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

对于热核聚变反应堆和重水型反应堆的氚过程以及核燃料后处理来说，根据氚的浓度来控制氚的流速/通过是必不可少的。特别是对于高含量氚工艺，从安全角度考虑，研制精确的氚控制系统具有重要意义。迄今为止，对轫致辐射计数法在高水平氚原位测量中的适用性进行了研究。由于轫致辐射x射线的穿透范围明显大于β射线，因此可以用轫致辐射计数法直接测量带有适当窗口的容器中的氚量。因此，这种方法将是一种很有前途的控制氚的流速/通过的方法。为了提高轫致辐射计数方法的灵敏度，研究了金蒸发窗对轫致辐射x射线强度的影响。窗口对氚的约束和轫致辐射x射线的发射起着重要的作用。利用金涂层窗口，可将检测限向氚浓度约0.1 μ i/cm^3的低浓度方向扩展。除上述试验外，还利用自制的装置进行了初步试验，以检验韧致辐射计数法对控制系统的适用性。结果，从初步试验中可以看出，连接在本装置上的两个控制阀在给定浓度下精确地工作，而不管流量在7至54 cm^3/min范围内。这些结果表明，基于轫致辐射计数方法开发氚控制系统是可能的。

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.