Experimental and numerical study of the dynamics at the fuel rod/spacer grid interface in nuclear reactors******

压水堆(PWR)中发现的流致振动(FIV)会对包括燃料棒在内的关键燃料组件造成微动磨损。燃料棒是由锆合金制成的细长管子，其中含有核燃料，是核裂变产物与外部环境之间的屏障。燃料棒表面的过度磨损可能会打破这一安全屏障，并将裂变产物释放到外部环境中。因此，了解这种微动现象并开发预测严重程度的方法对FIV和法马通加拿大有限公司的微动专家至关重要，因为这有助于他们不仅确保燃料组件的安全和性能，而且还降低制造相同组件的成本。具体来说，微动磨损是由于燃料棒和支承之间的相对运动造成的。目前还没有确定的方法来通过实验测量它们之间的这种相对运动。对这一现象的准确测量将有助于FIV专家验证他们的微动模型，并准确预测微动磨损对燃料组件的影响。**拟议的项目涉及燃料棒在流致振动下的安全性和结构完整性，方法是开发一种创新的测试方法，以跟踪燃料棒表面(接触点)和间隔格栅表面(接触点)的相对位移，以及燃料棒在流致振动期间两个表面之间的净力交换。此外，还将发展一种描述燃料棒-间隔棒网格界面边界条件演化的理论方法，以更好地了解燃料棒在受到流致振动时的动态响应过程中界面条件对结构稳定性的影响。拟议的项目是McGill和Framatome Canada Ltd.(前身为Areva NP Canada Ltd.)之间一系列成功合作的延续。在国家经济、社会和文化权利委员会的资助下，如国家经济、社会和文化权利委员会-EG#462720-14、国家经济合作与发展委员会PLUS#476586-14和国家经济、社会和文化权利委员会-CRDPJ#490978-15。******

Flow-Induced Vibrations (FIV) found in the Pressurized Water Reactors (PWR) cause fretting wear on critical fuel assembly components, including fuel rods. Fuel rods are long slender tubes made of Zirconium alloy which contain the nuclear fuel and act as the barrier between nuclear fission products and the external environment. Excessive wear in the fuel rods' surface could break this safety barrier and release fission products into the external environment. Thus understanding this fretting phenomenon and developing methodologies to predict the severity is of critical importance to FIV and fretting experts at Framatome Canada Ltd. As this helps them to ensure not only the safety and performance of the fuel components but also reduce costs in manufacturing the same. Specifically, the fretting wear is attributed to the relative motion between the fuel rod and the support. There is no established methodology to experimentally measure this relative motion between them. An accurate measurement of this phenomenon would help FIV experts in validating their fretting models and accurately predicting the impact of fretting wear on the fuel components. **The proposed project pertains to the safety and structural integrity of fuel rods subjected to flow-induced vibrations by developing an innovative test methodology to track the relative displacements of the fuel rods surface (point of contact) and the spacer grid surface (point of contact) and the net force exchange between the two surfaces during flow-induced vibrations of the fuel rod. In addition, a theoretical methodology to describe the evolution of the boundary conditions at the fuel rod-spacer grid interface will be developed to better understand the effect of interface conditions on the structural stability of the fuel rod during its dynamic response when subjected to flow-induced vibrations. The proposed project is a continuation of a number of successful collaborations between McGill and Framatome Canada Ltd. (formerly AREVA NP Canada Ltd.) under the NSERC grants such as NSERC-EG#462720-14, NSERCEGplus#476586-14 and NSERC-CRDPJ #490978-15. ******