DRC-2025-002503

August 4, 2025
Vern C. Rogers, Director of Regulatory Affairs
EnergySolutions, LLC
299 South Main Street, Suite 1700
Salt Lake City, UT 84111
RE:Federal Cell Facility Application Request for Information
Dear Mr. Rogers:
The Division of Waste Management and Radiation Control (Division) hereby provides follow up Requests for Information (RFI) regarding the Federal Cell Facility Application dated August
4, 2022.
Each RFI in the attached document represents a follow up to an RFI issued earlier in the application review process. The numbering system ties the additional questions to the initial
RFI with an added letter designation. When responding to an RFI, please use the assigned number representing the question.
With this round of follow up RFIs, the Division recommends that appropriate staff from the Licensee, the Division and consultants meet to discuss each matter for clarity. Please contact
Larry Kellum at 385-622-1876 to schedule a meeting.
Sincerely,
Douglas J. Hansen, Director
Division of Waste Management and Radiation Control
DJH/LK/JMK/BBD
Enclosure: Federal Cell Application, Requests for Information.
c:Jeff Coombs, EHS, Health Officer, Tooele County Health Department
Bryan Slade, Environmental Health Director, Tooele County Health Department EnergySolutions General Correspondence EmailLLRW General Correspondence Email
Federal Cell Application Review
Request for Information or Updates to the Application (RFI)
General
Each of the RFI’s has been assigned an identifier with a numbering convention as follows-
Application/Appendix Section
Section/Appendix Subsection
Section/Appendix Subsubsection (when applicable)
Sequential numbering
Example: A question in Section 1, subsection 1, subsubsection 1 -The first RFI # would be 1.1.1-1, the next question in that section/subsection would be numbered 1.1.1-2
Please refer to the assigned RFI number when submitting a response.
Appendix O: Federal Cell Facility Waste Characterization Plan
O-39.a-1
The mistake acknowledged in response to 39.b (DRC-2025-001078) does not address the concerns previously outlined by the Division regarding the aeolian deposition rate distribution. To
clarify, please justify the continued use of a scaling data approach for aeolian deposition. The justification for theapproach taken in Deep Time Assessment for Clive DU PA (NAC-0032_R7)
to replace the standard deviation with the standard errorremains insufficient. Because the Depleted Uranium Performance Assessment (DU PA) is a nuclear licensing document, it has documentation
requirements that may not apply to other, less-critical analyses and without sufficient justification to the contrary, the full range of a distribution should be used.
Alternatively, please re-run the model replacing the standard error (i.e., 5.0 cm) with the standard deviation (i.e., 16.6 cm) in the Deep Time model aeolian deposition data. Then, compare
the results to ensure that it is sufficiently conservative.  
O-41
Please provide data that justifies the assumption of an effective porosity of 0.29 and a standard deviation of 0.05.
O-42
Section 3.1 of the Saturated Zone Modeling report statesthat 253 measurements of saturated hydraulic conductivities were taken at 122 locations nearthe cells and ponds. It is not clear
whether the measurements were performed on saturated zone materials or how the measurements were conducted and analyzed. Typically, hydraulic conductivity values are log-normally distributed
and the Performance Assessment assumes a normal distribution. It is not clear how the samples were oriented and whether it was vertical saturated hydraulic conductivity or horizontal,
which is more relevant to the saturated zone modeling.
Section 3.3 discusses the need for upscaling of the hydraulic gradient over time and space.The same types of factors should be considered for the hydraulic conductivities. As such,
please provide the following:
a) Please provide the technical report(s) describing how the hydraulic conductivity measurements were made, depth intervals, other aquifer properties (e.g., grain size distribution),
data analyzed, interpretation of results etc.
b) Please provide a detailed description of how the random effects analysis of variance model was performed to produce estimates of the mean Ks and its associated standard error, as
well as any spreadsheets etc. used in the analysis.
c) Please describe the upscalingprocess used to reconcile the hydraulic conductivity measurements with the scale of the modeling analysis.
d) Please explain why these tests are more representative of the hydraulic conductivities than those performed in the shallow aquifer presented in Envirocare (2004). As the hydraulic
conductivities cited in Envirocare 2004, obtained via slug testing of the shallow aquifer, averaged 7.45 ft/day. While the maximum hydraulic conductivity assigned in the DU PA is 2.72
ft/day. Higher hydraulic conductivity would result in higher radionuclide concentrations at the compliance well.
