• Title, Summary, Keyword: radiolysis

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Effect of Additives on Gamma Radiolysis of Methanol (메탄올의 감마선 분해에 대한 첨가물의 영향)

  • Choi, Sang-Up
    • Journal of the Korean Chemical Society
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    • v.14 no.3
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    • pp.237-242
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    • 1970
  • Effect of Added 1-hexene on the yield of hydrogen produced from Co-60 gamma radiolysis of methanol was investigated at room temperature. The results indicated that the yield of hydrogen decreased rapidly with increasing 1-hexene concentrations. Effect of added methyl borate on the radiolysis of methanol was also studied in the presence of oxygen. The results revealved that methyl borate acted as a less effective scavenger than oxygen towards the precursors of the radiolysis products. Experimental data previously obtained on the systems with oxygen added were treated more quantitatively to re-examine mechanism of the radiolysis of methanol in detail.

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Radiolysis of Methanol and Methanolic Solutions by Co-60 Gamma-Rays (Co-60 갬마線에 의한 Methanol 및 Methanolic Solution 의 Radiolysis)

  • Choi, Sang-Up
    • Journal of the Korean Chemical Society
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    • v.6 no.1
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    • pp.73-77
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    • 1962
  • Yields of hydrogen, methane, carbon monoxide, formaldehyde and ethylene glycol by gamma-radiolysis of methanol have been determined at room temperature and compared with values reported in the literature. The G-values obtained by the present studies are as follows: $G(H_2)=4.98,\;G(CH_4)=0.28,\;G(CO)=0.09,\;G(HCHO)=2.14\;and\;G(C_2H_6O_2)=3.07.$ The effects of water, methyl borate and alkali halides added to methanol prior to radiolysis have also been investigated. It is observed that alkali iodides and bromides affect the G-values, particularly, of hydrogen, formaldehyde and/or ethylene glycol, whereas alkali chlorides and fluorides have less pronounced effects.

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Formation and Properties of Enyne Radical Cation

  • Kim, Bang-Duk;Shim, Sang-Chul;Noboyuki Ichinose;Sachiko Tojo;Tetsuro Majima
    • Journal of Photoscience
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    • v.8 no.2
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    • pp.67-69
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    • 2001
  • Radical cations of DPBEY and PPCB were generated by ${\gamma}$-radiolysis and pulse radiolysis in halogenated solvents. The radical cation PPCB+ shows 505 (shoulder) and 520 nm absorption peaks with 700 ns lifetime in agreement with the laser flash photolysis work and strongly support the exciplex mechanism proposed for the photoreaction of PPCB and dimethylfumarate.

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Gamma-Radiolysis of Carbon Dioxide (IV). Effect of the Addition of Alcohols on the Gamma-Radiolysis of Gaseous Carbon Dioxide$^+$

  • Jin Joon Ha;Choi Jae Ho;Pyun Hyung Chick;Choi Sang Up
    • Bulletin of the Korean Chemical Society
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    • v.9 no.1
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    • pp.55-59
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    • 1988
  • The gaseous carbon dioxide has been irradiated with Co-60 gamma-radiation in the presence and absence of various alcohols, and the radiolysis products analyzed by gas chromatography. Experimental results indicate that no detectable amount of carbon monoxide is formed when pure carbon dioxide is irradiated. By adding small quantities of alcohols to carbon dioxide, however, considerable amount of carbon monoxide, ketones, alcohols and other organic products have been detected. By adding 0.1% of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-methyl-l-propanol, 2-butanol, and 2-methyl-2-propanol, G(CO) values obtained are 4.4, 4.5, 5.2, 4.4, 5.2, 5.0, 4.7 and 4.1, respectively. These high yields of carbon monoxide suggest that the oxidation reactions of carbon monoxide may be suppressed by scavenging oxygen atom with the alcohols. The main radiolytic decomposition reactions of the alcohols present in small quantity in carbon dioxide may be supposed to be the reactions with the oxygen atom produced by the radiolysis of carbon dioxide. The decomposition reactions seems to follow pseudo-first order kinetics with respect to the alcohols. The decomposition rate measured with 2-propanol is the fastest and that with 2-methyl-2-propanol the slowest. The mechanisms of the radiolytic decomposition reactions of the alcohols present in carbon dioxide are discussed on the basis of the experimental results of the present study.

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Formation and Cycloreversion of 2-Silacyclobuta[2.3]cyclophances via Photoinduced Electron Transfer

  • Mizuno, Kazuhiko;Nakanishi, Kazuhisa;Otsuji, Yoshio;Hayamizu, Tomoo;Maeda, Hajime;Adachi, Tomohiro;Ishida, Akito;Takamuku, Setsuo
    • Journal of Photoscience
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    • v.10 no.1
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    • pp.121-126
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    • 2003
  • Irradiation of an acetonitrile solution containing dimethylbis(4-vinylphenylmethyl)silane 1a in the presence of 9,10-dicyanoanthracene leads to formation of the intramolecular photocycloadduct, 2-sila-cyclobuta[2.3]cyclophane(2a). In contrast, prolonged irradiation gave insoluble polymeric material. The photocycloreversion of 2a occurs efficiently (quantum yields exceeds unity) by use of redox-type photosensitization in the presence of magnesium perchlorate. The transient absorption spectra generated by pulse radiolysis and gamma-radiolysis show that the radical cation species generated from 1a is different from that arising from 2a.

