Description: In contrast with previous EBR-1 reactor cores which were fueled with enriched uranium, the current Mark IV core is a 7 x 8-in. cylinder made of delta-stabilized plutonium alloyed with 1 1/4 w/o aluminum. The reactivity of the reactor is largely controlled by the movement of the entire outer blanket mounted on a hydraulic elevator with a travel of 80 inches. Partial meltdown occurred in November, 1955 during the last experiment scheduled for the core which was directed toward identifying the time constants associated with the components of the over-all reactivity coefficients. The incident is reported elsewhere. The changes in reactivity apparently come about as a result of changing from operation on the high temperature system to the low temperature system or vice versa. Continuous operation from day to day on either system does not effect any significant change in reactivity. Reactivity is not dependent on the duration of a run, but rather on the maximum power attained during that run.
Date: October 1963
Creator: Haroldsen, R. O. (Ray Ottley), 1928-; McGinnis, F. D. & Smith, R. R.
Partner: UNT Libraries Government Documents Department