In this study, the possibility of power flattening of the DT driven blanket in the Prometheus-H (Heavy ion) breeder reactor cooled with helium and fueled with different mixed fuels and nuclear waste actinide is investigated. The research has been performed individually for each mixed fuels, namely, UC-ThC, UO2-ThO2, UC-C, UO2-C and (CmO2)-Cm-244-UO2, with various mixture fractions. The mixed fuels with variable fractions of the compounds are spherically prepared, and cladded with SiC to prevent fission products from contaminating coolant in the blanket. The fuel spheres are replaced in the blanket as 10 rows in radial direction. Fractions of the uranium and curium compounds in each mixed fuel are linearly increased from the first to last row of the FFB (fissile fuel breeding) zone to obtain quasi-constant FPD (fission power density) profiles. Calculations of neutronic data per DT fusion neutron have been performed by using SCALE 4.4a Code. The blanket fueled with mixed (CMO2)-C-244(10%)-UO2 has maximum M (energy multiplication ratio) being one of main parameters in a fusion-fission hybrid reactor, while total FFBR (fissile fuel breeding ratio) reaches 0.212 in the case of mixed UC(70%)-ThC. TBR (tritium breeding ratio) values are greater than 1.05 in all investigated cases so that tritium self-sufficiency is maintained for (D,T) fusion driver. Neutron leakage out of the blanket is quite low. The spatial non-uniform fission energy density, defined with the help of peak-to-average fission power density ratio, Gamma, is reduced from about 1.4 to 1.05, and quasi-uniform FPD profiles are obtained by using the method of linearly increased mixture fraction, which means excellent power flattening. Calculations show that in all investigated cases, the breeder reactor has high neutronic performance and can produce substantial electricity in situ, fissile fuel and tritium required for (D,T) fusion reaction, and the method of linearly increased mixture fraction can supply the quasi-uniform FPD profiles. (C) 2002 Elsevier Science Ltd. All rights reserved.