US 4,749,543 A · Axially shaped channel and integral flow trippers

Abstract

An improved channel is disclosed which has a reduced average thickness in its upper portion. The lesser average thickness corresponds to a lower pressure difference acting on the channel sides, over the upper portion of the channel. The reduction in average thickness is accomplished by cutting flow trippers into the inner surface of the channel walls and/or cutting grooves into the outer surface of the channel. The axial variation of channel average thickness increases water volume adjacent to the upper part of the channel to provide increased neutron moderation, to minimize the steam void reactivity coefficient, and to provide a greater cold shutdown margin. The material removed to produce the flow trippers increases the cross-sectional area inside the channel and reduces pressure drop in the upper portion of the channel. The flow trippers divert water flowing on the channel walls to the fuel rods adjacent to the channel walls, permitting higher reactor power operation. The flow trippers also permit operation at lower flow rates.

Claims10

Dependent claims

A fuel assembly comprising a plurality of fuel rods positioned in spaced array by upper and lower tie-plates, an open ended flow channel surrounding said array for conducting coolant upward between a lower support plate having coolant communicated thereto to an upper support grid having a steam/water outlet communicated thereto, said flow channel surrounding said array for conducting coolant about said fuel rods;

said open ended channel having a polygon shaped cross section with said channel constituting a closed conduit with flat side sections connected at corners to form said enclosed conduit;
means separate from said channel for connecting said upper and lower tie-plates together and maintaining said fuel rods in spaced array independent of said flow channel, the improvement in said flow channel comprising tapered side walls, said tapered side walls extending from an average thick cross section adjacent said lower support plate to an average thin cross section adjacent said upper core grid whereby said channel is reduced in thickness adjacent said upper core grid to correspond with the reduced pressure adjacent said upper core grid.

Dependencies are inferred from the claim text.

Axially shaped channel and integral flow trippers

Life of this patent

Axially shaped channel and integral flow trippers

Life of this patent

Abstract

Claims10