共查询到18条相似文献,搜索用时 125 毫秒
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我们采用小型固体核径迹探测器实现了多测点布置及有效地消除了缝隙泄漏中子影响等技术关键。成功地测得了小直径控制棒内中子注量率精细分布。 1.实验原理和方法 把由~(235)U电镀靶片和天然白云母片组成的探测器置入被测样品内。在反应堆中辐照后云母片上形成的径迹密度与所处位置的中子注量率成正比关系, 相似文献
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Ag-In-Cd芯体的辐照肿胀规律是评价控制棒堆内运行安全性的基础。辐照后Ag-In-Cd芯体的成分变化是引起肿胀的主要物理原因,但目前尚未看到定量计算成分变化的研究报道。本文根据Ag-InCd芯体中各核素的嬗变反应方式和反应截面,建立描述芯体成分变化的微分方程组,编写该微分方程组的数值计算程序,计算预测芯体成分随热中子注量的变化规律。当热中子注量为1.5×1021~6.2×1021 cm-2时,芯体中各元素的含量与热中子注量之间呈较好的线性关系,而芯体表层Sn和Cd的含量会达到中心含量的2倍以上。 相似文献
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Ag-In-Cd合金在核电站压水堆控制棒中广泛使用,其辐照肿胀行为是评价Ag-In-Cd控制棒使用寿命的关键因素。本文通过制备不同成分的模拟合金,来模拟Ag-In-Cd合金在堆内辐照后的成分变化,分析合金的密度及微观组织特点。结果发现,当Ag含量低至77.5%(质量分数)时,合金会分解为fcc和hcp两相,fcc相中贫Sn高Ag,hcp相中富Sn低Ag。当Ag含量在55%~61%之间时,合金以hcp单相存在。由实测的密度拟合出了合金密度随成分变化的关系式。此结果对于理解和掌握Ag-InCd合金的辐照肿胀行为有重要意义。 相似文献
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利用固体径迹探测器测量反应堆不同位置燃料元件内的中子注量率,得到反应堆燃料元件内的中子注量率分布。与对应点慢化剂内中子注量率进行比较,对反应堆物理实验中一个近似假设公式ΦU(r)/ΦU≈ΦM(r)/ΦM进行了验证。给出了该公式成立的条件。 相似文献
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《同位素》2020,(2)
建立了热电离质谱法(TIMS)测量天然及辐照后氧化钆同位素丰度比的检测方法。天然氧化钆制备成靶件,放入高通量工程试验堆(HFETR)预定孔道接受中子辐照,辐照时间共计91.3 h,反应堆功率为80 MW,辐照孔道中子注量率约为2×10~(14) n·cm~(-2)·s~(-1)。辐照后靶件经切割、转运、溶解、制样与测量等过程,完成了对可燃中子毒物钆的辐照与测量,并对测量值进行了修正。数据结果表明,热电离质谱法对Gd辐照后检验的分析数据准确可靠,辐照后样品的后处理方法合理,钆的各同位素的丰度变化值前后吻合,且与中子吸收截面大小密切相关。本方法可用于铀钆混合燃料芯块和卸料元件组件中可燃毒物钆的同位素分析。获得的实测数据可反向用于理论计算修正,以期获得更优的反应堆堆芯设计方案。 相似文献
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M.K. Shoushtari S.M. Sadat Kiai H. Ghaforian 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(5):519-523
The Monte Carlo simulation has been established for a research reactor with nominal power of 7 MW. A detailed model of the reactor core was employed including standard and control fuel elements, reflectors, irradiation channels, control rods, reactor pool and thermal column. The following physical parameters of reactor core were calculated for the present LEU core: core reactivity (ρ), control rod (CR) worth, thermal and epithermal neutron flux distributions, shutdown margin and delayed neutron fraction. Reduction of unfavorable effects of blockage probability of control safety rod (CSR)s in their interiors because of not enough space in their sites, and lack of suitable capabilities to fabricate very thin plates for CSR cladding, is the main aim of the present study. Making the absorber rod thinner and CSR cladding thicker by introducing a better blackness absorbing material and a new stainless steel alloy, respectively, are two studied ways to reduce the effects of mentioned problems. 相似文献
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球床氟盐冷却高温堆的控制棒位于侧反应射层内,存在无裂变中子源且受堆芯泄漏谱强烈影响的强吸收体区域扩散计算难题。超级均匀化方法(Super Homogenization,SPH)被用于对氟盐球冷却床堆侧反射层中控制棒区域的强吸收体进行等效均匀化处理,同时堆芯除控制棒区域外采用谱修正方法(Spectra Modification,SM),将输运计算的结果作为基准进行验算。结果表明,SM-SPH模型能有效地计算球床氟盐冷却高温堆反射层控制棒价值及通量分布,并且较常规的SPH方法能更好地处理棒间干涉效应。 相似文献
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张家骅 《核技术(英文版)》1996,(1)
ExistenceofthefifthunstablenuclidedseriesZhangJia-Hua(张家骅)(ShanghaiInstituteofNuclearResearch,theChineseAcademyofSciences,Sha... 相似文献
