• Title/Summary/Keyword: Radiation Damage Theory

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Radiation-induced thermal conductivity degradation modeling of zirconium

  • Sangil Choi;Hyunmyung Kim;Seunghwan Yu
    • Nuclear Engineering and Technology
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    • v.56 no.4
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    • pp.1277-1283
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    • 2024
  • This study presents a radiation-induced thermal conductivity degradation (TCD) model of zirconium as compared to the conventional UO2 TCD model. We derived the governing factors of the radiation-induced TCD model, such as maximum TCD value and temperature range of TCD. The maximum TCD value was derived by two methods, in which 1) experimental result of 32 % TCD was directly utilized as the maximum TCD value and 2) a theoretical approach based on dislocation was applied to derive the maximum TCD value. Further, the temperature range of TCD was determined to be 437-837 K by 1) experimental results of post-annealing of irradiation hardening as compared to 2) the rate theory and thermal equilibrium. Consequently, the radiation-induced TCD model of zirconium was derived to be $f_r=1-{\frac{0.32}{1+{\exp}\,\{(T-637)/45\}}}$. Because the thermal conductivity of zirconium is one of the factors determining the storage and transport system, this newly proposed model could improve the safety analysis of spent fuel storage systems.

RADIATION-INDUCED DISLOCATION AND GROWTH BEHAVIOR OF ZIRCONIUM AND ZIRCONIUM ALLOYS - A REVIEW

Radiation Damage of SiC Detector Irradiated by High Dose Gamma Rays

  • Kim, Yong-Kyun;Kang, Sang-Mook;Park, Se-Hwan;Ha, Jang-Ho;Hwang, Jong-Sun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.12a
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    • pp.87-90
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    • 2006
  • Two SiC radiation detector samples were irradiated by Co-60 gamma rays. The irradiation was performed with dose rates of 5 kGy/hour and 15 kGy/hour for 8 hours, respectively. Metal/semiconductor contacts on the surface were fabricated by using a thermal evaporator in a high vacuum condition. The SiC detectors have metal contacts of Au(2000 ${\AA}$)/Ni(300 ${\AA}$) at Si-face and of Au(2000 ${\AA}$)/Ti(300 ${\AA}$) at C-face. I-V characteristics of the SiC semiconductor were measured by using the Keithley 4200-SCS parameter analyzer with voltage sources included. From the I-V curve, we analyzed the Schottky barrier heights(SBHs) on the basis of the thermionic emission theory. As a result, the 6H-SiC semiconductor showed- similar Schottky barrier heights independent to the dose rates of the irradiation with Co-60 gamma rays.

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Collision Simulation of a Floating Offshore Wind Turbine Considering Ductile Fracture and Hydrodynamics Using Hydrodynamic Plug-in HydroQus

  • Dong Ho Yoon;Joonmo Choung
    • Journal of Ocean Engineering and Technology
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    • v.37 no.3
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    • pp.111-121
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    • 2023
  • This paper intends to introduce the applicability of HydroQus to a problem of a tanker collision against a semi-submersible type floating offshore wind turbine (FOWT). HydroQus is a plug-in based on potential flow theory that generates interactive hydroforces in a commercial Finite element analysis (FEA) code Abaqus/Explicit. Frequency response analyses were conducted for a 10MW capacity FOWT to obtain hydrostatic and hydrodynamic constants. The tanker was modeled with rigid elements, while elastic-plastic elements were used for the FOWT. Mooring chains were modeled to implement station keeping ability of the FOWT. Two types of fracture models were considered: constant failure strain model and combined failure strain model HC-LN model composed of Hosford-Coulomb (HC) model & localized necking (LN) model. The damage extents were evaluated by hydroforces and failure strain models. The largest equivalent plastic strain observed in the cases where both restoring force and radiation force were considered. Stress triaxiality and damage indicator analysis showed that the application of HC-LN model was suitable. It could be stated that applications of suitable failure strain model and hydrodynamics into the collision simulations were of importance.

