• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1354-1357
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• 2017

Characterization of special nuclear material may be performed using energy spectroscopy of either the neutron or gamma-ray emissions from the sample. Gamma-ray spectroscopy can be performed relatively easily using high-resolution semiconductors such as high-purity germanium. Neutron spectroscopy, by contrast, is a complex inverse problem. Here, results are presented for $^{252}Cf$ and PuBe energy spectra unfolded using a single EJ309 organic scintillator; excellent agreement is observed with the reference spectra. Neutron energy spectroscopy is also possible using a two-plane detector array, whereby time-of-flight kinematics can be used. With this system, energy spectra can also be obtained as a function of position. Spatial-dependent energy spectra are presented for neutron and gamma-ray sources that are in excellent agreement with expectations.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1406-1413
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• 2022

In this study, a diamond-based neutron scatter camera (DNSC) was developed for neutron spectroscopy in high flux environments. The DNSC was evaluated experimentally and through simulations. It was simulated using several Monte Carlo codes in a two-array layout. The two-array model included two diamond detectors. The simulation reconstructed the spectra of ²⁵²Cf and ²³⁹Pu-Be neutron sources with high accuracy (~93%). The two-diamond array system was experimentally evaluated, demonstrating the neutron spectroscopy capabilities of the DNSC. The reconstructed spectrum of the ²³⁹Pu-Be source manifested the characteristic peaks of the source. The advantage of a DNSC over a NSC is its ability to define any neutron double-scattering events without the need to absorb incident neutrons in the second detector, and atomic recoil energy information is not needed to determine the incident neutron energy.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3784-3789
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• 2021

We report a simple technique for direct neutron spectroscopy using pure LaCl₃ crystals. Pure LaCl₃ crystals exhibit considerably better pulse shape discrimination (PSD) capabilities with relatively good energy resolution as compared with Ce-doped LaCl₃ crystals. Single crystals of pure and Ce-doped LaCl₃ were grown using an inhouse-developed Bridgman furnace. PSD capabilities of these crystals were investigated using ²⁴¹Am and ¹³⁷Cs sources. Fast neutron detection was tested using a²⁵²Cf source and three separate bands corresponding to electron, proton, and alpha were observed. The proton band induced by the ³⁵Cl(n,p)³⁵S reaction can be used for direct neutron spectroscopy because proton energy is proportional to incident neutron energy. Owing to good scintillation performance and excellent PSD capabilities, pure LaCl₃ is a promising candidate for space detectors and other applications that necessitate gamma/fast neutron discrimination capability.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.201-208
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• 2023

The dependence of the electrical characteristics on the fast neutron fluence of an epitaxial 4H-SiC Schottky barrier diode (SBD) was investigated. The 30 MeV cyclotron was used for fast neutron irradiation. The neutron fluences evaluated through Monte Carlo simulation were in the 2.7 × 10¹¹ to 1.45 × 10¹³ neutrons/cm² range. Current-voltage and capacitance-voltage measurements were performed to characterize the samples by extracting the parameters of the irradiated SBDs. Neutron-induced defects in the epitaxial layer were identified and quantified using a deep-level transient spectroscopy measurement system developed at the Korea Atomic Energy Research Institute. As the neutron fluence increased from 2.7 × 10¹¹ to 1.45 × 10¹³ neutrons/cm², the concentration of the Z_1/2 defects increased by approximately 20 times. The maximum defect concentration was estimated as 1.5 × 10¹⁴ cm^-3 at a neutron fluence of 1.45 × 10¹³ neutrons/cm².

