Abstract

Post Fukushima the U.S. Nuclear Regulatory Commission issued an Order on Spent Fuel Instrumentation (EA-12-051) requiring all U.S. nuclear plants to install spent fuel pool (SFP) water level monitoring instrumentation and ensure the instrument would remain functional following a safe shutdown earthquake (SSE). The structural integrity analysis requires an assessment of the hydrodynamic loads and wave impact forces that the instrument is subjected to during an SSE. Modeling and simulation of the SFP response to an SSE can provide this type of information if the simulation tool is able to capture the important physical phenomena, such as seismic acceleration, surface wave formation, fluid velocities, and multidimensional effects. This paper describes the capabilities of GOTHIC^TM that can be used to simulate the sloshing surface waves and subsurface fluid motion of an SFP in response to an earthquake.

GOTHIC is a versatile, general-purpose, thermal-hydraulic software package for multiphase flow that is a hybrid between traditional system thermal-hydraulic and computational fluid dynamics codes. It includes a transient, variable body force capability to simulate multi-axis acceleration, and is therefore applicable to seismic events; movement experienced on ships, airplanes, or spacecraft; and other events with system acceleration. Also, since the gravitational constant can be adjusted, GOTHIC can model systems placed outside the Earth’s atmosphere (e.g., spacecraft, space station, the Moon, or other extraterrestrial bodies). The variable body force capability makes GOTHIC well suited to model the hydrodynamic response of an SFP to a seismic event.

This paper describes the governing equations that are solved by GOTHIC as they pertain to accelerating systems. A series of benchmarks covering a range of experiments for surface wave dynamics, acceleration-induced motion, and other important phenomena are presented to demonstrate the verification and validation of GOTHIC for these types of applications. Finally, results from a sample application of GOTHIC for SFP hydrodynamic response are presented that provide the necessary inputs for a structural integrity analysis.

摘要

福岛核事故后，美国核管理委员会发布了关于乏燃料仪表的命令 (EA-12-051)，要求所有美国核电厂安装乏燃料池 (SFP) 水位监测仪表，并确保该仪表在安全停工地震后仍能正常工作（上海证券交易所）。结构完整性分析需要对仪器在 SSE 期间承受的流体动力载荷和波浪冲击力进行评估。如果模拟工具能够捕获重要的物理现象，例如地震加速度、表面波形成、流体速度和多维效应，则 SFP 对 SSE 响应的建模和模拟可以提供此类信息。本文描述了 GOTHIC ^TM的功能可用于模拟 SFP 响应地震的晃动表面波和地下流体运动。

GOTHIC 是一种用于多相流的多功能、通用的热工水力软件包，它是传统系统热工水力和计算流体动力学代码的混合体。它包括模拟多轴加速度的瞬态、可变体力能力，因此适用于地震事件；在轮船、飞机或航天器上经历的运动；和其他具有系统加速功能的事件。此外，由于可以调整引力常数，GOTHIC 可以模拟放置在地球大气层之外的系统（例如，航天器、空间站、月球或其他地外天体）。可变体力能力使 GOTHIC 非常适合模拟 SFP 对地震事件的流体动力学响应。

本文描述了由 GOTHIC 求解的控制方程，因为它们与加速系统有关。一系列基准测试涵盖了表面波动力学、加速度引起的运动和其他重要现象的一系列实验，以证明 GOTHIC 在这些类型的应用中的验证和验证。最后，介绍了 SFP 水动力响应的 GOTHIC 示例应用结果，为结构完整性分析提供了必要的输入。