乏燃料溶液系统临界安全分析计算方法研究

Critical safety analysis method of spent fuel solution system

核临界安全分析是保证乏燃料后处理厂安全性的关键技术,而现有核临界安全事故分析程序中,或在几何适用范围上受限,或由于计算效率低而工程实用性差。因此,亟需研发一套适用范围大、计算精度高的临界安全分析方法,提高对核临界事故的分析精度,为乏燃料后处理厂提供技术保障。为此,本文针对乏燃料溶液系统特性,基于零维超细群截面制作与全问题并群方法、预估-校正准静态中子动力学计算方法和二维轴对称热工-辐解气体模型,开发了相应的计算程序模块,最终形成了一套具备并行功能的三维乏燃料溶液系统临界安全分析程序hydra-TD。进一步利用该程序对法国SILENE实验装置进行了验证,结果显示:第一裂变功率峰、倍增时间、总裂变次数等关键参数的误差较小,证明hydra-TD程序正确模拟了燃料溶液系统临界过程中的多物理过程,具备临界安全分析的能力。

[Background]Nuclear critical safety analysis is the key technology to ensure the safety of spent fuel reprocessing plant.However,the present critical safety analysis codes for solution system are either limited in the geometric scope of application,or have poor engineering practicability due to low computational efficiency.[Purpose]This study aims to develop a method suitable for wide application range and high accuracy for nuclear critical safety analysis,so as to provide technical support for spent fuel reprocessing plant.[Methods]According to the characteristics of spent fuel solution system,a set of methods,such as the zero-dimension cross-section calculation and whole system group condensation model,the three-dimensional space-time neutron dynamics model based on PCQS,and the R-Z two dimensional thermal and radiolysis gas simulation model,were combined to establish a paralleled 3D critical safety analysis code hydra-TD.In addition,some experiments of SILENE facility at France were modeled and calculated by using hydra-TD code to verify its effectiveness.[Results]The verification results indicate that there are very small errors of key parameters such as the first fission power peak,multiplication time and total fission times.[Conclusion]The code hydra-TD developed in this study can be applied to simulation of the multi-physics processes in the critical transients of the fuel solution,hence has the ability of critical safety analysis.