UC Berkeley engineers send equipment, expertise to ransacked Chernobyl

加州大学伯克利分校的工程师把设备和专业知识送到了被洗劫的切尔诺贝利

作者:Kara Manke     来源:berkeley     阅读模式:只看译文

After the Russian occupation of the Chernobyl Nuclear Power Plant in Ukraine in spring 2022, many scientists returned to the site to find their work in tatters. Offices and labs had been ransacked. Computers, instrumentation and other valuable equipment had been stolen or destroyed. Radioactive dust had been kicked up by heavy trucks and small fires, spreading additional contamination throughout the area. Today, “There is very little left that is usable,” said Jake Hecla, a graduate student studying nuclear engineering at the University of California, Berkeley. “They’re really starting from the ground up.” To help in the relief effort, nuclear engineers at UC Berkeley are testing and refurbishing critical pieces of equipment to send to their collaborators at Chernobyl, the site of a 1986 nuclear explosion that spread radioactive contamination throughout the region. “I reached out to our main contact over there and basically said, ‘These are the things we have a lot of. Which of these things could you use?’” Hecla said. Dangerous levels of radioactivity still linger at Chernobyl, which is increasingly being spelled Chornobyl to reflect the original Ukrainian name. A few thousand scientists, engineers and workers regularly commute to the remote location in northern Ukraine to monitor the radiation and limit further spread. Even before the current Russian-Ukraine war, these scientists were often forced to rely on old and outdated equipment to perform their work. Since 2017, Hecla and other nuclear engineers at UC Berkeley have been collaborating with Chernobyl scientists, demonstrating state-of-the-art nuclear detection systems to help monitor the radiation at the plant. Now that the Russian invasion has left these scientists without even the most basic tools, the team is also helping out by donating useful equipment. The first batch of instruments — a set of sodium-iodide gamma-ray detectors that are ideal for monitoring lingering radiological contamination in soil and vegetation — shipped late last week. Hecla and fellow nuclear engineering graduate student Michael Bondin are also testing much higher-resolution and valuable high-purity germanium detectors to potentially send to Ukraine. Over the years, UC Berkeley scientists have used these detectors — some of which date back to the 1980s — as part of systems designed to detect radiological threats to national security and to study radiological background signatures in the environment. Now, they will be used to help Chernobyl scientists rebuild their labs. “The war has turned what was a desperate situation into one that is absolutely dire, because the Russian army stole pretty much all of the equipment and computers, and also cross-contaminated portions of the facilities,” said Kai Vetter, professor of nuclear engineering at UC Berkeley. “We believe strongly in providing the expertise and equipment that we have available.” A smoldering threat Thirty-six years after the explosion of Chernobyl’s Unit 4 reactor, the remnants of the meltdown — a highly radioactive mix of uranium, zirconium, graphite and silica — are still smoldering in the basement of the plant. In recent years, neutron counts from this “nuclear lava” have been ticking upward, a sign that the remaining radioactive fuel may be at risk of a runaway reaction that could damage the concrete containment structure around the plant. “There is an enormous need to provide better technology to monitor the nuclear debris, which is still sitting there under Unit 4,” Vetter said. “Even before the war, things seemed to be happening. There were some changes [in the debris], but the measurements were not that reliable because the instrumentation they had was already quite old.” Scientists at the site must also grapple with the ongoing risk that wind or wildfires will kick up radioactive debris and spread the contamination across a wider area. In 2018, Vetter’s team of students at UC Berkeley and scientists at Lawrence Berkeley National Laboratory used a technique called scene data fusion (SDF) — it combines data from nuclear detectors with contextual scene information ­— to create 3D visualizations of the radioactivity at the Chernobyl power plant and in the nearby town of Pripyat. In addition to providing equipment in the wake of the Russian occupation, the team hopes to use this same technique to map how the Russian attack spread radioactive material across the landscape. “Having this kind of technology would be extremely powerful in Chernobyl right now,” Vetter said. The 3D mapping system can be deployed on drones, which means that it could be used to map contamination even in the areas where the Russians have left landmines. And it could also help Chernobyl be better prepared if something happens in the future, like wildfire or even another attack.”

