi/ m3 Air Particulate 673285004 6/25/2024 BETA 2.58E-02 3.79E-03 2.35E-03 pCi/m3 Air Particulate 674236004 7/2/2024 BETA 2.45E-02 1.91E-03 2.38E-03 pCi/m3 Air Particulate 675355004 7/9/2024 BETA 3.0lE-02 2.lOE-03 2.46E-03 pCi/m3 Air Particulate 676443004 7/16/2024 BETA 3.72E-02 2.33E-03 2.49E-03 pCi/m3

Annual Environmental Operatin_g__Report J

YEAR: 2024 I Page 62 of 138 Company: Vistra Corp

! Comanche Peak Nuclear Power Plant Air Sam_Qle Location A-6 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 677643004 7/23/2024 BETA 3.80E-02 2.33E-03 2.35E-03 pCi/m3 Air Particulate 678791004 7/30/2024 BETA 2.52E-02 1.92E-03 2.37E-03 pCi/m3 Air Particulate 679919004 8/6/2024 BETA 4.33E-02 2.47E-03 2.34E-03 pCi/m3 Air Particulate 681151004 8/13/2024 BETA 5.63E-02 2.81E-03 2.38E-03 pCi/m3 Air Particulate 682299004 8/20/2024 BETA 3.30E-02 2.15E-03 2.17E-03 pCi/m3 Air Particulate 683273004 8/27/2024 BETA 4.27E-02 2.43E-03 2.42E-03 pCi/m3 Air Particulate 684114004 9/3/2024 BETA 2.31E-02 1.90E-03 2.53E-03 pCi/m3 Air Particulate 685520003 9/10/2024 BETA 4.00E-02 2.40E-03 2.38E-03 pCi/m3 Air Particulate 686609004 9/17/2024 BETA 2.69E-02 1.97E-03 2.31E-03 pCi/m3 Air Particulate 687551004 9/24/2024 BETA 2.59E-02 1.92E-03 2.33E-03 pCi/m3 Air Particulate 688665004 10/1/2024 BETA 4.19E-02 2.43E-03 2.37E-03 pCi/m3 Air Particulate 690029004 10/8/2024 BETA 5.30E-02 2.71E-03 2.31E-03 pCi/m3 Air Particulate 690778004 10/15/2024 BETA 6.20E-02 2.85E-03 2.37E-03 pCi/m3 Air Particulate 691848004 10/22/2024 BETA 3.27E-02 2.20E-03 2.42E-03 pCi/m3 Air Particulate 693027004 10/29/2024 BETA 4.64E-02 4.95E-03 2.39E-03 pCi/m3 Air Particulate 694334004 11/5/2024 BETA 3.28E-02 2.20E-03 2.47E-03 pCi/m3 Air Particulate 695643004 11/12/2024 BETA 5.44E-02 2.70E-03 2.46E-03 pCi/m3 Air Particulate 696957004 11/19/2024 BETA 4.42E-02 2.52E-03 2.35E-03 pCi/m3 Air Particulate 698137004 11/26/2024 BETA 4.02E-02 2.39E-03 2.43E-03 pCi/m3 Air Particulate 699161004 12/3/2024 BETA 5.90E-02 2.85E-03 2.55E-03 pCi/m3 Air Particulate 700156004 12/10/2024 BETA 5.19E-02 2.68E-03 2.56E-03 pCi/m3 Air Particulate 701439004 12/17/2024 BETA 3.14E-02 2.11E-03 2.49E-03 pCi/m3 Air Particulate 702177004 12/23/2024 BETA 5.65E-02 2.S0E-03 2.43E-03 pCi/m3 Air Particulate 703336004 12/31/2024 BETA 5.48E-02 2.53E-03 2.llE-03 pCi/m3 Air Particulate 703311004 1n12025 BETA 4.71E-02 2.53E-03 2.40E-03 pCi/m3

Annual Environmental Operating Report r-YEAR: 2024 I Page 63 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant

___,.., _____ --******-__,..., ___ rosco PY AirS Location A-6 Air Quarterly C, ite G Soect1 Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 665488004 3/26/2024 Cesium-134

-6.77E-05 1.48E-04 4.77E-04 pCi/m3 Air Particulate 665488004 3/26/2024 Cesium-137 1.86E-04 1.70E-04 5.88E-04 pCi/m3 Air Particulate 678485004 5/10/2024 Cesium-134

-4.29E-04 1.47E-04 3.S0E-04 pCi/m3 Air Particulate 678485004 5/10/2024 Cesium-137 1.71E-05 1.40E-04 4.04E-04 pCi/m3 Air Particulate 693204004 9/24/2024 Cesium-134.

1.03E-04 1.20E-04 4.27E-04 pCi/m3 Air Particulate 693204004 9/24/2024 Cesium-137 4.90E-05 1.26E-04 4.26E-04 pCi/m3 Air Particulate 706294004 12/23/2024 Cesium-134 6.67E-05 1.24E-04 4.40E-04 pCi/m3 Air Particulate 706294004 12/23/2024 Cesium-137 5.64E-05 1.72E-04 5.26E-04 pCi/m3 Air Sample Location A-7 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 650472010 1/2/2024 lodine-131 7.36E-03 1.01E-02 3.28E-02 pCi/m3 Air Charcoal 651480010 1/9/2024 lodine-131

-8.85E-03 4.75E-03 1.28E-02 pCi/m3 Air Charcoal 652168010 1/16/2024 lodine-131 4.73E-05 4.31E-03 1.44E-02 pCi/m3 Air Charcoal 652769010 1/23/2024 lodine-131

-3.53E-03 3.0SE-03 9.l0E-03 pCi/m3 Air Charcoal 653673010 1/30/2024 lodine-131

-2.60E-03 3.34E-03 1.07E-02 pCi/m3 Air Charcoal 654638010 2/6/2024 lodine-131 4.15E-03 3.S0E-03 1.34E-02 pCi/m3 Air Charcoal 655415010 2/13/2024 lodine-131 1.94E-03 3.54E-03 1.27E-02 pCi/m3.

Air Charcoal 656171010 2/20/2024 lodine-131 2.22E-03 5.93E-03 2.lOE-02 pCi/m3 Air Charcoal 657034010 2/27/2024 lodine-131

-1.57E-03 5.38E-03 1.67E-02 pCi/m3 Air Charcoal 657989010 3/5/2024 lodine-131

-8.35E-04 5.89E-03 1.94E-02 pCi/m3 Air Charcoal 659140010 3/12/2024 lodine-131 8.19E-03 6.62E-03 2.53E-02 pCi/m3 Air Charcoal 659692010 3/19/2024 lodine-131 3.41E-03 5.69E-03 2.02E-02 pCi/m3 Air Charcoal 660512010 3/26/2024 lodine-131

-4.96E-03 5.36E-03 1.66E-02 pCi/m3 Air Charcoal 662103010 4/2/2024 lodine-131 5.61E-03 4.72E-03 1.72E-02 pCi/m3 Air Charcoal 662643010 4/9/2024 lodine-131

-7.49E-03 5.84E-03 1.81E-02 pCi/m3 Air Charcoal 664746010 4/23/2024 lodine-131 1.01E-02 9.69E-03 3.40E-02 pCi/m3 Air Charcoal 665753010 4/30/2024 lodine-131

-7.41E-03 1.26E-02 4.0BE-02 pCi/m3 Air Charcoal 667499010 5/7/2024 lodine-131

-2.26E-04 1.18E-02 3.62E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 64 of 138 Company: Vistra Corp J Comanche Peak Nuclear Power Plant Air Sample Location A-7 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 667922010 5/14/2024 lodine-131

-6.33E-03 7.22E-03 2.14E-02 pCi/m3 Air Charcoal 668704010 5/21/2024 lodine-131

-4.04E-03 5.0BE-03 1.50E-02 pCi/m3 Air Charcoal 669507010 5/28/2024 lodine-131 5.42E-03 1.16E-02 4.07E-02 pCi/m3 Air Charcoal 670356010 6/4/2024 lodine-131

-7.39E-03 5.14E-03 1.SOE-02 pCi/m3 Air Charcoal 671436010 6/11/2024 lodine-131

-5.63E-03 1.lSE-02 3.51E-02 pCi/m3 Air Charcoal 672520010 6/18/2024 lodine-131 3.19E-04 1.21E-02 4.02E-02 pCi/m3 Air Charcoal 673285010 6/25/2024 lodine-131

-1.60E-02 1.40E-02 3.87E-02 pCi/m3 Air Charcoal 674236010 7/2/2024 lodine-131

-1.77E-02 9.11E-03 1.81E-02 pCi/m3 Air Charcoal 675355010 7/9/2024 lodine-131 2.61E-03 9.49E-03 3.33E-02 pCi/m3 Air Charcoal 676443010 7/16/2024 lodine-131

-8.51E-03 1.13E-02 3.64E-02 pCi/m3 Air Charcoal 677643010 7/23/2024 lodine-131

-2.22E-02 2.07E-02 6.44E-02 pCi/m3 Air Charcoal 678791010 7/30/2024 lodine-131

-7.49E-03 1.67E-02 5.36E-02 pCi/m3 Air Charcoal 679919010 8/6/2024 Jodine-131 8.13E-02 2.03E-02 2.90E-02 pCi/m3 Air Charcoal 681151010 8/13/2024 lodine-131 3.44E-03 9.91E-03 3.SOE-02 pCi/m3 Air Charcoal 682299010 8/20/2024 lodine-131

-8.47E-03 5.41E-03 1.26E-02 pCi/m3 Air Charcoal 683273010 8/27/2024 lodine-131 4.19E-03 6.29E-03 2.34E-02 pCi/m3 Air Charcoal 684114010 9/3/2024 lodine-131

-1.24E-02 6.65E-03 1.45E-02 pCi/m3 Air Charcoal 685520008 9/10/2024 lodine-131 1.41E-02 9.16E-03 3.70E-02 pCi/m3 Air Charcoal 686609010 9/17/2024 lodine-131 1.24E-02 6.51E-03 2.68E-02 pCi/m3 Air Charcoal 687551010 9/24/2024 lodine-131 5.73E-03 1.39E-02 4.85E-02 pCi/m3 Air Charcoal 688665010 10/1/2024 lodine-131 7.98E-03 1.41E-02 5.23E-02 pCi/m3 Air Charcoal 690029010 10/8/2024 lodine-131 1.12E-02 1.90E-02 6.68E-02 pCi/m3 Air Charcoal 690778010 10/15/2024 lodine-131

-1.45E-02 1.06E-02 2.96E-02 pCi/m3 Air Charcoal 691848010 10/22/2024 lodine-131

-6.SOE-03 1.lSE-02 3.65E-02 pCi/m3 Air Charcoal 693027010 10/29/2024 lodine-131

-3.90E-03 5.62E-03 1.67E-02 pCi/m3 Air Charcoal 694334010 11/5/2024 lodine-131 6.51E-03 1.07E-02 3.87E-02 pCi/m3 Air Charcoal 695643010 11/12/2024 lodine-131

-2.94E-02 1.55E-02 3.96E-02 pCi/m3 Air Charcoal 696957010 11/19/2024 lodine-131

-3.15E-02 2.24E-02 5.64E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 65 of 138 Company: Vistra Corp

~=r Comanche Peak Nuclear Power i:>lant Air Sam_Q]e Location A-7 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 698137010 11/26/2024 lodine-131

-7.30E-03 6.65E-03 1.86E-02 pCi/m3 Air Charcoal 699161010 12/3/2024 lodine-131

-4.96E-03 1.52E-02 4.99E-02 pCi/m3 Air Charcoal 700156010 12/10/2024 lodine-131

-2.83E-02 1.89E-02 4.40E-02 pCi/m3 Air Charcoal 701439010 12/17/2024 lodine-131 3.83E-03 8.47E-03 3.0lE-02 pCi/m3 Air Charcoal 702177010 12/23/2024 lodine-131 2.02E-02 1.50E-02 5.99E-02 pCi/m3 Air Charcoal 703336010 12/31/2024 lodine-131

-1.99E-02 2.51E-02 6.05E-02 pCi/m3 Air Charcoal 703311010 1n1202s lodine-131 1.42E-02 1.87E-02 5.17E-02 pCi/m3 Air Sample Location A-7 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 650472002 1/2/2024 BETA 4.50E-02 2.75E-03 2.93E-03 pCi/m3 Air Particulate 651480002 1/9/2024 BETA 4.60E-02 2.58E-03 2.54E-03 pCi/m3 Air Particulate 652168002 1/16/2024 BETA 4.72E-02 2.59E-03 2.56E-03 pCi/m3 Air Particulate 652769002 1/23/2024 BETA 5.13E-02 2.63E-03 2.37E-03 pCi/m3 Air Particulate 653673002 1/30/2024 BETA 3.92E-02 2.33E-03 2.37E-03 pCi/m3 Air Particulate 654638002 2/6/2024 BETA 4.53E-02 2.55E-03 2.58E-03 pCi/m3 Air Particulate 655415002 2/13/2024 BETA 2.98E-02 2.08E-03 2.58E-03 pCi/m3 Air Particulate 656171002 2/20/2024 BETA 5.05E-02 2.70E-03 2.65E-03 pCilm3 Air Particulate 657034002 2/27/2024 BETA 3.72E-02 2.27E-03 2.25E-03 pCi/m3 Air Particulate 657989002 3/5/2024 BETA 4.37E-02 2.49E-03 2.35E-03 pCi/m3 Air Particulate 659140002 3/12/2024 BETA 3.86E-02 2.38E-03 2.59E-03 pCi/m3 Air Particulate 659692002 3/19/2024 BETA 3.16E-02 2.13E-03 2.41E-03 pCi/m3 Air Particulate 660512002 3/26/2024 BETA 3.36E-02 2.21E-03 2.33E-03 pCi/m3 Air Particulate 662103002 4/2/2024 BETA 3.51E-02 2.21E-03 2.39E-03 pCi/m3 Air Particulate 662643002 4/9/2024 BETA 3.25E-02 2.19E-03 2.41E-03 pCi/m3 Air Particulate 664746002 4/23/2024 BETA 3.37E-02 2.18E-03 2.22E-03 pCi/m3 Air Particulate 665753002 4/30/2024 BETA 2.76E-02 2.03E-03 2.45E-03 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 j Page 66 of 138 Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant Air Sample Location A-7 Air Particulate

~-

Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 667499002 5/7/2024 BETA 2.41E-02 1.91E-03 2.34E-03 pCi/m3 Air Particulate 667922002 5/14/2024 BETA 3.25E-02 2.17E-03 2.33E-03 pCi/m3 Air Particulate 668704002 5/21/2024 BETA 2.95E-02 2.05E-03 2.29E-03 pCi/m3 Air Particulate 669507002 5/28/2024 BETA 3.18E-02 2.14E-03 2.41E-03 pCi/m3 Air Particulate 670356002 6/4/2024 BETA 2.S0E-02

1.92E-03 2.29E-03 pCi/m3 Air Particulate 671436002 6/11/2024 BETA 2.96E-02 2.09E-03 2.53E-03 pCi/m3 Air Particulate 672520002 6/18/2024 BETA 3.33E-02 2.17E-03 2.48E-03 pCi/m3 Air Particulate 673285002 6/25/2024 BETA 2.16E-02 3.57E-03 2.40E-03 pCi/m3 Air Particulate 674236002 7/2/2024 BETA 2.23E-02 1.82E-03 2.32E-03 pCi/m3 Air Particulate 675355002 7/9/2024 BETA 2.56E-02 1.99E-03 2.51E-03 pCi/m3 Air Particulate 676443002 7/16/2024 BETA 3.12E-02 2.11E-03 2.33E-03 pCi/m3 Air Particulate 677643002 7/23/2024 BETA 3.13E-02 2.llE-03 2.28E-03 pCi/m3 Air Particulate 678791002 7/30/2024 BETA 2.05E-02 1.79E-03 2.46E-03 pCi/m3 Air Particulate 679919002 8/6/2024 BETA 3.70E-02 2.29E-03 2.48E-03 pCi/m3 Air Particulate 681151002 8/13/2024 BETA 4.48E-02 2.49E-03 2.21E-03 pCi/m3 Air Particulate 682299002 8/20/2024 BETA 2.70E-02 1.99E-03 2.34E-03 pCi/m3 Air Particulate 683273002 8/27/2024 BETA 4.08E-02 2.39E-03 2.36E-03 pCi/m3 Air Particulate 684114002 9/3/2024 BETA 1.46E-02 1.55E-03 2.49E-03 pCi/m3 Air Particulate

685520001 9/10/2024 BETA 3.48E-02 2.23E-03 2.39E-03 pCi/m3 Air Particulate 686609002 9/17/2024 BETA 2.39E-02 1.92E-03 2.51E-03 pCi/m3 Air Particulate 687551002 9/24/2024 BETA 2.30E-02 1.86E-03 2.37E-03 pCi/m3 Air Particulate 688665002 10/1/2024 BETA 3.00E-02 2.llE-03 2.34E-03 pCi/m3 Air Particulate 690029002 10/8/2024 BETA 3.71E-02 2.29E-03 2.40E-03 pCi/m3 Air Particulate 690778002 10/15/2024 BETA 4.14E-02 2.42E-03 2.35E-03 pCi/m3 Air Particulate 691848002 10/22/2024 BETA 2.46E-02 1.89E-03 2.36E-03 pCi/m3 Air Particulate 693027002 10/29/2024 BETA 2.98E-02 4.11E-03 2.40E-03 pCi/m3 Air Particulate 694334002 11/5/2024 BETA 2.39E-02 1.90E-03 2.54E-03 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 67 of 138 Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant Air Sample Location A-7 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 695643002 11/12/2024 BETA 2.57E-02 1.98E-03 2.55E-03 pCi/m3 Air Particulate 696957002 11/19/2024 BETA 2.56E-02 1.95E-03 2.37E-03 pCi/m3

. AirParticulate 698137002 11/26/2024 BETA 2.31E-02 1.84E-03 2.41E-03 pCi/m3 Air Particulate 699161002 12/3/2024 BETA 2.92E-02 2.12E-03 2.66E-03 pCi/m3 Air Particulate 700156002 12/10/2024 BETA 3.03E-02 2.12E-03 2.52E-03 pCi/m3 Air Particulate 701439002 12/17/2024 BETA 1.96E-02 1.76E-03 2.51E-03 pCi/m3 Air Particulate 702177002 12/23/2024 BETA 5.60E-02 3.02E-03 2.90E-03 pCi/m3 Air Particulate 703336002 12/31/2024 BETA 4.80E-02 2.43E-03 2.24E-03 pCi/m3 Air Particulate 703311002 1/7/2025 BETA 4.19E-02 2.45E-03 2.55E-03 pCi/m3 AirS le Location A-7 Air Q

'lvG

.,. G s

~oectroscoov Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 665488002 3/26/2024 Cesium-134 2.10E-04 1.66E-04 6.29E-04 pCi/m3 Air Particulate 665488002 3/26/2024 Cesium-137 6.36E-05 1.07E-04 3.73E-04 pCi/m3 Air Particulate 678485002 5/10/2024 Cesium-134 1.25E-04 1.86E-04 6.59E-04 pCi/m3 Air Particulate 678485002 5/10/2024 cesium-137

-7.98E-05 1.51E-04 4.60E-04 pCi/m3 Air Particulate 693204002 9/24/2024 Cesium-134 2.18E-05 3.11E-04 1.05E-03 pCi/m3 Air Particulate 693204002 9/24/2024 Cesium-137

-2.35E-04 2.58E-04 8.04E-04 pCi/m3 Air Particulate 706294002 12/23/2024 Cesium-134 2.05E-04 1.36E-04 5.05E-04 pCi/m3 Air Particulate 706294002 12/23/2024 Cesium-137 1.17E-04 5.22E-05 2.43E-04 pCi/m3 Air Sample Location A-8 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 650472009 1/2/2024 lodine-131

-1.0lE-02 7.88E-03 2.36E-02 pCi/m3 Air Charcoal 651480009 1/9/2024 lodine-131 1.59E-02 5.42E-03 2.22E-02 pCi/m3 Air Charcoal 652168009 1/16/2024 lodine-131

-7.82E-04 3.28E-03 1.0SE-02 pCi/m3 Air Charcoal 652769009 1/23/2024 lodine-131

-2.06E-03 1.92E-03 5.69E-03 pCi/m3 Air Charcoal 653673009 1/30/2024 lodine-131 2.13E-04 2.49E-03 8.44E-03 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 68 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-8 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 654638009 2/6/2024 lodine-131 7.16E-04 3.61E-03 1.22E-02 pCi/m3 Air Charcoal 655415009 2/13/2024 lodine-131

-6.69E-03 4.11E-03 1.13E-02 pCi/m3 Air Charcoal 656171009 2/20/2024 lodine-131 3.0BE-03 5.52E-03 1.99E-02 pCi/m3 Air Charcoal 657034009 2/27/2024 lodine-131 2.08E-02 1.23E-02 2.10E-02 pCi/m3 Air Charcoal 657989009 3/5/2024 lodine-131

-5.46E-03 5.33E-03 1.59E-02 pCi/m3 Air Charcoal 659140009 3/12/2024 lodine-131 6.35E-03 6.67E-03 2.32E-02 pCi/m3 Air Charcoal 659692009 3/19/2024 lodine-131

-4.40E-03 6.65E-03 2.10E-02 pCi/m3 Air Charcoal 660512009 3/26/2024 lodine-131

-4.98E-04 6.31E-03 2.09E-02 pCi/m3 Air Charcoal 662103009 4/2/2024 lodine-131

-7.35E-03 4.64E-03 1.36E-02 pCi/m3 Air Charcoal 662643009 4/9/2024 lodine-131 9.72E-04 5.77E-03 1.99E-02 pCi/m3 Air Charcoal 663750009 4/16/2024 lodine-131

-3.58E-04 1.0lE-02 3.44E-02 pCi/m3 Air Charcoal 664746009 4/23/2024 lodine-131

-1.l0E-02 9.75E-03 2.45E-02 pCi/m3 Air Charcoal 665753009 4/30/2024 lodine-131 5.33E-03 1.37E-02 4.72E-02 pCi/m3 Air Charcoal 667499009 5/7/2024 lodine-131 4.41E-03 9.36E-03 3.25E-02 pCi/m3 Air Charcoal 667922009,

5/14/2024 lodine-131

-5.37E-03 8.05E-03 2.52E-02 pCi/m3 Air Charcoal 668704009 5/21/2024 lodine-131 1.85E-03 6.90E-03 2.36E-02 pCi/m3 Air Charcoal 669507009 5/28/2024 lodine-131

-3.39E-03 1.19E-02 3.86E-02 pCi/m3 Air Charcoal 670356009 6/4/2024 lodine-131

-1.00E-02 4.64E-03 1.0SE-02 pCi/m3 Air Charcoal 671436009 6/11/2024 lodine-131

-5.94E-03 1.39E-02 4.27E-02 pCi/m3 Air Charcoal 672520009 6/18/2024 lodine-131 9.28E-03 7.25E-03 2.71E-02 pCi/m3 Air Charcoal 673285009 6/25/2024 lodine-131 7.25E-03 1.83E-02 6.54E-02 pCi/m3 Air Charcoal 674236009 7/2/2024 lodine-131

-1.26E-02 1.21E-02 2.S0E-02 pCi/m3 Air Charcoal 675355009 7/9/2024 lodine-131 8.53E-03 9.0SE-03 3.65E-02 pCilm3 Air Charcoal 676443009 7/16/2024 lodine-131

-1.32E-02 2.77E-02 5.28E-02 pCi/m3 Air Charcoal 677643009 7/23/2024 lodine-131 5.94E-03 2.03E-02 6.90E-02 pCi/m3 Air Charcoal 678791009 7/30/2024 lodine-131 1.37E-02 2.03E-02 6.92E-02 pCilm3 Air Charcoal 679919009 8/6/2024 lodine-131 2.29E-03 1.57E-02 5.42E-02 pCi/m3 Air Charcoal 681151009 8/13/2024 lodine-131 5.59E-03 9.59E-03 3.26E-02 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 69 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant Air Sample Location A-8 Air Charcoal Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Charcoal 682299009 8/20/2024 Iodine-131

-9.20E-03 5.33E-03 1.30E-02 pCi/m3 Air Charcoal 683273009 8/27/2024 Iodine-131 1.25E002 1.08E-02 3.93E-02 pCi/m3 Air Charcoal 684114009 9/3/2024 lodine-131 1.03E-02 8.90E-03 3.39E-02 pCi/m3 Air Charcoal 686609009 9/17/2024 lodine-131

-3.34E-03 6.22E-03 1.90E-02 pCi/m3 Air Charcoal 687551009 9/24/2024 lodine-131

-1.58E-02 1.33E-02 3.86E-02 pCi/m3 Air Charcoal 688665009 10/1/2024 lodine-131 2.42E-02 1.61E-02 6.31E-02 pCi/m3 Air Charcoal 690029009 10/8/2024 lodine-131

-1.89E-04 1.35E-02 4.50E-02 pCi/m3 Air Charcoal 690778009 10/15/2024 lodine-131

-1.24E-02 7.75E-03 1.78E-02 pCi/m3 Air Charcoal 691848009 10/22/2024 lodine-131 7.00E-03 6.19E-03 2.44E-02 pCi/m3 Air Charcoal 693027009 10/29/2024 lodine-131

-3.37E-03 8.63E-03 2.75E-02 pCi/m3 Air Charcoal 694334009 11/5/2024 Iodine-131 4.68E-03 1.31E-02 4.56E-02 pCi/m3 Air Charcoal 695643009 11/12/2024 Iodine-131

-6.85E-03 1.70E-02 4.84E-02 pCi/m3 Air Charcoal 696957009 11/19/2024 lodine-131

-2.78E-02 1.57E-02 4.12E-02 pCi/m3 Air Charcoal 698137009 11/26/2024 lodine-131

-3.44E-04 8.19E-03 2.77E-02 pCi/m3 Air Charcoal 699161009 12/3/2024 lodine-131 1.24E-02 1.27E-02 4.81E-02 pCi/m3 Air Charcoal 700156009 12/10/2024 lodine-131

-2.66E-02 1.88E-02 5.36E-02 pCi/m3 Air Charcoal 701439009 12/17/2024 lodine-131 7.77E-03 7.77E-03 2.96E-02 pCi/m3 Air Charcoal 702177009 12/23/2024 lodine-131

-7.S0E-03 1.68E-02 5.29E-02 pCi/m3 Air Charcoal 703336009 12/31/2024 lodine-131 3.05E-02 2.42E-02 6.86E-02 pCi/m3 Air Charcoal 703311009 1/7/2025 lodine-131 1.66E-03 1.46E-02 4.08E-02 pCi/m3 Air Sample Location A-8 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 650472001 1/2/2024 BETA 8.30E-02 3.64E-03 2.91E-03 pCi/m3 Air Particulate 651480001 1/9/2024 BETA 9.49E-02 3.57E-03 2.55E-03 pCi/m3 Air Particulate 652168001 1/16/2024 BETA 8.66E-02 3.40E-03 2.51E-03 pCi/m3 Air Particulate 652769001 1/23/2024 BETA 5.76E-02 2.83E-03 2.47E-03 pCi/m3 Air Particulate 653673001 1/30/2024 BETA 4.23E-02 2.46E-03 2.47E-03 pCi/m3

Annual Environmental Operating Report J

YEAR: 2024 J

Page 70 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant Air Sample Location A-8 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 654638001 2/6/2024 BETA 3.41E-02 2.21E-03 2.48E-03 pCi/m3 Air Particulate 655415001 2/13/2024 BETA 3.79E*02 2.32E-03 2.39E*03 pCi/m3 Air Particulate 656171001 2/20/2024 BETA 4.13E-02 2.41E-03 2.36E-03 pCi/m3 Air Particulate 657034001 2/27/2024 BETA 3.72E-02 2.27E-03 2.36E-03 pCi/m3 Air Particulate 657989001 3/5/2024 BETA 3.84E-02 2.36E-03 2.53E-03 pCi/m3 Air Particulate 659140001 3/12/2024 BETA 3.61E-02 2.25E-03 2.32E-03 pCi/m3 Air Particulate 659692001 3/19/2024 BETA 3.03E-02 2.l0E-03 2.30E-03 pCi/m3 Air Particulate 660512001 3/26/2024 BETA 2.54E-02 1.98E-03 2.57E-03 pCi/m3 Air Particulate 662103001 4/2/2024 BETA 2.49E-02 1.92E-03 2.35E-03 pCi/m3 Air Particulate 662643001 4/9/2024 BETA 2.50E-02 1.96E-03 2.48E-03 pCi/m3 Air Particulate 663750001 4/16/2024 BETA 3.17E-02 2.16E-03 2.48E-03 pCi/m3 Air Particulate 664746001 4/23/2024 BETA 2.00E-02 1.74E-03 2.33E-03 pCi/m3 Air Particulate 665753001 4/30/2024 BETA 1.83E-02 1.66E-03 2.24E-03 pCi/m3 Air Particulate 667499001 5/7/2024 BETA 1.16E-02 l.43E-03 2.40E-03 pCi/m3 Air Particulate 667922001 5/14/2024 BETA 6.03E-02 2.89E-03 2.39E-03 pCi/m3 Air Particulate 668704001 5/21/2024 BETA 1.41E-02 1.52E-03 2.34E-03 pCi/m3 Air Particulate 669507001 5/28/2024 BETA 4.82E-02 2.65E-03 2.41E-03 pCi/m3 Air Particulate 670356001 6/4/2024 BETA 3.29E-02 2.20E-03 2.50E-03 pCi/m3 Air Particulate 671436001 6/11/2024 BETA 3.83E-02 2.36E-03 2.42E-03 pCi/m3 Air Particulate 672520001 6/18/2024 BETA 4.94E-02 2.61E-03 2.36E-03 pCi/m3 Air Particulate 673285001 6/25/2024 BETA 3.06E-02 4.08E-03 2.29E-03 pCi/m3 Air Particulate 674236001 7/2/2024 BETA 2.72E-02 1.98E-03 2.43E-03 pCi/m3 Air Particulate 675355001 7/9/2024 BETA 4.16E-02 2.42E-03 2.36E-03 pCi/m3 Air Particulate 676443001 7/16/2024 BETA 5.36E-02 2.74E-03 2.37E-03 pCi/m3 Air Particulate 677643001 7/23/2024 BETA 4.97E-02 2.59E-03 2.31E-03 pCi/m3 Air Particulate 678791001 7/30/2024 BETA 3.94E-02 2.34E-03 2.34E-03 pCi/m3 Air Particulate 679919001 8/6/2024 BETA 6.15E-02 2.94E-03 3.09E-03 pCi/m3

Annual Environmental Operating Report j YEAR: 2024 I Page 71 of 138 Compan~~ Vistra Corp

! Comanche Peak Nuclear Power Plant Air Sam_Q_le Location A-8 Air Particulate Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 681151001 8/13/2024 BETA 8.09E-02 3.29E-03 2.45E-03 pCi/m3 Air Particulate 682299001 8/20/2024 BETA 4.63E-02 2.56E-03 2.49E-03 pCi/m3 Air Particulate 683273001 8/27/2024 BETA 7.16E-02 3.13E-03 2.SOE-03 pCi/m3 Air Particulate 684114001 9/3/2024 BETA 3.28E~02 2.28E-03 2.58E-03 pCi/m3 Air Particulate 686609001 9/17/2024 BETA 4.33E-02 2.53E-03 2.SSE-03 pCi/m3 Air Particulate 687551001 9/24/2024 BETA 3.96E-02 2.32E-03 2.27E-03 pCi/m3 Air Particulate 688665001 10/1/2024 BETA 6.40E-02 2.99E-03 2.47E-03 pCi/m3 Air Particulate 690029001 10/8/2024 BETA 7.77E-02 3.20E-03 2.45E-03 pCi/m3 Air Particulate 690778001 10/15/2024 BETA 8.28E-02 3.31E-03 2.42E-03 pCi/m3 Air Particulate 691848001 10/22/2024 BETA 4.84E-02 2.59E-03 2.31E-03 pCi/m3 Air Particulate 693027001 10/29/2024 BETA 6.75E-02 5.89E-03 2.27E-03 pCi/m3 Air Particulate 694334001 11/5/2024 BETA 4.67E-02 2.58E-03 2.45E-03 pCi/m3 Air Particulate 695643001 11/12/2024 BETA 3.64E-02 2.25E-03 2.35E-03 pCi/m3 Air Particulate 696957001 11/19/2024 BETA 5.44E-02 2.75E-03 2.53E-03 pCi/m3 Air Particulate 698137001 11/26/2024 BETA 6.12E-02 2.87E-03 2.27E-03 pCi/m3 Air Particulate 699161001 12/3/2024 BETA 9.83E-02 3.65E-03 2.67E-03 pCi/m3 Air Particulate 700156001 12/10/2024 BETA 7.70E-02 3.25E-03 2.45E-03 pCi/m3 Air Particulate 701439001 12/17/2024 BETA 4.24E-02 2.45E-03 2.44E-03 pCi/m3 Air Particulate 702177001 12/23/2024 BETA 7.63E-02 3.53E-03 3.11E-03 pCi/m3 Air Particulate 703336001 12/31/2024 BETA 7.98E-02 3.06E-03 2.38E-03 pCi/m3 Air Particulate 703311001 1/7/2025 BETA 5.lOE-02 2.66E-03 2.69E-03 pCi/m3

Annual Environmental Operating Report I YEAR: 2024 I Page 72 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant AirS

~ - - Location A-8 Air Quarterly C

-- 9~-.

