The very interesting PBS Nova episode about this incident was repeated a couple of weeks ago. Although the allies had no way of knowing it, the Germans had apparently already abandoned the bomb project, and there wasn't really that much heavy water available anyhow. The barrel that was recovered was of a very low concentration. The barrels that had higher concentrations were only partly full, floated, and were recovered by the Germans anyhow.
Originally Posted by TrAI
Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.