Radioactive products generated by long-term operation at NPP can become deposited on the surfaces of the system and equipment, leading to radiation exposure for workers during the decommissioning process. Chemical decontamination is one of the methods to reduce radiation exposure of workers, and there are HP CORD UV, CITROX, CAN-DECON. In the chemical decontamination process, organic acids are generally used, and representative organic acids include oxalic acid and citric acid. There are various methods for removing residual organic acid in decontamination liquid waste, such as using an oxidizing agent and an ion exchange methods. However, there is a problem in that oxidizing agent is used excessively or secondary wastes are generated in excess during organic waste treatment. However, when organic acid is decomposed using a UV lamp, the amount of secondary waste is reduced because it tis decomposed into CO2 and H2O. In this study, organic acid decomposition was evaluated as the contact time of the UV lamp. The experimental equipment consists of a UV reactor, a mixing tank, a circulation pump. The experimental conditions involved preparing 60 L of organic liquid waste containing oxalic acid, hydrogen peroxide and iron chloride. Test A was conducted using one UV reactor, and Test B was performed by connecting two UV reactors in series. As a result of the experiment, a decomposition rate of over 95% was shown after one hour for oxalic acid, and it was confirmed that the initial decomposition rate was faster as the contact time increases. Therefore, in order to increase the initial decomposition rate, it is necessary to increase the contact time of the UV lamp by connecting the UV reactors in series.

본 연구에서는 Bulk형 플라스틱과 유리 조광렌즈， 박막형 플라스틱 조광렌즈를 이 용하여 온도를 6 0C 에 서 UVA, UVB, UVC을 각각 조사하여 자외 선 파장에 따라 조 광렌즈의 변색전을 기준으로 조광렌즈의 색차에 대한 분석을 위하여 lN꺼Tis Spectrophometer로 조사시간을 다양하게 하여 측정하였다. Bulk형 플라스틱 조광렌 즈의 경우 6 0C 의 UVA에서 색상변화가 가장 크고， UVC 에서 가장 작았다. 유리조광 렌즈인 SINbr는 온도의 변화에 무관하게 색상변화가 거의 없었다. Bulk형 유리조광 렌즈의 눈에 띄는 감각정도는 광원과 온도에 관계없이 Slight에 해당하였다. Brown 색상이 Smoke 색상보다 온도와 광원에 무관하게 색상변화가 더 컸다. 광원에 따른 색상변화는 UVC에서 가장 작았다.

This study investigates leaching and thermal treatment characteristics of mercury in waste phosphor powder from UV lamp for industrial use. Waste phosphor powder contaminated with mercury compounds requires proper treatment for final disposal. A sequential extraction procedure was conducted in order to estimate the stability of mercury compounds in waste phosphor powder. The fraction of mercury compounds leached in initial steps by ion-exchangeable and low acidic solutions was 62%, which would be unstable. Finally 36% of mercury compounds was left as a strongly stable form before last step of acid digestion by aqua regia. Mercury was decomposed rapidly during initial period in thermal treatment. However, the decomposition rate reached in steady later. Correlation of mercury content in residues with concentration of leaching extract was attempted in order to set a thermal treatment condition. When mercury content in residue of phosphor powder could be lowed up to about 13 mg-Hg/kg by thermally with satisfying the Korean leaching standard limit of 0.005 mg-Hg/L.

Diethyl phthalate (DEP) is widely spread in the natural environment as an endocrine disruption chemicals (EDs). Therefore, in this study, ultrasound (US) and ultraviolet (UVC), including various applied power density (10-40 W/L), UV wavelengths (365 nm, 254 nm and 185 nm) and frequencies (283 kHz, 935 kHz) were applied to a DEP contaminated solution. The pseudo-first order degradation rate constants were in the order of 10-1 to 10-4 min-1 depending on the processes. Photolytic and sonophotolytic DEP degradation rate also were high at shortest UV wavelength (VUV) due to the higher energy of photons, higher molar absorption coefficient of DEP and increased hydroxyl radical generation from homolysis of water. Sonolytic DEP degradation rate increased with increase of applied input power and the dominant reaction mechanism of DEP in sonolysis was estimated as hydroxyl radical reaction by the addition of t-BuOH, which is a common hydroxyl radical scavenger. Moreover, synergistic effect of were also observed for sonophotolytic degradation with various UV irradiation.