• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.232-232
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• 2004

우라늄 변환시설 내의 라군 슬러지의 처리를 위해 슬러지의 물 첨가 용해를 실시하고, 여과후 발생한 질산염의 안정적 처리를 위한 열분해를 실시하였다. 라군 슬러지의 질산염 및 우라늄 제거공정은 후속처리공정에서의 부담을 최소화 할 수 있도록 1.5배의 물을 첨가 용해하였으며, 두 개의 라군에 저장된 슬러지 처리방법의 효율성 평가를 위하여 각 라군의 개별적, 혹은 혼합하여 실험을 실시하였다.(중략)

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.179-186
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• 2006

Chemical wastes are generated from nuclear facilities and R&D laboratories, but the uranium concentration in the final dried cake is evaluated into 11.2 Bq/g, which exceeds the exemption level of 10 Bq/g for each U isotopes, so the cake is categorized into a radioactive waste. Acid dissolution was applied to extract uranium from the waste sludge, and uranium adsorption on the dissolved solution was experimented by using IRN-77 and Diphosil bead. A large amount of resin was required to get above 80% of uranium removal, which was found to be due to a large amount of metal ions simultaneously dissolved from the precipitates with uranium. As an alternative method, acid dissolution is applied to the dewatered wet cake of the sludge, and the natural evaporation method is adopted for the dissolved solution. The uranium concentration of the dissolved solution was estimated to be 6.97E-01 Bq/ml, and the specific activity of the final waste sheets is evaluated to be 4.3 Bq/g. These results lead to the suggestion that the application of acid dissolution to the wet cake and the natural evaporation for the dissolved solution is an effective treatment method for chemical wastes containing uranium.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2011.10a
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• pp.345-346
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• 2011

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.2
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• pp.85-93
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• 2013

This study has been carried out to elucidate the characteristics of the dissolution for Thermal Decomposed Solid Waste of uranium-bearing sludge (TDSW), the removal of impurities by an alkalization in a nitric acid dissolving solution of TDSW, and the selective removal (/recovery) of uranium by an acidification in an carbonate alkali solution, respectively. TDSW generated by thermal decomposition of U-bearing sludge which was produced in the uranium conversion plant operation, was stored in KAERI as a solid-powder type. It is found that the dissolution of TDSW is more effective in nitric acid dissolution than oxidative-dissolution with carbonate. At 1 M nitric acid solution, TDSW was undissolved about 30wt% as a solid residue, and uranium contained in TDSW was dissolved more than 99%. In order to the alkalization for the nitric acid dissolving solution of TDSW, carbonate alkalization is more effective with respect to remove the impurities. At the carbonate alkali solution controlled to about 9 of pH, Al, Ca, Fe and Zn co-dissolved with U in dissolution step was removed about $98{\pm}1%$. On the other hand, U could be recovered more than 99% by an acidification at pH about 3 in a carbonate alkali solution, which was nearly removed the impurities, adding 0.5M $H_2O_2$. It was found that uranium could be selectively recovered (/removed) from TDSW.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.111-111
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• 2005

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.238-238
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• 2004

우라늄 변환시설은 중수로용 $UO_2$ 분말 제조 시설로서 2001년도부터 제염 해체를 통한 변환시설 환경복원사업을 시작하였다. 변환 공정의 운전 중 발생하여 라군(lagoon)에 저장되어 있는 방사성 슬러지 폐액의 처리는 시설의 해체과정에서 매우 중요한 업무중의 하나이다. 라군 슬러지의 주성분은 $NH_4NO_3$, $NaNO_3$, $Ca(NO_3)_3$, $CaCO_3$ 및 U 화합물과 소량의 Fe, Mg, Al, Si 및 P 화합물로 구성되어 있다.(중략)

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2008.11a
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• pp.65-66
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• 2008

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.10a
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• pp.23-24
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• 2010

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2012.10a
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• pp.255-256
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• 2012

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.3
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• pp.249-256
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• 2005

Thermal decomposition and stabilization characteristics of the solid cake after the dissolution of nitrate of the lagoon sludge was investigated. Most of the nitrates were dissolved in the water and removed to the filtrate, but small amount of nitrates, calcium carbonate and uranium were remained in the solid cake. The solid cake was thermally decomposed in the muffle furnace at $900^{\circ}C$ for 5 hours. Uranium, which is in the lagoon 1, was stabilized with $NaNO_3$ decomposition to $Na_{2}O{\cdot}2UO_3$ form. For the lagoon 2, it is confirmed that CaO, which was created by thermal decomposition of the $Ca(NO_3)_2$ and $CaCO_3$, was transferred to $Ca(OH)_2$ in the air with water. Because it is known that $Ca(OH)_2$ is stable material, further additives did not need to the stabilization of the thermal decomposition of the lagoons.