新型铪控制棒的研制

铪材具有良好的综合性能,是反应堆控制棒的首选材料.为了克服铪板辐照后的变形和力学性能下降等问题,增加控制棒的使用寿命,开展了新型控制棒组件的研制工作.在研制过程中,对铪材的化学成分、机械性能、腐蚀性能、物理性能等进行了试验研究,并进行了成品验证试验,证明此新型控制棒的设计和制造完全满足技术要求,具有良好的机械性能,能有效提高铪控制棒的使用寿命.     

铪替代银-铟-镉合金控制棒价值分析

随着我国锆铪分离技术的突破,核级海绵铪已经实现了工业规模的生产,为国内核电厂使用铪作为控制棒材料奠定了物质基础。本文从控制棒价值及控制棒材料燃耗特性角度,分析天然铪(Hf)、硼化铪(HfB₂)、氢化铪(HfH_X)、氧化铪(HfO₂)4种材料替代银-铟-镉合金(AIC)控制棒的可行性,分析结果表明:从增加控制棒价值的角度,替代AIC的优先顺序为HfB₂>HfH₃>Hf;从工程应用角度,应用于国内主流核电厂时,替代AIC的首选铪材料为Hf。     

堆芯中子学程序系统SARCS-4.0的开发及初步验证

开发了堆芯中子学程序系统SARCS-4.0,该程序系统能处理由任意方形燃料组件组成的堆芯;能计算铀钚、钍铀燃料循环;能计算硼、钆、铒、铪、银、铟、铕、钐等各类可燃毒物和含硼、铪、银-铟-铬、铕、镝等各类控制棒;具备堆芯核设计的基本功能.使用SARCS-4.0系统对超临界水冷反应堆(SCWR)堆芯进行计算以验证程序系统的计算准确性,结果表明,SARCS-4.0系统具有较高计算精度,该系统从功能上、精度上均适用于新型反应堆堆芯选型研究.     

小型模块化快堆中含铪控制棒的设计与分析

快堆一般采用以碳化硼（B4C）为吸收剂的控制棒进行反应性控制。小型模块化快堆中子泄漏率较大,增殖能力偏弱,单位燃耗反应性损失较大。模块化反应堆运行周期较长,且需要紧凑型堆芯设计,控制棒数量有限。因此,小型模块化快堆需要高10B富集度的B4C进行反应性控制。由于吸收剂燃耗深、功率密度高且导热能力受辐照削弱严重,B4C的安全使用寿命有限。本文通过对比硼化铪（HfB2）、氢化铪（HfH162）和传统B4C为吸收剂的控制棒的反应性价值、堆芯功率分布、堆芯反应性反馈系数、控制棒温度裕度与吸收剂燃耗深度,发现HfB2有更高的安全裕度和更长的安全使用寿命。HfH162控制棒略微改善了功率分布,但其高温氢气解离问题有待进一步研究。     

CARR寿期对控制棒价值的影响研究

以铪为吸收体的研究堆中,控制棒价值随着燃耗加深而减小.使用蒙特卡罗软件 MVP-BURN建模计算在寿期内堆芯燃料组件的组成、控制棒中铪的成分随燃耗变化,使用 MCNP 计算程序计算不同寿期棒栅效率曲线.计算得到,控制棒价值与燃耗呈线性关系,在一个换料周期内吸收能力减少大约为 1.4%.在同一个换料周期内,随着寿期进行,...     

带非能动安全系统的一体化船用反应堆研究

一体化船用反应堆可用于极地破冰船和特殊材料运输船、水下海洋观测艇、海水淡化及陆上供热等用途．其主要设计特点是：一体化反应堆。内置型控制棒驱动机构和非能动安全系统．一体化堆型结构紧凑。安全性好，并且减轻了全船的耐压要求．对一体化船用反应堆的研究。主要集中在：①一体化反应堆的研究发展和堆型的选择；②一体化船用反应堆的设计原理和安全要求；③一体化船用堆MRX的堆芯物理和热工设计；④MRX的主回路系统和设备；⑤：MRX的内置型控制棒驱动机构；⑥MRX的非能动应急余热排出系统和充水式安全壳。⑦MRX的安全分析；⑧反应堆和全船的工程模拟系统，研究中特别关注适合高温、高压、高湿度的材料研制以及海洋条件对反应堆安全性能的影响。     

