基于精细燃耗历史及精细燃耗链的球床高温气冷堆燃耗不确定性分析

Pebble-Bed High-Temperature Gas-Cooled Reactor Burnup Uncertainty Analysis Based on Fine Burnup History and Fine Burnup Chains

球床高温气冷堆的燃料管理具有燃料球多次通过堆芯的特点,使得燃料元件经历的燃耗历史十分复杂。球床高温气冷堆堆芯物理设计程序VSOP可以提供燃料元件的精细燃耗历史,但仅包含少量燃耗链和核素种类。而清华大学自主开发的燃耗计算程序NUIT可实现精细燃耗计算,且包含完整燃耗链和核素信息,但不具备精细燃耗历史跟踪功能。本文基于NUIT,结合VSOP提供的球床高温气冷堆精细燃耗历史,开发了球床高温气冷堆堆芯的精细燃耗计算功能,搭建了带有精细燃耗历史模拟和精细燃耗链核素的燃耗分析流程,并实现燃耗不确定性分析功能。在此基础上研究了裂变产额不确定性对球床高温气冷堆燃耗计算不确定性的贡献,并与VSOP的计算结果进行对比。计算分析结果显示,基于NUIT的精细燃耗计算结果和VSOP的燃耗计算结果得到了相互验证,且可以得到更多的核素浓度信息,该计算结果是开展球床高温气冷堆衰变热不确定性研究的基础。

The fuel element burnup history becomes extremely complex as a result of the multi�pass of the fuel pebble through the reactor core in fuel management of the pebble-bed high�temperature gas-cooled reactor(PB-HTGR).The core physical design program VSOP of PB-HTGR can provide a fine burnup history of fuel elements,but it involves only a small number of burn-up chains and nuclide species.The burnup calculation program NUIT developed independently by Tsinghua University can realize fine burnup calculation and contains complete burnup chain and nuclide information,but it cannot track the fine burnup history.In this paper,we will develop the fine burnup calculation function of PB-HTGR based on NUIT and the fine burnup history of PB�HTGR provided by VSOP,build a burnup analysis process with fine burnup history simulation and fine burnup chain nuclides and realize a burnup uncertainty analysis function.On this basis,the contribution of fission yield uncertainty to the burnup calculation contribution of PB-HTGR is studied,and the results are compared with the VSOP calculation results.The calculation and analysis results show that the fine burnup calculation results based on NUIT and the burnup calculation results based on VSOP are mutually verified,and more nuclide information can be obtained.Such calculation results can be used as a basis for the decay heat uncertainty study of PB�HTGR.