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3121-3125
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• 2023

Neutron conversion detectors that use ¹⁰B-enriched boron carbide are feasible alternatives to ³He-based detectors. We prepared boron carbide films at micron-scale thickness using direct-current magnetron sputtering. The structural characteristics of natural B₄C films, including density, roughness, crystallization, and purity, were analyzed using grazing incidence X-ray reflectivity, X-ray diffraction, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and scanning electron microscopy. A beam profile test was conducted to verify the practicality of the ¹⁰B-enriched B₄C neutron conversion layer. A clear profile indicated the high quality of the neutron conversion of the boron carbide layer.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2014년도 자성 및 자성재료 국제학술대회
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• pp.15-15
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• 2014

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.209-214
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• 2023

The effect of thermal annealing on defect recovery of in-core neutron-irradiated 4H-SiC was investigated. Au/SiC Schottky diodes were manufactured using a 4H-SiC epitaxial wafer that was neutron-irradiated at the HANARO research reactor. The electrical characteristics of their epitaxial layers were analyzed under various conditions, including different neutron fluences (1.3 × 10¹⁷ and 2.7 × 10¹⁷ neutrons/cm²) and annealing times (up to 2 h at 1700 ℃). Capacity-voltage measurements showed high carrier compensation in the neutron-irradiated samples and a recovery tendency that increased with annealing time. The carrier density could be recovered up to 77% of the bare sample. Deep-level-transient spectroscopy revealed intrinsic defects of 4H-SiC with energy levels 0.47 and 0.68 eV below the conduction-band edge, which were significantly increased by in-core neutron irradiation. A previously unknown defect with a high electron-capture cross-section was discovered at 0.36 eV below the conduction-band edge. All defect concentrations decreased with 1700 ℃ annealing; the decrease was faster when the defect level was shallow.

• 분석과학
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• 제16권1호
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• pp.12-24
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• 2003

$^{252}Cf$ 중성자 선원을 이용한 즉발감마선 계측 시스템 (NIPS, Neutron Induced Promp ${\gamma}$-ray Spectroscopy)을 설계 및 구성하기 위하여, 시스템내의 감속제 및 차폐체등의 효과를 시험하고 감마선 바탕값과 Cl을 포함한 시료의 즉발 감마선을 계측하였다. 이를 위한 예비시험으로 한국원자력연구소 내에 있는 TLD 판독용 $^{252}Cf$ 선원을 이용하였으며 즉발감마선은 시스템 내부의 동축형 HPGe (GMX, 60% relative efficiency)과 시스템외부 (약 20m 거리)의 Notebook PC 중성자와 감마선의 바탕값을 측정하고, 바탕값을 최소로 할 수 있는 차폐체의 기하학적 구조를 고안하였다. 감마선 바탕값을 최소화하기 위하여 두 개의 HPGe 검출기를 이용한 감마-감마 동시계측법을 이용하였다. 이 실험 자료를 이용하여 최적의 NIPS 시스템을 구성하였다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2004년도 학술논문집
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• pp.433-433
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• 2004

Neutron induced prompt gamma-ray spectroscopy (NIPS) system measures the prompt gamma-ray, emitting by the interaction of a neutron with various materials. This system will be of great benefit to scientists worldwide, since it provides the non-destructive measurement of many elements in either solid or liquid wastes. A NIPS facility has been developed in Nuclear Chemistry Research Division, at Korea Atomic Energy Research Institute (KAERI) with the aim of analyzing the major component elements in both aqueous and solid samples.(omitted)

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.3012-3017
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• 2021

The spatial distribution and the energy spectrum of the neutron yield were investigated with the neutron activation analysis and MCNP simulation was carried out to verify the analysis results and to extend the results to a 3D mapping of the neutron yield distribution in the KSTAR. High purity Ni specimen was selected in the neutron activation analysis. Total neutron yields turned out to be 3.76 × 10¹² n/s - 7.56 × 10¹² n/s at the outer vessel of the KSTAR, two orders of magnitude lower than those at the inner vessel of the KSTAR, which demonstrates the attenuation of neutron yield while passing through the different structural materials of the reactor. Based on the fully expanded 3D simulation results, 2D cross-sectional distributions of the neutron yield on XY and ZX planes of KSTAR were examined. The results reveal that the neutron yield has its maximum concentration near the center of blanket and decreases with increasing proximity to the vacuum vessel wall.