Text

Yankee Nuclear Power Station Independent Spent Fuel Storage Installation - Annual Radioactive Effluent Release Report, Annual Radiological Environmental Operating Report, and Changes to the Off-Site Dose Calculation Manual for 2024
	ML25111A112
Person / Time
Site:	Yankee Rowe
Issue date:	04/09/2025
From:	Clifford F; Yankee Atomic Electric Co
To:	; Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
	BYR-2025-011
	Download: ML25111A112 (1)
	v • d • e

YANKEE ATOMIC ELECTRIC COMPANY 49 Yankee Road, Rowe, Massachusetts 01367 April 9, 2025 BYR 2025-011 10 CFR 50.4 and 10 CFR 50.36a(a)(2)

ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555 - 0001 Yankee Atomic Electric Company Yankee Nuclear Power Station Independent Spent Fuel Storage Installation NRC License No. DPR-3 (NRC Docket Nos.50-029 and 72-31)

Subject:

Annual Radioactive Effluent Release Report, Annual Radiological Environmental Operating Report, and Changes to the Off-Site Dose Calculation Manual for 2024 10 CFR 50.36a(a)(2), Section 2.3.2 of Appendix C of the Yankee Atomic Electric Company (Y AEC) Quality Assurance Program (QAP) for the Yankee Rowe Independent Spent Fuel Storage Installation (ISFSI), and Section 3.2 of the Yankee Nuclear Power Station ISFSI Off-Site Dose Calculation Manual (ODCM): require YAEC to submit an Annual Radioactive Effluent Release Report. Enclosure 1 provides this report for the period of January 1 through December 31, 2024.

Section 2.3.1 of Appendix C of the YAEC QAP for the Yankee Rowe ISFSI and Section 3.1 of the Yankee Nuclear Power Station ISFSI ODCM require the submittal of an Annual Radiological Environmental Operating Report. Enclosure 2 provides the report for the period of January 1 through December 31, 2024.

Section 2.2.b) of Appendix C of the YAEC QAP for the Yankee Rowe ISFSI requires that any changes to the Yankee Nuclear Power Station ISFSI ODCM to be submitted as part of or concurrent with the Annual Radioactive Effluent Release Report. No revisions to the Yankee Nuclear Power Station ISFSI ODCM were issued during calendar year 2024.

If you have any questions regarding this submittal, please do not hesitate to contact me at (413) 424-5261 ext. 304.

Respectfully, Francis Clifford ISFSI Manager 1 E49

-TC25

4tiJf Nf-fS5Z?

J.Jf.-15S

Yankee Atomic Electric Company BYR 2025-011/April 9, 2025/Page 2

Enclosures:

1. Yankee Nuclear Power Station Independent Spent Fuel Storage Installation, Annual Radioactive Effluent Release Report, January - December 2024.

2. Yankee Nuclear Power Station Independent Spent Fuel Storage Installation, Annual Radiological Environmental Operating Report, January - December 2024 cc:

A. Kock, NRC Region I Administrator A. Dimitriadis, Chief, Decommissioning Branch, NRC, Region I Y. Diaz-Sanabria, Chief, Division of Fuel Management, Storage and Transportation Licensing Branch J. W. Priest, Director DPH, Radiation Control Program

ENCLOSURE 1 YANKEE NUCLEAR POWER STATION INDEPENDENT SPENT FUEL STORAGE INSTALLATION ANNUAL RADIOACTIVE EFFLUENT RELEASE REPORT JANUARY - DECEMBER 2024 BYR 2025-011

YANKEE NUCLEAR POWER STATION INDEPENDENT SPENT FUEL STORAGE INSTALLATION License Nos. DPR-3 and SFGL-13 ANNUAL RADIOACTIVE EFFLUENT RELEASE REPORT (ARERR)

January - December 2024 March 2025

EXECUTIVE

SUMMARY

Tables 1 and 2 summarize the quantity of radioactive gaseous and liquid effluents, respectively, for each quarter of 2024. There were no gaseous or liquid releases in 2024. Table 3 summarizes waste shipped off-site for disposal for each half year of 2024. There was no waste shipped for disposal in 2024.

Appendices A and B indicate the status of reportable items per the requirements of the Offsite Dose Calculation Manual (ODCM). There were no reportable items in 2024. Appendix C presents any changes in the ODCM. The ODCM was not revised in 2024.

