WO1997031378A1

WO1997031378A1 - Wall system and bricks for shielding generated radiation

Info

Publication number: WO1997031378A1
Application number: PCT/US1997/003339
Authority: WO
Inventors: Michael Allen Rollor; Timothy Alan Carraway; James Noah Taylor
Original assignee: Alaron Corp
Current assignee: Alaron Corp
Priority date: 1996-02-26
Filing date: 1997-02-26
Publication date: 1997-08-28
Anticipated expiration: 1998-08-26

Abstract

A shielding wall system for containing generated radiation. A plurality of bricks form a lower row and an upper row. An upper brick is stacked with respect to a lower brick. Each brick has a top and a bottom. In a stacked position of an upper brick with respect to a lower brick, a top of the lower brick abuts a bottom of the upper brick. The top of the lower brick has generally planar top faces which are angled with respect to each other. The bottom of the upper brick has generally planar bottom faces which are angled with respect to each other. In the stacked position of the upper brick with respect to the lower brick, the top faces of the lower brick matingly abut at least a portion of corresponding bottom faces of the upper brick.

Description

WALL SYSTEM AND BRICKS FOR SHIELDING GENERATED RADIATION

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

This invention relates to a wall system and differently shaped individual bricks of the wall system which can be interconnected or interlocked to geometrically shield or block radiation rays emitted from a generator.

DESCRIPTION OF PRIOR ART

Conventional wall shielding which is used to block radiation is typically constructed of lead material. Lead wall components are extremely heavy and very awkward to transport, construct and dismantle. Regardless of the level of contamination of the lead shielding, when removal is required the entire lead wall must be dismantled. Each lead component must then be transported, properly treated for decontamination and stored.

There is an apparent need for a shielding wall system that can be easily constructed from relatively smaller and lighter wall components, such as wall bricks. However, even with smaller and lighter wall components there remains a need to properly shield alpha, beta and gamma rays emitted from a radiation generator.

SUMMARY OF THE INVENTION

It is one object of this invention to provide a wall system constructed of multiple individual interlocking bricks which can be easily transported and set into position.

It is another object of this invention to provide differently shaped individual bricks that interlock in a vertical stacking direction to form a shielding wall system.

It is another object of this invention to provide differently shaped individual bricks that interlock in a longitudinal direction, along a row of bricks, to form a shielding wall system.

The above and other objects of this invention are accomplished with differently shaped individual bricks that can be stacked and positioned with respect to each other to form a shielding wall system that effectively blocks or shields alpha, beta and or gamma rays of radiation. In one preferred embodiment according to this invention, a floor surface is used to support a constructed wall system. A course of base bricks are set as a lowermost row. One upper row of bricks are then stacked upon the lowermost row of bricks. Depending upon the particular wall height desired, additional upper rows of bricks can be vertically stacked to attain the desired height.

In order to achieve stacking and shielding capabilities, a top of each brick of a lower row preferably has two generally planar top faces that are angled with respect to each other. In a corresponding fashion, each brick of the upper row which is stacked upon a brick of the lower row has a bottom which includes two generally planar bottom faces that are angled with respect to each other. Each brick preferably has a generally inverted V-shape. In a stacked position of the upper brick with respect to the lower brick, top faces of the lower brick matingly abut corresponding bottom faces of the upper brick.

Each brick of the lowermost row preferably has enough of a generally planar bottom surface to contact a floor surface, for example, and sufficiently support the wall system. The uppermost row of bricks can have either two top faces which are angled with respect to each other or one generally planar surface that is suitable for abutting an upper structure, such as a ceiling or other suitable framework. In one preferred embodiment according to this invention, side surfaces of the bricks are generally planar. Thus, the constructed wall system preferably has a generally planar overall surface.

Each brick according to this invention can be constructed of Radioactive Scrap Metal (RSM), such as waste metal from a radioactive generator. Recycling processes for decontaminating radioactively contaminated materials are known to those skilled in the art. For example U.S. Patents 4,828,759, 4,933,113, Re. 34,613 and 5,340,505 teach radioactive decontamination processes that produce recycled metals or other recycled materials which contain acceptable levels of radiation.

