ON OPERATIONAL AND START-UP TRANSIENTS IN AN ACCELERATOR DRIVEN SYSTEMS

Accelerator Driven Systems (ADS) are subcritical nuclear reactor cores driven by external spallation neutron source. These systems are currently under investigation to be used as minor actinide burners and also as transmuters of long lived fission products. The subcriticality level plays an important rule in the control of the system. Low subcriticality level more source dominant is the system. In this paper one analyzes two transients to analyze the feedback effect on power of the Accelerator Driven Systems, since they cover a wide range of temperature variations. These operational transients are a beam interruption in power and a startup one, when the ADS are powered up from zero power to power operation. Numerical results shown that ADS can not reach the nominal operation temperatures if the systems operate next to critical ones. In a beam interruption transient systems are not affected if operated as critical ones.