核电取水通道前端海冰动力聚集及堵塞机制研究

The first nuclear power engineering in ice-covered area of China is enduring the sea ice risk to nuclear cooling resource. Because of the missing of design standards and management technology for ice prevention, the research on mechanism of sea ice risk to water intake should be conducted as soon as possible. Based on the mechanics property and space-time distribution characteristic sea ice of China, sea ice dynamic accumulation is the potential reason for intake channel blocking, which has not yet any related research. Based on the research on broken ice clearing and pilling up, this proposal research is on the mechanism for sea ice dynamic accumulation and morphology model for blocking ice in the front of water intake channel of nuclear power plant. The discrete simulate methods of motion-crushing on level ice, brash ice, ice ridge will be estimated composed by ice elements. Three form of sea ice dynamic accumulation were demonstrated and simulated, which are large block ice jamming, local ice pilling up, floating ice diving. The calculated formula for blocking ice was formed based on the analysis of main impact factors for sea ice dynamic accumulation process. This research will benefit for understanding the mechanism of sea ice failure and broken ice motion, and will be the technical support for reasonable design and safety operation of nuclear power cooling resource in ice covered area.

首次应用我国北方有冰海域的核电工程正面临着冷源安全海冰灾害风险的新问题，相关防冰设计标准和冰期管理技术普遍缺失，亟待开展冷源取水工程海冰灾害机理研究。根据我国海冰的材料力学性质和时空分布特征，海冰动力聚集是可能造成取水通道堵塞的主要原因，且国内外针对该问题的研究尚未开展。为此，本项目在申请人主持前一项自然科学基金项目有关破碎冰动力清除与堆积行为的研究基础之上，开展核电取水通道前海冰动力聚集过程和堵塞冰体形态表征研究。建立基于冰块元集合体的平整冰、碎冰、冰脊运移-破碎过程的离散元模拟方法；阐明取水通道前大冰块堵塞、局部冰堆积、浮冰块下潜等三种海冰聚集形式，开展冰块体接触-聚集物理过程模拟；分析堵塞冰体生长的影响因素，建立堵塞冰体形态发展的表征方法。本项目研究有助于更准确揭示工程条件下海冰破碎和碎冰运动机制，还可为冰区核电冷源工程的合理设计和冬季安全运行提供有力的科学依据。

近年核电工程开始逐步成为我国北方海域的新兴支柱产业，但因冷源取水工程的防冰设计标准和冰期管理技术缺失，使得核电冷源安全的未知风险迅速暴露，急切需要开展相应的海冰灾害机理研究。受地理位置和环境因素影响，海冰动力聚集是我国北方滨海核电取水通道堵塞的可能原因，但国内外针对该问题的研究尚未开展。本项目开展核电取水通道前海冰动力聚集过程和堵塞冰体形态表征研究。利用扩展圆盘单元模型和平行粘结模型，建立基于冰块元集合体的平整冰、碎冰、冰脊运移-破碎过程的离散元模拟方法；阐明取水通道前大冰块堵塞、局部冰堆积、浮冰块下潜等三种海冰聚集形式，开展冰块体接触-聚集物理过程模拟；分析堵塞冰体生长的影响因素，重点分析海冰密集度、海冰速度和碎冰平均尺寸对取水口碎冰堆积发生发展的影响；建立堵塞冰体形态的数学模型，确立基于模型算法的取水口海冰动力堆积风险评估技术流程，以取水通道口被堆积冰堵塞程度为评估指标进行风险级别划分，分析推算出所对应的海冰危险性指标阈值。.本项目研究揭示工程条件下海冰破碎和碎冰运动机制，是核电海冰灾害理论的重要组成部分，填补了我国冰区核电冷源安全海冰灾害风险理论的空白，是传统工程海冰学科的有益补充。同时，项目研究成果为冰区核电冷源工程的合理设计和冬季安全运行提供有力的科学依据已经应用于核电冷源海冰风险预警应急工作，在我国第一座也是目前唯一一座正在运行的冰区核电工程——红沿河核电工程的冬季海冰监测预警保障工作中发挥了重要作用。根据我国核电中长期发展规划，核电工程将逐渐成为我国北方海域的新兴支柱产业，在建和拟建的冰区核电工程将在不同程度上将本项目成果作为技术依据，进而为保冰区核电海域环境监测和风险防范提供成功经验。