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Comparison of neutron energy spectrum unfolding methods and evaluation of rationality criteria

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Nuclear Science and Techniques 2022年第12期33卷 159-172页

作者： Jun‑Kai Yang Ping‑Quan Wang Zhong‑Guo Ren Ren‑Sheng Wang Hui Zhang Jian Zhang National Institute of Metrology Beijing 100029China Institute of Applied Electronics China Academy of Engineering PhysicsMianyang 621900China School of Radiation Medicine and Protection Medical College of Soochow UniversitySuzhou 215123China Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions Suzhou 215123China

The neutron energy spectrum was measured using a Bonner sphere spectrometer at six locations inside the containment vessel of a nuclear reactor at the Qinshan nuclear power plant. The structures of the neutron spectra obtained by the maximum entropy, iteration, and genetic algorithm methods were consistent with one another and could be interpreted as the spectral superposition of different energy regions. The characteristic parameters of the neutron spectrum, including the fluence rate,average energy, and neutron ambient dose equivalent rate H^(*)(10), were in good agreement among the three methods. In addition, an LB6411 neutron ambient dose equivalent meter was employed to obtain the H^(*)(10) directly for *** findings indicate that neutron spectrum unfolding methods can be used to overcome the problems associated with the response functions of dosimeters to provide more accurate H^(*)(10) values. In this study, the following three evaluation criteria were systematically addressed to ensure the accuracy of the unfolded spectra: count rates of the inverse solutions,neutron spectrum structures, and comparison of key parameters.

关键词： neutron spectrum ̇H∗(10) Nuclear power plant Evaluation criteria

Measurement of the Energy spectrum of the neutrons inside the neutron Flux Trap Assembled in the Center of the Reactor Core IPEN/MB-01

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Journal of Energy and Power Engineering 2014年第11期8卷 1817-1823页

作者： Ulysses d'Utra Bitelli Luiz Ernesto Credidio Mura Diogo Feliciano dos Santos Rogério Jerez Instituto de Pesquisas Energéticas e Nucleares Comissao Nacional de Energia Nuclear Sao Paulo 05508-000 Brasil

This paper presents the neutron energy spectrum in the central position of a neutron flux trap assembled in the core center of the research nuclear reactor IPEN/MB-01, obtained by an unfolding method. To this end, we have used several different types of activation foils （Au, Sc, Ti, Ni, and plates） which have been irradiated in the central position of the reactor core （setting number 203） at a reactor power level （64.57±2.91 watts）. The activation foils were counted by solid-state detector HPGe （high pure germanium detector）（gamma spectrometry）. The experimental data of nuclear reaction rates （saturated activity per target nucleus） and a neutron spectrum estimated by a reactor physics computer code are the main input data to get the most suitable neutron spectrum in the irradiation position obtained through SANDBP （spectrum analysis neutron detection code-version Budapest University） code： a neutron spectra unfolding code that uses an iterative adjustment method. the integral neutron flux, （2.41 ± 0.01） × 10^9 n·cm^-2·s^-1 for the thermal The adjustment resulted in （3.85 ± 0.14） × 10^9 n·cm^-2·s^-1 for neutron flux, （1.09 ±0.02） × 10^9n·cm^-2·s^-1 for intermediate neutron flux and （3.41 ± 0.02） × 10^8 n·cm^-2·s^-1 for the fast neutrons flux. These results can be used to verify and validate the nuclear reactor codes and its associated nuclear data libraries, besides, show how much effective it can be that the use of a neutron flux trap in the nuclear reactor core to increase the thermal neutron flux without increase the operation reactor power level. The thermal neutral flux increased 4.04 ± 0.21 times compared with the standard configuration of the reactor core.

关键词： Thermal neutron flux flux trap activation detectors neutron spectrum zero power reactor.

neutronic analysis of deuteron-driven spallation target

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Nuclear Science and Techniques 2021年第9期32卷 52-60页

作者： Wei-Wei Qiu Wu Sun Jun Su Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

Deuteron-driven spallation targets have garnered attention recently because they can provide high-energy neutrons to transmute long-lifetime fission *** this study,the Geant4 toolkit was used to simulate the inter-action between a deuteron beam at 500 MeV and a com-posite target composed of alternating lead-bismuth eutectic(LBE)and *** water was used because it may be employed as a target *** energy spectrum,neu-tron yield,average energy,and total energy of the emitted neutrons were calculated for different thicknesses and thickness ratios between the LBE and *** a constant target thickness,the neutron yield increases with an increasing thickness ratio of LBE to H 2 O,while the aver-age energy of the emitted neutrons decreases with an increasing in the aforementioned thickness *** two aspects support the use of a pure target,either LBE or ***,with an increasing LBE-to-H 2 O thickness ratio,the total energy of the emitted neutrons increases and then *** result supports the addition of water into the LBE *** angular distributions of the emitted neutrons show that the rear of the target is suit-able for loading nuclear waste containing minor actinides and long-lifetime fission products.

