In 1988, following decades of nuclear safety research (USNRC, 1988a), the United States Nuclear Regulatory Commission (USNRC) in 1988 amended its regulations (USNRC, 1988b) to allow the use of best-estimate evaluation models for the analyses of the loss-of-coolant accident (LOCA) in a light water reactors (LWRs). This was followed by similar action by other national nuclear safety authorities. Until this time, LOCA evaluation models applied a strict set of deterministic rules (see (USNRC, 2000)) that specified conservative models and assumptions to be applied simultaneously. This placed implicit restrictions on plant operations, limiting the nuclear industry’s ability to innovate and apply experience gained for the benefit of their customers. The rule change presented the opportunity for a variety of benefits, from simple procedural and operational flexibility to more significant power uprates.

In response to this regulatory paradigm shift, the nuclear power industry has since advanced the nuclear-thermal-hydraulic systems analysis capability for a broad spectrum of technical issue resolution applications. Today these industry stakeholders include the major nuclear fuel and plant suppliers (e.g., Westinghouse, GEH, Framatome, MHI, etc.), their utility customers, the advanced and small modular reactor (SMR) design organizations, safety and regulatory authorities, industry advocate organizations such the Electrical Power Research Institute (EPRI) and the Nuclear Energy Agency (NEA) of the European Organization for Economic Co-operation and Development (OECD), and dedicated research institutions such as the U.S. DOE and the academic community. To preserve their position on the leading edge, these stakeholders have maintained continuous modeling and simulation development efforts to serve their customers and sponsors.

Of particular note is the ongoing activity in new plant design reviews: both plant suppliers and national safety and regulatory authorities are challenging their analysts to demonstrate greater fidelity and reliability in code prediction of realistic design and safety margins. Research pertaining to this objective has focused on the expanded use of best-estimate-plus-uncertainty (BEPU) analysis methodologies (i.e., beyond LOCA), modern numerical methods, multi-physics/multi-scale component modeling (including computational fluid dynamics), and physics-based risk models. This paper reviews the emergence of BEPU analysis methods, their applications, their adaptations among nuclear states, and the insights revealed from the past two decades of use in the nuclear industry.

1988年，在进行了数十年的核安全研究（USNRC，1988a）之后，美国核监管委员会（USNRC）在1988年对其法规进行了修订（USNRC，1988b），以允许使用最佳估计评估模型来分析损失。轻水反应堆（LWR）的冷却液事故（LOCA）。其他国家核安全当局也采取了类似的行动。在此之前，LOCA评估模型采用了一套严格的确定性规则（请参阅（USNRC，2000年）），该规则指定了要同时应用的保守模型和假设。这对工厂运营施加了隐含的限制，限制了核工业进行创新和应用所获得的经验以使其客户受益的能力。规则变更为您带来了各种好处，

为了应对这种监管范式的转变，核电行业自此提高了用于各种技术问题解决应用的核热工液压系统分析能力。今天，这些行业利益相关者包括主要的核燃料和电厂供应商（例如，Westinghouse，GEH，Framatome，MHI等），其公用事业客户，先进和小型模块化反应堆（SMR）设计组织，安全和监管机构，行业倡导者欧洲经济合作与发展组织（OECD）的电力研究所（EPRI）和核能局（NEA）等组织，以及美国DOE和学术界等专门的研究机构。为了保持自己在前沿的地位，

特别值得注意的是，新工厂设计审查中正在进行的活动：工厂供应商以及国家安全和监管部门都在挑战他们的分析师，以在现实设计和安全裕度的代码预测中展现出更高的保真度和可靠性。与此目标相关的研究集中在扩展使用最佳估计值和不确定度（BEPU）分析方法（即超越LOCA），现代数值方法，多物理场/多尺度组件建模（包括计算流体动力学）以及基于物理的风险模型。本文回顾了BEPU分析方法的出现，其应用，它们在核国家之间的适应性以及过去二十年来在核工业中的使用所揭示的见解。