Target-Moderator-Reflector system for 10-30 MeV proton accelerator-driven compact thermal neutron source: Conceptual design and neutronic characterization

Jeon, Byoungil,Kim, Jongyul,Lee, Eunjoong,Moon, Myungkook,Cho, Sangjin,Cho, Gyuseong Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.3

Imaging and scattering techniques using thermal neutrons allow to analyze complex specimens in scientific and industrial researches. Owing to this advantage, there have been a considerable demand for neutron facilities in the industrial sector. Among neutron sources, an accelerator driven compact neutron source is the only one that can satisfy the various requirements-construction budget, facility size, and required neutron flux-of industrial applications. In this paper, a target, moderator, and reflector (TMR) system for low-energy proton-accelerator driven compact thermal neutron source was designed via Monte Carlo simulations. For 10-30 MeV proton beams, the optimal conditions of the beryllium target were determined by considering the neutron yield and the blistering of the target. For a non-borated polyethylene moderator, the neutronic properties were verified based on its thickness. For a reflector, three candidates-light water, beryllium, and graphite-were considered as reflector materials, and the optimal conditions were identified. The results verified that the neutronic intensity varied in the order beryllium > light water > graphite, the compacter size in the order light water < beryllium < graphite and the shorter emission time in the order graphite < light water < beryllium. The performance of the designed TMR system was compared with that of existing facilities and were laid between performance of existing facilities.

Measurements of Neutron-Induced Neutron-Production Double-Differential Cross Sections from 50 to 150 MeV

T. Kajimoto,N. Shigyo,K. Ishibashi,D. Moriguchi,Y. Nakamura,H. Arakawa,S. Kunieda,T. Watanabe,R. C. Haight 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

We measured neutron-production double-differential cross-sections by neutron incidence from 50 to 150 MeV. A ^(238)U fission ionization chamber was set to take the incident-neutron flux. Six NE213 liquid scintillators which had a thickness of 12.7 cm and 12.7 cm in diameter, were placed at 15˚, 30˚, 60˚, 90˚, 120˚, and 150˚ to detect neutrons emitted from a sample. The energy of incident neutron was determined by the time of flight (TOF) technique. The energy spectra of neutron emitted from the sample were derived by the unfolding their light output spectra with the response functions of the detectors. The response functions were measured with the spallation neutrons above 25 MeV. In the unfolding process, we assumed that neutron energy spectra reproduced the shape by the moving source model. The neutron-induced neutron-production double-differential cross sections were parameterized with the moving source model by the least-square method. The experimental results were compared with calculations of the PHITS and the TALYS codes.

Neutron-Emission Measurements at a White Neutron Source

R. C. Haight 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Data on the spectrum of neutrons emitted from neutron-induced reactions are important in basic nuclear physics and in applications. Our program studies neutron emission from inelastic scattering as well as fission neutron spectra. A ``white'' neutron source (continuous in energy) allows measurements over a wide range of incident neutron energies all in one experiment. We use the fast neutron source at the Los Alamos Neutron Science Center for incident neutron energies from 0.5 MeV to 200 MeV. These experiments are based on double time-of-flight techniques to determine the energies of the incident and emitted neutrons. For the fission neutron measurements, parallel-plate ionization or avalanche detectors identify fission in actinide samples and give the required fast timing pulse. For inelastic scattering, gamma-ray detectors provide the timing and energy spectroscopy. A large neutron-detector array detects the emitted neutrons. Time-of-flight techniques are used to measure the energies of both the incident and emitted neutrons. Design considerations for the array include neutron-gamma discrimination, neutron energy resolution, angular coverage, segmentation, detector efficiency calibration and data acquisition. We have made preliminary measurements of neutron emission spectra from neutron-induced fission of ^(235)U, ^(238)U, ^(237)Np and ^(239)Pu. Neutron emission spectra from inelastic scattering on iron and nickel have also been investigated. The results obtained will be compared with evaluated data.

