Liquid Metal Fast Breeder Reactor Program: sec. 1. Summary. sec.2. Background. sec.3 IMFBR program.-v.2, sec.4. Environmental impact of the LMFBR fuel cycle. sec.5. Economic, social and other impacts.- v. 3, sec.6. Alternative technology options.- v. 4, sec.7. Mitigation of adverse environmental impacts. sec.8. Unavoidable adverse environmental impacts. sec.9. Short term benefits and long term losses. sec.10. Irreversible and irretrievable commitments of resources. sec.11. Cost-benefit analysis.- v. 5. Appendix. Comment letters 1-25 and responses.- v. 6. Appendix. Comment letters 26-38 and responses.- v. 7. Appendix. Comment letters 39-66 and responses