Patent Number: 046506373
Section: abstract

A method and apparatus for identifying those fuel rods (32) of a multiple-rod nuclear fuel assembly (30) which contain leaks, are described. The longitudinal position of the leak in the fuel assembly is determined by moving a first test probe (62) longitudinally along the length of the fuel assembly while drawing coolant surrounding the fuel rods into the probe and sampling the radioactive product content of such coolant. The exact position of the leaking fuel rod is then determined by using second (63) and third (64) test probes to logically subdivide the fuel rods of the fuel assembly at such longitudinal position into successively smaller groups while sampling the radioactive content of coolant surrounding the smaller rod groups, until the leaking fuel rod is isolated. A test probe configuration (60) for subdividing and isolating selective groups of the fuel rods for the coolant sampling is disclosed. The test probe assembly includes a plurality of test probes (62, 63, 64) each having a pair of opposed baffle members (62.1, 62.2) secured at one end to a collector (62.3) to define a volumetric test zone (T). The baffles are configured for slidable insertion between adjacent rows of the fuel rods. Means (68, 69) for drawing liquid coolant into the collector, and probe positioning means (66, 67) are also disclosed.