13 MeV 양성자 사이클로트론 기반 열중성자 발생원 설계 및 특성

김정호,이승욱,이수현,김종열,문명국 한국물리학회 2016 새물리 Vol.66 No.2

We have designed and characterized a cyclotron-driven neutron source based on the 13 MeV proton beam for thermal-neutron imaging systems. Accelerator-based neutron sources mainly comprise \romannumeral 1) a target emitting neutrons via nuclear reactions with high energy protons, \romannumeral 2) moderators reducing the kinetic energy of the fast neutrons to allow neutron radiography and \romannumeral 3) reflectors optimizing the divergence of the neutron beam. In this study, a conceptual design consisting of a 1.25 mm-thick beryllium target, a 3 cm-thick HDPE (high-density polyethylene) moderator and a 50 cm-cube-shaped graphite reflector has been proposed. For realistic demonstrations, not only have we calculated the neutron fluences and distributions at up to L/D = 200, where L is the aperture-to-detector distance and D is the aperture diameter, which is an important factor in the field of radiography, but also we have confirmed that the neutron flux of up to $1.4\times10^{5}$ n/cm$^{2}\cdot$s can be obtained when the source-to-detector distance is 3 m. 13 MeV급 양성자 사이클로트론에 적용하여 열중성자 영상시스템에 최적인 중성자 발생원을 설계하고 그 특성을 분석하였다. 중성자 발생원은 1) 양성자를 이용하여 중성자를 생산하는 표적, 2) 표적에서 발생된 고속의 중성자를 영상획득에 알맞게 중성자의 에너지를 줄여주는 감속재, 3) 표적과 감속재를 거쳐 방출된 중성자를 반사시켜 중성자 빔을 인출하는 방향으로 모아주는 반사체 등으로 구성된다. 전산모사를 통하여 두께 1.25 mm 베릴륨, 감속재는 두께 3 cm 고밀도 폴리에틸렌으로 구성하고, 두께 50 cm 흑연 반사체를 사용하면 중성자 영상획득을 위한 최적 조건임을 보였다. 또한, 중성자 영상획득 시 중요한 변수인 L/D 값을 200 까지 변경시키면서 중성자 영상검출기 위치에서 얻을 수 있는 열중성자의 선속과 분포를 확인하였으며, 중성자 발생원과 검출기 사이의 거리가 3 m 인 경우 최대 $1.4\times10^{5}$ n/cm$^{2}\cdot$s 수준의 중성자 선속을 얻을 수 있음을 확인하였다.

GEANT4 몬테카를로 전산모사를 이용한 PET 사이클로트론 기반 중성자 선원의 BNCT 적용가능성 평가

최재원,강보선 한국물리학회 2017 New Physics: Sae Mulli Vol.67 No.11

본 연구는 붕소-중성자 포획치료용 (boron neutron capture therapy, BNCT) 중성자 선원으로 사이클로트론의 활용가능성 평가를 위한 선행 연구이다. GEANT4 전산모사 도구를 이용하여 사이클로트론에서 가속된 양성자 빔을 베릴륨 표적에 조사할 때 발생되는 중성자 수율을 계산하였다. 또한 양성자 빔의 에너지와 표적의 두께 변화에 따른 중성자 스펙트럼의 변화와 각도별 수율을 계산하였다. 계산된 결과를 종합하여 중성자 반사체가 포함된 표적의 주요 설계인자를 결정하였고, 설계된 표적에서 발생되는 고열중성자 선속을 계산하였다. 20 MeV 이하의 저에너지 양성자 빔을 조사할 때 발생되는 고열중성자 선속은 BNCT 중성자 선원으로 적합하지 않았으며, 30 MeV 500 $\mu$A 양성자 빔에 의해 발생되는 고열중성자 선속은 1.03$\times$10$^{9}$ n/cm$^{2}$$\cdot$s로서 BNCT 중성자 선원에 요구되는 권고선속 이상의 고열중성자 선속을 발생시킴을 확인하였다. This report presents the results of a feasibility study on a cyclotron-based neutron source for boron neutron-capture therapy (BNCT). Neutron yields from a beryllium target bombarded by a proton beam accelerated by a cyclotron were calculated using the GEANT4 simulation tool kit. The calculations were performed with different proton energies and different target thicknesses to find the changes in neutron spectra and yield at various angles. The main parameters for the design of a target with a neutron reflector were determined based on the calculated results, and epithermal neutron fluxes generated from the target were calculated. The epithermal neutron flux generated by a proton beam with an energy lower than 20 MeV was not sufficient for BNCT. However the flux generated by a 30 MeV, 500 $\mu$A proton beam was 1.03$\times$10$^{9}$ n/cm$^{2}$$\cdot$s, which satisfies the flux recommandation for a BNCT neutron source.

