Patent Number: 050911392
Section: claims

1. A method of blocking in real time power increases on a reactor core as a function of minimum critical power ratio having discrete monitored rod bundle groups comprising the steps of: providing initial local power range monitor readings to obtain reactor local power data in all core discrete monitored rod bundle groups via a plurality of vertical strings of local power range monitors, each string including a plurality of power monitors disposed at differing elevations:  providing control rod position data from a group of control rods having positions of penetration with respect to said rod bundle group for the control of nuclear reaction in said rod bundle group:  providing initial flow rate through said reactor core:  providing core average power data in the said reactor core:  utilizing said core average power data and said initial flow rate to determine operating limit minimum critical power ratio;  utilizing a reactor thermal limit output model to determine the worst initial regional minimum critical power ratio for said rod bundle group,  downloading the worst initial regional critical power ratio from the computing model to memory;  looking up at least one constant which is predetermined as a function of positions of withdrawal of said control rod, said constant constituting a bounding, substantially worst case scenario for all control rod withdrawals from said rod bundle groups;  computing a setpoint for said local power range monitor output based on said constant, said operating limit minimum critical power ratio, said initial local power range monitor reading, and said worst case initial regional minimum critical power ratio:  comparing said instantaneous local power range monitor to said setpoint: and  blocking said power increase responsive to violations of said setpoint.  utilizing said reactor thermal limit output model to determine the worst initial regional minimum critical power ratio for said rod bundle group  looking up at least one second constant which is a predetermined function of positions of withdrawal of said control rod, said constant constituting a bounding worst case scenario for all control rod withdrawals from said rod bundle groups;  utilizing said core average power data and said flow rate to determine safety limit minimum critical power ratio;  computing a second setpoint for local power range monitor output based on said second constant, said safety limit minimum critical power ratio, said initial local power range monitor reading and said worst case initial regional minimum critical power ratio;  comparing said instantaneous local power range monitor to said second setpoint;  and, blocking said power increase responsive to violations of said second setpoint.  said step of comparing includes comparing said instantaneous local power range monitor to said setpoint for each and all of said rod bundle groups.  providing reactor local power data in all core discrete monitored rod bundle groups via a plurality of vertical strings of local power range monitor, each string including a plurality of monitors disposed at differing elevations;  providing control rod position data from a group of control rods having positions of penetrations with respect to said rod bundle group for the control of nuclear reaction in said rod bundle group;  providing initial flow rate through said reactor core;  providing core average power data in the said reactor core;  utilizing said core average power data and said initial flow rate to determine operating limit maximum linear heat generation rate;  utilizing a reactor thermal limit output model to determine the worst initial regional maximum linear heat generation rate for said rod bundle group;  downloading said worst case initial regional maximum linear heat generation rate from the computing model to memory;  looking up at least one constant which is a predetermined function of withdrawal of said control rod; said constant constituting a bounding worst case scenario for all said control rod withdrawals relative to a ratio of said local power data ratio and said worst regional maximum linear heat generation rate ratio for a selected elevation of said rod bundle group;  computing a setpoint for said local power range output based on said constant, said operating limit maximum linear heat generation rate, said initial local power range monitor reading and said worst case initial regional maximum linear heat generation rate;  comparing said instantaneous local power range monitor to said setpoint; and,  blocking said power increase responsive to violations of said setpoint.  providing reactor local power data in all discrete monitored rod bundle groups at selected elevations from a plurality of vertical strings of local power range monitor, each string including a plurality of power monitors disposed at said selected elevations;  providing control rod position data from a group of control rods having positions of penetrations with respect to said rod bundle group for the control of nuclear reaction in said rod bundle group;  providing initial flow rate through said reactor core;  providing core average power data in the said reactor core;  utilizing said core average power data and said initial flow rate to determine operating limit maximum average planar linear heat generation rate;  utilizing a reactor thermal limit output model to determine the worst initial regional maximum average planar linear heat generation rate for said rod bundle group;  downloading the worst initial regional maximum average planar linear heat generation rate;  looking up at least one constant which is predetermined as a function of positions of withdrawal of said control rod; said constant constituting a bounding worst case scenario for all control rod withdrawals relative to a ratio of said local power data ratio and said worst regional maximum average planar linear heat generation rate ratio for a selected elevation of said rod bundle group;  computing a setpoint for said local power range monitors output based on said constant, said operating limit maximum average planar average linear heat generation rate, said initial local power range monitor reading and said worst case initial regional maximum average planar linear heat generation rate;  comparing said instantaneous local power range monitor reading to said setpoint; and,  blocking said power increase responsive to violations of said setpoint.  