iteG

--

Jt,J

...... Soect1

,µ ___ rosco DV Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Air Particulate 665488001 3/26/2024 Cesium-134 2.18E-04 1.65E-04 5.86E-04 pCi/m3 Air Particulate 665488001 3/26/2024 Cesium-137 7.06E-05 1.54E-04 5.14E-04 pCi/m3 Air Particulate 678485001 5/10/2024 Cesium-134 1.lOE-04 1.41E-04 4.93E-04 pCi/m3 Air Particulate 678485001 5/10/2024 Cesium-137 9.64E-05 1.39E-04 4.81E-04 pCi/m3 Air Particulate 693204001 9/24/2024 Cesium-134 1.91E-05 1.80E-04 6.09E-04 pCi/m3 Air Particulate 693204001 9/24/2024 Cesium-137 9.llE-06 1.95E-04 6.22E-04 pCi/m3 Air Particulate 706294001 12/23/2024 Cesium-134 1.30E-04 1.81E-04 6.SOE-04 pCi/m3 Air Particulate 706294001 12/23/2024 Cesium-137

-2.62E-04 1.92E-04 5.70E-04 pCi/m3 SW-1 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 653744002 1/30/2024 Barium-140 1.22E+OO 3.00E+OO 1.01E+01 pCi/L Surface Water 653744002 1/30/2024 Cesium-134 6.35E-02 6.29E-01 2.05E+OO pCi/L Surface Water 653744002 1/30/2024 Cesium-137 4.04E-01 5.91E-01 1.99E+OO pCi/L Surface Water 653744002 1/30/2024 Cobalt-58

-6.46E-01 5.83E-01 1.79E+OO pCi/L Surface Water 653744002 1/30/2024 Cobalt-60

-8.36E-02 5.30E-01 1.75E+OO pCi/L Surface Water 653744002 1/30/2024 lodine-131

-1.67E+OO 1.0SE+OO 3.41E+OO pCi/L Surface Water 653744002 1/30/2024 lron-59 8.18E-01 9.38E-01 3.34E+OO pCi/L Surface Water 653744002 1/30/2024 Lanthanum-140

-2.38E+OO 8.38E-01 2.lOE+OO pCi/L Surface Water 653744002 1/30/2024 Manganese-54 3.39E+OO 1.60E+OO 1.69E+OO pCi/L Surface Water 653744002 1/30/2024 Niobium-95

-1.44E-01 5.90E-01 1.90E+OO pCi/L Surface Water 653744002 1/30/2024 Zinc-65 l.77E+OO 9.60E-01 3.58E+OO pCi/L Surface Water 653744002 1/30/2024 Zirconium-95 8.48E-01 1.00E+OO 3.39E+OO pCi/L Surface Water 657026002 2/27/2024 Barium-140 1.56E+OO 2.39E+OO 7.83E+OO pCi/L Surface Water 657026002 2/27/2024 Cesium-134

-1.87E-01 4.85E-01 1.59E+OO pCi/L Surface Water 657026002 2/27/2024 Cesium-137 7.14E-01 5.28E-01 1.88E+OO pCi/L Surface Water 657026002 2/27/2024 Cobalt-58

-3.60E-01 4.49E-01 1.44E+OO pCi/L Surface Water 657026002 2/27/2024 Cobalt-60 9.90E-01 6.41E-01 2.04E+OO pCi/L Surface Water 657026002 2/27/2024 lodine-131 8.19E-01 9.41E-01 3.14E+OO

pCi/L

Annual Environmental Operating Report J

YEAR: 2024 J

Page 73 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-1 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 657026002 2/27/2024 lron-59

-3.17E+OO 1.40E+OO 3.21E+OO pCi/L Surface Water 657026002 2/27/2024 Lanthanum-140 6.66E-02 8.76E-01 2.82E+OO pCi/L Surface Water 657026002 2/27/2024 Manganese-54 4.97E-01 6.98E-01 1.47E+OO pCi/L Surface Water 657026002 2/27/2024 Niobium-95 5.85E-01 5.17E-01 l.81E+OO pCi/L Surface Water 657026002 2/27/2024 Zinc-65 4.08E-01 9.57E-01 3.22E+OO pCi/L Surface Water 657026002 2/27/2024 Zirconium-95

-4.96E-01 8.75E-01 2.87E+OO pCi/L Surface Water 660511002 3/26/2024 Barium-140

-4.06E+OO 4.14E+OO 1.25E+Ol pCi/L Surface Water 660511002 3/26/2024 Cesium-134

-1.21E+OO 1.05E+OO 3.24E+OO pCi/L Surface Water 660511002 3/26/2024 Cesium-137 1.93E+OO 2.02E+OO 3.47E+OO pCi/L Surface Water 660511002 3/26/2024 Cobalt-58 1.39E-01 1.08E+OO 3.63E+OO pCi/L Surface Water 660511002 3/26/2024 Cobalt-60 8.40E-01 1.11E+OO 3.78E+OO pCi/L Surface Water 660511002 3/26/2024 lodine-131 1.63E+OO 1.27E+OO 4.40E+OO pCi/L Surface Water 660511002 3/26/2024 lron-59 1.92E-01 1.86E+OO 6.llE+OO pCi/L Surface Water 660511002 3/26/2024 Lanthanum-140

-3.31E-01 1.42E+OO 4.63E+OO pCi/L Surface Water 660511002 3/26/2024 Manganese-54

-1.70E+OO 1.02E+OO 3.06E+OO pCi/L Surface Water 660511002 3/26/2024 Niobium-95 2.16E-01 1.05E+OO 3.54E+OO pCi/L Surface Water 660511002 3/26/2024 Zinc-65

-1.67E+OO 2.23E+OO 6.85E+OO pCi/L Surface Water 660511002 3/26/2024 Zirconium-95

-1.97E+OO 1.76E+OO 5.53E+OO pCi/L Surface Water 665744002 4/30/2024 Barium-140 1.99E+OO 1.72E+OO 6.lOE+OO pCi/L Surface Water 665744002 4/30/2024 Cesium-134 1.74E+OO 8.55E-01 1.85E+OO pCi/L Surface Water 665744002 4/30/2024 Gesium-137 4.90E-01 4.43E-01 1.56E+OO pGi/L Surface Water 665744002 4/30/2024 Cobalt-58

-3.05E-01 3.91E-01 1.22E+OO pCi/L Surface Water 665744002 4/30/2024 Cobalt-60 3.20E-01 5.llE-01 1.69E+OO pCi/L Surface Water 665744002 4/30/2024 lodine-131 3.52E-01 7.04E-01 2.24E+OO pCi/L Surface Water 665744002 4/30/2024 lron-59

-7.65E-01 9.97E-01 2.65E+OO pCi/L Surtace Water 665744002 4/30/2024 Lanthanum-140

-1.98E+OO 8.47E-01 1.88E+OO pCi/L Surface Water 665744002 4/30/2024 M anga nese-54 2.35E-01 4.54E-01 1.53E+OO pCi/L Surface Water 665744002 4/30/2024 Niobium-95 5.63E-01 4.71E-01 1.65E+OO pCi/L

Annual Environmental Operating Report j YEAR: 2024 I Pag_e 74 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-1 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 665744002 4/30/2024 Zinc-65 1.17E+00 9.04E-01 3.16E+00 pCi/L Surface Water 665744002 4/30/2024 Zirconium-95

-3.03E-01 8.05E-01 2.61E+0O pCi/L Surface Water 669519002 5/28/2024 Barium-140 1.92E+00 2.63E+00 9.00E+0O pCi/L Surface Water 669519002 5/28/2024 Cesium-134 3.03E-01 5.75E-01 1.91E+0O pCi/L Surface Water 669519002 5/28/2024 Cesium-137 4.16E-01 6.21E-01 2.09E+0O pCi/L Surface Water 669519002 5/28/2024 Cobalt-58 7.81E-03 5.82E-01 1.88E+0O pCi/L Surface Water 669519002 5/28/2024 Cobalt-60

-3.54E-01 5.20E-01 1.66E+0O pCi/L Surface Water 669519002 5/28/2024 lodine-131 9.69E-02 1.00E+00 3.42E+0O pCi/L Surface Water 669519002 5/28/2024 lron-59

-8.89E-01 1.55E+00 3.12E+00 pCi/L Surface Water 669519002 5/28/2024 Lanthanum-140 1.14E+00 9.76E-01 3.45E+00 pCi/L Surface Water 669519002 5/28/2024 Manganese-54

-1.00E+00 5.90E-01 1.75E+00 pCi/L Surface Water 669519002 5/28/2024 Niobium-95 7.72E-01 5.80E-01 1.99E+00 pCi/L Surface Water 669519002 5/28/2024 Zinc-65 2.97E-01 1.08E+00 3.72E+00 pCi/L Surface Water 669519002 5/28/2024 Zirconium-95

-3.43E-01 1.08E+O0 3.45E+0O pCi/L Surface Water 673283002 6/25/2024 Barium-140

-8.26E-01 2.48E+00 7.94E+0O pCi/L Surface Water 673283002 6/25/2024 Cesium-134 9.78E-01 5.98E-01 1.89E+0O pCi/L Surface Water 673283002 6/25/2024 Cesium-137

-9.53E-02 5.70E-01 1.81E+0O pCi/L Surface Water 673283002 6/25/2024 Cobalt-58

-4.31E-01 4.68E-01 1.52E+0O pCi/L Surface Water 673283002 6/25/2024 Cobalt-60

-1.32E-01 5.30E-01 1.69E+00 pCi/L Surface Water 673283002 6/25/2024 lodine-131

-6.48E-01 8.93E-01 2.92E+0O pCi/L Surface Water 673283002 6/25/2024 lron-59 1.44E-02 9.57E-01 3.16E+00 pCi/L Surface Water 673283002 6/25/2024 Lanthanum-140

-4.06E-01 8.43E-01 2.76E+00 pCi/L Surface Water 673283002 6/25/2024 Manganese-54 7.45E-01 4.63E-01 1.66E+00 pCi/L Surface Water 673283002 6/25/2024 Niobium-95 2.861;-01 4.89E-01 1.70E+00 pCi/L Surface Water 673283002 6/25/2024 Zinc-65

-1.99E-02 1.0lE+00 3.32E+0O pCi/L Surface Water 673283002 6/25/2024 Zirconium-95

-7.10E-01 8.31E-01 2.72E+0O pCi/L Surface Water 678790002 7/30/2024 Barium-140

-1.54E+00 2.07E+00 6.36E+0O pCi/L Surface Water 678790002 7/30/2024 Cesium-134 2.88E-01 5.08E-01 1.75E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 j Page 75 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-1 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 678790002 7/30/2024 Cesium-137 3.22E-01 1.24E+00 1.71E+0O pCi/L Surface Water 678790002 7/30/2024 Cobalt-58 7.09E-02 5.24E-01 1.65E+00 pCi/L Surface Water 678790002 7/30/2024 Cobalt-60 5.13E-01 5.03E-01 1.76E+00 pCi/L Surface Water 678790002 7/30/2024 lodine-131

-1.05E-02 7.llE-01 2.31E+00 pCi/L Surface Water 678790002 7/30/2024 lron-59 l.38E-01 9.94E-01 3.32E+00 pCi/L Surface Water 678790002 7/30/2024 Lanthanum-140 2.llE-01 7.23E-01 2.39E+00 pCi/L Surface Water 678790002 7/30/2024 Manganese-54

-1.20E-01 4.98E-01 1.66E+00 pCi/L Surface Water 678790002 7/30/2024 Niobium-95 1.61E+00 1.22E+00 1.58E+00 pCi/L Surface Water 678790002 7/30/2024 Zinc-65 1.33E+00 1.03E+00 3.64E+00 pCi/L Surface Water 678790002 7/30/2024 Zirconium-95

-7.75E-01 8.98E-01 2.68E+0O pCi/L Surface Water 683293002 8/27/2024 Barium-140 3.57E+00 3.99E+00 1.36E+01 pCi/L Surface Water 683293002 8/27/2024 Cesium-134 3.93E-01 5.21E-01 1.74E+0D pCi/L Surface Water 683293002 8/27/2024 Cesium-137

-2.65E-01 4.79E-01 1.54E+0O pCi/L Surface Water 683293002 8/27/2024 Cobalt-58

-3.69E-01 5.64E-01 1.78E+0O pCi/L Surface Water 683293002 8/27/2024 Cobalt-60 7.37E-01 4.81E-01 1.72E+00 pCi/L Surface Water 683293002 8/27/2024 lodine-131

-6.0lE-01 1.85E+00 6.27E+00 pCi/L Surface Water 683293002 8/27/2024 lron-59

-1.51E+00 9.86E-01 3.12E+00 pCi/L Surface Water 683293002 8/27/2024 Lanthanum-140

-8.56E-01 1.13E+00 3.53E+00 pCi/L Surface Water 683293002 8/27/2024 Manganese-54 5.93E-01 5.lOE-01 1.71E+00 pCi/L Surface Water 683293002 8/27/2024 Niobium-95 7.29E-02 5.67E-01 1.85E+00 pCi/L Surface Water 683293002 8/27/2024 Zinc-65

-4.13E-01 8.39E-01 2.78E+00 pCi/L Surface Water 683293002 8/27/2024 Zirconium-95

-3.71E-01 9.88E-01 3.17E+00 pCi/L Surface Water 687543002 9/24/2024 Barium-140

-7.26E-01 3.45E+00 1.11E+01 pCi/L surtace Water 687543002 9/24/2024 Cesium-134 7.67E-01 6.61E-01 2.lOE+0O pCi/L Surface Water 687543002 9/24/2024 Cesium-137 2.83E-01*

6.0SE-01 1.98E+0O pCi/L Surface Water 687543002 9/24/2024 Cobalt-58

-1.17E+00 6.72E-01 1.79E+0O pCi/L Surface Water 687543002 9/24/2024 Cobalt-60 5.52E-01 6.53E-01 2.20E+00 pCi/L Surtace Water 687543002 9/24/2024 lodine-131

-1.07E+00 1.83E+00 4.51E+O0 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 76 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant SW-1 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 687543002 9/24/2024 lron-59 2.07E+OO 1.32E+OO 4.65E+OO pCi/L Surface Water 687543002 9/24/2024 Lanthanum-140

-2.02E+OO 1.25E+OO 3.79E+OO pCi/L Surface Water 687543002 9/24/2024 Manganese-54 9.20E-01 5.11E-01 1.85E+OO pCi/L Surface Water 687543002 9/24/2024 Niobium-95 1.04E+OO 1.62E+OO 2.07E+OO pCi/L Surface Water 687543002 9/24/2024 Zinc-65

-7.01E-01 1.29E+OO 4.12E+OO pCi/L Surface Water 687543002 9/24/2024 Zirconium-95

-9.38E-01 1.05E+OO 3.42E+OO pCi/L Surface Water 693015002 10/29/2024 Barium-140 3.31E+OO 2.50E+OO 8.71E+OO pCi/L Surface Water 693015002 10/29/2024 Cesium-134 3.74E-01 4.95E-01 1.65E+OO pCi/L Surface Water 693015002 10/29/2024 Cesium-137 2.65E-01 4.58E-01 1.53E+OO pCi/L Surface Water 693015002 10/29/2024 Cobalt-58 6.54E-01 4.96E-01 1.70E+OO pCi/L Surface Water 693015002 10/29/2024 Cobalt-60

-8.49E-02 5.12E-01 1.68E+OO pCi/L Surface Water 693015002 10/29/2024 lodine-131

-3.92E-01 9.40E-01 3.15E+OO pCi/L Surface Water 693015002 10/29/2024 lron-59

-1.14E+OO 9.22E-01 2.89E+OO pCi/L Surface Water 693015002 10/29/2024 Lanthanum-140 2.32E+OO 7.25E-01 2.67E+OO pCi/L Surface Water 693015002 10/29/2024 Manganese-54

-8.41E-02 4.39E-01 1.39E+OO pCi/L Surface Water 693015002 10/29/2024 Niobium-95

-1.46E+OO 7.40E-01 1.47E+OO pCi/L Surface Water 693015002 10/29/2024 Zinc-65 1.64E+OO 9.31E-01 3.15E+OO pCi/L Surface Water 693015002 10/29/2024 Zirconium-95 4.29E-01 8.38E-01 2.78E+OO pCi/L Surface Water 698142002 11/26/2024 Barium-140 1.25E+OO 3.30E+OO 1.09E+01 pCi/L Surface Water 698142002 11/26/2024 Cesium-134

-7.74E-01 5.81E-01 1.82E+OO pCi/L Surface Water 698142002 11/26/2024 Cesium-137 8.73E-01 6.09E-01 2.09E+OO pCi/L Surface Water 698142002 11/26/2024 Cobalt-58

-7.70E-01 5.21E-01 1.SOE+OO pCi/L Surface Water 698142002 11/26/2024 Cobalt-SO 9.64E-01 6.89E-01 2.42E+OO pCi/L Surface Water 698142002 11/26/2024 lodine-131

-2.0lE-01 1.19E+OO 3.97E+OO pCi/L Surface Water 698142002 11/26/2024 lron-59

-2.34E+OO 1.36E+OO 4.00E+OO pCi/L Surface Water 698142002 11/26/2024 Lanthanum-140

-1.09E+OO 1.29E+OO 3.39E+OO pCi/L Surface Water 698142002 11/26/2024 Manganese-54

-7.85E-01 7.03E-01 2.0lE+OO pCi/L Surface Water 698142002 11/26/2024 Niobium-95 7.31E-01 5.46E-01 1.97E+OO pCi/L M*.. **-*~**-

Annual Environmental Operating Report I YEAR: 2024 I Page 77 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-1 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 698142002 11/26/2024 Zinc-65 7.67E-01 1.39E+OO 4.18E+OO pCi/L Surface Water 698142002 11/26/2024 Zirconium-95 5.48E+OO 1.66E+OO 4.00E+OO pCi/L Surface Water 703333002 12/31/2024 Barium-140 5.58E+OO 3.76E+OO 1.32E+01 pCi/L Surface Water 703333002 12/31/2024 Cesium-134 1.82E-01 5.62E-01 1.85E+OO pCi/L Surface Water 703333002 12/31/2024 Cesium-137 1.09E+OO 5.63E-01 1.99E+OO pCi/L Surface Water 703333002 12/31/2024 Cobalt-58 6.02E-02 5.54E-01 1.81E+OO pCi/L Surface Water 703333002 12/31/2024 Cobalt-SO

-8.92E-01 4.93E-01 1.45E+OO

. pCi/L Surface Water 703333002 12/31/2024 lodine-131 1.56E+OO 1.61E+OO 5.65E+OO pCi/L Surface Water 703333002 12/31/2024 lron-59

-5.SOE-01 1.18E+OO 3.43E+OO pCi/L Surface Water 703333002 12/31/2024 Lanthanum-140 4.81E-01 1.23E+OO 4.15E+OO pCi/L Surface Water 703333002 12/31/2024 Manganese-54 6.21E-01 5.17E-01 1.76E+OO pCi/L Surface Water 703333002 12/31/2024 Niobium-95

-2.69E-01 5.BOE-01 l.85E+OO pCi/L Surface Water 703333002 12/31/2024 Zinc-65 3.37E+OO 1.92E+OO 3.17E+OO pCi/L Surface Water 703333002 12/31/2024 Zirconium-95 2.14E-01.

1.03E+OO 3.39E+OO pCi/L Surtace Water 703333002 12/31/2024 lodine-131 1.56E+OO 1.61E+OO 5.65E+OO pCi/L Surface Water 703333002 12/31/2024 lron-59

-5.SOE-01 1.18E+OO 3.43E+OO pCi/L Surface Water 703333002 12/31/2024 La nth a nu m-140 4.81E-01 1.23E+OO 4.15E+OO pCi/L Surface Water 703333002 12/31/2024 Manganese-54 6.21E-01 5.17E-01 1.76E+OO pCi/L Surface Water 703333002 12/31/2024 Niobium-95

-2.69E-01 5.80E-01 1.85E+OO pCi/L Surface Water 703333002 12/31/2024 Zinc-65 3.37E+OO 1.92E+OO 3.17E+OO pCi/L Surface Water 703333002 12/31/2024 Zirconium-95 2.14E-01 1.03E+OO 3.39E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 78 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-1 Quarterly Composite Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 665489002 3/26/2024 Tritium 1.01E+04 4.73E+02 7.26E+02 pCi/L Surface Water 678504002 6/25/2024 Tritium 1.26E+04 6.26E+02 7.63E+02 pCi/L Surface Water 692597002 9/24/2024 Tritium 1.17E+04 6.10E+02 7.71E+02 pCi/L Surface Water 707025002 12/31/2024 Tritium 8.65E+03 2.93E+02 5.44E+02 pCi/L SW-2 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 653791002 1/30/2024 Barium-140

-8.51E-01 3.17E+0O 1.05E+01 pCi/L Surface Drinking 653791002 1/30/2024 Cesium-134 3.09E-01 6.13E-01 2.03E+00 pCi/L Surface Drinking 653791002 1/30/2024 Cesium-137 1.74E-01 5.89E-01 1.96E+00 pCi/L Surface Drinking 653791002 1/30/2024 Cobalt-58

-2.08E-01 5.57E-01 1.77E+00 pCi/L Surface Drinking 653791002 1/30/2024 Cobalt-60 7.98E-01 5.37E-01 1.95E+00 pCi/L Surface Drinking 653791002 1/30/2024 lron-59 21E+00 9.88E-01 3.12E+00 pCi/L Surface Drinking 653791002 1/30/2024 Lanthanum-140 4.27E-02 8.36E-01 2.77E+00 pCi/L Surface Drinking 653791002 1/30/2024 Manganese-54

-9.86E-01 5.83E-01 1.73E+00 pCi/L Surface Drinking 653791002 1/30/2024 Niobium-95 6.96E-01 6.46E-01 2.19E+00 pCi/L Surface Drinking 653791002 1/30/2024 Zinc-65 2.70E-01 1.0lE+00 3.09E+00 pCi/L Surface Drinking 653791002 1/30/2024 Zirconium-95

-1.53E+00 1.08E+00 3.27E+00 pCi/L Surface Drinking 653791002 1/30/2024 lodine-131 6.14E-01 2.87E-01 8.88E-01 pCi/L Surface Drinking 657015002 2/27/2024 lodine-131 1.71E-01 2.22E-01 7.07E-01 pCi/L Surface Drinking 657015002 2/27/2024 Barium-140

-9.84E-01 2.46E+00

8.01E+00 pCi/L Surface Drinking 657015002 2/27/2024 Cesium-134

-6.14E-01 5.42E-01 1.63E+00 pCi/L Surface Drinking 657015002 2/27/2024 Cesium-137

-2.83E-01 5.28E-01 1.68E+00 pCi/L Surface Drinking 657015002 2/27/2024 Cobalt-58 4.27E-01 5.15E-01 1.73E+00 pCi/L Surface Drinking 657015002 2/27/2024 Cobalt-60 5.32E-01 5.76E-01 2.02E+00 pCi/L Surface Drinking 657015002 2/27/2024 lodine-131 2.31E+00 1.37E+00 3.05E+00 pCi/L Surface Drinking 657015002 2/27/2024 lron-59 7.29E-01 1.15E+00 4.0lE+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 79 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-2 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 657015002 2/27/2024 Lanthanum-140

-1.86E-01 8.93E-01 2.88E+OO pCi/L Surface Drinking 657015002 2/27/2024 Manganese-54 9.66E-01 5.43E-01 1.75E+OO pCi/L Surface Drinking 657015002 2/27/2024 Niobium-95 3.39E+OO 1.52E+OO 1.57E+OO pCi/L Surface Drinking 657015002 2/27/2024 Zinc-65 9.0lE-01 9.77E-01 3.39E+OO pCi/L Surface Drinking 657015002 2/27/2024 Zirconium-95 1.33E+OO 1.03E+OO 2.74E+OO pCi/L Surface Drinking 660509002 3/26/2024 Barium-140 5.23E+OO 2.47E+OO 8.88E+OO pCi/L Surface Drinking 660509002 3/26/2024 Cesium-134 1.42E+OO 6.00E-01 2.19E+OO pCi/L Surface Drinking 660509002 3/26/2024 Cesium-137

-4.00E-01 6.04E-01 1.89E+OO pCi/l Surface Drinking 660509002 3/26/2024 Cobalt-58

-1.04E-01 5.42E-01 1.71E+OO pCi/L Surface Drinking 660509002 3/26/2024 Cobalt-60 7.51E-01 5.70E-01 2.06E+OO pCi/l Surface Drinking 660509002 3/26/2024 lodine-131 2.38E-01 7.42E-01 2.53E+OO pCi/l Surface Drinking 660509002 3/26/2024 lron-59

-1.65E+OO 1.05E+OO 3.17E+OO pCi/l Surface Drinking 660509002 3/26/2024 Lanthanum-140 9.34E-01 9.93E-01 3.11E+OO pCi/l Surface Drinking 660509002 3/26/2024 Manganese-54

-2.83E-01 5.65E-01 1.75E+OO pCi/L Surface Drinking 660509002 3/26/2024 Niobium-95

-1.01E+OO 7_.16E-01 1.54E+OO pCi/l Surface Drinking 660509002 3/26/2024 Zinc-65

-1.50E+OO 1.05E+OO 3.18E+OO pCi/L Surface Drinking 660509002 3/26/2024 Zirconium-95

-1.40E+OO 9.45E-01 2.75E+OO pCi/L Surface Drinking 660509002 3/26/2024 lodine-131

-3.35E-01 2.19E-01 7.89E-01 pCi/L Surface Drinking 665741002 4/30/2024 Barium-140

-1.49E+OO 2.61E+OO 8.53E+OO pCi/L Surface Drinking 665741002 4/30/2024 Cesium-134 8.72E-03 7.41E-01 2.37E+OO pCi/L Surface Drinking 665741002 4/30/2024 Cesium-137 5.25E-01 6.73E-01 2.28E+OO pCi/L Surface Drinking 665741002 4/30/2024 Cobalt-58 1.50E-01 6.lOE-01 2.0BE+OO pCi/L Surface Drinking 665741002 4/30/2024 Cobalt-60

-4.18E-02 7.31E-01 2.44E+OO pCi/L Surface Drinking 665741002 4/30/2024 lodine-131 9.68E-01 8.0BE-01 2.73E+OO pCi/L Surface Drinking 665741002 4/30/2024 lron-59

-2.88E+OO 1.48E+OO 4.32E+OO pCi/L Surface Drinking 665741002 4/30/2024 Lanthanum-140 5.23E-03 1.04E+OO 3.42E+OO pCi/L Surface Drinking 665741002 4/30/2024 M anga nese-54

-4.31E-01 6.03E-01 1.96E+OO pCi/L Surface Drinking 665741002 4/30/2024 Niobium-95

-7.64E-01 6.69E-01 2.03E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 80 of 138 Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant SW-2 Monthly Composite Gamma Spectrum Sample Type lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 665741002 4/30/2024 Zinc-65

-8.49E-02 1.39E+0O 4.54E+00 pCi/L Surface Drinking 665741002 4/30/2024 Zirconium-95

-1.35E+00 1.16E+O0 3.49E+00 pCi/L Surface Drinking 665741002 4/30/2024 lodine-131

-2.86E-01 2.26E-01 7.62E-01 pCi/L Surface Drinking 669524002 5/28/2024 Barium-140

-2.33E+00 4.35E+O0 1.36E+01 pCi/L Surface Drinking 669524002 5/28/2024 Cesium-134

-9.41E-01 9.91E-01 2.71E+00 pCi/L Surface Drinking 669524002 5/28/2024 Cesium-137 3.38E-01 9.93E-01 3.03E+00 pCi/L Surface Drinking 669524002 5/28/2024 Cobalt-58

-7.77E-01 8.33E-01 2.65E+00 pCi/L Surface Drinking 669524002 5/28/2024 Cobalt-60

-8.43E-02 1.00E+00 3.19E+00 pCi/L Surface Drinking 669524002 5/28/2024 lodine-131

-3.80E-01 1.42E+00 4.62E+00 pCi/L Surface Drinking 669524002 5/28/2024 lron-59 2.90E+00 1.63E+00 5.90E+00 pCi/L Surface Drinking 669524002 5/28/2024 Lanthanum-140 6.42E-01 1.28E+00 4.43E+00 pCi/L Surface Drinking 669524002 5/28/2024 Manganese-54

-7.0lE-01 8.04E-01 2.56E+00 pCi/L Surface Drinking 669524002 5/28/2024 Niobium-95 2.26E+00 8.98E-01 3.33E+00 pCi/L Surface Drinking 669524002 5/28/2024 Zinc-65

-1.17E-01 1.89E+00 6.13E+00 pCi/L Surface Drinking 669524002 5/28/2024 Zi rconiu m-95

-2.30E+00 1.S0E+00 4.66E+00 pCi/L Surface Drinking 669524002 5/28/2024 lodine-131 3.38E-01 2.34E-01 7.39E-01 pCi/L Surface Drinking 673279002 6/25/2024 Barium-140 1.89E+00 3.05E+00 1.00E+0l pCi/L Surface Drinking 673279002 6/25/2024 Cesium-134 5.45E-01 6.43E-01 2.23E+00 pCi/L Surface Drinking 673279002 6/25/2024 Cesium-137 7.51E-02 6.71E-01 2.28E+00 pCi/L Surface Drinking 673279002 6/25/2024 Cobalt-58

-3.76E-01 6.07E-01 1.96E+00 pCi/L Surface Drinking 673279002 6/25/2024 Cobalt-60 1.15E-01 6.04E-01 1.96E+00 pCi/L Surface Drinking 673279002 6/25/2024 lodine-131 3.81E-01 1.09E+0O 3.60E+00 pCi/L Surface Drinking 673279002 6/25/2024 lron-59

-7.56E-01 1.42E+00 4.47E+00 pCi/L Surface Drinking 673279002 6/25/2024 Lanthanum-140 5.95E-01 1.17E+00 4.02E+00 pCi/L Surface Drinking 673279002 6/25/2024 Manganese-54 8.99E-01 5.58E-01 2.00E+00 pCi/L Surface Drinking 673279002 6/25/2024 Niobium-95

-9.0lE-01 5.91E-01 1.83E+00 pCi/L Surface Drinking 673279002 6/25/2024 Zinc-65

-3.55E-01 1.34E+00 4.27E+00 pCi/L Surface Drinking 673279002 6/25/2024 Zirconium-95

-1.39E+00 1.13E+00 3.57E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 81 of 138 Company: Vistra Corp

l Comanche Peak Nuclear Power Plant SW-2 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 673279002 6/25/2024 lodine-131 3.89E-01 2.98E-01 9.61E-01 pCi/L Surface Drinking 678789002 7/30/2024 Barium-140 1.44E+00 1.87E+00 6.36E+00 pCi/L Surface Drinking 678789002 7/30/2024 Cesium-134 1.13E+00 4.70E-01 1.70E+00 pCi/L Surface Drinking 678789002 7/30/2024 Cesium-137

-2.65E-01 4.34E-01 1.37E+00 pCi/L Surface Drinking 678789002 7/30/2024 Cobalt-58 1.89E-01 4.47E-01 1.47E+00 pCi/L Surface Drinking 678789002 7/30/2024 Cobalt-60 6.73E-01 4.68E-01 1.69E+00 pCi/L Surface Drinking 678789002 7/30/2024 lodine-131 8.01E-01 6.19E-01 1.99E+00 pCi/L Surface Drinking 678789002 7/30/2024 lron-59

-7.17E-01 1.18E+00 2.83E+00 pCi/L Surface Drinking 678789002 7/30/2024 Lanthanum-140

-3.13E-01 6.50E-01 2.05E+00 pCi/L Surface Drinking 678789002 7/30/2024 Manganese-54

-8.0SE-01 5.79E-01 1.42E+00 pCi/L Surface Drinking 678789002 7/30/2024 Niobium-95

-1.58E-01 4.19E-01 1.32E+00 pCi/L Surface Drinking 678789002 7/30/2024 Zinc-65 5.45E-01 9.53E-01 3.30E+00 pCi/L Surface Drinking 678789002 7/30/2024 Zirconium-95 2.31E-01 7.52E-01 2.47E+00 pCi/L Surface Drinking 678789002 7/30/2024 lodine-131 8.14E-01 2.83E-01 8.28E-01 pCi/L Surface Drinking 683314002 8/27/2024 lodine-131

-3.21E-01 1.75E-01 5.99E-01 pCi/L Surface Drinking 683314002 8/27/2024 Barium-140 1.01E+00 3.94E+00 1.30E+01 pCi/L Surface Drinking 683314002 8/27/2024 Cesium-134 1.78E+00 8.77E-01 2.10E+00 pCi/L Surtace Drinking 683314002 8/27/2024 Cesium-137

-3.82E-01 4.89E-01 1.51E+00 pCi/L Surface Drinking 683314002 8/27/2024 Cobalt-58 1.80E-02 4.83E-01 1.64E+O0 pCi/L Surface Drinking 683314002 8/27/2024 Cobalt-60 6.95E-01 5.34E-01 1.69E+O0 pCi/L Surface Drinking 683314002 8/27/2024 lodine-131

-3.86E+00 1.92E+00 6.06E+O0 pCi/L Surface Drinking 683314002 8/27/2024 lron-59

-1.58E+00 1.20E+00 3.69E+00 pCi/L Surface Drinking 683314002 8/27/2024 Lanthanum-140

-2.22E+00 1.46E+00 4.44E+O0 pCi/L Surface Drinking 683314002 8/27/2024 Manganese-54