Quantitative Estimation of Radiation Damage in Reactor Pressure Vessel Steels by Using Multiscale Modeling (멀티스케일 모델링을 이용한 압력용기강의 조사손상 정량예측)

  • Lee, Gyeong-Geun;Kwon, Junhyun
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.10 no.1
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    • pp.113-121
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    • 2014
  • In this work, an integrated model including molecular dynamics and chemical rate theory was implemented to calculate the growth of point defect clusters(PDC) and copper-rich precipitates(CRP) which could change the mechanical properties of reactor pressure vessel(RPV) steels in a nuclear power plant. A number of time-dependent differential equations were established and numerically integrated to estimate the evolution of irradiation defects. The calculation showed that the concentration of the vacancies was higher than that of the self-interstitial atoms. The higher concentration of vacancies induced a formation of the CRPs in the later stage. The size of the CRPs was used to estimate the mechanical property changes in RPV steels, as is the same case with the PDCs. The calculation results were compared with the measured values of yield strength change and Charpy V-notch transition temperature shift, which were obtained from the surveillance test data of Korean light water reactors(LWRs). The estimated values were in fair agreement with the experimental results in spite of the uncertainty of the modeling parameters.

Waveload Analysis for Heeled Barges with Flooded Compartments (손상침수로 자세변화된 바지형 선박의 파랑하중해석)

  • Hong, Do-Chun;Hong, Sa-Young
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.4 s.142
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    • pp.379-387
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    • 2005
  • A ship may suffer sinkage and heel due to flood in a compartment caused by damage on a deck. The motion and waveloads of the heeled ship floating in waves have been analyzed by making use of a three dimensional potential theory taking account of the hydrodynamic pressure in the flooded compartments. The shear forces and bending moments due to radiation-diffraction waves have been calculated by the direct integration of the 3-d hydrodynamic pressure on the outer and inner hulls of floating barges. The motion responses and the relative flow rate across the mean free surface of the water in the flooded compartments are also presented.

From Hiroshima to Fukushima: Nuclear and Artist Response in Japan (히로시마에서 후쿠시마까지, 핵과 미술가의 대응)

  • Choi, Tae Man
    • The Journal of Art Theory & Practice
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    • no.13
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    • pp.35-71
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    • 2012
  • The purpose of this essay is to examine the responses of artists on nuclear experiences through an analysis of the nuclear images represented in contemporary Japanese art. Japan has previously as twice experienced nuclear disaster in 20th century. The first atomic bombs were dropped in 1945 as well as the 5th Fukuryumaru, Japanese pelagic fishing boat, exposed by hydrogen bomb test operated by the US in 1954 nearby Bikini atoll. Due to Tsunami taken place by the great earthquake that caused the meltdown of Fukushima Nuclear Power Plant in March 2010, Japan is being experienced a nuclear disaster again. Despite practical experiences, comtemporary Japanese art has avoided the subject of nuclear disasters since the end of the Asia-Pacific War for a variety of reasons. Firstly, GHQ prohibited to record or depict the terrible effect of atomic bomb until 1946. Secondly, Japanese government has tried to sweep the affair under the carpet quite a while a fact of nuclear damage to their people. Because Japan has produced numerous war record paintings during the Second World War, in the aftermath of the defeated war, most of Japanese artists thought that dealing with politics, economics, and social subject was irrelevant to art as well as style of amateur in order to erase their melancholic memory on it. In addition, silence that was intended to inhibit victims of nuclear disasters from being provoked psychologically has continued the oblivion on nuclear disasters. For these reasons, to speak on nuclear bombs has been a kind of taboo in Japan. However, shortly after the atomic bomb dropped on Hiroshima, the artist couple Iri and Toshi Maruki visited to ruin site as a volunteer for Victim Relief. They portrayed the horrible scenes of the legacy of nuclear bomb since 1950 based on their observation. Under the condition of rapid economical growth in 1960s and 1970s, Japanese subculture such as comics, TV animations, plastic model, and games produced a variety of post apocalyptic images recalling the war between the USA and Japanese militarism, and battle simulation based on nuclear energy. While having grown up watching subculture emerged as Japan Neo-Pop in 1990s, New generation appreciate atomic images such as mushroom cloud which symbolizes atomic bomb of Hiroshima. Takashi Murakami and other Neo-Pop artists appropriate mushroom cloud image in their work. Murakami curated three exhibitions including and persists in superflat and infantilism as an evidence in order to analyze contemporary Japanese society. However, his concept, which is based on atomic bomb radiation exposure experience only claimed on damage and sacrifice, does not reflect Japan as the harmer. Japan has been constructing nuclear power plants since 1954 in the same year when the 5th Fukuryumaru has exposed until the meltdown of Fukushima Nuclear Plant although took place of nuclear radiation exposures of Three Mile and Chernobyl. Due to the exploding of Fukushima Nuclear Power Plant, Japan reconsiders the danger of nuclear disaster. In conclusion, the purpose of this paper may be found that the sense of victim which flowed in contemporary art is able to inquire into the response of artist on the subject of nuclear as well as the relationship between society, politics, culture, and modern history of Japan and international political situation.

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