• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2139-2146
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• 2023

During reactor operation, the divertor must withstand unprecedented simultaneous high heat fluxes and high-energy neutron irradiation. The extremely severe service environment of the divertor imposes a huge challenge to the bonding quality of divertor joints, i.e., the joints must withstand thermal, mechanical and neutron loads, as well as cyclic mode of operation. In this paper, potassium-doped tungsten (KW) is selected as the plasma facing material (PFM), oxygen-free copper (OFC) as the interlayer, oxide dispersion strengthened copper (ODS-Cu) alloy as the heat sink material, and reduced activation ferritic/martensitic (RAFM) steel as the structural material. In this study, a vacuum brazing technology is proposed and optimized to bond Cu and ODS-Cu alloy with the silver-free brazing material CuSnTi. The most appropriate brazing parameters are a brazing temperature of 940 ℃ and a holding time of 15 min. High-quality bonding interfaces have been successfully obtained by vacuum brazing technology, and the average shear strength of the as-obtained KW/Cu and ODS-Cu alloy joints is ~268 MPa. And a fabrication route for manufacturing the flat-type divertor target based on brazing technology is set. For evaluating the reliability of the fabrication technologies under the reactor relevant condition, the high heat flux test at 20 MW/m² for the as-manufactured flat-type KW/Cu/ODS-Cu/RAFM mockup is carried out by using the Electron-beam Material testing Scenario (EMS-60) with water cooling. This paper reports the improved vacuum brazing technology to connect Cu to ODS-Cu alloy and summarizes the production route, high heat flux (HHF) test, the pre and post non-destructive examination, and the surface results of the flat-type KW/Cu/ODS-Cu/RAFM mockup after the HHF test. The test results demonstrate that the mockup manufactured according to the fabrication route still have structural and interfacial integrity under cyclic high heat loads.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1526-1531
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• 2024

¹³¹I is a fission product produced in a nuclear reactor by irradiating tellurium dioxide, with a half-life of 8.02 day. The most important and widely used method for making ¹³¹I is irradiation using a nuclear reactor and post-irradiation followed by dry distillation. The advantage of the dry distillation process is that the process and the equipment are relatively simple, namely TeO₂ (m.p. 750 ℃), which can withstand heating during reactor irradiation. Based on TeO₂ irradiation by neutron following the technique of dry distillation was explained for production of ¹³¹I on a large scale. A dry distillation followed the radioisotope production operation using the 30 MW GA Siwabessy nuclear reactor to meet national demand. TeO₂ targets are 25 and 50 g irradiated for 87-100 h. The resulting ¹³¹I activity is 20.29339-368.50335GBq. According to the requirements imposed on the radionuclide purity of the preparation, the contribution of ¹³¹I training in the resulting preparation was not less than 99.9 %

• Nuclear Engineering and Technology
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• 제3권3호
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• pp.148-154
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• 1971

원자로를 여러가지 불연속적 방법으로 가동시킬 때 얻어지는 방사성동위원소의 생성량을 구하는 식을 안출하였다. 특히 현재 우리나라 원자로의 가동조건인 월요일부터 목요일까지 매일 평균 8.2시간을 가동하고 금요일과 일요일은 가동치 않고 토요일은 평균 3.2시간으로 가동하는 조건을 중점적으로 다루었다. 이 경우의 activity를 구하는 식은 생성동위원소가 제 2의 핵반응으로 소실되지 않을 경우에는 (equation omitted) 가 된다. 여기서 A: activity (dps), $\Phi$: 중성자속(n $cm^{-2}$ sec$^{-1}$), No: 조사되기전 원자수, $\sigma$: 방사화단면적($\textrm{cm}^2$), λ: 생성방사성동위원소의 붕괴상수($hr^{-1}$), t： 조사하기 시작해서 끄집어낼 때까지의 시간(hr), n: 조사일수, m:금요일이 처음 나타날 때까지의 조사일 수, s, r, q: 조사기간중 금요일, 토요일 및 일요일이 나타난수를 각각 뜻한다. 윗식은 거의 고정항들로 구성되 있으므로 각 동위원소에 대해 이 고정항들을 계산하여 그 값을 구해 도표를 만들어 이 식이 보다 편리하게 이용되도록 하였다.

