Abstract: This technical report is concerned with the program and results of the SM-1 reactor vessel head removal and core inspection at Fort Belvoir, Virginia from the period March 7, 1969 to May 17, 1959. It covers the operating procedures in detail and records the conditions found and problems encountered in order to make a record for reference in future work of this nature. The major objective of the program, to obtain irradiation data on the SM-1 type core, has been met. The boron control rod elements were found unsatisfactory for full core life, and europium oxide elements were placed in the core for future irradiation stability data. A major problem was experienced with the cracked pressure vessel head studs. The methods developed for the removal of the broken studs are presented. The complete metallurgical study of the stud failure from stress corrosion is included as Appendix B.

From Introduction: "The present semiannual progress report introduces more active consideration than has been given in the past (by us, at least) to the importance of energy degradation in DCX-like devices. The following pages introduce also a new major apparatus designated as DCX-2. Some of these concepts cannot as yet be released publicly and therefore Chap. 3 of this report, covering the DCX-EP-B design, is being issued separately, with restricted distribution, as ORNL-3044."