Making the most of a forced outage
MAKING THE MOST OF A FORCED OUTAGE
By Ron Wallace, Manager, Utility Industry Marketing, Project Software& Development, Inc.
Although American power plants are aging, the frequency and duration of forced outages in fossil plants has gone down dramatically over the past few years. According to Ronald J. Niebo, Director of the Generating Availability Data System at the North American Electric Reliability Council (NERC), the Forced Outage Rate (FOR) in fossil plants is down from 7.53% in 1985 to 5.73 in 1988. (FOR is the percentage of time a unit was unavailable due to forced outages during the time when it was expected to be in service.)
For the same period, the forced outage rate for nuclear plants, which are typically newer facilities, went up from 14.65% in 1985 to 17.73 in 1986 before starting a downward trend, ending at 11.56% in 1988.
Regardless of fuel type, forced outages can and do occur. And managers must be prepared to take advantage of these shutdowns when they happen.
There are several measures plant managers can take to prevent forced outages from happening. But it is also important to review methods that will enable managers to make optimal use of time and resources the next time they find themselves in an unscheduled outage. They must begin by identifying areas of greatest vulnerability in their plants’ operations so they can anticipate when and why a forced outage is likely to occur. They must also develop a sound process for prioritizing additional maintenance tasks to be done in the event of a forced outage. Once priorities are established, they can develop a series of “what-if” schedules for a variety of outage scenarios.
With these schedules as a blueprint, they can explore a variety of inventory and staffing options to see which promotes the most cost-effective “readiness.”
Attention to Maintenance and Quality Improvement Pays Off
A wide variety of maintenance initiatives help to account for the diminished rate of forced outages.
One such example is the Boiler Tube Failure Reduction Program conducted by Electric Power Reliability Institute (EpRI). Boiler tube failures area major cause of fossil plant availability loss, with repeat tube failures accounting for about half of all boiler tube failures. However, since implementing EPRI‘s boiler availability improvement guidelines (RP 1890) three years ago, the members of the Utility Boiler Tube Failure Reduction Group (UBTFRG) have reduced equivalent availability losses by 1%. Although it may sound insignificant, this 1% represents a 50% improvement over the national average, and is expected to account for an annual saving of $46.5 million over the next ten years for the UBTFRG member utilities.
In all nuclear plants, efforts are underway to lower the number of reactor trips, Utilities like Southern California Edison have implemented a “Trip Reduction Program.” By taking greater care when doing surveillance testing, by better planning and controlling work on operating systems, and taking a variety of other common-sense measures, SCE now has one of the lowest rates of reactor trips.
However, despite everyone's best efforts, forced outages continue to occur. What is striking is that, along with a decline in frequency of occurrence, there was a decline in forced outage hours in 1988. According to industry figures, the average duration of forced outages at American nuclear power plants decreased by 9% from 1987 to 1988. Does this mean that forced outage activities are being accomplished more effectively, or that fewer are being done? The answer appears to be “both of the above.”
Doing Less Work in Less Time
Historically, the goal of project and maintenance planning was to accomplish the greatest amount of work in the least amount of time. That goal remains, but it's been refined by a growing understanding of how to do the right work, the work that actually needs doing, in the least amount of time.
Florida Power & Light (FPL) uses a predictive maintenance approach to meet this end. They use a variety of diagnostic techniques to help determine what work does and does not have to be performed. FPL engineers gather and analyze data most indicative of how well a given piece of equipment is operating. This enables them to assess not only what does not work but what does, and to plan preventive maintenance not just on the basis of elapsed time, but on the basis of the equipment's actual stress and vulnerability.
These techniques do more than help FPL decide what work can be deferred. They also tend to reduce the complexity of the repairs that are required, because engineers can detect problems early and determine root causes before they are obscured by secondary breakdowns.
A Good Decision-Making Process is Critical
These decisions about what to do and what to defer should not be made on the spot. Rather, whenever possible, they should be made before the forced outage even occurs. Utilities around the country are implementing new procedures to ensure that this decision-making process is systematic, informed, and timely.
For example, at Southern California Edison's San Onofre Nuclear Generating System, preparation for forced outages is an ongoing effort. Lists of potential work are maintained in their Automated Maintenance Order Control System for a few scenarios. When a forced outage occurs, the lists are reviewed for applicability and combined with the repair work for the problem that caused the outage, This is the forced outage scope. The company stores standard outage plans, including shutdown and start-up logic, and repeated activities, in its project management software. The outage scope is incorporated into a standard outage plan to produce a plan for the outage. The software is used to schedule the work orders and the activities of the shutdown and start-up.
