A novel channel selection method for CANDU refuelling based on the BPANN and GA techniques

A novel channel selection method for CANDU refuelling based on the back-propagation artificial neural network (BPANN) and genetic algorithm (GA) techniques is developed. In this method, GA is used as an “optimization tool” and BPANN as a refuelling “simulator” used to predict the core parameters. Based on this method an automatic refuelling channel selection program for CANDU reactors has been developed and tested by the refuelling simulation of the Qinshan Phase III CANDU reactor for 400 effective full power days. The numerical results show that the average properties of the time-dependent core are very close to the reference one and the refuelling channel selection method possesses superior computational efficiency.     

用于CANDU堆换料方案快速评价的线性敏感矩阵方法

为了实现CANDU堆换料方案的快速评价,本文提出了线性敏感矩阵方法(LSM).该方法基于各种扰动引起的堆芯状态变化互不干涉且堆芯对扰动的响应与扰动量成正比的假设,借助于事先针对参考堆芯形成的敏感矩阵,主要的堆芯参数经简单代数运算就可得到,无需耗时的三维扩散方程求解.秦山三期1号机组部分运行历史检验结果表明,该方法不但可大幅提高换料方案评价的速度,而且还具有较高的精度,能满足现场工程应用的要求.     

DERMAGA – An alternative tool to generate random patterned-channel-age in CANDU fuel management analyses part I: Method development

In any reactor physics analysis, the instantaneous power distribution in the reactor core of any power reactor, including CANDU-type reactor, can be calculated when the actual bundle-wise burnup distribution is known. Considering the fact that CANDU utilizes the on-power refuelling to compensate for the reduction in reactivity due to fuel burnup, in the CANDU fuel management analysis, snapshots of power and burnup distributions can be obtained by simulating and tracking reactor operation over an extended period using various tools such as the *SIMULATE module of the reactor fuelling simulation program (RFSP) code. However, for some studies, such as an evaluation of a conceptual design of a next generation CANDU reactor, the preferred approach to obtain a snapshot of the power distribution in the core is based on the patterned-channel-age model implemented in the *INSTANTAN module of the RFSP code. The objective of this approach is to obtain a representative snapshot of core conditions quickly. Presently such patterns could be generated by a program called RANDIS which is implemented within the *INSTANTAN module. Presented in this paper is an alternative approach to derive the patterned-channel-age model where an optimization algorithm is utilized to find patterns which produce representative power distributions in the core. In the present analysis, the genetic algorithm (GA) technique has been successfully utilized to find a quasi-optimal patterned-channel-age. This paper is Part I of a two-part paper which highlights the development of this alternative method for generating patterned-channel-ages.     

A generalized perturbation theory program for CANDU core analysis

A generalized perturbation program GENOVA has been developed for the purpose of various applications to Canada deuterium uranium (CANDU) reactor physics analyses. The program was developed under the framework of CANDU physics design and analysis code RFSP. The generalized perturbation method was implemented to estimate the power distribution in conjunction with the zone controller level. The numerical algorithm of the generalized perturbation method was verified by a simple 2×2 node problem. The capability of predicting the zone controller level was validated for a CANDU-6 reactor refueling problem. GENOVA is compatible with the current CANDU physics design code and, therefore, it can be used for advanced CANDU core analysis and fuel development in the future.     

秦山三期CANDU核电厂的运行特性及其管理

ＣＡＮＤＵ－６核电厂的设计特征与其它类型反应堆的核电厂很不相同。这些设计特性是ＣＡＮＤＵ６安全经济运行的主要保证。ＣＡＮＤＵ－６核电厂的控制和运行特性包括极好的负荷跟踪能力、频率稳定能力和高的容量因子，而运行管理特点包括不停堆换料以及由于使用重水作冷却剂和慢化剂和相关的重水管理问题。     

秦山CANDU堆功率测量校正和控制改进

本文介绍了秦山三核CANDU6堆功率测量、控制设备的分区布置,论述了反应堆功率控制信号的计算校正和反应堆的区域功率控制,从CANDU6核功率控制设备、堆物理角度浅析其实现分区精细控制的机理,并阐述了为了提高反应堆功率控制系统可靠性和安全性而进行的主要设计改进     