The bricks according to this invention can be constructed of radiation- containing recycled metal. After a constructed wall system of this invention is exposed to radiation over a certain time period and a predetermined level of radiation is detected within the bricks, the wall system of this invention can be quickly and easily dismantled. The bricks of this invention are relatively lightweight and easy to transport. The contaminated bricks can then be passed through a suitable decontamination and recycling process. Depending upon the structural deterioration of the decontaminated brick structures, the bricks can either be reused or melted down and again poured into molds that produce recycled bricks with original dimensions. Because the bricks of this invention can be continuously recycled for decontamination purposes, the amount of radioactive waste remaining after each recycling process is significantly reduced, along with the associated recycling and disposal costs. BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and objects of this invention will be better understood from the following detailed description taken in conjunction with the drawings wherein:

Fig. 1 is a perspective view of three adjacent wall systems constructed to form a shielding enclosure, according to one preferred embodiment of this invention;

Fig. 2 is a perspective exploded view of a lowermost row containing a plurality of base bricks, according to one preferred embodiment of this invention;

Fig. 3 is a perspective partially exploded view of an upper row of bricks and their relationship with respect to a lowermost row of bricks, according to one preferred embodiment of this invention;

Fig. 4 is a perspective, partially exploded view showing another upper row of bricks and their relationship with respect to two lower rows of assembled bricks, according to one preferred embodiment of this invention;

Fig. 5 is a perspective view of the wall system shown in Fig. 4, in an assembled condition;

Fig. 6 is a schematic front view of a wall system having five rows of bricks, and a radiation generator, according to one preferred embodiment of this invention;

Fig. 7 is a perspective view of a standard base brick, according to one preferred embodiment of this invention;

Fig. 8 is a front view of the standard base brick, as shown in Fig. 7;

Fig. 9 is a back view of the standard base brick, as shown in Fig. 7;

Fig. 10 is a top view of the standard base brick, as shown in Fig. 7;

Fig. 11 is a bottom view of the standard base brick, as shown in Fig. 7;

Fig. 12 is a side view of the standard base brick, as shown in Fig. 7; Fig. 13 is a side view of the standard base brick, opposite the side view shown in Fig. 12;

Fig. 14 is a perspective view of a male base brick, according to one preferred embodiment of this invention;

Fig. 15 is a front view of the male base brick, as shown in Fig. 14;

Fig 16 is a back view of the male base brick, as shown in Fig. 14; Fig 17 is a top view of the male base brick, as shown in Fig. 14; Fig 18 is a bottom view of the male base brick, as shown in Fig. 14; Fig 19 is a side view of the male base brick, as shown in Fig. 14; Fig 20 is a side view of the male base brick, opposite the side view shown in

Fig. 19;

Fig. 21 is a perspective view of a female base brick, according to one preferred embodiment of this invention;

Fig. 22 is a front view of the female base brick, as shown in Fig. 21;

Fig. 23 is a back view of the female base brick, as shown in Fig. 21;

Fig. 24 is a top view of the female base brick, as shown in Fig. 21;

Fig. 25 is a bottom view of the female base brick, as shown in Fig. 21;

Fig. 26 is a side view of the female base brick, as shown in Fig. 21;

Fig. 27 is a side view of the female base brick, opposite the side view shown in Fig. 26;

Fig. 28 is a perspective view of a standard wall brick, according to one preferred embodiment of this invention;

Fig. 29 is a front view of the standard wall brick, as shown in Fig. 28;

Fig. 30 is a back view of the standard wall brick, as shown in Fig. 28;

Fig. 31 is a top view of the standard wall brick, as shown in Fig. 28;

Fig. 32 is a bottom view of the standard wall brick, as shown in Fig. 28;

Fig. 33 is a side view of the standard wall brick, as shown in Fig. 28;

Fig. 34 is a side view of the standard wall brick, opposite the side view shown in Fig. 33; Fig. 35 is a perspective view of a male wall brick, according to one preferred embodiment of this invention;

Fig. 36 is a front view of the male wall brick, as shown in Fig. 35;

Fig. 37 is back view of the male wall brick, as shown in Fig. 35;

Fig. 38 is a top view of the male wall brick, as shown in Fig. 35;

Fig. 39 is a bottom view of the male wall brick, as shown in Fig. 35;

Fig. 40 is a side view of the male wall brick, as shown in Fig. 35;

