Wood

As indicated in the April issue of Nuclear News, development of advanced reactor concepts heavily emphasizes small modular reactors and microreactors. Promised features, such as capital cost savings, plant system simplification, implementation flexibility, and favorable operational responsiveness with passive safety behavior, all promote small reactors as desirable, non-­­carbon-­­emitting power sources to help satisfy future energy needs. In spite of the favorable up-­­front economics compared to large nuclear reactors, SMRs and microreactors do not provide the benefit of economy of scale that typically compensates for the high staffing demands associated with traditional, labor-intensive operations and maintenance (O&M) practices in the nuclear industry. To avoid the prospect that high staffing levels relative to unit power production will lead to unsustainable O&M costs for small reactors, a significantly higher degree of automation, to the point of near autonomy, is necessary. Essentially, the economy of automation is needed to offset the loss of economy of scale.

Online monitoring (OLM) technology can be used in nuclear power plants as an analytical tool to measure sensor drift during plant operation and thereby identify the sensors whose calibration must be checked physically during an outage. The technology involves a procedure to (1) retrieve redundant sensor measurements from the process computer or through a separate data acquisition system, (2) calculate the average of these measurements and the deviation of each sensor from the average, and (3) identify any sensor that has deviated beyond its predetermined monitoring limit.

The pace of advances in nuclear instrumentation, controls, and human-machine interface technologies and their deployment has increased in recent years and are essential to achieving the enhanced safety and improved economics of advanced reactors.

As the U.S. nuclear industry moves into plant life extension and subsequent license renewals, the modernization of safety instrumentation and control (I&C) systems holds significant potential to transform plant operations. Automated system diagnostics, equipment health monitoring, and performance indications reduce the need for manual surveillance activities and enable condition-based maintenance, resulting in improved system reliability and reduced maintenance costs. Despite these benefits, adoption of digital I&C systems for safety-related applications across the domestic nuclear fleet has been slow. U.S. nuclear power plants that do choose to embrace the transition from analog to digital are in good company; international plants have successfully implemented digital safety systems for more than a decade. Furthermore, digital safety systems are also the first choice of the growing small modular reactor (SMR) and advanced reactor (AR) communities.