High Flux Isotope Reactor - Neutron Activation Analysis

Neutron Activation Analysis

Neutron activation analysis (NAA) is a powerful analytical technique used to probe the elemental makeup of a wide variety of materials. NAA enjoys very high sensitivity and accuracy and is generally practiced nondestructively. Samples are bombarded with neutrons and the emissions from the radioisotopes produced are analyzed to determine both their number and identity. Several university, government, and industrial laboratories, both domestic and abroad, employ NAA to study forensic evidence, lunar and meteoritic materials, advanced materials, and high purity materials. NAA is free from classical “matrix” effects and is capable of very precise measurements having detection limits commonly in the fractions of PPM.

Reactor-based NAA was first performed at the Graphite Reactor at what is now ORNL. The PT-1 facility was installed at the HFIR in 1970 and was upgraded in 1987 when the PT-2 facility was added. Both facilities terminate in the permanent beryllium reflector portion of the reactor and facilitate the transfer of samples to and from the reactor. The PT-1 facility features the highest thermal neutron flux in the western world and offers many advantages in sensitivity for ultra-trace level determinations and for limited isotope production. The PT-2 facility offers a highly thermalized flux coupled with delayed neutron counting, giving us the ability to measure very low quantities of fissile materials in minutes.