YNPS 2024 ARERR Page2of15

Table 1 YNPS ISFSI Effluent and Waste Disposal Annual Report 2024 Gaseous Effluents-Summation of All Releases Nuclides Released Units 1st 2nd 3rd Quarter Quarter Quarter A. Fission and Activation Gases Total Release Ci N/A*

N/A*

Average release rate

µCi/s N/A*

N/A*

Percent of regulatory limit N/A*

N/A*

B. Iodines Total Iodines released Ci N/A*

N/A*

Average release rate

µCi/s N/A*

N/A*

Percent of regulatory limit N/A*

N/A*

C. Particulates Particulates Released Ci N/A*

N/A*

Average release rate

µCi/s N/A*

N/A*

Percent of regulatory limit N/A*

N/A*

Gross alpha radioactivity Ci N/A*

N/A*

D. Tritium Total release Ci N/A*

N/A*

Average release rate

µCi/s N/A*

N/A*

Percent of regulatory limit N/A*

N/A*

N/A*= Not Applicable 4th Quarter N/A*

N/A*

There are no gaseous effluents associated with the Yankee Nuclear Power Station Independent Spent Fuel Storage Installation (ISFSI)

Error N/A*

N/A*

YNPS 2024 ARERR Page 3 of 15

Table 1A YNPS ISFSI Effluent and Waste Disposal Annual Report 2024 Gaseous Effluents - Ground Level Releases - Batch Mode Nuclides Released Unit 1st 2nd 3rd 4th Quarter Quarter Quarter Quarter

1. Fission Gases Krypton-B5 Ci N/A*

N/A*

Krypton-B5m Ci N/A*

N/A*

Krypton-Bl Ci N/A*

N/A*

Krypton-BB Ci N/A*

N/A*

Xenon-133 Ci N/A*

N/A*

Xenon-135 Ci N/A*

N/A*

Xenon-135m Ci N/A*

N/A*

Xenon-13B Ci N/A*

N/A*

Unidentified Ci N/A*

N/A*

Total for period Ci N/A*

N/A*

2. Iodines lodine-131 Ci N/A*

N/A*

lodine-133 Ci N/A*

N/A*

lodine-135 Ci N/A*

N/A*

Total for period Ci N/A*

N/A*

3. Particulates Strontium-89 Ci N/A*

N/A*

Strontium-90 Ci N/A*

N/A*

Cesium-134 Ci N/A*

N/A*

NIA*

Cesium-137 Ci N/A*

N/A*

Cobalt-60 Ci N/A*

N/A*

Barium-Lanthanum-140 Ci N/A*

N/A*

Others-Plutonium-23B Ci N/A*

N/A*

Curium-243,244 Ci N/A*

N/A*

Uranium-234 Ci N/A*

N/A*

Uranium-23B Ci N/A*

N/A*

Thorium-232 Ci N/A*

N/A*

Radium-226 Ci N/A*

N/A*

N/A*= Not Applicable There are no gaseous effluents associated with the Yankee Nuclear Power Station ISFSI.

Total N/A*

N/A*

YNPS 2024 ARERR Page 4 of 15

Table 1B YNPS ISFSI Effluent and Waste Disposal Annual Report 2024 Gaseous Effluents - Ground Level Releases - Continuous Mode Nuclides Released Unit 1st 2nd 3rd 4th Quarter Quarter Quarter Quarter

1. Fission Gases Krypton-85 Ci N/A*

N/A*

Krypton-85m Ci N/A*

N/A*

Krypton-87 Ci N/A*

N/A*

Krypton-88 Ci N/A*

N/A*

Xenon-133 Ci N/A*

N/A*

Xenon-135 Ci N/A*

N/A*

Xenon-135m Ci N/A*

N/A*

Xenon-138 Ci N/A*

N/A*

Unidentified Ci N/A*

N/A*

Total for period Ci N/A*

N/A*

2. Iodines lodine-131 Ci N/A*

N/A*

lodine-133 Ci N/A*

N/A*

lodine-135 Ci N/A*

N/A*

Total for period Ci N/A*

N/A*

3. Particulates Strontium-89 Ci N/A*

N/A*

Strontium-90 Ci N/A*

N/A*

Cesium-134 Ci N/A*

N/A*

Cesium-137 Ci N/A*

N/A*

Cobalt-60 Ci N/A*

N/A*

Barium-Lanthanum-140 Ci N/A*

N/A*

Others-Plutonium-238 Ci N/A*

N/A*

Curium-243,244 Ci N/A*

N/A*

Uranium-234 Ci N/A*

N/A*

Uranium-238 Ci N/A*

N/A*

Thorium-232 Ci N/A*

N/A*

Radium-226 Ci N/A*

N/A*

N/A*= Not Applicable There are no gaseous effluents associated with the Yankee Nuclear Power Station ISFSI.

