No abstract

This study was conducted to assess a kind of specific cement (ASC) extensively and recommend a suitable formula for the immobilization of the radioactive ion exchange resins from China Institute of Atomic Energy (CIAE). A mixture response surface approach was employed to design the experiment and interpret the results. Compared with the blend composed of ordinary Portland cement (OPC), an optimum combination, resin: .17 (dry wt/wt); ASC: .43; zeolite: .10, and water: .30, was determined within a series of restrictions for such properties as the slump, the 28-d compressive strength, the water immersion, the thaw-freeze resistance, the irradiation resistance, and the leaching rate. The diffusivities of 137 Cs and 60 Co of the waste forms resulting from the formula were 2.72E-06 (cm 2 /d) and 1.63E-07 (cm 2 /d) after 123 d, respectively. The loading amount of spent resins in the ASC form was larger than that in the OPC form by 5% under the equal performance indexes. The microanalysis indicated that there were many interlaced columnlike crystals (ettringites) developed in ASC-resin concrete. This structure could enhance the strength and stabilization of the waste forms significantly.

The simulated HLW glass was found to be altered in Beishan underground water at high temperature in two different stages starting with slow leaching of the immobilized elements for a period followed by a sharp degradation of the glass matrix. Immersed at 150• C in Beishan underground water with glass-surface-area-to-solution-volume ratio of 6000 m −1 , the glass was alterated rapidly with the sharp release of B, Na, Li, Cs, and Mo from the cold HLW glass after a stable period of 180 days. The glass was degraded up to 73.6% for the immersion period of 730 days resulting in the release of Mo and Cs up to 73.6% and 2.7% from the glass, respectively. With the alteration underway, new minerals were identified to be zeolite P, mordenite, nontronite, dickite, okonite, quartz, saponite, and tincalconite. However, at low temperature of 90• C, the glass was very stable with limited leaching of Na, B, and Li.

This study was conducted to assess a kind of specific cement (ASC) extensively and recommend a suitable formula for the immobilization of the radioactive ion exchange resins from China Institute of Atomic Energy (CIAE). A mixture response surface approach was employed to design the experiment and interpret the results. Compared with the blend composed of ordinary Portland cement (OPC), an optimum combination, resin: .17 (dry wt/wt); ASC: .43; zeolite: .10, and water: .30, was determined within a series of restrictions for such properties as the slump, the 28-d compressive strength, the water immersion, the thaw-freeze resistance, the irradiation resistance, and the leaching rate. The diffusivities of 137 Cs and 60 Co of the waste forms resulting from the formula were 2.72E-06 (cm 2 /d) and 1.63E-07 (cm 2 /d) after 123 d, respectively. The loading amount of spent resins in the ASC form was larger than that in the OPC form by 5% under the equal performance indexes. The microanalysis indicated that there were many interlaced columnlike crystals (ettringites) developed in ASC-resin concrete. This structure could enhance the strength and stabilization of the waste forms significantly.