• 분석과학
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• 제18권1호
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• pp.5-12
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• 2005

고정밀 전자소자의 오동작의 한 원인인 soft error는 원료물질에 함유된 U, Th과 같은 알파방출 불순물로 알려져 있으며 전자소자의 소형화, 고집적화에 따라서 이들 불순물의 규제함량은 기존의 분석법으로는 불가능할 정도로 낮아지고 있다. 연구의 목적은 다양한 전자소자의 밀봉소재로 사용되는 EMC (epoxy molding compound)의 주 원료인 고순도 실리카에 함유되어 있는 U, Th을 고감도 (ng/g이하)로 분석할 수 있는 방사화분석법과 감마선분광분석법의 개발이다. 지금까지 방사화분석법에 이용하던 PTS (pneumatic transfer system) 중성자 조사 설비로는 산업계에서 요구하는 분석 감도를 충족시킬 수 없기 때문에 의약용 혹은 산업용 RI 생산에 주로 사용되고 있는 HTS (Hydraulic transfer system) 중성자 조사 설비를 이용한 방사화분석 조건을 확립하였다. 또한, 공기중 라돈 ($^{222}Rn$)과 자핵종 (progenies)에 의한 불안정한 바탕방사능은 분석의 감도는 물론 정확도를 저하시키는 주 요인으로 작용하므로 질소가스 유입시스템을 제작하여 라돈에 의한 바탕방사능을 소멸 혹은 안정화시켰다. 그 결과 U과 Th의 분석한계를 각각 0.1 ng/g, 0.01 ng/g까지 낮출 수 있었다.

• 한국세라믹학회지
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• 제51권5호
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• pp.418-423
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• 2014

Fully ceramic micro encapsulated (FCM) nuclear fuel is a concept recently proposed for enhancing the stability of nuclear fuel. FCM nuclear fuel consists of tristructural-isotropic (TRISO) fuel particles within a SiC matrix. Each TRISO fuel particle is composed of a $UO_2$ kernel and a PyC/SiC/PyC tri-layer which protects the kernel. The SiC ceramic matrix is created by sintering. In this FCM fuel concept, fission products are protected twice, by the TRISO coating layer and by the SiC ceramic. The SiC ceramic has proven attractive for fuel applications owing to its low neutron-absorption cross-section, excellent irradiation resistivity, and high thermal conductivity. In this study, a SiC-matrix composite containing TRISO particles was sintered by hot pressing with $Al_2O_3-Y_2O_3$ additive system. Various sintering conditions were investigated to obtain a relative density greater than 95%. The internal distribution of TRISO particles within the SiC-matrix composite was observed using an x-ray radiograph. The fracture of the TRISO particles was investigated by means of analysis of the cross-section of the SiC-matrix composite.

• 한국진공학회지
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• 제6권S1호
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• pp.96-109
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• 1997

In order to simulate the corrosion behavior of Zr-4 alloy in pressurized water reactors it was implanted (or bombarded) with 190ke V $Zr^+\; and \;Ar^+$ ions at liquid nitrogen temperature and room temperature respectively up to a dose of $5times10^{15} \sim 8\times10^{16} \textrm{ions/cm}^2$ The oxidation behavior and electrochemical vehavior were studied on implanted and unimplanted samples. The oxidation kinetics of the experimental samples were measured in pure oxygen at 923K and 133.3Pa. The corrosion parameters were measured by anodic polarization methods using a princeton Applied Research Model 350 corrosion measurement system. Auger Electron Spectroscopy (AES) and X-ray Photoelectric Spectroscopy (XPS) were employed to investigate the distribution and the ion valence of oxygen and zirconium ions inside the oxide films before and after implantation. it was found tat: 1) the $Zr^+$ ion implantation (or bombardment) enhanced the oxidation of Zircaloy-4 and resulted in that the oxidation weight gain of the samples at a dose of $8times10^{16}\textrm{ions/cm}^2$ was 4 times greater than that of the unimplantation ones;2) the valence of zirconium ion in the oxide films was classified as $Zr^0,Zr^+,Zr^{2+},Zr^{3+}\; and \;Zr^{4+}$ and the higher vlence of zirconium ion increased after the bombardment ; 3) the anodic passivation current density is about 2 ~ 3 times that of the unimplanted samples; 4) the implantation damage function of the effect of ion implantation on corrosion resistance of Zr-4 alloy was established.