Total N/A*

N/A*

YNPS 2024 ARERR Page 5 of 15

Table 1C YNPS ISFSI Effluent and Waste Disposal Annual Report 2024 Gaseous Effluents - Elevated Releases - Batch Mode Nuclides Released Unit 1st 2nd 3rd 4th Quarter Quarter Quarter Quarter

1. Fission Gases Krypton-85 Ci N/A*

N/A*

Krypton-85m Ci N/A*

N/A*

Krypton-87 Ci N/A*

N/A*

Krypton-88 Ci N/A*

N/A*

Xenon-133 Ci N/A*

N/A*

Xenon-135 Ci N/A*

N/A*

Xenon-135m Ci N/A*

N/A*

Xenon-138 Ci N/A*

N/A*

Unidentified Ci N/A*

N/A*

Total for period Ci N/A*

N/A*

2. Iodines lodine-131 Ci N/A*

N/A*

lodine-133 Ci N/A*

N/A*

lodine-135 Ci N/A*

N/A*

Total for period Ci N/A*

N/A*

3. Particulates Strontium-89 Ci N/A*

N/A*

Strontium-90 Ci N/A*

N/A*

Cesium-134 Ci N/A*

N/A*

Cesium-137 Ci N/A*

N/A*

Cobalt-60 Ci N/A*

N/A*

Barium-Lanthanum-140 Ci N/A*

N/A*

Others-Plutonium-238 Ci N/A*

N/A*

Curium-243,244 Ci N/A*

N/A*

Uranium-234 Ci N/A*

N/A*

Uranium-238 Ci N/A*

N/A*

Thorium-232 Ci N/A*

N/A*

Radium-226 Ci N/A*

N/A*

N/A*= Not Applicable There are no gaseous effluents associated with the Yankee Nuclear Power Station ISFSI.

Total N/A*

N/A*

YNPS 2024 ARERR Page 6 of 15

Table 1D YNPS ISFSI Effluent and Waste Disposal Annual Report 2024 Gaseous Effluents - Elevated Releases - Continuous Mode Nuclides Released Unit 1st 2nd 3rd 4th Quarter Quarter Quarter Quarter

1. Fission Gases Krypton-85 Ci NIA*

NIA*

Krypton-85m Ci NIA*

NIA*

Krypton-87 Ci NIA*

NIA*

Krypton-88 Ci NIA*

NIA*

Xenon-133 Ci NIA*

NIA*

Xenon-135 Ci NIA*

NIA*

Xenon-135m Ci NIA*

NIA*

Xenon-138 Ci NIA*

NIA*

Unidentified Ci NIA*

NIA*

Total for period Ci NIA*

NIA*

2. Iodines lodine-131 Ci NIA*

NIA*

lodine-133 Ci NIA*

NIA*

lodine-135 Ci NIA*

NIA*

Total for period Ci NIA*

NIA*

3. Particulates Strontium-89 Ci NIA*

NIA*

Strontium-90 Ci NIA*

NIA*

Cesium-134 Ci NIA*

NIA*

Cesium-137 Ci NIA*

NIA*

Cobalt-60 Ci NIA*

NIA*

Barium-Lanthanum-140 Ci NIA*

NIA*

Others-Plutonium-238 Ci NIA*

NIA*

Curium-243,244 Ci NIA*

NIA*

Uranium-234 Ci NIA*

NIA*

Uranium-238 Ci NIA*

NIA*

Thorium-232 Ci NIA*

NIA*

Radium-226 Ci NIA*

NIA*

NIA*= Not Applicable There are no gaseous effluents associated with the Yankee Nuclear Power Station ISFSI.

