A method for protecting a nuclear reactor core from fuel damage due to thermal hydraulic instability in an extended operating domain for an extended power uprate, comprising: generating a power-flow operating map, comprising: establishing a natural circulation curve; establishing a Maximum Extended Load Line Limit Analysis (MELLLA) control rod line; and establishing a higher MELLLA+ control rod line positioned above the MELLLA control rod line; forming a MELLLA+ domain above the MELLLA control rod line, up to the higher MELLLA+ control rod line; allowing operation in the MELLLA+ domain and characterized by calculating by a thermal hydraulic code simulator a thermal hydraulic stability limit; determining a power level that corresponds to the thermal hydraulic stability limit at different core flow rates; providing an Average Power Range Monitor (APRM) flow-biased scram line; lowering the APRM flow-biased scram line to below the thermal hydraulic stability limit; and actuating an APRM-based trip system when core flow is decreased resulting from a flow decrease transient and power increases above the power level to provide an automatic anticipatory scram or a selected rod insertion trip to cause a power reduction. generating a power-flow operating map, comprising: establishing a natural circulation curve; establishing a Maximum Extended Load Line Limit Analysis (MELLLA) control rod line; and establishing a higher MELLLA+ control rod line positioned above the MELLLA control rod line; forming a MELLLA+ domain above the MELLLA control rod line, up to the higher MELLLA+ control rod line; allowing operation in the MELLLA+ domain and characterized by calculating by a thermal hydraulic code simulator a thermal hydraulic stability limit; determining a power level that corresponds to the thermal hydraulic stability limit at different core flow rates; providing an Average Power Range Monitor (APRM) flow-biased scram line; lowering the APRM flow-biased scram line to below the thermal hydraulic stability limit; and actuating an APRM-based trip system when core flow is decreased resulting from a flow decrease transient and power increases above the power level to provide an automatic anticipatory scram or a selected rod insertion trip to cause a power reduction. establishing a natural circulation curve; establishing a Maximum Extended Load Line Limit Analysis (MELLLA) control rod line; and establishing a higher MELLLA+ control rod line positioned above the MELLLA control rod line; forming a MELLLA+ domain above the MELLLA control rod line, up to the higher MELLLA+ control rod line; allowing operation in the MELLLA+ domain and characterized by calculating by a thermal hydraulic code simulator a thermal hydraulic stability limit; determining a power level that corresponds to the thermal hydraulic stability limit at different core flow rates; providing an Average Power Range Monitor (APRM) flow-biased scram line; lowering the APRM flow-biased scram line to below the thermal hydraulic stability limit; and actuating an APRM-based trip system when core flow is decreased resulting from a flow decrease transient and power increases above the power level to provide an automatic anticipatory scram or a selected rod insertion trip to cause a power reduction.