PWR（U）乏燃料中超铀元素在混合堆快裂变包层内嬗变研究

从中子学角度对ＰＷＲ（Ｕ）乏燃料中的超铀元素（２３８Ｐｕ，２３９Ｐｕ，２４１Ｐｕ，２４１Ａｍ，２４３Ａｍ，２３７Ｎｐ，２４４Ｃｍ）在聚变－裂变混合堆快裂变包层内嬗变的可行性进了研究。利用一维中子输运和燃耗计算程序ＢＩＤＥＣＡＹ译不同燃料组分的四个快裂变包层进行分析计算。结果表明，在聚变－裂变混合堆快裂变包层内安全，高效地嬗变ＰＷＲ（Ｕ）乏燃料中的超铀元素是可能的。     

Project SPHINX spent hot fuel incinerator by neutron flux (the development of a new reactor concept with liquid fuel based on molten fluorides)

The SPHINX project is dealing with a solution of some principle problems of a very promising way of nuclear waste treatment, high level wastes from spent nuclear fuel in particular, by means of transmutation of radionuclides by use of a nuclear reactor with liquid fuel based on molten fluorides, which might be a subcritical system driven by a suitable neutron source. Its superiority lies also in the fact that it makes possible to utilize actinides contained, by others, in spent nuclear fuel and so to reach a positive energy effect.

The SPHINX project has been proposed by the consortium TRANSMUTATION being established by four leading nuclear research bodies in the Czech Republic (Nuclear Research Institute Rez plc, SKODA Nuclear Machinery plc in Pilsen, Nuclear Physics Institute of Academy of Sciences in Rez and Technical University in Praha) at the end of 1996 to which Technical University in Brno (specialized for a secondary circuit problems) has associated in the year 2000. The project has been supported by the Ministry of Industry and Trade of the Czech Republic, CEZ, a.s. (Czech Electricity Generating Company) and RAWRA (Radwaste Repository Authority).

The R&D program of the SPHINX project contains an experimental part, which serves for a verification of design inputs for designing a demonstration unit of a transmuter with liquid fuel based on molten fluorides. The current status of the experimental program performance has been focused upon the irradiation of samples of molten-salt systems as well as structural materials proposed for the blanket of the SPHINX transmuter in the field of high neutron flux of research reactors.

The main aims of this program called Irradiated Probes BLANKA are the following: (1) Experimental verification of long time behavior of transmuter blanket which contains molten fluoride salts as a fuel and coolant, (2) Validation of computational code system being developed for the computation of actinides concentration in long- term operation of the transmuter, and (3) Material research on behavior of materials in neutron and gamma fields, and materials interactions on high temperature conditions.

At present, two agreements on multinational cooperation in this field have been signed: One with European Commission and one with Russian Kurchatov Institute (joint experimental programs AMPULA containing fluorides of transuranium elements like Np, Pu, Am and Cm in irradiated samples and a joint development of the ISTAR code).     

快中子照相样品散射本底及图像特性的Monte Carlo模拟

模拟了14MeV中子在穿透样品后与闪烁体光纤的作用。对每根光纤中的能量沉积进行了计算,并转换成可见光(496nm)光子数在模拟实验中,分析了影响图像质量的因素。首先计算了散射中子本底与闪烁体和样品(聚乙烯)间距的关系。当间距为厘米量级时散射中子本底对图像的影响很小。其次,计算表明系统对样品的甄别厚度与入射中子总数N有关,在一定范围内近似与logN成线性关系。最后,通过模拟结果给出了理想平行中子束入射情况下系统的平面分辨率。     

固体径迹法测量水泥反射体中~(252)Cf中子源反射中子

叙述了水泥反射体中~(252)Cf中子源反射中子测量实验原理。测量了无反射体、有反射体、本底三种状态下中子引发~(235)U产生的裂变率。并根据裂变率得到实验模型下水泥反射体对中子的反射系数。比较了不同中子源相同实验模型水泥反射体对中子的反射系数,对反射系数随角度变化趋势进行了分析。同时,对固体径迹探测技术进行了研究,探索了最佳蚀刻条件,得到火花放电计数随信号膜质量厚度及蚀刻厚度变化趋势。标定了固体径迹火花自动计数器效率,发展了固体径迹探测技术。     

特定实验条件下中子引发~(238)U裂变率测量可行性研究

用小型平板裂变室测量中子穿透实验模型后引发238U绝对裂变率,掌握小空间测量中子技术。通过对有无反射壳测量结果的比较,得到中子对反射壳反射因数。实验结果与MCNP模拟计算结果比较,以此来检验计算方法与参数。