Abstract:
A method of modifying a domed structure for demolition comprises forming a hinge or pivoting arrangement in a wall of the domed structure. The hinge arrangement allowing the domed structure to rotate about a reaction line for controlled demolition of the structure. The domed structure can be modified with additional openings in the dome and wall for explosive charges to facilitate the demolition.

Description:
[0001]    This application claims priority based on provisional patent application No. 60/355,754 filed on Feb. 12, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is directed to a domed structure and its method of demolition, and particularly to demolition of nuclear reactor domed structures using a hinge arrangement to direct the domed structure in a desired direction during demolition.  
         BACKGROUND ART  
         [0003]    In the prior art, various techniques are employed to demolish buildings. One technique involves the use of a hinge structure. In this technique, a “hinge” is built within the structure to be demolished. The hinge is formed from concrete and/or rebar, and is typically installed within the structure to be demolished. The hinge is positioned and configured with the appropriate explosives so that once the explosives are detonated, the hinge defines a pivot line for the structure to fall. The hinge aids in directing the structure along a predetermined fall line, so that surrounding buildings are not damaged. Identification of the fall line also allows the demolition team to prepare the ground for impact.  
           [0004]    While it is known to use hinges to take down buildings that have a large height to diameter ratio, e.g., a chimney, domed structures are more problematic, particularly nuclear reactor domed structures. Often times, the walls of the containers are four feet thick, the height to diameter ratio is far less than is found in chimneys, grain elevators and the like. Consequently, there is a need for improved techniques for demolishing nuclear reactor domed structures as well as other domed structures of substantial mass.  
         SUMMARY OF THE INVENTION  
         [0005]    It is a first object of the present invention to provide a method of demolishing domed structures.  
           [0006]    Another object of the invention is a method of demolishing domed structures using sides of the structure to assist in the demolition.  
           [0007]    A still further object of the invention is a method of demolishing domed structures that utilize a pivoting mechanism or hinge.  
           [0008]    One other object is modified domed structure that employs the hinge or pivoting mechanism as a part thereof.  
           [0009]    Other objects and advantages of the present invention will become apparent as a description thereof proceeds.  
           [0010]    In satisfaction of the foregoing objects and advantages, the invention includes both a method of demolition and a domed structure configured for such demolition.  
           [0011]    In the method aspect of the invention, the method is an improvement in demolishing a structure using explosives, the improvement comprising forming a pivoting mechanism in a wall portion of the structure to direct the structure along a predetermined fall line. More particularly, the method entails the steps of segmenting a dome of the domed structure and forming a pivoting mechanism in side walls of the domed structure along a reaction line. Openings are formed in opposing wall portions, one wall portion facing a direction of intended fall. Support portions of the one wall portion are removed using explosives to rotate the domed structure about the reaction line and the pivoting mechanism to demolish the domed structure. The pivoting mechanism can be a roller cam or a hinge and the removal of portions of the remaining dome-supporting wall using explosives can be done after the domed structure has begun to rotate. For example, explosive charges can be placed vertically in the remaining wall portion as part of the demolition.  
           [0012]    Water can be applied to all or part of the domed structure during, before and/or after use of the explosives and the dome can be segmented radially, if desired. Preferably, the domed structure is a nuclear reactor, but other structures can be subjected to the inventive process.  
           [0013]    Prior to demolition, one or more materials may be wrapped around a portion or all of the domed structure and backfill can be added to the domed structure base, if necessary.  
           [0014]    The invention also includes the domed structure as modified for demolition, wherein the domed structure has a domed roof and a roof supporting wall. The improvement in these structures is the existence of a hinge or pivoting arrangement positioned in the wall, the hinge arrangement adapted to rotate the domed structure along a reaction line for demolition purposes.  
           [0015]    The hinge can be a roller cam mechanism or use opposing arcuate hinge surfaces formed in the wall. Legs can be formed in the wall down from the hinge arrangement, removal thereof assisting in rocking of the structure. Other openings can be made in the dome to facilitate is demolition such as in the wall to facilitate its demolition.  
