Debris filtering skirt arrangement for nuclear fuel assembly bottom nozzle and bottom nozzle including same

A fuel assembly configured for selective engagement with a lower core plate of a nuclear reactor, the fuel assembly comprising:

• a bottom nozzle comprising a flow plate, wherein the flow plate comprises a plurality of flow passages through which a coolant can traverse towards a core region of the nuclear reactor;
• and
• a debris filtering skirt comprising a base portion comprising a plurality of holes and a bottom edge, wherein the base portion defines an opening between the bottom edge and the reactor vessel lower core plate, wherein the opening comprises a dimension configured to position the bottom edge a predetermined distance away from the lower core plate when the fuel assembly is selectively engaged with the lower core plate, and wherein at least one hole of the plurality of holes comprises a dimension determined based, at least in part, on a predetermined size of debris capable of traversing through the at least one hole;
• wherein the dimension of the opening and the dimension of the at least one hole is determined based, at least in part, on a predetermined loss coefficient of the bottom nozzle.

A method of manufacturing a debris filtering skirt of a bottom nozzle configured for selective engagement with a reactor vessel lower core plate of a nuclear reactor, the method comprising:

• determining a maximum loss coefficient of the bottom nozzle;
• determining a minimum filtration capability of the debris filtering skirt;
• calculating a first dimension based at least in part on the maximum loss coefficient and the minimum filtration capability;
• calculating a second dimension based at least in part on the maximum loss coefficient;
• producing the bottom nozzle;
• producing the debris filtering skirt comprising a bottom edge and a plurality of sides;
• defining a plurality of holes in at least one side of the plurality of sides of the debris filtering skirt, wherein at least one hole of the plurality of holes comprises the first dimension;
• defining an opening within the debris filtering skirt, wherein the opening comprises the second dimension such that, when the bottom nozzle is selectively coupled to the lower core plate, the bottom edge of debris filtering skirt is positioned the second dimension away from a surface of the lower core plate.