• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.3
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• pp.221-227
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• 2010

The solidification methods for powder wastes dried at CWDS(Concentrate Waste Drying System) in PWR have been studied in a variety of ways both at home and abroad. The solidification for these wastes has been performed using stabilization agents such as cement, paraffin and polymer. The applicability studies to maximize the reduction ratio of wastes and operational effectiveness for wastes treatment have been carried out, recently. It is necessary to pretreat the powder wastes before feeding wastes to vitrification facility because the fines flying brings about clogging of feeding pipes and off-gas treatment system or workers' exposure to radiation during maintenance. This paper describes an effective method for treatment of powder wastes to improve safety and stability of vitrification facilities.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.2
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• pp.155-161
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• 2015

Technetium-99m (^99mTc) is an important, short-lived decay product of molybdenum-99 (⁹⁹Mo), and it is considered the backbone of the modern nuclear diagnostic procedures. Since fission of ²³⁵U is the main source of production of ⁹⁹Mo, either highly-enriched uranium (HEU) targets or low-enriched uranium (LEU) targets are irradiated in the research reactors. The use of LEU targets is being promoted by the international community to avoid the proliferation issues linked with the use of HEU. In order to define the waste management strategy at the planning stage of establishment of an LEU based ⁹⁹Mo production facility, the impact of the use of LEU targets on the radioactive waste stream of the ⁹⁹Mo production facility was analyzed. Because the volume of uranium waste is estimated to increase six times, the use of high uranium density targets and the utilization of hot isostatic pressing were recommended to reduce the increased waste volume from the use of LEU based targets.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.2
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• pp.143-150
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• 2010

Vitrification technology has been gradually recognized as one of effective solidification methods for concentrated boric acid wastes generated in PWR. Vitrification for low- and intermediate-level radioactive wastes has a large volume reduction and good durability for the final products. A feasibility study for the vitrification of concentrated boric acid wastes has been performed with developing the pre-treatment methods of powdered wastes, glass compositions using glass formulation and demonstration test. The pre-treatment method is pelletizing the powder type for stable feeding within cold crucible melter. The glass compositions should be developed considering molten glass are related with wastes reduction. High contents of sodium and boron within borate wastes give influence to waste loading. A variety of factors obtained from the demonstration test are reviewed, which is wastes feeding rate, off-gas characteristics on stack and glass characteristics of final products such as durability for implementing the wastes disposal requirement. The aim of this paper is to present the feasibility of vitrification and review the solidification method for concentrated boric acid wastes and obtain the physicochemical characteristics of solidified glass.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.220-225
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• 2003

Generally, liquid radioactive wastes generated in nuclear power plant exist in powder form which do not contain moisture through the evaporating process of the Liquid Waste Management System and drying process of the Concentrated Waste Drying System. This powder form wastes are blended homogeneously with paraffin solidification agent and packed in metal drum to ensure its stability during handling and disposal. However, it was experienced that the powder form wastes were not blended homogeneously and separated into two layers in metal drum, on the other hand, a Portion of powder was adhered and solidified to the Inside parts of facility during the blending process. And the flaw of blending process above would come in case the mole ratio of Boron to Sodium in liquid radioactive wastes exceeds 0.2.

• Nuclear industry
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• v.7 no.8 s.54
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• pp.56-61
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• 1987

원자력발전소에서 생성되는 폐기물들의 양을 줄이는 것은 주요한 관심사이다. 방사성폐기물의 감용은 여러 방법으로 성취될 수 있는데, 본고에서는 액체폐기물 처리계통의 증발기를 효율적으로 운전하여 폐기물의 양을 감소시키는데 초점을 맞추었다. 이를 위해, 온도와 pH를 변화시키면서 농도가 다른 붕산수들의 침전상태가 조사되었는데, 배관의 보온을 고려하지 않았을 때는 붕산농도 $17wt.\%$까지, 고려했을 때는 $25wt.\%$까지 농축할 수 있음이 밝혀졌다. 또한, 붕산농도의 증가에 따른 시멘트고화체의 압축강도변화를 조사하였고 증발기 농축운전으로 얻어질 경제적 이들을 평가하였다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2007.05a
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• pp.99-100
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• 2007

• Analytical Science and Technology
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• v.14 no.3
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• pp.274-285
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• 2001

In this study, the thermal desorption-cryofocusing-gas chromatographic(TD-C-GC) method was developed for determination of volatile organic compounds(VOCs) in ambient air and was applied at the municipal solid waste landfill sites. On-column cryofocusing was possible only with a 100 ml dewars bottle in TD-C-GC method with a stainless steel column. However, high operating pressure was needed for purging VOCs from the absorbent trap, which was able to solve by pressure programming with a electric pressure controller. By using both pressure and temperature programming brought increasing of resolution power in on-column cryofocusing method, but the high pressure caused a leakage of sample tube with repeated use. A loop cryofocusing devise was also developed and compared with the direct on-column method. In loop cryofocusing method, VOCs were concentrated on a 0.8mm i.d. loop which is located between the injector and separation column by using liquid nitrogen. In order to purge VOCs from the absorbent trap, only 0.4 psi of pressure was need in the loop cryofocusing method. Dual detection system was applied for the analysis of VOCs; a FID was used for hydrocarbons and a FPD was used for sulfur-containing compounds. Qualitative analysis was done by on-column cryofocusing GC-MS system. Among the large number of VOCs, toluene was the most abundant. Hydrogen sulfide, dimethyl sulfide, carbon disulfide, dimethyl disulfide and methyl propyl disulfide were detected at landfill site by FPD.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.161-162
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• 2009

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.145-146
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• 2009

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.4
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• pp.297-308
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• 2007

The granulation equipment of concentrated wastes is manufactured for the polymer solidification of concentrated wastes. It uses liquid sodium silicate as a granulating agent for the granulating of dried powder containing boric acid. The granulating agent is sprayed in the form of droplet and mean size of dried granules is $2{\sim}4mm$. The new technology which has been used for the polymer solidification of spent resin in U.S. and certified by Nuclear Regulatory Commission (NRC) is successfully applied to concentrated wastes. This uses in-situ solidification process within drum without mechanical mixing. Maximum loading of waste can be achieved without increasing of waste volume. Polymer waste forms were evaluated with several test such as fire test, compressive strength test, leaching test, immersion test, irradiation test, and thermal cycling test according to standard test procedures.