Patent Number: 
Section: claims

1. A method of controlling fluid flow in a conduit, the method comprising:installing a plurality of plates in a flow path of the conduit, wherein each plate of the plurality of plates are configured to removably secure in the conduit and are positionable in place of each other in the conduit, and wherein the installing includes,sliding a first plate of the plurality of plates into the flow path, andsliding a second plate of the plurality of plates into the flow path with the first plate already in the flow path such that the flow path divides into portions that pass through only one of the first plate and the second plate, wherein the first and the second plates have different flow surfaces from each other, and wherein the sliding the second plate includes abutting the second plate directly against an edge of the first plate in the flow path. 2. The method of claim 1, wherein the installing includes sliding the first and the second plate to separate lengthwise positioning in a retainer in the conduit. 3. The method of claim 2, further comprising:installing the plurality of plates in the conduit to fill the conduit lengthwise with the plates, wherein all the plurality of plates have a same width and span the conduit so that the flow path in the conduit only passes through openings within the plates. 4. The method of claim 2, further comprising:joining the retainer to an internal surface of the conduit prior to the installings. 5. The method of claim 4, wherein the conduit is an upper manifold of a PCCS system in a nuclear power plant, wherein the retainer includes two grooved ledges on opposite internal surfaces of the upper manifold, and wherein the plurality of plates includes a chevron plate in a center of the upper manifold. 6. The method of claim 1, further comprising:removing an end plate from the conduit to access the flow path prior to the installing; andreaffixing the end plate to the conduit after the installing. 7. The method of claim 6, wherein the conduit is a manifold having a longest dimension in a first direction, wherein the end plate seals the conduit at an end in the longest dimension, wherein the sliding the first plate and the sliding the second plate slides the first and the second plates in the first direction, and wherein the flow path is perpendicular to the first direction. 8. The method of claim 1, wherein the sliding the first plate slides the first plate in a plane of the largest surface of the first plate and the second plate, and wherein the sliding the second plate slides the second plate in the plane. 9. The method of claim 8, wherein the plane is perpendicular to the flow path, and wherein all of the plurality of plates directly touch another plate of the plurality and the conduit. 10. The method of claim 1, wherein the plurality of plates includes at least five different plates that all have largest faces in a same plane. 11. A method of controlling fluid flow in a system including a conduit having, an upper manifold configured to receive fluid flow in a nuclear power plant through a fluid inlet, a lower manifold configured to receive a cooled and condensed fluid flow, a plurality of tubes providing a flow path between the upper and lower manifolds and configured to be surrounded by a heat sink to convert the fluid flow into the cooled and condensed fluid flow in the plurality of tubes, a retainer configured to rigidly join to an internal wall of the conduit, and a plurality of plates all configured to removably and directly join to the retainer, the plurality of plates being positionable in place of each other in the retainer, the plurality of plates including a chevron plate positioned in a center of the upper manifold, and the plurality of plates including at least one of a solid flat plate, a perforated flat plate, and a spacing plate, the method comprising:installing a first plate of the plurality of plates in a flow path in the conduit; andinstalling a second plate of the plurality of plates in the flow path in the conduit, wherein the first plate and the second plate have different fluid flow characteristics. 12. The method of claim 11, wherein the installing includes sliding the first and the second plate to separate lengthwise positioning in the retainer. 13. The method of claim 12, further comprising:installing a plurality of plates in the conduit to fill the conduit lengthwise with the plates, wherein all the first, the second, and the plurality of plates have a same width and span the conduit so that the flow path only passes through openings within the plates. 14. The method of claim 11, wherein the retainer includes two grooved ledges on opposite internal surfaces of the upper manifold. 15. The method of claim 11, further comprising:removing an end plate from the upper manifold to access the flow path prior to the installings; andreaffixing the end plate to the upper manifold after the installings. 16. The method of claim 15, wherein the upper manifold has a longest dimension in a first direction, wherein the end plate seals the upper manifold at an end in the longest dimension, wherein the installing the first plate and the installing the second plate slides the first and the second plates in the first direction, and wherein the flow path is perpendicular to the first direction. 17. The method of claim 15, wherein the installing the second plate includes abutting the second plate directly against an edge of the first plate in the flow path. 18. The method of claim 12, wherein the sliding the first plate slides the first plate in a plane of the largest surface of the first plate and the second plate, and wherein the sliding the second plate slides the second plate in the plane. 19. The method of claim 18, wherein the plane is perpendicular to the flow path, and wherein all of the plurality of plates directly touch another plate of the plurality and the conduit.