Bismuth isotopes functions

Numerous nuclear reactions have been employed to produce astatine. Three of these are particularly suited for routine preparation of the relatively long-lived isotopes with mass numbers 209, 210, and 211. The most frequently used is the ° Bi(a,xn) At (a = 1-4) reaction, in which bismuth 44, 74,120) or bismuth oxide (7,125) is bombarded by 21-to 40-MeV a-particles. The ° Bi(He, xn) At reaction can also be used to produce isotopes of astatine 152), the nuclear excitation functions (62) favor a predominant yield of ° At and °At. The routine preparation of astatine is most conveniently carried out through the ° Bi(a,xn) At nuclear reactions, from which a limited spectrum of astatine nuclides may be derived. The excitation functions for these nuclear reactions have been studied extensively (78, 89, 120). The... 

The buildup of fission products and uranium isotopes as a function of time was calculated to determine the fuel concentration necessary for criticality after various time periods of operation. Since the solubility of uranium in bismuth is limited to 6560 ppm at 965°F, the lowest fuel temperature in the LMF-GCR, the reactor fuel must be replaced or processed after the poisons build up to such a level that this solubility limit is exceeded by criticality requirements. With the total fuel inventory in the system equal to 1.2 times the fuel in the core, the fuel lifetime will be 220 megawatt-t ears. This corresponds to an operating period of 4.8 years with a plant utilization factor of 80%. 

---