silo 3 - U.S. Department of Energy

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Access and Retrieval Strategy for the Silo 3 Project
Document No. 40430-PL-0002, Rev. 1
September 2003
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' SILO 3 MATERIAL
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Silo 3 contains metal oxide material generated from the operation of the former Feed
Materials Production Center (FMPC), now known as the Fernald Closure Project (FCP).
1.2.1 HISTORY OF GENERATION OF SILO 3 MATERIAL
Raffinate streams from FMPC's solvent extraction process were dewatered using rotary
vacuum filters. The filtrate streams were then processed through evaporators, and the
evaporator concentrates were further processed using either a spray calciner or a rotary
calciner. From plant startup through the mid-1 950s, a spray calciner processed the
concentrates. Approximately 35 percent of the Silo 3 material is believed to have come
from this process. Because of operational difficulties with the spray calciners, a rotary
calciner process was implemented. In this process, the evaporator concentrates were
transferred to a drum dryer and, finally, to a rotary calciner. The calciner removed residual
liquids and converted the metal nitrates to metal oxides. The resulting fine powdered
metal oxides were pneumatically transferred to Silo 3 for storage. Transfer of all materials
into Silo 3 continued until 1957.
1.2.2 QUANTITY AND CHARACTERISTICS OF SILO 3 MATERIAL
Approximately 5,100 yd3 of metal oxide material are stored in Silo 3. The predominant
radionuclide of concern is thorium-230, which is produced from the natural decay of
uranium-238. Silo 3 material is classified as 11 (e)(2) byproduct material under the Atomic
Energy Act of 1954, as amended, and contains several Resource Conservation and
Recovery Act of 1976 (RCRA) metals. Silo,3 material is specifically exempt from
regulation as a hazardous waste under RCRA because of its classification as 1 1 (e)(2)
byproduct material.
Based on historical information and recent sampling events, the following assumptions are
made regarding the physical characteristics of the Silo 3 material:
0 The uppermost two-thirds of the material is dry, fine powder, similar to fly ash.
0 Using data obtained during the Silo 3 Small Scale Waste Retrieval (FEMP 19981, and
the Flow Properties Test Report (Jenike & Johanson 20021, the lower third of the
material is assumed to be compacted such that it cannot flow freely. Small Scale
Retrieval activities removed material up to 11 feet high and 4 feet into the silo.
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Miscellaneous debris, such as simple hand tools, personal protective equipment (PPE),
and plastic bags, are potentially present in the silo.
0 About ninety percent (by weight) of the Silo 3 material sample passes through a 200-
mesh sieve. This indicates that the majority of the contents are expected to be silt/clay
size or smaller. Much of the Silo 3 material sample was easily fluidized, dispersible,
and flowable. Recent particle size analyses (Savannah River Technology Center 2001 1
showed that most of the material consists of particles greater than 1 micron. However,
these particles are aggregates of submicron size particles, that can be easily dispersed
during retrieval operations. It is expected that the retrieved Silo 3 material will have
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