Research in nuclear forensics

Identification and characterization of nuclear materials

Below are some highlights from recent research activities related to the categorization and characterization of nuclear material of unknown origin. In particular the Institute of Isotopes is developing several new methods of nuclear forensic science using various analytical techniques, such as (low background) gamma spectrometry, mass spectrometry (ICP-SFMS), prompt-gamma activation analysis (PGAA), electron microscopy etc.

Gamma spectrometry


Promt-gamma activation analysis (PGAA)

PGAA is a useful method for identification and characterization of fissile materials in containers. This project is supported by the Hungarian Atomic Energy Authority and the IAEA. As slow neutrons deeply penetrate into most materials, several centimeters of the most common shielding material still transmit significant fraction of the neutron beam. Though the internal flux is not exactly known inside the shielding containers, the samples with high cross-section, hidden in the shielding, still give strong gamma signals. Fissile materials always show a characteristic shape of gamma spectrum. This is true for both, prompt and also for the decay spectra. This latter one can be measured in a chopped neutron beam, while the decay spectrum is collected during the beam-off phases. Chopped beam measurements make possible the investigation of nuclear materials in shielding with higher cross-section as well, since in the decay phase the decay gammas from the fissile material will give a much stronger signal than the container itself. Based on the characteristic shape fissile materials can easily be identified in many commonly used shielding material, lead, iron etc. The characteristic gamma lines from uranium isotopes and from fission products enable the determination of the enrichment of the uranium sample. The mass of the hidden material can also be estimated.

Electron microscopy