Various types of solidifying materials are used to stabilize and solidify low and intermediatelevel radioactive dispersible waste. Portland cement is generally used to solidify various radioactive wastes because its facilities and processes are simple, less dangerous, and it has excellent compressive strength after curing compared to other materials. However, it is difficult to use Portland cement in radioactive waste containing highly water-soluble harmful substances such as sodium fluoride because it is prone to leaching harmful ingredients in immersion tests due to its low water resistance. In this study, solidification was achieved using an organic-inorganic hybrid solidifying binders consisting of inorganic binders such as Portland cement, blast furnace slag powder, silica fume, and organic binders such as epoxy resin. This material was then compared with a solidification material made of Portland cement alone. The mixing ratio of inorganic binders, water, and organic binders to simulated waste is 35%, 20%, and 25%, respectively. The mixing ratio of inorganic binders and water when using only Portland cement for simulated waste is 100% and 80%, respectively. The mixed paste was poured into a cylinder mold (Φ 5 × 10 cm) to seal the upper part, cured at room temperature for 28 days to produce a solidification specimen, and then subjected to various tests were performed, including compressive strength, immersion compressive strength, hydration peak temperature, length change, and immersion weight change. The compressive strength of the organic-inorganic hybrid solidification test was 13-17 MPa, the immersion compressive strength was 15-18 MPa, the hydration peak temperature was 33-36°C, the length change rate was -0.086%, and the immersion weight change rate was –2.359%. The compressive strength of the Inorganic solidification test using only Portland cement was 16-18 MPa, the immersion compressive strength was 20-21 MPa, the hydration peak temperature was 23-25°C, the length change rate was -0.150%, and the immersion weight change rate was -5.213%. The compressive strength and immersion compressive strength of the organic-inorganic hybrid solidification materials were slightly lower compared to those of Portland cement solidification materials, they still met the compressive strength standard of 7-12 MPa, taking into consideration the strength reduce and economic feasibility of the core drill process. Furthermore, it indicates that the rates of change in length and immersion weight decreased to about 1% and 5%, suggesting an improvement in water resistance. The above results suggest that applying the organic-inorganic hybrid solidification method to radioactive waste treatment can effectively improve water resistance and help secure long-term stability.

Methyl bromide (MB) has been banned by Montreal Protocol due to ozone depletion in developed countries since 2005 but uses for quarantine & pre-shipment (QPS) remains exemption. Current MB alternatives such as phosphine gas, ethyl formate has been showing their potential in terms of their no phytotoxic damages to target perishable commodities post fumigation as well as their efficacy at low temperature. We evaluated phosphine (PH3) gas as MB alternatives welsh onion, carrot, and lettuce fumigation. on sensitivity test, larvae of Aphis gossypii were most tolerant to PH3 among the all stage of A. gossypii, Tetranychus urticae and Plutella xylostella. The LC99 and LCT99 value of mixture gas for adult of A. gossypii was 1.79 mg/L (24hr, 5℃) and 33.56 mg h/L(5℃), respectively. On confirmation trials scheduled in 28m3 container for 24hr at 5℃, all stages of T. urticae was completely controlled in 2g/㎥ of phosphine gas, but A. gossypii and M. persicae were not completely controled. No phytotoxic damage was observed in vegetables.