Challenges of the nuclear industry
08 May 2018
Long-term, reliable solutions are in high demand within the nuclear industry. What does this mean for components such as connectors? And how are connector companies evolving to meet these increasingly extreme requirements? DPA asked Peter Dent, MD LEMO UK LTD, for his thoughts.
The nuclear industry demands long-term reliable solutions designed for the most severe environments. How do LEMO connectors meet these demands?
Working within the nuclear industry presents many unique challenges, as exposure to hazardous conditions means that many of the processes need to be controlled, monitored and maintained remotely. Whilst alpha-emitting isotopes are handled in sealed containers called glove boxes, gamma-emitting isotopes are handled within heavily shielded rooms, called hot cells. Tasks performed in these hot cells are managed remotely as the governing bodies operating these facilities practice the ‘As Low As Reasonably Achievable (ALARA)’ policy which minimises operator exposure to harmful radiation. To manage this requirement safely, a specialist branch of robotics known as tele-manipulators has evolved over the last few decades. They are highly sophisticated master-slave type devices, enabling the operator to complete a task at a safe distance whilst providing them with a sense of touch and feel.
Designing a device for use in a radioactive environment has considerable challenges, since many common materials and components have a short-life expectancy in high radiation. In addition, these devices and/or components need to withstand decontamination processes which involve a mild acid wash. Coupled with the unique material requirements, most tele-manipulators are mechanical devices which operate on a 1:1 ratio and therefore, the forces exerted at the slave side are limited by the human element input on the master side. Highly sophisticated force reflecting master-slave servo manipulators have been developed for heavier operations, but these are less common due to the obvious costs involved.
Electrical connectors designed for use in these environments also have unique features as, critically, the main design consideration is a remote coupling requirement. With operators observing movements through a radiation shielding window (RSW) or via a CCTV system, connectors need to have a large mating capture area, as well as a self-coupling system that can be de-activated by gripper controls. In addition, low mating forces are an obvious benefit as this negates force restrictions associated with certain types of manipulators. Furthermore, observing operations through a window or via a monitor naturally impairs a depth perception in the Z axis and therefore designs also need to cater for this requirement by providing guiding aids to ensure precise interconnection.
Which features are unique to connectors developed for the nuclear industry?
LEMO has supported the nuclear industry for many decades and during this period it has developed the N-Series range of connectors specifically designed for use in remote handling applications. With the hazardous environment, the first unique feature of this connector is the material selection. Housings are manufactured from stainless steel 304, while contact insulators are manufactured from Polyether ether ketone (PEEK) Thermoplastic and seals from Ethylene propylene diene monomer (EDPM) Elastomer, all of which exhibit excellent radiation resistant properties. The second unique feature is the coupling/decoupling mechanisms. Products need to be robust and designed so that they can be coupled by remotely controlled robots and therefore self-guiding features are a pre-requisite. On the LEMO N series connectors there is an additional depth aid (bump bar) designed-in to help operators align the Z axis. In addition, latching systems are automatic with visual aids to help operators determine whether the connector has been fully engaged. Uncoupling these connectors is like other LEMO push-pull connectors, except the collar has flats for gripper operation. Furthermore, relatively low mating forces and optional CAM-assisted operation are also features you will find on these reliable heavy-duty connectors.
Around the world, nuclear facilities are reaching the end of their lives as they pass half a century of service. The decommissioning process involves extensive equipment to complete nuclear waste disposal and decontamination of the site. This is creating a robust market for connectors that can perform in these roles. How are connectors evolving to meet these demands?
The UK nuclear industry is one of the driving forces behind the global development of decommissioning equipment. As with the other processes within the industry, operations need to be completed remotely where achievable and therefore purpose built tele-manipulators are also widely used in this stage of the life cycle. Again, products need to be “fit for purpose” as this process can take years. Furthermore, the issue of low maintenance is another consideration for design engineers within these complex environments.
“With respect to the design-in of LEMO’s products within the nuclear industry, does the company service these applications in the UK or in Europe. Perhaps, it may even undertake such work further afield”?
With the UK leading the development of tele-manipulators for use in the nuclear industry, many of the projects LEO support are for use in other countries using nuclear power such as Japan, Germany, France and China.
As a business, LEMO has a global footprint whilst maintaining strong local, culturally-aligned services. Supporting such critical projects using the group capability is one of the key reasons that customers come to LEMO.
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