Patent Number: 052176789
Section: claims

1. A gang control-rod controlling system for operating a plurality of control rods at the same time to attain a predetermined control rod pattern, wherein said system comprises: (a) first means storing a first sequence of control rod operations for operating a plurality of control rods at the same time to configure a first control rod pattern, a second sequence of control rod operations for operating a plurality of control rods at the same time to configure a second control rod pattern, and a third sequence of control rod operations for operating a plurality of control rods at the same time to exchange a control rod pattern between said first control rod pattern and said second control rod pattern; and  (b) second means for selecting one of said first to third sequences of control rod operations stored in said first means, and operating a plurality of control rods at the same time based on the selected sequence of control rod operations.  (a) a first step of previously storing a first sequence of control rod operations for operating a plurality of control rods at the same time to configure a first control rod pattern, a second sequence of control rod operations for operating a plurality of control rods at the same time to configure a second control rod pattern, and a third sequence of control rod operations for operating a plurality of control rods at the same time to exchange a control rod pattern between said first control rod pattern and said second control rod pattern; and  (b) a second step of selecting one of said first to third sequences of control rod operations stored in said first step, and operating a plurality of control rods at the same time based on the selected sequence of control rod operations. 2. A gang control-rod controlling system according to claim 1, wherein said second means includes means for inhibiting selection of said third sequence of control rod operations when reactor power is below a set value. 3. A gang control-rod controlling system according to claim 1, wherein said second means includes rod worth limiting means that functions when reactor power is below a set value whereby withdrawal of control rods is inhibited when reactivity worth of those control rods exceeds a predetermined range. 4. A gang control-rod controlling system according to claim 3, wherein said second means further includes means actuatable by an operator for selecting the group number of plural control rods to be operated at the same time, and when said reactor power is below the set value, said rod worth limiting means determines whether or not said control rod group number selected by the operator is in match with said selected sequence of control rod operations and, if the decision is no, inhibits output of said selected sequence of control rod operations. 5. A gang control-rod controlling system according to claim 1, wherein said second means includes first operating means actuatable by an operator for selecting one of said first to third sequences of control rod operations, second operating means actuatable by the operator for selecting the group number of plural control rods to be operated at the same time, third operating means actuatable by the operator for selecting insertion or withdrawal of plural control rods to be operated at the same time, sequence select means for selecting one of said first to third sequences of control rod operations stored in said first means that corresponds to the sequence of control rod operations selected by said first operating means, gang, control-rod select means for selecting position data, associated with control rods of the group number selected by said second operating means, from the sequence of control rod operations selected by said sequence select means, and control rod operation select means for determining, based on the selection by said third operating means, insertion or withdrawal of the plural control rods associated with the position data selected by said gang controlrod select means. 6. A gang control-rod controlling system according to claim 5, wherein said second means further includes means for, when said reactor power is below the set value, determining whether or not the control rod group number selected by said second operating means is in match with the sequence of control rod operations selected by said sequence select means and, if the decision is no, disabling said selected sequence of control rod operations. 7. A gang control-rod controlling system according to claim 1, wherein said first sequence of control rod operations includes first sequence data to configure a first type control rod pattern in which control rods inserted at a rated power comprise only those control rods arranged in the form of a checker board including a control rod at the core center, said second sequence of control rod operations includes second sequence data to configure a second type control rod pattern in which control rods inserted at the rated power comprise only those control rods arranged in the form of a checker board in which a control rod at the core center is not included, and said third sequence of control rod operations includes third sequence data in combination of a part of said first sequence data and a part of said second sequence data. 8. A gang control-rod controlling system according to claim 1, wherein each of said first to third sequences of control rod operations includes data comprising the group numbers of plural control rods to be operated at the same time in correspondence to coordinate values indicative of respective radial positions of the control rods belonging to each group number. 9. A gang control-rod controlling system according to claim 1, wherein said first sequence of control rod operations contains sequence data in which all control rods are divided into first to m-th groups in order of withdrawing the control rods, in the first to fourth groups including those control rods of about half the number of total control rods that are arranged in the form of a checker board and in which a control rod at the core center is not included, and the fifth to m-th groups including the remaining about half control rods; said second sequence of control rod operations contains sequence data in which all control rods are divided into first to n-th groups in order of withdrawing the control rods, the first to fourth groups including those control rods of about half the number of total control rods that are arranged in the form of a checker board including the control rod at the core center, and the fifth to n-th groups including the remaining about half control rods; and said third sequence of control rod operations contains sequence data in combination of the fifth to m-th groups in said first sequence of control rod operations and the fifth to n-th groups in said second sequence of control rod operations. 10. A reactor operation method for operating a plurality of control rods at the same time to attain a predetermined control rod pattern, wherein said method comprises: 11. A reactor operation method according to claim 10, wherein said second step selects one of said second and third sequences of control rod operations when reactor power is below a set value, and selects one of said first, second and third sequences of control rod operations when said reactor power is above the set value. 12. A reactor operation method according to claim 10, wherein said second step selects the group number of plural control rods to be operated at the same time in response to actuation by an operator, outputs said selected sequence of control rod operations only when said control rod group number selected by the operator is in match with said selected sequence of control rod operations when said reactor power is below the set value, and always outputs said selected sequence of control rod operations when said reactor power is above the set value.