A novel ceramic GEM used for neutron detection

Zhou, Jianrong,Zhou, Xiaojuan,Zhou, Jianjin,Jiang, Xingfen,Yang, Jianqing,Zhu, Lin,Yang, Wenqin,Yang, Tao,Xu, Hong,Xia, Yuanguang,Yang, Gui-an,Xie, Yuguang,Huang, Chaoqiang,Hu, Bitao,Sun, Zhijia,Chen, Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.6

A novel ceramic Gas Electron Multiplier (GEM) has been developed to meet the demand of high counting rate for the neutron detection which is an alternative to ³He-based detector at China Spallation Neutron Source (CSNS). An experiment was performed to measure the neutron transmittance of ceramic-GEM and FR4-GEM at the small angle neutron scattering (SANS) instrument. The result showed the ceramic-GEM has higher transmittance and less self-scattering especially for cold neutrons. One single ceramic GEM could give a gain of 10²-10⁴ in the mixture gas of Ar and CO₂ (90%:10%) and its energy resolution was about 27.7% by using ⁵⁵Fe X ray of 5.9 keV. A prototype has been developed in order to investigate the performances of the ceramic GEM-based neutron detector. Several neutron beam tests, including detection efficiency, spatial resolution, two-dimensional imaging, and wavelength spectrum, were carried out at CSNS and China Mianyang Research Reactor (CMRR). The results show that the ceramic GEM-based neutron detector is a good candidate to measure the high intensity neutrons.

중성자 에너지 측정을 위한 NE213-PSD 장치의 감응 분석

이경주,Lee, Kyung-Ju 한국분석과학회 1992 분석과학 Vol.5 No.4

방사선 중성자 선원의 에너지 스펙트럼을 측정하기 위하여 액체 섬광 검출기(NE213)와 펄스모형 분리장치를 감마선 선원과 중성자 선원을 이용하여 그 감응 특성을 분석하였다. Am-Be 선원을 이용하여 이 장치에 대한 "Figure of Merit"을 측정한 결과 1.13 이었다. 이 값은 단색 에너지 중성자 선원인 $^{12}C(d,\;n)^{13}N$에서의 1.3 과 상당히 유사한 값을 보여 준다. NE213-PSD 장치의 성능 시험을 위한 이 실험결과는 중성자-감마 혼합 방사선장에서 스펙트럼의 측정과 중성자 에너지 스펙트럼과 속밀도 측정표준을 확립하는 데 기술적으로 유용하게 쓰일 것이다. In order to measure the energy spectrum of a radioactive neutron source, the pulse shape discrimination (PSD) system with organic scintillator, NE-213, was characterized by using some of the gamma ray sources and neutron source, Am-Be. The figure of merit of the rise time spectrum of AmBe source measured by this system was about 1.13. This value agrees well with the value of 1.3 which is measured for monoenergetic source, $^{12}C(d,\;n)^{13}N$. The results of present experiment for performance test of NE213-PSD system will provide the useful technique to measure the spectrum of neutron-gamma mixed field and to establish the neutron energy spectrum and flux density standards.

