The results of experiments are presented on testing the separation of uranium from U-Be nuclear fuel solutions by extraction. It was shown that the degree of uranium extraction using a solution of 10 vol% TBP in RED-3 from a nitric acid solution of this fuel is 98.7%. Transfer of uranium into the re-extract is 97.9%. More than 99.99 % of beryllium goes into the extraction raffinate intended for further vitrification. The results of the study were used for the preparation of technological regulations on reprocessing of U-Be SNF at the RT-1 plant of the Mayak Production Association. The industrial-scale reprocessing of this fuel confirmed the values determined in the study.