• 한국전기전자재료학회논문지
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• 제20권8호
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• pp.742-747
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• 2007

In 2-dimensional SCBF (Spherically Convergent Beam Fusion) device, the effect on neutron production rate of the grid cathode geometry was simulated. The motion of Particles was tracked using Monte Carlo Method including the atomic and molecular collision processes and potential distribution was calculated by Finite Element Method, Main processes of the discharge were the ionization of $D_2$ by fast $D_2^+\;ion$. As the number of cathode rings was small and the size of grid cathode decreased, the ion current increased and neutron production rate will also increase. The star mode discharge which is a very important characteristic in SCBF device, was confirmed by the ionization position.

• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1234-1239
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• 2017

Basic research on the accelerator-driven system is conducted by combining $^{235}U$-fueled and $^{232}Th$-loaded cores in the Kyoto University Critical Assembly with the pulsed neutron generator (14 MeV neutrons) and the proton beam accelerator (100 MeV protons with a heavy metal target). The results of experimental subcriticality are presented with a wide range of subcriticality level between near critical and 10,000 pcm, as obtained by the pulsed neutron source method, the Feynman-${\alpha}$ method, and the neutron source multiplication method.

• 한국방사선학회논문지
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• 제1권1호
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• pp.45-49
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• 2007

동경공업대학교의 3MV 펠레트론가속기를 사용하여 10에서 90keV 영역에 대하여 $^{197}Au$의 중성자포획 스펙트럼을 측정하였다. 중성자 펄스빔은 $^7Li(p,n)^7Be$반응을 통하여 발생되었다. 사용되어진 양성자 빔의 폭은 1.5-ns였다. 금 시료에 입사된 중성자의 에너지 스펙트럼은 $^6Li$-glass 섬광검출기의 중성자 비행시간법을 사용하여 측정하였다. 금 시료의 중성자포획에 의해서 발생된 감마선은 anti-Compton NaI(TI) 검출장비를 사용하여 측정되었다. 본 연구에서는 5개의 중성자 에너지 역영을 선택했고, 각각의 에너지영역에서 얻어진 감마선파고스펙트럼을 표시하였다. 본 연구에서 얻어진 스펙트럼은 처음으로 얻어진 결과이며, 중성자 결합에너지부근에 몇 개의 천이 피크가 보인다.

• Nuclear Engineering and Technology
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• 제37권5호
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• pp.433-446
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• 2005

The development of accelerator science and technology has been accommodating ever increasing demand from scientific community of the beam energy and intensity of proton beams. The use of high-powered proton beams has extended from the traditional application of nuclear and high-energy physics to other applications, including spallation neutron source replacing nuclear reactor, nuclear actinide transmutation, energy amplification reactors. This article attempts to review development of proton accelerator, both linear and circular, and issues related to the proton beam energy, intensity as well as its output power. For related accelerator physics and technical review, one should refer to the recent article in the Reviews of Modem Physics [1]

• 한국진공학회지
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• 제16권1호
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• pp.7-14
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• 2007

수평형 중성자 반사율 측정 장치는, 나노 박막의 두께와 구성성분, 표면의 거칠기 등 그 구조와 더불어 나노 박막의 동역학적인 거동을 연구하는데 긴요한 측정 장치이다. 특히, 수평형이기 때문에 액체시료의 자유표면을 유지하며 표면을 분석하는 것이 가능하다. 30 MW의 하나로의 열중성자원에 적합하도록 최적화하기 위하여, 몬테카를로 수치해석 방법을 적용한 McStas를 사용하여 장치의 각 부분에서의 중성자의 빔을 추적 계산하였고 그 결과의 해석과 그에 따른 설계변수결정을 기술하였다. 최적화 상태에서 단색파장이 ${\lambda}=2.5{\AA}$ 이고 $q<0.126{\AA}^{-1}$ 그리고 시료위치에서 $10^4n/cm^2/s$ 이상의 중성자빔의 세기를 얻었다. 본 장치가 설치 완료되면 국내에서 나노박막의 구조를 연구하는데 크게 기여할 것이다.

