微结构半导体中子探测器研究进展

微结构半导体中子探测器(MSND)除了具有体积小、时间响应快、工作偏压低以及易于与读出电子学系统集成等优点外,还解决了二维平面半导体中子探测器存在的探测效率极低的问题(5%),其在军用和民用领域都具有良好的发展前景。介绍了微结构半导体中子探测器的中子探测原理,简述了其发展概况,综述了近年来的研究进展,展望了微结构半导体中子探测器的研究方向和应用前景。     

CR-39对各向同性中子的能量响应研究

建立了由聚乙烯、铅和CR-39组成的叠层探测器探测各向同性中子能谱模型,计算了叠层探测器对各向同性中子的能量响应以及叠层探测器的能量分辨率。计算结果表明,叠层探测器的响应和能量分辨率与中子能量、聚乙烯以及铅衰减层厚度有关。聚乙烯厚度不变,响应峰值和能量分辨率随铅的厚度增加而变小：铅的厚度不变,响应峰值和能量分辨率随聚乙烯厚度增加而变大,且响应函数形状改变。     

气泡中子探测器用于个人剂量监测

气泡中子探测器是可重复使用、积分型、无源剂量计。它的体积小,可对中子辐射进行直接、可视的测量。为了将气泡中子探测器用在个人剂量监测中,先验证气泡中子探测器对从0．2～15MeV能量的中子具有平直的能量响应。然后用5．10和1．3MeV的中子考察了气泡中子探测器的线性及其稳定性。     

keV能区中子注量率测量初级标准装置研制

由于大多数中子探测器在keV能区处于共振能区,截面数据无法精确已知,无法作为中子注量率测量初级标准装置。⁶Li在keV能区的截面精确已知,本文以此设计了一种包含⁶LiF转换体的硅半导体探测器系统（LiF-SSD探测器）,建立了keV能区中子参考辐射场中子注量率测量初级标准装置。利用SRIM和TRIM程序估算了LiF-SSD探测器的计数率;基于Geant4开发了探测器响应计算程序,给出了中子能量为27.4 keV的探测器脉冲幅度计算谱;利用⁴⁵Sc(p,n)-⁴⁵Ti反应,测量了27.4 keV中子能量点的探测器脉冲幅度谱,测量结果与理论计算谱符合较好。     

SiC中子探测器的研究进展

相比于气体、闪烁体及常规半导体中子探测器,基于第三代半导体材料SiC的中子探测器具有体积小、响应快、位置分辨率好、抗高温和耐辐照等众多优点。其中抗高温和耐辐照是应用于核反应堆堆芯、高能物理试验和太空等高温高压以及强辐射环境下的中子探测器需要突破的瓶颈。论文总结和分析了SiC的材料特性,SiC中子探测器的结构、工作原理、国内外发展现状以及存在的问题,并对我国中子探测器的发展趋势进行了探讨。     

金-硅面垒型探测器的制备

一、引言金-硅面垒型探测器具有下列的特点:能量分辨率高;脉冲上升时间短;耗尽层宽度可调节,因而能甄别不同的射线;脉冲高度与能量之间的线性响应好;对γ射线、中子本底不灵敏,适于在γ射线、中子本底较高的情况下测量带电粒子;工艺简单,成本较低等等。因此,自1949年麦凯(K.G.McKay)首先利用半导体探测器探测射线以来,它在核辐射探测领域中得到了很大的发展。关于金-硅面垒型探测器的制作工艺、探测原理、性能和应用已有报导。     

载6Li塑料闪烁探测器中子能量响应的实验研究

为提高塑料闪烁探测器对低能中子的探测灵敏度,根据中子灵敏度补偿原理研制了载^6Li塑料闪烁探测器。利用串列加速器中子源对几种新研制的载^6Li塑料闪烁探测器中子能量响应进行了实验标定,获得了几种掺不同^6Li浓度的塑料闪烁探测器的中子能量响应曲线。实验结果表明,载^6Li塑料闪烁探测器对低能中子确有较高的探测灵敏度。     

BC501探测器对~(252)Cf裂变瞬发射线的响应测量

为了应用BC501液体闪烁探测器测量脉冲信号时间序列,利用252Cf裂变γ射线和中子飞行时间谱,测量了两种大小BC501探测器对裂变瞬发射线的响应。探测器对入射γ射线的定时精度能够达到1.2 ns。获得了平均一次252Cf裂变,不同中子能量阈值以上,γ射线和中子的绝对计数。     

Response Measurement of Three Scintillation Detector to Instantaneous Rays from 252 Cf Fission

应用飞行时间谱,测量了LaCl3(Ce)、BC400、ST401三种闪烁探测器对252Cf裂变γ射线和中子的响应,获得了信号输出波形参数、定时精度、不同中子能量阈值的计数.测量了LaCl3,(Ce)探测器被高密度聚乙烯屏蔽后的响应.BC400探测器对入射γ射线的定时精度为1.3ns,ST401为1.5 ns.通过匹配快响应光电倍增管,LaCl3 (Ce)探测器是混合场中测量γ射线时间序列的一种有效方法.     