熔盐堆石墨控制棒套管碳纤维布增强工艺及性能研究

在熔盐堆中需要设置控制棒套管,以实现控制棒在反应堆中的自由升降.石墨是理想的控制棒套管材料,但石墨强度与韧性不足,是其作为熔盐堆控制棒套管需要解决的主要问题.首先,在真空环境下用先驱体溶液预浸渍碳纤维布,并将其以一定的张力缠绕在石墨管上.其次,通过先驱体浸渍裂解工艺多次循环压力浸渍、固化、碳化制备不同增密次数和缠绕层数...     

压水堆控制棒价值的亏损速率研究

分析了以天然铪、Ag-In-Cd合金、纯银、B4C为吸收体的控制棒的燃耗特性及价值亏损规律。结果表明,天然铪、纯银的控制棒价值随燃耗呈线性递减,而Ag-In-Cd合金、B4C呈非线性递减,在相同燃耗内B4C的控制棒价值亏损幅度最大,纯银的亏损幅度最小。除以Ag-In-Cd合金为吸收体的控制棒价值亏损速率在燃耗初期出现陡降外,其余吸收体的控制棒价值亏损速率均随燃耗的加深而出现不同程度的增加。     

微型中子源反应堆改进方案研究

分析研究了使微型中子源反应堆延长单次运行时间的几种改进方案。研究与实验结果表明,在中心控制棒与堆芯原有结构保持不变,不超过安全运行限值的情况下,在侧铍反射层外附加弧形补偿板,再添加适当当量的顶铍片后,中心控制棒与补偿板联动,可使微型中子源反应堆一次连续运行时间大大提高．提高了微型中子源反应堆的运行性能。     

状态微分反馈控制与压水反应堆功率现有两种控制系统的等价性研究

本文提出了一种新型的反馈控制--状态微分反馈控制,并用于设计负荷跟随运行模式下的反应堆控制系统。设计过程依赖于控制棒位置的积分控制和控制棒速度的状态微分反馈控制两种控制系统之间的等价性,这一关系被证明并总结为定理。数值仿真结果表明,所设计的反应堆功率的状态微分反馈控制系统具有很好的负荷跟随模式性能。     

Terminal Solid Solubility of Hydrogen in Hafnium

The terminal solid solubility (TSS) of hydrogen during hydride dissolution/precipitation is determined by differential scanning calorimetry technique for nonirradiated hafnium (Hf) that is used as control rods of light water reactors. The hydrogen concentration in hydrogenated Hf samples ranged from 27 to 300 wt ppm. The reliability of the TSS data obtained for Hf was confirmed using those for Zircaloy-2 (Zry-2) obtained in this study with the literature data, and best-fit equations for the obtained TSS curves for Hf are derived. The TSS for Hf at 573 K, which corresponds to an operational temperature of control rods in boiling water reactors, is in the range of 10–15 wt ppm, and is found to be 1/5–1/7 of the TSS for Zry-2.     

An Effective Method for Estimating Multiple Control Rod Worths in Large Fast Reactors

A method for estimating the multiple control rod worth in large fast reactors has been developed using the higher order perturbation technique. With this method, physical significance of the interaction effect between multiple control rods can be understood by decomposing it into independent components with different physical processes. Furthermore, a new technique is proposed, whereby the interaction effect between multiple control rods can be estimated from a combination of the interaction effects between two or three control rods depending on the strength of the effect. The validity of the method is examined with the experimental data of PHENIX and numerically for MONJU. The results show that the interaction effect between multiple control rods in prototype fast reactors can be estimated from a combination of the effects between 2 control rods with a good accuracy. The numerical examinations for a 1,000 MWe fast reactor showed that the interaction effect is too large to apply the present method for large fast reactors. To overcome this difficulty, a new concept of “quasi-control-rod” is introduced in the method. With this improved method, the worths of 19 and 18 control rods in the 1,000 MWe fast reactor are estimated with accuracies of ±2%.     

