In troduc tion 1 2. Breeding Blanket Design and Materials 3. Tritium Breeding Requirements 4. Breeding Potential of Candidate Materials 4.1 Effects of Penetrations on T 4.2 Breeding in the Inboard Blanket 4.3 Fast and Thermal Systems 19 4.4 Neutron Multipliers 4.5 Conclusions on Breeding Potential 5. Sensitivity to Data Uncertainties 6. Recommended Effort 7. Nuclear Data Needs 44 References 49 iii