300#反应堆单晶硅中子嬗变掺杂计算

介绍了300#反应堆单晶硅中子嬗变掺杂辐照量计算的原理,给出了计算软件类结构及其主要类中的实现函数,描述了该程序在辐照计算,原始和出厂清单处理,以及各类原始数据处理方面的功能和特点,对相应的界面都给出了图示,并对软件的特性和应用前景作了分析。     

GaAs中子嬗变掺杂的初步研究

硅的中子嬗变掺杂(简称NTD)法已经得到了广泛应用,在制备大功率整流器、可控硅、硅靶摄像管、核探测器和集成电路等方面被公认是一种好方法。中子辐照硅的优点是掺杂十分均匀,浓度偏差可在±5％之内;掺杂精度高,能够准确地达到所要求的浓度。近年来,Ⅲ-V族化合物半导体的中子嬗变掺杂亦有报道。1971年Miriashvili等人首先报道了GaAs的中子嬗变掺杂。在这之后,一些作者进一步研究了热中子辐照GaAs的原理、特点和它的应用。1982年在美国马里兰举行的第四届国际NTD会议上也报道了这方面的内容。     

中子辐照直拉硅退火后的施主行为

利用多种实验手段对中子辐照直位硅退火过程中特有的施主效应进行了研究；探讨了不同中子辐照注量以及氧对施主形成的影响；报道了低于７５０℃热处理所产生的“施主平台”现象。实验结果表明，该施主在禁带中产生￣４３ＭｅＶ的浅施主能级，它的结构为辐照缺陷与硅、二氧化硅以及碳等组成的亚稳态络合物，其电话性起源于硅和二氧化硅沉淀的界面态。     

Design simplification of a small nuclear reactor for large-diameter neutron transmutation doping silicon using control rods

A design concept for a small nuclear reactor for neutron transmutation doping silicon (NTD-Si) using a Pressurized Water Reactor (PWR) full-length fuel assembly was proposed in our previous work. The excess reactivity was suppressed by a combination of Gd₂O₃ and soluble boron, which results in a flatter flux profile over the core than with control rod insertion; however, the soluble boron system for reactivity control is quite complex and expensive. The removal of this system would make the design much simpler. In the current work, the removal of soluble boron is considered. Criticality, neutron transportation and core burn-up calculations were performed using the MVP/GMVP II code and MVP-BURN code. The calculation results show that the insertion of control rods in five of the nine assemblies is enough to suppress reactivity. The thermal hydraulic analysis showed that heat removal from the core was possible under 1 atm operating pressure. Silicon ingots up to 30 cm in diameter could be irradiated with sufficient uniformity in the irradiation channels.     

Radiation damage in neutron transmutation doped-InP

InP crystals irradiated at different thermal neutron fluences have been investigated by optical absorption and positron lifetime measurements. Irradiation produces a shift of the absorption edge towards long wavelengths and the appearance of an absorption band centered at 1.24 eV. The absorption edge is fully recovered after annealing but the absorption band remains. Positron lifetime spectra are analysed with two components. The longer lifetime, τ₂ = 300 ps, has an intensity that increases with the fluence and falls down after annealing. This component has been associated to positrons trapped at In-monovacancy related defects. The absorption tail has been proposed to be due to optical transitions involving vacancies that act as acceptors while the 1.24 eV band has been tentatively ascribed to anion antisites.     

Temperatures in nuclear silicon doping

Translated from Atomnaya Énergiya, Vol. 68, No. 1, pp. 46–47, January, 1990.     

High-efficiency neutron generation in a deuteron accumulator for radionuclide transmutation

Institute of High-Energy Physics and Institute Automation and Electrometry. Translated from Atomnaya Énergiya, Vol. 73, No. 4, pp. 289–293, September, 1992.     

Parametric analysis of the neutron transmutation doping (NTD) facility at the Egyptian Second Research Reactor (ETRR-2)

One of the most important facilities of the Egyptian Second Research Reactor (ETRR-2) is the silicon Neutron Transmutation Doping (NTD) Facility. This work is done to optimize the performance of the ETRR-2 NTD facility based on the standards and to develop a calculation line that can be used during its commercial operating phase. Calculation line methodology was developed using WIMS-D4 and CITVAP codes as well as nuclear data file libraries to perform core calculations needed to predict neutronic parameters at the two NTD locations. Axial flux profile was calculated and results were in good agreement with the experimental flux mapping. Based on the calculated variation of the thermal neutron flux axial distribution, it was proposed to displace the silicon ingot axially from its initially proposed position to minimize flux variation. Impact of control rod configuration was analyzed to maximize the neutron flux at the NTD two locations and the best control rod configuration is recommended. Thermal to fast neutron flux was also calculated and concluded that radiation damage caused by fast neutrons can safely be neglected. Flux depression across the ingot was estimated using the ANISN code. Finally, the SIMULINK module of the MATLAB code was used to evaluate the ingot activity due to different radioactive nuclides. The activity was found to reach its exempted limit after 2.79 days after its discharge from the irradiation channel. It was also concluded that the worse ETRR-2 scram will not affect the obtained Si doping and its resistivity.     