-1.34E-01 4.88E-01 1.63E+00 pCi/L Surface Drinking 683314002 8/27/2024 Niobium-95 7.58E-01 5.07E-01 1.82E+00 pCi/L Surface Drinking 683314002 8/27/2024 Zinc-65

-1.03E+00 1.11E+00

3.49E+00 pCi/L Surface Drinking 683314002 8/27/2024 Zirconium-95

-4.0lE-01 1.08E+00 3.17E+00 pCi/L Surface Drinking 687525002 9/24/2024 Barium-140 5.44E-01 2.38E+00 7.92E+00 pCi/L

Annual Environmental Operating Report j YEAR: 2024 j

Page 82 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-2 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 687525002 9/24/2024 Cesium-134

-4.06E-01 5.42E-01 1.68E+00 pCi/L Surface Drinking 687525002 9/24/2024 Cesium-137 1.75E+00 8.06E-01 1.60E+00 pCi/L Surface Drinking 687525002 9/24/2024 Cobalt-58 3.48E-01 4.83E-01 l.61E+00 pCi/L Surface Drinking 687525002 9/24/2024 Cobalt-60 8.83E-01 4.31E-01 1.63E+00 pCi/L Surface Drinking 687525002 9/24/2024 lodine-131

-1.13E+00 8.94E-01 2.90E+00 pCi/L Surface Drinking 687525002 9/24/2024 lron-59 1.36E-01 9.83E-01 3.34E+00 pCi/L Surface Drinking 687525002 9/24/2024 Lanthanum-140

-1.01E+00 8.43E-01 2.52E+00 pCi/L Surface Drinking 687525002 9/24/2024 Manganese-54

-7.17E-0l 4.53E-01 1.32E+00 pCi/L Surface Drinking 687525002 9/24/2024 Niobium-95 2.87E-01 4.61E-01 1.53E+00 pCi/L Surface Drinking 687525002 9/24/2024 Zinc-65 4.92E-01 8.55E-01 2.98E+00 pCi/L Surface Drinking 687525002 9/24/2024 Zirconium-95

-1.21E+0O 8.22E-01 2.44E+00 pCi/L Surface Drinking 687525002 9/24/2024 lodine-131

-1.64E-01 2.46E-01 8.48E-01 pCi/L Surface Drinking 693050002 10/29/2024 Barium-140 1.67E+00 4.93E+00 1.17E+01 pCi/L Surface Drinking 693050002 10/29/2024 Cesium-134

-3.63E-02 7.26E-01 2.31E+00 pCi/L Surtace Drinking 693050002 10/29/2024 Cesium-137

-1.78E-01 6.84E-01 2.19E+00 pCi/L Surface Drinking 693050002 10/29/2024 Cobalt-58 4.96E-01 7.12E-01 2.36E+00 pCi/L Surface Drinking 693050002 10/29/2024 Cobalt-60

-3.13E-01 6.82E-01 2.16E+00 pCi/L Sutiace Drinking 693050002 10/29/2024 lodine-131

-9.72E-01 1.21E+00 4.01E+00 pCi/L Surface Drinking 693050002 10/29/2024 lron-59

-3.38E-01 1.46E+00 4.82E+00 pCi/L Surface Drinking 693050002 10/29/2024 Lanthanum-140

-2.59E+00 1.81E+00 4.11E+00 pCi/L Surface Drinking 693050002 10/29/2024 Manganese-54

-7.42E-01 6.87E-01 2.05E+00 pCi/L Surface Drinking 693050002 10/29/2024 Niobium-95 1.41E-01 9.89E-01 2.52E+00 pCi/L Surface Drinking 693050002 10/29/2024 Zinc-65

-1.41E+0O 1.32E+00 4.lOE+00 pCi/L Surface Drinking 693050002 10/29/2024 Zirconium-95

-7.97E-01 1.24E+00 3.83E+00 pCi/L Surface Drinking 693050002 10/29/2024 lodine-131

-1.0lE-01 2.62E-01 8.71E-01 pCi/L Surface Drinking 698143002 11/26/2024 lodine-131

-2.57E-01 2.39E-01 8.41E-01 pCi/L Surface Drinking 698143002 11/26/2024 Barium-140 2.92E+00 2.49E+00 8.61E+00 pCi/L Surface Drinking 698143002 11/26/2024 Cesium-134

-2.30E-01 5.50E-01 1.73E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Pa_g_e 83 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-2 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide i

Result Uncertainty MDC Units Surface Drinking 698143002 11/26/2024 Cesium-137 I

2.13E-01 4.90E-01 1.63E+00 pCi/L Surface Drinking 698143002 11/26/2024 Cobalt-58

-2.77E-02 4.59E-01 1.47E+00 pCi/L Surface Drinking 698143002 11/26/2024 Cobalt-60

-1.29E-01 4.58E-01 1.50E+00 pCi/L Surface Drinking 698143002 11/26/2024 lodine-131

-5.49E-01 9.61E-01 3.18E+00 pCi/L Surface Drinking 698143002 11/26/2024 lron-59 3.27E+00 1.07E+00 3.38E+00 pCi/L Surface Drinking 698143002 11/26/2024 Lanthanum-140 8.45E-01 7.93E-01 2.81E+00 pCi/L Surface Drinking 698143002 11/26/2024 Manganese-54 7.61E-02 4.81E-01 1.55E+00 pCi/L Surface Drinking 698143002 11/26/2024 Niobium-95 6.58E-01 7.02E-01 1.52E+00 pCi/L Surface Drinking 698143002 11/26/2024 Zinc-65

-1.0SE+00 8.44E-01 2.63E+00 pCi/L Surtace Drinking 698143002 11/26/2024 Zirconium-95

-2.21E-01 8.52E-01 2.71E+00 pCi/L Surface Drinking 703332002 12/31/2024 Barium-140 3.69E-01 2.64E+00 8.80E+00 pCi/L Surface Drinking 703332002 12/31/2024 Cesium-134 5.56E-01 4.54E-01 1.55E+00 pCi/L Surface Drinking 703332002 12/31/2024 Cesium-137 2.15E-03 4.07E-01 1.33E+00 pCi/L Surface Drinking 703332002 12/31/2024 Cobalt-58 1.S0E-03 3.97E-01 1.28E+00 pCi/L Surface Drinking 703332002 12/31/2024 Cobalt-60 6.23E-01 4.26E-01 1.53E+00 pCi/L Surface Drinking 703332002 12/31/2024 lodine-131

-1.14E+00 1.15E+00 3.79E+00 pCi/L Surface Drinking 703332002 12/31/2024 lron-59

-1.67E+00 7.74E-01 2.33E+00 pCi/L Surface Drinking 703332002 12/31/2024 Lanthanum-140

-1.67E+00 8.96E-01 2.59E+00 pCi/L Surface Drinking 703332002 12/31/2024 Manganese-54

-3.78E-01 3.98E-01 1.23E+00 pCi/L Surface Drinking 703332002 12/31/2024 Niobium-95

-1.31E-01 4.46E-01 1.43E+00 pCi/L Surface Drinking 703332002 12/31/2024 Zinc-65

-4.92E-01 8.00E-01 2.63E+00 pCi/L Surface Drinking 703332002 12/31/2024 Zirconium-95

-6.24E-01 7.99E-01 2.51E+00 pCi/L Surface Drinking 703332002 12/31/2024 lodine-131 5.99E-01 2.64E-01 8.18E-01 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 84 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-2 Quarterly Composite 1ritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 665495002 3/26/2024 Tritium

-3.58E+02 2.68E+02 9.50E+02 pCi/L Surface Drinking 679339002 6/25/2024 Tritium 4.37E+03 4.34E+02 8.51E+02 pCi/L Surface Drinking 692595002 9/24/2024 Tritium

-1.09E+02 2.40E+02 8.09E+02 pCi/L Surface Drinking 707018002 12/31/2024 Tritium

-9.91E+01 1.62E+02 5.41E+02 pCi/L SW-2 Monthly Composite Gross Beta Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 653791002 1/30/2024 BETA 1.78E+OO 1.09E+OO 3.49E+OO pCi/L Surface Drinking 657015002 2/27/2024 BETA 5.44E+OO 1.89E+OO 5.82E+OO pCi/L Surface Drinking 660509002 3/26/2024 BETA 4.92E+OO 1.05E+OO 3.17E+OO pCi/L Surface Drinking 665741002 4/30/2024 BETA 6.37E+OO 7.21E-01 2.00E+OO pCi/L Surface Drinking 669524002 5/28/2024 BETA 3.23E+OO 1.36E+OO 2.06E+OO pCi/L Surface Drinking 673279002 6/25/2024 BETA 8.12E+OO 8.00E-01 2.16E+OO pCi/L Surface Drinking 678789002 7/30/2024 BETA 7.12E+OO 2.48E+OO 7.73E+OO pCi/L Surface Drinking 683314002 8/27/2024 BETA 9.78E+OO 2.22E+OO 6.76E+OO pCi/L Surtace Drinking 687525002 9/24/2024 BETA 3.30E+OO 8.07E-01 2.46E+OO pCi/L Surface Drinking 693050002 10/29/2024 BETA 8.42E+OO 1.19E+OO 3.41E+OO pCi/L Surface Drinking 698143002 11/26/2024 BETA 1.15E+01 1.17E+OO 3.14E+OO pCi/L Surface Drinking 703332002 12/31/2024 BETA 8.71E+OO 1.65E+OO 4.93E+OO pCi/L SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 653744004 1/30/2024 Barium-140 3.00E+OO 2.20E+OO 7.66E+OO pCi/L Surface Water 653744004 1/30/2024 Cesium-134 4.63E-03 5.26E-01 1.69E+OO pCi/L Surface Water 653744004 1/30/2024 Cesium-137

-6.18E-01 5.44E-01 1.68E+OO pCi/L Surtace Water 653744004 1/30/2024 Cobalt-58 3.16E-02 4.93E-01 1.58E+OO pCi/L Surface Water 653744004 1/30/2024 Cobalt-60

-7.73E-01 5.42E-01 1.37E+OO pCi/L Surface Water 653744004 1/30/2024 lodine-131

-4.82E-01 7.87E-01 2.60E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 85 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 653744004 1/30/2024 lron-59

-7.58E-01 1.20E+00 3.40E+0O pCi/L Surface Water 653744004 1/30/2024 Lanthanum-140 1.34E+00 7.81E-01 2.85E+0O pCi/L Surface Water 653744004 1/30/2024 Manganese-54

-3.22E-01 4.41E-01 1.35E+0O pCi/L Surface Water 653744004 1/30/2024 Niobium-95

-5.17E-01 8.91E-01 1.61E+0O pCi/L Surface Water 653744004 1/30/2024 Zinc-65

-3.61E+00 1.46E+00 2.81E+0O pCi/L Surface Water 653744004 1/30/2024 Zirconium-95

-3.33E-01 8.58E-01 2.70E+0O pCi/L Surface Water 657026004 2/27/2024 Barium-140

-1.07E+00 2.43E+00 7.85E+OO pCi/L Surface Water 657026004 2/27/2024 Cesium-134 1.06E+00 5.12E-01 1.81E+0O pCi/L Surface Water 657026004 2/27/2024 Cesium-137

-3.12E-01 5.27E-01 1.67E+00 pCi/L Surface Water 657026004 2/27/2024 Cobalt-58 3.15E-01 5.03E-01 1.50E+00 pCi/L Surface Water 657026004 2/27/2024 Cobalt-60 2.S0E-01 5.0lE-01 1.71E+00 pCi/L Surface Water 657026004 2/27/2024 lodine-131

-9.84E-02 8.0lE-01 2.69E+00 pCi/L Surface Water 657026004 2/27/2024 lron-59

-1.19E+00 9.98E-01 3.16E+00 pCi/L Surface Water 657026004 2/27/2024 Lanthanum-140

-3.85E-01 9.04E-01 2.87E+00 pCi/L Surface Water 657026004 2/27/2024 Manganese-54

-3.26E-01 4.56E-01 1.40E+00 pCi/L Surface Water 657026004 2/27/2024 Niobium-95 5.00E-01 4.85E-01 1.64E+00 pCi/L Surface Water 657026004 2/27/2024 Zinc-65

-2.11E-1-0Q 1.12E+00 2.82E+00 pCi/L Surface Water 657026004 2/27/2024 Zirconium-95

-7.59E-01 8.96E-01 2.76E+00 pCi/L Surface Water 660511004 3/26/2024 Barium-140

-7.75E-01 3.04E+00 1.00E+01 pCi/L Surface Water 660511004 3/26/2024 Cesium-134

-7.44E-01 9.25E-01 2.82E+00 pCi/L Surface Water 660511004 3/26/2024 Cesium-137

-4.24E-01 8.40E-01 2.67E+0O pCi/L Surface Water 660511004 3/26/2024 Cobalt-58 1.45E-01 7.26E-01 2.48E+0O pCi/L Surface Water 660511004 3/26/2024 Cobalt-60 2.34E+0O S.53E-01 2.92E+00 pCi/L Surface Water 660511004 3/26/2024 lodine-131

-5.12E-01 1.07E+00 3.38E+00 pCi/L Surface Water 660511004 3/26/2024 lron-59

-1.53E+00 1.59E+00 4.87E+00 pCi/L Surface Water 660511004 3/26/2024 Lanthanum-140 1.54E+00 1.24E+O0 4.47E+00 pCi/L Surface Water 660511004 3/26/2024 Manganese-54

-9.77E-02 9.07E-01 2.64E+00 pCi/L Surface Water 660511004 3/26/2024 Niobium-95 1.38E+00 7.32E-01 2.62E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 86 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 660511004 3/26/2024 Zinc-65

-1.90E+00 1.75E+0O 5.30E+00 pCi/L Surface Water 660511004 3/26/2024 Zirconium-95

-8.49E-01 1.43E+00 4.45E+00 pCi/L Surface Water 665744004 4/30/2024 Barium-140

-2.08E+00 3.52E+00 6.97E+00 pCi/L Surface Water 665744004 4/30/2024 Cesium-134

-1.60E+00 7.S0E-01 1.80E+00 pCi/L Surface Water 665744004 4/30/2024 Cesium-137

-1.10E+00 9.48E-01 1.74E+00 pCi/L Surface Water 665744004 4/30/2024 Cobalt-58

-8.32E-01 5.0lE-01 1.55E+00 pCi/L Surface Water 665744004 4/30/2024 Cobalt-60 1.65E-01 5.60E-01 1.85E+00 pCi/L Surface Water 665744004 4/30/2024 lodine-131 6.52E-01 7.27E-01 2.43E+0O pCi/L Surface Water 665744004 4/30/2024 lron-59

-2.69E+00 9.20E-01 2.46E+0O pCi/L Surface Water 665744004 4/30/2024 Lanthanum-140

-1.55E+00 7.86E-01 2.14E+OO pCi/L Surface Water 665744004 4/30/2024 Manganese-54 5.44E-01 4.63E-01 1.63E+00 pCi/L Surface Water 665744004 4/30/2024 Niobium-95

-2.63E-01 5.12E-01 1.68E+00 pCi/L Surface Water 665744004 4/30/2024 Zinc-65 1.48E-01 1.06E+00 3.51E+00 pCi/L Surface Water 665744004 4/30/2024 Zirconium-95

-1.41E+00 8.02E-01 2.47E+00 pCi/L Surface Water 669519004 5/28/2024 Barium-140

-7.14E-01 2.54E+00 8.27E+00 pCi/L Surface Water 669519004 5/28/2024 Cesium-134 9.96E-01 4.82E-01 1.72E+00 pCi/L Surface Water 669519004 5/28/2024 Cesium-137

-5.57E-01 6.94E-01 1.87E+00 pCi/L Surface Water 669519004 5/28/2024 Cobalt-58 9.93E-01 8.37E-01 1.33E+00 pCi/L Surface Water 669519004 5/28/2024 Cobalt-60 5.91E-01 4.89E-01 1.74E+00 pCi/L Surface Water 669519004 5/28/2024 lodine-131 3.33E-01 7.48E-01 2.56E+00 pCi/L Surface Water 669519004 5/28/2024 lron-59 7.40E-01 9.32E-01 3.27E+00 pCi/L Surface Water 669519004 5/28/2024 Lanthanum-140 6.72E-01 7.66E-01 2.67E+00 pCi/L Surface Water 669519004 5/28/2024 Manganese-54

-1.27E+00 4.70E-01 1.28E+00 pCi/L Surtace Water 669519004 5/28/2024 Niobium-95

-4.31E-01 8.36E-01 1.65E+00 pCi/L Surface Water 669519004 5/28/2024 Zinc-65

-2.12E-01 8.93E-01 2.97E+00 pCi/L Surface Water 669519004 5/28/2024 Zirconium-95

-7.85E-02 8.76E-01 2.81E+00 pCi/L Surface Water 673283004 6/25/2024 Barium-140 2.13E+00 2.45E+00 7.63E+00 pCi/L Surface Water 673283004 6/25/2024 Cesium-134 5.17E-01 4.83E-01 1.65E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 87 of 138 Company: Vistra Corp

] Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 673283004 6/25/2024 Cesium-137 1.79E+OO 6.70E-01 1.35E+OO pCi/L Surface Water 673283004 6/25/2024 Cobalt-58

-5.99E-01 4.23E-01 1.24E+OO pCi/L Surface Water 673283004 6/25/2024 Cobalt-SO 1.48E-01 5.08E-01 1.72E+OO pCi/L Surface Water 673283004 6/25/2024 lodine-131

-2.26E+OO 1.14E+OO 2.69E+OO pCi/L Surface Water 673283004 6/25/2024 lron-59 4.23E-01 8.88E-01 3.08E+OO pCi/L Surface Water 673283004 6/25/2024 Lanthanum-140

-4.44E-01 8.23E-01 2.59E+OO pCi/L Surface Water 673283004 6/25/2024 Manganese-54

-1.06E+OO 6.67E-01 1.48E+OO pCi/L Surface Water 673283004 6/25/2024 Niobium-95 3.64E-01 4.66E-01 1.57E+OO pCi/L Surface Water 673283004 6/25/2024 Zinc-65

-1.20E-01 9.67E-01 3.24E+OO pCi/L Surface Water 673283004 6/25/2024 Zirconium-95 3.78E-01 7.88E-01 2.62E+OO pCi/L Surface Water 678790004 7/30/2024 Barium-140 4.56E+OO 2.42E+OO 8.53E+OO pCi/L Surface Water 678790004 7/30/2024 Cesium-134 8.96E-02 6.17E-01 2.11E+OO pCi/L Surface Water 678790004 7/30/2024 Cesium-137 1.03E+OO 6.75E-01 2.31E+OO pCi/L Surface Water 678790004 7/30/2024 Cobalt-58

-2.87E-02 5.79E-01 1.95E+OO pCi/L Surface Water 678790004 7/30/2024 Cobalt-60

-2.36E-01 6.35E-01 2.00E+OO pCi/L Surface Water 678790004 7/30/2024 lodine-131

-7.47E-03 7.lOE-01 2.39E+OO pCi/L Surface Water 678790004 7/30/2024 lron-59

-1.27E+OO 1.20E+OO 3.70E+OO pCi/L Surface Water 678790004 7/30/2024 Lanthanum-140 2.62E+OO 1.86E+OO 3.10E+OO pCi/L Surface Water 678790004 7/30/2024 Manganese-54

-1.20E+OO 5.28E-01 1.56E+OO pCi/L Surface Water 678790004 7/30/2024 Niobium-95 1.77E+OO 5.92E-01 2.25E+OO pCi/L Surface Water 678790004 7/30/2024 Zinc-65

-1.78E-01 1.21E+OO 3.95E+OO pCi/L Surface Water 678790004 7/30/2024 Zirconium-95

-4.94E-01 1.03E+OO 3.44E+OO pCi/L Surface Water 683293004 8/27/2024 Barium-140

-3.04E+OO 4.16E+OO 1.03E+01 pCi/L Surface Water 683293004 8/27/2024 Cesium-134 5.59E-01 4.45E-01 1.50E+OO pCi/L Surface Water 683293004 8/27/2024 Cesium-137 8.84E-01 4.59E-01 1.11E+OO pCi/L Surface Water 683293004 8/27/2024 Cobalt-58

-2.14E-01 4.17E-01 1.31E+OO pCi/L Surface Water 683293004 8/27/2024 Cobalt-60

-5.00E-01 4.19E-01 1.31E+OO pCi/L Surface Water 683293004 8/27/2024 lodine-131 1.36E+OO 1.46E+OO 5.03E+OO pCi/l

Annual Environmental Opera~ing Report I YEAR: 2024 I Page 88 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 683293004 8/27/2024 lron-59 6.30E-02 8.53E-01 2.89E+OO pCi/L Surface Water 683293004 8/27/2024 Lanthanum-140

-5.65E-01 1.08E+OO 3.42E+OO pCi/L Surface Water 683293004 8/27/2024 Manganese-54 2.59E-01 3.98E-01 1.31E+OO pCi/L Surface Water 683293004 8/27/2024 Niobium-95 6.95E-01 4.43E-01 1.51E+OO pCi/L Surface Water 683293004 8/27/2024 Zinc-65

-2.60E-01 7.42E-01 2.46E+OO pCi/L Surface Water 683293004 8/27/2024 Zirconium-95 1.38E+OO 7.51E-01 2.60E+OO pCi/L Surface Water 687543004 9/24/2024 Barium-140 1.56E-01 2.67E+OO 8.85E+OO pCi/L Surface Water 687543004 9/24/2024 Cesium-134 4.69E-01 4.84E-01 1.64E+OO pCi/L Surface Water 687543004 9/24/2024 Cesium-137

-6.65E-01 4.52E-01 1.37E+OO pCi/L Surface Water 687543004 9/24/2024 Cobalt-58 1.51E-01 4.91E-01 1.60E+OO pCi/L Surface Water 687543004 9/24/2024 Cobalt-60

-2.32E-01 4.52E-01 1.39E+OO pCi/L Surface Water 687543004 9/24/2024 lodine-131 1.30E+OO 1.03E+OO 3.64E+OO pCi/L Surface Water 687543004 9/24/2024 lron-59

-1.53E-01 9.02E-01 3.01E+OO pCi/L Surface Water 687543004 9/24/2024 Lanthanum-140

-1.69E+OO 1.09E+OO 2.58E+OO pCi/L Surface Water 687543004 9/24/2024 Manganese-54

-3.84E-01 4.84E-01 1.49E+OO pCi/L Surface Water 687543004 9/24/2024 Niobium-95 2.32E-01 5.03E-01 1.66E+OO pCi/L Surface Water 687543004 9/24/2024 Zinc-65

-1.66E-01 9.0BE-01 3.02E+OO pCi/L Surface Water 687543004 9/24/2024 Zirconium-95 3.25E-01 8.06E-01 2.66E+OO pCi/L Surface Water 693015004 10/29/2024 Barium-140 1.32E+OO 2.67E+OO 9.10E+OO pCi/L Surface Water 693015004 10/29/2024 Cesium-134 1.71E-01 4.36E-01 1.45E+OO pCi/L Surface Water 693015004 10/29/2024 Cesium-137 9.0lE-01 4.71E-01 1.70E+OO pCi/L Surface Water 693015004 10/29/2024 Cobalt-58 4.92E-01 4.81E-01 1.65E+OO pCi/L Surtace Water 693015004 10/29/2024 Cobalt-60 6.45E-01 4.77E-01 1.75E+OO pCi/L Surface Water 693015004 10/29/2024 lodine-131

-2.21E-01 9.21E-01 3.11E+OO pCi/L Surface Water 693015004 10/29/2024 lron-59 2.05E+OO 8.0lE-01 3.03E+OO pCi/L Surface Water 693015004 10/29/2024 Lanthanum-140

-5.lOE-02 8.52E-01 2.79E+OO pCi/L Surface Water 693015004 10/29/2024

Manganese-54

-3.52E-02 4.76E-01 1.53E+OO pCi/L Surtace Water 693015004 10/29/2024 Niobium-95 4.0lE-01 4.46E-01 1.53E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 89 of 138 Company: Vistra Corp

! Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 693015004 10/29/2024 Zinc-65 4.26E-01 8.89E-01 3.11E+OO pCi/L Surface Water 693015004 10/29/2024 Zirconium-95

-3.74E-01 8.62E-01 2.73E+OO pCi/L Surface Water 698142004 11/26/2024 Barium-140

-2.68E+OO 4.79E+OO 1.23E+01 pCi/L Surface Water 698142004 11/26/2024 Cesium-134

-2.15E-01 7.05E-01 2.22E+OO pCi/L Surface Water 698142004 11/26/2024 Cesium-137

-3.00E-01 6.38E-01 2.04E+OO pCi/L Surface Water 698142004 11/26/2024 Cobalt-58

-7.64E-01 6.24E-01 1.98E+OO pCi/L Surface Water 698142004 11/26/2024 Cobalt-SO 3.SOE-01 9.65E-01 2.75E+OO pCi/L Surface Water 698142004 11/26/2024 lodine-131

-1.55E+OO 1.46E+OO 4.54E+OO pCi/L Surface Water 698142004 11/26/2024 lron-59 3.59E+OO 1.49E+OO 5.48E+OO pCi/L Surface Water 698142004 11/26/2024 Lanthanum-140

-5.62E-01 1.50E+OO 4.82E+OO pCi/L Surface Water 698142004 11/26/2024 Manganese-54

-1.04E-01 6.42E-01 2.15E+OO pCi/L Surface Water 698142004 11/26/2024 Niobium-95

-3.03E+OO 1.18E+OO 2.15E+OO pCi/L Surface Water 698142004 11/26/2024 Zinc-65

-2.66E-01 1.33E+OO 4.30E+OO pCi/L Surface Water 698142004 11/26/2024 Zirconium-95 3.46E-01 1.27E+OO 4.15E+OO pCi/L Surface Water 703333004 12/31/2024 Barium-140 5.36E-01 3.33E+OO 1.11E+01 pCi/L Surface Water 703333004 12/31/2024 Cesium-134 8.28E-01 6.0lE-01 1.87E+OO pCi/L Surface Water 703333004 12/31/2024 Cesium-137 5.29E-01 5.07E-01 1.72E+OO pCi/L Surface Water 703333004 12/31/2024 Cobalt-58 2.33E-01 5.25E-01 1.73E+OO pCi/L Surface Water 703333004 12/31/2024 Cobalt-SO

-7.55E-01 9.66E-01 2.05E+OO pCi/L Surface Water 703333004 12/31/2024 lodine-131 1.24E+OO 1.77E+OO.

5.52E+OO pCi/L Surface Water 703333004 12/31/2024 lron-59

-2.83E-01 1.lOE+OO 3.69E+OO pCi/L Surface Water 703333004 12/31/2024 Lanthanum-140 9.88E-01 1.17E+OO 3.65E+OO pCi/L Surface Water 703333004 12/31/2024 Manganese-54 1.08E+OO 4.78E-01 1.70E+OO pCi/L Surface Water 703333004 12/31/2024 Niobium-95

-4.62E-03 5.90E-01 1.91E+OO pCi/L Surface Water 703333004 12/31/2024 Zinc-65 1.47E-01 1.23E+OO 3.70E+OO pCi/L Surface Water 703333004 12/31/2024 Zirconium-95 1.70E+OO 9.92E-01 3.44E+OO pCi/L Surface Water 653744004 1/30/2024 Barium-140 3.00E+OO 2.20E+OO 7.66E+OO pCi/L Surface Water 653744004 1/30/2024 Cesium-134 4.63E-03 5.26E-01 1.69E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 90 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 653744004 1/30/2024 Cesium-137

-6.18E-01 5.44E-01 1.68E+00 pCi/L Surface Water 653744004 1/30/2024 Cobalt-58 3.16E-02 4.93E-01 1.58E+00 pCi/L Surface Water 653744004 1/30/2024 Cobalt-60

-7.73E-01 5.42E-01 1.37E+00 pCi/L Surface Water 653744004 1/30/2024 lodine-131

-4.82E-01 7.87E-01 2.60E+00 pCi/L Surface Water 653744004 1/30/2024 lron-59

-7.58E-01 1.20E+00 3.40E+00 pCi/L Surface Water 653744004 1/30/2024 Lanthanum-140 1.34E+00 7.81E-01 2.85E+00 pCi/L Surface Water 653744004 1/30/2024 Manganese-54

-3.22E-01 4.41E-01 1.35E+00 pCi/L Surface Water 653744004 1/30/2024 Niobium-95

-5.17E-01 8.91E-01 1.61E+00 pCi/L Surface Water 653744004 1/30/2024 Zinc-65

-3.61E+00 1.46E+00 2.81E+00 pCi/L Surface Water 653744004 1/30/2024 Zirconium-95

-3.33E-01 8.58E-01 2.70E+00 pCi/L Surface Water 657026004 2/27/2024 Barium-140

-1.07E+00 2.43E+00 7.85E+00 pCi/L Surface Water 657026004 2/27/2024 Cesium-134 1.06E+00 5.12E-01 1.81E+0O pCi/L Surface Water 657026004 2/27/2024 Cesium-137

-3.12E-01 5.27E-01 1.67E+0O pCi/L Surface Water 657026004 2/27/2024 Cobalt-58 3.15E-01 5.03E-01 1.50E+0O pCi/L Surface Water 657026004 2/27/2024 Cobalt-60 2.50E-01 5.0lE-01 1.71E+0O pCi/L Surface Water 657026004 2/27/2024 lodine-131

-9.84E-02 8.0lE-01 2.69E+0O pCi/L Surface Water 657026004 2/27/2024 lron-59

-1.19E+00 9.98E-01 3.16E+0O pCi/L Surface Water 657026004 2/27/2024.