在俄罗斯于2022年春天占领乌克兰的切尔诺贝利核电站后,许多科学家回到现场,发现他们的研究成果已经支离破碎。办公室和实验室被洗劫一空。电脑、仪器和其他贵重设备被盗或被毁。放射性尘埃被重型卡车和小型火灾卷起,向整个地区扩散了更多的污染。
如今,“剩下的可用资源已经所剩无几,”加州大学伯克利分校(University of California, Berkeley)研究核工程的研究生杰克·赫克拉(Jake Hecla)说。“他们真的是从头开始。”
为了帮助救灾工作,加州大学伯克利分校的核工程师们正在测试和翻新关键设备,以便送到切尔诺贝利的合作者那里。1986年,切尔诺贝利发生核爆炸,放射性污染在整个地区扩散。
“我联系了我们在那里的主要联系人,基本上说,‘这些是我们有很多的东西。你可以用哪一种?”Hecla说。
危险的放射性水平仍然存在于切尔诺贝利,它越来越多地被拼成切尔诺贝利,以反映其最初的乌克兰名称。数千名科学家、工程师和工人定期往返于乌克兰北部的偏远地区,监测辐射并限制进一步扩散。即使在目前的俄乌战争之前,这些科学家也经常被迫依靠陈旧过时的设备来完成他们的工作。
自2017年以来,赫克拉和加州大学伯克利分校的其他核工程师一直在与切尔诺贝利的科学家合作,展示最先进的核探测系统,以帮助监测核电站的辐射。由于俄罗斯的入侵,这些科学家甚至连最基本的工具都没有,研究小组也通过捐赠有用的设备来帮助他们。
第一批仪器是一套碘化钠伽马射线探测器,用于监测土壤和植被中残留的放射性污染非常理想。赫克拉和他的核工程研究生迈克尔·邦丁也在测试更高分辨率和有价值的高纯度锗探测器,可能会送往乌克兰。
多年来,加州大学伯克利分校的科学家使用这些探测器-其中一些可以追溯到20世纪80年代-作为旨在检测对国家安全的放射性威胁和研究环境中的放射性背景特征的系统的一部分。现在,它们将被用来帮助切尔诺贝利科学家重建他们的实验室。
加州大学伯克利分校(UC Berkeley)核工程教授凯·维特尔(Kai Vetter)说,“这场战争把一个绝望的局面变成了绝对可怕的局面,因为俄罗斯军队偷走了几乎所有的设备和电脑,还交叉污染了部分设施。”“我们坚信能够提供我们现有的专业知识和设备。”
阴燃的威胁
切尔诺贝利4号反应堆爆炸36年后,熔毁的残留物-铀,锆,石墨和二氧化硅的高放射性混合物-仍在工厂地下室闷烧。近年来,这种 “核熔岩” 的中子计数一直在上升,这表明剩余的放射性燃料可能面临失控反应的风险,这可能会损坏工厂周围的混凝土安全壳结构。
维特说:“急需提供更好的技术来监测仍在4号反应堆下面的核碎片。”“甚至在战争之前,事情似乎就已经发生了。(残骸中)有一些变化,但测量结果不那么可靠,因为他们使用的仪器已经相当老旧了。”
该地点的科学家还必须应对风或野火会引发放射性碎片并将污染扩散到更广泛区域的持续风险。
2018年,维特在加州大学伯克利分校的学生团队和劳伦斯伯克利国家实验室的科学家使用了一种名为场景数据融合(SDF)的技术——它将核探测器的数据与背景场景信息结合起来——创建了切尔诺贝利核电站和附近普里皮亚季镇放射性的3D可视化。
除了在俄罗斯占领之后提供设备外,该团队还希望使用同样的技术来绘制俄罗斯的攻击是如何将放射性物质扩散到整个地形上的。
维特说: “拥有这种技术现在在切尔诺贝利将是非常强大的。”3D绘图系统可以部署在无人机上,这意味着即使在俄罗斯人留下地雷的地区,它也可以用于绘制污染图。如果未来发生野火甚至另一次袭击,这也可以帮助切尔诺贝利做好更好的准备。“