• 제목/요약/키워드: fuel burn-up

검색결과 88건 처리시간 0.048초

고연소도 신형 Zr피복관의 미세조직과 기계적 특성에 미치는 열처리 및 중성자 조사의 영향 (Effects of Annealing and Neutron Irradiation on Micostructural and Mechanical Properties of High Burn-up Zr Claddings)

  • 백종혁;김현길;정용환
    • 열처리공학회지
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    • 제17권3호
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    • pp.151-164
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    • 2004
  • The changes of microstructural and mechanical properties were evaluated for the high burn-up fuel claddings after the neutron irradiation of $1.8{\sim}3.1{\times}10^{20}n/cm^2$ (E>1.0 MEV) in HANARO research reactor. After the irradiation, the spot-type dislocations (a-type dislocations) were easily observed in most claddings, and the density of the dislocations was different depending on the grains and was higher at grain boundaries than within grains. As the final annealing temperature increased, the density of spot-type dislocations increased and the line-type dislocations (c-type dislocations) which was perpendicular to the <0002> direction, appeared sporadically in some claddings. However, the types of precipitates in the fuel claddings after the irradiation were not changed from that in unirradiated claddings. The mechanical properties including the hardness, strength and elongation after the irradiation were changed due to the formation of spot-type dislocations. That is, the increase in hardness and strength as well as the decrease in elongation after the irradiation was occurred simultaneously with increasing the final annealing temperature. Owing to the Nb contribution to the formation of spot-type dislocation during the irradiation, the increase in hardness and strength in higher Nb-contained Zr alloys after the irradiation was higher than that in lower Nb-contained Zr alloys.

A Study on the Sensitivity of Self-Powered Neutron Detectors(SPNDs) and a new Proposal

  • Lee, Wanno;Gyuseong Cho
    • 한국원자력학회:학술대회논문집
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    • 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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    • pp.445-450
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    • 1997
  • Self-Powered Neutron Detectors(SPNDs) are currently used to estimate the power generation distribution and fuel burn-up in several nuclear power reactors in Korea. In this paper, Monte Carlo simulation is accomplished to calculate the escape probability of beta particle as a function of their birth position fur the typical geometry of rhodium-based SPNDs. Also, a simple numerical method calculates the initial generation rate of beta particles and the change of generation rate due to rhodium burn-up. Using the simulation and the numerical method, the burn-up profile of rhodium density and the neutron sensitivity are calculated as a function of burn-up time in the reactor. The sensitivity of the SPNDs decreases non-linearly due to the high absorption cross-section and the non-uniform burn-up of rhodium in the emitter rod. In addition, for improvement of some properties of rhodium-based SPNDs which are currently used, this paper presents a new material. The method used here can be applied to the analysis of other types of SPNDs and will be useful in the optimum design of new SPNDs for long term usage.

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Stable In-reactor Performance of Centrifugally Atomized U-l0wt.%Mo Dispersion Fuel at Low Temperature

  • Kim, Ki-Hwan;Kwon, Hee-Jun;Park, Jong-Man;Lee, Yoon-Sang;Kim, Chang-Kyu
    • Nuclear Engineering and Technology
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    • 제33권4호
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    • pp.365-374
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    • 2001
  • In order to examine the in-reactor performance of very-high-density dispersion fuels for high flux performance research reactors, U-l0wt.%Mo microplates containing centrifugally atomized powder were irradiated at low temperature. The U-l0wt.%Mo dispersion fuels show stable in- reactor irradiation behaviors even at high burn-up, similar to U$_3$Si$_2$ dispersion fuels. The atomized U-l0wt.%Mo fuel particles have a fine and a relatively uniform fission gas bubble size distribution. Moreover, only one of third of the area of the atomized fuel cross-sections at 70a1.% burn-up shows fission gas bubble-free zones, This appears to be the result of segregation into high Mo and low Mo.

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사용후핵연료 길이에 따른 심지층 처분시스템 분석 (An Analysis on the Deep Geological Disposal Concepts Considering the Spent Fuel Length)

  • 이종열;김현아;이민수;최희주;김건영
    • 방사성폐기물학회지
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    • 제13권3호
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    • pp.201-209
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    • 2015
  • 우리나라에서는 현재 23기의 원자력발전소를 운영 중에 있으며, 이들 원자력발전소로부터 발생하는 사용후핵연료를 처분대상으로 기준 심지층 처분시스템을 개발한 바 있다. 현재 이 기준 심지층 처분시스템은 초기농축도 4.5wt%, 방출연소도 55 GWd/MtU의 40 년 냉각된 사용후핵연료를 기준으로 하고 있다. 본 논문에서는 처분효율 및 경제성 향상 방안의 일환으로서 사용후핵연료의 종류 및 연소도 특성 등 발생특성을 검토하였다. 그리고 기준 사용후핵연료에 비하여 길이가 짧고 연소도가 비교적 낮은 사용후핵연료에 대한 처분용기 개념을 도출하고 열해석을 수행하여 처분시스템 개념을 제시하였다. 또한, 이 처분시스템 개념과 기준 사용후핵연료 처분시스템 개념을 처분밀도, 처분면적 등의 처분효율 및 구리와 벤토나이트 소요량 등 경제성 관점에서 비교 분석한 결과 약 20% 이상 향상을 보이는 것을 확인하였다. 본 분석결과는 사용후핵연료 관리정책 수립 및 실제 처분시스템 설계에 활용될 수 있을 것으로 사료된다.

Focused ion beam-scanning electron microscope examination of high burn-up UO2 in the center of a pellet

  • Noirot, J.;Zacharie-Aubrun, I.;Blay, T.
    • Nuclear Engineering and Technology
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    • 제50권2호
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    • pp.259-267
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    • 2018
  • Focused ion beam-scanning electron microscope and electron backscattered diffraction examinations were conducted in the center of a $73\;GWd/t_U\;UO_2$ fuel. They showed the formation of subdomains within the initial grains. The local crystal orientations in these domains were close to that of the original grain. Most of the fission gas bubbles were located on the boundaries. Their shapes were far from spherical and far from lenticular. No interlinked bubble network was found. These observations shed light on previous unexplained observations. They plead for a revision of the classical description of fission gas release mechanisms for the center of high burn-up $UO_2$. Yet, complementary detailed observations are needed to better understand the mechanisms involved.