Irradiation Creep in the Dounreay Fast Reactor

Abstract

HELICAL springs, mostly from batches used in a thermal reactor irradiation¹ and loaded in tension in strings of five, have been used to measure irradiation creep in three experiments in the Dounreay Fast Reactor (DFR). The specimens were immersed in sodium and creep deflexions were estimated from pre and post-irradiation X-radiographs of the rigs. The deflexion of each spring was limited by design to about 15 mm. One nickel specimen, the uppermost in the second rig (Table 1) and of larger coil radius than the rest, was cut from a spring supplied by Dr R. V. Hesketh from the batch he used in his thermal irradiation². For this spring a strain of 10⁻⁴ corresponded to a deflexion of 2.54 mm, twice that for the others, the comparison being for twenty-five active turns.