DRC-2025-001739

May 28, 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 AB: Operational Period Modeling
AB-3.a
Based on Table S-1 of the “Final Supplement Environmental Impact Statement for Disposition of Depleted Uranium oxide Conversion Product Generated from DOE’s Inventory of Depleted Uranium
Hexafluoride” which projects conversion activities at gaseous diffusion plants continuing for over 40 years. Response to this RFI indicates that RESRAD was modeled for 50 years.
Please include both discussion and graphical representation covering the RESRAD modeled 50 year period in Appendix AB.
AB-10.a
The precise measurements of the 2000 stormwater retention pond, which were used in the RESRAD model, could not be located. While the model represents the surface water body as 100-meter
by 105-meter, a review of Engineering Drawing 08081-G03 suggests the pond is more rectangular in its physical form.
Please provide the engineering drawing with dimensional details, that informed the 100m x 105m used in RESRAD.
AB-16.a
As discussed in RFI AB-3.a above, please include both discussion and graphical representation covering the RESRAD modeled 50 year period in Appendix AB.
AB-23.a
Completion of the RESRAD model rerun has been confirmed. However, additional adjustments may be required due to subsequent Requests for Information. These potential changes include modifying
the stormwater retention pond dimensions, changes in hydraulic conductivity and creating updated graphs for the operational period.
Please review and, if necessary, rerun the RESRAD model to ensure the responses to RFIs AB-3.a, AB-10.a, and AB-16.a are integrated, as they may impact the results.
Appendix B: Federal l Cell Facility Engineering Drawings
B-23.a
The leaders along the ditch centerline in the drawing seem to indicate the flow direction for the drainage ditch, based on a callout on the Federal Cell’s northeast side and the inverts
at the cell corners. However, the proposed pitch of the drainage ditches is unclear, given the inconsistent dimension callouts addressed in RFI B-27.a.
Please clearly specify the pitch of the drainage ditches and provide accurate invert callouts.
B-27.a
The revision of the dimension on Cross Section A (Sheet 14004 C02, pg. 380) has now created a low point in the invert between the northeast and southeast corners. Based on the current
dimensions, surface drainage flowing due south will not be achieved.
Please revise or clarify the dimensions with consideration of RFI B-18 as requested in RFI-23.
B-34.a
The specified minimum distance of 3 feet from the Clay Liner conflicts with the 5-foot minimum indicated by the dimensions. The original RFI requested minimum excavation dimensions,
including the minimum cover from the "NATIVE SOIL" to the bottom of the "FILTER ZONE" material in the Drainage Ditch. These details are necessary to ensure clear constructability of
the "COMPACTED BORROW MATERIAL". 
Please revise Note #3 on Sheet 14004 C03 (pg. 382) to clarify excavation limits.
B-46.a

Neither Note #2 of Sheet 14004 C05 nor Specification 155 of CQA/QC Manual in Appendix C details the "approved seed mixture to be used on the embankment”. This information is necessary
to confirm the intended seed mixture will not include plant species that could adversely affect the final cover's performance.
Please provide specifications for the embankment seed mixture.
B-50.a
The proposed orientation of the DU cylinders lacks clarity to achieve structural integrity of the material, ensuring CLSM can be poured to adequately fill all voids, while maintaining
the butter zone limitations.
Please provide clarification on the orientation, construction methods, and geometry of the DU cylinders and their relationship to the buffer zone and embankment as shown. Include structural
details in the drawings or add explanatory text within the application to address these questions.
B-50.b
Appendix C, Specification #61 of the CQA/QC Manual requires DU cylinders to be punctured with a minimum of eight square inches or have their lids removed before infilling. However, FCF-CW-PR-102
(Appendix I), concerning Federal Cell Facility Waste Void Remediation, lacks specifics on puncture methods or lid removal for Controlled Low-Strength Material (CLSM) inflow.It is unclear
how this will be accomplished considering ALARA, uncertainty about container orientation, and potential CLSM reactions with cylinder contents.
Please provide methodologies and robust justification to confirm adequate CLSM infill for these containers, satisfying NUREG sections 4.3.1 and 4.3.2, or demonstration of established
professional industry practices and references to support the proposed approach.
Appendix O: Erosion Modeling
O-5.a
The suitability of the Rangeland Hydrology and Erosion Model (RHEM) to parameterize SIBERIA remains uncertain.
Consideringthat limiting parameter space is acceptable in principle, please provide justification for parameter culling given inherent uncertainties and parameter tradeoffs.
O-5.b
Gully formation is of key interest and according to the *RHEM Tutorial Guide, a limitation of the model is that “RHEM does not address channel, gulley, side-bank sloughing, head cutting,
rain-on-snow, and/or seep induced soil erosion processes”.
Please provide information on how the limitation of the RHEM model has been addressed.
*https://apps.tucson.ars.ag.gov/rhem/assets/docs/tutorials_and_fact_sheet/RHEM_Tutorial.pdf
O-5.c
REHM, an empirical model for estimating runoff and sediment yields in rangelands, differs structurally from SIBERIA, which uses physics-based, landform-specific calculations like advective
channel formation and diffusive hillslope processes. Therefore, direct parameter mapping between the two does not appear to be suitable.
Please provide the method and justification used to address the disparity.
O-5.d
Previous submissions suggest a narrow interpretation of hillside diffusion being solely surface runoff driven. However, it is important to note that hillslope diffusion more broadly
encompasses processes, notably soil creep. Soil creep involves gradual depth dependent downslope movement, a characteristic not accounted for by RHEM.
Please address this discrepancy and provide detail on the consideration of these factors.
O-5.e
Please provide rationale for the extremely low hillslope diffusivity values selected.
Appendix W: Surety
W-1.a
The 2020 Federal Cell Facility Quantity Calculations and Assumptions donot include equipment hours.
Please revise to incorporate equipment hourswhere applicable.
W-1.b
Line Item #31: DISPOSAL OF STORED FEDERAL WASTE.It is unclear how the amount of Controlled Low Strength Material required to encapsulate the Cylinders has been determined because the
application lacks clarity regarding the placement and encapsulation construction methodology.
Please provide further information to allow for verification of the calculation.
W-1.c
Line Item #211: SETTLEMENT MONITORING indicates 4 monuments are anticipated to close the cell.
Please justify the limited number of settlement monuments included in post closure.
W-1.d
Line Item #204: LINER CONSTRUCTION. contains a 0.11 factor forexcavating overburden, but the value of this indication is unclear. Additionally, it is unclear why the excavation volume
for the liner matches exactly the volume of the liner being placed. This implies that the excavation costs begin from the Top of Liner and not from the Top of Native Grade.
Please provide clarity on the calculation for these two items.
W-1.e
Line Item 207: COVER CONSTRUCTION. It is unclear which materials are being used in the calculation for volume.
Please revise the calculations to indicate consistent language throughout the application.