• Title/Summary/Keyword: Radioactive liquid waste

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Oxalate Precipitation of Lanthanide and Actinide in a Simulated Radioactive Liquid Waste (모의 방사성용액에서 란탄족과 악티늄족원소의 옥살산침전)

  • Chung, Dong-Yong;Kim, Eung-Ho;Lee, Eil-Hee;Yoo, Jae-Hyung;Park, Hyun-Soo
    • Applied Chemistry for Engineering
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    • v.10 no.7
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    • pp.996-1002
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    • 1999
  • The oxalate precipitation of lanthanide and actinide by oxalic acid was investigated in the simulated radioactive liquid waste, which was composed of 17 elements of alkali, alkaline earth(Cs, Rb, Ba, Sr), transition metal(Zr, Fe, Mo, Ni, Pd, Rh), lanthanide(La, Y, Nd, Ce, Eu) and actinide(Np, Am) in nitric acid solution. The effect of concentrations of nitric acid and ascorbic acid on the precipitation yield of each element in the simulated solution was examined at 0.5 M oxalic acid concentration. The precipitation yields of the elements were usually decreased with nitric acid concentration, nevertheless, the precipitation yields of lanthanide and actinide were more than 99%. Palladium was precipitated due to the reduction of Pd(II) into Pd metal by the addition of ascorbic acid in the oxalate precipitation and then, the precipitation yields of Mo, Fe, Ni, Ba decreased by 10~20% with concentration of ascorbic acid. The reductive precipitation of Pd(II) into Pd metal by the addition of ascorbic acid into the simulated radwaste occurred at below 1 M nitric acid concentration and its yield showed maximum at the ascorbic acid concentration of 0.01~0.02 M. The hydrazine suppressed the reductive precipitation of Pd by the ascorbic acid.

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A Verification of Tip-over Analysis of a Dry Concrete Storage Cask under The Accident Conditions by a Test for the 1/3 Scale Model (사고조건하의 건식저장용기 전복해석검증을 위한 1/3 축소모델의 시험)

  • Kim Dong-Hak;Seo Ki-seog;Lee Ju-Chan;Jung Ki-Jung;Cho Chun-Hyung;Choi Byung-Il;Lee Heung-Young
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2005.11a
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    • pp.237-246
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    • 2005
  • A tip-over test of the 1/3 scale model is conducted to verify the tip-oner analysis of a dry concrete storage cask under a hypothetical accident condition. The tip-oner analysis is executed using the velocity at each point which are determined from the initial angular velocity as the initial conditions of the model just before the impact. To confirm the structural integrity of the canister of a dry concrete storage cask, the non-detective testing such as Liquid Penetrants testing and Ultrasonic Testing are conducted. The strains and tile accelerations acquired by the tip-over test are compared with those by the analysis to verify the tip-over analysis. The lid of a storage calk are plastically deformed at the impact point. Liquid

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A Study and Analysis on Tritium Radioactivity and Environmental Behavior in Domestic NPPs (국내 원전 삼중수소 방사능 배출 및 환경 거동에 대한 분석 및 고찰)

  • Han, Sang Jun;Lee, Kyeong Jin;Yeom, Jeong Min;Shin, Dae Tewn
    • Journal of Radiation Protection and Research
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    • v.40 no.4
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    • pp.267-276
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    • 2015
  • Several analyses on tritium that is the largest release of gas or liquid radioactive waste from domestic PWR and PHWR NPPs were carried out, such as release comparison, directional frequency of wind and tritium behavior changes in environmental samples. First of all, analysis result showed that tritium released from PHWR was more than ten times as gas and double to three times as liquid in comparison to PWR in 2013. Independent release management in NPP units is needed to precisely control and analyze tritium, since there were 2 units of some NPPs having the same amount of release during analysis. In analysis on frequency of wind direction, average range showed 1.7 to 11.5% by 16-point compass. In case of analysis on sampling points by wind direction, Result showed most of the sampling points are right in places. However, There are some areas needed to examine. In analysis on tritium concentration changes in environmental samples, tritium concentration near NPPs was higher than one far away from NPPs. In case of environmental samples far from PWR, a trace of tritium occur. While, tritium concentration near NPPs was more than or equal to one further from PHWR. In conclusion, tritium occurs considerably in PHWR and is lower than standard in samples. but, it is still detected. Therefore, it is needed to strengthen control in system in NPPs and to consistently monitor tritium in environment.

