Patent Number: 043607365
Section: description

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a simplified showing of the relationship between a nuclear reactor vessel 10 and a surrounding primary shield 12. The primary shield 12 defines a reactor cavity 14. The walls of the primary shield 12 are spaced from the reactor vessel 10 to define an annular space 16 having an open upper end 18. The reactor vessel 10 has an annular ledge 20 which is adjacent to and radially inwardly disposed from an annular ledge 22 on the primary shield 12. The upper end 18 between the annular ledges 20 and 22 is spanned by a form of the radiation shield of this invention which is generally indicated by the number 24. It comprises a container 26 formed of a thin flexible material, such as rubber or plastic, filled with a radiation attenuating liquid 28. The radiation attenuating liquid 28 is preferably a hydrogeneous liquid. The liquid serves as a moderator and absorber for neutron radiation emanating from the reactor vessel 10. As shown in FIG. 2, the radiation shield 24 also comprises means 30 connecting opposing walls 32 and 34 of the container 26 to maintain the distance therebetween when the container 26 is filled with the radiation attenuating liquid 28. Since the radiation shield 24 is preferably collapsible for storage, the means 30 are preferably flexible, permitting the opposing walls 32 and 34 to approach each other when the container 24 is not filled with a radiation attenuating liquid. In the illustrated embodiment, the means 30 are drop stitches. FIG. 3 shows a second embodiment of the subject invention. In this embodiment, the radiation shield 36 is rectangular parallelepipedal in shape--that is, it is shaped like a water mattress. An intersecting grid of drop stitches 38 is provided to maintain the distance between the major walls of the container when it is filled with a radiation attenuating fluid--or, put another way, to prevent the major surfaces of the radiation shield from bulging. As is well known in the textile art, drop stiches are threads which extend between spaced pieces of fabric and are interlaced with the threads in the spaced pieces of fabric. FIG. 4 shows a third embodiment of the subject invention. In this embodiment, the radiation shield 40 has parallel walls 42 and 44 which are each initially formed from two plies of material joined (as by stitching, heat welding, or cementing) along the nodes 46. The inner plies are cut between the nodes 46, bent inwardly, and joined along the lines 48. If desired, inserts may be placed between the inner plies, and the inner plies from each side may be joined to the inserts, thereby increasing the spacing of the outer plies. The connections between the outer plies, known as "wing tabs," also serve to maintain the distance between the major walls of the container when it is filled with a radiation attenuating fluid. CAVEAT While the present invention has been illustrated by detailed descriptions of three preferred embodiments thereof, it will be obvious to those skilled in the art that various changes in form and detail can be made therein without departing from the true scope of the invention. For that reason, the invention must be measured by the claims appended hereto and not by the foregoing preferred embodiments.