Simulation and experimental study of a random neutron analyzing system with （252）~Cf neutron source

Experiments were performed on a high-speed online random neutron analyzing system(HORNA system)with a 252Cf neutron source(up to 1 GHz sampling rate and 3 input data channel),to obtain time-and frequencydependent signatures which are sensitive to changes in the composition,fissile mass and configuration of the fissile assembly.The data were acquired by three high-speed synchronized acquisition cards at different detector angles,source-detector distances and block sizes.According to the relationship between 252Cf source and the ratio of power spectral density,Rpsd,all the signatures were calculated and analyzed using correlation and periodogram methods.Based on the results,the simulated autocorrelation functions were utilized for identifying different fissile mass with Elman neural network.The experimental results show that the Rpsd almost remains at constant amplitude in frequency range of 0-100 MHz,and is only related to the angle and source-detector distance.The trained Elman neural network is able to distinguish the characteristics of autocorrelation function and identify different fissile mass.The average identification rate reached 90% with high robustness.     

Simulation and optimization for a 30-MeV electron accelerator driven neutron source

A neutron source driven by electron accelerator is proposed in Shanghai Institute of Applied Physics (SINAP). The facility is planned for the study of nuclear data in Thorium-Uranium cycling system, and for material research. A detailed simulation of the neutron source is performed for the program to get the neutron generation maximum economically. Several parameters of the facility, which affect the neutron yield and the neutron escape from outer surface of the target, are analyzed respectively. Besides, the yielding neutron spectrum and the escaping neutron angular distribution are calculated and discussed.     

Effects of neutron spectrum and external neutron source on neutron multiplication parameters in accelerator-driven system

The neutron multiplication parameters: neutron multiplication M, subcritical multiplication factor k_s, external source efficiency φ^*, play an important role for numerical assessment and reactor power evaluation of an accelerator-driven system (ADS). Those parameters can be evaluated by using the measured reaction rate distribution in the subcritical system. In this study, the experimental verification of this methodology is performed in various ADS cores; with high-energy (100 MeV) proton–tungsten source in hard and soft neutron spectra cores and 14 MeV D–T neutron source in soft spectrum core. The comparison between measured and calculated multiplication parameters reveals a maximum relative difference in the range of 6.6–13.7% that is attributed to the calculation nuclear libraries uncertainty and accuracy for energies higher than 20 MeV and also dependent on the reaction rate distribution position and count rates. The effects of different core neutron spectra and external neutron sources on the neutron multiplication parameters are discussed.     

241Am-Be源在煤中所形成中子场的参数拟合

研究了7种煤中主要元素对241Am-Be中子源在煤中形成中子场的影响,给出了描述中子场中快中子和热中子数量变化曲线的经验公式和拟合参数。     

Computational characteristics of a neutron source based on the CERN colliding-beams accelerator

The computational characteristics of a pulsed source of thermal neutrons, which can be implented on the basis of the collidng-beams accelerator under construction at CERN, are presented. The calculations were performed at the All-Russia Reserach Institute of Experimental Physics (Sarov) using two Monte Carlo programs: the GEANT-3 program developed at CERN and our own program S-95. The neutron source is assumed to be a cylindrical tungsten target with an internal neutron moderator made of zirconium hydride bombarded by protons from a colliding-beam accelerator. The maximum power of the source is estimated on the basis of the results of calculations of the dynamical stresses in tungsten. To decrease the negative impact of mechanical stresses, recommendations are formulated dividing the target efficiently into individual elements. __________ Translated from Atomnaya énergiya, Vol. 100, No. 2, pp. 117–125, February, 2006.     

Feasibility of a multi-purpose demonstration neutron source based on a compact superconducting spherical tokamak

Tokamak neutron sources would allow near term applications of fusion such as fusion–fission hybrid reactors, elimination of nuclear wastes, production of radio-isotopes for nuclear medicine, material testing and tritium production. The generation of neutrons with fusion plasmas does not require energetic efficiency; thus, nowadays tokamak technologies would be sufficient for such purposes. This paper presents some key technical details of a compact (～1.8 m³ of plasma) superconducting spherical tokamak neutron source (STNS), which aims to demonstrate the capabilities of such a device for the different possible applications already mentioned. The T-11 transport model was implemented in ASTRA for 1.5 D simulations of heat and particle transport in the STNS core plasma. According to the model predictions, total neutron production rates of the order of ～10¹⁵ s^?1 and ～10¹³ s^?1 can be achieved with deuterium/tritium and deuterium/deuterium respectively, with 9 MW of heating power, 1.4 T of toroidal magnetic field and 1.5 MA of plasma current. Engineering estimates indicate that such scenario could be maintained during ～20 s and repeated every ～5 min. The viability of most of tokamak neutron source applications could be demonstrated with a few of these cycles and around ～100 cycles would be required in the worst cases.     

