PERFORMANCE DEGRADATION. Failure or degradation of a facility, process, system or component that reduces the reliability of critical components of the facility whose loss or degradation prevents the system from performing its intended function. Performance degradation does not include:
(1) A burned out power indicator light on a piece of radiation monitoring equipment which does not prevent the equipment from detecting elevated radiation levels and alarming as designed;
(2) A piece of equipment that is determined to be out of calibration on the conservative side (such as a low level alarm that alarms at a higher value than it should); or
(3) the temporary loss of a component where identical redundant components are maintained in operation and the minimum authorization bases is not compromised. SOURCE: US Department Of Energy
A Breakdown in a process component.