A fuel assembly

A fuel assembly configured to be positioned in a nuclear water reactor, wherein the fuel assembly comprises:

• an upstream end,
• a downstream end,
• a flow interspace between the upstream end and the downstream end,
• a plurality of fuel rods provided in the flow interspace between the upstream end and the downstream end, the flow interspace being configured to permit a flow of coolant through the fuel assembly along a flow direction from the upstream end to the downstream end in contact with the fuel rods,
• a filter device configured to catch debris particles in the flow of coolant,
• wherein the filter device comprises a first filter zone provided in the flow of coolant between the upstream end and the fuel rods, and a second filter zone,
• wherein the first filter zone comprises a plurality of passages arranged to guide at least a part of the flow of coolant to pass the first filter zone through the passages towards the downstream end, wherein the second filter zone comprises a plurality of passages arranged to guide at most a part of the flow of coolant to pass the second filter zone through the passages towards the downstream end, and
• wherein the first filter zone has a first filtering efficiency and the second filter zone has a second filtering efficiency,
• wherein the second filtering efficiency is higher than the first filtering efficiency.