The performance of the TITAN-SDM algorithm for solving a reactor pressure vessel dosimetry problem is evaluated. Douglass and Rahnema recently developed the he subgroup decomposition method (SDM); a methodology which directly couples a consistent coarse-group transport calculation with a set of "decomposition sweeps" to provide a fine-group flux spectrum. The SDM has been implemented into the TITAN three-dimensional transport code and has been shown to accurately solve core criticality problems while significantly reducing computation time. This paper addresses the use of SDM for fixed-source problems. The VENUS-2 dosimetry benchmark problem is selected with an emphasis on fast neutron analysis; therefore, material cross sections are generated from the BUGLE-96 library considering neutron energies greater than 0.1 MeV. The accuracy and efficiency of TITAN-SDM is evaluated by comparison with a standard TITAN multigroup calculation.