O-43
Please provide the site-wide hydraulic gradient information below:
a) The rationale for why the hydraulic gradients measured from 1999 to 2010 will be representative for the next 500 years once the proposed cell is constructed.
b) The analysis using the AMRA models used for the time correlation.
c) Detailedinformationon how the raw data was upscaled for the parameter distribution.

O-44
NAC-0016_R6 Section 2.0 Clive Site Hydrogeology states “The water table in the shallow aquifer is reported to be located in Unit 3 on the west side of the site and in Unit 2 on the east
side.” (p. 3).
Please explain why Unit 2 parameters are being assumed for hydraulic conductivity, porosity, and bulk density.
O-45
Please explain the physical processes that would lead toinstantaneous and uniform mixing of the radionuclides throughout the entire thickness of the aquifer before reaching the compliance
well located 90 feet from the proposed depleted uranium(DU) waste?
O-46
Please provide the technicium-99 concentrations, infiltration rates entering the saturated zone from the unsaturated zone in an Excel file for all of the GoldSim cells and simulations.
O-47
NAC-0016_R6 section 4.2 Dispersion states “The distance from the edge of the waste to the compliance point is 90 ft as required by the groundwater discharge permit.” However the report
also states that “For the Clive DU PA Model the point of compliance is a fixed location 265 ft from the edge of the DU waste,”. Please clarify thedistance specified from the edge of
the DU waste to the compliance point.
O-48
Please indicate ifthe number of cells in the transport path need to be recalculated based on a distance of 90 ft to the compliance well as opposed to 265 ft.
O-49
Please undertake other methods to ensure that mass balance is conserved in the GoldSim simulations. The small change obtained in the results by changing the solution precision does not
confirm that mass is being conserved.
O-50
Please explain why the peak concentrations are so sensitive to molecular diffusivity.
O-51
Please provide and discuss the assumptions and source for the tortuosity value(s).
O-52
The Envirocare 2004 report states that “From March 1993 to spring 1997 a borrow pit was excavated near the 11.e(2) cells to provide low permeability clay for adjacent disposal cell construction.
The pit occasionally filled with rainwater and the resulting infiltration resulted in a ground water mound near wells GW-37 and GW-38.” (p. 6) Please provide the extent of the on-site
clay mining activities and verify that neither the proposed Federal Cell Footprint nor saturated zone modelling is impacted by previous mining operations.
O-53
A continuous downward vertical hydraulic gradient has persisted at GW-19A/GW-19-B prior to the Envirocare 2004 report and continues to present day. Additionally, GW-27/GW-27D has also
had a downward vertical hydraulic gradient since 2015 (CD15-0221). Please provide justification why these consistently recorded data would be considered off-normal.
O-54
In the 2019 Revised Hydrogeological Report, hydrostratigraphic Unit 1 is “typically defined as the first occurrence of a unit beneath Unit 2 logged as sand in the field.” (p. 5) This
approach appears to differ from the NAC-0016_R6 methodology outlined in Section 4.1 Saturated Zone Dimensions. The reinterpretation of the data in NAC-0016_R6 would result in a reduction
in the thickness of Unit 2 (GW-19B ~ 2 ft, GW-27D ~12 ft) and would delineate the confining unit differently than previously understood. Please provide justification for changes in the
hydrostratigraphic units and provide the characteristics of the confining layer within the aquifer system at the Clive site. Includesupporting data for a confining layer, the hydraulic
properties of the confining unit, an updated hydrostratigraphic map, any additional bore logs, geochemical data, etc. that support that decision.
E-30
Please provide the proposed monitoring details for the vadose zone as required by NUREG-1388 section 4.2.2.1.3 Ground Water and Utah Administrative Code R317-6-6.3.I.4.