cell housings 3 the support bars 1 7 and 8 are located between each of the rows of cells and along the perimeter of the array as shown in fig5 support bars 1 7 and 8 are provided at both the top and bottom end portions of the rack the cell housings are held in parallel alignment by welding the individual cell housings 3 to the upper and lower support bars 1 7 and 8 the support bars also add strength to the upper and lower ends of the cell housings to resist damage during inserting and removal of the nuclear fuel rod assemblies as shown in fig2 a base plate 2 is welded to the bottom of the rack to close the bottom of the cells and support the nuclear fuel assemblies the base plate 2 may also be provided with holes 12 at locations within each cell and pedestal feet 9 to facilitate the flow of water for enhanced cooling each cell housing 3 is an elongated tube having a rectangular cross section the housing is constructed from suitable material for example 050 inch thick stainless steel tubing typically the tubes are square approximately 81 2 inches along each side and 14 feet long each outer surface of the housing is planar to which is applied with a preload force an elongated slab 4 constructed of a damping material the damping material may also be a neutron absorbing material such as borated stainless steel borated aluminum boral such as manufactured by brooks amp perkins minneapolis minnesota or other neutron absorbing materials may be.