DEVELOPMENT OF CONTROL SYSTEM FOR THE FLOW RATE/PASSAGE OF TRITIUM WITH BREMSSTRAHLUNG COUNTING METHOD.

在热核聚变反应堆、重水型反应堆和核燃料后处理的氚过程中，根据氚的浓度来控制氚的流量/通过是必不可少的。特别是对于高水平氚化过程，从安全的角度考虑，研制高精度的氚化控制系统具有重要意义。本文研究了韧致辐射计数法在高水平氚现场测量中的适用性。由于韧致辐射X射线的穿透范围明显大于β射线的穿透范围，因此可以通过韧致辐射计数法直接测量带有适当窗口的容器中的氚量。作为提高韧致辐射计数方法灵敏度的第一步，研究了金蒸发窗口对韧致辐射X射线强度的影响。该窗口对氚的限制和韧致辐射X射线的发射起着重要的作用。通过使用金涂层窗口，可以看到检测限向较低的氚浓度延伸，约为0.1 μ Ci/cm ^3。除了上述的检查，一些初步的实验进行了使用的装置构造，以测试韧致辐射计数方法的控制系统的适用性。结果，从初步试验中可以看出，安装在本装置上的两个控制阀在给定浓度下精确地操作，而与7至54 cm^3/min范围内的流速无关。从这些结果可以看出，可以开发基于韧致辐射计数法的氚控制系统。

For tritium process in thermonuclear fusion reactors as well as a heavy water type reactor and the nuclear fuel reprocessing, it is indispensable to control the flow rate/passage of tritium according to the concentration of tritium. Especially, for the process of high level tritium, the development of precise control system for tritium is of a great importance from viewing point of safety. The applicability of a bremsstrahlung counting method to the insitu measurement of high level tritium has been examined so far. Since the penetration range of bremsstrahlung X-rays is remarkably greater than that of beta-rays, it is possible to measure directly the amount of tritium in a container attached with an appropriate window by the bremsstrahlung counting method. This method, therefore, will be a promising one to control the flow rate/passage of tritium.As a first step, to improve the sensitivity of bremsstrahlung counting method, the effect of a gold evaporated window on the intensity of bremsstrahlung X-rays has been examined. The window plays important roles of the confinement of tritium and the emission of the bremsstrahlung X-rays. By using the gold coating window, it was seen that the detection limit was extended toward lower tritium concentration of about 0.1 muCi/cm^3. In addition to the above examination, some preliminary experiments were carried out using an apparatus constructed to test the applicability of bremsstrahlung counting method to the control system. As a result, it was seen from the preliminary tests that two control valves attached to the present apparatus precisely operated at a given concentration irrespective to the flow rate in the range from 7 to 54 cm^3/min. From those results, it was revealed that it was possible to develop a tritium control system based on the bremsstrahlung counting method.