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A Monte Carlo simulation of a typical 5 MW research reactor (TRR) was carried out using MCNP4C code. The geometry of the reactor core was modeled including the details of all fuel elements, control rods, all irradiation channels, graphite reflectors, reactor pool and thermal column. The model predicted neutron flux distributions within the core, control rod (CR) worth, core reactivity (ρ), shutdown margin, and some kinetic parameters when the control rod insert or withdraw. This study was carried out to reduce blockage probability of shim safety rod (SSR)s of the TRR. Two introduced more blackness SSRs were chosen and made thinner in a way adequate blackness, in comparison to the present rods, achieved. 相似文献
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Reactions resulting in the accumulation of 3He and 6Li, whose thermal neutron capture cross-section is large, occur under the action of neutron radiation in the beryllium blocks
of the MIR reactor core. When a neutron absorber accumulates in the moderator of a reactor, important physical characteristics
change: reactivity access, efficiency of safety and control rods, and reactivity effects; in addition, energy release is redistributed.
An algorithm for calculating 3H, 3He, and 6Li in each beryllium block of the core has been developed and implemented. This algorithm makes it possible to follow the
change in the concentration of these nuclides during reactor operation and shutdown. The 3He and 6Li concentrations are used as initial data for calculating the neutron-physical characteristics of the MIR reactor using the
MCU and BERCLI programs. The computational results for the effect of the accumulation of the nuclides indicated on the neutron-physical
characteristics of the core are presented.
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Translated from Atomnaya énergiya, Vol. 104, No. 2, pp. 84–88, February, 2008. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(4):421-429
A hydride control rod is being developed to improve the economy of fast reactor plants because it has a longer lifetime than the currently used B4C control rod. A hydride burnable poison rod is also under development to reduce the number of control rods by decreasing core excess reactivity. Hydrogen in the hydride control rod causes neutron spectrum interference between the fuel and control rod regions. Thus, the study on core design was performed with the continuous-energy Monte Carlo code MVP using the nuclear data library JENDL-3.3 to deal with this phenomenon precisely. To evaluate the applicability of MVP to hydride absorber rod design, two benchmark calculations were carried out. One of them is a hydrogen-contained metal fuel fast core constructed in Fast Critical Assembly (FCA) and the other is the Nuclear Safety Research Reactor (NSRR) core where zirconium-hydride fuel (U-ZrH1.6) rods are loaded. These benchmark calculations and the design study on a fast reactor core with hafnium-hydride control rods have revealed that MVP is a reliable tool for hydride absorber rod design. 相似文献
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The dependence of rod vibration induced, neutron density fluctuations on the static neutron gradients was investigated experimentally at the QMC research reactor. By appropriate fuel loading arrangements the rod was made to vibrate (a) within a flat flux and (b) a flux gradient. The neutron density was fluctuating with the frequency of the vibrating absorber only when the static flux gradient in the vicinity of the absorber was not zero. The double frequency effect was not observed. 相似文献