The 16th Annual Joint ISA POWID/EPRI Controls and Instrumentation Conference—also known as the
49th Annual POWID Symposium—was held this June in San Jose, Calif. Many of the trends driving this important aspect of power generation were on full display in technical sessions with titles such as Power Plant Control Systems, Power Plant Instrumentation, Data Management, and C&I Technologies. Several papers and presentations described new and innovative control techniques that more than a few of the 200 attendees surely found worthy of further discussion with their plant colleagues and managers.
Nothing, however, seemed to sound alarms more than the sad state of digital controls at U.S. nuclear plants. In a session dedicated to this topic, Jerry Mauck—formerly of the Nuclear Regulatory Commission and now a consultant—summed up activities in the field (actually, the lack thereof) with a question: "Is there a digital impasse?"
The question proved rhetorical. As Mauck explained:
- U.S. nuclear plants are falling behind.
- There's no rush to retrofit aging systems.
- One flagship project involving two Midwestern plants died "a quick death."
- "No large-scale digital application has been implemented or accepted."
Nuclear neighbors
Yet nuclear plants in Korea, China, Taiwan, Finland, the Czech Republic, France, and other countries have digital-based safety systems. Despite the numerous benefits of digital controls, Mauck conceded that finding projects with favorable cost/benefit ratios is difficult.
John Stevens, of Doosan/HF Controls Corp. (Addison, Texas), then described how different the situation is in the Republic of Korea. By 2010, 12 nuclear plants will have digital controls there, while the plants to be built later will use "soft" controls. Shin Kori 3-4, for example, will have total soft control for the nuclear steam supply system and balance of plant. Construction is expected to begin in 2010.
Stevens noted that standardization guides all new plant designs in Korea. Yet no off-the-shelf control systems can meet the specifications put forth by Korea Power Engineering Co. Although safety and non-safety systems are still isolated in Korean control system designs, data still are wheeled between them. An interesting feature of the Korean design philosophy is that engineering must be able to remotely guide plant operators through any emergency. Korea's nuclear industry demands that control system vendors be willing to support their system for 25 years to warrant consideration.
Not everything is stalled in the U.S., however, as Larry Bethel of St. Louis–based Emerson Process Management reminded the audience. For example, by upgrading a feedwater regulator valve at its Fort Calhoun station to digital control, Omaha Public Power District reduced the valve's setup and calibration time by a factor of four while cutting 40 man-hours of labor from the job. The operational benefit: The steam generator level at Fort Calhoun is now much more stable. On an overall basis, the retrofit has saved the plant more than $200,000 annually.
Another example cited by Bethel was Edison International's $800,000 annual saving at its San Onofre Nuclear Generating Station, the result of having switched to digital positioners, changing out valve trims, and retuning controllers on feedwater heater control valves. A third he described was a similar retrofit of feedwater regulator control valves at Florida Power Corp's Crystal River station. Bethel was quick to note that these plants have yet to fully harness the diagnostic capabilities of their new digital controls.
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