The splitting of the atom is arguably one of humanity’s greatest technological achievements. The atom was long thought to be the smallest possible unit of matter, its name deriving from the ancient Greek for "uncuttable." Then, in the early 20th century, scientists found a way to divide large atoms by bombarding them with wayward neutrons, releasing a colossal amount of energy. Not only can this process generate large amounts of heat and power, but it can do so without emitting climate-warming gases.
不幸的是，几乎一旦实现这一突破，就被滥用了。起初，它被故意滥用，作为一种暴力手段。今年夏天标志着美国轰炸广岛和长崎的75周年，日本造成了100,000至20万人。这是军事冲突中唯一使用原子武器，但原子弹的幽灵有史以来，特别是在冷战期间迫在眉睫。
Nuclear technology also has been misused unintentionally, due to negligence and poor design. Accidents such as Chernobyl, Three Mile Island and Fukushima have raised doubts about nuclear’s potential as a clean and reliable power source.
There’s no denying real and grave risks when things go wrong with nuclear power. That may be why nuclear engineering has faltered in the U.S. over the past few decades. Nuclear provides20 percentof the U.S. electricity supply, but the country has只建成一个21世纪商业上运营的核反应堆。在全球范围内，核工业预计将经历复合年增长率，平价2.5％（中国）至2.8％（德国）。
但是，新一代核技术可以改变前景。其支持者试图解决过去的缺陷，并为未来履行新的愿景，其中希望将核裂变为丰富，低碳能源。
"It’s a little bit like how cars or airplanes now are different from what they were 15, 20, 30, 40 years ago," said Jacopo Buongiorno, a nuclear engineering professor at the Massachusetts Institute of Technology (MIT). "It’s the same with nuclear. You’re now buying a model 2020 Mercedes. You’re not buying a Peugeot from 1965."
Many new models of nuclear power generation technology exist, varying in size, design and market-readiness, but they share some critical features designed to make them safer and more versatile than previous models.
Some experts are skeptical that these new technologies will be able to achieve their intended advantages at a reasonable cost, in a manner safe enough to confidently allay concerns — at least not without huge government subsidies, which seem unlikely in the U.S. for the foreseeable future.
"If it sounds too good to be true, it probably is," said Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists.
Like any comeback story, there are major barriers to overcome, and there’s no guarantee of success. However, there’s also something captivating about a redemption arc. In particular, there are three opportunities that nuclear advocates see as a pathway to redeeming nuclear energy in the 21st century.
NUSCALE正在制定计划在美国的第一个小规模的核电站，其中12个反应堆。照片（鸟瞰图）由NUSCALE提供
机会1：缩小规模
One of the biggest recent advances in nuclear energy has been making reactors smaller. The reactors of the 20th century were large, expensive behemoths. These large plants could generate enough energy to power millions of homes, but they also required decades of time and billions of dollars to build.
The latest trend in nuclear is the small modular reactor (SMR), which generates a fraction of the energy of traditional reactors, but at a fraction of the cost. Existing nuclear reactors generate 500 megawatts to 1 gigawatt of electricity. SMRs generate less than 300 MW.
较小的反应堆的好处是它们比他们的前辈更灵活。单个反应堆可以适合能量需求较低的项目，并且可以将多个反应堆添加到具有更高能量需求的项目上，例如将额外的汽车挂起到货运列车或将更多灯泡连接到一串度假灯。
NuScale位于俄勒冈州arguably has made the most progress with SMR technology. Its reactors have a capacity of 60 MW, enough to power about 50,000 homes. The companyrecently received美国核监管委员会（NRC）的初步设计批准，其设计最接近任何小规模核反应堆的绿灯。
“这对我们来说是一个巨大的里程碑，”Nuscale首席技术官Jose Reyes说。
借助a13.5亿美元的补助金from the Department of Energy, NuScale is making plans to build the United States’ first small-scale nuclear power project. The plant would consist of 12 reactors selling electricity to a consortium of cities in Utah, with the first reactor turning on by 2029.