Fig. 41 is a side view of the male wall brick, opposite the side view shown in Fig. 40;

Fig. 42 is a perspective view of a female wall brick, according to one preferred embodiment of this invention;

Fig. 43 is a front view of the female wall brick, as shown in Fig. 42;

Fig. 44 is a back view of the female wall brick, as shown in Fig. 42;

Fig. 45 is a top view of the female wall brick, as shown in Fig. 42;

Fig. 46 is a bottom view of the female wall brick, as shown in Fig. 42;

Fig. 47 is a side view of the female wall brick, as shown in Fig. 42; and

Fig. 48 is a side view of the female wall brick, opposite the side view shown in Fig. 47.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Fig. 1 , an enclosure for shielding generated radiation, according to one preferred embodiment of this invention, comprises three modular self-supported sections of wall system 55. Figs. 2-5 show simplified method steps for assembling the first three rows of bricks of one wall section.

Fig. 2 shows the first lower row 57 in an exploded view. Lower row 57 is shown as the lowermost row in each of the wall sections of Fig. 1. As shown in Figs. 1 and 2, lower row 57 preferably comprises one male base brick 62 and one female base brick 63, such as at opposing ends of lower row 57. Although not required, one or more standard base bricks 61 are preferably positioned between male base brick 62 and female base brick 63. The number of standard base bricks 61 is a function of the length, from front 80 to back 82 of each of base bricks 61-63, as well as the desired length of wall system 55. In an extreme arrangement, only one base brick 61 can be used to construct lower row 57 if the overall length of base brick 61 is equal to the desired length of wall system 55. However, one advantage of wall system 55 according to this invention is to build a relatively long and high wall system 55 with multiple relatively lightweight bricks that can be easily transported, set and dismantled.

Fig. 3 shows upper row 58 in an exploded view and positioned above an assembled lower row 57. Fig. 4 shows a second upper row 58, exploded, and how it is constructed with respect to a first upper row 58, assembled. The second upper row 58 is similar to the first upper row 58, except that the angle from front 80 to back 82, as described in more detail below, is preferably reversed with each alternating row of bricks, as clearly shown in Figs. 3 and 4.

Fig. 5 shows three fully constructed rows of bricks, according to one preferred embodiment of this invention. As shown in Fig. 5, the end face of wall system 55 is generally flat. A relatively flat end face is not essential to wall system 55 of this invention but is preferred to eliminate safety hazards associated with exposed edges and sharp corners, of standard base bricks 61 and standard wall bricks 64, such as those shown in Figs. 7 and 28, respectively, that would result from stacking only standard base bricks 61 and standard wall bricks 64. Furthermore, wall system 55 as shown in Figs. 1 and 5 is more aesthetically pleasant.

Fig. 6 shows a schematic diagram of radiation source 56 which may emit alpha, beta and/or gamma rays. One purpose of wall system 55 is to shield such rays emitted from radiation source 56. The thickness of wall system 55, as measured from side 84 to side 86 of the stacked bricks is sufficient to provide required shielding. At the joints where the bricks interlock, particular geometries such as angles of top faces 73, bottom faces 77, front faces 81 and/or back faces 83, as discussed in more detail below, of the bricks prevent radiation rays from passing through wall system 55.

As used throughout this specification and in the claims, the terms lower row and upper row are relative to each other. For example as shown in Figs. 5 and 6, male base brick 62 is set within the lowermost row of wall system 55. The first upper row 58 of bricks positioned adjacently above lower row 57 can be considered an upper row. However, the first upper row 58 of bricks just below the second upper row 58, for example, can be considered a lower row with respect to the second upper row 58 but may also be considered an upper row with respect to lower row 57 positioned below the first upper row 58 of bricks.

As shown in Figs. 1-5, wall system 55 preferably comprises a plurality of bricks which form lower row 57 and at least one upper row 58. Each of wall bricks 64-66 of upper row 58 are stacked with respect to corresponding base bricks 61-63 of lower row 57. The vertical joint between bricks is preferably but not necessarily staggered. The staggered arrangement as shown in Fig. 5, for example, provides additional wall strength and shielding.

