论文标题
中子噪声分析中的逆不确定性定量的多输出高斯过程
Multi-output Gaussian processes for inverse uncertainty quantification in neutron noise analysis
论文作者
论文摘要
在裂变材料中,通过诱导的裂变出生的中子的固有多样性导致其检测统计数据的相关性。中子之间的相关性可用于追溯裂变材料的某些特征。这种称为中子噪声分析的技术在核保障或废物识别中应用。它为未知的裂变材料提供了一种非破坏性检查方法。这是一个逆问题的一个例子,其中从对后果的观察中推断出原因。但是,由于基础过程的随机性,中子相关测量通常是嘈杂的。这使得逆问题的分辨率更加复杂,因为测量很大程度上取决于材料特征。材料属性的微小变化会导致非常不同的输出。这种反问题据说是不适合的。对于错误的反问题,逆不确定性定量至关重要。实际上,数据中看似低的噪声可能会导致材料特性估计的强烈不确定性。此外,通常用于描述中子相关性的分析框架依赖于强烈的物理假设,因此固有地存在偏见。本文解决了双重目标。首先,替代模型用于改善中子相关预测并量化这些预测的错误。然后,进行逆不确定性定量,以包括测量误差以及残留模型偏置的影响。
In a fissile material, the inherent multiplicity of neutrons born through induced fissions leads to correlations in their detection statistics. The correlations between neutrons can be used to trace back some characteristics of the fissile material. This technique known as neutron noise analysis has applications in nuclear safeguards or waste identification. It provides a non-destructive examination method for an unknown fissile material. This is an example of an inverse problem where the cause is inferred from observations of the consequences. However, neutron correlation measurements are often noisy because of the stochastic nature of the underlying processes. This makes the resolution of the inverse problem more complex since the measurements are strongly dependent on the material characteristics. A minor change in the material properties can lead to very different outputs. Such an inverse problem is said to be ill-posed. For an ill-posed inverse problem the inverse uncertainty quantification is crucial. Indeed, seemingly low noise in the data can lead to strong uncertainties in the estimation of the material properties. Moreover, the analytical framework commonly used to describe neutron correlations relies on strong physical assumptions and is thus inherently biased. This paper addresses dual goals. Firstly, surrogate models are used to improve neutron correlations predictions and quantify the errors on those predictions. Then, the inverse uncertainty quantification is performed to include the impact of measurement error alongside the residual model bias.