Effect of the neutron spectrum on the characteristics of Np, Am, and Cm transmutation chains

It is shown by analysis of the influence of the neutron spectrum on the neutron balance of the transmutation chains of ²³⁷Np and ²⁴¹Am that in a fast-reactor spectrum these chains are short and more neutrons are created (excess 0.8–1 neutron per starting nucleus) than absorbed in them. In a thermal-reactor spectrum, these chains are longer and more neutrons are absorbed (deficit 0.7–0.83 per starting nucleus) than created in them. Additional nuclear fuel, for example, ²³⁵U and ²³⁹Pu, must be burned to cover the neutron deficit. __________ Translated from Atomnaya énergiya, Vol. 100, No. 6, pp. 452–458, June, 2006.     

A study of transmutation of minor-actinide in a thermal neutron field of the advanced neutron source

Since Minor Actinides (MAs) have a large cross section in a thermal energy region, a thermal neutron field has possibility to provide high relative transmutation rate. The transmutation of MA in a thermal neutron field was investigated in this study, focusing on relative transmutation rate, transmutation rate of weight and neutron economy in a thermal neutron field in comparison with those in a fast neutron field. The followings are the major results: (1) a thermal neutron field, especially a well-thermalized neutron field, provides high relative transmutation rate of MA. (2) However, the transmutation rate of weight of MA is limited since the region with high flux is restricted even in the ANS. (3) The accumulation of ²⁴⁶Cm slows the relative transmutation rate of MA in a thermal neutron field. However, it can be compensated by providing a neutron field with high flux in keV region. (4) The neutron economy of the transmutation of MA is not so bad in a thermal neutron field, and is rather good when the neutron flux is high.     

Modelling effects on axial neutron flux in a Tokamak device

Using Monte Carlo N-Particle (MCNP5), three different Tokamak models using different geometries were simulated, maintaining some basic parameters from the ITER design. The neutron flux and the reaction rates were obtained over different volumes: FW, divertor and along the different device walls. The three geometries were compared under the same conditions. The results showed the behaviour of the neutron flux spectra along the different walls, as well as, the most suitable model taking in consideration the different analyses and the final purpose of adding a transmutation layer. Finally, the chosen geometry will be used to analyse the burnup, buildup, decay, and processing of material under irradiation.     

Effect of radial hydrides on the axial and hoop mechanical properties of Zircaloy-4 cladding

The effect of radial hydrides on the mechanical properties of stress-relief annealed Zircaloy-4 cladding was studied. Specimens were firstly hydrided to different target hydrogen levels between 100 and 600 wt ppm and then thermally cycled in an autoclave under a constant hoop stress to form radial hydrides by a hydride reorientation process. The effect of radial hydrides on the axial properties of the cladding was insignificant. On the other hand, the cladding ductility measurements decreased as its radial hydride content increased when the specimen was tested in plane strain tension. A reference hydrogen concentration for radial hydrides in the cladding was defined for assessing the fuel cladding integrity based on a criterion of the tensile strength 600 MPa. The reference hydrogen concentration increased with the specimen (bulk) hydrogen concentration to a maximum of ∼90 wt ppm at the bulk concentration ∼300 wt ppm H and then decreased towards higher concentrations.     

Tomsk complex for neutron-transmutation doping of silicon

All-Union Scientific-Research Institute of Nuclear Physics at the S. M. Kirov Tomsk Polytechnical University. Translated from Atomnaya énergiya, Vol. 79, No. 1, pp. 38–40, July, 1995.     

Reactivity cost for different top reflector materials in miniature neutron source reactors

The cost of reactivity of the top reflector in MNSRs was investigated based on the market prices. A 3-D model for the reactor components was used. Three reflectors were compared, namely: graphite, beryllium and heavy water. The average cost of reactivity revealed to be minimum for graphite (maximum value of 3.92 US$/mk), while the second cheapest reflector resulted to be beryllium up to the price of 650 US$/kg. Heavy water can compete with beryllium only for higher prices of beryllium. The best reflector for MNSRs results to be graphite from the economy and safety points of view.     

Np,Am, Cm transmutation efficiency parameters taking account of neutron reaction rates

Np, Am, and Cm transmutation efficiency parameters, taking account of the neutron reaction rates on all transuranium isotopes in all transformation chains initiated by introducing Np, Am, and Cm, are proposed for specialized transmutation facilities. These parameters can be helpful when comparing the efficiencies of different types of transmutation facilities and analyzing possible ways to increase the Np, Am, and Cm transmutation efficiency. The efficacy of including the parameters in the definition of transmutation efficiency is shown for a specialized transmutation facility. The possibility of evaluating the efficiency of Np, Am, and Cm transmutation in fast power reactors is examined taking account of the proposed parameters.