Three-dimensional (3-D) neutron-gamma transport calculations have been performed for the LIBRA-SP chamber with detailed geometrical modeling and results were compared to results based on one-dimensional (1-D) calculations. The overall tritium breeding ratio is 1.396. This is only 3% lower than the value predicted from the 1-D results. The overall reactor energy multiplication is 1.157 which is only 2% lower than the value estimated from the 1-D calculations. Larger differences were observed in the local heating and damage results obtained from the 1-D and 3-D calculations.