Lanthanum-140

-3.85E-01 9.04E-01 2.87E+0O pCi/L Surface Water 657026004 2/27/2024 Manganese-54

-3.26E-01 4.56E-01 1.40E+0O pCi/L Surface Water 657026004 2/27/2024 Niobium-95 5.00E-01 4.85E-01 1.64E+0O pCi/L Surface Water 657026004 2/27/2024 Zinc-65

-2.llE+00 1.12E+00 2.82E+0O pCi/L Surface Water 657026004 2/27/2024 Zirconium-95

-7.59E-01 8.96E-01 2.76E+0O pCi/L Surface Water 660511004 3/26/2024 Barium-140

-7.75E-01 3.04E+00 1.00E+0l pCi/L Surface Water 660511004 3/26/2024 Cesium-134

-7.44E-01 9.25E-01 2.82E+00 pCi/L Surface Water 660511004 3/26/2024 Cesium-137

-4.24E-01 8.40E-01 2.67E+00 pCi/L Surface Water 660511004 3/26/2024 Cobalt-5.8 1.45E-01 7.26E-01 2.48E+00 pCi/L Surface Water 660511004 3/26/2024 Cobalt-60 2.34E+00 9.53E-01 2.92E+00 pCi/L Surface Water 660511004 3/26/2024 lodine-131

-5.12E-01 1.07E+00 3.38E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 91 of 138 Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma S2_ectrum Sample Type lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 660511004 3/26/2024 lron-59

-1.53E+00 1.59E+00 4.87E+00 pCi/L Surface Water 660511004 3/26/2024 La nth a nu m-140 1.54E+00 1.24E+00 4.47E+00 pCi/L Surface Water 660511004 3/26/2024 Manganese-54

-9.77E-02 9.07E-01 2.64E+00 pCi/L Surface Water 660511004 3/26/2024 Niobium-95 1.38E+00 7.32E-01 2.62E+00 pCi/L Surface Water 660511004 3/26/2024 Zinc-65

-1.90E+00 1.75E+00 5.30E+00 pCi/L Surface Water 660511004 3/26/2024 Zirconium-95

-8.49E-01 1.43E+00 4.45E+00 pCi/L Surface Water 665744004 4/30/2024 Barium-140

-2.08E+00 3.52E+00 6.97E+00 pCi/L Surface Water 665744004 4/30/2024 Cesium-134

-1.60E+00 7.60E-01 1.80E+00 pCi/L Surface Water 665744004 4/30/2024 Cesium-137

-1.l0E+00 9.48E-01 1.74E+00 pCi/L Surface Water 665744004 4/30/2024 Cobalt-58

-8.32E-01 5.0lE-01 1.55E+00 pCi/L Surface Water 665744004 4/30/2024 Cobalt-60 1.65E-01 5.60E-01 1.85E+00 pCi/L Surface Water 665744004 4/30/2024 lodine-131 6.52E-01 7.27E-01 2.43E+00 pCi/L Surface Water 665744004 4/30/2024 lron-59

-2.69E+00 9.20E-01 2.46E+00 pCi/L Surface Water 665744004 4/30/2024 Lanthanum-140

-1.55E+00 7.86E-01 2.14E+00 pCi/l Surface Water 665744004 4/30/2024 Manganese-54 5.44E-01 4.63E-01 1.63E+00 pCi/l Surface Water 665744004 4/30/2024 Niobium-95

-2.63E-01 5.12E-01 1.68E+00 pCi/L Surface Water 665744004 4/30/2024 Zinc-65 1.48E-01 1.06E+00 3.SlE+00 pCi/L Surface Water 665744004 4/30/2024 Zirconium-95

-1.41E+00 8.02E-01 2.47E+00 pCi/L Surface Water 669519004 5/28/2024 Barium-140

-7.14E-01 2.54E+00 8.27E+00 pCi/L Surface Water 669519004 5/28/2024 Cesium-134 9.96E-01 4.82E-01 1.72E+00 pCi/L Surface Water 669519004 5/28/2024 Cesium-137

-5.57E-01 6.94E-01 1.87E+00 pCi/L Surface Water 669519004 5/28/2024 Cobalt-58 9.93E-01 8.37E-01 1.33E+00 pCi/L Surface Water 669519004 5/28/2024 Cobalt-60 5.91E-01 4.89E-01 1.74E+00 pCi/L Surface Water 669519004 5/28/2024 lodine-131 3.33E-01 7.48E-01 2.56E+00 pCi/L Surface Water 669519004 5/28/2024 lron-59 7.40E-01 9.32E-01 3.27E+00 pCi/L Surface Water 669519004 5/28/2024 Lanthanum-140 6.72E-01 7.66E-01 2.67E+00 pCi/L Surface Water 669519004 5/28/2024 Manganese-54

-1.27E+00 4.70E-01 1.28E+00 pCi/L Surface Water 669519004 5/28/2024 Niobium-95

-4.31E-01 8.36E-01 1.65E+00 pCi/L

Annual Environmental Operating Report J YEAR: 2024 J

Pa_g_e 92 of 138 Company: Vistra Corp J Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 669519004 5/28/2024 Zinc-65

-2.12E-01 8.93E-01 2.97E+OO pCi/L Surface Water 669519004 5/28/2024 Zirconium-95

-7.85E-02 8.76E-01 2.81E+OO pCi/L Surface Water 673283004 6/25/2024 Barium-140 2.13E+OO 2.45E+OO 7.63E+OO pCi/L Surface Water 673283004 6/25/2024 Cesium-134 5.17E-01 4.83E-01 1.65E+OO pCi/L Surface Water 673283004 6/25/2024 Cesium-137 1.79E+OO 6.70E-01 1.35E+OO pCi/L Surface Water 673283004 6/25/2024 Cobalt-58

-5.99E-01 4.23E-01 1.24E+OO pCi/L Surface Water 673283004 6/25/2024 Cobalt-60 1.48E-01 5.0BE-01 1.72E+OO pCi/L Surface Water 673283004 6/25/2024 lodine-131

-2.26E+OO 1.14E+OO 2.69E+OO pCi/L Surface Water 673283004 6/25/2024 lron-59 4.23E-01 8.88E-01 3.08E+OO pCi/L Surface Water 673283004 6/25/2024 Lanthanum-140

-4.44E-01 8.23E-01 2.59E+OO pCi/L Surface Water 673283004 6/25/2024 Manganese-54

-1.06E+OO 6.67E-01 1.48E+OO pCi/L Surface Water 673283004 6/25/2024 Niobium-95 3.64E-01 4.66E-01 1.57E+OO pCi/L Surface Water 673283004 6/25/2024 Zinc-65

-1.20E-01 9.67E-01 3.24E+OO pCi/L Surface Water 673283004 6/25/2024 Zircon iu m-95 3.78E-01 7.88E-01 2.62E+OO pCi/L Surface Water 678790004 7/30/2024 Barium-140 4.56E+OO 2.42E+OO 8.53E+OO pCi/L Surface Water 678790004 7/30/2024 Cesium-134 8.96E-02 6.17E-01 2.11E+OO pCi/L Surface Water 678790004 7/30/2024 Cesium-137 1.03E+OO 6.75E-01 2.31E+OO pCi/L Surface Water 678790004 7/30/2024 Cobalt-58

-2.87E-02 5.79E-01 1.95E+OO pCi/L Surface Water 678790004 7/30/2024 Cobalt-SO

-2.36E-01 6.35E-01 2.00E+OO pCi/L Surface Water 678790004 7/30/2024 lodine-131

-7.47E-03 7.10E-01 2.39E+OO pCi/L Surface Water 678790004 7/30/2024 lron-59

-1.27E+OO 1.20E+OO 3.70E+OO pCi/L Surface Water 678790004 7/30/2024 Lanthanum-140 2.62E+OO 1.86E+OO 3.10E+OO pCi/L Surface Water 678790004 7/30/2024 Manganese-54

1.20E+OO 5.28E-01 1.56E+OO pCi/L Surface Water 678790004 7/30/2024 Niobium-95 1.77E+OO 5.92E-01 2.25E+OO pCi/L Surface Water 678790004 7/30/2024 Zinc-65

-1.78E-01 1.21E+OO 3.95E+OO pCi/L Surface Water 678790004 7/30/2024 Zirconium-95

-4.94E-01 1.03E+OO 3.44E+OO pCi/L Surface Water 683293004 8/27/2024 Barium-140

-3.04E+OO 4.16E+OO 1.03E+01 pCi/L Surface Water 683293004 8/27/2024 Cesium-134 5.59E-01 4.45E-01 1.50E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 93 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 683293004 8/27/2024 Cesium-137 8.84E-01 4.59E-01 1.11E+0O pCi/L Surface Water 683293004 8/27/2024 Cobalt-58

-2.14E-01 4.17E-01 1.31E+00 pCi/L Surface Water 683293004 8/27/2024 Cobalt-60

-5.00E-01 4.19E-01 1.31E+00 pCi/L Surface Water 683293004 8/27/2024 lodine-131 1.36E+00 1.46E+00 5.03E+00 pCi/L Surface Water 683293004 8/27/2024 lron-59 6.30E-02 8.53E-01 2.89E+00 pCi/L Surface Water 683293004 8/27/2024 Lanthanum-140

-5.65E-01 1.08E+00 3.42E+00 pCi/L Surface Water 683293004 8/27/2024 Manganese-54 2.59E-01 3.98E-01 1.31E+00 pCi/L Surface Water 683293004 8/27/2024 Niobium-95 6.95E-01 4.43E-01 1.51E+00 pCi/L Surface Water 683293004 8/27/2024 Zinc-65

-2.60E-01 7.42E-01 2.46E+00 pCi/L Suriace Water 683293004 8/27/2024 Zirconium-95 1.38E+00 7.51E-01 2.60E+00 pCi/L Surface Water 687543004 9/24/2024 Barium-140 1.56E-01 2.67E+00 8.85E+00 pCi/L Surface Water 687543004 9/24/2024 Cesium-134 4.69E-01 4.84E-01 1.64E+00 pCi/L Surface Water 687543004 9/24/2024 Cesium-137

-6.65E-01 4.52E-01 1.37E+00 pCi/L Surface Water 687543004 9/24/2024 Cobalt-58 1.SlE-01 4.91E-01 1.60E+00 pCi/L Surface Water 687543004 9/24/2024 Cobalt-60

-2.32E-01 4.52E-01 1.39E+00 pCi/L Surface Water 687543004 9/24/2024 lodine-131 1.30E+00 1.03E+00 3.64E+00 pCi/L Surface Water 687543004 9/24/2024 lron-59

-1.53E-01 9.02E-01 3.01E+00 pCi/L Surface Water 687543004 9/24/2024 Lanthanum-140

-1.69E+00 1.09E+00 2.58E+00 pCi/L Surface Water 687543004 9/24/2024 Manganese-54

-3.84E-01 4.84E-01 1.49E+00 pCi/L Surface Water 687543004 9/24/2024 Niobium-95 2.32E-01 5.03E-01 1.66E+00 pCi/L Surface Water 687543004 9/24/2024 Zinc-65

-1.66E-01 9.08E-01 3.02E+00 pCi/L Surface Water 687543004 9/24/2024 Zirconium-95 3.25E-01 8.06E-01 2.66E+00 pCi/L Surface Water 693015004 10/29/2024 Barium-140 1.32E+00 2.67E+00 9.10E+O0 pCi/L Surface Water 693015004 10/29/2024 Cesium-134 1.71E-01 4.36E-01 1.45E+00 pCi/L Surface Water 693015004 10/29/2024 Cesium-137 9.0lE-01 4.71E-01 1.70E+00 pCi/L Surface Water 693015004 10/29/2024 Cobalt-58 4.92E-01 4.81E-01 1.65E+00 pCi/L Surface Water 693015004 10/29/2024 Cobalt-60 6.45E-01 4.77E-01 1.75E+00 pCi/L Surface Water 693015004 10/29/2024 lodine-131

-2.21E-01 9.21E-01 3.11E+00 pCi/L

Annual Environmental Operating Report J

YEAR: 2024 J

Page 94 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 693015004 10/29/2024 lron-59 2.05E+00 8.01E-01 3.03E+00 pCi/L Surface Water 693015004 10/29/2024 Lanthanum-140

-5.10E-02 8.52E-01 2.79E+00 pCi/L Surface Water 693015004 10/29/2024 Manganese-54

-3.52E-02 4.76E-01 1.53E+00 pCi/L Surface Water 693015004 10/29/2024 Niobium-95 4.0lE-01 4.46E-01 1.53E+00 pCi/L Surface Water 693015004 10/29/2024 Zinc-65 4.26E-01 8.89E-01 3.11E+00 pCi/L Surface Water 693015004 10/29/2024 Zirconium-95

-3.74E-01 8.62E-01 2.73E+00 pCi/L Surface Water 698142004 11/26/2024 Barium-140

-2.68E+00 4.79E+00 1.23E+01 pCi/L Surface Water 698142004 11/26/2024 Cesium-134

-2.15E-01 7.0SE-01 2.22E+00 pCi/L Surface Water 698142004 11/26/2024 Cesium-137

-3.00E-01 6.38E-01 2.04E+00 pCi/L Surface Water 698142004 11/26/2024 Cobalt-58

-7.64E-01 6.24E-01 1.98E+00 pCi/L Surface Water 698142004 11/26/2024 Cobalt-60 3.S0E-01 9.65E-01 2.75E+00 pCi/L Surface Water 698142004 11/26/2024 lodine-131

-1.55E+00 1.46E+00 4.54E+00 pCi/L Surface Water 698142004 11/26/2024 Jron-59 3.59E+00 1.49E+00 5.48E+00 pCi/L Surface Water 698142004 11/26/2024 Lanthanum-140

-5.62E-01 1.50E+00 4.82E+00 pCi/L Surface Water 698142004 11/26/2024 Manganese-54

-1.04E-01 6.42E-01 2.15E+00 pCi/L Surface Water 698142004 11/26/2024 Niobium-95

-3.03E+00 1.18E+00 2.15E+0O pCi/L Surface Water 698142004 11/26/2024 Zinc-65

-2.66E-01 1.33E+00 4.30E+00 pCi/L Surface Water 698142004 11/26/2024 Zirconium-95 3.46E-01 1.27E+00 4.15E+00 pCi/L Surface Water 703333004 12/31/2024 Barium-140 5.36E-01 3.33E+00 1.11E+0l pCi/L Surtace Water 703333004 12/31/2024 Cesium-134 8.28E-01 6.0lE-01 1.87E+00 pCi/L Surface Water 703333004 12/31/2024 Cesium-137 5.29E-01 5.07E-01 1.72E+00 pCi/L Surface Water 703333004 12/31/2024 Cobalt-58 2.33E-01 5.25E-01 1.73E+00 pCi/L Surface Water 703333004 12/31/2024 Cobalt-60

-7.55E-01 9.66E-01 2.05E+0O pCi/L Surface Water 703333004 12/31/2024 lodine-131 1.24E+00 1.77E+00 5.52E+00 pCi/L Surtace Water 703333004 12/31/2024 lron-59

-2.83E-01 1~10E+00 3.69E+00 pCi/L Surface Water 703333004 12/31/2024 Lanthanum-140 9.88E-01 1.17E+00 3.65E+00 pCi/L Surface Water 703333004 12/31/2024 Manganese-54 1.08E+00 4.78E-01 1.70E+00 pCi/L Surface Water 703333004 12/31/2024

Niobium-95

-4.62E-03 5.90E-01 1.91E+00 pCi/L

Annual Environmental Operating Report J

YEAR: 2024 J

Page 95 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-3 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 703333004 12/31/2024 Zinc-65 1.47E-01 1.23E+00 3.70E+00 pCi/L Surface Water 703333004 12/31/2024 Zirconiurn-95 1.70E+00 9.92E-01 3.44E+00 pCi/L SW-3 Quarterly Composite Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 665489004 3/26/2024 Tritium

-1.22E+02 2.22E+02 7.47E+02 pCi/L Surface Water 678504004 6/25/2024 Tritium

-2.00E+02 2.32E+02 8.03E+02 pCi/L surtace Water 692597004 9/24/2024 Tritium 1.54E+02 2.36E+02 7.48E+02 pCi/L Surface Water 707025004 12/31/2024 Tritium 1.93E+02 1.68E+02 5.40E+02 pCi/L SW-4 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 653744003 1/30/2024 Barium-140 4.95E+00 2.43E+00 8.51E+00 pCi/L Surface Water 653744003 1/30/2024 Cesium-134

-5.87E-01 7.04E-01 1.68E+00 pCi/L Surface Water 653744003 1/30/2024 Cesium-137 6.23E-01 5.09E-01 1.72E+00 pCi/L Surface Water 653744003 1/30/2024 Cobalt-58 1.14E-01 5.00E-01 1.71E+00 pCi/L Surface Water 653744003 1/30/2024 Cobalt-60

-2.90E-01 5.61E-01 1.77E+00 pCi/L Surface Water 653744003 1/30/2024 lodine-131 1.38E-01 8.83E-01 2.95E+00 pCi/L Surface Water 653744003 1/30/2024 lron-59

-5.49E-01 9.46E-01 3.03E+00 pCi/L Surface Water 653744003 1/30/2024 Lanthanum-140

-1.51E-01 9.45E-01 3.00E+00 pCi/L Surface Water 653744003 1/30/2024 Manganese-54 2.72E-01 4.25E-01 1.48E+00 pCi/L Surface Water 653744003 1/30/2024 Niobium-95

-2.04E-01 5.08E-01 1.70E+0O pCi/L Surface Water 653744003 1/30/2024 Zinc-65

-1.14E-01 1.03E+00 3.39E+0O pCi/L Surface Water 653744003 1/30/2024 Zirconium-95 1.05E+00 8.23E-01 2.94E+OO pCi/L Surface Water 657026003 2/27/2024 Bariurn-140 1.46E+O0 2.62E+00 8.68E+0O pCi/L Surface Water 657026003 2/27/2024 Cesium-134

-3.63E-01 5.16E-01 1.70E+00 pCi/L Surface Water 657026003 2/27/2024 Cesium-137 8.39E-01 5.53E-01 1.80E+00 pCi/L Surtace Water 657026003 2/27/2024 Cobalt-58

-2.20E-01 4.95E-01 1.64E+00 p'Ci/L

Annual Environmental Operating Report J YEAR: 2024 I Page 96 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-4 Monthly Composite Gamma S.2_ectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 657026003 2/27/2024 Cobalt-SO

-1.38E-01 5.25E-01 1.68E+OO pCi/L Surface Water 657026003 2/27/2024 lodine-131 5.35E-01 8.49E-01 2.88E+OO pCi/L Surface Water 657026003 2/27/2024 lron-59 7.58E-02 1.01E+OO 3.36E+OO pCi/L Surface Water 657026003 2/27/2024 Lanthanum-140

-1.62E+OO 1.15E+OO 2.82E+OO pCi/L Surface Water 657026003 2/27/2024 Manganese-54 7.SOE-01 5.02E-01 1.79E+OO pCi/L Surface Water 657026003 2/27/2024 Niobium-95

-5.87E-01 4.62E-01 1.49E+OO pCi/L Surface Water 657026003 2/27/2024 Zinc-65

-1.81E+OO 1.08E+OO 2.68E+OO pCi/L Surface Water 657026003 2/27/2024 Zirconium-95 6.39E-01 8.28E-01 2.90E+OO pCi/L Surface Water 660511003 3/26/2024 Bari.um-140

-4.70E-01 3.15E+OO 1.04E+01 pCi/L Surface Water 660511003 3/26/2024 Cesium-134 2.76E-01 7.46E-01 2.47E+OO pCi/L Surface Water 660511003 3/26/2024 Cesium-137 2.94E-01 6.82E-01 2.29E+OO pCi/L Surface Water 660511003 3/26/2024 Cobalt-58 1.21E+OO 5.38E-01 2.03E+OO pCi/L Surface Water 660511003 3/26/2024 Cobalt-60 5.88E-01 2.08E+OO 3.42E+OO pCi/L Surface Water 660511003 3/26/2024 lodine-131 1.27E+OO 1.11E+OO 3.93E+OO pCi/L Surface Water 660511003 3/26/2024 lron-59

-3.24E-01 1.36E+OO 4.54E+OO pCi/L Surface Water 660511003 3/26/2024 Lanthanum-140

-1.30E-01 9.91E-01 3.21E+OO pCi/L Surface Water 660511003 3/26/2024 Manganese-54

-4.22E-01 7.03E-01 2.17E+OO pCi/L Surface Water 660511003 3/26/2024 Niobium-95

-1.97E-01 6.80E-01 2.16E+OO pCi/L Surface Water 660511003 3/26/2024 Zinc-65 2.57E+OO 1.65E+OO 5.58E+OO pCi/L Surface Water 660511003 3/26/2024 Zirconium-95 5.93E-01 1.29E+OO 4.28E+OO pCi/L Surface Water 665744003 4/30/2024 Barium-140 2.38E-01 2.52E+OO 8.24E+OO pCi/L Surface Water 665744003 4/30/2024 Cesium-134 4.37E-01 6.40E-01 2.22E+OO pCi/L Surface Water 665744003 4/30/2024 Cesium-137

-1.25E+OO 9.72E-01 1.95E+OO pCi/L Surface Water 665744003 4/30/2024 Cobalt-58 5.11E-02 5.38E-01 1.82E+OO pCi/L Surface Water 665744003 4/30/2024 Cobalt-SO 1.67E-01 6.82E-01 2.22E+OO pCi/L Surface Water 665744003 4/30/2024 lodine-131

-1.02E+OO 1.48E+OO 2.68E+OO pCi/L Surface Water 665744003 4/30/2024 lron-59

-2.90E-01 1.24E+OO 3.50E+OO pCi/L Surface Water 665744003 4/30/2024

. Lanthanum-140

-1.29E+OO 9.11E-01 2.79E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 97 of 138 Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant SW-4 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 665744003 4/30/2024 Manganese-54 1.17E+O0 5.37E-01 1.96E+0O pCi/L Surface Water 665744003 4/30/2024 Niobium-95

-3.26E-02 6.12E-01 2.07E+0O pCi/L Surface Water 665744003 4/30/2024 Zinc-65

-1.80E-01 1.34E+00 3.79E+00 pCi/L Surface Water 665744003 4/30/2024 Zircon iu m-95

-6.72E-02 9.72E-01 3.29E+00 pCi/L Surface Water 669519003 5/28/2024 Barium-140 2.37E-02 2.33E+00 7.68E+00 pCi/L Surface Water 669519003 5/28/2024 Cesium-134

-2.06E-01 5.11E-01 1.60E+0O pCi/L Surface Water 669519003 5/28/2024 Cesium-137 4.74E-01 4.71E-01 1.60E+00 pCi/L Surface Water 669519003 5/28/2024 Cobalt-58

-7.73E-01 4.76E-01 1.39E+00 pCi/L Surface Water 669519003 5/28/2024 Cobalt-60 1.16E+00 4.77E-01 1.81E+00 pCi/L Surface Water 669519003 5/28/2024 lodine-131 8.95E-01 7.97E-01 2.78E+00 pCi/L Surface Water 669519003 5/28/2024 lron-59 1.29E+00 1.40E+00 3.41E+00 pCi/L Surface Water 669519003 5/28/2024 Lanthanum-140

-4.18E-01 7.45E-01 2.24E+00 pCi/L Surface Water 669519003 5/28/2024 Manganese-54

-8.65E-02 4.81E-01 1.52E+00 pCi/L Surface Water 669519003 5/28/2024 Niobium-95

-4.38E-01 7.17E-01 1.75E+00 pCi/L Surface Water 669519003 5/28/2024 Zinc-65

-2.32E+00 1.43E+00 3.12E+00 pCi/L Surface Water 669519003 5/28/2024 Zirconium-95 6.31E-01 8.60E-01 2.87E+00 pCi/L Surface Water 673283003 6/25/2024 Barium-140

-2.39E+00 2.21E+00 6.95E+00 pCi/L Surface Water 673283003 6/25/2024 Ccsium-134

-1.12E+00 7.89E-01 1.69E+00 pCi/L Surface Water 673283003 6/25/2024 Cesium-137 3.39E-01 4.93E-01 1.65E+00 pCi/L Surface Water 673283003 6/25/2024 Cobalt-58

-4.17E-01 4.82E-01 1.47E+00 pCi/L Surface Water 673283003 6/25/2024 Cobalt-60

-4.20E-02 4.90E-01 1.62E+00 pCi/L Surface Water 673283003 6/25/2024 lodine-131 1.80E-01 7.74E-01 2.63E+00 pCi/L Surface Water 673283003 6/25/2024 lron-59 1.16E+00 9.74E-01 3.46E+00 pCi/L Surface Water 673283003 6/25/2024 Lanthanum-140 8.34E-01 8.61E-01 2.98E+00 pCi/L Surface Water 673283003 6/25/2024 Manganese-54 4.62E-01 5.14E-01 1.71E+00 pCi/L Surtace Water 673283003 6/25/2024 Niobium-95 8.32E-01 5.25E-01 1.66E+00 pCi/L Surface Water 673283003 6/25/2024 Zinc-65

-8.63E-01 8.76E-01 2.77E+OO pCi/L Surface Water 673283003 6/25/2024 Zirconium-95 8.84E-01 9.67E-01 2.30E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 98 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-4 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 678790003 7/30/2024 Barium-140 1.53E+OO 2.17E+OO 6.73E+OO pCi/L Surface Water 678790003 7/30/2024 Cesium-134 2.39E-01 5.21E-01 1.73E+OO pCi/L Surface Water 678790003 7/30/2024 Cesium-137 1.75E-01 5.llE-01 1.70E+OO pCi/L Surface Water 678790003 7/30/2024 Cobalt-58 1.38E-01 4.73E-01 1.56E+OO pCi/L Surface Water 678790003 7/30/2024 Cobalt-60 1.92E-01 4.85E-01 1.67E+OO pCi/L Surface Water 678790003 7/30/2024 lodine-131

-1.63E+OO 1.06E+OO 2.09E+OO pCi/L Surface Water 678790003 7/30/2024 lron-59

-2.66E+OO 1.04E+OO 3.03E+OO pCi/L Surface Water 678790003 7/30/2024 Lanthanum-140 1.08E+OO 7.37E-01 2.68E+OO pCi/L Surface Water 678790003 7/30/2024 Manganese-54 2.00E-01 4.76E-01 1.57E+OO pCi/L Surface Water 678790003 7/30/2024 Niobium-95

-3.90E-01 5.46E-01 1.71E+OO pCi/L Surface Water 678790003 7/30/2024 Zinc-65

-4.04E-03 8.75E-01 2.97E+OO pCi/L Surface Water 678790003 7/30/2024 Zirconium-95

-1.15E-01 8.41E-01 2.71E+OO pCi/L Surface Water 683293003 8/27/2024 Barium-140 4.51E+OO 3.34E+OO 9.94E+OO pCi/L Surtace Water 683293003 8/27/2024 Cesium-134 6.43E-01 4.55E-01 1.41E+OO pCi/L Surface Water 683293003 8/27/2024 Cesium-137 6.36E-01 4.02E-01 1.39E+OO pCi/L Surface Water 683293003 8/27/2024 Cobalt-58 3.27E+OO 9.62E-01 1.29E+OO pCi/L Surface Water 683293003 8/27/2024 Cobalt-GO 5.17E-02 4.52E-01 1.33E+OO pCi/L Surface Water 683293003 8/27/2024 lodine-131

-5.33E-01 1.39E+OO 4.68E+OO pCi/L Surface Water 683293003 8/27/2024 lron-59

-1.68E-01 1.38E+OO 2.95E+OO pCi/L Surface Water 683293003 8/27/2024 Lanthanum-140

-1.89E-01 1.04E+OO 2.91E+OO pCi/L Surface Water 683293003 8/27/2024 Manganese-54 4.50E-01 3.74E-01 1.26E+OO pCi/L Surface Water 683293003 8/27/2024 Niobium-95 5.75E-01 4.08E-01 1.40E+OO pCi/L Surface Water 683293003 8/27/2024 Zinc-65

-5.78E-01 1.06E+OO 2.52E+OO pCi/L Surface Water 683293003 8/27/2024 Zirconium-95 3.33E-01 7.86E-01 2.58E+OO pCi/L Surface Water 687543003 9/24/2024 Barium-140

-8.71E-01 2.68E+OO 8.60E+OO pCi/L Surface Water 687543003 9/24/2024 Cesium-134 9.98E-01 5.26E-01 1.91E+OO pCi/L Surtace Water 687543003 9/24/2024 Cesium-137 7.SOE-01 5.42E-01 1.83E+OO pCi/L Surface Water 687543003 9/24/2024 Cobalt-58

-5.SOE-01 4.61E-01 1.47E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Pa_g_e 99 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-4 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 687543003 9/24/2024 Cobalt-SO 3.98E-01 5.53E-Ol 1.87E+OO pCi/L Surface Water 687543003 9/24/2024 lodine-131 1.30E+OO 1.10E+OO 3.79E+OO pCi/L Surface Water 687543003 9/24/2024 lron-59

-7.44E-01 1.07E+OO 3.39E+OO pCi/L Surface Water 687543003 9/24/2024 Lanthanum-140

-9.17E-01 1.02E+OO 3.27E+OO pCi/L Surface Water 687543003 9/24/2024 Manganese-54

-6.96E-01 5.27E-01 1.44E+OO pCi/L Surface Water 687543003 9/24/2024 Niobium-95

-6.70E-01 7.84E-01 1.84E+OO pCi/L Surface Water 687543003 9/24/2024 Zinc-65 3.12E-01 1.11E+OO 3.71E+OO pCi/L Surface Water 687543003 9/24/2024 Zirconium-95

-4.61E-01 8.22E-01 2.72E+OO pCi/L Surface Water 693015003 10/29/2024 Barium-140

-1.38E+OO 2.44E+OO 7.92E+OO pCi/L Surface Water 693015003 10/29/2024 Cesium-134

-2.20E-01 4.98E-01 1.57E+OO pCi/L Surface Water 693015003 10/29/2024 Cesium-137

-3.73E-03 4.55E-01 1.49E+OO pCi/L Surface Water 693015003 10/29/2024 Cobalt-58 2.21E+OO 8.49E-01 1.37E+OO pCi/L Surface Water 693015003 10/29/2024 Cobalt-60

-5.61E-01 5.02E-01 1.55E+OO pCi/L Surface Water 693015003 10/29/2024 lodine-131 3.69E-01 1.03E+OO 3.39E+OO pCi/L Surface Water 693015003 10/29/2024 lron-59 4.84E-01 8.75E-01 3.05E+OO pCi/L Surface Water 693015003 10/29/2024 Lanthanum-140

-1.84E+OO 9.35E-01 2.60E+OO pCi/L Surface Water 693015003 10/29/2024 Manganese-54

-4.0lE-01 4.69E-01 1.44E+OO pCi/L Surface Water 693015003 10/29/2024 Niobium-95

-6.29E-01 9.48E-01 1.70E+OO pCi/L Suliace Water 693015003 10/29/2024 Zinc-65

-1.79E+OO 1.00E+OO 3.05E+OO pCi/L Surface Water 693015003 10/29/2024 Zirconium-95

-2.20E-01 8.SOE-01 2.72E+OO pCi/L Surface Water 698142003 11/26/2024 Barium-140 2.00E+OO 8.76E+OO 1.14E+01 pCi/L Surface Water 698142003 11/26/2024 Cesium-134 7.19E-01 7.54E-01 2.54E+OO pCi/L Surface Water 698142003 11/26/2024 Cesium-137

-3.96E-01 6.67E-01 2.lOE+OO pCi/L Suliace Water 698142003 11/26/2024 Cobalt-58 6.78E-01 6.84E-01 2.31E+OO pCi/L Surface Water 698142003 11/26/2024 Cobalt-60 6.63E-02 6.34E-01 2.10E+OO pCi/L Surface Water 698142003 11/26/2024 lodine-131 6.99E-02 1.16E+OO 3.97E+OO pCi/L Surface Water 698142003 11/26/2024 lron-59

-1.25E+OO 1.30E+OO 4.08E+OO pCi/L Surface Water 698142003 11/26/2024 Lanthanum-140

-1.78E+OO 1.43E+OO 4.14E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 100 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-4 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 698142003 11/26/2024 Manganese-54 3.24E-01 6.64E-01 2.17E+00 pCi/L Surface Water 698142003 11/26/2024 Niobium-95

-9.lOE-01 1.10E+00 2.23E+00 pCi/L Surface Water 698142003 11/26/2024 Zinc-65

-2.56E-02 l.37E+00 4.55E+00 pCi/L Surface Water 698142003 11/26/2024 Zirconium-95 1.63E+00 1.31E+00 4.47E+00 pCi/L Surface Water 703333003 12/31/2024 Barium-140

-8.86E-01 3.39E+0O 1.14E+01 pCi/L Surface Water 703333003 12/31/2024 Cesium-134

-2.51E-01 5.31E-01 1.74E+00 pCi/L Surface Water 703333003 12/31/2024 Cesium-137

-2.18E-01 5.15E-01 1.71E+00 pCi/L Surface Water 703333003 12/31/2024 Cobalt-58 3.99E-01 6.22E-01 1.76E+00 pCi/L Surface Water 703333003 12/31/2024 Cobalt-60

-3.06E-01 6.51E-01 1.78E+00 pCi/L Surface Water 703333003 12/31/2024 lodine-131 4.87E+00 2.27E+00 4.16E+00 pCi/L Surface Water 703333003 12/31/2024 lron-59

-7.44E-01 1.12E+00 3.59E+00 pCi/L Surface Water 703333003 12/31/2024 Lanthanum-140 2.66E+00 1.29E+00 3.82E+00 pCi/L Surtace Water 703333003 12/31/2024 Manganese-54

-4.86E-01 4.71E-01 1.51E+00 pCi/L Surface Water 703333003 12/31/2024 Niobium-95

-4.02E-01 9.64E-01 1.98E+00 pCi/L Surface Water 703333003 12/31/2024 Zinc-65

-1.46E+O0 1.07E+0O 3.32E+00 pCi/L Surtace Water 703333003 12/31/2024 Zirconium-95 2.17E+00 1.09E+00 3.46E+00 pCi/L SW-4 Quarterly Composite Tritium Sample Type Lab JD Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 665489003 3/26/2024 Tritium 6.50E+00 2.28E+02 7.51E+02 pCi/L Surface Water 678504003 6/25/2024 Tritium

-2.45E+02 2.18E+02 7.65E+02 pCi/L Surface Water 692597003 9/24/2024 Tritium 4.27E+02 2.34E+02 6.94E+02 pCi/L Surface Water 707025003 12/31/2024 Tritium 3.34E+02 1.72E+02 5.42E+02 pCi/L SW-5 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 653744001 1/30/2024 Barium-140

-3.77E-01 3.18E+00 1.05E+01 pCi/L Surface Water 653744001 1/30/2024 Cesium-134 1.26E+00 6.39E-01 2.28E+00 pCi/L Surtace Water 653744001 1/30/2024

Cesium-137 6.71E-01 6.33E-01 2.17E+00 pCi/L

Annual Environmental Operating Report J YEAR: 2024 I Page 101 of 138 Company: Vistra Corp

] Comanche Peak Nuclear Power Plant SW-5 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 653744001 1/30/2024 Cobalt-58

-5.47E-01 6.70E-01 1.95E+00 pCi/L Surface Water 653744001 1/30/2024 Cobalt-60

-1.01E+00 1.08E+00 2.85E+00 pCi/L Surface Water 653744001 1/30/2024 lodine-131 1.26E+00 1.19E+00 4.17E+00 pCi/L Surface Water 653744001 1/30/2024 lron-59 1.22E-01 1.31E+00 4.44E+00 pCi/L Surtace Water 653744001 1/30/2024 Lanthanum-140

-1.36E+00 1.15E+00 3.45E+00 pCi/L Surface Water 653744001 1/30/2024 Manganese-54 1.65E+0O 1.06E+00 1.77E+O0 pCi/L Surface Water 653744001 1/30/2024 Niobium-95 4.71E-02 5.93E-01 1.93E+00 pCi/L Surface Water 653744001 1/30/2024 Zinc-65 1.73E+00 1.29E+00 4.65E+00 pCi/L Surtace Water 653744001 1/30/2024 Zirconium-95

-1.13E+00 1.l0E+00 3.36E+O0 pCi/L Surface Water 657026001 2/27/2024 Barium-140

-5.44E+00 4.0SE+00 9.29E+00 pCi/L Surface Water 657026001 2/27/2024 Cesium-134 3.74E-02 6.43E-0l 2.09E+00 pCi/L Surface Water 657026001 2/27/2024 Cesium-137

-3.14E-01 5.77E-01 1.85E+00 pCi/L Surface Water 657026001 2/27/2024 Cobalt-58

-6.57E-01 6.20E-01 1.91E+00 pCi/L Surface Water 657026001 2/27/2024 Cobalt-60

-4.86E-01 5.44E-01 1.72E+00 pCi/L Surface Water 657026001 2/27/2024 lodine-131 4.80E-01 1.03E+0O 3.56E+00 pCi/L Surface Water 657026001 2/27/2024 lron-59 7.27E-01 9.93E-01 3.50E+00 pCi/L Surface Water 657026001 2/27/2024 Lanthanum-140