           [0016]    Another method aspect of the invention includes identifying a first side portion toward which a dome of the domed structure will fall and segmenting the dome portion. Then, a plurality of openings are formed in the first side portion, the forming step leaving a leg between adjacent openings. A through slot is formed in a second side portion opposite said first side portion, and a pivoting mechanism is formed either as part of remaining side portions of the dome or as a separate structure. The legs are demolished so that the remaining side portions pivot toward the first side portion so that said dome structure can collapse. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    Reference is now made to the drawings of the invention wherein:  
         [0018]    [0018]FIG. 1 is a schematic representation of a typical domed structure for a nuclear power plant;  
         [0019]    [0019]FIG. 2 is a diagram showing a demolition fall line for a domed structure;  
         [0020]    [0020]FIG. 3 is a schematic representation of a domed structure configured for demolition according to the invention;  
         [0021]    [0021]FIG. 3A shows an enlarged side view of an alternative hinge arrangement;  
         [0022]    [0022]FIG. 4 is a schematic view of the domed structure of FIG. 3 in a partial demolition state;  
         [0023]    [0023]FIG. 4A is a schematic view of the dome structure of FIG. 3 in a more advanced partial demolition state;  
         [0024]    [0024]FIG. 5 is a schematic view of a demolished domed structure using one mode of the invention;  
         [0025]    [0025]FIG. 6 is a schematic view of prepared domed structure for demolition with an alternative hinge configuration; and  
         [0026]    [0026]FIG. 7 is a schematic view of the domed structure of FIG. 6 in a partially demolished state. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    The present invention is a significant advance in the demolition of buildings, particularly domed structures for nuclear power plants reactors.  
         [0028]    Referring to FIGS.  1 - 5 , one mode of the inventive method is depicted that employs a domed structure  10  for demolition. Although the domed structure can be any type, a typical domed structure would be a nuclear power plant reactor. These structures are quite massive and can be 144 feet in diameter, have a dome height of 70 feet, and have an above ground elevation of 148 feet, a total structure height of around 170 feet, see FIG. 1.  
         [0029]    The structure  10  has a dome  1 , a cylindrical wall  3 , and a foundation/base walls  4 . The cylindrical wall  3  and dome  1  are generally constructed with a steel liner and an overcoating of concrete. Many times, the steel liner has studs extending outwardly so that the concrete has additional anchoring surfaces for bonding to the liner.  
         [0030]    A first step in demolishing the structure  10  is to fill the base with a backfill  5  so that the debris is at grade for removal. The use of the backfill may be optional if the domed structure does not extend below grade.  
         [0031]    Next, a number of operations are employed to configure the structure for a fall along a specified direction or fall line. First and as shown in FIG. 2, a fall line “A” passing through the center “C” of the dome is determined. The fall line also defines a reverse fall line “B” and a line “D” that is perpendicular to the fall line and passing through center “C”. Next, a reaction line “E” is sited behind line D. The reaction line is the line on which the dome will pivot and fall in the direction of fall line “A.” 
         [0032]    Referring to FIGS. 1 and 3, and once the reaction line is identified, a pair of pivoting mechanisms or hinges  7  (only one shown) are formed in each side of the wall  3  of the structure. The hinges  7  are formed by making a pair of arcuate cuts through the wall  3 . A straight cut  11  is also made in the wall portion  13  which is opposite the wall portion  15 , and which spans between the two hinges  7 . The outer surface of the wall portion  15  faces the fall line “A.” Shims or the like (not shown) can be used to prop up the wall portion  17 , if desired. It should be understood that the cutting or severing can be done by any known means, such as a wire saw, thermal means, or combinations of different means.  
         [0033]    Referring to FIG. 3A, the pivoting mechanism or hinge  7  can be strengthened by interposing steel plates  21  and  23  between the concrete surfaces  25  and  27 . This forms a stronger and more crush-resistant hinge. The steel plates can be modified with studs  29  and a grout layer  31  for bonding to the concrete surfaces as well.  
         [0034]    The hinges could have any dimension depending on the size of the domed structure, e.g., a 4 foot or even a 10 foot radius.  
         [0035]    Referring to FIG. 3 again, once the hinges  7  are formed and the wall portion  13  is severed, a number of through openings  33  are made in the wall portion  15  by cutting, etc. The openings would be made by removal of both the concrete and steel, but the concrete could be removed and the steel could be merely cut to follow the opening shape formed by the concrete removal. Formation of the openings  33  creates a number of legs  35  that span the side between the two hinges  7 . The height of the openings is sufficient so that an eccentric load is created, and should extend beyond the elevation of the line  11 .  
         [0036]    The dome  1  is also segmented or severed along the lines  39  using a wire saw or the like to form dome segments  41 . Preferably, the cut goes through both the steel liner and the concrete outer shell, but just the concrete could be severed. If the steel liner cannot be cut, explosives could be used to cut the steel liner in several predetermined places to facilitate dome segment separation. This radial precutting permits the dome to stand safely while the overall dome is in its original position. However, the pre-cut dome parts would come apart on explosion. Explosives could also be placed with the dome segments  41  to assist their separation.  