“我们相信我们在我们用安全性和移动到这种不同的范例方面，我们铺平了道路，以便部署反应堆，”雷耶斯说。
犹他州项目仍然有很长的路要走，过去几个月被陷入困境delayed timelines那撤回城市伙伴关系andlingering questions关于安全。
虽然前往先进的核电的道路仍在铺设，但它远非空虚。整个公司的公司在本十年结束时试图在本十年结束时建立下一代核电站。
如果您将定位核反应堆，接近易燃或可燃的化学设施，显然可以注入新的问题。
Like NuScale, many of these companies are thinking small, but some are also thinking different. NuScale’s reactor is a smaller version of the reactors at 20th-century nuclear power plants, which use water to cool the high-temperature reactions at the core. Newer technologies cool the reactions with molten salt or high-temperature gas.
Terrestrial Energy那based in Ontario, is working with Canadian regulatory agencies to get approval for its molten salt reactor design. The company aims to have two plants licensed and built by 2030, each with a capacity of 195 MW.
Canon Bryan, chief financial officer of Terrestrial, noted that building small isn’t just a practical opportunity, it’s a financial one. He has observed that private investors are hesitant to back a project that would cost over $1 billion, but expenditures less than that are a different story.
“在部署方面，全球核能行业面临核能行业的最大限制是前期成本，”他说。
Buongiorno也认为成本是关键阈值，特别是当小核电站饲喂电网时，与其他发电来源竞争，而且还补充它们。
"They would be a good combo with renewables," he said, "because when the sun doesn’t shine, the wind doesn’t blow, you can have your nuclear reactors that cover the peaks and the valleys. The key question is, at what cost? If the levelized cost of electricity for this system is too high then people will just not buy them, and they might find it even more advantageous to buy big storage."
For off-grid applications, some nuclear technology companies are thinking even smaller than small. A few companies are working on "micro"-scale reactors of less than 50 MW, with some as small as 1 MW. These microreactors could power mines as well as unconnected or poorly connected communities.
一个这样的公司是Ultra Safe Nuclear Corporation（USNC）开发了一种氦气冷却的微反应器，容量为5兆瓦。Mark Mitchell是USNC的权力部门总裁，指出，起始的且变大是相同的途径，适用于太阳能等可再生能源。
“它代表了一种新的方式来做核强烈modeled on how renewables businesses have worked and scaled over the last 10 years," he said. "If nuclear learns the lessons from renewables, I think it will be very powerful."
Bryan emphasized that having a variety of sizes opens the door to a wide set of applications for nuclear, in a way that was previously impossible. "The only types of nuclear power plants that are available today are one size: enormous, and one size does not fit all," he said
Opportunity 2: Versatility
涉及能源发电时，电力只是一开始。More than 80 percent世界能源的流向非电量uses such as industrial processes and transportation. In that sense, the nuclear plants of the 20th century essentially have been humongous one-trick ponies, because their only function is to make electricity. The next generation of nuclear has the potential to do other tricks, and the basis for most of those tricks is heat.
"Most everything we encounter in society is made in an industrial facility, and most every single industrial facility uses heat," Bryan said. "That is a vast market that nuclear innovation can compete in, where no other technology really can, except for fossil fuels. If nuclear innovation can compete on cost with fossil fuels, then I would have to say that it’s game, set, match."
Traditional reactors can’t exceed 572 degrees Fahrenheit or the coolant will start to boil off too quickly, creating major safety risks. However, that’s not a problem for molten salt reactors, which can reach temperatures of 1,292 degrees F, or high-temperature gas reactors, which can reach over 1,652 degrees F.
布莱恩说，大多数工业设施需要25至150兆瓦的能量，这意味着在大多数情况下，小型反应堆至少理论上能够更换化石燃料以满足工业需求，只要它们可以降低成本。
这只是今天的产业流程。低碳未来将需要全新的全新能源密集型流程。结合热量，蒸汽和电力是一个有效的配方，用于从水中拉出氢气并使用它用于氢气。热量对制造钢和混凝土是至关重要的，一些最具挑战性的地区脱碳。为了有净利润，直接捕获二氧化碳from the atmosphere requires low-carbon sources of either heat or electricity. All of these processes potentially could be powered by small, high-temperature nuclear reactors.
“如果你可以使用[核反应堆]，那么你将能够开始脱碳，否则就可以用电力，你无法触及，”Buongiorno说。
However, safety experts such as Lyman warn that industrial applications bring additional risks. Heat-producing reactors would need to be in close proximity to the facilities where the heat is used, making proper containment procedures even more critical.
"If you’re going to be locating nuclear reactors close to chemical facilities that are flammable or combustible, obviously that can infuse new concerns," Lyman said.
