Initial studies of the sensitivities of estimates of particle fluence, absorbed dose, and dose equivalent to fragmentation parameter variations are undertaken by using the LaRC galactic cosmic ray transport code (HZETRN). The new results, presented as a function of aluminum shield thickness, include upper and lower bounds on dose/dose equivalent corresponding to the physically realistic extremes of the fragmentation process and the percentage of variation of the dose/dose equivalent as a function of fragmentation parameter variation. Townsend, Lawrence W. and Cucinotta, Francis A. and Shinn, Judy L. and Wilson, John W. Langley Research Center NASA-TM-4386, L-17082, NAS 1.15:4386 RTOP 593-42-21-01...