NRG Announces New Technique For Measuring Nuclear Fuel Creep In Reactors

26 Sep (NucNet): Netherlands-based NRG has become the first organisation to develop a technique to measure the deformation of nuclear fuel at the high temperatures and radiation levels experienced during irradiation in a nuclear reactor, the company said in a statement on 26 September 2017. Data from the technique has advanced understanding of how nuclear fuel behaves in nuclear power stations, NRG said. The technique will play an important part in research into – and the development of – safer and better nuclear fuels. The technique monitors “nuclear fuel creep”, which occurs when uranium oxide pellets (UO21) used in nuclear fuel rods are permanently deformed as a result of the high pressure, temperature and radiation level in the reactor. NRG said it had developed the technique in its High Flux Reactor (HFR) in Petten, in which the deformation of several samples was monitored simultaneously under operational conditions. Researchers identified dimensional changes in samples of metal and ceramics to an accuracy smaller than one micrometre during irradiation at temperatures between 500 and 1,200 degrees Celsius. NRG said this was a “tremendous challenge” and it had worked for two years to develop the technique and prove its feasibility. The next step is to measure the deformation of actual nuclear fuel, which is scheduled for 2018. “We now know that the instrument and the measurement principle work and how we can determine the creep of the nuclear fuel at high radiation levels and at high temperatures,” said Steven Knol, a nuclear fuel expert at NRG. NRG said obtaining better data about nuclear fuel creep is important for understanding nuclear fuel’s behaviour under normal and accident conditions. The new monitoring technique can also be used in the research into accident tolerant fuels (ATFs) and mixed-oxide (MOX) fuels.