NUCLEAR POWER FOR PEACEFUL PURPOSES — SMYTH 197 



these studies use the various low-power research reactors that have 

 been built. 



One of the most interesting experiments that has been done was car- 

 ried out last summer at the Idaho Test Site by Dr. Zinn, director of our 

 Argonne Laboratory, and his associates. We had long worried about 

 what would happen to a water-cooled reactor if the flow of water 

 should be cut off. We were afraid that if the water supply was cut off 

 or if the temperature of the reactor rose too rapidly boiling would occur 

 and that this might have disastrous results. Dr. Zinn decided to make 

 a direct approach to this problem and built a small reactor with the 

 deliberate intention of producing boiling. When it was set up at the 

 Idaho testing station, it had an arrangement in it which suddenly 

 ejected the control rods so that the power generated by the chain reac- 

 tion went up in a fraction of a second from a few watts to many thou- 

 sands of watts. This had the expected effect on the water. It boiled. 

 It boiled so violently in fact that it was ejected from the reactor in a 

 small geyser. Repeated trials showed that in every case the boiling 

 reduced the power of the reactor so rapidly that no serious damage was 

 done. 



This particular experiment illustrates very well the reasons for 

 choosing an isolated area as a site for experimental reactors. It was 

 not only that some of the reactors might be inherently dangerous, but 

 it was felt that an experimental reactor, one built primarily for the 

 purpose of obtaining information, should be operated to extremes, and 

 that it was desirable to have such reactors in an isolated location for 

 that reason. In other words, if you want to get as much information 

 as you can out of a reactor, you need to push it to the point where it 

 might conceivably run into trouble. 



RESULTS OF THE PAST FIVE YEARS AND PRESENT STATUS OF THE ART 



Let me summarize some of the major results that we have obtained 

 in the past 5 years either directly from the reactors we have built and 

 operated or from laboratory work. I will take them in terms of the 

 five general areas that I enumerated at the start. So far as neutron 

 economy is concerned we have learned a great deal about the prob- 

 abilities of various nuclear events, including the relationship between 

 the probability of fission and the energy of the neutrons. (This, for 

 example, was tested in the experimental breeder reactor.) We have 

 found that we can use a number of different substances as moderators, 

 specifically beryllium, light water, and heavy water in addition to the 

 familiar graphite. 



As to the effects of radiation, the MTR has, of course, been of the 

 greatest value as one might expect, since it was designed for that 

 purpose. But we also have the benefit of studying the fuel elements 



