Industry Leaders in Plant-Specific Neutron Fluence Evaluations
Measured Uncertainty Recapture (MUR)
MUR refers to the process of reducing conservatism in the reactor thermal power limits by crediting improved measurement accuracy, primarily in feedwater flow and thermal power determination. In short, if you can measure reactor power more accurately, you do not need as much built-in safety margin and you can "recapture" that margin for increased power output. When uncertainties in measurement systems improve from a +/-2% uncertainty to closer to +/- 1% uncertainty, a plant operator can use that margin to increase the thermal rated power of the reactor with more confidence without violating licensing or regulatory requirements. All MUR's are subject to NRC review and approval.
Stretch Power Uprate (SPU)
An SPU is a moderate increase in a nuclear power plant's licensed thermal power, usually on the order of 2% to 7% above the original licensed thermal power. Rather than an MUR which relies mainly on improved measurement uncertainties, an SPU is supported by re-analysis and upgrades to thermal-hydraulics and potential minor plant modifications. As opposed to Extended Power Uprates (EPUs), SPUs have far less associated costs and quicker implementation in achieving desired power uprates. SPUs will require NRC license amendment requests (LARs) and involves revisions to other licensing documents.
Extended Power Uprate (EPU)
An EPU is a large increase in a nuclear power plant's licensed thermal power, usually on the order of 15% to 20% above the original licensed thermal power. EPUs are more complex than SPUs in that they require real, physical capability increases across multiple plant systems. Some potential costly hardware modifications would be turbine upgrades, feedwater pumps, heater or condenser modifications, high-capacity transformers, and others. Nearly all safety systems would require re-analyses to ensure safe operation during the licensing period. All EPUs will be subject to full NRC review and approval and may take as long as 5 years to complete. While costly, implementing an EPU will allow plants to massively increase power output without having to build a new generating unit and will help improve economic competition.
MELLLA+
Maximum Extended Load Line Limit Analysis Plus (MELLLA+) is used primarily in Boiling Water Reactors (BWRs) and allows the reactor to operate at lower core flow conditions while maintaining higher power conditions. Load line refers to a BWRs relationship between power and core flow. Original limitations were imposed that linked this relationship more tightly. However, with the advancement of fuel designs and advanced analytics, operators are able to manipulate these variables more freely in response to operational needs. MELLLA+ does not result in a power increase like an uprate would. It simply increases where you are allowed to operate that power. Implementing a MELLLA+ will require operators to demonstrate safety of operation and stability considerations through a LAR, revised power-flow map, and other avenues.