The sodium-graphite reactor would use known technology, and an SGR SodiumGraphite Reactor experiment would be appropriate, The AEC was still negotiatingwith | North American Aviation. Perhaps the AEC would finance an eoperinent, and NAA the pilot plant.’ The next subject was water-cooled reactors, Continued supportLd Water- be given to ANL for research on principles. in experimentalboilingater Reootors reactor maybe built to obtain more experimental data on this type of 4 | operation than could be got from the recent boiling experiment carried. out with limited experimental facilities at Arco, Gol. Krisberg next described the Arco boiling water experiment. Arco experiment was carried out to study the feasibility of extracting power by direct boiling of primary water coolant, and to learn how safe water— Experiment cooled reactors might be when suddenly made supercritical, the assembly was composed of MTR fuel elements, The core of The reactivity was increased suddenly by known inerenente, and the behavior of the system| studied, Neutron flux, pressure in the water, and tenporature of the fuel and of the aluminumean were ‘recorded osedllographically. The behavior was very satisfactory. At moderate power, the operation wasSe steady; with large excess k ‘the water was expelled in | geyser fashion and | the reactor turned Ltself off. The water boiled with’small fauctintions at 24-28 kw/Liter at one atmosphere. With the system‘closed and ‘operating at 100 psi the operation was somewhat more stable. _It became quite | unstable at 4% excess Kk, very promising, It w 4 as concluded that the system was safe and Further study of the steadiness of such a system, par- ticularly how it is affected by pressure and geometry , needs to be done. At 12: 35 p.Me this session wasaadoumed & Boiling Water The al o