Abstract

Based on the analysis of experiments carried out on simulators of fuel elements with a cladding of low-melting metals, models of melting and movement of the melt over the surface of fuel elements are proposed. The presented work is a continuation of experimental and theoretical work carried out jointly at the Nuclear Safety Institute, Russian Academy of Sciences, and Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, to study the features of the movement of a melt over a cylindrical surface that simulates the surface of a fuel element. It analyzes the factors that determine the thermal destruction of fuel elements. One of the important conclusions drawn from the analysis of experimental data was the conclusion about the prevailing film laminar runoff in the heated part of the fuel element simulator. Using this assumption, an analytical model was built that allows predicting the mass of a fuel element carried out of its limits during melting. As a result of calculations using the proposed model, it was shown that, for an accident with the introduction of positive reactivity, when the power increase can reach ten ratings, a modification of the model is necessary to take into account the turbulent runoff regime. For this purpose, a simplified model of the flow of the melt was built. A comparison is made with known techniques and it is shown that the proposed approach makes it possible to describe the turbulent flow regime with satisfactory accuracy. The modified model made it possible to calculate the features of the movement of a stainless steel melt over the surface of a fuel element of a fast neutron (BN) reactor. Information was obtained on the thickness of the melt, its velocity and Reynolds number, depending on the conditions of drainage, and on the mass carried outside the core.

中文翻译：

---

分析燃料销表面融化运动的开发方法

摘要

基于在具有低熔点金属包覆层的燃料元件模拟器上进行的实验分析，提出了熔体在燃料元件表面上的熔化和运动的模型。呈现的工作是在俄罗斯科学院核安全研究所和俄罗斯科学院西伯利亚分校库塔拉德泽热物理研究所共同开展的实验和理论工作的延续，以研究熔体在地上运动的特征。模拟燃料元件表面的圆柱表面。它分析了决定燃料元件热破坏的因素。从实验数据分析得出的重要结论之一是关于燃料元件模拟器受热部分中普遍存在的膜层流径流的结论。使用此假设，建立了一个分析模型，该模型可以预测在熔化过程中燃料元素在极限范围内的质量。使用所提出的模型进行计算的结果表明，对于引入正反应性的事故，当功率增加可以达到十个额定值时，有必要对模型进行修改以考虑湍流径流情况。为此，建立了熔体流动的简化模型。与已知技术进行了比较，结果表明，所提出的方法使得以令人满意的精度描述湍流状态成为可能。修改后的模型可以计算出不锈钢熔体在快中子（BN）反应堆燃料元件表面上的运动特征。