Total NIA*

NIA*

YNPS 2024 ARERR Page 7 of 15

Table 2 YNPS ISFSI Effluent and Waste Disposal Annual Report 2024 Liquid Effluents - Summation of All Releases Nuclides Released Units 1st 2nd 3rd Quarter Quarter Quarter A. Fission and Activation Products Total Release (not including Ci N/A*

N/A*

tritium, qases, alpha)

Average diluted concentration

µCi/ml N/A*

N/A*

during period Percent of applicable limit N/A*

NIA*

B. Tritium Total Release Ci N/A*

N/A*

Average diluted concentration

µCi/ml N/A*

N/A*

NIA*

during period Percent of applicable limit N/A*

N/A*

C. Dissolved and Entrained Gases Total Release Ci N/A*

N/A*

Average diluted concentration

µCi/ml N/A*

N/A*

NIA*

durinq period Percent of applicable limit N/A*

N/A*

D. Gross Alpha Radioactivity Total release Ci N/A*

N/A*

NIA*

Average diluted concentration

µCi/ml N/A*

NIA*

N/A*

during period E. Volume of Waste Released Liters N/A*

N/A*

{prior to dilution)

F. Volume of Dilution Water Liters N/A*

N/A*

Used During Period N/A*= Not Applicable 4th Error Quarter N/A*

N/A*

There are no liquid effluents associated with the Yankee Nuclear Power Station ISFSI.

YNPS 2024 ARERR Page 8 of 15

Table 2A YNPS ISFSI Effluent and Waste Disposal Annual Report 2024 Liquid Effluents - Batch Mode Nuclides Released Unit 1st 2nd 3rd Quarter Quarter Quarter Stronti u m-89 Ci N/A*

N/A*

Strontium-90 Ci N/A*

N/A*

Cesium-134 Ci N/A*

N/A*

Cesium-137 Ci N/A*

N/A*

lodine-131 Ci N/A*

N/A*

Cobalt-58 Ci N/A*

N/A*

Cobalt-60 Ci N/A*

N/A*

lron-59 Ci N/A*

N/A*

Zinc-65 Ci N/A*

N/A*

Manganese-54 Ci N/A*

N/A*

Chromium-51 Ci N/A*

N/A*

Zirconium-Niobium-95 Ci N/A*

N/A*

Molybdenum-99 Ci N/A*

N/A*

Technetium-99m Ci N/A*

N/A*

Barium-Lathanium-140 Ci N/A*

N/A*

Cerium-141 Ci N/A*

N/A*

Others-lron-55 Ci N/A*

N/A*

Antimony-125 Ci N/A*

N/A*

Unidentified Ci N/A*

N/A*

Total for period (above)

Ci N/A*

N/A*

Dissolved and Entrained Ci N/A*

N/A*

Gasses Tritium Ci N/A*

N/A*

Gross Alpha Ci N/A*

N/A*

N/A *= Not Applicable 4th Totals Quarter N/A*

N/A*

There are no liquid effluents associated with the Yankee Nuclear Power Station ISFSI.

YNPS 2024 ARERR Page 9 of 15

Table 28 YNPS ISFSI Effluent and Waste Disposal Annual Report 2024 Liquid Effluents - Continuous Mode Nuclides Released Unit 1st 2nd 3rd Quarter Quarter Quarter Strontium-89 Ci N/A*

N/A*

Strontium-90 Ci N/A*

N/A*

Cesium-134 Ci N/A*

N/A*

Cesium-137 Ci N/A*

N/A*

lodine-131 Ci N/A*

N/A*

Cobalt-58 Ci N/A*

N/A*

Cobalt-60 Ci N/A*

N/A*

lron-59 Ci N/A*

N/A*

Zinc-65 Ci N/A*

N/A*

Manganese-54 Ci N/A*

N/A*

Chromium-51 Ci N/A*

N/A*

Zirconium-Niobium-95 Ci N/A*

N/A*

Molybdenum-99 Ci N/A*

N/A*

Technetium-99m Ci N/A*

N/A*

Barium-Lathanium-140 Ci N/A*

N/A*

Cerium-141 Ci N/A*

N/A*

Others-I ron-55 Ci N/A*

N/A*

Antimony-125 Ci N/A*

N/A*

Unidentified Ci N/A*

N/A*

Total for period (above)

Ci N/A*

N/A*

Dissolved and Entrained Ci N/A*

N/A*

Gasses Tritium Ci N/A*

N/A*

Gross Alpha Ci N/A*

N/A*

N/A*= Not Applicable 4th Totals Quarter N/A*

N/A*

There are no liquid effluents associated with the Yankee Nuclear Power Station ISFSI.

