Investigation of water-logged spent fuel rods under dry storage conditions

The primary purpose of the present work was to determine how much releasable water is contained in breached spent fuel rods, the amount of water released during an exposure to vacuum and temperature, and the effects of the water on spent fuel rod integrity under dry storage conditions. The secondary objectives of this work were to determine the degree of water migration in a fuel rod and whether there are differences in this migration behavior between failed and unfailed rods, and between BWR and Pressurized Water Reactor (PWR) fuel rods. To achieve these objectives, two well-characterized BWR fuel rods containing reactor-induced breaches, and two unfailed fuel rods (1 BWR and 1 PWR) wer tested in the hot cell at a heating rate simulating the temperature rise in a storage cask during pump down and dryout operations. The moisture release from the fuel rods was determined by weight changes monitored on a moisture absorbent. This paper describes the results obtained. 2 refs., 14 figs., 3 tabs.