Hazardous or toxic waste destruction or containment – Destruction or containment of radioactive waste – By fixation in stable solid media
Reexamination Certificate
1999-12-21
2003-01-28
Silverman, Stanley S. (Department: 1754)
Hazardous or toxic waste destruction or containment
Destruction or containment of radioactive waste
By fixation in stable solid media
C588S252000
Reexamination Certificate
active
06512157
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to packaging of radioactive and/or hazardous waste in below grade trenches or excavations used for long term containment of the waste. Specifically, the present invention is an economical and efficient method for forming a waste containing monolith which meets applicable waste disposal laws, rules and regulations.
BACKGROUND OF THE INVENTION
The development of effective methods for the long term disposal of radioactive and/or hazardous wastes in an efficient and economic manner has proven to be a challenging problem. A variety of unfavorable characteristics present in these wastes dictate the use of solutions and methods which insure the effective isolation of these wastes from the environment for long periods of time for health and safety reasons. These characteristics include, but are not limited to, toxicity, radioactivity, and leachability in ground water. Other characteristics which may be present in these wastes, such as corrosiveness, rule out many potential disposal schemes as viable, long term solutions.
To protect human health and the environment, the United States and foreign governments have set up a variety of laws, rules, and regulations which govern the acceptable disposal of many of these wastes. One scheme currently allowed under the laws, rules and regulations of the United States permits these wastes to be contained within concrete monoliths, which are then buried in trenches and excavations for long term disposal. Over the course of the last several years, such disposal schemes have evolved to increase the efficiency and lower the cost of disposing of wastes in this manner.
For example, in the past it was common for concrete boxes with open tops to be fabricated, and then have wastes placed inside these boxes for disposal. Concrete boxes used for in these methods were typically fabricated, either on or off site, using common concrete construction methods, whereby forms, typically fashioned of plywood or an equivalent material, were constructed to define the exterior and interior dimensions of the concrete boxes. After placing material such as reinforcing bar, for reinforcing and adding structural strength to the concrete within the interior of the forms, Portland cement and concrete additive materials were then poured in and allowed to cure. Once the concrete cured, the forms were then removed, leaving a solidified, concrete box. The thus formed concrete box was then ready for accepting waste. If fabricated off site, the concrete boxes were then placed in position within a trench or excavation, and waste was then loaded over the exterior walls of the concrete boxes, typically with a crane, and placed in the interior of the boxes. The loading of these wastes could be an expensive and time consuming process. Wastes arriving in trucks for disposal needed to be removed from the trucks and transported, typically with a crane, over the walls of the concrete boxes for placement within. The hazardous nature of the wastes dictated that stringent safety procedures be followed. Additionally, some radioactive wastes with high levels of activity dictated the use of remote handling techniques which greatly complicated the movement of the wastes from the delivery trucks, onto the cranes, and into the interior of the concrete boxes. Once the waste was placed in the interior of these concrete boxes, and a concrete top was placed over the box and the box was buried. Drawbacks of this method included very low waste loading efficiency and gaps between the boxes.
These and other drawbacks then led to the development of methods whereby the boxes were fabricated utilizing form-type construction, with one end left open. In this manner, trucks delivering waste could access the interior of the boxes without the necessity of loading wastes over the walls with a crane. Once wastes are placed in the interior of the boxes utilizing this method, the open end is then closed, by fabricating an end to the box, using the same form-type construction. The thus completed box is then filled with concrete to capture the waste in a concrete.
A large disposal site, consisting of a trench or excavation, will typically be sequentially filled with many, separately fabricated concrete monoliths repetitively formed in this manner and using common walls, thereby forming a single, large monolith. The thus formed monolith is then covered with barriers as specified in applicable laws, rules and regulations, and buried. This method of forming a series of boxes, each with an open end, loading the waste into the box, and then fabricating a form to construct a closed end, and then filling the thus formed concrete box with concrete, represents the current state of the art method for containing wastes in concrete monoliths which is allowed under current laws, rules and regulations.
However, this state of the art method poses several drawbacks which add to the overall cost and inefficiency of the process. For example, the construction of boxes using the traditional forms requires significant labor and time to build the forms. Additionally, the fabrication of an open ended box, the end for the box, and the addition of the concrete to the waste in the interior of the box, all must be performed sequentially if waste is to be loaded into the interior of the concrete boxes directly from delivery trucks, and without the use of expensive cranes and rigging and the attendant safety precautions. The cumulative time required to wait for each of the various stages to be completed, including the time for the concrete to cure in each of these sequential steps, renders the overall process for forming each concrete monolith time consuming and expensive.
Thus, there exists a need for an improved method for forming concrete monoliths containing hazardous and/or radioactive wastes which is less labor intensive, has lower cost, is less time consuming, and allows efficient covering with barriers mandated by existing laws, rules and regulations.
OBJECTS
Accordingly, it is an object of the present invention to provide an improved method for forming a concrete monolith containing radioactive and/or hazardous wastes which minimizes the necessary labor, time and expense.
It is another object of the present invention to provide a method for forming the concrete monolith utilizing removable walls, which may be repeatedly used in the formation of other monoliths, or in the expansion of the original monolith.
It is another object of the present invention to provide a method for forming a concrete monolith utilizing removable walls, which allows for the encapsulation of waste simultaneous with the formation of the monolith, and without preformed walls to contain waste deposited therein.
It is another object of the present invention to provide a method for expanding a concrete monolith, wherein the expansion of the monolith is formed integrally with the existing monolith, and where the method allows for the encapsulation of waste simultaneous with the expansion of the monolith, and without a need for the construction of walls to contain waste deposited therein.
SUMMARY OF THE INVENTION
These and other objects are accomplished by forming a monolith containing hazardous and/or radioactive wastes by first forming an interior volume by placing removable walls on the site, pouring a flowable, curable, monolith forming material into the interior volume, thereby forming a floor within the interior volume, placing waste within the interior volume, submerging the waste within a second application of the monolith forming material by placing the second application of the monolith forming material within the interior volume, allowing the monolith forming material to cure to a solidified state, thereby forming a monolith with the waste encased within the monolith, and removing the walls. Alternatively, the floor may be first formed utilizing standard construction practices, and the method of the present invention is then practiced in the same manner as set forth above, except the removable wall
Alexander Robert G.
Phillips Steven J.
Williams Seleste A.
AGEC
Alexander Robert G.
Johnson Edward M.
Phillips Steven J.
Silverman Stanley S.
LandOfFree
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