This report is a summary of the neutron attenuation data which have been obtained at the Brookhaven shielding facility on a mock-up of the fuel-rod-unloading plug used in the KAPL Reactor. Before this program was initiated, a number of small scale tests had been made in the ORNL lid tank on carbon steel mock-ups of components of the rotating plug. The results of the tests indicated considerable neutron streaming through the vertical steel and air members of the plug. However, the lid tank source strength and dimensions did not permit the tests to be extended to the full plug height. In view of the concern aroused by the ORNL tests and the absence of fundamental information on the transmission of neutrons through steel and the addition height (12') available here resulted in a request for BNL to construct and test a mock-up of a sector of the SIR top plug in accordance with KAPL specifications.