Moab Critical Minerals EOI.pdf

Moab Critical Minerals EOI — Responses to Post-Industry Day Questions

Q1: Does DOE have a minerals assay for the Moab tailings that it can share with interested parties? If not, would DOE allow prospective participants to collect representative samples for independent assay and metallurgical testing? What approvals, sampling protocols, and radiological controls would apply?

DOE does not currently have a whole-cell or current-stream mineral assay for the Crescent

Junction tailings. The available data is historical and pre-relocation: the Atlas Corporation (1979) program, SRK Consulting (2001) study, and ORNL (1998) boring program, none of which constitute a present-day assay of the disposed stream. No site-specific metallurgical testing has been performed on vanadium or any other constituent.

Whether DOE would permit independent sampling, and under what protocols and approvals, is a decision DOE-EM leadership would need to make in coordination with the Moab site team. Any physical access to the cell for sampling efforts would require coordination with DOE-EM and the

NRC given the cell's UMTRCA/NRC-regulated status. Any sampling would need to be performed within applicable safety, environmental, and regulatory requirements, including the project's Radiation Protection Program. DOE would consider any impact to disposal cell design and integrity resulting from any sampling effort. This will be flagged to DOE-EM program leadership, who would work with the Moab site to define a sampling access framework before a response can be provided to the respondent.

Q2: Are the west-side slime placements, where vanadium appears most concentrated, under interim cover or final rock armor cover today? Would DOE consider recovery from completed cover sections, or only from areas not yet under final cover?

It's important to note upfront that the belief that the west side holds the highest grade and volume of critical minerals is based on disposal sequencing, not confirmed, comprehensive mapping.

On cover status: the cell's cover progression is more layered than a simple interim versus final rock armor distinction. Completed cover sections may include a radon barrier layer, with further layers potentially including a biointrusion/infiltration barrier, a frost protection layer, and a surface rock layer.

DOE would consider recovery from both completed cover sections and areas not yet under final cover. Areas previously covered are furthest from active operations and may offer greater operational flexibility, depending on timing. DOE would likely work with the NRC for a definitive path forward.

Q3: With placement continuing through about 2029, would DOE allow sampling, or segregating higher-grade material, as the remaining sub-pile and off-pile material is shipped and placed? That could avoid reopening completed cells.

Based on the lack of mineralogical data on current sub-pile and off-pile material, the project's mission focus, and the fact that sub-pile material is not tailings and off-pile material has process-related contamination without the tailings profile seen in the tailings pile, DOE is not considering sampling or segregation of this incoming material at this time. The appendix notes that the approximately 1 million tons expected through the tentative 2029 completion date includes off-pile and subpile radiologically contaminated material and may not have the same composition as the existing bulk tailings, and is not separately characterized, underscoring why a sampling or segregation protocol is not currently practical for this material stream.

Q4: The session noted that DOE plans to rework the west-side cover from rock armor to an evapotranspiration cover, with no near-term cover construction scheduled. What is the target timeframe for that rework, and would DOE consider sequencing recovery of the slime placements with it?

Timing is to be determined based on the overall project schedule and budget. Currently, cover construction is not planned until 2028, though this could change. Whether recovery could be sequenced with that construction has yet to be determined, but it is likely that the two would not occur concurrently, based on the construction process and hazards that could be associated with dual operations. Additionally, any material recovery would need to be evaluated for its potential impact on tailings volumes and cell design, since removing material could affect grading, cover design assumptions, or other engineering parameters that the cover construction depends on.

Q5: Does DOE have data on residual uranium content in the tailings? If a respondent recovers vanadium, would co-recovered uranium and other byproducts be available to the respondent, or retained by DOE?

Most of the uranium was removed during the milling process. DOE's published project overview confirms that more than 90 percent of the uranium was removed during processing, with radium and other decay products remaining in the tailings. The project's soil cleanup criteria are based on radium-226 and thorium-230 concentrations, not uranium, and there is significant residual radium in the tailings (DOE reports an average activity of about 660 picocuries per gram of radium-226, consistent with the appendix's reported Ra-226 average of 477 pCi/g in more recent

2012 to 2025 loadout measurements).

Separately, uranium is listed among the other co-located measured metals in the tailings in the appendix (along with barium, cadmium, calcium, iron, lead, mercury, molybdenum, selenium, silver, strontium, thallium, thorium), but no current whole-cell uranium grade or tonnage has been established. Similar to vanadium, no present-day assay exists.

Whether co-recovered uranium or other byproducts would be made available to a recovery respondent, versus retained by DOE, is a disposition and regulatory question. Given uranium's distinct regulatory status (source material under NRC/UMTRCA), this will likely require its own legal and regulatory determination separate from the vanadium recovery question and should be raised with DOE-EM and NRC early in any further discussions.