Geslot B, Vermeeren L, Filliatre P, Lopez A Legrand, Barbot L, Jammes C, Bréaud S, Oriol L, Villard J-F
CEA, DEN, Cadarache, SPEx∕LDCI, F-13108 Saint-Paul-lez-Durance, France.
Rev Sci Instrum. 2011 Mar;82(3):033504. doi: 10.1063/1.3554439.
Flux monitoring is of great interest for experimental studies in material testing reactors. Nowadays, only the thermal neutron flux can be monitored on line, e.g., using fission chambers or self-powered neutron detectors. In the framework of the Joint Instrumentation Laboratory between SCK-CEN and CEA, we have developed a fast neutron detector system (FNDS) capable of measuring on line the local high-energy neutron flux in fission reactor core and reflector locations. FNDS is based on fission chambers measurements in Campbelling mode. The system consists of two detectors, one detector being mainly sensitive to fast neutrons and the other one to thermal neutrons. On line data processing uses the CEA depletion code DARWIN in order to disentangle fast and thermal neutrons components, taking into account the isotopic evolution of the fissile deposit. The first results of FNDS experimental test in the BR2 reactor are presented in this paper. Several fission chambers have been irradiated up to a fluence of about 7 × 10(20) n∕cm(2). A good agreement (less than 10% discrepancy) was observed between FNDS fast flux estimation and reference flux measurement.
通量监测对于材料试验反应堆的实验研究具有重要意义。如今，只能在线监测热中子通量，例如使用裂变室或自给能中子探测器。在比利时核能研究中心（SCK-CEN）与法国原子能委员会（CEA）联合仪器实验室的框架下，我们开发了一种快速中子探测器系统（FNDS），能够在线测量裂变反应堆堆芯和反射层位置的局部高能中子通量。FNDS基于坎贝尔模式下的裂变室测量。该系统由两个探测器组成，一个探测器主要对快中子敏感，另一个对热中子敏感。在线数据处理使用CEA的燃耗代码DARWIN，以便在考虑裂变产物同位素演化的情况下，区分快中子和热中子成分。本文介绍了FNDS在BR2反应堆中的首次实验测试结果。几个裂变室已被辐照至约7×10²⁰ n∕cm²的注量。在FNDS快中子通量估计值与参考通量测量值之间观察到良好的一致性（差异小于10%）。