DPF装置脉冲中子测量技术研究

研制了用于DPF装置脉冲中子产额和波形监测的脉冲中子飞行时间-闪烁探测系统。在中国原子能科学研究院高压倍加器上采用电流法和脉冲中子飞行时间方法标定了该系统的D-T和D-D中子灵敏度。根据测量的光响应函数,采用Monte-Carlo方法模拟了塑料闪烁探测器的中子能量响应,由此对中子灵敏度标定结果进行了能量响应修正。利用研制的闪烁探测系统对ING-103型DPF装置的D-T脉冲中子产额和时间波形进行了实验测量,并对测量结果进行了分析和讨论。测量的DPF装置D-T脉冲中子产额在1×109–2×109n/shot之间,中子时间波形的半高宽约为9ns。     

Microstructural disorder and the mechanical properties of carbon fibres

The effect of fast neutron irradiation on the mechanical and microstructural properties of carbon fibres heat-treated to various stages of graphitization has been investigated. Changes in selected crystallinity parameters were used to monitor the microstructural disorder induced in each fibre type by three different irradiation doses. Associated changes in fracture strength and Young's modulus are related to the dependence of dislocation mobility on short-range microstructural damage.     

Irradiation creep under 60 MEV alpha irradiation

Accelerator-produced charged-particle beams have advantages over neutron irradiation for studying radiation effects in materials, the primary advantage being the ability to control precisely the experimental conditions and improve the accuracy in measuring effects of the irradiation. An apparatus has recently been built at ORNL to exploit this advantage in studying irradiation creep. These experiments employ a beam of 60 MeV alpha particles from the Oak Ridge Isochronous Cyclotron (ORIC). The experimental approach and capabilities of the apparatus are described. The damage cross section, including events associated with inelastic scattering and nuclear reactions, is estimated. The amount of helium that is introduced during the experiments through inelastic processes and through backscattering is reported. Based on the damage rate, the damage processes and the helium-to-dpa ratio, the degree to which fast reactor and fusion reactor conditions may be simulated is discussed. Recent experimental results on the irradiation creep of type 316 stainless steel are presented, and are compared to light ion results obtained elsewhere. These results include the stress and temperature dependence of the formation rate under irradiation. The results are discussed in relation to various irradiation creep mechanisms and to damage microstructure as it evolves during these experiments.     

Effect of Cascade as Fundamental Research on Radiation Damage of Core Component Materials

Effect of neutron irradiation on materials to a high fluence is important for advanced energy systems as fast breeder or fusion reactors. Two major features of fast neutron irradiation effects are high energy cascade effect and the effect of nuclear transmutations. In this paper, recent progress on the cascade damage is reviewed. The discussions include structure of the cascade, depending on the mass and energy of incoming particles or PKAs, formation and stability of the cascade defects, effects of the cascade on free defect and clustered defect formation and on the defect survival, characteristic phenomena of the cascades. Future directions to establish irradiation correlation are discussed. Emphasis is placed on the importance of establishing damage analysis methodology based on PKA energy spectrum.     

影响反应堆压力容器安全运行的根本原因及应对措施

从实现核反应堆安全目标和运行工况的角度,分析了反应堆压力容器在承受压力、温度和快中子辐照条件下的失效形式及根本原因。针对能量≥1MeV快中子辐照损伤,给出了预测和监督方法;对承压热冲击下可能引发脆性断裂进行了分析,并提出了分析方法。分析和介绍了各运行工况下RPV安全运行的压力一温度限值计算方法。     

The definition of damage functions from irradiation test data

This report describes a method of determining irradiation effectiveness of different neutron spectra in causing radiation effects to fuel cladding and reactor structural materials. It involves the definition of a semi-empirical damage function or cross section using measured data from specimens irradiated in thermal and fast test reactor spectra. The damage function is applied to design problems involving irradiation effects to reactor structural and fuel cladding materials to predict the fluence which would produce a specific change in material properties.     

