Turbogenerator flywheel for Alcator C-MOD

At peak performance the Alcator C-MOD experiment at MIT will require pulses of up to 500 MJ over a 5-s period. This will be supplied by a commercial alternator supplemented by a 75-ton flywheel. When spun at 1800 rpm, the alternator-rotor combination stores a total kinetic energy of 2000 MJ. The safety analysis for the system must address several concerns, including fracture. To this end an extensive fracture mechanics analysis of the flywheel is being conducted. At present the initial flaw distribution has been determined by ultrasonic and magnetic particle examination. Material samples will be heat-treated to duplicate the thermal histories and properties of various locations within the single-piece forging. A program of materials tests, including crack growth and fracture toughness, is being conducted for use in predicting the life of the flywheel