Control concepts for nuclear ramjet reactors

Tory II-A, the first experimental reactor in the Pluto nuclear ramjet program, will be tested in late 1960 at the Nevada Test Site of the Atomic Energy Commission. The fundamental objective of Tory II-A is to demonstrate that a high power-density, high-temperature, air-cooled reactor can be successfully designed, constructed, and operated. This application places requirements on the reactor control system which are considerably more stringent than those found in previous reactor systems, both from the standpoint of radiation environment and system performance. To fulfill the system requirements a high-performance reactor control system has been designed and built; control actuation hardware has been developed which can withstand the high-radiation environment of Tory II-A. This actuation system features radiation-tolerant electrohydraulic components: actuators, servo-valves, solenoid valves, feedback transducers, accumulators and associated hydraulic components. To provide high reliability against undesired shutdowns while carrying out high power level transients, the Tory II-A control philosophy includes a new concept in reactor safety: reliance on a nonlocking, fast-reset safety system during accident situations. The fast-reset system acts so as to hold the programmed power level rather than initiating an irreversible "scram" action. A reactor "scram," if tolerated, could produce thermal shocks which would seriously damage the core components.