Prospects for zirconium and hafnium supplies for nuclear power in Russia up to 2030

The prospects for supplying zirconium and hafnium-the main structural and prospective absorbing material for thermal reactors-are examined in accordance with the strategy for the development of nuclear power in our country up to 2030. The present situation concerning the use of Russian nuclear fuel is described. The characteristics of the main zirconium alloys used in domestic and foreign thermal reactors and the approximate requirements for baddeleyite and zirconium concentrates, the distribution of balance zirconium reserves, and the requirements of the nuclear industry for hafnium metal and hafnium compounds are presented. Translated from Atomnaya énergiya, Vol. 105, No. 4, pp. 190–194, October, 2008.     

Design,construction and simulation of a multipurpose system for precision movement of control rods in nuclear reactors

This article presents the design and implementation of a microcontroller-based system for the automatic movement of control rods in nuclear reactors of either power or research types. This system is controlled automatically, is linked to a personal computer system, and has manual controlling ability as well. The important features of this system are: automatic scram of the control rods, activation of alarm in emergency situations, and the ability to tune the control rod movement course both upwards and downwards. In this system, a small tank has been improvised as a coolant reservoir for pool type reactors such as Tehran Research Reactor and its water level is continuously adjusted by special sensors. Also, this system can be applied for controlling various types of control rods such as the regulating rods, safety rods and shim rods; can be connected to all reactor measurement tools and systems such as the period meter, power meter and flux meter; and can receive feedback signals from them. The devised system can be calibrated with these measurement tools by two special potentiometers in the related electronic board. The processes of this system have been simulated by the SIMULINK tool kit of MATLAB software and all responses of the system, including oscillation and transient responses, have been analyzed.     

Research on Segment Design of Control Rod in Sodium-cooled Fast Reactor

In sodium-cooled fast reactors, control rods are commonly used to compensate for the excess reactivity and shut down the reactor. The traditional sodium-cooled fast reactor design consists of the safety rod, shim rod and regulating rod. The 10B enrichment of the shim rods is relatively higher, which unavoidably increases the burnup, the heat generation and the power peak factor of the fuel assemblies around the shim rods. To solve this issue, the segment design of control rods was proposed. Compared with traditional design, the new design can significantly reduce the heat generation by about 30 percent and burnup of control rods by about 50 percent, as well as improve the power peak factor of the fuel assemblies around the shim rods. The replacement cycle of the control rods can be extended by time.     

钠冷快堆控制棒分段设计研究

在钠冷快堆中,反应堆运行时的反应性补偿和停堆安全主要由控制棒来实现。当前的钠冷快堆设计中,一般含有安全棒、补偿棒和调节棒。其中,补偿棒中10B的富集度较高,使补偿棒的燃耗较高,且发热量较大,并造成周围燃料组件功率峰因子偏大。本文提出一种分段设计方案,可用于改进上述缺点。该方案相比于传统方案,控制棒发热减小约30%,控制棒燃耗减小50%,并能有效改善周围燃料组件的功率峰因子,控制棒更换周期可提升1倍。     

Performance of UO2 ceramic fuel in low-power research reactors

The Low Enriched Uranium UO₂ fuel performance in low-power research reactors is assessed in this paper. The usability of this fuel has been demonstrated in some research reactors in the world (SLOWPOKE-2). The fuel proved to be usable in the miniature neutron source low-power research reactors when about 50 fuel rods were substituted by as many dummy rods, while in SLOWPOKE reactors the number of fuel pins reduced by 98. About 3.8531 mk reactivity was rendered available at reactor start-up in MNSRs. The power of MNSRs needed to be increased by about 19%. Shut-down margin, effective shut-down margin, and control rod worth all decreased.     

Core design improvement by optimizing the control and protection system elements distribution

One of the main attributes of reactor core design is finding the best distribution of the core control and protection system. Nuclear reactors have several distinct types of control and protection elements, such as control rods, shimming rods and emergency rods. Each of these elements performs a separate task in a control procedure. The distribution of these elements in the core contributes to their worth and expense, therefore finding the best location and distribution of the control protection system (CPS) elements is very important from the view point of nuclear reactor design and safety.