MEASUREMENT OF FISSION NEUTRON-SPECTRUM AVERAGED CROSS-SECTIONS OF SOME THRESHOLD REACTIONS ON NICKEL - SMALL-SCALE PRODUCTION OF CO-57 IN A NUCLEAR-REACTOR

Fission neutron spectrum averaged cross sections were measured by the activation technique in combination with radiochemical separations and high-resolution gamma-ray spectroscopy for the low-yield reactions Ni -58(n,2n)Ni-57, Ni-58(n,n'p+pn+d)Ni-57, (Ni(n,p)Co)-Ni-61-Co-61, (Ni(n ,p)Co)-Ni-62-Co-62, (Ni(n,alpha)Fe)-Ni-62-Fe-59 and (Ni(n,alpha)Fe)-Ni -64-Fe-61. The cross sections lie between 5 and 1600 mub. The relevanc e of the data to the production of Co-57 is discussed. Co-57 of high p urity cannot be easily produced via the (Ni(n,n'p+pn+d)Co)-Ni-58-Co-57 process using fission neutrons due to the competing (Ni(n,p)Co)-Ni-58 -Co-58 reaction. However, a radiochemical separation of Ni-57 followed by removal of its decay product leads to high purity Co-57; about 50 KBq amounts could be obtained.