An ex-reactor test stimulating the charging of a tubular fuel element in a Zircaloy-2 process tube showed a problem of severe process tube scratching and galling may occur if metal sliding contact fuel element supports are used. Both the fuel supports and the process tubes were autoclaved. Although the conditions of this test were severe in that the sharp edges rather than a flat surface of the supports were in contact with the process tube, it pointed out the potential problem of galling by point on small area contact supports on heavy fuel elements. This difficulty had not been observed with the lighter tubular or cluster fuel elements used in KER irradiation. In addition to the loss of metal and thinning of the process tube after a number of charge-discharge operations, these scratches may lead to localized corrosion or act as points of stress concentration.

Experimental studies on continuous denitration performed in 321 Building resulted in the development of an agitated-through-type calciner. The performance of a paddle-agitated 4-in.-diameter by 44-in.-long reactor was sufficiently promising to warrant construction of a 16-in.-diameter by 8 ft.-long semi-plant scale model. This progress report summarizes the results of studies to date employing the semi-plant scale calciner.