A system for monitoring stored spent fuel rods is provided, the system comprising: canisters containing the spent fuel rods; and temperature measuring means positioned on external surfaces of the canisters. Also provided is a method for monitoring stored spent fuel rods contained in canisters, the method comprising measuring temperature of the canisters at a plurality of external surfaces of each of the canisters, recording time of temperature differences between said external surfaces, determining time of oxidation initiation of the spent fuel rods based on the recording time, and preventing oxidation from occurring.