-2.45E-01 9.70E-01 2.73E+00 pCi/L Surface Water 657026001 2/27/2024 Manganese-54

-1.36E+00 6.56E-01 1.63E+00 pCi/L Surface Water 657026001 2/27/2024 Niobium-95

-2.13E-01 6.45E-01 1.83E+00 pCi/L Surface Water 657026001 2/27/2024 Zinc-65

-1.97E-01 1.04E+00 3.49E+00 pCi/L Surface Water 657026001 2/27/2024 Zirconium-95

-9.39E-01 9.47E-01 2.93E+00 pCi/L Surface Water 660511001 3/26/2024 Barium-140

-3.63E+00 2.67E+0O 8.27E+00 pCi/L Surface Water 660511001 3/26/2024 Cesium-134

-4.66E-01 6.37E-01 1.96E+00 pCi/L Surface Water 660511001 3/26/2024 Cesium-137

-1.26E-01 9.0lE-01 2.24E+00 pCi/L Surface Water 660511001 3/26/2024 Cobalt-58

-6.45E-03 6.02E-01 1.93E+00 pCi/L Surface Water 660511001 3/26/2024 Cobalt-60 1.05E+00 5.91E-01 2.04E+0O pCi/L Surface Water 660511001 3/26/2024 lodine-131

-5.18E-03 8.80E-01 2.96E+0O pCi/L Surface Water 660511001 3/26/2024 lron-59 1.04E-01 1.11E+00 3.78E+0O pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 102 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-5 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 660511001 3/26/2024 Lanthanum-140 5.79E-01 8.53E-01 2.66E+0O pCi/L Surface Water 660511001 3/26/2024 Manganese-54

-5.l0E-01 5.77E-01 1.75E+0O pCi/L Surface Water 660511001 3/26/2024 Niobium-95

-1.48E-01 6.03E-01 1.92E+0O pCi/L Surface Water 660511001 3/26/2024 Zinc-65 4.80E-01 1.23E+00 3.78E+0O pCi/L Surface Water 660511001 3/26/2024 Zirconium-95 8.28E-01 1.02E+00 3.42E+0O pCi/L Surface Water 665744001 4/30/2024 Barium-140

-1.30E+00 1.89E+00 6.05E+OO pCi/L Surface Water 665744001 4/30/2024 Cesium-134

-2.23E-01 4.95E-01 1.55E+OO pCi/L Surface Water 665744001 4/30/2024 Cesium-137

-2.26E-01 5.27E-01 1.68E+0O pCi/l Surface Water 665744001 4/30/2024 Cobalt-58

-5.l0E-01 4.70E-01 1.42E+0O pCi/L Surface Water 665744001 4/30/2024 Cobalt-60

-3.17E-01 4.75E-01 1.52E+0O pCi/L Surface Water 665744001 4/30/2024 lodine-131

-1.70E-02 6.03E-01 2.03E+00 pCi/L Surface Water 665744001 4/30/2024 lron°59 3.0lE-02 8.98E-0l 3.05E+00 pCi/L Surface Water 665744001 4/30/2024 Lanthanum-140 7.47E-01 7.43E-01 2.38E+00 pCi/L Surface Water 665744001 4/30/2024 Manganese-54 9.0SE-01 7.76E-01 1.68E+00 pCi/L Surface Water 665744001 4/30/2024 Niobium-95 3.99E-01 4.42E-01 1.50E+00 pCi/L Surface Water 665744001 4/30/2024 Zinc-65

-1.30E+00 9.52E-01 2.96E+00 pCi/L Surface Water 665744001 4/30/2024 Zirconium-95 1.98E+00 l.84E+00 2.71E+00 pCi/L Surface Water 669519001 5/28/2024 Barium-140

-3.69E+00 3.03E+00 9.43E+00 pCi/L Surface Water 669519001 5/28/2024 Cesium-134 4.35E-01 1.17E+00 2.31E+00 pCi/L Surface Water 669519001 5/28/2024 Cesium-137 8.03E-01 6.32E-01 2.13E+00 pCi/L Surface Water 669519001 5/28/2024 Cobalt-58 2.42E-01 6.05E-01 2.07E+00 pCi/L Surface Water 669519001 5/28/2024 Cobalt-60

-1.l0E-03 6.58E-01 2.llE+00 pCi/L Surface Water 669519001 5/28/2024 lodine-131 4.86E-02 1.03E+00 3.46E+00 pCi/L Surface Water 669519001 5/28/2024 lron-59 1.50E+00 1.16E+00 4.04E+00 pCi/L Surface Water 669519001 5/28/2024 Lanthanum-140

-1.47E+00 1.19E+00 3.08E+00 pCi/L Surface Water 669519001 5/28/2024 Manganese-54

-7.79E-01 5.43E-01 1.71E+00 pCi/L Surface Water 669519001 5/28/2024 Niobium-95

-3.26E-01 5.56E-01 1.84E+00 pCi/L Surface Water 669519001 5/28/2024 Zinc-65

-8.41E=-01 1.32E+00 3.59E+O0 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 103 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-5 Monthly Composite Gamma S_2_ectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 669519001 5/28/2024 Zirconium-95 1.63E+00 1;09E+00 3.89E+00 pCi/L Surface Water 673283001 6/25/2024 Barium-140 3.09E+00 2.87E+00 9.91E+00 pCi/L Surface Water 673283001 6/25/2024 Cesium-134 9.11E-01 6.13E-01 2.12E+00 pCi/L Surface Water 673283001 6/25/2024 Cesium-137 3.21E-01 5.83E-01 1.96E+00 pCi/L Surface Water 673283001 6/25/2024 Cobalt-58

-2.06E-01 5.51E-01 1.75E+00 pCi/L Surface Water 673283001 6/25/2024 Cobalt-60

-5.22E-02 4.78E-01 1.59E+00 pCi/L Surface Water 673283001 6/25/2024 lodine-131 7.56E-01 9.70E-01 3.38E+00 pCi/L Surface Water 673283001 6/25/2024 lron-59

-8.36E-01 1.00E+00 3.26E+00 pCi/L Surface Water 673283001 6/25/2024 Lanthanum-140

-9.60E-01 8.96E-01 2.73E+00 pCi/L Surface Water 673283001 6/25/2024 Manganese-54

-1.41E-01 5.06E-01 1.61E+00 pCi/L Surface Water 673283001 6/25/2024 Niobium-95

-4.57E-01 5.94E-01 1.86E+00 pCi/L Surface Water 673283001 6/25/2024 Zinc-65

-4.28E-01 8.81E-01 2.90E+00 pCi/L Surface Water 673283001 6/25/2024 Zirconium-95 9.37E-01 1.02E+00 3.46E+00 pCi/L Surface Water 678790001 7/30/2024 Barium-140 1.22E+00 1.93E+00 6.56E+00 pCi/L Surface Water 678790001 7/30/2024 Cesium-134

-8.87E-02 5.07E-01 1.62E+00 pCi/L Surface Water 678790001 7/30/2024 Cesium-137 1.55E-01 4.32E-01 1.44E+00 pCi/L Surface Water 678790001 7/30/2024 Cobalt-58

-7.54E-01 4.14E-01 1.19E+00 pCi/L Surface Water 678790001 7/30/2024 Cobalt-60

-4.13E-01 4.25E-01 1.31E+00 pCi/L Surface Water 678790001 7/30/2024 lodine-131 1.12E+00 5.89E-01 2.12E+00 pCi/L Surface Water 678790001 7/30/2024 lron-59

-6.14E-01 8.42E-01 2.73E+00 pCi/L Surface Water 678790001 7/30/2024 Lanthanum-140 5.60E-01 5.83E-01 2.06E+00 pCi/L Surface Water 678790001 7/30/2024 Manganese-54

-5.47E-01 5.12E-01 1.35E+00 pCi/L Surtace Water 678790001 7/30/2024 Niobium-95 5.32E-01 4.96E-01 1.53E+00 pCi/L Surface Water 678790001 7/30/2024 Zinc-65

-5.28E-02 9.63E-01 2.85E+00 pCi/L Surface Water 678790001 7/30/2024 Zirconium-95

-5.81E-01 7.61E-01 2.36E+00 pCi/L Surface Water 683293001 8/27/2024 Barium-140 2.81E+00 4.14E+00 1.38E+01 pCi/L Surface Water 683293001 8/27/2024 Cesium-134

-1.18E+00 7.48E-01 1.88E+00 pCi/L Suliace Water 683293001 8/27/2024 Cesium-137

-5.48E-01 5.23E-01 1.61E+0O pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 104 of 138 Compa'!Y_:_ Vistra Corp Comanche Peak Nuclear Power Plant SW-5 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 683293001 8/27/2024 Cobalt-58 1.26E+OO 5.30E-01 1.92E+OO pCi/L Surface Water 683293001 8/27/2024 Cobalt-60

-2.78E-01 5.28E-01 1.65E+OO pCi/L Surface Water 683293001 8/27/2024 lodine-131 3.58E-01 2.00E+OO 6.75E+OO pCi/L Surface Water 683293001 8/27/2024 lron-59 5.39E-01 1.20E+OO 4.0lE+OO pCi/L Surface Water 683293001 8/27/2024 Lanthanum-140

-2.91E+OO 1.42E+OO 4.27E+OO pCi/L Surface Water 683293001 8/27/2024 Manganese-54

-2.79E-01 4.93E-01 1.63E+OO pCi/L Surface Water 683293001 8/27/2024 Niobium-95 7.69E-02 5.58E-01 1.90E+OO pCi/L Surface Water 683293001 8/27/2024 Zinc-65

-6.26E-01 1.23E+OO 3.42E+OO pCi/L Surface Water 683293001 8/27/2024 Zirconium-95 7.36E-01 9.77E-01 3.39E+OO pCi/L Surface Water 687543001 9/24/2024 Barium-140

-4.07E+OO 4.73E+OO 1.07E+01 pCi/L Surface Water 687543001 9/24/2024 Cesium-134 5.21E-02 8.37E-01 2.39E+OO pCi/L Surface Water 687543001 9/24/2024 Cesium-137

-8.06E~02 6.62E-01 2.14E+OO pCi/L Surface Water 687543001 9/24/2024 Cobalt-58

-4.00E-01 7.18E-01 2.22E+OO pCi/L Surface Water 687543001 9/24/2024 Cobalt-SO

-2.87E-01 7.39E-01 2.36E+OO pCi/L Surface Water 687543001 9/24/2024 lodine-131

-4.25E-01 1.25E+OO 4.20E+OO pCi/L Surface Water 687543001 9/24/2024 lron-59

-1.38E+OO 1.32E+OO 4.lOE+OO pCi/L Surface Water 687543001 9/24/2024 Lanthanum-140

-1.25E+OO 1.37E+OO 4.08E+OO pCi/L Surface Water 687543001 9/24/2024 Manganese-54 4.57E-01 7.20E-01 2.37E+OO pCi/L Surface Water 687543001 9/24/2024 Niobium-95

-8.50E-01 6.78E-01 2.0lE+OO pCi/L Surface Water 687543001 9/24/2024 Zinc-65

-4.91E-02 1.43E+OO 4.75E+OO pCi/L Surface Water 687543001 9/24/2024 Zirconium-95 1.77E+OO 1.26E+OO 4.35E+OO pCi/L Surface Water 693015001 10/29/2024 Barium-140

-1.94E+OO 2.56E+OO 8.08E+OO pCi/L Surface Water 693015001 10/29/2024 Cesium-134 5.lOE-01 4.92E-01 1.65E+OO pCi/L Surface Water 693015001 10/29/2024 Cesium-137 6.27E-01 5.23E-01 1.77E+OO pCi/L Surface Water 693015001 10/29/2024 Cobalt-58

-4.34E-01 4.52E-01 1.35E+OO pCi/L Surface Water 693015001 10/29/2024 Cobalt-60 2.25E-01 4.57E-01 1.55E+OO pCi/L Surface Water 693015001 10/29/2024 lodine-131

-5.22E-01 1.02E+OO 3.34E+OO pCi/L Surface Water 693015001 10/29/2024 lron-59 2.35E+OO 2.60E+OO 2.90E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 105 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-5 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 693015001 10/29/2024 Lanthanum-140 1.86E+OO 9.86E-01 3.59E+OO pCi/L Surface Water 693015001 10/29/2024 Manganese-54

-1.91E-01 4.61E-01 1.54E+OO pCi/L Surface Water 693015001 10/29/2024 Niobium-95

-2.56E-01 5.04E-01 1.56E+OO pCi/L Surface Water 693015001 10/29/2024 Zinc-65 2.72E+OO 9.54E-01 3.45E+OO pCi/L Surface Water 693015001 10/29/2024 Zirconium-95

-1.51E-01 8.71E-01 2.75E+OO pCi/L Surface Water 698142001 11/26/2024 Barium-140 3.57E+OO 3.52E+OO 1.23E+01 pCi/L Surface Water 698142001 11/26/2024 Cesium-134 3.66E-01 7.03E-01 2.35E+OO pCi/L Surface Water 698142001 11/26/2024 Cesium-137 1.52E+OO 9.68E-01 2.04E+OO pCi/L Surface Water 698142001 11/26/2024.

Cobalt-58 6.63E-01 6.lOE-01 2.10E+OO pCi/L Surface Water 698142001 11/26/2024 Cobalt-SO 9.34E-02 6.27E-01 2.12E+OO pCi/L Surface Water 698142001 11/26/2024 lodine-131

-6.66E-01 1.30E+OO 4.38E+OO pCi/L Surface Water 698142001 11/26/2024 lron-59 5.71E-01 1.44E+OO 4.45E+OO pCi/L Surface Water 698142001 11/26/2024 Lanthanum-140

-5.87E-01 1.28E+OO 4.08E+OO pCi/L Surtace Water 698142001 11/26/2024 Manganese-54

-3.59E-01 6.34E-01 1.99E+OO pCi/L Surface Water 698142001 11/26/2024 Niobium-95 1.35E+OO 6.38E-01 2.30E+OO pCi/L Surface Water 698142001 11/26/2024 Zinc-65

-1.72E+OO 1.20E+OO 3.07E+OO pCi/L Surface Water 698142001 11/26/2024 Zirconium-95

-8.73E-01 1.08E+OO 3.34E+OO pCi/L Surface Water 703333001 12/31/2024 Barium-140 2.67E+OO 2.68E+OO 9.14E+OO pCi/L Surface Water 703333001 12/31/2024 Cesium-134

-1.0SE-01 4.63E-01 1.46E+OO pCi/L Surface Water 703333001 12/31/2024 Cesium-137 1.49E+OO 1.45E+OO 1.41E+OO pCi/L Surface Water 703333001 12/31/2024 Cobalt-58

-4.47E-01 4.03E-01 1.21E+OO pCi/L Surface Water 703333001 12/31/2024.

Cobalt-SO

-2.86E-01 4.21E-01 1.34E+OO pCi/L Surface Water 703333001 12/31/2024 lodine-131 5.76E-03 1.13E+OO 3.79E+OO pCi/L Surface Water 703333001 12/31/2024 lron-59

-2.70E+OO 1.12E+OO 2.79E+OO pCi/L Surface Water 703333001 12/31/2024 Lanthanum-140

-2.34E-01 1.02E+OO 3.29E+OO pCi/L Surface Water 703333001 12/31/2024 Manganese-54

-4.92E-01 4.03E-01 1.20E+OO pCi/L Surface Water 703333001 12/31/2024 Nicibium-95 1.BOE-01 4.37E-01 1.43E+OO pCi/L Surface Water 703333001 12/31/2024 Zinc-65

-1.71E+OO 8.16E-01 2.44E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 106 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-5 Monthly Composite Gamma Spectrum Sample Type lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 703333001 12/31/2024 Zirconium-95

-1.53E+OO 7.92E-01 2.31E+OO pCi/L SW-5 Quarterly Com__2_osite Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surtace Water 665489001 3/26/2024 Tritium 8.81E+03 4.33E+02 6.75E+02 pCi/L Surface Water 678504001 6/25/2024 Tritium 1.33E+04 6.46E+02 7.71E+02 pCi/L Surface Water 692597001 9/24/2024 Tritium 1.10E+04 5.82E+02 7.41E+02 pCi/L Surface Water 707025001 12/31/2024 Tritium 1.37E+04 3.44E+02 5.39E+02 pCi/L SW-6 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 653791001 1/30/2024 Barium-140 6.15E-01 3.26E+OO L06E+01 pCi/L Surface Drinking 653791001 1/30/2024 Cesium-134 9.89E-03 5.92E-01 1.99E+OO pCi/L Surface Drinking 653791001 1/30/2024 Cesium-137

-2.82E-01 6.61E-01 2.06E+OO pCi/L Surface Drinking 653791001 1/30/2024 Cobalt-58 4.57E-02 5.85E-01 1.97E+OO pCi/L Surface Drinking 653791001 1/30/2024 Cobalt-60

-7.87E-02 6.91E-01 1.91E+OO pCi/L Surface Drinking 653791001 1/30/2024 lodine-131

-1.13E+OO 1.29E+OO 3.74E+OO pCi/L Surface Drinking 653791001 1/30/2024 lron-59

-3.22E-01 1.20E+OO 3.86E+OO pCi/L Surface Drinking 653791001 1/30/2024 Lanthanum-140

-1.04E+OO 1.02E+OO 3.20E+OO pCi/L Surface Drinking 653791001 1/30/2024 Manganese-54

-4.05E-01 5.58E-01 1.81E+OO pCi/L Surface Drinking 653791001 1/30/2024 Niobium-95 5.54E-01 7.36E-01 2.27E+OO pCi/L Surface Drinking 653791001 1/30/2024 Zinc-65

-1.39E+OO 1.32E+OO 4.08E+OO pCi/L Surface Drinking 653791001 1/30/2024 Zirconium-95

-1.40E+OO 9.92E-01 3.15E+OO pCi/L Surface Drinking 653791001 1/30/2024 Iodine-131

-3.05E-01 2-05E-01 7.05E-01 pCi/L Surface Water 657015001 2/27/2024 lodine-131 3.35E-01 2.65E-01 8.25E-01 pCi/L Surface Water 657015001 2/27/2024 Barium-140

-2.25E+OO 2.77E+OO 8.74E+OO pCi/L Surface Water 657015001 2/27/2024 Cesium-134 8.24E-01 5.66E-01 1.95E+OO pCi/L Surface Water 657015001 2/27/2024 Cesium-137 8.SOE-01 5.61E-01 1.95E+OO pCi/L Surface Water 657015001 2/27/2024 Cobalt-58

-6.30E-01 5.22E-01 1.53E+OO pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 107 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-6 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Water 657015001 2/27/2024 Cobalt-60 3.04E-01 5.56E-01 1.90E+00 pCi/L Surface Water 657015001 2/27/2024 lodine-131 4.67E-01 8.92E-01 3.05E+00 pCi/L Surface Water 657015001 2/27/2024 lron-59

-1.51E+00 1.11E+00 3.40E+00 pCi/L Surface Water 657015001 2/27/2024 Lanthanum-140

-1.23E+00 8.94E-01 2.54E+00 pCi/L Surface Water 657015001 2/27/2024 Manganese-54 2.06E-01 5.73E-01 1.85E+00 pCi/L Surface Water 657015001 2/27/2024 Niobium-95 1.SSE-01 5.33E-01 1.73E+00 pCi/L Surface Water 657015001 2/27/2024 Zinc-65

-7.28E-01 1.44E+0O 3.34E+00 pCi/L Surface Water 657015001 2/27/2024 Zirconium-95 1.08E+00 9.59E-01 3.26E+00 pCi/L Surface Drinking 660509001 3/26/2024 Barium-140

-1.32E-01 2.58E+0O 8.36E+00 pCi/L Surface Drinking 660509001 3/26/2024 Cesium-134

-1.13E-02 6.22E-01 2.11E+00 pCi/L Surface Drinking 660509001 3/26/2024 Cesium-137 2.64E-01 8.44E-01 2.26E+00 pCi/L Surface Drinking 660509001 3/26/2024 Cobalt-58 8.0SE-01 6.12E-01 2.13E+00 pCi/L Surface Drinking 660509001 3/26/2024 Cobalt-60 6.87E-01 5.76E-01 2.04E+00 pCi/L Surface Drinking 660509001 3/26/2024 lodine-131

-2.30E-01 8.25E-01 2.72E+0O pCi/L Surface Drinking 660509001 3/26/2024 lron-59

-1.15E+00 1.02E+00 3.lOE+0O pCi/L Surface Drinking 660509001 3/26/2024 Lanthanum-140

-9.58E-01 9.43E-01 2.78E+0O pCi/L Surface Drinking 660509001 3/26/2024 Manganese-54

-2.24E-01 5.76E-01 1.91E+0O pCi/L Surface Drinking 660509001 3/26/2024 Niobium-95

-3.07E-01 5.72E-01 1.90E+0O pCi/L Surface Drinking 660509001 3/26/2024 Zinc-65

-5.41E-01 1.26E+00 4.05E+0O pCi/L Surface Drinking 660509001 3/26/2024 Zirconium-95 1.21E-01 9.34E-01 3.20E+0O pCi/L Surface Drinking 660509001 3/26/2024 lodine-131 3.0SE-01 2.60E-01 7.97E-01 pCi/L Surface Drinking 665741001 4/30/2024 Barium-140 1.0BE-01 2.58E+00 8.61E+0O pCi/L Surface Drinking 665741001 4/30/2024 Cesium-134

-7.58E-01 8.30E-01 2.19E+0O pCi/L Surface Drinking 665741001 4/30/2024 Cesium-137 5.15E-01 6.66E-01 2.26E+00 pCi/L Surface Drinking 665741001 4/30/2024 Cobalt-58

-4.13E-01 6.41E-01 2.00E+00 pCi/L Surface Drinking 665741001 4/30/2024 Cobalt-60 1.92E+00 7.45E-01 2.37E+00 pCi/L Surface Drinking 665741001 4/30/2024 lodine-131

-1.53E-02 8.02E-01 2.74E+00 pCi/L Surface Drinking 665741001 4/30/2024 lron-59

-1.02E+00 1.16E+00 3.72E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 108 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-6 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 665741001 4/30/2024 Lanthanum-140

-1.16E+0O 9.32E-01 2.75E+00 pCi/L Surface Drinking 665741001 4/30/2024 Manganese-54

-1.87E-01 6.44E-01 2.04E+00 pCi/L Surface Drinking 665741001 4/30/2024 Niobium-95 1.02E+00 6.0lE-01 2.12E+00 pCi/L Surface Drinking 665741001 4/30/2024 Zinc-65 1.50E-01 1.10E+00 3.75E+00 pCi/L Surtace Drinking 665741001 4/30/2024 Zirconium-95

-1.14E+00 1.05E+00 3.18E+00 pCi/L Surface Drinking 665741001 4/30/2024 lodine-131

-7.69E-01 2.27E-01 7.96E-01 pCi/L Surface Drinking 669524001 5/28/2024 Barium-140 2.61E-01 3.20E+00 1.07E+01 pCi/L Surface Drinking 669524001 5/28/2024

. Cesium-134 1.68E+00 6.66E-01 2.44E-1-00 pCi/L Surface Drinking 669524001 5/28/2024 Cesium-137 6.69E-01 6.67E-01 2.29E-1-00 pCi/L Surface Drinking 669524001 5/28/2024 Cobalt-58 1.54E+00 6.88E-01 2.46E+00 pCi/L Surface Drinking 669524001 5/28/2024 Cobalt-60

-1.56E-01 6.41E-01 2.10E+00 pCi/L Surface Drinking 669524001 5/28/2024 lodine-131 1.27E+00 1.20E+00 3.87E+00 pCi/L Surface Drinking 669524001 5/28/2024 lron-59

-9.46E-01 1.29E+00 4.18E+00 pCi/L Surface Drinking 669524001 5/28/2024 La nth a nu m-140

-1.54E+00 1.18E+00 3.48E+00 pCi/L Surface Drinking 669524001 5/28/2024 Ma nga nese-54

-7.09E-02 6.34E-01 2.03E+00 pCi/L Surface Drinking 669524001 5/28/2024 Niobium-95

-4.24E-01 6.74E-01 2.12E+00 pCi/L Surface Drinking 669524001 5/28/2024 Zinc-65 1.0lE+00 1.28E+00 4.08E+00 pCi/L Surface Drinking 669524001 5/28/2024 Zirconium-95

-3.46E+00 2.03E+00 3.52E+00 pCi/L Surface Drinking 669524001 5/28/2024 lodine-131

-1.04E-01 2.98E-01 9.88E-01 pCi/L Surface Drinking 673279001 6/25/2024 Barium-140

-3.92E+00 4.43E+00 9.46E+00 pCi/L Surface Drinking 673279001 6/25/2024 Cesium-134 2.27E-01 5.77E-01 1.99E+00 pCi/L Surface Drinking 673279001 6/25/2024 Cesium-137

-3.04E-01 6.46E-01 2.02E+00 pCi/L Surface Drinking 673279001 6/25/2024 Cobalt-58

-3.86E-01 4.65E-01 1.49E+00 pCi/L Surface Drinking 673279001 6/25/2024 Cobalt-60

-2.60E-01 6.60E-01 2.07E+00 pCi/L Surface Drinking 673279001 6/25/2024 lodine-131

-1.87E-01 1.0lE+00 3.38E+00 pCi/L Surface Drinking 673279001 6/25/2024 lron-59

-1.29E+00 1.30E+00 4.01E+00 pCi/L Surtace Drinking 673279001 6/25/2024 Lanthanum-140

-2.84E-01 1.17E+00 3.34E+00 pCi/L Surface Drinking 673279001 6/25/2024 Manganese-54

-2.90E-01 5.37E-01 1.76E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 j Page 109 of 138

--~---

Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant SW-6 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 673279001 6/25/2024 Niobium-95

-1.86E-01 5.33E-01 1.78E+0O pCi/L Surface Drinking 673279001 6/25/2024 Zinc-65 4.70E-02 1.08E+00 3.56E+0O pCi/L Surface Drinking 673279001 6/25/2024 Zirconium-95

-7.83E-01 9.89E-01 3.24E+0O pCi/L Surface Drinking 673279001 6/25/2024 lodine-131

-9.39E-02 2.59E-01 8.64E-01 pCi/L Surface Drinking 678789001 7/30/2024 Barium-140 1.21E+00 2.27E+00 7.69E+0O pCi/L Surface Drinking 678789001 7/30/2024 Cesium-134 1.21E+00 6.84E-01 2.37E+0O pCi/L Surface Drinking 678789001 7/30/2024 Cesium-137 1.98E-02 5.67E-01 1.86E+0O pCi/L Surtace Drinking 678789001 7/30/2024 Cobalt-58

-9.89E-01 5.69E-01 1.69E+0O pCi/L Surface Drinking 678789001 7/30/2024 Cobalt-60

-1.39E-01 5.08E-01 1.67E+0O pCi/L Surface Drinking 678789001 7/30/2024 lodine-131

-1.00E+00 7.56E-01 2.49E+00 pCi/L Surface Drinking 678789001 7/30/2024 lron-59

-1.55E+00 8.90E-01 2.71E+00 pCi/L Surface Drinking 678789001 7/30/2024 Lanthanum-140 1.43E-02 7.71E-01 2.54E+00 pCi/L Surface Drinking 678789001 7/30/2024 Manganese-54

-3.99E-01 6.0SE-01 1.90E+00 pCi/L Surface Drinking 678789001 7/30/2024 Niobium-95 4.21E-01 5.55E-01 1.86E+00 pCi/L Surface Drinking 678789001 7/30/2024 Zinc-65

-1.0SE+00 1.04E+0O 3.32E+00 pCi/L Surface Drinking 678789001 7/30/2024 Zirconium-95

-1.42E+00 9.85E-01 2.98E+00 pCi/L Surface Drinking 678789001 7/30/2024 lodine-131

-5.22E-01 2.15E-01 8.00E-01 pCi/L Surface Drinking 683314001 8/27/2024 lodine-131

-4.38E-02 1.57E-01 5.19E-01 pCi/L Surface Drinking 683314001 8/27/2024 Barium-140 1.63E+00 3.40E+00 1.15E+01 pCi/L Surface Drinking 683314001 8/27/2024 Cesium-134 8.04E-01 4.13E-01 1.47E+00 pCi/L Surface Drinking 683314001 8/27/2024 Cesium-137

-5.42E-01 3.92E-01 1.20E+00 pCi/L Surface Drinking 683314001 8/27/2024 Cobalt-58

-7.15E-02 4.44E-01 1.43E+00 pCi/L Surface Drinking 683314001 8/27/2024 Cobalt-60 1.25E+00 4.34E-01 1.68E+00 pCi/L Surface Drinking 683314001 8/27/2024 lodine-131 3.41E-01 1.57E+00 5.39E+00 pCi/L Surface Drinking 683314001 8/27/2024 lron-59 6.29E-01 9.49E-01 3.32E+00 pCi/L Surface Drinking 683314001 8/27/2024 Lanthanum-140

-3.73E-01 1.33E+00 4.31E+0O pCi/L Surface Drinking 683314001 8/27/2024 Manganese-54

-2.0lE-01 4.32E-01 1.37E+00 pCi/L Surface Drinking 683314001 8/27/2024 Niobium-95 2.40E-01 4.53E-01 1.51E+00 pCi/L

---*--**---**-*--*-*-*-*--~- --,*--*

Annual Environmental Operating Report J

YEAR: 2024 I Page 110 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant SW-6 Monthly Composite Gamma S_2.ectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 683314001 8/27/2024 Zinc-65

-6.48E-01 9.00E-01 2.95E+OO pCi/L Surface Drinking 683314001 8/27/2024 Zirconium-95

-1.72E-01 8.22E-01 2.65E+OO pCi/L Surface Drinking 687525001 9/24/2024 Barium-140

-7.41E+OO 3.33E+OO 1.01E+01 pCi/L Surface Drinking 687525001 9/24/2024 Cesium-134 8.50E-01 7.08E-01 2.41E+OO pCi/L Surface Drinking 687525001 9/24/2024 Cesium-137 7.73E-01 6.65E-01 2.29E+OO pCi/L Surface Drinking 687525001 9/24/2024 Cobalt-58 2.47E-01 6.54E-01 2.25E+OO pCi/L Surface Drinking 687525001 9/24/2024 Cobalt-60

-5.49E-01 6.93E-01 2.20E+OO pCi/L Surface Drinking 687525001 9/24/2024 lodine-131 1.35E+OO 1.36E+OO 4.11E+OO pCi/L Surface Drinking 687525001 9/24/2024 lron-59 3.11E-01 1.36E+OO 4.51E+OO pCi/L Surface Drinking 687525001 9/24/2024 Lanthanum-140

-2.93E-01 1.47E+OO 4.77E+OO pCi/L Surface Drinking 687525001 9/24/2024 Manganese-54 8.88E-01 6.62E-01 2.36E+OO pCi/L Surface Drinking 687525001 9/24/2024 Niobium-95 6.41E-01 6.96E-01 2.34E+OO pCi/L Surface Drinking 687525001 9/24/2024 Zinc-65

-3.46E-02 1.50E+OO 4.89E+OO pCi/L Surface Drinking 687525001 9/24/2024 Zirconium-95 1.17E+OO 1.27E+OO 4.28E+OO pCi/L Surface Drinking 687525001 9/24/2024 lodine-131 3.41E-01 3.09E-01 9.49E-01 pCi/L Surface Drinking 693050001 10/29/2024 Barium-140 4.06E+OO 3.16E+OO 1.11E+01 pCi/L Surface Drinking 693050001 10/29/2024 Cesium-134 8.45E-01 6.46E-01 2.23E+OO pCi/L Surface Drinking 693050001 10/29/2024 Cesium-137

-6.75E-01 5.83E-01.

