[en] A fuel pin irradiated to about 3400 MWd/tU from the Halden reactor has been investigated by a measurement of the production of fast neutrons in a thermal column and by pile oscillator technique in the central channel of the reactor R1. Calibration was made by using samples with different U 235 enrichments. The thermal column experiment gives the quantity ave(νΣ_f) (average in the thermal column spectrum) for the Halden sample. Σ_f is the macroscopic fission cross section and ν is the number of fast neutrons produced per fission. The result of the oscillator measurements is a value of ave(Σ_a) - w ave(Σ_f) (average in the central channel spectrum) for the irradiated sample, w is the importance of a fast neutron relative to a thermal one and ave(Σ_a) is the macroscopic absorption cross section. The results from both the experiments have been compared with values calculated by the REBUS code and the agreement was good