Effect of tokamak neutron source shape on radwaste transmutation

Elsevier 2019 Fusion engineering and design Vol.147 No.-

<P><B>Abstract</B></P> <P>The effects of tokamak neutron source shape on the radial build and transmutation characteristics of a transmutation reactor were investigated. The optimal dimension of the reactor components was determined by the requirements not only on plasma physics and tokamak engineering, but also on neutronic performance. Tokamak neutron source shapes with two aspect ratios and two blanket configurations were compared. With the plasma physics and tokamak engineering constraints moderately extrapolated from the International Thermonuclear Experimental Reactor (ITER) design, the transmutation reactor with a normal aspect ratio (NAR) tokamak neutron source showed better transmutation performance with a smaller system dimension and larger fusion power than a low aspect ratio (LAR) tokamak neutron source. It was also shown that, with separate TRU burning and tritium breeding blanket configuration, the transmutation ratio was larger with the smaller initial TRU inventory than with merged TRU burning and tritium breeding blanket configuration.</P>

Adaptive group of ink drop spread: a computer code to unfold neutron noise sources in reactor cores

Seyed Abolfazl Hosseini,Iman Esmaili Paeen Afrakoti 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.7

The present paper reports the development of a computational code based on the Adaptive Group of InkDrop Spread (AGIDS) for reconstruction of the neutron noise sources in reactor cores. AGIDS algorithmwas developed as a fuzzy inference system based on the active learning method. The main idea of theactive learning method is to break a multiple inputesingle output system into a single inputesingleoutput system. This leads to the ability to simulate a large system with high accuracy. In the presentstudy, vibrating absorber-type neutron noise source in an International Atomic Energy Agency-twodimensional reactor core is considered in neutron noise calculation. The neutron noise distribution inthe detectors was calculated using the Galerkin finite element method. Linear approximation of theshape function in each triangle element was used in the Galerkin finite element method. Both the realand imaginary parts of the calculated neutron distribution of the detectors were considered input data inthe developed computational code based on AGIDS. The output of the computational code is thestrength, frequency, and position (X and Y coordinates) of the neutron noise sources. The calculatedfraction of variance unexplained error for output parameters including strength, frequency, and X and Ycoordinates of the considered neutron noise sources were 0.002682 #/cm3s, 0.002682 Hz, and0.004254 cm and 0.006140 cm, respectively.

The Compact Pulsed Hadron Source: A Design Perspective

Jie Wei,Huaibi Chen,Cheng Cheng,Qiang Du,Zhe Feng,Xialin Guan,Xiaoxue Han,Tuchen Huang,Renkai Li,Chun K. Loong,Beibei Shao,Chuanxiang Tang,Qingzi Xing,Yigang Yang,Hao Zha,Huayi Zhang,Shuxin Zheng,Bin 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.61

During the past decades, large-scale national neutron sources have been developed in Asia, Europe,and North America. Complementing such efforts, compact hadron beam complexes and neutron sources intended to serve primarily universities and industrial institutes have been proposed,and some have recently been established. Responding to the demand in China for pulsed neutron/proton-beam platforms that are dedicated to fundamental and applied research for users in multiple disciplines from materials characterization to hadron therapy and radiography to accelerator-driven sub-critical reactor systems (ADS) for nuclear waste transmutation, we have initiated the construction of a compact, yet expandable, accelerator complex-the Compact Pulsed Hadron Source (CPHS). It consists of an accelerator front-end (a high-intensity ion source, a 3-MeV radio-frequency quadrupole linac (RFQ), and a 13-MeV drift-tube linac (DTL)), a neutron target station (a beryllium target with solid methane and room-temperature water moderators/reflector),and experimental stations for neutron imaging/radiography, small-angle scattering, and proton irradiation. In the future, the CPHS may also serve as an injector to a ring for proton therapy and radiography or as the front end to an ADS test facility. In this paper, we describe the design of the CPHS technical systems and its intended operation.