YNPS 2024 ARERR Page 10 of 15

Table 3 YNPS ISFSI Effluent and Waste Disposal Annual Report First Half 2024 Low Level Waste Shipments Resins, Filters and Evaporator Bottoms Volume Waste Class Solidifying Agent ft3 m3 A

0 0

B 0

0 C

0 0

All 0

0 Major radionuclides for above data: N/A Dry Active Waste Volume Waste Class Solidifying Agent ft3 m3 A

0 0

B 0

0 C

0 0

All 0

0 Major radionuclides for above data: N/A Irradiated Components Volume Waste Class Solidifying Agent tt3 m3 A

0 0

B 0

0 C

0 0

All 0

0 Major radionuclides for above data: N/A Other Waste Volume Waste Class Solidifying Agent tt3 m3 A

0 0

B 0

0 C

0 0

All 0

0 Major radionuclides for above data: N/A YNPS 2024 ARERR Curies Shipped Curies 0

0 0

0 Curies Shipped Curies 0

0 0

0 Curies Shipped Curies 0

0 0

0 Curies Shipped Curies 0

0 0

0 Page 11 of 15

Table 3A YNPS ISFSI Effluent and Waste Disposal Annual Report Second Half 2024 Low Level Waste Shipments Resins, Filters and Evaporator Bottoms Volume Waste Class Solidifying Agent tt3 m3 A

0 0

B 0

0 C

0 0

All 0

0 Major radionuclides for above data: N/A Dry Active Waste Volume Waste Class Solidifying Agent tt3 m3 A

0 0

B 0

0 C

0 0

All 0

0 Major radionuclides for above data: N/A Irradiated Components Volume Waste Class Solidifying Agent tt3 m3 A

0 0

B 0

0 C

0 0

All 0

0 Major radionuclides for above data: N/A Other Waste Volume Waste Class Solidifying Agent tt3 m3 A

0 0

B 0

0 C

0 0

All 0

0 Major radionuclides for above data: N/A YN PS 2024 ARERR Curies Shipped Curies 0

0 0

0 Curies Shipped Curies 0

0 0

0 Curies Shipped Curies 0

0 0

0 Curies Shipped Curies 0

0 0

0 Page 12 of 15

Appendix A Radiation Dose Assessment There were no gaseous or liquid effluent releases in 2024. Therefore, an assessment of radiation doses to the most likely exposed member(s) of the public to show compliance with 40CFR190 or 10CFR72.104 from effluents was not required.

YNPS 2024 ARERR Page 13 of 15

Appendix B Unplanned Releases There were no unplanned releases of radioactive materials in effluents in 2024.

YNPS 2024 ARERR Page14of15

Appendix C Offsite Dose Calculation Manual Changes There were no changes to the Offsite Dose Calculation Manual in 2024.

YNPS 2024 ARERR Page 15 of 15

BYR 2025-01 1 ENCLOSURE2 YANKEE NUCLEAR POWER STATION INDEPENDENT SPENT FUEL STORAGE INSTALLATION ANNUAL RADIOLOGICAL ENVIRONMENTAL OPERATING REPORT JANUARY - DECEMBER 2024

YANKEE NUCLEAR POWER STATION INDEPENDENT SPENT FUEL STORAGE INSTALLATION License Nos. DPR-3 and SFGL-13 ANNUAL RADIOLOGICAL ENVIRONMENTAL OPERA TING REPORT (AREOR)

January - December 2024 March 2025

EXECUTIVE

SUMMARY

Yankee Nuclear Power Station (YNPS) was permanently shutdown in 1991. All fuel has been transferred into dry storage casks and placed at the Independent Spent Fuel Storage Installation (ISFSI). The Radiological Environmental Monitoring Program (REMP) for the YNPS ISFSI located in Rowe, Massachusetts was continued for the period January through December 2024 in compliance with the YNPS Offsite Dose Calculation Manual (ODCM).

By design, there are no liquid or gaseous effluents associated with the operation of the ISFSI. Changes in radiological conditions at the ISFSI are only created through radiological decay of the spent nuclear fuel and greater than class C (GTCC) waste.

Therefore, the ODCM only requires monitoring of direct exposure from the facility.

TLDs were used to measure direct gamma exposure at six locations in the vicinity of the ISFSI and one control location 7.6 kilometers away. The results of these measurements showed no significant change in exposures and potential doses to members of the public during the monitoring period. The results of the monitoring performed in 2024 also show that operating the YNPS ISFSI results in only a small fraction of the 40 CFR Part 190 and 10 CFR Part 72.104 direct radiation dose limit of 25 mrem/year to members of the public.

