Made to measure A special container spreader with special functionality
On the artificial island of Beznau in the Aar river, Axpo Power AG (Axpo) operates a nuclear power station of the same name, the oldest pressurised water reactor in Switzerland. Regular inspections, maintenance and renovation work have allowed the plant close to the German border in the canton of Aargau to continue producing electricity safely. In the course of the latest renovation work, the store for weak and medium radioactive waste was rebuilt in order to use the available space better. One of the components of the optimised store: a KAUP 25T191KND8 container spreader with automatic level compensating device and shaft rotation.
Projects involving power stations, whether hydro, gas or nuclear, are always complex. Numerous papers, calculations, designs and documents have to be individually prepared and industry-standard guidelines and standards adhered to. In the project, the specifications and requirements of the Beznau nuclear power plant and not those of the German Nuclear Safety Standards Commission (KTA) were applicable.
The primary contact for KAUP in this project was Bifag AG (Bifag). The company plans and installs crane systems and hoisting devices and is responsible for the cranes and hoisting equipment in the Beznau plant. It coordinated this part of the store rebuilding and worked with KAUP for the first time. The beginning was surprising. “I came across a picture of a spreader that could be rotated through 360°”, explains Daniel Trachsel, technology head at Bifag, and continues: “I followed that link and landed on KAUP, luckily.” Because, despite no physical meeting during the project, all those involved are very happy with the result.
Assignment and area of application
For the rebuilding of the store, Bifag planned to add an additional spreader to an existing crane system already including a 20‘ container spreader in order to move specially sized LC concrete containers with up to 25 tonnes of weak and medium radioactive waste. The handling task to be implemented initially seemed standard: The containers are picked up outside the radiation protection area, moved over an existing shielding wall and deposited inside the radiation protected area. But in reality, the assignment was tricky to implement. “But KAUP got down to the development work in a creative and targeted manner right after the request in March 2022,” emphasizes the Axpo project engineer in charge, adding: “And at the time, they didn’t even have the order.”
The container spreader is controlled from a shielded control position and has to fulfil certain key properties. For example, it requires a compact height in order to move over the shielding wall carrying a container. At the same time, the design must ensure that the containers stored a floor lower can also be gripped and handled. Furthermore, the operational conditions demand a small run-in play and spacings of 50 mm to the neighbouring containers and 60 mm and 80 mm to the edge positions. This includes end positions that are difficult to access involving two corners. As a result, the spreader needs to be able to rotate the containers by 90° horizontally. Last but not least, the existing connection cable to the crane must be used by the spreader so that the new functions can also be controlled. “None of this is standard and needed some creativity in the design”, says Maximilian Noll, responsible for the development of this spreader at KAUP. Creativity that convinced. “We always had a good feeling” says Daniel Trachsel, because “KAUP were always competent and contributed their own ideas.”
Control with camera and laser
The crane spreader has been in use in the Beznau nuclear power station since early 2024. Alongside the key properties already mentioned, KAUP implemented other features, some for the first time. For example, the spreader was attached to the existing crane with a 2-point mounting to prevent swinging or tilting of the containers if they were not evenly loaded. “An unusual solution”, the Axpo project manager emphasizes positively, because “normally there are 1 or 3-point mountings.” The level compensating device likewise installed, which can be activated as required, gives additional safety, because it compensates for non-centralised load carrying (0 - 7 %) for unevenly loaded containers. This is particularly important as the containers can ultimately be stacked on top of each other to the height of nine storeys.
As the operator in the control position naturally does not have an overview of the complete store, there are some supporting functions. Cross-hair lasers on the underside of the spreader visualise the container contours on the floor and provide a rough orientation for the operator. Measuring scales and a total of eight cameras ensure exact positioning. It was challenging to find suitable positions to install them. After all, they have to be positioned such that an exact overview is transmitted to the control position. This is particularly important when the shielding wall has been passed and the storage positions are moved to.
Complete satisfaction
The spreader is intended to be in use for the next 20 to 30 years, political decisions allowing. Which from the perspective of those involved in the project should not be a problem. “The feedback on the functionality and quality of the equipment was very positive” reports the KAUP design engineer, Maximilian Noll. The customers and users agree. As Axpo say about the spreader: “The quality supplied actually exceeded all expectations.” And Daniel Trachsel adds for Bifag: “The equipment was supplied with a quality that I had not expected these days.” And the experienced head of technology continued: “Even the small details had not only a top design, they were also installed to the same standard.” They are both unanimous: “If we needed another spreader, then it would only be from KAUP. Because they are really good.”