1.79E+OO pCi/L Surface Drinking 693050001 10/29/2024 Cobalt-58

-7.16E-01 6.27E-01 1.89E+OO pCi/L Surface Drinking 693050001 10/29/2024 Cobalt-60 1.72E+OO 1.42E+OO 2.86E+OO pCi/L Surface Drinking 693050001 10/29/2024 lodine-131 3.02E-01 1.28E+OO 4.37E+OO pCi/L Surface Drinking 693050001 10/29/2024 lron-59

-1.30E+OO 2.05E+OO 4.06E+OO pCi/L Surface Drinking 693050001 10/29/2024 Lanthanum-140 3.26E-01 1.19E+OO 4.00E+OO pCi/L Surface Drinking 693050001 10/29/2024 Manganese-54

-4.35E-01 6.18E-01 1.91E+OO pCi/L Surface Drinking 693050001 10/29/2024 Niobium-95 3.06E-01 6.36E-01 2.11E+OO pCi/L Surface Drinking 693050001 10/29/2024 Zinc-65 4.80E-01 1.26E+OO 4.36E+OO pCi/L Surface Drinking 693050001 10/29/2024 Zirconium-95

-2.08E-01 1.05E+OO 3.37E+OO pCi/L Surface Drinking 693050001 10/29/2024 lodine-131 2.04E-01 2.70E-01 8.72E-01 pCi/L

Annual Environmental Operating Report J

YEAR: 2024 I Page 111 of 138 Company: Vistra Corp l Comanche Peak Nuclear Power Plant SW-6 Monthly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 698143001 11/26/2024 lodine-131

-9.99E-02 2.41E-01 8.18E-01 pCi/L Surface Drinking 698143001 11/26/2024 Barium-140 3.08E+OO 2.53E+OO 8.82E+OO pCi/L Surface Drinking 698143001 11/26/2024 Cesium-134

-1.77E-01 5.17E-01 1.64E+OO pCi/L Surface Drinking 698143001 11/26/2024 Cesium-137 1.lOE-01 4.73E-01 1.56E+OO pCi/L Surface Drinking 698143001 11/26/2024 Cobalt-58

-3.43E-01 5.lOE-01 1.59E+OO pCi/L Surface Drinking 698143001 11/26/2024 Cobalt-SO

-5.04E-01 4.57E-01 1.40E+OO pCi/L Surface Drinking 698143001 11/26/2024 lodine-131

-3.02E-01 9.29E-01 3.13E+OO pCi/L Surface Drinking 698143001 11/26/2024 lron-59 6.08E-01 1.12E+OO 3.47E+OO pCi/L Surface Drinking 698143001 11/26/2024 Lanthanum-140

-1.70E+OO 9.07E-01 2.53E+OO pCi/L Surface Drinking 698143001 11/26/2024 Manganese-54

-1.21E-01 4.63E-01 1.47E+OO pCi/L Surface Drinking 698143001 11/26/2024 Niobium-95 8.48E-01 8.08E-01 1.39E+OO pCi/L Surface Drinking 698143001 11/26/2024 Zinc-65

-7.29E-01 9.50E-01 3.07E+OO pCi/L Surface Drinking 698143001 11/26/2024 Zirconium-95 4.83E-01 8.0SE-01 2.69E+OO pCi/L Surface Drinking 703332001 12/31/2024 Barium-140 2.09E+OO 4.37E+OO 1.41E+Ol pCi/L Surface Drinking 703332001 12/31/2024 Cesium-134 2.39E-01 7.97E-01 2.47E+OO pCi/L Surface Drinking 703332001 12/31/2024 Cesium-137

-1.49E+OO 1.17E+OO 2.22E+OO pCi/L Surface Drinking 703332001 12/31/2024 Cobalt-SB 4.29E-01 6.72E-01 2.20E+OO pCi/L Surface Drinking 703332001 12/31/2024 Cobalt-60 7.04E-01 5.98E-01 2.11E+OO pCi/L Surface Drinking 703332001 12/31/2024 lodine-131 9.73E-01 1.67E+OO 5.53E+OO pCi/L Surface Drinking 703332001 12/31/2024 lron-59

-3.21E+OO 1.62E+OO 4.76E+OO pCi/L Surtace Drinking 703332001 12/31/2024 Lanthanum-140

-4.08E+OO 1.78E+OO 4.11E+OO pCi/L Surface Drinking 703332001 12/31/2024 Manganese-54

-4.SOE-01 6.33E-01 2.03E+OO pCi/L Surface Drinking 703332001 12/31/2024 Niobium-95 3.98E-01 7.47E-01 2.51E+OO pCi/L Surface Drinking 703332001 12/31/2024 Zinc-65 6.89E-01 1.53E+OO 4.39E+OO pCi/L Surtace Drinking 703332001 12/31/2024 Zirconium-95

-6.29E-01 1.24E+OO 4.02E+OO pCi/L Surface Drinking 703332001 12/31/2024 lodine-131 5.63E-01 2.89E-01 8.89E-01 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 112 of 138 "T

Company: Vistra Corp I Comanche Peak Nuclear Power Plant SW-6 Quarterly Composite Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 665495001 3/26/2024 Tritium 1.23E+04 7.08E+02 9.79E+02 pCi/L Surface Drinking 679339001 6/25/2024 Tritium 1.02E+04 4.61E+02 6.00E+02 pCi/L Surface Drinking 692595001 9/24/2024 Tritium 1.20E+04 6.17E+02 8.06E+02 pCi/L Surface Drinking 707018001 12/31/2024 Tritium 1.42E+04 3.46E+02 5.32E+02 pCi/L SW-6 Monthly Composite Gross Beta Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Surface Drinking 653791001 1/30/2024 BETA 1.52E+01 1.53E+00 4.24E+00 pCi/L Surface Drinking 657015001 2/27/2024 BETA 1.58E+01 2.51E+00 7.41E+00 pCi/L Surface Drinking 660509001 3/26/2024 BETA 1.64E+01 1.85E+00 5.0lE+00 pCi/L Surface Drinking 665741001 4/30/2024 BETA 1.06E+01 1.63E+00 4.56E+00 pCi/L Surface Drinking 669524001 5/28/2024 BETA 1.80E+01 3.01E+00 3.61E+00 pCi/L Surface Drinking 673279001 6/25/2024 BETA 1.37E+01 1.71E+00 4.82E+00 pCi/L Surtace Drinking 678789001 7/30/2024 BETA 1.28E+01 2.67E+00 8.02E+00 pCi/L Surface Drinking 683314001 8/27/2024 BETA 8.08E+00 2.20E+00 6.61E+00 pCi/L Surface Drinking 687525001 9/24/2024 BETA 1.69E+01 1.65E+00 4.49E+O0 pCi/L Surface Drinking 693050001 10/29/2024 BETA 1.62E+01 2.24E+00 6.51E+00 pCi/L Surface Drinking 698143001 11/26/2024 BETA 1.63E+01 2.65E+00 7.99E+00 pCi/L Surface Drinking 703332001 12/31/2024 BETA 2.03E+0l 2.16E+00 5.98E+00 pCi/L GW-1 Quarterly_~omposite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499004 3/26/2024 Barium-140

-3.31E+00 3.04E+00 9.66E+00 pCi/L Ground Water 660499004 3/26/2024 Cesium-134

-2.63E-01 7.87E-01 2.51E+00 pCi/L Ground Water 660499004 3/26/2024 Cesium-137 9.38E-01 6.98E-01 2.23E+00 pCi/L Ground Water 660499004 3/26/2024 Cobalt-58 2.89E-01 6.69E-01 2.22E+00 pCi/L Ground Water 660499004 3/26/2024 Cobalt-60 3.0lE-01 6.25E-01 2.16E+00 pCi/L Ground Water 660499004 3/26/2024 lodine-131 2.78E-01 9.47E-01 3.26E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 113 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant GW-1 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499004 3/26/2024 lron-59

-2.54E+00 1.23E+00 3.66E+00 pCi/L Ground Water 660499004

3/26/2024 Lanthanum-140 2.28E-01 9.S0E-01 3.29E+00 pCi/L Ground Water 660499004 3/26/2024 Manganese-54

-1.13E+00 6.44E-01 1.86E+00 pCi/L Ground Water 660499004 3/26/2024 Niobium-95 2.58E+00 1.27E+0O 1.86E+00 pCi/L Ground Water 660499004 3/26/2024 Zinc-65 1.30E+00 1.14E+0O 3.80E+00 pCi/L Ground Water 660499004 3/26/2024 Zirconium-95

-1.65E+00 1.23E+0O 3.73E+00 pCi/L Ground Water 673267004 6/25/2024 Barium-140 1.53E+00 2.47E+00 8.31E+00 pCi/L Ground Water 673267004 6/25/2024 Cesium-134 7.18E-02 5.49E-01 1.76E+00 pCi/L Ground Water 673267004 6/25/2024 Cesium-137

-2.07E+00 1.02E+00 1.80E+00 pCi/L Ground Water 673267004 6/25/2024 Cobalt-58

-2.37E-01 5.43E-01 1.68E+0O pCi/L Ground Water 673267004 6/25/2024 Cobalt-60 6.84E-01 5.71E-01 2.03E+0O pCi/L Ground Water 673267004 6/25/2024 lodine-131 1.43E+00 9.34E-01 3.16E+0O pCi/L Ground Water 673267004 6/25/2024 lron-59

-5.86E-01 1.13E+00 3.65E+0O pCi/L Ground Water 673267004 6/25/2024 Lanthanum-140

-2.16E-01 9.78E-01 2.69E+0O pCi/L Ground Water 673267004 6/25/2024 Manganese-54 5.41E-02 5.18E-01 1.65E+0O pCi/L Ground Water 673267004 6/25/2024 Niobium-95

-3.87E-01 5.91E-01 1.82E+OO pCi/L Ground Water 673267004 6/25/2024 Zinc-65

-8.69E-01 1.07E+00 3.39E+00 pCi/L Ground Water 673267004 6/25/2024 Zirconium-95 3.54E-01 1.0lE+00 3.30E+00 pCi/L Ground Water 687534004 9/24/2024 Barium-140

-2.77E+00 2.55E+00 8.06E+00 pCi/L Ground Water 687534004 9/24/2024 Cesium-134 5.38E-01 5.19E-01 1.78E+00 pCi/L Ground Water 687534004 9/24/2024 Cesium-137 1.15E+00 4.99E-01 1.82E+00 pCi/L Ground Water 687534004 9/24/2024 Cobalt-58 1.81E-01 4.77E-01 1.58E+00 pCi/L Ground Water 687534004 9/24/2024 Cobalt-60

-5.24E-01 4.73E-01 1.44E+00 pCi/L Ground Water 687534004 9/24/2024 lodine-131 1.69E+00 1.03E+00 3.71E+00 pCi/L Ground Water 687534004 9/24/2024 lron-59

-7.58E-01 1.02E+00 2.83E+00 pCi/L Ground Water 687534004 9/24/2024 La nth a num-140 3.15E+00 1.05E+00 4.15E+00 pCi/L Ground Water 687534004 9/24/2024 Manganese-54

-4.37E-01 5.49E-01 1.70E+00 pCi/L Ground Water 687534004 9/24/2024 Niobium-95 2.38E-02 5.40E-01 1.76E+00 pCi/L

Annual Environmental Operating~ Report J

YEAR: 2024 I Page 114 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant GW-1 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 687534004 9/24/2024 Zinc-65 4.67E-02 9.57E-01 3.26E+0O pCi/L Ground Water 687534004 9/24/2024 Zirconium-95

-2.08E-01 9.14E-01 2.94E+0O pCi/L Ground Water 701437004 12/17/2024 Barium-140

-4.75E+00 2.18E+00 6.75E+00 pCi/L Ground Water 701437004 12/17/2024 Cesium-134 6.96E-01 7.49E-01 1.66E+0O pCi/L Ground Water 701437004 12/17/2024 Cesium-137 4.17E-01 4.78E-01 1.45E+0O pCi/L Ground Water 701437004 12/17/2024 Cobalt-58 4.70E-01 4.34E-01 1.46E+0O pCi/L Ground Water 701437004 12/17/2024 Cobalt-60

-2.73E+00 1.09E+00 1.71E+0O pCi/L Ground Water 701437004 12/17/2024 lodine-131

-5.71E-01 7.76E-01 2.59E+00 pCi/L Ground Water 701437004 12/17/2024 lron-59 5.22E-01 8.72E-01 3.02E+00 pCi/L Ground Water 701437004 12/17/2024 Lanthanum-140

-6.50E-01 6.85E-01 2.12E+00 pCi/L Ground Water 701437004 12/17/2024 Manganese-54 7.04E-01 3.81E-01 1.32E+00 pCi/L Ground Water 701437004 12/17/2024 Niobium-95

-9.27E-02 4.09E-01 1.31E+00 pCi/L Ground Water 701437004 12/17/2024 Zinc-65

-8.72E-01 8.77E-01 2.84E+00 pCi/L Ground Water 701437004 12/17/2024 Zirconium-95

-7.54E-01 7.55E-01 2.35E+00 pCi/L GW-1 Quarterly Composite Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499004 3/26/2024 Tritium

-9.lOE+0l 1.27E+02 4.29E+02 pCi/L Ground Water 673267004 6/25/2024 Tritium

-2.32E+01 3.55E+01 1.20E+02 pCi/L Ground Water 687534004 9/24/2024 Tritium

-2.61E+02 2.18E+02 7.66E+02 pCi/L Ground Water 701437004 12/17/2024 Tritium

-1.47E+02 1.01E+02 3.61E+02 pCi/L GW-2 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499005 3/26/2024 7:27 Barium-140 1.02E+00 2.32E+00 7.58E+00 pCi/L Ground Water 660499005 3/26/2024 7:27 Cesium-134 2.41E-02 5.66E-01 1.90E+00 pCi/L Ground Water 660499005 3/26/2024 7:27 Cesium-137 2.74E-01 5.91E-01 2.04E+00 pCi/L Ground Water 660499005 3/26/2024 Barium-140 l.02E+0O 2.32E+00 7.58E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 115 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant GW-2 Quarterly Composite Gamma Spectrum

Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499005 3/26/2024 Cesium-134 2.41E-02 5.66E-01 1.90E+00 pCi/L Ground Water 660499005 3/26/2024 Cesium-137 2.74E-01 5.91E-01 2.04E+00 pCi/L Ground Water 660499005 3/26/2024 Cobalt-58 1.76E-01 5.73E-01 1.95E+00 pCi/L Ground Water 660499005 3/26/2024 Cobalt-60 1.83E+00 6.81E-01 2.59E+00 pCi/L Ground Water 660499005 3/26/2024 lodine-131 9.05E-01 7.96E-01 2.71E+00 pCi/L Ground Water 660499005 3/26/2024 lron-59 1.12E+00 1.24E+00 3.86E+00 pCi/L Ground Water 660499005 3/26/2024 Lanthanum-140 4.06E-01 8.45E-01 2.52E+00 pCi/L Ground Water 660499005 3/26/2024 Manganese-54

-2.96E-01 5.52E-01 1.79E+00 pCi/L Ground Water 660499005 3/26/2024 Niobium-95 7.02E-01 5.66E-01 2.02E+00 pCi/L Ground Water 660499005 3/26/2024 Zinc-65 7.21E-01 1.15E+0O 3.92E+00 pCi/L Ground Water 660499005 3/26/2024 Zirconium-95

-8.12E-01 9.56E-01 3.06E+00 pCi/L Ground Water 673267005 6/25/2024 Barium-140 3.84E-01 2.79E+00 8.97E+00 pCi/L Ground Water 673267005 6/25/2024 Cesium-134 9.17E-01 6.43E-01 2.29E+00 pCi/L Ground Water 673267005 6/25/2024 Cesium-137 9.31E-01 5.98E-01 2.15E+00 pCi/L Ground Water 673267005 6/25/2024 Cobalt-58

-4.00E-01 5.90E-01 1.90E+00 pCi/L Ground Water 673267005 6/25/2024 Cobalt-60

-5.90E-01 6.76E-01 2.03E+00 pCi/L Ground Water 673267005 6/25/2024 lodine-131 1.89E+00 9.88E-01 3.45E+00 pCi/L Ground Water 673267005 6/25/2024 lron-59

-4.70E-02 1.19E+00 3.85E+00 pCi/L Ground Water 673267005 6/25/2024 Lanthanum-140

-1.S0E+00 1.11E+00 3.31E+00 pCi/L Ground Water 673267005 6/25/2024 Manganese-54

-3.l0E-01 5.58E-01 1.80E+00 pCi/L Ground Water 673267005 6/25/2024 Niobium-95 1.57E-01 5.96E-01 2.02E+00 pCi/L Ground Water 673267005 6/25/2024 Zinc-65

-1.83E+00 1.37E+00 4.11E+00 pCi/L Ground Water 673267005 6/25/2024 Zirconium-95 7.97E-02 1.09E+00 3.66E+00 pCi/L Ground Water 687534005 9/24/2024 Barium-140

-4.81E+00 3.40E+00 1.06E+01 pCi/L Ground Water 687534005 9/24/2024 Cesium-134 3.62E-02 6.85E-01 2.22E+00 pCi/L Ground Water 687534005 9/24/2024 Cesium-137 1.16E-01 5.75E-01 1.90E+00 pCi/L Ground Water 687534005 9/24/2024 Cobalt-58 3.42E-01 5.89E-01 1.96E+00 pCi/L Ground Water 687534005 9/24/2024 Cobalt-60

-1.25E+00 1.10E+00 2.79E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 116 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant GW-2 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 687534005 9/24/2024 lodine-131 1.58E+00 1.31E+00 4.64E+OO pCi/L Ground Water 687534005 9/24/2024 lron-59

-4.93E-01 1.24E+00 4.09E+00 pCi/L Ground Water 687534005 9/24/2024 Lanthanum-140

-8.86E-01 1.74E+00 3.90E+00 pCi/L Ground Water 687534005 9/24/2024 Manganese-54

-8.02E-01 6.72E-01 1.75E+00 pCi/L Ground Water 687534005 9/24/2024 Niobium-95 1.06E+00 6.61E-01 2.30E+00 pCi/L Ground Water 687534005 9/24/2024 Zinc-65

-8.lOE-02 1.24E+00 4.16E+00 pCi/L Ground Water 687534005 9/24/2024 Zirconium-95 1.16E+00 1.04E+00 3.58E+00 pCi/L Ground Water 701437005 12/17/2024 Barium-140 2.73E+00 2.34E+00 8.00E+00 pCi/L Ground Water 701437005 12/17/2024 Cesium-134

-2.17E-01 5.35E-01 1.68E+00 pCi/L Ground Water 701437005 12/17/2024 Cesium-137 4.41E-01 4.95E-01 1.66E+00 pCi/L Ground Water 701437005 12/17/2024 Cobalt-58

-1.83E+00 7.78E-01 1.57E+O0 pCi/L Ground Water 701437005 12/17/2024 Cobalt-60 5.36E-03 5.03E-01 1.65E+00 pCi/L Ground Water 701437005 12/17/2024 Iodine-131 7.73E-01 7.54E-01 2.63E+00 pCi/L Ground Water 701437005 12/17/2024 lron-59

-1.97E+00 1.07E+00 2.78E+00 pCi/L Ground Water 701437005 12/17/2024 Lanthanum-140

-7.02E-01 8.91E-01 2.74E+00 pCi/L Ground Water 701437005 12/17/2024 Manganese-54

-8.21E-02 4.68E-01 1.48E+00 pCi/L Ground Water 701437005 12/17/2024 Niobium-95 1.60E+00 8.85E-01 1.58E+00 pCi/L Ground Water 701437005 12/17/2024 Zinc-65 1.26E+00 9.54E-01 3.27E+00 pCi/L Ground Water 701437005 12/17/2024 Zirconium-95

-1.16E-01 8.66E-01 2.76E+00 pCi/L GW-2 Quarterly Composite Tritium Sample Type LablD Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499005 3/26/2024 Tritium 3.61E+00 l.37E+02 4.51E+02 pCi/L Ground Water 673267005 6/25/2024 Tritium

-8.0lE+00 3.68E+01 1.22E+02 pCi/L Ground Water 687534005 9/24/2024 Tritium 1.85E+02 2.54E+02 8.03E+02 pCi/L Ground Water 701437005 12/17/2024 Tritium 3.95E+01 1.15E+02 3.71E+02 pCi/L

Annual Environmental Operating Report I YEAR: 2024 ! Pa_ge 117 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant GW-3 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499001 3/26/2024 Barium-140 2.22E+00 3.0SE+0O 1.05E+01 pCi/L Ground Water 660499001 3/26/2024 Cesium-134 2.20E-01 7.32E-01 2.42E+00 pCi/L Ground Water 660499001 3/26/2024 Cesium-137

-3.l0E-01 1.02E+00 2.98E+00 pCi/L Ground Water 660499001 3/26/2024 Cobalt-58 1.13E+00 7.03E-01 2.51E+00 pCi/L Ground Water 660499001 3/26/2024 Cobalt-60

-5.85E-01 7.65E-01 2.38E+00 pCi/L Ground Water 660499001 3/26/2024 lodine-131 1.33E-01 1.02E+00 3.50E+00 pCi/L Ground Water 660499001 3/26/2024 lron-59

-2.70E+0O 1.43E+00 4.19E+00 pCi/L Ground Water 660499001 3/26/2024 Lanthanum-140 3.85E-01 1.24E+00 4.16E+00 pCi/L Ground Water 660499001 3/26/2024 Manganese-54 1.44E+00 7.03E-01 2.56E+00 pCi/L Ground Water 660499001 3/26/2024 Niobium-95

-S.11E-01 7.90E-01 2.47E+00 pCi/L Ground Water 660499001 3/26/2024 Zinc-65

-7.51E-01 1.62E+00 4.61E+00 pCi/L Ground Water 660499001 3/26/2024 Zirconium-95

-5.29E-02 1.27E+0O 4.11E+00 pCi/L Ground Water 673267001 6/25/2024 Barium-140 2.24E+00 4.15E+0O 1.38E+01 pCi/L Ground Water 673267001 6/25/2024 Cesium-134 1.21E+00 9.44E-01 3.37E+00 pCi/L Ground Water 673267001 6/25/2024 Cesium-137 1.62E+00 8.91E-01 3.10E+00 pCi/L Ground Water 673267001 6/25/2024 Cobalt-58

-1.36E+00 8.12E-01 2.48E+00 pCi/L Ground Water 673267001 6/25/2024 Cobalt-60 5.15E-01 9.27E-01 3.11E+00 pCi/L Ground Water 673267001 6/25/2024 lodine-131 1.35E+00 1.37E+00 4.72E+00 pCi/L Ground Water 673267001 6/25/2024 lron-59 1.84E+00 1.78E+00 6.20E+00 pCi/L Ground Water 673267001 6/25/2024 Lanthanum-140 1.44E-01 1.S0E+00 5.04E+00 pCi/L Ground Water 673267001 6/25/2024 Manganese-54 1.61E+00 8.33E-01 3.05E+00 pCi/L Ground Water 673267001 6/25/2024 Niobium-95 6.11E-01 9.53E-01 3.31E+00 pCi/L Ground Water 673267001 6/25/2024 Zinc-65

-2.31E+00 1.95E+00 5.91E+00 pCi/L Ground Water 673267001 6/25/2024 Zirconium-95

-1.76E-01 1.30E+00 4.35E+00 pCi/L Ground Water 687534001 9/24/2024 Barium-140

-1.51E+00 3.29E+00 1.08E+01 pCi/L Ground Water 687534001 9/24/2024 Cesium-134 1.21E+00 6.12E-01 2.16E+0O pCi/L Ground Water 687534001 9/24/2024 Cesium-137

-1.39E-01 6.00E-01 1.95E+0O pCi/L Ground Water 687534001 9/24/2024 Cobalt-58

-3.85E-01 6.0lE-01 1.88E+0O pCi/L

Annual Environmental Operating Report J

YEAR: 2024 J Page 118 of 138 Company; Vistra Corp I Comanche Peak Nuclear Power Plant GW-3 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 687534001 9/24/2024 Cobalt-SO

-1.89E+OO 1.36E+OO 1.49E+OO pCi/L Ground Water 687534001 9/24/2024 lodine-131 9.57E-01 1.18E+OO 4.09E+OO pCi/L Ground Water 687534001 9/24/2024 lron-59

-1.27E+OO 1.12E+OO 3.58E+OO pCi/L Ground Water 687534001 9/24/2024 Lanthanum-140

-1.95E+OO 1.22E+OO 2.97E+OO pCi/L Ground Water 687534001 9/24/2024 Manganese-54

-1.0SE+OO 6.47E-01 1.66E+OO pCi/L Ground Water 687534001 9/24/2024 Niobium-95

-3.06E+OO 8.27E-01 1.75E+OO pCi/L Ground Water 687534001 9/24/2024 Zinc-65 4.54E-02 1.23E+OO 3.70E+OO pCi/L Ground Water 687534001 9/24/2024 Zi rconiu m-95

-6.16E-01 1.14E+OO 3.20E+OO pCi/L Ground Water 701437001 12/17/2024 Barium-140 2.78E-01 1.59E+OO 5.26E+OO pCi/L Ground Water 701437001 12/17/2024 Cesium-134 1.23E+OO 5.99E-01 1.31E+OO pCi/L Ground Water 701437001 12/17/2024 Cesium-137

-2.00E-02 3.44E-01 1.12E+OO pCi/L Ground Water 701437001 12/17/2024 Cobalt-58

-1.34E-01 3.65E-01 1.02E+OO pCi/L Ground Water 701437001 12/17/2024 Cobalt-60

-6.18E-01 4.41E-01 1.09E+OO pCi/L Ground Water 701437001 12/17/2024 lodine-131

-1.61E-01 5.99E-01 2.01E+OO pCi/L Ground Water 701437001 12/17/2024 lron-59

-2.16E-01 7.10E-01 2.08E+OO pCi/L Ground Water 701437001 12/17/2024 Lanthanum-140

-1.93E-01 5.36E-01 1.66E+OO pCi/L Ground Water 701437001 12/17/2024 Ma nga nese-54 2.77E-01 3.44E-01 1.02E+OO pCi/L Ground Water 701437001 12/17/2024 Niobium-95

-2.0SE+OO 8.77E-01 1.09E+OO pCi/L Ground Water 701437001 12/17/2024 Zinc-65 5.78E-01 7.54E-01 2.33E+OO pCi/L Ground Water 701437001 12/17/2024 Zirconium-95 1.23E-01 5.84E-01 1.90E+OO pCi/L GW-3 Quarterly Composite Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499001 3/26/2024 Tritium 6.60E+01 1.32E+02 4.27E+02 pCi/L Ground Water 673267001 6/25/2024 Tritium

-8.88E+01 3.28E+01 1.20E+02 pCi/L Ground Water 687534001 9/24/2024 Tritium

-2.43E+02 2.32E+02 8.08E+02 pCi/L Ground water 701437001 12/17/2024 Tritium

-1.28E+02 1.05E+02 3.72E+02 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Pa_ge 119 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant GW-4 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499003 3/26/2024 Barium-140

-9.65E-01 3.0lE+00 9.67E+00 pCi/L Ground Water 660499003 3/26/2024 Cesium-134

-5.35E-02 7.0lE-01 2.36E+00 pCi/L Ground Water 660499003 3/26/2024 Cesium-137 1.25E+00 7.20E-01 2.50E+00 pCi/L Ground Water 660499003 3/26/2024 Cobalt-58

-5.95E-01 6.43E-01 2.07E+0O pCi/L Ground Water 660499003 3/26/2024 Cobalt-60

-1.18E+00 6.90E-01 1.90E+00 pCi/L Ground Water 660499003 3/26/2024 lodine-131 1.30E+00 1.04E+00 3.61E+00 pCi/L Ground Water 660499003 3/26/2024 lron-59

-1.94E+00 1.48E+00 4.49E+0O pCi/L Ground Water 660499003 3/26/2024 Lanthanum-140 1.49E+0O 1.21E+00 4.15E+00 pCi/L Ground Water 660499003 3/26/2024 Manganese-54 1.70E+00 8.65E-01 2.33E+00 pCi/L Ground Water 660499003 3/26/2024 Niobium-95 6.0SE-01 6.88E-01 2.42E+O0 pCi/L Ground Water 660499003 3/26/2024 Zinc-65

-2.97E+00 1.58E+00 4.59E+00 pCi/L Ground Water 660499003 3/26/2024 Zirconium-95 2.34E+00 1.33E+00 4.83E+00 pCi/L Ground Water 673267003 6/25/2024 Barium-140 9.45E-01 2.19E+00 7.36E+00 pCi/L Ground Water 673267003 6/25/2024 Cesium-134 1.02E-01 5.86E-01 1.70E+00 pCi/L Ground Water 673267003 6/25/2024 Cesium-137 8.42E-01 4.89E-01 1.73E+00 pCi/L Ground Water 673267003 6/25/2024 Cobalt-58 7.07E-01 4.65E-01 1.62E+00 pCi/L Ground Water 673267003 6/25/2024 Cobalt-60

-2.16E-01 5.47E-01 1.79E+00 pCi/L Ground Water 673267003 6/25/2024 lodine-131

-1.03E+00 7.25E-01 2.32E+00 pCi/L Ground Water 673267003 6/25/2024 lron-59

-1.16E+00 8.84E-01 2.76E+00 pCi/L Ground Water 673267003 6/25/2024 Lanthanum-140 1.00E+00 6.99E-01 2.56E+00 pCi/L Ground Water 673267003 6/25/2024 Manganese-54 4.07E-01 4.84E-01 1.63E+00 pCi/L Ground Water 673267003 6/25/2024 Niobium-95 2.97E-01 4.72E-01 1.58E+00 pCi/L Ground Water 673267003 6/25/2024 Zinc-65 9.86E-01 8.57E-01 3.l0E+00 pCi/L Ground Water 673267003 6/25/2024 Zirconium-95

-2.52E-01 8.67E-01 2.76E+00 pCi/L Ground Water 687534003 9/24/2024 Barium-140 4.91E+00 4.07E+00 8.73E+0O pCi/L Ground Water 687534003 9/24/2024 Cesium-134 1.31E-01 5.26E-01 1.71E+0O pCi/ L Ground Water 687534003 9/24/2024 Cesium-137 1.63E+O0 4.94E-01 1.82E+0O pCi/L Ground Water 687534003 9/24/2024 Cobalt-58

-3.17E-01 4.82E-01 1.30E+00 pCi/L

Annual Environmental Operating~ Report I YEAR: 2024 I Page 120 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant GW-4 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 687534003 9/24/2024 Cobalt-60 3.33E-01 4.50E-01 1.57E+0O pCi/L Ground Water 687534003 9/24/2024 lodine-131

-1.27E+00 1.12E+00 3.23E+0O pCi/L Ground Water 687534003 9/24/2024 lron-59 2.22E-01 1.02E+00 3.08E+0O pCi/L Ground Water 687534003 9/24/2024 Lanthanum-140

-7.45E-02 8.74E-01 2.85E+0O pCi/L Ground Water 687534003 9/24/2024 Manganese-54

-9.80E-01 4.88E-01 1.40E+0O pCi/L Ground Water 687534003 9/24/2024 Niobium-95 1.57E+00 4.93E-01 1.82E+00 pCi/L Ground Water 687534003 9/24/2024 Zinc-65 1.04E+00 8.80E-01 3.16E+00 pCi/L Ground Water 687534003 9/24/2024 Zirconium-95 1.42E-02 8.12E-01 2.62E+00 pCi/L Ground Water 701437003 12/17/2024 Barium-140

-3.91E+00 3.37E+00 1.03E+01 pCi/L Ground Water 701437003 12/17/2024 Cesium-134 7.16E-01 7.20E-01 2.46E+0O pCi/L Ground Water 701437003 12/17/2024 Cesium-137 1.78E+00 7.l0E-01 2.54E+0O pCi/L Ground Water 701437003 12/17/2024 Cobalt-58 4.39E-01 6.59E-01 2.08E+0O pCi/L Ground Water 701437003 12/17/2024 Cobalt-60 2.62E-01 6.11E-01 2.08E+0O pCi/L Ground Water 701437003 12/17/2024 lodine-131

-1.21E-01 1.05E+00 3.42E+0O pCi/L Ground Water 701437003 12/17/2024 lron-59 1.93E+00 1.31E+00 4.47E+OO pCi/L Ground Water 701437003 12/17/2024 Lanthanum-140

-1.04E+00 9.93E-01 3.06E+0O pCi/L Ground Water 701437003 12/17/2024 Manganese-54

-6.47E-01 6.13E-01 1.94E+0O pCi/L Ground Water 701437003 12/17/2024 Niobium-95 8.03E-01 6.88E-01 2.12E+0O pCi/L Ground Water 701437003 12/17/2024 Zinc-65 4.59E-01 1.35E+00 4.38E+OO pCi/L Ground Water 701437003 12/17/2024 Zirconium-95 1.71E+00 1.20E+00 4.16E+OO pCi/L GW-4 Quarterly Composite Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499003 3/26/2024 Tritium 1.24E+02 1.36E+02 4.32E+02 pCi/L Ground Water 673267003 6/25/2024 Tritium

-8.01E+01 3;35E+01 1.21E+02 pCi/l Ground Water 687534003 9/24/2024 Tritium

-1.90E+02 2.33E+02 8.03E+02 pCi/L Ground Water 701437003 12/17/2024 Tritium

-2.66E+02 9.47E+01 3.66E+02 pCi/L

Annual Environmental Operating Report J

YEAR: 2024 J Page 121 of 138 Company: Vistra Corp J Comanche Peak Nuclear Power Plant GW-5 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499002 3/26/2024 Barium-140

-3.69E+00 3.24E+00 9.71E+0O pCi/L Ground Water 660499002 3/26/2024 Cesium-134 3.03E-01 8.67E-01 2.94E+OO pCi/L Ground Water 660499002 3/26/2024 Cesium-137

-1.29E+00 8.83E-01 2.20E+OO pCi/L Ground Water 660499002 3/26/2024 Cobalt-58

-7.03E-02 6.49E-01 2.15E+0O pCi/L Ground Water 660499002 3/26/2024 Cobalt-60 3.13E-01 7.0lE-01 2.34E+0O pCi/L Ground Water 660499002 3/26/2024 lodine-131

-9.07E-01 9.58E-01 3.0lE+00 pCi/L Ground Water 660499002 3/26/2024 lron-59 8.05E-01 1.45E+00 4.89E+0O pCi/L Ground Water 660499002 3/26/2024 Lanthanum-140 8.82E-01 1.14E+00 4.01E+0O pCi/L Ground Water 660499002 3/26/2024 Manganese-54 4.94E-01 6.68E-01 2.31E+0O pCi/L Ground Water 660499002 3/26/2024 Niobium-95 1.49E+00 7.52E-01 2.75E+0O pCi/L Ground Water 660499002 3/26/2024 Zinc-65 1.93E-01 1.48E+00 4.84E+0O pCi/L Ground Water 660499002 3/26/2024 Zirconium-95

-3.49E-01 1.33E+00 4.38E+0O pCi/L Ground Water 673267002 6/25/2024 Barium-140 3.85E+00 2.81E+00 9.91E+0O pCi/L Ground Water 673267002 6/25/2024 Cesium-134 1.20E+00 9.24E-01 2.40E+0O pCi/L Ground Water 673267002 6/25/2024 Cesium-137 9.15E-01 6.39E-01 2.23E+0O pCi/L Ground Water 673267002 6/25/2024 Cobalt-58 3.71E-01 6.43E-01 2.23E+OO pCi/L Ground Water 673267002 6/25/2024 Cobalt-60 3.90E-01 7.98E-01 2.75E+0O pCi/L Ground Water 673267002 6/25/2024 Iodine-131