• Journal of Nutrition and Health
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• 제31권2호
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• pp.206-212
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• 1998

This study was undertaken to analyze the iodine content in commonly donsumed Korean foods. Food samples were purchased from 3 randomly selected markets. The iodine contents in foods were determined by nuetron activation analysis (NAA). All irradiation of food samples were done at a pnueumatic transfer system (thermal nuetron flux : 1 $\times$1013n/$\textrm{cm}^2$.s) of the TRIGA MarkIII research reactor in the Korea Atomic Energy Research Institute . The results indicated that the iodine content was high in seaweeds, fishes, and iodine-enriched eggs in that order and very low in grain, beans , fruits and vegetables. Edible seaweeds contained iodine levels of between 13,700 and 1,790, 600$\mu\textrm{g}$/kg. Levels of iodine in fishes and shellfishes were between 478 and 2, 840$\mu\textrm{g}$/kg. Ordinary eggs contained 314$\mu\textrm{g}$/kg iodine, but iodine -enriched eggs contained 1,869$\mu\textrm{g}$/kg. The average concentration of iodine in milk was 207$\mu\textrm{g}$/kg. There was seasonal variation in the iodine content of milk , levels were highest in winter milk(230$\mu\textrm{g}$/kg) and lowest in summer milk(180$\mu\textrm{g}$/kg).The idodine contents of most vegetables and fruits were below 10$\mu\textrm{g}$/kg. The iodine contents of most vegetables and fruits were below 10$\mu\textrm{g}$/kg. From high to low , the sequence of foods with high iodine content in one serving was as follows ; sea tangle , sea mustard, iodine-enriched eggs, fish , laver and milk. This study may provide basic data on the iodine content of foods consumed by Korean which have not yet been analyzed .

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.291-295
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• 2007

FTL(Fuel Test Loop) is a facility that confirms performance of nuclear fuel at a similar irradiation condition with that of nuclear power plant. FTL consists of In-Pile Test Section (IPS) and Out-Pile System (OPS). FTL construction work began on August, 2006 and ended on March, 2007. During Construction, ensuring the worker's safety was the top priority and installation of the FTL without hampering the integrity of the HANARO was the next one. Task Force Team was organized to do a construction systematically and the communication between members of the task force team was done through the CoP(community of Practice) notice board provided by the Institute. The installation works were done successfully overcoming the difficulties such as on the limited space, on the radiation hazard inside the reactor pool, and finally on the shortening of the shut down period of the HANARO. Without a sweet of the workers of the participating company of HEC(Hyundae Engineering Co, Ltd), HDEC(HyunDai Engineering & Construction Co. Ltd), equipment manufacturer, and the task force team, it is not possible to install the FTL facility within the planned shutdown period. The Commissioning of the FTL is on due to check the function and the performance of the equipment and the overall system as well. The FTL shall start operation with high burn up test fuels in early 2008 if the commissioning and licensing progress on schedule.

• 분석과학
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• 제18권1호
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• pp.23-26
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• 2005

셀렌은 항산화 작용을 하는 미량 원소로 잘 알려져 있으며 많은 고객들은 다양한 식품시료중의 셀렌의 농도 및 정량에 관심을 갖고 있다. 본 연구에서는 $^{75}Se$과 $^{77m}Se$ 핵종을 이용한 중성자 방사화 분석법에 의한 생물시료중의 셀렌 분석법을 확립하고 비교하고자 하였다. 이를 위하여 미국표준연구원의 3종의 인증 표준물질을 선택하여 미리 설정된 분석조건 (조사, 냉각 및 측정시간) 하에서 셀렌의 농도를 결정하였다. 두 가지 분석방법에 의한 측정값을 인증값과 평가하였으며 $^{75}Se$과 $^{77m}Se$의 측정값에 대한 검출한계와 불확도를 서로 비교 하였다.

• 대한핵의학회지
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• 제28권2호
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• pp.227-233
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• 1994

Irradiation of 20mg of natural $Dy(NO_3)_3$ in a neutron flux of $2{\times}10^{13}n/cm^2$ sec for 4 hours gave 5.76 Ci of $^{165}Dy$(specific activity, 610mCi/mg Dy) with high radionuclidic purity (>99.9 %). $^{165}Dy-MA$ was prepared in a quantitative yield by reacting the aqueous solution of $^{165}Dy(NO_3)_3$ with sodium borohydride solution in 0.2N NaOH. Coulter particle analyzer exhibited mean particle size of $2.6{\mu}m$ (range $1{\sim}6{\mu}m$), Even though the $^{165}Dy-MA$ suspension in saline was stored at $37^{\circ}C$ for 24 hours or autoclaved at $121^{\circ}C$ for 30minutes, there was no significant change in particle size and leakage problem indicating the prepared $^{165}Dy-MA$ is sufficiently stable. In-vivo retention studies were carried out by administering $^{165}Dy-MA$ into the knee joint space of normal rabbits. Gamma camera analysis showed high retention in joint space of normal rabbits. Gamma camera analysis showed high retention in joint space even at 24 hours after administration (> 99.9%). The ease with which the $^{165}Dy-MA$ can be made in the narrow size range and their high invitro and vivo stability make them attractive agents for radiation synovectomy.