YNPS 2024 AREOR Page 2 of 18

TABLE OF CONTENTS Section Title Page

1.0 INTRODUCTION

............................................................................................ 5 2.0 GENERAL ISFSI AND SITE INFORMATION................................................. 6 3.0 PROGRAM DESIGN...................................................................................... 6 3.1 MONITORING ZONES......................................................................................... 6 3.2 PATHWAYS MONITORED.................................................................................... 7

3.3 DESCRIPTION

OF MONITORING PROGRAM.......................................................... 7 4.0 RADIOLOGICAL DATA

SUMMARY

TABLES............................................. 14 5.0 ANALYSIS OF ENVIRONMENTAL RESULTS............................................ 17 5.1 SAMPLING PROGRAM DEVIATIONS.................................................................... 17 5.2 DIRECT RADIATION PATHWAY........................................................................... 17

6.0 REFERENCES

............................................................................................. 18 YNPS 2024 AREOR Page 3 of 18

Table Title 3.1 Radiological Environmental Monitoring Program...................................... 8 3.2 Radiological Environmental Monitoring Locations................................... 9 4.1 TLD Measurements by Half-Year............................................................... 15 4.2 Direct Dose from ISFSI Operations........................................................... 16 Figure 3.1 All Radiation Monitoring Locations.......................................................... 10 3.2 Onsite Direct Radiation Monitoring Locations......................................... 11 3.3 Direct Radiation Monitoring Locations (Within 1 mile)............................ 12 3.4 Offsite Control Location............................................................................. 13 YNPS 2024 AREOR Page 4 of 18

1.0 INTRODUCTION

This report summarizes the findings of the REMP conducted by Yankee Atomic Electric Company (YAEC) in the vicinity of the ISFSI in Rowe, Massachusetts during the calendar year. There were no changes identified in the use of unrestricted areas that would require modifications to the monitoring program for evaluating doses to individuals from principal pathways of exposure. It is submitted annually in compliance with the ODCM. The remainder of this report is organized as follows:

Section 2:

Provides a brief description of the Yankee site and its environs.

Section 3:

Provides a description of the overall REMP design. Included is a summary of the ODCM requirements for REMP sampling, tables listing TLD monitoring locations with compass sectors and distances from the ISFSI, and maps showing the location of each of the TLD monitoring locations.

Section 4:

Provides a complete set of TLD data in the exposure units of milliroentgen (mR). These TLD data are then converted to a calculated dose equivalent in units of mrem per year.

Section 5:

Provides the results of the calendar year monitoring program. The performance of the program in meeting ODCM requirements is discussed, and the data acquired during the year is analyzed.

Section 6:

References YNPS 2024 AREOR Page 5 of 18

2.0 GENERAL ISFSI AND SITE INFORMATION The YNPS site is located on over 1800 acres in a predominantly rural area of northwestern Massachusetts, three-quarters of a mile south of the Vermont border. The site resides in the town of Rowe, Massachusetts, approximately 9 air miles east-northeast of North Adams, Massachusetts. The surrounding area is heavily forested and lightly populated. Hills bounding the river valley rise 500 to 1000 feet above the site, reaching elevations of 2100 feet.

The Deerfield River is used extensively for hydroelectric power generation both upstream and downstream of YNPS. The Sherman Dam, immediately adjacent to the site, operates as a hydroelectric generating station. Sherman Pond, the impoundment behind this dam, had been used as a source of cooling water for the former power plant.

The former nuclear power plant was voluntarily shut down on October 1, 1991, after 31 years of operation. The site was involved in the process of decommissioning over the years which involved the disassembly and removal of the plant components and structures and was completed in 2006. This process took place in strict conformance with USN RC regulations. Oversight of the site closure process also took place from the U.S. Environmental Protection Agency, the Massachusetts Department of Environmental Protection, and Massachusetts Department of Public Health.

3.0 PROGRAM DESIGN The REMP for the YNPS ISFSI was designed to provide assurance to regulatory agencies and the public that the station's environmental impact is known and within anticipated limits. The direct dose limit for members of the public from operation of the ISFSI is 25 mrem per year (References 2 and 3).

