Preliminary Assessment of the Total Activity of Disposed Radioactive Waste in Module A-1 of the Radioactive Waste Disposal Site "Pidlisnyi"

Preliminary assessment of the total activity of localized radioactive waste in module A-1 of the radioactive waste disposal site (RWDS) "Pidlisnyi" was carried out, based on the survey, calculation and the main research works conducted on the RWDS "Pidlisnyi". The survey determined the dose rate on the surface of the storage module. 16 wells were made, up to the depth of the "body" of radioactive waste over the entire plane of module A-1. The analysis of the cores showed that the thickness of radioactive waste, concrete and gravel-sand backfill fluctuate throughout the plane of module A-1, that was taken into account in the simulation and calculation. The assessment was carried out using the program code MicroShield. The results of the calculations showed that the ambient dose rate of gamma radiation at the selected point on the storage surface for this model is 7.6 · 10–4 μSv/h. At the same time, the results of field tests of module A-1 of RWDS "Pidlisnyi" showed that the dose rate of gamma radiation at this point is 7.8 μSv/h. Therefore, the dose rate of gamma radiation on the surface of the module is formed by radiation from the gravel-sand backfill. As part of this work, the inverse problem of determining the activity by known dose rate values was solved to assess the total waste activity. The results of the preliminary assessment showed that the total waste activity in module A-1 is approximately 1.5 · 1015 Bq. (author)