Effect of control rod insertion on the TRIGA neutron spectrum and the determination of elemental concentrations with k(0)-INAA

摘要

We suspected that changes in the neutron spectrum, caused by varying control rod positions in routine steady state operation of our TRIGA nuclear reactor, coupled with the k (0) formalism, were the cause of systematically biased concentrations compared to assigned values. To confirm this, we investigated the effect of control rod insertion on the spectrum parameters f and alpha, and the subsequent effect on the determination of concentrations with k (0)-INAA. We determined the spectra for three control rod configurations, in three irradiation positions, using the bare triple-monitor method, as well as using MCNP simulations, and compared the results.