微型反应堆卸料装置设计及可靠性分析

微型反应堆（简称“微堆”）低浓化及退役都包含乏燃料卸出的操作，而保证乏燃料安全卸出的关键设备之一就是卸料装置。现有的卸料装置在操作过程中会破坏微堆堆筒体密封性，并且无法恢复，但微堆低浓化后还需利用原有堆筒体进行装料运行，所以本文在此需求的基础上设计了一套新型的卸料装置，可在不分离筒节、不破坏筒体完整性及密封性的前提下完成卸料操作。新设计的卸料装置包含卸料操作工具和辅助机械装置两部分。卸料操作工具通过小盖开口即可实现燃料组件的抓取，实施吊装。卸出的微堆乏燃料具有很高的放射性，卸料操作工具配合辅助机械装置，可实现远距离起升平移的操作，这种设计便于屏蔽，同时可有效降低工作人员所受辐射剂量。对该卸料装置进行计算和可靠性分析，结果表明其强度远大于实际使用载荷，安全可靠，能较好地满足微堆使用需求。新型微堆卸料装置具有经济性好、易制备、易操作的特点，下一步将在国内外微堆低浓化卸料或退役中推广应用。

Structure Design and Reliability Analysis of Unloading Device for Miniature Neutron Source Reactor

Miniature Neutron Source Reactor (MNSR) low enriched uranium (LEU) conversion and decommissioning include the unloading operation of discharging spent fuel, and unloading device is one of the key equipment to ensure operation safety. When the existing unloading device is used, the sealing performance and tightness of MNSR reactor vessel will be destroyed and can’t be restored. However, it is necessary to use the original reactor vessel to recover the reactor normal operation after LEU conversion. On the basis of LEU conversion requirements, the new unloading device was designed, which could be used in the unloading operation without separating reactor vessel and destroying the sealing performance and tightness. The new unloading device consists of unloading operating tools and auxiliary mechanical device. The unloading operating tools can be used to grab the fuel assembly only through the small cover opening of reactor vessel top plate. The auxiliary mechanical device can be used with unloading operating tools to realize operation in a long distance by lifting and level motion. The calculation and analysis results show that the structure strength of unloading device is much larger than the actual load to ensure operation safety and reliability. The unloading device is reasonable and reliable, and can be used in the practical operation of MNSR LEU conversion or decommissioning at home and abroad.