Summary: A comparison of the thermal, radiation and ultra violet annealing of neutron irradiated potassium and ammonium dichromates is reported. Although substantial thermal annealing is possible in the ammonium salt the process is eventually limited by gross thermal decomposition. Ultra-violet irradiation of the neutron irradiated salts leads to a reduction in retention in the ammonium salt. This is explained in terms of a photochemical reaction between the CrO22+ fragment and the ammonium ions or their photolytic product.