-4.76E-01 1.08E+00 3.44E+0O pCi/L Ground Water 673267002 6/25/2024 lron-59

-3.07E+00 1.71E+00 4.11E+0O pCi/L Ground Water 673267002 6/25/2024 Lanthanum-140 3.46E-02 1.13E+00 3.73E+0O pCi/L Ground Water 673267002 6/25/2024 Manganese-54

-1.18E+00 6.62E-01 2.05E+0O pCi/L Ground Water 673267002 6/25/2024 Niobium-95 1.05E+00 6.57E-01 2.28E+0O pCi/L Ground Water 673267002 6/25/2024 Zinc-65

-6.70E-01 1.45E+00 4.60E+0O pCi/L Ground Water 673267002 6/25/2024 Zirconium-95

-7.67E-01 1.22E+00 3.80E+0O pCi/L Ground Water 687534002 9/24/2024 Barium-140 2.95E+00 2.42E+00 8.40E+0O pCi/L Ground Water 687534002 9/24/2024 Cesium-134 1.28E-01 4.89E-01

1.59E+0O pCi/L Ground Water 687534002 9/24/2024 Cesium-137

-1.23E-01 5.02E-01 1.62E+00 pCi/L

Annual Environmental Operating Report I YEAR: 2024 I Page 122 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant GW-5 Quarterly Composite Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 687534002 9/24/2024 Cobalt-58

-1.64E-01

4.72E-01 1.49E+OO pCi/L Ground Water 687534002 9/24/2024 Cobalt-60 8.67E-01 4.75E-01 1.75E+OO pCi/l Ground Water 687534002 9/24/2024 lodine-131 3.93E+OO 1.95E+OO 2.88E+OO pCi/L Ground Water 687534002 9/24/2024 lron-59 1.47E+OO 1.08E+OO 2.86E+OO pCi/L Ground Water 687534002 9/24/2024 Lanthanum-140

-9.88E-01 8.96E-01 2.69E+OO pCi/L Ground Water 687534002 9/24/2024 Manganese-54 2.51E-01 3.94E-01 1.31E+OO pCi/L Ground Water 687534002 9/24/2024 Niobium-95 8.46E-01 5.44E-01 1.87E+OO pCi/L Ground Water 687534002 9/24/2024 Zinc-65 7.00E-01 9.23E-01 3.23E+OO pCi/L Ground Water -

687534002 9/24/2024 Zirconium-95

-5.77E-02 8.73E-01 2.81E+OO pCi/L Ground Water 701437002 12/17/2024 Barium-140 3.90E+OO 2.52E+OO 7.48E+OO pCi/L Ground Water 701437002 12/17/2024 Cesium-134

-3.65E-01 4.46E-01 1.45E+OO pCi/L Ground Water 701437002 12/17/2024 cesium-137

-2.83E-01 4.35E-01 1.44E+OO pCi/L Ground Water 701437002 12/17/2024 Cobalt-58 9.09E-02 4.23E-01 1.42E+OO pCi/L Ground Water 701437002 12/17/2024 Cobalt-60

-1.67E-01 4.34E-01 1.40E+OO pCi/L Ground Water 701437002 12/17/2024 lodine-131 4.43E-01 8.83E-01 2.88E+OO pCi/L Ground Water 701437002 12/17/2024 lron-59

-1.20E+OO 8.17E-01 2.54E+OO pCi/L Ground Water 701437002 12/17/2024 Lanthanum-140

-7.85E-01 7.40E-01 2.28E+OO pCi/L Ground Water 701437002 12/17/2024 Manganese-54 2.08E-01 4.33E-01 1.46E+OO pCi/L Ground Water 701437002 12/17/2024 Niobium-95

-1.98E+OO 1.15E+OO 1.60E+OO pCi/L Ground Water 701437002 12/17/2024 Zinc-65

-1.94E+OO 1.66E+OO 3.02E+OO pCi/L Ground Water 701437002 12/17/2024 Zirconium-95 1.34E+OO 7.44E-01 2.61E+OO pCi/L GW-5 Quarterly Composite Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Ground Water 660499002 3/26/2024 Tritium 3.70E+01 1.34E+02 4.36E+02 pCi/L Ground Water 673267002 6/25/2024 Tritium

-8.33E+OO 3.57E+01 1.19E+02 pCi/L Ground Water 687534002 9/24/2024 Tritium

-3.78E+02 2.26E+02 8.14E+02 pCi/L Ground Water 701437002 12/17/2024 Tritium

-1.28E+02 1.06E+02 3.73E+02 pCi/L

Annual Environmental Operating Report f YEAR: 2024 I Page 123 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant SS-1 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Sediment 651487002 1/9/2024 Cesium-134 7.70E+00 1.08E+0l 3.83E+01 pCi/kg Sediment 651487002 1/9/2024 Cesium-137 2.13E+01 1.12E+01 4.26E+01 pCi/kg Sediment 675354002 7/8/2024 Cesium-134 1.44E+0l 1.81E+0l 5.99E+0l pCi/kg Sediment 675354002 7/8/2024 Cesium-137 4.15E+00 1.35E+01 4.59E+01 pCi/kg SS-2 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Sediment 651487004 1/9/2024 Cesium-134

-1.45E+01 8.55E+00 2.54E+01 pCi/kg Sediment 651487004 1/9/2024 Cesium-137 9.26E+00 1.48E+0l 2.50E+01 pCi/kg Sediment 675354004 7/9/2024 Cesium-134 9.91E-01 9.99E+0O 3.37E+01 pCi/kg Sediment 675354004 7/9/2024 Cesium-137

-1.64E-01 1.04E+0l 3.51E+01 pCi/kg SS-3 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Sediment 651487003 1/9/2024 Cesium-134 4.0lE+0l 2.llE+0l 3.73E+01 pCi/kg Sediment 651487003 1/9/2024 Cesium-137 5.17E+00 1.16E+01 3.63E+01 pCi/kg Sediment 675354003 7/9/2024 Cesium-134

-1.20E+01 1.26E+01 3.43E+01 pCi/kg Sediment 675354003 7/9/2024 Cesium-137 4.16E+00 9.02E+00 3.27E+01 pCi/kg SS-4 Gamma Spectrum Sample Type Lab ID Collection Date Radion~clide Result Uncertainty MDC Units Sediment 651487001 1/9/2024 Cesium-134 1.02E+01 1.20E+0l 4.33E+01 pCi/kg Sediment 651487001 1/9/2024 Cesium-137 7.86E+00 1.21E+01 4.36E+01 pCi/kg Sediment 675354001 7/9/2024 Cesium-134 6.06E+01 1.92E+01 7.35E+0l pCi/kg Sediment 675354001 7/9/2024 Cesium-137 2.88E+0l 1.64E+01 6.26E+01 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 124 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant F-1 Semiannual Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Catfish 700139001 12/10/2024 Cesium-134 5.35E-01 1.81E+OO 5.89E+OO pCi/kg Catfish 700139001 12/10/2024 Cesium-137 1.99E+OO 1.67E+OO 5.85E+OO pCi/kg Catfish 700139001 12/10/2024 Cobalt-58

-2.87E+OO 2.00E+OO 5.62E+OO pCi/kg Catfish 700139001 12/10/2024 Cobalt-SO 1.02E+OO 1.89E+OO 6.51E+OO pCi/kg Catfish 700139001 12/10/2024 lron-59

-6.47E+OO 5.61E+OO 1.47E+01 pCi/kg Catfish 700139001 12/10/2024 Manganese-54 1.22E+OO 2.18E+OO 7.16E+OO pCi/kg Catfish 700139001 12/10/2024 Zinc-65

-2.57E+OO 4.79E+OO 1.54E+01 pCi/kg Bass 700139002 12/10/2024 Cesium-134 1.16E-01 2.01E+OO 6.54E+OO pCi/kg Bass 700139002 12/10/2024 Cesium-137 8.64E-01 1.56E+OO 5.33E+OO pCi/kg Bass 700139002 12/10/2024 Cobalt-58 2.09E+OO 2.00E+OO

6.90E+OO pCi/kg Bass 700139002 12/10/2024 Cobalt-SO 2.84E+OO 2.0SE+OO 6.88E+OO pCi/kg Bass 700139002 12/10/2024 lron-59

-4.53E+OO 4.97E+OO 1.60E+01 pCi/kg Bass 700139002 12/10/2024 Manganese-54

-4.70E-01 1.82E+OO 5.77E+OO pCi/kg Bass 700139002 12/10/2024 Zinc-65 4.37E+OO 4.36E+OO 1.56E+01 pCi/kg F-2 Semiannual Gamma S12.ectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Catfish 700139003 12/10/2024 Cesium-134

-1.89E+OO 1.98E+OO 5.67E+OO pCi/kg Catfish 700139003 12/10/2024 Cesium-137

-2.83E-01 1.97E+OO 6.22E+OO pCi/kg Catfish 700139003 12/10/2024 Cobalt-58

-1.01E+OO 1.84E+OO 5.95E+OO pCi/kg Catfish 700139003 12/10/2024 Cobalt-60

-1.07E+OO 2.55E+OO 6.75E+OO pCi/kg Catfish 700139003 12/10/2024 lron-59 7.95E-01 5.82E+OO 1.92E+01 pCi/kg Catfish 700139003 12/10/2024 Manganese-54 2.06E-01 2.05E+OO 6.91E+OO pCi/kg Catfish 700139003 12/10/2024 Zinc-65 3.20E+OO 5.60E+OO 1.69E+01 pCi/kg Bass 700139004 12/10/2024 Cesium-134

-1.09E+OO 1.74E+OO 5.44E+OO pCi/kg Bass 700139004 12/10/2024 Cesium-137 2.SOE-01 1.55E+OO 5.12E+OO pCi/kg Bass 700139004 12/10/2024 Cobalt-58

-1.43E+OO 1.73E+OO 5.32E+OO pCi/kg Bass 700139004 12/10/2024 Cobalt-60

-1.65E+OO 1.62E+OO 5.0lE+OO pCi/kg Bass 700139004 12/10/2024 lron-59 4.53E-01 3.70E+OO 1.27E+01 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 125 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant F-2 Semiannual Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Bass 700139004 12/10/2024 Manganese-54 4.46E-01 1.66E+00 5.44E+00 pCi/kg Bass 700139004 12/10/2024 Zinc-65 1.34E+01 4.14E+00 1.17E+01 pCi/kg F-3 Annual Tritium Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Catfish 700139005 12/10/2024 Tritium 8.07E+00 1.27E+00 1.02E+0O pCi/g FP-1 Semiannual Gamma S_2_ectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Food Product 695660001 11/12/2024 Cesium-134

-3.37E+00 8.12E+00 2.50E+01 pCi/kg Food Product 695660001 11/12/2024 Cesium-137 1.32E+00 7.02E+00 2.36E+01 pCi/kg Food Product 695660001 11/12/2024 lodine-131 5.43E+O0 1.13E+01 3.64E+01 pCi/kg FP-2 Semiannual Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Food Product 671414001 6/11/2024 Cesium-134 1.99E+00 2.37E+00 8.08E+00 pCi/kg Food Product 671414001 6/11/2024 Cesium-137

-5.12E+00 2.13E+00 5.67E+00 pCi/kg Food Product 671414001 6/11/2024 lodine-131

-8.71E-01 2.72E+00 9.20E+00 pCi/kg BL-1 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 653795001 1/30/2024 Barium-140 6.79E+00 3.46E+01 1.18E+02 pCi/kg Broad Leaf-Grasses 653795001 1/30/2024 Cesium-134 6.08E+O0 9.29E+00 3.18E+01 pCi/kg Broad Leaf-Grasses 653795001 1/30/2024 Cesium-137 1.38E+01 8.06E+00 2.95E+01 pCi/kg Broad Leaf-Grasses 653795001 1/30/2024 lodine-131

-6.58E+00 9.87E+00 3.10E+01 pCi/kg Broad Leaf-Grasses 653795001 1/30/2024 Lanthanum-140

-4.48E+00 1.13E+01 3.00E+01 pCi/kg Broad Leaf-Grasses 656982001 2/27/2024 Barium-140 4.91E+00 4.34E+01 1.16E+02 pCi/kg Broad Leaf-Grasses 656982001 2/27/2024 cesium-134

-1.45E+00 9.16E+00 2.94E+01 pCi/kg Broad Leaf-Grasses 656982001 2/27/2024 Cesium-137 6.88E+00 7.62E+00 2.60E+01 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 i Page 126 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant BL-1 Gamma Spectrum Sample Type Lab ID

Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 656982001 2/27/2024 lodine-131 1.91E+01 1.19E+01 4.24E+01 pCi/kg Broad Leaf-Grasses 656982001 2/27/2024 Lanthanum-140 1.14E+01 1.04E+01 3.74E+01 pCi/kg Broad Leaf-Grasses 660475001 3/26/2024 Barium-140

-1.22E+01 2.08E+01 6.79E+01 pCi/kg Broad Leaf-Grasses 660475001 3/26/2024 Cesium-134

-1.20E+00 5.03E+00 1.62E+01 pCi/kg Broad Leaf-Grasses 660475001 3/26/2024 Cesium-137

-1.13E+00 4.l0E+00 1.34E+01 pCi/kg Broad Leaf-Grasses 660475001 3/26/2024 lodine-131 3.91E+00 7.59E+00 2.49E+01 pCi/kg Broad Leaf-Grasses 660475001 3/26/2024 Lanthanum-140 2.02E+01 1.10E+01 2.99E+01 pCi/kg Broad Leaf-Grasses 665731001 4/30/2024 Barium-140 3.56E+00 3.16E+0l 1.06E+02 pCi/kg Broad Leaf-Grasses 665731001 4/30/2024 Cesium-134

-3.42E+00 7.08E+00 2.20E+01 pCi/kg Broad Leaf-Grasses 665731001 4/30/2024 Cesium-137 2.43E+00 6.88E+00 2.30E+0l pCi/kg Broad Leaf-Grasses 665731001 4/30/2024 lodine-131

-3.69E+00 1.13E+01 3.80E+01 pCi/kg Broad Leaf-Grasses 665731001 4/30/2024 Lanthanum-140

-5.59E+00 1.09E+01 3.36E+0l pCi/kg Broad Leaf-Grasses 669527001 5/28/2024 Barium-140

-1.30E+01 3.27E+01 9.14E+01 pCi/kg Broad Leaf-Grasses 669527001 5/28/2024 Cesium-134

-3.53E-01 7.40E+00 2.S0E+0l pCi/kg Broad Leaf-Grasses 669527001 5/28/2024 Cesium-137 1.28E+0l 6.54E+00 2.40E+01 pCi/kg Broad Leaf-Grasses 669527001 5/28/2024 lodine-131 1.74E+0l 1.21E+01 4.32E+01 pCi/kg Broad Leaf-Grasses 669527001 5/28/2024 Lanthanum-140 1.19E+01 1.07E+01 4.04E+01 pCi/kg Broad Leaf-Grasses 673260001 6/25/2024 Barium-140 1.57E+0l 2.0SE+0l 7.02E+01 pCi/kg Broad Leaf-Grasses 673260001 6/25/2024 Cesium-134 8.57E+00 4.83E+00 1.67E+01 pCi/kg Broad Leaf-Grasses 673260001 6/25/2024 Cesium-137 3.35E+00 4.28E+00 1.44E+01 pCi/kg Broad Leaf-Grasses 673260001 6/25/2024 lodine-131 5.25E+00 7.87E+00 2.49E+01 pCi/ kg Broad Leaf-Grasses 673260001 6/25/2024 Lanthanum-140 5.93E+00 6.62E+00 2.30E+01 pCi/kg Broad Leaf-Grasses 678786001 7/30/2024 Barium-140

-5.18E+00 3.52E+01 1.14E+02 pCi/kg Broad Leaf-Grasses 678786001 7/30/2024 Cesium-134 1.13E+01 5.60E+00 2.02E+0l pCi/kg Broad Leaf-Grasses 678786001 7/30/2024 Cesium-137 1.40E+01 1.45E+01 1.63E+01 pCi/kg Broad Leaf-Grasses 678786001 7/30/2024 lodine-131 7.47E+00 1.39E+0l 4.70E+01 pCi/kg Broad Leaf-Grasses 678786001 7/30/2024 Lanthanum-140

-2.67E+00 1.24E+01 4.12E+01 pCi/kg Broad Leaf-Grasses 683326001 8/27/2024 Barium-140 9.18E+0l 6.62E+0l 2.27E+02 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 127 of 138 Company: Vistra Corp Comanche Peak Nuclear Power Plant BL-1 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 683326001 8/27/2024 Cesium-134 9.28E+00 1.15E+01 3.40E+01 pCi/kg Broad Leaf-Grasses 683326001 8/27/2024 Cesium-137 1.16E+0l 1.05E+01 3.53E+0l pCi/kg Broad Leaf-Grasses 683326001 8/27/2024 lodine-131

-4.26E+01 2.87E+01 9.35E+01 pCi/kg Broad Leaf-Grasses 683326001 8/27/2024 Lanthanum-140 1.76E+01 2.48E+01 8.35E+01 pCi/kg Broad Leaf-Grasses 687541001

. 9/24/2024 Barium-140

-1.46E+00 4.19E+0l 1.19E+02 pCi/kg Broad Leaf-Grasses 687541001 9/24/2024 Cesium-134 1.37E+01 7.87E+00 2.62E+01 pCi/kg Broad Leaf-Grasses 687541001 9/24/2024 Cesium-137

-2.93E+01 1.19E+01 3.15E+0l pCi/kg Broad Leaf-Grasses 687541001 9/24/2024 Iodine-131

-2.59E+01 1.46E+01 4.48E+01 pCi/kg Broad Leaf-Grasses 687541001 9/24/2024 Lanthanum-140

-2.78E+00 1.19E+01 3.78E+Ol pCi/kg Broad Leaf-Grasses 693021001 10/29/2024 Barium-140

-4.25E+01 1.03E+02 1.64E+02 pCi/kg Broad Leaf-Grasses 693021001 10/29/2024 Cesium-134 8.87E+00 1.04E+01 3.62E+01 pCi/kg Broad Leaf-Grasses 693021001 10/29/2024 Cesium-137

-9.82E+00 9.99E+00 3.04E+0l pCi/kg Broad Leaf-Grasses 693021001 10/29/2024 lodine-131 1.46E+0l 1.89E+0l 5.86E+01 pCi/kg Broad Leaf-Grasses 693021001 10/29/2024 Lanthanum-140

-4.43E+00 1.82E+01 5.99E+01 pCi/kg Broad Leaf-Grasses 698141001 11/26/2024 Barium-140 2.19E+0l 4.00E+0l 1.35E+02 pCi/kg Broad Leaf-Grasses 698141001 11/26/2024 Cesium-134 1.23E+01 9.89E+00 3.36E+01 pCi/kg Broad Leaf-Grasses 698141001 11/26/2024 Cesium-137 3.59E+00 9.05E+00 3.01E+01 pCi/kg Broad Leaf-Grasses 698141001 11/26/2024 lodine-131 3.42E+01 3.45E+01 4.57E+01 pCi/kg Broad Leaf-Grasses 698141001 11/26/2024 Lanthanum-140

-1.12E+01 1.33E+01 4.07E+0l pCi/kg Broad Leaf-Grasses 703331001 12/31/2024 Barium-140 3.17E+01 3.03E+0l 1.03E+02 pCi/kg Broad Leaf-Grasses 703331001 12/31/2024 Cesium-134 6.0lE+00 4.59E+0O 1.55E+01 pCi/kg Broad Leaf-Grasses 703331001 12/31/2024 Cesium-137 2.31E+01 9.22E+0O 1.46E+01 pCi/kg Broad Leaf-Grasses 703331001 12/31/2024 lodine-131

-1.22E+0l 1.46E+01 4.83E+01 pCi/kg Broad Leaf-Grasses 703331001 12/31/2024 Lanthanum-140

-9.62E+00 9.S0E+0O 2.94E+01 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 128 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant BL-2 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 653795003 1/30/2024 Barium-140 3.15E+01 2.20E+01 7.87E+01 pCi/kg Broad Leaf-Grasses 653795003 1/30/2024 Cesium-134 1.26E+00 6.51E+00 2.13E+01 pCi/kg Broad Leaf-Grasses 653795003 1/30/2024 Cesium-137 4.33E+00 5.97E+00 2.04E+01 pCi/kg Broad Leaf-Grasses 653795003 1/30/2024 lodine-131

-3.0SE-01 6.80E+00 2.31E+0l pCi/kg Broad Leaf-Grasses 653795003 1/30/2024 Lanthanum-140

-1.44E+01 7.96E+00 1.38E+0l pCi/kg Broad Leaf-Grasses 656982003 2/27/2024 Barium-140 2.39E+01 2.24E+01 7.05E+0l pCi/kg Broad Leaf-Grasses 656982003 2/27/2024 Cesium-134

-4.85E+00 5.14E+00 1.55E+01 pCi/kg Broad Leaf-Grasses 656982003 2/27/2024 Cesium-137

-9.19E+00 4.98E+00 1.45E+01 pCi/kg Broad Leaf-Grasses 656982003 2/27/2024 lodine-131 1.39E+01 7.13E+00 2.57E+01 pCi/kg Broad Leaf-Grasses 656982003 2/27/2024 Lanthanum-140 7.94E+00 7.80E+00 2.52E+0l pCi/kg Broad Leaf-Grasses 660475003 3/26/2024 Barium-140

-7.64E+00 2.54E+0l 8.44E+01 pCi/kg Broad Leaf-Grasses 660475003 3/26/2024 Cesium-134

-6.48E+00 6.62E+00 2.06E+01 pCi/kg Broad Leaf-Grasses 660475003 3/26/2024 Cesium-137 2.19E+01 5.85E+00 2.31E+0l pCi/kg Broad Leaf-Grasses 660475003 3/26/2024 lodine-131 2.06E+01 8.26E+0O 2.99E+01 pCi/kg Broad Leaf-Grasses 660475003 3/26/2024 Lanthanum-140 5.71E+00 8.18E+00 2.92E+01 pCi/kg Broad Leaf-Grasses 665731003 4/30/2024 Barium-140 2.43E+0l 2.11E+0l 7.41E+0l pCi/kg Broad Leaf-Grasses 665731003 4/30/2024 Cesium-134

-1.05E+00 4.50E+00 1.42E+0l pCi/kg Broad Leaf-Grasses 665731003 4/30/2024 Cesium-137 7.02E+00 4.28E+00 1.55E+01 pCi/kg Broad Leaf-Grasses 665731003 4/30/2024 lodine-131 4.49E+00 5.96E+00 2.09E+01 pCi/kg Broad Leaf-Grasses 665731003 4/30/2024 Lanthanum-140

-2.75E-02 6.72E+00 2.22E+01 pCi/kg Broad Leaf-Grasses 669527003 5/28/2024 Barium-140 1.06E+00 3.44E+01 1.03E+02 pCi/kg Broad Leaf-Grasses 669527003 5/28/2024 Cesium-134

-8.64E+00 7.0lE+00 2.06E+01 pCi/kg Broad Leaf-Grasses 669527003 5/28/2024 Cesium-137

-4.95E+00 5.60E+00 1.72E+01 pCi/kg Broad Leaf-Grasses 669527003 5/28/2024 lodine-131 6.24E+00 9.83E+00 3.45E+01 pCi/kg Broad Leaf-Grasses 669527003 5/28/2024 Lanthanum-140

-8.90E+00 1.06E+0l 3.13E+01 pCi/kg Broad Leaf-Grasses 673260003 6/25/2024 Barium-140 1.25E+01 1.63E+01 5.47E+01 pCi/kg Broad Leaf-Grasses 673260003 6/25/2024 Cesium-134 1.20E+00 3.62E+00 1.17E+01 pCi/kg Broad Leaf-Grasses 673260003 6/25/2024

Cesium-137

-1.34E+01 6.44E+00 9.94E+00 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 129 of 138 Company: Vistra Corp J Comanche Peak Nuclear Power Plant BL-2 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 673260003 6/25/2024 lodine-131

-2.58E+O0 5.33E+00 1.77E+01 pCi/kg Broad Leaf-Grasses 673260003 6/25/2024 Lanthanum-140

-4.47E+00 4.98E+00 1.50E+01 pCi/kg Broad Leaf-Grasses 678786003 7/30/2024 Barium-140 3.44E+01 3.31E+01 9.91E+01 pCi/kg Broad Leaf-Grasses 678786003 7/30/2024 Cesium-134

-1.24E+00 5.08E+00 1.68E+01 pCi/kg Broad Leaf-Grasses 678786003 7/30/2024 Cesium-137 2.52E+00 4.49E+00 1.55E+01 pCi/kg Broad Leaf-Grasses 678786003 7/30/2024 Iodine-131

-1.08E+01 1.23E+01 3.92E+01 pCi/kg Broad Leaf-Grasses 678786003 7/30/2024 Lanthanum-140

-8.26E+00 1.05E+01 3.33E+01 pCi/kg Broad Leaf-Grasses 683326003 8/27/2024 Barium-140 6.40E+00 5.38E+01 1.72E+02 pCi/kg Broad Leaf-Grasses 683326003 8/27/2024 Cesium-134

-1.79E+00 8.15E+00 2.70E+01 pCi/kg Broad Leaf-Grasses 683326003 8/27/2024 Cesium-137 1.36E+01 7.97E+00 2.81E+01 pCi/kg Broad Leaf-Grasses 683326003 8/27/2024 lodine-131 2.09E+01 2.67E+01 8.01E+01 pCi/kg Broad Leaf-Grasses 683326003 8/27/2024 Lanthanum-140 1.10E+01 1.78E+01 6.12E+01 pCi/kg Broad Leaf-Grasses 687541003 9/24/2024 Barium-140 2.65E+01 2.63E+01 8.80E+D1 pCi/kg Broad Leaf-Grasses 687541003 9/24/2024 Cesium-134

-1.63E+0l 9.65E+00 1.77E+01 pCi/kg Broad Leaf-Grasses 687541003 9/24/2024 Cesium-137 8.55E+00 6.19E+00 1.99E+01 pCi/kg Broad Leaf-Grasses 687541003 9/24/2024 lodine-131 6.25E+00 1.03E+0l 3.45E+01 pCi/kg Broad Leaf-Grasses 687541003 9/24/2024 Lanthanum-140

-1.17E+01 8.46E+00 2.48E+01 pCi/kg Broad Leaf-Grasses 693021003 10/29/2024 Barium-140

-8.19E+01 4.95E+01 1.54E+02 pCi/kg Broad Leaf-Grasses 693021003 10/29/2024 Cesium-134 8.79E+00 9.38E+00 2.79E+01 pCi/kg Broad Leaf-Grasses 693021003 10/29/2024 Cesium-137 6.41E+00 7.88E+0O 2.62E+01 pCi/kg Broad Leaf-Grasses 693021003 10/29/2024 lodine-131

-8.47E+00 2.02E+01 6.43E+01 pCi/kg Broad Leaf-Grasses 693021003 10/29/2024 Lanthanum-140

-3.36E+01 1.76E+0l 5.02E+01 pCi/kg Broad Leaf-Grasses 698141003 11/26/2024 Barium-140 1.53E+01 3.35E+01 1.11E+02 pCi/kg Broad Leaf-Grasses 698141003 11/26/2024 Cesium-134

-7.27E+00 8.33E+00 2.39E+01 pCi/kg Broad Leaf-Grasses 698141003 11/26/2024 Cesium-137 4.98E+00 8.09E+00 2.67E+01 pCi/kg Broad Leaf-Grasses 698141003 11/26/2024 lodine-131

-1.50E+01 2.13E+01 4.11E+0l pCi/kg Broad Leaf-Grasses 698141003

11/26/2024 Lanthanurri-140

-5.05E+01 2.52E+01 3.89E+01 pCi/kg Broad Leaf-Grasses 703331003 12/31/2024 Barium-140 6.B0E+00 3.01E+01 9.98E+01 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 130 of 138 Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant BL-2 Gamma Spectrum Sample Type lab ID Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 703331003 12/31/2024 Cesium-134 5.33E+00 4.86E+00 1.62E+01 pCi/kg Broad Leaf-Grasses 703331003 12/31/2024 Cesium-137 3.29E+00 4.61E+00 1.53E+Ol pCi/kg Broad Leaf-Grasses 703331003 12/31/2024 lodine-131 1.19E+Ol 1.29E+01 4.43E+0l pCi/kg Broad Leaf-Grasses 703331003 12/31/2024 Lanthanum-140

-7.64E+00 1.03E+01 2.74E+0l pCi/kg BL-3 Gamma Spectrum Sample Type lab ID Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 653795002 1/30/2024 Barium-140

-1.48E+0l 2.27E+01 7.19E+0l pCi/kg Broad Leaf-Grasses 653795002 1/30/2024 Cesium-134 4.87E+O0 5.86E+00 2.01E+0l pCi/kg Broad Leaf-Grasses 653795002 1/30/2024 Cesium-137 1.54E+00 5.75E+00 1.90E+01 pCi/kg Broad Leaf-Grasses 653795002 1/30/2024 lodine-131 1.75E+00 7.14E+00 2.43E+01 pCi/kg Broad Leaf-Grasses 653795002 1/30/2024 Lanthanum-140 1.21E+0l 9.60E+00 2.89E+0l pCi/kg Broad Leaf-Grasses 656982002 2/27/2024 Barium-140

-4.97E+00 2.87E+01 9.06E+0l pCi/ kg Broad Leaf-Grasses 656982002 2/27/2024 Cesium-134 3.37E+00 6.06E+00 2.09E+01 pCi/kg Broad Leaf-Grasses 656982002 2/27/2024 Cesium-137 7.31E+00 6.28E+00 2.23E+01 pCi/kg Broad Leaf-Grasses 656982002 2/27/2024 lodine-131 6.76E+00 1.03E+01 3.42E+01 pCi/kg

Broad Leaf-Grasses 656982002 2/27/2024 Lanthanum-140 4.93E+00 8.75E+00 2.96E+01... __ pfi~k.L_

Broad Leaf-Grasses 660475002 3/26/2024 Barium-140

-2.91E+01 4.00E+01 1.10E+02 pCi/kg Broad Leaf-Grasses 660475002 3/26/2024 Cesium-134 9.45E+00 7.73E+00 2.25E+01 pCi/kg Broad Leaf-Grasses 660475002 3/26/2024 Cesium-137

-9.57E+00 6.62E+00 1.92E+01 pCi/ kg Broad Leaf-Grasses 660475002 3/26/2024 lodine-131

-4.38E-01 1.23E+01 4.08E+01 pCi/ kg Broad Leaf-Grasses 660475002 3/26/2024 Lanthanum-140

-3.32E-01 1.12E+0l 3.58E+01 pCi/ kg Broad Leaf-Grasses 665731002 4/30/2024 Barium-140 2.03E+01 2.79E+01 8.68E+0l pCi/kg Broad Leaf-Grasses 665731002 4/30/2024 Cesium-134 2.22E+00 6.55E+00 2.15E+01 pCi/kg Broad Leaf-Grasses 665731002 4/30/2024 Cesium-137

-1.33E+01 8.34E+00 1.81E+0l pCi/kg Broad Leaf-Grasses 665731002 4/30/2024 lodine-131 4.54E+0l 1.96E+01 2.92E+0l pCi/kg Broad Leaf-Grasses 665731002 4/30/2024 Lanthanum-140

-3.95E+00 9.87E+00 3.llE+0l pCi/kg Broad Leaf-Grasses 669527002 5/28/2024 Barium-140

-9.95E+00 2.47E+01 7.70E+0l pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 131 of 138 Company: Vistra Corp I

Comanche Peak Nuclear Power Plant BL-3 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 669527002 5/28/2024 Cesium-134

-1.76E+0O 5.65E+00 1.73E+0l pCi/kg Broad Leaf-Grasses 669527002 5/28/2024 Cesium-137 1.41E+01 1.01E+01 1.60E+01 pCi/kg Broad Leaf-Grasses 669527002 5/28/2024 Iodine-131 4.89E+00 8.72E+00 2.90E+01 pCi/kg Broad Leaf-Grasses 669527002 5/28/2024 Lanthanum-140

-1.99E+01 7.45E+00 1.42E+01 pCi/kg Broad Leaf-Grasses 673260002 6/25/2024 Barium-140

-9.45E+0l 5.09E+01 9.34E+01 pCi/kg Broad Leaf-Grasses 673260002 6/25/2024 Cesium-134 9.91E+00 6.53E+00 2.33E+01 pCi/kg Broad Leaf-Grasses 673260002 6/25/2024 Cesium-137 7.57E+O0 6.44E+00 2.16E+01 pCi/kg Broad Leaf-Grasses 673260002 6/25/2024 lodine-131

-1.05E+01 1.08E+01 3.55E+01 pCi/kg Broad Leaf-Grasses 673260002 6/25/2024 Lanthanum-140

-5.42E+00 1.03E+01 3.33E+01 pCi/kg Broad Leaf-Grasses 678786002 7/30/2024 Barium-140 2.08E+02 9.09E+01 1.58E+02 pCi/kg Broad Leaf-Grasses 678786002 7/30/2024 Cesium-134 5.98E+00 1.08E+01 2.68E+01 pCi/kg Broad Leaf-Grasses 678786002 7/30/2024 Cesium-137 9.67E+00 9.45E+00 2.30E+01 pCi/kg Broad Leaf-Grasses 678786002 7/30/2024 lodine-131

-2.21E+01 1.86E+01 6.06E+01 pCi/kg Broad Leaf-Grasses 678786002 7/30/2024 Lanthanum-140

-2.90E+01 1.96E+01 5.20E+01 pCi/kg Broad Leaf-Grasses 683326002 8/27/2024 Barium-140

-7.91E+0l 8.48E+01 1.91E+02 pCi/kg Broad Leaf-Grasses 683326002 8/27/2024 Cesium-134

-2.00E+00 9.51E+00 3.03E+01 pCi/kg Broad Leaf-Grasses 68-3326002 8/27/2024 Cesium-137 1.76E+01 9.17E+00 3.15E+0l pCi/kg Broad Leaf-Grasses 683326002 8/27/2024 lodine-131 2.99E+01 2.59E+01 8.94E+01 pCi/kg Broad Leaf-Grasses 683326002 8/27/2024 Lanthanum-140

-7.44E+00 2.09E+01 6.72E+0l pCi/kg Broad Leaf-Grasses 687541002 9/24/2024 Barium-140 9.12E+01 4.13E+01 8.94E+01 pCi/kg Broad Leaf-Grasses 687541002 9/24/2024 Cesium-134 7.47E+00 6.15E+00 2.11E+01 pCi/kg Broad Leaf-Grasses 687541002 9/24/2024 Cesium-137

-5.24E+00 6.46E+00 2.01E+01 pCi/kg Broad Leaf-Grasses 687541002 9/24/2024 lodine-131

-4.74E+00 8.34E+00 2.75E+01 pCi/kg Broad Leaf-Grasses 687541002 9/24/2024 Lanthanum-140 9.38E-01 1.07E+01 3.49E+01 pCi/kg Broad Leaf-Grasses 693021002 10/29/2024 Barium-140 6.84E+01 4.96E+01 1.72E+02 pCi/kg Broad Leaf-Grasses 693021002 10/29/2024 Cesium-134 3.67E+00 1.08E+01 3.52E+01 pCi/kg Broad Leaf-Grasses 693021002 10/29/2024 Cesium-137 1.99E+01 1.05E+01 3.66E+01 pCi/kg Broad Leaf-Grasses 693021002 10/29/2024 lodine-131

-9.42E+00 1.63E+01 5.38E+01 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 132 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant BL-3 Gamma Spectrum Sample Type Lab ID Collection Date Radionuclide Result Uncertainty MDC Units Broad Leaf-Grasses 693021002 10/29/2024 Lanthanum-140

-1.26E+0l 1.89E+01 5,79E+01 pCi/kg Broad Leaf-Grasses 698141002 11/26/2024 Barium-140

-1.05E+02 7.67E+01 1.77E+02 pCi/kg Broad Leaf-Grasses 698141002 11/26/2024 Cesium-134 8.56E+00 1.31E+01 4.30E+01 pCi/kg Broad Leaf-Grasses 698141002 11/26/2024 Cesium-137 1.03E+01 1.23E+01 4.12E+01 pCi/kg Broad Leaf-Grasses 698141002 11/26/2024 lodine-131 7.79E+00 1.63E+01 5.61E+01 pCi/kg Broad Leaf-Grasses 698141002 11/26/2024 Lanthanum-140 4.l0E+00 2.13E+01 6.11E+01 pCi/kg Broad Leaf-Grasses 703331002 12/31/2024 Barium-140 3.22E+01 4.58E+01 1.52E+02 pCi/kg Broad Leaf-Grasses 703331002 12/31/2024 Cesium-134 9.63E,..00 6.12E+00 2.16E+01 pCi/kg Broad Leaf-Grasses 703331002 12/31/2024 Cesium-137 3.42E,..00 6.30E+00 2.0SE+0l pCi/kg Broad Leaf-Grasses 703331002 12/31/2024 lodine-131 1.13E+01 2.06E+01 6.97E,..01 pCi/kg Broad Leaf-Grasses 703331002 12/31/2024 La nthanum-140

-4.09E,..00 1.43E+01 4.76E+01 pCi/kg

Annual Environmental Operating Report I YEAR: 2024 I Page 133 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant, Cross Check lntercomparison Program Participation in cross check intercomparison studies is mandatory for laboratories performing analyses of REMP samples satisfying the requirements in the Offsite Site Dose Calculation Manual. lntercomparison studies provide a consistent and effective means to evaluate the accuracy and precision of analyses performed by a laboratory.

