Belgium’s nuclear research centre SCK CEN has commissioned a second pressurised water capsule (PWC) facility (PWC-8) that has doubled its capacity to test new design nuclear fuel rods. “In technical terms, this type of test is known as a transient test. It involves simulating a sudden power increase of a reactor so that we can identify what increase causes the cladding – the first physical barrier containing the uranium fuel – to fail,” explained project leader Brian Boer. In the reactor cycle that has now been completed, doubled capacity made it possible to carry out two transient tests one after the other.
Boer said such tests are indispensable when ensuring the safety of nuclear power plants. They probe the safety margins of newly developed fuels and form the final piece in a licence file. “In Europe, we are the only organisation that is allowed to perform these necessary tests,” he noted. So supply is limited, but demand remains high.
“When we installed our PWC-7 in 2020, we were already noticing an increasing demand for more testing capacity. At the time, we were already talking about building an identical copy of it,” said PWC operations manager Miquel Torres.
Now that it has two installations at its disposal, SCK CEN has not only doubled its capacity, but if a fuel rod fails, the nuclear research centre is now also able to schedule further tests more quickly. “When the cladding fails, we detect activity in the water in the PWC plant, Torres explained. “The fission products released are then correctly and safely collected. Before starting another test, we must thoroughly clean the capsule and its water circuit outside the core. That cleaning process takes time because no residual contamination from the previous experiment is allowed to remain. That way, we can avoid the possibility of traces of previous fission products affecting the results of a subsequent test. Thanks to our second PWC installation, we already have a ‘clean’ capsule, which means that we can proceed with the scheduled tests.”
