Determination of the leaching rate of ~134Cs from the immobilized low-level radioactive sources in the cement and cement mixed with dolomite grains and with natural pozzolan powder

摘要

The leaching rate of ~134Cs from the immobilized low-level radioactive source in the Portland cement was found to be 4.481 × 10~-4 g/cm~2 per day. Mixing this cement with dolomite grains and natural pozzolan powder increased and reduced significantly the leaching rate to 7.373 × 10~-4 g/cm~2 and 3.495 × 10~-4 g/cm~-2 per day for 1 wt% mixing, and to 12.340 × 10~-4 g/cm~2 and 3.215 × 10~-5 g/cm~2 per day for 3 wt% mixing, respectively. This increase and reduction of the leaching rate is due to dedolomitization reactions between dolomite grains and cement alkalis, and pozzolanic reaction between pozzolan powder and calcium hydroxide, respectively. It was also found that the application of a latex paint reduced these leaching rates by about 8.8 and 8.2% for cement mixed with dolomite and with pozzolan, respectively. The obtained results help to improve the concrete properties used for the storage and disposal of the low-level radioactive wastes.