氢计钠回路冷阱净化系统设计和调试

The Design and Commissioning of Cold Trap Purifying System of Hydrogen Meter Sodium Loop

液态金属钠冷快堆电站蒸汽发生器的钠泄漏会导致钠水反应和氢的产生。因此,钠中微量氢的探测是判断蒸汽发生器中是否存在钠泄漏的重要手段,是确保快堆电站安全运行的关键问题之一。清华大学液态金属技术研究室建立了服务于钠中微量氢探测的氢计钠回路。为了准确测量微氢含量,需要确保回路中钠的纯度,尤其是氢的含量应加以严格控制。在氢计钠回路中,利用钠温降低后,钠中杂质含量降低的原理,达到去除钠中杂质的目的。 本文给出了氢计钠回路冷阱净化系统的设计特点和参数,并讨论了它的调试结果。 为了调节流量的方便,冷阱净化系统布置在电磁泵的出口。它由回热器和冷阱组成。回热器位于冷阱的上部。主回路的高温钠流过回热器后,在冷阱的入口,钠温降至180℃,进入冷阱后,钠从两侧进入净化区,到达底部时,其温度降至110℃。冷阱选用空气冷却。经回热器的作用,净化后的钠温升至与主回路钠温相近。然后,回到电磁泵入口。 根据调试结果,通过降低冷阱流量及主回路钠温或者增加冷却空气流量及切除冷阱预热电源,冷阱钠温可以降至要求的110℃。作者认为,后者更符合设计规定和氢计实验的需要,而且能满足核电站运行的要求。

The sodium leak in the steam generator of LMFBR Nuclear Power Plant can result in Sodium-Water reaction and production of hydrogen. So, detecting the micro-hydrogen is an important judgement method for sodium leak in the steam generator, and one of the key problem for ensureing operating safety to the power plant. The hydrogen meter sodium loop built by the research laboratory of liquid metel technology in Tsinghua Unirersity is giving service for detecting the micro-hydrogen in sodium. To detect the micro-hydrogen exactly, we must ensure the prity of the sodium in the loop, especially the hydrogen content must be controled strictly. In order to get the impurity in sodium away, we apply the principle to the hydrogen-meter sodium loop that the lower the sodium temperature, the lower the impurity content in sodium is.The paper reports the design feature and parameters of cold trap purifying system of hydrogen meter sodium loop, and disscusses its commissioning results.In order to adjust the flow easily, the cold trap purifying system is arranged in the exit of the electromagnetic pump. It is composed of regenerator and the cold trap. The regenerator is above the cold trap. The high temperature sodium in the main-loop flows through the regenerator, in the entrance of the cold trap, its temperature is reduced to 180℃. After entering the cold trap, the sodium flows to the purifying region by side, when it arrives the bottom of the trap, its temperature is reduced to 110℃. The cold trap is cooled by air. The temperature of the Clean sodium rises nearby the main-loop's by the regenerator, and then it returns to the extrance of the electromagnetic pump. Acorrding to the commissioning results, the sodium's temperature of the cold trap could be reduced to 110℃ by reducing the flow of the cold trap purifying system and the temperature of the main-loop, or increasing the air flow and cuting off the power supply of its heating. The authores think that the latter is more conformable with the design stipulation and with the requirment of the hydrogen meter experiment, and it can meet the requirments of the operation of the Nuclear Power Plant.