A review of limitations, upgrade strategies, and performance projections for nuclear power generation system uprates

Thermal power uprates are being pursued as a near-term route to expand U.S. dispatchable nuclear generation by extracting more electrical output from already-licensed pressurized-water reactors. For modest uprates, plants can often recover analytical margin with limited hardware changes, but uprates above ∼20% increasingly become a balance-of-plant throughput problem. More steam and feedwater must be moved through the same cycle while preserving pressure and temperature limits, moisture and vibration margins, condenser heat-rejection capability, and secondary-side hydraulic headroom. These coupled constraints—steam-path choking, turbine exhaust and moisture limits, condenser backpressure, and feedwater and condensate pump and valve margins—often dominate feasibility and shift uprate projects from incremental adjustments to major equipment modifications and integrated requalification. The novelty of this review lies in its synthesis of U.S. uprate experience and its presentation of large-uprate solutions within three balance-of-plant architectures: (1) parallel steam-conversion capacity, adds a supplemental turbine-generator train downstream of a main-steam manifold so the existing turbine train is not forced to accept the full incremental mass flow; (2) heat-balance shift, re-optimizes regenerative feedwater heating, extraction fractions, and terminal feedwater temperature so that a larger fraction of the added thermal input is converted to useful work with a smaller marginal increase in steam and feedwater flow; and (3) industrial steam diversion and cogeneration, routes a portion of steam to process heat applications and return condensate to the condenser or feedwater train, reducing conversion burden on constrained turbine and condenser systems. Across these pathways, the key technical requirement is an integrated, constraint-based evaluation that couples steam generator thermal hydraulics, turbine and condenser limits, pump and valve capacities, and plant controls to identify feasible operating regions and the minimum upgrade set. The paper concludes with research needs for validating uprate-scale models and for quantifying cost-benefit tradeoffs among the three architectures. Case histories are summarized to distinguish typical Stretch Power Uprate scope from Extended-Power-Uprate-driven replacements.