Technology Engineering OceanGate's'Titan' went on 7 dives with a damaged hull before implosion Investigators found that the submersible's exterior featured'multiple anomalies' as early as 2022. Breakthroughs, discoveries, and DIY tips sent every weekday. The United States National Transportation Safety Board (NTSB) recently concluded its investigation into the OceanGate submersible disaster . According to the summary report released on October 15, an already weakened hull caused the deep sea tourist vessel to implode while it was en route to visit the wreckage of the RMS in June 2023, killing all five passengers on board. But according to their findings, investigators noted that the submersible wasn't damaged shortly before its final voyage.

During the design process of an autonomous underwater vehicle (AUV), the pressure vessel has a critical role. The pressure vessel contains dry electronics, power sources, and other sensors that can not be flooded. A traditional design approach for a pressure vessel design involves running multiple Finite Element Analysis (FEA) based simulations and optimizing the design to find the best suitable design which meets the requirement. Running these FEAs are computationally very costly for any optimization process and it becomes difficult to run even hundreds of evaluation. In such a case, a better approach is the surrogate design with the goal of replacing FEA-based prediction with some learning-based regressor. Once the surrogate is trained for a class of problem, then the learned response surface can be used to analyze the stress effect without running the FEA for that class of problem. The challenge of creating a surrogate for a class of problems is data generation. Since the process is computationally costly, it is not possible to densely sample the design space and the learning response surface on sparse data set becomes difficult. During experimentation, we observed that a Deep Learning-based surrogate outperforms other regression models on such sparse data. In the present work, we are utilizing the Deep Learning-based model to replace the costly finite element analysis-based simulation process. By creating the surrogate we speed up the prediction on the other design much faster than direct Finite element Analysis. We also compared our DL-based surrogate with other classical Machine Learning (ML) based regression models( random forest and Gradient Boost regressor). We observed on the sparser data, the DL-based surrogate performs much better than other regression models.

Nearly a decade after the three meltdowns at Fukushima No. 1 nuclear power plant, plans are underway to finally remove nuclear fuel debris from the three reactors. But in order to remove it, Tokyo Electric Power Company Holdings Inc. (Tepco), the operator of the plant, needs to ensure there is a place to store the debris once it is retrieved. This is thought to be the reason why the government is rushing to give the green light to releasing tritium-laced water piling up at the plant into the Pacific -- to give room for the storage of fuel debris. But removing the fuel debris -- a crucial step in the decommissioning process -- is an enormous task on its own, with measures that need to be resolved emerging one after another. At a three-day online meeting of the Atomic Energy Society of Japan from Sept. 16, an official from the International Research Institute for Nuclear Decommissioning (IRID) who is in charge of technical development regarding the decommissioning of the Fukushima plant, explained the plan, or the lack thereof, to remove the debris at reactor No. 2. "We will consider what kind of measures to take, comparing tactics and developing techniques," the official said, with a hint of frustration at not being able to come up with a specific way yet.

Tokyo Electric said Friday that a remotely controlled robot investigating the interior of reactor 3 at the Fukushima No. 1 power plant has finally spotted objects that could potentially be fuel debris. The objects look like icicles hanging around a control rod drive attached to the bottom of the pressure vessel, which holds the core, Tokyo Electric Power Company Holdings Inc. said at an evening news conference. Enclosed by the huge primary containment vessel, the pressure vessel originally contained the fuel rod assemblies. But the rods melted into a puddle and pierced the bottom of the pressure vessel once the plant lost power after being swamped by the monstrous tsunami of March 11, 2011. The robot also captured images of lumps of material that appears to have melted and resolidified near the wall of the pedestal, a concrete structure that supports the pressure vessel.

The location and condition of the fuel in the three reactors hit by core meltdowns is critical information for Tokyo Electric Power Company Holdings Inc., which runs the plant. Removing the fuel debris is considered the most difficult part of decommissioning the complex. Unit 3 has the highest level of water inside at 6 meters. The fuel debris inside is presumed to have melted through its pressure vessel and settled at the bottom of its primary containment vessel. "Until today, no one has seen the situation inside reactor 3," said Tsutomu Takeuchi, senior manager at Toshiba's Fukushima Restoration and Fuel Cycle Project Engineering Department.

MUELHEIM-KAERLICH, GERMANY – As head of the Muelheim-Kaerlich nuclear reactor, Thomas Volmar spends his days plotting how to tear down his workplace. The best way to do that, he says, is to cut out humans. About 200 nuclear reactors around the world will be shut down over the next quarter century, mostly in Europe, according to the International Energy Agency. That means a lot of work for the half a dozen companies that specialize in the massively complex and dangerous job of dismantling plants. Those firms -- including Areva, Rosatom's Nukem Technologies Engineering Services, and Toshiba's Westinghouse -- are increasingly turning away from humans to do this work and instead deploying robots and other new technologies.

Six years after the triple meltdown at the Fukushima No. 1 nuclear power plant, recent investigations underneath the damaged reactor 2 using cameras and robots came close to identifying melted fuel rods for the first time. Experts say getting a peek inside the containment vessel of reactor 2 was an accomplishment. But it also highlighted how tough it will be to further pinpoint the exact location of the melted fuel, let alone remove it some time in the future. The biggest hurdle is the extremely lethal levels of radiation inside the containment vessel that not only prevent humans from getting near but have also crippled robots and other mechanical devices. Safely removing the melted fuel would be a best-case scenario but the risks and costs should be weighed against the option of leaving the melted fuel in the crippled reactors, some experts said.

"We put in cameras and robots and obtained valuable images, though they were partial . . . "We first need to know the situation of the debris." Last month, the utility inserted a 10.5-meter rod with a camera on its tip into a hole in the No. 2 reactor's primary containment vessel and discovered black lumps sticking to the grating directly underneath the suspended pressure vessel, which holds the core. Tepco claims it is still unsure whether the lumps are really melted fuel that burned through the bottom of the pressure vessel. Although it is still years away from actually trying to remove the fuel, Tepco, the government and related parties are planning to decide on a basic strategy this summer and go into more detail next year.

A renewed attempt to survey reactor 2 at the damaged Fukushima No. 1 nuclear power plant failed Thursday when the latest robot probe became obstructed. The robot was inserted into the primary containment vessel at around 7:50 a.m. to approach the metal grating directly underneath the pressure vessel, where a black mass has been found. Tokyo Electric Power Company Holdings Inc. had hoped to take a closer look at what could be melted nuclear fuel, but it was forced to abandon the operation shortly after 3 p.m. The robot didn't reach its objective, Tepco said, and the utility eventually severed its controller cable. Having detected an extraordinarily high radiation level --estimated at 650 sieverts per hour -- in a preparatory survey, Tepco had hoped to obtain more precise readings, images and data needed to remove fuel and other debris to decommission the plant.

The high radiation estimates in the No. 2 reactor of the stricken Fukushima No. 1 nuclear plant will probably force a rethink of the nationalized utility's robot-based strategy for locating its molten fuel. According to an analysis of Thursday's abbreviated probe, the radiation in the primary containment vessel is about 650 sieverts per hour, more than the 530 sieverts estimated late last month, Tokyo Electric Power Company Holding Inc. said. That level could kill a person quickly and indicates the fuel likely burned through the pressure vessel during the meltdown and is somewhere nearby. Tepco, as the utility is known, halted Thursday's robot after its camera went dark. The company suspects the problem was caused by the radiation.