Upgrading & Uprating

Going virtual

25 July 2010

Any plant upgrade relies heavily on information. As operators of nuclear plants move toward a fully-digitised record of their plant, computer-based tools simplify the capture, use and exchange of digital information. By Bob Aldridge

Digital information is now so pervasive that it can come as a surprise to realise that many of the western world’s nuclear plants were designed before the computer age or, at least, with relatively primitive early software tools. This issue becomes a critical problem when operating licence renewals approach or when major upgrades are required. Current regulatory requirements demand very high levels of information integrity and it is not unusual for this to impose extensive reverse engineering to bring legacy plant information up to these higher standards.

In an ideal world, an entire plant would have a complete, accurate and fully-detailed ‘digital plant’ counterpart, enabling modern engineering IT solutions to be applied to its operation and maintenance. This almost never exists in practice, but many plants are progressively being reverse-engineered into the digital domain. A typical example is the Paks nuclear power plant in Hungary, which has recently undergone an extensive programme of upgrading and modernisation and is now preparing for its licence renewal. Generating around 40% of the country’s energy needs makes it a vital national asset, so creating a ‘digital Paks’ was seen as essential to this programme and to its long-term operations strategy. Part of this programme involved surveying the plant.

Historically, surveying an as-built plant was a laborious process involving steel measuring tapes and theodolites. While this may still have its place for some projects, the time, costs and hazards involved in any extensive survey can be considerable. Today, there are two principal methods for digitising an existing installation: photogrammetry and laser scanning. The effectiveness of this approach is well-established; the optical scanning technologies are mature, accurate, non-invasive, safe and cost-efficient. Contractors in the oil & gas industry routinely use the 3D virtual backdrop technique to create accurate bolt-in upgrades for offshore platforms, on which any welding or grinding is prohibited and downtime is very costly.

Each method has its merits, but either can be used to capture an accurate 3D survey of a plant that can then be manipulated within a 3D plant design system such as Aveva’s PDMS. According to need, this survey data can be used either to reverse engineer the as-built plant into a fully intelligent PDMS model or used just as a form of 3D virtual backdrop against which plant modifications can be designed so that, for example, new pipes will fit accurately onto existing equipment nozzles. In practice, plant operators will often adopt both approaches; the former is a long-term strategic process aimed at ultimately creating a full digital plant, while the latter is an expedient way of gathering information for an upgrade or local modification and may contribute to an overall digitisation strategy.

So when planning an upgrade, an effective first step is to scan the parts of the plant involved. Even large areas can be captured by automatically stitching together multiple local scans, so that not only the plant elements themselves can be modelled, but also the surrounding building structure. For particularly large or awkward upgrades this enables the demolition, equipment removal, equipment installation and buildings restoration stages to be planned using 3D CAD models. This brings to upgrade projects techniques such as animation, which are commonly used in new-build designs to simulate construction sequences.

One important area which has seen considerable transformation in recent years is the methods available for communicating and sharing design information. Virtual reality representations of 3D designs are not new, but technology now enables navigable, photo-realistic 3D views of even the most complex plant to be streamed over the internet. This enables, for example, a proposed upgrade to be reviewed by ‘walk-through’ navigation by a specialist anywhere in the world with an Internet connection.

In the case of major plant upgrade projects, the ability to construct animated sequences of the equipment removal and replacement processes can be valuable in both the planning and execution stages. Combined with the ease of internet communication, this enables all project stakeholders to contribute effectively in planning the work, and the project execution team to plan and rehearse each individual step in the procedure as the work proceeds.

As digital plants gradually become more common and more comprehensive, efficiency benefits follow. Upgrade projects will become easier as the necessary information becomes more complete, more reliable, and more accessible.

Author Info:

Bob Aldridge is marketing manager, AVEVA Plant, AVEVA Solutions Ltd

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