Fast Reactor Physics Programme of the United States Atomic Energy Commission

The United States of America fast reactor physics programme is a broadly based research and development effort that is focused on the major neutronics problems of fast reactor design and operation and aims at providing a sound basis for the large-scale commercial exploitation of fast power breeder reactors. These include the optimization of reactor performance to gain maximum economic advantages from fuel without sacrificing safety and reliability requirements. The major emphasis is on the physics of sodium-cooled systems with lesser effort currently on steam and gas-cooled systems. The refinement of nuclear data for use in reactor calculations is a major high priority item. Such refinement will come from further specific differential cross-section measurements as well as correlations and/or adjustments via integral data and theory. The availability of large amounts of differential and integral data places severe requirements on automatic data processing techniques. These must be used both in the procurement and the compilation of the data to provide it in a form which is routinely useful for the reactor designer. The continued operation of the fast critical facilities ZPR-III, VI, and XI, as well as the projected operation of the ZPPR, is planned. Much of the work on these facilities is in support of nuclear data verification of nuclear design methods. These facilities will also be used in support of engineering design of fast test and power reactors. The development of reliable and relatively sophisticated nuclear design methods is extremely important so that the qualitative interpretive aspects of nuclear design can be minimized. The development of these methods requires that certain aspects of nuclear theory, in particular space-time kinetics, three-dimensional techniques, and/or variational methods must be applied to fast reactor systems. The safety analysis requirements include major accident and kinetics codes which provide for system transients. Experimentally, the development of improved neutron spectrometry for fast reactors will provide a necessary basis for verifying theory and data for nuclear design. The full exploitation of the critical assemblies will give consideration to the use of automated data accumulation and processing, as well as improved techniques for reactivity measurements. The Physics Programme is sensitive to the requirements of other disciplines in the liquid Metal Fast Breeder Reactor (LMFBR) Programme. These include the application of nuclear design methods to conceptual studies and safety analyses. Related quantitative studies and evaluation of the reactor fuel cycle are major - considerations throughout the operating history of both conceptual and currently operating reactors. Such studies will provide feedback and specifications for the basic research and development programme. (author)