Lower pipe seat and bottom device

Abstract

The invention provides a lower pipe seat of a light water reactor nuclear fuel component. The lower pipe seat comprises a connecting plate, wherein the connecting plate comprises an up-and-down through side frame, a plurality of first main ribs which are arranged at intervals in parallel, a plurality of second main ribs which are arranged at intervals in parallel and a plurality of auxiliary ribs, wherein the first main ribs and the second main ribs are arranged in a staggered manner, a plurality of up-and-down through regions are divided in the side frame, the plurality of the auxiliary ribs are respectively arranged in the plurality of the regions, and a plurality of up-and-down through water flowing holes which are uniform in size are divided in the plurality of the regions. The invention further provides a bottom device of the light water reactor nuclear fuel component, which comprises the lower pipe seat. As the lower pipe seat disclosed by the invention adopts the design of the main ribs and the auxiliary ribs and the water flowing holes are uniform in the size, foreign matters in the larger size can be blocked; and simultaneously, the lower pipe seat is further conductive to blocking the violent disturbance of cooling water which is ejected by a lower reactor core plate, and can enable the transverse maximum flow rate and the axial maximum flow rate of the cooling water to achieve better desired values, enable the speed distribution to be more uniform and reduce the vibration at the lower end of the fuel component.

Description

technical field [0001] The invention relates to a light water reactor, in particular to a lower pipe seat and a bottom device of a light water reactor nuclear fuel assembly. Background technique [0002] A light water reactor consists of a core consisting of a number of prismatic fuel assemblies arranged side by side in a vertical position. The fuel assembly comprises a framework consisting of longitudinal ducts and grids and secured by two header means, within which fuel rods are seated. One of the fuel assembly's two header assemblies, known as the bottom assembly, sits on the lower core plate, which has holes drilled at the location of each fuel assembly to allow the reactor's cooling water to flow vertically upwards through the core. With long-term operation, some large foreign objects such as screws, nuts, and metal cuttings are easily mixed into the cooling water. If these foreign objects enter the fuel assembly, they will easily cause abrasion to the fuel rods drive...

AI Technical Summary

Problems solved by technology

However, the rib structure of the lower pipe seat of the bottom device is mainly used for strengthening, and its flow hole area is large and unevenly distributed. Large foreign objects (such as screws, nuts, metal cutting objects) in the cooling water etc.) can pass through the water hole and hit the anti-foreign matter plate at high speed. At this time, the anti-foreign matter plate has the risk of being scratched

Moreover, the above-mentioned structural characteristics of the bottom device make the maximum axial flow velocity upstream of the end grid of the nuclear fuel assembly too large, while the minimum axial flow velocity is too small, that is, the flow uniformity is poor, which easily causes the fuel rods to vibrate, and further It is easy to cause damage to the fuel rods; moreover, the bottom device will also cause the maximum lateral flow velocity upstream of the end grid of the nuclear fuel assembly to be too large, that is, the flow disturbance characteristics are poor, and it is also easy to cause the fuel rods to vibrate

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