The detailed sampling requirements of the REMP are given in the ODCM. The sampling requirements specified in the ODCM are summarized in Table 3.1 of this report. Details of the locations monitored are shown in Table 3.2, as well as Figures 3.1 through 3.4 of this report.

3.1 Monitoring Zones The REMP is designed to allow a comparison of levels of radioactivity in samples from the area possibly influenced by the ISFSI to levels found in areas not influenced by the ISFSI. The first area is called "indicator stations." The second area is called "control stations." The distinction between the two is based on relative direction from the facility and distance. Analysis of survey data from the two zones aids in determining if there is a significant difference between the two areas. It can also help in differentiating between radioactivity or radiation due to releases and those due to other fluctuations in the environment, such as seasonal variations in the natural background.

YNPS 2024 AREOR Page 6 of 18

3.2 Pathways Monitored Based on the design of the ISFSI, only the direct radiation exposure pathway is monitored by the REMP. This pathway is monitored by the collection of thermoluminescent dosimeters (TLDs) which are described in more detail below.

3.3 Description of Monitoring Program 3.3.1 Direct Radiation Direct gamma radiation exposure was continuously monitored during 2024 with the use of TLDs. At each monitoring location, these TLDs are sealed in plastic bags and attached to an object, such as a tree, fence or utility pole. The TLDs are posted and retrieved on a semi-annual basis. All TLDs are provided and processed by a National Voluntary Laboratory Accreditation Program (NVLAP) certified vendor. The TLDs are placed at various locations around the ISFSI.

Table 3.2 lists the Station ID Codes, distances and direction of the TLDs from the ISFSI.

3.3.2 Special Monitoring Special samples can be taken that are not required in the ODCM. No special samples were collected in 2024.

YNPS 2024 AREOR Page 7 of 18

Table 3.1 Radiological Environmental Monitoring Program Exposure Collection Analysis Pathway Number of Routine and/or Collection Analysis Analysis Sample Sample Sampling Frequency Type Frequency Media Locations Mode Direct Total Locations: 7 Continuous Semi-Gamma Semi-Radiation (6 around annual dose annual (TLD) perimeter of the site and 1 offsite control location)

YNPS 2024 AREOR Page 8 of 18

Table 3.2 Radiological Environmental Monitoring Locations Distance Direction Station Code Station Description Zone

From ISFSI (km)

From ISFSI GM-15 Onsite Perimeter (I)**

1 0.24 NW GM-16 Onsite Perimeter (I)**

1 0.22 NNW GM-17 Onsite Perimeter (I)**

1 0.13 NNE GM-21 Onsite Perimeter (I)**

1 0.17 WSW GM-02 Observation Stand (O)**

1 0.50 NW GM-06 Tunnel Road Readsboro 1

1.30 N

Town Line (0)**

GM-27 Number Nine Road (0)*

2 7.60 ENE

2 = Control TLD; 1 = Indicator TLD

- I = Inner Ring TLD; 0 = Outer Ring TLD YNPS 2024 AREOR Page 9 of 18

Figure 3.1 All Radiation Monitoring Locations YNPS 2024 AREOR Page 10 of 18

Figure 3.3 Direct Radiation Monitoring Locations (Within 1 mile)

YNPS 2024 AREOR 0

CZ, r:::

r:::

>2 OGM-6 0

INSET 1 300 Page 12 of 18

YNPS 2024 AREOR Figure 3.4 Offsite Control Location 0 GM-27

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0) 0

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INSET2 Page 13 of 18

4.0 RADIOLOGICAL DATA

SUMMARY

TABLES This section summarizes the analytical results of the environmental samples which were collected during the monitoring period.

Data from direct radiation measurements made by TLDs are presented in Table 4.1.

Table 4.2 presents the estimated direct dose from ISFSI operations as determined by TLD data shown in Table 4.1.

YNPS 2024 AREOR Page 14 of 18

Station ID GM-02 GM-06 GM-15 GM-16 GM-17 GM-21 GM-27 GM-27a Notes:

Table 4.1 TLD Measurements by Half-Year (mR)

Location 1st Half-Year Observation Stand 38 Tunnel Road Readsboro (1)

Town Line On-site perimeter 48 On-site perimeter 44 On-site perimeter 45 On-site perimeter 39 Control 37 Control Backup 38 (1) TLD missing at time of retrieval.

