摘要
从考虑燃料装载格式影响的普遍反应性平衡方程出发,用Z变换法研究了燃料循环的动态变化过程。对燃料类型和换料策略给定的变循环寿期长度问题和循环寿期长度和换料策略给定的变循环初换入堆内新燃料初始反应性问题,求得了动态过程的解析解。发现除换料策略(m+f)外,燃料装载格式是影响燃料循环动态过程的重要因素,须予以考虑。文中对轻水堆常用的换料策略作了探讨,并给出数值例子。另外。论证了Lewins对上述第二类问题的收敛性结论,只是在堆芯平功率分布的假设下才成立,对Out-in或低泄漏换料方案是不适用的。对压水堆采用的(3+f)换料策略,导出了动态过程收敛性的普遍判据。
Based on the general reactivity balance equations which were taken into account the effect of fuel loading pattern, in-core fuel cycle dynamic behavior has been analysed by means of Z-Transform Method. This paper offers analytical solutions of dynamic behavior to be expected in two typical forms of the problem. These representative problems are identified as follows. l)with fixed type fuel assemblies and fixed refueling strategy, study the sequence of cycle times. 2)With fixed cycle times and fixed refueling strategy, study the sequence of initial reactivities or enrichment. We discover that the loading pattern has an important effect on the fuel cycle dynamic behavior besides refueling strategy (m +f), so that the loading pattern must be considered in studying fuel cycle dynamic behavior. This paper gives some numerical examples for LWRs. In the second problem, Lewins has demonstrated that the initial reactivity sequence has two possible forms. In the integer batch refueling case he obtained an m-fold pure oscillation around a neutral center. Alternatively, if the refueling strategy is noninteger, the reactivity sequence is convergent to the expected stability center. We demonstrate that his conclusion is not suitable to out-in or low leakage loading pattern. His conclusion is true only if the core power distribution is flat. We establish a general convergence criterion for refueling strategy (3+f), which can be used for PWRs.
出处
《核科学与工程》
CSCD
北大核心
1989年第1期45-56,6,共12页
Nuclear Science and Engineering