关键词： Long-lived nuclear waste product Accelerator-driven sub-critical system Deuteron-induced spallation target neutron spectrum

Real-Time Bonner Sphere Spectrometry on the HL-2A Tokamak

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Plasma Science and Technology 2016年第6期18卷 699-702页

作者：蒋春雨曹靖蒋小菲赵艳凤宋先瑛阴泽杰 State Key Laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China Department of Modern Physics University of Science and Technology of ChinaHefei 230026China Southwestern Institute of Physics Chengdu 610041China

Real-time Bonner sphere spectrometry（BSS）at the HL-2A tokamak for the neutron spectrum diagnostic is *** spectrometer consists of eight different size Bonner spheres made of polyethylene and with a ^3helium-filled detector in the center,pre-amplifiers,and parallelprocessing data acquisition system（DAQ）.Dynamic neutrons from plasma discharges of the HL-2A tokamak were measured and the real-time neutron spectrum was presented.

关键词： Bonner sphere spectrometry real-time neutron spectrum tokamak

Study of neutron spectra in a water bath from a Pb target irradiated by 250 MeV protons

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Chinese Physics C 2015年第4期39卷 31-36页

作者：李严严张雪荧鞠永琴马飞张宏斌陈亮葛红林万波骆鹏周斌张艳斌李建阳徐俊奎王松林杨永伟杨磊 Institute of Modern Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Institute of High Energy Physics Chinese Academy of Sciences

Spallation neutrons were produced by the irradiation of Pb with 250 MeV protons. The Pb target was surrounded by water which was used to slow down the emitted neutrons. The moderated neutrons in the water bath were measured by using the resonance detectors of Au, Mn and In with a cadmium （Cd） cover. According to the measured activities of the foils, the neutron flux at different resonance energies were deduced and the epithermal neutron spectra were proposed. Corresponding results calculated with the Monte Carlo code MCNPX were compared with the experimental data to check the validity of the code. The comparison showed that the simulation could give a good prediction for the neutron spectra above 50 eV, while the finite thickness of the foils greatly effected the experimental data in low energy. It was also found that the resonance detectors themselves had great impact on the simulated energy spectra.

关键词： spallation reaction bath activation method neutron spectrum MCNPX simulation

Simulation of the response functions of an extended range neutron multisphere spectrometer using FLUKA

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Chinese Physics C 2015年第7期39卷 37-41页

作者：王攀峰丁亚东王庆斌马忠剑郭思明李冠稼 Institute of High Energy Physics Chinese Academy of Sciences

In this paper, the distribution of radiation field in the CSNS spectrometer hall at Dongguan, China, was simulated by the FLUKA program. The results show that the radiation field of the high energy proton accelerator is dominated by neutron radiation, with a broad range of neutron energies, spanning about eleven orders of *** and calculation of the response functions of four Bonner spheres with a simplified model is done with FLUKA and MCNPX codes respectively, proving the feasibility of the FLUKA program for this application and the correctness of the calculation method. Using the actual model, we simulate and calculate the energy response functions of Bonner sphere detectors with polyethylene layers of different diameters, including detectors with lead layers, using the FLUKA code. Based on the simulation results, we select eleven detectors as the basic structure for an Extended Range neutron Multisphere Spectrometer（ERNMS）.

关键词： neutron multisphere spectrometer neutron spectrum energy response FLUKA 3He-filled spherical proportional counter

MEASUREMENT OF neutron SPECTRA FROM THICK Be TARGET BOMBARDED WITH DEUTERONS

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Nuclear Science and Techniques 1994年第4期5卷 193-201页

作者：王效忠白希祥李安利柳卫平戚大海袁媛司国建

neutron spectra of Be(d,n) reaction were measured for deuteron energies from 13.5 to 22 MeV by using a stilbene scintillator detector and flight time technique.A special calibration method of neutron detector efficiency for higher energy portion was adopted. The spectral neutron yield per unit beam charge on the Be target at 0° was determined. The fluence-averaged mean neutron energies of the neutron spectra are given as a function of the incident energy for several thresholds. The measured neutron spectra have an almost same shape at different incident deuteron energies. High energy portion (En>1.8MeV) and low energy portion (Enneutron spectra were separately measured and they were concerned with each other by normalization. The energy range of whole neutron spectra is 0.7 MeV to 30MeV.

关键词： neutron spectrum Be target Deuterons

Americium Transmutation in the SVBR-100 Reactor

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World Journal of Nuclear Science and Technology 2020年第3期10卷 116-128页

作者： A. V. Gulevich V. A. Eliseev O. G. Komlev I. V. Tormyshev G. I. Toshinsky JSC “SSC RF-IPPE” Obninsk Russia JSC “AKME-Engineering” Moscow Russia

One of the postponed problems of nuclear power (NP) is the problem of the management of long-lived radioactive waste (RAW), and, first of all, with minor actinides (MA), of which americium-241 is the most difficult. The aim of this work is to study the efficiency of americium transmutation in a fast reactor with a heavy liquid metal coolant lead-bismuth eutectic alloy. The article presents the results of calculations of the transmutation of americium in the SVBR-100 reactor using standard uranium oxide fuel with the addition of americium-241. The obtained values of the rate of transmutation of americium are compared with similar values for the SVBR-100 reactors on MOX-fuel and in the BN-800 reactor.

关键词： SVBR-100 Fast Reactor Nuclear Power Lead-Bismuth Eutectic Minor Actinides Americium Nuclear Fuel Cycle neutron spectrum Core