[en] The hydraulic and mechanical analyses and tests performed to demonstrate the acceptability of the retainer design are described. Side and top views of the retainer are shown. The design criteria for the retainer have been established on the basis of functional requirements and structural integrity. The functional aspects of the design were satisfied by ensuring that the retainer provides positive captured holddown on the BPRA to prevent motion. The structural integrity was confirmed through extensive static and dynamic analyses in which results were compared to conservative design limits and shown to be acceptable. The analytical parameters used and the conservatism of the dynamic flow analysis were further confirmed by prototype testing in air and under maximum flow conditions. The results of tests and analytical studies demonstrated that the retainer design is adequate for all conditions