中子源识别芥子气毒剂弹的蒙特卡罗模拟

日本战败后遗弃的化学武器不断造成伤人事件的发生。在这些事件中，因接触者无识别能力而造成重大损失，其中又以芥子气毒剂伤人事件最多和最为严重。芥子气毒剂弹由于埋藏时间较长，锈蚀、泄露比较严重，已经无法从外观上与普通炮弹进行识别，传统的化学试剂识别方法对人员容易造成伤害。研究了非接触性的外中子源诱发γ谱识别方法，模拟计算了外中子源对芥子气毒剂弹照射后的γ谱。根据γ谱上Cl、S和Fe等关键核素的特征射线，便可完成对毒剂弹的识别。     

Conditions for effective utilization of the electronuclear blanket system as a neutron source

The efficiency of an intermediate-energy electronuclear setup with a blanket as an alternative source of neutrons is discussed on the basis of experience in designing the electronuclear neutron generator at the Institute of Theoretical and Experimental Physics. A classification of electronuclear setups is introduced. The factors determining the efficiency of the driver-target-multiplying blanket scheme at low and intermediate driver energies are examined. To obtain high neutron fluxes, the possibility of compensating an inadequate driver current by decreasing the subcriticality store is examined and the conditions for realizing such a possibility while preserving the fundamental requirement of nuclear safety are formulated. The concept of the criterion of dynamical safety, in contrast to the criterion of static safety ordinarily assumed for subcritical systems, is introduced. A program of precision investigations for studying operating regimes of a blanket under conditions of a low store of subcriticality is formulated on the basis of the criterion of dynamical safety. The results of an implementation of this program are important for the assessment of the technological possibility and desirability of replacing research reactors with subcritical setups based on an accelerator. 2 figures, 6 references. State Science Center of the Russian Federation-Institute of Theoretical and Experimental Physics. Translated from Atomnaya énergiya, Vol. 87, No. 4, pp. 255–262, October, 1999.     

Selective energy neutron source based on the D-Li stripping reaction

A proposal is made on a version of the deuterium-lithium stripping (the FMIT)-type neutron source enhanced with its potential suitability for resolving complex neutron energy dependence in irradiation effects on materials. Some attractive features of such an accelerator-based source are skimmed out which cover the limitations fatal in the conventional means. The flexibility of controlling the quality and quantity of neutrons and the closer accessibility toin-situ- type experimentation are stressed as essential for the advanced studies on either interpretation of complex phenomena or innovating new materials compatible with specific neutron environments. A suggested conceptional design specification includes the selectivity of energy from 5, 10, and 14 MeV, and the maximum fluence of about 0.5–1×10²² n/cm²/year which can create damage of a typical candidate fusion reactor material by around 10 dpa. The concept is stressed to be reasonable and a realistic optionregarding the maturity of underlying technology, financial feasibility, and timing.     

Intensive 14 MeV neutron source based on deuteron storage ring

The key element of a Self-Consistent Nuclear Energy System is excess neutron generation. External neutron source is supposed to be included in the nuclear energy structure to improve its neutron balance. The paper presents accelerator based 14 MeV neutron source that might contribute to neutron excess generation required for transmuting of those fission products which are difficult to transmute in ordinary fission reactors.     

Bonner球谱仪对Pu-Be源中子能谱的测量

Bonner球谱仪是开展中子能谱测量的重要仪器,本文利用自行研制的Bonner球谱仪对已知源强的Pu-Be中子源进行能谱测量,以验证谱仪测量方法和中子能谱解谱方法的准确性。首先制作出由8个球组成的Bonner球谱仪,再根据谱仪的测量读数,采用最大熵法获得中子能谱信息,与国际原子能机构公布的数据基本符合,进一步计算得到所测Pu-Be中子源的中子周围剂量当量转换系数为0.37nSv.cm2,与目前已经公布的数值0.36nSv.cm2基本一致,表明求解出的能谱测量数据基本符合物理事实,测量所使用的Bonner谱仪和解谱方法的准确可靠性。