research on direct measurement of time series and spatial distribution of reactor noises for criticality safety

长期以来，反应堆噪声信号被用于表征反应堆和/或关键组件中的中子场参数。确定噪声信号时间相关性的方法有很多，如费曼- α法、罗西- α功率谱法等。这些程序是用一些模块型硬件来实现的，例如多通道标度器（MCS）、所谓的时间分析仪、快速傅立叶变压器以及特殊的解析公式。在本工作中，实现了探测器信号到达时间的直接读取，并尝试了进一步的应用。从本质上讲，电抗器噪声的信息包含在所用探测器发出的信号的时间序列中，它们的直接测量应能提供所需的全部数据。直接读取探测器信号到达时间的方法一般是用录音机（ATR），有时也尝试应用于反应堆噪声测量。ATR方法虽然简单实用，但数据没有进行在线处理，多秒区死区特征不明确，一般没有建立增加输入次数的技术。特别是，最近的需求是快速在线数据采集的可能性。研制了一套微机直接时序数据采集测试系统，并应用于中子场参数的测量。为了直接读取计算机存储器地址中信号的到达时间，在微机的接口上安装了控制电路，它由门电路、时钟电路和寄存器电路组成。经过几次工作，最终设计的电路完成了。该电路读取每个事件信号，并使用0.5MHz时钟附加到达时间。在kHz计数条件下，它的死区时间性能约为1mus。输入的数量增加到4个，然后可以进行多次互相关测量。该系统已在九州大学的亚临界装置、近畿大学反应堆和动力反应堆和核燃料开发公司的临界装置（DCA）上进行了多次试验。最后，完成了直接时间序列数据采集技术，从探测器采集的一个时间序列数据中获得了费曼- α、罗西- α和功率谱分析的在线数据，建立了不需要特殊硬件对中子场信号进行直接时间序列测量的概念。少

The reactor noise signal is long used to characterize neutron field parameters in reactors and/or critical assemblys. There are many procedures to determine the time correlation of noise signals, as methods of Feynman-alpha, Rossi-alpha power spectrum and so on. These procedures are rearized with some module-type hardwares, for example, multi-channel scaler (MCS), so-called time analyzers, fast Fourier transformers, with special analytical formula.In the present work, direct reading of the arriving time of detector signals is realized and further applications are tried. Intrinsically, the information of the reactor noise is included in the time-series of the signal from the used detector and their direct measurement should provide all the required data. Direct reading of the arriving time of detector signal has been performed generally by audio tape recorder (ATR) and applications to reactor noise measurements are sometimes tried. Although the ATR method is simmple and useful, the data … More treatment is not of on-line, the dead-time characteristics is not clear in mu second region and technique of increasing the number of input is not established in general. Especially, recent requirement is possibility of fast on-line data accuisition.Authors have developed a test system to realize the direct time-series data accusition with a microcomputer and the designed system has been appllied to measure neutron field parameters. To read directly the arriving time of the signal in a memory address of a computer, a control circuit is installed in the interface of a micro-computer, which consists of gate, clock and registration circuits.After several works, a finaly designed circuit is completed. This circuit reads each event signal with attaching the arriving time using a 0.5MHz clock. It has dead-time performance of about 1mus under kHz counting condition. The number of input is increased to four and then several cross-correlation measurement become possible. This system has been tested several times at the sub-critical assembly of Kyushu University, the Kinki University Reacter and the critical assembly(DCA) of Power Reactor and Nuclear Fuel Development Corporation. Finaly, technique of the direct time-series data accuisition is accomplished, and on-line data of Feynman-alpha, Rossi-alpha, and power spectrum analyses are obtained from one time-series data from a detector and the concept of direct time-series measurement of signal from a neutron field without any special hardware is established. Less