Patent ID: 6570949
Filing Date: 2003-05-27
Classification: G21C,Y02E

Abstract:
A method for testing whether fuel rods of fuel assemblies resting on a working base and under water, of a nuclear reactor are leaking, which comprises the steps of:fitting a common hood over all fuel assemblies of a first division of fuel assemblies, the first division containing at least a first group and a second group having in each case a plurality of the fuel assemblies, each of the first and second group including a first fuel assembly and a second fuel assembly; heating all fuel assemblies of the first division of fuel assemblies by passing a filling gas under the hood, for driving radioactive fission products out of a defective fuel rod contained in the fuel assemblies of the first division; subjecting the fuel assemblies belonging to the first group to a first common preliminary test and independently subjecting the second group to a second common preliminary test by continuously extracting samples of water and continuously degassing the water removed from an area around the fuel assemblies of the first division even during the heating resulting in gas; continuously recording a radioactivity of gaseous fission products contained in the gas being continuously released; carrying out the first common preliminary test by using a first device for extraction, a first device for degassing and a first device for recording the radioactivity in order to jointly test all the fuel assemblies belonging to the first group to determine if they are leaking; carrying out the second common preliminary test by using a second device for extraction, a second device for degassing and a second device for recording the radioactivity in order to jointly test all the fuel assemblies belonging to the second group to determine if they are leaking; performing an individual test of each of the fuel assemblies belonging to one of the first group and second group only if the first or second preliminary common test detects excessive radioactivity, carrying out the individual test using in each case a dedicated device for extraction, a dedicated device for degassing and a dedicated device for recording the radioactivity for each of the fuel assemblies, the dedicated device for extraction, the dedicated device for degassing and the dedicated device for recording the radioactivity provided for the individual test of the individual fuel assemblies already being in use for subjecting in each case the fuel assemblies belonging to one of the first and second group to the first and second common preliminary test; and heating the fuel assemblies belonging to a second division of fuel assemblies only if the first division of fuel assemblies has been tested.