Canadian firm Terrestrial Energy is designing small-scale molten salt reactors. It hopes to have two plants, each with a 195-megawatt capacity, licensed and built by 2030. Courtesy of Terrestrial Energy
机会3：设计更安全
从气候观点来看，它鼓励想象一个充满小型核电站的未来，提供便宜，丰富，低碳能源，以各种各样的目的。但是，有些人会发现生活在一个小型核电站附近。核技术需要确保安全超出任何怀疑的阴影。这就是为什么先进的核公司规划固有的安全特征，他们希望能使许多潜在的灾难不仅仅是不可能的，而且是不可能的。
The safety risks can be grouped generally into three main categories. First, there’s the risk that nuclear fuel will fall into the wrong hands and be used to create a nuclear weapon. Then, there’s the risk that a plant will malfunction and release toxic radiation. Lastly, there’s the risk that the leftover material will pose a danger wherever it’s stored.
让我们从措施开始解决武器扩散的风险。任何放射性物质都需要保持警惕，但大多数核反应堆中使用的燃料与武器级核材料非常不同。放射性铀的浓度远低得多，富集的浓度更高的浓度是复杂且昂贵的，而不是任何单个演员可以完成的东西。
此外，较小的反应器的好处是它们是可运输的。这意味着即使反应器本身被广泛分布，它们也可以设计成使得燃料仅在中央，安全位置中添加或移除。
These elements don’t rule out the risk of nuclear material getting into the wrong hands, but they help ensure a nuclear power sector that’s distinct from weapons production.
接下来，存在灾难性意外的风险。过去发生的每次失败都是一种学习体验，导致增强的设计，旨在消除同样的问题的可能性，即使在极端或不太可能的情况下也是如此。这被称为固有的安全性。
例如，福岛崩溃发生在海啸击中电力供应后发生。先进的核设计使用依赖重力的被动冷却技术，不需要外部电源。在福岛，用来冷却植物的水沸腾了。如果没有水，并且如前所述，小型核反应堆如NUSCALE的设计用于从周围的空气中冷却，并且如前所述，如前所述，诸如熔盐和高温气体的冷却剂不会脱掉。
Ultimately, what happens when reactors fail is that the solid fuel melts and seeps out of the area where it’s contained, hence the term "meltdown." Gas reactors use燃料球各自单独涂有保护罩，大多数熔盐反应器根本不使用固体燃料。相反，将它们的燃料溶解在盐中，完全消除崩溃风险。
"You can’t melt down something that is already liquid," Bryan said.
然而，这些新的冷却剂具有自己的挑战和并发症，例如用于含有高温过程或副产品的核算的保障措施。传统的反应堆已开发出多层保护，先进的技术可能需要解决额外的安全机制，以补充已经内置的设计。
"If you give too much credit to fundamental design features for safety and then use that to justify reducing other types of safety measures, then you end up with something that’s less safe," Lyman said.
Lastly, there’s the waste, which nuclear professionals refer to as "spent fuel." Some reactors use what’s called a快速反应那which converts spent fuel back into usable material, leading to an end product that’s much less radioactive, or potentially to no extra material whatsoever, if this process is repeated a sufficient number of times.
然而，快速反应器比其他反应器更难以稳定，因为其他反应器具有慢速和控制反应的内置机制。快速反应堆也可以与武器级钚燃料一起运行，这可能是永久摆脱武器股的有用方式，但也产生了额外增殖的风险。
In practice, most advanced reactors likely would create some sort of spent fuel that would need to be stored securely for centuries. Currently, in the U.S., spent fuel is stored onsite at nuclear plants, which isn’t sustainable in the long term.
找到一个更久的地方来存储这款花费的燃料一直很棘手。最值得注意的是，由于当地的反对，内华达州伊加达山区尤卡卡山的储存库的计划被延迟无限期。
“这个问题一直是政治进程，在美国，我们已经做出了灾难性的错误，”布康诺说。
在一天结束时，社会许可证真的处于反应堆设计的最前沿。
但是，芬兰等欧洲国家already building storage sites那which have moved forward with the support and buy-in of the surrounding communities. Once repositories such as these are built, they only need to store a modest volume of spent fuel.
