The irradiated fuel attribute tester (IRAT) is a small, lightweight CdZnTe based detector that can be suspended from a spent fuel pond bridge and used to differentiate irradiated non-fuel items from irradiated fuel items that are stored in spent fuel storage ponds. The IRAT detects γ radiation characteristic of either fission products contained in spent fuel or activation products contained in irradiated structural materials. The detector is housed in a stainless steel cylinder that includes shielding and a collimator. A multichannel analyser (operated above water) collects and analyses spectral information from the irradiated item. The presence of fission product isotopes, such as 137Cs, 134Cs, 144Pr and 154Eu, is used to confirm the irradiated fuel characteristics. In the case of a structural item, the presence of certain isotopes, such as 60Co, indicates prior exposure to a significant neutron flux. Measurement with the IRAT requires movement of the spent fuel, as the detector approaches the item from the side.

(Source: IAEA Safeguards Techniques and Equipment)