Preliminary Calculations on a Breeder with Circulating Uranium

Preliminary Calculations on a Breeder with Circulating Uranium 

The following constitutes our present ideas on the breeder which, no need to say, are very preliminary and which we hope will undergo considerable changes before they will crystallize. Under ordinary conditions we would not report on work which is still as much in flux as the present one is. However, we had to shift our attention, at least temporarily, to another subject and we want to record for this reason the results obtained so far. 

The breeder is an arrangement in which 23 undergoes flssion and the neutrons produced thereby are absorbed by thorium. When this thorium decays it produces again 23 via Pa. Since the rj of 23 is, according to Anderson and May, 2.37 the net increase in the number of neutrons per 23 destroyed is 1.37. If all these neutrons were absorbed in thorium, we would obtain 1.37 23 atoms per 23 destroyed. It is well to remember, however, that if only as many as 15% of the 2.37 neutrons emitted are lost by escape from the system or parasitic absorption by other materials or otherwise, the efficiency of the breeder goes down to 1 and no increase in the amount of 23 results. 

Another point that is important is the power to product ratio of such a breeder. Let us assmne that the total losses in neutrons amount to only 7 %. In this case 1.19 atoms of 23 are produced per 23 atom destroyed. Thus the net gain in 23 is. 19 atoms per 23 atoms destroyed or per. 89 atoms 23 undergoing flssion. As a result, the power output per net production is about flve times greater than in the conventional piles. 

If only the energy of the 23 produced by the breeder is utilized, the energy of at least 1/1.19 = 84% of the Th is wasted if we adopt the numbers of the preceding example. 

---