Study results should fall within specified control limits and results that fall outside the control limits are investigated and corrected.

Gel Laboratories participated in the following proficiency testing studies provided by Environmental Resource Associates (ERA), and Eckert Ziegler Analytics in 2024.

The Laboratory's intercomparison program results for 3 are summarized below.

Vendor supplied data is listed in Cross Check lntercomparison Results Table below.

Gel Laboratories addressed all the not acceptable Performance Evaluation by initiating investigations and Corrective Action teams. The corrective action teams consisted of representatives from the affected laboratories. The sample preparation and analytical processes were reviewed. This included review of reagents and standards used in the sample preparation steps, calibration records, process control samples, and interviews with the analysts.

The investigations determined that the laboratory met all quality control criteria specified in each respective method. Additionally, all internal procedures and policies were performed as required. These failures were tracked through GEL's internal non-conformance system.

Cross Check lntercomparison Results Radionuclide/Standard Units Reported Assigned Acceptance Performance Value Value Limits Evaluation Air Filler Cesium-134 pCi 262 273 177-335 Acceptable Ceslurn-137 pCi 120 106 87.1-139 Acceptable Cesium-134 Bq 1.54 1.6 1.12-2.08 Acceptable Cesium-137 Bq 0.0177 False pos. test Acceptable Ceslum-134 pCi 571 581 377 - 712 Acceptable Cesium-137 pCi 912 848 696

1110 Acceptable Air Filter Gross Alpha/Beta Gross Alpha pCi 112 95.9 50.1-158 Acceptable Gross Beta pCI 33.7 22.2 13.5-33.5 Not Acceptable Gross Alpha Bq 0.463 0.225 0.077-0.434 Not Acceptable Gross Beta Bq 1.45 1.49 0.75-2.24 Acceptable Gross Alpha pCI 83.9 72.4 37.8-119 Acceptable Gross Beta pCi 62.4 47.9 29.0 - 72.4 Acceptable Water Ceslum-134 pCI/L 31.2 28 16.0- 40.0 Acceptable Cesium-137 pCI/L 52.8 47.7 24.5-70.9 Acceptable

Annual Environmental Operating Report I YEAR: 2024 J Page 134 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Cross Check lntercomparison Results Radionuclide/Standard Units Reported Assigned Acceptance Performance Value Value Limits Evaluation Cobalt-60 pCi/L 96.7 84 66.4

102 Acceptable lodine-131 pCi/L 16.1 26.3 22.7-29.9 Not Acceptable Zlnc-65 pCi/L 322 284 228

340 Acceptable Ceslum-134 pCi/L 402 415 313-456 Acceptable Cesium-137 pCi/L 2400 2310 1980-2630 Acceptable Cobalt-60 pCi/L 1570 1500 1290-1720 Acceptable Manganese54 pCi/L

<10.2

<71.0 0.00-71.0 Acceptable Zinc-65 pCi/L 567 503 448-635 Acceptable lodine-131 pCi/L 20.4 25.1 21.7-28.5 Not Acceptable Ceslum-134 pCi/L 14.6 18.9 7.81-30.0 Acceptable Cesium-137 pCi/L 66.8 57 32.9-81.1 Acceptable Cobalt-60 pCi/L 79.5 76.8 59.9-93.7 Acceptable lodine-131 pCi/L 23.5 27.9 24.2-31.6 Not Acceptable Zinc-65 pCi/L 327 312 253-371 Acceptable Cesium-134 pGi/L 2060 2190 1650-2410 Acceptable Cesium-137 pCi/L 1570 1550 1330 -1760 Acceptable Cobalt-60 pCi/L 1120 1050 906

1200 Acceptable Manganese54 pCI/L

<11.3

<71.0

<71.0 Acceptable Zlnc-65 pCi/L 556 526 468

664 Acceptable lodine-131 pCi/L 25.8 26.3 22.7-29.0 Acceptable Cesium-134 pCi/L 2.32E+00 2.42E+02 0.96 Acceptable Cesiurn-137 pCi/L 2.26E+00 2.29E+02 0.99 Acceptable Cobalt-58 pCi/L

-2.80E-NA NA Acceptable Cobalt-60 pCi/L 4.10E+00 3.91E+02 1.05 Acceptable lodlne-131 pCi/L 2.40E+00 1.85E+01 1.29 Acceptable lron-59 pCi/L 2.09E+00 1.74E+02 1.2 Acceptable Manganese54 pCi/L 2.22E+00 2.04E+02 1.09 Acceptable Zinc-65 pCi/L 1.21 E+00 9.91E+01 1.22 Acceptable Ceslum-134 pCi/L 1.72E+00 1.93E+02 0.89 Acceptable Cesiurn-137 pCi/L 1.33E+00 1.32E+02 1.01 Acceptable Cobalt-58 pCi/L 1.58E+00 1.54E+02 1.02 Acceptable Cobalt-60 pCi/L 2.48E+00 2.43E+02 1.02 Acceptable lodine-131 pCi/L 1.01 E+00 9.39E+01 1.08 Acceptable lron-59 pCI/L 1.32E+00 1.14E+02 1.13 Acceptable Manganese54 pCi/L 1.84E+00 1.67E+02 1.1 Acceptable Zinc-65 pCi/L 3.25E+00 2.84E+02 1.14 Acceptable Cesium-134 pCI/L 1.37E+00 1.45E+02 0.94 Acceptable Cesium-137 pCi/L 1.07E+00 1.81E+02 1.03 Acceptable Cobalt-58

pCi/L 1.32E+00 1.23E+02 1.07 Acceptable Cobalt-60 pCi/L 3.01E+00 2.75E+02 1.09 Acceptable lodine-131 pCi/L 6.63E+00 6.73E+01 0.99 Acceptable lron-59 pCi/L 1.57E+00 1.34E+02 1.17 Acceptable

Annual Environmental Operating Report I YEAR: 2024 I Page 135 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Cross Check lntercomparison Results Radionuclide/Standard Units Reported Assigned Acceptance Performance Value Value Limits Evaluation Manganese54 pCI/L 1.49E+OO 1.30E+02 1.14 Acceptable Zinc-65 pCI/L 2.41E+OO 1.95E+02 1.24 Acceptable Cesium-134 Bq/L 10.1 11.3 7.9-14.7 Acceptable Cesium-137 Bq/L 9.09 8.7 6.1-11.3 Acceptable Cobalt-60 Bq/L 0.0227 False pos.

Acceptable Manganese54 Bq/L 13.1 12.7 8.9-16.5 Acceptable Zinc-65 Bq/L 21.1 19.1 13.4-24.8 Acceptable Cesium-134 Bq/L False Pos. Test Acceptable Ceslum-137 Bq/L 10.6 9.7 6.8-12.6 Acceptable Cobalt-60 Bq/L 10.5 10.27 7.19-13.35 Acceptable Manganese54 Bq/L 7.87 7.36 5.15-9.57 Acceptable Zinc-65 Bq/L

-0.079 False Pos. Test Acceptable Cesium-134 Bq/L 19.5 22.3 15.6-29.0 Acceptable Cesium-137 Bq/L

-0.0164 False Pos. Test Acceptable Cobalt-60 Bq/L 15.1 15 10.5-19.5 Acceptable lron-59 Bq/L 62.4 57.5 40.3-74.8 Acceptable Manganese54 Bq/L 0.0424 False Pos. Test Acceptable Zlnc-65 Bq/L 24.5 22.8 16.0-29.6 Acceptable Water Gross Alpha/Beta Gross Alpha pCi/L 32.6 35.2 25.7 - 44.7 Acceptable Gross Beta pCi/L 44 55.5 41.1-69.9 Acceptable Gross Alpha pCi/L 144 168 61.3-232 Acceptable Gross Beta pCi/L 180 175 87.5-241 Acceptable Gross Alpha pCi/L 11.4 13 7.94-18.1 Acceptable Gross Alpha pCi/L 11.1 13 7.94-18.2 Acceptable Gross Beta pCi/L 19.7 20.6 13.2-28.0 Acceptable Gross Alpha pCi/L 33.9 52.1 19.0- 71.8 Acceptable Gross Beta pCi/L 51.5 51.7 25.8-71.1 Acceptable Gross Alpha Bq/L 1.44 1.59 0.48-2.70 Acceptable Gross Beta Bq/L 15.8 16.27 8.14-24.41 Acceptable Gross Alpha Bq/L 0.897 1.01 0.30-1.72 Acceptable Gross Beta Bq/L 5.01 5.57 2.79-8.36 Acceptable Gross Alpha Bq/L 1.07 1.29 0.39-2.19 Acceptable Gross Beta Bq/L 4.78 5.09 2.55-7.64 Acceptable Water Tritium Tritium pCi/L 9790 10300 8350 -12300 Acceptable Tritium pCI/L 12000 13100 9870-15900 Acceptable Tritium pCi/L 7470 7550 5870-9230 Acceptable Tritium pCi/L 7080 7550 5870-9230 Acceptabie Tritium pCI/L 16400 17600 13300 - 21400 Acceptable Hydrogen-3 Bq/L 5.01 False pos.

Acceptable Hydrogen-3 Bq/L 574 637 446-828 Acceptable

Annual Environmental Operating Report I YEAR: 2024 I Page 136 of 138 Company: Vistra Corp I Comanche Peak Nuclear Power Plant Cross Check lntercomparison Results Rad ion ucl ide/Standard Units Reported Assigned Acceptance Performance Value Value Limits Evaluation Hydrogen-3 Bq/L 350 374 262-486 Acceptable Soil Casium-134 pCi/kg 3530 3500 2390-4180 Acceptable Cesium-137 pCi/kg 10600 9150 6920-11600 Acceptable Cesium-134 pCi/kg 1800 1810 1240 - 2160 Acceptable Cesium-137 pCl/kg 1510 1370 1040 - 1730 Acceptable Cesium-134 Bq/Kg 634 693 485-901 Acceptable Cesium-137 Bq/Kg 2010 1810 1267-2353 Acceptable Cesium-134 Bq/Kg 371 404 293-525 Acceptable Cesium-137 Bq/Kg 1690 1550 1085-2015 Acceptable Cesium-134 Bq/Kg 375 417 292-542 Acceptable Cesium-137 Bq/Kg 1790 1650 155-2145 Acceptable Vegetation Cesium-134 pCi/kg 1220 1290 856-1720 Acceptable Cesium-137 pCi/kg 2440 2420 1860-3260 Acceptable Cesium-134 pCi/kg 2270 2460 1630 - 3270 Acceptable Cesium-137 pCl/kg 912 889 683-1200 Acceptable Cesium-134 Bq/smpl 4.65 4.98 3.49-6.47 Acceptable Cesium-137 Bq/smpl 0.0079 False pos.

Acceptable Cesium-134 Bq/smpl 3.28 3.67 2.57-4.77 Acceptable Cesium-137 Bq/smpl 2.82 2.57 1.80-3.34 Acceptable Cesium-134 Bq/smpl 2.67 2.89 2.02-3.76 Acceptable Cesium-137 Bq/smpl 1.93 1.91 1.34-2.48 Acceptable Charcoal Jodine-131 pCi 8.75E+00 9.13E+01 0.96 Acceptable lodine-131 pCi 9.71E+00 9.26E+01 1.05 Acceptable lodine-131 pCi 6.85E+00 6.50E+01 1.05 Acceptable

Annual Environmental Operating Re~ort I

YEAR: 2024 I Page J}7 of 138 Company: Vistra Corp 1 Comanche Peak Nuclear Power Plant, Environmental Direct Radiation Dosimetry Sample Results Quarterly Normallzed Quarterly Monitoring Data, Ma Quarterly Facility Dose, Fa=Ma-Ba Annual Annual Annual Monitoring

Baseline, Baseline, Monitoring Facility Location Ba (mrem)

(mrem)

BA Data, MA

Dose, (mrem) 1 2

3 4

1 2

4 (mrem)

(mrem)

FA=MA-BA 3

(mrem) 1 12.0 13 13 12 ND ND ND ND 45.5 ND 2

13.5 14 15 16 13 ND ND ND ND 50.4 49.5 ND 3

11.5 11 13 14 11 ND ND ND ND 45.3 44.5 ND 4

12.2 13 16 14 13 ND ND ND ND 46.3 44.5 ND 5

8.1 8

9 6

6 ND ND ND ND 29.0 25.5 ND 6

12.3 13 14 16 12 ND ND ND ND 47.8 51.5 ND 7

7.9 8

9 8

6 ND ND ND ND 27.9 20.5 ND 8

12.3 12 14 13 10 ND ND ND ND 46.8 43.5 ND 9

13.0 15 17 13 13 ND ND ND ND 49.5 52.5 ND 10 14.2 15 16 15 15 ND ND ND ND 55.6 51.5 ND 11 11.4 12 14 13 10 ND ND ND ND 41.9 40.5 ND 12 10.2 10 11 10 10 ND ND ND ND 38.9 34.5 ND 13 11.5 12 13 14 11 ND ND ND ND 42.9 42.5 ND 14 12.9 14 16 14 11 ND ND ND ND 48.9 49.5 ND 15 11.5 14 14 12 10 ND ND ND ND 43.2 42.5 ND 16 12.3 14 14 14 10 ND ND ND ND 45.0 48.5 ND 17 12.6 13 15 14 12 ND ND ND ND 45.5 48.5 ND 18 11.2 14 13 15 10 ND ND ND ND 41.9 40.5 ND 19 11.6 12 14 11 10 ND ND ND ND 44.4 45.5 ND 20 11.6 12 11 12 12 ND ND ND ND 43.6 45.5 ND 21 11.3 11 11 11 10 ND ND ND ND 42.7 42.5 ND 22 12.0 13 15 13 11 ND ND ND ND 44.9 48.5 ND 23 10.7 12 13 11 9

ND ND ND ND 40.2 38.5 ND 24 12.7 14 15 16 11 ND ND ND ND 47.8 48.5 ND 25 11.6 12 13 14 11 ND ND ND ND 44.2 48.5 ND

Annual Environmental Operating Report I YEAR: 2024 I Page 138 of 138

~~ompany: Vistra Corp I Comanche Peak Nuclear Power Plant, Environmental Direct Radiation Dosimetry Sample Results Quarterly Normalized Quarterly Monitoring Data, Ma Monitoring

Baseline, (mrem)

Location Ba (mrem) 1 2

3 4

26 11.7 14 10 10 12 27 11.5 12 14 13 11 28 10.5 11 11 11 9

29 11.7 13 14 12 10 30 12.2 12 15 14 12 31 11.4 13 12 12 11 32 12.9 15 16 14 33 10.2 12 13 9

10 34 10.3 11 11 11 9

35 10.5 12 12 12 11 36 11.8 13 13 12 10 37 12.2 14 14 10 38 11.4 13 12 12 10 39 11.1 12 13 12 10 40 12.6 14 16 15 14 41 10.9 12 13 8

10 42 7.4 8

8 6

6 43 13.4 15 17 13 14 MDDa = Quarterly Minimum Differential Dose = 5.96 mrem MDDA = Annual Minimum Differential Dose = 12.2 mrem ND = Not Detected, where MaS:(Ba+MDDa) or MA:s:(BA+MDDA)

Quarterly Facility Dose, Fa=Ma*Ba Annual (mrem)

Baseline, BA 1

2 3

4 (mrem)

ND ND ND ND 44.2 ND ND ND ND 44.2 ND ND ND ND 37.9 ND ND ND ND*

44.8 ND ND ND ND 46.0 ND ND ND ND 42.5 ND ND ND ND 48.7 ND ND ND ND 38.6 ND ND ND ND 37.5 ND ND ND ND 39.3 ND ND ND ND 46.6 ND ND ND ND 46.3 ND ND ND ND 42.5 ND ND ND ND 41.9 ND ND ND ND 46.8 ND ND ND ND 38.7 ND ND ND ND 27.2 ND ND ND ND 49.9 Annual Monitoring Data, MA (mrem) 38.5 48.5 32.5 43.5 46.5 39.5 36.5 37.5 45.5 42.5 39.5 44.5 33.5 19.5 51.5 Annual Facility

Dose, FA=MA-BA (mrem)

ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND

Appendix B Comanche Peak Nuclear Power Plant Land Use Census 2024 COMANCHE PEAK NUCLEAR POWER PLANT

LAND USE CENSUS 2024 The Land Use Census identified receptors within a five (5) mile radius of the plant in each of the sixteen (16) meteorological sectors. The Land Use Census was conducted June 3-6, 2024 and includes the following items:

I.

Evaluation of the 2024 Land Use Census

2.

Nearest Resident by Sector, Distance, X/Q and D/Q

3.

Nearest Garden by Sector, Distance and D/Q

4.

Nearest Milk Animal by Sector, Distance and D/Q

5.

Population by Sector and Distance

6.

Enviromnental Sample Locations Table

7.

Enviromnental Monitoring Locations Map - 2 Mile Radius

8.

5 Mile Sector and Road Map with Field Data*

9.

Environmental Monitoring Locations Map - all sample locations*

These maps are vaulted along with this census. Copies of this census will not contain a copy of these maps unless specifically requested.

Evaluation of the 2024 Land Use Census The results of the 2024 Land Use Census were reviewed for impact on the Radiological Environmental Monitoring Program (REMP). The specific areas reviewed, that could be affected by changes found in the land use census, were the sampling requirements for milk, broadleaf vegetation and food products.

Reviewing the milk sampling requirements from the ODCM Table 3.12-1 requires that samples are to be obtained from milking animals in three locations within a 5 km distance having the highest potential dose. If none are available, samples are acceptable from milking animals in locations 5 to 8 km distance where doses are calculated to be greater than 1 mRem per year. A sample is also required at a control location. There are cu1Tently no identified milking animals (cow or goat) within the specified distances therefore; there are no cunent milk samples during the year 2024.

If no milk samples are available, the broadleaf vegetation sampling specified in ODCM Table 3.12-1 will be performed. Broadleaf sample requirements are such that samples of broadleaf vegetation are to be collected from each of two offsite locations of the highest predicted annual average D/Q if milk sampling is not performed at all the required locations. Cunently, broadleaf vegetation samples are collected at two indicator locations (N - 1.45 and SW - 1.0) and one control location (SW - 13.5). These indicator locations are near the site boundary in sectors where broadleaf vegetation is available, and D/Q is high. Therefore, no change to the broadleaf sampling program is required.

Food product sample requirements of ODCM Table 3.12-1 requires that one sample of each principal class of food product be collected from any area that is irrigated with water in which liquid plant waste has been discharged. Of the gardens identified in the land use census, no gardens are located in any area that irrigates with water in which liquid plant wastes are discharged.

Currently, food products are sampled from two locations (ENE - 9.0) and (E-4.2) when in season.

The location ENE-9.0 is for pecans at time of harvest and location E-4.2 will continue to be a major source of food products sold to the public.

The location E-4.2 had tomatoes which were collected from this location as a conservative measure. Th.is garden does not meet the ODCM Table 3.12-1 requirements because the products are not irrigated by water in which liquid plant wastes have been discharged.

Calculated values for the associated X/Q and D/Q values for each controlling receptor location and pathway are included along with the 1'eceptol' distances in the data tables of this land use census. The values used to determine potential dose due to radioactive effluent discharges am the highest calculated values based on annual average values. The following values are based on the original pre-operational and subsequent Comanche Peak 3 and 4 new build calculations which identified predominant wind direction, structures affecting potential release patterns, and area population. The annual average X/Q used for dose calculations is 3,30E-06, tritium X/Q is 4.36E-06, and the D/Q value is 3.34 E-08. All these values are conservative based on the 2023 Land Use Census data and therefore no changes are required in the dose calculation parameters as verified by the field data.

X/Q units are Sec/cubic meter

D/Q units are inverse square meters

Nearest Resident by Sector, Distance, XJQ and D/Q Sector Distance (Miles)

X/Q DIQ N

2.6 6.39E-07 3.50E-09 NNE 2.5 4.20E-07 2.00E-09 NE 2.5 2.90E-07 l.00E-09 ENE 2.6 2.20E-07 5.77E-10 E

2.5 2.70E-07 5.80E-10 ESE 2.2 4.02E-07 9.00E-10 SE 2.0 7.1 E-07 2.80E-09 SSE 1.5 1.1 0E-06 6.60E-09 s

l.5 8.50E-07 5.20E-09 SSW 1.8 5.04 E-07 2.42 E-09 SW 0.8 3.56E-06 l.85E-08 WSW 0.8 3.92E-06 l.63E-08 w

1.6 7.64E-07 2.S0E-09 WNW 2.5 4.70E-07 l.40E-09 NW 2.9 6.26E-07 l.98E-09 NNW 2.2 l.1 2E-06 5.16E-09 Note: The An11ual Average X/Q used for dose calculations is 3.30E-06 sec/cubic meter.

The Tritium value X/Q used for dose calculations is 4.36E-06 sec/cubic meter.

The Annual Average D/Q used for dose calculations is 3.34E-08 inverse square meters.

Nearest Garden by Sector, Distance and D/Q I Sector I Distance (Miles)*

I D/Q I

N None None NNE None None NE None None ENE None None E

4.2 2.00E-10 ESE None None SE None None SSE None None s

None None SSW None None SW None None WSW None None w

None None WNW None None NW None None NNW None None

Nearest Milk Animal by Sector, Distance and D/Q I Sector I Distance (Miles)*

I D/Q I

N None None NNE None None NE None None ENE None None E

None None ESE None None SE None None SSE None None s

None None SSW None None SW None None WSW None None w

None None WNW None None NW None None NNW None None

No Milk samples are currently being collected.

Population by Sector and Distance Sector 0-1 1-2 2-3 3-4 4-5 Total N

0 0

13 84 117 214 NNE 0

0 8

74 72 154 NE 0

0 182 179 320 68 1 ENE 0

0 111 31 67 209 E

0 0

229 312 43 584 ESE 0

0 117 181 174 472 SE 0

0 273 655 189 1117 SSE 0

105 157 130 2798 3190 s

0 30 133 64 307 534 SSW 0

6 8

11 80 105 SW 8

137 20 104 69 338 WSW 36 161 11 14 3

225 w

.0 112 10 28 18 168 WNW 0

0 21 71 158 250 NW 0

0 3

0 10 13 NNW 0

0 8

54 63 125 TOTAL 44 55 1 1304 1992 4488 8379 The average number of residents per house was obtained from North Central Texas Council of Governments for Hood and Somervell Counties. The number of residents per house is 2.56 and

2. 60, respectively. (http://www. in<lcxm u n<li.com/facts/uni ted-states/g uick-facts/tcxas/a vcrn gc-household-size#table)

Hood County, Texas/ Somervell County, Texas Age Persons under 5 years Persons under 18 years Persons 65 years and older 4.8% I 4.7%

20.6% I 21.6%

25.3% / 19.8%

(Population estimates as of April, I 2020 United State Census)

Environmental Sample Locations Table Sampling Point Location Sample Type*

A l A2 A3 A4 AS A6 A7 A8 RI R2 R3 R4 R5 R6 R7 RS R9 R IO RI I Rl2 R l3 Rl4 Rl5 Rl6 Rl7 Rl 8

sample Type:

N-1.45 (Squaw Creek Park)

A N-9.4 (Granbury)

A E-3.5 (Children's Home)

A SSE-4.5 (Glen Rose)

A S/SSW-1.2 A

SW-12.3 (CONTROL)

A SW/WSW-0.95 A

NW-1.0 A

N-1.45 (Squaw Creek Park)

R N-4.4 R

N-6.5 R

N-9.4 (Granbury)

R NNE-1.1 R

NNE-5.65 R

NE-1.7 R

NE-4.8 R

ENE-2.5 R

ENE-5.0 R

E-0.5 R

E-l.9 R

E-3.5 (Children's Home)

R E-4.2 R

ESE-1.4 R

ESE-4.7 R

SE-1.3 R

SE-3.85 R

I\\ - /\\ir Sample; R - Direct Radiaiion; SW - Surface Water: OW - Drinking Water GW - Ground Water; SS - Shoreline Sediments; M - Milk; F - Fish; FP - Food Products; BL - Broadleaf Vegetation

Environmental Sample Locations Table (cont.)

Sampling Point Location Sample Type*

Rl9 R20 R21 R22 R23 R24 R25 R26 R27 R28 R29 R30 R3 1 R32 R33 R34 R35 R36 R37 R38 R39 R40 R41 R42 R43 R44 R45 R46 R47

Sample Type:

SE-4.6 R

SSE-1.3 R

SSE-4.4 (Glen Rose)

R SSE-4.5 (Glen Rose)

R S-l.5 R

S-4.2 R

S/SSW-1.2 R

SSW-4.4 (State Park)

R SW-0.9 R

SW-4.8 (Girl Scout Camp)

R SW-12.3 (CONTROL)

R WSW-1.0 R

WSW-5.35 R

WSW-7.0 (CONTROL)

R W-1.0 R

W-2.0 R

W-5.5 R

WNW-1.0 R

WNW-5.0 R

WNW-6.7 R

NW-1.0 R

NW-5.7 R

NW-9.9 (Tolar)

R NNW-1.35 R

NNW-4.6 R

SE-0.6 R

A

Air Sample: R

Di reel Radimion; SW - Surface Waler; DW

Drinking Waler GW - Gmund Water: SS - Shoreline Sediments: M - Milk; F

Fish: FP - Food Products; BL * !Jrondlcaf Vegetation

Sampling Point Environmental Sample Locations Table (cont.)

Location Sample Type*

SWI SW2 SW3 SW4 SW5 SW6 GWl GW2 GW3 GW4 GW5 SSI SS2 SS3 SS4 Fl F2 FP I FP2

sample Type:

N-1.5 (Squaw Creek Reservoir Marina)

N-9.9 (Lake Granbury)

N-19.3 (CONTROL-Brazos River)

NE-7.4 (Lake Granbu1y)

ESE-1.4 (Squaw Creek Reservoir)

NNW-0. 1 (Squaw Creek Reservoir)

W-1.2 (Security Rifle Range)

WSW-0.1 (Somerville Water district)

SW SW/DW1 SW SW sw2 SW/DW2* 3 GW7 Gw3,4,6 SSE-4.6 (Glen Rose - Somerville Water District)

GW4 N-9.8 (Granbury)

GW1. 4,6 N-1.45 (Squaw Creek Park)

GW4 NNE-1.0 (Squaw Creek Reservoir)

SS N-9.9 (Lake Granbuty)

SS NE-7.4 (Lake Granbury)

SS SE-5.3 (Squaw Creek)

SS SE-0. I (Squaw Creek Reservoir)

F NNE-8.0 (Lake Granbury)

F ENE-9.0 (Leonard Bros. Pecan Farm)

FP E-4.2 (Hornick's Produce Farm)

FP A - Air Sample; R - Dirccl Radiation; SW - Surface Waler; DW - Drinking Wu1er G\\V - Ground Waier; SS - Shoreline Sediments; M - Milk; F - Fish; FP - l'ood Products; BL - Broadlcaf Vegetation

Sampling Point BLl BL2 BL3 Environmental Sample Locations Table (cont.)

Location N-1.45 SW-1.0 SW-13.5 (CONTROL)

Sample Type*

BL BL5 BL5

sample Type:

A - Air Sample; R - Direct Radiation; SW - Surface Water; OW - Drinking Waier GW - Ground Water; SS - Shoreline Sediments; 1vl - Milk; F - Fish; FP - food Products; BL - Broadlcaf Vegetation NOTES:

1. The municipal water system for the City of Granbury is supplied by surface water from Lake Granbury (location SW2) and ground water (location GW4). Each of these supplies is sampled. These samples are not required for compliance with Radiological Effluent Control 3/4.12.1, Table 3.12-1, because they are not affected by plant discharges.

2. This sample (location SW6) is representative of discharges from Squaw Creek Reservoir both down Squaw Creek and to Lake Granbury via the return line to Lake Granbury if used.

3. Plant potable water could be supplied by surface water from Squaw Creek Reservoir (location SW6) or ground water from onsite wells (location GW2) but is currently supplied by the Somerville Cmmty Water District from the Wheeler Branch Reservoir.

Each of these possible sources of water were sampled.

4. Ground water supplies in the plant site area are not affected by plant liquid effluents as discussed in CPSES FSAR Section 2.4.13. However, they are monitored for radioactivity IA W the requirements of the Radiological Effluent Control 3/4.12.1, Table 3.12-1.

5. Broadleaf sampling will be performed at the specified locations if milk samples are unavailable from any location.

6. Plant Potable Water (GW2) and Glen Rose (GW3) are supplied from surface water by the Somerville Water District from the Wheeler Branch Reservoir.

7. CPNPP Secu1ity Rifle Range (GWI ) is supplied by a local Well.

2 Mile Buffer

~

R36 R33 R30 R42 BL2 R27. A-7 J

SW1 GW5 A-1 R1 BL1

~

~

R9 "

sws

~

. <:)

u',".

. ii'~

~

CP-202500114, (CPNPP) - 2024 Annual Radiological Environmental Operating Report

Contents

Text

Subject:

Dear Sir or Madam:

Enclosure:

SUMMARY

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3.0 INTRODUCTION

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CP-202500114, (CPNPP) - 2024 Annual Radiological Environmental Operating Report

Text

Subject:

Dear Sir or Madam:

Enclosure:

SUMMARY

Conclusions:

3.0 INTRODUCTION

SUMMARY

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