Irradiation Effects on Flow Localisation in Zirconium Alloys

这个项目的重点是能源，更具体地说是核裂变。从核反应堆开启的那一刻起，燃料组件等核心材料就会受到辐射。中子对材料的轰击会产生碰撞级联，从而立即在材料中产生点缺陷和位错。这导致材料性能与未辐照材料相比发生了非常显著的变化。用于轻水反应堆的核燃料由所谓的包层管组成，包层管由锆合金制成，具有优异的耐腐蚀性、足够的机械性能和低的中子吸收系数。核燃料最初用5%的235U进行浓缩。然而，由于包层材料降解和燃料组件尺寸不稳定的不确定性，燃料不能完全燃烧。核燃料组件的安全运行需要完全了解辐照材料的机械性能。例如，当塑性应变时，辐照材料表现出严重的流动局部化，在锆材的情况下，也会从柱状滑移转变为基面滑移。因此，我们需要详细了解导致这些现象的机制，以及它们如何受到材料化学和辐射过程中微结构演变的影响。在20世纪60年代和70年代，包括英国在内的许多国家都有试验反应堆，允许科学家对辐射材料进行研究。然而，这些测试反应堆中的大多数现在已经消失，英国或其他国家不太可能建造许多新的测试反应堆。出于这个原因，各国政府投资了质子/离子加速器来模拟中子辐射。这种设施的优点是，它们的运行成本比测试反应堆低许多个数量级。然而，我们对中子引起的损伤与质子/离子引起的损伤之间的关系的了解是有限的。由于锆合金在受到中子照射时具有相对温和的活性，它们也是校准质子/离子对抗中子辐射的理想材料。这项研究将由英国和印度合作进行，目的是培训印度研究人员进行先进的电子背散射衍射(EBSD)和同步加速器X射线衍射实验。中子辐照材料将由印度孟买的TIFR/BARC设施提供，而离子辐照将在英国的新道尔顿坎布里亚设施进行。

This project focuses on energy and more specifically on nuclear fission. Core material such as fuel assemblies are exposed to irradiation from the moment a nuclear reactor is switched on. The bombardment of material with neutrons creates collision cascades that immediately produce point defects and dislocations in the material. This results in very significant changes of the material properties compared to non-irradiated material.Nuclear fuel for light water reactors is contained by so-called cladding tubes, which are made from zirconium alloys because of their excellent corrosion resistance, sufficient mechanical properties and their low neutron absorption coefficient. Nuclear fuel is enriched initially with 5% 235U. However, the fuel cannot be fully burned due to the uncertainty of clad material degradation and dimensional instability of fuel assemblies. The safe operation of nuclear fuel assemblies requires a complete understanding of the mechanical properties of irradiated material. For instance, when strained plastically, irradiated materials display severe flow localisation and in the case of zirconium also a change from prismatic to basal slip. Consequently, we need to develop a detailed understanding of the mechanisms leading to these phenomena and how they are affected by material chemistry and the microstructure evolution during irradiation.During the 1960s and 70s many countries including the UK had test reactors that allowed scientists to undertake research on irradiated material. However, most of these test reactors are gone now and it is unlikely that the UK or other countries will build many new test reactors. For this reason, governments have invested in proton/ion accelerators to simulate neutron irradiation. The advantage of such facilities is that they are by many order of magnitudes cheaper to run than a test reactor. However, our understanding of how well neutron induced damage is related to proton/ion induced damage is limited. Since Zr alloys are relatively mildly active when irradiated by neutrons, they represent also an ideal material to calibrate proton/ion against neutron irradiation.The research will be undertaken in a collaborative effort between the UK and India with the aim to train Indian researchers to undertake advanced electron back scatter diffraction (EBSD) and synchrotron x-ray diffraction experiments. Neutron irradiated material will be provided by the TIFR/BARC facility, Mumbai, India while ion irradiation will be carried out at the new Dalton Cumbria Facility in the UK.