Analysis of 766 keV Gamma Peak from NPP Environmental Samples (원전주변 환경시료의 766 keV 감마선에너지 피크에 대한 해석)

  • Kim, Wan;Lee, Hae-Young;Yang, He-Sun;Park, Hae-Soo;Kim, Bong-Kuk;Park, Hwan-Bae;Kim, Hong-Joo;Lee, Sang-Hoon
    • Journal of Radiation Protection and Research
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    • v.34 no.4
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    • pp.190-194
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    • 2009
  • Gamma spectral results for macroalgae samples taken from the environment of Ulchin nuclear power plants in Korea (east coast), showed 766 keV peaks, which were identified as $^{95}Nb$ by several research institutes. After the enhancement of liquid radioactive waste disposal facility at Ulchin NPP site, the $^{95}Nb$ amount in the liquid radioactive waste outflow has drastically reduced, but the expected reduction in $^{95}Nb$ specific activity from environmental samples did not actually show up on gamma spectroscopy. Detailed re-investigation revealed that along with 766 keV peak, other peaks (63, 92 and 1001 keV) from $^{234}Th-^{234}mPa$ decay series were also detected on spectroscopy, and that the measured half lives of the four peaks were very close to known half life of $^{234}Th-^{234}mPa$ decay series, which is 24.1 day. The measured gamma yield ratios of 766 keV peak to 1001 peak were very close to known ratio 0.35 for $^{234}mPa$. It is concluded that 766 keV peaks on gamma spectroscopy of Ulchin NPP environmental samples were mainly from $^{234}mPa$, which is one of naturally occurring radionuclides.

A Sensitive Detection of Actinide Species in Solutions Using a Capillary Cell (모세관 셀을 이용한 수용액 내 악티나이드 화학종의 고감도 검출)

  • Cho, Hye-Ryun;Park, Kyuong-Kyun;Jung, Euo-Chang;Song, Kyu-Seok
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.7 no.2
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    • pp.109-114
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    • 2009
  • Absorption spectra for a quantitative analysis of actinide elements such as U(VI) and Pu(V) were measured by using a liquid waveguide capillary cell (LWCC) which has an optical path length of 1.0 meter. In order to investigate radioactive elements, a LWCC is installed in a glove box and is coupled to a spectrophotometer with optical fibers. Limits of detection (LOD) for the system were determined as 0.74 and 0.35 M with molar absorption coefficients of 8.14${\pm}$0.07 (414 nm) and 17.00${\pm}$0.16 (569 nm) $M^{-1}cm^{-1}$ for U(VI) and Pu(V) ions, respectively. The measured LOD values are about 30 times more sensitive when compared to those achievable by using a conventional quartz cell with an optical path length of 1.0 cm. As an application with an enhanced sensitivity, a quantitative analysis for micromolar concentrations of Pu(V) has been performed to decrease the uncertainty in the formation constant of the Pu(VI)-OH complex.

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Prediction of the Dynamic Adsorption Behaviors of the Uranium and Cobalt Ions in a Fixed Bed by Surface Modified Activated Carbon (표면개질 활성탄을 이용한 고정층에서 우라늄 및 코발트 이온의 동적 흡착거동 모사)

  • Geun-IL Park;Jung-Won Lee;Kee-Chan Song;In-Tae Kim;Kwang-Wook Kim;Myung-Seung Yang
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.1 no.1
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    • pp.81-92
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    • 2003
  • In order to predict the dynamic behaviors of uranium and cobalt in a fixed bed at various influent pH values of liquid waste, the adsorption system is regarded as a multi-component adsorption between each ionic species in the solution. Langmuir isotherm parameters of each species were extracted by incorporating equilibrium data with the solution chemistry of the uranium and cobalt using IAST. Prediction results were in good agreement with the experimental data, except for a high concentration and pH. Although there was some limitations in predicting the cobalt adsorption, this method may be useful in analyzing a complex adsorption system where various kinds of ionic species exist in a solution.

