DRC-2024-007430

299 South Main Street, Suite 1700 ▪ Salt Lake City, Utah 84111 [phone] ▪ Fax: [phone] ▪ www.energysolutions.com
October 1, 2024 CD-2024-207 Mr. Doug Hansen, Director
Division of Waste Management and Radiation Control
P.O. Box 144880 Salt Lake City, UT 84114-4880 Re: Deep Dose Equivalent (DDE) Exceedance at Air Monitoring Station A-28 (A-28)
for the Annual Period July 1, 2023 to June 30, 2024
Dear Mr. Hansen: On September 24, 2024, EnergySolutions calculated a DDE of 128 mrem/year for the
annual period from July 1, 2023, to June 30, 2024. This exceeds the Utah Administrative
Code (UAC) R313-15-301 limit of 100 mrem/year for public dose limits during operations of the Clive facility, as outlined in Section 4.4.2 of EnergySolutions’ Environmental Monitoring Plan, required by Condition 26 of Radioactive Material License UT2300249. This calculation was limited to external gamma dosimetry data in
preparation of the first semi-annual Environmental Monitoring Report of 2024.
As of now, EnergySolutions has not received particulate air sample data from its independent analytical laboratory, preventing the completion of the total effective dose equivalent (TEDE) calculation for Station A-28. However, historically, the TEDE has
primarily reflected the DDE, prompting this notification. In accordance with UAC
R313-15-1203, this report is submitted within 30 days of exceeding a dose limit. The TEDE exceedance for Station A-28 was previously reported to the Director on September 29, 2023 in the First 2023 Semi-Annual Environmental Monitoring Report (CD-2023-195), again in the March 26, 2024 notification letter regarding the DDE exceedance at
Air Monitor Station A-28 for 2023 (CD-2024-060), and in the Second 2023 Semi-Annual
Environmental Monitoring Report (CD-2024-081). Although the DDE remains above the limit, measures taken after the initial notification have continued to lower the elevated dose. Of the reported 128 mrem/year annual DDE,
93.7 mrem was recorded for the second half of 2023, while the DDE at Station A-28 has
decreased to 34.3 mrem for the first half of 2024. The increase in dose rate at Station A-28, identified in September 2023, was attributed to a significant volume of waste disposed of in 2022 in a High Radiation Area near the
vicinity of Station A-28. Standard procedures to shield the area with grouting were
disrupted due to an unexpected industry shortage of fly ash, essential for producing Controlled Low-Strength Material (CLSM). Consequently, EnergySolutions could not initiate grouting as planned in 2022.
Mr. Doug Hansen October 1, 2024 CD-2024-207 Page 2 of 2

To mitigate the dose rate since September 2022, EnergySolutions implemented several actions, including installing 20 sea van shielding containers between the High Radiation Area and the facility’s western fence line. A concrete barrier comprising 146 dense concrete blocks was also constructed, along with two earth berms approximately 8 feet
high. Following these corrective measures, the fence line dose fell below the action limit.
Clive security routinely patrols the property and has no report of any member of the public stationary and in place for any period of time. To prevent future elevated fence line doses from additional high radiation waste,
EnergySolutions has fully encapsulated the main source of the exceedance, High Radiation disposal lift area AWB18 in CLSM. As a result, the DDE at Station A-28 decreased by 63% from the second half 2023 to the end of the first half 2024. EnergySolutions will continue to monitor dose rates near A-28 for effectiveness, but it is expected that the fence line TEDE at A-28 will be below 100 mrem/year for the second
half of 2024 reporting period A root cause analysis is currently in progress to identify opportunities to predict potential exceedances so that preventative actions can be taken.
Please contact me at [phone] with any questions regarding this notification. Sincerely, Jon Anderson
Environmental Compliance Manager
I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations.