Patent Number: 052256855
Section: description

DESCRIPTION OF A PREFERRED EMBODIMENT A construction module for use in protecting personnel against emissions from radio active material includes a shaped member A suitable for assembly with other shaped members to form a shielding structure. The shaped members A are formed from suitable shielding material, such as concrete, water, sand or lead, capable of excluding passage of emissions from radio active material and having adjoining surfaces for reception closely adjacent complementary surfaces of other shaped members. A synthetic polymeric material B, having been formed by molding, engages and extends over an exterior surface of the shaped member forming a hardened coating layer which is sufficiently stiff for protecting the shielding material from contamination by exposure to radio active material and serving as a readily decontaminated surface to avoid exposure of personnel to emissions from radio active material. Thus, an encapsulated construction module is formed suitable for assembly as a structure to shield personnel and which is easily decontaminated avoiding exposure to emissions from radio active material. The structure further includes a joint construction for assembly of the modules wherein a full thickness of shielding material is afforded with full coverage of adjoining surfaces of respective modules by the hardened molded coating layer of synthetic polymeric material. For example, the structure at the joint may be formed by modules each having a bulbous arcuate adjoining portion C on one side, and a complementary arcuate end D on the other side. The bulbous portion has a recess accommodating a complementary end of an adjoining construction module. Alternatively the joint may be chevron shaped in cross section as illustrated at E. The hardened coating layer may be molded in situ upon the shielding material as by dipping or otherwise molding, depositing or forming, or preferably the hardened coating layer is first molded as a shape or form and then filled with shielding material. Referring more particularly to FIGS. 1-3, the shielding material is illustrated at A and is formed as a panel which includes a wire reenforcing member 10. A plurality of spaced lifter lugs are illustrated at 11 which have suitable legs 11a embedded in the concrete. It will be observed that a recess 12 has straight sides 12a and an arcuate interior 12b for accommodating the arcuate end D of the panel as is illustrated in FIG. 1. FIG. 4 illustrates a chevron construction E which has an end 13 with front 14 and top 15. Chevron like joints may be provided as shown or at the ends of the bricks wherein the chevron points in at a 45.degree. angle on one end and out at a 45.degree. angle at the other end. In FIG. 4 the shielding material A is provided in the form of lead as illustrated at 16. A complementary lower portion 17 is provided. Thus, the joint structure is an interengaging construction formed by opposing portions of adjacent modules. Preferably, the panels of FIGS. 1-3 and perhaps the brick of FIG. 4 may be constructed of concrete as a shielding material. The brick is illustrated as and may preferably be constructed of lead. The synthetic polymeric material is preferably a polyethylene polymer or other suitable thermoplastic tough polymeric material. Certain thermo-setting polymers may also be used. The hardened coating layer A may be formed in situ about concrete as by a suitable molding process such as rotational molding. It is preferable to construct a form utilizing the hardened coated layer as a relatively rigid container and then filling the container with shielding material thereby acting as a form for pouring in the shielding material and containing same while setting up. In the case of the brick of FIG. 4 the shielding material is lead and is poured into the formed hardened plastic coating layer which acts as a mold when filled with the molten lead. Rotational molding is a suitable molding technique wherein a hollow mold containing polymer powder is mounted on a rotational device and heated in an oven. The mold rotates on one or more axes. Heat fuses the polymer to the sides of the mold while rotation assures the proper distribution of the polymer to produce a mold or form of desired uniform thickness. After the mold is removed from the oven and cooled, it is separated from the polymer form. The mold is cleaned, refilled and reheated. The fabricated polymer form shape can be filled with whatever shielding media is most appropriate. Preferably the thickness of the plastic polymer encapsulation molding material will be from about 1/8 to 3/8 inches in order to provide sufficient rigidity and toughness. The shielding media thickness and material type may be varied depending upon the specific shielding requirements. Likewise, the molded polymer which encases the shielding media may also be varied in thickness and material type depending upon specific environmental conditions and requirements. The molded polymer protects the shielding media from adverse conditions and possible damage such as cracking and chipping due to impact with other objects. It also provides protection against elements such as liquid absorption. Since the molded polymer surface is very smooth, it can easily be wiped clean of liquids and other surface contaminants. While a clean, uncontaminated surface is safer for personnel, the molded polymer exterior further enhances safety by preventing contact with potentially hazardous shielding media such as lead. The shielding panel designs have a surface made of a polymer such as polyethylene encapsulating an interior filled with a shielding media. Depending on the user's requirements, the shielding media may be concrete, water, sand, lead pellets, solid lead, or another media. Reinforcement materials may be added to the media whenever necessary to provide additional strength or rigidity. For instance, reinforcement wire may be added to concrete media. The panels may be varied in height, length, and width to accommodate a range of site conditions. Bricks are also made of a molded polymer encasing a shielding media such as concrete, sand, water, lead pellets solid lead, or other media. They can be used to construct walls of various heights and lengths. The size and shape of the brick may be varied depending upon requirements. Such bricks made of sold lea encapsulated in molded polymer provide greater shielding protection than soft bricks or composite bricks and are safer than un-encapsulated solid lead. Other designs for bricks currently on the market include solid lead bricks with exposed lead surfaces, and composite bricks composed of a non-homogeneous mixture of lead pellets distributed throughout a plastic shape. The former design is impossible to decontaminate and exposes personnel to a hazardous material. The latter provides reduced shielding due to a reduction in density. While a preferred embodiment of the invention has been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.