Repair job complete at Angra 2 pool

18 August 2016

Brazil's fuel cycle company INB has celebrated the successful underwater repair of a damaged fuel rod canister in the storage pool of Angra 2.

If the integrity of fuel rods in a light water reactor such as Angra 2 is reduced they sometimes begin to release radioactive elements such as iodine-131 into the coolant water. This has no effect on the performance or safety of the plant, but is nevertheless monitored by operators. On the next refuelling outage the damaged elements are removed from the reactor, placed in a sealed canister and stored alongside other used fuel elements in the used fuel pool.

During this procedure at Angra 2 in April 2014 the canister itself suffered damage while being manoeuvred. Rather than purchase a new container and transfer the rods, plant owner Eletronuclear and Industriás Nucleares do Brasil (INB) launched a project to repair the canister in situ, some 12 metres underwater and with used nuclear fuel elements inside it as well as nearby.

Planning the job took two years for INB and Eletronuclear, based on the technical drawings of the canister, Eletronuclear's capabilities within its power plant and INB's machining skills. After a test run at an INB facility, the team performed the repair "with a high level of technical sophistication and pinpoint accuracy," said Rogger Faria, the mechanical engineer at INB who led the project.

INB said the success has led to a partnership for a commercial service offering ultrasound inspection of fuel elements in nuclear power plant used fuel pools and company superintendent Reinaldo Gonzaga said the experience opens the opportunity for INB to become qualified in fuel element repair.

Researched and written
by World Nuclear News