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Management of Commercially Generated Radioactive Waste - U.S. ...

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6.101<br />

Isolation from the biosphere is achieved by low leach rates <strong>of</strong> radionuclides from the hard-<br />

ened grout sheet, negligible ground-water flow particularly up through the shale strata,<br />

retardation <strong>of</strong> nuclide movement by minerals within the shale strata, and low probability <strong>of</strong><br />

breeching by natural or man-made events.<br />

6.1.6.2 System and Facility Description<br />

System Options<br />

The two reference concepts for well injection disposal <strong>of</strong> nuclear waste have been<br />

selected from a number <strong>of</strong> options available at each step from the reactor to disposal at the<br />

well injection facility. These two concepts are judged as "most likely" based on the status<br />

<strong>of</strong> current technology. A summary <strong>of</strong> various options to be considered for well injection dis-<br />

posal is illustrated in Figure 6.1.18. Additional pertinent data available on the options<br />

can be found in various source material listed in Appendix M.<br />

<strong>Waste</strong>-Type Compatibility<br />

For both reference concepts the waste form injected would be HLW. Since disassembly and<br />

some processing would be necessary for well injection, the concepts would be suitable for<br />

fuel cycles that recycle uranium and plutonium. However, well injection could also be ap-<br />

plied to once-through fuel cycles after dissolution or slurrying <strong>of</strong> spent fuels. In these<br />

Reactors<br />

I LR <strong>Waste</strong> Mixes<br />

<strong>Waste</strong> Sources * Production, propulsion Fuel Cycles Do ste Mixes<br />

Domestic civilian<br />

SDomestic civilian and research U & Pu recycle cases I High level waste from<br />

* Domestic defense LMFBR Once-through cycle (LWR) Purex process<br />

Foreign HTGRTRU wastes<br />

* CANDU * Spent fuel assemblies.<br />

* Magnox or rods<br />

* Pebble bed<br />

<strong>Waste</strong> Forms<br />

* Diluted acidic liquid<br />

* Neutralized liquid<br />

* Acidic liquid Geologic Medium Site Arrangement Well Types<br />

* Neutralized supernate (C137)<br />

* Partitioned Cs, Sr sludge and Sedimentary Multiple wells per site * Deep well (5000 m)<br />

supernate Shale Single well per site * Shallow well (500 m)<br />

* Acid solution (Cs, Sr)<br />

* Spent fuel slurry<br />

Well Excavation Well Sealing<br />

Well Sealing<br />

I Rota drilling It M d Note: Option Classifications<br />

I Rotary drilling IEmplacement Method<br />

SShaft sinking Multiple seals above waste * Current Reference<br />

Big hole drilling Pumping Down hole seals e Primary Alternative<br />

SBlind hole boring Gravity Flow * Single seal above waste * Secondary Alternative<br />

e Combination<br />

* Single seal plus backfilling<br />

FIGURE 6.1.18. Major Options for Well Injection Disposal <strong>of</strong> Nuclear <strong>Waste</strong>

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