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The Effects of Methyl Borate, Iodine and Potassium Iodide on the Radiolysis of Methanol by Co-60 Gamma Rays (붕산메틸, 요오드 및 요오드화칼륨이 메탄올의 Co-60 放射線分解에 미치는 영향)

  • Choi, Sang-Up
    • Journal of the Korean Chemical Society
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    • v.9 no.2
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    • pp.106-109
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    • 1965
  • The effects of methyl borate, iodine and potassium iodide on the Co-60 gamma radiolysis of methanol have been reinvestigated at room temperature, utilizing an experimental technique based on gas chromatographic determinations of the gaseous products of the radiolysis. The presence of methyl borate reduces the yield for ethylene glycol to some extent, with slight reductions of the yields for hydrogen and formaldehyde. The presence of iodine causes appreciable reduction of the yields for hydrogen, formaldehyde and ethylene glycol, with a slight reduction of the yield for methane. The presence of potassium iodide reduces the yields for hydrogen and ethylene glycol but increases that for formaldehyde. A mechanism of the radiolysis reaction is discussed, on the basis of the observed data.

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Derivation of the Cathodic Current Density around the HLW Canister Due to the Radiolysis of Groundwater (고준위 폐기물 처분용기 주변에서의 지하수의 방사분해에 의한 음 전류 밀도 유도)

  • Choi, Heui-Joo;Cho, Dong-Keun;Choi, Jong-Won;Hahn, Pil-Soo
    • Journal of Radiation Protection and Research
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    • v.31 no.2
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    • pp.105-113
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    • 2006
  • The oxidizing species are generated from the radiolysis of groundwater in the pore of buffer material around the canister used for the disposal of spent fuels. A mathematical model was introduced to calculate the cathodic current density induced by the oxidant around the canister, which determined the corrosion of carbon steel. An analytical solution was derived to get the cathodic current density in the cylindrical coordinate. The cathodic current densities from both the rectangular coordinate and cylindrical coordinate were compared with each other. The source terms and absorbed dose rate for the calculation of the radiolysis were calculated using the ORIGEN2 and MCNP computer code, respectively. The radius of the canister was determined with the new model in order to prevent the local corrosion. The results showed that the new solution made the cathodic current density around 25 % lower than the Marsh model.

Synthesis of DMDBTDMA and determination of radiolysis products by GC/MS (DMDBTDMA의 합성 및 방사선 분해산물의 GC/MS 분석)

  • Yang, Han-Beom;Lee, Eil-Hee;Park, Gyo-Beom
    • Analytical Science and Technology
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    • v.21 no.5
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    • pp.403-411
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    • 2008
  • Dimethyldibutyltetradecylmalonamide (DMDBTDMA) extractant was used in a solvent extraction process for a radioactive liquid waste treatment. For the study of radiolysis phenomena, DMDBTDMA was synthesized and the degradation compounds (n-methylbutylamine, tetradecane, 1-tetradecanol) in the DMDBTDMA extractant, irradiated with $^{60}Co$ gamma ray, were identified and determined as radiolysis products by a Fourier transform infrared (FT-IR), gas chromatograph/mass spectrometer (GC/MS) analysis and GC/MS with selected ion monitoring (SIM) mode. Retention behavior of n-methylbutylamine, n-dodecane, tetradecane and 1-tetradecanol in the total ion chromatogram with the standard materials and n-dodecane as the internal standard (ISTD) were 2.35 min., 8.83 min., 10.68 min. and 12.75 min., respectively. In the case of tetradecane, there was a linear relationship between the concentration of the tetradecane and the absorbed dose of the ${\gamma}$-ray irradiated DMDBTDMA.

Change of chemical properties by neutron irradiation in boric acid solution (중성자 조사에 의한 붕산수의 화학특성 변화)

  • Choi, Ke-Chon;Yeon, Jei-Won;Kim, Won-Ho
    • Analytical Science and Technology
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    • v.18 no.4
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    • pp.292-297
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    • 2005
  • The effect of neutron irradiation on the chemical properties was measured in boric acid solution. The pH of the solution decreased in proportion to the irradiation time and the concentration of boric acid. The concentration of hydrogen peroxide, which is one of the radiolysis products of water, is in proportion to the concentration of boric acid, while in inverse proportion to the irradiation time. The oxygen and hydrogen gases had same chemically equivalent ratio in water radiolysis. The lithiun, which comes from $^{10}B(n,{\alpha})^7Li$, had poor relationship with neutron irradiation time at low concentration, $233{\sim}699{\mu}g/mL$, of boric acid, but the relationship was improved at higher concentration.

THE PREDICTION OF pH BY GIBBS FREE ENERGY MINIMIZATION IN THE SUMP SOLUTION UNDER LOCA CONDITION OF PWR

  • Yoon, Hyoungju
    • Nuclear Engineering and Technology
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    • v.45 no.1
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    • pp.107-114
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    • 2013
  • It is required that the pH of the sump solution should be above 7.0 to retain iodine in a liquid phase and be within the material compatibility constraints under LOCA condition of PWR. The pH of the sump solution can be determined by conventional chemical equilibrium constants or by the minimization of Gibbs free energy. The latter method developed as a computer code called SOLGASMIX-PV is more convenient than the former since various chemical components can be easily treated under LOCA conditions. In this study, SOLGASMIX-PV code was modified to accommodate the acidic and basic materials produced by radiolysis reactions and to calculate the pH of the sump solution. When the computed pH was compared with measured by the ORNL experiment to verify the reliability of the modified code, the error between two values was within 0.3 pH. Finally, two cases of calculation were performed for the SKN 3&4 and UCN 1&2. As results, pH of the sump solution for the SKN 3&4 was between 7.02 and 7.45, and for the UCN 1&2 plant between 8.07 and 9.41. Furthermore, it was found that the radiolysis reactions have insignificant effects on pH because the relative concentrations of HCl, $HNO_3$, and Cs are very low.