[en] The irradiation was carried out in the helium-loop in the central channel of FR 2. Pins, each with an active length of 150 mm, were irradiated for 3 or 15 days. The whole series consisted of 8 specimens. The plutonium content was some 15 wt percent (rest natural uranium) and the density of pellets was some 86 percent T.D. The cladding was an austenitic steel (No. 1.4988). The O.D. of cladding was 10.0 mm with a wall thickness of 0.55 mm. Besides the thermocouples on the cladding, the specimen possessed a central thermocouple. The rod power was some 1100 W/cm, the outer cladding temperature 500⁰C, and the burnup only some 0.2 percent. Three pins melted near the central thermocouple by a peritectic reaction between thermocouples, cladding, and fuel. Results of non-destructive and destructive post irradiation examinations are represented. (auth)