As clearly shown in Figs. 7-48, each of base bricks 61-63 and wall bricks 64- 66 comprise top 72, bottom 76, front 80, back 82 and opposing sides 84 and 86. For example, top 72 of standard base brick 61 is shown in Fig. 2 and has two top faces 73. As used throughout this specification and in the claims the term top is intended to relate to the structure which is shown in a corresponding top view of the drawings, and likewise for the terms bottom, front, back and side. For example, top 72 of standard wall brick 64 is shown in the top view of Fig. 10.

In a stacked position of a brick of upper row 58 with respect to a brick of lower row 57, for example, top 72 of the lower brick abuts bottom 76 of the upper brick, such as clearly shown in Fig. 5. In one preferred embodiment according to this invention, top 72 of the lower brick has a plurality of generally planar top faces 73, such as shown in Figs. 8, 10, 29 and 31. Bottom 76 of the upper brick has a plurality of generally planar bottom faces 77. As clearly shown in Figs. 28-30, for example, two bottom faces 77 are angled with respect to each other. In the stacked position of the upper brick with respect to the lower brick, top faces 73 of the lower brick matingly abut at least a portion of, preferably substantially all of, corresponding bottom faces 77 of the upper brick. Top 72 and/or bottom 76 can also have more than two top faces 73 and/or more than two bottom faces 77, respectively, as long as certain corresponding faces matingly abut to provide adequate structural strength and shielding for wall system 55.

As used throughout this specification and in the claims, the phrase matingly abutting is intended to relate to a theoretically contiguous relationship between top face 73 of the lower brick and a corresponding bottom face 77 of the upper brick. The intended result of stacking an upper brick with respect to a lower brick in a matingly abutting manner is to provide sufficient structural contact or support between the upper brick and the lower brick as a function of the desired height of wall system 55, and to reduce gaps between adjacent bricks in an effort to more completely shield radiation rays and to prevent such radiation rays from passing through wall system 55. From a practical standpoint it is apparent that manufacturing tolerances or particular design conditions would result in an incomplete contiguous relationship and the phrase matingly abutting is intended to include such arrangement.

Although portions of this specification may refer either to one or to a plurality of either base bricks 61-63 or wall bricks 64-66, it is apparent that one or more bricks can be used in each row of bricks. Also, when referring to features of bricks as shown in Figs. 7-48, it is apparent that many geometrical features are common between various bricks 61-69 and by referring to a feature of one particular brick it is intended that the specification also refer to similar features of other bricks.

As clearly shown in Figs. 1-3, lower row 57 has a plurality of base bricks 61- 63 comprising a plurality of standard base bricks 61 longitudinally interlocked between one male base brick 62 and one female base brick 63. Each of base bricks 61-63 preferably comprises a generally planar bottom surface 78. As shown in Figs. 8, 9, and 11-13, bottom surface 78 forms one generally planar surface. However, it is apparent that bottom surface 78 can have grooves or cutout sections that may interrupt an otherwise completely planar surface. The importance of bottom surface 78 is to provide enough bearing surface area to adequately support base bricks 61-63 and wall bricks 64-66 stacked upon such base bricks 61-63. Furthermore, if base bricks 61-63 are not positioned upon a relatively flat surface, such as a floor surface, but are supported by another suitable structural member, it is apparent that bottom face 77 can be modified to accommodate any other suitable structural support member. For example, wall system 55 may be framed with steel structural support members. With such steel structural support members, it is possible to support wall system 55 above or with respect to but not necessarily upon a ground or floor surface. Throughout this specification and in the claims the phrase generally planar is intended to relate to surfaces which have an overall planar configuration in the macrostructure sense. Included within the phrase generally planar are surfaces that have microstructures which are relatively rough and porous, such as those surfaces of metals, concrete and other similar materials. The phrase generally planar as used throughout this specification and in the claims is intended to include even an irregularly shaped microstructure.

