This seventh Annual Report is a summary of some of the progress in scientific and engineering research and development carried on at Argonne National Laboratory during 1961. As is customary in this series, only those portions of the total program that have reached such a stage that they may be of general interest are recorded. Thus, a comparison with the Annual Reports for 1959 (ANL-6125) and for 1960 (ANL-6275) will reveal the description of a generally different set of scientific activities. A more detailed presentation of any work covered in this report or of the many ANL projects not mentioned may be obtained by perusing the various progress and topical reports issued by the Laboratory during 1961. A list of the publications in the scientific journals during 1961 by Argonne personnel has been given as an Appendix.

A total of nine clad plates, containing uranium -5 w/o zirconium 1.5 w/o niobium alloy cores and clad with Zircaloy-II, were rolled in plain carbon steel jackets, heat treated, physically evaluated, and corrosion tested. All these plates were found to be within predetermined dimensional tolerance in width, thickness, length, cladding thickness, and core distribution. Improved control of wielding variables and of the length of the seal pin projecting above the end plugs resulted in the elimination of frequently observed segmented inclusions at the seal pin interfaces.

Report issued by the Argonne National Laboratory covering a summary report of the work conducted by the Idaho Division. Experimental work and progress made on reactors are presented. This report includes tables, illustrations, and photographs.

Report issued by the Argonne National Laboratory discussing a summary of projects conducted with the Idaho Division. Descriptions of each project are presented. This report includes tables, and illustrations.

From Introduction: "The Fast Reactor Test (FARET) program is part of the United States Fast Reactor Program directed toward the demonstration of breeder reactors essential to the long-range goal of utilizing fertile fuels. (1) With-in this program is the current thinking that the early construction and operation of two or three prototype nuclear power plants of the order of 250 Mw(e) will lead eventually to the construction of practical and economic full scale breeder reactors by the early 1980's. (2)"