Buongiorno has a knack for coming up with clever visualizations, and he helped me to put the volume of spent fuel into context. "If you or I were to use nuclear energy for our lifetime, the amount of high-level waste … would fit into a teacup," he said. "All your life, just nuclear electricity, that’s the amount of waste that you have."
显然，那些茶杯将加起来，它们是放射性的，但如果可以对政治进行整理，这是一种可管理的材料量，这对于先进的反应堆和传统来说是正确的。
Still, it's not everyone's cup of tea. All of these safety measures can’t guarantee that advanced nuclear will be absolutely risk-free, especially as there aren’t yet any advanced nuclear plants in commercial operation. There’s always the potential for unknown unknowns with new technology, and in the case of nuclear energy, mistakes can be catastrophic. The fact that older technologies already have experienced errors and shutdowns doesn’t help.
莱曼说，“谈论开发一个没有任何经营经验的新一类反应堆时，关键的考虑之一就是试图考虑所有的不确定性，”莱曼说。
Every nuclear technology company I spoke with emphasized taking nuclear safety seriously. Ultra Safe Nuclear Corporation (USNC) even chose to put safety front and center by including it as part of its name.
“我们的名字也是对自己和行业的挑战，”米切尔说。
This safety-first approach goes beyond lip service. Companies need to show thorough evidence of safety in order to receive the regulatory approval necessary for setting up a new nuclear plant in countries such as the U.S. and Canada.
Lyman, however, is worried that nuclear companies and the NRC are rushing the process to bring unproven technologies to market.
"The NRC is under quite a bit of pressure by the industry and by Congress not to hold things up," he said.
In addition to the formal regulatory process, there’s also the court of public opinion, an additional reason for companies to think through every possible risk, even the ones that seem improbable.
"They’re perceived issues," said Carl Perez, chief executive officer ofElysium Industries，一家设计了大型熔盐反应堆的公司。“这足以认为这是一个问题。在一天结束时，社会许可证真的处于反应堆设计的最前沿。”
俄克洛微反应器的渲染。由奥克洛提供
核的下一个行为
核电已经为可再生能源作为一个干净而有前途的能量选择，但它在重新进入敏捷的边缘，可能比有些人更快地进入敏捷。
"A lot of the general thinking out there is that these technologies are great, but they’re not going to be ready for 30, 40, 50 years. What we’re here to say is that that is rubbish," Bryan said.
即使是核聚变，小原子的高能量组合（例如在太阳内发生的事情）看起来更多within the realm of possibility。
This technological progress is exciting because nuclear energy is seen by some as an important tool to have in the toolbelt for solving climate change. Buongiorno and a team of other nuclear researchers ran scenarios for reducing emissions in the electricity sector in multiple regions of the world, andthey foundthat advanced nuclear fission was critical to reaching the lowest carbon at the lowest cost.
"Nuclear really can and should play a role if we’re serious about decarbonizing," Buongiorno said.
如果您开始说您必须将核电作为系统的一部分，那么您可能会在您需要的安全程度上提出错误的答案。
The Union of Concerned Scientists, which has long been critical of nuclear technologies, also承认the value of nuclear power as a carbon-free energy source, although the organization continues to push for the strictest possible safety considerations.
"If you start off by saying you have to have nuclear power as part of the system no matter what, then you could come up with the wrong answer with regard to the level of safety you need," Lyman said.
Some nuclear advocates see decarbonization as an imperative to think bigger. Perez is skeptical of small modular reactors. His company is looking to build large molten salt reactors (more than 1 GW) in parts of the world where energy demand is increasing rapidly.
“我们想要贬低世界的速度迅速？因为如果我们想快速这样做，那么我们需要不建立小输出反应堆，”他说。
However, decarbonization is a motivating factor for developing smaller technologies as well. Oklo has designed a 1.5 MW microreactor, and its founders also see the company’s technology as a part of the patchwork of solutions necessary to address climate change.
"Countries that have deeply decarbonized did it using nuclear and renewables," said Caroline Cochran, chief operating officer of Oklo. "That’s what we really need to do if we want to rapidly decarbonize in a way that we have to do if we want any semblance of not having massive ecosystem collapse."
Oklo takes its name from the Oklo region of Gabon, where uranium deposits have formednatural fission reactorsfor 2 billion years, deep below the earth’s surface. This name choice is a reminder that nuclear fission has been a part of the world for eons, even though humanity only stumbled onto it recently.