秦山CANDU堆物理跟踪计算从基于PPV到WIMS-AECL程序的转换

秦山CANDU重水堆物理跟踪计算使用的基本栅元计算,使用的是PPV程序计算产生的1.5群栅元截面,随着对计算精度越来越高的要求,以及将来新燃料类型的使用,有必要更新为WIMSAECL程序计算产生的2群栅元截面。本文重点研究基本栅元计算程序从PPV到WIMS-AECL的转换,以及基于转换后的程序,堆芯跟踪计算程序系统的更新方法,并对转换前后的计算结果进行了对比分析。     

Utilization of spent PWR fuel-advanced nuclear fuel cycle of PWR／CANDU synergism

High neutron economy, on line refueling and channel design result in the unsurpassed fuel cycle flexi-bility and variety for CANDU reactors. According to the Chinese national conditions that China has both PWR and CANDU reactors and the closed cycle policy of reprocessing the spent PWR fuel is adopted, one of the advanced nu-clear fuel cycles of PWR/CANDU synergism using the reprocessed uranium of spent PWR fuel in CANDU reactor is proposed, which will save the uranium resource (-22.5%), increase the energy output (-41%), decrease the quantity of spent fuels to be disposed (-2/3) and lower the cost of nuclear poower, Because of the inherent flexibility of nuclearfuel cycle in CANDU reactor, and the low radiation level of recycled uranium(RU), which is acceptable for CANDU reactor fuel fabrication, the transition from the natural uranium to the RU can be completed without major modifica-tion of the reactor core structure and operation mode.It can be implemented in Qinshan Phase Ⅲ CANDU reactors with little or no requirement of big investment in new design. It can be expected that the reuse of recycled uranium of spent PWR fuel in CANDU reactor is a feasible and desirable strategy in China.     

An asymptotic estimate for optimal reactor refuelling strategy

Conclusion The simple formula, derived for estimating the optimal number of reactor refuellings during the fuel lifetime may prove to be very useful for IFC planning. They can be used to easily estimate the effect of various factorson the refuelling strategy, such as the load factor of the generating unit, fuel costs, or shutdown time during refuelling, testing, and maintenance of equipment. The FEP model allows solving a number of other similar problems.The conclusions based on the quantitative estimates should not be interpreted as general unambiguous recommendations. This would be contrary to the established conception of individual approach to IFC planning for each reactor.The author would like to thank V. A. Sidorenko for suggesting the topic of this research and Ya. V. Shevel'ev for useful comments and advice that helped to bring the article in its present form.Translated from Atmonaya Énergiya, Vo. 59, No. 4, pp. 243–247, October, 1985.     

Scenarios for the transmutation of actinides in CANDU reactors

With world stockpiles of used nuclear fuel increasing, the need to address the long-term utilization of this resource is being studied. Many of the transuranic (TRU) actinides in nuclear spent fuel produce decay heat for long durations, resulting in significant nuclear waste management challenges. These actinides can be transmuted to shorter-lived isotopes to reduce the decay heat period or consumed as fuel in a CANDU(R) reactor.Many of the design features of the CANDU reactor make it uniquely adaptable to actinide transmutation. The small, simple fuel bundle simplifies the fabrication and handling of active fuels. Online refuelling allows precise management of core reactivity and separate insertion of the actinides and fuel bundles into the core. The high neutron economy of the CANDU reactor results in high TRU destruction to fissile-loading ratio.This paper provides a summary of actinide transmutation schemes that have been studied in CANDU reactors at AECL, including the works performed in the past ( [Boczar et al., 1996] , [Chan et al., 1997] , [Hyland and Dyck, 2007] and [Hyland et al., 2009] ). The schemes studied include homogeneous scenarios in which actinides are uniformly distributed in all fuel bundles in the reactor, as well as heterogeneous scenarios in which dedicated channels in the reactor are loaded with actinide targets and the rest of the reactor is loaded with fuel.The transmutation schemes that are presented reflect several different partitioning schemes. Separation of americium, often with curium, from the other actinides enables targeted destruction of americium, which is a main contributor to the decay heat 100–1000 years after discharge from the reactor. Another scheme is group-extracted transuranic elements, in which all of the transuranic elements, plutonium (Pu), neptunium (Np), americium (Am), and curium (Cm) are extracted together and then transmuted. This paper also addresses ways of utilizing the recycled uranium, another stream from the separation of spent nuclear fuel, in order to drive the transmutation of other actinides.