Surface storage, retrievable

Figure 1, Retrievable surface storage facility, water basin concept, cutaway...

A first step in our program was to define tentative criteria for acceptable waste forms for retrievable surface storage (I). The proper-... 

Compressive strength is historically one of the best measures of cement quality and will be useful for design purposes for the RSSF (the Retrievable Surface Storage Facility). 

After solidification and packaging, our conceptual studies assume that the waste may be placed in an on-site Retrievable Surface Storage Facility (RSSF). For the design basis assumed for this study, there would probably be a total of 9,000-10,000 containers, 2 ft in diameter by 10 ft in length, with an average heat output of / 250 W/container. The RSSF would probably be close-coupled to the solidification plant. The facility is expected to have the following characteristics ... 

Three main concepts have been considered for disposal of nuclear fuel waste in the very thick ice sheets of Antarctica and Greenland-meltdown, anchored emplacement, and surface storage [26]. In the meltdown concept, the heat-generating container of waste would be placed in shallow boreholes in the ice and flowed to melt their way down to the base of the ice sheet over a period of about a decade. In anchored emplacement, the containers would be attached by cables to a surface anchor that would limit their penetration into the ice to a depth of 200 to 500 m. This concept was designed to provide waste retrievability for a period of a few hundred years before additional accumulation of ice covert up the anchors. In surface storage, containers would be placed in a storage facility constructed above the ice surface on piers. As the piers sank, the facility could be jacked up to remain above the ice for perhaps a few hundred years. Then the entire facility would be allowed to slowly sink into the ice sheet. 

Density skimmers are a special type of bailer that are designed to remove LNAPL from the water surface in wells (Figure 7.4). Most of these circular skimmers are constructed with a hydrophobic (water-repelling) membrane around the intake area. When installed in a well (or other structure), such that the membrane is at or slightly below the water surface, the LNAPL seeps into the storage compartment. Periodically, the bailer is manually retrieved and LNAPL is recovered. Density skimmers are very useful at locations that have slow recovery and are in remote locations. A properly designed skimmer unit can remove LNAPL down to a thickness of /x in. (0.01 ft or 3 mm). 

An analysis of EPA s STORET (STOrage and RETrieval) database for 1980-82 showed that based on the statistical criteria used, 2,3,7,8-TCDD was detected but at concentrations too low to be quantified in surface-water samples collected at sampling sites (Staples et al. 1985). The sampling sites in the STORET database included both ambient and pipe sites. Ambient sites included streams, lakes, ponds, wells, reservoirs, canals, estuaries, and oceans and were intended to be indicative of general U.S. waterway conditions. Pipe sites referred to municipal or industrial influents or effluents (Staples et al. 1985). 

In a discussion on retrievability and recoverability some experts noted that, once the conceptual decision of disposal is taken, be it for waste or spent fuel, one should not any more talk of retrievability which is contradictory to the safety of the repository but of recoverability. There is always some possibility of recoverability. One can mine again into a repository. If long term storage of spent fuel for later use is considered, storage of spent fuel at the surface is e ier and cheaper than disposal in geological formations. 

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