providing initial local power range monitor readings to obtain reactor local power data in all core discrete monitored rod bundle groups via a plurality of vertical strings of local power range monitors, each string including a plurality of power monitors disposed at differing elevations;  providing control rod position data from a group of control rods having positions of penetration with respect to said rod bundle group for the control of nuclear reaction in said rod bundle group;  providing initial flow rate through said reactor core;  providing core average power data in said reactor core;  utilizing said core average power data and said initial flow rate to determine operating limit minimum critical power ratio;  utilizing a reactor thermal limit output model to determine the worst initial regional minimum critical power ratio for said rod bundle group;  downloading the worst initial regional minimum critical power ratio from the computing model to memory;  looking up at least one constant which is a predetermined function of said initial flow rate and said instantaneous flow rate of the reactor core, said constant constituting a bounding case relative to a ratio of said local power data ratio and a ratio of said critical power ratio, for all rod bundle groups under a plurality of power and flow conditions;  computing a setpoint for said local power range monitor output based on said constant, said operating limit minimum critical power ratio, said initial local power range monitor reading and said worst case initial regional minimum critical power ratio;  comparing said instantaneous local power range monitor to said setpoint; and,  blocking said power increase responsive to violations of said second setpoint.  utilizing said reactor thermal limit output model to determine the worst initial regional minimum critical power ratio for said rod bundle group;  looking up at least one second constant which is a predetermined function of positions of withdrawal of said control rod, said constant constituting a bounding worst case scenario for all control rod withdrawals from said rod bundle groups;  utilizing said core average power data and said flow rate to determine safety limit minimum critical power ratio;  computing a second setpoint for local power range monitor output based on said second constant, said safety limit minimum critical power ratio, said initial local power range monitor reading and said worst case initial regional minimum critical power ratio;  comparing said instantaneous local power range monitor to said second setpoint;  and blocking said power increase responsive to violations of said setpoint. 2. The process of claim 1 and wherein said utilizing step includes: 3. The process of claim 1 and wherein said blocking said power increase responsive to violations of said setpoint includes a step of blocking rod withdrawal. 4. The process of claim 1 wherein said step of computing a setpoint includes computing a setpoint for each and all of said rod bundle groups; and 5. A method of blocking in real time power increases on a reactor core as a function of maximum linear heat generation rate having discrete monitored rod bundle groups comprising the steps of; 6. The process of claim 5 wherein said blocking said power increase responsive to violations of said setpoint includes the step of blocking rod withdrawal. 7. The process of claim 5 wherein said blocking said power increase responsive to violations of said setpoint includes the step of blocking flow change. 8. The process of claim 7, wherein for flow change, the setpoint and the algorithm determining said setpoint are valid power block functions. 9. A method, as claimed in claim 5, wherein said step of comparing comprises comparing said instantaneous local power range monitor to said setpoint for each of different selected elevations of each and all of said rod bundle groups. 10. A method of blocking in real time power increases on a reactor core as a function of maximum average planar linear heat generation rates within a reactor core having discrete monitored rod bundle groups comprising the steps of; 11. A method, as claimed in claim 10, wherein said step of comparing comprises comparing said instantaneous local power range monitor reading to said setpoint for each of different selected elevations of each and all of said rod bundle groups. 12. A method, as claimed in claim 10, wherein said step of blocking said power increase comprises blocking withdrawal of said control rods. 13. The process of claim 10 wherein said blocking said power increase responsive to violations of said setpoint includes the step of blocking flow change. 14. The process of claim 13, wherein for flow change, the setpoint and the algorithm determining said setpoint are valid power block functions. 15. A method of blocking in real time power increases on a reactor core as a function of minimum critical power ratio having discrete monitored rod bundle groups comprising the steps of; 16. The process of claim 15 and wherein said utilizing step includes: 17. A method, as claimed in claim 15, wherein said step of comparing comprises comparing said instantaneous local power range monitor to said setpoint for each of said rod bundle groups. 18. A method, as claimed in claim 15, wherein said step of blocking said power increase responsive to violations of said setpoint includes the step of blocking flow change.