YNPS 2024 AREOR 2nd Half-Year 44 41 46 47 43 41 37 39 Page15of18

Station ID GM-02 GM-06 GM-15 GM-16 GM-17 GM-21 Notes:

Table 4.2 Direct Dose from ISFSI Operations (mrem) 1st Half-Year 2nd Half-Year NetTLD Calculated NetTLD Calculated Result Dose Result Dose 0.5 0.03 6.0 0.34 (1)

(1) 3.0 0.17 10.5 0.60 8.0 0.46 6.5 0.37 9.0 0.51 7.5 0.43 5.0 0.29 1.5 0.09 3.0 0.17 Max Dose=>

Annual Dose 0.37 0.34(2) 1.06 0.88 0.72 0.26 1.06 Doses based on a 250 hour0.00289 days 0.0694 hours 4.133598e-4 weeks 9.5125e-5 months occupancy in both of the first and second half-years.

(1) TLD missing at time of retrieval.

(2) TLD result from the second half of the year was doubled to account for the missing TLD in the first half of the year.

YNPS 2024 AREOR Page 16 of 18

Radiological Environmental Monitoring Program Trending An evaluation of current 2024 TLD data was compared to the recent historical data by location for each of the REMP TLDs for trending purposes. This trending assessment evaluates the final doses from each of the indicator locations as compared to recent annual historical doses. The trending assessment is performed for the "real members of the public" based on the guidance provided in the ODCM.

The analysis of the trends identifies very low annual doses near or typically below 1.5 mrem with minor fluctuations in the data as compared to recent historical data.

The trending comparison for each of the indicator locations confirmed that the doses are generally consistent with the most recent historical doses.

In this report, the uncorrected TLD results have been summarized and presented in Table 4.1. The annual doses, calculated for "real members of the public" based upon guidance in the ODCM, are presented in Table 4.2.

5.0 ANALYSIS OF ENVIRONMENTAL RESULTS 5.1 Sampling Program Deviations A sampling program deviation is defined as samples that are unobtainable due to hazardous conditions or to malfunction of sampling equipment. Such deviations do not compromise the program's effectiveness and in fact are considered insignificant with respect to what is normally anticipated for this REMP.

There was one deviation of the sampling program documented in 2024.

The deviation was a missing TLD at location GM-06 at the time of retrieval at the end of the 1st half of the year in 2024. This was documented in Condition Report Number YA-CR-2024-138.

This condition has no impact on the REMP.

5.2 Direct Radiation Pathway 5.2.1 Annual Dose Trends Direct radiation is continuously measured at 6 indicator locations surrounding the YNPS ISFSI, along with 1 control location at Number Nine Road using TLDs. These dosimeters are collected semi-annually for readout at the NVLAP certified dosimetry services vendor.

The review of the data for trending purposes shows no significant difference in annual doses over time at the indicator locations and their relation to the 25 mrem/yr limit.

5.2.2 Direct Doses from ISFSI Operations The ODCM specifies that a cumulative dose estimate from direct radiation is required to be determined semi-annually. This dose estimate is the potential YNPS 2024 AREOR Page 17 of 18

dose to any real member of the public that could use portions of the site or be present adjacent to the site for recreational activities throughout the year. The ODCM states that direct exposure above background can be estimated by subtracting the average TLD value of the control station from the indicator location measurements. As in previous years, the 2024 dose estimate assumes a total of 500 hours0.00579 days 0.139 hours 8.267196e-4 weeks 1.9025e-4 months occupancy for the dose calculation; of which 250 hours0.00289 days 0.0694 hours 4.133598e-4 weeks 9.5125e-5 months are used in both the first and second half-years. The most likely location for exposure to a member of the public from the ISFSI is in Sherman Reservoir for boating and fishing; however, the time estimates are conservatively applied to all monitoring locations.

Table 4.2 presents the results of the dose calculations. The highest calculated dose is at Station ID number GM-15. The maximum calculated annual dose at this location is 1.06 mrem. This value is only 4.2 percent of the 25 mrem per year limit. This represents a conservative dose estimate because a member of the public would normally be situated further away in the reservoir.

6.0 REFERENCES

1. Yankee Nuclear Power Station Offsite Dose Calculation Manual, Revision

23.

2.

40 CFR Part 190, "Environmental Radiation Protection Standards for Nuclear Power Operation."

3.

10 CFR Part 72.104, "Criteria for Radioactive Materials in Effluents and Direct Radiation from an ISFSI or MRS."

YNPS 2024 AREOR Page 18 of 18

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