Determination of Neutron Fluxes and Spectrum Shaping Factors in Irradiation Sites of Ghana’S Miniature Neutron Source Reactor (mnsr) by Activation Method After Compensation of Loss of Excess Reactivty
Determination of Neutron Fluxes and Spectrum Shaping Factors in Irradiation Sites of Ghana’S Miniature Neutron Source Reactor (mnsr) by Activation Method After Compensation of Loss of Excess Reactivty
复制标题
补偿过量反应性损失后激活法测定加纳微型中子源反应堆（mnsr）辐照场中子通量和能谱整形因子
DOI：
10.4236/wjnst.2011.12009
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
R. Abrefah
中科院分区：
文献类型：
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作者：
Robert Bright Mawuko Sogbadji;B. Nyarko;E. Akaho;R. Abrefah
研究堆辐照孔道中子注量率的准确测量是保证其正常使用的关键。加纳研究堆-1（GHARR-1）的总中子通量是在其填隙片上添加铍反射体以补偿过量反应性损失后测量的。用箔活化法测定了热中子、超热中子和快中子通量。在加纳研究堆-1设施辐照场的各向同性中子场中，对有和无厚度为1 mm的镉盖的实验样品进行了辐照。样品中的诱导活性通过具有高纯锗检测器的γ射线光谱法测量。在实验分析中考虑了γ衰减、热中子和共振中子自屏蔽效应的必要修正。在镉的截止能量为0.55eV的条件下，以3 kW的功率辐照可忽略厚度的Al-0.1% Au线，测定了外通道7和内通道2的中子通量，其中子整形因子α分别为（0.037 ± 0.001）和（-0.961 ± 0.034）。发现内辐照部位2处的中子通量比为，（25.308 ± 3.201）热-超热中子通量，（0.179 ± 0.021）为超热到快中子通量，（4.528 ± 0.524）对于热中子到快中子通量，在外部辐照部位7中，发现中子通量比为，（40.865 ± 3.622）、（0.286 ± 0.025）和（11.680 ± 1.030）。
Accurate neutron flux values in irradiation channels of research reactors are very essential to their usage. The total neutron flux of the Ghana Research Reactor-1(GHARR-1) was measured after a beryllium reflector was added to its shim to compensate for excess reactivity loss. The thermal, epithermal and fast neutron fluxes were determined by the method of foil activation. The experimental samples with and without a cadmium cover of 1-mm thickness were irradiated in the isotropic neutron field of the irradiation sites of Ghana Research Reactor-1 facility. The induced activities in the sample were measured by gamma ray spectrometry with a high purity germanium detector. The necessary correction for gamma attenuation, thermal neutrons and resonance neutron self-shielding effects were taken into account during the experimental analysis. By defining cadmium cutoff energy of 0.55eV, Al-0.1% Au wires of negligible thickness were irradiated at 3kW to determine the neutron fluxes of two irradiation channels, outer channel 7 and inner channel 2 whose Neutron Shaping Factor (α) were found to be (0.037 ± 0.001) and (–0.961 ± 0.034). The neutron flux ratios at the inner irradiation site 2 were found to be, (25.308 ± 3.201) for thermal to epithermal neutrons flux, (0.179 ± 0.021) for epithermal to fast neutrons flux and (4.528 ± 0.524) for thermal to fast neutrons flux, in the outer irradiation site 7, the neutron flux ratios were found to be, (40.865 ± 3.622) for thermal to epithermal neutrons flux, (0.286 ± 0.025) for epithermal to fast neutrons flux and (11.680 ± 1.030) for thermal to fast neutrons flux.