         [0037]    Then, explosive charges are placed on the legs  35  to remove them. The explosives can be placed by first drilling horizontal holes into or through the legs  35  and placing the explosives in the holes. Of course, other shaped openings can be employed, e.g., vertical or diagonal slots or through holes, and the like. The explosives are then detonated to remove the legs  35 . Once the legs  35  are blasted out, an eccentric load is formed as shown in FIGS. 4A and 4B whereby the dome  1  and remainder of wall  15  and wall  13  rotate or pivot about the reaction line and hinges  7 .  
         [0038]    Referring now to FIG. 4, another option is to vertically place explosives in the side wall portions  13  and  15  around a periphery of the structure  10 , including if desired above the hinges  7  to assist the demolition. The explosives could be placed in holes  43  in the wall  3  that are positioned vertically, but the holes could take on other configurations, e.g., horizontal, diagonal, or in various combinations thereof if desired. As the dome  1  rotates, the explosives could be detonated to demolish the structure  10  as shown in FIG. 5, wherein the dome segments  41  as well as wall segments  45  collapse along the fall line “A”. This step, although optional, would better assure that the dome structure does not merely rotate to the position shown in FIG. 4A and come to rest without separation of the dome segments  41 . FIG. 4A is shown with the openings  43  but as though explosives were not employed to assist in demolition of the wall  3  of the structure  10 .  
         [0039]    [0039]FIG. 6 shows an alternative eccentric load creating configuration  50 . In this embodiment, roller cams  51  are used (one shown) rather than the hinges  7 . Each roller cam  51  has a cut line  53  similar to line  11  in FIG. 3. The cut line  53  and remaining opening or notch  54  leave a cam surface  57  as part of the wall  3 , which allows the dome structure  10  to rotate. In this embodiment, the pivoting mechanism is formed out of the side portion such that the roller cam acts as the pivot, whereas the hinge of FIG. 3 is formed in the side portion such that the two opposing surfaces co-act during rotation of the structure.  
         [0040]    After the openings  33  are made in the wall  15  to leave legs  35 , and the legs are removed using explosives, the remaining structure  10  will rotate as shown in FIG. 7. The blasting of the remaining wall structure can be done as is explained above and shown in FIGS. 4, 4A and  5 .  
         [0041]    One advantage that the roller cam design has is that it avoids the problem of the hinges binding before the dome structure rotates. With the roller cam design, the space formed by the notch  54  eliminates any surface that could interfere with the cam surface  57  during rotation.  
         [0042]    Control of the falling of debris can be achieved by the use of protective netting or mats. Plastic or metal fencing, curtains of woven materials like wire, cable, rope, curtains of non-woven materials such as spun bound polypropylene geotextile fabric or other types of materials can be suspended or placed in front or around the structure to be demolished. These materials can be used alone or in combination, e.g., a double wrap of chain link fence, with a double wrap of geotextile fabric around the fence.  
         [0043]    It should be understood that the explosives for use in the domed structure demolition are all well known in the art and a further explanation is not deemed necessary for understanding of the invention.  
         [0044]    Vibration that occurs during the demolition process can be mitigated by the use of cushioning materials placed in the appropriate areas when material are to fall, e.g., in the fall line, around the periphery of the structure, within the periphery of the structure, etc. The materials can be any type suitable to consume the energy existing in the descending debris, e.g., sand or other particulate material.  
         [0045]    Since dust is always a problem in the demolition of buildings, dust suppression and/or collection steps can be taken before, during, and/or post demolition. One technique would include covering or layering the explosive charges with water containers such as hoses, bags, vessels or the like. Upon detonation, the water in the containers would suppress dust generated and assist in controlling of flying debris from the detonation.  
         [0046]    An alternative technique involves the use of a wet layer of flexible material such as a geotextile fabric placed over the structure, i.e., a wet blanket.  
         [0047]    Another alternative is to create hydraulic envelope around the structure and its fall area. In this technique, water is sprayed in the vicinity of the structure. The water can be augmented with additives that would reduce its surface tension such as surfactants. This would permit the formation of smaller water droplets and more efficiently wet down airborne particulate matter. In place of water, a superheated steam could be employed. The use of superheated steam should result in the production of a fog bank or fog-bank like environment due to the steams geometrical expansion when contacting lower temperature air.  
         [0048]    The different dust suppression and elimination techniques can be combined together in various fashions to augment each other. Moreover, filtering and/or collection systems can be employed when using water so that any objectionable material entrained in the water or mist can be recovered without contaminating the environment.  
         [0049]    As such, an invention has been disclosed in terms of preferred embodiments thereof which fulfills each and every one of the objects of the present invention as set forth above and provides a method for demolishing domed structures and a modified dome structure to achieve such demolition.  
         [0050]    Of course, various changes, modifications and alterations from the teachings of the present invention may be contemplated by those skilled in the art without departing from the intended spirit and scope thereof. It is intended that the present invention only be limited by the terms of the appended claims.