• 한국진공학회지
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• 제14권3호
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• pp.119-125
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• 2005

원자로의 중성자 빔을 사용하는 수평형 반사율 장치는 중성자 고유의 투과성 및 낮은 에너지의 비파괴성과 함께 시편을 수평으로 놓을 수 있는 장점을 가지고 수 나노미터 이내의 박막의 두께와 밀도를 측정하기 위하여 활용되는 새로운 장치이다. 원자력연구소에 열 중성자를 기반으로 개발을 추진하고 있으나, 아직 국내에 설치되어 있지 않아서 장치의 개념 및 최적화를 위한 시뮬레이션이 시급하다. 따라서 열중성자에 해당하는 $2.5{\AA}$를 기반으로 몬테카를로 시뮬레이션을 이용하는 MCSTAS를 이용하여 장치의 개념을 설계하였다. 단색기와 collimator, 그리고 초거울등의 설계 및 각 변수들은 설계의 목표인 최대 Flux를 갖는 중성자 빔 세기를 고려하여 결정하였다.

• 한국진공학회지
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• 제14권3호
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• pp.132-137
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• 2005

국내 유일의 연구용 원자로인 하나로에 중성자 반사율 측정장치를 개발 설치하였다. 하나로 중성자 반사율 측정장치는 수직형 시료 배치를 가지며 입사 중성자 빔의 파장은 $2.459\;\AA$이다. 원자로 출력 24 MW에서 금줄방사화법을 이용하여 측정한 단색기 및 시료위치에서의 중성자속은 각각 $4.5\times10^9\;n/cm^2/sec,\;6.64\times10^6\;n/cm^2/sec4이었다. 또한 하나로 중성자 반사율 측정장치를 이용하여 d-PS, $SiO_2$등의 일부 기준 박막 시료에 대하여 반사율을 측정하고 구조 분석을 수행하였다. 장치 성능 평가 결과 장치 최소 반사율은 $\sim10^{-6}$, 측정 가능한 Q 영역은 $0.003\sim0.3\;\AA^{-1}$이었다.

• Journal of Radiation Protection and Research
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• 제42권3호
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• pp.141-145
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• 2017

Background: The concrete walls inside the vaults of cyclotron facilities are activated by neutrons emitted by the targets during radioisotope production. Reducing the amount of radioactive waste created in such facilities is very important in case they are decommissioned. Thus, we proposed a strategy of reducing the neutron activation of the concrete walls in cyclotrons during operation. Materials and Methods: A polyethylene plate and B-doped Al sheet (30 wt% of B and 2.5 mm in thickness) were placed in front of the wall in the cyclotron room of a radioisotope production facility for pharmaceutical use. The target was Xe gas, and a Cu block was utilized for proton dumping. The irradiation time, proton energy, and beam current were 8 hours, 30 MeV, and $125{\mu}A$, respectively. To determine a suitable thickness for the polyethylene plate set in front of the B-doped Al sheet, the neutron-reducing effects achieved by inserting such sheets at several depths within polyethylene plate stacks were evaluated. The neutron fluence was monitored using an activation detector and 20-g on de Au foil samples with and without 0.5-mm-thick Cd foil. Each Au foil sample was pasted onto the center of a polyethylene plate and B-doped Al sheet, and the absolute activity of one Au foil sample was measured as a standard using a Ge detector. The resulting relative activities were obtained by calculating the ratio of the photostimulated luminescence of each foil sample to that of the standard Au foil. Results and Discussion: When the combination of a 4-cm-thick polyethylene plate and B-doped Al sheet was employed, the thermal neutron rate was reduced by 78%. Conclusion: The combination of a 4-cm-thick polyethylene plate and B-doped Al sheet effectively reduced the neutron activation of the investigated concrete wall.

• Nuclear Engineering and Technology
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• 제48권1호
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• pp.189-199
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• 2016

Fast neutrons with a broad energy spectrum, with which it is possible to evaluate nuclear data for various research fields such as medical applications and the development of fusion reactors, can be generated by irradiating proton beams on target materials such as beryllium. To generate short-pulse proton beam, we adopted a deflector and slit system. In a simple deflector with slit system, most of the proton beam is blocked by the slit, especially when the beam pulse width is short. Therefore, the available beam current is very low, which results in low neutron flux. In this study, we proposed beam modulation using a buncher cavity to increase the available beam current. The ideal field pattern for the buncher cavity is sawtooth. To make the field pattern similar to a sawtooth waveform, a multiharmonic buncher was adopted. The design process for the multiharmonic buncher includes a beam dynamics calculation and three-dimensional electromagnetic simulation. In addition to the system design for pulsed proton generation, a test bench with a microwave ion source is under preparation to test the performance of the system. The design study results concerning the pulsed proton beam generation and the test bench preparation with some preliminary test results are presented in this paper.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.903-904
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• 2005