Digital fast neutron assay of uranium

众所周知，铀有一种特殊的性质，即当以特定的排列和浓度配置时，它可以维持核链式反应，从中可以获得大量的能量。正是这种特性使它在世界各地被专门用作核反应堆的燃料。然而，也许不太容易理解的是，在用于反应堆之前的原始、未辐照状态下，铀在放射性意义上是相当良性的，释放出相对较少的辐射，可以用于表征。这一点极为重要，因为虽然在反应堆中使用铀为和平用途提供了大量电力，但必须对现有铀的数量进行量化和记录，以便发现将其转用于非法用途的情况。这一活动的一个重要要求往往是能够在不接触铀的情况下远程探测和评估铀的数量，以便与生产反应堆燃料等有关的商业活动能够不受阻碍地继续进行，并使评估迅速有效。用于此目的的现有检测介质是氦气的同位素3 He，其现在供应短缺并且非常昂贵，其依赖于慢中子的检测。在这个项目中，我们打算探索使用快中子与不同的探测器技术，有机稀释器，用于评估高浓缩铀235和铀233的铀化合物。为了进行这项研究，我们必须将我们的设备和专业知识运送到美国田纳西州的橡树岭国家实验室，因为这个实验室是世界上唯一一个既能获得这些材料，又能在评估中拥有世界领先的专业知识的地方。这一旅行申请特别值得注意的是，它将使人们能够接触到铀-235的浓缩水平，这在其他任何地方都是不可能的，再加上联合王国的ADRIANA探测器系统，该系统也是世界上独一无二的。此外，它还将使铀-233的探测量在其他任何地方都是不可能的，这对探索与钍核燃料循环有关的材料安全至关重要。

It is well known that uranium has a special property whereby when configured in a particular arrangement and concentration it can sustain a nuclear chain reaction from which a great deal of energy can be derived. It is this property that has led it to be used exclusively throughout the world as the fuel for nuclear power reactors. However, perhaps less well appreciated is the fact that in its raw, un-irradiated state prior to use in a reactor uranium is quite benign in a radioactive sense, emitting relatively little radiation that can be of use in terms of characterisation. This is extremely important because whilst its use in reactors provides much electricity for peaceful uses, it is essential that the amount of uranium in existence is quantified and recorded so that diversion of it for illicit uses is detected. Often an important requirement of this activity is to be able to detect and assess quantities of uranium remotely, without touching it so that commercial activities associated with the production of fuel for reactors etc. can continue unhindered and so that the assessment is quick and effective. The existing detection medium for this purpose is an isotope of helium gas, 3He, which is now in short supply and very expensive which relies on the detection of slow neutrons. In this project we intend to explore the use of fast neutrons with a different detector technology, organic scintillators, for the assessment of uranium compounds that are highly enriched in 235U and 233U. To carry out this research it is essential that we transport our equipment and expertise to the Oak Ridge National Laboratory in Tennessee in the United States because this laboratory is one of the only places in the world that combines access to these materials with resident world-leading expertise in their assessment. Of particular note to this travel request is that it will enable access to enriched levels of 235U not possible anywhere else combined with the UK's ADRIANA detector system that is also unique in the world. Further it will enable 233U to be explored in quantities not possible anywhere else that is essential to exploring materials security associated with the thorium nuclear fuel cycle.