医用同位素生产堆应急停堆系统设计研究

医用同位素生产反应堆(MIPR)以硝酸铀酰（或硫酸铀酰）水溶液为核燃料，主要生产医用同位素⁹⁹Mo和¹³¹I。反应堆的安全性是需要关注的重要问题。当发生一次冷却水泵故障、误提棒、气回路氢氧复合能力丧失等事故而未能紧急停堆的情况下，由应急停堆系统实现反应堆停堆。本文介绍了应急停堆系统的设计原理及运行方式，并分析了“正压卸料”和“负压卸料”停堆方式应急停堆瞬态过程。结果表明，“正压卸料”应急停堆可在150 s内完成燃料的完全排出；“负压卸料”应急停堆可在700 s内完成燃料的完全排出。“正压卸料”的燃料排出速度比“负压卸料”快，该研究结果可对反应堆临界安全分析提供输入数据。

Emergency Reactor Trip System Design of MIPR

The nuclear fuel of medical isotope production reactor (MIPR) project will make great contribution to reactor technology R & D and application, popularization and application of new technology for the production of radionuclide drugs, development of medical radionuclide industry, and making patients with special diseases especially malignant tumors, to get better diagnosis and treatment with a lower cost. At the same time, it can help the MIPR to carry out the experimental research on the radiation performance of the special and large size shielding material and fill the blank of the country. MIPR is the reactor of uranyl nitrate (or uranyl sulfate) solution. The purpose of MIPR is to produce molybdenum-99 (⁹⁹Mo) and iodine-131 (¹³¹I). And the safety of MIPR is also the very important issue to be considered as other reactor type. Under the condition of primary cooling pump failed, or mis-withdraw rods, or gas loop hydrogen and oxygen recombiner function failed etc., emergency reactor trip system (ERTS) should be action. There are two ERTS action modes: positive pressure mode and negative pressure mode. In this article the emergency reactor trip system design principle of MIPR has been presented, and transient of emergency trip of MIPR has been analyzed on two system action modes. Calculation results show that the fuel can be completely unloaded within 150 s by positive pressure mode for emergency shutdown; and 700 s by negative pressure mode. The positive pressure mode is more advantage. Analysis results of this article can provide the input data for reactor safety analysis.