The prevailing state of knowledge of two-phase flow in complex systems, as in the nuclear field, usually leads a certain degree of ad hoc calibration of computational models and the consequent inevitable subjectivity in analyses and assessments. The UPC-ANT Uncertainty Analysis methodology for code assessment attempts to maintain scientifically desired features of models and analyses, by crediting BEPU analysis and centering the assessment criteria on T-H phenomenology rather than on safety criteria, as it is the usual practice. An SB-LOCA in the upper head is utilized as a case study, and global, chronological, FOMs and phenomenological analyses are carried out and illustrated briefly. Overall, it was concluded that the developed RELAP5 model reproduces all the relevant T-H phenomena to the investigated scenario, either partially or totally, and the BEPU methodology is generally adequate to perturb the underlying T-H phenomena.

复杂系统（如核领域）中两相流的普遍知识状态通常会导致计算模型的一定程度的临时校准以及随之而来的分析和评估中不可避免的主观性。用于代码评估的 UPC-ANT 不确定性分析方法试图保持模型和分析的科学所需特征，方法是将 BEPU 分析归功于并以 TH 现象学而不是安全标准为中心的评估标准，因为这是通常的做法。上头部的 SB-LOCA 被用作案例研究，并进行了全局、时间顺序、FOM 和现象学分析，并进行了简要说明。总体而言，得出的结论是，开发的 RELAP5 模型部分或全部重现了所有与调查场景相关的 TH 现象，