Patent Number: 
Section: claims

1. A transponder card for a nuclear reactor control rod drive control system, the control system comprising a control processor and a plurality of electrical devices operationally coupled to the control processor, said transponder card configured to: receive commands from the control processor;  energize an appropriate electrical device when commanded;  detect a failure in control circuitry of said transponder card;  send a failure alarm; and  remove power from an electrical device during a control circuitry failure event when there is no command to energize the electrical device. 2. A transponder card in accordance with  claim 1  wherein said transponder card is further configured to energize the appropriate electrical device during a control circuitry failure event when commanded. claim 1 3. A transponder card in accordance with  claim 1  wherein said transponder card is further configured to: claim 1 detect if an electrical device is energized when said transponder card has been commanded to energize the solenoid; and  detect if an electrical device is de-energized when said transponder card has been commanded to de-energize the electrical device. 4. A transponder card in accordance with  claim 1  further configured to: claim 1 receive a command word from the control processor; and  buffer the command word on to another transponder card located downstream from said transponder card. 5. A transponder card in accordance with  claim 4  wherein each said transponder card comprises a unique identification address and each said transponder card is configured to: claim 4 compare a command address embedded in the command word with said identification address of said transponder card;  decode command bits of the command word to energize the appropriate electrical device when the command address compares with said transponder card identification address; and  transmit an acknowledge word to another transponder card located upstream from the transponder card. 6. A transponder card in accordance with  claim 1  further configured to generate an acknowledge word comprising: claim 1 a transponder identification address;  electrical device activity bits;  electrical device status bits; and  transponder trouble bits. 7. A transponder card in accordance with  claim 5  further configured to receive the following inputs: claim 5 command words from an upstream transponder card or the control processor;  acknowledge words from a downstream transponder card; and  electrical device status. 8. A transponder card in accordance with  claim 1  further configured to output the following: claim 1 command words to a downstream transponder card;  acknowledge word to an upstream transponder card or the control processor;  switched AC voltage to the electrical devices; and  AC voltage to a downstream transponder. 9. A nuclear reactor control rod drive control system, the nuclear reactor comprising a plurality of control rods, said control system comprising: a control processor;  a control rod drive configured to be connected to a control rod; and  an hydraulic control unit connected to said control rod drive, said hydraulic control unit comprising at least one solenoid, at least one directional control valves, and at least one transponder card, each said solenoid connected to one of said at least one directional control valve, each transponder card operationally coupled to said control processor and configured to:  receive commands from said control processor;  energize an appropriate solenoid when commanded by said control processor;  detect a failure in control circuitry of said transponder card;  send failure alarm to said control processor; and  remove power from a solenoid during a control circuitry failure event when there is no command to energize said solenoid. 10. A control system in accordance with  claim 1  wherein said transponder card is further configured to energize the appropriate electrical device during a control circuitry failure event when commanded. claim 1 11. A control system in accordance with  claim 9  wherein said transponder card is further configured to: claim 9 detect if a solenoid is energized when said transponder card has been commanded to energize said solenoid; and  detect if a solenoid is de-energized when said transponder card has been commanded to de-energize said solenoid. 12. A control system in accordance with  claim 9  further comprising at least one cluster of transponder cards, said transponder cards configured to: claim 9 receive a command word from said control processor; and  buffer the command word on to downstream transponder cards in the same cluster. 13. A control system in accordance with  claim 11  wherein each said transponder card comprises a unique identification address and each said transponder card is configured to: claim 11 compare a command address embedded in the command word with said identification address of said transponder card;  decode command bits of the command word to energize the appropriate directional control valve solenoid when the command address compares with said transponder card identification address; and  transmit an acknowledge word to the next upstream transponder card. 14. A control system in accordance with  claim 9  wherein said transponder card is configured to generate an acknowledge word comprising: claim 9 a transponder identification address;  directional valve activity bits;  hydraulic control unit status bits; and  transponder trouble bits. 15. A control system in accordance with  claim 9  wherein said transponder card is configured to receive the following inputs: claim 9 command words from an upstream transponder card or said control processor;  acknowledge words from a downstream transponder card; and  hydraulic control unit status. 16. A control system in accordance with  claim 9  wherein said transponder card is configured to output the following: claim 9 command words to a downstream transponder card;  acknowledge word to an upstream transponder card or said control processor;  switched AC voltage to said directional control valve solenoids; and  AC voltage to a downstream transponder. 17. A control system in accordance with  claim 9  wherein each said transponder card is operationally coupled via serial digital electronic communication to said control processor. claim 9