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物理-热工耦合是超临界水堆系统分析的关键问题之一。以日本超临界水冷热堆Super LWR的堆芯设计为例,借助Dragon编制中子截面数据库,建立双群中子扩散方程计算模块,联系同时建立的热工计算模块,得到超临界水堆的物理-热工耦合计算模型。通过对比稳态与瞬态工况下耦合前、后的热工工况,分析物理-热工耦合条件下的超临界水堆系统热工特性。结果表明:在稳态工况下,物理-热工耦合将导致内、外组件堆芯功率峰值沿轴向发生明显偏移,使得部分节点的包壳温度升高,但包壳最高温度降低;在瞬态工况下,物理-热工耦合将导致堆芯包壳最高温度的发生位置有所改变。发生给水加热丧失瞬态后,在某一时刻,外部组件的包壳最高温度将转而超过内部组件的包壳最高温度。可见,物理-热工耦合对包壳最高温度的大小和发生位置均可能产生明显影响。计算分析可为超临界水堆瞬态及安全分析提供相应理论参考。 相似文献
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针对一种新型的超临界水堆设计方案——混合能谱超临界水堆(SCWR-M)进行分析。混合能谱超临界水堆包括热谱区和快谱区两部分,分别布置在堆芯的外部与内部。它在继承了热谱与快谱超临界堆芯设计优点的同时,有效地克服了两者的不足。对于热谱区,冷却剂与慢化剂同向流动,大幅降低了燃料包壳的表面温度和组件的机械加工难度;对于快谱区,采用多层燃料组件和较大的栅距棒径比p/d,可得到较高的燃料转换比和较小的冷却剂负反应性系数。本工作采用自主开发的基于子通道分析和三维物理计算的耦合程序,对混合能谱超临界水堆的热工性能和中子物理性能(包括燃耗性能)进行研究。初步的耦合分析结果表明了混合能谱超临界水堆设计方案的可行性。 相似文献
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针对超临界水堆堆芯内流体物性分布非均匀性显著、核热反馈强烈的特点,建立了适用于超临界水堆运行环境的、基于燃料棒层面的精细化堆芯中子学/热工水力耦合方法,开发了子通道程序NCEDSCWR、节块扩散计算程序MRAPS、多功能程序COUPLE,结合西屋公司组件能谱计算程序PARAGON,构建了堆芯中子学/热工耦合分析程序系统SCAP。以具有121盒燃料组件的超临界水堆堆芯进行模拟分析,研究了堆芯三维功率分布和流体物性分布的特点以及反应性参数与重要同位素密度等随燃耗的变化规律。结果表明,本文提出的精细化核热耦合方法和开发的程序系统可以应用于超临界水堆堆芯的研究与分析,相关研究结果对超临界水堆堆芯设计具有一定的指导意义。 相似文献
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提出了超临界水冷混合堆快谱区多层燃料组件设计方案.应用MCNP程序为该组件建立计算模型,并进行了相应的物理计算;同时运用子通道分析程序STAFAS对多层燃料组件子通道进行了初步的稳态热工分析.计算结果表明:超临界水冷混合堆快谱区多层燃料组件燃料转换比超过1.0,并且获得负的冷却剂空泡反应性系数;燃料包壳表面最高温度约为595℃,低于设计准则规定的上限值,同时组件各子通道出口冷却剂温度均匀性较好.通过对燃料棒径敏感性分析可知,较大棒径组件燃料转换比较大,但也会导致热通道包壳表面温度峰值升高. 相似文献
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中欧核能合作研究项目超临界水堆燃料验证实验(SCWR-FQT)的主要研究内容为在超临界水环境下对一个小型燃料组件进行堆内性能分析和验证。本文应用修过后的系统程序ATHLET-SC对该实验回路进行建模,同时结合堆芯中子物理的计算结果,对由于压力管进口管破裂形成的失水事故进行热工水力和中子物理的耦合分析,并讨论了物理耦合中停堆棒的负反应性、冷却剂温度系数等参数对结果的影响。计算结果表明,进行了中子物理耦合的结果得到的最高包壳温度比未进行中子耦合的结果要低15℃,同时停堆棒引入的负反应性是该事故过程中影响燃料棒最高包壳温度的一个主要因素。 相似文献
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A.A. Burlon A.J. Kreiner 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(5):763-771
In this work, the performance of an accelerator-based neutron source design has been compared with that of a modern fluoride-filtered reactor-based epithermal beam having near-optimal quality for treatment of deep seated tumors in relation to its applicability for BNCT. The accelerator is a Tandem-Electrostatic-Quadrupole (TESQ) accelerator which is a design under development at the National Atomic Energy Commission (CNEA) in Buenos Aires, Argentina based on the 7Li(p,n)7Be reaction, relatively close to its energy threshold. The reactor is the Massachusetts Institute of Technology reactor upgraded with a Fission Converter Beam (MIT-FCB) and improved with an 8 mm thick 6Li filter. The comparison has been done by means of data reported on the MIT-FCB + 6Li filter performance and MCNP simulations on our TESQ design considering the neutron fluxes provided by the two sources and the doses delivered in a human phantom by both devices. The results show a deeper advantage depth (AD) for the TESQ which turns out to be a promising alternative to a reactor-based BNCT treatment. 相似文献
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This paper presents an extension to a point kinetics model of fissile solution undergoing a transient through the development and addition of correlations which describe neutronics and thermal parameters and physical models. These correlations allow relevant parameters to be modelled as a function of time as the composition of the solution changes over time due to the addition of material and the evaporation of water from the surface of the solution. This allows the simulation of two scenarios. In the first scenario a critical system eventually becomes subcritical through under-moderation as its water content evaporates. In the second scenario an under-moderated system becomes critical as water is added before becoming subcritical as it becomes over-moderated. The models and correlations used in this paper are relatively idealised and are limited to a particular geometry and fissile solution composition. However, the results produced appear physically plausible and demonstrate that simulation of these processes are important to the long term development of transients in fissile solutions and provide a qualitative indication of the types of behaviour that may result in such situations. 相似文献
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V. I. Nosov 《Atomic Energy》1961,9(4):795-803
The conditions of criticality and the distributions of the neutron flux for a homogeneous thermal-neutron reactor with a system of absorbing rods are obtained in the two-group approximation. The rods extend through the entire depth of the reactor and are situated around the circumference of the active zone or radial reflector at a uniform distance from one another. The results of the calculation are presented.The author expresses his gratitude to Ya. V. Shevelev for discussing basic questions connected with this work, and also to N. N. Ponomarev-Stepnii and E. S. Glushkov for aid and critical remarks. Numerous and difficult calculations were performed by R. V. Kulev, to whom the author is very grateful. 相似文献
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The behavior of a charge-sensitive preamplifier exhibiting a stabilized cold resistance at the input port is analyzed in view of its application as a low-noise termination for a cable or a delay-line transformer. Its use in conjuction with a remote semiconductor detector of large capacitance is discussed. Results obtained with different values of cable length, detector capacitance and shaping time constants are given. It is concluded that such a preamplifier can be successfully employed in several circumstances associated with silicon live targets in high-energy experiments. 相似文献
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The thermal stress problem of a circular discontinuity in a cylindrical shell has been solved by continuum approach. Two types of discontinuities are considered: (i) a circular hole and (ii) a circular regid inclusion. The effect of a uniform temperature or a linearly varying temperature across the thickness has been studied. The problem is converted into an equivalent boundary value problem and boundary conditions are specified around the discontinuity. The results are presented in a graphical form for ready use. 相似文献
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