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Appendix G- Detailed Description of Altemative 4: DoE(Rlr20o1-t 1
^ Entombment with Internal and Extei•nal Waste Disposal Rev. I t>mtt s
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1 would be the best location to do these activities because it is a closed facility for controlling
2 contamination spread. The most significant contribution to worker exposure under Alternative 4
3 would be the size reduction of the contaminated legacy equipment that is currently slered-on the
4 operating deck. Estimated worker dose for these activities alone is nearly 36 person-tem (I3111
5 2001a). If all of the legacy equipment on the operating deck is substantially reduced in size and
6 volume for placement into the process cells, significant worker time and resulting higher
7 exposures would occur. This activity, even with latest technologies available, would be
8 performed in personal protective equipment-required work areas ( i.e., contaminated areas and
9 airborne areas). Significant engineering controls would be required to reduce worker exposure
10 from external and internal exposure sources. Worker turnover could increase due to harsher
11 working conditions.
12
13 During final design, it is anticipated that emerging size and volume reduction technologies would
14 be evaluated for use. For this final FS, use of conventional size- and volume-reduction
15 technologies is assumed. Disassembly activities would include mechanical cutting, hydraulic
16 shearing, and manual methods. Additional technologies that could be applied are described in
17 Appendix I.
18
19 After the equipment is placed into the process cells, each cell would be coated with a fixative for
20 control of loose surface contamination. Cement grout would be placed in lifts into each process
(0^'21 cell to fill voids. Each lift would be allowed to cura before placing additional lifts. As each
22 process cell is filled, the cover blocks would be placed back int6 position. The volume of void
23 space to be filled within the process cells is conservatively estimated as 50% of total cell volume.
24 Therefore, the grout volume needed to fill the process cells is 3,400 m3 (4,400 yd3). After the
25 process cell cover blocks are in place, holes would be drilled through the covers and any voids
26 under and around the edges of the blocks would be filled by pressure grouting. The cover lifting
27 bails would be removed after pressure grouting is complete.
28
29 In the Phase I FS, consideration had been given to reserving the process cells only for disposal of
30 Class C wastes at 22I-U because of the high degree of isolation and shielding provided by the
31 process cells. However, in this final FS, there is a need to clear the sanyen epereting
32 deekcanvon deck to support building demolition. The removal and disposal of legacy equipment
33 to the process cells would be the most efficient means of achieving this objective. Moreover,
34 while the process cells provide a significant amount of isolation in 221-U as it is currently
35 configumd, after closure activities for Alternative 4, all parts of the 221-U Facility containing
36 waste fill, regardless of the class of waste within, would be equally protected (contained) by an
37 engineered barrier. Therefore, from the standpoint of long-term protectiveness, there is no
38 advantage in reserving the process cells exclusively for Class C waste. However, cell 3, may
39 have room for placement of avaste n+etefiais waste in addition to legacy waste from the canyon
40 #leerdcck.
41
42 All equipment and materials inside the operating gallery must be removed to support placement
("\43 of containerized waste into this gallery. There is a substantial amount of piping in this gallery
44 that requires removal. Conversely, very little equipment and piping would need to be removed
45 to prepare the pipe and electrical galleries ready for waste container placement.
Final Feasibifity StnCy jor llre Canyon Disporition lniriarive (22!•U Faeiirry)
1 00l G-11