Patent Number: 
Section: claims

1. An apparatus comprising:a circuit or digital processor configured to adjust reactor power generated by a pressurized water reactor (PWR) by:(i) changing an average primary coolant temperature of primary coolant of the PWR by adjusting at least one of flow rate and temperature of feedwater into a steam generator that is in thermal communication with the PWR, and(ii) adjusting a pressurizer water level setpoint of the PWR upward if the change (i) is to a higher average primary coolant temperature and downward if the change (i) is to a lower average primary coolant temperature. 2. The apparatus as set forth in claim 1, wherein:the changing (i) comprises increasing feedwater flow rate into the steam generator in thermal communication with the PWR, andthe adjusting (ii) comprises adjusting the pressurizer water level setpoint of the PWR downward. 3. The apparatus as set forth in claim 1, wherein:the changing (i) comprises decreasing feedwater flow rate into the steam generator in thermal communication with the PWR, andthe adjusting (ii) comprises adjusting the pressurizer water level setpoint of the PWR upward. 4. The apparatus as set forth in claim 1, wherein:the changing (i) comprises increasing temperature of feedwater being fed into the steam generator in thermal communication with the PWR, andthe adjusting (ii) comprises adjusting the pressurizer water level setpoint of the PWR upward. 5. The apparatus as set forth in claim 1, wherein:the changing (i) comprises decreasing temperature of feedwater being fed into the steam generator in thermal communication with the PWR, andthe adjusting (ii) comprises adjusting the pressurizer water level setpoint of the PWR downward. 6. The apparatus as set forth in claim 1, wherein the steam generator in thermal communication with the PWR is an integral steam generator disposed inside a pressure vessel of the PWR. 7. The apparatus as set forth in claim 1, wherein a magnitude of the adjusting (ii) is a function of the changing (i). 8. The apparatus as set forth in claim 1, wherein the adjusting (ii) further includes adjusting upper and lower pressurizer water level limits to track with the adjusted pressurizer water level setpoint, and the circuit or digital processor is further configured to perform a method comprising:adding makeup water to a reactor coolant system (RCS) of the PWR conditional upon a monitored pressurizer water level of the PWR decreasing below the adjusted pressurizer water level lower limit; andperforming letdown of water from the RCS of the PWR conditional upon the monitored pressurizer water level of the PWR increasing above the adjusted pressurizer water level lower limit. 9. A pressurized water reactor (PWR) comprising:a pressure vessel;a reactor core disposed in the pressure vessel;an integral or external pressurizer;primary coolant disposed in the pressure vessel and heated by operation of the reactor core, the primary coolant not including a soluble boron poison in the primary coolant; andan apparatus as set forth in claim 1. 10. A method comprising:operating a pressurized water reactor (PWR) comprising a nuclear reactor core contained in a pressure vessel to generate electric power wherein the operating includes operating a pressurizer to regulate pressure in the pressure vessel of the PWR; andduring the operating:performing a PWR power adjustment comprising adjusting at least one of flow rate and temperature of secondary coolant flowing into a steam generator of the PWR; andadjusting a pressurizer water level setpoint based on a predicted direction and magnitude of change of a pressurizer water level of the PWR predicted to result from the performing the PWR power adjustment. 11. The method as set forth in claim 10, wherein:the performing a PWR power adjustment comprises one of increasing and decreasing the secondary coolant flow rate; andthe adjusting of the pressurizer water level setpoint comprises one of lowering and raising the pressurizer water level setpoint based on a predicted decrease or increase in primary coolant volume in a reactor coolant system (RCS) of the PWR predicted to result from the increasing or decreasing of the secondary coolant flow rate. 12. The method as set forth in claim 10, wherein:the performing a PWR power adjustment comprises one of increasing and decreasing the secondary coolant flow rate into an integral steam generator of the PWR; andthe adjusting of the pressurizer water level setpoint comprises one of lowering and raising the pressurizer water level setpoint based on a predicted decrease or increase in primary coolant volume in a reactor coolant system (RCS) of the PWR predicted to result from the increasing or decreasing of the secondary coolant flow rate through the integral steam generator of the PWR. 13. The method as set forth in claim 10, wherein:the performing a PWR power adjustment comprises one of increasing and decreasing the temperature of secondary coolant flowing into the steam generator of the PWR; andthe adjusting of the pressurizer water level setpoint comprises one of raising and lowering the pressurizer water level setpoint based on a predicted increase or decrease in primary coolant volume in a reactor coolant system (RCS) of the PWR predicted to result from the increasing or decreasing of the temperature of secondary coolant flowing into the steam generator of the PWR. 14. The method as set forth in claim 10, wherein:the performing a PWR power adjustment comprises one of increasing and decreasing the temperature of secondary coolant flowing into an integral steam generator of the PWR; andthe adjusting of the pressurizer water level setpoint comprises one of raising and lowering the pressurizer water level setpoint based on a predicted increase or decrease in primary coolant volume in a reactor coolant system (RCS) of the PWR predicted to result from the increasing or decreasing of the temperature of secondary coolant flowing into the integral steam generator of the PWR. 15. The method as set forth in claim 10, wherein the method does not include operating the PWR with a concentration of a soluble poison in a primary coolant of the PWR. 16. A pressurized water reactor (PWR) comprising:a pressure vessel;a reactor core disposed in the pressure vessel;an integral or external pressurizer;primary coolant disposed in the pressure vessel and heated by operation of the reactor core;an integral steam generator disposed in the pressure vessel and configured to convert secondary coolant in the form of feedwater into steam by heat transfer from the primary coolant heated by operation of the reactor core to secondary coolant in the steam generator;a feedwater valve arranged to control feedwater flow rate into the integral steam generator; anda controller configured to perform a PWR control method including the operations of (i) adjusting PWR power by operating the feedwater valve to increase or decrease feedwater flow rate and (ii) adjusting a pressurizer water level setpoint based on a predicted direction and magnitude of change of a pressurizer water level of the PWR predicted to result from the adjusting (i). 17. The PWR as set forth in claim 16, wherein the primary coolant does not include a soluble boron poison. 18. The PWR as set forth in claim 17, further comprising:an integral pressurizer. 19. The PWR as set forth in claim 16, wherein the controller is configured to perform the operation (ii) by:decreasing the pressurizer water level set point in correspondence with increasing the feedwater flow rate, andincreasing the pressurizer water level in correspondence with decreasing the feedwater flow rate. 20. A pressurized water reactor (PWR) comprising:a pressure vessel;a reactor core disposed in the pressure vessel;an integral or external pressurizer;primary coolant disposed in the pressure vessel and heated by operation of the reactor core, the primary coolant not including a soluble boron poison in the primary coolant;a controller configured to perform a method including the operations of:performing a PWR power adjustment; andadjusting a pressurizer water level set point based on a predicted direction and magnitude of change of a pressurizer water level of the PWR predicted to result from the performing the PWR power adjustment;a steam generator configured to bring the primary coolant into thermal communication with secondary coolant to transfer heat from the primary coolant to the secondary coolant to convert the secondary coolant to steam; anda feedwater valve arranged to control flow rate of the secondary coolant into the steam generator;wherein the controller is configured to perform a PWR power adjustment by operating the feedwater valve to increase or decrease the flow rate of secondary coolant into the steam generator.