Digital technology can help solve system obsolescence and performance degradation issues that plague many ageing I&C systems. It can enable management to reduce costs and increase plant output and operating margins. It eliminates the significant risk posed by ageing equipment by implementing state-of-the-art open architecture. Digital technology minimises plant O&M costs through a standardised digital platform. It simplifies plant operations. And, by selecting a limited number of I&C solutions, the organisation is better able to share the risks and rewards of plant operation in a deregulated electric generation industry.

Choosing the right time and the right level

Of course, all existing plant I&C systems do not need to be modernised before end of plant life. A sensible modernisation programme should focus on a logical phased replacement of selected plant I&C systems. New, advanced digital systems make sense when:

they create cost-justified enhancements to plant safety;

modernisation improves plant performance through greater availability or reliability; or

when an ageing system cannot be maintained until the end of plant life.

The initiation of a logical modernisation programme provides other benefits as well. A visionary approach, with the effective integration of information technology with modern instrumentation and controls can impact the entire plant business cycle with enhancements to plant reliability, process automation and staffing optimisation.

Deciding on the appropriate level of I&C modernisation requires some degree of objective soul-searching and a critical appraisal of your current situation.

You must have a thorough understanding of your plant’s current I&C technology, with an estimate of its maintainability. There are practical limits on ageing I&C systems. Operating histories from many plants have demonstrated that, as equipment ages, a point is reached when occurrences of equipment failure begin to increase significantly. Modernisation is required before that point is reached.

Manpower is a related issue. Maintaining an I&C maintenance staff to service existing analog equipment will become increasingly difficult. There is an industry-wide shortage of ageing skilled people to maintain older analog equipment.

The obvious advantages of digital information and control technology over current plant I&C systems might dictate modernisation even if the current systems are performing as designed and at previously accepted cost levels. If a plant upgrades to take advantage of more advanced technology, initiating the modernisation process before the plant experiences increasing maintenance costs allows management to pursue options that will give the best return on investment.

You should consider the impact of integrating information technology and instrumentation & control technology on plant wide, and utility wide, enterprise integration. Integrated I&C systems may encompass plant computer and information systems, non-safety nuclear steam supply systems and balance-of-plant control, safety systems diagnostics and monitoring systems, and a wide range of special nuclear applications like rod control, flux mapping and nuclear instrumentation.

I&C replacements and upgrades are categorised into five levels of implementation, from easiest to most difficult (see Figure 1). A utility can implement at a pace consistent with operational changes and to gain experience before proceeding to the next level. Plant upgrades with the largest near-term impact can be implemented during the first few outages to obtain an immediate return on investment.

Two key Issues

There is no doubt that I&C modernisation can reduce the cost per kWh. But this alone is not sufficient justification.To decide whether or not to move forward with an I&C modernisation programme, utility management must address two key issues:

First, is modernisation justified by conventional cost benefit analyses? Previous analyses of a great many plants show that a modernisation involving Levels 1 and 2 has an acceptable payback period. This payback is realised through reduced inventory and training, increased operational efficiency and the enhanced capabilities of microprocessor-based technology in terms of diagnostics, calibration and reliability. The payback period will be shorter as annual increases in maintenance costs for analog systems become more and more non-linear. The phased approach, with a minimum number of I&C solutions from a single vendor to handle maintenance of analog equipment and system upgrades, typically results in the lowest cost and lowest risk strategy.

Second, can your plant afford the risks of competing in a deregulated market with ageing analog systems? There will come a time when the failure rate will become unacceptable, both from an economic as well as from a performance point of view. Not only will it be more costly to maintain the analog equipment, but it may be difficult to maintain the staff with the required skills. These threats can make a nuclear plant non-competitive with other power generating stations.

Economic analyses further indicate that implementation of Levels 3, 4 and 5 provide the technology to enable plant management to manage cost reductions, process improvements and productivity improvements in all other areas of plant operations. For example, while implementing Level 1 will optimise staffing in the I&C department, implementation of Levels 2 to 5 provides an opportunity for plant-wide O&M staff optimisation. This results from the automation of required periodic surveillance testing, the automation of plant processes, decreased training time, and an enterprise management of plant-wide I&C systems.

Counting the costs

The cost of I&C system modernisation is based on the cost of the replacement hardware and the estimated costs of installation. A phased implementation allows utility management to minimise technical risks while immediately realising the benefits of I&C systems technology.

Use of a standardised I&C system can reduce costs and directly benefit plant operations. Costs are reduced by cutting maintenance and operating needs, minimising training requirements and the need for smaller inventory levels. Plant operations directly benefit from the effectiveness and efficiency realised through the use of a standard human–machine interface, while system maintenance complexity is reduced with only a single platform to understand and maintain.

Of course, any paradigm change in plant operations must be accompanied by a detailed financial analysis to justify a large scale capital investment in upgraded I&C systems. Westinghouse has created a cost/benefit model to help evaluate the costs, both on an annual and on a cumulative basis, of operating and maintaining I&C systems.

The model permits sensitivity studies of various implementation scenarios such as systems replaced, systems maintained, phased replacement schedule, vendor costs and utility costs. The model identifies the break-even point for installing a proposed I&C modernisation programme.

Figure 2 shows the sensitivity of the break-even point to anticipated future maintenance cost increases for analog systems. For a $100 million modernisation programme, the break-even point is 1.5 to 6.5 years after the completion of a phased installation when maintenance cost increases are in the range of 5 per cent to 10 per cent per year. The $100 million investment is levelled over the time frame of the phased replacement.

Figure 3 shows how a phased replacement programme maximises the value of the capital investment and reduces the break-even point. In effect, substantial savings accrue more quickly during, and immediately after, the completion of the installation.

In almost all cases, the keys to obtaining cost benefits are projected to be standardisation on a few I&C systems platforms for future replacements. Additional cost benefits come from cost-effective, phased modernisation plans supplemented by an integrated I&C and information technology plan, and plant-wide staffing optimisation.

Utilities must place greater emphasis on plant-wide I&C modernisation to support a plant’s remaining life objectives and to keep life extension options open. Plant specific plans should be considered in the light of today’s I&C and information technology integration to create an enterprise management system. A cost-benefit analysis can help plant operators evaluate a plant’s level of I&C modernisation as well as its impact on safety, plant reliability, plant-wide O&M costs, and power production.

Some projects

Utilities in the USA are charting their direction for installing digital I&C systems to replace vintage analog equipment.

For example, Wisconsin Electric Power is upgrading the Point Beach 1 and 2 plant process computer system, including the safety assessment system. Westinghouse is providing a functional equivalent of the existing system for the power plant and its training system, using state-of-the-art technology that will meet the plant’s needs into the 21st century.

Other utilities are selecting the optimum route for total plant modernisation, typically based on a 5 to 10 outage phased approach standardising on a single instrumentation and control platform. The South Texas Project, one of the largest instrumentation and control modernisation projects yet undertaken, is now complete. The new system, called the Integrated Control System, takes over the plant computer function and emergency response system and can be readily expanded in anticipation of future plant control requirements.

Meanwhile, in Sweden, Westinghouse recently began work on a comprehensive five-year programme to completely upgrade the instrumentation, control and information systems at Ringhals 2. This is the largest, most comprehensive modernisation programme ever undertaken and will further the goal of making Ringhals one of Europe’s safest, most environmentally excellent and cost competitive plants.