Radiant energy – Radiation controlling means – Shields
Reexamination Certificate
2003-07-18
2004-12-28
Wells, Nikita (Department: 2881)
Radiant energy
Radiation controlling means
Shields
C250S519100, C141S010000, C141S066000, C141S097000
Reexamination Certificate
active
06835945
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to wall systems, and in particular, to modular wall systems made of a plurality of interconnecting, wall components.
2. Related Art
As the demand for electrical power increases around the world, the development and use of nuclear reactors also increases. Accordingly, workers at such nuclear power plants have a great need for portable wall systems that prevent or minimize radiation emanating from a nuclear reactor itself and/or from activation products resulting from reactor operation because the workers often must go into areas of high radiation to perform required maintenance, inspections or repairs. Workers use such shielding wall systems as a means for protecting a designated work area within a nuclear power plant in order for the workers to work within the protected or shielded area without the worry of being exposed to high levels of radiation. In addition, federally required inspections of nuclear power plants necessitate open access to critical areas within the plant. Therefore, there is a need for a shielding system that is easily portable from one location to another while shielding persons within the protected area from unwanted radiation.
Early prior art shielding systems included lead sheets and concrete blocks, but neither of these were easily portable from one location to another. As a result, several patents were issued in attempts to solve the non-portability of these prior art systems. In U.S. Pat. No. 4,090,087 to Weissenfluh, a radiation shield is disclosed having a bag filled with a liquid radiation attenuating material suspended from a mobile carrier. Although an arguable improvement over the early prior art, there are disadvantages with the '087 system. First, the system cannot fully protect an individual working behind the shield because the bag does not provide complete coverage. There are open areas on all sides of the bag between the mobile carrier and the bag as well as between the ground and the bag. Therefore, unwanted radiation will stream around the shield and compromise the area sought to be protected. The system continues in stating that the filler liquid can be any hydrogenous material which may have a boron compound as a neutron absorber. Therefore, if there is a shortage of such filler material, repairs, inspections, or other work may halt until such filler material is found and brought to the area. Third; the bags are hung from the mobile carrier, as shown in FIG.
11
. Thus, the heavy weight of the filler material may compromise the hooks or fasteners holding the bag in place. If the hooks happen to fail, the bag would fall to the ground, perhaps even burst open.
In U.S. Pat. No. 4,360,736 to Weissenfluh, a radiation shield is disclosed which improves upon the shielding system of the '087 system. Specifically, an improved bag is disclosed which has a means for connecting opposing walls of the bag, thereby ensuring a uniform thickness of the bag throughout its length when filled with a radiation attenuating liquid and hung on a mobile carrier. Despite this improvement to the bag, the radiation shielding system has the same disadvantages as described with the '087 system above.
In U.S. Pat. No. 4,362,948 to Weissenfluh, a radiation shield is disclosed being a freestanding container of a uniform thickness which is adapted to be used only with a radiation attenuating liquid. This shielding systems solves some of the problems with the prior '087 and '736 systems; however, it too has several disadvantages. First, the same problem exists in terms of having to use a radiation attenuating liquid. Second, the container has a fixed U-shape which cannot be altered according to the specific needs of the location sought to be protected. That is, if the target work area sought to be protected is in close proximity to walls, corners, stationary equipment, and the like, the pre-defined U-shape of the container may not work or fit within the confines of the target work area. Therefore, the '948 shielding system cannot be used.
In U.S. Pat. No. 4,504,739 to Weissenfluh, a method is disclosed for filling and emptying the shield system of the '948 patent. This method includes the introduction and emptying of both a gas and a radiation attenuating liquid to the container. Therefore, the same problem exists as with the other patented shielding systems described above.
Subsequent to these prior art patents, other commercially available shielding systems have been developed that use water as a filler material. However, as with the prior patented shielding systems, these conventional shielding systems all have a pre-defined shape such that each shape is targeted for a specific application. For example, there are hanging shields that operate as the container or bag of the '087 and '736 systems; there are U-shaped shields that operate as the free-standing container of '948 and '739 systems; and there are special form bags that conform to the exterior shape of a component piece of equipment, e.g., a section or intersection of pipes, and are intended to wrap and surround the target pipe or equipment.
The disadvantages with all of these prior art shield systems is that none of them are modular such that two or more components can be interconnected to form a unique shaped wall shielding system. By having predefined shapes, the use of the prior art shielding systems is limited. Therefore, there is a need for a portable and modular shielding system having component parts that interconnect to form a shielding wall of varying shapes and sizes.
Another disadvantage with the prior art shield systems is that there is no mechanism for interconnecting two or more shields while maintaining the shielding properties of the shields at the point of connection. For example, when placing two U-shaped shields next to each other in an attempt to protect a larger area, radiation may enter the protected area at the joint of the two adjacent shields. This is true whether the two shields overlapped each other (one placed in front of the other) or not. Therefore, there is a need for a portable and modular shielding system wherein two adjacent component shields maintain the integrity of the shield at their joint and prevent the protected area from seeing increased radiation levels.
Another prior art shielding system is shown in FIGS.
1
(A), (B) and
2
. In this system, a prior art shield component
100
is designed having a main container
112
with a first end
102
and a second end
104
. She first end
102
is a receiving end and the second end
104
is a locking end. Specifically, the second end
104
has a cross-sectional shape that is generally circular wherein the diameter of the second end
104
is equal to the width or thickness of the main container
112
. The first end
102
is concave in shape having a diameter and radius and is adapted to correspond to the generally circular shape of the cross section of the second end
104
, such that the radius of the first end
102
is equal to the radius of the second end
104
. In addition, the prior art shield component
100
is hollow so that it can be filled with any radiation attenuating material, e.g., water. Filling and draining of this prior art system is accomplished through an open port at the top of the shield section, making this an open system.
Using two or more prior art shield components
100
, a user can build a prior art shielding wall
200
as shown in FIG.
2
. For example, a first shield component
202
, having a first (or receiving) end
206
and a second (or locking) end
208
, is placed adjacent to a second shield component
204
, also having a first (or receiving) end
210
and a second (or locking) end
212
. As shown, the locking end
208
of the first shield component
202
is placed within the receiving end
210
of the second shield component
204
, thereby creating a conventional “ball and socket” joint. Once in the proper position, the first shield component
202
can be secu
Mossor David B
Seth Ernest
Leybourne James J.
Steptoe & Johnson PLLC
Wells Nikita
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