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Spatial Distributions of $^3H$ and $^{14}C$ in the Shielding Concrete of KRR-2 (연구로 2호기 수조 콘크리트의 $^3H$$^{14}C$ 공간분포)

  • Hong, Sang-Bum;Kim, Hee-Reyoung;Chung, Kun-Ho;Kang, Mun-Ja;Jeong, Gyeong-Hwan;Chung, Un-Soo;Park, Jin-Ho
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.4 no.4
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    • pp.329-334
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    • 2006
  • The depth distributions of total $^3H$ and $^{14}C$ activities were characterized for the activated shielding concrete from a decommissioning of KRR-2 using the commercially available tube furnace and a liquid scintillation counter. The correlation of measurement results between $^3H,\;^{14}C$ and gammer emitter was evaluated to apply for estimating radionuclide inventory of the concrete waste generated from decommissioning KRR-2. The detection limits for $^3H$ and $^{14}C$ are 0.048 and 0.028 Bq/g respectively. The specific activities of the $^3H$ and $^{14}C$ tend to decrease exponentially as the depth of the concrete becomes deeper from the surface. In addition, the $^3H$ and $^{14}C$ activities were in good correlation with the $^{60}CO$ activities analysed for the shielding concrete of KRR-2.

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Studies on the Sorption and Fixation of Cesium by Vermiculite

  • Lee, Sang-Hoon
    • Nuclear Engineering and Technology
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    • v.5 no.4
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    • pp.310-320
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    • 1973
  • The sorption and fixation of cesium in dilute solutions by vermiculite saturated with Na or K were studied in order to investigate any possibibty of its use in radioactive effluent treatment. The cesium sorbed by vermiculite with the increase in pH is attributed to the increase of sorption surface as a result of the dispersion. The increased cesium sorption by Na-vermiculite is due to the different sorption rates by the different exchange sites : external surface and internal surface. It is shown that the larger amount of sorbed cesium was extracted by KCI rather than with any other extractants. It is suggested that the fixation of cesium by vermiculite occurs at the crystal edge where Cs may replace K. Domestic vermiculite is a valuable material for use in the cesium sorption and fixation, and might be useful as a good packing material outside the tank of highly radioactive liquid waste. And from these results one could suggest that the artificial alteration of the biotite to vermiculite might be occurring by treating with NaCl.

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The Removal of NOx by Mediated Electrochemical Oxidation Using Ag(II) As a Mediator (Ag(II)를 매개체로 사용하는 전기화학적 매개산화에 의한 NOx 제거)

  • Lee, Min-Woo;Park, So-Jin;Lee, Kune-Woo;Choi, Wang-Kyu
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.9 no.3
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    • pp.121-129
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    • 2011
  • The effects of the applied current density, the $AgNO_3$ concentration, the scrubbing liquid flow rate and the NO-air mixed gas flow rate on the NO removal efficiency were investigated by using $Ag^{2+}$ mediated electrochemical oxidation (MEO). Results showed that the NO removal efficiency increased with increasing the applied current density. The effect of the $AgNO_3$ concentration on the NO removal efficiency was negligibly small in the concentration of $AgNO_3$ above 0.1 M. When the scrubbing liquid flow rate increased, the NO removal efficiency was gradually increased. On the other hands, the NO removal efficiency decreased with increasing the NO-air mixed gas flow rate. As a result of the treatment of NO-air mixed gas by using the MEO process with the optimum operating condition and the chemical absorption process using 3 M $HNO_3$ solution as a scrubbing liquid, the removal efficiency of NO and $NO_x$ was achieved as 95% and 63%, respectively.

Chemical Stability Evaluation of Ceramic Materials for Liquid Cadmium Cathode (액체카드뮴음금용 세라믹 소재의 화학적 안정성 평가)

  • Ku, Kwang-Mo;Ryu, Hong-Youl;Kim, Seung-Hyun;Kim, Dae-Young;Hwang, Il-Soon;Sim, Jun-Bo;Lee, Jong-Hyeon
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.11 no.1
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    • pp.23-29
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    • 2013
  • LCC (Liquid cadmium cathode) is used for electrowinning in pyroprocessing to recover uranium and transuranic elements simultaneously. It is one of the core technologies in pyroprocessing with higher proliferation resistance than a wet reprocessing because LCC-cell does not separate TRU from uranium. The crucible which holds the LCC is technically important because it should be nonconducting material to prevent deposition of metallic elements on the crucible outer surface. The chemical stability is also crucial factor to choose crucible material due to the strong reactivities of TRU and possible incorporation of Li metal during the operation. In this study, the chemical stabilities of four kinds of representative ceramic materials such as $Al_2O_3$, MgO, $Yl_2O_3$ and BeO were thermodynamically and experimentally evaluated at $500^{\circ}C$ with simulated LCC. The contact angle of LCC on ceramic materials was measured as function of time to predict chemical reactivity. $All_2O_3$ showed poorest chemical stability and the pores in BeO contributed to a decreases in contact angle. MgO and $Y_2O_3$ have superior chemical stability among the materials.