In one preferred embodiment according to this invention, the remaining upper rows 58 comprise wall bricks 64-66 and/or cap bricks 67-69. As clearly shown in Figs. 28-30 and 32, bottom faces 77 are angled with respect to each other. The particular angle between bottom faces 77 can vary. The dimensions of each face of the brick can vary depending upon the particular intended use. Regarding standard base brick 61 as shown in Figs. 7-13 and standard wall brick 64 as shown in Figs. 28-34, front faces 81 are angled with respect to each other and back faces 83 are angled with respect to each other, for both an interlocking purpose and a shielding purpose. The interlocking feature provides more structural integrity and strength to wall system 55. The angled feature also prevents radiation rays from passing through wall system 55. The angle between bottom faces 77 and top faces 73, generally referred as an apex angle, can be varied along with the dimensions of bottom face 77 and top face 73, so that even without the angular relationship between front faces 81 and between back faces 83, adequate shielding can be provided. For example, side faces 85 and 87 of an upper brick can extend low enough to interfere with a line taken from the radiation source to a longitudinal horizontal joint formed between an upper brick and a lower brick.

As shown in Figs. 31 and 32, angle θ between front faces 81 is approximately 270° and angle Ω between back faces 83 is approximately 90°. Such angles can be significantly varied while still accomplishing the desired results of this invention, such as the shielding and interlocking capabilities. Likewise, as shown in Figs. 29 and 30, angle μ between top faces 73 is approximately 270° and angle Φ between bottom faces 77 is approximately 90°. Again, such angles can be significantly varied and still accomplish the same desired results of this invention.

As shown in Figs. 7-13, standard base brick 61 has both front 80 and back 82 with angled front faces 81 and angled back faces 83, respectively. As shown in Figs. 14-20, male base brick 62 has angled front faces 81 but a generally planar surface for back 82. As shown in Figs. 21-27, female base brick 63 has angled back faces 83 but a generally planar surface for front 80.

As shown in Figs. 28-34, standard wall brick 64 has angled front faces 81, angled back faces 83, as well as angled top faces 73 and angled bottom faces 77. As shown in Figs. 35-41, male wall brick 65 has angled front faces 81, angled top faces 73 and angled bottom faces 77 but a generally planar surface for back 82. As shown in Figs. 42-48, female wall brick 66 has angled back faces 83, angled top faces 73 and angled bottom faces 77 but a generally planar surface for back 82.

As shown in Fig. 1, cap bricks 67-69 of uppermost upper row 58 have a generally planar top surface 74 which can be used adjacent a ceiling structure or any other suitable frarning structure which is not shown in Fig. 1. Top surface 74 of such cap bricks 67- 69 is preferably similar to bottom surface 78 of base bricks 61-63, as discussed above and shown in the drawings. Although detailed drawings of cap bricks 67-69 are not included with the drawings associated with this specification, standard cap brick 67, male cap brick 68 and female cap brick 69, as generally shown in Fig. 1, have bottoms 76 which are similar to bottoms 76 of standard wall brick 64, male wall brick 65 and female wall brick 66, respectively.

As shown in Figs. 7-48, side faces 85 and 87 of each brick preferably have cutout areas 88 as means for individually lifting the corresponding brick. Lift tool 89, as shown in Fig. 1, can be used to lift a brick by inserting prongs of lift tool 89 within cutout areas 88. Because lift tool 89 pivots about an axis where one arm is pivotally connected to another arm of lift tool 89, when in use the gravitational weight of the brick retains the prongs within cutout areas 88. By lifting handles of lift tool 89, as shown in Fig. 1, individual bricks can be easily transported and set into position.

The method for constructing wall system 55, according to one preferred embodiment of this invention, begins with setting a course of base bricks 61-63, such as lower row 57 as shown in Fig. 2. After base bricks 61-63 are set within lower row 57, wall bricks 64-66 can be used to construct a first upper row 58. Additional upper rows 58 can be added until the desired vertical height is attained. Many different custom wall constructions can be assembled from various wall systems 55. For example, wall system 55 according to this invention can be used for shielding windows and other similar frames, glove ports, doors and other similar frames, and the like.

Each brick is preferably constructed of decontaminated and recycled Radioactive Scrap Metal (RSM). Once the bricks of wall system 55 are surface contaminated, each brick can be surface decontaminated and recycled at relatively minimal costs. By recycling materials used to construct each brick, the volume and thus cost associated with radioactive waste disposal is significantly reduced.

While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.

