• Title/Summary/Keyword: Degradation of radiation

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State-of-Arts of Primary Concrete Degradation Behaviors due to High Temperature and Radiation in Spent Fuel Dry Storage (사용후핵연료 건식저장 콘크리트의 고열과 방사선으로 인한 주요 열화거동 분석)

  • Kim, Jin-Seop;Kook, Donghak;Choi, Jong-Won;Kim, Geon-Young
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.16 no.2
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    • pp.243-260
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    • 2018
  • A literature review on the effects of high temperature and radiation on radiation shielding concrete in Spent Fuel Dry Storage is presented in this study with a focus on concrete degradation. The general threshold is $95^{\circ}C$ for preventing long-term degradation from high temperature, and it is suggested that the temperature gradient should be less than $60^{\circ}C$ to avoid crack generation in concrete structures. The amount of damage depends on the characteristics of the concrete mixture, and increases with the temperature and exposure time. The tensile strength of concrete is more susceptible than the compressive strength to degradation due to high temperature. Nuclear heating from radiation can be neglected under an incident energy flux density of $10^{10}MeV{\cdot}cm^{-2}{\cdot}s^{-1}$. Neutron radiation of >$10^{19}n{\cdot}cm^{-2}$ or an integrated dose of gamma radiation exceeding $10^{10}$ rads can cause a reduction in the compressive and tensile strengths and the elastic moduli. When concrete is highly irradiated, changes in the mechanical properties are primarily caused by variation in water content resulting from high temperature, volume expansion, and crack generation. It is necessary to fully utilize previous research for effective technology development and licensing of a Korean dry storage system. This study can serve as important baseline data for developing domestic technology with regard to concrete casks of an SF (Spent Fuel) dry storage system.

Detection of Radiation Degradation of LDPE by ESR Spectroscopy (전자스핀공명을 이용한 저밀도 폴리에틸렌의 방사선 열화 검지)

  • Kim Ki-Yup;Lee Chung;Ryu Boo-Hyung
    • Journal of the Korean Society of Safety
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    • v.20 no.1 s.69
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    • pp.81-86
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    • 2005
  • This study has investigated radiation degradation of low density polyethylene(LDPE). Samples were irradiated up to 800kGy using a $Co^{60}\;\gamma-ray$ at a dose rate of 5kGy/hr in the presence of air atmosphere at room temperature. After irradiation, storing for 2 weeks, free radical measurement of LDPE has established by electron spin resonance(ESR). ESR measurement showed that free radical concentration(FRC) was increased with radiation dose and decreased with the time. The radical types showed alkyl, allyl, and peroxy radical with the irradiation, these changed to peroxy radical with the time.

The Effect on Antioxidant for Improving to Radiation Resistance on Irradiated PVDF (PVDF의 내방사선 특성 향상을 위한 산화방지제 첨가효과)

  • Kim, Ki-Yup;Lee, Chung;Ryu, Boo-Hyung;Lim, Kee-Joe
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.252-253
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    • 2005
  • The dielectric relaxation properties of $^{60}Co$ gamma-ray irradiated Poly(vinylidene fluoride) (PVDF) containing various antioxidants have been investigated for radiation degradation. Cole-Cole's circular arcs were induced from the results of temperature and frequency dependency of dielectric properties with radiation dose. The magnitude of polarization of PVDF was decreased by adding antioxidants. The values of dielectric relaxation intensity calculated by using the Cole-Cole's circular arcs showed a certain tendency for radiation degradation.

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Study on the Physicochemical Properties of Crosslinked Poly(Styrene-Butadiene-Styrene) Block Copolymers Prepared by Radiation (방사선으로 제조된 가교 구조의 Poly(Styrene-Butadiene-Styrene) 블록 공중합체 특성에 관한 연구)

  • Lee, Sun-Young;Song, Ju-Myung;Sohn, Joon-Yong;Shin, Junhwa
    • Journal of Radiation Industry
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    • v.6 no.2
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    • pp.171-176
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    • 2012
  • In this study, a crosslinked poly(styrene-butadiene-styrene) [SBS] block copolymers were prepared by using gamma ray irradiation method. The effects of various radiation doses on the degree of crosslinking, thermo property, and morphology of crosslinked SBS block copolymer were investigated. The degree of crosslinking of crosslinked SBS block copolymers were measured by gel-fraction and FT-IR. It was found that the degree of crosslinking of crosslinked SBS block copolymers increases with increase of the irradiation dose while the TGA result shows that the initial degradation temperature of irradiated SBS block copolymer was shifted to lower temperature with increasing irradiation dose. These results indicate that degradation reaction also occurs when SBS block copolymer is exposed to gamma ray irradiation for crosslinking reaction. The SAXS and FE-SEM results indicate that the phase separation of the styrene block and butadiene block was reduced with increasing irradiation dose.

