Rapid chemical separations for thermal neutron activation analysis of niobium and vanadium and application to controlled thermonuclear reactor materials studies

Procedures are described for rapid, high-yield chemical separation of niobium and vanadium from surfaces of quartz, silicon, and carbon following thermal neutron activation. Practical detection limits for stable niobium and vanadium are 7x1010 and 6x1011 atoms, respectively. Application of these procedures to controlled thermonuclear reactor materials studies is discussed. It is shown that the fast neutron induced lattice dynamic sputtering ratio of laboratory-grade niobium is 1x10-5; a value which is sufficiently low so that no plasma stability problems are anticipated in a controlled thermonuclear reactor due to this phenomenon. Relatively large amounts of vanadium have been found on all collectors placed in juxtaposition to vanadium targets, including blank experiments, which were not irradiated with fast neutrons. No correlation has been found between measured vanadium and fast neutron flux. (T.G.)