Willis G. Frick, a supervisor of Outage Management at the facility says, “The combination of prepared lists of work items and the pre-established standard outage sequences permits us to develop a forced outage plan in the first few days of an outage.”
Job Tickets Are the Ticket
Using resource availabilities as their starting point, Metropolitan Edison has also developed a systematic means of determining how to optimize forced outages at their two fossil stations. Planners first allocate the maintenance personnel needed to repair whatever failure caused the unit to go off line. Then, after also allocating the personnel needed to keep their other units running, they end up with a net number of available resource hours to support other “non-emergency” activities during a forced outage. With this realistic resource schedule in hand, they choose activities from a list of pre-coded “job tickets” for forced outages, which are detailed descriptions of maintenance work, including work relating to capital projects and to Operation and Maintenance projects.
Formalized Procedures at RG&E
At Rochester Gas & Electric's R.E. Ginna Nuclear Station, Dick Marchionda, Director of Outages, recently formalized the procedure for forced outages and power reductions, They have eight “contingency networks” for the most likely types of forced outages, developed with PM system on the station's VAX computer. Although the unit has a low forced outage rate, it is 20 years old, and can have power reduction outages of 50% two or three times a year, typically for condenser tube leaks.
Marchionda reports this approach definitely helps get the job done faster. The contingency schedules store the shortest historical time for each type of outage. “This gives maintenance crews something to shoot for—trying to beat their previous best,” Marchionda says.
All of the above-mentioned outage planners and engineers have something in common. All are integrating the previously segregated disciplines of maintenance management, project management, and statistical quality control. At the same time, the software industry is trying to keep pace with and establish standards for these integrated applications.
Expanding Information Systems
Engineering, operations and maintenance, project management, materials control, finance, administrative, and personnel functions are working more and more in concert, and this must be reflected in the software these disciplines use.
The computer software industry is moving toward standards that will help these systems connect with each other and provide integrated corporate solutions. Some of the current trends include:
- SQL (Structured Query Language) Databases, offering ease of development and connectivity to other corporate systems;
- Mainframe as Data Repository, with the mainframe becoming a huge server in many organizations with the clients being users working on PCs and workstations—exchanging data with this host; and
- OSI (Open Systems Interconnect) Network Standards, allowing data interchange among various computers—the OSI seven-level “layered” specification handles high-level software interface protocols, which enables integrated applications to eliminate “islands of information.”
In the meantime, outage managers can do a alot with the took at hand to optimize their unanticipated downtime. They should routinely generate feasible forced outage schedules based on their maintenance backlog and the required and available resources. These schedules and the associated cost data can form the basis for an economic evaluation. allowing managers to determine the most cost-beneficial time to perform this work. For example, in the spring, when power demand is down, it maybe worth it to complete additional backlog maintenance items and prolong the shutdown. This would be an alternative to shutting the plant down during summer or winter peaks when it is more costly to purchase replacement power.
Planning for Forced Outages
How do you plan for a forced outage? Basically, it is the preplanning process that allows utility managers Continued on page 58
Continued from page 32 to take greatest advantage of a forced outage. For example, as soon as a Maintenance Request (MR) is submitted, the process to plan and schedule this MR should begin. Maintenance planners should generate the work orders needed to perform the repair, produce tags to physically hang on machinery, and necessary sign-off sheets.
An “order of magnitude” estimate should be done to establish priority. Finally, the fully planned MR, including special needs such as scaffolding or lifted tools, should be completed. That way, in the event of an outage, maintenance crews will be ready to go.
Better than optimizing forced outages is to not have any. This is a goal worth striving for, and one that requires an ongoing commitment to spending money on maintenance, even though it may take at least a couple of years for the investment to be rewarded. But unless and until this utopian, forced-outage-free state is achieved, managers will have to bring non-traditional approaches to routine tasks. In this way, they'll make the most out of their outages.
Ron Wallace joined Project Software &Development, Inc. in 1983 and is currently Manager of Utility Industy Marketing, responsible for marketing PROJECT/2, QWIKNET Professional and APECS 8000 to some 50 telecommunication, gas, electric and water utilities.
Ron is active in PMI and AACE and conducts PSDI‘s annual PROJECT/2 Utility Users Group Conference. Prior to joining PSDI, he worked for Gilbert Associates, Inc. and Stone & Webster Engineering Corporation. He has a Bachelor of Science degree in Industrial Engineering from. Northwestern University.