A UKAEA evaluation of displacement damage models for iron

Various damage models used within the UKAEA have been evaluated and compared in the context of fast reactor and accelerator irradiations for iron. The limitations of the Kinchin-Pease model are discussed in the light of our present understanding of the partition between elastic and inelastic energy loss within collision cascades. The individual collisions within the cascade are treated as a series of binary collisions and matched to dynamic collision models at low energy. It is recommended that the damage model based on the calculations of Norgett, Robinson and Torrens be used for the calculation of the number of atomic displacements produced during neutron or ion irradiation.     

快中子照射唐菖蒲球茎的损伤作用初探

用快中子脉冲堆(China fast burst reactor Ⅱ,CFBR-Ⅱ)对唐菖蒲"超级"球茎进行不同剂量的照射处理,研究快中子对唐菖蒲球茎表面的刻蚀情况及对蛋白质表达的阻遏作用.扫描电镜观察发现球茎受损伤情况随照射剂量和照射角度的不同而变化,受垂直方向照射的球茎表面刻蚀程度最严重,且刻蚀程度随着剂量增大而增大.通过田间栽培试验和SDS-聚丙烯酰胺凝胶电泳(SDS-polyacrylamide gel electrophoresis,SDS-PAGE)分析发现,随照射剂量的增大,植株生长发育受到明显的抑制,蛋白表达数量显著减少.由此表明,快中子照射对植株能产生明显的影响.     

核数据处理软件NECP-Atlas中的光子相关数据计算方法研究

NECP-Atlas是西安交通大学自主研制的核数据处理软件,具有丰富的功能,可将评价核数据制作为后续核设计所需的应用核数据库,本文在NECP Atlas中建立了光子相关数据的计算方法,可计算产生中子核反应释放的瞬发光子产生截面、光子与原子的反应截面,裂变产物衰变释放的缓发光子多群产生矩阵,以及光子辐照损伤截面等数据。数值结果显示,如果不考虑缓发光子,钠冷快堆中控制组件、反射层组件的光子功率与参考解的最大偏差可达3258%、2041%,采用NECP Atlas计算的多群缓发光子产生矩阵后两类组件偏差降为093%以下。采用文献结果对Fe的光子辐照损伤截面进行了验证,计算结果与参考解吻合良好。     

The effect of neutron irradiation on mechanical properties of YAG laser weldments using previously irradiated material

The objective of this study is to make clear the effect of neutron irradiation on mechanical properties of laser weldments using irradiated material. This estimation is necessary for the application to joining coolant piping of the ITER blanket. Irradiation testing was performed at Japan Material Testing Reactor (JMTR). On the irradiation condition for weldments using irradiated material, fast neutron fluence was 1.4 × 10²⁴ n/m², which corresponds to a displacement damage rate of 0.26 displacement per atom (dpa) and irradiation temperature 200 °C. The results of this study show that tensile properties of all weldments changed into that of base material by the effect of neutron irradiation. The results of hardness tests show that irradiation hardening at an irradiation damage dose of 0.3 dpa is almost same as that at irradiation damage 0.6 dpa. It is concluded that irradiated weldments using irradiated material were moved toward irradiated base material on tensile and hardness properties up to 0.6 dpa. On the other hand, tensile properties of base material were changed by the effect of neutron irradiation up to about 0.3 dpa, and with much less change from 0.3 dpa to 0.6 dpa. It is inferred that the effect of neutron irradiation of SS316LN-IG almost saturated up to 0.3 dpa.     

Diametral strain of fast reactor MOX fuel pins with austenitic stainless steel cladding irradiated to high burnup

The C3M irradiation test, which was conducted in the experimental fast reactor, “Joyo”, demonstrated that mixed oxide (MOX) fuel pins with austenitic steel cladding could attain a peak pellet burnup of about 130 GWd/t safely. The test fuel assembly consisted of 61 fuel pins, whose design specifications were similar to those of driver fuel pins of a prototype fast breeder reactor, “Monju”. The irradiated fuel pins exhibited diametral strain due to cladding void swelling and irradiation creep. The cladding irradiation creep strain were due to the pellet-cladding mechanical interaction (PCMI) as well as the internal gas pressure. From the fuel pin ceramographs and ¹³⁷Cs gamma scanning, it was found that the PCMI was associated with the pellet swelling which was enhanced by the rim structure formation or by cesium uranate formation. The PCMI due to cesium uranate, which occurred near the top of the MOX fuel column, significantly affected cladding hoop stress and thermal creep, and the latter effect tended to increase the cumulative damage fraction (CDF) of the cladding though the CDF indicated that the cladding still had some margin to failure due to the creep damage.