Claims

WE CLAIM:

1. A shielding wall system for containing generated radiation, the shielding wall system comprising: a plurality of bricks, a lower row and an upper row of said bricks, a first brick of said bricks of said upper row stacked with respect to a second brick of said bricks of said lower row; each said brick having a top and a bottom, in a stacked position of each said first brick with respect to said second brick said top of said first brick abutting said bottom of said second brick; and said top of said first brick having a plurality of generally planar top faces, said top faces angled with respect to each other, said bottom of said second brick having a plurality of generally planar bottom faces, said bottom faces angled with respect to each other, and in said stacked position said top faces of said first brick matingly abutting at least a portion of corresponding said bottom faces of said second brick.

2. A shielding wall system according to Claim 1 wherein said rows include a lowermost row having a plurality of said first bricks, and each of said first bricks of said bottom row comprises a generally planar bottom surface.

3. A shielding wall system according to Claim 2 wherein said bottom surface matingly abuts a supporting surface of a structure.

4. A shielding wall system according to Claim 2 wherein a front of at least one of said first bricks of said lowermost row has a plurality of generally planar front faces, and said front faces are angled with respect to each other.

5. A shielding wall system according to Claim 4 wherein a back of at least one of said first bricks of said lowermost row has a plurality of generally planar back faces, and said back faces are angled with respect to each other.

6. A shielding wall system according to Claim 2 wherein a back of at least one of said first bricks of said lowermost row has a plurality of generally planar back faces, and said back faces are angled with respect to each other.

7. A shielding wall system according to Claim 1 wherein said rows include an uppermost row, and each said second brick of said uppermost row comprises a generally planar top surface.

8. A shielding wall system according to Claim 7 wherein said top surface matingly abuts a supporting surface of a structure.

9. A shielding wall system according to Claim 7 wherein a front of at least one of said second bricks of said uppermost row has a plurality of generally planar front faces, and said front faces are angled with respect to each other.

10. A shielding wall system according to Claim 9 wherein a back of at least one of said second bricks of said uppermost row has a plurality of generally planar back faces, and said back faces are angled with respect to each other.

11. A shielding wall system according to Claim 7 wherein a back of at least one of said second bricks of said uppermost row has a plurality of generally planar back faces, and said back faces are angled with respect to each other.

12. A shielding wall system according to Claim 1 wherein opposing sides of said bricks each have a generally planar side face.

13. A shielding wall system according to Claim 1 further comprising lift means for individually lifting a corresponding said brick.

14. A shielding wall system according to Claim 13 wherein said lift means comprise opposing sides of said bricks each having a generally planar side face, and each said side face having a cutout area that accommodates a prong of a lift tool.

15. A stackable shielding wall brick for a wall system, the shielding wall brick comprising: a top and a bottom, said top having a plurality of generally planar top faces, said top faces angled with respect to each other, said bottom having a plurality of generally planar bottom faces, and said bottom faces angled with respect to each other.

16. A shielding wall brick according to Claim 15 further comprising a front of said wall brick having a plurality of generally planar front faces, and said front faces angled with respect to each other.

17. A shielding wall brick according to Claim 16 further comprising a back of said wall brick having a plurality of generally planar back faces, and said back faces angled with respect to each other.

18. A shielding wall brick according to Claim 15 further comprising a back of said wall brick having a plurality of generally planar back faces, and said back faces angled with respect to each other.

19. A shielding base brick for a wall system, the shielding base brick comprising: a top and a bottom, said top having a plurality of generally planar top faces, said top faces angled with respect to each other, and said bottom having a generally planar bottom surface.

20. A shielding base brick according to Claim 19 further comprising a front having a plurality of generally planar front faces, and said front faces angled with respect to each other.

21. A shielding base brick according to Claim 20 further comprising a back having a plurality of generally planar back faces, and said back faces angled with respect to each other.

22. A shielding base brick according to Claim 19 further comprising a back having a plurality of generally planar back faces, and said back faces angled with respect to each other.

23. A shielding cap brick for a wall system, the shielding cap brick comprising: atop and a bottom, said bottom having a plurality of generally planar bottom faces, said bottom faces angled with respect to each other, and said top having a generally planar top surface.

24. A shielding cap brick according to Claim 23 further comprising a front having a plurality of generally planar front faces, and said front faces angled with respect to each other.

25. A shielding base brick according to Claim 24 further comprising a back having a plurality of generally planar back faces, and said back faces angled with respect to each other.

26. A shielding base brick according to Claim 23 further comprising a back having a plurality of generally planar back faces, and said back faces angled with respect to each other.