Study of the Changes in Wood Properties by Gamma Irradiation (감마선 조사에 의한 목재성질 변화에 관한 연구)

  • Yoon, Min-Chul;Park, Byung-Soo;Kim, Ik-Joo;Choi, Jong-Il
    • Journal of the Korean Wood Science and Technology
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    • v.40 no.4
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    • pp.229-236
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    • 2012
  • This study was conducted to investigate the effect of gamma radiation on cell wall degradation, cellulose crystallinity, and flexural strength of Pinus densiflrora, Zelkova serrenata, and Paulownia tomentosa. By the gamma radiation at the dose up to 100 kGy, the cell wall degradation was not detected with scanning electron microscope (SEM) observation from all samples, and the flexural strength was not significantly changed. Cellulose crystallinity was neither changed by the gamma radiation. This high stability of wood against gamma radiation means that the radiation technology can be used for eradicating fungal and insect infestation of wood without the changes in wood properties.

Photocatalytic Degradation of Methylene Blue using $TiO_2$ Supported on Activated Carbon (TiO$_2$가 담지된 활성탄을 이용한 Methylene Blue의 광분해)

  • Lee, Jong-Dae;Lee, Tae-Jun;Cho, Kyong-Tae
    • Journal of the Korean Applied Science and Technology
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    • v.23 no.2
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    • pp.153-159
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    • 2006
  • The photocatalytic degradation of methylene blue(MB) was investigated using $TiO_2$ as photocatalyst and UV radiation. $TiO_2$ supported with activated carbon(AC) was prepared by SOL-GEL method and depended on several parameters such as the mass ratio of $TiO_2/AC$, pH and experimental time. The presence of the anatase and rutile crystal phase was determined by XRD analyses of the prepared $TiO_2$. The degradation of MB with $TiO_2/AC$ was about 20% higher than that of AC alone. A variation of photodegradation was negligible under UV radiation conditions ( ${\geq}$ 40W). It was experimentally showed that the photodegradation rate was increased with increasing the amount of photocatalyst. The optimal catalyst was prepared by impregmation of $5wt%-TiO_2$ with AC and was calcined at $300^{\circ}C$, and showed about 99% removal efficiency for 3hrs.

Effect of Radial Rays on Residual Voltage for EPR cable (EPR 케이블의 잔류전압에 미치는 방사선의 영향)

  • 이성일;류성림;김용추
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1999.05a
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    • pp.518-521
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    • 1999
  • This paper describes the properties of discharge current and the residual voltage for $^{60}$ C$_{0}$ -${\gamma}$ irradiated cables using in nuclear power generating station. As these properties related with $^{60}$ C$_{0}$ -${\gamma}$ -irradiatiation dose, it is suggested that these properties can be utilized as a index of irradiation degradation. As the ratio of degradation increases, the residual voltage in the initial time range increases and the peak moves to the shorter time. Therefore, I know the degree of radiation degradation from the position of the peak.

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The Improvements for Fire Retardancy and Radiation Resistance of Chloroprene Rubber (클로로프렌 고무의 난연성 및 내방사선 특성 향상)

  • Kim, Ki-Yup;Lee, Chung;Ryu, Boo-Hyung
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.11
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    • pp.1205-1211
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    • 2004
  • This study has investigated radiation degradation of chloroprene rubber in the presence of some fire retardant. Ammonium polyphosphate, aluminium trihydroxide, magnesium hydroxide, calcium carbonate and antimony trioxide were selected as flame retardant. Samples were irradiated using a Co$^{60}$ ${\gamma}$ -ray and ray up to 2000 kGy at a dose rate of 5 kGy/hr in the presence of air atmosphere at room temperature. After irradiation, samples were assessed fire retardancy with electrical properties and mechanical properties. Some considerations concerning the effects of the fire retardants added to chloroprene rubber on the radiation and thermal stability of chloroprene rubber are presented. From fire retardancy with electrical and mechanical property measurements, it was found that addition of magnesium hydroxide resulted in maximum fire retardant effect.

The Variation of Silicon Characteristic with Radiation Damage Effects (Radiation 손상에 기인한 실리콘 특성변화)

  • 장기현
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.15 no.4
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    • pp.26-32
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    • 1978
  • For a long life photovoltaic cell the degradation of the device characteristics with 1 MeV electron radiation must be known so as to be able to predict the life of the cell. Hence, a study was made of radiation damage effects on the bulk properties of the silicon crystal. From the results of the data, it is concluded that there appeared to be a steads rotate damage level reached in f type material.

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