A fuel-element assembly from the first loading of the OMRE was examined in detail after experiencing an average uranium burnup of between 1 and 2 at.%. The rate of decay heat generation was evaluated by temperature monitoring of the shipping-cask coolant. Temperatures of the fuel-element-box assembly and the fuel plates were measured with thermocouples and tempilstiks. Structurally, the fuel-element assembly was affected very little by either radiation or the organic coolant-moderator. Although there was some distortion in the side and end plates of the assembly, the coolant channels between the fuel plates were free from major fouling and obstructions. The channel cross sections were reduced at specific points less than 5 per cent. The plates studied were subjected to complete gamma scanning. Specimens removed from selected areas of the scanned plates were radiochemically analyzed for burnup and the results correlated with the gamma-scan data. Burnup profiles were constructed for each of the scanned plates. The gamma-scan data were also utilized to determine the average plate burnup. (auth)