Abstract

This study presents a method that can be used to gain information relevant to determining the corrosion risk for spent nuclear fuel (SNF) canisters during extended dry storage. Currently, it is known that stainless steel canisters are susceptible to chloride-induced stress corrosion cracking (CISCC). However, the rate of CISCC degradation and the likelihood that it could lead to a through-wall crack is unknown. This study uses well-developed computational fluid dynamics and particle-tracking tools and applies them to SNF storage to determine the rate of deposition on canisters. The deposition rate is determined for a vertical canister system and a horizontal canister system, at various decay heat rates with a uniform particle size distribution, ranging from 0.25 to 25 µm, used as an input. In all cases, most of the dust entering the overpack passed through without depositing. Most of what was retained in the overpack was deposited on overpack surfaces (e.g., inlet and outlet vents); only a small fraction was deposited on the canister itself. These results are provided for generalized canister systems with a generalized input; as such, this technical note is intended to demonstrate the technique. This study is a part of an ongoing effort funded by the U.S. Department of Energy, Nuclear Energy Office of Spent Fuel Waste Science and Technology, which is tasked with doing research relevant to developing a sound technical basis for ensuring the safe extended storage and subsequent transport of SNF. This work is being presented to demonstrate a potentially useful technique for SNF canister vendors, utilities, regulators, and stakeholders to utilize and further develop for their own designs and site-specific studies.

摘要

本研究提出了一种方法，该方法可用于获取与确定延长干式储存期间乏核燃料 (SNF) 罐腐蚀风险相关的信息。目前，已知不锈钢罐易受氯化物诱发应力腐蚀开裂（CISCC）的影响。然而，CISCC 退化的速度以及它可能导致穿墙裂缝的可能性是未知的。这项研究使用了成熟的计算流体动力学和粒子跟踪工具，并将它们应用于 SNF 存储以确定罐上的沉积速率。垂直罐系统和水平罐系统的沉积速率是在各种衰变热速率下确定的，具有均匀的粒径分布，范围从 0.25 到 25 µm，用作输入。在所有情况下，进入外包装的大部分灰尘通过而没有沉积。保留在外层包装中的大部分物质沉积在外层包装表面（例如，入口和出口通风口）；只有一小部分沉积在罐本身上。这些结果是为具有广义输入的广义罐系统提供的；因此，本技术说明旨在演示该技术。这项研究是美国能源部乏燃料废物科学与技术核能办公室资助的一项持续努力的一部分，该办公室的任务是开展与开发可靠的技术基础相关的研究，以确保安全的扩展储存和随后的运输的 SNF。这项工作旨在向 SNF 罐供应商、公用事业、监管机构展示一种潜在有用的技术，